En Tutorcdp

7/26/2019 En Tutorcdp

1/58

Tutorial on Seismic Reflection CDPData Processingin the RadExPro Plussoftware

(Edition of 21.11.2007.)

DECO Geophysical, OOOMoscow State University Science Park,

Leninskiye gory 177,11!!!2 Moscow, "#ssia

$e%.&'a (*7 +!) !-0 !+ 1+Eai% s#//ortrade/ro.co

nternetwww.rade/ro.r#
mailto:[email protected]://www.radexpro.ru/http://www.radexpro.ru/mailto:[email protected]:[email protected]://www.radexpro.ru/http://www.radexpro.ru/http://www.radexpro.ru/mailto:[email protected]


2/58

Content

INTRODUCTION.....................................................................................................................................................................3Data input, assigning geometry, binning ....................................................................................................................3

Creating a RadExPro Plus project ............................................................................................................................3

Loading raw data into the project ................................................................................................................. ........ .....

!eometry assigning and binning .......................................................................................................................... ....""Import of coordinates of source and receiver points from a text file ......................................................................... ..... ..... ..12Calculation of the distances et!een the shot and receiver points" coordinates of CD# points" innin$ .................... ..... ..... .1%

#orting the data by CDP and control o$ the assigned geometry .............................................................................."%

D&T&&N&'()I)&NDTR&C*+(TR&C*#ROC*))IN,...................................................................................................................2-#orting traces by CDP and analysis o$ the wa&e $ield ..............................................................................................'(

Correction $or amplitude attenuation .................................................................................................................. .....')

#pectrum spreading ...................................................................................................................................... ........ ....'%*andpass $iltering .....................................................................................................................................................3+

race amplitude e-ualiation .................................................................................................................... ......... ......3"

/ssigning muting parameters .......................................................................................................................... ........ .33

op muting ..................................................................................................................................................... ......... ..30

Execution o$ the preprocessing $low ................................................................................................................... ......3%

*'OCIT(&N&'()I)&ND)T&C/IN,.......................................................................................................................................30

Preparation o$ the data $or &elocity analysis, super1gathering ................................................................................32

elocity analysis ...................................................................................................................................... ........ .........('

#tac4ing .................................................................................................................................................... ......... .......'

Display o$ the stac4 ...................................................................................................................................................)


3/58

Introduction

This tutorial is intended for the users" !ho e$in to process seismic reflection CD# data in the

RadExPro Pluspro$ram. &ll standard sta$es of asic CD# processin$ are discussed" from the

introduction of $eometr to stacin$" that is the socalled minimal processin$ se4uence. It is

assumed that the user is alread familiar !ith the theor of the CD# reflection method and !ith the

fundamental technolo$ of processin$ such data.

The processin$ is conducted on an example of the real data" !hich can e do!nloaded from our

5esite6http677radexpro.ru7upload7file7tutors7CD#7inpdata.8ip

The archive contains initial data for the !or6 a fra$ment of an onshore seismic profile" recorded in

)*,( format 9file line5".sgy:" !ith the trace headers containin$ source point and receiver point

numers" and t!o &)CII files" rec5geom.txt andsou5geom.txt" containin$ coordinates of the

receivers and sources" respectivel.

;urthermore" ou can load the final pro


4/58

5hen the RadExPro Plus starts" the Project Managerdialo$ opens" containin$ the list of

re$istered pro


5/58

)elect it and clic Ok.

The main !indo! of the RadExPropro$ram" containin$ the pro


6/58

In this folder" create a sudirector ata and cop the initial data there.

)torin$ the data inside the folder of the pro


7/58

)imilarl" ri$htclic !ith the mouse on the ello! rectan$le !ith the name of the area" select

Create l!necommand and create a ne! line. The name of the line is assi$ned the same !a.

The dataase allo!s stora$e of several areas !ithin one pro


8/58

Create a flo!" consistin$ of the modules "E#$% &n'utand Trace Out'ut9oth are located in

$roup ata &(O:. This flo! !ill read the data from a )*,( file and record them into the prodataset>o


9/58

Remap of header fields.)ome seismic data formats allo! trace header remappin$" that is stora$e in

the trace headers of some values" not provided the standard. )ometimes the values are recorded

in a nonstandard format of numer representation or in a nonstandard position !ithin the header.

