AVA correction for migration in highly discontinuous media

Abstract

Summary Current macro-model–based one-way wavefield extrapolation ignores the practical highly discontinuous character of rock formations. The main effects of this highly discontinuous behaviour on transmitted wavefields are angle-dependent dispersion and amplitude losses. In this paper the angle-dependent dispersion and amplitude losses are quantified by a proposed extended macro model, which is much related to the current macro model except that two stochastic parameters on the rock formations are added. The stochastic parameters are derived based on the observation of power-law behaviour of subsurface heterogeneity. Explicit extrapolation operators are used to perform forward and inverse wavefield extrapolation. A true-amplitude prestack migration scheme is proposed, that can correctly eliminate the dispersion effects of the fine-layering together with the geometrical spreading effects in imaging the subsurface based on the extended macro model. A synthetic seismic experiment is designed to test the migration scheme.