San Juan Basin

U.S. Department of the Interior

U.S. Geological Survey

Printed on recycled paper

Introduction

The U.S. Geological Survey (USGS) recently completed an 

assessment of the potential for undiscovered oil and gas resources 

of five of six priority provinces (fig. 1) to meet the requirements 

of the Energy Policy and Conservation Act of 2000 (EPCA 2000). 

The assessment results for the Paradox Basin Province are from 

Dolton and Fox (1996). The assessment of each province is based 

on the geologic elements of each Total Petroleum System defined 

in the province, including hydrocarbon source rocks (source-rock 

maturation, hydrocarbon generation and migration), reservoir rocks 

(sequence stratigraphy and petrophysical properties), and hydrocarbon traps (trap formation and timing). Using this geologic framework, the USGS quantitatively estimated the undiscovered oil and 

gas resources within each province (table 1).

Resource Summary

The USGS assessed undiscovered conventional oil and gas and 

continuous (unconventional) oil and gas. The USGS estimated a mean 

of 183 trillion cubic feet of gas (TCFG), a mean of 2,350 million 

barrels of oil (MMBO), and a mean of 3,160 million barrels of total 

natural gas liquids (MMBNGL) in six provinces. About 92 percent 

(169 TCFG) of the undiscovered gas resource is continuous, and about 

8 percent (13 TCFG) is conventional (table 1). Of the 169 TCFG 

of undiscovered continuous gas at the mean, about 42 TCFG (or 25 

percent) is estimated to be coal-bed gas. Volumes of undiscovered 

continuous gas resources are estimated to be far greater than undiscovered conventional gas resources in the Southwestern Wyoming, San 

Juan, Uinta-Piceance, and Powder River Provinces; only the Montana 

Thrust Belt Province and the Southwestern Wyoming Province contain significant undiscovered conventional gas resources (table 1).

Of the 2,350 MMB of undiscovered oil at the mean, about 837 

MMB (36 percent) is estimated to be undiscovered continuous oil, 

and 1,513 MMB (64 percent) is undiscovered conventional oil. About 

75 percent (1,131 MMBO) of the undiscovered conventional oil is in 

the Powder River Basin Province.

For Further Information

Supporting geologic studies o

Assessment Units, and reports o

2000 province assessments, are 

available at the USGS Central E

http://energy.cr.

USGS EPCA 2000 Assessmen

C.J. Schenk (Task Leader; sc

R.R. Charpentier, S.M. Condon, 

R.F. Dubiel, T.S. Dyman, T.M. F

M.E. Henry, R.D. Hettinger, A.C

R.C. Johnson, J. Kibler, M.A. K

P.H. Nelson, V.F. Nuccio, W.J. P

J.L. Ridgley, L.N.R. Roberts, an

Reference Cited

Dolton, G.L., and Fox, J.E., 1996, P

in Gautier, D.L., Dolton, G.L., T

1995 National Assessment of 

methodology, and supporting 

Data Series DDS-30, one CD-

Figure 1. Location of six Energy Poli

FS-149-02.indd 1 
2.80 16.20 37.50 21.10 8,585.99 14,335.40 23,903.15 15,051.13 0.00 

7.00 17.76 35.92 19.10 31.35 87.03 175.31 93.33 0.45 

5.20 43.30 124.20 58.10 27.21 66.21 135.49 71.82 0.93 

5.20 43.30 124.20 58.10 41,015.03 49,929.85 61,488.02 50,419.45 91.52 

7.30 22.60 66.40 27.80 20.60 59.80 164.90 72.00 1.00 

66.90 100.50 151.00 103.60 590.10 2,028.90 5,211.40 2,348.80 16.50 

66.90 100.50 151.00 103.60 34.90 59.10 99.90 62.20 1.90 

52,574.00 79,075.70 121,731.00 82,169.10 1,275.60 

7.15 19.09 40.44 20.39 8.77 27.74 70.09 32.11 0.49 

135.53 217.49 349.03 226.67 59.01 162.31 366.71 181.15 0.93 

24.83 37.57 56.84 38.78 35.72 60.74 103.29 63.99 2.23 

116.99 189.32 306.38 197.61 12,118.77 20,060.53 33,875.52 21,147.04 16.49 

131.35 895.05 3,306.56 1,512.69 2,023.48 10,981.25 31,663.35 13,623.80 58.3

417.83 760.72 1,510.88 836.88 114,862.65 164,172.29 242,605.62 169,580.25 1,339.

549.18 1,655.77 4,817.44 2,349.57 116,886.13 175,153.54 274,268.97 183,204.05 1,458.

Gas

Oil

Gas

Gas

Oil

Gas

Oil

Gas

Oil

Gas

Oil

Gas

Total Continuous

Resources

San Juan Basin Province

Uinta-Piceance Province

Southwestern Wyoming 

Province

Conventional Resources

Conventional Resources

Conventional Resources

Continuous Resources

Continuous Resources

Continuous Resources

Total Undiscovered

Oil and Gas Resources

Total Conventional

Resources

FS-149-02.indd 2