Regional Geology of Deep Water Salt Architecture, Offshore Gulf of Mexico
Abu Chowdhury and Simon Lopez-Mora
TGS-NOPEC, Houston, Texas
A prestack depth migration project was undertaken to better image the deep-water salt and associated geology of the Gulf of Mexico. A regional 100,000 kilometers of 3.2-kilometer by 3.2 kilometer grid, 2 dimensional seismic data was used. One hundred and ninety deep-water wells were integrated with the seismic stacking velocities to create a velocity model with which to migrate the sediments. The top salt was picked using both the sediment migration and the mapped time data. The subjacent sections were then migrated with salt velocity in an attempt to image base salt that was subsequently interpreted from seismic character, regional geology and flatness of common image gathers. Integrated into the interpretation was, the mapped base salt from time data, water bottom multiples, top salt multiples, and cross- line interpretation picks that were posted in depth domain.
The prestack, depth-migrated data reveal thick salt canopies up to 6 kilometers associated with fold belts in Alaminos Canyon, Keathley Canyon and southern Garden Banks. They are very massive with generally gently dipping bases. In contrast, the salt bodies of eastern Walker ridge and southeastern Green Canyon show steep dips. The salt further east in the Atwater fold belt generally dip gently. The salt body architecture commonly varies from back ramp rooted to deflated autocthons. Northward, in relatively shallow water, salt generally varies in thickness from 0.5 to 3 kilometers. Many show association with shallow decollement surfaces that can be traced up dip into the shelf areas.
AAPG Search and Discovery Article #90032©2004 GCAGS 54th Annual Convention, San Antonio, Texas, October 10-12, 2004