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Y2    @` @ ` @ @@@`@@@@@` `@``````` @` @` @` @`@ @@@`@@@@@ @ @@ @` @ @ @ @ @@@ @@@`@@@@@@@@@@`@ `@@`@``@`@`@`@`@@ @@@`@@@@@@ @@@`@@@@@@ @@@`@@@@@@ @@@`@@@@@ @` @ ` @ @@@`@@@@@` `@``````` @` @`ࠀ @` @` @` @ ` @ @@@`@@@@@` `@```````׀ @` @` @` @`452C ( ]]]]9ShSh BhBzBzBzzhzzzzh9 zzzSzzzhhS99  Szz'9 z'zhz Sz'z 9']]]]]4+lpfT  n   @` @ ` @ @@@`@@@@@` `@``````` @` @` @` @`@ @@@`@@@@@ @ @@ @` @ @ @ @ @@@ @@@`@@@@@@@@@@`@ `@@`@``@`@`@`@`@@ @@@`@@@@@@ @@@`@@@@@@ @@@`@@@@@@ @@@`@@@@@ @` @ ` @ @@@`@@@@@` `@``````` @` @`ࠀ @` @` @` @ ` @ @@@`@@@@@` `@```````׀ @` @` @` @`45nC (WWWW0ShSh9h9z9z9zzhzz zz h9 zz z Szz z hhS 99 Szz*9 z* zhz Sz* z 9*WWW4+lpfT  n   @` @ ` @ @@@`@@@@@` `@``````` @` @` @` @`@ @@@`@@@@@ @ @@ @` @ @ @ @ @@@ @@@`@@@@@@@@@@`@ `@@`@``@`@`@`@`@@ @@@`@@@@@@ @@@`@@@@@@ @@@`@@@@@@ @@@`@@@@@ @` @ ` @ @@@`@@@@@` `@``````` @` @`ࠀ @` @` @` @ ` @ @@@`@@@@@` `@```````׀ @` @` @` @`45nC (WWWW0ShSh9h9z9z9zzhzz zz h9 zz z Szz z hhS 99 Szz*9 z* zhz Sz* z 9*WWW$l!KLRayfract online help (lCopyright Intelligent Resources Inc. 1996-2007. All rights reserved. See rayfract.com for tutorials etc.BrowseButtons()ZmainRayfract online helpZspreadsRayfract receiver spreadsHaZasciformASCII format dialogaZprocessRayfract processing sequenceaZfctkeysRayfract keyboard mappingaZcntxthlpRayfract help)  RAYFRACT.CNT , = I1ՄI{Introduction2 {# IntroductionIAC T RAYFRACT is a Windows 32-bit software package, suited for processing of seismic profiles with low, medium or high coverage. We support the interpretation of both P-wave and S-wave seismic refraction and borehole surveys. First breaks are imported via ASCII, or picked semi-automatically or interactively. Traveltimes may be mapped to refractors manually or semi-automatically, based on apparent (instantaneous) CMP velocities measured and typical refractor velocity intervals, as specified by the interpreter. Finally, traveltime data is processed on a per refractor basis, according to three different interpretation methods: CMP intercept time refraction (Gebrande and Miller 1985; Rhl 1995), Plus-Minus (Hagedoorn 1959) and Wavefront (Brckl 1987; Jones and Jovanovich 1985). Plus-Minus and Wavefront are based on traveltime field regression (Brckl 1987). Wavefront considers local emerging wavefront angles. A critically refracted ray is represented by first break and emergence angle at a receiver. Each reverse ray is combined with a matching forward ray, such that both rays surface from an approximated common refractor location. {#1 0cYou may consider our Wavefront method as an optimized version of the GRM (Generalized Reciprocal Method) algorithm as described by Palmer (Palmer, 1980). Instead of assuming a user-specified constant receiver separation ("XY distance", "Optimum XY value") all along the profile, the Wavefront method automatically estimates the local receiver separation at each receiver station, from local forward and reverse wavefront emergence angles. So the receiver separation obtained may vary laterally along the profile considerably. This means that the Wavefront method optimally images refractors with high relief (i.e. strongly undulating refractors, with pronounced troughs and humps).VAy[ ]zOTStarting with version 1.30, as released in December 1998, our software now also implements the Delta-t-V method as described by (Gebrande and Miller 1985). This pseudo-2D turning ray inversion method delivers continuous 1D depth vs. velocity profiles for all profile stations. The profiles are written to an ASCII file which may be processed conveniently with Golden Software's Surfer etc., to produce station nr. vs. depth velocity maps / contour plots with velocity isolines. The method handles real life geological settings such as vertical velocity gradients inside layers / linear increasing of velocity with depth / velocity inversions / pinchouts and outcrops / faults and local velocity anomalies, without requiring user-specified a priori model constraints. Especially, it does not require the user to map traveltimes to refractors at all. Importing seismic data and complementing it with geometry information / traveltime picks is all that is needed. Delta-t-V models show you the relative velocity distribution in the subsurface. Systematic velocity increases (at the top of the basement) and strong velocity anomalies such as low velocity zones, faults etc. will be visible in many situations. The absolute velocity values obtained may have an error of up to about 15 or 20 percent or more, however. Especially, the absolute values, signatures and locations obtained for strong but narrow velocity anomalies may be distorted and should be taken with a grain of salt. Pseudo-2D Delta-t-V generates systematic imaging artefacts in case of strong lateral velocity variation in the near-surface overburden. Use our Smooth inversion method to virtually eliminate these artefacts in the initial model, and to obtain more reliable absolute velocity estimates.O#DU x Vs.FStarting with version 2.01, as released in OctobyD er 2000, RAYFRACT now supports improved quality control of depth-velocity models as obtained with our Delta-t-V method by forward modeling of wave propagation through these models. The forward modeling algorithm implemented for modeling of first breaks is the first-order Eikonal solver as described by Podvin/Lecomte (Lecomte 2000). It handles any geological setting such as vertical or lateral velocity gradients, sharp velocity changes (i.e. discontinuous velocity distribution, systematic changes at unit boundaries), strong velocity contrasts (of local velocity anomalies) and velocity inversions and runs very fast. Thanks to this powerful new quality control tool our Delta-t-V method does not require core drilling data any longer. Just check and if necessary tune the Delta-t-V parameters by comparing synthetic i.e. modeled traveltimes with traveltimes as measured and picked (as shown in the Shot breaks display). According to raytracing results from about 20 sample profiles, Delta-t-V does work for low coverage surveys (just 5 or 7 shots per receiver spread) as well. Default values for the Delta-t-V parameters as proposed by the software automatically will give good results in most cases. yG= HH>Starting with version 2.11, as released in February 2001, RAYFRACT now also supports the iterative refining of Delta-t-V output (or of Surfer .GRD velocity models as obtained with third party methods) with our new WET Wavepath Eikonal Traveltime tomography processing. See (Schuster 1993; Watanabe 1999). This highly sophisticated method supports extreme topography. Wave propagation is modeled in a physically meaningful way with wavepaths i.e. Fresnel volumes (also known as "fat rays"), based on our advanced first-order Eikonal solver as mentioned above. As a consequence velocity anomalies such as low velocity zones and faults may be imaged with higher contrast than with conventional ray tomography.BDhJE Xw Starting with version 2.34 as released in March 2002, WET processing allows the integration of uphole picks for seismic traces recorded by surface receivers for shots positioned at the bottom of deep shot holes (e.g. recorded by same receiver spreads as used for surface based shots).Starting with version 2.43 as released in April 2003, RAYFRACT now supports the fully automatic interpretation of 2D profiles with our Delta-t-V and WET inversion methods, including automated gridding, imaging and contouring of resulting tomograms with Golden Software Surfer.GxM1 0TStarting with version 2.51 as released in March 2004, RAYFRACT now implements a fail-safe "Smooth inversion" option, for fully automated determination of a 1D gradient initial model and subsequent refinement with WET tomography processing. A smooth initial 1D gradient model is determined automatically directly from the traveltime data, by averaging Delta-t-V method 1D velocity-depth profiles along the seismic line. This procedure delivers reliable smoothed models even in case of velocity inversions. The 1D initial model guarantees that Delta-t-V artefacts (occurring e.g. in situations of strong refractor curvature / strong lateral velocity variation) are virtually eliminated from the interpretation at an early stage.hJ`G \+H3۲For detailed and up-to-date information about features of version 2.61 and later versions of our software seehttp://rayfract.com/help/release_notes.pdf. Version 2.62 of our RAYFRACT software, as released in August 2005, features improved Delta-t-V internal static corrections. During a second pass of statics computation, ray emergence angles are now regarded. See the German language thesis of Roland A. Winkelmann, as available at amazon.de, ISBN 3932965043 , chapter 3.3. Also, we now offer an additional Delta-t-V setting Suppress velocity artefacts to suppxM` ress the generation of processing artefacts, i.e. unrealistic velocity variation.xM~1 0XbVersion 2.71 of our RAYFRACT software, as released in December 2006, now supports modeling of constant-velocity layers in addition to constant velocity-gradient layers, with the XTV inversion method. This method has been published by Roland A. Winkelmann in his 1998 Ph.D. thesis (Winkelmann 1998), as done with Professor Helmut Gebrande in Munich. Professor Gebrande has described the foundations of CMP refraction theory, in (Gebrande and Miller, 1985) and (Gebrande 1986). See alsoX` 3 4http://edoc.ub.uni-muenchen.de/archive/00000222/01/Gawlas_Peter.pdf . Describes XTV inversion in chapter 3.2.2.4, page 43 ff.Version 2.73 of our RAYFRACT software as released in May 2007 has been adapted to work under Microsoft Windows Vista, in addition to 98 SE, NT, 2K and XP. Also, we now allow import of OPTIM LLC SeisOpt data files, with first breaks and source/receiver geometry. When importing Interpex GREMIX or OPTIM LLC SeisOpt files, dead traces missing from these files will be regenerated automatically when located in the active part of the specified receiver spread type.~"A P㦍AVersion 3.01 of our RAYFRACT software as released in September 2007 now supports crosshole survey interpretation, with our Smooth inversion method and a constant velocity initial model. Data needs to be formatted as Daryl Tweeton GeoTomCG input files. For instructions showing processing of a crosshole data set seehttp://rayfract.com/tutorials/igta13.pdf. Also, we now support import of Geometrics/OYO SeisImager PickWin and PlotRefa .VS formatted files.E g= H]8Version 3.05 released in January 2008 implements an optimized WET inversion algorithm. The wavepath width is determined for each trace individually, as a linear function of the picked traveltime. Uncheck WET Tomo|WET tomography Settings|Adjust wavepath width to use the same wavepath width for all traces. Also, we now use the undifferentiated Ricker wavelet for wavepath modeling and weighting per default, instead of its derivative. You can edit WET parameters with WET Tomo|Interactive WET tomography... ."zQ pRQW1Version 3.06 released in February 2008 scales WET smoothing filter height with depth below topography. This ensures better vertical resolution of the weathering layer. Also, the misfit between modeled and picked first breaks decreases faster during WET inversion (with fewer iterations). Disable this feature by unchecking WET Tomo|WET tomography Settings|Scale WET filter height.Version 3.09 released in May 2008 supports traveltime tomography of first breaks recorded for Walkaway VSP surveys, with a constant-velocity initial model. See http://rayfract.com/tutorials/walkaway.pdf . Also, we offer improved support for combination of uphole shots with surface refraction shots, both recorded with surface refraction receiver spreads. See http://rayfract.com/tutorials/coffey04.pdf . You may generate uphole shots from multi-offset VSP downhole shot surveys with our GeoTomCG .3DD export and import routines, as implemented for version 3.12.gE X]zOhttp://rayfract.com/tutorials/vsp.pdf. Before running Smooth inversion and WET tomography, we always check shot positions against traveltime curves. If these do not match, an error message is shown, prompting you to adjust first break picks or shot position. Also we do not allow our long-deprecated pseudo-2D Delta-t-V inversion any longer, to avoid publication of artefacts. Seehttp://rayfract.com/srt_evaluation.pdf , Fig. 1z € ]zOTwSystem requirementsTo use Rayfract, you will need the following :ZMA^ P:H"""""A 386 (or better) PC running Windows XP or Windows VistaVGA monitor or betterAt least 512 MBytes of RAM. For high coverage / long profiles and efficient WET tomography processing, 1'024 MB or more aA re recommended.At least 100 MBytes of available hard-disk space for the program files, including two sample profiles.Enough hard disk space for your profiles. One profile typically consumes about 20 MBytes of space, depending on data density, profile length and the amount of data generated by our tomography processing and Surfer gridding, smoothing, imaging and contouring of results.A C6 :P:Hl "Another 100 MBytes of free storage on your data disk containing Rayfract profile databases, to allow for storage of temporary traveltime grids for all profile receiver stations. These are generated during WET tomography, and will be deleted automatically once the tomography processing terminates. If you abort the processing with Windows task manager, Rayfract version 3.16 and later will delete these temporary grid files once you reopen the same profile. Earlier versions will not delete these grids if aborted.1A FF ZP:H " "Surfer version 8 or 9 for automatic plotting of tomograms. You may download a free print-disabled demo from http://www.goldensoftware.com. Enter e.g. state CA .After installation of the free Surfer demo, start it up once interactively via the Start menu. Then click on the splash screen. If you omit this step, Rayfract is not able to automatically call Surfer, and will just hang instead. After installing the full Surfer version, start it up and then register the software.,C5F( P:H5 FjF) "HSupport*5FF' P:HBjFG2 2!HIf you have any questions regarding our Rayfract software and processing of your data sets, please contact us via e-mail at sales@rayfract.com. Also, check out our web site at http://rayfract.com for tutorials, application samples, links to theoretical papers etc.(FG% HGK5 8 HTutorials as available for download on our web site http://rayfract.com cover our Smooth inversion method and our older Delta-t-V method and following WET tomographic inversion only. While we do offer more conventional time-to-depth conversion methods (such as our Wavefront method) which require the user to assign refractors to segments of shot sorted or CMP (Common MidPoint) sorted and stacked traveltime curves, we really do not believe in the unqualified importance and usefulness of the theoretical concept of a "refractor" (i.e. a layer with no vertical velocity variation inside it) any longer. Once you assign first breaks to refractors you just force a subjective model on the data at an early processing stage and may get large errors (regarding refractor depths and velocities) in many situations later on, especially if subsurface seismic velocity increases gradually with depth.(GK% HfKxN2 2HThe identification of geological units / stratigraphic layers should be done once you have obtained the final tomogram only. The interpreter needs to realize that the tomogram shows the "in situ" subsurface seismic velocity. I.e. not just the material velocity component but also the stress field induced component : increasing overburden pressure with burial depth results in smaller sediment pores and less fractured rock. Stress magnitude variation at folds and faults may have similar local effects i.e. cause a systematic variation of seismic velocity (R. J. Twiss and E. M. Moores 1992 : pp. 429-431).(KN% H`xN8, &HAlso, mechanical and chemical weathering cause the rock quality and seismic velocity to decrease the closer the rock or sediment unit is to the surface. In other words, rock quality and seismic velocity tend to increase with increasing burial depth. See B. Murck 2001 : chapter 6 Weathering and Erosion : N8 joints, exfoliation and frost wedging etc.(N`% H98& 'HFor identification of stratigraphic units this stress and weathering induced velocity component needs to be "subtracted" from the subsurface velocity distribution as imaged. You then obtain the estimated material velocity component and may correlate that velocity with geological units as known to exist in the area i.e. from a geological map or core drilling. Of course it is very difficult to mathematically formalize this "subtraction" i.e. separation of the velocity components. It needs to be done mentally by the observer.(`% H(% H(% H4E% HBibliography(m% HE) HM. Ali Ak 1990. An analytical raypath approach to the refraction wavefront method. Geophysical Prospecting, volume 38, pp. 971-982.(mE% H/ ,?HBarton P. and Barker N. 2003. Velocity imaging by tau-p transformation of refracted seismic traveltimes. Geophysical Prospecting, volume 51, pp. 195-203.(E;% H) HE. Brueckl 1987. The Interpretation of Traveltime Fields in Refraction Seismology. Geophysical Prospecting, volume 35, pp. 973-992.(;% Hۆ) ?HJ. B. Diebold and P. L. Stoffa 1981. The traveltime equation, tau-p mapping, and inversion of common midpoint data. SEG Geophysics, volume 46, pp. 238-254.(% HۆŇ) 3HW. Frei 1995. Refined field static corrections in near-surface reflection profiling across rugged terrain. The Leading Edge, April 1995, pp. 259-262.(% H=Ň*) )HGawlas, Peter Florian 2001 Ph. D. Thesis. Mglichkeiten eines DMO-Prozesses in der CMP-Refraktionsseismik. LMU Munich: Faculty of Geosciences. See http://edoc.ub.uni-muenchen.de/archive/00000222/01/Gawlas_Peter.pdf . Describes XTV inversion in chapter 3.2.2.4, page 43 ff.(R% H*=, &HH. Gebrande 1986. CMP-Refraktionsseismik. Paper presented (in German) at MintropSeminar / Uni-Kontakt Ruhr-Universitaet Bochum, Expanded abstract "Seismik auf neuen Wegen", pp. 191-205.(Re% H=J, &sHH. Gebrande and H. Miller 1985. Refraktionsseismik (in German). In: F. Bender (Editor), Angewandte Geowissenschaften II. Ferdinand Enke, Stuttgart; pp. 226-260. ISBN 3-432-91021-5.(er% HJ]) HBruce S. Gibson, Mark E. Odegard and George H. Sutton 1979. Nonlinear least-squares inversion of traveltime data for a linear velocity-depth relationship. Geophysics, volume 44, pp. 185-194.(r% H]:) HJ. G. Hagedoorn 1959. The Plus-Minus Method of Interpreting Seismic Refraction Sections. Geophysical Prospecting, volume 7, pp. 158-182.(b% H: ) HGlyn M. Jones and D. B. Jovanovich 1985. A ray inversion method for refraction analysis. Geophysics, volume 50, pp. 1701-1720.(b5% H () HI. Lecomte, H. Gjoystdal, A. Dahle and O.C. Pedersen 2000. Improving modeling and inversion in refraction seismics with a first-order Eikonal solver. Geophysical Prospecting, volume 48, pp. 437-454.(5P% Hr( ( HTak Ming Leung 1995. Examination of the optimum XY value by ray tracing. Geophysics, volume 60, pp. 1151-1156.P  (P4% H ) HTak Ming Leung 2003. Controls of traveltime data and problems of the generalized reciprocal method. Geophysics, volume 68, pp. 1626-1632.(4% Hi( HB. Murck 2001. Geology. A Self-Teaching Guide. John Wiley & Sons, Inc., New York. ISBN 0-471-38590-5.(% H) 9HD. Palmer 1980. The Generalized Reciprocal Method Of Seismic Refraction Interpretation. Society of Exploration Geophysicists, Tulsa. ISBN 0-931830-14-1.(% H) HPascal Podvin and Isabelle Lecomte 1991. Finite difference computation of traveltimes in very contrasted velocity models: a massively parallel approach and its associated tools. Geophysical Journal International volume 105, pp. 271-284.(% H, &WHWilliam H. Press, Brian P. Flannery, Saul A. Teukolsky and William T. Vetterling 1986. Numerical Recipes. Cambridge University Press, Cambridge. ISBN 0-521-30811-9.(% H) HT. Ruehl 1995. Determination of shallow refractor properties by 3D-CMP refraction seismic techniques. First Break, volume 13, pp. 69-77.(% H) HGerard T. Schuster and Aksel Quintus-Bosz 1993. Wavepath eikonal traveltime inversion : Theory. Geophysics, volume 58, pp. 1314-1323.(% H0 .HHamdy H. Seisa 2007. Is the Optimum XY spacing of the Generalized Reciprocal Method (GRM) constant or variable? Paper presented at 67th Annual Meeting of the German Geophysical Society (DGG), Aachen, March 26-29 2007.4 6HHamdy H. Seisa 2010. Migration and interpretation of first arrival inflection points due to lateral variations. Near Surface Geophysics, Vol. 8, No. 1, pp. 55-63.Sheehan J.R., Doll W.E. and Mandell W.A. 2005a. An Evaluation of Methods and Available Software for Seismic Refraction Tomography. Journal of Environmental and Engineering Geophysics, volume 10, pp. 21-34. ISSN 1083-1363, Environmental and Engineering Geophysical Society. JEEG March 2005 issue.(% H) HSheehan J.R., Doll W.E., Watson D.B and Mandell W.A. 2005b. Application of Seismic Refraction Tomography to Karst Cavities. U.S. Geological Survey Scientific Investigations Report 2005-5160.(% Hi( HRobert J. Twiss and Eldridge M. Moores 1992. Structural Geology. W. H. Freeman and Company, New York.(% Hn) HToshiki Watanabe et al. 1999. Seismic traveltime tomography using Fresnel volume approach. SEG Houston 1999 Meeting, Expanded Abstracts.(% Hqn/( HD. J. White 1989. Two-dimensional seismic refraction tomography. Geophysical Journal, volume 97, pp. 223-245.(W% H/U) HRoland A. Winkelmann 1998 Ph. D. Thesis. Entwicklung und Anwendung eines Wellenfeldverfahrens zur Auswertung von CMP-sortierten Refraktionseinsaetzen. Akademischer Verlag Muenchen, Munich. ISBN 3-932965-04-3.(W}% H(U% H(}% H>& 1HCopyright 1996-2010 Intelligent Resources Inc. All rights reserved. Rayfract is a registered trademark of Intelligent Resources Inc. in Canada and in Switzerland. All other product names as mentioned above are trademarks or registered trademarks of their respective holders.Kb1!xbInstallation and licensing@# :Installation and licensing b, &To install the Rayfract trial, please proceed as described below :For installation under Windows XP/VISTA please login as a user with "Administrator" rights. We support Microsoft Windows 32-bit versions only. Installation under 64-bit Windows versions should work for release 3.14 andlater versions, but has not yet been tested.Download the installable archive file RAYTRIAL.EXE from our web site http://rayfract.com, link "Trial" or directly from the associated URL A) 1address http://rayfract.com/trial/RAYTRIAL.EXE. Start up your web browser such as Mozilla Firefox or Microsoft Internet Explorer. Then specify one of these addresses in the URL address field on top of the browser window and hit Enter.Once you have downloaded RAYTRIAL.EXE, copy it into a temporary directory on the target hardware, e.g., C:\TEMP or C:\TMP.To start up the self-installing archive, run ...\RAYTRIAL.EXE from DOS or from Windows. Please substitute drive name and directory path into which you copied installation file RAYTRIAL.EXE for ... . Click on the Start button, and then select menu item Run, at the bottom of the menu. In the Run dialog that now appears, key in above command line, with correct drive and directory path (e.g. command line "C:\TEMP\RAYTRIAL.EXE").~Wm' Alternatively, specify the command line by clicking on your Browse/Search button, displayed at the bottom of the Run dialog. In the following, first navigate to the hard disk partition and directory containing your archive file RAYTRIAL.EXE. Then select this file by clicking on it. To execute the command line, press the ENTER/RETURN key, or click on the OK button.When the installation program displays the "Select Destination Directory" dialog, please change the drive or partition part of the directory only and leave the rest as \RAY32 root level directory as per default (e.g. D:\RAY32).D - (/To verify the positive outcome of above installation, please test starting up the Rayfract trial, as described below :To start up Rayfract, proceed as follows : Under Windows XP/VISTA double-click the desktop link with our icon.The Rayfract trial license will expire after 50 runs, or 30 days after having been run for the first time. It will run without the need for any initial registration. When you start up the trial, the licensing dialog will display. Just hit RETURN or click on the "Continue" button to continue.pGm! ) Once the license has expired on a given hardware, the free trial will not run any longer run on that hardware, even if you reinstall it as described above. You do have the option to rent or purchase a full functionality license : 4 month rental or unlimited license. For details see our web site http://rayfract.com/pricing.htm . You are welcome to pass on the trial installation file RAYTRIAL.EXE and this file TRIAL.TXT to any interested third party by any means as long as you do not charge them for the free trial and correctly display our Rayfract registered trademark. @3 4Here some more information concerning usage and functionality restrictions of your free trial Rayfract software :For a .PDF version of our Windows help file, please see http://rayfract.com/help/rayfract.pdf . This may be easier for viewing. Now you are ready to work with your license. You may first want to open the existing sample profiles LINE14 and PALMFIG4. Select the SEIS32.DBD in these subdirectories, to open the profile database. See "Starting up Rayfract and profile management" and later topics of the online help for details. You may start up the online help by selecting menu items in the rightmost Help menu. Be sure to read topic "System limitations" as w! @ell. There you will find a complete list of restrictions related to your trial license. Once you have opened profile LINE14, select Smooth invert|WET with 1D gradient initial model, to run our Smooth inversion.[! bC% We recommend to get acquainted with the processing capabilities of our Rayfract free trial by working through our EJEMPL3.pdf tutorial at http://rayfract.com/tutorials/EJEMPL3.pdf. For the full functionality Rayfract version, we recommend our SAGEEP09 short course tutorial, at http://rayfract.com/SAGEEP09.pdf. Also review the introductory "Tutorial" chapter of our manual at http://rayfract.com/help/manual.pdf . Or work through some tutorials at http://rayfract.com/tutorials/TUTORIAL.ZIP. The original data sets are available for download. Just click on the corresponding link in the tutorial.)@E' Please be aware that your trial license will handle up to ten shots per profile only ! We recommend to renumber the shots to 0 to 9 during import. Just edit the "Shot Number" field value in the "Import Shot" dialog. See the online help / topic "System limitations" for Rayfract versions with extended capabilities.To obtain more information on an edit field in a dialog, please click on that field with your left mouse key and then press function key F1. This will cause a help popup window to be displayed.`;bCG% wTo automatically grid and plot/display WET tomography output, you need to install Golden Software's Surfer version 8 or 9. You may download a free demo version at http://www.goldensoftware.com. Enter e.g. state CA for registration. You need to start up the free demo Surfer interactively via Start menu after (re)installing it. Then click on the splash screen, which covers the Surfer window. If you skip this step, Rayfract is not able to call Surfer automatically for plotting. For the full version, please startup Surfer and enter your license number first. EH+ $The WIBU-KEY copy protection device help file WkUseUS.CHM is available athttp://rayfract.com/help/wkuseus.chmIf your Rayfract license comes with a WIBU license management hardware device, please proceed as follows :,G}KY aP:H"".Z""Connect this device to your PC's parallel port (in between the port and the printer cable) or an USB port, as appropriate.Try to start up your Rayfract software (installed as described above). See topic Starting up Rayfract and profile management.If the Rayfract main menu is displayed without any preceding message box, please skip the following instructions, since your license has been activated already.If the software displays a message box mentioning the WIBU key copy protection device, please complete the following instructions.RHLN jP:H"""In order to activate/update/upgrade your license, you need to generate a context file for your WIBU-KEY, as lined out in the following steps.Select menu item "Control Panel" in your Windows XP/Vista Start menu.Double-click / open the WIBU-KEY icon_}KcM5 :PHl "Left-click on small icon to left of dialog title bar, select "Advanced Mode" if availableILNT vP:H""""Click on tab "WIBU-BOX Context" of the WIBU control applet now displayed.Click on text field "Remote Programming Context File".Enter an output context file name, e.g. "C:\TEMP\PROGRAM.RTC" into that field.Press the "apply" button.4cM- (HOnce you have produced the context file, please e-mail it to us (as binary e-mail attachment) so that we can activate/update your Rayfract license electronically. We will send you a license update file in order to do so, along with instructions on how to process the update file. If your reNntal license has expired and you wish to purchase a refill or unlimited license, we will require you to transfer the corresponding funds at such a time by bank wire, or fax us your credit card charge authorization details.CN/1d/gSystem limitations8g# *System limitations/[, &Your full functionality Rayfract license is a Windows 32-bit application (compiled with Microsoft Visual C++ 2005) and has the following inherent limitations regarding size of data sets etc. :Hg qP:H""""""handles processing of seismic lines with up to 1000 shots per profilesupports reading in of shots recorded with from 12 to 360 traces per shot recordsupports processing of seismic lines with up to 360'000 traces per profileminimum / maximum sample rate is one microsecond / one secondmaximum of 10,000 samples per tracesupports raytracing through Surfer grid files with up to 640'000 nodes per grid[> JP:H""assumes that trace data in .ASC ASCII files is sorted by increasing shot nr. and increasing receiver station (for same shot)all traces keyed to the same shot must be listed in the same .ASC ASCII file.SW |HƔ牀áܯ;To check whether you recorded enough shots for your profile, please review the Midpoint breaks display, by selecting Refractor|Midpoint breaks. Now map traces to refractors. If at a significant number of CMP's the traveltime curves start at an offset larger than 1 (i.e. are not connected to the top horizontal axis), subsequent inversion with Delta-t-V will become unstable because the weathering layer velocity is not constrained sufficiently with direct wave first breaks. You may improve the situation somewhat by increasing the CMP stack width (display and Delta-t-V) parameter. This amounts to widening the running average filter, for smoothing and interpolation of the weathering velocity. Velocities as determined below the shot points will be propagated to CMP's between the shot points, where no weathering velocity can be determined directly. But this may not help in all cases, especially if the weathering velocity varies laterally to a substantial degree (which may often be the case). U xH]zOH>COur Delta-t-V and WET tomography inversion methods require a shot spacing of 6 receiver stations or smaller. Optimally shot points will be positioned at each 3rd receiver station or closer. Also, please use a receiver spacing of 10 metres or less. Finally, we recommend to employ multiple overlapping receiver spreads with at least 24 channels per spread, per Rayfract profile. Please record 10 or more shots per receiver spread.\/w- (_H"Conventional" time-to-depth inversion methods (Wavefront, Plus-Minus, CMP Intercept-Time Refraction) will generally deliver more shallow refractor interpretations than the Delta-t-V method. This is because while the Delta-t-V method optimally models gradual velocity increase with depth inside one layer, these conventional methods assume that velocity inside one layer remains constant with increasing depth (below top surface of layer). As a consequence, raypath segments within one layer will be modeled as straight lines. Corresponding raypath segments within layers as modeled with the Delta-t-V method are arcs of a circle, determined by the vertical velocity gradient as modeled for each layer. These diving wave paths penetrate deeper into the subsurface than the conventional straight segment paths.BK dHH>]zOPlease note that we strongly recommend to refine subsurface wvelocity models as obtained with our Delta-t-V method with our new Wavepath Eikonal Traveltime WET tomography algorithm. This makes sense especially in situations of extreme topography (with absolute line elevation deviation from a horizontal or inclined flat plane along one receiver spread about equaling or exceeding the target depth being imaged). Please check topic Delta-t-V Inversion for more details on data acquisition requirements, such as coverage of profile receivers with first breaks etc.(w8% HM4 6HThe free limited functionality Rayfract trial license is a Windows 32-bit application as well (compiled with Microsoft Visual C++ 6.0 SP 5) and has these time and run limitations, as well as functional limitations :|8` ?P:H"""will expire after 30 days or after 50 runs, whichever happens firstsupports up to 10 shots per profile only. You will need to renumber your shots as shot number 0 to shot number 9.supports raytracing through Surfer grid files with up to 100'000 nodes per grid onlyMS tPHl " "does not support topography specificationdoes not support Crosshole survey Smooth inversion, with WET tomographyY+7 >P:H"does not support interactive Wavepath Eikonal Traveltime WET tomography processingI8 @PHl "does not support interactive pseudo-2D Delta-t-V and XTV inversion+= HIP:H""does not offer time-to-depth inversion methods Wavefront and CMP intercept-time refractiondoes not offer Midpoint breaks display and Offset breaks display~I 5 :PHl "Trace|Midpoint gather and Trace|Offset gather displays are disabledY {P:H""""does not support importing or specifying shot and receiver station coordinates. Assumes a straight line recorded on a flat topography.does not support importing or specifying lateral shot position offsets and shot hole depthsdoes not offer semi-automatic first break picking for shot sorted trace gathers, in the Shot breaks displaydoes not support printing of trace gathers/time sections/depth sections and velocity sectionsA \> J P:H""when importing or updating first breaks e.g. from Interpex Gremix .GRM files and OYO SEISREFA .ODT files, receiver elevations and shot hole depths will not be updateddoes not support exporting station and shot point coordinates to .COR and .SHO filesL%' KHThe trial license will expire whenever either it has been run 50 times, or after 30 days have passed. You may then purchase a 4 month rental or unlimited license. See our web site at http://rayfract.com/pricing.htm . Please contact us for further details, by e-mail to sales@rayfract.com .*\' P:HK1_ Strong refractor curvatureB_% :HStrong refractor curvature(% H_2 2HTFor true 2D WET tomography processing of profiles with strong basement undulations, we recommend to use our Smooth inversion method, based on a 1D gradient initial model. See e.g. our tutorials(% HU0% `Hhttp://rayfract.com/tutorials/broadepi.pdf ,V1T% bHhttp://rayfract.com/tutorials/depress.pdf andU0% `Hhttp://rayfract.com/tutorials/palmfig3.pdf .(T% H( % H , & HAs shown in the last tutorial, to prevent velocity artefacts in the imaged basement, your profile (overlapping receiver spreads) should extend over the edges of a basement depression (e.g. a steep valley). You may need to limit the maximum imaged basement velocity during inversion to a value estimated e.g. with our Wavefront method; see http://rayfract.com/tutorials/palmfig3.pdf .( % H( % H(4% H( \% HR4Y H]|A Ɣ{s.FFor conventional refraction interpretation of strong basement topography undulations, we recommend to prefer Wavefront and Plus-Minus interpretation results over CMP intercept time refraction interpretation. These interpretations may be based on semi-automatically mapping the first breaks to refractors in the Midpoint breaks display. Alternatively, you may want to manually map the first breaks to refractors for each shot sorted traveltime curve, in the Shot breaks display. For low coverage data, this is the only option available for mapping first breaks to refractors.(\/% H(W% H/g 8 >H ĝ؉Conventional CMP intercept time refraction fails to deliver accurate refractor depths and velocities at locations of strong refractor curvature, such as at the top of steep/narrow anticlines and at the bottom of steep/narrow synclines. In case of constantly dipping refractors, sorting the traces by Common Mid Point (CMP) basically eliminates intercept time and slope errors caused by refractor dip. This automatic error correction does not work in situations of strong refractor curvature, however. The two delays (relative to the horizontal layering case) of raypath segments traveling down to the refractor and coming up from the refractor null out each other symmetrically to the CMP for each ray mapped to the same CMP in case of constantly dipping refractors. This is not true with strong refractor curvature. In such situations, delays along the down going and the emerging raypath segments of each ray add to each other, instead, with increasing offset from the CMP.(W % Hrg 9 8 >HƔAs a consequence, expect apparent CMP velocities at the vertex of steep/narrow anticlines (refractor humps) to be too low by about ten to twenty percent. In analogy, expect apparent CMP velocities at the bottom of steep/narrow synclines (refractor troughs) to be too high by about the same percentage. Please note that semi-automatically mapping first breaks to refractors in the Midpoint breaks display will work even in such situations of strongly undulating refractors, however. I.e. laterally varying crossover distances can be determined reliably even in case of slightly wrong apparent CMP refractor velocities.( a % H`49  , &iHIf CMP basement velocities and CMP basement depth show a strong correlation for certain station numbers, there is a high chance that refractor synclines/anticlines are located below these station numbers. This location information may be useful when interpreting Wavefront and Plus-Minus depth sections.Da 1>NOptimize Windows XP9 ># ,Optimize Windows XP?B2 2Windows XP's default configuration is far from optimized. See e.g. PC Today August 2004 issue, page 70 and following pages for more details. Here we first focus on optimization of disk access :The Indexing Service in Windows XP indexes your files presumably to shorten the time needed to search your hard drive if you are looking for a specific file or part of a phrase inside a file. However>?B , the constant indexing of files actually slows down system performance considerably. Specifically, the hard disk is accessed almost all the time. You may witness this by observing the constant flashing of the hard disk drive diode or similar.To disable the Indexing Service permanently, click Start and Run. In the Run dialog box, type services.msc and press ENTER or click OK. In the Service window, scroll down and right-click the Indexing Service entry. Select Properties from the pop-up menu. Click Disabled from the Startup Type drop-down and click OK.