&s a rule" contemporar soft!are paca$es provide a possiilit to indicate explicitl from !hat

te from the e$innin$ of a header and in !hat format to read the values saved this !a. In thetrainin$ file line5".sgy" the header fields containin$ the numer 9picet: of source and receiver

position are recorded as inte$er -te numers in tes 1A11A- and 1A?1AA are saved this !a.

The remap strin$ sho!n aove !ill allo! for readin$ them from there and savin$ into the R*CNO

and )OURC* header fields of the Rad*x#ro #lus dataase.

RadExPro header fields. The Rad*x#ro soft!are uses its o!n set of header fields for storin$

auxiliar information aout seismic traces. The values of header fields are associated !ith the trace

and can e perceived an arra of named variales lined to the trace.

5hen creatin$ a ne! pro


10/58

&fter the "E#$% &n'ut module" add into the flo! the module Trace Out'ut" !hich !ill save the

data from the flo! into the dataase. Name the o


11/58

Important!:5hen the volume of the data read from the file is $reat 9comparale or exceeds the

volume of R&= or


12/58

Note. The list $iven aove corresponds to onedimensional $eometr. ,enerall speain$" the

header fields )OUJ" )OU( and R*CJ" R*C( can e used for descriin$ the coordinates of

)# and ##. o!ever" as the oservations in the trainin$ file !ere carried out alon$ one line onl" it

is proposed to use onl one coordinate J" J axis is directed alon$ the profile.

5hile the ;;ID" C&N" )OURC* and R*CNO header fields !ere filled !hen readin$ the data

from the initial )*, ( file" the coordinates of )# and R# should e imported from the test files"and the distances et!een )# and R# should e calculated.

In practice" asolutel an comination of the filled trace headers can e met. ;or example" the data

can e transmitted into processin$ !ith empt headers. In this case the should e formed !ith the

use of tools" availale in the processin$ soft!are paca$e.

The situation" in !hich the initial seismic data contain the numers of field records and channels"

!hile the connection et!een the field record numers and )#s" as !ell as et!een the channel

numers for each shot and the R#s is to e calculated is rather !idespread. o!ever" for

simplification of $eometr assi$nin$ for trainin$ purposes" the data alread contain the numers of

picets shot points and receiver points" and onl the coordinates are to e imported..

Import of coordinates of source and receiver points from a text file

;or manipulations !ith trace header field values" includin$ import of the values from &)CII tales"

in the RadExProsoft!are the #eo*etr- "'reads+eettool is used.

)elect the atabase(#eo*etr- "'reads+eet... entr in the menu.

Then" in the opened dialo$" select the seismic dataset" $eometr of !hich is to e edited.

12


13/58

The follo!in$ fi$ure sho!s the #eo*etr- "'reads+eet!indo!.

In order to displa the re4uired header fields 9all header fields declared in the dataase alread

exist" ut are not displaed: use the !elds()dd f!elds... option of the menu In the opened dialo$

ox" eepin$ the Ctrl e pressed" select the follo!in$ header fields6 )OURC*" )OUJ" R*CNO"

R*CJ

13


14/58

&s a result the header editor !indo! shall loo as follo!in$6

)elect the Tools(&*'ortmenu command. The dialo$ !ith the import parameters !ill open. Open

the filesou5geom.txt there and define the rules of fillin$ header fields. ;or this add to the Matc+!ng

f!elds listthe field )OURC* 9for that" clic the appropriate )ddutton and select it from the list:.

To the )ss!gn !eldslist add the )OUJ field . Then specif the columns of the text file from

!hich the indicated fields should e read. The shall e set in the text lines under "et colu*n

uttons. 9+ the !a" if ou set the cursor into the appropriate column and clic "et colu*n" the

numer of the column !ill e automaticall entered there:. ;inall" the ran$e of the lines should e

1-


15/58

indicated" from !hich the pro$ram !ill otain the values. This shall e done in /!nesfield6 set

ro*and Tovalues. The correct settin$s are sho!n on the fi$ure elo!.

