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US 5,285,422 AGranted
Method for compensating 3D DMO for the effects of an inhomogeneous earth
AssigneeWestern Atlas International, Inc.
InventorsAlfonso Gonzalez, Everett C. Mobley, Ronald E. Chambers
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Abstract
A three dimensional residual modeling operator is applied to seismic times that have been preprocessed by application of NMO and velocity independent DMO. The residual operator compensates for vertical velocity variation and anisotropy and its use precludes the need for ray tracing.
Claims4
A method for three-dimensional migration of seismic data to zero offset in the presence of an inhomogeneous earth, comprising the steps of:
- sorting the seismic data into a combined common offset and common azimuth gather;
- applying normal moveout to the sorted data gathers, said normal moveout being based upon the average RMS velocity to flat-lying beds corresponding to the recorded travel times;
- forming an intermediate data set t.sub.1 by applying a velocity-independent dip-moveout (DMO) operator to the normal-moveout-corrected data gathers;
- defining a three-dimensional (3-D) residual DMO operator .gamma..sub.c ;
- forming a zero-offset data set t.sub.2 by applying said 3-D residual DMO operator to said intermediate data set;
- and
- resorting said zero-offset data set to a common midpoint gather.
4 more elements
Dependencies are inferred from the claim text.