U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2009–3012

March 2009

Oil Shale Assessment Project Fact Sheet

Assessment of In-Place Oil Shale Resources of the Green 

River Formation, Piceance Basin, Western Colorado

Printed on recycled paper

Introduction

The U.S. Geological Survey 

(USGS) recently completed a 

reassessment of in-place oil shale 

resources, regardless of richness, in the Eocene Green River 

Formation in the Piceance Basin, 

western Colorado (fig. 1). A 

considerable amount of oil-yield 

data has been collected after previous in-place assessments were 

published (Pitman and Johnson, 

1978; Pitman, 1979; Pitman and 

others, 1989), and these data 

were incorporated into this new 

assessment. About twice as many 

oil-yield data points were used, 

and several additional oil shale 

intervals were included that were 

not assessed previously for lack 

of data. Oil yields are measured 

using the Fischer assay method. 

The Fischer assay method is a 

standardized laboratory test for 

determining the oil yield from oil 

shale that has been almost universally used to determine oil yields 

for Green River Formation oil 

shales (Stanfield and Frost, 1949; 

ASTM, 1980). Fischer assay 

does not necessarily measure the 

maximum amount of oil that an 

oil shale can produce, and there 

are retorting methods that yield 

more than the Fischer assay yield. 

However, the oil yields achieved 

by other technologies are typically reported as a percentage of 

the Fischer assay oil yield, and 

thus Fischer assay is still considered the standard by which other 

methods are compared.

U sing a geology-based assessment methodology, the U.S. Geological Survey estimated a total of 1.525 trillion barrels of oil in place 

in seventeen oil shale zones in the Eocene Green River Formation in the Piceance Basin, western 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

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

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R 96 W R 95 W

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108°30' 108°0'

40°0'

39°30'

0 3 6 12 MILES

COLORADO

0 5 10 2.5 KILOMETERS

Piceance

Basin

EXPLANATION

Top of Mahogany zone

Base of Parachute Creek Member,

Green River Formation

Control point

Figure 1. Map showing distribution of oil shale deposits in the Eocene Green River Formation, 

Piceance Basin, Colorado. Control points used in resource assessment are shown.
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

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

Depth in feet Oil yield (gallons per ton)

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. 

Methodology

The oil shale interval in the Piceance 

Basin is subdivided into seventeen 

“rich” and “lean” zones (fig. 2) that were 

assessed separately. These zones, originally defined by Cashion and Donnell 

(1972), are roughly time-stratigraphic 

units consisting of distinctive, laterally 

continuous sequences of rich and lean 

oil shale beds that can be traced throughout much of the Piceance Basin. In this 

assessment, a spatial interpolation and 

extrapolation method for generating 

resource maps and computing resource 

volumes was used—the Radial Basis 

Function (RBF) in ArcGIS GeoStatistical Analyst (Environmental Systems 

Research Institute, Inc. (ESRI), Redlands, 

Calif., 2006, version 9.2).

The RBF method in GeoStatistical 

Analyst is an exact interpolator; it will 

honor all data points without introducing 

errors at those locations. Where it is 

important for the modeling method to 

honor the measured values, RBF can also 

extrapolate values above or below the 

actual values away from the data-point 

locations. The final resource models for 

each oil shale zone were created using a 

sampling method containing ten moving 

window sectors with eight neighbors in 

each sector.

Although the RBF method does not 

generate as complete an error estimate 

as kriging, it does give the difference 

between the predicted and measured 

value for each control point, and it does 

give an overall difference value for an 

entire oil shale zone model. To obtain the 

difference between the predicted value 

and the measured value, the RBF method 

predicts a value at a given control point 

from the nearest control points (in this 

assessment, eight neighbors are used) 

without knowing the actual value measured at that control point. That predicted 

value is then compared with the measured value, and the difference between 

the two is calculated.

