Imaging complex salt bodies with turning‐wave one‐way wave equation

Abstract

We propose a modified version of one-way wave equation migration which incorporates true amplitude corrections to enhance steep dips and propagates wavefields to any possible directions. With this new method, turning waves can be properly imaged and the imaging capability of one-way wave equation is greatly improved. Introduction One-way wave equation migration has been widely used in 3-D seismic processing for imaging complex structures. To image steeply dipping reflectors, sometimes we have to depend on the reflections conveyed by turning waves. However, conventional one-way wave equation can only compute the wavefield with propagation angles less than 90o relative to the vertical direction. Therefore steeply dipping salt flanks and the underside of domes, which require turning waves to generate an image, are often absent from seismic images. To properly delineate complex salt bodies, we need a wave equation based migration that can image all dips, even beyond 90o. In this paper we propose a modified version of the one-way wave equation migration that can propagate wavefields to any possible direction. Also, we incorporate true amplitude corrections in the migration to enhance steep dips. With this new method, turning waves are properly imaged by a prestack depth migration. Theory and Algorithm According to Zhang (1993), the two-way wave equation can be approximately split into the following coupled one-way wave equation system