3-D prestack depth migration with an acoustic pseudo-screen propagator

The acoustic pseudo-screen propagator is a kind of one-way wave propagator implemented in the wavenumber-space domain (dual-domain). It takes into account lateral velocity and density variations. We have recently used it for modeling primary reflected waves. In this paper, we use it as recursive downward wave extrapolators to develop a 3-D prestack depth migration method for common-shot data. In the method, the transversal Laplacian operators in the acoustic wave equation for heterogeneous media are applied exactly. The method has fast computational speed due to the use of fast Fourier transform algorithm and capability of handling wide-angle downward wave propagation/backpropagation in laterally heterogeneous media. Another main advantage of the method is huge memory saving relative to finite-difference or ray tracing based methods. Therefore, the 3-D acoustic pseudo-screen prestack depth migration method may enable 3-D prestack migration for large real 3-D data sets to be implemented within a reasonable CPU time on a supercomputer. Numerical examples of migrating synthetic reflected data generated by a finite-difference algorithm for 2-D and 3-D models are presented to demonstrate the feasibility of the method.