ANALYSIS OF LATERAL COHERENCY IN WIDE-ANGLE SEISMIC IMAGES OF HETEROGENEOUS TARGETS

The character of deep reflections recorded in wide-angle seismic experiments often suggests fine-scale layering in the structure of the reflecting target. The lateral continuity of wide-angle reflections is enhanced, however, because energy arriving at a long-offset receiver is confined to a narrow range of apparent slowness. The distribution of energy with slowness was studied by Levander and Gibson (this issue), who show that the restricted range amounts to a dip filter. Their energy-slowness distribution is used here to relate lateral correlation in a reflected wave field to the correlation properties of a randomly heterogeneous target. Tests with finite difference synthetic data from Levander and Gibson confirm a simple convolutional relation between the statistics of the wave field and those of a target with small-magnitude velocity variations. Field data recorded in the Basin and Range Province, Nevada, show a progressive increase in reflection continuity with increasing source-receiver offset, as expected. Interpretation of reflector heterogeneity for this data set, however, is complicated by noise contamination and scattering above the target.