Imaging in 3-D DMO, Part II: Amplitude effects

Abstract

The amplitude of the dip‐moveout (DMO) output for a planar reflector at a point P and half offset k is a function of the curvature of the midpoint curve of the DMO input traces, the dip magnitude, and the dip direction. No single weighting function will preserve the amplitude of dipping events. Seismic synthetics on a circle of midpoints minimal data set verify that this data set has 6 dB of amplitude variation with azimuth for a 15° dipping reflector and a 14 dB variation for a 45° reflector. The theory shows that the 3DDMO weight for an arbitrary minimal data set is equal to the impulse response weight multiplied by the density of the normal segments at the dip being imaged. Aliasing is also a function of the normal segment density at the dip being imaged. If the spatial sampling is fine enough to prevent aliasing, DMO can be performed on a dip by dip basis and, by correcting for the normal segment density, these amplitude variations may be corrected.