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Brad Artman

Brad Artman. undergraduate: Colorado School of Mines, Geophysical Engineer graduate: Stanford University, Ph.D. candidate work experience: Western Atlas Logging Services, Junior Engineer U.S. Geological Survey, Visiting Scientist

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Brad Artman

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  1. Brad Artman • undergraduate: Colorado School of Mines, Geophysical Engineer • graduate: Stanford University, Ph.D. candidate • work experience: • Western Atlas Logging Services, Junior Engineer • U.S. Geological Survey, Visiting Scientist • Shell Deepwater Development Inc., Petrophysicist & Exploration Geophysicist

  2. passive seismic imaging at Valhall Brad Artman, Stanford Exploration Project –Advanced imaging team Monday, September 27

  3. multiple modeling in the image-space Brad Artman, Stanford Exploration Project –Advanced Imaging Team Ken Matson, Advanced Imaging Team Monday, September 27

  4. passive seismic imaging at Valhall Brad Artman, Stanford Exploration Project –Advanced imaging team Monday, September 27

  5. passive seismology • not event location • structural imaging • reflection seismology: subsurface investigation from the time-delayed reflections of sound off of geologic variations. • passive imaging: with no application of controlled experimental sources, a relationship between a recorded transmission wavefield and reflection wavefields is required. • requires: stationary seismometers, lots of disk space

  6. crustal scale exploration

  7. earthquake energy

  8. capitalizing on ambient noise • earthquake arrivals • ocean waves • wind vibrations coupled with foundations • cultural activity • vehicle and boat traffic • drilling noise • nearby seismic acquisition

  9. Valhall • one of the North sea giant fields • partners Amerada Hess, Shell and Total • reservoir highly porous chalk • first production 1982 • field life 2028 • field production 90,000 bpd/day • expected ultimate recovery 1,050 mm stb oil • produced to date (01.01.2003) 500 mm stb oil • remaining reserves 540 mm stb oil • high activity level – new wells & well work

  10. Valhall Life of Field Seismic (LoFS) • Permanent field wide seismic array installed at Valhall during 2003 • 120 km seismic cables • 2414 groups of 4C sensors • Covers 45sq km • 3 seismic surveys acquired, 4th to be acquired mid-September

  11. state of the art airgun array carried by stand-by boat – 53,000 shots per survey ~1/2 cost of LoFS installations related to the source operations

  12. passive seismology by correlation • why image? • linearity of wavefield extrapolation • application to Valhall LoFS • why try passive seismic imaging? • future plans

  13. transmission wavefield position(m) position(m) time (s) depth (m)

  14. ambient noise r1 r2 r1 r2 t

  15. ambient noise r1 r2 r1 r2 t

  16. ambient noise r1 r2 r1 r2 t

  17. ambient noise r1 r2 r1 r2 r1 r1 r1 r2 t lag

  18. ambient noise r1 r2 r1 r2 r1 r1 r1 r2 t twt

  19. position(m) offset(m) 0 200 300 400 600 1200 100 0 0 0.1 5 10 lag(s) time(s) 0.3 20 25 30

  20. position(m) offset(m) 0 200 300 600 1200 -100 100 0 0 0.1 5 10 lag(s) time(s) 0.3 20 25 30

  21. offset(m) position(m) 0 200 -200 -100 100 600 1200 0 0 0.1 5 10 lag(s) time(s) 0.3 20 25 30

  22. offset(m) position(m) 0 -300 -200 -100 100 600 1200 0 0 0.1 5 10 lag(s) time(s) 0.3 20 25 30 2 n long traces n short traces

  23. passive seismology by correlation • why image? • linearity of wavefield extrapolation • application to Valhall LoFS • why try passive seismic imaging? • future plans

  24. why image? signal/noise enhancement migrated image one correlated shot gather

  25. T T z z + - T T z+1 z+1 flow model R D U z z z + - + R D U z+1 z+1 z+1 extrapolation correlation T= Transmission wavefield D= Source wavefield (down-going) U= Receiver wavefield (up-going) R= Total reflection data

  26. SR Migration T T z z + - T T z+1 z+1 flow model R D U z z z + - + R D U z+1 z+1 z+1 extrapolation correlation T= Transmission wavefield D= Source wavefield (down-going) U= Receiver wavefield (up-going) R= Total reflection data

  27. CMP Migration T T z z + - T T z+1 z+1 flow model R D U z z z + - + R D U z+1 z+1 z+1 extrapolation correlation T= Transmission wavefield D= Source wavefield (down-going) U= Receiver wavefield (up-going) R= Total reflection data

  28. Passive Migration T T z z + - T T z+1 z+1 flow model R D U z z z + - + R D U z+1 z+1 z+1 extrapolation correlation T= Transmission wavefield D= Source wavefield (down-going) U= Receiver wavefield (up-going) R= Total reflection data

  29. imaging advantages • poor data quality mandates imaging • transformation from transmission to reflection wavefield can be accomplished along the way • saves time • n instead of n2 traces • removes IFFT of n2 (long) traces • trace length difference ~cancels strict compute cost savings • file i/o provides big savings • 1 shot of n traces vs. n shots of n traces • multiple image-space summations

  30. synthetic proof of concept active migration reflection gather

  31. synthetic proof of concept passive migration correlated passive gather

  32. passive seismology by correlation • why image? • linearity of wavefield extrapolation • application to Valhall LoFS • why try passive seismic imaging? • future plans

  33. Valhall data

  34. Valhall data

  35. Depth slice near 88m Valhall data trace # energy localized around rig moveout across traces suggests surface noise

  36. Valhall data rig activity mono-freq. boat noise Reflector?

  37. Valhall pipe cut normalization 12km 4km

  38. Valhall pipe cut image 12km 4km

  39. Valhall pipe cut image 12km 4km

  40. Valhall active seismic 12km 4km

  41. passive seismology by correlation • why image? • linearity of wavefield extrapolation • application to Valhall LoFS • why try passive seismic imaging? • future plans

  42. why try passive seismic imaging • understand a completely undeveloped experiment • capitalize on: • existing hardware • competitor’s sources • teleseismic & local noise • extend imaging bandwidth to lower frequencies • imaging forward scattered modes

  43. passive seismology by correlation • why image? • linearity of wavefield extrapolation • application to Valhall LoFS • why try passive seismic imaging? • future plans

  44. future plans • continued exploration of existing data • multi-component experiments • appropriate bandwidth parameterization • time/energy requirements • earthquake sources • rig-site continuous correlation • BP’s passive seismic imaging capabilities • file-handling infrastructure • native 3D imaging algorithms

  45. Oyo-Geospace cable

  46. multiple modeling in the image-space Brad Artman, Stanford Exploration Project –Advanced Imaging Team Ken Matson, Advanced Imaging Team Monday, September 27

  47. Surface Related Multiple Elimination (SRME) • mechanics • classic shortfall • addressing the problem through imaging • shot-record imaging • multiple modeling at Maddog • implications and status

  48. Surface Related Multiple Extraction * = = * = *

  49. SRME s r

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