Figure 2. Diagram illustrating the production of
water (blue) and gas (white) from a coal bed (black) in a typical coal-bed
methane well. Other rock types are shown in yellow. Coal-bed gas and
water are separated at the surface.
|
| Table 1. Coal-bed gas resources of selected Rocky Mountain provinces. The year signifies the date of the latest USGS assessment of each province. |
| [TCFG, trillion cubic feet of gas. F95 represents a 95 percent chance
of at least the amount of resource tabulated; F5 represents a 5 percent
chance of at least the amount of resource tabulated] |
| Province |
Coal-Bed Gas (TCFG)
|
| Uinta-Piceance (2002) |
|
| San Juan (2002) |
|
| Powder River (2002) |
|
| Wind River (1995) |
|
| SW. Wyoming (2002) |
|
| Raton Basin (1995) |
|
| Total |
|
|
|
|
| reassessed most recently in 2002. In the six geologic provinces
assessed for this study, the assessment at present indicates that
about 44.5 trillion cubic feet (TCF) of technically recoverable coal-bed
gas (mean estimate) exists (table 1). The Powder River Basin is estimated
to contain nearly one third (14.2 TCF at the mean) of the undiscovered
coal-bed gas resource. The San Juan Basin, where coal-bed gas has
been produced for 20 years, is estimated to contain about 54% (24.2
TCF) of undiscovered coal-bed gas at the mean. In a national perspec-tive,
coal-bed gas production accounts for about 1.3 TCFG of the 18.5 TCFG
of total natural gas produced annually in the U.S. Although the production
of coal-bed gas is minor compared to natural gas produc-tion from
conventional oil and gas fields, coal-bed gas production is important
regionally, as in provinces of the Rocky Mountain region. Assessment
results can be found at http://energy.cr.usgs.gov/oilgas/noga |
|
| Summary |
| A significant portion of the undiscovered coal-bed gas resource of the U.S. occurs in Rocky Mountain provinces. If the demand for natural gas increases significantly through the next few decades, as expected, coal-bed gas will continue to be an important regional source of natural gas. |
| References Cited |
Gautier, D.L., Dolton, G.L., Takahashi, K.I., and Varnes, K.L.,
1996, 1995 National assessment of United States oil and gas
resources—Results, methodology, and supporting data: U.S. Geological Survey
Digital Data Series DDS-30, Version 2, one CD-ROM.
U.S. Geological Survey
National Oil and Gas Resource Assessment Team, 1995, 1995 National
assessment of United States oil and gas resources: U.S. Geological
Survey Circular 1118, 20 p. |
| For More Information on Coal-Bed
Methane: |
| National Assessmentof Oil and Gas Project |
| C.J.Schenk |
(schenk@usgs.gov) |
| U.S. coal-bed gas resources |
| V.F.Nuccio |
(vnuccio@usgs.gov) |
| Powder River Basin, Raton Basin |
| R.M.Flores |
(rflores@usgs.gov) |
| Wind River Basin, SW Wyoming, Uinta-Piceance Basin |
| R.C.Johnson |
(rcjohnson@usgs.gov) |
| S.B.Roberts |
(sroberts@usgs.gov) |
| T.M.Finn |
(finn@usgs.gov) |
| San Juan Basin |
| J.Ridgley |
(ridgley@usgs.gov) |
|
|
