Analysis of lateral coherency in wide‐angle seismic images of heterogeneous targets

Abstract

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‐off set 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.