1. Specular-Ray Parameter Extraction and Stationary Phase Migration Jing Chen University of Utah

2. Outline Parameter Extraction Parameter Extraction Stationary Phase Migration Stationary Phase Migration Conclusions Conclusions

3. Parameter Extraction Extract specular-ray related parameters from prestack migration SG R

4. Why Specular-Ray Parameters Needed ? Prestack Depth Migration Prestack Depth Migration Traveltime Inversion Traveltime Inversion Tomographic MVA Tomographic MVA AVO AVO Etc... Etc...

5. Prestack Migration Operator ImageWeightDataAperture

6. Stationary Phase Approximation

7. Weighted Prestack Migration Operator ImageWeightDataAperture Parameter

8. Stationary Phase Approximation

9. Specular-Ray Related Parameters

10. R Source Receiver Midpoint Traveltime Reflector Normal Departure Angle Emergence Angle Incidence Angle

11. Parameter Extraction Synthetic Data Examples: Migrate a COG; Migrate a COG; Extract Midpoint Coordinates, Extract Midpoint Coordinates, Traveltimes, and Incidence Angles. Traveltimes, and Incidence Angles.

12. Kirchhoff Migration of a COG Distance (km) Depth (km) 4 2 0 1680 1 3 412

13. Weighted Kirchhoff Migration of a COG Distance (km) Depth (km) 4 2 0 1680 1 3 412 Extra Weight

14. Division of Two COG Images =

15. COG Incidence Angles 0 10 20 (Degrees ) Distance (km) Depth (km) 4 2 0 1680

16. COG Incidence Angles 0 10 20 Distance (km) Depth (km) 4 2 0 1680 (Degrees )

17. COG Traveltimes 0 3.5 (Seconds) Distance (km) Depth (km) 4 2 0 1680 1.75

18. COG Traveltimes 0 3.5 Distance (km) Depth (km) 4 2 0 1680 1.75 (Seconds)

19. COG S-R Midpoint Coordinates 0 20 (km) Distance (km) Depth (km) 4 2 0 1680 10

20. COG S-R Midpoint Coordinates 0 20 Distance (km) Depth (km) 4 2 0 1680 10 (km)

21. Verification of Extracted Parameters Distance (km) Depth (km) 4 2 0 1680 1 3 412

22. COG S-R Midpoint Coordinates 0 20 Distance (km) Depth (km) 4 2 0 1680 10 (km)

23. COG Traveltimes 0 3.5 Distance (km) Depth (km) 4 2 0 1680 1.75 (Seconds)

24. Verification of Extracted Parameters Trace Midpoint Coordinates Time (sec) 2 1 151311 Trvaeltimes Extracted

25. Applications Stationary Phase Migration Stationary Phase Migration

26. Stationary Phase Migration Migrate traces within Fresnel zone Migrate traces within Fresnel zone Reject traces out of Fresnel zone Reject traces out of Fresnel zone Suppress alias artifacts Suppress alias artifacts SPM uses specular-ray parameters to :

27. Stationary Phase Migration Algorithm Algorithm Synthetic Data Example Synthetic Data Example Field Data Example Field Data Example

28. Stationary Phase Migration Operator Minimum Aperture Fresnel zone width Stationary phase point Fresnel Zone Schleicher et al. (1997) :

29. Stationary Phase Migration Algorithm Algorithm Synthetic Data Example Synthetic Data Example Field Data Example Field Data Example

30. Kirchhoff Migration of a COG Distance (km) Depth (km) 4 2 0 1680 1 3 412

31. Stationary Phase Mig. of a COG 4 2 0 1680 1 3 412 Distance (km) Depth (km)

32. Migration Operator Trace Contributions

33. Trace Contributions : KM Trace Number Depth (km) 4 2 0 3001500

34. Trace Contributions : SPM Trace Number Depth (km) 4 2 0 3001500

35. Stationary Phase Migration Algorithm Algorithm Synthetic Data Example Synthetic Data Example Field Data Example Field Data Example

36. Kirchhoff Migration of a COG Distance (km) Depth (km) 6 4 0 1460 2 2124810

37. Stationary Phase Mig. of a COG Distance (km) Depth (km) 6 4 0 1460 2 2124810

38. Stacked KM Image Distance (km) Depth (km) 6 4 0 1460 2 2124810

39. Stacked SPM Image Distance (km) Depth (km) 6 4 0 1460 2 2124810

40. Conclusions Specular-ray related parameters can be accurately estimated from presatck migration Specular-ray related parameters can be accurately estimated from presatck migration SPM suppresses alias artifacts and improves horizon continuity SPM suppresses alias artifacts and improves horizon continuity

41. Acknowledgements I thank the 1999 UTAM sponsors for their supports. I thank the 1999 UTAM sponsors for their supports.