Imaging a salt dome flank by directional redatuming of a field 3‐D VSP survey

Abstract

We processed a large 3‐D vertical seismic profile (VSP) around a Gulf of Mexico (GOM) salt dome. The VSP was acquired to address uncertainty in subsalt structure and in locating the dipping edge of the salt base on the surface seismic images. To simplify the processing, remove potential uncertainty in the velocity of the overburden, and image the salt edge, we create and apply a strategy of seismic interferometric, directional redatuming followed by prestack depth migration. The surface VSP shots are grouped into 10° wedges based on the shot to geophone azimuth. Each wedge is redatumed and migrated separately to create separately steered images of the salt flank. The final merged result complements and is compatible with the interpretation of the surface seismic data. The redatuming methodology does not require knowledge of the velocity structure between the surface shots and the downhole receivers, and the salt‐flank reflections are easily seen on the intermediate redatumed, virtual source gathers.