Pre-stack Least-squares Reverse Time Migration - A Case Study from Deep Offshore West Africa

Least-Squares Migrations are well studied since few decades and are essentially known for their good properties in improving the signal-to-noise ratio, increasing the resolution and giving better and well-balanced amplitudes. Herein, the focus is done on Least-Square Reverse Time Migration for its ability to handle complex velocity fields with sharp velocity contrasts. In this paper we present an application of our regularized Least-Squares Reverse Time Migration to a subsalt imaging study using wide-azimuth seismic data. The operational objectives of this work are to improve the imaging of the target, to better understand the geometry of the structure and to reduce subsalt uncertainty related to reservoir extension so as to optimally position development wells. Numerical tests on this field will exhibit the potential of our current approach in producing images with better lateral continuities, improving signal-to-noise ratio and reducing migration artifacts. The impact of Least-Squares Reverse Time Migration on the amplitudes will also be debated.