>XE. *Furthermore, we recommend to disable file search indexing for Microsoft Office. Click Start and Control Panel. Now double-click the icon with the binocular and yellow flash graphics. Then select menu item "Stop indexing" or similar, in menu "Index".The startup time for Windows XP is acceptable if you use the Suspend / Resume mode, e.g. on a Toshiba portable. XP suspends when you close the lid and resumes when you reopen the lid of your portable. On a desktop PC, click Start and Turn Off Computer. Once the Turn off computer dialog appears, press down and hold the SHIFT key. Now click on the yellow "Hibernate" button. When you restart your PC, Windows XP will be restored almost instantly to the state it was before you turned it off.z?BH3 4If you note that Windows XP is running slower and slower, please shutdown XP via the Start menu "Turn Off Computer" item. Then start up XP again. If program execution under Windows XP is still slow and you are using the ZoneAlarm Internet Security Suite, please disable the ZoneAlarm OSFirewall component. Go into the main tab of "Program Control". Now click on the "Custom" button in the "Program Control" area. Uncheck "Enable OSFirewall" and click on "OK". If program execution and disk access is still too slow, you may want to stop a currently running ZoneAlarm virus scan, or shut down and uninstall/reinstall ZoneAlarm.XEI, &+We recommend to shut down all other non-essential applications before starting inversion with our WET method. Also, you may want to upgrade the amount of RAM installed in your work station or notebook computer, to the maximum amount allowed by your Windows version. Under Windows XP 32-bit, the maximum supported RAM amounts to 4 GBytes. For Microsoft Windows versions supporting more RAM, please seerLH8J& http://www.microsoft.com/whdc/system/platform/server/PAE/PAEmem.mspx .$I\L7 <To delete temporary Internet files and cookies, we recommend a file-cleaning program such as R-Wipe & Clean. Seehttp://www.r-tt.com . Run it about once a week. Select Tools|Settings... and select Wiping Algorithm Pseudo-random for acceptable performance. To streamline and clean up your Windows Registry on a weekly basis or so, we recommend CleanMyPC. Seehttp://www.registry-cleaner.net . Be sure to first make a backup of the registry, when starting up CleanMyPC.8JoN= HTo archive Rayfract profile database files seis32.* and WET tomography output files *.GRD etc. as written to profile subdirectories GRADTOMO (Smooth inversion) and TOMO (Automatic Delta-t-V and WET inversion), we recommend WinRAR. Seehttp://www.rarlab.com .For safe Internet access, we recommend to stop using Microsoft Internet Explorer and use e.g. the free Mozilla Firefox browser instead. For details seehttp://www.mozilla.org/products/firefox .4\L5 8Also, we recommend to stop using the Microsoft Outlook Express e-mail client and use a more secure alternative such as Eudora, with automatic HTML display disabled. Even better, always check your incoming e-mail in your webmail account and delete any spam. Only then download the relevant messages to your PC, with your local e-mail client.oN For more tips on securing your PC, we recommend the book "Computer Security for the Home and Small Office" Copyright 2004 Thomas C. Greene, ISBN 1-59059-316-2.xoNN' For tips on administering Windows Operating Systems in general, please see e.g.http://www.petri.co.il/index.htm .S"1Starting up and profile managementR/N# ^Starting up Rayfract and profile managementr ΀ D-To startup Rayfract, proceed as follows : Under Windows 95 or 98 and NT 4.0, click the Start button. Then select menu item Rayfract and the Rayfract icon contained in that folder.Opening a profileIn order to open a profile, please select File|Open Profile. Now a file open dialog appears, prompting you to select a seis32.dbd database schema. All profile header, shot header, trace header, binary trace data and resulting model data related to one profile is stored in one Rayfract profile database, defined by a seis32.dbd database schema. Exactly one database is stored per file system subdirectory. The sample profiles are located in directories \RAY32\LINE14 and \RAY32\PALMER. If you want to open a profile which you created earlier on, please select the directory you specified when you created it via New Profile. You may change the current profile database with File|Open Profile at any time. The current profile's directory path is displayed in the application's title bar.kF Zg Defining a new profileTo initialize a new profile, select File|New Profile. Next, the Create New Profile dialog is displayed. Either accept the default new profile subdirectory proposed or enter a unique new profile name (whole directory path or just subdirectory name, up to 8 characters) in edit field file name. Please note that long format directory names (containing spaces or longer than 8 characters) are not allowed. Select the drive to contain the new profile with the drop down list at the bottom of the dialog. Specify the directory to contain the new profile (i.e. its parent directory) via the directory list control in the center of the dialog. Navigate to that parent directory by consecutively double clicking directory levels, starting at the root \RAY32 directory of the drive selected. We recommend to have a directory \RAY32 in the root directory of your hard-disk volume (does not have to be drive chosen at installation time), and then create subdirectories in that root level directory, one for each profile to be processed. Once you have specified above information, click OK in order to generate the new profile database and to open it as the current database. rA P Now a new empty Rayfract profile database will be generated, in the subdirectory as specified above. The database component files are named seis32.d?? and seis32.k??. The database will be filled in once you import seismic data files; see below.Once you have generated the profile as just described, select Header|Profile and fill out at least edit fields Line ID, Job ID, Instrument, and Station spacing (in meters).Then hit RETURN.Please note that creating a new profile may fail in certain rare circumstances. These typically are low disk space situations. The software will display an error message indicating the problem and how to proceed. It will shut down once you accept the dialog (with RETURN or by clicking on the OK button). We recommend to reboot your PC in such a situation, and to make sure that there is ample disk space on both your C: drive, the drive/partition onto which you installed Rayfract, and on the partition on which you tried to create the new profile database. 400 MBytes of free disk space on each of these drives/partitions should be safe. Then delete the invalikNd profile subdirectory within Windows Explorer (see below) and re-create it with Rayfract (File|New Profile...).kQ paValidating a profile databaseYou may check the consistency of the profile database currently opened by selecting File|Check Profile at any time. The resulting message "0 errors were encountered in 0 records/nodes" signals that your profile database is in a consistent state.Renaming and deleting Rayfract profilesTo rename and delete Rayfract profile subdirectories, start up your Windows Explorer. E.g. select Start|Run..., enter command line "Explorer" and hit ENTER. Now navigate to the drive containing your \RAY32 data root level directory. Click on the \RAY32 directory with your left mouse key. Then click on the targeted subdirectory label. Now click your right mouse key and select menu item Rename or Delete. If your selected Rename, now enter the new subdirectory name (i.e. profile name) and then hit RETURN. If you selected Delete, confirm the following prompt to delete the subdirectory and its content.($ U$1d$I IDialog box control and function keysJ'I# NDialog box control and function keys2p e Use the TAB key in order to cycle through the control fields, i.e. to change the input focus. Use the RETURN key in order to confirm the dialog box changes just made. Alternatively, click the OK, Read, Accept or equivalent button (if existing). Use the ESC key in order to cancel changes to the dialog box / not to carry out the transaction configured by the dialog box. Alternatively, click the CANCEL or equivalent button (if existing). Press F1 to obtain online dialog help on the dialog control currently holding the input focus.`IKI `/In the following, displays generated by selecting menu items in menu Trace are called Gather displays. Displays generated by selecting menu items in menu Refractor are called Breaks displays.Here are the most important function keys for working with Rayfract :CR#t+#S""8Function key combinationMeaning assigned to key combinationWKX#+#S".  2F1Context sensitive online help in dialogs. Zoom time scale (Gather displays)-R#tZ+#S"" F2Unzoom time scale (Gather displays)?M}#Ȁ+#S"vu|s.FƔCTRL-F1Zoom traces, in amplitude coordinate (Gather displays). Pick Branch point 1, in Shot breaks display. Zoom CMP curves (reduced time axes) in Midpoint breaks display .Fd#+#S"Fu|s.FDEL-CTRL-F1Delete Branch point 1, in Shot breaks displayBM9}#Ȁ+#S"vu|s.FƔCTRL-F2Unzoom traces, in amplitude coordinate (Gather displays). Pick Branch point 2, in Shot breaks display. Unzoom CMP curves (reduced time axes) in Midpoint breaks display.Fd#+#S"Fu|s.FDEL-CTRL-F2Delete Branch point 2, in Shot breaks display=9rR#tz+#S""CTRL-F3Toggle trace display modes, in Gather displaysg=X#+#S". F7Page backward (header data dialog boxes, gathersr=, traveltime curves in Shot breaks display)erX#+#S". F8Page forward (header data dialog boxes, gathers,traveltime curves in Shot breaks display)S=R#t+#S""PAGE DOWNPage downwards (increasing time) along time axis (Gather displays)O@R#t+#S""PAGE UPPage upwards (decreasing time) along time axis (Gather displays)XR#t+#S""CTRL-HOMEPage to up most time section (minimum recording time) (Gather displays)Z@R#t+#S""CTRL-ENDPage to bottom most time section(maximum recording time) (Gather displays)kL#h>+#S""ALT-PAGE DOWNSee F8 aboveijL#h:+#S"ALT-PAGE UPSee F7 aboveM R#t+#S""ALT-HOMEPage to first record (dialog box / gather / traveltime curve)KjR#t+#S""ALT-ENDPage to last record (dialog box / gather / traveltime curve)O GR#t+#S""SHIFT-F1Zoom station number axis (horizontal axis), for Gather displaysQR#t+#S""SHIFT-F2Unzoom station number axis (horizontal axis), for Gather displays`GR#t+#S""&SHIFT-PAGE DOWNPage to the right by one profile section / pan right, for Gather displays\JR#t+#S"""SHIFT-PAGE UPPage to the left by one profile section / pan left, for Gather displaysGR#t+#S""SHIFT-HOMEPage to leftmost profile section, for Gather displaysGJ| R#t+#S""SHIFT-ENDPage to rightmost profile section, for Gather displaysl k#+#S"RƔALT-MDisplay Model parameter dialog, for Midpoint breaks (Trace to refractor mapping parameters), CMP intercept time refraction, Plus-Minus and Wavefront menu items/displays. Display Trace processing parameter dialog for Shot gather display.k|  R#t+#S""ALT-PDisplay Display parameter dialog, for Gather and Breaks displays / Depth and Velocity sectionso f R#t+#S""ALT-ADisplay Annotations parameter dialog, for Gather and Breaks displays / Depth and Velocity sections = X#+#S".ALT-YRedisplay current Gather display and/or Breaks display, to ensure consistent display e.g. after repicking tracesSf  X#+#S".s.FSHIFT-OCheck shot positions vs. traveltime curves, in Shot breaks displayH= R#t+#S""SHIFT-LReverse polarity of current trace, in Shot Gather display k#e+#S"Ru|s.FALT-LReverse polarity of all traces of current shot, in Shot Gather display. Remap traces to refractors based on current Branch points, in Shot breaks display .@Y#+#S".ƔALT-G@Smooth crossover distance separating refractors, along profile, with running average filter. Use this after mapping traces to refractors in Midpoint breaks display with ALT-M .-Ae#+#S"Fs.FƔALT-UUndo mapping of traces to refractors, in Shot breaks display and Midpoint breaks display. Also undo shot offset corrections, as applied to traveltime curves during earlier mapping._@BR#t+#S""6Left button Mouse clickSelect trace and sample and pick first break, in Gather displays\APCR#t+#S""BSHIFT-Left button Mouse clickSelect trace and delete first break, in Gather displaysfBDR#t+#S""SPACE keyPick first break at current trace and sample (at cursor location), in Gather displaysGPCDR#t+#S""ALT-DELDelete first break for current trace, in Gather displaysDE_#+#S":ƔARROW DOWNMove trace cursor down trace in Gather displays. Move CMP curve cursor to next larger offset in Midpoint breaks displayDwF_#+#S":ƔARROW UPMove trace cursor up trace in Gather displays. Move CMP curve cursor to next smaller offset in Midpoint breaks display.3EGk#+#S"RƔs.FARROW LEFTMove trace cursor one trace left in Gather displays. Move CMP curve cursor one CMP left in Midpoint breaks display. Move branch point pick cursor left in Shot breaks display.7wFHk#+#S"RƔs.FARROW RIGHTMove trace cursor one trace right in Gather displays. Move CMP curve cursor one CMP right in Midpoint breaks display. Move branch point pick cursor right in Shot breaks display.*G I& HR!H]I1o]IIData processing sequence overviewG$ II# HData processing sequence overviewU]ILs  Ts.FƔC]Proceed by selecting menus / menu items from left to right : import data, edit header data (station spacing !) and pick first breaks semi-automatically or interactively. Now either process your profile automatically with Smooth inversion|WET with gradient initial model, or assign traces to refractors (manually in Shot breaks display, semi-automatically in Midpoint breaks display). Before starting to assign traces to refractors, decide if you want to model your data as a 2-layer case (1 refractor) or as a 3-layer case (2 refractors). When mapping traces to refractors in your Midpoint breaks display, set parameter Refractor count in Midpoint breaks display / Model parameter dialog (ALT-M) accordingly.II `Please note that whenever you repick first breaks, edit coordinates or delay times, or (re)import shots, first breaks or geometry, previous results and trace-to-refractor mappings will be reset. Also, (re)importing one or more shots will automatically reset the profile geometry. You will then need to update the geometry, e.g. via File|Update Station coordinates and File|Update Shotpoint coordinates. So it does make sense to regularly export station coordinates and shotpoint coordinates, via File|Export Station coordinates and File|Export Shotpoint coordinates. The resulting files are per default located in your \RAY32 profile subdirectory, and are per default named COORDS.COR andL I SHOTPTS.SHO.L( IFor an illustration of typical data processing sequences, please see our manual and tutorial chapter, as available athttp://rayfract.com/help/manual.pdf .F-1-h!Receiver spread types;h# 0Receiver spread types-Z* " If you are processing your seismic data both with reflection seismics methods and refraction seismics methods, you typically have no other choice than planting your receivers at constant intervals. Otherwise reflection seismics processing may not work. High coverage data typically is recorded for interpretation with reflection seismics methods, and possibly for parallel interpretation with refraction seismics methods. For reasons of simplicity, you may also want to employ spreads with receivers separated from each other by a constant distance interval for low and high coverage refraction surveys. We actually recommend to employ these already defined, regularly spaced layout types whenever possible.hB' For carrying out low coverage refraction seismics surveys, some parties prefer to define their own irregularly spaced layout types. You want to optimally map both the (typically thin) weathering layer (as indicated by direct wave arrivals, at near offset receivers) and refractors (as indicated by refracted wave first breaks, recorded at further offset receivers). To optimally map the direct wave velocity, you may want to place receivers close to each other and to the source at near offsets. To optimally map refracted wave velocities and intercept times, you need to record the refracted wavefronts over as long a distance as feasible with a limited number of channels. Resolution is not that important (and not easy to numerically achieve) for deeper refractors, so you will separate neighboring receivers by distances increasing with offset from source location. Note that we implicitly assume that velocity increases with depth, i.e. with refractor.Z.E XOiZ\o4When importing seismic trace data recorded for one shot, you need to specify the spread type used (relative distances between adjacent receivers), the station spacing (scale at which spread type is actually planted), and finally the layout start. The layout start is expressed in profile relative, integer (whole) station numbers. The spread type is defined in spread relative integer station numbers. These relative station numbers are relative to the first/leftmost receiver position of the spread, as planted. The spread relative station number of the leftmost receiver position is always 0. The profile relative station number of the first spread receiver position is defined by layout start. So the software will be able to convert between spread relative and profile relative station numbers by means of the layout start, as entered during data import. For more details, please see Station numbers and spread types.=BkA PiZ\The station spacing is defined once only, for the whole profile. The corresponding edit field is located in your Profile Editor (Header|Profile).Note that we assume that channel 1 of your seismic data recorder always records trace data as registered by the receiver planted at the left limit (with station numbers increasing to the right)/start/lowest station number of your spread. If you have the habit of turning this recording convention around by 180 degrees sometimes, please let us know.P. D VCFinally, we would like you to lay out your spreads such that they overlap by a few receiver positions, ideally by up to half the spread length. This makes data interpretation easier/safer, especially regarding absolute depth of refractors.To define your own receiver spread types, please see Defining your own layout types.k k0 .wʘgTo export your custom spread types to an ASCII text file, and to reimport such a text file into your reference database, please proceed as described in Import/export of layout types.* !& Q r1 rStation numbers and spread typesH#!% FStation numbers and spread types(r% & cThe "station number" concept is widely used in Reflection Seismics processing, and is helpful for the reliable and correct interpretation of Refraction Seismics data as well.(% 2 2eiZ\The Interpex Gremix .GRM file format lists shot and receiver locations in metres, with the leftmost receiver conventionally positioned at an offset of one station spacing.(% D ViZ\Let us assume that during import of one shot with File|Import Data... , Layout start is set to station nr. 1, Station spacing is set to 4 metres, and the first layout receiver is located at "position" 4m, as indicated in a related .GRM file. Also, let us assume that this is a profile with just one equidistant receiver spread. In this case, station nr. 0 corresponds to a .GRM position of 0m, and station nr. 1 corresponds to a .GRM position of 4m.('% & sTo convert a shot position in metres e.g. 12m to the left of the first profile receiver (corresponding to a .GRM location of -8m) to a station number, now please proceed as follows :('.% >E X}PliZ\1.Determine the signed distance between the shot position and the first profile receiver, e.g. -12m.2.To obtain the relative position in station numbers (relative to the first profile receiver), please divide this signed shot distance (from the first receiver) by the station spacing. E.g. -12m divided by 4m gives -3.3.Now add this relative position (in station numbers) to the absolute station nr. of the first profile receiver i.e. to the layout start. E.g. add -3 to 1 and obtain -2, as the "absolute" (profile relative) shot position in station numbers..xA P PlR?h4.Finally enter this profile relative shot position (in station nrs.) into field Shot position, of the Import shot dialog.(% lx@ NlTo get a better understanding of the conversion from positions in metres to positions in station nrs., please also review topics Receiver spread type and Defining your own layout types.(% l0 .wlʘgTo export your custom spread types to an ASCII text file, and to reimport such a text file into your reference database, please proceed as described in Import/export of layout types.(% l(% l& lWe admit that the station number concept and the related concept of Receiver spread types may be a bit difficult to understand at first sight. Especially to users who up to now have processed their data with other software such as Interpex Gremix, W_GeoSoft WinSism, Earth FX VIEWSEIS etc. These packages let the user specify shot locations and receiver positions in metres directly.(% l]m; FlThe advantages of our station number and related Receiver spread type concepts are :(% lNmR rPl " "much fewer recording! geometry specification errors, especially in situations where the receiver spacing varies along the spread. Correct geometry specification is paramount for obtaining meaningful first break interpretations. We prefer to catch geometry errors as early as possible with mandatory redundancy in the specification, instead of giving your clients bad output based on an invalid geometry specification.let the user explicitly define and name his or her own receiver spread types.< ڀPl " " " "]zOclear separation of the concepts "x coordinate" and "position in metres" vs. "station number".in situations of steep and strongly undulating topography, x and y coordinates can be corrected for the topography in the Station Editor (Header|Station), with buttons Correct x and Correct y.Station numbers always remain constant, independent of the topography.enable the easy and consistent database internal sorting of traces by CMP station number. This is a prerequisite for subsequent interpretation of first breaks with our Delta-t-V method.M1$ @Overlapping receiver spreadsB@# >Overlapping receiver spreadsH J b}&Q ƔAs specified in System limitations, we require that multiple receiver spreads overlap with each other, if you want to process shots recorded by these spreads as one Rayfract profile.In the following we assume that you want to import shots recorded with six overlapping receiver spreads. Each such receiver spread has 24 active receivers.If adjacent receiver spreads overlap at least at one receiver station, then you can process the shots recorded by these receiver spreads as one Rayfract profile. If there is no overlap between adjacent receiver spreads, then you have to process each spread separately. The less far offset shots you record for each spread, the more the spreads need to overlap to obtain a good coverage. If you don't record far offset shots at all, spreads need to overlap 25% or even 50% of their length. Otherwise resulting tomograms may show coverage gaps. To check the coverage, select Refractor|Midpoint breaks.R@ R rR?ho4When importing a specific shot, you need to review and if necessary adapt Layout start and Shot position in the Import shot dialog. See Station numbers and spread types for more information. We recommend to proceed as described below :x H  o Pl " " " "create a new Rayfract profile database named e.g. "NIRMTEST", as described in our manual http://rayfract.com/help/manual.pdf.now open a DOS box e.g. via Start|All Programs|Accessories|Command Prompt.now generate a separate subdirectory for each of your 6 spreads, named e.g. \RAY32\NIRMTEST\SPREAD1 etc. with md command.copy the binary trace data and ASCII header data (Interpex Gremix .GRM etc.) files for each spread into the corresponding subdirectory, with copy command or in Windows Explorer.# 5S tPl " "R?hmake sure that shot numbers are unique over all spreads imported. E.g. rename shot nr. 1 of SPREAD1 to shot nr. 11, shot nr. 2 of SPREAD1 to shot nr. 12, ..., shot nr. 3 of SPREAD4 to shot 43, ..., etc.You can rename either the .DAT trace data files in subdirectories SPREAD1 ... SPREAD6 : rename 1.DAT to 11.DAT for SPREAD1, ..., rename 3.DAT to 43.DAT for SPREAD4, ..., etc. Or you can renumber the shots during import, in the Import shot dialog.G  B ԀPl "tp΀ "tp΀o4now import shots for SPREAD1 into profile NIRMTEST, as described in 5 Bhttp://rayfract.com/help/manual.pdf. Set Input directory to \RAY32\NIRMTEST\SPREAD1. Leave Layout start at its default value of 1.0.now import shots for SPREAD2. Set Input directory to \RAY32\NIRMTEST\SPREAD2. Adapt Layout start to the profile relative station number of the first receiver of SPREAD2. E.g. if the first receiver of SPREAD2 is positioned at station nr. / receiver nr. 19 of SPREAD1, then set Layout start to 19.0. See Station numbers and spread types for more details.F5E Pl " " "mGux]set Shot position for shots recorded with SPREAD2 to the spread relative shot pos. (starting at 1.0) PLUS the difference between Layout start for SPREAD2 and Layout start for SPREAD1. E.g. if a shot is positioned at station nr. / receiver nr. 3 of SPREAD2, specify its shot position as 3+ (19-1) = 3+18 = 21.0.proceed with importing shots from SPREAD3 etc. as described above for SPREAD2.instead of determining layout start and shot position manually as above, you may want to uncheck import option File|Import Data Settings|Keep same Layout start for consecutive shot trace files. Then our import routine will determine layout start and shot position directly from the SEG-2 trace headers. Of course this will work reliably if SEG-2 trace headers contain valid recording geometry information only.( BF% l(EAF% lFPIP nlIf your input data is formatted as ASCII .ASC/Interpex Gremix .GRM/OYO SEISREFA .ODT, W_GeoSoft WinSism .XYZ, Earth FX VIEWSEIS .PRN files, OPTIM LLC SeisOpt or Geometrics SeisImager PickWin/PlotRefa .VS, you may copy all files relevant for one profile (one file per overlapping receiver spread or "line") into the same subdirectory. Then select one of these files in the Import Shots dialog, with the Select button. Now select the correct receiver spread type etc. and click on button Import shots. Now shots specified in all matching files (regarding file extension) stored in the same subdirectory will be displayed in the Import Shot dialog and may be imported with the Read button.(AFxI% ldPI&KJ blPlease note that you may need to adjust shot position and layout start for these shots, so that all station numbers are relative to the layout start of the leftmost receiver spread imported into the same profile database. Also, shot number need to be unique across all files (spreads) to be imported into the same Rayfract profile database.xIM- (}lYou need a maximum shot-geophone offset of 6 times the maximum target depth. If you insist on a maximum target depth of 150 meters, then the maximum shot-geophone offset required is at least 900 meters. We recommend to use a geophone spacing of 10 meters, with your 48 channel spread. Some of our clients regularly use our software, with such a receiver spacing. Use an overlap of 22 geophones, between adjacent spread layouts. See below.(&K9M% l_9MN& slThen shoot into the first spread layout from maximum far reverse offset at 480 meters to right of last receiver. Shoot into the last spread layout from a maximum far forward offset at 480 meters to left of first receiver. For receiver spread layouts and shot positions, please refer to the following graphics :(9MN% l(NN% lnINVO% l +--+--+--+--+--+--+--+--+ + + + + + + + + : first spread(N~O% loJVO % l + + + + +--+--+--+--+--+--+--+--+ + + + + : second spread~O )~O5% l nI % l + + + + + + + + +--+--+--+--+--+--+--+--+ : third spread(5ˀ% lӁ& lThe "+" symbol means a shot position. The "--------" line represents the 48 channel receiver spread. One character column corresponds to a distance of 20 meters. The shot spacing is 60 meters, receiver spacing is 10 meters.(ˀ% lF ӁA& AlThe second spread is moved 260 meters to the right, in relation to the first spread. Shot stations don't coincide between adjacent spreads, but are "staggered", i.e. moved 20 meters to the right. Receiver stations do coincide, in the overlapping section of two adjacent spread layouts.(i% lA) lSince all shots "+" are positioned within or directly adjacent to at least one receiver spread layout, all shots can be used for WET true 2D tomography processing. In the context of WET processing, all spreads are "active" at the same time.(i% l(ք% l(% lvQքt% lFor a sample client recording geometry using overlapping receiver spreads, see(% lP+t% Vlhttp://rayfract.com/help/overlap.pdf .(% l(<% l(d% lvK<چ+ &lWe recommend to use a mobile weight drop as an energy source. See e.g.(d% l`;چb% vlhttp://www.geoexpert.ch/en/us/drop.php (in English), and\7% nlhttp://www.geoexpert.ch/it/us/drop.php (in Italian).(b% lO51 5yDefining your own layout typesD!y# BDefining your own layout types25f PY E1. Start up Rayfract and open a profile if not yet done so, i.e. \RAY32\LINE14.2.Select File|New Spread Type... .3.Page through existing receiver spread type definitions with F7/F8. Position to a spread type resembling the new type you want to define.4.Enter a new unique Spread type name into the topmost edit field of the dialog. This name will be shown for selection of the spread type, in dialogs Import Shots and Import Shot.q'yJ bOPY<5.Enter the number of receiver positions you are going to define for the new spread type, into edit field Receiver count.6.Take a sheet of paper and write down relative receiver positions of your spread type, in meters or in feet. These positions are relative to the leftmost receiver position (layout start, which therefore is always 0). E.g. 0, 5, 15, 25, 45, 50, 60, ...7.Determine the greatest common divisor (GCD) of distances (in meters or in feet) separating adjacent receiver positions, of your spread type. E.g. if separations are 5 or 10 or 20 meters or feet, the GCD is 5 meters or feet. This GCD will be the station spacing of your spread type (as defined in your Profile Editor, Header|Profile). The GCD value corresponds to one station number interval, in meters or in feet.W"5 8EPY8.Divide all relative geophone positions (in meters or in feet) of your spread type by the GCD distance determined above, in order to obtain relative geophone positions in integer station numbers. E. g. for a spread type with receiver positions (in meters or in feet) 0, 5, 15, 25, 45, 50, 60, ..., the resulting receiver positions (in station numbers) are 0, 1, 3, 5, 9, 10, 12, ...9.Once you have rewritten your spread type with receiver positions expressed in relative integer station numbers (relative to layout start/leftmost position, equal to 0), translate this form of spread type definition into yet another, shorter form : the receiver separations string. This string is formed by counting the number of times the same receiver separation distance (in station numbers) is used between adjacent receiver positions, starting at the leftmost spread position equal to 0 and moving to the right / increasing receiver position station numbers. Once the receiver separation changes, append a term "x*y" to the receiver separations string. Replace the place holder x with the number of times the same receiver separation distance is used, and y with that receiver separation distance (in station numbers). If x is equal to 1, just append a term "y". Now count the number of times the new receiver separation is used, starting at the receiver position to the right of which this new separation is used for the first time and proceeding to the right until the separation changes again. Then append the resulting new term to the end of above receiver separation string, separated from the previous term by a comma. E.g. for a spread type with receiver positions (in meters or in feet) 0, 5, 15, 25, 45, 50, 60, ..., and a station spacing of 5 meters the resulting receiver separation string is "1, 2*2, 4, 1, 2, ...".k 3PY³YiZ\10.Now enter the receiver separation string as just computed into edit field Receiver separations [station nr. intervals], of your Create New Spread Type dialog. Then hit ENTER or click on button Create to generate the new receiver spread type.11.The new receiver spread type as just defined will now be available in all Rayfract profiles you open or create, with this Rayfract installation.12.Startup Rayfract, and create a new profile (via File|New Profile). Specify the correct station spacing in Header|Profile. If you just want to check if your new spread type definition was successful, you may just open an existing profile. }_ =PYl *13.Bring up the Import shots dialog, by selecting File|Import Data. Click on the combo box list control below label Default spread type. Scroll through spread type names available with up/down arrow keys. If your name appears, your spread type definition was successful.14.You may now want to actually import a shot. Be careful to correctly specify spread type and layout start. Then select the shot record in the Shot Editor (Header|Shot) by navigating to the shot just imported with F7/F8. Leave the editor with ESC.D VgPY15.Now startup the Receiver Editor, via Header|Receiver. Page through receiver records with F7/F8. Check if Station positions (i.e. station numbers) displayed are correct for all receiver Channels nrs. Note that station numbers displayed are absolute (relative to profile). You need to mentally subtract the station number of the first receiver channel (i.e. the layout start), in order to obtain relative station numbers.) Once you have become acquainted with this procedure, you may skip the formal steps 6 to 9 as described above and just perform these in your mind before proceeding to step 10, of course. Steps 12 to 15 are not a must as well.R!X1M XImport and export of layout typesI$% HImport and export of layout types(X% mh& Version 2.72 and later versions of our Rayfract software offer File menu functions for export/import of receiver spread types. Please note that starting with version 2.73, you are not required to open a profile database first, to enable this import/export. Also, wheneverh you define a new spread type, all spread types are exported to file \RAY32\REF\MYSPREAD.SPR. Spread types are stored in the reference database (directory \RAY32\REF, files SEISRF32.*), and not in the individual profile databases. So any custom spread type defined earlier is available for all profile databases. After installing an updated version of our software, you may want to reimport your custom spread types, as e.g. stored in \RAY32\REF\MYSPREAD.SPR . Version 2.73 and later of our installation routine will import your custom spread types automatically, into a reinstalled reference database.(% h& When using version 2.71 or earlier versions of our Rayfract software, we recommend to export your custom receiver spread types from your reference database to an ASCII text file whenever you define a new spread type. Please proceed as follows :(% Z50% j0. Shut down Rayfract, if currently running.(X% 0m0 .Tl1.Open a command prompt with Start|All Programs|Accessories|Command Prompt, or just Start|Command Prompt if available.2.Change the current drive to the drive / partition on which you installed Rayfract. E.g. enter the command line "d:" and hit RETURN.3.Change the current directory to your \RAY32\REF directory, with command "cd \ray32\ref".4.Backup file SPREAD_T.TXT to SPREAD_T.OLD with command "copy spread_t.txt spread_t.old". Confirm the "Overwrite..." prompt with "y".oX . *Tl5.Export your current spread type definitions with command "dbexp -r refref32 spread_type". Now your custom spread types are written to file spread_t.txt.6.Backup file SPREAD_T.TXT to SPREAD_T.BAK with command "copy spread_t.txt spread_t.bak". Confirm the "Overwrite..." prompt with "y".7.Backup file SPREAD_T.BAK to permanent media, e.g. CD-R or floppy disk.m ( lTo import your custom spread types into your reference database, e.g. after upgrading from/to a new Rayfract version up to and including version 2.73, or after installing Rayfract on another desktop or portable PC :c  2 2Tl8.Repeat steps 1. to 4. as described above.9.Restore your SPREAD_T.BAK file from CD-R or floppy disk, to the current directory (e.g. to d:\ray32\ref).10.Copy your custom spread types from file SPREAD_T.BAK to file SPREAD_T.TXT, with command "copy spread_t.bak spread_t.txt". Confirm the prompt with "y".11.Initialize your reference database with command "..\bin\initdb refref32". Confirm the prompt with "y".12.Import all reference database types including your custom spread types with command "dbimp seisrf32.imp". The last line echoed to your command prompt window should say "Successful import".  ) lTo update your reference database with your custom spread types after upgrading to Rayfract version 2.74 or later from an old version :Proceed as described in steps 8. to 12. outlined above, except steps 10. to 12. : . *Tl10.Copy your custom spread types from file SPREAD_T.BAK to file SPREAD_TYPE.TXT, with command "copy spread_t.bak spread_type.txt". Confirm the prompt with "y".11.Initialize your reference database with command "..\bin\initdb refref32". Confirm the prompt with "y".12.Import all reference database types including your custom spread types with command "..\bin\dbimp seisrf32.imp". The last line echoed to your command prompt window should say "Successful import".D 1_ -CASCII format dialog9-# ,ASCII format dialog@Bd  uYQ}9,`The ASCII format dialog contains drop down list boxes, one for each value column of the import file. The d-Befault sequence of values in one ASCII import line (corresponding to one trace header) is Shot number, Shot station, Receiver station and First break. Specify the value separator in edit field Separator. The default separator is a semicolon (;). Another frequently used separator is a comma (,). Specify the number of header lines in your ASCII file format at the bottom of the ASCII format dialog, in edit field Header lines to skip. Note that ASCII import files are supposed to have the DOS file extension .ASC . First break values in .ASC files are supposed to be specified in seconds. Please refer to sample file ASCII.ASC in your \RAY32\DOC directory, for a typically formatted ASCII import file.-C% Rayfract supports reading in multiple .ASC files from one directory, during one import session. Please note that traces recorded for the same shot need all to be stored in the same .ASC file.OBD1Zc DYDSeismic and header data importD!CYD# BSeismic and header data importT,DD( XDOS file names and extensions expected8YD:EU#zpV<?Z( ": Seismic data file formatDOS file name extension=DEI#bzV<?ZSEG-2.SG2 or .DAT (customary for Geometrics SEG-2 files)m$:E-FI#bHV<?Z,Bison-2 9000 seriesno extensionk"EFI#bDV<?Z8ASCII column format files.ASC?