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Robust Imaging for RVSP Data with Static Errors. Jianhua Yu University of Utah. Problems in RVSP imaging. How to eliminate the static errors in RVSP imaging. Synthetic and real data examples. Summary. Outline. Problems in RVSP imaging. Outline.
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Robust Imaging for RVSP Data with Static Errors Jianhua Yu University of Utah
Problems in RVSP imaging How to eliminate the static errors in RVSP imaging Synthetic and real data examples Summary Outline
Problems in RVSP imaging Outline How to eliminate the static errors in RVSP imaging Synthetic and real data examples Summary
Geophone Well RVSP Acquistion Geometry ?
Don’t know source wavelet Don’t know initial time Have limitation to deviated well Static shift error may exist Problems in RVSP imaging
(a) Primary reflection (solid line) (b) ghost reflection (solid line) Autocorrelogram Migration • Do not require source wavelet • Image conditions:
Migrated Image Autocorrelograms of seismic data Migration Formula:
Outline Problemsin RVSP imaging How to eliminate the static errors in RVSP imaging Synthetic and real data examples Summary
Outline Problemsin RVSP imaging How to eliminate the static errors in RVSP imaging Synthetic and real data examples Summary
25 geophones Well 98 sources RVSP and Geology Model 625 ft 250 Depth (ft) 1750
0.03 Depth (kft) 1 0.03 Depth (kft) 1 0 CRG 16 CRG 2 Time (s) 2.5
0.03 Depth (kft) 1 0.03 Depth (kft) 1 0 CRG 16 CRG 2 Time (s) 2.5
0.03 Depth (kft) 1 0.03 Depth (kft) 1 0 Time (s) Autocorr. CRG 16 Autocorr. CRG 2 2.0
Primary Kichhoff Migration No static errors With static errors 0 Depth (ft) 1750
Primary Autocorr. Migration No static errors With static errors 0 Depth (ft) 1750
Kirchhoff Autocorr. Mig 0 Depth (ft) 1750
Ghost Kirchhoff Migration No static errors With static errors 250 Depth (ft) 1500
Ghost Autocorr. Migration No static errors With static errors 250 Depth (ft) 1500
Kirchhoff Autocorr Mig (Ghost) 250 Depth (ft) 1500
Outline Problemsin RVSP imaging How to eliminate the static errors in RVSP imaging Synthetic and real data examples Summary
Depth (kft) Depth (kft) 1 0.03 1 0.03 0 CRG 6 CRG 15 Time (s) 0.35
Depth (kft) Depth (kft) 1 0.03 1 0.03 0 CRG 6: primary CRG 15: primary Time (s) 0.30
Depth (kft) Depth (kft) 1 0.03 1 0.03 0 Time (s) Autocorr. CRG 6: primary Autocorr. CRG 15: primary 0.30
Depth (kft) Depth (kft) 1 0.03 1 0.03 0 Time (s) Autocorr. CRG 6: ghost Autocorr. CRG 15: ghost 0.30
Kirchhoff Mig. with Primary 120 ft 150 Depth (ft) 1200
Well Log and Kirchhoff Migration 0 Depth (ft) 1000
Autocorr. Mig. with Primary 120 ft 150 Depth (ft) 1200
Well Log and Primary Autocorr. Mig 0 Depth (ft) 1000
Primary autocorrelogram migration gives better correlation with well log synthetic seismograms Kirchhoff Mig. Primary Auto. Mig. Well Mig Well Mig. 0 Depth (ft) 1000
Auto mig. with P+G 120 ft 150 Depth (ft) 1200
Well Log and Mig without Separating Primary and Ghost 0 Depth (ft) 1000
Joint mig. with P+G 120 ft 150 Depth (ft) 1200
Well log and Joint Mig. with Primary and Ghost 0 Depth (ft) 1000
Well Well Mig Mig Joint Mig. With P+G Mig. With P+G 0 Depth (ft) 1000
Outline Problemsin RVSP imaging How to eliminate the static errors in RVSP imaging Synthetic andreal data examples Summary
Summary • Autocorrelogram imaging condition is capable of suppressing static shift errors • It can be used to image reflectivity with static error-polluted VSP and drill-bit data where no pilot signal is available
Acknowledgments • Thank 2002 sponsors of UTAM consortium for the financial support • Thank Exxon for providing the real data