5hen importin$ the values of the header fields from the text file" the pro$ram !ors as follo!s. ;or

each line of the text file" all the matchin$ fields as !ell as the assi$n fields are read from the

specified columns. In the specified seismic dataset all the traces !ith the values of the matchin$header fields ein$precisely e4ual to the values from the read line are determined. Then" the values

from the read line are entered into the assi$n fields of these traces.

Important!:&mon$ other thin$s" this means that the matchin$ fields are etter to e inte$er 9this

fact shall e taen into account !hen the files !ith the $eometr are formed:.

Clic the O0utton to assi$n the header fields. The result is sho!n elo!.

1?


16/58

Import the coordinates of the receiver points from the rec5.geom.txt file in the same !a.

Calculation of the distances between the shot and receiver points, coordinates ofCDP points, binnin

Usin$ the !elds()dd f!eldsmenu entr add to the spreadsheet the follo!in$ fields6 O;;)*T

9source receiver distance:" &O;;)*T 9the asolute value of the offset:" CD#J 9coordinate of the

CD#:" CD# 9CD# point numer:.

1%


17/58

;or calculation of the specified values use the Trace 1eader Mat+tool" dedicated to mathematical

operations !ith header field values. The Trace 1eader Mat+ is availale from the menu

Tools(1eader Mat+.

In the open dialo$ ox enter the follo!in$ expressions6

and clic the O0utton.

The numers of the CD# $athers !ill e calculated" on the asis of the CD# coordinate and desiredsi8e of a in. &s the distance et!een the receivers !as K2? m" and the shot interval !as K?G m" the

in si8e should e selected as 12.? m. ;or calculation of the CD# numers" in the same Trace

1eader Mat+ !indo!enter the follo!in$ expression6

1@


18/58

The resultin$ tale should loo lie the follo!in$6

To save the chan$es in the dataase on exit from the#eo*etr- "'reads+eetselect %es" or use the

Ed!t("a,e c+anges menu option.

Sorting the data by CDP and control of the assigned geometry

To verif the correctness of $eometr assi$ned" mae the follo!in$.

Create a ne! flo!" name it +'+ 1 geometry chec4

1A


19/58

Construct a processin$ flo!" consistin$ of the Trace &n'utand "creen !s'la- modules.

The Trace &n'utshould enter the data into the flo! sorted " primaril" CD# and" secondaril"

O;;)*T 9hereinafter" !e !ill use CD#6O;;)*T notation to descrie this sortin$:. ;or this" set the

routine parameters as sho!n on the follo!in$ fi$ure.

10


20/58

Due to this selection of the "ort !elds" the traces !ill e entered into the flo! ordered their

CD# numer. 5ithin each ensemle !ith identical CD# numer" the traces !ill e ordered the

O;;)*T.

The text line specifin$ a trace selection mas for each of the sortin$ es should e entered in the

"elect!on field. )election parameters for each of the es are separated a colon. In this case" L6Lmeans that for each of the t!o sortin$ es" all availale traces !ill e entered into the flo! sorted

accordin$ to the sortin$ e values in ascendin$ order.

In the "creen !s'la- module assi$n the parameters as sho!n on the fi$ure elo!.

2G


21/58

If the Ense*ble boundar!esparameter is s!itched on" the ensemles of traces !ill e separated on

the screen empt spaces. The ensemle in the RadExProis defined the first sortin$ e

assi$ned in the Trace &n'ut" that is" in this case" the value of the CD# field.

Clic the utton )x!s...and assi$n the follo!in$ parameters of the axes6

*xecute the flo! usin$ the Run command of the menu. The ra! data sorted CD#6O;;)*T

9CD# $athers: !ill e displaed on the screen.

21


22/58

To control $eometr assi$nin$ displa the theoretical travel times of reflected !ave calculated from

header field values. To do it use the Tools()''rox!*ate(1-'erbola 2reflect!onentr of the

"creen !s'la-menu.

Use the default parameters of the traveltime hperola6

22


23/58

On the screen the travel time curve of a !ave reflected from the oundar of a halfspaces is

depicted a lue line. Current parameters of the medium and the oundar are displaed in the

upper left corner of the "creen !s'la- !indo!.

Usin$ the arro!s on the eoard 9ri$ht7left: chan$e the velocit in the medium" until the

approximate coincidence of the lue line and the oserved first arrivals is achieved.

