PS tomography with cross-correlation-based event matching

Le résumé fourni par la source

Seismic PS images can complement conventional PP images, especially where PP images cannot effectively illuminate, e.g., below gas pockets. However, building reliable Vs migration velocity is crucial to achieve high-quality PS images, which is not trivial. Here we propose a raytracing-based PS tomography workflow to produce Vs velocity models with subsurface common-offset gathers. First, a double difference objective function is constructed due to the unknown target depths. Second, the raytracing process handles negative and positive offset gathers respectively because of the asymmetrical nature of PS rays. Third, after the PS gathers are flattened, we propose a depth-varied cross-correlation method with similarity scores to automatically pick depth shifts between PP and PS images, which are then used to invert for residual Vs velocity errors. Numerical examples show large heterogeneous Vs velocity errors can be solved for PS migration.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.