Common-image gathers (CIGs) are extensively used in migration velocity analysis. Any defocused events in the subsurface offset domain or equivalently nonflat events in angle-domain CIGs are accounted for revising the migration velocities. However, CIGs from wave-equation methods such as reverse time migration are often expensive to compute, especially in 3D. Using the excitation amplitude imaging condition that simplifies the forward-propagated source wavefield, we have managed to extract extended images for space and time lags in conjunction with prestack reverse time migration. The extended images tend to be cleaner, and the memory cost/disk storage is extensively reduced because we do not need to store the source wavefield. In addition, by avoiding the crosscorrelation calculation, we reduce the computational cost. These features are demonstrated on a linear v(z) model, a two-layer velocity model, and the Marmousi model.
|Original language||English (US)|
|Number of pages||1|
|State||Published - Jun 7 2016|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We would like to thank the King Abdullah University of Science
and Technology (KAUST) for its support and especially all the
members of Seismic Wave Analysis Group within KAUST for the
many fruitful discussions. This research made use of the resources of
IT Research Computing at KAUST. Also, we thank all the reviewers,
namely, B. D. Nguyen, H. Jin, and one anonymous reviewer for their
critical and constructive suggestions.