Practical Aspects of Least-squares Reverse Time Migration

Abstract

A 3D inversion based Least-Squares Reverse Time Migration (LSRTM) technique has been developed. Compared to the conventional migration algorithm, which is the adjoint operator of forward modeling, LSRTM tries to solve the inversion operator of forward modeling. Thus, LSRTM can effectively suppress conventional migration artifacts, including migration swings, side lobes and the acquisition footprint, and deliver a high resolution and true amplitude seismic image. Compared to conventional RTM, the LSRTM broadens the image spectrum through suppression of the side lobes, which gives the LSRTM image a 3D textured visual effect and sharper resolution of layer boundaries. This leads us to the use of LSRTM as a broadband imaging tool. As a true amplitude and broadband imaging approach, LSRTM is effective for steep events and fault plane imaging and for 4D and detailed reservoir imaging. In this paper, we address some practical aspects of LSRTM and will share some practical lessons learned from our study.