1. Joint Migration of Primary and Multiple Reflections in RVSP Data Jianhua Yu, Gerard T. Schuster University of Utah

2. 3.0 2.0 1.0 Time (s) SP1255 1235 1215 Drill-bit Primary Autocorrelogram Migration Drill Hole Real ? Ghost ?

3. Outline Motivation Joint Migration Method Examples Synthetic data UPRC data Summary

4. Outline Motivation Joint Migration Method Examples Synthetic data UPRC data Summary

5. Source Geophone ? RVSP While Drilling Provide Look-ahead Image Below the Drill Bit Reduce Uncertainty in Drilling

6. Source Geophone Bit Position? Problems in RVSPWD Pilot signal? Wavelet ?

7. Problems with Drill-bit and RVSP Data No source wavelet No source initiation time Not easy to get pilot signal in deviated well Not easy to get pilot signal in deviated well and horizontal well

8. Static shift errors may exist Difficulty for separating primary and ghost waves from deviated or horizontal well Problems with Drill-bit and RVSP Data

9. Solution Autocorrelogram Migration Why do we use autocorrelation of seismic data rather than the seismogram ???

10. Strengths of Autocorrelogram Migration No need to know initial time No limits to deviated well Be able to reduce static errors No need to know source wavelet

11. Well Drill bit Receiver Primary Direct Wave Ghost What is Joint Migration

12. Final migration image Ghost migration Primary migration Seismic Data

13. Joint Migration using Primary and Ghost Reflections Do not need to separate primary and ghost waves Attenuate the interferences in migration image What is Benefit from Joint Migration

14. Outline Motivation Joint Migration Method Examples Synthetic data UPRC data Summary

15. Primary Autocorrelogram Imaging Condition: x g s Autocorrelating Trace

16. Primary Autocorrelogram Imaging Condition: x g s

17. x g s

18. x g s Ghost Autocorrelogram Imaging Condition Ghost Autocorrelogram Imaging Condition: Autocorrelating Trace

19. x g s Ghost Autocorrelogram Imaging Condition Ghost Autocorrelogram Imaging Condition:

20. x g s

21. Principle of Joint Migration Seismic data: Primary + Ghost Ghost migrationPrimary migration Final migration image Product

22. Procedure of Joint Migration Pre-processing raw data Autocorrelating seismic traces: Migrating traces using both primary Mp and ghost imaging conditions Migrating traces using both primary Mp and ghost imaging conditions Mg Weighting primary image Calculating weight by w= Mp*Mg

23. Outline Motivation Joint Migration Method Examples Synthetic data UPRC data Summary

24. Outline Motivation Joint Migration Method Examples Synthetic data UPRC data Summary

25. Horizontal Well Model 0 Depth (m) 3 40 X (m) V1 V2 V4 V3 V5 V6

26. Shot Gather 1 200 0 4 Time (s) CSG 10 1 200 0 4 Time (s) Traces Autocorrelogram

27. 1.6 2.1 0 2.5 Depth (km) X (km) 1.6 2.1 X (km) Standard migration Joint migration Standard Migration with Joint Migration (3 CSGs) Source

28. 1.6 2.1 0 2.0 Time (s) X (km) 1.6 2.1 X (km) With only primaryJoint auto. migration Time Migration Results (39 CSGs) Source X (km)

29. 1.6 2.1 0 2.5 Depth (km) X (km) 1.6 2.1 X (km) Kirchhoff migAuto. mig Depth Migration With Static Errors Source 3 CSGs

30. 1.6 2.1 0 2.5 Depth (km) X (km) 1.6 2.1 X (km) Joint Kirchhoff mig Joint auto. mig Depth Migration With Static Errors Source 39 CSGs

31. Outline Motivation Joint Migration Method Examples Synthetic data UPRC data Summary

32. Acquisition Survey 0 04.5 -5 East (kft) North (kft) Well Rig 3C Receivers Drill bit 10 Depth (kft) 0

33. Recording Length: 20 s Sample Interval: 2 ms 0 04.5 -5 East (kft) North (kft) Well Rig 10 Depth (kft) 0 9188 ft Offset=1135-4740 ft Main Acquisition Parameters

34. Main Processing Steps Trace editing and static shift Trace editing and static shift Frequency panel analysis and noise elimination Frequency panel analysis and noise elimination Velocity analysis Velocity analysis Amplitude balance and energy normalization Autocorrelograms, vertical stacking utocorelograms Joint migrating autocorelograms

35. Autocorrelograms of CSG 96 1 10 0 4 Time (s) 1 10 8 s 12 s16 s

36. 1 0.0 3.3 Time (s) 50 Joint Migration Images Traces

37. Acquisition Survey Map Well Rig 3C Receivers Drill bit 0 0 150030004500 -5000 East (ft) North (ft) C Line AC4

38. 3.0 2.0 1.0 Time (s) SP1255 1235 1215 Drill hole Joint Migration ( insert) and CDP Section

39. 3.0 2.0 1.0 Time (s) SP1255 1235 1215 Primary Migration ( insert) and CDP Section Drill hole

40. 3.0 2.0 1.0 Time (s) SP1255 1235 1215 Drilling hole Joint Migration ( insert) and CDP Section Joint

41. 3.0 2.0 1.0 Time (s) SP1255 1235 1215 Primary Migration ( insert) and CDP Section Drilling hole Primary

42. Outline Motivation Joint Migration Method Examples Synthetic data UPRC data Summary

43. SUMMARY Need separating primary and multiple? NO Work for deviated or horizontal well ? YES Reduce the influence of static errors ? YES Need pilot signal ? NO Need source wavelet and initial time ? NO Suppress coherent noise ? YES Amplitude fidelity ? NO Virtual Multiple ? YES

44. Acknowledgments I greatly appreciate Union Pacific Resources Corporation for providing this dataI greatly appreciate Union Pacific Resources Corporation for providing this data I thank the sponsors of the UTAM consortium for financial supportI thank the sponsors of the UTAM consortium for financial support