Vitrinite Reflectance Data for Cretaceous Marine Shales 

and Coals in the Bighorn Basin, North-Central Wyoming 

and South-Central Montana

By Mark J. Pawlewicz and Thomas M. Finn

Open-File Report 2012–1254

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2012 

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Suggested citation:

Pawlewicz, M.J., and Finn, T.M., 2012, Vitrinite reflectance data for Cretaceous marine shales and

coals in the Bighorn Basin, north-central Wyoming and south-central Montana: U.S. Geological Survey 

Open-File Report 2012–1254, 11 p.

Any use of trade, product, or firm names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government. 

Although this report is in the public domain, permission must be secured from the individual 

copyright owners to reproduce any copyrighted material contained within this report.
iii

Contents

Introduction.................................................................................................................................................................... 1

References Cited........................................................................................................................................................... 2

Figures

1. Map of the Rocky Mountain region showing Laramide basins ................................................................................ 4

2. Index map of the Bighorn Basin .............................................................................................................................. 5

3. Stratigraphic chart of uppermost Jurassic to lower Tertiary rocks in the Bighorn Basin .......................................... 6

Table

1. Vitrinite reflectance data for the Bighorn Basin, Wyoming....................................................................................... 7
1

Vitrinite Reflectance Data for Cretaceous Marine Shales 

and Coals in the Bighorn Basin, North-Central Wyoming 

and South-Central Montana

By Mark J. Pawlewicz and Thomas M. Finn

Introduction

The Bighorn Basin is a large Laramide (Late Cretaceous through Eocene) structural and 

sedimentary basin that encompasses about 10,400 square miles in north-central Wyoming and southcentral Montana (fig. 1). The basin is bounded on the northeast by the Pryor Mountains, on the east by 

the Bighorn Mountains, and on the south by the Owl Creek Mountains (fig. 2). The north boundary, as 

defined in this report, includes a zone of faulting and folding referred to as the Nye-Bowler lineament 

(Wilson, 1936). The northwest and west margins are formed by the Beartooth Mountains and Absaroka 

Range, respectively (fig. 2).

Important conventional oil and gas resources have been discovered and produced from reservoirs 

ranging in age from Cambrian through Tertiary (Fox and Dolton, 1989; 1996a, b; De Bruin, 1993). In 

addition, a potential unconventional basin-centered gas accumulation may be present in Cretaceous 

reservoirs (Johnson and Finn, 1998; Johnson and others, 1999; Surdam and others, 1997; Finn and 

others, 2010). In recent years, advances and success in horizontal drilling and multi-stage fracture 

stimulation have led to an increase in exploration and completion of wells in marine shales in other 

Rocky Mountain Laramide basins that were traditionally thought of as hydrocarbon source rocks. 

Important parameters that control hydrocarbon production from these shales include: reservoir 

thickness, amount and type of organic matter, and thermal maturity (Milici, 1993; Curtis, 2002). The 

purpose of this report is to present new vitrinite reflectance data collected from Cretaceous marine 

shales and coals in the Bighorn Basin to better characterize the thermal maturity and petroleum potential 

of these rocks. These new data supplement previously published data by Hagen (1986), Nuccio and 

Finn (1998), Yin (1997), and Finn and Pawlewicz (2007). 

Ninety-eight samples from Lower Cretaceous and lowermost Upper Cretaceous strata (fig. 3) 

were collected from well cuttings from wells stored at the U.S. Geological Survey (USGS) Core 

Research Center in Lakewood, Colorado. Sample locations are shown on figure 2. All samples were 

analyzed by vitrinite reflectance to determine levels of thermal maturation. Preparation of samples for 

reflectance analysis required (1) crushing the larger pieces into 0.25- to 1-millimeter pieces, (2) casting 

the pieces with epoxy in pre-cut and drilled plugs, and (3) curing the samples overnight. Subsequently, 

a four-step grinding and polishing process was implemented that included sanding with progressively 

finer sandpaper (60 to 600 grit) followed by a two-step polishing process (0.3 and 0.05 micron). 

