U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2010–3041

June 2010

In-Place Oil Shale Resources Underlying Federal Lands in 

the Piceance Basin, Western Colorado

Printed on recycled paper

Introduction 

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

an assessment of in-place oil shale resources that underlie Federal lands in the Eocene Green River Formation in the Piceance 

Basin, western Colorado (fig. 1), incorporating the considerable 

amount of oil-yield data collected since a 1989 USGS in-place 

assessment. The new estimate of in-place oil in the basin is 

about 1.5 trillion barrels for all categories of mineral-rights 

ownership (Johnson and others, 2009), an increase of 50 percent 

over the previous assessment. Most of this increase is due to 

1. Additional areas being assessed that previously had too 

little data for assessment purposes, and 

2. New intervals being assessed. 

Using geographic information systems (GIS) technology, 

several subsets of the 1.5-trillion barrels total were calculated 

by merging the oil shale resource data with Bureau of Land 

Management (BLM) surface and subsurface ownership files 

(BLM, 2009a, b). This resulted in an estimated Federal in-place 

resource of 1.07 trillion barrels (table 1). More than 67 percent 

of the total in-place resource, or 1.027 trillion barrels, is located 

under Federal lands. The map in figure 1 provides a general 

overview of Federal lands in the Piceance Basin; however, it 

should not be used to define title to any specific area, because of 

the complicated nature of surface and mineral estate ownership.

Resources Underlying Federal Lands

The entire oil shale interval in the Piceance Basin is 

subdivided into 17 “rich” and “lean” zones that were assessed 

separately (fig. 2). These zones are roughly time-stratigraphic 

units consisting of distinctive, laterally continuous sequences of 

oil shale beds that can be traced throughout much of the basin. 

More detailed analysis of the resource numbers was performed 

on the 17 zones than was done for the assessment in 2009. 

Table 1 lists several subtotals of the 1.5 trillion barrels total that 

were calculated: 

1. About 920 billion barrels (60 percent) exceed 15 gallons 

per ton (GPT), 

2. About 352 billion barrels (23 percent) exceed 25 GPT, and 

3. About 689 billion barrels (75 percent) of the 15 GPT total 

and about 285 billion barrels (81 percent) of the 25 GPT 

total are under Federal mineral (subsurface) ownership. 

These 15 and 25 GPT estimates include only those areas where 

the weighted average of an entire zone exceeds those minimum cutoffs. In areas where the entire zone does not meet the 

minimum criteria, some oil shale intervals of significant thickness could exist within the zone that exceed these minimum 

cutoffs. For example, a 30-ft interval within an oil shale zone 

might exceed 25 GPT, but if the entire zone averages less than 

25 GPT, these resources are not included in the 15 and 25 GPT 

subtotals, although they might be exploited in the future.

Using a geologic-based assessment methodology, the U.S. Geological Survey estimated an in-place oil shale 

resource of 1.07 trillion barrels under Federal mineral rights, or 70 percent of the total oil shale in place, in 

the Piceance Basin, Colorado. More than 67 percent of the total oil shale in-place resource, or 1.027 trillion 

barrels, is under Federal surface management.

Anvil Points, Piceance Basin, 

northwestern Colorado
R 96 W R 95 W

R 101 W R 100 W R 99 W R 98 W R 97 W R 94 W

T

8

S

T

7

S

R 93 W

T

6

S

T

5

S

T

4

S

T

3

S

T

9

S

R 94 W

R 101 W R 100 W R 99 W R 98 W R 97 W

T

2

S

T

1

S

T

1

N

R 96 W R 95 W

T

2

N

108°30' 108°00'

40°00'

39°30'

GARFIELD COUNTY

RIO BLANCO COUNTY

MOFFAT COUNTY

RIO BLANCO COUNTY

GARFIELD COUNTY

MESA COUNTY

6

13

325

789

64

330

139

65

132

Meeker

Rifle

Parachute

Rio

Blanco

0 6 12 MILES

COLORADO

Piceance

Basin

EXPLANATION

Mahogany ledge outcrop

Base of Parachute Creek Member

Bureau of Land Management Piceance Basin boundaries

U.S. Forest Service

Federal mineral rights

0 5 10 KILOMETERS

70

Figure 1. Map showing Federal surface management and Federal mineral rights of oil shale resources in the Eocene Green River Formation, 

Piceance Basin, Colorado.
Table 1. Oil shale resources under Federally managed lands and under Federal mineral rights in the Piceance Basin, Colorado.

