Processing and Binning OverviewFrom chapter 14 Elements of 3D Seismology by Chris Liner

OutlineJustification for ProcessingProcessing FlowBins

JustificationField data representation of the data is distant from a distance-depth representation of data.

Categories of ProcessingAdjustments to wavelets, or short-pulse adjustments e.g.,frequency filteringphase shifts (rotation)vibroseis correlationTraveltime Corrections (fig. 14.1) :StaticsNormal Moveout Dip MoveoutMigration

Categories of ProcessingAmplitude Corrections Geometric spreadingAutomatic Gain ControlNoise ReductionVertical stackMutingCMP stackfiltering (f, f-k, tau-p (or radon)multiple suppression

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

Seismic data Multiple universes for seismic dataShotpoint gathers (distance versus time)CMP gathers (distance versus time)Tau-p (horizontal slowness versus intercept time)f-k (frequency versus wavenumber)

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

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

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

dT/dx = 1/V (s/m)x1/V = 0 ( s/m)1/V = p (ray parameter)V

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

dT/dx = 1/Vh (s/m)x1/Vh = 1/[V/ sin(angle) ] ( s/m)1/Vh = p (ray parameter)angleV

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

x1/Vh = 1/[V/sin(angle) ]( s/m)1/Vh = p (ray parameter)angleV

x (m)Two-way traveltime (s)T0p (s/m)p=0tau (intercept time) sAdd amplitude

x (m)Two-way traveltime (s)T0p (s/m)p=0tau (intercept time) sAdd amplitude

x (m)Two-way traveltime (s)f (1/s)p=0k (wavenumber - 1/m)V=f/k (m/s)100 Hz1000 m/s1/10 m

x (m)Two-way traveltime (s)f (1/s)p=0k (wavenumber - 1/m)V=f/k (m/s)100 Hz1000 m/s1/10 m

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

P-wave& Sv -waveSzSx

skin depth = 1/2 longest wavelengthVh ~= 90% shear wave velocity

Dispersiont0t1t2t1t2Dispersion

Xia et al., 2004

x (m)Two-way traveltime (s)f (1/s)p=0k (wavenumber - 1/m)V=f/k (m/s)100 Hz1000 m/s

OutlineBinsCalculated common midpointsCMP bin centerLength and width of bin

To prevent aliasing:

max dimension = V/4fmaxFor GOM:V = V0 + 0.4 x depthRule of Thumb: 12.5m by 12.5 m for > 2000 mIDEAL BIN SIZE: 5m by 5m for seafloor and deeper

The best bin:SMALLALL OFFSETSALL AZIMUTHSLARGE FOLD

OutlineJustification for ProcessingProcessing FlowBins