FORGOTSON, J.M., School of Geology and Geophysics, University of Oklahoma, Norman, OK; and SAMUEL A. FRIEDMAN, Oklahoma Geological Survey, Norman, OK

ABSTRACT: Arkoma Basin (Oklahoma) Coal-Bed Methane Resource Base and Development

Seventy percent of the 4 TCF coal bed methane resource estimated for the Arkoma Basin is in the basal Desmoinesian (Pennsylvanian) Hartshorne coals that are a total of 3 to 12 ft thick. The Lower Hartshorne coal is a maximum of 10 ft thick and is 4 to 5 ft thick in most of the basin. Distribution and thickness of Hartshorne coals have been determined from outcrops, surface and underground mines, core holes, and logs of wells drilled for gas in deeper formations. From the western to the eastern part of the Oklahoma Arkoma basin the rank of Hartshorne coals increases from high-volatile C bituminous to low-volatile bituminous, and the gas content increases from 300 cu ft/ton to 600 cu ft/ton at depths of 800 to 2,000 feet.

Approximately 40 wells in the Kinta area of Haskell County are producing gas commercially from the Hartshorne coal reservoir. In Pittsburg County a few wells previously producing from the-Hartshorne sandstone have been recompleted in the overlying Hartshorne coal. Approximately 20 test wells, drilled in Le Flore County, are waiting on pipeline connections, are in various stages of completion, or have been abandoned. Coal-bed methane production rates in the basin range from 25 MCF/D to 250 MCF/D with little or no water production.

Preliminary economic evaluation suggests that because of the good infrastructure of roads, pipelines and gas field services, and low drilling and operating costs development of coal-bed methane production from Hartshorne coals totalling 5-10 ft thick, at depths of 500 to 2,000 feet, underlying relatively flat, easily accessible grazing land, should provide internal rates of return of 30% or more if the wellhead price is at least $2.00 MCF.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.