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seismic imaging tutorial exploding reflector modeling/migration Paul Sava Center for Wave Phenomena Colorado School of Mines psava@mines.edu WSI assignment modify the acquisition parameters to explore the illumination at different

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seismic imaging tutorial

“exploding reflector” modeling/migration Paul Sava

Center for Wave Phenomena Colorado School of Mines psava@mines.edu

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assignment modify the acquisition parameters to explore the illumination at different locations in the subsurface

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import packages

from r s f p r o j import ∗ import sigsbee , fdmod

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setup main parameters

par=s i g s b e e . paramwin () # Sigsbee2A parameters par [ ’ nt ’ ]=3001 # time steps ( samples ) par [ ’ kt ’ ]=100 # wavelet delay ( samples ) par [ ’ dt ’ ]=0.001 # time sampling (ms) par [ ’ nb ’ ]=100 # boundary s i z e ( g r i d p o i n t s ) fdmod . param ( par ) # p l o t t i n g parameters

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source coordinates

# source c o o r d i n a t e s ( exploding r e f l e c t o r s ) fdmod . boxarray ( ’ ss ’ ,6 ,2 ,1 ,12 ,8 ,1 , par ) # p l o t sources Plot ( ’ ss ’ , fdmod . s s p l o t ( ’ p l o t f a t =1 symbol=. ’ , par ))

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receiver coordinates

par [ ’ j r ’ ]=4 # r e c e i v e r jump ( g r i d p o i n t s ) par [ ’ nr ’ ]=120 # number of r e c e i v e r s par [ ’ f r ’ ]=100 # r e c e i v e r s

r i g i n

( g r i d p o i n t s ) # r e c e i v e r c o o r d i n a t e s fdmod . h o r i z o n t a l ( ’ t t ’ , par [ ’ oz ’]+ par [ ’ dz ’ ] , par ) Flow ( ’ r r ’ , ’ t t ’ , ’ window n2=%(nr )d j2=%(j r )d f2=%(f r )d ’%par ) # p l o t r e c e i v e r s Plot ( ’ r r ’ , fdmod . r r p l o t ( ’ ’ , par ))

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velocity/density models

# get v e l o c i t y s i g s b e e . g e t s t r v e l w i n ( ’ v s t r ’ , par ) Flow ( ’ velo ’ , ’ v s t r ’ , ’ smooth rect1 =100 rect2 =100 repeat=1 ’ ) # p l o t v e l o c i t y Plot ( ’ velo ’ , fdmod . cgrey ( ’ a l l p o s=y b i a s =1.43 ’ , par )) Result ( ’ velo ’ , [ ’ velo ’ , ’ ss ’ , ’ r r ’ ] , ’ Overlay ’ ) # p l o t d e n s i t y Flow ( ’ dens ’ , ’ velo ’ , ’ math output=1 ’ )

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source wavelet

# c o n s t r u c t wavelet fdmod . wavelet ( ’ wav ’ ,15 , par ) # transpose wavelet Flow ( ’wav ’ , ’ wav ’ , ’ transp ’ ) # p l o t wavelet Result ( ’wav ’ , ’ window n2=1000 | ’ + fdmod . waveplot ( ’ ’ , par ))

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FD modeling

# run FD modeling fdmod . awefd1 ( ’ temp ’ , ’ wfld ’ , ’wav ’ , ’ velo ’ , ’ dens ’ , ’ ss ’ , ’ r r ’ , ’ f r e e=n ’ , par )

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plot wavefield

# generate w a v e f i e l d movie Plot ( ’ wfld ’ , fdmod . wgrey ( ’ p c l i p =99 ’ , par ) , view=1) # p l o t w a v e f i e l d frames for i in range ( 1 0 ) : tag = ’−%02d ’ %( i ∗3) fdmod . wframe ( ’ wfld ’+tag , ’ wfld ’ , i ∗3 , ’ p c l i p =99 ’ , par ) Result ( ’ wfld ’+tag , [ ’ wfld ’+tag , ’ ss ’ , ’ r r ’ ] , ’ Overlay ’ )

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plot data

# undo wavelet delay Flow ( ’ data ’ , ’ temp ’ , ’ ’ ’ window squeeze=n f2=%(kt )d | pad end2=%(kt )d | put o2=%(ot ) g ’ ’ ’ %par ) # p l o t data Result ( ’ data ’ , ’ window j2=4 | transp | ’ + fdmod . dgrey ( ’ ’ , par ))

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FD migration

# run FD migration fdmod . zom( ’ imag ’ , ’ j d a t ’ , ’ data ’ , ’ velo ’ , ’ dens ’ , ’ r r ’ , ’ r r ’ , ’ f r e e=n ’ , par )

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plot image

# p l o t image Plot ( ’ imag ’ , ’ bandpass f l o =2 | ’ + fdmod . cgrey ( ’ p c l i p =99.9 ’ , par )) Result ( ’ imag ’ , [ ’ imag ’ , ’ r r ’ ] , ’ Overlay ’ )

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closing rules

End ()

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the contest

◮ random sources in the subsurface ◮ random receivers on the surface

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