Resource Summary

Table 1 lists the estimated total 

in-place oil for each oil shale zone in 

each township (36 mi2

) in the Piceance 

Basin. An “NA” on the resource table 

means that a particular zone was not 

assessed in that township due either to 

not being present or because of inadequate control. Richest oil shale zones in 
EXPLANATION

Total-in place shale oil resource—in millions of barrels

< 15,000

15,000–25,000

25,000–50,000

50,000–65,000

> 65,000

Top of Mahogany zone

Base of Parachute Creek Member

Total in-place shale oil resource—

by township, in millions of barrels 74430

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

69 367

584

4,177

5,020 2,056 224

2,444

1,347 5,451

1,544

1,290 3,334

689 2,588

4,977

10,492

20,284 9,833 9,161 491

1,851 4,468

17,894 24,305

35,113 31,331

27,288

17,091

926

9,643

29,650 39,030 48,512 46,928 38,641

9,591 93 9,248

37,246 54,308, 64,779 58,562 41,267 4,139 3,903

50,265 69,927 74,430 60,565 27,986

353 15,478

19,072 18,746 1942 120

56,283 73,271 68,167 46,360

15,199 27,160

41,772 58,144 39,787

10,580

6037

108°30' 108°00'

40°00'

39°30'

0 3 6 12 MILES

COLORADO

0 5 10 2.5 KILOMETERS

References

American Society for Testing and Materials (ASTM), 1980, Standard method of 

test for oil from oil shale: Annual Book 

of ASTM Standards, Part 25, Designation D 3904–80, p. 513–515.

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 oilshale zones in the Green River Formation, Piceance Creek basin, Colorado: 

Colorado School of Mines Quarterly, 

v. 65, p. 73–87.

Pitman, J.K., 1979, Isopach, structure 

contour, and resource maps of the R-6 

oil shale zone, Green River Formation, Piceance Creek basin, Colorado: 

U.S. Geological Survey Miscellaneous 

Field Investigations Map MF–1069, 

scale 1:126,720.

Pitman, J.K., and Johnson, R.C., 1978, 

Isopach, structure contour, and 

resource maps of the Mahogany oilshale zone, Green River Formation, 

Piceance Creek basin, Colorado: U.S. 

Geological Survey Miscellaneous 

Field Investigations Map MF–958, 

scale 1:126,720. 

Pitman, J.K., Pierce, F.W., and Grundy, 

W.D., 1989, Thickness, oil-yield, 

and kriged resource estimates for 

the Eocene Green River Formation, 

Piceance Creek basin, Colorado: U.S. 

Geological Survey Oil and Gas Investigations Chart OC–132.

Stanfield, K.E., and Frost, I.C., 1949, 

Method of assaying oil shale by a 

modified Fischer retort: U.S. Bureau of 

Mines Report of Investigations 4477.

Figure 3. Map showing total in-place oil in millions of barrels as assessed for each 

township in the Piceance Basin, Colorado.

the basin are, in ascending stratigraphic 

order, (1) R-1 zone, 195.4 billion barrels; 

(2) R-5 zone, 198.2 billion barrels; 

(3) R-6 zone, 185.4 billion barrels; 

(4) Mahogany zone, 191.7 billion barrels; and (5) interval from Bed 44 to 

A-groove with 189.7 billion barrels. Total 

in-place oil in the seventeen oil shale 

zones assessed is 1.525 trillion barrels (table 1) or about 50 percent larger 

than the previous in-place assessment 

of about one trillion barrels. Almost all 

of this increase is due to (1) new areas 

being assessed that had too little data to 

assess in the previous assessment, and 

(2) new intervals being assessed that 

were not assessed previously. Much of 

this previously unassessed resource is of 

low grade. Figure 3 shows the total oil in 

place for all oil shale zones combined in 

each township in the basin. The richest 

resources are in Tps. 1 and 2 S., Rs. 97 

and 98 W. with a combined total of nearly 

286 billion barrels of oil in place.
Township and Range 1N. 96W. 1N. 97W. 1N. 98W. 1N. 99W. 1N. 100W. 2N. 97W. 2N. 98W. 2N. 99W. 2N.100W. 1S. 95W.

