Tutorial on Seismic Reflection CDP Data Processing in the
Contents
1. Comments can be added to the copied values in the window just type them manually When you are finished with the velocities save the file selecting the command File Save in the menu of additional window and then close the window My Project My Area Line 1 030 preproc Zoom Common parameters Tools Exijotop How Exit v 1 65 OFESET ms MM Save parameters in file E E x v 1 65 0FFSET ms Estimate the spectrum of different parts of the record For this use the Tools Spectrum Average menu command My Project My Area Line 1 030 preproc Zoom Common parameters MEMES eit Stop tow Exit Approximate Spectrum Pick A yerage D Spectrum Wells Static corrections k Apply procedure Write History Amplitude editing b Trace Header Math Reflect header changes in Reflect ident Fields Text hint Print gt Save ima n 92 0 2 ar ae fF j Tis e e reves pS tt i Correction for amplitude attenuation To compensate amplitude attenuation add the Amplitude Correction module into the flow Place it between the modules Trace Input and Screen Display Changing the parameters of the module and each time executing the flow you can test different types of amplitude corrections For purposes of the subsequent processing spherical divergence correction is a good choice In order to apply this correction set the parameters of the modu2. a ih A ae y i if i AM A N i IN W f i y Hi hi i i ee y VA i WERI ih AN IAAI T IN f i 10 y pny r NINE if i i 1 Mi Li IRI U CIN Sy yi wii Ai iM E A A A 8 ee ee ee ee ee ee ee T 1 F M Y E MN m FF ee a es i Y j e yes rash ee A yuan ql of he A AW J 7 a gt gt o gt gt ra gt Tr i179 Sam 745 Amp 3 19 t 2980 0ms ma Hl ln eco e HO COMTAPA 2007 r Trace amplitude equalization The amplitudes recorded by each seismic receiver 1s influenced among other things by the conditions around the source and the receiver When the data is not aimed for the dynamic interpretation for example for the purposes of AVO analysis it is not necessary to use the complex procedures of the surface consistent amplitude corrections instead you can try to reduce the differences between traces by the simple traces equalization To do this add the module Amplitude Correction into the flow again with the following set of the parameters i 31 Amplitude Correction Action to apply 1 000000 0 000000 100 000000 MEAN CENTERED Spherical divergence correction l s Exponential correction dB s Automatical Gain Control Operator length ms Type of AGC scalar Basis for sc
3. PIECO GEOPHYSICAL Tutorial on Seismic Reflection CDP Data Processing inthe RadExPro Plus software Edition of 21 11 2007 DECO Geophysical OOO Moscow State University Science Park Leninskiye gory 1 77 119992 Moscow Russia Tel Fax 7 495 930 94 14 E mail support radexpro com Internet www radexpro ru Content Creatine a RadExPro Plus FE diia 3 Loading raw data into the project a DATA AAT A BY TRACE A e aas 24 Sorn races Dy CDF eg EMCEE RT REO E wave TO A A IA TTT TET Ce AAA E AAA TT eT Tor AAA 24 Correction for amplitude A ii al O O 52 BA a Oe ET OR eee Ne ee eee ee ee eee ee ee 57 Introduction This tutorial is intended for the users who begin to process seismic reflection CDP data in the RadExPro Plus program All standard stages of basic CDP processing are discussed from the introduction of geometry to stacking that is the so called minimal processing sequence It is assumed that the user is already familiar with the theory of the CDP reflection method and with the fundamental technology of processing such data The processing is conducted on an example of the real data which can be downloaded from our Web site http radexpro ru upload file tutors CDP inpdata zip The archive contains initial data for the work a fragment of an on shore seismic profile recorded in SEG Y format file line _1 sgy with the trace headers containing source point and receiver point numbers and two
4. Clit lat 14 A4 Number of traces 23954 i BM Floating Paint Trace length 750 i Use trace weighting factor le SEGY Normal byte order MSB First f SEGY Reverse byte order LSB First Sorted by FFID OFFSET f Get all f Selection f 30 Survey 2D Survey Profile ID i Remap header value RECNO 41 187 SOURCE 4165 Add Delete Load list Save list Load remap Save remap Ok Lancel Remap of header fields Some seismic data formats allow trace header remapping that is storage in the trace headers of some values not provided by the standard Sometimes the values are recorded in a non standard format of number representation or in a non standard position within the header As a rule contemporary software packages provide a possibility to indicate explicitly from what byte from the beginning of a header and in what format to read the values saved this way In the training file line_1 sgy the header fields containing the number picket of source and receiver position are recorded as integer 4 byte numbers in bytes 181 184 and 185 188 are saved this way The remap string shown above will allow for reading them from there and saving into the RECNO and SOURCE header fields of the RadExPro Plus database RadExPro header fields The RadExPro software uses its own set of header fields for storing auxiliary information about seismic traces The values of header fields are associated with the trace
5. database object name where the velocity pick 1s to be stored as shown on the following figure 42 Choose velocity picks Object name veld Objects Location data load geometry check preproc Velocity analysis Rename Delete It is reasonable to store the velocity picks at the second level of the database corresponding to the line Now specify the same velocity pick as an input velocity function It will be useful if you decide to return to the velocity analysis later and to continue the work with the pick For this in the Input Velocity tab assign the same parameters as on the previous one Interactive Velocity Analysis PS PP velocities Semblance Display Gather Display FLF Display LYS Display Super gather Input velocity Output velocity Semblance C Single velocity function f Use file Browse Database picks vell r Bross Velocity domain Velocity type a ES f AMS C Interval Save template Load template OF Otmena Important When assigning a new velocity pick 1ts name must be specified first on the Output Velocity tab and only then on the Input Velocity tab Otherwise the program reports an error message 43 Now select the tab Super gather and switch off the Bin offsets option This option allows for summing up the traces with the close offsets before calculating the velocity spectrum This would result in much faster calculation
6. 109 o ann arr a0000 arse 274820000 ini nmo MOM To save the changes in the database on exit from the Geometry Spreadsheet select Yes or use the Edit Save changes menu option Geometry spreadsheet k P A Bo you want to sawe changes before exit Sorting the data by CDP and control of the assigned geometry To verify the correctness of geometry assigned make the following Create a new flow name it 020 geometry check 18 f RadExPro 3 7 gt gt gt My Project Help Options Database Tools 010 data load O20 geometry check Pi My Project My Area Line 1 020 geometry check Help Options Database Tools Run Flow mode Trace Input lt line 1 raw Stacking Ensembles screen Display Ensemble Stack Asymptotic CCP Binning Deconvolution Deconvolution Predictive Deconvolution Ssurface Consisteni DeconvoluitCusiom impulse Trace Transforms Nonstationary predictive deconvolution Interactive Tools screen Display 30D Screen Display OC Anafpsis MB1 Drag module Ctrl MBi Copy module MB1 DblClick Module Parameters MB2 Toggle module Ctri MB2 DblClick Delete 2 The Trace Input should enter the data into the flow sorted by primarily CDP and secondarily OFFSET hereinafter we will use CDP OFFSET notation to describe this sorting For this set the routine parameters as shown on the following figure 19 Trace Input Data Sets Sort Fields COF Delete Add Delete e Selection
7. ASCII files rec_geom txt and sou_geom txt containing coordinates of the receivers and sources respectively Furthermore you can load the final project which is a result of executing all steps described in the tutorial http radexpro ru upload File tutors CDP MyProject zip Note that the facilities of the software of course are not limited to the minimal processing sequence described here We consciously did not consider more complicated tasks such as for example horizontal velocity analysis migration calculation and analysis of seismic attributes etc You can find the information about these and other procedures of data processing and analysis in the User Manual to the program Data input assigning geometry binning Creating a RadExPro Plus project All reflection data processing in the RadExPro Plus is performed within the framework of projects A project is a complex of initial data intermediate and final processing results processing flows all organized into a common database used by the software The projects are stored in separate folders on disk When a project is created the new folder for it is created automatically A project can be transferred from one computer to another by simple copying of the folder in case that all the data used are stored inside this folder Let us create a new processing project Start up the software To do this select RadExPro Plus Total 3 75 command in the Windows Start menu DECO
8. Ctrl MB2 DblClick Delete lt w Execute 1t and make sure that the result looks approximately like this My Project My Area Line 1 030 preproc Zoom Common parameters Tools Exitjatop tow Exit Wh KWYN a y U ip ii rd f i sa a W TUY 7 n b j mu i Ane WAT Nit t Y POR A 1 i 7 21 ih Y A W Sam 35 Amp 1 31 2940 0ms Tr 145 lt 37 Execution of the preprocessing flow At this point you may consider that the parameters of preliminary data processing are selected and you can execute the flow with the complete dataset To do it change the parameters of the Trace Input in such a way that now the data from all CDP points enter the flow Trace Input Data Sets Sort Fields OFFSET Delete Add Delete f Selection Select from file C Database object As the volume of data in the flow 1s rather large now we have to execute 1t frame by frame In the window of the flow editor select the Flow mode menu entry and assign the frame size so that the data of each frame were completely fit to the available RAM memory Flow Mode Flow Data Processing Mode All at once all in memory Frame Selection W Honor ensemble boundaries Frame width traces H FUL Cancel Add the module Trace Output to the end of the flow in order to save the results of the preliminary data processing In the parameter dialo
9. Delete Create a flow consisting of the modules SEG Y Input and Trace Output both are located in group Data I O This flow will read the data from a SEG Y file and record them into the project database a dataset object of the database Modules are added to the flow one by one To add a module into the flow just drag it over from the library on the right to the area of the flow on the left At this moment a parameter dialog of the module will be opened later when the module is already in the flow the same routine parameter dialog can be called up by a double click of the mouse on the module name in the flow While already in the flow the routines can be moved up and down relative to each other by simple drag and drop In Data I O group find the SEG Y Input module and add it into the flow When adding the routine assign the parameters of data reading in the opened dialog box Click the Add button and select our test data file ine_J sgy For training purposes the information about source and receiver positions in this file is stored not in the standard SEG Y trace header words but in the reserved space of the trace headers In order to read the traces header information recorded in non standard positions within the SEG Y trace headers enter a remap of the header fields For this switch on the Remap header value option and enter the following text RECNO 41 181 SOURCE 41 185 SEG Input sample Format sample interval E
10. Geophysical Re RadExPro Plus Total 3 7 fan Exact Audio Copy R TapeLoader 3 Far Manager Google Earth im Documentation k ia RadExPro Plus Wear Surface 3 7 fr IntelR Software Development Tools Tunes k When the RadExPro Plus starts the Project Manager dialog opens containing the list of registered projects F RadExPro Project Manager Registered projects Line_ 22 lam hhh A New project MS test DEMO OC nomarnne l shallow NSP 7 Select project WS 2005 EAST BlackSea_vels BlackSea seismic tasks Project directory Click the button New Project and select a parental folder on the disk where the subdirectory with the project will be created After this in the appearing window enter the new project name Mew database Title M y Project iW Create subfolder Cancel Make sure that the option Create subfolder is selected and click Ok In the selected folder the subdirectory with the project name will appear Also the project will appear in the list of available registered projects F RadExPro Project Manager Registered projects WS 2005 EAST BlackSea_vels a New project BlackSea selemic_ tasks DEMO QC nomarine Select project LandD ema BUST _2007_calibr 7 Remove from list Practicum Project directory F Prachcums hiy Project OR Cancel Select it and click OK The main window of the RadExPro program containing the proje
11. and can be perceived an array of named variables linked to the trace When creating a new project the default set of header fields generated is quite similar to the SEG Y trace header See the correspondence of the RadExPro header fields and SEG Y trace header in the description of module SEG Y Output in the User s manual However further the header fields can be edited you can add new fields remove or re name the existing ones A part of the header fields are standard and it is strongly not recommended to change their meaning for example field DT must always store the value of the sample interval Other fields can be used at your discretion In the new or existing but not used header fields different information can be recorded for example the arival time of a wave as picked on this trace You can perform mathematical operations with the values of the header fields convert them into picks etc After the SEG Y Input module add into the flow the module Trace Output which will save the data from the flow into the database Name the object which will contain these data as line 1 raw and place it at the second level of the database into the Line 1 as shown in the following Select dataset Object name line 1 raw Objects Location My Area Line 1 010 data load Rename Delete figure Besides for the control after module Trace Output add into the flow
12. case by the value of the CDP field Click the button Axis and assign the following parameters of the axes Axis Parameters Time Traces Different dy Values Interval ye Primary lines 000 W Multiple a Different Secondary lines 100 0 P OFFSET Interval 1 5 0 IW Font size i Ll Margins Left axis gt a Cancel magn IO magn 20 mm dt Values COP Multiple Execute the flow using the Run command of the menu The raw data sorted by CDP OFFSET CDP gathers will be displayed on the screen 21 F z or 4 My Project My Area Line 1 020 geometry check BAE cm g7 98 39 100 OFFSET 2437435 939285 565267 2063451 1415 306 27 073 156 431 1988375 487235 I012A01 2513 1064285 48268 1937451 10007 7p qe E po eb am ee gt mt 20004 r AT Ea ee 5 Al To control geometry assigning display the theoretical travel times of reflected wave calculated from header field values To do it use the Tools Approximate Hyperbola reflection entry of the Screen Display menu l orrae J e Interval Hsn E ct My Area Line 1 020 geometry check In parameters Tools ExiEistop Flow Exit As a Spectrum Pick 6365 1635 42 wells Line 13126 Static corrections Save parameters Apply procedure EF ir Wiribe History Amplitude editing PE Trace Header Math Reflect header changes in Reflect ident Fields Text hint Print MINA MN Save ima
13. less is the analyzed interval ce i Y 560 T 1092 SCDP 100 ILINE 100 XLINE 0 After the velocity pick for this super gather position 1s assigned it 1s possible to pass to the next position clicking the button with the right arrow on the tool bar If you carry out the velocity analysis in the framed mode you can move through the super gathers to the right or left within the current frame otherwise within the entire dataset Carry out the velocity analysis for all super gathers then before exiting the module press the Save button on the tool bar in order to save the created velocity pick Stacking Create the flow 050 stack De f RadExPro 3 75 gt gt gt My Project Help Options Database Tools Why Area 010 data load 020 geometry check MBL ObiClick Default action MBZ Context meno MBL Drag Flow to line to copy The flow must contain the following routines Trace Input which enters the line 1 preproc dataset into the flow in the CDP OFFSET sorting order Trace Input Data Sets Sort Fields Delete Add Delete e Selection Select from file C Database object IS Cancel C Get all The NMO NMI module to correct the traces for the NMO The parameters of the module should be 53 assigned as follows Select the NMO mode in the NMO tab set muting on the signal tension 30 1 e those parts of the traces which as a result of the NMO correction will be extended to more
14. of the velocity spectrum however its coherency somewhat deteriorates Interactive Velocity Analysis PS PP velocities Semblance Display Gather Display FLF Display LYS Display Super gather Input velocity Output velocity Semblance A Stark X End E Step Range CO CO Y Start oO Y End G m mwm Y Range OFF Start OFF End Off Step Off Range Dast Save template Load template OtrMeHa Select the tab Semblance to assign the parameters of the velocity spectrum calculation the start and end velocities the velocity step and the time step The velocity spectrum will be calculated as a normalized for the specified range of velocities 44 Interactive Velocity Analysis PS PP velocities Semblance Display Gather Display FLF Display LYS Display Super gather Input velocity Output velocity Semblance Start velocity 500 End velocity 5000 Velocity step 20 Time step 20 Number of CS i 1 Save template Load template Otmena The parameters by default for the considered data set are completely acceptable The remaining dialog tabs are responsible for display parameters of different elements of the velocity analysis window It 1s reasonable to keep the parameters by default on the Semblance Display tab responsible for the parameters of velocity spectrum display 45 Interactive Velocity Analysis Super gather Input velocity Output velocity Semblance PS PP veloci
15. the Screen Display module The obtained flow must appear as follows F My Project My Area Line 1 010 data load Help Options Database Tools Run Flow mode Exit SECG Y Input line l sgy Trace Output gt line 1 raw screen Display Trace input Trace Ouiput VSP Data Modeling 3D Data Output 22D Finite Difference Modeling GSST JHOPHC SES S Fag SEG Y Input Text Output Amplitude Correction DC Removal AResample FSP SDC Mave field subiracii n Ensemble Stack Deconvolution Ssurface Consistenit Deconvolution aa Data input Data Output 3D Data Input SEG D Input Super Gather RAMACYGPR Lama Solid Layer Sold modeling SECS Input SEG Output Analogic Data Input sional Processing bundpass Filtering Hilbert Transformi Trace Math Transforms Trace Math Transforms 1 Sstacking Ensembles Asymptotic CCP Dinning Deconvolution Predictive Deconvolution Cusiom impulse Trace Transforms Nonsiatoncry predictive deconvoliutian MB1 Drag module Ctrl MB1 Copy module MB1 DbiClick Module Parameters MB2 Toggle module Ctrl MB2 DblClick Delete For executing the flow select the Run menu command As a result the Screen Display window should open showing the data being entered while the data will be read from the disk file and recorded into the database The window Screen Display which should appear on the screen is shown below 10 My Project My Area Line 1 010 data loa
16. 0 U i n oe Me 4 abs sab de de Ki Wi f ii ii f i i y ME d y p ad edi IA 7 3 re e f 53 83 z itai a eel SA sate Miers Sth BF le Sra 4 re 2 ay i 34 A ST i BM 5 il l A ri la IAS ds td core ta PEA Ae er Ad at he Fe e og ee re Gr do A emt tr ua ell de id gt del do e en ur aAa gt MA RA Y SN ar A Cd lt AS dr te Su AS ALTE i ZN tl ier tel bt te it a Adar Pe da AN rr Pol PA A PD aa i a SS fw wen lt i oh Peer des eke e da Pred TA ad note wry pS cn A oe SA ee 4 musa dr e rai n y do Me ds iat Maren A Aarie rn a O Bt a tj et A SE arar AA Do OP RET Re dr o bebe dnd Mordor Se Al ee VN or a ae E a NS a wy de i ms 1 a EA a in a PA Dm oe aot A E AS ye HL de La ea ZR Be i i J 2 1 SE a a PIPAS E q gee fa te a4 i a Additionally the module Interactive Velocity Analysis allows accomplishing the following a oe dE Hoe TE actions useful for the QC of the velocity picking ri N a it eee ot aa See REE b 4 Y 2764 T 2173 SCDP 100 ILINE V 2764 T 2173 O O TLINE 100 XLINE 0 E en XLINE 0 e The button N on the tool bar switches on the mode when the current super gather is dynamically corrected for NMO with the current velocity pick At that the travel time curves of t
17. C Select from file C Database object Due to this selection of the Sort Fields the traces will be entered into the flow ordered by their CDP number Within each ensemble with identical CDP number the traces will be ordered by the OFFSET The text line specifying a trace selection mask for each of the sorting keys should be entered in the Selection field Selection parameters for each of the keys are separated by a colon In this case means that for each of the two sorting keys all available traces will be entered into the flow sorted according to the sorting key values in ascending order In the Screen Display module assign the parameters as shown on the figure below 20 Display parameters Display mode Fromt 0 0 to 2996 Tt Seale COW TT fy Co OWT Number of traces 200 M Y Scale CA nenes 9 te tional scalar p 3 o R E Bias 0 5 Custor Normalizing factor None W Ensemble boundaries Variable spacing f Entire screen E CC Individual Ensembles gap 2 HS Header mark Muliple panels Ais Plot headers Show headers iM Use excursion 2 0 traces _Plot headers Picks settings Save Template Load Template Ok Cancel If the Ensemble boundaries parameter is switched on the ensembles of traces will be separated on the screen by empty spaces The ensemble in the RadExPro is defined by the first sorting key assigned in the Trace Input that is in this
18. ES E ee E A blkwto td p al i Cul Fas pal HeaaBHe prismi pal a E rainbi pal shade pal velink pal PaboyH cron Mow ok YMeHTE Moe KOMMBIOTeD Lereboe Hra pana bikwtord pal OK pyieHHe Tan parinoe Palette files Ormena fe The result should be as shown in the following Custom Palette x Cancel The dynamic stack FLP Display and the panel of the constant velocity stacks CVS Display can be conveniently observed when the traces are displayed in wiggle trace variable area WT VA mode Therefore the parameters for them can be kept as they are set by default 48 Interactive Velocity Analysis Super gather Input velocity Output velocity Semblance FPS7 FPF velocities Semblance Display Gather Display FLF Display CYS Display Display modes r Scaling mi Normal type a i C Entire Scree Maximu E o lndiridual Mean AMS f Color Additional scalar Bias 0 Save template Load template Otmena After assigning the parameters execute the flow As a result the interactive velocity analysis window will appear It consists of 4 parts from left to right the semblance velocities spectrum the current super gather the dynamic stack and the constant velocity stack panels The dynamic stack consists of the traces obtained as a result of stacking of the CDP gathers of the current super gather corrected for NMO with with the current velocity p
