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

Outline Introduction Introduction Methodology Methodology Synthetic Data Test Synthetic Data Test Conclusions Conclusions

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

Outline Introduction Introduction Methodology Methodology Synthetic Data Test Synthetic Data Test Conclusions Conclusions

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

g s X s’

Review: Near Surface Scattering Decon. gs X s’

gs X s’

g s x s’ EAV

g s x s’ EAV

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

Outline Introduction Introduction Methodology Methodology Synthetic Data Test Synthetic Data Test Conclusions Conclusions

Velocity Model X (m) Depth (m) Shots: 676; Receivers: 50 (1100m -1600m)

Time (s) m 1500m CSG m 1500m Upgoing component S G X 1180m 1500m Downgoing component S G X

CRG 33 Time (s) X (m) Early part (pilot signal) Late part (vibroseis trace)

EAV to Upgoing Component X (m) Depth (m) s g x g’

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

Primary Migration Image Depth (m) X (m) 6750 s g x

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

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

Outline Introduction Introduction Methodology Methodology Synthetic Data Test Synthetic Data Test Conclusions Conclusions

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

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

We thank UTAM sponsors for their financial support Acknowledgments