A MODIFIED IMAGING PRINCIPLE FOR TRUE-AMPLITUDE WAVE-EQUATION MIGRATION

Abstract

A modified imaging principle is proposed in order to retrieve the `true amplitude' map of the relative slowness perturbations from multishot surface seismic data. The purpose is to obtain a method applicable with a finite-difference solution of the wave equation and equivalent to the ray-based migration/inversion approach. The proposed modification consists of multiplying the integrand of the classic Claerbout imaging principle by an angle-dependent factor in order to remove the angle dependency and obtain an estimate of the slowness perturbations. It is demonstrated that in high-frequency asymptotics the proposed modified imaging principle is similar to the ray-based inversion. A numerical example based on a 2-D synthetic marine-type seismic data set and a finite-difference wavefield extrapolation shows the relevance of this modification.