Advanced Modeling And Imaging For Seismic Acquisition - A GOM Subsalt Example

Summary We developed a workflow for advanced seismic acquisition design. Visibility analyses, wave-equation modeling, RTM imaging and critical reflection illuminations are used to understand the causes of poorer images beneath the salt in the deepwater of Gulf of Mexico. Results indicate that the poorly imaged subsalt target horizons are partly because of the limited maximum offset (4 to 7 km) in acquisition and processing, and partly because of the critical angle reflections at the base of the salt. For the former, one can increase the cable length in acquisition. However, if critical reflection becomes a problem, it is impossible to improve imaging using surface seismic, no matter how long the cable is used. The advanced modeling and imaging can be used not only for seismic acquisition design, but also for subsalt structural interpretation.