Petroleum Potential of 

Wilderness Lands in 

, Wyoming-Utah-Idaho 

Thrust Belt 

By Richard B. Powers 

P~TROLEUM POTENTIAL OF WILDERNESS LANDS IN THE 

WESTERN UNITED STATES 

GEOLOGICAL SURVEY CIRCULAR 902-N 
j 
CONTENTS 

Page 

Abstract---------------------------------------------------------------------- N1 

Acknowledgments-------------------------------------------------------------- 1 

Introduction------------------------------------------------------------------- 1 

Geologic framework ------------------------------------------------------------ 1 

Petroleum potential factors ------------------------------------------------------ 4 

Reservoirrocks------------------------------------------------------------- 4 

Sourceandsealrocks -------------------------------------------------------- 4 

Structure------------------------------------------------------------------ 7 

Oilandgasfields--------------------------------------------------------------- 7 

Productive trends---------------------------------------------------------- 9 

Qualitative ratings of Wilderness Lands-------------------------------------------- 9 

~ethodsofevaluation-------------------------------------------------------- 9 

Petroleum potential ratings--------------------------------------------------- 11 

Summary--------------------------------------------------------------------- 13 

Referencescited----------~----------------------------------------------------- 13 

ILLUSTRATIONS 

Page 

FIGURE 1. ~ap showing location and boundaries of the Wyoming-Utah-Idaho Thrust Belt province------------------- N2 

2. Index map of Wyoming-Utah-Idaho thrust belt showing principal tectonic features, major thrust faults, oil and 

gas fields, and new-field wildcat discovery wells sit:lce 1975----------------------------------------- 3 

3. Diagrammatic west to east structural cross section in vicinity of Summit County, Utah, and Yellow Creek 

field, Uinta County, Wyoming, showing the relation between an anticline in the "hanging wall" and 

rocks in the "footwall" (subthrust block)------------------------------------------------------- 5 

4. Generalized stratigraphic chart of the Wyoming-Utah-Idaho thrust belt showing productive formations and 

known or potential reservoir and source rocks. (~odified from Hayes, 1976; Powers, 1977; 1983; Lageson and 

others, 1980; and Ver Ploeg and De Bruin, 1982) ------------------------------------------------- 6 

5. Structure contour map of the Whitney Canyon-Carter Creek field, Wyoming----------------------------- 10 

6. Simplified west-east structural cross section across Whitney Canyon-Carter Creek field in the Wyoming-UtahIdaho thrust belt showing hanging wall fold closed against the Tunp thrust ----.:...--..,...------------------- 11 

TABLE 

Page 

TABLE 1. New fields discovered since 1975 and indicated recent new-field wildcat discoveries in the Wyoming-Utah-Idaho 

thrustbelt--------------------------------------------------------------------------------- N8 

III 
PETROLEUM POTENTIAL OF WILDERNESS LANDS IN THE WESTERN UNITED STATES 

Petroleum Potential of Wilderness Lands 

in Wyoming-Utah-Idaho Thrust Belt 

By Richard B. Powers 

ABSTRACT 

Three segments of the North American part of the Cordilleran thrust belt (north of Mexico) produce oil and gas-the 

Canadian Foothills, western Montana, and Wyoming-UtahIdaho thrust belts. Between 1975 and 1983, 26 new (or indicated new) fields (at least 8 of them "giants") were found in the 

Wyoming-Utah-Idaho thrust belt; these fields have an estimated, ultimately recoverable 3.2 billion barrels of oil (BBO) 

and 16.5 trillion cubic feet (TCF) of gas, plus natural gas liquids. Most of this oil and gas is trapped in major (>50 MMBO, 

or >0.3 TCF of gas) and giant (100 MMBO, or 1 TCF of gas) 

fields, and not in numerous, smaller-size fields. This is significant because over 80 percent of the world's discovered oil and 

gas is in giant fields, and giant fields account for as much as 

70 percent of the world's present production. 

Four major thrust plates, which are oriented, generally, 

from north to south, are. recognized in the province. All 26 

fields discovered since 1975 are concentrated mainly in the 

southern one-third of the thrust belt and are located on, and 

controlled by, the folded leading edges of three of the four 

major thrust plates. Six wilderness tracts within the province 

are rated as having a high potential for the occurrence of oil 

and gas, one has a medium potential, and the remainder have 

either zero, low, or unknown oil and gas potential. 

ACKNOWLEDGMENTS 

The many, detailed reports on the surface geology and mineral potential of wilderness areas published by colleagues in the U.S. Geological Survey 

were a valuable source of information. I would like 

particularly to thank Steven S. Oriel for his helpful discussions on the overall surface geology of 

the thrust belt. Jerome W. Boettcher of Exxon 

Co. USA provided me with up-to-date information 

on the status of new-field wildcat gas discoveries 

in the area west of La Barge, Wyoming, that 

aided greatly in the evaluation of tracts in that 

area. 

N1 

INTRODUCTION 

A review has been made of the oil and gas potential of various categories of Wilderness Lands 

in the Wyoming-Utah-IdahoThrust Belt province 

(fig. 1). The types of Wilderness Lands are shown 

on maps of Wyoming, Utah and Idaho prepared 

by the U.S. Bureau of Land Management 

(1981a,b,c). Tract numbers evaluated in the present study are shown on these maps. Six of the 

wilderness tracts have a high oil and gas potential, 

one has a medium potential, and the remainder 

have either zero, low, or unknown oil and gas potential. 

The Wyoming-Utah-Idaho thrust belt straddles 

parts of western Wyoming, north-central Utah, 

and eastern Idaho and covers an area of 15,000 

square miles (fig. 1). The northern boundary is 

placed at the south edge of the Snake River volcanic plain west of Jackson, Wyoming; the southern boundary is at the intersection of the Uinta 

Mountains just east of Salt Lake City; the eastern 

boundary is at the surface trace of the DarbyProspect thrust fault, which separates the structurally deformed thrust belt from the undeformed 

Green River basin on the east; the western boundary is the surface trace of the Willard-Paris thrust 

on the east side of the Bear River Range (fig. 2). 

GEOLOGIC FRAMEWORK 

During a span of geologic time (Paleozoic-early 

Mesozoic) ranging from about 570 to 140 million 

years (m.y.) before the present, more than 60,000 

feet of sand, silt, mud, and limy material was de-
SOUTHWESTERN I I 

EASTERN BASIN 

II 

WYOMING II 

BASINS 

AND RANGE 

0 100 200 MILES 

FIGURE 1.-Map showing location and boundaries of the Wyoming-Utah-Idaho Thrust Belt province in respect to the other 

petroleum provinces in the northern Rocky Mountain region. 

N2 
BASIN 

Pinedale 

• 

BIG PINEY-LaBARGE 

PRODUCING COMPLEX 

GREEN RIVER BASIN 

EXPLANATION 

Quaternary and Tertiary 

volcanic rocks 

Precambrian rocks, 

u ndi ffe rentiated 

..._...., Thrust fault (sawteeth on 

overthrust block) 

, Producing oil and gas fields 

and indicated new discoveries 

0 10 20 30 MILES 

FIGURE 2.-Index map of Wyoming-Utah-Idaho thrust belt showing principal tectonic features, major thrust faults, 

oil and gas fields (numbered), and new-field wildcat discovery wells since 1975. Numbers coded to field names 

are shown on table 1. Cross section A-A ' shown in fig. 3 (Modified from Powers, 1977, 1980; Lamerson and 

Royse 1980; Petroleum Information, 1981; and Ver Ploeg and De Bruin, 1982). Cross section B-B' is shown 

in figure 5. 

N3 
posited in an ocean basin that was located some 

distance west of the present thrust belt. About 

140 m.y. ago, in latest Jurassic time, the ocean 

basin (or miogeosyncline) began to be deformed, 

and the mass of sedimentary rocks within it was 

strongly folded and thrust eastward by compressional forces from the west. Compression continued episodically for about 85 m.y., or until 

early Eocene time (55 m.y.) after which normal 

(extensional) faulting occurred within the thrustfold belt until the present. Eastward horizontal 

movement on most of the individual thrust sheets 

exceeds 5 miles. 

Four major thrust-fault systems are recognized 

in this province and are named after the major 

thrusts involved (fig. 2). They are from oldest to 

youngest, and from west to east: (1) WillardParis, (2) Meade-Crawford, (3) Absaroka, and (4) 

Darby-Prospect-Hogsback (Royse, 1979). Prior to 

horizontal shortening of some 65 miles due to 

west-east folding and thrusting, the width of this 

rock sequence was about 130 miles. The chief 

structural characteristic of this province, as a result of all of the tectonic pushing, sliding, and 

crumpling is that older rocks have been thrust 

over, and now overlie, younger rocks. This is illustrated in a cross section (fig. 3), in which rocks as 

old as Devonian and Cambrian in the hanging wall 

(overthrust block) are thrust over rocks as young 

as Cretaceous in the footwall (subthrust block), 

forming an anticlinal fold, a possible trap for oil 

and gas, in the hanging wall. 

