1 Fast 3D Target-Oriented Reverse Time Datuming Shuqian Dong University of Utah 2 Oct. 2008

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1

Fast 3D Target-Oriented Reverse Time Datuming

Shuqian Dong

University of Utah2 Oct. 2008

2

OutlineOutline

• MotivationMotivation

• TheoryTheory

• ConclusionsConclusions

• Numerical TestsNumerical Tests 2-D SEG/EAGE salt model2-D SEG/EAGE salt model

3-D SEG/EAGE salt model3-D SEG/EAGE salt model

3-D field data3-D field data

Motivation Theory Numerical Tests Conclusions

3

OutlineOutline

• MotivationMotivation

• TheoryTheory

• ConclusionsConclusions

• Numerical TestsNumerical Tests 2-D SEG/EAGE salt model2-D SEG/EAGE salt model

3-D SEG/EAGE salt model3-D SEG/EAGE salt model

3-D field data3-D field data

Motivation Theory Numerical Tests Conclusions

4Motivation Theory Numerical Tests Conclusions

z (k

m)

z (k

m)

00

2.02.0

KM image

x (km)x (km)00 8.08.0

Tim

e (s

)T

ime

(s)

00

4.04.0

Common shot gather

x (km)x (km)00 8.08.0

MotivationMotivationz

(km

)z

(km

)

00

2.02.0

Velocity model

x (km)x (km)00 8.08.0

km/s

4.54.5

1.51.5

Defocusing: lower resolution, distorted image

Multiples: image artifacts.

Problem:

KM: high frequency approximation.

Reason:

Solutions?

5

Solutions:Solutions:

MotivationMotivation

• Reverse time migration: solving two-way wave equationReverse time migration: solving two-way wave equation

Velocity modelKM image RTM image

• Target-oriented reverse time datuming:Target-oriented reverse time datuming: solving two-way wave equation to bypass overburdensolving two-way wave equation to bypass overburden

Luo, 2002: target-oriented RTDLuo, 2002: target-oriented RTDLuo and Schuster, 2004: bottom-up strategyLuo and Schuster, 2004: bottom-up strategy

Motivation Theory Numerical Tests Conclusions

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MotivationMotivation

Motivation Theory Numerical Tests Conclusions

• RTD + Kirchhoff = accurate + cheap RTD + Kirchhoff = accurate + cheap

• RTD can reduce defocusing effectsRTD can reduce defocusing effects

RTDRTD

• Complex structures cause defocusing effectsComplex structures cause defocusing effects

• RTM is computationally expensiveRTM is computationally expensive

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• Bottom-up strategy: computational efficiency Bottom-up strategy: computational efficiency

• Redatumed data can be used for least squares Redatumed data can be used for least squares migration and migration velocity analysis (MVA)migration and migration velocity analysis (MVA)

• Reduce defocusing effects for subsalt imagingReduce defocusing effects for subsalt imaging

• Closer to the target: better resolutionCloser to the target: better resolution

Motivation Theory Numerical Tests Conclusions

MotivationMotivation

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OutlineOutline

• MotivationMotivation

• TheoryTheory

• ConclusionsConclusions

• Numerical TestsNumerical Tests 2-D SEG/EAGE salt model2-D SEG/EAGE salt model

3-D SEG/EAGE salt model3-D SEG/EAGE salt model

3-D field data3-D field data

Motivation Theory Numerical Tests Conclusions

9

d(s|r)d(s|r)

RRSS

x’x’ x’’x’’

Reverse time datumingReverse time datuming

TheoryTheory

Motivation Theory Numerical Tests Conclusions

10

SS

x’x’ x’’x’’

d(s|x”)=d(s|x”)= g*(r|x”)g*(r|x”) d(s|r)d(s|r)d(s|x’’)d(s|x’’)

Reverse time datumingReverse time datuming

RR

TheoryTheory

Motivation Theory Numerical Tests Conclusions

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x’x’ x’’x’’

d(s|x”)=d(s|x”)= g*(r|x”)g*(r|x”) d(s|r)d(s|r)d(x’|x’’)d(x’|x’’)

d(x’|x”)=g*(s|x’) d(s|x”)d(x’|x”)=g*(s|x’) d(s|x”)

Reverse time datumingReverse time datuming

RRSS

TheoryTheory

Motivation Theory Numerical Tests Conclusions

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TheoryTheory

Motivation Theory Numerical Tests Conclusions

Calculate Green’s functionsCalculate Green’s functions

Real source number Real source number on surface: 10on surface: 10

Virtual source number Virtual source number on datum: 3on datum: 3

VSP (source on surface) VSP (source on surface) Green’s functions: 10Green’s functions: 10