Vitrinite reflectance measurements were determined at 500 X magnification using plane-polarized 

incident white light and a 546-nanometer monochromatic filter in immersion oil. For samples 

containing sufficiently high quality vitrinite, at least 25 measurements were recorded. For samples of 

poorer quality, either due to a poor polish or to the presence of mineral or other inorganic material, 

fewer measurements were recorded. Analytical results are given in table 1. 
2

References Cited

Curtis, J.B., 2002, Fractured shale-gas systems: American Association of Petroleum Geologists Bulletin, 

v. 86, no. 11, p. 1,921–1,938. 

De Bruin, R.H., 1993, Overview of oil and gas geology of Wyoming, in Snoke, A.W., Steidtmann, J.R., 

and Roberts, S.M., eds., Geology of Wyoming: Geological Survey of Wyoming Memoir No. 5, 

p. 836–873. 

Dickinson, W.R., Klute, M.A., Hayes, M.J., Janecke, S.U., Lundin, E.R., McKittrick, M.A., and 

Olivares, M.D., 1988, Paleographic and paleotectonic setting of Laramide sedimentary basins in the 

central Rocky Mountain region: Geological Society of America Bulletin, v. 100, p. 1,023–1,039. 

Finn, T.M., and Pawlewicz, M.J., 2007, New vitrinite reflectance data for the Bighorn Basin, northcentral Wyoming and south-central Montana: U.S. Geological Survey Open-File Report 2007–1246, 

4 p. 

Finn, T.M., Kirschbaum, M.A., Roberts, S.B., Condon, S.M., Roberts, L.N.R., and Johnson, R.C., 2010, 

Cretaceous-Tertiary Composite Total Petroleum System (503402), Bighorn Basin, Wyoming and 

Montana, Petroleum Systems and Geologic Assessment of Oil and Gas Resources in the Bighorn 

Basin Province, Wyoming and Montana: U.S. Geological Survey Digital Data Series DDS–69–V, 

chap. 3, 146 p., CD–ROM.

 Fox, J.E., and Dolton, G.L., 1989, Petroleum geology of the Wind River and Bighorn Basins, Wyoming 

and Montana: U.S. Geological Survey Open-File Report 87–450P, 41 p. 

Fox, J.E., and Dolton, G.L., 1996a, Bighorn Basin Province, in Gautier, D.L., Dolton, G.L., Takahashi, 

K.I., and Varnes, K.L., eds., National assessment of United States oil and gas resources—Results, 

methodology, and supporting data: U.S. Geological Survey Digital Data Series DDS–30, Release 2, 

CD–ROM.

Fox, J.E., and Dolton, G.L., 1996b, Petroleum geology of the Bighorn Basin, north-central Wyoming 

and south-central Montana, in Bowen, C.E., Kirkwood, S.C., and Miller, T.S., eds., Resources of the 

Bighorn Basin: Wyoming Geological Association Guidebook, p. 19–39. 

Green, G.N., and Drouillard, P.H., 1994, The digital geologic map of Wyoming in ARC/INFO format: 

U.S. Geological Survey Open-File Report 94–425, scale 1:500,000. 

 Hagen, E.S., 1986, Hydrocarbon maturation in Laramide-style basins—Constraints from the northern 

Bighorn Basin, Wyoming and Montana: Laramie, University of Wyoming, Ph.D. dissertation, 215 p. 

Johnson, R.C., and Finn, T.M., 1998, Is there a basin-centered gas accumulation in Upper Cretaceous 

rocks in the Bighorn Basin?, in Keefer, W.R., and Goolsby, J.E., eds., Cretaceous and Lower Tertiary 

rocks of the Bighorn Basin, Wyoming and Montana: Wyoming Geological Association Guidebook, 

p. 257–273. 

