ABSTRACT: Geological Aspects of Coalbed Methane Occurrence in Pennsylvania

MARKOWSKI, ANTONETTE K., Pennsylvania Geological Survey, Harrisburg, PA

Coal-bearing intervals from the Dunkard Group to the Pottsville Group are mapped to better understand the relationship between the regional geology of southwestern Pennsylvania and its influence on coalbed methane potential. An elliptical area from the Dunkard basin in Greene County northeastward to southwestern Indiana County was investigated. This seven month project was part of a Gas Research Institute funded study of the Northern Appalachian Coal basin with the West Virginia Geological and Economic Survey.

Numerous cable tool drillers' records, sample descriptions, geophysical well logs, and coal exploration cores were used to identify coals and other lithologic units, and to examine evidence of water and gas production, and gas shows from coalbeds. A regional cross section showing the correlation of Pennsylvanian strata was constructed along with coal occurrence, isopach, and isopleth maps.

Three genetic units thought to have the greatest potential to produce coalbed methane in southwestern Pennsylvania are: (1) between the base of the Clarion coal and the top of the Upper Kittanning in the lower part of the Allegheny Group; (2) between the base of the Lower Freeport coal and the top of the Lower Bakerstown in the upper part of the Allegheny Group and the lower part of the Conemaugh Group; and (3) between the base of the Pittsburgh coal and the top of the Sewickley in the lower part of the Monongahela Group.

Some of the geologic factors affecting production and field development are: (1) depositional and stratigraphic controls, (2) structural controls, tectonic history, and natural fracture systems, and (3) hydrologic controls.

AAPG Search and Discovery Article #91013©1992 AAPG Eastern Section Meeting, Champaign, Illinois, September 20-22, 1992 (2009)