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Fast 3D Target-Oriented Reverse Time Datuming

Fast 3D Target-Oriented Reverse Time Datuming. Shuqian Dong University of Utah. 2 Oct. 2008. Outline. Motivation. Theory. Numerical Tests. 2-D SEG/EAGE salt model. 3-D SEG/EAGE salt model. 3-D field data. Conclusions. Motivation. Numerical Tests. Theory. Conclusions. Motivation.

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Fast 3D Target-Oriented Reverse Time Datuming

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

  2. Outline • Motivation • Theory • Numerical Tests 2-D SEG/EAGE salt model 3-D SEG/EAGE salt model 3-D field data • Conclusions Motivation Numerical Tests Theory Conclusions

  3. Motivation Numerical Tests Theory Conclusions Outline • Motivation • Theory • Numerical Tests 2-D SEG/EAGE salt model 3-D SEG/EAGE salt model 3-D field data • Conclusions

  4. km/s Velocity model 0 0 0 Common shot gather 4.5 Time (s) z (km) z (km) 1.5 2.0 4.0 2.0 x (km) x (km) x (km) 8.0 8.0 8.0 0 0 0 KM image Problem: Defocusing: lower resolution, distorted image Multiples: image artifacts. Reason: KM: high frequency approximation. Motivation Numerical Tests Theory Conclusions Motivation Solutions?

  5. RTM image Velocity model KM image Motivation Numerical Tests Theory Conclusions Motivation Solutions: • Reverse time migration: solving two-way wave equation • Target-oriented reverse time datuming: • solving two-way wave equation to bypass overburden Luo, 2002: target-oriented RTD Luo and Schuster, 2004: bottom-up strategy

  6. RTD • Complex structures cause defocusing effects • RTD can reduce defocusing effects • RTM is computationally expensive • RTD + Kirchhoff = accurate + cheap Motivation Numerical Tests Theory Conclusions Motivation

  7. Motivation Numerical Tests Theory Conclusions Motivation • Reduce defocusing effects for subsalt imaging • Closer to the target: better resolution • Bottom-up strategy: computational efficiency • Redatumed data can be used for least squares • migration and migration velocity analysis (MVA)

  8. Motivation Numerical Tests Theory Conclusions Outline • Motivation • Theory • Numerical Tests 2-D SEG/EAGE salt model 3-D SEG/EAGE salt model 3-D field data • Conclusions

  9. Motivation Numerical Tests Theory Conclusions Theory Reverse time datuming d(s|r) S R x’’ x’

  10. d(s|x’’) g*(r|x”) d(s|r) d(s|x”)= Motivation Numerical Tests Theory Conclusions Theory Reverse time datuming S R x’’ x’

  11. g*(r|x”) d(s|r) d(s|x”)= d(x’|x’’) Motivation Numerical Tests Theory Conclusions Theory Reverse time datuming S R d(x’|x”)=g*(s|x’) d(s|x”) x’’ x’

  12. Real source number on surface: 10 Virtual source number on datum: 3 Motivation Numerical Tests Theory Conclusions Theory Calculate Green’s functions VSP (source on surface) Green’s functions: 10

  13. Real source number on surface: 10 Virtual source number on datum: 3 VSP (source on surface) Green’s functions: 10 Motivation Numerical Tests Theory Conclusions Theory Calculate Green’s functions Reciprocity: RVSP=VSP RVSP (source on datum) Green’s functions: 3

  14. Reciprocity: RVSP =>VSP Green’s functions: FFT: time domain => frequency domain Crosscorrelation: Green’s functions with original data IFFT: frequency domain => time domain Redatumed data Motivation Numerical Tests Theory Conclusions Workflow FD: Compute RVSP Green’s functions Original data: FFT: time domain =>frequency domain

  15. Motivation Numerical Tests Theory Conclusions Outline • Motivation • Theory • Numerical Tests 2-D SEG/EAGE salt model 3-D SEG/EAGE salt model 3-D field data • Conclusions

  16. km/s Velocity model 0 0 0 0 4.5 Time (s) Time (s) Time (s) z (km) 1.5 2.0 4.0 4.0 4.0 x (km) x (km) x (km) x (km) 8.0 8.0 8.0 8.0 0 0 0 0 Motivation Numerical Tests Theory Conclusions 2D SEG/EAGE Test RVSP Green’s function True CSG at datum Redatumed CSG

