U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2004–3092

September 2004

National Assessment of Oil and Gas 

Assessment of Undiscovered Carboniferous Coal-Bed Gas 

Resources of the Appalachian Basin and Black Warrior Basin 

Provinces, 2002

Printed on recycled paper

Introduction

Almost all coal beds contain gases within internal pore spaces 

and fractures. These gases, which consist mostly of methane, are 

generally hazardous to mining operations and may form explosive 

mixtures with oxygen where they are not properly vented from 

underground coal mining operations. In places, the gas is so abundant that it constitutes an economic resource and is produced from 

wells. Wells are drilled into unmined coal, which is then fractured 

artificially in order to release the gas to the well bore in relatively 

large quantities. Alternatively, wells drain mine gases from the broken down rock (gob) associated with underground coal mining.

Coalbed Methane

Coalbed methane (CBM) occurs in coal beds of Mississippian 

and Pennsylvanian (Carboniferous) age in the Appalachian basin, 

which extends almost continuously from New York to Alabama. In 

general, the basin includes three structural subbasins: the Dunkard 

basin in Pennsylvania, Ohio, and northern West Virginia; the 

Pocahontas basin in southern West Virginia, eastern Kentucky, and 

southwestern Virginia; and the Black Warrior basin in Alabama 

and Mississippi (fig. 1). For assessment purposes, the Appalachian 

basin was divided into two assessment provinces: the Appalachian 

Basin Province from New York to Alabama, and the Black Warrior 

Basin Province in Alabama and Mississippi (fig. 1, table 1). By far, 

most of the coalbed methane produced in the entire Appalachian 

basin has come from the Black Warrior Basin Province.

Methane degasification in advance of underground mining 

began in the early 1970s in the Black Warrior Basin Province, and 

in the late 1970s and early 1980s in the Pocahontas Basin Assessment Unit (AU) of the Appalachian Basin Province in an effort to 

improve mine safety conditions in deeply buried coal beds. At first, 

vertical ventilation holes were drilled into the Blue Creek coal bed 

in Alabama and Pocahontas No. 3 coal bed in Virginia, and the gas 

that was produced from coal beds in advance of mining, or from 

gob wells drilled into old works after mining, was vented into the 

atmosphere. Upon recognition of the value of the resource and 

resolution of ownership issues, production of CBM commenced 

in Alabama in 1980 and in Virginia in 1988. Coalbed methane 

production from the Pocahontas No. 3 coal bed began in southern 

West Virginia in 1995.

By 2002, annual production of CBM in the Black Warrior 

Basin Province of Alabama had increased to more than 110 billion 

cubic feet (Bcf) of gas from 3,357 wells. In the Appalachian Basin 

Figure 1. Appalachian basin coalbed methane. Although the Appalachian Basin Province extends northward into New York, no coal-bearing units 

are found north of Pennsylvania.

West

East

Michigan

Illinois Indiana Ohio

Kentucky

Tennessee

Mississippi Alabama

Georgia

South Carolina

North Carolina

New York

Pennsylvania

Virginia

Del.

Md.

N.J.

Ark.

Mo.

Iowa 42 ̊

38 ̊

34 ̊

92 ̊ 88 ̊ 84 ̊ 80 ̊ 76 ̊

0 100 Miles

West Virginia

EXPLANATION

Boundary of Appalachian Basin Province

Carboniferous Coal-bed Gas Total Petroleum System

Anthracite and Semi-Anthracite Assessment Unit

Dunkard Basin Assessment Units

Pocahontas Basin Assessment Unit

Central Appalachian Shelf Assessment Unit

Pottsville Coal-bed Gas Total Petroleum System

Cahaba Basin Assessment Unit

Boundary of Black Warrior Province

Pottsville Coal-Bed Gas Total Petroleum System

Black Warrior Basin Assessment Unit
Province, 2,359 wells in the Pocahontas Basin AU in Virginia 

and southern West Virginia produced 65.8 Bcf; and 252 wells 

in the East Dunkard (Folded) AU in Pennsylvania and northern 

West Virginia produced 1.4 Bcf of CBM. As of 2003, cumulative 

production from the Black Warrior Basin Province was about 1.5 

trillion cubic feet (Tcf) of CBM, and cumulative production from 

the Pocahontas Basin and East Dunkard (Folded) Basin AUs was 

about 439 Bcf and 8.5 Bcf, respectively. Although the gas is chiefly 

methane, small amounts of other gases may be present. Gob gas 

produced from previously mined areas (coal mine methane) commonly contains relatively large amounts of nitrogen, oxygen, and 

carbon dioxide.

Assessment Results

The results of the U.S. Geological Surveyʼs 2002 assessment 

of the Appalachian Basin and Black Warrior Basin Provinces for 

coalbed methane are shown in table 1. These two provinces were 

subdivided into assessment units and only the units that were currently productive were assessed. The assessment was conducted 

with the assumption that the bulk of the exploration and discoveries 

in the next 30 years would be within the Black Warrior basin, Pocahontas basin, and the East Dunkard (Folded) Assessment Units.