If it is possile to attain $ood matchin$ of the oserved direct !ave the theoretical travel timesfor all CD# $athers" then the distances et!een the )# and the R# !ere calculated correctl.

If the matchin$ cannot e attained 9for example" the oserved travel times appear to e shifted

relative to the theoretical positions:" this indicates an error in the $eometr of the traces. Then

assi$n the $eometr a$ain or find and correct the error some other !a.

23


24/58

Data analysis and trace by trace processing

Sorting traces by CDP and analysis of the wa#e field

To preprocess the seismic data" create a ne! flo! in the RadExPropro?as a sortin$ rule means the follo!in$6

;rom all CD# $athers" !hich fall into the ran$e of G1GGGG 9ut these are all CD# $athers in

2-


25/58

the dataset:" onl those !ith the numers divisile 1G" !ill e taenM

5ithin the CD# ensemles" the traces !ill e sorted the values of O;;)*T in ascendin$

order.

This sortin$ is necessar no! to decrease the amount of data 9in 1G times: on the sta$e of testin$ of

the processin$ parameters. +ecause of this sortin$ it !ill e possile to control the result of the

processin$ not on a sin$le ensemle ut on a numer of CD# $athers evenl selected alon$ the line.

&ssi$n the parameters of the "creen !s'la-to have some 3? $athers on the screen. The flo! !ill

loo as follo!s6

*xecute the flo!" the CD# $athers !ill appear on the screen.

*xamine the $athers on the screen and tr to identif the tpes of the oserved !aves. ;ind the

direct !ave" reflected !aves" surface !aves.

*stimate the velocit of the direct !ave" the $roup velocit of the surface !aves. ;or this" use the

the "creen !s'la-E'ineFtool allo!in$ to fit theoretical travel times of the direct !ave to the data.

)ince velocit is calculated as distance from the source divided the arrival time" first it is

necessar to indicate the header field" !hich !ill e used for calculation of the distance et!een the

traces !hen calculatin$ the apparent velocit. Use the point of menu Tools()''rox!*ate(/!ne

1eader word...and select the field O;;)*T.

2?


26/58

;or evaluatin$ the apparent velocit use Tools()''ox!*ate(/!ne. In order to fit the line to the data

assi$n the e$innin$ of the approximated section on the screen left clic of the mouse" then theend of the section ri$ht clic. The current value of the apparent velocit !ill e sho!n in the

$reen line in the top left corner of the screen.

Record the otained values of velocities into a text file. It can e made automaticall. ;or that"

!hile the 'inetool is active" select Tools()''rox!*ate("a,e 'ara*eters menuentr.

&dditional !indo! !ith an editale text field !ill open. Cop the current velocit there pressin$

Ctrl@A!hile the "creen !s'la- !indo! is in focus. (ou can cop as man values as ou lie.

2%


27/58

Comments can e added to the copied values in the !indo!"


28/58

Compare the appearance of the data efore and after the spherical diver$ence correction. ;or this"

run the flo! t!o times !ith the active and >commented> )*'l!tude Correct!on module. 9to

EcommentF the module ri$htclic it !ith the mouse:. &s a result" t!o "creen !s'la- !indo!s

appear on the screen" one of !hich contains corrected data" the other one initial data.

Spectrum spreading

&fter the correction for spherical diver$ence" add the module Pred!ct!,e econ,olut!onto the

flo!. 5hen the purpose of the predictive deconvolution is spectrum spreadin$" it is reasonale to set

prediction $ap e4ual to one sample" to select the filter len$th close to the len$th of the !avelet and

to assi$n the !indo! for the calculation of the deconvolution operator in such a !a that it contains

the tar$et reflections. +asin$ on these considerations" some initial parameters can e assi$ned as

follo!s6

2A


29/58

*xperiment !ith different parameters" research ho! the level of !hite noise influences the result.The follo!in$ t!o fi$ures demonstrate the data efore and after the use of predictin$

deconvolution.

+efore the deconvolution6

20


30/58

&fter the deconvolution6

$andpass filtering

+andpass filterin$ is to e used after the deconvolution" aimed to decrease the level of lo!

fre4uenc and hi$hfre4uenc noise and to shape the spectrum of the trace to achieve a simple

!avelet. &dd the module 4and'ass !lter!nginto the flo! after the deconvolution routine. In the

parameters of the module select OrmsBs filter !ith the follo!in$ parameters6 ?1G-GAG 8.