PETROLEUM POTENTIAL FACTORS 

The oil and gas (petroleum) potential of the 

thrust belt, as well as for most sedimentary basins, is controlled by several factors critical to the 

generation, migration, and trapping of petroleum 

and must be present in natural balance, in order 

for discrete hydrocarbon accumulations to occur. 

The most important of these factors are (1) 

number and thickness of porous reservoir rocks, 

(2) organic-rich fine-grained rocks that are the 

source of hydrocarbons, (3) thermal maturation of 

the source rocks that allows the generation and 

expulsion of hydrocarbons, (4) structural or 

stratigraphic traps such as folds (anticlines), 

faults, or lensing of reservoir rocks, (5) tight, 

dense (impermeable) rocks over the trap that act 

as a seal to prevent the upward and lateral escape 

of hydrocarbons, and finally (6) correct timing as 

to generation and migration of hydrocarbons relaN4 

tive to the forming of a trap. All of these factors 

are present in the Wyoming-Utah-Idaho thrust 

belt. 

RESERVOIR ROCKS 

Fifteen formations produce oil or gas in anticlinal traps in the thrust belt~ These formations represent eight different geologic systems, ranging in 

age from Cretaceous through Ordovician (fig. 4). 

In contrast, many producing basins in the United 

States have only one or two formations within a 

single geologic period that are oil or gas bearing. 

Rocks of the Jurassic and Triassic Systems contain six reservoir formations that are productive 

of oil or gas, including the prolific Nugget 

Sandstone,. which is the main oil or gas reservoir 

in 11 fields. Paleozoic rocks contain five productive 

reservoirs ranging in age from the Permian Phosphoria Formation through the Ordovician Bighorn 

Dolomite. These formations are the major gas and 

condensate (light, high gravity crude oil similar to 

natural gasoline) reservoirs in seven recently discovered fields in the thrust belt (table 1, fig. 4). 

The Madison Group of Mississippian age, which is 

the principal Paleozoic reservoir in these fields, 

has substantial intercrystalline porosity developed 

in limestones and dolomites of the Mission Canyon 

Limestone (fig. 4). 

SOURCE AND SEAL ROCKS 

Nine formations in the thrust belt contain possible source rocks ranging from the Cretaceous 

Frontier Formation to the Devonian Darby Formation (fig. 4). However, the only probable source 

rocks, for which documented and published data 

exist, are those of Cretaceous age (Frontier Formation, Aspen Shale, and Bear River Formation). 

Warner (1982) conducted extensive geochemical 

studies and concluded that the oil trapped in 

Jurassic-Triassic reservoir rocks in fields along the 

Ryckman Creek-Pineview structural trend on the 

Absaroka thrust (fig. 2) was generated in source 

rocks in the footwall Cretaceous sequence that 

was overriden by the Absaroka thrust plate about 

75 m.y. ago. This conclusion is supported by data 

from a variety of analytic techniques used to make 

oil-to-oil and oil-to-source rock correlations. The 

source of sour gas (gas high in sulfur content) and 

high-gravity oil in Paleozoic reservoirs in the 

fields along the Whitney Canyon-Carter Creek 

trend west of the Tunp thrust (fig. 2) is more 

difficult to identify with any degree of certainty. 
.Z 

en 

WEST 

A PHILLIPS HATCH #1 

ELEV.7,000 FT 

SEA 

T 

LEVEL 

I 

~ 

.J 

<( 

~ 

(!) 

z 

(!) 

z 

<( 

I: 

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UPPER CRETACEOUS 

LOWER 

·:·:.· 

TRIASSIC 

pENNSYLVANIAN. 

pERMIAN. NIAN 

AND UPPER DEVO 

..... ··>·=::':·:'::·::::::··.:·: . . ···:.':~ 

TRIASSIC 

WASATCH 

EVANSTON 

UPPER DEVONIAN 

MISSISSIPPIAN AND PERMIAN,.PENNSVLVANIAN. 

MIDDLE DEVQNIAN TO CAMBRIAN 

BASAL DETACHMENT 

BASEMENT (PRECAMBRIAN) 

FIELD I TUNP THRUST 

JURASSIC 

WASATCH 

EVANSTON 

EAST 

.r 

SEA 

~~======~,.-LEVEL 

.. ::::-·.:·-:.::.::.-:.: .. _·::-:.:: ·,_;_:_-.. ::_:"_. ... ·.~-: NU.GqET.-·Ss: _·:: ·::'.=:.":·-:--.::·>·::. 

