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Specular Interferometric Migration of Free Surface Multiples in VSP Land Data

Specular Interferometric Migration of Free Surface Multiples in VSP Land Data. C. Boonyasiriwat and M. Zhou. Dept. of Geology & Geophysics University of Utah. Outline. Problem. Specular Interferometric Migration. Data Processing. Numerical Results. Conclusion. Problem.

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Specular Interferometric Migration of Free Surface Multiples in VSP Land Data

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  1. Specular Interferometric Migration of Free Surface Multiples in VSP Land Data C. Boonyasiriwat and M. Zhou Dept. of Geology & Geophysics University of Utah

  2. Outline • Problem • Specular Interferometric Migration • Data Processing • Numerical Results • Conclusion

  3. Problem • Interferometric migration is expensive • Specular interferometric migration is cheaper • Land data have problems with the weathering zones • Marine data have very strong multiples

  4. Outline • Problem • Specular Interferometric Migration • Data Processing • Numerical Results • Conclusion

  5. Specular reflection Diffraction time Specular time Specular Interferometric Migration s’ s* s g x

  6. Natural Time Calculated Time Natural Green’s Function Model-based Green’s Function Specular Interferometric Migration of first-order multiples Migration Equation:

  7. Specular Interferometric Migration: s g s* x Specular Interferometric Migration vsInterferometric Migration

  8. Interferometric Migration: Specular Interferometric Migration vsInterferometric Migration s s’ g x

  9. Specular Interferometric Migration: Interferometric Migration: Specular Interferometric Migration vsInterferometric Migration

  10. Outline • Specular Interferometric Migration • Data Processing • Numerical Results • Conclusion

  11. AGC Normalization Separate Upgoing Wave Kirchhoff Migration with Residual Statics Corrections Processing Steps for Primary Reflections Raw Data

  12. AGC Separate Downgoing Wave Specular Interferometric Migration with Residual Statics Corrections Processing Steps for Ghost Reflections Raw Data Normalization

  13. Outline • Specular Interferometric Migration • Data Processing • Numerical Results • Conclusion

  14. P-wave ghost S-wave ghosts Primaries + Ghosts from Elastic Wave Eq. Forward Modeling Results Primaries from Acous. Wave Eq. 0 Time (s) s g x 3.5 Offset (km) 4 Offset (km) 4 -4 -4

  15. P-wave ghost S-wave ghosts Comparison between Field and Synthetic Results Field Data Synthetic Data 0 Time (s) 3.5 Offset (km) 4 Offset (km) 4 -4 -4

  16. Residual Statics Correction Before statics correction After statics correction 0.2 Time (s) 2 Offset (km) 4 Offset (km) 4 -4 -4

  17. Kirchhoff Migration of Primaries 0 Depth (km) 5 Offset (km) 2 -2

  18. Specular Interferometric Migration of Ghosts 0 Depth (km) 5 Offset (km) 2 -2

  19. Primary migration result overlaid on the surface data

  20. Ghost migration result overlaid on the surface data

  21. Outline • Specular Interferometric Migration • Data Processing • Numerical Results • Conclusion

  22. Conclusions • VSP land data contain strong primaries compared to P- and S-wave multiples. • Migration image of ghosts has a wider subsurface coverage and flatter layers. • Migration image of primaries has a better S/N ratio for the P-wave image zone. • Both Kirchhoff and specular interferometric images correlate well with the CDP image. • Specular interferometric migration gives comparable results to the Kirchhoff migration.

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