-F GI#b~V<?ZtGeometrics SeisImager PickWin and PlotRefa module files.VSRFGI#bV<?Z6OPTIM LLC SeisOpt files.TXT or no extension, files XYZ_SRC, XYZ_REC, XYZ_OBSr) G-HI#bRV<?ZFInterpex GREMIX / FIRSTPIX files.GRM;GHK#fvV<?Z`ABEM Terraloc Mark 3 filesOYO SEISREFA files.ABM.ODT=-H;IK#fzV<?ZdW_GeoSoft WinSism filesEarth FX VIEWSEIS files.XYZ.PRNYHNC T Gux] For SEG-2, Bison-2 9000 and Terraloc Mark 3 files, the shot number is determined by parsing the current shot input file's DOS filename. This filename is supposed to have the format "AAAXXXXX" plus the file extension, as specified above. "AAA" stands for an alphabetic label (must not contain digits) of the profile, i.e. "GLA". It may be empty. This label is discarded when the software reads in the file. "XXXXX" stands for a number string from which the shot number is determined, i.e. "00101". For ASCII column format files, the shot number is determined from the value specified in the corresponding column of the ASCII file. For Interpex GREMIX, OPTIM SeisOpt, OYO SEISREFA, WinSism and VIEWSEIS files, the shot number is read from the ASCII format shot headers as contained in these files. The shot number will be trimmed to a three digit number. I.e. shot number string "1001" will be truncated to RAYFRACT shot number 1. Assume that your shot file names include e.g. spread number and shot position in metres (at least three last digits of filename). If this is the case, you are supposed to renumber the shots during import, to sequentially increasing numbers starting at 0 or 1. See below. The original input file name remains visible, in the read-only Shot header field Original input disk filename, as visible in the Shot editor Header|Shot.D ;I': B Store/copy all shot files to be imported into one profile into the same subdirectory. This typically is a subdirectory of the directory holding the profile's Rayfract database (e.g. \RAY32\LINE14\INPUT).Conversion of unsupported dN'Cata formats to SEG-2We recommend to use the Interpex IXSeg2SegY utility (version 2.01 or higher) to convert binary trace data files from these formats to SEG-2 format : SEG-Y, SEG-1, BISON Geopro-1 8000 series, BISON Geopro-2 5000 and 7000 series, EG&G Geometrics 1200 series (Seisview), EG&G Geometrics 2401, OYO McSeis, SCINTREX S-2 Echo, multiplexed .TF, Dolang. First breaks picked with IXSeg2SegY and exported to SEG-2 format will be imported by our Rayfract software automatically (but .BPK and .FIR ASCII first break files in the input file directory have higher priority). Please make sure to specify sample type 32-bit Integer or 16-bit Integer, when exporting SEG-2 files from IXSeg2SegY. This utility also offers nice functionality for frequency filtering, of seismic traces.N7' You may download a free trial version of IXSeg2Segy from http://www.interpex.com. If your Windows XP installation does not allow the download from the Interpex ftp server, please try to download under Windows 98.Alternatively, you may want to use W_GeoSoft WinSism v. 10, for import of above data formats and first break picking. You may then generate either ASCII.ASC files or OPTIM SeisOpt files, for import into RAYFRACT. See http://www.wgeosoft.ch . Please note that we do not recommend to install WinSism v. 10 under Microsoft Windows 98 SE. Doing so will disable automatic imaging of Rayfract output with Surfer, since OLE system DLL files are overwritten by the WinSism installation routine, in your C:\Windows\System directory.P'@ N!  Conversion between feet and metersWhen importing SEG-2, Earth FX VIEWSEIS, Interpex Gremix .GRM files with header values specified in feet, these are converted to meters during import automatically. To import OPTIM LLC SeisOpt files and Geometrics SeisImager PickWin/PlotRefa .VS files with locations specified in feet, uncheck File|Default distance unit is meter. Our import routine currently (version 2.74) implicitly assumes that coordinates, elevations, shot offsets and shot depths in ASCII.ASC, W_GeoSoft WinSism and OYO SEISREFA files are specified in meters. We may regard the setting of File|Default distance unit is meter for these file types in a future version, if wished. Source and receiver locations in ASCII.ASC are always specified in Station Numbers. E7Au  iZ\ ZހlIf the word feet or meter is contained in a header line of a Survey Geometry .PRN, .SHO or .COR file, the shot and receiver positions and coordinates in that file are assumed to be specified in that distance unit. See http://rayfract.com/help/ln14feet.zip for sample files specified in feet.Internally all computations are done in meters, to enable easier development and testing of the software. Specify the station spacing in meters, in Header|Profile . Also, specify shot depth, shot position inline and lateral offsets in meters, in Header|Shot.@ގ] ^] ^]Z"mTo generate Smooth inversion, Delta-t-V and WET output in feet, please check Delta-t-V|Delta-t-V Settings|Output Delta-t-V results in Feet, before running these inversion methods.To generate Smooth inversion, Delta-t-V and WET output in meters, please uncheck Delta-t-V|Delta-t-V Settings|Output Delta-t-V results in Feet, and check Delta-t-V|Delta-t-V Settings|Output Horizontal offset of CMP pos. in meters, before running these inversion methods. For Smooth inversion, you may alternatively use option Smooth invert|Output inversion results in Feet.gA ̀T]zOH>vI+w^.ZAOnce Smooth inversion or pseudo-2D Delta-t-V inversion, possibly refined with WET tomography has completed, you may convert Surfer .GRD grid files (velocitގCy tomograms and coverage grids) with Grid|Convert grid file between feet and meters. Then plot these with Grid|Image and contour velocity and coverage grids.Import data files into RayfractStart with defining a new profile and Rayfract database, by selecting File|New Profile. See topic Starting up Rayfract and profile management. For importing of ASCII file format, review and if necessary edit the ASCII format dialog .bގ2 ꀩpqԂ"wd𞠀GmWNext review and if necessary adapt File|Import Data Settings options Allow missing traces for SeisOpt and Gremix files, X coordinate is corrected for topography already, Default layout start is 1.0, Default distance unit is meter, Default time unit is seconds, Detect shifted 32-bit floating point trace data start, Keep same Layout start for consecutive shot trace files, Keep same sample count for consecutive shot trace files.{ s 9C_ tpΉl Gux]In order to import data into the profile database currently opened, please select File|Import Data. Now, the Import shots dialog is being displayed. You only need to fill out control fields Import data type, Input directory and Default spread type. Specify the import file format by selecting the corresponding list entry, in the Import data type drop down list box. Currently, import file types ABEM Terraloc Mark 3 / ASCII column format/Bison-2 9000 Series / Interpex GREMIX/OYO SEISREFA /SEG-2 / W_GeoSoft WinSism / Earth FX VIEWSEIS / OPTIM LLC SeisOpt / Geometrics SeisImager Plotrefa are supported. 2 c l o4Specify the Input directory by clicking button Select besides that static edit field. In the file selection dialog now appearing, select an input file containing shot(s) to be imported, in the appropriate input directory. All matching files in that directory will be imported. Specify the receiver spread type used during recording of the data with the Default spread type drop down list box. Spread types are named "X: YYY channels". Please note that all except the last two (named "11: leftnarrow" and "12: 24 refract.") currently defined spread types assume equidistant receiver spacing, with all adjacent receiver positions separated from each other by one station number interval. If you need to define your own, non-equidistant spread types, please follow instructions as provided in help topic Defining your own layout types. Also, see topic Station numbers and spread types.* 5& Hg 1 2Hj≀Once you have specified at least these parameters, click on button Import shots, or hit RETURN. (5% H -HR?hbŀϓuAs soon as you have confirmed the Import shots dialog (and the ASCII format dialog, for import type ASCII), the Import shot dialog is displayed, once for each shot contained in the input directory. Edit the Shot Number if you need to renumber the shot. Adapt Shot position (in station numbers) and Layout start, if required, for each shot being imported. Confirm the dialog by hitting ENTER, or by clicking on the Read button, with your left mouse button. If you activated check box Batch import in dialog Import shots with Import data type ASCII, the Import shot dialog is still displayed for each shot being imported, but you cannot edit its content. Instead, the program simulates hitting the Read button and proceeds with importing the shot at once.(% H^[2 2HWhen importing[C Geometrics or ABEM data files, the import routine checks for the existence of Rimrock Geophysics SIP .PIK, Geometrics .BPK or ABEM .FIR ASCII first breaks files in the input directory, correspondingly. If these are present in the same directory as the data files to be imported and named the same way as the data files (not regarding the file extension), first breaks contained in these files are imported automatically. Check your \RAY32\DOC directory for sample files. .PIK files have precedence over .BPK or .FIR files, if both versions are present in the current import directory.(% Hg[ HiZ\mR?hGux] o4When importing SEG-2 formatted files, the shot position is initialized according to SEG-2 trace header entries SOURCE_LOCATION and RECEIVER_LOCATION for the first channel read in. These locations may be specified either in meters or in feet, according to the SEG-2 file header UNITS entry. It is assumed that the first channel stored in the SEG-2 file was recorded at the receiver location with the lowest station number of the spread employed for recording the data. Rayfract parameters Station spacing and Layout start are used to determine the initial value for shot position (in station numbers), based on SOURCE_LOCATION and RECEIVER_LOCATION. If import option Keep same Layout start for consecutive shot trace files is disabled/unchecked, Layout start specified in Import shot dialog is disregarded and the layout start and shot position are determined from the SEG-2 trace header directly. SEG-2 trace header fields SOURCE_STATION_NUMBER and RECEIVER_STATION_NUMBER override fields SOURCE_LOCATION and RECEIVER_LOCATION. See topic Station numbers and spread types for details.(% H' & HIf an ASCII .PIK / .FIR / .BPK first breaks file is present in the input directory and for the shot currently being imported, the shot position is determined from the source and first receiver location as specified in that file. This specification has precedence over the SEG-2 trace header entries SOURCE_LOCATION and RECEIVER_LOCATION. The distance unit is determined directly from the .PIK and .FIR files. For .BPK files, the distance unit is determined from the corresponding SEG-2 file header UNITS entry.( % HE  > JHo4If the shot position determined as just described and as displayed in the Shot position edit field of the current Import shot dialog is wrong, please compute the correct shot position in station numbers manually. Do this as explained in the following, and in more detail in topic Station numbers and spread types :(  % H$  X ~P:H"""receiver nr. 1 is typically located at station number 1, ..., receiver nr. 24 at station number 24, for an equidistant receiver spread type with 24 channelsconsider the station number coordinate system as being extended to include shot positions to the left of the first receiver / to the right of the last receiveras a consequence, station numbers equal to or smaller than 0 and equal to or larger than 25 may be used, to express shot positionsg A@w P:H""iZ\ ""determine the signed distance (in feet or meters) of the shot position, from the position of the first layout receivernow divide this distance by the station spacing (see Header|Shot, e.g. 10 feet)the result is the spread layout relative shot position, in station numbersto obtain the profile relative shot position in station numbers, add this spread relative shot position to the station nr. assigned to the leftmost spre A@Cad receiver (i.e. add it to the layout start).  EAE XP:H"R?hEnter this shot position into edit field labeled Shot pos. [station nr.] as displayed on the current Import shot dialog. Click on the Read button or hit ENTER to import the shots.R,A@B& YHIf you have ASCII .PIK / .FIR / .BPK first breaks files available for the corresponding shots, you may alternatively correct source and first receiver positions (in feet or meters) in these files with an ASCII editor and then reimport the corresponding shots and updated ASCII first breaks files. (EAB% H;BC& +HWhen importing first breaks from ASCII.ASC files, these files need to specify first break pick times for all receivers specified in the spread type used. If a trace cannot be picked (data is too noisy or the trace is dead), please specify a time of -1, meaning not picked.1B+D, ( P:CIG8 >R?hImport of ASCII.ASC shots may show an error message Shot position of shot nr. is not at traveltime curve minimum ". The import routine detects for inline shots the two channels with the smallest first break picks. If the shot is not positioned between these two channels, above message is shown and the shot is not imported. You may want to repick traces or edit the .ASC such that the shot position is located between the two smallest first break times. You may need to introduce artificial picks for near-shot traces which you did not pick previously. The traveltime curve minimum position may deviate from the true shot position by an inline offset up to the shot depth as specified in the .ASC or in the Import shot dialog .(+DqG% (IGG% (qGG% ^9GH% rUpdate trace headers with coordinates and first breaks(GGH% HLq 5Gux]You may update database records (trace header attributes) in an existing profile by importing survey geometry, receiver and shot point coordinates, elevations, shot hole depths, first breaks and uphole times. Do this via selecting the corresponding File|Update Geometry..., File|Update Coordinates..., File|Update Shotpoint coordinates, File|Update First Breaks..., File|Update from Gremix .GRM....and File|Update from OYO.ODT files... . Before you can use these items, you must have imported ABEM Terraloc Mark 3/SEG-2/Bison-2 9000/ASCII column format/OYO SEISREFA/Interpex GREMIX/W_GeoSoft WinSism/Earth FX VIEWSEIS/OPTIM LLC SeisOpt / Geometrics SeisImager .VS formatted data files as specified above, however. Please refer to sample ASCII files SPRNG2XT.PRN, L5.PRN, LINEBC.PRN, COORDS.COR, RECVRS.COR, SHOTPTS.SHO, BREAKS.LST, ASCII.ASC, LINE14.GRM, OYO.ODT, TOMOEVAL.XYZ, VIEWSEIS.PRN, SEISOPT_SRC/SEISOPT_REC/SEISOPT_OBS, PLOTREFA.VS, PICKWIN.VS in directory \RAY32\DOC, concerning the format of these input files.(GHL% L؁> J)  FIt is assumed that .COR files hold coordinates for inline (receiver) positions with whole station numbers only. The "seismic line" is assumed to be defined by all consecutive receiver positions. Since shot points are often located at inline and lateral offsets from the next receiver position (whole station number), it does not make sense to specify shot point coordinates, for shot stations, in .COR inline coordinate files. You may specify coordinates for far offset shot points in .COR files, however. Inline shot position coordinates are obtained by interpolating between the two nearest receiver station positions automatically. You may specify inline and lateral shot point offsets, shot hole depths anL؁Cd uphole times in Header|Shot. Alternatively, specify absolute shot point coordinates (x, y and elevation of shot point), shot hole depths and uphole times in a .SHO or .PRN file as shown in \RAY32\DOC sample files. Then import this .PRN or .SHO file by selecting File|Update Geometry... or File|Update Shotpoint coordinates... . These offsets will be regarded when estimating weathering velocities and correcting traveltimes for shot position offsets.(L% H؁H, &9If the y coordinate column (and shot hole depth column and uphole time column) of a .PRN file is empty, RAYFRACT will set the y coordinate of all station positions to 0.0 when such a .PRN file is imported with File|Update Geometry... . See sample file LINEBC.PRN in \RAY32\DOC .(p% Hc8 >ws.FIf edit field Uphole time correction term of the corresponding shot record (as edited in Header|Shot) is non-zero, first breaks of corresponding traces are always mapped to basement refractor automatically and are corrected for the hole depth by addition of this time correction term. You may fit in these uphole travel times with other traveltime curves in the Shot breaks display. , by adapting the time correction term iteratively.(p% c8& Sample file BREAKS.LST contains first breaks for the profile TRA9002 as illustrated in our manual and tutorial chapter. See http://rayfract.com/help/manual.pdf .Values in one line of a first breaks .LST file are supposed to be separated from each other by either one or more TAB characters or by one or more spaces. First breaks in .LST files are supposed to be specified in milliseconds.(`% O82 2;If the first (few) line(s) in .PRN, .SHO , .COR and .LST do(es) not contain number formatted data, these header lines will be skipped by the corresponding RAYFRACT import routines automatically. These header lines may contain column headers/titles etc. If the word feet or meter is contained in such a header line of a .PRN, .SHO or .COR file, the shot and receiver positions and coordinates in that file are assumed to be specified in that distance unit. See http://rayfract.com/help/ln14feet.zip for sample files specified in feet.(`׉% a/82 2_You may process the binary trace data and pick first breaks with your FIRSTPIX software as published by Interpex. Then import the resulting first breaks with File|Import Data... or File|Update from Gremix .GRM files... Receiver elevations and shot hole depths are imported from .GRM files automatically as well. If your Rayfract profile contains shot trace records as recorded with multiple receiver spreads along the same 2D line, just copy all corresponding .GRM files into the same subdirectory and select one of these in the file selection dialog.(׉`% 8W2 2If you have processed your trace data and picked first breaks with SEISREFA as published by OYO, you may import the resulting first breaks with File|Import Data. Receiver elevations and shot hole depths are imported from .ODT files automatically as well. File|Update from OYO .ODT files... . lets you update an existing Rayfract profile with first break data. If your Rayfract profile contains shot trace records as recorded with multiple receiver spreads along the same 2D line, just copy all corresponding .ODT files into the same subdirectory and select one of these in the file selection dialog. It is assumed that one .ODT file lists first breaks recorded with exactly one receiver spread only.(`% DWÏ1? Ā Ï  @Editing header data9 # ,Editing header dataÏ ] ÏiR r iZ\ ^ Once you have successfully imported your data, make sure that you correctly specify the corresponding header data. Review and correct Header|Profile, and fill out at least edit fields Line ID, Job ID, Instrument, and Station spacing (in meters). Please note that parameter Station spacing is of utmost importance, because all velocity estimations are based on that distance unit. Parameter Left handed coordinates lets you specify the orientation of your coordinate system, depending on your hemisphere. m [ %t>E所s.FYou may inspect shot headers by selecting Header|Shot. Page through them with function keys F7/F8. If you enter a non-zero value into shot header edit field Uphole time correction term, first breaks of corresponding uphole shot traces are corrected for the hole depth by addition of this time correction term (e.g. for display in Shot breaks display). You may optimally fit in these uphole travel times with other traveltime curves in the Shot breaks display by adapting the time correction term iteratively.'iQ pWhen selecting Header|Receiver, you may page through the trace headers of the current shot, as selected in Header|Shot. Edit the first breaks numerically in edit field First break time. A first break value of 0 or -1 means no first break picked for this trace. Receiver offset values are not regarded during processing at this time.Elevation specificationTo specify elevations for all profile shot and receiver stations, please proceed as follows :DQ po#{΀- select Header|Station- browse station records with F7/F8 . If x/y/z are correct already exit with ESC key.- otherwise click on button Reset coordinates and v0- leave x/y coordinates empty for all stations- enter elevation z for a few non-adjacent stations- you do not need to enter z elevation for all stations- now click on button Interpolate coordinates and v0Next you may reopen the station editor with Header|Station. Now browse station records with F7/F8 to check the interpolated elevations. Also, x/y coordinates have been generated automatically.1  o#{΀u|s.F{e{s.FTo specify a known/fixed elevation at more stations before interpolation, you need to first click on Reset coordinates and v0. Then reenter the elevation at all relevant stations, and click again on Interpolate coordinates and v0.Weathering velocity specificationPlease skip this step for Smooth inversion, and Delta-t-V and subsequent WET tomography processing. For conventional time-to-depth conversion methods you are required to specify a weathering velocity (e.g. 500 to 800 meters/second) for at least one station, in the Station & Shot point Editor (Header|Station). Specification of laterally varying weathering velocity is supported. You may manually pick branch points in the Shot breaks display. By doing so you interactively map first breaks of the currently selected shot sorted traveltime curve to refractors, on a segment wise/branch wise basis. Once you have picked branch points for all shot traveltime curves (to be regarded during time-to-depth conversion; see Mapping traces to refractors), you may copy the resulting weathering velocities to all profile stations and shot points. Do this by clicking on button v0 from Shots in your Station & Shot point editor. Version 2.66 and later versions of our Rayfract software will copy weathering velocities to station records automatically, once you remap traces to refractors in the Shot breaks display. Ѐ1HƔ牀*M?.]h@ƔIf the traveltime coverage is high enough, you may alternatively obtain a laterally varying weathering velocity function in the Midpoint breaks display (if receivers and shot points are spaced close enough to each other). See Mapping traces to refractors. Activate check box Direct Wave, in your Trace to refractor mapping parameters dialog /Midpoint breaks display. Once you have mapped first breaks to refractors in your Midpoint breaks display, the button v0 from CMP in your Station & Shot point Editor is enabled. Click on this button with your left mouse key, in order to copy laterally varying and smoothed/interpolated weathering velocity values into all station and shot point records. Version 2.66 and later versions of our Rayfract software will copy weathering velocities to station records automatically when you smooth crossover distances in the Midpoint breaks display.  x H豶pD u|s.FƔe.]hOnce you have picked first breaks and mapped traces to refractors, as described in Mapping traces to refractors, please check that you specified the correct shot hole depth and inline / lateral offsets (in meters) for all shot records. Do this by starting up your Shot Editor with Header|Shot, and then paging through records with F7/F8, as usual. Next, make sure that you specified appropriate (laterally varying) weathering velocities, in your Station & Shot Point Editor, as just described. Now you may compute and apply to first breaks Shot position offset corrections (for inline and lateral offsets / shot hole), by clicking on button Correct breaks, Station & Shot Point Editor. These corrections are computed and applied to first breaks automatically, when clicking on Station & Shot Point Editor buttons v0 from Shots or v0 from CMP. Please note that first breaks mapped to the weathering layer are corrected according to a different formula than first breaks mapped to refractors. This may lead to the necessity to repick branch points, in your Shot breaks display and Midpoint breaks display. You may want to pick branch point positions such that traveltime curves do not show artifacts of the picking process (irregularities near branch points picked). These artifacts may become visible when first breaks are corrected for shot position offsets and you redisplay the Shot breaks display or Midpoint breaks display with Trace mapping|Refresh display. Once you have repicked branch points, go back into the Station and Shot Point editor via Header|Station. Click on button v0 from Shots or v0 from CMP, in order to recompute and copy velocity values into all station and shot point positions. ? LHOnce shot position offset corrections have been applied to all traces, you may redisplay your Shot breaks display (Refractor|Shot breaks) or Midpoint breaks display (Refractor|Midpoint breaks). Reopen the display or click on its title bar with your left mouse key and enter command ALT-Y. Traveltime curves are now reduced to shapes which you would have recorded with your source located at the same elevation as and aligned with the (adjacent) receivers.A  @G \HWhen you have carried out time-to-depth conversions and resulting refractor velocities are known, you may remap traces to refractors (Trace mapping|Remap all traces) and redo the time-to-depth conversions. This may result in slightly improved results, especially in situations where velocity contrasts are low.In order to undo shot position offset corrections as applied to all traces, select Trace mapping|Undo trace corrections while in the Shot breaks display or Midpoint breaks display.  @E Q@1% Q@@Picking first breaks: @@# .Picking first breaks@Q@BD V t>Next, select Trace|Shot gather. You may page through shot records with function keys F8 (forward) and F7 (reverse). Use function keys CTRL-F1/CTRL-F2 in order to zoom/unzoom traces in the amplitude coordinate. Use CTRL-F3 in order to toggle trace display modes. Use F1/F2 to zoom/unzoom the vertical time scale. Use SHIFT-F1 and SHIFT-F2 to zoom/unzoom the horizontal station number axis. See Dialog box control and function keys, for a complete listing of function keys and their functionality.@F- (Click at a trace location with the left mouse button, in order to pick a first break. Press the left SHIFT key and then click at a trace in order to delete the first break picked earlier, for that trace. Alternatively, first breaks may be edited numerically, in the Receiver editor (Header|Receiver). A first break value of 0 or -1 means not picked.To move the pick cursor (cross symbol) along a trace sample by sample, select the trace with the left mouse key. Then use the Arrow Up and Arrow Down keys on your keyboard to move along the trace. Once the pick cursor is located on the estimated first break sample, click your left mouse key without moving the mouse to pick the trace. For version 3.14 and later versions of our software, hit the space bar instead, to pick at the current cursor location, without re-selecting current trace and sample. Also, use ALT-DEL key combination to delete the first break pick for the current trace, with version 3.14 and later versions.DB{Le s.FTo move the pick cursor to the next / previous trace and pick, use Arrow Left and Arrow Right keys on your keyboard. Trace cursor attributes are shown at bottom of trace gather display, when moving the pick cursor with left/right/up/down arrow keys. We show station number, gather specific trace number, shot number, channel number, sample number, time and amplitude attributes .Note that when you bring up the Shot gather display by selecting Trace|Shot gather, the Shot breaks display is rendered in the lower half of your display. The traveltime curve corresponding to the currently selected shot gather (displayed in upper half of display) is highlighted in the Shot breaks display. Whenever you interactively (re)pick a first break for a trace of the current shot gather, that traveltime curve is redisplayed automatically. If you selected branch points for that traveltime curve before repicking first breaks, automatic branch point validation is carried out while redisplaying the traveltime curve. In order to redisplay the whole Shot breaks display, just enter ALT-Y (Trace processing|Refresh breaks display). You may zoom up the Shot gather display to fill the whole screen by double clicking on its title bar with your left mouse key. Double click on the main Rayfract title bar as well to maximize its size.PFN ؀/2z,ǀǑ~+You may process traces for enhanced visibility of first breaks with Trace processing|Trace processing (ALT-M). The dialog displayed when selecting this menu item offers the possibility to interactively specify the following parameters : AGC window, Do AGC for current trace display, Clip amplitude peaks for current trace display, Filter traces, Filter width, Central filter weight, Remove systematic dc offset from traces.@{Lo ׮6Kqy*Gr|L Also, you may carry out semi-automatic first break picking with Trace processing|Automatic picking (ALT-B). The corresponding dialog offers these parameters : Search window width, MinimuN @m propagation velocity, Maximum propagation velocity, First break envelope length, First break stabilization factor.In order to obtain context sensitive online help on these parameters, please tab to the dialog control of interest and then press F1.N Ne Kr|L ׮6Kr|L qy*G׮6KOnce you have specified appropriate parameter values, hit ENTER to carry out the semi-automatic picking. In situations of strong pre-first break noise or weak first break signals, adapt parameters First break envelope length and First break stabilization factor. If this does not help much, you may want to resort to forcing first breaks being picked automatically to be located in the vicinity of a polyline consisting of multiple straight line segments connected to each other, picked interactively with the right mouse button. Move the mouse cursor to the trace located closest to the shot point position, positioning it at a vertical time offset approximating the visually estimated first break time. Then click the right mouse button once. Now move the mouse away from the shot point, i.e. to the left for reverse shots and to the right for normal (forward) shots. Try to follow the visually estimated positions of first breaks, for the traces being crossed with the mouse. Once you detect a systematic change of slope of that direction, click the right mouse button a second time, in order to define the first line segment of the polyline. Once you have done so, automatic picking will be carried out for all traces located in the offset range covered by that line segment. For each such trace, the pick search window will be centered at the linearized time just picked. The window's width will be limited to parameter Search window width, as specified above. Once these traces have been picked for the first line segment, you may define further line segments of the same polyline by moving the mouse still further away from the shot position, and clicking the right mouse button at appropriate offsets. Whenever a new line segment has been picked by you in such a way, the traces recorded at offsets covered by that segment will be picked automatically, as just described for the first segment. Terminate the polyline picking process by clicking the left mouse button. Please note that parameters First break envelope length and First break stabilization factor are regarded during this picking process, while parameters Minimum propagation velocity and Maximum propagation velocity have a meaning if no linearized time has been defined for a trace by picking such a polyline only. In case of low signal to noise ratio or bad traces, we advise to set parameter Search window width to its minimum value of 0.1 msec.P U xWhenever you repick a first break or remap traces to refractors, all depth and velocity sections computed previously are invalidated. If such sections are currently displayed, these windows are shut down automatically. In order to recompute and redisplay these depth and velocity sections, remap all traces to refractors by selecting Trace mapping|Remap all traces in your Shot breaks display or Midpoint breaks display. Then optionally update the weathering velocity specification in Header|Station. Now reselect the appropriate items in the Depth menu and Velocity menu.e.7 <Select Trace mapping|Undo trace mapping and corrections in your Shot breaks display or Midpoint breaks display to internally reset the trace to refractor mapping for all traces and to reset first break corrections for shot position offsets and shot hole depths as computed and applied previously. This gives you the option to restart the weathering velocity estimation and subsequent correction of traveltimes for shot position offsets and . @ hole depths from a clean slate.+ YC TSelect Trace mapping|Display regressed traveltimes in your Shot breaks display to show synthetic traveltimes for the basement (deepest refractor) as computed from the traveltime field characteristic functions resulting from the traveltime field regression (as described by Brueckl, E. 1987). This regression is carried out automatically whenever you redo the Wavefront or Plus-Minus time-to-depth conversion after selecting Trace mapping|Remap all traces as described above.%.~O lInstead of picking first breaks in the Trace|Shot gather display, you may pick in Trace|Offset gather or Trace|Shot point gather displays. Use Arrow keys as described above, for trace and sample navigation. Color traces with menu items in Processing menu. Picking of shear-wave records, with sign-inverted traces recorded for the same shot point, is easy with our Trace|Shot point gather display and appropriate trace coloring with our Processing menu.&Y# A~1 B Smooth inversion:& (HSmooth inversion(G% H , &[HVersion 2.51 and later versions of our software implement a new fail-safe "Smooth inversion" option, for fully automated determination of a 1D gradient initial model and subsequent refinement with WET tomography processing. Start this inversion with Smooth inversion|WET with gradient initial model. See our short manual and tutorial as available at http://rayfract.com/help/manual.pdf for illustrated processing sequences. (GH% H  2 2HH>Once you have completed the first run of our Smooth inversion with default parameters, you may want to run our WET true 2D tomography processing a second time. Specify the same GRADIENT.GRD 1D gradient initial model but increase the WET iteration count to e.g. 100 or 200 iterations. For detailed instructions see e.g. our tutorial http://rayfract.com/tutorials/line01pt.pdf . Increasing the WET iteration count typically helps to increase the vertical velocity resolution, e.g. to obtain a sharper velocity contrast between imaged overburden and basement. Velocity inversions are easier to recognize with an increased WET iteration count as well.(H1% H 2 2_H]zOH>The 1D initial model guarantees that pseudo-2D Delta-t-V velocity artefacts (occurring e.g. in situations of strong refractor curvature / strong lateral velocity variation) are virtually eliminated from the interpretation at an early stage. The pseudo-2D Delta-t-V initial model as determined with our Delta-t-V inversion will show systematic velocity artefacts : too low velocity below anticlines, and too high velocity below synclines. The 1D gradient initial model still shows a good initial traveltime fit, between measured and picked times. This good initial fit is required for WET true 2D tomography processing to have a chance to converge towards a meaningful final model.(1:% H9& HVelocity artefacts are unrealistic imaged velocity variations, caused by the imaging algorithm and not by the input traveltime data. These variations are not necessary to explain the measured and picked input data.(:a% H}X9% HFor a peer-reviewed third-party evaluation of our Smooth inversion method, please see(a% HW2]% dHhttp://rayfract.com/pub/srt_evaluation.pdf .(% H]6 & HThis benchmark study by Jacob Sheehan et al. entitled "An Evaluation of Methods and 6 Available Software for Seismic Refraction Tomography Analysis" has been published in the March 2005 issue of EEGS Journal of Environmental & Engineering Geophysics, ISSN-1083-1363. The paper compares our Rayfract software and Smooth inversion method with OYO SeisImager and GeoTomo LLC GeoCT-II.(^ % HnI6  % HThe 1D gradient initial model is determined automatically as follows :(^  % HJ > W |Pl " " "first, the pseudo-2D Delta-t-V initial model is determined. This will give individual velocity vs. depth profiles, below each profile station.then, the average velocity vs. depth profile is determined, by averaging velocities of the pseudo-2D Delta-t-V initial model over all profile stations, at common depths.finally, this average velocity vs. depth profile is extended laterally along the whole profile. A 1D gradient velocity grid is generated, based on these average velocities.yE  4 8Pl "XTV inversion is disabled automatically, during this procedure.(>  % l(  % l& - , &l]zOIf initial processing with our new Smooth inversion method indicates a sub-horizontally layered subsurface geology without strong refractor relief, you may want to try our Delta-t-V based WET inversion, and compare the resulting interpretations.( U % l- $ 2 2;lRQW1Check option WET Tomo|WET tomography Settings|Scale WET filter height to ensure better overburden resolution and less artefacts at bottom of tomogram.(U L % l+$ w 2 2l]8Check option WET Tomo|WET tomography Settings|Adjust wavepath width for better overburden resolution, for long profiles. Uncheck this option for short profiles with 48 or less receivers, in case of strong topography and for wide shot spacing.(L  % l(w  % l w & lFor comparison of 1D gradient initial model based WET inversion with pseudo-2D Delta-t-V based WET inversion, please see our tutorials( % lU0w % `lhttp://rayfract.com/tutorials/broadepi.pdf ,V1 J % blhttp://rayfract.com/tutorials/depress.pdf andU0 % `lhttp://rayfract.com/tutorials/palmfig3.pdf .(J % l( % ly# h V zGlX"m㦍APlease note that since our Smooth inversion is based on our pseudo-2D inversion, both methods share some parameters. E.g. to limit the maximum velocity exported by Delta-t-V, please select Delta-t-V|Interactive Delta-t-V|Export Options and adapt edit field Max. velocity exported. Confirm with Accept. You don't need to run the pseudo-2D inversion; click on Cancel to abort. To generate tomograms in feet, select Smooth invert|Output inversion results in Feet. For borehole WET options see topic Crosshole survey interpretation.Y  ' HTo check the Delta-t-V and WET settings used for your Smooth inversion, you may review ASCII text file \RAY32\\GRADTOMO\GRADIENT.PAR. E.g. select Start|Run..., enter command line "Notepad" (without the enclosing "") and hit ENTER. Then open file GRADIENT.PAR. Select "File of type" "All Files", in the Notepad Open dialog.