| Using a geology-based assessment methodology,
the U.S. Geological Survey estimated a mean of 16.5 trillion cubic feet of undiscovered
natural gas, a mean of 1.5 billion barrels of undiscovered oil, and a
mean of 86.5 million barrels of natural gas liquids in the Powder River Basin
Province. |
|
| Introduction |
| The U.S. Geological Survey (USGS) recently completed an assessment
of the potential for undiscovered resources in continuous oil and
gas accumulations of the Powder River Basin Province of northeastern
Wyoming and southeastern Montana (fig. 1). The assessment of continuous
oil and gas resources is based on geologic elements such as hydrocarbon
source rocks (source-rock maturation, hydrocarbon generation and migration),
reservoir rocks (sequence stratigraphy and petrophysical properties),
and hydrocarbon traps (trap formation and timing) in four Total Petroleum
Systems (TPS) identified in the province by the USGS. Six continuous
assessment units and one conventional assessment unit were defi ned
within the TPSs. Estimates of the undiscovered oil and gas resources
in these seven assessment units, along with previous estimates of
undiscovered oil and gas resources in 11 conventional plays within
the province (Dolton and Fox, 1996), are presented in table
1. |
|
| Resource Summary |
| The USGS estimated a mean of 16.5 trillion cubic feet of undiscovered
gas, a mean of 1.5 billion barrels of oil, and a mean of 86.5 million
barrels of total natural gas liquids. Most of the undiscovered gas
resource (94 percent, or 15.5 trillion cubic feet) is continuous (table
1). Of the 15.5 trillion cubic feet of continuous gas at the mean,
about 14.3 trillion cubic feet is estimated to be coal-bed gas in
three AUs of the TertiaryUpper Cretaceous Coal-Bed Methane TPS. The
Cretaceous Biogenic Gas TPS is estimated to contain a mean of 0.78
trillion cubic feet of gas (table
1). The Mowry TPS is estimated to contain a mean of 198 million
barrels of undiscovered continuous oil, and the Niobrara TPS is estimated
to contain a mean of about 227 million barrels of undiscovered continuous
oil, together representing about 27 percent (424 million barrels)
of the total mean undiscovered oil in the province. One-third of the
mean undiscovered oil (33 percent, or 522 million barrels) is estimated
to be in conventional accumulations of the Upper Minnelusa Sandstone
Play (table
1). |
|
| For Further Information |
Supporting geologic studies and reports on the assessment methodology
used in the Powder River Basin Province assessments of
continuous resources are in progress.
Assessment results from 1995
and 2002 are available at the USGS Central Energy Team website:
http://energy.cr.usgs.gov/oilgas/noga/ |
| 
Figure 1. Powder River Basin Province of northeastern
Wyoming and southeastern Montana.
| Powder River Basin Province Assessment
Team: |
| Romeo M. Flores (Task Leader; flores@usgs.gov), Larry O. Anna, Gordon
L. Dolton, James E. Fox, Christopher D. French, Ronald R. Charpentier,
Troy A. Cook, Robert A. Crovelli, Timothy R. Klett, Richard M. Pollastro,
and Christopher J. Schenk. |
| Reference Cited |
| Dolton, G.L., and Fox, J.E., 1996, Powder River Basin Province (033),
in Gautier, D.L., Dolton, G.L., Varnes, K.L., and Takahashi, K.I.,
eds., 1995 National Assessment of United States Oil and Gas
Resources—Results, methodology, and supporting data: U.S.
Geological Survey Digital Data Series DDS-30, one CD-ROM,
Release 2. |
|