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Calculate Green’s functionsCalculate Green’s functions

TheoryTheory

Motivation Theory Numerical Tests Conclusions

Real source number Real source number on surface: 10on surface: 10

Virtual source number Virtual source number on datum: 3on datum: 3

VSP (source on surface) VSP (source on surface) Green’s functions: 10Green’s functions: 10

RVSP (source on datum) RVSP (source on datum) Green’s functions: 3Green’s functions: 3

Reciprocity: RVSP=VSPReciprocity: RVSP=VSP

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FD: Compute RVSP Green’s functions

Original data: FFT: time domain =>frequency domain

Crosscorrelation: Green’s functions with original data

WorkflowWorkflow

Motivation Theory Numerical Tests Conclusions

Reciprocity: RVSP =>VSP

Green’s functions: FFT: time domain => frequency domain

IFFT: frequency domain => time domain

Redatumed data

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OutlineOutline

• MotivationMotivation

• TheoryTheory

• ConclusionsConclusions

• Numerical TestsNumerical Tests 2-D SEG/EAGE salt model2-D SEG/EAGE salt model

3-D SEG/EAGE salt model3-D SEG/EAGE salt model

3-D field data3-D field data

Motivation Theory Numerical Tests Conclusions

16Motivation Theory Numerical Tests Conclusions

z (k

m)

z (k

m)

00

2.02.0

Velocity model

x (km)x (km)00 8.08.0

km/s

4.54.5

1.51.5

Tim

e (s

)T

ime

(s)

00

4.04.0

RVSP Green’s function

x (km)x (km)00 8.08.0

2D SEG/EAGE Test2D SEG/EAGE Test

Tim

e (s

)T

ime

(s)

00

4.04.0

True CSG at datum

x (km)x (km)00 8.08.0

Tim

e (s

)T

ime

(s)

00

4.04.0

Redatumed CSG

x (km)x (km)00 8.08.0

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z (k

m)

z (k

m)

00

2.02.0

Velocity model

x (km)x (km)00 8.08.0

km/s

4.54.5

1.51.5

z (k

m)

z (k

m)

00

2.02.0

KM image

x (km)x (km)00 8.08.0

z (k

m)

z (k

m)

00

2.02.0

RTM image

x (km)x (km)00 8.08.0

z (k

m)

z (k

m)

00

2.02.0

KM of redatumed data

x (km)x (km)00 8.08.0

Motivation Theory Numerical Tests Conclusions

2D SEG/EAGE Test2D SEG/EAGE Test

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OutlineOutline

• MotivationMotivation

• TheoryTheory

• ConclusionsConclusions

• Numerical TestsNumerical Tests 2-D SEG/EAGE salt model2-D SEG/EAGE salt model

3-D SEG/EAGE salt model3-D SEG/EAGE salt model

3-D field data3-D field data

Motivation Theory Numerical Tests Conclusions

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3D SEG/EAGE test3D SEG/EAGE test Z

(km

)Z

(km

)

00

2.02.0

y (km)y (km)

22

00

x (km)x (km)

3.53.5

00

km/s

4.54.5

1.51.5

Velocity model

SSP geometry:

1700 shots

1700 receivers

Datum depth:

1.5 km

RVSP Green’s functions:

850 shots

1700 receivers

Motivation Theory Numerical Tests Conclusions

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3D SEG/EAGE test3D SEG/EAGE test

y (km)y (km)00 3.53.5

Tim

e (s

)T

ime

(s)

00

2.52.5

Original CSG

Motivation Theory Numerical Tests Conclusions

y (km)y (km)00 3.53.5

Tim

e (s

)T

ime

(s)

00

2.52.5

RVSP Green’s function

y (km)y (km)00 3.53.5

Tim

e (s

)T

ime

(s)

00

2.52.5

True CSG at datum

y (km)y (km)00 3.53.5

Tim

e (s

)T

ime

(s)

00

2.52.5

Redatumed CSG

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Z (

km)

Z (

km)00

2.02.0

y (km)y (km)

22

00

x (km)x (km) 3.53.5

00

KM of original data

3D SEG/EAGE test3D SEG/EAGE test

Z (

km)

Z (

km)

00

2.02.0

y (km)y (km)

22

00

x (km)x (km) 3.53.5

00

KM of RTD data

Motivation Theory Numerical Tests Conclusions

22x (km)x (km)00 3.53.5

z (k

m)

z (k

m)