THRUST ~ 

LOWER CRETACEOUS 

JURASS~C 

DARBV (HOGSBACK) THRUST 

0 

0 

HORIZ SCALE 

8000 

2 3 MILES 

~ 

.J 

<( 

~ 

to 

0 

u.. 

~ ARROWS SHOW DIRECTION OF FAULT MOVEMENT 

~IGURE 3.-Diagrammatic west to east structural cross section in vicinity of Summit County, Utah, and Yellow Creek field, Uinta County, Wyoming, showing the relation 

between an anticline in the ''hanging wall" and rocks in the "footwall" (subthrust block). Older Devonian and Cambrian rocks have been thrust over younger Cretaceous 

and Jurassic rocks along the Absaroka thrust fault (basement is not involved in thrusting). (Slightly modified from Royse and others, 1975, Plate II, and Conrad, 1977). 

Line of cross section is shown in figure 2. 
Formation Oil 'lbickness Geologic Age 

or Group or Range Gas 

Tertiary Green R1 ver Fm. 

Wasatch-EvanstonFms. o-8,000' 

Adaville Fm. 6,000'-

8 

Late Billiard Fa. 16,000' Frontier Fm. RSe 

~ Aspen Shale RS ~ • ~ 

Q) Early Bear River Fm. RS* ... 

u 10,000' Gannett Group 

-,. . Stump Fm. R • 500'-

Jurassic Preuss Ss. ~Saltl R * 1,QOO' 

Twin Creek Ls. RS * 1,200'-

IGypsumSpringMbr. 3,500' 

Jurassic(?) R * 500'- and Nugget Ss. 2,000 Triassic (?) 

Triassic Ankareh Fm. R 

lbaynes Fm. RS * 

~ 2,000'-

Early Triassic Woodside Fm. 7,000' 

Dinwoocly Fa. R ~ 

Permian Phosphoria Fm. 2 RS ~ 400'- 5,000' - c 

Pennsylvanian - - - Weber Ss. R :7 750'-4,000' 

Mississippian I C:S a. Mission 'j&nyon R ~ 1,000'- -,o=' Ls. c 

:2"0 .,...~ Lodgepole Ls. RS ~ 7,000' c 

- . . - - - - - -- Devonian Darby lbree Forks Pm~ RS~ 500'-

FM4 Jefferson Fm. c 3,000 

Ordovician Bighorn Dolomite RS9 250'- 2,000' 

Gallatin Fa. 1,500'- Cambrian Gros. Ventre Fa. 5,000' Flathead S~. -- Precambrian Uinta Mtn. Group )20,000' 

e Oil productive ~ Gas with condensate productive c 

14f· Oil and gas productive R- KnoWn or potential reservoir rock 

~ Gas productive S- Known or potential source rock 

1of Maher (1976) larazer li~stone of so~ authors 

2 And equivalent strata ~cally in Wyoming 

FIGURE 4.-Generalized stratigraphic chart of the Wyoming-Utah-Idaho thrust belt showing productive formations and known or potential reservoir and source rocks. (Modified 

from Hayes, 1976; Powers, 1977, 1983; Lageson and others, 1980; and Ver Ploeg and 

De Bruin, 1982.') 

N6 
However, the identical sulfur content and 

chromatographic character of condensate from the 

Paleozoic and Jurassic-Triassic reservoirs suggest 

that both were generated from the same Cretaceous source rocks (Warner, 1982), or possibly at 

the same time from rocks of different ages. 

The key factors that led to the presence of oil 

and gas fields in the thrust belt appear to be (1) 

the presence of an extensive area of organic-rich 

Cretaceous source rocks at peak maturation in the 

footwall of, and in contact with, the Absaroka 

thrust, (2) generation of oil and gas from these 

rocks after being overridden and buried by the 

Absaroka plate, and consequent expulsion of the 

oil and gas, (3) migration of the expelled hydrocarbons laterally and upward into Jurassic, Triassic, 

and Paleozoic reservoir rocks in available hangingwall traps, and (4) sealing over the traps by impermeable shale, anhydrite, or halite (salt) caprocks (Royse, 1979). 

