CARDOTT, BRIAN J.
Oklahoma Geological Survey, Norman, OK
Abstract: Oklahoma Coalbed Methane: from Mine Explosion to Gas Resource
Once an explosion hazard in eastern Oklahoma underground coal mines, coalbed-methane (CBM) has become a valuable resource. Mine explosions from gas and dust caused more than 500 deaths in mining disasters from 1885-1945. There have been more than 600 CBM completions in Oklahoma since 1988.
CBM well information is in the coalbed-methane completions table of the Oklahoma Coal Database. Each record in the table includes the operator, well name, completion date, location information (township grid system and latitude-longitude), county, coal bed, producing depth interval, initial potential gas and produced-water rates, and comments. A searchable version of, the table is available as a link from the Oklahoma Geological Survey web page.
The CBM play began in 1988 with 7 wells in the Hartshorne coal bed at depths of 611-716 ft. A maximum of 68 wells were drilled in 1992, followed by a decline to 26 wells in 1994. Through 1993, CBM production was exclusively from the Arkoma basin. Activity on the northeast Oklahoma shelf began with 3 wells in 1994. More than 140 CBM wells were drilled in 1997, of which more than 100 were on the shelf. Since 1988, depths of producing intervals ranged from 216-1,689 ft on the shelf to 598 - 3,748 ft in the basin. Initial potential gas rates ranged from a trace to 125 thousand cubic feet of gas per day (MCFGPD) on the shelf and from a trace to 595 MCFGPD from a horizontal CB well in the basin.
Low initial gas rates and minimal initial increase in gas production during dewatering are often attributed to formation damage caused by well stimulation, including the generation of coal fines that plug permeability. Present industry emphasis is on matching the completion technique to the specific coal bed.
AAPG Search and Discovery Article #90921©1999 AAPG Mid-Continent Section Meeting, Wichita, Kansas