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Stacking Statics Residual statics in combination with the
velocity analysis Muting
Approximated zero offset section
Delay-Time
GRM (“generalised reciprocal method”)
DRM (“diminishing residual matrices”)
Methods to determine the residual statics:
Statics (done before velocity analysis)
•Topographic Correction (elevation statics)
•“Uphole”-correction using shots in borehole
•Refraction statics: corrections for weathered layer
CMP Gathers with field statics applied
1. Velocity analysis
NMO-Correction
Compute Residual statics
NMO-Correction with new Velocities
Stacking
Apply Residual statics
2. Velocity analysis
Residual statics
NMO corrected data before and after residual corrections
Yilmaz, 1987
188297
Velocity spectra before (a) and after (b) residual stacking
CMP stacks without and with residual stacking
Yilmaz, 1987
Mean stack
Weighted Stack
Diversity Stack/Min-Max-exclude
Certain traces are muted and not included in the stacking procedure
n
itimeant w
ns
1,,
1
n
itiiedmeanweightt w
ns
1,,
1
Methods to Stack
stacked section
Velocity model
Velocity model
Stacking velocity field
Yilmaz, 1987
CMP stack
Yilmaz, 1987
CMP stack using gain function
Yilmaz, 1987
Migrated CMP stack