Stationary-phase wave-equation migration

Efficient implementation of 3D wave-equation migration is of vital importance for practical applications of wave-equation migration to marine streamer data. We develop a new 3D wave-equation migration scheme that is significantly more efficient than the full survey-sinking migration based on the double-square-root (DSR) equation in the midpoint-offset domain while maintaining the accuracy of migration algorithms. The method is based on the stationary-phase approximation and downward continuation of prestack marine streamer data in the midpoint-offset domain. It uses a small number of the cross-line offsets during downward continuation and uses an interpolation algorithm to obtain the wavefield at the stationary-phase point along the cross-line-offset wavenumber coordinate at each depth level for forming migration images. Our impulse response studies demonstrate that the method can produce accurate and clear images using only a small number of cross-line offsets.