(h  % H( 8 % H( ` % H8 A & HIf there is only a moderate degree of lateral velocity variation in your WET inversion output, you may want to consider i` A maging the subsurface based on "Smooth inversion" output averaged with "Automatic Delta-t-V and WET inversion" output. This will give you a reliable background model, overlaid with more speculative local velocity anomalies as obtained with our pseudo-2D Delta-t-V inversion and smoothed / refined with WET inversion. Use Surfer Grid Math as described e.g. in our tutorial(` A % HU0A A % `Hhttp://rayfract.com/tutorials/poisson.pdf (A 'B % HM(A tB % PHand your Surfer 8 manual chapter 18.('B B % H(tB B % H(B B % HPB WlH>T]zOWe recommend to always base your WET tomography inversions on Smooth inversion 1D gradient or Delta-t-V pseudo-2D initial models. If you base your WET inversions on your own or third-party initial models as described above, we cannot give any guarantee regarding the quality of WET output. ( % lf T / ,/lH>If you still decide to build your own initial model as described above, and use this model with our interactive WET tomography processing, please be sure to leave wavepath width and grid smoothing at their default settings. Also, you may need to increase the WET iteration count significantly, e.g. to its maximum allowed value of 999, to make sure that WET output converges towards a realistic model.( | % lT O & ClOur WET tomography processing has been explicitly designed and tested to work with smooth initial models such as obtained with our Smooth inversion. This method gives a good initial fit between modeled and picked first breaks, even in case of velocity inversions. To check the goodness of fit for your own initial model, please select WET Tomo|Forwa| O cE rd model traveltimes... and specify your MODEL.GRD initial model.(| w % lO D & OlThe better the initial fit between modeled and picked first breaks, the higher the chance that WET inversion converges towards a realistic model, in our experience.(w l % l[D % lFor our comments on the recent University of New South Wales thesis of Ramin Nikrouz see(l  % lT/ h % ^lhttp://rayfract.com/tutorials/nikrouz.pdf .( % l(h % lN  1| I Pseudo-2D Delta-t-V inversionC I # @Pseudo-2D Delta-t-V inversion + $TPlease always first invert your refraction data with our fail-safe Smooth inversion method. Smooth inversion guarantees a realistic interpretation, even in case of strong lateral velocity variation. The 1D gradient initial model computed by our Smooth inversion method guarantees that Delta-t-V artefacts (occurring e.g. in situations of strong refractor curvature / strong lateral velocity variation) are virtually eliminated from the interpretation at an early stage. The pseudo-2D Delta-t-V initial model will show systematic velocity artefacts in such situations : too low velocity below anticlines, and too high velocity below synclines. ]I Z f H>s.FIf the Smooth inversion interpretation shows at least some degree of quasi-horizontal subsurface layering, you may then optionally proceed with pseudo-2D Delta-t-V based WET inversion . To start the automated version of our pseudo-2D Delta-t-V inversion, please select Delta-t-V|Automated Delta-t-V and WET inversion .Starting with version 1.30, as released in December 1998, our Rayfract software now also implements the Delta-t-V method as described by (Gebrande and Miller 1985). This turning ray inversion method delivers continuous depth vs. velocity profiles for all profile stations. These profiles consist of (horizontal inline offset, depth, velocity) triples. The profiles are written to an ASCII file which may be processed conveniently with Golden Software's Surfer etc., to produce color-coded inline offset vs. depth velocity contour maps / velocity isolines. The method handles real life geological situations such as velocity gradients / linear increasing of velocity with depth / velocity inversions / pinching out layers and outcrops / faults and local velocity anomalies gracefully. Furthermore, it does not require the user to map traveltimes to refractors at all. Importing seismic data and complementing it with geometry information / traveltime picks is all that is needed. Be sure to do quality control of models obtained by comparing synthetic traveltimes as obtained with our new integrated raytracing algorithm against times as measured and picked (as shown in the Shot breaks display). Default values for the Delta-t-V parameters as proposed by the software automatically will give good results in most cases and no tuning of the parameter values is necessary (but is possible; see below for a description of all parameters). k * Y H>CAlternatively, you may want to have one core drilling site along the profile, in order to check depths delivered by the Delta-t-V method with velocity-depths as reconstructed from the core. Our Delta-t-V method requires 10 or more shots per profile for reliable inversion results. The more shots the better, as long as first breaks are picked carefully. You may want to record uphole picks from such a deep hole bottom, e.g. with the same receiver spread(s) used to record surface shot picks. These uphole picks can then be integrated with surface picks during the WET tomography iZ * nversion. Typically, shot point distances should not exceed 6 times the receiver distance. A ratio of 1:3 would be ideal. You may want to employ an accelerated weight drop of high mobility to reach a high enough number of shots recorded per hour. Be sure to record enough far offset shots (inline offset from the receiver spread by one half to one spread length) in order to reach your targeted depth / increase the maximum depth imaged. Receiver spreads should overlap by a few positions, ideally by up to one half spread length.k4Z  7 To automatically adjust the subsurface velocity model until the synthetic times optimally match the first break times as measured and picked, please employ our new WET Wavepath Eikonal Traveltime tomography processing.Subsequent WET tomography processing makes it less important to tune the Delta-t-V parameters. Default values for Delta-t-V parameters should give acceptable initial subsurface velocity models for WET processing in most geological settings.7; A m EEáYXWhen looking at Delta-t-V output, please be aware that you should give most weight to near-surface imaging. The deeper the structure imaged, the more uncertainty is involved in determining depth and velocity. This is caused by accumulation of modeling errors in the overburden, during reduction of deeper traveltimes to the next lower level ("overburden layer stripping"). These modeling errors may occur if you specify uncalibrated values for parameter Regression over offset stations and other Delta-t-V parameters. As a consequence of these modeling errors in the overburden, deeper traveltimes will be reduced with unrealistic delay times and may be under- /over corrected. This error accumulation may result in unrealistically high/low velocities as imaged beyond a certain depth (e.g. below the bottom of the overburden) or too shallow/deep interpretations. You may want to adjust (increase from default value of 5) the value for parameter Regression over offset stations. and vary parameter CMP curves stack width. Alternatively, make use as appropriate, of parameters MaximF A um valid velocity and Maximum velocity exported (see below) to suppress the consideration during processing and the later output of unrealistically high velocities. The value specified for the former parameter should exceed the value for the latter and maximum velocity estimates obtained as outlined in the following paragraph by e.g. about 500 to 1000 meters per second. fF DE U xs.F"OԀ豶p* You may obtain a first guess at maximum real velocities present in the subsurface by measuring traveltime curve dips as displayed in your Shot breaks display, using a ruler. Alternatively, you may numerically display these velocities at the bottom of your screen during the semi-automatic picking of first breaks in your Shot gather display. Also, you may carry out a conventional traveltime curve processing as described in topics Mapping traces to refractors and Time-to-Depth Conversion, to obtain basement velocity estimates. But note that these velocity estimates will be too low in most cases, since there almost always exists a positive vertical velocity gradient inside the basement itself as well. I.e. seismic velocity increases with depth of penetration into the basement, at the turning points of the seismic rays sampling the subsurface.p,A K D VY %UɀWith option Output Measured CMP Velocities. activated, our Delta-t-V method will combine inverted velocities and depths as obtained during inversion of the CMP sorted and stacked traveltime curves with instantaneous velocities as measured directly on the CMP sorted curves as input to the inversion, at corresponding source-receiver offsets. While disabling this option should deliver more realistic results from a strictly wave propagation physics point of view (as verifiable with raytracing), enabling it may help to enhance the imaging of near surface velocity anomalies. Please be aware that enabling this option means that basement velocities are not corrected for anomalies in the overburden. So if your primary objective is to image anomalies in the near surface / overburden, you may want to enable the option. If your main goal is to make an educated guess at the basement structure and depth, we recommend to disable this option. Note that unchecking this option may deliver better results in case of undulating topography along the line (with static corrections applied, as per default). Also, unchecking may help with inaccurately picked first breaks (i.e. in low signal-to-noise ratio situations), with low velocity contrasts between overburden and basement geological units and if shot positions are not specified exactly. For the sample profile TRA9002 (tra9002.pdf tutorial on our web site), we recommend to disable this option because of the deep valley the profile crosses. This option will be unchecked by default when you create a new profile.0DE N 1 0TPlease note that there will always be a significant mismatch between synthetic and picked traveltimes for some traces when checking Delta-t-V output with subsequent forward modeling i.e. ray tracing though the model obtained, regardless of Delta-t-V parameters chosen. So you may just as well generate pseudo-2D Delta-t-V output with default parameters and then carry out subsequent WET tomography processing to automatically adjust the subsurface velocity model. Even better, use our Smooth inversion method, which builds a 1D gradient initial model virtually free of artefacts. With such a 1D gradient initial model, true 2D WET tomography runs a much lower risk to get stuck in a local minimum of the traveltime misfit function (Schuster 1993, equation 1).BuK 2 h%Uɀ^]Z"sL⪳GH3۲jڇIfq,[a;bBefore inverting the traveltime data with our Delta-t-V method code, you may N 2 toggle the current settings for Delta-t-V options Output Measured CMP Velocities (see above), Output Delta-t-V Results in feet, Output Horizontal offset of CMP pos. in meters, Shot point is zero time trace, Reduced offset 0.0 is valid trace with time 0.0 , Enforce Monotonically increasing layer bottom velocity, Suppress velocity artefacts, Process every CMP offset, Prefer Average over minimum interface velocity, Taper velocity steps at layer interfaces, Smooth CMP traveltime curves, Weigh picks in CMP curves and Regard uphole picks for Delta-t-V inversion as displayed in menu Delta-t-V|Delta-t-V Settings. Options Output Delta-t-V Results in feet and Output Horizontal offset of CMP pos. in meters may not be activated both at the same time._N ܅ K dufVTo interactively invert your traveltime data according to the Delta-t-V method, select Delta-t-V|Interactive Delta-t-V. Wait until the Parameters for Delta-t-V method dialog appears. If you invert the data set for the first time, we propose that you just accept the default parameter values by clicking on button Process CMP sorted traveltime curves. If you are not happy with the output or raytracing shows a significant mismatch between picked and synthesized first breaks, you may change Delta-t-V options (see above) or default parameter values as following and as deemed appropriate :Q2 - \ ܯ;ܯ;Parameters CMP curves stack width and Regression over offset stations let you specify to what degree the traveltime data should be smoothed horizontally and vertically. We advise you to vary parameter Regression over offset stations between values of 5 to 20 offset stations. Generally, smaller values for this parameter will deliver more shallow velocity-depths. For low coverage surveys or situations of high velocity contrasts between clearly recognizable layers, we recommend to set this parameter to a value near the minimum value of 5. Also, vary parameter CMP curves stack width between values of 10 to 25 (neighboring Common MidPoints). One station number interval corresponds to two CMP positions (at positions .0 and at .5).܅ ( y  _oHsg'BGroup box Linear regression method lets you select between the two methods least squares and least deviations. The method specified will be used to carry out a piecewise linearization of CMP traveltime curves, in order to determine smoothed local apparent CMP velocities. When selecting option least deviations, the inversion will take about ten times as long as with option least squares. See (Press et al. 1986) chapter 14 for details. Least deviations will recognize outliers / less relevant data points and give them less weight when modeling / linearizing the trend inherent in the data. Least squares treats all data points with the same priority. You may want to compare least squares output with least deviations output, in situations of high coverage and noisy picks/automatic picking. Save the resulting DELTATV.CSV files to differently named files and then import and process both e.g. with Surfer, see below. Set limits and scale of both resulting contour plots to the same values, optimally fit the contour plots to the screen size and page through the plots with CTRL-TAB, in order to compare them visually.x-- K d[۽Y|jIncrease the value of Weathering sub-layer count in order to obtain slightly slower and more detailed topmost / weathering velocity imaging. As a consequence, synthetic traveltimes as obtained by raytracing through the resulting Delta-t-V model will be slightly slower.Parameter Maximum valid velocity lets you specify the maximum velocity value accepted as valid when processing of ( CMP curves is carried out during the inversion. Apparent CMP velocities as obtained during processing and higher than this value will be skipped. See above.( O l<\c25*VGroup box Process all CMP curves lets you specify the lateral data density of the ASCII file generated. Option process all CMP will process CMP sorted traveltime curves at every CMP location. Option skip every 2nd will process every second CMP only. Use this option in order to reduce computation time for the inversion and the following gridding with Surfer or similar. This may help to achieve a fast turnaround time while iteratively calibrating Delta-t-V parameters against raytracing results or a priori information such as core drilling data, data from nearby construction sites such as tunnels or data from geological maps. ? 2 2 -ڀWhen clicking on button Static Corrections, you may edit the following parameters relevant for correction of first breaks for topography features. The Delta-t-V method works best if all sources and receivers belonging to the CMP gather currently evaluated are located on a dipping plane. So in case of rough topography, you may want to compute and apply refracted wave first break corrections for each source and receiver, hypothetically moving these vertically up or down until they are located on that dipping datum plane. Refracted wave first breaks will be corrected for shot hole depth and topography, while direct wave first breaks will be corrected for shot position offsets including shot hole depth (assuming a straight ray path between source and receiver). The algorithm makes the simplifying assumption that the turning rays as corresponding to refracted wave first breaks reach the receiver vertically from below / dip down vertically from the source. For source and receiver elevations above the datum elevation determined as below, a negative first break correction is computed and applied (hypothetically moving the source/receiver vertically down, onto the datum plane). For source and receiver elevations below the datum elevation determined as below, a positive first break correction is computed and applied (hypothetically moving the source/receiver vertically up, onto the datum plane). , [ % uܢyjGroup box Static first break corrections lets you select between option No static corrections applied and the two computation methods Surface consistent and CMP gather datum specific. See (Frei, 1995) for details. Our CMP gather datum plane is not constricted to a horizontal plane, but will have a constant dip fitting the relevant CMP gather trace specific source and receiver elevations. This is based on the assumption that subsurface geology roughly follows the topography. Also, first break corrections will be as small in value as possible as a consequence. This reduces the danger of over-correcting first breaks for topography features, e.g. if employing a too low weathering velocity for the computation of the datum corrections as described above. We recommend to process each RAYFRACTprofile with two Delta-t-V parameter values sets : the first set consists of the default values as displayed in these dialogs when processing that profile the first time. The second parameter values set consists of the same values as in the first set, except for Static first break corrections : change that parameter to No static corrections applied.d?  { Āi^-Nq%q&ՀƔs.FGroup box Determination of weathering velocity lets you choose between the two options Copy v0 from Station editor and Automatically estimate v0.Parameter Weathering crossover specifies the estimated average crossover distance separating direct wave arrivals from refracted arrivals. You may make an educated guess at this mean,  crossover distance by looking at the Midpoint breaks display (available for full functionality licenses only) or the Shot breaks display. This parameter will be used for Static first break corrections options No static corrections applied and CMP gather datum specific to estimate the near-surface weathering velocity. This laterally varying velocity estimate is required for the computation of shot position offset corrections and static corrections, for direct wave and refracted first breaks; see above.i,  [ $ikX|jParameter Topography filter specifies the filter width used to obtain a smoothed topography in the context of first break correction method Surface consistent, see above.When clicking on button Export Options, you may edit these parameters relevant for determining the format of the ASCII output file DELTATV.CSV, as generated at the end of the Delta-t-V inversion :Parameter Maximum velocity exported lets you specify the maximum value of velocities written to the DELTATV.CSV ASCII file. See above.o  { Ā95W5>eCheck box limit velocity exported to apply a low pass filter to velocities written to file DELTATV.CSV. Check box negative depths to write depth with a leading minus "-" sign to DELTATV.CSV, in connection with radio button depth below topography.Group box Handling of too high velocities lets you specify what should be done with velocities exceeding Maximum velocity exported if check box limit velocity exported is checked. Select radio button set to max. exported if the corresponding velocity value should be replaced with the value specified for Maximum velocity exported, see above. Select radio button do not export if velocities exceeding Maximum velocity exported should be skipped during creation of DELTATV.CSV.[ T v涀95ufGroup box Depth information exported lets you define if either absolute elevations or depth below topography should be exported. Select the appropriate radio button.Once you have edited all parameter values you want to change or to just accept the default parameter values, hit button Process CMP sorted traveltime curves to start the inversion or abort the inversion with the ESC key. Observe messages displayed in the status bar at the bottom of your Rayfract client window. You may switch to other Windows applications while the inversion proceeds. The size of the resulting DELTATV.CSV ASCII file will give you a hint at how many velocity-depth points at how many CMP stations have been obtained. You may want to inspect the file with a plain ASCII text editor in order to check if results have been obtained for most CMP stations./ = HThe inversion routine generates files DELTATV.CSV, MINVELO.CSV etc. You may want to grid both of these, as described below. The DELTATV.CSV file contains average interface velocities, for all CMP's and infinitesimal layers. The MINVELO.CSV contains minimum interface velocities. See entry Z data unit description of the corresponding .PAR file. Both of these .CSV files normally represent good solutions; the DELTATV.CSV velocities are just a bit faster than the MINVELO.CSV velocities.  B 7 < VOnce the inversion has been completed, you may import the generated .CSV file(s) into Surfer or any other scientific data plotting package. You may want to download a free Surfer evaluation license from www.golden.com. Be sure to backup the file and rename it if appropriate, e.g. in another subdirectory \RAY32\LINE14\TOMO and to LINE14.CSV or similar. If you specified absolute elevations above, be sure to set Surfer gridding parameters # of lines in X direction and Y direction to e.g. a value of B 200 to 400. If you leave the default values for these parameters unedited, the grid generated will be too coarse to smoothly approximate the topography as specified in Surfer blanking file SEIS.BLN. Please be aware that later forward modeling of traveltimes by raytracing through .GRD grid files requires the grid cells to be of quadratic shape. Repeatedly adapt Y Dir. # of Lines until the Y Dir. size of the cell (as indicated in the previous column) matches the X Dir. size of the cell as closely as possible. Also, the finer the grid and the higher the number of nodes (rows and columns), the more accurate synthetic first breaks as obtained with raytracing are supposed to be. WET processing time increases with the grid size, of course.( F a QWe recommend to use the Surfer 8 Map|Image Map command, instead of Map|Contour Map as described in our tutorials. Double click on the image map generated, from the .GRD file. Then click on the General tab and the Colors bar. Now click on the Load button and select file \RAY32\REF\RAINBOW2.CLR. If you still need contours, you can generate a separate contour map for the same .GRD file, via Map|Contour Map. Then combine the two maps by pasting them both into a new Surfer Plot Document. Then select both maps with Edit|Select All. Now overlay the two maps via Map|Overlay Maps. Then interactively adjust the scale and the limits of the resulting map, as previously. For details, please see our updated tutorial LINE14.PDF as available at http://rayfract.com/tutorials/line14.pdf .B KJ 7 <% ĝ؀When specifying Surfer section limits in Surfer menu Map (Map|Limits), please be sure to suppress the display of the first five and last five or so stations of the profile. Blanking out these margins at the profile start and end is necessary to guarantee that the depth-velocity information displayed in the Surfer section is based on sufficient coverage of CMP's with first breaks (especially direct wave arrivals). Also, be sure to limit the vertical elevation range / maximum depth shown on the section. The bottom part of the section as displayed with Surfer default section limits will not convey much useful information, and gridding/contouring of the scarce data with Surfer becomes instable. This is based on the fact that ray density in that area is very low in most cases. Only the first breaks recorded for the largest source receiver offsets will penetrate the subsurface to that depth.k:F N 1 0uWe recommend to use the Surfer 8 Matrix Smoothing (Grid filtering) feature, to obtain a more regular subsurface image. This will help especially in case of irregular topography / irregular Delta-t-V output (with static corrections applied). E.g. enter values 1 and 15 for edit fields "Rows on Either Side of Center" and "Columns on Either Side of Center". Our Rayfract Delta-t-V method (with default parameter values) implicitly applies a higher degree of vertical smoothing than horizontal / lateral smoothing, to CMP binned and stacked traveltime curves. If using Surfer 7, please note that if you smooth over too many rows (e.g. more than 3), low weathering velocities as contained in the topmost grid data pixels will be lost and are not recovered during raytracing by extrapolating velocities from lower rows. As a consequence, raytracing will give back too fast synthetic traveltimes. We recommend to use Surfer version 8 Matrix Smoothing (Grid filtering) instead. It preserves data at the topography and at the edges of the grid region covered with velocity data.-KJ + $Use horizontal smoothing aggressively. For a grid of e.g. 800 horizontal by 200 vertical pixels, use a user-defined running average filter of 3 rows vs. 41 columns. This ensures that local Delta-t-V artifacts are filtered out while the general velocity trend with depth is preserved.N Keeping the original velocity is important directly below the topography. The weathering velocity typically increases quite suddenly with depth over just a few rows. That's the reason we recommend to smooth just over 3 rows.LN H ^^]For short profiles with e.g. 24 or less receiver stations, you may want to activate Delta-t-V option Output Delta-t-V Results in feet to obtain a more regular model when kriging/gridding and smoothing Delta-t-V output with Surfer. Then convert the Surfer .GRD file obtained back to meters with Delta-t-V|Convert Grid file between feet and meters... .In situations of undulating line topography, you may want to refine Delta-t-V output with Delta-t-V|Refine Delta-t-V output... . This menu item asks you to specify a Surfer .GRD file as obtained by gridding and smoothing previous Delta-t-V or WET output for the same line and with identical processing options and parameters. In the following, Delta-t-V internal static corrections will be computed by integrating the delay time over .GRD velocity cells at corresponding source and receiver locations (instead of applying the smoothed weathering velocity as estimated during standard Delta-t-V processing; see above). Alternatively, you may specify a Surfer .GRD file as generated by WET tomography processing, e.g. VELOIT10.GRD.y@ 9 @H>For reflection seismic processing, you may obtain a rough estimate of zero offset near-surface vertical velocity vs. two-way time with Delta-t-V|Delta-t-V Velocity vs. Two-way time... .To refine the Delta-t-V output obtained as described above, please proceed as described in topic WET tomography processing.T# P 1 P e Raytracing through Delta-t-V outputI& # LRaytracing through Delta-t-V outputTP 6 I `]zOs.FStarting with version 2.01, RAYFRACT now supports forward modeling of first breaks. The algorithm implemented is the first-order eikonal solver as described by Podvin and Lecomte (1991, 2000). Thanks to this new tool it is no longer necessary to calibrate Delta-t-V parameters against a priori depth velocity information obtained from third party sources such as coring. Just select Depth|Forward model travel times... and then specify the Surfer .GRD grid file to run our new eikonal solver over the depth-velocity model based on previous Delta-t-V output as gridded and smoothed with Surfer. See topic Delta-t-V Inversion for details. Then display modeled traveltimes on top of measured and picked times in the Shot breaks display. Modeled traveltime picks and curves are colored blue. A close match between picked and synthesized times means that parameters used previously to obtain the Delta-t-V output model are reasonable. Default values for these parameters will lead to a good agreement of these two traveltime sets for most profiles, recording geometries and geological settings.( ^ 3 4You will note that the forward modeling algorithm rejects Surfer .GRD grid files with non-quadratic cells. Just regrid the .CSV file with the X/Y Dir. # of Lines as proposed in the message displayed in the status bar at the bottom of the RAYFRACT window.Select forward modeling option Correct all velocities for Delta-t-V systematic error to reduce all grid node velocities as indicated in the Surfer .GRD grid file by 10 percent before running the model through the raytracing algorithm.a(6 9 @QSelect forward modeling option Correct basement velocities for Delta-t-V systematic error to reduce basement grid node velocities as indicated in the Surfer .GRD grid file by 15 percent before running the model through the raytracing algorithm. "Basement" just means high velocity regions, as indicated by values in the grid file.Select forward modeling ^ option Skip every 2nd shot for raytracing to speed up the forward modeling process and optimize the amount of information displayed in the Shot breaks display for high coverage surveys.o^ e + $Please note that for the forward modeling algorithm to work reliably, the Surfer grid should not be too coarse. Increase Surfer gridding parameters X/Y Dir. # of Lines as necessary, until there is a reasonably close match between picked and modeled traveltime curve features. Regard the limit of 640'000 nodes : this is the maximum number of nodes our eikonal solver will accept, to reasonably conserve RAM memory and hard disk space available. 600 columns versus 200 rows or similar may be a reasonable setting. For the free limited trial, try e.g. 300 columns vs. 100 rows (regarding the limit of 100'000 nodes).J 13 Ʌ WET tomography processingP-e # ZWET Wavepath Eikonal Traveltime tomographyH G E X EStarting with version 2.11 as released in February 2001, Rayfract now supports refining Delta-t-V output with our new WET Wavepath Eikonal Traveltime tomography processing (Schuster 1993; Watanabe 1999).Wavepath tomography as implemented in our software allows the integration of "uphole picks" from shots positioned at the bottom of deep shot holes with first breaks picked for surface based (or shallow shot hole) shots. Please note that these deep shot holes need to be positioned inside the receiver spread(s) used for recording surface based shots. You can record both surface picks and uphole picks with the same receiver spread(s). To ensure that the WET processing can work with uphole picks for a deep shot hole, make sure that the Delta-t-V output covers the bottom of such a deep shot hole. You may increase the depth penetration of the Delta-t-V output by recording more far offset shots, at larger offsets. Be sure to mark a deep shot hole shot as such by entering an uphole time correction term different from 0.0, in Header|Shot. Integration of such uphole picks with surface picks should considerably increase the resolution of and confidence in the lower half of the WET processing output (i.e. tomograms obtained). Positioning two deep shot holes at the profile start and at the profile end (just inside the receiver spread) may help to make sure that the depth coverage as obtained with our Delta-t-V method (by recording and picking/processing far offset shots) is not lost again during WET processing. 2 ' Please note that in order to be able to use Delta-t-V method output as a starting model for WET tomography inversion, you need to configure the Delta-t-V method as follows (as per default) :qG > LP:H"Select Depth|Output Horizontal offset of CMP pos. in meters or Depth|Output Delta-t-V results in Feet. $2  Z P:Hl "ik95XDelta-t-V export options : if you select option depth below topo or do not specify any topography i.e. set the topography to 0.0, you need to select negative depths in the same dialog.* / ' P:H( W % H`/ P n!H$.2]8RQW1Next, you may toggle the current setting of WET Tomo|WET tomography settings option Write grids for every iteration. Set options WET Tomo|WET tomography Settings|Adjust wavepath width and WET Tomo|WET tomography Settings|Scale WET filter height as needed.(W % H> ) P nH&?>׀dNow select WET Tomo|Interactive WET tomography... to display the WET parameters dialog. Click on button Select to specify the starting model. Click on button Edit velocity smoothing to specify param ) e eters for smoothing the updated velocity grid model as obtained after each tomography processing iteration. Click on button Edit grid file generation to specify what kind of intermediate Surfer formatted disk grid files should be generated and kept by the tomography processing.( Q % H) " 2 2?H]vPOnce you have reviewed and optionally have adapted above parameters, click on button Start tomography processing to start the WET tomography processing.(Q J % HT"  , &HOnce the tomography processing has terminated a corresponding message will be displayed in the status bar at the bottom of the Rayfract window. The updated velocity model grid as obtained after each iteration is stored as disk file VELOIT1.GRD for iteration 1 etc. . These Rayfract generated and Surfer .GRD formatted files will be located in the same directory as the one holding the starting model, as specified above. To obtain a velocity tomogram, just contour and plot the corresponding VELOITXX.GRD file with Surfer version 8 via Grid|Image and contour velocity and coverage grids.(J  % H>  h }HXf:mcxRQW1Please note that you may specify initial model .GRD files / velocity models as obtained by previous WET tomography runs, i.e. refine the output of earlier WET processing. You can do the first run (ten iterations) with velocity smoothing option full smoothing, and then carry out a second run (another 10 iterations) with velocity smoothing option minimal smoothing. You may want to further increase near-surface resolution (at the expense of more artefacts in the obtained "basement" image) by selecting option Manual specification of smoothing filter and then decreasing the half width and possibly half height of the smoothing filter. Since version 3.06 we scale WET smoothing filter height with depth below topography per default, so manual adjustment of the smoothing filter has become less important.(  % H(  % H & iHIf your WET tomography processing run terminates with a message "Updated velocity model has gaps" or you are not satisfied with the tomogram obtained please proceed as follows :( % H ` P:Hl "GhRQW1]8make sure that you are running the latest version of our software. Our WET inversion method has been made more robust in versions 3.05 and 3.06 of our software, by setting WET parameter Degree of differentiation of Ricker wavelet to 0 per default, and with new options Scale WET filter height and Adjust wavepath width. See http://rayfract.com/help/release_notes.pdf .- N R r]P:H"'K&?if your seismic refraction line has one or more gap(s) without coverage, please activate option Allow gaps in coverage of velocity model grid columns in dialog Edit Forward Modeling Parameters which appears when you click on button Select of the main WET tomography parameters dialog.P @ H ^P:Hl "check if the first breaks have been picked correctly at the corresponding profile positions. Use our Trace|Offset Gather display to check your first breaks for consistency regarding reciprocal traveltimes. For the same offset and midpoint (station number), first breaks picked (red crosses) should collapse onto a single pick. If these are displayed on the same trace but vertically offset from each other, such picks violate the traveltime reciprocity principle which states that traveltime is invariant to exchanging source and receiver between two constant measuring stations. N @ e c#N oA @ NIP:H"otherwise make sure that the profile topography and recording geometry (shot point coordinates : specify lateral offset in Header|Shot) has been specified correctly. Missing or incorrectly specified topography may cause the imaging of non-existent overburden anomalies; see below.H @ )D r P:Hl "T]zOj]zOFuse our Smooth inversion, to obtain a 1D gradient starting model virtually devoid of velocity artefacts. For our pseudo-2D Delta-t-V inversion, you may want to use a different Surfer gridding method than the default kriging method. Specify your preferred gridding method via Delta-t-V|Interactive Delta-t-V|Export Options|Gridding method. Confirm with Accept button. You can then abort the interactive Delta-t-V inversion with Cancel button. Now regrid the DELTATV.CSV generated during an earlier inversion, with Grid|Grid and image Delta-t-V .CSV file... .{oA E O lR:Hl "Wif the vertical velocity variation is too smooth and does not indicate any sharp velocity increase at the top of the basement, you may want to redo the WET inversion with WET Tomo|Interactive WET Tomography... and increase the WET iteration count parameter to e.g. 100 or 200 iterations. See our tutorial http://rayfract.com/tutorials/line01pt.pdf for instructions.))D F & HlnE G V zP:H"^*']8overemphasized near-surface anomalies may refract the modeled wavepaths for larger offsets at a too shallow depth. You may want to decrease WET Tomo|Interactive WET tomography|Wavepath width interactively by 35%. For long profiles and dense enough shot spacing, enable WET Tomo|WET tomography Settings|Adjust wavepath width to avoid these artefacts.)F H & HlvG K b P:H"^*'GhRQW1]8for S-wave surveys and slow P-wave surveys with maximum time picked for inline shots exceeding 200 msecs. and with overemphasized near-surface anomalies, you also may need to decrease WET Tomo|Interactive WET tomography|Wavepath width interactively by 35%. Otherwise WET output may show wavepaths following a high-speed skeleton with slow background velocity cells in the overburden, especially with a high number of WET iterations. Also, decreasing the WET wavepath width may result in a better match between picked and modelled times. Decreasing the wavepath width has become less important since the release of versions 3.05 and 3.06 of our software, which set WET parameter Degree of differentiation of Ricker wavelet to 0 per default, and offer new options Scale WET filter height and Adjust wavepath width. See http://rayfract.com/help/release_notes.pdf * H L ' P:H4K ?O A PHCIf you are not satisfied with the depth penetration i.e. the maximum depth imaged with the resulting WET tomogram, please note the following :Far offset shots into one receiver spread per Rayfract profile cannot be used for WET tomography because the all-important local weathering velocity cannot be determined, at these far-offset shot points. Because there are no receivers there. Extrapolation of the weathering velocity determined at the first/last receiver to these far offset shot points is not feasible, since the weathering velocity typically varies laterally to a large degree. To reach a deeper penetration, you need to employ multiple, overlapping receiver spreads. See topic Overlapping receiver spreads. Also see our tutorial ( L gO % HY?O ' Hhttp://rayfract.com/tutorials/tra9002.pdf and our client recording geometry samplegO e (gO 4 % HL' % NHhttp://rayfract.com/help/overlap.pdf(4 % H] + & H. Basically you need to make sure that the "far offset" shot locations for one receiver spread layout are "inside" another receiver spread layout along the same line. And receiver spread layouts employed along the same "line" need to overlap with both their preceding and their following spread layout, at a few common "active" receiver stations.