John H. Shinol1,
H. Scott Sumner2,
J. Tim Ford2
(1) Unocal Corporation, Sugar Land, TX
(2) Unocal Corp, Sugar Land, TX
Abstract: Subsalt Exploration in the Gulf of Mexico Deepwater
The subsalt play in the United States portion of the deepwater Gulf of Mexico is an evolving trend with significant hydrocarbon potential. The trend was partitioned into distinct regional provinces based on geological, geophysical and associated petroleum system attributes. This regional framework is the backbone for Unocal's subsalt exploration in the deepwater Gulf of Mexico.
A 'Subsalt Tectonic Features and Charge Elements Map' delineates the subsalt provinces. Each province is described in terms of salt configuration, trap styles, reservoir quality, charge characteristics, potential field size and seismic image quality. The petroleum systems and exploration risks are summarized for each province.
In general, traps, reservoirs, and thermal charge are interpreted to be present in all the subsalt provinces. However, there are significant variations in each of these parameters resulting in important differences between provinces in hydrocarbon volume potential, field size distribution, exploration risking, and business strategy.
As a result of the approach described above, Unocal has focused its deepwater exploration below the Sigsbee Salt Canopy on the offshore Louisiana lower continental slope. We believe this area contains petroleum systems that are conducive to large discoveries (300 MMBOE). Attributes of these petroleum systems include large Middle Miocene to Pliocene-aged salt-cored folds, large turtle structures, high quality Miocene turbidite reservoirs, access to oil prone Mesozoic sourced charge, soft to moderate geopressures, relatively good subsalt data quality, and favorable drilling conditions.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana