Coalbed methane resources and activity in Pennsylvania
Markowski, Antonette K., DCNR-PA Geological Survey, 3240 Schoolhouse Road, Middletown, PA 17057-3534
A preliminary reconnaissance of coalbed methane (CBM) gas content data from exploratory coal cores and pre-existing data implied that with increasing depth and rank, the greater the gas content. Overall estimates of CBM resources indicate there may be 61 trillion cubic feet (Tcf) of gas-in-place contained in the Northern Appalachian coal basin, based on a 1988 topical report for the Gas Research Institute by Kelafant and others. The technically recoverable CBM resources for the basin is projected at 11.48 Tcf from the United States Geological Survey oil and gas resource assessment of 1995. The total recoverable CBM resources in Pennsylvania are estimated at 2,654 billion cubic feet (Bcf) by a 1983 Briggs and Tatlock report for the Pennsylvania Oil and gas Association and the Pennsylvania Natural Gas Associates. A subsequent mapping investigation to evaluate the regional geology of the bituminous coal-bearing intervals focused on a stratigraphic delineation of Allegheny Formation coal beds and associated sandstones. A variety of cross sections and isopach maps show several prospective coal beds and facies relationships with channel-fill sandstones. These scenarios suggest the potential for CBM traps and current production figures reflect methane-producing coals in the Allegheny. Pennsylvania has a conservative estimate of 285 CBM wells in commercial production as of December 2005. This is about ten times the number of wells that were producing in 1997. Over 400 permits since 1938 reflect wells exhibiting serendipitous discoveries of gas from coal, unsuccessful attempts at CBM, and various degrees of CBM production. Target depths range from less than 200 feet in Fayette County to approximately 2,165 feet in Greene County. Overall reported production from 1988 to 2003 is 7.6 Bcf. The most recent total production available, for 2003, is 1.6 Bcf. There has been a general increase in production since 1988 and dramatic growth since 1999 because of increased knowledge of the CBM reservoir, improvement in drilling technology, high gas prices, and the need to expand our domestic energy sources.
Northeastern Section–41st Annual Meeting (March 22, 2006)