  17. km/s Velocity model 0 0 0 0 4.5 z (km) z (km) z (km) z (km) 1.5 2.0 2.0 2.0 2.0 x (km) x (km) x (km) x (km) 8.0 8.0 8.0 8.0 0 0 0 0 KM image RTM image Motivation Numerical Tests Theory Conclusions 2D SEG/EAGE Test KM of redatumed data

  18. Motivation Numerical Tests Theory Conclusions Outline • Motivation • Theory • Numerical Tests 2-D SEG/EAGE salt model 3-D SEG/EAGE salt model 3-D field data • Conclusions

  19. km/s 4.5 0 x (km) 3.5 0 1.5 Z (km) 2.0 0 y (km) 2 Motivation Numerical Tests Theory Conclusions 3D SEG/EAGE test Velocity model SSP geometry: 1700 shots 1700 receivers Datum depth: 1.5 km RVSP Green’s functions: 850 shots 1700 receivers

  20. Original CSG RVSP Green’s function 0 0 0 0 Time (s) Time (s) Time (s) Time (s) 2.5 2.5 2.5 2.5 Redatumed CSG True CSG at datum y (km) y (km) y (km) y (km) 3.5 3.5 3.5 3.5 0 0 0 0 Motivation Numerical Tests Theory Conclusions 3D SEG/EAGE test

  21. KM of RTD data x (km) x (km) 0 0 3.5 3.5 0 0 Z (km) Z (km) 2.0 2.0 0 0 y (km) y (km) 2 2 KM of original data Motivation Numerical Tests Theory Conclusions 3D SEG/EAGE test

  22. KM of original data KM of redatumed data 0 0 0 z (km) z (km) z (km) 2.0 2.0 2.0 3.5 3.5 3.5 x (km) x (km) x (km) 0 0 0 Velocity model Motivation Numerical Tests Theory Conclusions 3D SEG/EAGE test ( Inline No. 41 )

  23. 0 0 0 z (km) z (km) z (km) 2.0 2.0 2.0 3.5 3.5 3.5 x (km) x (km) x (km) 0 0 0 Motivation Numerical Tests Theory Conclusions 3D SEG/EAGE test KM of original data KM of redatumed data Velocity model ( Inline No. 101 )

  24. 0 0 0 z (km) z (km) z (km) 2.0 2.0 2.0 2.0 2.0 2.0 y (km) y (km) y (km) 0 0 0 Motivation Numerical Tests Theory Conclusions 3D SEG/EAGE test KM of original data KM of redatumed data Velocity model ( Crossline No. 161 )

  25. 0 0 0 z (km) z (km) z (km) 2.0 2.0 2.0 2.0 2.0 2.0 y (km) y (km) y (km) 0 0 0 Motivation Numerical Tests Theory Conclusions 3D SEG/EAGE test KM of original data KM of redatumed data Velocity model ( Crossline No. 201 )

  26. 0 0 0 y (km) y (km) y (km) 2.0 2.0 2.0 3.5 3.5 3.5 x (km) x (km) x (km) 0 0 0 Motivation Numerical Tests Theory Conclusions 3D SEG/EAGE test KM of original data KM of redatumed data Velocity model ( depth: z=1.4 km )

  27. 0 0 0 y (km) y (km) y (km) 2.0 2.0 2.0 3.5 3.5 3.5 x (km) x (km) x (km) 0 0 0 Motivation Numerical Tests Theory Conclusions 3D SEG/EAGE test KM of original data KM of redatumed data Velocity model ( depth: z=1.5 km )

  28. Motivation Numerical Tests Theory Conclusions Outline • Motivation • Theory • Numerical Tests 2-D SEG/EAGE salt model 3-D SEG/EAGE salt model 3-D field data • Conclusions

  29. Interval velocity model km/s 0 5.5 Z (km) 8.0 0 y (km) 12 x (km) 6.0 0 1.5 Motivation Numerical Tests Theory Conclusions 3D 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

  30. Redatumed CSG Original CSG 0 0 Time (s) Time (s) 6.0 6.0 y (km) y (km) 4.5 4.5 0 0 Motivation Numerical Tests Theory Conclusions 3D Field Data Test

