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Abstract: The Mahogany Subsalt Discovery: A Unique Hydrocarbon Play, Gulf of Mexico

Holly Harrison, Dwight (Clint) Moore, James Fox, Roberto Garcia

The Mahogany subsalt discovery is the industry's first commercial subsalt oil development in the Gulf of Mexico. The field discovery is located 80 miles offshore Louisiana on Ship Shoal South Additions blocks 349/359. It is a faulted anticline overlain by allochthonous salt. The allochthonous salt has a significant impact on subsalt trap formation, reservoir geometry and hydrocarbon migration. The area is characterized by multiple salt sheets. Two form a sutured canopy above Mahogany, and several older, deeper sheets are identified. Subsalt fairways can be interpreted by mapping relative salt-induced paleobathymetry. These deepwater sand fairways were deposited prior to allochthonous salt movement.

The discovery well tested 7256 BOPD and 7.3 MMCFD on a 32/64^Prime choke at 7063 PSI flowing tubing pressure. The primary subsalt reservoir is a critically pressured oil sand with high permeability and porosity and has tremendous deliverability. Subsequent appraisal wells suggest that high sustainable production rates can be expected, and this is confirmed by rock property studies and detailed well log analysis. Integrating this information with depth-migrated 3-D seismic and regional geology studies has yielded a more complete understanding of this dynamic petroleum system.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela