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Abstract: The Evolving Exploration of the Sub-Salt Play in the Offshore Gulf of Mexico

Dwight "Clint" Moore, Robert O. Brooks

The existence of horizontal components of salt movement with subsalt traps in the south additions of the Louisiana & Texas shelf and slope, has been established within the last decade. Throughout the 1970's and 1980's, hundreds of wells were drilled into salt on the outer shelf and slope of the northwestern Gulf of Mexico. Unless drilled into vertical salt diapirs, which themselves are secondary re mobilizations, these wells barely penetrated salt features that are now interpreted as laterally emplaced horizontal salt sheets. Drilling stopped thousands of feet short of testing the sizable petroleum potential of the subsalt exploration play, that is now evolving in the Offshore Gulf of Mexico. It is also apparent that the evolutionary vertical re mobilization of these heets has structured many of the supra-salt giant fields discovered in younger, overlying sediments.

Horizontal emplacement of Gulf of Mexico salt tectonics, when combined with subsalt drilling results, can be demonstrated using 2-D time seismic sections, well logs, and paleobathymetry from over 20 wells drilled through and/or into varying thicknesses of the horizontal salt sheets. The presence of thick subsalt sands, such as those observed in SMI 200, are now also proven. Subsalt petroleum discoveries announced in SS 349, ST 260, and in MC 211, have confirmed the play and encourage future exploratory drilling. As advanced acquisition and processing techniques provide improvements in seismic image resolution, and subsalt well control refines geologic models and concepts, geoscientific integration will lead to additional significant discoveries in multiple styled traps beneath the hor zontal salt sheets of the Offshore Gulf of Mexico.

The 1990's should be the Decade of Discovery for the significant subsalt petroleum potential that has been previously hidden by the horizontal salt sheets that have obscured subsalt seismic images for decades.

AAPG Search and Discovery Article #90955©1995 GCAGS 45th Annual Meeting and Gulf Section SEPM, Baton Rouge, Louisiana