)everal CD# $athers after the andpass filterin$ !ith these parameters are sho!n on the follo!in$

fi$ure.

3G


31/58

Trace amplitude e%uali&ation

The amplitudes" recorded each seismic receiver is influenced" amon$ other thin$s" theconditions around the source and the receiver. 5hen the data is not aimed for the dnamic

interpretation 9for example" for the purposes of &O analsis: it is not necessar to use the

complex procedures of the surfaceconsistent amplitude corrections" instead ou can tr to reduce

the differences et!een traces the simple traces e4uali8ation. To do this add the module

)*'l!tude Correct!oninto the flo! a$ain !ith the follo!in$ set of the parameters6

31


32/58

Note" that the !indo! !e select here for estimation of the avera$e amplitude of each trace contains

the tar$et reflections and does not contain trace sections efore the first arrivals.

&t the present moment the flo! loos as follo!s6

32


33/58

'ssigning muting parameters

)ince our processin$ is aimed to otain a seismic section of reflected !aves" in this case" direct

!ave is" oviousl" shall e considered as noise. The most effective method of suppression of this

noise is the top mutin$ from the e$innin$ of the trace to the time" e4ual to the direct !ave arrival

time" plus some time after it" containin$ the !avelet of the direct !ave.

In order to assi$n this mutin$" resort the traces in the module Trace &n'ut temporaril in the orderO;;)*T6CD#. To do it" chan$e the parameters of the module Trace Input as follo!s6

*xecute the flo!M the traces" sorted out in ascendin$ order of the O;;)*T header field !ill e

sho!n on the screen. )uch a $ather 9called" commonoffset $ather: allo!s convenient assi$nin$ the

mutin$ time" !hich !ill e suitale for all CD# $athers.

To do it" create a ne! pic o


34/58

& pic in the RadExProis the collection of the time values matched t!o header fields" as it is

considered that it is al!as possile to find t!o header fields that !ill unami$uousl identif a

trace 9for example" numer of CD# and offset" or shot point numer and channel numer:. In this

case" ho!ever" !e !ant the time of the mutin$ to e suitale for all CD# $athers and depend onl

on the offset. Therefore !e must ind the pic to onl one header field O;;)*T.

To do it" select the Tools(P!ck(P!ck 1eadersentr of the "creen !s'la- menu

3-


35/58

In oth columns of the open !indo! select O;;)*T6O;;)*T

Then clic the O/ utton and save the pic !ith the Tools(P!ck("a,e )s... command of the "creen

!s'la- menu. Indicate the name of the pic as top5mute.

3?


36/58

Top muting

In the flo! +3+ 1 preprocreturn to the initial sortin$ 9CD#6O;;)*T: chan$in$ respectivel the

Trace &n'utparameters.

&dd the module Trace Ed!t!ngto the end of the flo! 9efore the "creen !s'la- module: !ith the

follo!in$ parameters6

On the second ta specif the hori8on that !ill define mutin$" as a dataase pic top5mute" !hich

!as saved at the previous sta$e. The 1or!onta must loo lie this6

No! the flo! loos lie the follo!in$6

3%


37/58

*xecute it and mae sure that the result loos approximatel lie this6

3@


38/58

Execution of the preprocessing flow

&t this point ou ma consider that the parameters of preliminar data processin$ are selected and

ou can execute the flo! !ith the complete dataset. To do it chan$e the parameters of the

Trace &n'utin such a !a that no! the data from all CD# points enter the flo!6

&s the volume of data in the flo! is rather lar$e no!" !e have to execute it frame frame. In the

!indo! of the flo! editor select the low *odemenu entr and assi$n the frame si8e so that the

data of each frame !ere completel fit to the availale R&= memor6

&dd the module Trace Out'utto the end of the flo! in order to save the results of the preliminar

data processin$. In the parameter dialo$ of this routine create a ne! dataset !ith the name line " ;

preproc !here the data from the flo! !ill e saved to.

3A


39/58

Comment the "creen !s'la-.

;inall the processin$ flo! appears as follo!s6

*xecute the flo!.

