Wesley T. Combs¹, Richard A. Eisenberg¹, Robert Shank¹

(1) Chevron, New Orleans, LA

ABSTRACT: Predicting the Sub-salt Structural Framework Beneath the Salt Canopy in Mississippi Canyon - Atwater Valley, Northern Gulf of Mexico

The Mississippi Canyon - Atwater Valley area of the deepwater Northern Gulf of Mexico contains a variety of extensional and compressional hydrocarbon play types. Extensive salt canopy development in this region obscures the structural linkage between the extensional province and associated plays in the north, and the Mississippi Fan Fold Belt and associated plays in the south. Time migrated seismic data often gives poor illumination of the Miocene geology present beneath the extensive salt canopy. Interpretation of complex extensional and compressional structural relationships using only time migrated data is often ambiguous and the structural solution non-unique.

The sub-salt structural framework can be constrained by integrating the interpretation of three different tools and techniques; projection of regional structural styles from areas with little or no canopy developed, interpretation of 3D depth migrated seismic data, and integration of regional gravity and magnetics. By evaluating the structural styles in the bounding regions it is possible to predict structural styles underneath the salt canopy. Sub-salt structural style can be used to then evaluate prospect risk. Use of extensive regional 3D seismic prestack and post stack depth migrations provides an order of magnitude increase in the amount of mappable sub-salt reflectors. Regional gravity and magnetic data is used to constrain deep salt interpretations and to provide clues to basement structures critical for hydrocarbon migration and prospect/play definition.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado