1. Moveout Correction and Migration of Surface-related Resonant Multiples Bowen Guo*,1, Yunsong Huang 2 and Gerard Schuster 1 1 King Abdullah University of Science and Technology 2 CGG

2. Outline  Conclusions and future work  Introduction and motivation  Theory and workflow  Numerical results

3. Introduction  What is a surface-related resonant multiple ? Free surface Reflector Raypaths overlap

4. Introduction  Why migrate resonant multiples ? Super-resolution Case 1: migrate primary reflections Where did this come from ? t

5. Motivation  Why migrate resonant multiples ? Super-resolution Where did this come from ? Case 2: migrate resonant multiples t

6.  Super-resolution by migrating resonant multiples  Problem Only received by near-offset traces low SNR Motivation Free surface Reflector Free surface Reflector Multiple Image Primary Image X (km) Schuster and Huang (2014) 0.69 0.85 33.536.5 33.5 36.5

7.  Problem: Low SNR X (km) 1.5 6.0 0 30 COG offset=107 m  Solution: Step 1: CMP moveout correction. Step 2: Stacking to improve SNR. t offset CMP t offset CMP Pre-resonant multiples Resonant multiples Before stacking After stacking Resonant multiple Primary reflection Motivation

8.  Introduction and motivation  Theory  Numerical results  Conclusions and future work Outline

9. Theory: Pre-resonant Multiples Free surface Reflector 1 Reflector 2 Multiples from dissimilar interface Pre-resonant multiples from similar interface

10. Free surface Reflector h Resonant multiples Theory: Moveout Correction  Moveout correction based on moveout formla Free surface Reflector Pre-resonant multiples Valid for homogeneous velocity model

11. Theory: Moveout Correction Free surface Reflector  Moveout correction based on Fermat’s principle Valid for heterogeneous velocity model

12. Theory: Migration of Resonant Multiples  Migration of post-stack resonant multiples Free surface Primary Reflection Migration Image Horizontal distance Depth Resonant Multiple Migration Image Horizontal distance Depth

13. Work Flow CMP Moveout Correction for Non-zero Offset Traces Stack into zero-offset Migration of post-stack resonant multiples t x ZOG t x Post-stack ZOG z x Image t offset CMP 0 t offset CMP 0

14.  Introduction and motivation  Theory  Numerical results  Conclusions and future work Outline

15. Synthetic result of moveout Correction X (m) 0 0 700 0 0 1400 2000 m/s 3000 m/s Velocity Offset (m) 0.0 -700 700 1.5 CMP Offset (m) 0.0 -700 700 1.5 After Moveout Correction Offset (m) 0.0 -1000 1000 1.5 After Moveout Correction Offset (m) 0.0 1000 1.5 -1000 CMP X (m) 0 0 1000 0 0 2000 2000 m/s 3000 m/s Velocity

16. Synthetic Result: Point Scatterers Data generated by Kirchhoff modeling and migrated by Kirchhoff migration Z (km) x (km) 0.64 2.08 11.612.4 11.612.4 Primary Image Resonance Image

17. Field Data Example X (km) 0 30 1.5 6.0 COG = 107 m Resonant multiple Primary reflection Zoom in

18. Field Data: Zoom-in of COG X (km) 0 30 3.3 6.0 Dissimilar multiples Before After h 1 CMP 0.0 6.0 0.1 5.0 5.0(km) h 2 0.0 6.0 0.1 h 5.0 5.0(km) h CMP 3 0.0 6.0 0.1 h 5.0 5.0(km) h Top of Salt

19. X (km) 2.0 0 30 Primary Reflection Image 0.0 Multiple Image X (km) 0 30 Post-stack Multiple Image Field Data: Migration Image Higher-resolution top of the salt False reflectors from dissimilar multiples

20. Field Data 2: Sonar Data Processsed 120 kHz data 0 80 160 0370 x (m) t (ms) Primary reflection Resonant multiple Processsed 200 kHz data 0370 x (m) Primary reflection

21. Migration Image of the Sea Bottom Image from 120 kHz Primary Reflections 0 60 0 270 x (m) Z (m) Image from 120 kHz Resonant Multiples 0 60 Z (m) Image from 200 kHz Primary Reflections Image from 120 kHz Resonant Multiples

22.  Introduction and motivation  Theory  Numerical results  Conclusions and future work Outline

23. Conclusions  Resonant multiples give super-resolution  Pre-resonant multiples resonant multiples  Alignment and stacking improve SNR 0.0 6.0 0.15.0 h (km) CMP 0.0 6.0 0.15.0 h (km) CMP

24. Limitations and Future Research  Multiples suffer more from attenuation than primaries  Inaccurate moveout correction blur the stacked resonant multiples  Multiples from dissimilar reflectors cause artifacts

25. Acknowledgement We would like to thank King Abdullah University of Science and Technology for their support Thank you for your attention

26. Thank you !