(elocity analysis and stac)ing

Preparation of the data for #elocity analysis, super*gathering

&s a rule" in order to increase the si$naltonoise ratio and otain more coherent velocit spectra"velocit analsis is carried out on ensemles consistin$ of several ad


40/58

#lace the "u'er #at+er routine" !hich !ill form the super$athers" in the e$innin$ of the flo!.

It is reasonale to select the "u'er #at+erparameters approximatel as sho!n on the follo!in$

fi$ure.

That is" the velocit analsis !ill e carried out !ith an interval of ?G CD# points" each super

$ather !ill contain1G ad


41/58

The follo!in$ fi$ure sho!s the result of executin$ such a flo!.

It is eas to see that" due to the use of a sustantiall lar$er volume of data" the phases of the

reflected !aves are outlined much more confidentl than on sin$le CD# $athers..

-1


42/58

(elocity analysis

Comment the "creen !s'la- module or remove it from the flo!. ;or conductin$ the velocit

analsis" add the&nteract!,e 6eloc!t- )nal-s!sroutine to the end of the flo!.

'et us discuss the assi$nin$ order and the reasonale values of the parameters of the module.

;irst" it is necessar to specif" !here to save the resultin$ velocit pic. The output velocit fieldcan e stored either in a text file or in a dataase EvelocitpicF o


43/58

It is reasonale to store the velocit pics at the second level of the dataase" correspondin$ to the

line.

No! specif the same velocit pic as an input velocit function. It !ill e useful if ou decide to

return to the velocit analsis later and to continue the !or !ith the pic. ;or this in the &n'ut

6eloc!t- ta assi$n the same parameters as on the previous one.

&*'ortant6 5hen assi$nin$ a ne! velocit pic" its name must e specified first on the Out'ut

6eloc!t- ta and onl then on the &n'ut 6eloc!t- ta. Other!ise the pro$ram reports an error

messa$e.

-3


44/58

No! select the ta "u'er gat+erand s!itch off the 4!n offsetsoption. This option allo!s for

summin$ up the traces !ith the close offsets efore calculatin$ the velocit spectrum. This !ould

result in much faster calculation of the velocit spectrum" ho!ever its coherenc some!hat

deteriorates.

)elect the ta "e*blanceto assi$n the parameters of the velocit spectrum calculation6 the start andend velocities" the velocit step and the time step. The velocit spectrum !ill e calculated as a

normali8ed for the specified ran$e of velocities.

--


45/58

The parameters default for the considered data set are completel acceptale.

The remainin$ dialo$ tas are responsile for displa parameters of different elements of the

velocit analsis !indo!.

It is reasonale to eep the parameters default on the "e*blance !s'la- ta responsile for the

parameters of velocit spectrum displa.

-?


46/58

It is reasonale to displa the traces of the current super$ather for !hich the velocit analsis is

performed in color. )elect an palette" in !hich the traces efore and after the normal moveout

9N=O: corrections !ill e convenientl oserved 9 default the $rascale pallet is selected" here

!e are $oin$ to replace it the lac!hiteoran$e pallet:. ;or this" first select the Coloroption of

the !s'la- *ode in the ta #at+er.

-%


47/58

Then clic the Paletteutton and in the appeared dialo$ ox clic on the /oad 'aletteutton.

& set of the predefined palettes is stored in the folder" !here the Rad*x#ro paca$e is installed" in

P/LEE# sudirector. )elect the palettebl4wtord.pal.

-@


48/58

The result should e as sho!n in the follo!in$ fi$ure.

The dnamic stac 9/P !s'la-: and the panel of the constant velocit stacs 9C6" !s'la-: can

e convenientl oserved !hen the traces are displaed in !i$$le trace7variale area 9T(6):

mode. Therefore the parameters for them can e ept as the are set default.

-A


49/58

&fter assi$nin$ the parameters" execute the flo!.

&s a result" the interactive velocit analsis !indo! !ill appear. It consists of - parts 9from left to

ri$ht:6 the semlance 9velocities spectrum:" the current super$ather" the dnamic stac and the

constant velocit stac panels.

