Abstract:

We analyzes the cause of formation of complicated wave field on rugged surface, and proposes a reverse-time prestack depth migration method based on a time-space domain one-way wave equation with high dip angle for imaging subsurface geological structures below the rugged surface. From synthetic shot gathers of a complicated structure with rugged surface simulated by solving acoustic wave equations using the finite-difference method, it is known that if the shot is in the low velocity layer, the energy received on the low velocity layer is much stronger than that received on the high velocity layer, and a strong guided wave is created in the low velocity layer. The proposed prestack migration method is applied to the synthetic shot gathers. Although neither the guided wave related to the low velocity media, nor the random noise is suppressed before migration, the interfaces are clear and their positions are correct, and the planes of fault are well focused too.

Key words: seismic prospecting, prestack depth migration, rugged surface, time-space domain, one-way wave equation, high dip angle, complex structure