( S % H(+ { % HNS Ʌ 2 29HIf WET aborts with a status bar message "Error encountered while opening/writing disk file ...", please run CHKDSK /F ... . Then make sure that the hard disk drive / partition holding your \RAY32 profile subdirectory has property "Compress drive to save disk space" disabled. Right-click on the drive symbol in an Explorer window and select menu item "Properties", to display the Properties dialog. If drive compression is enabled, uncheck the box and click on button "Apply" to uncompress existing files. If this does not help, make sure to disable any backup utility which might access Surfer .GRD files and .PAR files as generated by our WET inversion. And avoid browsing profile subdirectories GRADTOMO, HOLETOMO and TOMO in Windows Explorer or a similar utility, while WET is running.H{  1 Midpoint breaks displayO Ʌ ` D Vĝ؉'B Midpoint breaks displayDisplays first breaks in a Common Mid Point (CMP) versus offset coordinate system. Open this display with Refractor|Midpoint breaks. At each CMP (horizontal axis, in station numbers), a local coordinate system is appended, with its origin at that CMP. It has recording time as horizontal axis (not displayed; overlaps CMP station number axis) and unsigned shot point to receiver offset as vertical axis. In each local coordinate system, one CMP traveltime curve is displayed. The curve is constructed by connecting first breaks picked for traces mapped to that CMP and with adjacent unsigned offsets by straight line segments. Traveltime curves for adjacent CMP positions are binned and stacked according to parameter value CMP Stack Width.  X 5 8HThe instantaneous velocity as directly available from the local traveltime curve dip (at specific offset and CMP) is less dependent on the refractor dip than velocities as inferred from shot sorted traveltime curves. Also, the vertical plotting of traveltime curves makes it easier for the eye to recognize gradual velocity variations.You may semi-automatically assign first breaks to refractors (based on instantaneous velocity) with ALT-M.(` % HMX ͋ 13H͋  " Mapping traces to refractorsB  # >Mapping traces to refractorsk͋ ր s.F艀u|Manually assign traces to refractors by interactively picking branch points for single shot sorted traveltime curves, in Shot breaks displayIf you are interpreting a low coverage seismic refraction profile (e.g. less than 20 shots recorded), or you want to have complete control over the process of assigning traces to refractors for single shot sorted traveltime curves, please select Refractor|Shot breaks. This display visualizes first breaks picked for all profile traces in a conventional Shot breaks display. Select a single shot sorted traveltime curve with F7/F8 function keys. Then move the vertical pick bar horizontally with your move cursor left/move cursor right keys (left arrow key/right arrow key), until it is located at an assumed branch point for the currently selected (highlighted) traveltime curve. Finally assign the branch point to t hat location with CTRL-F1 (first branch point) or CTRL-F2 (second branch point). The first branch point (displayed as an outlined square) separates direct wave first arrivals from first breaks critically refracted by the first refractor. The second branch point (displayed as a filled out black square) separates first breaks critically refracted by the first refractor from breaks critically refracted by the second refractor. Once you have defined branch points for both forward and reverse shot directions of the currently selected traveltime curve, please select the previous/next traveltime curve with F7/F8. At this point of time, first breaks of the formerly selected traveltime curve are mapped to refractors, according to the branch points specified above. Any error conditions relating to your branch point specification will be indicated on screen consecutively.& # G 3 4)HHandling of pinching out weathering layer/first refractor (3-layer case) : if the weathering layer pinches out, specify the second branch point only. If the first refractor pinches out, specify both branch points at the same profile position (for same shot direction). @ N=HIn order to delete one/all branch points picked for a traveltime curve, select that curve with F7/F8. Then move the pick bar to the left/right of the shot's shot point, depending on whether you want to delete a branch point related to first breaks recorded in the reverse/forward shot direction. Finally, press Delete-CTRL-F1 for deleting branch point 1, or Delete-CTRL-F2 for deleting branch point 2.F p HIn order to remap all traces to refractors based on branch points specified interactively as described above, just select Trace mapping|Remap all traces, while the Shot breaks display is activated. If you select this menu item with the Midpoint breaks display currently activated, the Trace to refractors mapping parameters dialog will be shown instead (see below). Whenever you repick a first break or remap traces to refractors by repositioning branch points as described above or semi-automatically mapping traces to refractors in the Midpoint breaks display, all depth and velocity sections computed previously are invalidated. If such sections are currently displayed, these windows are shut down automatically. In order to recompute and redisplay these depth and velocity sections, remap all traces to refractors as just described. Then optionally update the weathering velocity specification in Header|Station. Now reselect the appropriate items in the Depth menu and Velocity menu, to redo the time-to-depth conversion and redisplay the resulting sections..( % H( % H( % H ) KHSemi-automatically / iteratively assign traces to refractors by specifying a typical 1D velocity model and fitting mapping parameters, in Midpoint breaks display( % H0 1 /HƔ㩆Љ_جFÀ'Bu|2ZYour Rayfract software is optimally suited to process first breaks gathered from high coverage seismic surveys, e.g. from seismic reflection surveys. With the term "high coverage", we mean lines with more than 20 shots recorded per profile, and with a shot fired at every fourth receiver position, or with an even closer spacing of shot points., e.g. at every second receiver position. In order to view the first breaks for all traces of such a survey in a CMP sorted display, please select Refractor|Midpoint breaks. You will see your first breaks displayed in a Midpoint breaks display. This display has been des 1 cribed by Gebrande and Miller (Gebrande and Miller, 1985). Its advantage when compared to the traditional shot traveltime curve display is based on the fact that the influence of the dip of layers on the traveltime curves is greatly reduced in the CMP gather display (Rhl, 1995). Note that apparent CMP velocities will be incorrect by about ten to twenty percent at locations of strong refractor curvature, however. This typically occurs at the bottom of narrow/steep synclines and at the top of narrow/steep anticlines. Also, this display offers the possibility to uniquely map profile position (i.e. station number) to crossover distance, for each refractor. As a consequence, crossover distances (offsets where head wave first breaks from a deeper refractor overtake head wave first breaks from a shallower refractor or direct arrivals) may be identified more easily, via systematic discontinuities in slope of CMP traveltime curves (abrupt changes of slope). We will from now on call the location of such a discontinuity a branch point. A traveltime curve mapped to refractors is separated by branch points into segments. First breaks contained in one segment are all mapped to the same refractor. Such a segment is commonly called a refractor branch (located on a traveltime curve).( Y % H=1  cH*M?C]áxG坉v։◜㧉{&dX]*M?Once you have opened your Midpoint breaks display and reviewed your traveltime field, press ALT-M to display the Trace to refractor mapping parameters dialog. It enables you to interactively set the following important processing options and parameters : Direct wave visible , Refractor Count, CMP Stack Width, Regression Receiver Count, Direct Wave Offset Delta, Refracted Wave Offset Delta and Upper Layer Velocity Limits for Weathering and Refractor 1. Activate check box Direct Wave if receivers and shot points. are spaced closely enough to each other, so that the first few receivers next to a shot point record the direct wave as a first break.(Y  % H3 S tHĝ؉'BƔ2ZCMP Stack Width (valid values : 1 to 25) defines how many adjacent CMP positions (centered at the CMP position currently being evaluated) are regarded when constructing a CMP traveltime curve This stacking is done when mapping traces to refractors in the Midpoint Breaks display and when determining CMP intercept times and apparent velocities from first breaks assigned to the same refractor branch during CMP Intercept Time Refraction time-to-depth conversion.(  % H  M h1H'Bv։◜㧉Regression Receiver Count (valid values : 3, 4 or 5) specifies how many adjacent receiver positions with first breaks recorded (on the same CMP traveltime curve) are minimally considered when determining a local apparent CMP velocity (for a given CMP point, and a given offset). Velocity estimation is done by carrying out a least squares linear regression through these first breaks. For medium coverage data (e.g. less than 10 first breaks, per CMP curve), a value of 3 is recommended. For high coverage data, a value of 4 may be more appropriate (if offset differences between adjacent first breaks on the same CMP curve are small enough). The actual number of receiver positions employed for local traveltime curve linearization may be higher than the minimum value specified here, depending on the values specified for parameters Direct Wave Offset Delta and Refracted Wave Offset Delta, see below.( & % H- _D w m Hvր◜㧀2Zu|FÀDirect Wave Offset Delta (valid values : 3 to 10) and Refracted Wave Offset Delta (valid values& _D : 3 to 20) specify the offset range (in unsigned shotpoint-to-receiver offset station numbers) being considered when determining a local apparent CMP velocity, for a given CMP position and offset. Direct Wave Offset Delta is relevant for small shotpoint-to-receiver offsets, when mapping the weathering layer. Refracted Wave Offset Delta applies to all other, larger offsets. Since velocity contrast between weathering layer velocities and refractor velocities is usually quite high, but coverage of the weathering layer refractor branch is short, a value of 3 to 5 may be most appropriate, for parameter Direct Wave Offset Delta. If velocity contrast between refractor 1 and refractor 2 velocities is small, or if refractor 1 contains local velocity inversion zones, a value of 15 to 20 may be appropriate, for parameter Refracted Wave Offset Delta. This high value / long offset range may be necessary in order to cleanly detect branch points (i.e. systematic apparent velocity changes, identifying crossover distances separating refractor 1 branches from refractor 2 branches).(& D % H;_D H V zwH{&dX]'BThe next two editable control fields Weathering and Refractor 1, contained in group box Specify Upper Layer Velocity Limits, specify a 1D velocity model. For a 2-layer case, just the first value is needed. The corresponding refractor velocity intervals, as defined by these limits, are used to map an apparent CMP velocity, estimated as described above, to a refractor. Velocity inversions are not supported, i.e. it is assumed that the speed of refractor 2 is strictly higher than the speed of refractor 1, and that the speed of refractor 1 is strictly higher than the weathering velocity (speed of direct wave), at one CMP position. When regarding one CMP traveltime curve, it is assumed that apparent CMP velocity strictly increases with offset (between shot point and receiver pairs, mapped to that CMP).(D @H % H H LJ 2 2HThe bottom most three static (read only) text fields, contained in group box Median Layer Velocities Detected, display the median refractor velocities detected by local velocity estimation as described above, over the whole profile. These are output only fields. They may serve to iteratively improve your 1D velocity model, as specified above, however. Once you have (re)assigned traces to refractors, redisplay the dialog with ALT-M and inspect these median values.(@H tJ % HR&LJ L , &MHWhen you have entered correct values for all input fields of dialog Trace to refractor mapping parameters, press ENTER to have the system accept these values and to carry out the automatic assignment of traces/first breaks to refractors, based on parameter values entered. Traveltime curve segments assigned to the weathering layer are displayed in yellow (orange if your graphics card is configured to display more than 256 colors). Segments assigned to refractor 1 are displayed in red. Segments assigned to refractor 2 are displayed in green.(tJ L % H)L O n wH@_ }W+j%Once you have mapped first breaks to refractors in such a way, you may want to laterally smooth the crossover distances (color boundaries) obtained, for each refractor. Press ALT-G in order to do so, or select Trace mapping|Crossover processing. The dialog displayed when doing so offers these parameters : Smooth crossover distances, Overburden filter, Basement filter, Offset limit basement coverage, Offset limit.(L ?O % HO E Z AHpu|'Bt>You may scale/zoom the display via the Display parameter dialog (bring up with ALT-P). Edit field ?O E Reduction velocity lets you zoom the slope of CMP traveltime curves. Zoom the reduced time axis of local CMP coordinate systems, by pressing CTRL-F1 once or twice, until branch points (discontinuities in slope, per CMP traveltime curve) are clearly visible. See Dialog box control and function keys(?O m % HVE  V zHu|'BAn optimum mapping of first breaks to refractors has occurred when refractor limits detected (changes of colors) closely agree with the location of branch points (identified by systematic changes in slope, in traveltime curves), for as many CMP traveltime curves as possible, along the whole profile. If refractor limits are systematically located above branch points, increase the refractor's velocity limit, in the corresponding edit field in dialog Trace to refractor mapping parameters. If refractor limits are below branch points, decrease the corresponding velocity limit.(m A % H " B R?H{V'!You may also want to select Refractor|Shot breaks, in order to display your traveltime field in a more conventional way. You may page through traveltime curves with function keys F8/F7. Furthermore, you may display your traveltime field in a coordinate system with CMP station number as horizontal axis and recording time as vertical axis. Common offset traveltime curves displayed connect first breaks belonging to shot receiver pairs with constant unsigned offset along the profile. In order to do so, just select Refractor|Offset breaks. This kind of display also lets you guess at refractor dip and shape, even before carrying out time-to-depth conversion.IA k 1,} k QTime-to-depth conversion>" # 6Time-to-depth conversion1k ڊ | ƀk u|{Once you have iteratively reached a satisfying mapping of first breaks to refractors, you may carry out the time-to-depth conversion. Note that Depth menu items are enabled only if you either (re)mapped all traces in the Shot breaks display or in the Midpoint breaks display, via Trace Mapping|Remap all traces. If you did the mapping in your Midpoint breaks display, select Depth|CMP intercept time refraction (see paragraph CMP intercept time refraction processing below). If you manually selected the branch points in your Shot breaks display, proceed by selecting menu items Plus Minus or Wavefront, see paragraph Plus-Minus and Wavefront processing below.M r K d ;WWhen displaying sections on screen, you may lay out up to three sections adjusted vertically and displayed below each other by selecting Windows|Tile horizontally. Be careful to specify the same profile section limits for all three sections. These limits may be specified in the Display parameters dialog for each section (ALT-P).If you lay out more than three sections with option Windows|Tile horizontally, these will be displayed the same way as with option Windows|Tile. So close the less significant sections, regarding your current interpretation needs, and retile.2ڊ _ _جRD̀CMP Intercept Time Refraction processingOnce you have selected Depth|CMP Intercept Time Refraction, time-to-depth conversion is carried out, as described by (Rhl, 1995). Please note that the accuracy of refractor depths and velocities obtained is limited in case of strong refractor curvature. Once the resulting depth section is displayed, select Depth conversion|Depth conversion (ALT-M) in order to display the CMP Model Parameters dialog.@r G \5z[m1_جParameters limit " maximum basement velocity and Maximum basement velocity allow applying a low pass filter to CMP Intercept Time Refraction velocities estimated for the basement. When the estimated velocity at a station number exceeds the maximum velocity specified, no velocity and depth estimations are output for that station. Velocity and depth are interpolated/extrapolated from neighboring stations with valid results, instead. This may help in situations of strong refractor curvature.\  L O l$#7pfp;Parameters Overburden filter and Base filter width specify widths of smoothing filters (in station numbers; running average), for smoothing elevation and velocity of refractor 1 or 2, respectively. You may want to increase the default values (5, 10) to higher values, for difficult data and strongly undulating apparent refractor topography (e.g. 7, 12 or even 10, 15). Parameter Degree of Surface Consistency specifies to what degree the smoothed surface of refractor 1 should follow the line's topography.3x  D ;WtDwQ_ |€l~U3.̝,akv1{KD$tSelect Depth conversion|Depth display (ALT-P) in order to display the Display parameters dialog. Use controls Minimum station number and Maximum station number to specify the station number interval displayed. For depth sections, use controls Minimum elevation and Maximum elevation, to specify the elevation interval displayed. For time and velocity sections, use parameters Minimum velocity or time and Maximum velocity or time in order to define the vertical data value range displayed. Scale your section plot with parameters scale, vertical exaggeration and vertical scale."L ހ5|\s J _ج豶pAlways be sure to process your data with all three of the above methods (CMP Intercept Time Refraction, Plus Minus and Wavefront). Then compare the resulting depth and velocity sections, at the same scale. Plus Minus has a systematically lower lateral resolution when compared to the Wavefront method, because it basically assumes that critically refracted rays emerge vertically from the refractor. The error caused by this assumption increases with increasing overburden thickness or decreasing velocity contrast, between the layer above the refractor being mapped and the refractor itself. CMP Intercept Time Refraction has systematic problems in case of strong refractor curvature. Also, CMP Intercept Time Refraction will give you fast results, but may not be as reliable as Wavefront for data sets with bad first breaks, since Wavefront iteratively minimizes first break picking errors by first carrying out a regression over the whole traveltime field, for each refractor. This regression is expensive regarding processing time, however. For 30,000 or 40,000 traces, it may well run for a few minutes, on a Pentium 133 MHz system. It will take more time for complex / strongly undulating target geology, long high coverage profiles, low quality first break picks and sub optimal traces to refractors mappings (see Mapping traces to refractors above).+O l_جC]TIn case of strongly undulating refractor topography, refractor elevations as reflected by resulting CMP depth sections will systematically differ from elevations displayed in resulting Wavefront and Plus-Minus depth sections. Furthermore, low velocity contrast/diving wave situations and complex geologic target situations in general may lead to these variations in results. You may want to remap traces to refractors in order to minimize variations between different methods. Also, you may want to reduce the number of refractors being mapped from the default value 2 to the new value 1. See parameter Refractor Count in Mapping traces to refractors above. Above all, we strongly advise you to apply our Smooth inversion method (Smooth inversion|WET with 1D gradient initial model) if coverage is high enough (at least about 5 to 10 shots per receiver spread) in such difficult situations.&O Q# N+1. @Uphole shots and uphole picksC Q @# @Uphole shots and uphole picks @QB4 6w Uphole picks for seismic traces recorded with surface based receivers for deep uphole shots are very useful during tomography processing to increase the degree of angular coverage with wavepaths, the resolution in the lower half of the depth section and the depth coverage. Since the tomography processing can use shots situated between receivers (or maximally offset from the first / last profile receiver by two station number intervals) only, deep uphole shots positioned at profile start and profile end can increase the depth coverage in tomograms obtained considerably. A prerequisite is that the Delta-t-V output covers these uphole shots at their corresponding shot depths, however.X @FM hECIf you enter a non-zero value (in millisecs.) into shot header edit field uphole time correction term, the corresponding shot is considered as an uphole shot, i.e. as shot from a deep shot hole. The deep shot hole locations need to tie in with the 2D surface based seismic line, i.e. situated between receiver stations or offset from the first or last profile receiver by an inline distance of maximally two station numbers. It is assumed that uphole picks for each uphole shot have been recorded with a surface based 2D receiver spread which is part of (i.e. runs in the same line direction and overlaps with) the 2D surface based seismic line. The surface based 2D seismic line consists of the (overlapping) receiver spreads used to record surface based shots (or shot from shallow shot holes, but with an uphole time correction term 0). *B@Jv UE s.FE豶pu|TUphole picks i.e. first breaks of uphole shot traces are corrected by the software for the hole depth by addition of the uphole time correction term when shown in the Shot breaks display. You may fit in these uphole travel times related to one uphole shot with other traveltime curves in the Shot breaks display by adapting the uphole time correction term of that uphole shot iteratively. You may then process the traveltime data with conventional methods, i.e. map traveltimes to refractors etc. Please note that you are not required to pick branch points i.e. map first breaks to refractors for uphole shots. Do so if you feel that the uphole time correction term for such shots is plausible only. The preferred way is to proceed with our fail-safe Smooth inversion, however. /FLU x_ FÀ -ڀbH>Please note that direct wave first breaks for uphole shots are NOT considered by conventional time-to-depth conversion methods. The Delta-t-V method will regard an uphole pick if the unsigned trace offset (from the top of the shot hole to the receiver) equals or exceeds the Crossover distance (as specified in the Delta-t-V method Static Corrections dialog) and if Delta-t-V setting Regard Uphole picks for Delta-t-V inversion is checked only. On the other hand all uphole picks ARE considered during WET wavepath tomography processing.@Jԁo + b H>Since optimally guessing the uphole time correction term AND at the same time setting the Crossover distance to a reasonable value is a bit of a lottery, uphole picks are regarded for Delta-t-V inversion optionally only. The setting of Delta-t-V option Regard uphole picks for Delta-t-V inversion (in menu Depth) is unchecked i.e. false per default.Be sure to correctly specify the depth of the shot below surface with shot header edit field shot depth. This value is crucial for correct forward modelling of wave propagation, during tomography processing. The uphole time correction term is not used for tomography processing and is used to display picked and modeled uphole picks consistently LԁQwith picks for surface based shots (i.e. used for correction of uphole picks for uphole shot depth) in the Shot breaks display only. Also, make sure that the Delta-t-V output covers the uphole shot locations at the shot depth. Otherwise such uphole shots cannot be considered during WET wavepath tomography processing. You may need to record more shots at larger / far offsets to reach sufficient depth coverage with our Delta-t-V inversion method.&L# [*ԁU1= UMulti-user access to LAN profile databasesP-# ZMulti-user access to LAN profile databasesU- ({Starting with our Rayfract 32-bit version 2.34 as released in March 2002, we now support installation and access by multiple users, of profile databases on networked LAN (Local Area Network) hard disk drives/partitions. You may purchase more than one end user license to our Rayfract software. Each purchase of an additional license will give you an additional WIBU-KEY dongle. Exactly one end user may start up Rayfract 32-bit from each PC / workstation with a WIBU-KEY connected locally. Profile databases may be created on networked LAN drives. The software ensures that at most one user works with a specific LAN profile database at all times. If a second user (from another workstation) tries to open the same LAN profile database, he will receive a notification that the database is currently being worked on by another user. He may then either choose to wait until that other user is done, or cancel the request to work with that database.d+ $This multi-user collision prevention mechanism has been implemented with a file lock mechanism. The first user who opens a particular database causes the Rayfract software to create a lock file named SEIS32.LCK in the corresponding profile database directory. For all other users who try later on to open the same LAN profile database, the software will discover that this SEIS32.LCK file exists already. Access to the database will be allowed for one of these other users once the first user closes that LAN profile database only. At that time, the software will delete the SEIS32.LCK file automatically.+ $iThe software will automatically detect if the user i.e. workstation who first opened a LAN profile database has crashed. That workstation normally will rewrite the SEIS32.LCK LAN file once every five seconds. As a consequence, the "last modification" timestamp will reflect the time of that rewrite and will be updated all five seconds. Whenever another user tries to open the same LAN database, and the software finds that the SEIS32.LCK file exists already, it will wait for ten seconds and verify that the timestamp of SEIS32.LCK has been updated. If this update is not detected i.e. if the "last modification" timestamp remains unchanged, the software assumes that the user who first opened the LAN database has crashed. Rayfract 32-bit will then display a corresponding message and prompt the user if he wishes to proceed with deleting (and then recreating) the SEIS32.LCK file and then opening the LAN database as the new "first user".% Please note that this lock file mechanism will work with an unlimited number of users / workstations i.e. is not limited to just two users.X' 1* VGWIBU dongle setup and printing sectionsM*V# TWIBU dongle setup and printing sections d< F A few notes concerning printing of Gather displays / Refractor displays / Depth and Velocity sections :When issuing a print command from Rayfract (selecting a window as current display, selecting File|Print), please wait until the printing process has finished, before you proceed with interacting with Rayfract. Otherwise you may witness messages indicVdating failure of communication, between Rayfract and your LPT parallel port WIBU key.2V7 <Please note that when your current printer driver drives a plotter, i.e. does not support bitmap display, Rayfract needs specific plotter drivers in order to render axis titles. When running under Windows 95/98, Rayfract assumes that the HP 7550A printer driver is installed, set up in landscape mode and with page size A3 selected. When run under Windows NT 4.0 Workstation, Rayfract assumes that the HP-GL/2 Plotter driver is installed, set up in landscape mode and with page size A3 selected. These drivers are accessed by Rayfract in order to render and rotate axis title text, for output on plotters. If they are not installed or not configured correctly, the printing process will abort and a corresponding message will be displayed on screen.`d'1 0ƒiYou may generate HPGL / HP-GL/2 or PostScript files by selecting the appropriate Windows printer driver (e.g. HP 7470A or HP7475A for HPGL; HP-GL/2 Plotter for HP-GL/2; HP LaserJet IIISi PostScript for PostScript) and then setting up these drivers for output to file. See your Windows operating system documentation. Make sure that the page size selected provides enough space for the section size, as determined by your horizontal and vertical scaling of the plot. Under Windows NT 4.0 Workstation only, you may select e.g. the HP-GL/2 Plotter driver, in order to generate HP-GL/2 format plot files.`+ &Alternatively, and to document error messages, you may generate screen dumps as follows :' Pl " " " " " "click on the "Maximize" rectangle at the right upper corner of Rayfract windowmaximize the targeted display (shot gather, depth section etc.) as wellpress ALT-PRTSC (PrintScreen) key combinationselect Start menu item Run... and enter command "MSPAINT.EXE"paste screen dump into MSPAINT document with CTRL-Vnow save the Paint "Untitled" document as .JPG file(% l& -lAlternatively to MSPAINT.EXE, paste the screen dump e.g. into an Adobe Photoshop document, Microsoft Word or Golden Software Surfer plot document.(% l, &lIf after (re)installing our Rayfract software on your PC, the software displays an error message "Program needs WIBU-BOX with ...", and you are using a USB port WIBU key on this PC, please proceed as follows :(% l$x &Pl " " " " " " " "remove all WIBU-KEY dongles from your PCselect Start|Control Paneldouble-click on the WIBU-KEY applet iconleft-click on small icon to left of dialog title bar, select "Advanced Mode" if availableclick on the "Install" tabclick on button "Plug & Play..."confirm the prompt with "Yes" buttonclick on "OK" buttons to leave WIBU-KEY appletHd ]Pl " " " " " " "uninstall WIBU-KEY driver with Control Panel/Add/Remove Software/WIBU-KEY Setup Removenow reboot your PCreinstall the WIBU-KEY driver with \RAY32\WIBUKEY\SETUP.EXEreinsert the USB keynote bubble "Found New Hardware" at bottom of screenafter a few seconds, note display of "Found New Hardware Wizard" windowselect radio button "No, not this time" to prevent connecting to Windows UpdatexD4 8Pl "click on "Next" button twice, and on following "Finish" buttonYdh' lhIf above procedure does not work, make sure to uninstall the WIBU-KEY driver with Control Panel/Add/Remove Software/WIBU-KEY Setup Remove (Control Panel/Programs and Features under Windows Vista), directly before rebooting your PC. Then reboot, and now reinstall the WIBU-KEY driver with \RAY32\WIBUKEY\SETUP.EXE . Then reinsert the USB key.(% lh, &lPlease install the LPT parallel port WIBU key coming with your Rayfract license on your parallel printer port LPT1. Replug your printer cable into the WIBU-KEY dongle, instead of directly plugging it into the parallel printer port LPT1. This dongle is highly compatible with most printers and printer drivers. One known problem case is the HP LaserJet 5L printer : it needs to be installed as PCL printer driver (custom installation) and WITHOUT the PCL status window, so that the WIBU dongle can communicate with the Rayfract package correctly. If printing does not work in that configuration, try to reconfigure the printer driver driver by deactivating both the spooler and bidirectional communication with the printer.(% lu& %lIf you need to reinstall the WIBU key driver software for any reason, please run the command line \RAY32\WIBUKEY\SETUP and follow instructions.(% lu, &}lIf the dongle is still not recognized by the WIBU-KEY driver software (e.g. on Toshiba Satellite or Dell Notebook computers), please check and update the LPT: port address as follows :(% l&y ePl " " " " "start up Windows Explorer, and search for the MSINFO32.EXE utility on your C: driverun MSINFO32.EXE and click on Components/Ports/Parallelwrite down the (hexadecimal) IO Range Base parameter (left of hyphen), e.g. 0378 or BDA8start up the WIBU-KEY Control Panel applet with Start/Control Panel/WIBU-KEYleft-click on the small icon to the left of the dialog title bar, select "Advanced Mode" if available-  gPl " " " " " "click on the "Setup" tabuncheck "System default"make sure the "Port address" is the same as noted above e.g. 0378 or BDA8if not, enter the address as shown by MSINFO32.EXE manually, into field "Port address"now click on button "Apply"then try to start up Rayfract again( % l  & lIf the above does not help with your LPT port WIBU-KEY communication, please try connecting a printer with a parallel port printer cable plugged into the LPT WIBU-KEY or unplug such a cable. (  % lvP : & lSome PC's have a non-standard LPT port hardware and/or do not supply enough power to the dongle. If the LPT port dongle is still not recognized by the WIBU-KEY driver, you may introduce a delay factor to prevent a timeout, in case of too low power supply to the dongle. See also http://support.wibu.com/en/faq/faq.html#Delay . Please( b % l|W:  % l- download the .ZIP archive http://rayfract.com/dongle/diaglpt.zip from our web site{Pb Y+ &l- Start|Run "explorer.exe" (without enclosing ""), to open Windows Explorer[ % l- create a directory \ray32\wibukey\diaglpt on your PC's hard disk with Windows Explorer{VYT% l- copy diaglpt.zip file into this directory, and unzip it e.g. with WINRAR utility.(|% l|WT @% lNow slow down the communication speed between the LPT port and the WIBU-KEY dongle :| @(|4@% lT @@+ &l- open a DOS command prompt via Start|Run cmd.exe (without the enclosing )._4@7A% l- change the current directory of that prompt with command line "cd \RAY32\WIBUKEY\DIAGLPT"._@A% l- navigate with Windows Explorer to your \ray32\wibukey\diaglpt directory, as created above._:7AB% tl- click on w2k_delay4.reg, and confirm the two prompts.R-AlB% Zl- switch to the DOS prompt as opened aboveN)BB% Rl- enter command line "WKU32 RESET ALL"O*lB C% Tl- then try to start up Rayfract again.(B1C% l_9 CD& slIf this does not help, please repeat the above last four steps for all other .reg files in your DIAGLPT directory. ...delay12.reg will slow down the communication speed the most. If your LPT WIBU-KEY dongle is still not recognized by the WIBU-KEY driver, please contact us for an USB key license upgrade offer.(1CD% l]7DF& olShould you unexpectedly have serious trouble with printing (presumably caused by your WIBU dongle), or witness communication failure between WIBU-KEY dongle and Rayfract (in connection with a certain printer / printer driver), you may contact the WIBU-SYSTEMS hotline, located in Germany. Their number is :(D=F% l9FvF% (l+49 721 931 7215.(=FF% lEvFG& ?lYou may also direct your Web browser at http://www.wibu.de. You will find current drivers, answers to FAQ's (frequently asked questions) etc. on that site (English version available). Current drivers are contained in various installable archives which you may download from that site.DF'H1'HHAbsolute elevationsGH& Absolute elevationsSelect this radio button to export absolute elevations to file DELTATV.CSV, in (station nr., depth, velocity) triples.A'HI1IkJAcquisition dateO)HkJ& SAcquisition dateDate of recording of seismic data. It is recommended that the date be specified in dd/mm/yyyy format. Alternatively, in order to avoid any possible confusion in the ordering of the day and month, use format dd/mmm/yyyy, with mmm being a three-letter abbreviation of the month.AIJ1MJKAcquisition time kJK& Acquisition timeTime of recording of seismic data. The contents of this field is not used during processing. As a consequence, its format is not fixed. It is recommended that the time be stored in the 24-hour hh:mm:ss format.> JK1 KLActive tracesKL& 9Active tracesIf you do not want to import all traces recorded for the current shot, just specify the number of traces to be imported by this parameter.[*KM1!MXNAdjust X coordinate to fit Y and elevationELXN2 2'Adjust X coordinate to fit Y and elevationSelect this radio button to automatically adjust x coordinates imported to fit y coordinates and elevations imported, such that the resulting station spacing corresponds to the Station spacing as specified in Header|Profile.[*MN1"N Adjust Y coordinate to fit X and elevationEXN 2 2'Adjust Y coordinate to fit X and elevationSelect this radio button to automatically adjust y coordinates imported to fit x coordinates and elevations imported, such that the resulting station spacing corresponds to the Station spacing as specified in Header|Profile.N XNBNN1#N'AGC window length '& gAGC window lengthLength of time window (in milliseconds) enclosing samples which are regarded when carrying out automatic gain control (AGC) on sample central to that window.f5N1$,Allow gaps in coverage of velocity model grid columnsy',& Allow gaps in coverage of velocity model grid columnsSelect this option to allow grid columns with no velocity values between the first and last grid columns with velocity values. This may be necessary if there was a gap in coverage along the original 2D field seismic line, i.e. when crossing a river. We recommend to leave this option at its default value i.e. disabled.