1. The Earth’s Near Surface as a Vibroseis Signal Generator Zhiyong Jiang University of Utah

2. Outline Introduction Introduction Methodology Methodology Synthetic Data Test Synthetic Data Test Conclusions Conclusions

3. g s x Motivation: in Indonesia gas hydrates blur the reflections s’

4. Outline Introduction Introduction Methodology Methodology Synthetic Data Test Synthetic Data Test Conclusions Conclusions

5. Review: 1st-order Multiple Imaging with Crosscorrelation Migration g s X s’

6. g s X s’

7. Review: Near Surface Scattering Decon. gs X s’

8. gs X s’

9. g s x s’ EAV

10. g s x s’ EAV

11. g s x s’ Why name it “EAV” (Earth as a vibroseis signal generator) Pilot signal Vibroseis trace

12. Outline Introduction Introduction Methodology Methodology Synthetic Data Test Synthetic Data Test Conclusions Conclusions

13. Velocity Model 6750 0 X (m) 0 2000 Depth (m) Shots: 676; Receivers: 50 (1100m -1600m)

14. Time (s) 6 0 1180m 1500m CSG 333 1180m 1500m Upgoing component S G X 1180m 1500m Downgoing component S G X

15. CRG 33 Time (s) 6 0 67500 X (m) Early part (pilot signal) Late part (vibroseis trace)

16. EAV to Upgoing Component 67500 X (m) 0 2000 Depth (m) s g x g’

17. EAV to Downgoing Component 0 X (m) 0 2000 Depth (m) 6750 s x g g’

18. Primary Migration Image 0 0 2000 Depth (m) X (m) 6750 s g x

19. 1 st -order Multiple with Crosscorrelation Migration 0 0 2000 Depth (m) X (m) 6750 s g g’ x

20. EAV to Downgoing Component 0 X (m) 0 2000 Depth (m) 6750 s x g g’

21. Outline Introduction Introduction Methodology Methodology Synthetic Data Test Synthetic Data Test Conclusions Conclusions

22. Conclusion Free surface points can be regarded as vibroseis signal generator, and direct waves, primary reflections, multiple reflections can be regarded as the pilot signal, the response can be thought of as vibroseis trace Free surface points can be regarded as vibroseis signal generator, and direct waves, primary reflections, multiple reflections can be regarded as the pilot signal, the response can be thought of as vibroseis trace With EAV, a ringy trace can be compressed into an impulsive primary reflection With EAV, a ringy trace can be compressed into an impulsive primary reflection

23. s x s’ g Pilot signal vibroseis trace Future work: use EAV to deblur the scattering due to gas hydrates near the sea floor

24. We thank UTAM sponsors for their financial support Acknowledgments