R-0 zone 90.71 1,309.35 3,437.06 2,961.75 493.07 153.73 1,577.62 1,737.70 10.66 458.31

L-0 zone 78.62 291.73 347.06 223.74 37.09 21.48 137.50 131.64 0.85 81.79

R-1 1,474.42 5,233.07 6,010.24 5,711.78 1,198.22 235.43 2,590.34 3,194.78 26.34 1,644.14

L-1 88.66 413.01 401.78 400.10 82.38 23.06 181.75 223.72 1.67 253.50

R-2 531.28 1,995.89 3,041.92 2,393.75 460.87 145.58 1,350.17 1,502.56 10.93 941.00

L-2 173.20 657.99 1,306.47 933.54 142.62 47.13 532.77 560.72 3.70 469.14

R-3 467.19 2,301.64 3,891.74 3,106.60 482.95 119.14 1,321.60 1,612.73 12.13 698.68

L-3 204.32 726.38 1,317.69 820.37 118.69 35.92 435.71 406.37 2.54 313.86

R-4 1,155.68 4,241.89 6,682.88 5,121.74 782.50 243.59 1,841.36 2,168.90 17.86 1,861.57

L-4 590.49 2,634.00 4,156.20 2,614.72 400.65 100.60 818.33 846.96 7.37 918.81

R-5 1,867.63 6,313.40 9,373.94 6,041.55 980.27 321.64 2,489.14 2,358.30 18.03 2,711.60

L-5 634.13 2,000.49 3,276.53 2,060.38 369.63 96.24 1,163.47 1,250.38 8.29 1,196.01

R-6 1,612.99 5,764.13 7,794.81 5,052.84 260.56 216.10 2,503.07 1,616.96 NA 1,762.02

B-groove 78.29 219.57 231.56 136.24 6.14 6.85 82.27 63.10 NA 81.41

Mahogany 1,505.32 5,581.22 6,700.01 4,031.95 212.84 171.40 1,639.46 1,311.13 NA 1,688.44

A-Groove 27.33 102.76 173.95 160.76 8.49 3.88 81.50 86.04 NA 118.61

Bed 44-A-groove NA NA NA NA NA NA NA NA NA NA

Township and Range 1S. 96W. 1S. 97W. 1S. 98W. 1S. 99W. 1S. 100W. 2S. 94W. 2S. 95W. 2S. 96W. 2S. 97W. 2S. 98W.

R-0 zone 1,306.03 2,895.85 4,807.90 3,977.93 1,964.36 15.91 1,286.65 2,467.07 3,570.45 4,323.48

