1. Primary-Only Imaging Condition Yue Wang

2. Outline Objective Objective POIC Methodology POIC Methodology Synthetic Data Tests Synthetic Data Tests 5-layer model 5-layer model salt dome model salt dome model Unocal Field Data Tests Unocal Field Data Tests Discussion and Future Work Discussion and Future Work

3. Synthetic Shot Gather Distance (m) Time (s) 0 4 0 3000 Multiples Primary

4. 2D Kirchhoff migration * ^ Source Receiver  obs  obs =  SA +  RA  SA  RA

5. Kirchhoff Migration Image Artificial Multiple Image Distance (km) Depth (km) 0 6 0 5

6. Problem Standard imaging condition Standard imaging condition Data Data ( primary + multiple ) Image

7. Objective Primary-Only imaging condition Data Data ( primary + multiple ) Image

8. Outline Objective Objective POIC Methodology POIC Methodology Synthetic Data Tests Synthetic Data Tests 5-layer model 5-layer model salt dome model salt dome model Unocal Field Data Tests Unocal Field Data Tests Discussion and Future Work Discussion and Future Work

9. MethodologyData Primary Multiple = + First-order Multiple Second-order Multiple Third-order Multiple

10. Methodology Primary ---------------- Multiple ? What Differences What Differences

11. Primary Reflections Offset Depth * ^ Source Receiver A

12. Multiple Reflections Offset Depth * ^ Source Receiver A C B

13. Methodology For a specific event: Observed traveltime  obs Observed traveltime  obs shooting angle  shooting angle  incident angle  incident angle 

14. Shoot ray from source Offset Depth * ^ Source Receiver 

15. Offset Depth * ^ Source Receiver  Shoot ray from receiver

16. Find crossing point Offset Depth * ^ Source Receiver Cross point A  SA  RA  

17. Primary-Only Imaging Condition (POIC) One event is primary reflection only if :  obs =  SA +  RA  obs =  SA +  RA

18. Multiple Reflections Offset Depth * ^ Source Receiver A  SA  RA  

19. Multiple Reflections  obs =  SA +  RA  obs =  SA +  RA

20. Methodology Data Data ( primary + multiple ) Standard Imaging Condition  obs Image ( primary + multiple ) Primary Only Imaging Condition  obs,  and  Image ( primary + multiple )

21. Outline Objective Objective POIC Methodology POIC Methodology Synthetic Data Tests Synthetic Data Tests 5-layer model 5-layer model salt dome model salt dome model Unocal Field Data Tests Unocal Field Data Tests Discussion and Future Work Discussion and Future Work

22. 5-Layer Model Distance (km) Depth (km) 0 6 0 5 * Source Geophone Line

23. Shot Gather Distance (m) Time (s) 0 4 0 3000 P1 P2 P3 P4

24. Kirchhoff Migration Image 1 2 3 4 Distance (km) Depth (km) 0 6 0 5

25. Kirchhoff Migration Image Artificial Multiple Image Distance (km) Depth (km) 0 6 0 5

26. Migration Image with POIC 1 2 3 4 Distance (km) Depth (km) 0 6 0 5

27. Outline Objective Objective POIC Methodology POIC Methodology Synthetic Data Tests Synthetic Data Tests 5-layer model 5-layer model salt dome model salt dome model Unocal Field Data Tests Unocal Field Data Tests Discussion and Future Work Discussion and Future Work

28. Salt Model Distance (km) Depth (km) 0 3.5 0 5 * Source Geophone Line

29. Shot Gather Distance (m) Time (s) 0 4 0 3000

30. Kirchhoff Migration Image 1 2 3 4 5 6 6 A.M.I. Distance (km) Depth (km) 0 3.5 05 A.M.I.

31. Migration Image with POIC 1 2 3 4 5 6 6 Distance (km) Depth (km) 0 3.5 05

32. Outline Objective Objective POIC Methodology POIC Methodology Synthetic Data Tests Synthetic Data Tests 5-layer model 5-layer model salt dome model salt dome model Unocal Field Data Tests Unocal Field Data Tests Discussion and Future Work Discussion and Future Work

33. Processed CSG Distance (m) Time (s) 0 4 175 3175 M1 M2

34. NMO Corrected CMG Distance (m) Time (s) 0 6 1753175 M2

35. CMG after Dip Filtering CMG after Dip Filtering Distance (m) Time (s) 0 6 1753175 M2

36. Seismogram in  -p Domain Seismogram in  -p Domain p Time (s) 0 6 -200400 Multiple Primary

37. Muting in  -p Domain Muting in  -p Domain p Time (s) 0 6 -200400

38. CMG after Muting in  -p CMG after Muting in  -p Distance (m) Time (s) 0 6 1753175 M2

39. Stack before Muting Time (s) 0 4 M1 CDP Number 313 1400 M2

40. Stack after Muting Time (s) 0 M2 CDP Number 4 313 1400

41. Kirchhoff Image Depth (m) 0 4000 M1 M2 Distance (m) 2000 9000

42. POIC Image Depth (ft) 0 4000 M1 M2 Distance (m) 2000 9000

43. Conclusions POIC Works for synthetic data POIC Works for synthetic data Encouraging results for field data Encouraging results for field data POIC need more accurate velocity model POIC need more accurate velocity model

44. Future Work Apply to other field data Apply to other field data Improve velocity model estimate Improve velocity model estimate

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

46. Migration with POIC Four Steps: (1) pick seismic events automatically;  obs  obs

47. Migration with POIC Four Steps: (2) calculate incidence and shooting angles  and  for one event using local slant stack;

48. Migration with POIC Four Steps: (3) ray tracing and find the crossing point;  SA +  RA  SA +  RA

49. Find crossing point Offset Depth * ^ Source Receiver Cross point A  SA  RA  

50. (4)  obs =  SA +  RA ? No: Discard this event; No: Discard this event; Yes: Migrate this event; Yes: Migrate this event; Migration with POIC

51. Raw CSG Distance (m) Time (s) 0 4 175 3175

52. CMG Offset (m) Time (s) 0 6 1753175 M1 M2