00

2.02.0

Velocity modelx (km)x (km)00 3.53.5

z (k

m)

z (k

m)

00

2.02.0

KM of original data

x (km)x (km)00 3.53.5

z (k

m)

z (k

m)

00

2.02.0

KM of redatumed data

( Inline No. 41 )( Inline No. 41 )

Motivation Theory Numerical Tests Conclusions

3D SEG/EAGE test3D SEG/EAGE test

23x (km)x (km)00 3.53.5

z (k

m)

z (k

m)

00

2.02.0

Velocity modelx (km)x (km)00 3.53.5

z (k

m)

z (k

m)

00

2.02.0

KM of original data

x (km)x (km)00 3.53.5

z (k

m)

z (k

m)

00

2.02.0

KM of redatumed data

( Inline No. 101 )( Inline No. 101 )

Motivation Theory Numerical Tests Conclusions

3D SEG/EAGE test3D SEG/EAGE test

24y (km)y (km)00 2.02.0

z (k

m)

z (k

m)

00

2.02.0

Velocity modely (km)y (km)00 2.02.0

z (k

m)

z (k

m)

00

2.02.0

KM of original data

y (km)y (km)00 2.02.0

z (k

m)

z (k

m)

00

2.02.0

KM of redatumed data

( Crossline No. 161 )( Crossline No. 161 )

Motivation Theory Numerical Tests Conclusions

3D SEG/EAGE test3D SEG/EAGE test

25y (km)y (km)00 2.02.0

z (k

m)

z (k

m)

00

2.02.0

Velocity modely (km)y (km)00 2.02.0

z (k

m)

z (k

m)

00

2.02.0

KM of original data

y (km)y (km)00 2.02.0

z (k

m)

z (k

m)

00

2.02.0

KM of redatumed data

( Crossline No. 201 )( Crossline No. 201 )

Motivation Theory Numerical Tests Conclusions

3D SEG/EAGE test3D SEG/EAGE test

26x (km)x (km)00 3.53.5

y (k

m)

y (k

m)

00

2.02.0

Velocity modelx (km)x (km)00 3.53.5

y (k

m)

y (k

m)

00

2.02.0

KM of original data

x (km)x (km)00 3.53.5

y (k

m)

y (k

m)

00

2.02.0

KM of redatumed data

( depth: z=1.4 km )( depth: z=1.4 km )

Motivation Theory Numerical Tests Conclusions

3D SEG/EAGE test3D SEG/EAGE test

27x (km)x (km)00 3.53.5

y (k

m)

y (k

m)

00

2.02.0

Velocity modelx (km)x (km)00 3.53.5

y (k

m)

y (k

m)

00

2.02.0

KM of original data

x (km)x (km)00 3.53.5

y (k

m)

y (k

m)

00

2.02.0

KM of redatumed data

( depth: z=1.5 km )( depth: z=1.5 km )

Motivation Theory Numerical Tests Conclusions

3D SEG/EAGE test3D SEG/EAGE test

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OutlineOutline

• MotivationMotivation

• TheoryTheory

• ConclusionsConclusions

• Numerical TestsNumerical Tests 2-D SEG/EAGE salt model2-D SEG/EAGE salt model

3-D SEG/EAGE salt model3-D SEG/EAGE salt model

3-D field data3-D field data

Motivation Theory Numerical Tests Conclusions

29

Z (

km)

Z (

km)

00

8.08.0

y (km)y (km)

6.06.0

00

x (km)x (km)

1212

00

Interval velocity model

3D Field Data Test3D Field Data Test

OBC geometry:

50,000 shots

180 receivers per shot

Datum depth:

1.5 km

RVSP Green’s functions:

5,000 shots

180 receivers per shot

km/s5.55.5

1.51.5

Motivation Theory Numerical Tests Conclusions

30

3D Field Data Test3D Field Data Test

y (km)y (km)00 4.54.5

Tim

e (s

)T

ime

(s)

00

6.06.0

Original CSG

y (km)y (km)00 4.54.5

Tim

e (s

)T

ime

(s)

00

6.06.0

Redatumed CSG

Motivation Theory Numerical Tests Conclusions

31

KM of RTD data

Z (

km)

Z (

km)00

88

y (km)y (km)

55

00

x (km)x (km) 1212

00

KM of original data

Z (

km)

Z (

km)

00

88

y (km)y (km)

55

00

x (km)x (km) 1212

00

KM of redatumed data

Motivation Theory Numerical Tests Conclusions

3D Field Data Test3D Field Data Test

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X (km)X (km)00 1212

Z (

km)