Johnson, R.C., Crovelli, R.A., Lowell, B.G., and Finn, T.M., 1999, An assessment of in-place gas 

resources in the low-permeability basin-centered gas accumulation of the Bighorn Basin, Wyoming 

and Montana: U.S. Geological Survey Open-File Report 99–315–A, 123 p. 

Milici, R.C., 1993, Autogenic gas (self sourced) from shales—An example from the Appalachian Basin: 

U.S. Geological Professional Paper 1570, p. 253–278. 

Nuccio, V.F., and Finn, T.M., 1998, Thermal maturity and petroleum generation history of Cretaceous 

and Tertiary source rocks, Bighorn Basin, Wyoming and Montana, in Keefer, W.R., and Goolsby, 

J.E., eds., Cretaceous and Lower Tertiary rocks of the Bighorn Basin, Wyoming and Montana: 

Wyoming Geological Association Guidebook, p. 211–231. 

Raines, G.L., and Johnson, B.R., 1995, Digital representation of the Montana state geologic map—A 

contribution to the Interior Colombia River basin ecosystem management project: U.S. Geological 

Survey Open-File Report 95–691, 20 p. 
3

Surdam, R.C., Jiao, Z.S., and Heasler, H.P., 1997, Anomalously pressured gas compartments in 

Cretaceous rocks of the Laramide basins of Wyoming—A new class of hydrocarbon accumulation, 

in Surdam, R.C., ed., Seals, traps, and the petroleum system: American Association of Petroleum 

Geologists Memoir 67, p. 199–222. 

Wilson, C.W., Jr., 1936, Geology of the Nye-Bowler lineament, Stillwater and Carbon Counties, 

Montana: American Association of Petroleum Geologists Bulletin, v. 20, no. 9, p. 1,161–1,188. 

Yin, Peigui, 1997, Source rock maturation and diagenetic modeling in Badger Basin, in Campen, E.R., 

ed., Bighorn Basin—50 Years on the Frontier, Part 2: Yellowstone Bighorn Research AssociationWyoming Geological Association-Montana Geological Association, 1997 Field Trip and 

Symposium, p. 41–44. 
4

Figure 1. Map of the Rocky Mountain region extending from southern Montana to northern New Mexico showing 

locations of Laramide sedimentary and structural basins and intervening uplifts. Modified from Dickinson and 

others (1988).
5

Figure 2. Map showing general outline of the Bighorn Basin, bordering mountain ranges, distribution of major 

rock units, and sample localities. Province boundary from Finn and others (2010). Outcrops from Green and 

Drouillard (1994), and Raines and Johnson (1995). Numbers refer to column 1 (location) in table 1. 
6

Figure 3. Generalized stratigraphic chart of uppermost Jurassic, Cretaceous, and lower Tertiary rocks in the 

Bighorn Basin.
7

Table 1. Vitrinite reflectance (Ro) data and locations for cuttings samples from wells drilled for oil and gas exploration and production in the Bighorn 

Basin, north-central Wyoming and south-central Montana. Map no. refers to sample location numbers shown on figure 2.

[API, well number assigned by American Petroleum Institute; Tnsp., township; Rng., range; Sec., section; Lith., lithology; %Ro, vitrinite reflectance 

measurement; n, number of readings per sample; nr, no reading. Queried (?) where uncertain. Depth is in feet.]

Map

no.

API Tnsp. Rng. Sec. Operator Well Top 

depth 

Bottom 

depth Formation Lith. %Ro n 

1 49043050090000 42N 89W 5 Superior Oil 24-5 Unit Orchard 550 560 Cody shale 0.49 2 

1 49043050090000 42N 89W 5 Superior Oil 24-5 Unit Orchard 1,070 1,080 Frontier shale 0.60 3 

1 49043050090000 42N 89W 5 Superior Oil 24-5 Unit Orchard 1,820 1,830 Mowry shale 0.61 6 

