The Evolving Exploration of the Subsalt Play in the Offshore Gulf of Mexico

Dwight "Clint" Moore and Robert Brooks

The co-existence of horizontal components of salt movement with subsalt traps in the south additions of the Louisiana and Texas shelf and slope, has been recognized within the last decade. Throughout the 1970's & 1980's, hundreds of wells were drilled into salt on the outer shelf and slope of the northwest Gulf of Mexico. These wells barely penetrated salt features that are now known to be laterally emplaced horizontal salt sheets. Drilling was typically stopped thousands of feet short of testing the potential sizable petroleum reservoirs of the subsalt exploration play, which is now being pursued and developed.

Horizontal emplacement of Gulf of Mexico salt sheets, and their effect of subsalt drilling results, can be demonstrated using 2-D time seismic sections well logs, and biostratigraphy from over 30 wells drilled through varying thicknesses of the 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 MC 211, have confirmed the play and encourage future exploratory drilling. As advance 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-style traps beneath the horizontal salt sheets of the off hore Gulf of Mexico.

The 1990's should be the "Decade of Discovery" for this significant subsalt petroleum potential, hidden by these salt sheets that have obscured subsalt seismic images for decades.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California