Z (

km)

00

8.08.0

KM of original data KM of RTD data

( Inline No. 21 )( Inline No. 21 )

X (km)X (km)00 1212

Z (

km)

Z (

km)

00

8.08.0

Motivation Theory Numerical Tests Conclusions

3D Field Data Test3D Field Data Test

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( Inline No. 41 )( Inline No. 41 )

X (km)X (km)00 1212

Z (

km)

Z (

km)

00

8.08.0

KM of RTD data

X (km)X (km)00 1212

Z (

km)

Z (

km)

00

8.08.0

Motivation Theory Numerical Tests Conclusions

3D Field Data Test3D Field Data Test

KM of original data

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( Inline No. 61 )( Inline No. 61 )

X (km)X (km)00 1212

Z (

km)

Z (

km)

00

8.08.0

KM of RTD data

X (km)X (km)00 1212

Z (

km)

Z (

km)

00

8.08.0

Motivation Theory Numerical Tests Conclusions

3D Field Data Test3D Field Data Test

KM of original data

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( Crossline No. 41 )( Crossline No. 41 )

Y (km)Y (km)00 5.05.0

Z (

km)

Z (

km)

00

8.08.0

KM of RTD data

Y (km)Y (km)00 5.05.0

Z (

km)

Z (

km)

00

8.08.0

Motivation Theory Numerical Tests Conclusions

3D Field Data Test3D Field Data Test

KM of original data

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( Crossline No. 61 )( Crossline No. 61 )

Y (km)Y (km)00 5.05.0

Z (

km)

Z (

km)

00

8.08.0

KM of RTD data

Y (km)Y (km)00 5.05.0

Z (

km)

Z (

km)

00

8.08.0

Motivation Theory Numerical Tests Conclusions

3D Field Data Test3D Field Data Test

KM of original data

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( Crossline No. 81 )( Crossline No. 81 )

Y (km)Y (km)00 5.05.0

Z (

km)

Z (

km)

00

8.08.0

KM of RTD data

Y (km)Y (km)00 5.05.0

Z (

km)

Z (

km)

00

8.08.0

Motivation Theory Numerical Tests Conclusions

3D Field Data Test3D Field Data Test

KM of original data

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( Depth 2.0 km )( Depth 2.0 km )

X (km)X (km)00 1212

Y (

km)

Y (

km)

00

5.05.0

KM of RTD data

X (km)X (km)00 1212

Y (

km)

Y (

km)

00

5.05.0

Motivation Theory Numerical Tests Conclusions

3D Field Data Test3D Field Data Test

KM of original data

39

( Depth 2.5 km )( Depth 2.5 km )

X (km)X (km)00 1212

Y (

km)

Y (

km)

00

5.05.0

KM of RTD data

X (km)X (km)00 1212

Y (

km)

Y (

km)

00

5.05.0

Motivation Theory Numerical Tests Conclusions

3D Field Data Test3D Field Data Test

KM of original data

40

( Depth 4.0 km )( Depth 4.0 km )

X (km)X (km)00 1212

Y (

km)

Y (

km)

00

5.05.0

KM of RTD data

X (km)X (km)00 1212

Y (

km)

Y (

km)

00

5.05.0

Motivation Theory Numerical Tests Conclusions

3D Field Data Test3D Field Data Test

KM of original data

41

RTM

(CPU-hours)

RTD

(CPU-hours)

Speed up

2D SEG/EAGE test

21.0 6.5 3

3D SEG/EAGE test

16,000

(estimated)1,866 9

3D filed data test5,000,000

(estimated)52,000 100

Computational CostsComputational Costs

Motivation Theory Numerical Tests Conclusions

42

OutlineOutline

• MotivationMotivation

• TheoryTheory

• ConclusionsConclusions

• Numerical TestsNumerical Tests 2-D SEG/EAGE salt model2-D SEG/EAGE salt model

3-D SEG/EAGE salt model3-D SEG/EAGE salt model

3-D field data3-D field data

Motivation Theory Numerical Tests Conclusions

43

KM of RTD achieved image quality comparable to RTM KM of RTD achieved image quality comparable to RTM

at much lower cost.at much lower cost.

Motivation Theory Numerical Tests Conclusions

• 2-D numerical test2-D numerical test

3-D RTD is implemented for synthetic and GOM data at 3-D RTD is implemented for synthetic and GOM data at acceptable computational cost;acceptable computational cost;

• 3-D numerical test3-D numerical test

Apparent improvements in mage quality are achieved Apparent improvements in mage quality are achieved compared to KM image of original data.compared to KM image of original data.