> j1%j Annotate axesz, % Annotate axesDeactivate this option in order to display axes without annotations, i.e. without labeling of big ticks.MjV1&VAnnotation parameters dialog| % Annotation parameters dialogThis dialog lets you customize the labeling and coordinate system display of your sections.MVD1 'DAnnotations inside view port& 1Annotations inside view portCheck this option in order to display annotations such as axis calibration and axis title inside the coordinate system.g6Di1w(iyAutomatically adapt shape of rectangular filter matrixy' Automatically adapt shape of rectangular filter matrixCheck this item to automatically adapt the shape of the rectangular filter matrix to suppress processing artifacts. We recommend to leave this option activated i.e. checked.JiÇ1:)ÇAutomatically estimate v0y8 >qAutomatically estimate v0Activate this option in order to force estimation of a general laterally varying near-surface velocity based on the laterally constant crossover distance Weathering crossover. You may want to use this option e.g. in situations of locally outcropping geologic formations. Also, with this option there is no need to map first breaks to refractors explicitly, in your Shot breaks or Midpoint breaks display.CÇ1*XAxis big tick sizeb=X% zAxis big tick sizeSize of big axis ticks, in millimeter.B1+sBase filter widthXs& gBase filter widthThis parameter lets you specify over how many adjacent stations the running average smoothing filter will be applied, for the deepest refractor being mapped.J1;,Basement crossover filters, &Basement crossover filterFilter width (in station numbers) used for smoothing the laterally varying crossover distance separating first breaks mapped to the wave critically refracted by the first refractor from first breaks mapped to the wave critically refracted by the second refractor. If you specified a Refractor Count of 1, substitute weathering layer and first refractor for first refractor and second refractor, in the preceding sentence.= 1L-Batch import, &Batch importHas meaning for ASCII data type import only. Check this option in order to import all shots contained in directory specified automatically, without need of confirmation of shot data in the Import shot dialog.= 71.7Branch pointfK d7FÉ2Z Branch pointThe location on a traveltime curve offset from the CMP location or from the shot point by a crossover distance7 is called a branch point. A traveltime curve mapped to refractors is separated by branch points into segments, also called refractor branches.> 71/pCancel importdp% Cancel importUse this button to abort the import of shots into your Rayfract profile database.F1D0Central filter weightp& Central filter weightWeight applied to central sample of current trace sample time window, when filtering trace signals with the running average smoothing algorithm. All other samples are assigned a weight of 1.Q 114Central Ricker wavelet frequency/ 4& Central Ricker wavelet frequencyThis edit field lets you specify the central frequency of the Ricker wavelet used to modulate the wavepath misfit gradient amplitude. We recommend to leave it at the default value, i.e. at 50 Hz. See (Schuster 1993) for details.7k12kClientp4% ClientFree format text field naming the company or organization sponsoring data acquisition and processing._.k_1X3_XClip amplitude peaks for current trace displayX& Clip amplitude peaks for current trace displayWhen this option is activated, trace signals are displayed with peaks and troughs clipped. This guarantees that trace signals of adjacent traces do not overlap.G_14FCMP curves stack width{XF, &CMP curves stack widthLets you specify how many adjacent CMP positions, in a CMP station number interval centered at the current CMP position, are considered when constructing the CMP traveltime curve for the current CMP position. The number of CMP's in a given station number interval may be computed with the formula CMP count = (station nr. difference covered) * 2 + 1.A15CMP gather datumpJF& CMP gather datumSelect this option to compute first break static corrections relative to a dipping datum plane specific to the CMP gather currently being processed. This datum plane is obtained by linear regression through elevations of all sources and receivers employed for recording traces mapped to that Common Mid-Point.@71J67ACMP Stack Width A& CMP Stack WidthLets you specify how many adjacent CMP positions, in a CMP station number interval centered at the current CMP position, are considered when constructing the CMP traveltime curve for the current CMP position.E717CMP traveltime curve~FA8 >Ɣáĝ؉CMP traveltime curveThe midpoint breaks display is constructed by displaying all CMP traveltime curves for the current profile. One CMP traveltime curve is constructed by stacking the first breaks picked for CMP Stack Width adjacent CMP positions (centered at the CMP position currently being evaluated) and connecting first breaks located at adjacent unsigned offsets with straight line segments. If more than one first break are being mapped to the same unsigned trace offset during construction of the stack/traveltime curve, these breaks are averaged out numerically.9=18=Column 1' Column 1Specify the content of your ASCII format, column 1, by selecting the corresponding entry from the drop down list box.: =!109!#Column 10#& Column 10Specify the content of your ASCII format, column 10, by selecting the corresponding entry from the drop down list box. If your format does not specify this column, specify c!#ontent type No value.9!\1:\Column 2#& Column 2Specify the content of your ASCII format, column 2, by selecting the corresponding entry from the drop down list box.9\=1;=Column 3& Column 3Specify the content of your ASCII format, column 3, by selecting the corresponding entry from the drop down list box.9=1<Column 4& Column 4Specify the content of your ASCII format, column 4, by selecting the corresponding entry from the drop down list box.91-=Column 5& Column 5Specify the content of your ASCII format, column 5, by selecting the corresponding entry from the drop down list box. If your format does not specify this column, specify content type No value.9,1->, Column 6 & Column 6Specify the content of your ASCII format, column 6, by selecting the corresponding entry from the drop down list box. If your format does not specify this column, specify content type No value.9,Y1-?YMColumn 7 M& Column 7Specify the content of your ASCII format, column 7, by selecting the corresponding entry from the drop down list box. If your format does not specify this column, specify content type No value.9Y1-@zColumn 8Mz& Column 8Specify the content of your ASCII format, column 8, by selecting the corresponding entry from the drop down list box. If your format does not specify this column, specify content type No value.91-AColumn 9z& Column 9Specify the content of your ASCII format, column 9, by selecting the corresponding entry from the drop down list box. If your format does not specify this column, specify content type No value.G1,B Common Mid Point (CMP) & Common Mid Point (CMP)A profile position, expressed in station numbers, which represents the midpoint between shot and receiver position for one or more traces recorded for that profile.8 1C  Companyi  % CompanyFree format text field. Name of company responsible for acquiring and/or processing the data.N  1CD  Context sensitive online help  ( Context sensitive online helpWhenever you are displaying a dialog box, you may cycle through its controls by pressing the TAB key repeatedly. The control with the focus is visually highlighted. In order to get online help on that control, press F1. Now a pop up window containing a short description of the control's usage and meaning is displayed. In order to dismiss that pop up online help window under Windows 95, just press any key, such as ESC. When running Rayfract under NT 4.0 Workstation or Windows 3.1, press ALT-TAB instead, to return the focus to your dialog box and currently selected control. Or shut down the help window, with ALT-F4 or by clicking on its close icon in its upper right corner.L (1E(Copy v0 from Station editor|V & Copy v0 from Station editorUse this option to reuse weathering velocities as specified in the Station editor (Header|Station) for the computation of static corrections. This option will preserve existing mappings of first breaks to refractors and resulting weathering velocities and corrections of first breaks for shot position offsets.f5(@1F@IACorrect all velocities for Delta-t-V system@atic error3 IA& Correct all velocities for Delta-t-V systematic errorSelect this option to reduce all grid node velocities as indicated in the Surfer .GRD grid file by 10 percent before running the model through the raytracing algorithm during the first WET tomography iteration.l;@A1GAICCorrect basement velocities for Delta-t-V systematic errorsnIAIC& Correct basement velocities for Delta-t-V systematic errorsSelect this option to reduce basement grid node velocities as indicated in the Surfer .GRD grid file by 15 percent before running the model through the raytracing algorithm during the first WET tomography iteration. "Basement" just means high velocity regions, as indicated by values in the grid file.?AC1HCECorrect breaks]ICE- (Correct breaksOnce you have specified correct shot hole depths and inline/lateral shot position offsets for all shots and correct weathering velocities for all stations, click this button in order to correct first breaks for shot position offsets. It is assumed that the bottom of the shot hole is located in the uppermost, weathering layer.MC_E1I_E GCorrect picks for delay timeE G, &Correct picks for delay timeThis flag is disabled per default. Experience has shown that sometimes ASCII files with first breaks are encountered where first breaks have not yet been corrected for the delay time. One specific case are Rimrock Geophysics .PIK files. This problem may be caused by the Seismograph software not storing the delay time into the SEG-2 trace headers.: _EDG1JDGHCorrect x{U GH& Correct xIf x coordinate values are specified and have been interpolated for all profile station nrs. previously, you may correct x coordinates for topography change along the line. To automatically generate x and y coordinate values for all stations, just export coordinates via the File menu and then reimport the generated .COR file.: DGH1KHtJCorrect y{UHtJ& Correct yIf y coordinate values are specified and have been interpolated for all profile station nrs. previously, you may correct y coordinates for topography change along the line. To automatically generate x and y coordinate values for all stations, just export coordinates via the File menu and then reimport the generated .COR file.> HJ1LJ4LCritical fold\tJ4L& Critical foldRelevant for Plus-Minus and CMP intercept time refraction depth sections only. If the fold (i.e. the number of first breaks stacked at the current position, for the current refractor) is smaller than the value specified for this parameter, the corresponding depth location arc is not outlined, but drawn with a dashed pen instead.CJwL1MwL Crossover distanceu:4L ; DuƔ㩆Љ Crossover distance, crossover offsetCrossover distance means the in line offset in station numbers (from shot location or CMP location) where head wave first breaks from a deeper refractor overtake head wave first breaks from a shallower refractor. They are identified by visually or algorithmically locating systematic discontinuities in slope of traveltime curves (abrupt changes of slope). In situations of highly sloping / undulating refractor surfaces, crossover distances may be more easily identified on a CMP sorted traveltime curve display than on a shot sorted traveltime curve display. The reason for this better visibility of crossover offsets is that the influence of the dip of layers on traveltime curves is filtered out to a higher degree in the CMP sorted traveltime curve display (Rhl, T. 1995).wL 4LHwLT1NTDefault shot hole depth & )Default shot hole depthSpecify the default shot hole depth, in meters, for all shots to be imported into the currently opened profile database.DTR1OR Default spread type - ( Default spread typeSpread types are named "X: YYY channels". X enumerates the spread types, starting with 1. YYY stands for the number of receivers in spread type X, e.g. 144. Select the list entry matching the number of receivers contained in the layout type employed by you. If no exactly matching list entry is available, please select the one having the next higher number of receivers.\+Ri1PiDegree of differentiation of Ricker wavelet}Q , &Degree of differentiation of Ricker waveletThis parameter lets you specify how many times in time the Ricker wavelet to be used to modulate the amplitude of the wavepath misfit gradient should be differentiated. We recommend to leave this parameter at the default value of 0. See (Schuster 1993) for details. Before version 3.05, the default value was 1. But using the undifferentiated Ricker wavelet (instead of its derivative) for weighting of WET wavepaths renders the tomographic inversion more robust, and results in less artefacts. See http://rayfract.com/help/release_notes.pdf .Ni41~Q4dDegree of Surface Consistency >/ ,Degree of Surface ConsistencyThis parameter specifies to what degree the smoothed surface of refractor 1 should follow the line's topography. You will want to set this value according to the weatherability of refractor 1 : if the refractor consists of a formation with relatively high propagation of speed of sound, it will resist to weathering to a higher degree than the weathering layer itself. Therefore, refractor 1 will more likely keep its shape over time, with a higher degree of independence from the shape of the topography above it. The more refractor 1 resists to weathering or the weaker the weathering layer itself in relation to refractor 1, the smaller the degree of surface consistency specified should be.&4d# ; >1TRDelay timed& Delay timeThis value will normally be 0. If you start recording trace data after a certain delay after generating the sound waves only (i.e. by firing a shot or dropping a weight), please specify that delay with this parameter, in milliseconds. If the recording of samples starts BEFORE the shot is fired, the time difference needs to be specified as a NEGATIVE delay time. When importing SEG-2 binary trace data files, this field will be initialized from the SEG-2 trace headers automatically.d31SpDelete traveltime grid files for last WET iterationT.p& ]Delete traveltime grid files for last WET iterationUncheck this option if you want to keep Surfer .GRD formatted disk files holding the traveltime fields as computed with the Eikonal Solver for each shot, during the last WET iteration. These grid files will be named S1.GRD for shot number 1 etc.G1XTȎDepth below topographypȎ, &Depth below topographySelect this radio button to export depths below topography in (station nr., depth, velocity) triples to file DELTATV.CSV. If depths should be preceded with a minus "-" sign, check box negative depths.g6/1U/Detect shifted 32-bit floating point sample data startȎ, &iDetect shifted 32-bit floating point sample data startThis option was implicitly enabled before version 2.64. But the import routine cannot detect the true trace /Ȏstart in every case (by determining the correct byte shift with the minimum trace signal variance), so we decided to disable this option per default. If your imported binary shots don't show any coherent signal in Trace|Shot, please reimport with this option enabled.< /W1fVWDirect Wave*' Direct WaveDeselect this option if the shot-receiver spacing employed during data registration was too coarse to register direct wave first break arrivals. This occurs if all first breaks picked belong to refracted waves and with thin weathering layers.IW1CWDirect Wave Offset Delta& Direct Wave Offset DeltaValid values : 3 to 10. Offset range considered when carrying out piecewise linearization of first breaks mapped to the same CMP traveltime curve and assigned to the weathering layer.J1,XDisplay parameters dialog& yDisplay parameters dialogThis dialog lets you specify the station number and data range displayed. Furthermore, it lets you scale the plot generated when printing the current section.X'H1YHDo AGC for current trace gather displaym% Do AGC for current trace gather displayEnable AGC for the shot gather display currently being displayed.JH$1QZ$+Do not adjust coordinates+, &Do not adjust coordinatesSelect this radio button to display error messages for all coordinate values which do not fit the line geometry (station spacing) within the tolerance as specified with Maximum tolerance.> $i1d[iDo not export&+8 >Do not exportSelect this radio button in connection with options Maximum velocity exported and limit velocity exported, in order to skip velocity values exceeding Maximum velocity exported during generation of file DELTATV.CSV.Ji1S\Edit grid file generation & Edit grid file generationThis button brings up a dialog for specifying what kind of intermediate grid files should be generated and kept by the WET tomography processing. These intermediate Surfer formatted grid disk files may be contoured and plotted with Surfer and will let you follow the intermediate stages of the tomography processing. You may activate the generation of wavepath / gradient misfit / velocity update and composite subsurface wavepath coverage grid files.H*1]*Edit velocity smoothingY3& gEdit velocity smoothingClick on this button to determine the dimensions of the smoothing filter to be applied to the updated velocity model grid after each tomography processing iteration. Also, you may specify the maximum allowed relative change after one iteration, for velocity values of grid cells.@*1^uEnd shot importu/ ,End shot importClick this button in order to end the import of shots into your currently opened Rayfract profile database.11_4Vu4, &Enforce Monotonically increasing layer bottom velocitySelect this option to enforce a strictly physical modeling of 1D seismic refraction per CMP. Disable this option to prevent giving too much weight to apparent high velocity anomalies in the shallow i.e. overburden subsurface region. Reasons for unrealistically high apparent shallow subsurface velocity anomalies can be : strongly undulating topography, geometry specification errors, bad i.e. too early traveltime picks etc. You may want to disable this setting to enhance the low velocity imaging c4uapability of the Delta-t-V inversion.?s1-`saExport Options4a& Export OptionsClick on this button in order to specify parameters describing the format of the ASCII file generated and containing the velocity-depth results as output by the Delta-t-V inversion.Gs1afFar offset shot pointsaf& 1Far offset shot pointsShot points positioned before the first receiver station or behind the last receiver station of a profile (or receiver spread) are called far offset shot points. It is important to record shots fired from such far offsets (e.g. 5 or 10 station intervals away from the first/last receiver station) to ensure sufficient depth penetration of the seismic waves / first breaks recorded.> 1bFilter tracesj8f2 2qFilter tracesEnable this option in order to apply a high frequency filter to the traces currently displayed. The filter is implemented by a running average smoothing algorithm, with filter width and central sample weight as specified with the following parameters Filter width and Central filter weight.= K1$cK2Filter width2& Filter widthFilter width of the running average smoothing filter to be applied to trace signals, in milliseconds. The bigger the filter width, the lower the cutoff frequency of the filter.LK~1Ud~First break envelope length 2, &First break envelope lengthThis parameter (in milliseconds) determines the trace signal time window regarded when automatically picking the first break for that trace. Increase this parameter in case of weak first break amplitudes and if the automatically picked first breaks are too late. Once all first breaks are picked about correctly or too early, increase parameter First break stabilization factor in order to prevent too early picks due to pre-first break noise.Q ~1e< First break stabilization factord>< & }First break stabilization factorThis parameter helps in situations of strong pre-first break noise, caused by surface sources, such as circulation / trees moved by wind / footsteps. Increase its value in order to filter out increasingly larger amplitude noise / if first breaks picked automatically are too early.A} 1zf}  First break time9 <  , &First break timeSpecifies time (in milliseconds, relative to time when shot was fired) at which the first break energy arrives at the corresponding receiver. It may be picked interactively in menu Trace. Alternatively, it may be edited numerically in this field.O}  1bg  First refractor velocity limit  & First refractor velocity limitSpecifies the maximum expected velocity of the first refractor. Apparent CMP velocities higher than this limit are interpreted as belonging to the head wave critically refracted by the second refractor._. w 1hw Full smoothing after each tomography iterationd & Full smoothing after each tomography iterationSelect this radio button for full smoothing (i.e. a wide averaging filter) to be applied after each tomography iteration. The resulting velocity model i.e. tomogram will be relatively smoother accordingly. We recommend to select this option during the first few (e.g. first ten) WET tomography iterations.Aw B1iBGeneral constant}X% General constantThis value must be a positive decimal number of 12 or fewer digits.MB@1Sj@7AHalf smoothing f@ilter height7A& Half smoothing filter heightThis edit field will be enabled if you choose manual smoothing. It shows the number of grid rows scanned above and below the current pixel / grid cell to obtain a smoothed average value for the velocity of that cell.L@A1RkABHalf smoothing filter width7AB& Half smoothing filter widthThis edit field will be enabled if you choose manual smoothing only. It shows the number of columns scanned on each side of the current pixel / grid cell, for smoothing the value of that cell.EAB1^lBCHeader lines to skipBC& Header lines to skipUse this edit field to specify the number of header lines in your ASCII import file format. These lines will be skipped during import before starting mapping line content to trace header parameters, as specified above.FB-D10m-DEHorizontal axis ticksCE, &}Horizontal axis ticksUse this Annotations parameters dialog setting to specify the type of axis ticks shown on the horizontal X axis. Select type Major&Minor, Major ticks or No ticks.F-D]E1n]EEHorizontal axis titlejEE% Horizontal axis titleSpecify the axis title for the horizontal axis. It may not exceed 32 characters.F]E2F1`o2FLGHorizontal grid linesELG, &Horizontal grid linesUse this setting in the Annotations parameters dialog, to specify the type of auxiliary horizontal grid line shown in parallel to the X axis, at Y axis ticks. Select setting Dashed line, Dotted line or No line.A2FG1ipGHHorizontal scale(LGH& Horizontal scale [1:]Specify the ratio between the horizontal profile distances as printed or plotted and as measured (in meters). When displaying sections on screen, the section is scaled to the window's width regardless of the value of this parameter.AGH1qHIImport data typeHI& 7Import data typeSelect the appropriate entry from this drop down list box., in order to specify the data file format of your seismic trace data files.CHI1rIJImport shot dialogIJ& cImport shot dialogThis dialog lets you edit the shot and trace header data. These header values are relevant for all traces of the trace data file currently being imported.= IK1sKKImport shotsxJK% Import shotsClick this buttons once you have specified values for all parameter fields in your Import shots dialog.DKK1UtKMImport shots dialogKM, &Import shots dialogThis dialog is displayed when selecting Files|Import data. It lets you define the input file format, the directory containing files to be imported and further parameters valid during this import session.NKNM1~uNM~NInput directory Select button0 M~N& Input directory Select buttonUse this button to select one seismic trace data file located in the subdirectory from which you want to import data files. Note that only data files with a file extension matching the data type format selected above will be listed.; NMN1vNrOInstrument~NrO& 'Instrument . This identifies the instrument used to acquire the data stored in the file.HNO1wOBInterpolate coordinates|VrOB& Interpolate coordinatesClick OBrOon this button once you have specified x/y/z coordinates and weathering velocities for all station positions deemed necessary. Browse through station positions with F7/F8 function keys. Once you click this button and coordinates have been interpolated for all station positions, the dialog will be shut down.BO1xAInverted polarityBA& /Inverted polarityCheck this option if the trace was recorded with inverted polarity. The setting of this option is not regarded during processing.7x1yxJob IDwA% Job IDFree format text field. Names the job during which the seismic data was recorded, in the context of Line ID.= xQ1:zQNLayout startN- (Layout startProfile relative position of first / leftmost receiver spread position used for recording of current shot, in whole station numbers. See online help topic Station numbers and spread types.AQ1{*Least deviations?N*\ Least deviationsSelect this radio button in order to specify linear regression method Least absolute deviations. This method will be used to determine local apparent CMP velocities. Velocity estimates may be more realistic than with method least squares. Processing time for the whole Delta-t-V inversion will amount to about ten times the time spent when selecting the alternative option least squares, however. See (Press et al. 1986) chapter 14 for details. Least deviations will automatically recognize outliers / less relevant data points and give them less weight when modeling / linearizing the trend inherent in the data. Least squares treats all data points with the same priority. In low coverage situations, least squares may be more appropriate, giving equal weight to all first breaks available.> h1|h͉Least squarese9*͉, &sLeast squaresWhen you select this radio button, local apparent CMP traveltime curve velocities are determined by carrying out a least squares linear regression over traveltimes located in an offset interval having length Regression over offset stations and centered at the offset currently being evaluated.Hh1}ʌLeft handed coordinates͉ʌ& Left handed coordinatesIf this option is deactivated (by default), a right handed coordinate system is assumed. This means that X-Axis, Y-Axis and Z-Axis are orientated to each other as thumb, index finger and middle finger of the right hand. Orientate thumb and index finger horizontally and your middle finger vertically pointing to the ceiling. Longitude, latitude and elevation in the northern hemisphere are a right handed coordinate system. In a right -handed coordinate system, lateral shot point offsets have a positive sign when offset to the left from the profile (when looking along the profile in direction of increasing station numbers).P1~Limit maximum basement velocityySʌ& Limit maximum basement velocityActivate this option if you want to filter the estimated CMP basement velocity against the value as specified with the next parameter. This filtering will occur during CMP intercept time refraction time-to-depth conversion. It may be appropriate in case of steep / narrow synclinal refractor topography.= Ў1EЎ Limit offset , &Limit offsetImport traces which have been recorded at receiver positions offset from the shot position not farther than the value specified in the following edit field Maximum offset imported (in station numbers).Ў HЎT1TLimit velocity exportedV > JLimit velocity exportedCheck this box in order to apply a low pass filter to velocities written to file DELTATV.CSV. Specify the corresponding velocity threshold value with parameter Maximum velocity exported. Select radio button set to max. exported or do not export in group box Handling of too high velocities as appropriate. 8T 1 Line ID`% Line IDFree format text field. Names the seismic profile along which the data was recorded.Y( 1/Manual specification of smoothing filter1 /& Manual specification of smoothing filterSelect this radio button if you prefer to manually specify the dimensions (half width and half height) of the smoothing filter to be applied after each iteration. We recommend to prefer full smoothing or minimal smoothing.Jy1=ylMaximum basement velocity/l& Maximum basement velocityThis parameter (in meters per second) specifies the highest CMP basement velocity recognized as valid when carrying out CMP intercept time refraction time-to-depth conversion.By19Maximum elevationfl9% Maximum elevationElevation isoline value for upper station number axis, in depth section display.H1Maximum offset importede9, &Maximum offset importedIf the preceding check box Limit offset has been checked, traces recorded at receivers offset from the shot position farther than the value specified in this edit field (in station numbers) are not imported. If all traces of the shot currently being imported are offset farther than that value, the entire shot is not imported.M_1J_\Maximum propagation velocity\- (Maximum propagation velocityMaximum velocity (in meters per second) regarded when carrying out automatic first break picking. Trace signal peaks/troughs detected earlier than the time window resulting from mapping this velocity gradient to the current shot gather are not regarded during the picking process. If you carry out Semi-automatic first break picking by interactively picking a polyline with the right mouse button, this parameter has no meaning.G_1'Maximum station number_\'% Maximum station numberConstant station number location for displaying right vertical axis.Bi1PiwMaximum tolerance'w& Maximum toleranceUse this field to specify the maximum relative difference allowed between effective station spacing (as computed from the coordinates of neighboring stations) and station spacing as specified in Header|Profile.Gi13Maximum valid velocityw& Maximum valid velocitySpecify the maximum velocity regarded as valid when processing CMP curves with this option. Apparent CMP velocities exceeding this value will be skipped during processing.K11Maximum valid WET velocity, &uMaximum valid WET velocityUse this field to limit the maximum WET velocity modeled. This value overrides the Maximum valid velocity field as specified for the Delta-t-V inversion.J%1g%NMaximum velocity exportedN2 2Maximum velocity exportedUse this parameter to apply a low pass filter to velocities exported into file DELTATV.CSV, in connection with check box limit velocity expo%Nrted and group box Handling of too high velocities controls. T#%1Maximum velocity or time displayedV$N2 2IMaximum velocity or time displayedMaximum velocity isoline value at which the top horizontal station number axis is displayed, in velocity sections. In time sections, this field specifies the maximum time isoline value at which the bottom horizontal station number axis is displayed.H@1n@fMaximum velocity update&f& Maximum velocity updateThis parameter lets you specify the maximum allowed relative update of each velocity model cell, after one iteration. If computed relative updates exceed this threshold value the applied update will be limited by this threshold.b1@1}Minimal smoothing after each tomography iterationf}& Minimal smoothing after each tomography iterationSelect this radio button for minimal smoothing (i.e. a narrow averaging filter) to be applied to the updated velocity grid after each tomography iteration. The resulting velocity model i.e. tomogram will show more details than with full smoothing. We recommend to select this option during the last few (e.g. last ten) WET tomography iterations.B1VMinimum elevationr}V% Minimum elevationElevation isoline value for displaying bottom station number axis, in depth section display.M1JMinimum propagation velocityV- (Minimum propagation velocityMinimum velocity (in meters per second) regarded when carrying out automatic first break picking. Trace signal peaks/troughs detected later than the time window resulting from mapping this minimum velocity gradient to the current shot gather are excluded from the picking process. If you carry out Semi-automatic first break picking by interactively picking a polyline with the right mouse button, this parameter has no meaning.G1j Minimum station number^j % Minimum station numberConstant station number position for displaying left vertical axis.S" 1  Minimum velocity or time displayedV$j  2 2IMinimum velocity or time displayedMinimum velocity isoline value at which the bottom horizontal station number axis is displayed, in velocity sections. In time sections, this field specifies the minimum time isoline value at which the top horizontal station number axis is displayed.H [ 1 [  Model Parameters dialog  & 7Model Parameters dialogThis dialog lets you parameterize the time-to-depth conversion. You may specify to what degree the data should be smoothed etc.@[ \ 1\  Negative depths  & 1Negative depthsCheck this box in order to write depths with a preceding minus "-" to DELTATV.CSV, in connection with radio button depth below topo.F\ ` 1S` mNo static corrections  m2 2No static correctionsClick this radio button in order to disable the computation and application to first breaks, of static corrections. This option makes sense in situations of flat topography or topography approximating a dipping plane. Note that first breaks will still be corrected for shot position offsets and shot hole depth. The near-surface weathering velocity required for computation of these corrections is determined with parameter Weathering crossover.5` 1#@Notem@& YNoteA paragraph consisting of multiple lines, describ@ming further recording parameters and background information deemed important for processing. Up to 512 characters.T#@1X@ANumber of WET tomography iterations@A, &Number of WET tomography iterationsThis parameter lets you specify the number of WET tomography iterations to be carried out with the parameters specified, once you click on button Start tomography processing.9@B1BBObserveraAB% ObserverThe name of the individual responsible for data acquisition. Free format text field.FBB1BTDOffset breaks displaywKBTD, &ĝ؉Offset breaks displayDisplays your traveltime field in a coordinate system with CMP station numbers as horizontal axis and recording time as vertical axis. Common offset traveltime curves are constructed by connecting first breaks belonging to shot receiver pairs with constant unsigned offset and neighboring CMP position.= BD1DEOffset limitY-TDE, &[FÉOffset limitUse this parameter (station numbers) to limit the basement penetration depth of ray paths regarded during time-to-depth conversion. First breaks mapped to the basement and recorded at an offset exceeding the local basement crossover distance plus this offset limit are not regarded.OD9F19FGOffset limit basement coverageZEG- (Offset limit basement coverageCheck this option in diving wave situations, with relatively flat refractor topography. First breaks mapped to the basement and recorded at offsets exceeding the local crossover distance for the basement plus the value of the following parameter Offset limit are not regarded during time-to-depth conversion.= 9FG1G^HOutline axesa<G^H% xOutline axesCheck this option in order to outline axes.Q GH1HJOutput Delta-t-V Results in feetd>^HJ& }Output Delta-t-V Results in feetActivate this option if you want CMP positions, elevations or depths below topography and velocities in the resulting DELTATV.CSV file to be specified in feet and feet per second. If this option is not active, values will be output in station numbers, meters and meters per second.Q HdJ1LdJ_KOutput inline CMP pos. in metersJ_K& Output inline CMP pos. in metersSelect this option if you want CMP positions in resulting DELTATV.CSV files to be specified in meters. Otherwise CMP positions will be listed by their station number positions.OdJK1SKMOutput Measured CMP Velocities_KM, &Output Measured CMP VelocitiesWith this option activated, the Delta-t-V method will combine inverted velocities and depths as obtained during inversion of the CMP sorted and stacked traveltime curves with instantaneous velocities as measured directly on the CMP sorted curves as input to the inversion, at corresponding source-receiver offsets. If the option is not active, velocities as written into the resulting DELTATV.CSV are based on inverted velocities only.LKM1KMNOverburden crossover filterMN& Overburden crossover filterFilter width (in station numbers) for smoothing the laterally varying crossover distance separating first breaks mapping the direct wave from first breaks mapped to the first refractor.BM?O1?O#Overburden filterN#& eOverburden filterSpecify width of overburden filter, for carrying out running average smoothing of overburden refractor data, i.e. elevation and velocit?O#Ny of first refractor.> ?Oa1aOverwrite allU)#, &SOverwrite allSelect this radio button in order to automatically write over all shots already imported and with same shot number as currently being imported. If you select the opposite button Prompt overwriting, you will be prompted for confirmation before each existing shot is overwritten.1a1, &Prefer Average over minimum interface velocityYou may want to disable this setting to enhance the low velocity imaging capability of the Delta-t-V inversion. To enhance the high velocity anomaly imaging capability in the near surface region, you may want to enable this option. Since WET tomography processing has more difficulties when needing to deepen a too shallow (fast) interpretation than when rendering a too deep (slow) interpretation more shallow, you may want to disable this setting for surveys where the imaging targets are low velocity anomalies. Leave this setting enabled in case of strong lateral velocity variation.N1XPrefer CMP overburden mappingw<X; DyPrefer CMP overburden mappingCheck this option for Plus-Minus and Wavefront time-to-depth conversion if you want to prioritize the trace-to-refractor mapping as carried out in the Midpoint breaks display over another mapping as specified interactively by picking branch points in the Shot breaks display.M10Prefer regressed traveltimesX2 2cPrefer regressed traveltimesPrefer regressed traveltimes is activated by default. Deactivate it in order to base your refractor elevations and velocities on algorithmically linked traveltime curves, instead of on regressed traveltime curves. In low coverage situations, a significant difference between resulting depth sections may mean that the basement coverage is too low for traveltime field regression to work reliably.