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Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
USGS Assessment of Undiscovered Oil and Gas Resources of the Lower Cretaceous Sligo Sandstone, Eastern U.S. Gulf of Mexico Coastal Plain
(1) EERSC, USGS, Reston, VA.
The U.S. Geological Survey (USGS) has completed an assessment of the technically recoverable undiscovered oil and gas resources in Lower Cretaceous Sligo Sandstone Gas and Oil Assessment Unit (AU) of the U.S. Gulf of Mexico Coastal Plain and State Waters. The Sligo Sandstone Gas and Oil AU consists of the clastic facies of the Sligo Formation in the eastern Gulf Coast (Mississippi, Alabama and Florida). The western margin of the AU is defined by the Sligo clastic/carbonate facies transition near the Louisiana/Mississippi border, the northern margin by Sligo Formation outcrop, the eastern margin by the Lower Cretaceous clastic limit in Florida, and the southern margin by the state/federal water boundary. The AU is bounded stratigraphically by the underlying Hosston Formation and the overlying Pine Island Shale (where present) and Rodessa Formation.
The Sligo Sandstone Gas and Oil AU is composed of Lower Cretaceous Barremian to early Aptian, fine-grained, shallow marine sands deposited in primarily shore-face to near-shore environments. This AU is thought to contain hydrocarbons sourced solely from the Smackover limestone, and petroleum reservoirs within the AU are conventional gas and oil accumulations. To date, 13 gas fields and 13 oil fields have produced from within the AU at depths ranging from 7,500 ft to 15,800 ft. Production has been entirely from the flanks of salt anticlines and salt ridges within the Mississippi Interior Salt Basin and normal fault traps associated with these features.
Potential undiscovered reservoirs will be primarily around unexplored or under-explored salt anticlines within the Mississippi Interior Salt Basin. Although some potential remains for the discovery of oil accumulations on the up-dip flank of the Mississippi Salt Basin, the undiscovered reservoirs within the AU are most likely to be natural gas accumulations towards the center of the Salt Basin. Stratigraphic trapping of petroleum accumulations up-dip from the salt basin is possible within the AU; however the potential for this scenario is small due to the lack of a contiguous, regional sealing formation.