A comparison of migration methods in laterally varying media

Parallel implementation of 3‐D split‐step Fourier depth migration algorithm on T3E

“…Another approach for prestack split-step depth migration can be obtained by using downward continued receiver wave eld and pre-computed travel times from the source Tanis, 1993…”

“…While the advent of the MPP's made it possible for more accurate but compute intensive algorithms such a s explicit nite-di erence methods to be considered for 3-D imaging, their routine use primarily is still limited to 3-D poststack imaging. The split-step Fourier migration method, originally developed by Sto a et al 1990, is an imaging technique for both poststack and prestack depth migration since it is an e cient algorithm that can handle smooth lateral velocity variations Tanis, 1993. The method is an extension of Gazdag's phase-shift method to accommodate lateral velocity variations.…”

“…The wave eld is continued by applying a phase-shift based on the mean slowness in the frequency-wavenumber domain and a second phase-shift based on the laterally varying component in the frequency-space domain. The use of maximum slowness instead of mean slowness as the reference velocity can further improve the accuracy of the method Tanis, 1996. We implemented an optimized parallel 3-D split-step Fourier depth migration algorithm for migrating 3-D seismic data using PVM message passing calls on a Cray T3E. The poststack implementation is based on the work of Sto a et al 1990 where the exploding re ector model is assumed.…”

Prestack split-step fourier depth migration

“…To construct the image, the correlation with source wave eld is replaced by the application of a phase term obtained from direct arrival times Tanis, 1993. In addition, prestack split-step Fourier depth migration algorithm can be developed using the double square root DSR equation, where the source and receiver wave elds are downward continued simultaneously for a laterally varying medium.…”