1. Imaging Multiple Reflections with Reverse- Time Migration Yue Wang University of Utah

2. Outline BackgroundBackground Motivation & ObjectiveMotivation & Objective MethodologyMethodology Numerical ExamplesNumerical Examples ConclusionsConclusions

3. Forward Process Distance (km) Depth (km) 1 0 04.5 * Source Geophone Line

4. Forward Process Distance (km) Depth (km) 1 0 04.5 *  obs

5. Reverse Time Migration Distance (km) Depth (km) 1 0 04.5  obs Extrapolated Wavefield  obs Reversed traces

6. Reverse-Time Migration Extrapolated Wavefield Imaging Condition Migration Section

7. Outline BackgroundBackground Motivation & ObjectiveMotivation & Objective MethodologyMethodology Numerical ExamplesNumerical Examples ConclusionsConclusions

8. Ocean-Bottom Survey Distance (km) Depth (km) 1 0 04.5 * Source Geophone Line

9. Problem Distance (km) Depth (km) 1 0 04.5 * Receiver-side Multiples

10. Synthetic Shot Gather Time (s) Distance (km) Receiver side multiples 2 0 0.93.6

11. Field Data Time (s) Distance (m) 4 0 -80 1900 Receiver side multiples

12. Time Migration Time (s) Distance (m) 4 0 -80 1900 Receiver side multiples

13. Objective Using both primary and multiple reflections for imaging by reverse- time migration.Using both primary and multiple reflections for imaging by reverse- time migration.

14. Outline BackgroundBackground Motivation & ObjectiveMotivation & Objective MethodologyMethodology Numerical ExamplesNumerical Examples ConclusionsConclusions

15. Ocean-Bottom Survey Distance (km) Depth (km) 1 0 04.5 * Source Geophone Line

16. Ocean-Bottom Survey Distance (km) Depth (km) 1 0 0 *PV Up-going

17. Multi-Component Data pressure + particle velocity ( P & V ) ocean-bottom survey

18. Reverse Time Migration Distance (km) Depth (km) 1 0 0PV Down-going PV ( P & V Scheme )

19. Reverse Time Migration Distance (km) Depth (km) 1 0 0VV ( Particle Velocity Only )

20. Key Idea Primary + Multiple Correct Positions P & V Scheme

21. Key Idea Primary + Multiple Incorrect Positions V-Only Scheme

22. Ocean-Bottom Survey Distance (km) Depth (km) 1 0 0 *PV Up-going Waves

23. P & V Scheme Distance (km) Depth (km) 1 0 0PVPV Correct Position Down-going waves

24. Particle Velocity Only Scheme Distance (km) Depth (km) 1 0 0VV Incorrect

25. Ocean-Bottom Survey Distance (km) Depth (km) 1 0 0 *PV Down-going waves ( Multiples )

26. P & V Scheme Distance (km) Depth (km) 1 0 0PVPV Correct Position Up-going waves

27. Particle Velocity Only Scheme Distance (km) Depth (km) 1 0 0VV Incorrect

28. Outline BackgroundBackground Motivation & ObjectiveMotivation & Objective MethodologyMethodology Numerical ExamplesNumerical Examples Salt Dome Model Salt Dome Model ConclusionsConclusions

29. Salt Model Distance (km) Depth (km) 2.7 0 04.5

30. Shot Gather Normal Stress VerticalHorizontal Time (s) Distance (km) 2 0 0.93.6 0.93.6 0.93.6 Multiples

31. Kirchhoff Migration Distance (km) Depth (km) 2.5 0 0.454.05

32. Kirchhoff Migration Distance (km) Depth (km) 2.5 0 0.454.05

33. Particle Velocity Only Scheme Distance (km) Depth (km) 2.7 0 0.454.05

34. Particle Velocity Only Scheme Distance (km) Depth (km) 2.7 0 0.454.05

35. P & V Scheme Distance (km) Depth (km) 2.5 0 0.454.05

36. Distance (km) Depth (km) 2.5 0 0.454.05 P & V Scheme

37. Primary + Multiple Correct Positions Conclusion P + V RTM

38. Future Work: Field Data Test Time (s) Distance (m) 40-80 1900 Receiver side multiples

39. Acknowledgement We are grateful to the 1999 sponsors of the UTAM consortium for the financial support

40. Outline BackgroundBackground Motivation & ObjectiveMotivation & Objective MethodologyMethodology Numerical ExamplesNumerical Examples Plane-wave example Plane-wave example ConclusionsConclusions

41. Forward Process Distance Depth Up-going waves

42. P & V Scheme Distance Depth Down-going waves

43. P & V Scheme Time (s) Depth (km) 0 0.8 0 1.2 Down-going waves

44. Particle Velocity Only Scheme Distance Depth Down-going waves Up-going waves

45. Particle Velocity Only Scheme Time (s) Depth (km) 0 0.8 0 1.2 Down-going waves Up-going waves

46. P + V RTM Distance (km) Depth (km) 100 P+V Up-going waves Correct Position Distance (km) Depth (km) 1 0 0 P Down-going waves Up-going waves