Improved imaging through anisotropic depth migration and high‐resolution shallow tomography in lieu of refraction statics in South Timbalier Trench area of Gulf of Mexico: A case history

Abstract

We present a case study of an anisotropic prestack depth migration (APSDM) project which used high‐resolution, shallow tomography and anisotropic model building for a large depth migration project in the Gulf of Mexico. The enhanced work flow resulted in high quality images and more accurate placement of events, compared to previous processing in the area. The project consisted of approximately 553 OCS blocks of data in the Mississippi Canyon, South Timbalier, Ewing Bank, Grand Isle, Grand Isle South Addition and Ship Shoal South Addition areas (Figure 1). The goals of this project were to produce a more accurate velocity model which would enhance event placement and improve the imaging of steep dips, salt boundaries, and subsalt events. To this end, the low velocity South Timbalier trench area which was previously addressed via refraction statics was modeled using tomographic velocity inversion to produce a more accurate shallow velocity field. Additionally anisotropic prestack depth migration was employed to better tie the seismic events with well information.