Geologic framework for the assessment of undiscovered oil and gas resources in sandstone reservoirs of the Upper Jurassic-Lower Cretaceous Cotton Valley Group, U.S. Gulf of Mexico region

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Abstract

The U.S. Geological Survey (USGS) is assessing the undiscovered oil and gas resources in sandstone reservoirs of the Upper Jurassic–Lower Cretaceous Cotton Valley Group in onshore areas and State waters of the U.S. Gulf of Mexico region. The assessment is based on geologic elements of a total petroleum system. Four assessment units (AUs) are defined based on characterization of hydrocarbon source and reservoir rocks, seals, traps, and the geohistory of the hydrocarbon products. Strata in each AU share similar stratigraphic, structural, and hydrocarbon-charge histories. The Cotton Valley Group extends in the subsurface from southern Texas to the Florida Panhandle in an arcuate belt that crosses northern Louisiana, the southern part of Arkansas, and southern Mississippi and Alabama. Three of the AUs are quantitatively assessed for undiscovered volumes of hydrocarbons in conventional accumulations. The Cotton Valley Updip Oil AU includes areas between the maximum updip limit of the Cotton Valley Group and a curved belt of regional faults (included in the Peripheral Fault System AU). Hydrocarbon charge to this AU remains uncertain. The Peripheral Fault System Oil and Gas AU includes the Mexia, Talco, State Line, South Arkansas, Pickens, Gilbertown, and other fault segments, which trapped early oil that migrated from source rocks within the Smackover Formation. Hydrocarbons in the Downdip Oil and Gas AU are primarily associated with low-amplitude salt-related features in the East Texas, North Louisiana, and Mississippi salt basins. The Tight Sandstone Gas AU contains gas-charged sandstones previously referred to collectively as “massive.” Their reservoir properties are consistent with the USGS’s definition of continuous reservoirs, and their resources, therefore, are assessed using a separate methodology. Optimal coincidence of low-permeability sandstone, gas-mature source rocks, and complex structures of the regional Sabine feature encouraged development of a general “sweet spot” area in eastern Texas.

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Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Geologic framework for the assessment of undiscovered oil and gas resources in sandstone reservoirs of the Upper Jurassic-Lower Cretaceous Cotton Valley Group, U.S. Gulf of Mexico region
Volume 65
Year Published 2015
Language English
Publisher Gulf Coast Association of Geological Societies
Contributing office(s) Central Energy Resources Science Center
Description 16 p.
First page 93
Last page 105
Conference Title Gulf Coast Association of Geological Societies 2015 65th Annual Convention
Conference Location Houston, TX
Conference Date September 20-22, 2015
Country United States