L-0 zone 271.22 448.85 460.33 286.16 162.63 2.42 178.49 358.50 508.63 354.29

R-1 5,125.46 6,068.66 5,327.17 5,697.93 3,998.57 64.98 4,416.89 6,331.14 6,012.89 5,684.98

L-1 651.28 631.33 512.15 591.72 376.60 7.81 452.88 677.64 582.45 562.62

R-2 2,296.15 3,562.77 4,017.47 2,851.52 1,637.28 29.54 1,827.29 3,093.13 3,778.05 3,376.42

L-2 1,192.26 1,539.67 1,504.35 1,185.05 473.64 12.73 769.42 1,315.28 1,420.65 1,411.00

R-3 2,552.27 5,236.09 6,462.24 4,329.57 1,176.29 16.47 1,289.44 2,999.68 4,813.80 5,177.65

L-3 954.77 1,396.08 1,415.69 1,145.20 344.37 8.93 517.76 1,031.55 1,569.08 1,287.36

R-4 5,192.26 7,977.04 8,922.47 6,739.63 2,046.91 52.05 2,936.51 5,327.00 7,722.11 6,879.68

L-4 2,862.56 5,220.36 6,087.86 3,809.77 1,241.66 26.04 1,567.83 2,792.61 4,003.38 4,406.57

R-5 7,548.34 12,056.60 13,357.50 10,141.90 3,471.16 76.57 4,128.26 7,192.46 11,062.40 11,177.00

L-5 2,672.97 3,238.02 4,023.31 2,741.84 1,262.56 39.50 2,062.85 2,840.82 3,204.27 2,691.17

R-6 6,580.23 8,520.93 7,849.06 6,226.68 2,998.86 NA 3,038.56 6,985.57 7,655.86 6,617.41

B-groove 300.18 361.61 299.04 244.49 104.70 NA 99.32 195.26 233.28 281.61

Mahogany 6,549.13 8,747.78 8,034.57 6,151.92 2,581.55 NA 3,219.13 6,843.01 7,983.07 7,124.94

A-Groove 305.33 265.20 189.83 161.46 89.71 NA 194.31 281.24 228.80 139.03

Bed 44-A-groove NA NA NA NA NA NA NA 9,832.81 10,081.00 8,432.09

Township and Range 2S. 99W. 2S. 100W. 3S. 94W. 3S. 95W. 3S. 96W. 3S. 97W. 3S. 98W. 3S. 99W. 3S. 100W. 4S. 94W.

R-0 zone 3,508.29 1,353.83 78.65 1,438.66 2,936.60 3,548.70 3,696.50 2,960.79 374.62 91.13

L-0 zone 296.48 122.88 12.59 158.24 287.41 398.76 304.33 234.56 31.06 16.07

R-1 5,924.60 3,120.14 331.40 5,038.42 7,690.24 7,209.92 7,159.30 6,438.08 906.36 419.32

L-1 430.51 202.11 27.93 355.33 691.40 876.16 719.79 456.45 69.40 16.08

R-2 2,624.66 936.63 153.48 1,476.81 3,139.00 3,900.50 3,443.69 1,664.15 140.58 181.71

L-2 1,007.59 248.45 58.88 480.72 934.41 1,281.79 1,160.34 560.45 31.65 67.75

R-3 3,004.47 470.62 87.63 854.42 2,034.62 3,263.15 2,376.52 1,072.22 57.03 119.55

L-3 744.93 141.34 59.38 457.00 798.27 1,008.67 682.46 301.68 13.97 103.14

R-4 4,122.51 1,183.92 341.07 2,439.39 3,879.44 4,893.66 3,948.71 2,226.10 230.26 603.96

L-4 2,192.05 623.33 168.59 1,289.40 2,056.73 2,586.68 2,053.78 1,252.79 115.55 297.37

R-5 7,090.78 2,112.34 571.96 3,927.01 6,253.97 7,446.49 6,624.39 4,180.00 431.86 1,173.31

L-5 1,594.80 663.53 246.79 1,827.50 2,374.11 2,423.42 1,693.74 1,059.83 104.85 428.26

R-6 4,854.46 2,163.16 433.60 5,927.05 7,757.86 7,376.38 5,840.64 3,931.63 439.85 1,499.46

B-groove 172.29 106.63 16.68 180.35 256.22 459.13 177.12 173.32 34.34 75.70

Mahogany 5,258.36 1,965.48 401.10 6,222.47 7,545.47 7,966.01 6,058.93 4,157.58 436.36 1,465.50

A-Groove 140.26 63.97 18.36 180.31 203.94 176.09 178.40 180.86 15.66 98.85

Bed 44-A-groove 7,297.94 NA 895.04 9,014.21 9,721.99 9,963.75 8,189.66 6,395.67 NA 2,933.40

Table 1. Total in-place shale oil resources by township and oil shale zone in the Parachute Creek Member of the Green River Formation, 

Piceance Basin, Garfield and Rio Blanco Counties, northwest Colorado. Resource values are shown in millions of barrels of shale oil. 