[Resource figures are in millions of barrels; resources are reported to four significant figures and may not equal the sum of the components, because of independent rounding; GPT

Oil shale 

zone

All oil yields Oil yield of 15 gallons per ton or greater Oil yield of 25 

Total oil 

in place 

Federal mineral Federal surface

Oil in 

place 

As 

percent 

of total in 

place

Federal mineral

Oil in 

place 

As 

percent 

of total in 

place

Oil in 

place 

As 

percent 

of total 

in place

Oil in 

place 

As 

percent 

of total in 

place

Oil in 

place 

As 

percent 

of total in 

place

As percent 

of 

≥ 15 GPT

Bed 44 186,500 109,900 59 103,000 55 91,530 49 34,680 19 38

A-groove 6,283 4,394 70 4,178 66 92 1 88 1 96Mahogany zone

191,700 129,600 68 124,200 65 181,000 94 119,900 63 66 108,300 56 

B-groove 7,819 5,463 70 5,256 67 158 2 132 2 83R-6 185,400 127,400 69 122,300 66 139,600 75 97,860 53 70 36,460 20 L-5 66,060 46,900 71 46,660 71 10,650 16 9,256 14 87R-5 198,200 147,600 74 142,200 72 132,300 67 112,000 57 85 61,320 31 L-4 69,130 54,530 79 52,920 77 39,180 57 34,730 50 89 7,155 10 R-4 127,200 97,840 77 94,600 74 103,700 82 85,320 67 82 71,710 56 L-3 22,500 17,580 78 17,030 76 8,395 37 7,672 34 91 83 <1 R-3 68,080 56,480 83 55,040 81 56,150 82 50,150 74 89 27,240 40 L-2 24,220 19,860 82 19,290 80 9,643 40 8,843 37 92 146 1 R-2 66,770 52,350 78 50,700 76 48,110 72 42,220 63 88 28,160 42 L-1 15,070 10,790 72 10,310 68 132 1 88 1 67 1 <1 R-1 195,400 124,900 64 118,300 61 94,480 48 81,770 42 87 10,990 6 L-0 8,265 6,023 73 5,799 70R-0 83,420 58,240 70 55,600 67 5,040 6 4,293 5 85Total 1,522,000 1,070,000 70 1,027,000 67 920,100 60 689,000 45 75 351,600 23 
0 20 40 60 80 100

Arco-Mobil-Equity,

Figure Four 31-1 

Sec. 31, T. 3 S., R. 98 W. 

500

1,000

1,500

2,000

2,500

Top bed 44-

top A-groove

A-groove

Mahogany

zone

B-groove

R-6 zone

L-5 zone

R-5 zone

L-4 zone

R-4 zone

L-3 zone

R-3 zone

L-2 zone

R-2 zone

L-1 zone

R-1 zone

L-0 zone

R-0 zone

Stratigraphic nomenclature for 

oil shale zones from Donnell and Blair 

(1970), Cashion and Donnell (1972) Garden Gulch Member Parachute Creek Member (part) Green River Formation (part)

Oil yield, gallons per ton

Depth, in feet

Rich oil shale zones—Carbonate rich

Lean oil shale zones—Carbonate rich

Rich oil shale zones—Clay rich

Lean oil shale zones—Clay rich

EXPLANATION

References Cited

BLM (Bureau of Land Management), 2009a, Statewide land 

ownership (Colorado)—lst_conflated_poly: Bureau of Land 

Management database, accessed April 13, 2010, at

http://www.blm.gov/co/st/en/BLM_Programs/

geographical_sciences/gis/metadata.html.

BLM (Bureau of Land Management), 2009b, Statewide Federal 

mineral ownership (Colorado)—co_fed_minerals: Bureau 

of Land Management database, accessed April 13, 2010, at 

http://www.blm.gov/co/st/en/BLM_Programs/

geographical_sciences/gis/metadata.html.

Cashion, W.B., and Donnell, J.R., 1972, Chart showing correlation of selected key units in the organic-rich sequence of the 

Green River Formation, Piceance Creek Basin, Colorado, 

and Uinta Basin, Utah: U.S. Geological Survey Oil and Gas 

Investigations Chart OC-65.

Donnell, J.R., and Blair, R.W., 1970, Resource appraisal of 

three rich oil-shale zones in the Green River Formation, 

Piceance Creek Basin, Colorado: Colorado School of Mines 

Quarterly, v. 65, p. 73–87.

Johnson, R.C., Mercier, T.J., Brownfield, M.E., Pantea, M.P., 

and Self, J.G., 2009, Assessment of in-place oil shale 

resources of the Green River Formation, Piceance Basin, 

western Colorado: U.S. Geological Survey Fact Sheet 

2009–3012, 6 p.

For Additional Information

Supporting geologic studies of the oil shale-bearing units, 

assessment units, oil shale analysis, and the methodology used 

in assessing the oil shale resources in the Piceance Basin are in 

progress. Assessment results are available at the USGS Central 

Energy Science Center website at http://energy.cr.usgs.gov/

other/oil_shale/.

Contact Information

For further information contact

Tracey J. Mercier (tmercier@usgs.gov),

Ronald C. Johnson (rcjohnson@usgs.gov),

Michael E. Brownfield (mbrownfield@usgs.gov), or

Jesse G. Self (jself@usgs.gov).

Figure 2. Chart showing oil yield in gallons per ton and the rich 

and lean oil shale zones in the Green River Formation assessed in 

this study.