1 49043050090000 42N 89W 5 Superior Oil 24-5 Unit Orchard 2,050 2,060 Thermopolis shale 0.67 1 

 

2 49043202510000 43N 88W 20 Ashland Exploration 1-20 Chabot-Govt. 300 360 Frontier shale 0.45 4 

2 49043202510000 43N 88W 20 Ashland Exploration 1-20 Chabot-Govt. 540 570 Mowry shale nr 

2 49043202510000 43N 88W 20 Ashland Exploration 1-20 Chabot-Govt. 720 750 Mowry shale nr 

2 49043202510000 43N 88W 20 Ashland Exploration 1-20 Chabot-Govt. 940 970 Thermopolis shale 0.75 6 

 

3 49043050610000 44N 92W 32 Continental Oil 1 Govt. Mann 360 370 Cody shale 0.59 9 

3 49043050610000 44N 92W 32 Continental Oil 1 Govt. Mann 1,080 1,090 Frontier shale 0.73 11

3 49043050610000 44N 92W 32 Continental Oil 1 Govt. Mann 1,740 1,750 Mowry shale 0.73 11

3 49043050610000 44N 92W 32 Continental Oil 1 Govt. Mann 2,010 2,020 Thermopolis shale 0.97 9 

 

4 49017200830000 44N 94W 31 Bagdad Oil 1 Lyke 250 280 Cody shale 0.54 8 

4 49017200830000 44N 94W 31 Bagdad Oil 1 Lyke 1,330 1,360 Mowry shale 0.55 1 

4 49017200830000 44N 94W 31 Bagdad Oil 1 Lyke 1,600 1,630 Thermopolis shale 0.37 1 

 

5 49017058630000 44N 97W 7 Westates Petroleum 2-7 Lewis 720 740 Frontier shale 0.64 4 

5 49017058630000 44N 97W 7 Westates Petroleum 2-7 Lewis 1,040 1,080 Mowry shale nr 

5 49017058630000 44N 97W 7 Westates Petroleum 2-7 Lewis 1,200 1,220 Mowry shale 0.67 7 

5 49017058630000 44N 97W 7 Westates Petroleum 2-7 Lewis 1,450 1,470 Thermopolis shale nr 
8

Table 1. Vitrinite reflectance (Ro) data and locations for cuttings samples from wells drilled for oil and gas exploration and production in the Bighorn 

Basin, north-central Wyoming and south-central Montana. Map no. refers to sample location numbers shown on figure 2.—Continued

[API, well number assigned by American Petroleum Institute; Tnsp., township; Rng., range; Sec., section; Lith., lithology; %Ro, vitrinite reflectance 

measurement; n, number of readings per sample; nr, no reading. Queried (?) where uncertain. Depth is in feet.]

Map

no.

API Tnsp. Rng. Sec. Operator Well Top 

depth 

Bottom 

depth Formation Lith. %Ro n 

6 49043205120000 45N 90W 15 Pike Resources 1-15 Federal 4,780 4,810 Cody shale 0.86 8 

6 49043205120000 45N 90W 15 Pike Resources 1-15 Federal 6,100 6,120 Frontier shale 0.97 1 

6 49043205120000 45N 90W 15 Pike Resources 1-15 Federal 6,800 6,830 Mowry shale 0.86 5 

6 49043205120000 45N 90W 15 Pike Resources 1-15 Federal 7,040 7,060 Thermopolis shale 0.93 7 

 

7 49017206620000 45N 99W 5 Apache Corporation 5-16 Federal 3,180 3,210 Cody shale 0.99 4 

7 49017206620000 45N 99W 5 Apache Corporation 5-16 Federal 4,560 4,570 Frontier shale 0.76 12

7 49017206620000 45N 99W 5 Apache Corporation 5-16 Federal 5,420 5,430 Mowry shale 0.75 11

7 49017206620000 45N 99W 5 Apache Corporation 5-16 Federal 5,750 5,760 Thermopolis shale 0.73 5 

 