1 barrel of oil = 42 gallons.

[All values calculated by ESRI’s ArcGIS GeoStatistical Analyst extension with a Radial Basis Function (RBF) Multiquadratic Gridding Function; NA, not assessed]
Township and Range 4S. 95W. 4S. 96W. 4S. 97W. 4S. 98W. 4S. 99W. 4S. 100W. 4S. 101W. 5S. 94W. 5S. 95W. 5S. 96W.

R-0 zone 1,190.95 2,449.07 3,270.71 2,739.03 2,268.90 731.13 4.83 143.81 783.69 1,523.76

L-0 zone 109.66 207.75 265.96 218.25 157.91 56.81 0.61 24.26 69.85 126.11

R-1 3,986.71 7,468.62 9,439.64 8,031.78 6,319.22 2,249.36 14.81 592.64 2,606.03 4,985.71

L-1 185.07 415.14 635.22 591.38 381.29 135.20 1.06 11.85 56.93 173.12

R-2 915.45 1,589.77 1,945.46 1,436.89 781.39 113.45 0.01 155.57 306.58 616.89

L-2 268.01 376.91 549.81 283.21 144.60 24.02 0.03 87.70 145.78 190.24

R-3 576.41 897.00 1,030.74 644.40 401.71 76.45 0.04 170.80 326.16 453.05

L-3 349.91 420.61 453.61 369.39 324.22 70.77 0.15 168.44 232.84 266.08

R-4 2,110.90 2,695.35 2,708.38 2,241.35 1,551.64 494.13 3.50 1,051.72 1,459.02 1,700.24

L-4 1,144.45 1,427.76 1,528.54 1,022.19 760.93 230.22 1.36 463.95 742.96 813.06

R-5 4,214.38 4,964.98 4,845.95 3,960.32 2,827.29 1,004.77 10.23 1,802.37 2,881.68 3,243.39

L-5 1,672.03 2,031.25 1,936.79 1,426.39 860.36 246.11 1.42 489.82 1,121.24 1,412.85

R-6 6,579.42 6,915.16 5,773.39 4,227.30 3,107.90 1,207.48 10.28 2,316.05 4,782.84 4,796.21

B-groove 205.57 190.14 180.43 134.39 110.21 63.21 0.31 202.15 180.20 158.64

Mahogany 6,420.54 6,535.60 5,834.74 4,538.40 3,641.75 1,391.08 13.90 3,427.43 4,944.05 4,644.92

A-Groove 198.16 180.22 150.25 148.46 137.51 57.93 0.63 150.12 164.83 116.49

Bed 44-A-groove 8,512.92 8,162.23 7,962.17 7,017.09 5,872.87 2,303.53 29.61 5,832.41 6,483.44 6,110.43

Township and Range 5S. 97W. 5S. 98W. 5S. 99W. 5S. 100W. 5S. 101W. 6S. 94W. 6S. 95W. 6S. 96W. 6S. 97W. 6S. 98W.

R-0 zone 2,150.75 1,558.55 1,193.32 666.57 57.91 1.73 184.51 345.85 1,056.05 629.14

L-0 zone 166.79 122.82 90.24 53.28 6.51 0.74 19.99 31.97 89.02 48.76

R-1 7,082.52 5,272.85 3,777.32 1,941.63 132.59 6.94 576.91 1,111.15 3,362.65 2,004.86

L-1 290.69 275.37 216.70 114.43 8.33 0.47 13.09 29.28 171.56 143.58

R-2 702.37 436.66 249.30 63.30 0.53 2.21 47.90 97.27 316.50 164.67

L-2 198.51 98.50 46.52 13.80 1.42 1.54 32.73 46.70 98.46 40.04

R-3 480.10 315.61 214.88 80.70 4.17 2.67 72.11 112.57 280.96 139.67

L-3 319.98 246.02 200.69 82.31 4.86 3.51 78.13 81.16 160.49 83.16

R-4 1,863.92 1,283.57 904.98 469.14 47.44 28.85 470.38 530.92 1,176.85 567.46

L-4 869.18 514.17 356.79 190.02 19.66 8.95 160.69 199.34 367.25 195.92

R-5 3,538.30 2,274.38 1,629.68 967.75 119.44 37.54 682.66 878.18 1,983.84 1,048.54

L-5 1,285.61 869.30 579.08 245.10 17.13 13.12 288.17 374.98 738.65 313.68

R-6 4,096.45 2,705.87 2,060.04 1,129.54 103.18 75.15 1,454.55 1,468.84 2,311.66 1,106.72

B-groove 167.32 141.40 83.44 47.04 3.33 6.50 135.56 56.10 100.90 62.27

Mahogany 4,640.82 3,082.83 2,422.31 1,288.56 135.30 104.50 2,010.70 1,919.93 3,328.92 1,631.06

A-Groove 133.57 98.79 90.31 67.24 7.94 4.11 71.48 45.46 87.81 49.26

Bed 44-A-groove 7,126.06 5,008.44 3,778.77 2,223.04 256.33 192.60 2,861.28 2,503.13 4,652.46 2,263.30

Township and Range 6S. 99W. 6S. 100W. 6S. 101W. 7S. 93W. 7S. 94W. 7S. 95W. 7S. 96W. 7S. 97W. 7S. 98W. 7S. 99W.

R-0 zone 331.72 324.22 127.53 NA NA 0.98 57.35 240.43 79.72 167.10

L-0 zone 24.83 27.33 10.06 NA 2.02 2.25 5.67 23.18 6.46 12.92

R-1 1,033.23 842.07 259.20 NA NA 5.49 170.29 702.02 208.36 431.75

L-1 67.50 52.27 17.11 NA NA 0.35 5.38 27.46 15.85 32.23

R-2 71.33 36.44 5.37 NA NA 0.41 21.26 90.28 23.38 38.75

L-2 13.05 7.46 1.92 NA 2.22 1.86 6.00 22.31 4.70 5.69

R-3 76.40 61.36 15.26 NA 0.28 2.96 21.96 87.78 20.81 47.37

L-3 48.09 43.38 14.04 NA 3.01 3.52 9.71 34.68 8.94 19.28

R-4 249.84 216.19 90.76 0.08 160.74 60.73 90.02 335.77 79.17 120.98

L-4 73.91 64.29 35.53 0.01 23.88 7.99 11.63 41.34 11.35 13.02

R-5 436.44 415.46 206.62 0.06 134.50 55.77 118.59 462.31 122.81 188.51

L-5 137.73 103.65 33.19 0.03 67.44 30.71 44.17 153.38 32.01 43.00

R-6 533.44 503.57 219.28 0.27 584.06 221.55 200.09 658.07 152.07 255.79

B-groove 28.70 25.65 10.20 0.09 153.34 42.83 11.09 33.38 9.97 17.35

Mahogany 755.48 655.30 279.00 0.56 704.19 303.46 323.31 1,058.71 227.38 435.37

A-Groove 23.81 36.41 19.02 0.04 59.87 14.21 9.19 33.48 14.51 26.37

Bed 44-A-groove 1,071.83 1,053.47 507.00 1.28 1,438.67 534.87 438.60 1,446.49 329.64 588.19

Table 1. Total in-place shale oil resources by township and oil shale zone in the Parachute Creek Member of the Green River Formation, 

Piceance Basin, Garfield and Rio Blanco Counties, northwest Colorado. Resource values are shown in millions of barrels of shale oil. 