• Future applicationFuture application

Subsalt least suqares migration and migration velocity Subsalt least suqares migration and migration velocity analysisanalysis

ConclusionsConclusions

44

AcknowledgementsAcknowledgements• Dr. Gerard Schuster and my committee members:

Dr. Michael Zhdanov, Dr. Richard D. Jarrard for their advice and constructive criticism;

• UTAM friends:– Dr. Xiang Xiao, Weiping Cao, and Chaiwoot Boonyasiriwat

for their help on my thesis research;

– Ge Zhang for his experiences on field data processing;

– Dr. Sherif Hanafy, Shengdong Liu, Naoshi Aoki and all other UTAM members for their support in my life and work;

• CHPC for the computation support.

45

Thanks!Thanks!

46Motivation Theory Numerical Tests Conclusions

z (k

m)

z (k

m)

00

2.02.0

Velocity model

x (km)x (km)00 8.08.0

km/s

4.54.5

1.51.5

z (k

m)

z (k

m)

00

2.02.0

KM image

x (km)x (km)00 8.08.0

Tim

e (s

)T

ime

(s)

00

4.04.0

Common shot gather

x (km)x (km)00 8.08.0

MotivationMotivation

z (k

m)

z (k

m)

00

2.02.0

RTM image

x (km)x (km)00 8.08.0

47

d(s|r)d(s|r)

RRSS

x’x’ x’’x’’

Traditional reverse time datumingTraditional reverse time datuming

TheoryTheory

Motivation Theory Numerical Tests Conclusions

48

SS

x’x’ x’’x’’

d(s|x”)=d(s|x”)= g*(r|x”)g*(r|x”) d(s|r)d(s|r)d(s|x’’)d(s|x’’)

Reverse time DatumingReverse time Datuming

RR

TheoryTheory

Motivation Theory Numerical Tests Conclusions

49

x’x’ x’’x’’

d(s|x”)=d(s|x”)= g*(r|x”)g*(r|x”) d(s|r)d(s|r)d(x’|x’’)d(x’|x’’)

d(x’|x”)=g*(s|x’) d(s|x”)d(x’|x”)=g*(s|x’) d(s|x”)

Reverse time DatumingReverse time Datuming

RRSS

TheoryTheory

Motivation Theory Numerical Tests Conclusions

50

Target-oriented RTDTarget-oriented RTD(Luo , 2006)(Luo , 2006)

TheoryTheory

Motivation Theory Numerical Tests Conclusions

51

Target-oriented RTDTarget-oriented RTD(Luo , 2006)(Luo , 2006)

g(s|x’)g(s|x’) g(r|x”)g(r|x”)** d(s|r)d(s|r)

= d(x’|x’’)= d(x’|x’’)

TheoryTheory

Motivation Theory Numerical Tests Conclusions

52

Target-oriented RTDTarget-oriented RTD(Luo , 2006)(Luo , 2006)

TheoryTheory

Motivation Theory Numerical Tests Conclusions

g(s|x’)g(s|x’) g(r|x")g(r|x")** d(s|r)d(s|r)

= d(x’|x’’)= d(x’|x’’)

53

Compute VSP Green’s functions in time domain

Original data: time domain to frequency domain

Green’s functions: Time domain to frequency domain

Reverse time datum for different frequency

WorkflowWorkflow

Sum over frequency

Redatumed data: frequency domain to time domain

Motivation Theory Numerical Tests Conclusions

54

FD: Compute RVSP Green’s functions

Original data: FFT: time domain =>frequency domain

Crosscorrelation: Green’s functions with original data

WorkflowWorkflow

Motivation Theory Numerical Tests Conclusions

Reciprocity: RVSP =>VSP

Green’s functions: FFT: time domain => frequency domain

Sum over frequency

IFFT: frequency domain => time domain

Redatumed data

55

ConclusionsConclusions

• Bottom-up strategy: computational efficiency Bottom-up strategy: computational efficiency

• Redatumed data can be used by LSM & MVARedatumed data can be used by LSM & MVA

• Reduce defocusing effects for subsalt imagingReduce defocusing effects for subsalt imaging

• Closer to the target: better resolutionCloser to the target: better resolution

Benefits:Benefits:

Limitations:Limitations:

•Extra I/O for accessing Green’s functionsExtra I/O for accessing Green’s functions

Motivation Theory Numerical Tests Conclusions

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