Red Oak Gas Field, Arkoma Basin, Oklahoma

HOUSEKNECHT, DAVID W., University of Missouri, Columbia, MO, and T. A. MCGILVERY, HOCOL S.A., Cartegena, Colombia

Red Oak gas field, with ultimate reserves of greater than 2 TCF methane, is the largest field in the Arkoma basin. As a result of dynamic tectonic evolution of the basin during the Atokan, sandstone reservoirs display significant contrasts in reservoir characteristics.

The basal Atokan Spiro sandstone is a quartz arenite deposited in southward prograding deltas on a tectonically stable shelf. Geologic events associated with evolution of the Ouachita-Arkoma tectonic system influenced the Spiro reservoir. Most important among these were (1) fracturing of the Spiro into normal fault blocks, (2) facies selective diagenesis, (3) liquid hydrocarbon accumulation, (4) thermal degradation of hydrocarbons to methane, and (5) hydrothermal quartz cementation below hydrocarbon-water contacts. Consequently, optimum Spiro reservoir quality occurs along linear, north-south channel trends at locations that were structurally high at the time of thermal overmaturation.

The middle Atokan Red Oak sandstone is a sublithic arenite deposited by westward flowing turbidites in slope channels localized above normal faults formed during tectonic breakdown of the precursor shelf. During burial, diagenesis destroyed porosity in some slope channel facies and enhanced porosity in others. During methane generation in encasing shales, the Red Oak was an amalgamation of porous and nonporous slope channel sandstones. Compression associated with late stages of Ouachita orogenesis deformed the reservoir horizon into a thrusted anticline, separated from the underlying Sprio by decollements in intervening shales. In contrast to the Sprio, optimum Red Oak reservoir quality occurs along linear, east-west channel trends at locations that were structurally low at the time o deposition and diagenesis.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)