STRUCTURE 

As discussed earlier, a wedge of Paleozoic and 

Mesozoic sedimentary rocks was compressed from 

west to east into a zone about one-half of its original width, resulting in the thrust folds of the present Wyoming-Utah-Idaho thrust belt. However, 

in this province only the sedimentary rock section 

is involved in folding and thrusting and is structurally detached from basement crystalline rocks 

(Precambrian granite) by a regional "decollement." This decollement condition has also been 

referred to as "thin-skinned" structure by Rodgers (1963) in describing folds and faults in a 

thrust belt involving only the upper strata lying 

on a decollement, beneath which the structure differs. In other words, the basement is passive and 

only the overlying sedimentary rock sequence is 

actively involved in the shortening of the total section in the province (fig. 3). Nearly all of the present oil and gas fields in the thrust belt have been 

trapped in asymmetric and overturned anticlinal 

folds in the hanging wall of the Absaroka thrust 

plate. Most of the folds have numerous, additional 

imbricate thrust faults included within their overall configuration. Vertical structural relief or 

amplitude of the traps ranges from 500 to more 

than 4,500 feet, and areal size ranges from about 

3 to more than 50 square miles. The greater the 

vertical relief and area of the fold, the larger the 

amount of oil or gas it can trap. Many of the new 

discoveries in the thrust belt are major fields and 

N7 

some are estimated to be giant fields in size. A 

major field is defined informally as one that is estimat~d to ultimately produce 50 MMBO or more, 

or 300 BCF or more of combustible gas (Johnston, 

1980, p. 1303). A giant field is defined as one that 

is expected to produce more than 100 MMBO, or 

1 TCF of combustible gas (Halbouty, 1980, p. 1). 

Prior to 1975, lack of success in finding oil or 

gas traps in most of the prominent surface anticlines present in the thrust belt eventually led to 

the conclusion that perhaps the structures that 

held oil and gas did not necessarily lie directly beneath the surface structures. The problem then 

became a matter of finding the right tool, or 

method, that would enable explorationists to look 

thousands of feet below the surface and identify 

anticlines similar to those on the surface that 

might trap oil or gas. The problem was solved by 

applying an improved method of subsurface mapping employing advanced seismic-reflection tools 

that were the result of a breakthrough in seismic 

data processing and mapping, coupled with modern, sophisticated computer technology. 

OIL AND GAS FIELDS 

Table 1 summarizes basic data relating to new 

fields and indicated new-field wildcat discoveries 

in the Wyoming-Utah-Idaho thrust belt since 

1975. One of the largest of these fields is the Whitney Canyon-Carter Creek gas field in Uinta and 

Lincoln Counties, Wyoming, located 13 miles 

north of the town of Evanston (fig. 2, table 1). The 

field was discovered in late 1977 on a major northsouth-trending, slightly overturned anticline on 

the hanging wall of the Absaroka thrust plate. 

The overall anticline is actually made up of three 

individual structures with total structural closure 

(vertical relief) exceeding 4,500 feet (fig. 5). The 

anticline is 16 miles long and 4 miles wide occupying an area of 60 square miles (one and one-half 

townships). 

An unusual feature of this field is that production of sour gas, averaging 12 percent hydrogen 

sulfide (H2S), and condensate comes from six separate reservoirs, including the Permian Phosphoria Formation, Pennsylvanian Weber 

Sandstone, Mississippian Mission Canyon and 

Lodgepole Limestones, Devonian Darby Formation and Ordovician Bighorn Dolomite (figs. 4 and 

6). A seventh reservoir, the Triassic Thaynes Formation, which is productive of sweet gas and con-
TABLE 1.-New fields discovered since 1975 and indicated (one well drilled) recent new-field wildcat discoveries in the WyomingUtah-Idaho thrust belt. Numbered location of fields is shown on figure 2. Age of formations is shown on figure 4. (Modified 

and updated from Petroleum Information, 1981, and Ver Ploeg and De Bruin, 1982.) 

