Pennsylvanian bituminous coal, North-Central Texas: potential for coalbed methane resource development

The most recent U.S. Geological Survey National Coal Resources Data System (NCRDS) activities completed for the State of Texas by the Bureau of Economic Geology (BEG) focused on Wilcox Group deep coal (lignite) resources, including defining coalbed methane exploration fairways in East-Central Texas (Tyler and Scott, 1999) and deep-basin coal (lignite) in Wilcox Group, Sabine Uplift, East Texas: potential for unconventional coalbed methane resource development (Kim and Ruppel, 2001). The major objectives of these projects were to provide high-quality, organized digital information and interpretations on the location, quality, and quantity of the coal to be mined in the Wilcox Group, Texas Gulf Coast area, during the next several decades to meet the needs of the region and the nation for reliable, low-cost, environmentally compatible energy.

The first commercial coalbed methane field in Texas, the Sacatosa coalbed methane field in Maverick County, was announced in 2001 by The Exploration Company. This field is currently being produced from bituminous coal and carbonaceous shale of the Upper Cretaceous Olmos Formation in the Maverick Basin. Although the Pennsylvanian bituminous coals of North-Central Texas are of a rank higher than that of Texas Gulf Coast lignites and are comparable to Olmos bituminous coals, very little current information exists on their occurrence, distribution, geological setting, or future potential for coalbed methane development. More detailed and updated information on the coal resource in this region is essential for inclusion in the NCRDS, utilizing digital databases of available data as well as digitized maps compiled in a Geographic Information System (GIS) platform.

The Pennsylvanian bituminous coals of North-Central Texas are of higher rank and thereby have higher Btu values than Texas Gulf Coast lignites. Moreover, they are also closer to the major energy user market of the Dallas-Fort Worth area. However, owing to their high sulfur/ash content and thin beds, commercial mining and potential for coalbed methane in these coals is limited.