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REVERSE -TIME DATUMING

REVERSE -TIME DATUMING. M. Zhou Y. Luo (Saudi Aramco). Geology and Geophysics Department University of Utah. Outline. Objective How to Implement Examples Conclusions. Accurate. RTM. Expensive. +. Approx. Phase-shift Kirchhoff. Efficient. Objective. Offset (km).

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REVERSE -TIME DATUMING

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  1. REVERSE -TIME DATUMING M. Zhou Y. Luo (Saudi Aramco) Geology and Geophysics Department University of Utah

  2. Outline • Objective • How to Implement • Examples • Conclusions

  3. Accurate RTM Expensive + Approx. Phase-shift Kirchhoff Efficient Objective Offset (km) Complex Rough topography Large velocity variation RTD Depth (Km) Less Complex

  4. Outline • Objective • How to Implement • Examples • Conclusions

  5. Implement RTD d(s|x’’) d(s|x’’) d(s|r) g*(r|x’’) d(s|r) d(s|x’’)= d(x’|x’’) S R Depth d(x’|x’’)=g*(s|x’) d(s|x”) x’’ x’ Distance

  6. Implement RTD d(x’|x’’) = g(r|x’’) d(s|r) * = d(x’|x’’) d(s|r) S R g(s|x’) Depth x’’ x’ Target-oriented RTD (Luo , 2002) Distance

  7. Outline • Objective • Implement • Examples • Conclusions 2-D Salt Model Pluto 1.5 (Smarrt Jv.)

  8. 2-D Salt Model Offset (km) Offset (km) 15 0 15 0 Depth(Km) 3 Velocity Model Zero-offset Data

  9. After Redatuming Offset (km) 15 0 Offset (km) 0 15 Depth (Km) 3 Velocity Model Zero-offset Data at datum

  10. 2D Salt Model Offset (km) 0 5 10 15 2 Depth (Km) 3

  11. KM Image After Redatuming Offset (km) 0 5 10 15 2 Depth (Km) 3

  12. KM Image After Redatuming KM Images Before Redatuming Offset (km) 0 5 10 15 2 Depth (Km) 3

  13. KM Image After Redatuming Whole Volume RTM Offset (km) 0 5 10 15 2 Depth (Km) 3

  14. CPU Time Comparison S1400, 2048MB memory KM before datuming 1 (3801 sec) 6.88 (26147 sec) RTD + KM 13.4 (50832 sec) Whole volume RTM:

  15. After Redatuming Offset (km) 15 0 Depth (Km) Offset (km) 0 15 3 Velocity Model Zero-offset Data at datum

  16. Model KM Image After Redatuming Offset (km) 0 5 10 15 3 Depth (Km) 3 KM

  17. KM Before and After Redatuming Offset (km) 0 5 10 15 3 KM Before Depth (Km) 3 KM After

  18. Whole volume RTM KM After Redatuming vs. RTM Offset (km) 0 5 10 15 3 Before Depth (Km) KM After Datum 3 Save 40% w.r.t whole volume RTM

  19. KM After Redatuming Offset (km) 0 5 10 15 3 Shallow Datum Depth (Km) Deep Datum 3

  20. Outline • Objective • Implement • Examples • Conclusions 2-D Salt Model Pluto 1.5 (Smarrt Jv.)

  21. SMARRT JV. Pluto 1.5 Vp model 0 Depth (Km) 9 0 30 Distance (km)

  22. Zero-offset Data 1 Time (Sec) 5 5 25 Distance (km)

  23. Reflectivity Model Below Datum Zero-offset Data After Datuming 0 5 Depth (Km) Time (Sec) 1 7 10 20 Distance (km)

  24. Outline • Objective • How to Implement • Examples • Conclusions

  25. Conclusions • RTD is faster than RTM • RTD helps reveal deeper structure • RTD + KM is cost efficient and provides good depth image

  26. Conclusions • RTD introduces artifacts due to • data boundary

  27. 2000 ms 10 km Courtesy of Yi Luo (Saudi Aramco)

  28. Acknowledgements We thank Utah Tomography and Modeling/Migration Consortium sponsors for their financial support

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