The dnamic stac consists of the traces" otained as a result of stacin$ of the CD# $athers of the

current super$ather corrected for N=O !ith !ith the current velocit pic. 5hen the velocit pic

chan$es" the stac is dnamicall recalculated.

The constant velocit panels sho! a series of staced traces for a series of constant velocities. *ach

stac fra$ment here is otained from the CD# $athers of the current super$ather corrected for

N=O !ith one or another constant velocit.

-0


50/58

elocit pic is made on the semlance panel. 5hen picin$" follo! the maximums of the ener$

of the semlance. &n example of a reasonale velocit pic for the aove fi$ure is sho!n elo!6

?G


51/58

&dditionall" the module &nteract!,e 6eloc!t- )nal-s!sallo!s accomplishin$ the follo!in$

actions" useful for the C of the velocit picin$6

The utton Non the tool ar s!itches on the mode" !hen the current super$ather is

dnamicall corrected for N=O !ith the current velocit pic. &t that" the travel time

curves of the reflections ideall must ecome rectified 9see the fi$ure elo!:.

?1


52/58

Clicin$ the !xutton of the tool ar ou ma displa the interval velocities calculated forthe current velocit pic accordin$ to the DixBs formula 9li$htlue loced curve on the

fi$ure:. + the !a" s!itchin$ this option on and chan$in$ insi$nificantl the stacin$

velocit 9arel movin$ one of the points of the velocit pic:" ou can see ho! extremel

unstale is the conversion of the R=) velocities 9that is !hat !e actuall pic: into the

interval velocities. (ou can see that even the sli$htest chan$es in the stacin$ velocit can

lead to sometimes catastrophic chan$es in the interval velocities. This effect is the $reater"

the less is the anal8ed interval.

&fter the velocit pic for this super$ather position is assi$ned" it is possile to pass to the next

position" clicin$ the utton !ith the ri$ht arro! on the tool ar. If ou carr out the velocit

analsis in the framed mode" ou can move throu$h the super$athers to the ri$ht or left !ithin thecurrent frame" other!ise !ithin the entire dataset.

Carr out the velocit analsis for all super$athers" then efore exitin$ the module press the "a,e

utton on the tool ar in order to save the created velocit pic.

Stac)ing

Create the flo! ++ ; stac4.

?2


53/58

The flo! must contain the follo!in$ routines6

Trace &n'ut" !hich enters the line " 1 preprocdataset into the flo! in the CD#6O;;)*T sortin$

order.

The NMO(NM& module to correct the traces for the N=O. The parameters of the module should e

?3


54/58

assi$ned as follo!s. )elect the NMO mode in the NMO ta" set mutin$ on the si$nal tension P 3G

9i.e. those parts of the traces" !hich as a result of the N=O correction !ill e extended to more than

3GQ" !ill e reset to 8ero:.

In the 6eloc!t- ta select the velocit pic" !hich !as otained as a result of the velocit analsis

performed efore.

&fter the NMO(NM& module in the flo!" place the Ense*ble "tackroutine. This module stacs

hori8ontall all the traces !ithin each ensemle in the flo!. )ince in this case in the Trace &n'ut at

the e$innin$ of the flo! the CD# header field !as selected as the first sortin$ e" the CD# $athers

!ill e considered as ensemles.

?-


55/58

&ssi$n the parameters of the Ense*ble "tack module as sho!n on the follo!in$ fi$ure.

;inall" the Trace Out'ut module should e the last one in the flo!" it !ill save the results to the

line " ; stac4 dataset" !hich is also reasonale to e created at the second structural level of the

dataase.

The flo! loos no! as sho!n on the follo!in$ fi$ure6

??


56/58

;or executin$ this flo!" s!itch on the framed mode. )et an reasonale frame !idth and mae sure

that the 1onor ense*ble boundar!esoption is on. This !ill ensure that each frame is completeduntil the last trace of the last ensemle in the frame.

*xecute the flo!.

?%


57/58

Display of the stac)

Create the flo! +0+ ; &iew stac4.

The flo! should consist of the modules Trace &n'utand "creen !s'la-. The Trace &n'utshould

read the otained stac 9line " 1 stac4: sorted CD#s.

The result should loo approximatel as sho!n on the follo!in$ fi$ure.

?@


58/58

En Tutorcdp

Documents

Transcript of En Tutorcdp