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VSP->SWP Interferometry

VSP->SWP Interferometry. Redatum sources below overburden. Local VSP migration. 3x3 Classification Matrix. SSP. VSP. SWP. SSP. SSP. SSP. SSP. VSP. SSP. SWP. VSP. VSP. SSP. VSP. VSP. VSP. SWP. SSP. SWP. SWP. SWP. VSP. SWP. SWP. Motivation.

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VSP->SWP Interferometry

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  1. VSP->SWP Interferometry Redatum sources below overburden Local VSP migration

  2. 3x3 Classification Matrix SSP VSP SWP SSP SSP SSP SSP VSP SSP SWP VSP VSP SSP VSP VSP VSP SWP SSP SWP SWP SWP VSP SWP SWP

  3. Motivation Problem: Overburden+statics defocus VSP migration Solution: VSP -> SWP Transform Redatum sources below overburden Local VSP migration

  4. Outline • Motivation • Interferometry Theory • Numerical Examples • Conclusion

  5. SWP VSP { { Im G(B|A) + S S 0 0 0 0 Reciprocity Correlation Equation Far-field VSP -> SWP Transform = kG(B|x)* G(A|x) S0 x S A 0 B

  6. Outline • Motivation • Interferometry Theory • Numerical Examples: 3 Syn. Data • Conclusion

  7. FD Experiment 1500 0 Depth (m) Time (s) Reflection wavefield 3500 3 Offset (m) 1000 Depth (m) 3500 0 1500

  8. Reduced Form GSM Ray tracing of line source (picked direct wave) Reduce form GSM result 1500 ? Depth (m) 3500 0 Offset (m) 1000 0 Offset (m) 1000

  9. Reduced Form GSM Ray tracing of line source (picked direct wave) Reduce form GSM result 1500 Lesson: Super-resolution ? Depth (m) 3500 0 Offset (m) 1000 0 Offset (m) 1000

  10. Synthetic Experiment(He, 2006) 0 10 shots Depth (m) Overburden 94 geophones 5500 0 km 7 km Offset (m)

  11. A Shot Gather 0 s 5 s 2 km 6.5 km

  12. WEIM Result (one shot) 2700 Depth (m) Artifacts 5500 0 1700 Offset (m)

  13. Tricks: Filter down and up going waves: m(x) = U(x)/D(x) Lesson: Fltering+extra stacking reduces artifacts WEIM Result (ten shots) 2700 Depth (m) 5500 0 1700 Offset (m)

  14. Outline • Motivation • Interferometry Theory • Numerical Examples: GOM Data • Conclusion

  15. 120 shots ? 98 geophones Poor image of flank by standard migration VSP Salt Flank Imaging (BP Hornby et al, 2006) Overburden

  16. VSP Data 3.2 s 0 2000 ft 7.2 s

  17. Interferometric Migration Result 0 2000 ft

  18. VSP->SWP Summary ! 1. Redatum sources below overburden 2. Local VSP migration 3. Kills Source Statics and no need to know src location or excitation time 4. Super-resolution 5. Instead of redatuming receivers to surface, we redatum sources to depth.

  19. X (m) 1000 1400 950 Depth (m) 1950

  20. Main Parameters in VSP: • Source number: 100 • Shot interval: 10 m • Receiver number: 91 • Receiver interval: 10 m • Depth of the first receiver: 950 m • Depth of the last receiver: 1850 m • Temporal interval: 0.001 s

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