Field name and number Producing formations Hydrocarbon type Thrust plate Discovery date 

1. Anschutz Ranch Twin Creek Limestone Sweet gas and condensate Absaroka (east)1 10/78 

Nugget Sandstone Sweet gas and condensate Absaroka (west) 

Weber Sandstone Sour gas and condensate 

2. Anschutz Ranch East Nugget Sandstone Sweet gas and condensate Absaroka (east) 12/79 

3. Cave Creek Phosphoria Formation Sour gas and condensate Absaroka (west) 10179 

Weber Sandstone do 

Mission Canyon Limestone do 

4. Clear Creek Nugget Sandstone Oil and sweet gas Absaroka (east) 08/78 

5. Elkhorn Ridge Twin Creek Limestone Oil and sweet gas Absaroka (east) 09177 

6. Glasscock Hollow Nugget Sandstone Sweet gas and condensate Absaroka (east) 09/80 

7. Hogback Ridge Dinwoody Formation Dry sweet gas Crawford 10/77 

Phosphoria Formation Sour gas 

8. Lodgepole Twin Creek Limestone Oil and sweet gas Absaroka (east) 03177 

Nugget Sandstone do 

9. Mill Creek (temporarily Darby Formation Oil and sweet gas Darby-Hogsback 04/80 

abandoned) 

10. Painter Reservoir Nugget Sandstone Oil and sweet gas Absaroka (east) 10/77 

11. Painter Reservoir East Nugget Sandstone Sweet gas and condensate Absaroka (east) 08179 

12. Pineview Frontier Formation Oil and sweet gas Absaroka (east) 01175 

Stump Formation do 

Twin Creek Limestone do 

Nugget Sandstone do 

13. Red Canyon Weber Sandstone Sour gas and condensate Absaroka (west) 12/79 

14. Ryckman Creek Nugget Sandstone Oil and sweet gas Absaroka (east) 09/76 

Ankareh Formation Sweet gas and condensate 

Thaynes Formation do 

15. Thomas Canyon Phosphoria Formation Sour gas and condensate Absaroka (west) 08/81 

Madison Group do 

16. Whitney Canyon- Thaynes Formation Sweet gas and condensate Absaroka (west) 08/77 

Carter Creek Phosphoria Formation Sour gas imd condensate 

Weber Sandstone do 

Mission Canyon Limestone do 

Lodgepole Limestone do 

Darby Formation do 

Bighorn Dolomite do 

17. Woodruff Narrows Bighorn Dolomite Sour gas and condensate Absaroka (west) 04/81 

18. Yellow Creek Twin Creek Limestone Sweet gas and condensate Absaroka (west) 07/76 

Phosphoria Formation Sour gas and condensate 

Weber Sandstone do 

N8 
TABLE 1.-New fields discovered since 1975 and indicated (one well drilled) recent new-field wildcat discou.eries in the WyomingUtah-Idaho thrust belt. Numbered location of fields is shown on figure 2. Age of formations is shown on figure 4. (Modified 

and updated from Petroleum Information, 1981, and Ver Ploeg and De Bruin, 1982.) -Continued 

Field name and number Producing formations Hydrocarbon type Thrust plate Discovery date 

19. 1Aagard Frontier Formation Oil and sweet gas Absaroka (east) 03/82 

Stump Formation do 

20. Horsetrap Madison Group Sweet gas and condensate Darby-Hogsback 06/82 

21. Lodgepole South Frontier Formation Sweet gas Absaroka (east) 09/78 

22. North Pineview Nugget Sandstone Sweet gas and condensate Absaroka (east) 09/82 

23. Road Hollow Bighorn Dolomite Sour gas and condensate Absaroka (west) 11/81 

24. Ryckman Creek West Ankareh Formation Oil and sweet gas Absaroka (east) 02/82 

25. Coyote Creek Nugget Sandstone Sweet gas and condensate Absaroka (east) 11/82 

26. West Carter Creek Mission Canyon Limestone Sour gas and condensate Absaroka (west) 11/82 

Bighorn Dolomite 

•Position of field east or west of Tunp imbricate thrust of main Absaroka thrust. 

•Numbers 19-26 are indicated new-field wildcat discoveries. 

densate, is the exception in this dominantly sour 

gas field. Depth to production ranges from 9,200 

feet to 14,000 feet in these formations. Warping 

(folding) of the upper, main Absaroka thrust sheet 

has evidently been the main reason for the great 

amount of structural closure on the overall anticline. 

To gain some idea of the productive capability of 

this field, one well, the Amoco-Champlin No. 457-

A (fig. 6), was flow-tested in the Paleozoic reservoirs for a total recovery rate of nearly 75 million 

cubic feet (MMCF) of gas and 1,294 barrels of condensate (B.C.) per day; even more significant is 

the fact that a 30-foot-thick section of the Mission 

Canyon Limestone reservoir, alone, flowed 32 

MMCF of gas per day. 