Approximately 15.5 Tcf of technically recoverable undiscovered methane resources were assessed at the statistical mean in the 

Appalachian Basin and Black Warrior Provinces overall. Assessment units in the Appalachian Basin with no commercial development or with little reliable data at the time of the assessment were 

not assessed quantitatively. These areas, however, are recognized 

as having considerable potential for future development because 

of the wide distribution of coal and the occurrences of marginally 

economic amounts of gas within them.

Selected References

Hatch, J.R., Pawlewicz, M.J., Charpentier, R.R., Cook, T.A., Crovelli, R.A., 

Klett, T.R., Pollastro, R.M., and Schenk, C.J., 2003, Assessment of undiscovered oil and gas resources of the Black Warrior Basin Province, 2002: 

U.S. Geological Survey Fact Sheet FS–038–03, 2 p.

Markowski, A.K., 1998, Coalbed methane resource potential and current 

prospects in Pennsylvania: International Journal of Coal Geology, v. 38, 

p. 137–159.

Milici, R.C., 2004, Assessment of Appalachian Basin Oil and Gas 

Resources; Carboniferous coal-bed gas total petroleum system: U.S. 

Geological Survey Open-File Report 2004–1272, available only online 

at http://pubs.usgs.gov/of/2004/1272. (Accessed August 17, 2004). [This 

publication provides the geologic data and references supporting the 

assessment.]

Milici, R.C., Ryder, R.T., Swezey, C.S., Charpentier, R.R., Cook, T.A., 

Crovelli, R.A., Klett, T.R., Pollastro, R.M., and Schenk, C.J., 2003, 

Assessment of undiscovered oil and gas resources of the Appalachian 

Basin Province, 2002: U.S. Geological Survey Fact Sheet FS–009–03.

Nolde, J.E., and Spears, David, 1998, A preliminary assessment of in place 

coalbed methane resources in the Virginia portion of the central Appalachian Basin: International Journal of Coal Geology, v. 38, p. 115–136.

Pashin, J.C., and Hinkle, Frank, 1997, Coalbed methane in Alabama: Geological Survey of Alabama Circular 192, 71 p.

Rice, D.D., and Finn, T.M., 1996, Geologic framework and description of 

coalbed gas plays, in Gautier, D.L., Dolton, G.L., Takahashi, K.I., and 

Varnes, K.L., eds., 1995 National assessment of United States oil and gas 

resources; results, methodology, and supporting data: U.S. Geological 

Survey Digital Data Series 30, 1 CD-ROM.

West Virginia Geological and Economic Survey, 2004, Coal-bed methane (CBM) wells: Morgantown, W. Va., West Virginia Geological and 

Economic Survey Web site at http://www.wvgs.wvnet.edu/www/datastat/

datastat.htm. (Accessed August 16, 2004)

By Robert C. Milici and Joseph R. Hatch

For Further Information

CBM Resources of the Appalachian Basin Province:

Robert C. Milici

U.S. Geological Survey

956 National Center

Reston, VA 20192

Telephone: 703-648-6541, E-mail: rmilici@usgs.gov

CBM Resources of the Black Warrior Basin Province:

Joseph R. Hatch

U.S. Geological Survey

Denver Federal Center, MS 977, P.O. Box 25046

Denver, CO 80225

Telephone: 303-235-5418, E-mail: jrhatch@usgs.gov

Assessment Province Total Petroleum System Assessment Unit Total Undiscovered Resources of Gas (BCFG)

F95 F50 F5 Mean

Appalachian Basin Carboniferous Coal-bed Gas Pocahontas Basin 2,929.57 3,552.81 4,308.64 3,577.32

Appalachian Basin Carboniferous Coal-bed Gas East Dunkard (Folded) 2,748.71 4,593.61 7,676.78 4,823.03

Black Warrior Basin Pottsville Coal-bed Gas Black Warrior 4,614.56 6,854.42 10,181.47 7,055.63

Total Assessed Coal-Bed Gas Resources 10,292.84 15,000.84 22,166.89 15,455.98

Appalachian Basin Carboniferous Coal-bed Gas West Dunkard (Unfolded) Not Quantitatively Assessed

Appalachian Basin Carboniferous Coal-bed Gas Central Appalachian Shelf Not Quantitatively Assessed

Appalachian Basin Carboniferous Coal-bed Gas Appalachian Anthracite and Semi-Anthracite Not Quantitatively Assessed

Appalachian Basin Pottsville Coal-bed Gas Cahaba Basin Not Quantitatively Assessed

Table 1. Total undiscovered coalbed methane resources of the Appalachian Basin and Black Warrior Basin Provinces.

[BCFG, bi . Fractiles are additive under the 

assumption of perfect positive correlation.]