8 49043201380000 46N 89W 6 Chorney Oil 2 Shoal Unit 5,030 5,040 Frontier shale 0.75 6 

8 49043201380000 46N 89W 6 Chorney Oil 2 Shoal Unit 5,270 5,280 Frontier shale 0.98 5 

8 49043201380000 46N 89W 6 Chorney Oil 2 Shoal Unit 5,750 5,760 Mowry shale 0.90 12

8 49043201380000 46N 89W 6 Chorney Oil 2 Shoal Unit 6,000 6,020 Thermopolis shale 0.73 10

 

9 49017060990000 46N 97W 29 Midwest Oil 1 Gywnn Ranch 4,870 4,900 Cody shale 0.98 9 

9 49017060990000 46N 97W 29 Midwest Oil 1 Gywnn Ranch 6,230 6,250 Frontier shale 1.07 9 

9 49017060990000 46N 97W 29 Midwest Oil 1 Gywnn Ranch 6,950 6,970 Mowry shale 0.97 12

9 49017060990000 46N 97W 29 Midwest Oil 1 Gywnn Ranch 7,250 7,280 Thermopolis shale 1.05 8 

 

10 49043203090000 47N 94W 31 National Coop 1-31 Federal 9,290 9,320 Cody shale nr

10 49043203090000 47N 94W 31 National Coop 1-31 Federal 10,100 10,120 Cody shale 1.16 14

10 49043203090000 47N 94W 31 National Coop 1-31 Federal 10,810 10,820 Frontier shale 1.23 14

10 49043203090000 47N 94W 31 National Coop 1-31 Federal 11,460 11,480 Mowry shale 1.36 12

10 49043203090000 47N 94W 31 National Coop 1-31 Federal 11,710 11,720 Thermopolis shale 1.29 4 
9

Table 1. Vitrinite reflectance (Ro) data and locations for cuttings samples from wells drilled for oil and gas exploration and production in the Bighorn 

Basin, north-central Wyoming and south-central Montana. Map no. refers to sample location numbers shown on figure 2.—Continued

[API, well number assigned by American Petroleum Institute; Tnsp., township; Rng., range; Sec., section; Lith., lithology; %Ro, vitrinite reflectance 

measurement; n, number of readings per sample; nr, no reading. Queried (?) where uncertain. Depth is in feet.]

Map

no.

API Tnsp. Rng. Sec. Operator Well Top 

depth 

Bottom 

depth Formation Lith. %Ro n 

11 49029052770000 48N 101W 5 Heep Oil Rawhide Unit 2 700 710 Cody shale nr 

11 49029052770000 48N 101W 5 Heep Oil Rawhide Unit 2 1,760 1,770 Frontier shale 0.84 1 

11 49029052770000 48N 101W 5 Heep Oil Rawhide Unit 2 2,530 2,540 Mowry shale 0.71 3 

11 49029052770000 48N 101W 5 Heep Oil Rawhide Unit 2 2,850 2,860 Thermopolis shale 0.52 4 

 

12 49003051760000 49N 91W 15 Chandler & Simpson 1 Empire 580 600 Frontier shale 0.37 8 

12 49003051760000 49N 91W 15 Chandler & Simpson 1 Empire 790 820 Mowry shale 0.51 9 

12 49003051760000 49N 91W 15 Chandler & Simpson 1 Empire 1,000 1,030 Mowry shale 0.56 8 

12 49003051760000 49N 91W 15 Chandler & Simpson 1 Empire 1,230 1,260 Thermopolis shale nr 

12 49003051760000 49N 91W 15 Chandler & Simpson 1 Empire 1,430 1,450 Cloverly shale 0.66 6 

 

13 49003204660000 49N 94W 11 Excel Energy 1-11 Dobie Creek 8,550 8,570 Cody shale 1.07 9 

13 49003204660000 49N 94W 11 Excel Energy 1-11 Dobie Creek 9,790 9,820 Frontier shale 1.12 7 