19. J o ne 1 o 109 z7an 00000 2738 00000 273 00000 0 00000 fO o in 1 o o 21800000 263 0000 2703 00000 0 00000 0 o an err 00000 788 0000 2748 00000 aooo 0 MOM For calculation of the specified values use the Trace Header Math tool dedicated to mathematical operations with header field values The Trace Header Math is available from the menu Tools Header Math In the open dialog box enter the following expressions Trace Header Math cdp_s frec_x kou_s 2 offset rec_ sou_ x aottset abs ottset Cancel Load template Save template and click the OK button The numbers of the CDP gathers will be calculated on the basis of the CDP coordinate and desired size of a bin As the distance between the receivers was 25 m and the shot interval was 50 m the bin size should be selected as 12 5 m For calculation of the CDP numbers in the same Trace Header Math window enter the following expression 17 Trace Header Math cdp trunc cdp_ 12 5 Load template Save template The resulting table should look like the following line 1 raw Geometry Spreadsheet Sele Fields Edit Tools Exit tesco NN TOA A ot Fo ISO IO IRC zasson IRC unre os is isis as ms pcs e a on oo ec ea ASEO f os aro 00000 27135000 271380000 IEC wT ne 1 os 109 eras ooo 238 5000 273520000 serio 108 n 1 ss o 21800000 263 5000 270320000 10 2800
20. ace sequence number within line Integer Trace identification code Real Uphole time at source Integer CDP Cross Line Number vi gt Hold Ctrl to select several fileds Cancel Load template selection Save template selection As a result the header editor window shall look as following line 1 raw Geometry Spreadsheet Fields Edit Tools Exit O os TT Fo 1 0 00000 2 ooo KA os 100 0 00000 C a 1 es 10 0 00000 KA os 102 0 00000 C o 1 0 00000 103 e 00000 10s os 10 0 00000 106 1 0 00000 105 e 00000 As 106 0 00000 MUM Select the Tools Import menu command The dialog with the import parameters will open Open the file sou_geom txt there and define the rules of filling header fields For this add to the Matching fields list the field SOURCE for that click the appropriate Add button and select it from the list To the Assign Fields list add the SOU_X field Then specify the columns of the text file from which the indicated fields should be read They shall be set in the text lines under Set column buttons By the way if you set the cursor into the appropriate column and click Set column the number of the column will be automatically entered there Finally the range of the lines should be 14 indicated from which the program will obtain the values This shall be done in Lines field set From and To values The correct settings are shown on the figure be
21. alar application Trace equalization Basis for scaling MEAN 11700 000000 4000 000000 Time Yariant ScalingSpecify amplifying law along trace t ms A rl oa Note that the window we select here for estimation of the average amplitude of each trace contains the target reflections and does not contain trace sections before the first arrivals Time gate start time ms Time gate end time ms Example format 11 k1 1243 K2 INIEN At the present moment the flow looks as follows Pe My Project My Area Line 1 030 preproc Help Options Database Tools Run Flow mode ier a ee ee e AT Trace Input lt line 1 raw Amplitude Correction Predictive Deconvolution Bandpass Filtering Amplitude Correction screen Display MBI Drag module Ctri MB1 Copy module MB1 Dblclick Module Parameters MB2 Toggle module Ctri MB2 DblClick Delete lt hd Advanced VSP Dispaly 3D Gazer FSP Misration Curved Profile VAP Migration STOLTSD Trace Math Trace Length 2D Spatial Filterino Antenna Ringdown Removal Radial Trace Transform aC Orientation Trace Header Math 32 3D Screen Display OO Analysis Interactive Velocity Analysis Stream Plotting Migration T A Migration Stolt F K Misration Trace Editing A Interpolation Prace Editing Data Enhancement F K Filtering Radon Transforma 2D Spatial Filtering 1 3C Processing spitz art Geometry Headers Header Averaser Assigning muting parame
22. am Solid Layer Solid modeling SCS 3 Fut SiG E put SEG Y Input SEG Output Text Ouiput imal Processing Amplitude Correchion bundpass Filtering DC Removal Hilbert Transform MB1 Drag module Chrl MBi Copy module MB1 DblClick Module Parameters MBZ Toggle module Ctrl MB2 DblClick Delete Execute the flow the CDP gathers will appear on the screen Examine the gathers on the screen and try to identify the types of the observed waves Find the direct wave reflected waves surface waves Estimate the velocity of the direct wave the group velocity of the surface waves For this use the the Screen Display Line tool allowing to fit theoretical travel times of the direct wave to the data Since velocity is calculated as distance from the source divided by the arrival time first it 18 necessary to indicate the header field which will be used for calculation of the distance between the traces when calculating the apparent velocity Use the point of menu Tools Approximate Line Header word and select the field OFFSET 25 My Project My Area Line 1 030 preproc Zoom Common parameters MES Estopa Exit Spectrum Pick Walls Static corrections Apply procedure Write History Amplitude editing Text hint Print Save image 1000 Fee eS a E Trace Header Math Reflect header changes in Reflect ident Fields Hyperbola difraction Hyperbola re
23. at it 1s always possible to find two header fields that will unambiguously identify a trace for example number of CDP and offset or shot point number and channel number In this case however we want the time of the muting to be suitable for all CDP gathers and depend only on the offset Therefore we must bind the pick to only one header field OFFSET To do it select the Tools Pick Pick Headers entry of the Screen Display menu 34 My Project My Area Line 1 030 preproc Zoom Common parameters MERAT Get Stop tow Exit Approximate Spectrum Ef Pick H Mew pick N i wells Delete pick Del Static corrections d Load pick Ins Apply procedure d Load pick wiinterpolation Wribe History Collect picks Amplitude editing d Save Trace Header Math Save as Reflect header changes in Load From header Reflect ident Fields Save to header Text hint Export pick Import pick Print PATE Pick headers Save image nent Line style Label Picks Picking mode 10004 o o Er a a moe First breaks kw ike Pick mouse mode M Least squares Marks only Mext pick TAB Previous pick ShiFE T 4B Tai Ai LE I Fiat yl FFID IGAIN ILINE_NO Lat O Lon_ l MARKER NONE NUM SMP PATH PICK PICK2 PREAMP A_LIME i REC_CRL REC DATUM REC DATUM REC_ELEV REC_ELEY REC_H20D REC_H20D REC INL REC INL Then click the OK button and save the pi
24. ck with the Tools Pick Save As command of the Screen Display menu Indicate the name of the pick as top mute 35 Top muting In the flow 030 preproc return to the initial sorting CDP OFFSET changing respectively the Trace Input parameters Add the module Trace Editing to the end of the flow before the Screen Display module with the following parameters Trace Editing Muting Horizon C Bottom muting C Trace killing C Muting in windo Taper window length On the second tab specify the horizon that will define muting as a database pick top_mute which was saved at the previous stage The Horizon tab must look like this Trace Editing Muting Horizon C Trace header 3 C Specify Save template Load template OtrMeHa Now the flow looks like the following 36 Run Flow mode Interactive Velocity Analysis dis My Project My Area Line 1 030 preproc Exit dranced VAP Dispaly aired Plotina Database Tools A 3D Gazer FSP Misration P E Migration Curved Profile VSP Migration Stolt F K Misration SITOLT3D Help Options A Interpolation Trace Math Trace Editing Trace Length F K Filtering 2D Spatial Filtering Antenna Hinodown Removal Radon Pransforms Radial Trace Transform 2D Spatial Filtering 1 spitz art Header Averager SC Orientation Trace Header Math Shift Header MB1 Drag module Ctr MB1 Copy module MB1 DblClick Module Parameters MB2 Toggle module
25. ct tree will appear By now this tree is empty F RadExPro 3 7 gt gt gt My Project DEAR Help Options Database Tools Exit C MB1 DblClick Default action MB Context menu MB1 Drag Flow to line to copy Loading raw data into the project Using Windows Explorer enter the project folder lm My Project Dann Mpaera Bra WsbpeHHoe Cepeic Cnpabra Q Hasan es gt a Monck Wes Man Ei Paa aaa a 1 AApeci ma F PracticuribMye Project y Nepexoa a DB SAVE ators tbl data fbl data Fsp struct Fbl struct fsp In this folder create a subdirectory Data and copy the initial data there tain Opaska Bra bHi bpaHHoe Cepeic Cnpabka Te S Hasan T Q gt Bi a MoHce m Mankin Hak AApec ma F PracticumiMy Project Diata vl Nepexog line_1 sqy r ec_geom txt Mann Soy TekrcToBbIA JOKYMEHT 5796 KB 11 KB sou_georn txt TEeKCTOBBIA ADEYMEHT 6 KB Storing the data inside the folder of the project allows the software to use relative paths to the data files instead of the absolute ones This makes the transfer of projects from one computer to another much easier Return to the main window of the RadExPro program A RadExPro database has 3 structural levels The upper level corresponds to a study area the middle level to a line and the lower one to a processing flow Right click with the mouse on the yellow circle that 1s the root of the project tree select option Create new area in the con
26. d Zoom Common parameters Tools 20004 Tr 100 Sam 605 Amp 0 142 t 2420 0ms JA Important When the volume of the data read from the file 1s great comparable or exceeds the volume of RAM or just around 1 Gb or more it is necessary to use Framed mode which allows to read the data into the memory not as a whole but by pieces frames To turn into this mode and to determine the size of the frames use the Framed mode command available from the flows editor main menu Note about the names A name of any object of the database seismic dataset processing flow etc must reflect its essence but not consist just of several letters The name of a seismic dataset should consist of 2 parts the identifier of initial data and the processing stage of the data Thus when entering the field data the name line 1 raw was selected here Geometry assigning and binning Assigning geometry to seismic data means that for each trace a number of values are determined which then are saved in the specified header fields of the dataset in the project database The list of the necessary values and the header fields corresponding to them are given below 1 Source point also called shot point or SP number header field SOURCE 2 SP coordinate SOU_X 3 Receiver point RP number RECNO 4 RP coordinate REC X 5 Distance between the source and the receiver OFFSET and the modulus of this value AOFFSET 6 Uniq
27. e database Output sample format Aa C 12 H Cancel Select dataset Object name line 1 stack Objects Location data load geometry check preproc velocity analysis stack Rename Delete Cancel The flow looks now as shown on the following figure 55 F My Project My Area Line 1 050 stack Sele Help Options Database Tools Run Flow mode Ad Trace Input lt line 1 preproc NMO NMI die id Ap Ensemble Stack Trace Ouiput Data Output Trace Output gt line 1 stack SP Data Modeling SD Data input 3D Data Ouiput SEG D input 20D Finite Difference Modeling Super Gather EART RAMACGPR OTHE Lami Solid Layer Solid modeling SEAS Papi SEGA Input SEG Y faput SEG Oniput Text Output Data IO signal Processing Amplitude Correction Bandpass Filterino DC Removal Hilbert Transform Resample Trace Math Transforms FSP SDC Trace Math Transforms 1 Have field subiraciion Stackins Ensembles Ensemble Stack Asymptote CCP Dinning Deconvolution Deconvolution Predictive Deconvolution Suface Cansisient Deconvolution Custom Impulse Trace Fransforimns Nonstationary predictive deconvolution Interactive Tools FSP Display Sereen Display 3D View 3D Screen Display Felocity Editor OC Analysis MBL Drag module Chi MB1 Copy module MB1 DbiClick Module Parameters MBZ Toggle module Ctrl MB2 DbiClick Delete For executing this flow switch on the framed mode Set any reasonable frame width and make s
28. eal Horizon pick Real Instrument gain constant Int32 Receiver line number Integer Recelver s cross line number d Real Datum elevation at receiver group REC_ELEV Real Receiver group elevation REC_H20D Real Water depth at receiver group REC_INL Integer Receiver s inline number REC_RESID Real REC_SLOC Int32 Receiver station number within receiver line REC_STAT Real Receiver group static correction REC_STAT1 Real8 REC_STAT2 Real8 REC_STAT3 Real8 REC_UPHOLE Real Uphole time at receiver group Real receiver group coordinate Real Y receiver group coordinate Int32 Receiver station Number Int32 Source line number Int32 Super gather CDP Integer Trace sequence number within CDP ensemble Inte Stack index i Integer Source s cross line number SOU_DATUM Real Datum elevation at source SOU_ELEW Real Surface elevation at source 2 Baal O ua m fua m hgh mi lt es SOU_H20D Real Water depth at source SOU_INL Integer Source s inline number SOU_RESID Real SOU_SLOC Int32 Source station number within source line SOU_STAT Real Source static correction SOU_STAT1 Real SOU_STAT2 Real SOU_STAT3 Real8 Real x source coordinate Real Y source coordinate Int32 Source station number Int32 Int32 Number of vertically summed traces yielding this trac Real Intevactive time shifts Real Interactive time shifts Real End of mute time Real Start of mute time Real Total static applied Integer Number of horizontally stacked traced yielding this tr Integer Tr
29. flection Line header Word Save parameters a a For evaluating the apparent velocity use Tools Appoximate Line In order to fit the line to the data assign the beginning of the approximated section on the screen by left click of the mouse then the end of the section by right click The current value of the apparent velocity will be shown in the green line in the top left corner of the screen My Project My Area Line 1 030 preproc Zoom Common parameters v 1 65 OFFSET ims Tools Esat Stop Flow Exit Record the obtained values of velocities into a text file It can be made automatically For that while the Line tool is active select Tools Approximate Save parameters menu entry My Project My Area Line 1 030 preproc v 165 OFESET ins Spectrum Pick Wells Text hint Print gt ay e g Approximate Save image Zoom Common parameters ees ExitiStop How Exit Static corrections Apply procedure Write History Amplitude editing Trace Header Math Reflect header changes in Reflect ident Fields 26 w Line da t ay Hyperbola fdifraction Hyperbola reflection Line header word Save parameters J agp Additional window with an editable text field will open Copy the current velocity there by pressing Ctrl Q while the Screen Display window is in focus You can copy as many values as you like
30. g of this routine create a new dataset with the name line 1 preproc where the data from the flow will be saved to 38 Comment the Screen Display Finally the processing flow appears as follows iz My Project My Area Line 1 030 preproc Help Options Database Tools Run Flow mode Trace Input lt line 1 raw Amplitude Correction Predictive Deconvolution Bandpass Filtering Amplitude Correction Trace Editing Trace Output gt line 1 preproc eee Screen Display Trace Input Trace Output VSP Data Modeling 3D Data Output 20 Finite Difference Modeling GSSL TOLHC SCS 3 Input SEG Input Text Output Amplitude Correctian DC Removal Resample VSP SDC Mave field subtraction Ensemble Stack Data 1 0 Data Input Data Output 3D Data Input SEG D Input Super Gather RAMACYGPR Lamb Solid Layer Solid modeling SEG B Input SEG F Ouiput sional Processing Bandpass Filtering Hilbert Transform Prace Math Transforms Trace Math Transforms 1 Stacking Ensembles Asymptotic CCP Binning i ME1 Drag module Ckr MB1 Copy module MB1 DblClick Module Parameters MB2 Toggle module Ctrl MB2 DbicClick Delete Execute the flow Velocity analysis and stacking Preparation of the data for velocity analysis super gathering As arule in order to increase the signal to noise ratio and obtain more coherent velocity spectra velocity analysis is carried out on ensembles consisting of several adjacen