PRODUCTIVE TRENDS 

A fairly well defined, arcuate northeast-southwest pattern or trend exists of fields discovered in 

the southern part of the thrust belt (fig. 2). In addition, within this trend, a separation occurs between predominantly oil and sweet gas fields in 

Jurassic and Triassic reservoirs east of the Tunp 

thrust and dominantly sour gas and condensate 

fields in Paleozoic reservoirs west of the Tunp 

thrust (fig. 2, table 1). However, all these fields 

are common to the Absaroka thrust trend. Only 

N9 

do 

one gas field, Hogback Ridge, is located on the 

Crawford-Meade thrust trend and only one recently discovered (sweet) gas field in a Mississippian reservoir (Horsetrap field), and three indicated sour gas discoveries (not listed) are located 

on the Darby-Hogsback thrust trend (fig. 2, table 

1). Although temporarily abandoned at present, 

the Mill Creek field (table 1, no. 9) is also located 

on the Darby-Hogsback trend. This two-well field 

seems to be the exception to all of the fairly well 

defined patterns discussed above in that the discovery well flowed 154 barrels of sweet, 46 degree 

A.P.I. gravity green oil from a Paleozoic 

sandstone reservoir (Devonian Three Forks Formation). Interruptions in the established pattern 

of fields, trends, hydrocarbon type, and age of reservoir as shown by the anomalous Mill Creek 

field may indicate the possibilty of a different oil 

and gas field trend on the Darby-Hogsback thrust 

to the north and northwest along the leading edge 

of this thrust plate, as well as the Absaroka thrust 

trend. 

QUALITATIVE RATINGS OF 

WILDERNESS LANDS 

METHODS OF EVALUATION 

Tracts were rated on the basis of available 

geologic information, both published and unpub-
T. 

19 

N. 

T. 

18 

N. 

T. 

17 

N. 

LINCOLN CO. 

AMOCO #1 KEWANEE-FED. 

B 

AMOCO-CHAMPLIN 

457 "A" #1 

R.120W. 

CARTER 

CREEK 

CHEVRON #1-32 FEDERAL 

ANTICLINE 

SCALE 

2 3 4 MILES 

THRUST FAULT 

(SAWTEETH ON 

OVERTHRUST BLOCK) 

R.119W. 

FIGURE 5.--Structure contour map of the Whitney Canyon-Carter Creek field, Wyoming. Contours 

are on top of the Mississippian Mission Canyon Limestone; contour interval is 1,000 ft. Contours 

show the three large anticlines that make up the field. Also shown are field discovery wells (solid 

circle with ray8---{)il and gas productive) on each of the three anticlines. (Modified from Hoffman 

and Balcells-Baldwin, 1982). Cross section B-B' is shown in figure 6. 

NlO 
B 

West 

DEPTH IN FEET 

(SUB SEA) 

6000 

4000 

2000 

-2000 

-4000 

-6000 

-8000 

-10,000 

-12,000 

3-4° 

AMOCO-CHAMPLIN 

457 AMOCO "A." #1 

SWSE 7, 17N-119W 

7026 KB 

-¢-

ABSAROKA 

Up DETACHMENTPER BOUNDARy 

ABSAROKA DETACHMENTLOWER BOUNDARY 

B' 

East 

ARROWS SHOW DIRECTION OF FAULT MOVEMENT 

.... -----------3.5 MILES------------~ 

FIGURE G.-Simplified west-east structural cross section across Whitney Canyon-Carter Creek field in the Wyoming-Utah-Idaho 

thrust belt, showing hanging wall fold closed against the Tunp thrust. Also shows" warping'' (folding) of the main Absaroka 

thrust plate. Black rectangles indicate producing intervals. (Courtesy of Amoco Production Co.) Line of section is shown 

in figures 2 and 5. 

lished, taking into account the distribution and 

types of oil and gas accumulations in producing 

and abandoned fields. The analysis is weighted 

heavily toward the known or interpreted presence 

and distribution of reservoir rocks, petroleumsource rocks, geologic history, and stratigraphic 

and structural style favorable for oil.and gas accumulations in the Wyoming-Utah-Idaho thrust 

belt. 

PETROLEUM POTENTIAL RATINGS 

High potential.-Geologic environment highly 

favorable for occurrence of oil and gas accumulations. Area is near or on trend with existing production from structural and (or) stratigraphic 

traps. 

Medium potential.-Geologic environment 

favorable for the discovery of oil and gas fields. 

Nll 
Contains known reservoir rocks and hydrocarbonsource beds. Includes some areas of sparse subsurface control or areas where known or expected 

field size will be small. 