1 barrel of oil = 42 gallons.—Continued

[All values calculated by ESRI’s ArcGIS GeoStatistical Analyst extension with a Radial Basis Function (RBF) Multiquadratic Gridding Function; NA, not assessed]
Township and Range 7S. 100W. 7S. 101W. 8S. 93W. 8S. 94W. 8S. 95W. 8S. 96W. 8S. 99W. 8S. 100W. 8S. 101W. 9S. 94W.

R-0 zone 197.84 50.86 NA NA 0.60 0.02 36.74 16.17 1.76 NA

L-0 zone 17.99 5.36 NA 2.70 6.66 0.09 2.84 1.49 0.20 NA

R-1 336.29 58.70 NA NA 5.10 0.20 53.15 16.53 0.58 NA

L-1 25.11 5.02 NA NA 0.58 0.05 4.94 1.68 0.10 NA

R-2 21.52 2.00 NA NA 1.53 0.09 7.18 1.96 0.09 NA

L-2 5.42 1.24 0.27 3.40 6.50 0.10 1.26 0.56 0.07 NA

R-3 35.82 5.58 NA 0.03 8.33 0.17 8.54 2.68 0.12 NA

L-3 19.28 4.16 NA 1.69 8.85 0.12 3.24 1.20 0.10 NA

R-4 92.92 24.05 83.82 201.04 161.28 1.18 21.91 5.54 0.24 0.33

L-4 17.73 9.45 13.08 24.52 17.33 0.12 NA 0.16 0.09 0.03

R-5 206.45 74.18 61.91 149.61 128.43 0.94 37.37 14.73 1.81 0.18

L-5 33.56 6.97 27.05 87.16 79.02 0.60 4.65 0.70 0.01 0.14

R-6 280.38 77.45 348.55 902.56 730.24 7.04 74.79 25.82 2.74 2.07

B-groove 20.72 5.23 119.81 251.71 157.13 1.29 5.58 2.47 0.20 0.52

Mahogany 522.75 136.93 405.64 1,072.02 1,009.07 11.01 130.34 54.14 5.34 2.25

A-Groove 30.20 8.61 45.04 79.98 28.90 0.28 10.06 3.89 0.40 0.12

Bed 44-A-groove 724.33 212.91 950.54 2,243.21 1,827.53 18.65 181.76 74.26 8.16 4.53

Township and Range 9S. 95W. 9S. 96W. Grand Total By Township:

R-0 zone NA NA 83,400

L-0 zone 0.64 0.14 8,300

R-1 NA NA 195,400

L-1 0.14 0.06 15,100

R-2 0.16 0.01 66,800

L-2 0.66 0.14 24,200

R-3 0.75 0.13 68,100

L-3 0.81 0.15 22,500

R-4 9.95 1.27 127,200

L-4 0.93 0.12 69,100

R-5 6.66 0.65 198,200

L-5 5.21 0.67 66,100

R-6 65.22 12.21 185,400

B-groove 13.50 2.50 7,800

Mahogany 94.43 18.55 191,700

A-Groove 2.61 0.59 6,300

Bed 44-A-groove 164.85 31.84 189,700

Piceance Basin Grand Total 1,525,200

Table 1. Total in-place shale oil resources by township and oil shale zone in the Parachute Creek Member of the Green River Formation, 

Piceance Basin, Garfield and Rio Blanco Counties, northwest Colorado. Resource values are shown in millions of barrels of shale oil. 

1 barrel of oil = 42 gallons.—Continued

[All values calculated by ESRI’s ArcGIS GeoStatistical Analyst extension with a Radial Basis Function (RBF) Multiquadratic Gridding Function; NA, not assessed]

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 Team website: 

http://energy.cr.usgs.gov/other/oil_shale/.

Contact Information

For further information contact Ronald C. Johnson 

(rcjohnson@usgs.gov), T.J. Mercier (tmercier@usgs.gov), 

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

Michael P. Pantea (mpantea@usgs.gov), or Jesse G. Self 

(jself@usgs.gov).