31. ge TIR r Use the default parameters of the travel time hyperbola 22 Hyperbola parameters t step 30 00 min 0 00 max 3000 w step 0 01 min 0 05 max 5 00 fi step 5 00 min 90 00 max 90 00 On the screen the travel time curve of a wave reflected from the boundary of a half spaces is depicted by a blue line Current parameters of the medium and the boundary are displayed in the upper left corner of the Screen Display window Using the arrows on the keyboard right left change the velocity in the medium until the approximate coincidence of the blue line and the observed first arrivals is achieved My Project My Area Line 1 020 geometry check Zoom Common parameters Tools Gx i stop flow Exit W 00ms v 1900 mms fi 00 oe Cte Biker LEA FI Fe lt gt 24 a Y E oi J n e J s gt If it is possible to attain good matching of the observed direct wave by the theoretical travel times for all CDP gathers then the distances between the SP and the RP were calculated correctly If the matching cannot be attained for example the observed travel times appear to be shifted relative to the theoretical positions this indicates an error in the geometry of the traces Then assign the geometry again or find and correct the error some other way 23 Data analysis and trace by trace processing Sorting traces by CDP and analysis of the wave field ure Help Options Database Too
32. ger volume of data the phases of the reflected waves are outlined much more confidently than on single CDP gathers 41 Velocity analysis Comment the Screen Display module or remove it from the flow For conducting the velocity analysis add the Interactive Velocity Analysis routine to the end of the flow Let us discuss the assigning order and the reasonable values of the parameters of the module First it is necessary to specify where to save the resulting velocity pick The output velocity field can be stored either in a text file or in a database velocity pick object We recommend that the output velocities are always saved as a database object Then all possible manipulations with them such as export import can be made using the with the special tool Database Manager available from the Database Database Manager menu of the RadExPro main window Therefore in the module parameter dialog select the Output Velocity tab and make sure that the option Database picks is selected Interactive Velocity Analysis PS PP velocities Semblance Display Gather Display FLF Display LYS Display Super gather Input velocity Output velocity Semblance a AA Use file Browse Database picks vell Dene Velocity domain Velocity type a i f AMS C Interval Save template Load template OF OTtmena Click the Browse button corresponding to this option and in the appeared dialog box specify the
33. h super gather will contain10 adjacent individual CDP gathers The super gathers are formed of the preprocessed dataset line 1 preproc prepared at the previous stage If you add the module Screen Display into the flow after the Super Gather you will be able to see how the resulting super gathers look like 40 F My Project My Area Line 1 040 velocity analysis Iliaj Help Options Database Tools Run Flow mode ae A A ALAS F LLT Ad e LEPE se a Pa Resample Trace Math Transforms J FSP SDC Trace Math Transforms 1 Have field subtraction Ensemble Siack Asymptotic CCP Binning Deconvolution Predictive Deconvolution Ssuiface Consistent Deconvolution Custom impulse Trace Fransforms Nonsiatonary predictive deconvolution FSP Display Sereen Display 3D View 3D Screen Display Velocity Editor OC Analysis Advanced VSP Dispaly Interactive Velocity Analysis 3D Gazer Stream Plotting FSP Migration I A Misration Curved Profile VSP Misration Stott F K Migration MEL Drag module Chri MB1 Copy module MB1 DblClick Module Parameters MB2 Toggle module Ctri MmMB2 Dblclick Delete The following figure shows the result of executing such a flow o S My Project My Area Line 1 040 velocity analysis Ej a led Zoom Common parameters Tools Exit Stop flow Exit Hi A PARE Se Pe y nad ea Nt Tr 1099 Sam 171 Amp 0 t 684 0ms ey Al Te lt e xi It 1s easy to see that due to the use of a substantially lar
34. he reflections ideally must become rectified see the figure below 51 EM Interactive Velocity Analysis SCDP 100 ILINE 100 XLINE 0 Fie velocity Field NMO Help lt gt N wl als f al xl CYS m s M H M LI 1 mn f ha E E as a a ALCA A eg cy A a Ca IN CA Y Eey Q Pa et ahora ie eS a a aii rete eve ee a D kar 2 ae FA e PR ere Y KE A a gt et shi a o ti e r AN E rs A er rs tt ee ee E A parte RA NS Ping tg gg de PA A et Sry he at Shove 7 eT pee Y i b RS E VAA A AAA ASOT Aarie Fe ie Pet ee es ER E e A bd i Ln A y A Mn NA A ii a ee A ra a ee 2032 a a ma a y AA na a aa Area did bal Las ES LP ah Ser aah ATAN rr amt OS ee BSS vn ee de ME a o OS A eee r N 8 A i e Clicking the Dix button of the tool bar you may display the interval velocities calculated for the current velocity pick according to the Dix s formula light blue blocked curve on the figure By the way switching this option on and changing insignificantly the stacking velocity barely moving one of the points of the velocity pick you can see how extremely unstable is the conversion of the RMS velocities that is what we actually pick into the interval velocities You can see that even the slightest changes in the stacking velocity can lead to sometimes catastrophic changes in the interval velocities This effect is the greater the
35. ick When the velocity pick changes the stack is dynamically recalculated The constant velocity panels show a series of stacked traces for a series of constant velocities Each stack fragment here 1s obtained from the CDP gathers of the current super gather corrected for NMO with one or another constant velocity 49 BM Interactive Velocity Analysis SCDP 100 ILINE 100 XLINE 0 File velocity Field NMO Help gt N Bl alz l 2 x Velocity m s Offset m 2500 50 00 0 CYS m s 1000 2000 3000 4000 50 Te 4 1 i AL A Amer da i Fr a erri Eee ds Pr rd A e AS ADS he D AL s AAA A DATEN rt Ea ie i te eter at rae Pe O Bae Ra A ed th ee ae le MALAS a bh de td ar tr 3 Ron A Ma A ie aS Ge fa a PR AS ur yaa i AAA i Apt ad a tert tele a N gt SA MA A E Me de EA E Peau TE Par et my Cc BN Velocity pick is made on the semblance panel When picking follow the maximums of the energy of the semblance An example of a reasonable velocity pick for the above figure 1s shown below Ce ee v a 4 Y 1755 T 334 SCDP 100 ILINE Mm i755 T 334 SCOP 100 TUINE 100 XUINE 0 k XLINE 0 50 BM Interactive Velocity Analysis SCDP 100 ILINE 100 XLINE 0 File Velocity Field NMO Help lt el N al als fi al x Velocity m s 2500 50 00 0 CYS m s 1000 2000 300
36. le as shown on the figure below De Amplitude Correction Action to apply Spherical divergence correction 1s Exponential correction dB s Automatical Gain Control Trace equalization Time Variant Scaling OF Cancel Compare the appearance of the data before and after the spherical divergence correction For this run the flow two times with the active and commented Amplitude Correction module to comment the module right click it with the mouse As a result two Screen Display windows appear on the screen one of which contains corrected data the other one initial data Spectrum spreading After the correction for spherical divergence add the module Predictive Deconvolution to the flow When the purpose of the predictive deconvolution 1s spectrum spreading it is reasonable to set prediction gap equal to one sample to select the filter length close to the length of the wavelet and to assign the window for the calculation of the deconvolution operator in such a way that it contains the target reflections Basing on these considerations some initial parameters can be assigned as follows 28 Predictive Deconvolution White noise level 0 010 Experiment with different parameters research how the level of white noise influences the result The following two figures demonstrate the data before and after the use of predicting deconvolution Before the deconvolution My Pr
