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Joint Migration of Primary and Multiple Reflections in RVSP Data

Joint Migration of Primary and Multiple Reflections in RVSP Data. Jianhua Yu, Gerard T. Schuster University of Utah. Real ?. Ghost ?. Drill-bit Primary Autocorrelogram Migration. SP. 1255. 1215. 1235. 1.0. Drill Hole. Time (s). 2.0. 3.0. Motivation. Outline.

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Joint Migration of Primary and Multiple Reflections in RVSP Data

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

  2. Real ? Ghost? Drill-bit Primary Autocorrelogram Migration SP 1255 1215 1235 1.0 Drill Hole Time (s) 2.0 3.0

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

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

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

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

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

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

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

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

  12. Primary migration Ghost migration Final migration image What is Joint 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: Autocorrelating Trace g s x

  16. Primary Autocorrelogram Imaging Condition: g s x

  17. Primary Autocorrelogram Imaging Condition: g s x

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

  19. Ghost Autocorrelogram Imaging Condition: g s x

  20. Ghost Autocorrelogram Imaging Condition: g s x

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

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

  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 X (m) 0 4 0 V1 V2 Depth (m) V3 V4 V5 V6 3

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

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

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

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

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

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

  32. Acquisition Survey East (kft) 0 4.5 0 Drill bit North (kft) Well Rig 3C Receivers -5 0 Depth (kft) 10

  33. 9188 ft Main Acquisition Parameters East (kft) 0 4.5 0 Offset=1135-4740 ft North (kft) Well Rig -5 0 Depth (kft) Recording Length: 20 s Sample Interval: 2 ms 10

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

  35. Autocorrelograms of CSG 96 1 10 1 10 1 10 0 Time (s) 4 12 s 16 s 8 s

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

  37. Line AC4 Acquisition Survey Map Well Rig 0 North (ft) Drill bit 3C Receivers -5000 0 1500 3000 4500 East (ft)

  38. Joint Migration ( insert) and CDP Section SP 1255 1215 1235 1.0 Drill hole Time (s) 2.0 3.0

  39. Primary Migration ( insert) and CDP Section SP 1255 1215 1235 1.0 Drill hole Time (s) 2.0 3.0

  40. Joint Migration ( insert) and CDP Section SP 1255 1215 1235 1.0 Drilling hole Joint Time (s) 2.0 3.0

  41. Primary Migration ( insert) and CDP Section SP 1255 1215 1235 1.0 Drilling hole Primary Time (s) 2.0 3.0

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

  43. 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 Virtual Multiple ? Suppress coherent noise ? Amplitude fidelity ? NO YES YES SUMMARY

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

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