Improving subsalt image from multiazimuth TTI reprocessing at Kepler Field, Gulf of Mexico

Elebiju, Bunmi (BP E&P) | Pratt, Kevin (BP) | Gou, Weiping (CGG) | Zeng, Yu (CGG)


Summary Subsalt imaging at the Kepler field, located in deep water Gulf of Mexico, has proven to be challenging, largely because of suboptimal illumination and complicated ray bending caused by complex overburden salt. It is well understood that building an accurate velocity model is one of the prerequisites to obtain a good subsalt image. Multiazimuth seismic data sets not only help with improving subsalt illumination, they also benefit the velocity model building process by providing more data to constrain the updates. In this paper, we demonstrate the impact of multi-azimuth data and the Kepler salt geometry on subsalt illumination through a 3D ray-tracing and finite difference modeling illumination study. The integration of a top of salt (TOS) anomaly layer into the Kepler salt velocity model significantly improved the subsalt images and reduced base of salt depth uncertainties.