An Absorbing‐Layer Method of Seismic 3‐D Migration for Irregular Survey Objects

Abstract

3‐D seismic migration for an irregular acquisition geometry usually needs zero trace padding to form a regular area. The benefit of zero padding is easy to do 3‐D migration, but it will reduce the computational efficiency and migration quality. In this paper we use an additional absorbing thin layer surrounding the irregular geometry instead of zero padding. It has greatly decreased computational cost and improved the migration quality. In order to form an absorbing layer, a damping factor is added to one‐way wave equation. Since the wave field value attenuates quickly when the wave penetrates this thin layer, the reflection with the boundary condition that the wave‐field value is zero is very small. Since the migration algorithm with the zero‐boundary condition is easy to be implemented, 3‐D migration for an irregular acquisition geometry can be done directly. The effectivity of this method is illustrated by processing the practical data.