13 49003204660000 49N 94W 11 Excel Energy 1-11 Dobie Creek 10,460 10,500 Mowry shale 1.14 10

13 49003204660000 49N 94W 11 Excel Energy 1-11 Dobie Creek 10,730 10,740 Thermopolis shale 1.21 7 

 

14 49029207390000 49N 100W 20 Panther Exploration 2 Bar TL 4,380 4,410 Cody shale 1.25 7 

14 49029207390000 49N 100W 20 Panther Exploration 2 Bar TL 5,290 5,300 Frontier shale 1.19 4 

14 49029207390000 49N 100W 20 Panther Exploration 2 Bar TL 6,140 6,160 Mowry shale 0.98 15

14 49029207390000 49N 100W 20 Panther Exploration 2 Bar TL 6,510 6,540 Thermopolis shale 1.26 7 

 

15 49003055300000 51N 92W 2 Amerada 1 White Sheep 540 550 Cody shale 0.63 4 

15 49003055300000 51N 92W 2 Amerada 1 White Sheep 1,070 1,080 Frontier shale 0.64 16

15 49003055300000 51N 92W 2 Amerada 1 White Sheep 1,690 1,700 Mowry shale 0.76 5 

15 49003055300000 51N 92W 2 Amerada 1 White Sheep 1,960 1,970 Thermopolis shale 0.78 1 
10

Table 1. Vitrinite reflectance (Ro) data and locations for cuttings samples from wells drilled for oil and gas exploration and production in the Bighorn 

Basin, north-central Wyoming and south-central Montana. Map no. refers to sample location numbers shown on figure 2.—Continued

[API, well number assigned by American Petroleum Institute; Tnsp., township; Rng., range; Sec., section; Lith., lithology; %Ro, vitrinite reflectance 

measurement; n, number of readings per sample; nr, no reading. Queried (?) where uncertain. Depth is in feet.]

Map

no.

API Tnsp. Rng. Sec. Operator Well Top 

depth 

Bottom 

depth Formation Lith. %Ro n 

16 49029210090000 51N 100W 2 Hunt/Impel 1 Katrine Loch 18,760 18,770 Cody shale 1.86 7 

16 49029210090000 51N 100W 2 Hunt/Impel 1 Katrine Loch 19,530 19,540 Frontier shale 1.72 2 

16 49029210090000 51N 100W 2 Hunt/Impel 1 Katrine Loch 20,300 20,310 Mowry shale 2.10 11

16 49029210090000 51N 100W 2 Hunt/Impel 1 Katrine Loch 20,620 20,630 Thermopolis shale 1.85 5 

 

17 49003203160000 52N 95W 26 Gulf Oil 1 Otto Federal 9,950 9,960 Cody shale 1.05 11

17 49003203160000 52N 95W 26 Gulf Oil 1 Otto Federal 11,330 11,360 Frontier shale 1.34 10

17 49003203160000 52N 95W 26 Gulf Oil 1 Otto Federal 11,900 11,910 Mowry shale 1.36 9 

17 49003203160000 52N 95W 26 Gulf Oil 1 Otto Federal 12,140 12,150 Thermopolis shale 1.43 15

 

18 49003057770000 53N 96W 1 Sinclair Oil & Gas 1 Govt. 9,200 9,220 Cody shale 0.55 21

18 49003057770000 53N 96W 1 Sinclair Oil & Gas 1 Govt. 10,250 10,280 Frontier shale 1.52 12

18 49003057770000 53N 96W 1 Sinclair Oil & Gas 1 Govt. 10,940 10,970 Mowry shale 1.23 20

18 49003057770000 53N 96W 1 Sinclair Oil & Gas 1 Govt. 11,270 11,290 Thermopolis shale 1.67 14

 

19 49029058940000 55N 99W 3 Tidewater Oil 1 Atteberry 8,520 8,540 Cody shale 1.26 6 

