ABSTRACT: The Arkoma Basin--An Overmature Gas Province

WERNER, WILLIAM G., Mobil Exploration & Producing U.S. Inc., Oklahoma City, OK, and CHARLES E. GRIFFITH, Mobil Exploration and Producing Services, Inc., Dallas, TX

The Arkoma basin is a prolific, Paleozoic natural gas province located in eastern Oklahoma and Arkansas. Significant production occurs from "overmature" reservoir rocks that have some of the highest reported maturity levels (Ro's) in the world. These fields serve as productive analogs for other overmature areas. At Red Oak field, the Pennsylvanian Lower Atokan Spiro Sandstone produces from reservoir rocks with projected Ro's up to 4.5%. At Wilburton field, the Cambrian-Ordovician Arbuckle produces from reservoir rocks that have projected Ro's in excess of 3.5%.

Thermal modeling demonstrates that the Arkoma basin and Ouachita area was buried by a thick, thrusted overburden ranging in thickness from less than 10,000 ft to in excess of 30,000 ft. This thick overburden resulted in hydrocarbon generation in late Atokan/Desmoinesian and is the cause of the high thermal maturities present. Substantial removal of section by erosion has occurred during and since the Permian within the area.

The upper thermal exposure limit for significant production is not known for the Arkoma basin; it may be 5.0% Ro or higher. Deposition, structural development of traps, maturation and generation of hydrocarbons, migration, and trapping preceded the basin's maximum thermal history. Questions of methane stability, trap integrity, reservoir recrystallization, diffusion of gas, thermochemical destruction of gas, and dilution of gas best characterize potential problems in regard to the upper thermal limit of commercial production.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)