37. low MM import Headers Matching Fields Set column Multiplier 1 2 26 Column 2 4 2 3 y 5 T A o 18 11 12 13 14 15 16 17 18 Ok Cancel Assign helde Multiplier y SOU_X 12 38 88 137 187 237 288 338 387 437 487 537 587 637 687 737 787 837 58668 53928 54920 54919 54919 54919 54919 54919 55942 56948 57941 57941 53942 53942 59943 59943 60938 61938 Text table type Delimited C Fixed width wt Load template Save template File When importing the values of the header fields from the text file the program works as follows For each line of the text file all the matching fields as well as the assign fields are read from the specified columns In the specified seismic dataset all the traces with the values of the matching header fields being precisely equal to the values from the read line are determined Then the values from the read line are entered into the assign fields of these traces Important Among other things this means that the matching fields are better to be integer this fact shall be taken into account when the files with the geometry are formed Click the OK button to assign the header fields The result is shown below 15 line 1 raw Geometry Spreadsheet Fields Edit Tools Exit O TT P10 1 1250000 ARA 0 00000 ior tn 50000 0 00000 As _101 0 00000 o
38. ls Mails Sa TRASH MEI DblClick Default action MBZ Context menu MB1 Drag Flow to line to copy Put the Trace Input and Screen Display routines into the 030 preproc flow Enter the following parameters in the Trace Input dialog Trace Input Data Sets Sort Fields OFFSET Delete Add Delete le Selection Select from file C Database object Cancel C Get all The 0 10000 10 as a sorting rule means the following e From all CDP gathers which fall into the range of 0 10000 but these are all CDP gathers in 24 the dataset only those with the numbers divisible by 10 will be taken e Within the CDP ensembles the traces will be sorted by the values of OFFSET in ascending order This sorting is necessary now to decrease the amount of data in 10 times on the stage of testing of the processing parameters Because of this sorting it will be possible to control the result of the processing not on a single ensemble but on a number of CDP gathers evenly selected along the line Assign the parameters of the Screen Display to have some 3 5 gathers on the screen The flow will look as follows in My Project My Area Line 1 030 preproc Seles Help Options Database Tools Run Flow mode Trace Input line 1 raw Screen Display Trace Input Data input Trace Ouiput Data Ouiput VSP Data Modeling 3D Data Input 3D Data Output SEG fant 20 Finite Difference Modeling Super Gather RAMACYGPR L
39. oject My Area Line 1 030 preproc BAR Zoom Common parameters Tools Print spectrum Eit atop flow Exit Help A Tr 199 Sam 144 Amp 4 44e 003 t 576 0ms ma Hl Y ee gt 29 After the deconvolution aca My Project My Area Line 1 030 preproc Exit Stop flow Exit Zoom Common parameters Tools Print spectrum De A tk i Wi FEROA N MI M i ji t fil i N AA YH W ji thi PUM N i i y Yi y 1 sty Tht AY ni eu a z ANTAS Yi iu AN ON mi e Y gt Tr 104 Sam 749 Amp 20 8 t 2996 0ms RA HI E A Mponrpesareno Windows Medial A Windows Media gt Bandpass filtering Bandpass filtering is to be used after the deconvolution aimed to decrease the level of low frequency and high frequency noise and to shape the spectrum of the trace to achieve a simple wavelet Add the module Bandpass Filtering into the flow after the deconvolution routine In the parameters of the module select Ormsby s filter with the following parameters 5 10 40 80 Hz Several CDP gathers after the bandpass filtering with these parameters are shown on the following figure 30 My Project My Area Line 1 030 preproc Zoom Common parameters Tools Print spectrum t atop flow Exit Mi SUE aa y att i e A ad E iH i l s AAA IE Terese ee eee ee ee a i M m NAVIN Wy At
40. on the flow name to enter the flow editing mode The window of the flow editor will open On the left side of the window is the flow itself it is empty so far on the right side is the library of available processing routines modules divided into groups Pe My Project My 4rea Line 1 010 data load f z joj x Help Options Database Tools Run Flow mode Exit Data I O Trace input Data Input Trace Ouniput Data Ouipiut SEG D Input super Gather Lamb Solid Layer Solid modeling SCA amp 3 Input SEG E input SEG Y input SEG Y Ouiput Text Output signal Processing Amplitude Correction Bandpass Filtering DC Removal Hilbert Transform HRescinple Trace Math Transforms Trace Math Transforms 1 Have field subtraction Sstacking Ensembles Ensemble Stack Asymptotic CCP Binning Deconvolution Deconvolution Predictive Deconvolution Ssuface Consistent Deconvolution Custom impulse Trace Transforma Nonstationary predictive deconvolution Trace Editing Trace Math X Interpolation Trace Length Trace Editing Data Enhancement D Spatial Filtering F K Filtering Radon Transforms Radial Trace Transform 2D Spatial Filtering 1 Migration T K Misration STOLTSD Stott FAA Misration Interactive Tools Sereen Display Velocity Editor OC Analysis Interactive Velocity Analysis 3D Gazer Siream Plotina Radar Screen C onmaohw H ondore MB1 Drag module Chri MB1 Copy module MB1 BblClick Module Parameters MB2 Toggle module Chrl MBe Dblclick
41. s As Jae 0 00000 As 103 0 00000 os o 104 0 00000 oso as ooo As 106 0 00000 MOM Import the coordinates of the receiver points from the rec_ geom txt file in the same way line 1 raw Geometry Spreadsheet Fields Edit Tools Exit O tase NA F100 1 1250000 ETT As 100 25000000 As a 252 0000 o As o 250 0000 os o 2 00000 ios As _104 26000000 As as 262 00000 A os 106 sos MOM Calculation of the distances between the shot and receiver points coordinates of CDP points binning Using the Fields Add fields menu entry add to the spreadsheet the following fields OFFSET source receiver distance AOFFSET the absolute value of the offset CDP_X coordinate of the CDP CDP CDP point number 16 line 1 raw Geometry Spreadsheet Fields Edit Tools Exit A os f anono 203 0000 TT o Fo IO AO IRC 28 0000 2arn 00000 aooo JO o ier 1 ss 100 2x01 00000 212 0000 21200000 0 00000 fO o ie iro aor ara a0000 AO 2x57 00000 00000 J o o 1 so 102 asen ooo 252 0000 2e0z 00000 0 0000 JO o A ss 103 sere a0000 ase7 00000 2e07 00000 0 00000 0 os o 104 20000000 2612 00000 2012 00000 000000 JO o os 1250000 10s 20200000 2 00000 203 0000 0 00000 fO o Ki o 06 2a 00000 266 0000 2003 00000 000000 J o ies so 107 20re a0000 28 0000 zot 00000 0 00000 fO o ie ION STO AO ISC 271 0000 2713 00000 ooo
42. t CDP gathers the so called super gathers rather than on separate single CDP gathers Another peculiarity of the data preparation to the velocity analysis 1s that the data must possess maximum signal to noise ratio while the high vertical resolution of the record and the recovery of the dynamics are not important Therefore when preparing the data to the velocity analysis such procedures as automatic gain control in a relatively short window and bandpass filtering in a relatively narrow band aimed to keep only the part of the spectrum with the the maximum signal to noise ratio are often used Create the flow 040 velocity analysis 39 f RadExPro 3 75 gt gt gt My Project Help Options Database Tools My Area 010 data load O20 geometry check 040 velocity analysis MB1 ObliClick Default action MBZ Context meno MB61 Drag Flow to line to copy Place the Super Gather routine which will form the super gathers in the beginning of the flow It 1s reasonable to select the Super Gather parameters approximately as shown on the following figure Super gather 4 Stark A End 100000 so 4 Range IS 3D Gathe Y Start m Y End m m 7 Step Y Step Y Range Binoffeete Off Start Off End Off Step Off Range m _ Dataset fine 1 preprog Save template Load template TrenHa That is the velocity analysis will be carried out with an interval of 50 CDP points eac
43. ters Since our processing is aimed to obtain a seismic section of reflected waves in this case direct wave 1s obviously shall be considered as noise The most effective method of suppression of this noise is the top muting from the beginning of the trace to the time equal to the direct wave arrival time plus some time after 1t containing the wavelet of the direct wave In order to assign this muting re sort the traces in the module Trace Input temporarily in the order OFFSET CDP To do it change the parameters of the module Trace Input as follows Trace Input Data Sets Sort Fields Delete Add Delete le Selection 04000010 t Select from file C Database object C Get all Execute the flow the traces sorted out in ascending order of the OFFSET header field will be shown on the screen Such a gather called common offset gather allows convenient assigning the muting time which will be suitable for all CDP gathers To do it create a new pick object Tools Pick New Pick menu command of the Screen Display then pick the time of muting approximately as shown on the figure direct wave arrival time plus 100 200 ms 33 My Project My Area Line 1 030 preproc Zoom Common parameters Tools ExitjStop flow Exit Help C E 10004 All Tr 2386 Sam 250 Amp 0 00706 t 1000 0ms A pick in the RadExPro is the collection of the time values matched by two header fields as it is considered th
44. text file For manipulations with trace header field values including import of the values from ASCII tables in the RadExPro software the Geometry Spreadsheet tool is used My Project My Area Line 1 010 data load In Options Peewee Tools Run Flow mode Exit a Y Inpu SP SDC ace Outpy 727 Have field subtraction reen Disp Add data File Geometry E A EE mhle Siek Database visualization Database manager p Decanvalition Dataset history l i f parface Consistent Deconvolution Vansiationary predictive dzconvottui Database management VSP Display 3D View Velocity Editor Advanced VSP Dispaly Select the Database Geometry Spreadsheet entry in the menu Then in the opened dialog select the seismic dataset geometry of which is to be edited 12 Choose dataset Object name line 1 raw Objects Location My Area Line 1 O10 data load Rename Delete History Cancel The following figure shows the Geometry Spreadsheet window line 1 raw Geometry Spreadsheet Fields Edit Tools Exit In order to display the required header fields all header fields declared in the database already exist but are not displayed use the Fields Add fields option of the menu In the opened dialog box keeping the Ctrl key pressed select the following header fields SOURCE SOU_X RECNO REC X 13 Add header fields to view Name Type Description R
45. text menu and enter a name of the area where the field work was conducted Help Options Database Tools Exit Jal The following figure shows the window where the name of the area should be entered Hew area name hiy Areal f RadExPro 3 7 gt gt gt My Project Help Options Database Tools Exit VIEW map Create line Rename Delete Similarly right click with the mouse on the yellow rectangle with the name of the area select Create line command and create a new line The name of the line is assigned the same way Mew line name The database allows storage of several areas within one project Each area may contain several lines each line may contain several processing flows that are applied to the data of this line The same way you created the area and the line create a processing flow and name it 0 0 data load It is recommended to that you start the name of each flow with a number The process of seismic data processing has several stages carried out consecutively Since the RadExPro Plus program sorts the structural elements of the database alphabetically it is reasonable to number the flows so that they would be displayed in an accurate logical sequence F lt RadExPro 3 7 gt gt gt My Project Sele Help Options Database Tools Exit 010 data load MB DblClick Default action MBZ Context menu MBL Drag Flow to line to copy Double click the left mouse button
46. than 30 will be reset to zero NMOSNMI NMO Velocity NMO Mute percent 30 Use coordinate interpolation Save template Load template tmena In the Velocity tab select the velocity pick which was obtained as a result of the velocity analysis performed before NMO NMI NMO Velocity C Single velocity function f Use file Browse f Database picks vel Browse a Browse Velocity domain Velocity type a ES f AMS Interval Save template Load template OTMeHa After the NMO NMI module in the flow place the Ensemble Stack routine This module stacks horizontally all the traces within each ensemble in the flow Since in this case in the Trace Input at the beginning of the flow the CDP header field was selected as the first sorting key the CDP gathers will be considered as ensembles 54 Assign the parameters of the Ensemble Stack module as shown on the following figure Ensemble Stack Mode f Mear Of Median E Aloha trimmed ad C Coherent stack 30 E Window traces Filter length me 60 i Treat zero as result of muting Cancel Finally the Trace Output module should be the last one in the flow 1t will save the results to the line 1 stack dataset which is also reasonable to be created at the second structural level of the database Trace Output File lne 1 stack bly AreaslLine Thine 1 stack W Store headers outsid
47. ties Semblance Display Gather Display FLP Display CW S Display Display modes r Scaling COTA C None a i O WT f Entire Scree Maxinun Individual Mean AMS Additional scalar Normal type i 0 Palette Blas Save template Load template OtrMeHa It is reasonable to display the traces of the current super gather for which the velocity analysis is performed in color Select any palette in which the traces before and after the normal move out NMO corrections will be conveniently observed by default the gray scale pallet is selected here we are going to replace it by the black white orange pallet For this first select the Color option of the Display mode in the tab Gather 46 Interactive Velocity Analysis Super gather Input velocity Output velocity Semblance PS PP velocities Semblance Display Gather Display FLP Display CW S Display Display mode r Scaling IWT AA mi Normal type CWT C Entire Scree y Maxinun eon Individual Mean C RMS Additional scalar f Bias fo Save template Load template OF Otmena Then click the Palette button and in the appeared dialog box click on the Load palette button Custom Palette Cancel Load palette Save palette A set of the predefined palettes is stored in the folder where the RadExPro package 1s installed in PALETTES subdirectory Select the palette blkwtord pal 47 OTK pPbITb Manka O PALETT
48. ue field record number FFID 7 Channel number CHAN 11 Note The list given above corresponds to one dimensional geometry Generally speaking the header fields SOU X SOU Y and REC X REC Y can be used for describing the coordinates of SP and PP However as the observations in the training file were carried out along one line only it is proposed to use only one coordinate X X axis 1s directed along the profile While the FFID CHAN SOURCE and RECNO header fields were filled when reading the data from the initial SEG Y file the coordinates of SP and RP should be imported from the test files and the distances between SP and RP should be calculated In practice absolutely any combination of the filled trace headers can be met For example the data can be transmitted into processing with empty headers In this case they should be formed with the use of tools available in the processing software package The situation in which the initial seismic data contain the numbers of field records and channels while the connection between the field record numbers and SPs as well as between the channel numbers for each shot and the RPs is to be calculated is rather widespread However for simplification of geometry assigning for training purposes the data already contain the numbers of pickets shot points and receiver points and only the coordinates are to be imported Import of coordinates of source and receiver points from a
49. ure that the Honor ensemble boundaries option is on This will ensure that each frame is completed until the last trace of the last ensemble in the frame Flow Data Processing Mode All at once all in memory Frame Selection 4 Honor ensemble boundaries Frame width traces i FOL Cancel Execute the flow 56 Display of the stack Create the flow 060 view stack f RadExPro 3 75 gt gt gt My Project Help Options Database Tools Exit My Area 010 data load 020 geometry check The flow should consist of the modules Trace Input and Screen Display The Trace Input should read the obtained stack line 1 stack sorted by CDPs The result should look approximately as shown on the following figure 57 My Project My Area Line 1 060 view stack Zoom Common parameters Tools Get Stop flow Exit ee ee ee nes ee a a AN See a ode oe Teo Sam 99 Ampiz64 t 396 0ms 58
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