Preconditioning of Least-Squares Reverse-Time Migration with the Inverse-Scattering Imaging Condition

Abstract

The Inverse-Scattering Imaging Condition (ISIC) is an imaging condition for Reverse-Time Migration (RTM) that attempts to recover the medium reflectivity. It is theoretically based on the asymptotic inverse to the Born approximation and can be represented in several theoretically approximately equivalent forms. Its application leads to more reliable reflectivity estimates and strongly reduces backscattering artifacts. In this work, we demonstrate that an ISIC formulation involving a Laplacian filter can be used as an effective preconditioning for Least-Squares RTM (LSRTM). The Laplacian-filter ISIC does not increase the computational cost over conventional imaging conditions. Our numerical experiments using synthetic seismic data from the Marmousi II model demonstrate that this preconditioning leads to faster convergence and superior final images of LSRTM, both in the image domain (ID-LSRTM) and data domain (DD-LSRTM), in this way actually reducing computational cost and turnaround time.