@Ȉ1ȈProcess all CMP& oProcess all CMPActivate this option in order to process CMP sorted traveltime curves at all profile CMPs. This will ensure maximum lateral resolution of the subsurface as imaged.U$Ȉ1QProcess CMP sorted traveltime curves& Process CMP sorted traveltime curvesClick on this button once you have specified all parameters for the Delta-t-V inversion,or to accept the default parameter values as proposed by the software automatically..I?1?Process every CMP offsetM'& OProcess every CMP offsetUse this option to obtain better vertical velocity resolution, by inverting for an incremental gradient layer at every CMP offset . This new option may increase the amount of artefacts in the output, especially for low coverage data sets and noisy first break picks.@?̌1̌Processing dateR,& YProcessing dateThe date a processed file was created. It is recommended that the date be specified in dd/mm/yyyy format. Alternatively, in order to avoid any possible confusion in the ordering of the day and month, use format dd/mmm/yyyy, with mmm being a three-letter abbreviation of the month.@̌^1^Processing time`;% vProcessing timeThe time a processed file was created..E^1Profile start offsetxR& Profile start offsetUse this field to specify a horizontal inline offset different from 0.0, for the first profile receiver. This start offset value will be used by subsequent Delta-t-V and WET imaging. On resulting Surfer plots, the first profile receiver will be positioned at an x coordinate amounting to this start offset value.C1<Prompt overwriting& Prompt overwritingSelect this radio button if you want to be prompted before a shot imported earlier and with the same shot number as the one currently being imported is overwritten in the profile database.: 1Read shot, &ARead shotClick on this button to import the current shot, once you have specified all shot related header values, as displayed in the Import shot dialog.?1Receiver count~& Receiver countSpecify the number of receiver positions to be defined for the new spread type, by the Receiver separations string as displayed below. Once you hit RETURN to create the new spread type, the software will verify that the Receiver separations string defines intervals between exactly Receiver Count positions. If not so, a corresponding error message will be shown.?1JReceiver depth & Receiver depthIf the receiver was buried below topography, use this field to specify its depth below surface. Normally this field will be 0. Note that its value is not regarded during processing, contrary to shot hole depth.H>1>Receiver in line offsetsM& Receiver in line offsetSpecify the in line offset of the receiver, in meters, from the receiver position, as specified in station numbers. This offset will normally be 0. If you need to move the actual receiver for some small in line distance due to unexpected problems at the exact position planned, make use of this parameter.H>1]Receiver lateral offsetd>]& }Receiver lateral offsetSpecify the offset of the actual receiver position from the seismic line (i.e. from the spread), in meters. Normally this offset is 0. If you need to offset the receiver position from the spread due to some unexpected problem at the in line position planned, please use this value to do so.E1LReceiver separations~]L, &Receiver separationsSee online help topic Defining your own layout types. The receiver separations string is formed by counting the number of times the same receiver separation distance (in station numbers) is used between adjacent receiver positions, starting at the leftmost spread position equal to 0 and moving to the right / increasing receiver position station numbers.> 1[Receiver typeL[& WReceiver typeUse this drop down list box to specify the type of receiver used for registering seismic data. The value of this field is not regarded during processing.U$1Recompute traveltime characteristicsP[; D+ Recompute traveltime characteristicsYou may activate check box Recompute traveltime characteristics in order to redo the (time intensive) traveltime field regression. This should not be necessary under normal circumstances, though. If you remap traces to refractors, the traveltime field regression is redone automatically, at the next time you go into the Wavefront model display with Depth|Wavefront (and bring up the Wavefront Model Parameters dialog and confirm it). The same holds true for Plus-Minus interpretation.`/`1`Reduced offset 0.0 is valid trace with time 0.0^& Reduced offset 0.0 is valid trace with time 0.0Enabling this option (as per default) ensures that the information conta`ined in the near-offset part of CMP sorted and stacked traveltime curves is used to the fullest, during Delta-t-V inversion. Disable this option if the output obtained (as gridded and contoured with Surfer) is e.g. too noisy.C`313Reduction velocityt6> JmReduction velocityFirst breaks are reduced according to the Reduction velocity specified before display in the Midpoint breaks display. As a consequence, a refractor segment with apparent velocity of first breaks equal to Reduction velocity is displayed as a vertical CMP traveltime curve segment.\+31~%Reference topography smoothing filter width"%& Reference topography smoothing filter widthUse this parameter to specify the number of stations over which a running average filter will be applied to compute the smoothed elevation for each receiver. station. XY coordinates or elevations will be automatically adjusted during import of the coordinate file specified if the smoothed elevation difference between neighboring stations has the same sign as the unsmoothed difference in elevation. We recommend to leave this parameter at its default i.e. 5.Lq1_qRefracted Wave Offset Delta%& Refracted Wave Offset DeltaValid values : 1 to 20. Specifies the offset range being considered when determining a local apparent CMP refractor velocity from a CMP traveltime curve, for a given CMP position and unsigned trace offset.Nq1!Refractor 1 velocity detected& [Refractor 1 velocity detectedMedian refractor 1 velocity detected, when carrying out piecewise linearization of all CMP traveltime curve segments mapped to refractor 1.N1%Refractor 2 velocity detected& cRefractor 2 velocity detectedMedian refractor 2 velocity detected, when carrying out piecewise linear regression over all traveltime curve segments assigned to refractor 2.A 1 V Refractor branchK V ? Lu| Refractor branchA traveltime curve mapped to refractors is separated by branch points into segments. First breaks contained in one segment are all mapped to the same refractor. Such a segment is commonly called a refractor branch (of a traveltime curve).@  1w  Refractor Count7V  & #Refractor Count(valid values : 1 or 2) specifies how many refractors are being modeled. Enter a value of 1 if you want to model your data as a 2-layer case (weathering layer, and 1 refractor). Enter a value of 2 for a 3-layer case (weathering layer, and 2 refractors).\+ ) 1) Regard uphole picks for Delta-t-V inversion` > JEq&ՀRegard uphole picks for Delta-t-V inversionCheck this option only if you are sure that plausible uphole time correction terms have been specified for all uphole shots of the profile, and that you have or are going to specify a reasonable value for weathering crossover. Since obtaining good values for these two parameters at the same time is a bit of a guessing game, this option is disabled per default. You may want to enable it if you need the uphole picks to extend the coverage of the basement, at profile start and end, and are ready to sacrifice some accuracy for this extended coverage.P) 1@Regression over offset stations@2 2Regression over offset stationsLets you specify the length of the offset station interval used to carry out local piecewise linearization of CMP traveltime curves. This lineariza@tion is required in order to obtain a smoothed local apparent CMP velocity value. You may select the linear regression method used for piecewise linearization in the group box positioned below this edit field.J+A1L+A-BRegression Receiver Count@-B& Regression Receiver CountLets you specify how many adjacent receiver positions should minimally be considered when carrying out piecewise linearization of a CMP traveltime curve, for a given CMP position and offset.N+A{B1_{BDRelative regression tolerance-BD& Relative regression toleranceThe default value of this parameter is 0.000001 msec. It specifies a termination criterion used during carrying out traveltime field regression. The smaller the value, the more iteration steps will be carried out until that criterion (relative improvement of average traveltime modeling error, from one iteration step to next iteration step) is reached. You are advised not to change this value at will. The iteration will stop after maximally 10,000 steps.6{BD1D FRemapID F, &;RemapCheck this option in order to reassign traces to refractors, based on parameters specified in dialog Trace to refractors mapping parameters. The traces will be semi-automatically reassigned once you confirm the parameters displayed in the dialog by pressing the RETURN key.LDWF1@WFKGRemove systematic dc offset FKG& Remove systematic dc offsetCheck this option in order to remove systematic dc offset signals from traces. These offsets are presumably caused by systematic errors of the seismic trace recording system.IWFG1GGHReset coordinates and v0KGH& Reset coordinates and v0Click on this button to reset both coordinates and v0, for all stations. This should help in situations where invalid coordinates have been entered and are being rejected by the software.9GH1HfIReset v0vHfI% Reset v0Click this button in order to reset weathering velocities v0 for all station and shot point records to 0.= HI1I{JSample countfI{J& eSample countUse this parameter to specify how many samples to import from seismic data file traces. If your import data type is ASCII, all sample values displayed will be 0.@IJ1JoKSample Interval{JoK' Sample intervalLength of time step, in milliseconds, between the measurement of two consecutive samples on the same seismic data trace.DJK1KmOSearch window widthoKmO2 2Search window widthThis parameter is used in connection with Semi-automatic first break picking. You may pick first breaks for a shot gather semi-automatically by interactively defining a polyline (consisting of multiple straight line segments connected to each other) with the right mouse button. If such a line segment crosses the offset at which the trace currently being picked automatically has been recorded, the search window width is applied to the linearized time at that offset. The automatic picking algorithm carried out subsequently for that trace limits the search for an optimum pick to the resulting time window. Decrease the value of this parameter in situations of a high degree of pre-first break noise, or weak first break signals. The smaller the parameter value, the closer the automatic pick will be located to the linearized time defined by the polyline as picked by you.6KO15OuSEG-2mOu( =SEG-2The SEG-2 file format is a trace data file foOumOrmat recommended by the SEG Society of Exploration Geophysicists for raw or processed shallow seismic or digital radar data in the small computer environment. It is described exhaustively in the articleS. E. Pullan, 1990. Recommended standard for seismic (/radar) data files in the personal computer environment. Geophysics, volume 55, no. 9, pp. 1260-1284.7O1iރSelectH"u& DSpecify starting velocity model)& ރ' 5Click on this button to bring up the Forward modeling parameters dialog. This dialog lets you specify the initial / starting velocity model used as a basis for the WET tomography processing. Also, you may specify if velocities should be corrected for systematic Delta-t-V errors. Finally, you may specify if every second shot should be skipped during the tomography processing to reduce the processing time.G%1%҄Select coordinate fileރ҄& Select coordinate fileClick on this button to bring up a file selection dialog, for specifying the coordinate file to be imported.N% 1 Select initial velocity model=҄]& /Select initial velocity modelClicking on this button will bring up a file selection dialog, for selecting the initial / starting velocity model (formatted as a Surfer .GRD file). If there does not exist a .PAR parameter file (as generated by the Delta-t-V method) with the same name and in the same directory, you will be asked to specify the .PAR file explicitly as well. Please note that you may specify .GRD files / velocity models as obtained by previous WET tomography runs, i.e. refine the output of earlier WET processing.& # J]͇1͇Separator (one character)& _Separator (one character)Specify the column separator character in this field. The default separator is a semicolon (;). Another frequently used separator is a comma (,).E͇1qSet to max. exported,8 >Set to max. exportedSelect this radio button in connection with parameters Maximum velocity exported and limit velocity exported in order to reset velocity values exceeding the threshold value Maximum velocity exported to that value.FY1YShot acquisition dateT.& ]Shot acquisition dateDate of recording of seismic data. It is recommended that the date be specified in dd/mm/yyyy format. Alternatively, in order to avoid any possible confusion in the ordering of the day and month, use format dd/mmm/yyyy, with mmm being a three-letter abbreviation of the month.FY1WShot acquisition time& Shot acquisition timeTime of recording of seismic data. The contents of this field is not used during processing. As a consequence, its format is not fixed. It is recommended that the time be stored in the 24-hour hh:mm:ss format.DH1LHLShot breaks displayLP nQu|Shot breaks displayDisplays first breaks sorted by common shot. Open this display by selecting Refractor|Shot breaks. Traveltime curves are constructed by connecting first breaks recorded and picked for the same shot and at adjacent receiver positions by straight line segments. You may interactively map first breaks of each shot sorted traveltime curve to refractors by positioning branch points accordingly. Synthetic traveltimes obtained by Depth|Forward model traveltimes... or Depth|Wavefront... are displayed in blue. Toggle display options Trace mapping|Display raytraced traveltimes and TracHLe mapping|Display synthesized traveltime curves as necessary.; H1"nShot depthLn8 >_Shot depthSpecify the shot hole depth, in meters, for the current shot. You do not need to modify the value displayed if it is correct already, i.e. if the current shot's hole depth is equal to the default shot depth specified earlier, during import. You may specify a negative depth if the source elevation is higher than the elevation as shown in read-only field Source elevation (in Header|Shot). This may occur if the shot point has been offset laterally from the line, as specified in field Shot lateral offset. Source elevation is updated automatically whenever you enter a new shot depth or inline offset, and move to the next field or confirm the dialog (Header|Shot).D1]Shot gather displayn2 2Shot gather displayDisplays traces sorted by common shot. Open this display by selecting Trace|Shot gather. You may interactively and semi-automatically pick first breaks by picking a polyline with your right mouse button.D1Shot in line offset|, &Shot inline offsetSpecify the inline offset of the shot point, in meters, from the shot position (in whole station numbers) as specified above. If you need to move the shot position for some small in line distance due to unexpected problems at the exact position planned, make use of this parameter. For example to avoid damage to the geophones. Once you have entered the correct offset and move to the next field or confirm the dialog, the read-only field Source elevation (in Header|Shot) will be updated automatically. The source elevation is determined from interpolation between adjacent receiver stations, at inline offset.D1eShot lateral offsetjDe& Shot lateral offsetSpecify the offset of the shot point position from the seismic line (i.e. from the spread), in meters. Normally this offset is 0. If you need to offset the shot position from the spread due to some unexpected problem at the in line shot position (e.g. a rock or pipe), please use this value to do so.< 1~Shot Numbere~& oShot NumberIf the automatically determined shot number is incorrect, please use this parameter to specify the correct value. This should be necessary in rare cases only, however.N1!Shot point is zero time traceU/~!& _Shot point is zero time traceEnable this menu item to ensure that a hypothetical first break time of 0.0 is assumed for offset 0.0, at each Common MidPoint (CMP) during our Delta-t-V inversion. This will normally help to give more realistic weathering velocities directly below the line topography. As a consequence, deeper structures will be imaged more reliably as well. Disable this option e.g. if near offset first breaks are difficult to pick or you don't like the output as obtained with this option enabled (as gridded and contoured with Surfer).> _1_7Shot position!7, &YShot positionUse this parameter to specify the inline and profile relative shot position, in station numbers. See online help topic Station numbers and spread types.A_x1xShow axis titlesz7% Show axis titlesDeselect this option in order to display axes without axis title, e.g. in order to save screen space.?xV1qVhSkip every 2ndh& Skip every 2ndActivate this option in order to process CMP sorted traveltime curves for every second CMP only. This will reduce tVhhe computation time for the inversion and the following gridding of the data with Surfer.\+V1NSkip every second shot for forward modelingh& Skip every second shot for forward modelingSelect this option to speed up tomography processing by skipping every second shot. This will of course result in a coarser / more uncertain velocity model.: 1Skip shot& ;Skip shotClick on this button in order to skip the currently displayed shot record, i.e. in order NOT to import it into your Rayfract profile database.11G& Smooth CMP traveltime curvesUse this option for high coverage profiles only. For such profiles, this option may help to filter out bad picks from CMP sorted and stacked traveltime curves. For low coverage profiles, enabling this option may result in the destruction of valuable vertical gradient information, describing subsurface acoustic wave velocity distribution. Please note that enabling this option will result in smaller .CSV output files as generated during the Delta-t-V inversion.KE1E Smooth crossover distances 8 > Smooth crossover distancesCheck this option in case of irregular traveltime field region boundaries, separating traces mapped to different refractors or the weathering layer from each other. First breaks mapped to one region, i.e. one refractor, are all displayed in the same color. These boundaries are defined by the laterally varying vertical position of the color change, for all Common Mid Points (CMP)'s of a profile. E.g. the change from red to green identifies the boundary separating first breaks mapping the wave critically refracted by the first refractor from first breaks mapping the wave critically refracted by the second refractor. The estimated crossover distance for a particular CMP corresponds to the vertical offset of the color change on that CMP's midpoint sorted CMP traveltime curve, from the upper horizontal station number axis. This axis is located at offset 0.< E= 1"= # Source type # & Source typeSpecify the source type used to excite the ground, by selecting the corresponding entry from this drop down list box. The value of this field is not regarded during processing.< = _ 1_  Spread type#  , & Spread typeUse this drop down list box to specify a spread type different from the Default spread type, as specified earlier.A_ P 1P  Spread type name  , &Spread type namePlease enter a unique name (up to 31 characters long) identifying the new spread type to be created. Once you have filled in all edit fields of the Create New Spread Type dialog and hit RETURN, the software will verify that this name has not yet been used. If it is not unique, a corresponding error message will be displayed and the focus will be returned to this edit field.LP W 1W  Start tomography processing  & Start tomography processingClick on this button once you have reviewed and optionally adapted the WET tomography processing parameters.CW L1!L6@Static Corrections 6@, &eStatic CorrectionsUse this button to bring up a dialog which lets you specify parameters used during the process of correcting first breaks for topography features such as local humps (anticlines) or troughs (synclines) and for shot position offsets (hole depth / inline offset / lateral offset). This correction is necessary to obtain realistic CMP velocity estimates for the maximum deL6@ pth reached by refracted / turning rays.BLx@1)x@_AStation elevation6@_A, &wStation elevationSpecify the elevation of the station located at position Station position, in meters. Use an appropriate coordinate system. Normally, this will be above sea level.@x@A1ABStation spacingP'_AB) O Station spacingSpecifies how many meters correspond to one station number interval. Normally (i.e. in an equidistant spread type, where all adjacent receiver positions are separated from each other by one station number interval), the station spacing is equivalent to the receiver spacing.EA4C1 4CCStation x coordinateBC, &3Station x coordinateSpecify the x coordinate of the station located at position Station position, in meters. Use an appropriate coordinate system.E4C>D1 >DEStation y coordinateCE, &3Station y coordinateSpecify the y coordinate of the station located at position Station position, in meters. Use an appropriate coordinate system.I>DLE1LEFStore nth iteration only~EF2 2Store nth iteration onlyYou may edit this value n such that Surfer grid files are stored for each nth iteration only. This will help to preserve free disk space. The default value is 5. For Smooth inversion, Surfer .GRD grid files are written to profile subdirectory GRADTOMO. For Automatic Delta-t-V and WET inversion, grid files are stored in profile subdirectory TOMO.LLEHG1WHGSJSuppress velocity artefacts FSJ, &Suppress velocity artefactsEnable this option to suppress the generation of processing artefacts, i.e. unrealistic velocity variations. Use best for medium and high coverage profiles. See (Winkelmann 1998), top of page 36. If enabled, a candidate ray will be used for modeling of an incremental layer if the ray specific apparent velocity and intercept time (as modeled by local regression on CMP curve, at ray specific offset) both are lower than the mean of apparent velocity and intercept time, as estimated for the next three higher CMP offsets. If this setting is disabled, no candidate ray selection, i.e. filtering / enforcing of CMP traveltime curve continuity, based on apparent velocity and intercept time will occur.CHGJ1JKSurface consistentY-SJK, &[Surface consistentActivate this option in order to compute static first break corrections relative to a floating datum obtained by applying a running average smoothing filter to the topography specified or imported earlier. The filter width may be specified within edit field Topography filter.FJ5L15LNSweep angle [degrees]kKN& Sweep angle [degrees]Use this parameter to specify the width of arcs symbolizing estimated refractor location, in degrees. Note that intercept time methods such as CMP intercept time refraction and Plus-Minus do not deliver the exact lateral location of refractor features. They deliver the layer thickness above refractor only, as measured vertically upwards from the layer's bottom / the refractor's top. The refractor shape may be derived visually from the display by following the outlined curve defined by overlapping segments of adjacent depth arcs, however. Mathematically, this curve is called an envelope.B5LO1-O?O/Table of Contents7N?O# (Table of Contents OT Ҁ̀ /&Q_جք.Z㽡t><򎉂ቂo4CމʘgIntroductionInstallation and licensingSystem limitati?OTNonsStrong refractor curvatureOptimize Windows XPStarting up and profile managementDialog box control and function keysData processing sequence overviewReceiver spread typesStation numbers and spread typesOverlapping receiver spreadsDefining your own layout typesImport and export of layout types?O\ Aʀ %V4㘁艂T k㦍AG*]zOVXbH>Ɣ豶pASCII format dialogSeismic and header data importEditing header dataPicking first breaksSmooth inversionDynamic Poisson's ratio imagingCrosshole survey interpretationBuild your own modelPseudo-2D Delta-t-V inversionRaytracing through Delta-t-V outputXTV inversionWET tomography processingMidpoint breaks displayMapping traces to refractorsT/? L)* w ޳0+zΉTime-to-depth conversionUphole shots and uphole picksMulti-user access to LAN profile databasesWIBU dongle setup and printing sectionsM\|1v|Take shot record number from)/& Take shot record number fromThis parameter indicates how the shot number of the shot currently being imported is determined. It is set automatically, according to the Import data type specified above. You are advised not to change this parameter at will.1|օ1օ}{}, &Taper velocity steps at layer interfacesEnabling this option may result in an enhanced vertical resolution of subsurface layer interfaces, in case of subhorizontal layering and for high coverage surveys (e.g. 15 or more shots per profile). Leave this option disabled in case of strong lateral velocity variation. If this option is enabled, the two velocity values as obtained for each hypothetical incremental layer interface during Delta-t-V inversion are not merged into one value. Instead the estimated velocity at the upper layer's bottom and the inverted velocity as obtained for the lower layer's top are both written as separate triples (inline offset, depth, velocity) to the .CSV file. The second triple (for the lower incremental layer's top velocity) will specify a depth which is computed from the layer interface depth plus half of the thickness of the hypothetical lower layer, as determined during inversion. The resulting model will be slightly too deep i.e. too slow, in most situations and by construction. But this minor deficiency is easily and automatically compensated for during subsequent WET Tomography processing.EօŠ1uŠTarget Sample Format0 }& Target Sample FormatSpecify the target sample format for writing sample values imported to the current trace, in the currently opened Rayfract profile database. Currently, all samples are written as 16-bit Integers, regardless of the setting of this parameter.BŠ41{4mTopography filter9m2 2Topography filterUse this edit field to specify the filter width for the running average filter applied to topography specified or imported earlier, to obtain a smoothed floating datum. See option Static first break corrections method Surface consistent.; 41{Trace sortm{& [Trace sortThis drop down list box lets you specify the sort method of trace data files recorded for this profile. The value specified is not regarded during processing.],؎1+؎wTrace to refractor mapping parameters dialog[{w8 >Ɣ'BTrace to refractor mapping parameters dialogThis dialog is displayed when using ALT-M in your Midpoint breaks display. It lets you parameterize the semi-automatic mapping of first breaks to refractors. This mapping is carried out bas؎w{ed on apparent CMP velocity of the local CMP traveltime curve segment, at the first break to be mapped.> ؎1rTrigger delay4w2 2Trigger delayUse this field to interactively shift the shot specific traveltime curve in the Shot breaks display. The total time shift is the sum of BOTH delay time and trigger delay. The delay time may be changed during (re)import of the shot only.],F1\FETurn around spread 180 degrees during importE& Turn around spread 180 degrees during importTo store the first respectively last binary trace i.e. channel at the last i.e. rightmost respectively first i.e. leftmost receiver position of the receiver spread type chosen, please enable this option. Be sure to specify the shot position correctly when importing shots, with this option. You may want to check the imported shot in Trace|Shot gather, and reimport with adjusted shot position. You may skip all other shots.6F{1g{Units1 E& UnitsThis drop down list box lets you specify the linear distance measuring unit used throughout this profile. The value of this field is not regarded during processing. It is assumed that the station spacing and other relevant distances are specified in meters.H{1rUphole time as measured~Rr, &Uphole time as measuredYou may enter the uphole time as measured (in millisecs.) in the field into this edit field. This field is for documentation purposes only and is not used during processing at this time. Enter the uphole time correction term into the corresponding field as displayed in the Shot dialog just below this field.L1Uphole time correction term}rD Vs.F Uphole time correction termIf you enter a non-zero value (in millisecs.) into this shot header edit field, the corresponding shot is considered as an uphole shot, i.e. as shot from a deep shot hole. First breaks of corresponding traces are corrected for the hole depth by addition of this time correction term when displayed in the Shot breaks display. You may want to optimally fit in these uphole travel times with other traveltime curves in the Shot breaks display by adapting the time correction term iteratively. Start by setting this field to the uphole time as measured at the receiver nearest to the borehole top.zZa  FÀ -ڀbPlease note that direct wave first breaks for shots with an uphole time correction term different from 0 are NOT considered by conventional time-to-depth conversion methods. The Delta-t-V method will regard an uphole pick if the unsigned trace offset (from the top of the shot hole) equals or exceeds the Crossover distance (as specified in the Static Corrections dialog) and if Delta-t-V setting Regard Uphole picks for Delta-t-V inversion is checked only. On the other hand all uphole picks ARE considered (and very useful to increase the degree of angular coverage with wavepaths, resolution in the lower half of the depth section and depth coverage at profile start and end) during WET wavepath tomography processing. See topic Uphole shots and uphole picks for more details. This uphole time correction term is not considered during WET tomography processing.&# < Z1v0 from CMPL2 25v0 from CMPClick this button in order to copy estimated weathering velocities from your Midpoint breaks display (Refractor|Midpoint breaks) into all station and shot point records. Shot position offset corrections will be computed and applied to first breaks automatically.> R1Rv0 from ShotsI2 2/v0 from ShotsClick on this button in order to copy estimated weathering velocities from your Shot breaks display (Refractor|Shot breaks) into all station and shot point records. Shot position offset corrections will be computed and applied to first breaks automatically.DR1*Vertical axis ticks, &uVertical axis ticksUse this Annotations parameters dialog setting to specify the type of axis ticks shown on the vertical Y axis. Select type Major&Minor, Major ticks or No ticks.D 1 Vertical axis title& Vertical axis titleSpecify the vertical axis title in this field. Note that it will be clipped to a length of 32 characters.F 1Vertical exaggerationr& Vertical exaggerationSpecify the ratio of horizontal distances printed or plotted to vertical distances printed or plotted with this parameter. E.g. specify a value of 10, for a ratio of 1:10. Note that the vertical axis of depth sections displayed on screen is scaled to the height of the window containing the display, regardless of the setting of this parameter.D1ZVertical grid lines, &Vertical grid linesUse this setting in the Annotations parameters dialog, to specify the type of auxiliary vertical grid line shown in parallel to the Y axis, at X axis ticks. Select setting Dashed line, Dotted line or No line.?'1A') Vertical scale) 2 2Vertical scaleThis edit field lets you specify to how many centimeters a velocity interval of 1000 m/sec. should be scaled when printing or plotting a velocity section. When printing or plotting a time section, this field specifies to how many centimeters a time interval of 100 msecs. should be scaled. Note that the vertical axis is scaled to the height of the display window containing the section on screen, regardless of the value of this parameter.H'q 1q  Wavepath envelope width)  & Envelope wavepath widthUse this parameter to specify the width (in percent of one period) of the wavepaths used to construct the envelope at the bottom of the tomogram. We recommend to leave this parameter at its default value of 0.0. To obtain somewhat deeper but more uncertain imaging, you may increase this parameter up to a maximum value about 0.1% smaller than the wavepath width.?q ] 1]  Wavepath widths  & Wavepath widthThis parameter lets you specify the wavepath width, in percent of one period of the Ricker wavelet central frequency as specified above. See (Schuster 1993) for details. You may vary this parameter between 2.5 and 10 percent. An increased width will result in wider wavepaths and smoother velocity models as obtained with the WET tomography processing.E] ; 1; @Weathering crossoverD @\ -ڀWeathering crossover Use this edit field in the Delta-t-V Static Corrections dialog to specify the laterally constant estimated average crossover distance (in station numbers) separating direct wave arrivals from refracted arrivals. This parameter is relevant during first break corrections : traces with an absolute source-receiver offset equal to or exceeding the value of Weathering crossover will be corrected for shot hole depth and topography elevation, if CMP gather datum specific static corrections option is selected. Direct wave arrivals will be corrected for shot hole depth and shot posit; @ ion offsets, if either static corrections option No static corrections applied or CMP gather datum specific is selected.P; @1@BWeathering layer velocity limitC@B/ ,)Weathering layer velocity limitThis parameter lets you specify the maximum expected velocity of the direct wave. Apparent CMP velocities above this limit are interpreted as belonging to critically refracted head waves, either mapping the first or the second refractor.K@iB1iBEWeathering sub-layer countDBE, &1Weathering sub-layer countUse this parameter to control weathering velocity estimation in situations of strong possibly nonlinear vertical velocity gradients right below the topography. Uncompacted soil or sand at the topography are typical examples of such situations. Valid values for this parameter are 0 to 1000. The default value is 3. The higher the value, the lower and the more accurate and detailed the resulting weathering velocity imaging will be in general. As a consequence, synthetic traveltimes obtained by raytracing through the model obtained will be slightly slower. So increase this parameter if synthetic traveltimes are too fast (systematic offset between picked and synthesized traveltime curves, in Shot breaks display), compared to times as measured and picked.DiBE1ENGWeathering velocity]+ENG2 2WWeathering velocitySpecify the weathering velocity estimated for this station position, in meters per second. Alternatively, click v0 from Shots or v0 from CMP, in order to automatically copy estimated shot or CMP intercept time refraction weathering velocities, into all station positions.MEG1/G}HWeathering velocity detectedNG}H& yWeathering velocity detectedMedian weathering velocity detected, when carrying out piecewise linear regression over all CMP traveltime curve segments assigned to the weathering layer.1GH1HIKu}HIK& Weigh picks in CMP curvesWe recommend to always enable this option, as per default. With this option enabled, each individual traveltime pick is weighted with the reciprocal of the square root of the distance (in station nrs.) between the trace CMP and the central stack CMP, when constructing CMP stacked traveltime curves. This weighing is essential to ensure that a systematically dipping basement is imaged without artefacts. The individual picks and weights are displayed in the status bar at the bottom of the Midpoint breaks display. Just browse CMPs with F7/F8 and trace a chosen CMP curve with vertical cursor keys.PHK1KMWrite grids for every iterationi7IKM2 2oe<ހWrite grids for every iterationEnable this setting to force the generation of Surfer .GRD grid files for velocity and coverage, for every WET iteration. If enabled, this setting will override the current setting of Interactive WET tomography grid file generation setting Store each nth iteration only.\+K^M1^MNWrite misfit gradients to disk for shot nr.dMN& Write misfit gradients to disk for shot nr.Enter a valid shot number into this edit field to generate disk files of the misfit gradients for the wavepaths of all receivers i.e. traces recorded for this shot. The resulting Surfer formatted .GRD files will be named G001:001.GRD for trace number 1 of shot number 1 etc. See (Schuster 1993) for details.b1^MJO1.JOWrite section coverage grids after each iterationY3N& gWrite section coverage grids after each iterationEnable this option to generate Surfer .GRD formatted disk files showing the coverage of eacJONh velocity model grid cell with wavepaths, after each WET iteration. Disk files will be named COVERG01.GRD for the first WET tomography processing iteration etc.U$JO1 oWrite wavepaths to disk for shot nr.kEo& Write wavepaths to disk for shot nr.Enter a valid shot number into this edit field to generate disk files of the wavepaths for all receivers i.e. traces recorded for this shot. The resulting Surfer formatted .GRD files will be named W001:001.GRD for trace number 1 of shot number 1 etc. See (Schuster 1993) for details.i8؂1 ؂8Write section velocity update grids after each iteration`:o8& uWrite section velocity update grids after each iterationEnable this option to generate Surfer .GRD formatted disk files holding the velocity change / update to be applied to the output of the previous WET iteration. Disk files will be named VELUPD01.GRD for the first WET tomography processing iteration etc.