This paper shows the application of Phase Shift Plus Interpolation Split-Step (PSPI-SS) wavefield extrapolation operator coupled with the excitation-time imaging condition to perform prestack seismic depth migration of common shot profiles. The migration methods which are characterized by the use of different propagators for the source and receiver wavefields are called hybrid migration methods. Normally, the source wavefield is determined by the computation of the traveltimes from the solution of the eikonal equation. Here the traveltimes were calculated based on a finite difference solution of the eikonal equation (TGRID), a simple geometrical approach (FAST) and also by the paraxial ray tracing method (PARAX). For the extrapolation of the receiver data we applied the PSPI Split-Step operator, that is derived from the conventional Split-Step wave equation method using multiple references velocity. As the source traveltime computation is based on the ray assintotic theory the velocity field needs to be smoothed and the migration results obtained with the Kirchhof migration method, that is a very fast migration procedure, was used to choose the best level of smoothing of the velocity field. In this work the synthetic Marmousi data and a real dataset from Gulf of Mexico were used to test the migration methods proposed here. The migration results with the hybrid methods shown better images in quality then the kirchhoff's results and comparable to those obtained with the full PSPI-SS migration method, but a low computation cost.
Hybrid migration; Prestack migration; Split-Step Phase Shift Plus Interpolation
