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Processing and Binning Overview

Processing and Binning Overview. From chapter 14 “Elements of 3D Seismology” by Chris Liner. Outline. Justification for Processing Processing Flow Bins. Justification. Field data representation of the data is distant from a distance-depth representation of data. Categories of Processing.

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Processing and Binning Overview

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  1. Processing and Binning Overview From chapter 14 “Elements of 3D Seismology” by Chris Liner

  2. Outline • Justification for Processing • Processing Flow • Bins

  3. Justification Field data representation of the data is distant from a distance-depth representation of data.

  4. Categories of Processing • Adjustments to wavelets, or short-pulse adjustments e.g., • frequency filtering • phase shifts (rotation) • vibroseis correlation • Traveltime Corrections (fig. 14.1) : • Statics • Normal Moveout • Dip Moveout • Migration

  5. Categories of Processing • Amplitude Corrections • Geometric spreading • Automatic Gain Control • Noise Reduction • Vertical stack • Muting • CMP stack • filtering (f, f-k, tau-p (or radon) • multiple suppression

  6. An example of analysis for near-surface seismic structure Xia et al., 2004

  7. Seismic data “Multiple universes for seismic data” • Shotpoint gathers (distance versus time) • CMP gathers (distance versus time) • Tau-p (horizontal slowness versus intercept time) • f-k (frequency versus wavenumber)

  8. Distance between shot and the receiver (m) Two-way traveltime (s)

  9. Velocity (m/s) Distance between shot and the receiver (m) Two-way traveltime (s) T0 dT/dx = 1/V (s/m) T2 = T02 + x2/ V2

  10. Velocity (m/s) Distance between shot and the receiver (m) Two-way traveltime (s) T0 dT/dx = 1/V (s/m) T2 = T02 + x2/ V2

  11. x V dT/dx = 1/V (s/m) 1/V = 0 ( s/m) 1/V = p (ray parameter)

  12. Velocity (m/s) Distance between shot and the receiver (m) Two-way traveltime (s) T0 dT/dx = 1/V (s/m) T2 = T02 + x2/ V2

  13. x V angle dT/dx = 1/Vh (s/m) 1/Vh = 1/[V/ sin(angle) ] ( s/m) 1/Vh = p (ray parameter)

  14. Velocity (m/s) Distance between shot and the receiver (m) Two-way traveltime (s) T0 dT/dx = 1/V (s/m) T2 = T02 + x2/ V2

  15. x angle V 1/Vh = 1/[V/sin(angle) ]( s/m) 1/Vh = p (ray parameter)

  16. p (s/m) x (m) Two-way traveltime (s) tau (intercept time) s p=0 T0 Add amplitude

  17. p (s/m) x (m) Two-way traveltime (s) tau (intercept time) s p=0 T0 Add amplitude

  18. f (1/s) x (m) Two-way traveltime (s) k (wavenumber - 1/m) p=0 1000m/s V=f/k (m/s) 1/10 m 100 Hz

  19. f (1/s) x (m) Two-way traveltime (s) k (wavenumber - 1/m) p=0 1000m/s V=f/k (m/s) 1/10 m 100 Hz

  20. f (1/s) x (m) Two-way traveltime (s) k (wavenumber - 1/m) Vh=1000 (m/s) Vh=inf (m/s) Vh=1000 (m/s) Vh=inf (m/s)

  21. Sz Sx P-wave & Sv -wave

  22. Vh ~= 90% shear wave velocity “skin depth” = 1/2 longest wavelength

  23. Dispersion t1 t2 t0 t1 t2 Dispersion

  24. Xia et al., 2004

  25. f (1/s) x (m) Two-way traveltime (s) k (wavenumber - 1/m) p=0 1000m/s V=f/k (m/s) 100 Hz

  26. Outline Bins Calculated common midpoints “CMP bin center” Length and width of bin <= spatial aliasing dimensions

  27. To prevent aliasing: max dimension = V/4fmax For GOM: V = V0 + 0.4 x depth Rule of Thumb: 12.5m by 12.5 m for > 2000 m IDEAL BIN SIZE: 5m by 5m for seafloor and deeper

  28. The “best” bin: • SMALL • ALL OFFSETS • ALL AZIMUTHS • LARGE FOLD

  29. Outline • Justification for Processing • Processing Flow • Bins

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