Arkoma Basin
The basin lies in between the Ozark Uplift and Oklahoma Platform to the north and Ouachita Mountains to the south and with an area of approximately 33,800 mi2.
Surface mapping of coal seams in the early part of the 20th century lead to the discovery of sub-surface features that indicated the presence of natural gas.
Subduction and subsequent formation of an accretionary prism in the early Pennsylvanian caused normal faulting throughout the basin.
By late Atokan time, foreland-style thrusting became predominant as the subduction complex pushed northward against strata.
[3] Because of this, deformational features become more prominent in the basin towards the southern extent on the north face of the Ouachita Mountains.
The ocean basin that was present during the lower Paleozoic is indicated by deep marine shales with subordinate volumes of limestone and quartzose sandstones and bedded chert lie on top of the basement rock.
These sequences are referred to collectively as the 'Ouachita Facies'[4] The Mississippian to early Atokan strata indicate a shallow marine environment.
Middle Atokan consist primarily of deep-water clastic strata, and are restricted to the southern part of the basin south of its hinge line and to the tectonic belt; the Red Oak sandstone is the best-studied of these reservoirs.
The youngest group (Desmoinesian and upper Atokan) consists mostly of fluvial-deltaic sediments (e.g., Hartshorne Formation), some of which show significant tidal influence (e.g., Booch sandstones).
[5][6] Post Atokan strata are shales sandstones and coal beds deposited during final phases of foreland basin sedimentation These strata thicken to the south but do not display abrupt thickening across normal faults indicating that synde[7] positional faulting had ceased.
The surface exploration of coal seams in the Arkoma Basin provided maps which showed closed anticlines and encouraged prospectors to drill for oil and gas.
[2] The strata of the Arkoma basin display high thermal maturity as evidenced by vitrinite reflectance (Ro) values.
[2] In cited literature, the rocks of Red Oak gas field would be considered overmature with an Ro value of 3.0%.
The center of the basin experienced increased sedimentation rates during this period thus creating deep burial for organic material.
Four major erosion events along with decreased sedimentation occurred after the Mississippian period delayed gas formation.
In older strata, reservoirs are either quartzose sandstones (Spiro, Cromwell, and Simpson) or limestones/dolostones (Wapanucka, Mississippian, Hunton, and Arbuckle).