19 49029058940000 55N 99W 3 Tidewater Oil 1 Atteberry 9,500 9,510 Frontier shale 1.00 7 

19 49029058940000 55N 99W 3 Tidewater Oil 1 Atteberry 10,450 10,470 Mowry shale 1.30 4 

19 49029058940000 55N 99W 3 Tidewater Oil 1 Atteberry 10,700 10,710 Thermopolis shale 1.26 8 

 

20 49029059970000 56N 98W 1 C.E. Brehm 1 Deaton Govt. 2,840 2,860 Frontier shale 0.63 3 

20 49029059970000 56N 98W 1 C.E. Brehm 1 Deaton Govt. 3,240 3,260 Frontier shale 0.63 11

20 49029059970000 56N 98W 1 C.E. Brehm 1 Deaton Govt. 3,780 3,800 Mowry shale 0.53 6 

20 49029059970000 56N 98W 1 C.E. Brehm 1 Deaton Govt. 4,170 4,200 Thermopolis shale 0.90 6 
11

Table 1. Vitrinite reflectance (Ro) data and locations for cuttings samples from wells drilled for oil and gas exploration and production in the Bighorn 

Basin, north-central Wyoming and south-central Montana. Map no. refers to sample location numbers shown on figure 2.—Continued

[API, well number assigned by American Petroleum Institute; Tnsp., township; Rng., range; Sec., section; Lith., lithology; %Ro, vitrinite reflectance 

measurement; n, number of readings per sample; nr, no reading. Queried (?) where uncertain. Depth is in feet.]

Map

no.

API Tnsp. Rng. Sec. Operator Well Top 

depth 

Bottom 

depth Formation Lith. %Ro n 

21 49003205680000 57N 96W 27 Forest Oil 1 Stevens 830 840 Mowry shale 0.58 7 

21 49003205680000 57N 96W 27 Forest Oil 1 Stevens 1,100 1,130 Mowry shale 0.61 4 

21 49003205680000 57N 96W 27 Forest Oil 1 Stevens 1,400 1,430 Thermopolis shale 0.66 7 

21 49003205680000 57N 96W 27 Forest Oil 1 Stevens 1,550 1,560 Cloverly shale nr 

 

22 49029065930000 58N 98W 23 Continental 6 Pacific 900 930 Frontier shale nr 

22 49029065930000 58N 98W 23 Continental 6 Pacific 1,090 1,110 Mowry shale 0.67 2 

22 49029065930000 58N 98W 23 Continental 6 Pacific 1,230 1,250 Mowry shale 0.80 10

 

23 25009051910000 7S 21E 3 Ohio Oil Company 18 N.P. 2,900 2,910 lower 

Mesaverde coal 0.60 25

23 25009051910000 7S 21E 3 Ohio Oil Company 18 N.P. 3,520 3,570 Cody coal? 0.55 25

23 25009051910000 7S 21E 3 Ohio Oil Company 18 N.P. 4,120 4,155 Frontier coal/carb 0.55 21

23 25009051910000 7S 21E 3 Ohio Oil Company 18 N.P. 4,990 5,010 Mowry shale 0.58 2 

23 25009051910000 7S 21E 3 Ohio Oil Company 18 N.P. 5,360 5,380 Thermopolis shale 0.54 25

 

24 25009211550000 8S 23E 9 Arco 1 Hunt Creek 2,610 2,640 lower 

Mesaverde coal 0.54 11

24 25009211550000 8S 23E 9 Arco 1 Hunt Creek 3,600 3,630 Cody shale 0.87 4 

24 25009211550000 8S 23E 9 Arco 1 Hunt Creek 4,500 4,520 Frontier coal/carb 0.55 27

24 25009211550000 8S 23E 9 Arco 1 Hunt Creek 5,310 5,330 Mowry shale 0.74 6 

24 25009211550000 8S 23E 9 Arco 1 Hunt Creek 5,730 5,750 Thermopolis shale 0.87 4