> ؂v1w! vwXTV inversion38#  XTV inversionv- (yTo enable the realistic interpretation of sudden apparent velocity increase in CMP sorted traveltime curves, (Winkelmann 1998) proposes to extend the Delta-t-V gradient layer inversion (Gebrande 1986), with Dix inversion and Intercept Time inversion. These two additional inversion methods allow the modeling of constant-velocity layers. As described by (Winkelmann 1998) and (Gawlas 2001), the XTV inversion reconstructs the 1D velocity vs. depth function v(z) based on XTV data triples, with values X = (reduced) offset, T = (reduced) time and V = apparent velocity. These data triples sample a (reduced) CMP sorted traveltime curve. The inversion is based on the layer stripping principle.k"% XTV inversion is based on three different methods, for inversion of a data triple into a model layer :rV |Pl " " "Modified Dix inversionIntercept Time inversionGradient layer inversion (original Delta-t-V method)1 "' lThe inversion starts with the first XTV triple at the smallest offset X, as determined from the original CMP curve. Once the first layer has been determined by one of above methods, offset and time for all other triples are reduced to the bottom of this first layer. Then the XTV triple at the next smallest offset X is inverted into a second layer, and remaining triples are reduced to the bottom of this second layer. This triple inversion process is continued iteratively, until all XTV triples have been processed.a/|2 2_lWe first describe each of these three inversion methods in detail. We then describe the overall XTV algorithm, which decides what inversion method should be applied to the current XTV triple. All inversion methods are described for the two-layer case only. Since the XTV inversion is based on layer stripping, we only need to deal with two layers (current overburden, current refractor) during each iteration and triple-to-layer inversion step.The modified Dix inversion assumes reflection of a ray. The layer thickness h is determined as follows :2. , l"k@|+ &lD is the unsigned offset X between shot point and receiver.}R+ &lt is the traveltime T between shot point and receiver, separated by offset D.V+ &lV is the measured apparent velocity, at the bottom of the layer i.e. at offset D.0y ol"""""" " The average layer velocity is obtained withVelocities at the top and at the bottom of the modeled layer 8are both set to this average velocity .The Intercept Time inversion assumes critical refraction of a ray, with both overburden and basement layer having a constant velocity. Using intercept time as determined from the XTV triple withthe layer thickness h is determined with is the direct wave velocity (for first XTV triple) or the velocity as modeled for the bottom of the previously determined layer (for reduced XTV triples). \ el" " " "Velocities at the top and at the bottom of the modeled layer are both set to .The Gradient layer inversion method or Delta-t-V method assumes a diving wave ray and a constant velocity-gradient equal to a. So the layer's velocity-depth function is Since the velocity gradient is assumed constant, the diving first-break ray follows a circle segment, between shot point and receiver. Based on the two equationsY l"""""andthe velocity at the top of the modeled layer is determined numerically. Then the layer thickness h isand the velocity at the bottom of the modeled layer is set to the measured velocity V. can be smaller than the velocity measured at the bottom of the overlying layer. So the gradient layer inversion can recognize velocity inversions, at least in some situations. Also, the gradient layer inversion does not use the intercept time . / ,lOur XTV inversion implementation assumes that apparent velocity increases with offset. So XTV triples are sorted by offset, for layer inversion as described here. (Winkelmann 1998) proposes the following XTV inversion algorithm :3@| ƀwPl "!؀ """<Use Intercept Time inversion if the apparent velocity V increases suddenly, between adjacent XTV triples. The Minimum velocity ratio required for application of the Intercept Time layer inversion can be adjusted by the user. Intercept Time inversion can be disabled with XTV parameter Enable Intercept Time layer inversion.Use Dix inversion if both the average velocity (determined with Dix inversion) and the velocity at the top of the modeled layer (determined with Gradient layer inversion) are smaller than the velocity modeled for the bottom of the previously determined layer. You may disable Dix inversion with XTV parameter Enable Modified Dix layer inversion.b- 5 :\Rl "Otherwise use Gradient layer inversion.@Y +lH3۲""⨒sBA candidate XTV triple is optionally rejected if its apparent velocity V or intercept time are larger than average values for the next three XTV triples. This triple filtering has the aim of suppressing reflections erroneously picked as first breaks.Intercept Time layer inversion for multiple adjacent XTV triples as required for Intercept Time layer inversion is not clearly defined, especially if the previous layer has been obtained with Intercept Time inversion as well. You may suppress application of our Intercept Time inversion to multiple adjacent XTV triples, with XTV parameter Allow adjacent Intercept time layer inversion.#+n Ql""""")K:XIf the previous XTV triple was inverted with Intercept Time layer inversion as well, then the velocity for the bottom of the previous layer may be assumed to be the previous , or the apparent velocity V of the previous XTV triple, or any value between these two velocities. Alternatively, can be determined by interpolating between the previous and the apparent velocity V of the current XTV triple. You may specify how should be determined with XTV parameters Overlying layer velocity step and Cu+8rrent layer velocity step. $O ހAl""X"" )K:XC)If the resulting exceeds the previous apparent velocity V, used for inversion of the current XTV triple is reset to V of the previous triple.The XTV inversion ensures that the sum of Overlying layer velocity step and Current layer velocity step does not exceed 100%.If you want to use apparent velocities V (from previous and current XTV triples) exclusively and disregard previous , for determination of the current based on step parameters Overlying layer velocity step and Current layer velocity step, just enable XTV option Prefer measured layer top velocity over inverted. If this option is enabled, the apparent velocity V as obtained for the previous XTV triple and layer is taken as an estimate for the velocity at the top of the current layer. In analogy, the velocity at the top of the previous layer is estimated with the apparent velocity V of the previous-previous XTV triple.(+w% lGO1  Minimum velocity ratio>w% 2lMinimum velocity ratio($% l](5 8QlThe minimum velocity ratio (between apparent velocity V of the current XTV triple and the previous triple) required for application of the Intercept time layer inversion. If the actual ratio is smaller, the Intercept Time layer inversion method will not be applied. Instead, Dix inversion or Gradient layer inversion will be applied to the current XTV triple. Valid ratio values range from 1.01 to 2.5 . This ratio is regarded if XTV parameter Enable XTV Intercept Time layer inversion is checked only. See topic XTV inversion for more details.V%$1 Enable Intercept Time layer inversion, &)Enable Intercept Time layer inversionCheck this XTV option if you want to enable XTV Intercept Time layer inversion. See topic XTV inversion.T#1 Enable Modified Dix layer inversion , &Enable Modified Dix layer inversionCheck this XTV option if you want to enable Dix layer inversion. See topic XTV inversion.^- 1  Allow adjacent Intercept time layer inversionU1 M $ bAllow adjacent Intercept time layer inversion  , &AlCheck this XTV option to enable application of our Intercept Time inversion method, for multiple adjacent XTV triples. See topic XTV inversion for details.NM g 1eg ~ Overlying layer velocity step ~ D V"!""Overlying layer velocity stepThis XTV parameter is used if Allow adjacent Intercept time layer inversion is enabled only. This step parameter may vary between values 0% and 100%. The velocity step determines how needed for Intercept Time inversion of the current XTV triple is obtained, from the previous XTV triple and by interpolation between the previous (step 0%) and the previous apparent velocity V (step 100%). See topic XTV inversion for details.Lg  1 1@Current layer velocity step[~ 1@J b'"#"$Current layer velocity stepThis XTV parameter is used if Allow adjacent Intercept time layer inversion is enabled only. This step parameter may vary between values 0% and 99%. The velocity step determines how needed for Intercept Time inversion of the current XTV triple is obtained, from the current XTV triple and by interpolation between as obtained with step parameter Overlying layer velocity step (current step 0%) and the current apparent velocity V (current step 100%). See 1@~  topic XTV inversion for details.a0 @1Q@CPrefer measured layer top velocity over invertedB1@BD V"%"&Prefer measured layer top velocity over invertedCheck this XTV option to use apparent velocities V (belonging to previous and current XTV triples) exclusively and disregard the previous , for determination of the current , based on step parameters Overlying layer velocity step and Current layer velocity step .j2@C8 >gl"'Overburden velocity is needed for our Intercept Time two-layer case inversion method. If this option is enabled, the apparent velocity V as obtained for the previous XTV triple and layer is taken as an estimate for the velocity at the top of the current layer. See topic XTV inversion for details.KBC1C$HMin. horizontal separationBCG( 5Min. horizontal separationHeader|Profile field "Min. horizontal separation [%]" defines the minimum horizontal station offset applied during coordinate interpolation, in percent of the inline station offset, if no x/y coordinates have been specified. You may want to leave this field at its default value of 25%, for most recording geometry situations.If you import .ASC files with shot and receiver elevations, and then don't specify x/y coordinates for shot and receiver stations (e.g. with COORDS.COR import), x/y coordinates are determined automatically based on the station spacing and elevations specified. If the elevation change between adjacent stations equals or exceeds the station spacing, the horizontal offset between these stations should be zero, according to Pythagoras.C$H% However, we recognize that in practice, the inline receiver separation may vary along the line. In above situation, we therefore set the horizontal offset between these stations to "Min. horizontal separation" / 100 * "Station spacing".PGtH1ctHHCrosshole survey interpretationE"$HH# DCrosshole survey interpretationtHJ/ ,Since version 3.01 we support crosshole traveltime tomography, based on a constant velocity initial model which is iteratively refined with WET Wavepath Eikonal Traveltime tomography processing.We have tested our new crosshole tomography routine with sample survey files made available by our Spanish client I.G.T. International Geophysical Technology. These files are formatted as Daryl Tweeton GeoTomCG .3DD files. See http://rayfract.com/samples/borehole.zip&HJ# JLB RqlTo generate Daryl Tweeton GeoTomCG .3DD input files required by our new crosshole tomography routine, we recommend using TomTime picking software, available from GeoTom LLC. Contact Daryl Tweeton at tweetond@tc.umn.edu or at dtweeton@giscogeo.com . TomTime reads all common seismograph formats, and offers versatile frequency filtering and display options. See http://giscogeo.com/pages/seixgott.html for more information.*J M' luLM' lFor instructions on crosshole data interpretation, see file BOREHOLE.TXT included in borehole.zip and our tutorial* MM' lV,M%N* $Xlhttp://rayfract.com/tutorials/igta13.pdf*MON' lmE%NO( l. We currently regard X and Z coordinates only for crosshole surveys. Y coordinates as specified in GeoTomCG input files are not regarded and are assumed to be all zero.If you want us to support your crosshole data format and samples, you are welcome to send us these files, as long as you have a current support contract.*ON ' lO $HO. *lFor above IGTA13 tutorial a synthetic model is available at http://rayfract.com/samples/swiss.zip . This allows determination of vertical and lateral velocity resolution in WET output. * #' l0S: BlTOur Smooth inversion algorithm implements improved weighting/preconditioning for inversion of crosshole surveys. Velocity artefacts/anomalies at grid corners and at grid edges/directly adjacent to boreholes are suppressed. See Beydoun and Mendes 1989 Elastic Ray-Born L2-Migration/Inversion with abstract at http://www.blackwell-synergy.com/doi/abs/10.1111/j.1365-246X.1989.tb00490.x . See also Luo and Schuster 1991 Wave-equation Traveltime Inversion Appendix B, with abstract at http://link.aip.org/link/?GPY/56/645/1 . Luo and Schuster describe this weighting as Another modification is to use a preconditioned gradient (search) direction (formula). This preconditioning compensates for geometrical expansion (Beydoun and Mendes, 1989). *#}' ld<S( ylThe high sensitivity of WET to velocity variations directly at source/receiver is welcome for surface refraction surveys, since receivers are located close to the shot point in this case. For borehole surveys, the closest receiver is in the other hole. So velocity variation at source/receiver cannot be measured reliably in this case, and needs to be suppressed during tomography processing. More weight is given to the central portion of the subsurface section, located between the two boreholes. The fundamental assumption is that for borehole surveys, there are no large velocity variations, i.e. minimum velocity smaller than e.g. 50% of maximum velocity. For surface refraction surveys, minimum velocity (directly below topography) may be as small as 10% or less of maximum subsurface section velocity (in basement). *} ' lv4 6lTo disable dynamic Beydoun weighting during WET inversion of borehole surveys, check Smooth invert|Precompute static Beydoun weight matrix. Static weighting assumes that each pixel is affected by all wave paths. Dynamic weighting does not make this assumption. Static weighting is more conservative, and a compromise between dynamic weighting and no weighting at all.t oF Zl{ 8mUse option Smooth invert|Beydoun weighting for borehole WET to enable or disable Beydoun weighting.Use option Coverage grid shows unweighted hit count. If unchecked, the coverage grid shows the hit count of each grid cell, scaled by Beydoun weighting (if enabled).To display Daryl Tweeton GeoTomCG .3DD files in a readable way, please proceed as follows :*' l)oŒh Pl " " " "select Start|Runenter "Wordpad.exe" without the enclosing "" and click OKselect File|Open in Wordpad programnavigate to your \RAY32\DOC directory and select e.g. IGTA13.3DD*' Ȃ!jŒ4 6!TTo enable or disable posting and labeling of shot points and/or receivers on WET tomograms, check or uncheck the corresponding menu item in menu Grid before starting our Smooth inversion. You dont have to redo the Smooth inversion to redisplay WET tomograms with/without posting and labeling of shot points and/or receivers. Proceed as follows instead :)& v Pl " "w^ " " " "check or uncheck corresponding items at bottom of menu Gridselect Grid|Image and contour velocity and coverage grids...select desired WET tomogram grid fil$He e.g. VELOIT20.GRD (output after 20 WET iterations), storedin profile subdirectories GRADTOMO (Smooth inversion),BOREHOLE (crosshole survey) or TOMO (pseudo-2D Delta-t-V inversion).*' l1.1.Q*' TlPrecompute static Beydoun weight matrix*.' lH ( AlStatic weighting assumes that each pixel is affected by all wave paths. Dynamic weighting does not make this assumption. Static weighting is more conservative, and a compromise between dynamic weighting and no weighting at all. Disable/uncheck this option to specify dynamic weighting.1"1i"ZJ&l$ LBeydoun weighting for borehole WET"Z1 0{lCheck this option to enable Beydoun weighting, uncheck to disable Beydoun weighting. Use option Precompute static Beydoun weight matrix to specify static or dynamic Beydoun weighting.1l1'P,Z$ XCoverage grid shows unweighted hit countL'1 07lIf this option is unchecked, the coverage grid generated by borehole WET shows the hit count of each grid cell, scaled by Beydoun weighting (if enabled, with option Beydoun weighting for borehole WET). With this option checked, the coverage grid shows the unweighted hit count.1X1X'' Output inversion results in FeetCheck this option to generate tomograms in feet. Uncheck to generate velocity tomograms in meters.1X81?8FF2 2Scale WET filter heightCheck this Smooth inversion option to scale WET tomography processing smoothing filter height, with depth below topography. This ensures better vertical resolution of the weathering layer, and fewer artefacts at the bottom of WET tomograms. Also, the misfit between modeled and picked first breaks decreases faster during WET inversion (with fewer iterations). This option is checked per default, for profiles with 48 or more receiver stations.18w1w[F[, &qAllow missing traces for SeisOpt and Gremix filesCheck this option to enable import of SeisOpt and Gremix files with missing unpicked or dead traces. If there are traces missing from SeisOpt or Interpex Gremix input data files, these missing traces are regenerated during import automatically for the active part of the receiver spread type specified. This option is checked/enabled per default, when creating a new profile database.1w1: [2 2X coordinate is corrected for topography alreadyWith this option checked, our import routine will determine the inline offset between adjacent receivers with Pythagoras of (corrected for elevation change) true x and z coordinate offsets. If this option is unchecked, the inline offset is assumed to be the (uncorrected for elevation change) inline x coordinate offset. This inline offset is then used to match planted receivers to spread type receiver positions.1118 >R?hDefault layout start is 1.0Check this option to make our import routine use the default value 1.0 for the layout start of the first shot, in the Import shot dialog. With this option unchecked, the layout start defaults to 0.0. This option is checked per default. If you uncheck import option Keep same Layout start for consecutive shot trace files, layout start and shot position will be determined directly from the SEG-2 trace headers instead.1 1  & yDefault distance unit is meterCheck to specify distance unit meter, for OPTIM LLC SeisOpt and Geometrics SeisImager PickWin/PlotRefa .VS file import. Uncheck to specify distance feet.1 1& qDefault time unit is secondsCheck this option, to specify time unit seconds for first breaks specified in OPTIM LLC SeisOpt input files. Uncheck to specify time unit milliseconds.1.1<.9 9) Keep same Layout start for consecutive shot trace filesThis import option is unchecked per default, starting with version 3.07 of our software. When using earlier versions, this option is checked per default. With this option disabled/unchecked, our import routine determines layout start and shot position directly from the SEG-2 trace headers. SEG-2 trace header fields SOURCE_STATION_NUMBER and RECEIVER_STATION_NUMBER override fields SOURCE_LOCATION and RECEIVER_LOCATION.1.j1 jz92 2R?hKeep same sample count for consecutive shot trace filesCheck this option to have our import routine reuse the sample count specified for the previously import shot, as specified in the Import shot dialog. With this option unchecked, our import routine will determine the sample count directly from the SEG-2 shot file header. This option is checked/enabled per default.1jG1!Gc, &Adjust wavepath widthCheck this option to make WET determine the wavepath width for each trace individually, as a linear function of the picked time. Earlier picks will result in smaller wavepath width. This ensures improved overburden resolution, and more smoothing/less artefacts in the basement (at the bottom of the velocity tomogram). Uncheck this option to make WET use the constant wavepath width as specified in WET Tomo|Interactive WET tomography or as determined automatically, for our Smooth inversion method. This option is enabled per default, for profiles with 48 or more receiver stations.1G 1"  H P nGridding methodSpecify the Surfer gridding method used for gridding of pseudo-2D Delta-t-V inversion results, with this Delta-t-V export option. You may select methods Delauney Triangulation, Kriging, Minimum Curvature, Natural Neighbor and Nearest Neighbor. Per default this option is set to method Kriging.1  1# 0 :  D VGrid and image Delta-t-V .CSV fileFor our pseudo-2D Delta-t-V inversion, you may want to use a different Surfer gridding method than the default kriging method. Specify your preferred gridding method via Delta-t-V|Interactive Delta-t-V|Export Options|Gridding method. Confirm with Accept button. You can then abort the interactive Delta-t-V inversion with Cancel button. Now regrid the DELTATV.CSV generated during an earlier inversion, with Grid|Grid and image Delta-t-V .CSV file... .& 0 # 1 a 1c$a  AQ0  @D V vI+Image and contour velocity and coverage gridsUse this Grid menu command to automatically image previously generated Surfer .GRD grid files (velocity tomograms and coverage grids) with Surfer. Just select the desired VELOITXX.GRD (e.g. VELOIT10.GRD for WET iteration 10). Our software will then automatically image both the VELOITXX.GRD and the corresponding COVERGXX.GRD (if existing). You may flip over velocity tomograms with Grid|Turn around grid file by 180 degrees... , and convert tomograms between feet and meter with Grid|Convert grid file between feet and meters... . a  @0 a  A9 @HSurfer .GRD files are stored in profile subdirectories GRADTOMO (1D gradient based Smooth inversion), TOMO (pseudo-2D Delta-t-V inversion) and BOREHOLE (Crosshole survey interpretation).1 @:A1%:ACv> AB8 >}w^Convert grid file between feet and metersUse this Grid menu command to convert previously generated velocity tomograms VELOITXX.GRD (and matching coverage grids COVERGXX.GRD, if existing) between feet and meters. Then image the converted tomogram with Grid|Image and contour velocity and coverage grids... .:AC; DHSurfer .GRD files are stored in profile subdirectories GRADTOMO (1D gradient based Smooth inversion), TOMO (pseudo-2D Delta-t-V inversion) and BOREHOLE (Crosshole survey interpretation).1BC1&C8FY!C;E8 >Cw^Turn around grid file by 180 degreesUse this Grid menu command to flip over previously generated velocity tomograms VELOITXX.GRD (and matching coverage grids COVERGXX.GRD, if existing). Then image the flipped tomogram with Grid|Image and contour velocity and coverage grids... .C8F9 @HSurfer .GRD files are stored in profile subdirectories GRADTOMO (1D gradient based Smooth inversion), TOMO (pseudo-2D Delta-t-V inversion) and BOREHOLE (Crosshole survey interpretation).1;EiF1 'iFEG8FEG2 2ULine typeSpecify Refraction spread/line for surface refraction profiles. Specify Borehole spread/line if receivers are placed in vertical or horizontal borehole.1iFvG1(vGHBEGHD VkRxImport horizontal borehole survey or .3DD refraction surveyCheck this option before importing .3DD GeoTomCG files into a profile with Line type Borehole spread/line, with receivers in a horizontal borehole. Or check before importing .3DD refraction survey into profile with Line type Refraction spread/line.1vG-I1?)-I;KH;K2 2Round shot station to nearest whole station numberUncheck this import data setting to round shot stations to nearest .5 during import, e.g. to station number 0.5, 1.0 or 1.5. This ensures a consistent traveltime curve display in Refractor|Shot breaks even once first break picks are corrected for inline and lateral offset of shot points. Also reciprocal traveltime errors are now easier to recognize for small source-receiver offsets, in Trace|Offset gather display.1-IlK1V*lKL%;KL> J]zOTAllow unsafe pseudo-2D Delta-t-V inversionIf you want to invert your first breaks with our pseudo-2D Delta-t-V method, first run Smooth inversion. Then check this Smooth inversion setting, to enable our Delta-t-V menu.1lK1+ hMS Sans SerifSymbolArialCourier NewTimes New RomanWingdingsArial BlackAntique Olive CEArial Rounded MT Bol02020603050405020304AngsanaUPC$$ ,* $_'tW !q* r)"l',)ۂ)ǂ&G o[6"K 8% \" ]" &ʉ<܀&#V# #H(!H pE+z#&&3$IV#q#*;9$6*,b'D%Z$( C#%YS$A"=#X)#Ā H r !E߇%l8 #c(s!@o!2',^)"Y#2-?&J(BR*C '#@: (k"s*h) %ׁ!$*1a% }&j%>#%6(*G$5NJ&"&"D)#8ف"M)m"!6&G&yV'%ۃ!#"2) $4<(yp"# W } V*k n*C$  _$$n+`" 7`'KF#&*Y(F )p)s؃ FF'G  &D%=6#{<'-wd{,0s%m#3Bփ%O )n!1#t". p#o!?&&Yn "i%(؀$['\1'Q!/ ~' &71EW*2&M%0 vq(*mD !E!{ 1 /!(7~*~,"$(Z$$r̂"2T $9Ʉ!e"%$i $E$] 3" Ӏ% ( {( (w,"+Z$ 4 w$A#g" *"  )J %v %''߇!x *!5 8!,4 < (W$9%}'t( x5"!j, u0""'6,-8)' , 5"#o*^''&2$#H !]'&:%M&[#Y"$$. $U" "|'~ʉ.%,ޅ-̄" ۅ)B "È<<E[ w   T "    K  Ā. W 3- , (ό , .m-! ʂ . "!Q!D !@r !W !5W5!ۃ!gɄ!! ,{,߇!"t" <n " "{.3."" ̂""It . G P "*"##t.V. 4 ##V# 8 ##V##! /#ݍ#p#6##Ƀ$$vw,$$, $$ $$؀$f̈l G$$z-Z$@ ,%"-%,x%M%#%J %v % %% s%%փ%#%a% ߇%Έ%&6&m&& #g & &ǂ&ĂΌ&&&&- Ā ''F' ''1' Hۈ''''V'Ā 'U b'((P-((!( (x(  ({((.. (q(( ())5); )x/)Ȃ.) ۂ) )8)nj*T*p~**x *+*,*W*o**#*E++-+) C /0&0;)F24&Cabsolute elevationsActive tracesAdjust elevation to fit XY coordinatesAdjust wavepath width Adjust XY coordinates to fit elevationAGC Window lengthAllow adjacent Intercept layer inversionAllow gaps in coverage of velocity model grid columnsAllow missing traces for SeisOpt and Gremix files Annotate axes$Annotation parameters dialog(Annotations inside view port,ASCII format dialog0Automatically adapt shape of rectangular filter matrix4Automatically estimate v08Axis big tick size<Base filter width@Basement crossover filterDBatch importHBranch pointLBuild your own modelXCancel Import\Central filter weight`Central Ricker wavelet frequencydClienthClip amplitude peaks for current trace displaylCMP curves stack widthpCMP gather datumtCMP Intercept Time Refraction processingxCMP Stack Width|CMP traveltime curveColumn 1Column 10Column 2Column 3Column 4Column 5Column 6Column 7Column 8Column 9Common Mid Point (CMP)CompanyContext sensitive online helpConvert grid file between feet and metersCopy v0 from Station editorCorrect all velocities for Delta-t-V systematic errorCorrect basement velocities for Delta-t-V systematic errorsCorrect breaksCorrect xCorrect yCoverage grid shows unweighted hit countCritical foldCrosshole survey interpretationCrossover distanceCrossover processingCurrent layer velocity stepData processing sequence overviewDate of AcquisitionDefault distance unit is meterDefault layout start is 1.0Default shot hole depthDefault spread typeDefault time unit is seconds Defining your own layout typesDegree of differentiation of Ricker waveletDegree of Surface ConsistencyADelay timeDelete traveltime grid files for last WET iteration Delta-t-V inversion$Depth below topography(Detect shifted 32-bit floating point sample data start,Dialog box control and function keys0Direct Wave4Direct Wave Offset Delta8Display parameters dialog<Do AGC for current trace gather display@Do not adjust coordinatesDdo not exportHDynamic Poisson's ratio imagingLEdit grid file generationPEdit velocity smoothingTEditing header dataXEnable Intercept Time layer inversion\Enable Modified Dix layer inversion`End shot importdExport OptionshFar offset shot pointslFilter tracespFilter widthtFirst breakxFirst break envelope length|First break stabilization factorFirst refractor velocity limitFull smoothing after each tomography iterationGeneral constantGrid and Image Delta-t-V .CSV file...Gridding methodHalf smoothing filter heightHalf smoothing filter widthHeader lines to skipHorizontal axis ticksHorizontal axis titleHorizontal grid linesHorizontal scaleImage and contour velocity and coverage gridsImport data typeImport shot dialogImport shotsImport shots dialogImport/export of layout typesInput directory Select buttonInstallationInstrumentInterpolate coordinatesIntroductionInverted polarityJob IDKeep same Layout start for consecutive shot trace filesKeep same sample count for consecutive shot trace filesLayout startLeast deviationsLeast squaresLeft handed coordinatesLimit maximum basement velocityLimit offsetlimit velocity exported Line identificationManual specification of smoothing filterMaximum basement velocityMaximum elevationMaximum offset imported  of Surface ConsistencyAMaximum propagation velocity$Maximum station number(Maximum tolerance,Maximum valid velocity0Maximum valid WET velocity4Maximum velocity exported8Maximum velocity or time<Maximum velocity update@Midpoint breaks displayDMin. horizontal separationLMinimal smoothing after each tomography iterationPMinimum elevationTMinimum propagation velocityXMinimum station number\Minimum velocity or time`Minimum velocity ratiodModel Parameters dialoghnegative depthslNo static correctionspNotetNumber of WET tomography iterationsxObserver|Offset breaks displayOffset limitOffset limit basement coverageOptimize Windows XPOutline axesOutput Delta-t-V Results in feetOutput inline CMP pos. in metersOutput inversion results in FeetOutput Measured CMP VelocitiesOverburden crossover filterOverburden filterOverlapping receiver spreadsOverlying layer velocity stepOverwrite allPicking first breaksPlus Minus and Wavefront processingPrecompute static Beydoun weight matrixPrefer CMP overburden mappingPrefer measured layer top velocity over invertedPrefer regressed traveltimesprocess all CMPProcess CMP sorted traveltime curvesProcess every CMP offsetProcessing dateProcessing timeProfile start offsetPrompt overwritingRaytracing through Delta-t-V outputRead shotReceiver countReceiver depthReceiver in line offsetReceiver lateral offsetReceiver separationsReceiver spread typeReceiver type Recompute traveltime characteristicsReduced offset 0.0 is valid trace with time 0.0Reduction velocityReference topography smoothing filter widthRefracted Wave Offset Delta Refractor 1 velocity detected$Refractor 2 velocity detected(HRefractor branch,Refractor Count0Refresh breaks display<Regard uphole picks for Delta-t-V inversion@Regression over offset stationsDRegression Receiver CountHRelative regression toleranceLRemapPRemap all tracesTRemove systematic dc offsetXReset coordinates and v0\Reset v0`Sample countdSample IntervalhScale WET filter heightlSearch window widthpSEG-2tSeismic and header data importxSelect|Select coordinate fileSelect initial velocity modelSemi-automatic first break pickingSeparator (one character)set to max. exportedShot acquisition dateShot acquisition timeShot breaks displayShot depthShot gather displayShot in line offsetShot lateral offsetShot NumberShot point is zero time traceShot positionShow axis titlesskip every 2ndSkip every second shot for forward modelingSkip shotSmooth crossover distancesSmooth invert|Beydoun weighting for borehole WETSource typeSpread typeSpread type nameStart tomography processingStarting up and profile managementStatic CorrectionsStation elevationStation numbers and spread typesStation spacingStation x coordinate Station y coordinateStore nth iteration onlyStrong refractor curvatureSuppress velocity artefacts$Surface consistent(Sweep angle [degrees],System limitations0Table of Contents4Take shot record number from8Target Sample Format<Tile horizontal@Time of AcquisitionDTopography smoothing filterHTrace processingLTrace sortPTrace to refractor mapping parameters dialogTtrial licenseXTrigger delay\Turn around grid file by 180 degrees`Turn around spread 180 degrees during importdUndo trace correctionshUnitsled(Uphole shots and uphole pickspUphole time as measuredtUphole time correction termxv0 from CMP|v0 from ShotsVertical axis ticksVertical axis titleVertical exaggerationVertical grid linesVertical scaleWavepath envelope widthWavepath widthWeathering crossoverWeathering layer velocity limitWeathering sub-layer countWeathering velocityWeathering velocity detectedWET tomography processingWrite grids for every iterationWrite misfit gradients to disk for shot nr.Write section coverage grids after each iterationWrite section velocity update grids after each iterationWrite wavepaths to disk for shot nr.X coordinate is corrected for topography alreadyXTV inversion offsetShot NumberShot point is zero time traceShot positionShow axis titlesskip every 2ndSkip every second shot for forward modelingSkip shotSmooth crossover distancesSmooth invert|Beydoun weighting for borehole WETSource typeSpread typeSpread type nameStart tomography processingStarting up and profile managementStatic CorrectionsStation elevationStation numbers and spread typesStation spacingStation x coordinate Station y coordinateStore nth iteration onlyStrong refractor curvatureSuppress velocity artefacts$Surface consistent(Sweep angle [degrees],System limitations0Table of Contents4Take shot record number from8Target Sample Format<Tile horizontal@Time of AcquisitionDTopography smoothing filterHTrace processingLTrace sortPTrace to refractor mapping parameters dialogTtrial licenseXTrigger delay\Turn around grid file by 180 degrees`Turn around spread 180 degrees during importdUndo trace correctionshUnitsled(Delay timeMaximum propagation velocityRefractor branchUphole shots and uphole picks/&;)Lzz/(&(;)Lz,0GIntroductionInstallation and licensingSystem limitationsStrong refractor curvaturel Optimize Windows XPxStarting up and profile managementDialog box control and function keysData processing sequence overview Receiver spread types Station numbers and spread types@ Overlapping receiver spreads Defining your own layout typesP Import and export of layout types ASCII format dialogĀ Seismic and header data import Editing header dataPicking first breaksSmooth inversiongDynamic Poisson's ratio imaging<Build your own model@Pseudo-2D Delta-t-V inversionRaytracing through Delta-t-V outputoWET tomography processingMidpoint breaks display} Mapping traces to refractorsTime-to-depth conversion Uphole shots and uphole picksMulti-user access to LAN profile databases WIBU dongle setup and printing sections~Absolute elevations Acquisition date5Acquisition timeActive tracesAdjust X coordinate to fit Y and elevationʉAdjust Y coordinate to fit X and elevationAGC window lengthAllow gaps in coverage of velocity model grid columns,Annotate axesAnnotation parameters dialog"Annotations inside view portAutomatically adapt shape of rectangular filter matrixAutomatically estimate v0[Axis big tick sizeBase filter widthKBasement crossover filter Batch import Branch pointCancel importdCentral filter weight<Central Ricker wavelet frequencyEClientClip amplitude peaks for current trace displayCMP curves stack widthCMP gather datumMCMP Stack Width1CMP traveltime curvewColumn 1Column 10 Column 2 Column 3 Column 4 Column 5T Column 6" Column 7 Column 8 Column 9 Common Mid Point (CMP)K Company Context sensitive online help Copy v0 from Station editor Correct all velocities for Delta-t-V systematic errorJ Correct basement velocities for Delta-t-V systematic errors{ Correct breaks؃ Correct picks for delay timeW Correct x Correct y Critical fold] Crossover distance!Default shot hole depth!Default spread type"!Degree of differentiation of Ricker wavelets!Degree of Surface ConsistencyQ!Delay timeD !Delete traveltime grid files for last WET iterationr !Depth below topographyW !Detect shifted 32-bit floating point sample data start!Direct Wave!Direct Wave Offset Deltaׁ!Display parameters dialog!Do AGC for current trace gather display!Do not adjust coordinatesۃ!Do not exportɄ!Edit grid file generation!Edit velocity smoothing߇!End shot importb!"Export Options"Far offset shot points`"Filter traces"Filter widthY"First break envelope length6"First break stabilization factort"First break time"First refractor velocity limitn "Full smoothing after each tomography iteration "General constant* "Half smoothing filter height"Half smoothing filter widthف"Header lines to skip̂"Horizontal axis ticks"Horizontal axis title"Horizontal grid lines"Horizontal scale"Import data type"Import shot dialog0"Import shots"Import shots dialog"Input directory Select button"Instrument*"Interpolate coordinates#Inverted polarity#Job ID#Layout start#Least deviations#Least squaresV#Left handed coordinates#Limit maximum basement velocity8 #Limit offset#Limit velocity exportedV#Line ID#Manual specification of smoothing filter#Maximum basement velocity#Maximum elevation#Maximum offset importedY#Maximum propagation velocity)#Maximum station number#Maximum tolerancep#Maximum valid velocity6#Maximum valid WET velocity#Maximum velocity exported$Maximum velocity or time displayed$$Maximum velocity update$$Minimal smoothing after each tomography iteration$Minimum elevation%$Minimum propagation velocityP$Minimum station numberS$Minimum velocity or time displayedw$Model Parameters dialog$Negative depths$No static corrections $Note$Number of WET tomography iterations؀$Observer9$Offset breaks display$Offset limit$Offset limit basement coverage $Outline axesG$Output Delta-t-V Results in feet$Output inline CMP pos. in metersZ$Output Measured CMP Velocities2$Overburden crossover filter $Overburden filter%Overwrite all)%%Prefer CMP overburden mapping%Prefer regressed traveltimes%Process all CMPM%Process CMP sorted traveltime curves#%Process every CMP offsetJ %Processing datev %Processing time %Profile start offset%Prompt overwritingӀ%Read shots%Receiver count%Receiver depthփ%Receiver in line offset#%Receiver lateral offseta%Receiver separations߇%Receiver type%Recompute traveltime characteristics%Reduced offset 0.0 is valid trace with time 0.0&Reduction velocity6&Reference topography smoothing filter width2&Refracted Wave Offset Delta&Refractor 1 velocity detected&Refractor 2 velocity detected}&Refractor branch&Refractor Count&Regard uphole picks for Delta-t-V inversion &Regression over offset stations&Regression Receiver Count܀&Relative regression toleranceǂ&Remap&Remove systematic dc offset&Reset coordinates and v0&Reset v0&Sample count&Sample Interval?&Search window widthNJ&SEG-2'Select'Select coordinate fileF'Select initial velocity model`'Separator (one character)'Set to max. exported'Shot acquisition date1'Shot acquisition time'Shot breaks display'Shot depth'Shot gather display'Shot in line offset'Shot lateral offsetV'Shot Number 'Shot point is zero time trace<'Shot position'Show axis titlesb'Skip every 2nd(Skip every second shot for forward modeling(Skip shoti(Y(Smooth crossover distances(Source type(Spread type!(Spread type nameK (Start tomography processing< (Static Corrections(Station elevation(Station spacing(Station x coordinate{(Station y coordinate(Store nth iteration only(Suppress velocity artefactsq(Surface consistent(Sweep angle [degrees] (Table of Contents)Take shot record number from))Target Sample Format)Topography filter )Trace sortO )Trace to refractor mapping parameters dialog)Trigger delay)Turn around spread 180 degrees during importۂ)Units)Uphole time as measured8)Uphole time correction term2)v0 from CMP*v0 from Shots*Vertical axis ticks*Vertical axis titleR*Vertical exaggeration*Vertical grid lines*Vertical scale~*Wavepath envelope width*Wavepath widthx *Weathering crossover*Weathering layer velocity limit*Weathering sub-layer count,*Weathering velocityW*Weathering velocity detected**Write grids for every iteration*Write misfit gradients to disk for shot nr.#*Write section coverage grids after each iteration+Write wavepaths to disk for shot nr.E+Write section velocity update grids after each iteration+XTV inversion,Minimum velocity ratio,Enable Intercept Time layer inversion{,Enable Modified Dix layer inversion,Allow adjacent Intercept time layer inversion,Overlying layer velocity step ,Current layer velocity step,Prefer measured layer top velocity over invertedw,Min. horizontal separation,Crosshole survey interpretation-P-3-z--ޅ--m-5-.t.V..3.{.t .Ā.Ȃ..W..u.\.date1'Shot acquisition time'Shot breaks display'Shot depth'Shot gather display'Shot in line offset'Shot lateral offsetV'Shot Number 'Shot point is zero time trace<'Shot position'Show axis 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