Explicit wavefield extrapolation directly from topography

Abstract

Summary Downward continuation methods assume that extrapolation takes place between two planes, but most land surveys are acquired over irregular surfaces. Most approaches that allow downward continuation methods to handle such data, like the wave equation datuming and zero-velocity layer methods, require some processing prior to migration. In this paper, we show how explicit wavefield extrapolation methods in the space-frequency domain can efficiently extrapolate data directly from rugged topography. By building operators with different depth steps, these wavefield extrapolators can handle lateral velocity and topographic variations. We use a source-receiver migration technique to illustrate how this approach can be implemented, using a synthetic dataset as an example.