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Seismic interferometry: a comparison of approaches

Seismic interferometry: a comparison of approaches. Kees Wapenaar Deyan Draganov Joost van der Neut Jan Thorbecke Delft University of Technology. Contents. Essentials of seismic interferometry Interferometry with multiple sources Interferometry with multiple receivers

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Seismic interferometry: a comparison of approaches

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  1. Seismic interferometry:a comparison of approaches Kees Wapenaar Deyan Draganov Joost van der Neut Jan Thorbecke Delft University of Technology

  2. Contents • Essentials of seismic interferometry • Interferometry with multiple sources • Interferometry with multiple receivers • Interferometry with multiple scatterers

  3. Contents • Essentials of seismic interferometry • Interferometry with multiple sources • Interferometry with multiple receivers • Interferometry with multiple scatterers

  4. Cross-correlation

  5. Cross-correlation Cross-correlation result is equal to impulsive reflection response

  6. Cross-correlation

  7. Simplifying assumptions: • Direct arrival at xA correlated with primary at xB • Single diffractor • Primaries only • xA is the specular reflection point

  8. Contents • Essentials of seismic interferometry • Interferometry with multiple sources • Interferometry with multiple receivers • Interferometry with multiple scatterers

  9. Simplifying assumptions: • Direct arrival at xA correlated with primary at xB • Single diffractor • Primaries only • xA is the specular reflection point

  10. Simplifying assumptions: • Direct arrival at xA correlated with primary at xB • Single diffractor • Primaries only • xA is the specular reflection point

  11. Cross-correlation

  12. Timing error

  13. Timing error

  14. Simplifying assumptions: • Direct arrival at xA correlated with primary at xB • Single diffractor • Primaries only • xA is the specular reflection point

  15. Simplifying assumptions: • Direct arrival at xA correlated with primary at xB • Single diffractor • Primaries only • Responses of many independent sources available

  16. Simplifying assumptions: • Direct arrival at xA correlated with primary at xB • Single diffractor • Primaries only • Responses of many independent sources available

  17. Simplifying assumptions: • Direct arrival at xA correlated with primary at xB • Single diffractor • Primaries only • Responses of many independent sources available

  18. SEG 2002, Theory of acoustic daylight imaging revisited, p 2269-2272

  19. Simplifying assumptions: • Direct arrival at xA correlated with primary at xB • Single diffractor • Primaries only • Responses of many independent sources available

  20. Assume mutually uncorrelated sources

  21. SEG 2002, Theory of acoustic daylight imaging revisited, p 2269-2272

  22. 1500 m/s 2000 m/s

  23. Conclusions for interferometry with multiple sources • Reconstruction of reflection response • Arbitrary medium • Primaries and multiples • Requires many sources that are mutually uncorrelated

  24. Contents • Essentials of seismic interferometry • Interferometry with multiple sources • Interferometry with multiple receivers • Interferometry with multiple scatterers

  25. Cross-correlation

  26. Simplifying assumptions: • Direct arrival at xA correlated with primary at xB • Single diffractor • Primaries only • xA is the specular reflection point

  27. Cross-correlation per receiver, followed by sum over receivers gives Position of specular reflection point is different for each diffractor, which makes this approach useless However …..

  28. 0 t • Combine with downward extrapolation • and imaging • Forward extrapolation of ‘source’ • Inverse extrapolation of receiver • Cross-correlation

  29. 0 t

  30. 0 t

  31. Ghost • Forward extrapolation of ‘source’ • Inverse extrapolation of receiver • Cross-correlation • Integrate along receivers • Repeat for all subsurface points

  32. Schuster, EAGE, 2001 • Artman et al., EAGE 2004 • Draganov et al., SEG 2004, Wednesday afternoon, • Poster presentation Mig P3.4

  33. Conclusions for interferometry with multiple receivers • No reconstruction of reflection response possible. • Instead: imaging of subsurface reflectors • Arbitrary medium • Primaries only • Hence, multiples are imaged as ghosts • Requires small number of sources

  34. Contents • Essentials of seismic interferometry • Interferometry with multiple sources • Interferometry with multiple receivers • Interferometry with multiple scatterers

  35. Diffuse wavefield: Weaver and Lobkis, 2001, Phys. Rev. Lett. 87

  36. Conclusions for interferometry with multiple scatterers • Reconstruction of reflection response • (Green’s function) • Random medium • Primaries and multiples • Requires small number of sources

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