Survey sinking prestack depth migration using local cosine basis beamlets

In this work, we combine the local perturbation beamlet migration theory and the concept of survey sinking prestack depth migration. We prove the equivalence between the propagators in source-receiver survey sinking migration and the shot domain beamlet migration. In this algorithm, the frequency domain common point source and point receiver wavefield is first decomposed by the local cosine basis along common sources and receivers, and then the decomposed wavefield is downward-continued to the next depth along common beamlet-sources and beamlet-receivers subsequently. The propagated wavefield is equivalent to the data that would have been received if all sources and receivers were placed at the current depth. The migrated image is evaluated at zero time and zero offset. Numerical tests on synthetic data of the 2D SEG/EAGE salt model and the Marmousi model demonstrate the validity of the theory and the good accuracy of the beamlet method on strong contrast velocity model and complex geology structures.