  31. x (km) 0 12 KM of original data 0 Z (km) 8 KM of redatumed data 0 0 y (km) 5 Z (km) 8 0 12 y (km) x (km) 5 0 Motivation Numerical Tests Theory Conclusions 3D Field Data Test KM of RTD data

  32. 0 0 Z (km) Z (km) 8.0 8.0 0 0 X (km) X (km) 12 12 Motivation Numerical Tests Theory Conclusions 3D Field Data Test ( Inline No. 21 ) KM of original data KM of RTD data

  33. 0 0 Z (km) Z (km) 8.0 8.0 0 0 X (km) X (km) 12 12 Motivation Numerical Tests Theory Conclusions 3D Field Data Test ( Inline No. 41 ) KM of original data KM of RTD data

  34. 0 0 Z (km) Z (km) 8.0 8.0 0 0 X (km) X (km) 12 12 Motivation Numerical Tests Theory Conclusions 3D Field Data Test ( Inline No. 61 ) KM of original data KM of RTD data

  35. 0 0 Z (km) Z (km) 8.0 8.0 0 0 Y (km) Y (km) 5.0 5.0 Motivation Numerical Tests Theory Conclusions 3D Field Data Test ( Crossline No. 41 ) KM of original data KM of RTD data

  36. 0 0 Z (km) Z (km) 8.0 8.0 0 0 Y (km) Y (km) 5.0 5.0 Motivation Numerical Tests Theory Conclusions 3D Field Data Test ( Crossline No. 61 ) KM of original data KM of RTD data

  37. 0 0 Z (km) Z (km) 8.0 8.0 0 0 Y (km) Y (km) 5.0 5.0 Motivation Numerical Tests Theory Conclusions 3D Field Data Test ( Crossline No. 81 ) KM of original data KM of RTD data

  38. 0 0 Y (km) Y (km) 5.0 5.0 0 0 X (km) X (km) 12 12 Motivation Numerical Tests Theory Conclusions 3D Field Data Test ( Depth 2.0 km ) KM of original data KM of RTD data

  39. 0 0 Y (km) Y (km) 5.0 5.0 0 0 X (km) X (km) 12 12 Motivation Numerical Tests Theory Conclusions 3D Field Data Test ( Depth 2.5 km ) KM of original data KM of RTD data

  40. 0 0 Y (km) Y (km) 5.0 5.0 0 0 X (km) X (km) 12 12 Motivation Numerical Tests Theory Conclusions 3D Field Data Test ( Depth 4.0 km ) KM of original data KM of RTD data

  41. Motivation Numerical Tests Theory Conclusions Computational Costs

  42. Motivation Numerical Tests Theory Conclusions Outline • Motivation • Theory • Numerical Tests 2-D SEG/EAGE salt model 3-D SEG/EAGE salt model 3-D field data • Conclusions

  43. Motivation Numerical Tests Theory Conclusions Conclusions • 2-D numerical test KM of RTD achieved image quality comparable to RTM at much lower cost. • 3-D numerical test 3-D RTD is implemented for synthetic and GOM data at acceptable computational cost; Apparent improvements in mage quality are achieved compared to KM image of original data. • Future application Subsalt least suqares migration and migration velocity analysis

  44. Acknowledgements • 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!

  46. km/s Velocity model 0 0 0 0 Common shot gather 4.5 Time (s) z (km) z (km) z (km) 1.5 2.0 2.0 2.0 4.0 x (km) x (km) x (km) x (km) 8.0 8.0 8.0 8.0 0 0 0 0 KM image RTM image Motivation Numerical Tests Theory Conclusions Motivation

  47. Motivation Numerical Tests Theory Conclusions Theory Traditional reverse time datuming d(s|r) S R x’’ x’

  48. d(s|x’’) g*(r|x”) d(s|r) d(s|x”)= Motivation Numerical Tests Theory Conclusions Theory Reverse time Datuming S R x’’ x’

  49. g*(r|x”) d(s|r) d(s|x”)= d(x’|x’’) Motivation Numerical Tests Theory Conclusions Theory Reverse time Datuming S R d(x’|x”)=g*(s|x’) d(s|x”) x’’ x’

  50. Motivation Numerical Tests Theory Conclusions Theory Target-oriented RTD (Luo , 2006)

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