Low potential.-Geoiogic environment interpreted to have low potential for oil and gas. Includes 

areas of poor or unknown hydrocarbon-source bed 

richness and reservoir quality. Generally includes 

areas of sparse or no well control and (or) expected thin section of sedimentary rocks. 

Zero potential.-Mostly comprises areas with 

exposed Precambrian rocks or very thin sedimentary cover with no potential for occurrence of 

sealed structural or stratigraphic traps. 

Unknown potential.-Generally includes areas 

of no well control where Tertiary volcanic intrusions and volcaniclastic rocks are present on the 

surface. This cover, plus lack of subsurface well 

and geophysical control, makes prediction of hydrocarbon potential nearly impossible. Includes 

some areas where Precambrian igneous and 

metamorphic rocks are thrust over Phanerozoic 

sedimentary rocks of unknown potential. Lack of 

control does not mean that no oil and gas potential 

exists, but only that the potential can not reasonably be determined with present data. 

Six wilderness tracts within the thrust belt are 

rated to have a high oil and gas potential on the 

basis of possessing geologic characteristics favorable for the occurrence of petroleum. These six 

tracts, as identified by the Bureau of Land Management (1981a--c), are discussed in the following 

section for four cluster groupings, three clusters 

in Wyoming and one cluster in Idaho. 

1. Tracts 040--221 and 040--223 (U.S. Bureau of 

Land Mangement, 1981c), in cluster 15 (C. W. 

Spencer, Wyoming, chapter M), western Lincoln 

County, Wyoming.-Two wildcat tests were 

drilled in the northern part of tract 040--221 by 

Gulf Oil Co. and Sohio Petroleum (1978, 1982) on 

the Crawford thrust. Gulf drilled to a total depth 

of 15,992 feet and reported minor gas shows in 

Mesozoic rocks. Sohio set production casing in its 

well and tested perforations in the Permian Phosphoria Formation (fig. 4) at a total depth of 17,131 

feet. Good gas shows were indicated in this well, 

but the amounts were not sufficient to justify commercial production. 

2. Tract 040--110 (U.S. Bureau of Land Mangement 1981c), in cluster 15 (C. W. Spencer, WyomN12 

ing, chapter M), western Sublette County, Wyoming.-Exxon drilled a new-field wildcat discovery 

(Graphite Hollow) within the east half of this tract 

in 1982, on the Darby-Hogsback thrust. The discovery flowed 5 MMCF of low BTU gas (25 percent methane) from the Madison Group (fig. 4) 

below 16,000 feet. In addition, Exxon drilled two 

new-field wildcat discoveries, Lake Ridge and 

Fogarty Creek, directly north of the northern 

boundary of the tract. The Lake Ridge discovery 

well flowed 6 MMCF of low Btu gas from the 

Madison at 16,318 feet, and Fogarty Creek flowed 

20 MMCF of similar type gas from the Madison at 

16,291 feet, including a small percentage of 

helium. 

3. Tract 4--102 (U.S. Bureau of Land Mangement, 1981c), in cluster 17 (C. W. Spencer, 

Wyoming, chapter M), southern Teton County, 

Wyoming.-Only the southwestern portion of this 

tract, which lies between the Darby and Prospect 

thrusts where they form separate thrust sheets in 

the northern part of the thrust belt, is rated as 

having a high potential. Directly east of the tract 

Rainbow Resources Inc. completed a new-field 

wildcat gas discovery in the Frontier Formation 

(fig. 4) in 1977. The well is shut-in at present 

pending future field development. 

4. Tract 4--613 (U.S. Bureau of Land Management, 1981c), in cluster 16 (C. W. Spencer, 

Wyoming, chapter M), and tract W4-613 (U.S. 

Bureau of Land Management, 1981a) in Idaho 

cluster 7 (C. A. Sandberg, Idaho, chapter F).-

These tracts straddle the Wyoming-Idaho State 

line in the vicinity of Alpine, Wyoming, but are 

grouped together for this discussion on the basis 

of. geologic similarity. The Darby thrust trends 

northwest in the eastern part of the tracts and the 

Absaroka thrust parallels the Darby trend in the 

central part of the tracts. A wildcat well, the Allday No. 1 Government, · was drilled in the westernmost part of tract W 4-613 in 1966 to a depth 

of 5, 760 feet immediately northeast of the 

Palisades Creek picnic area in the Targhee N ationa} Forest, Bonneville County, Idaho. Live oil 

shows were encountered in porous and fractured 

Ordovician limestones from 1,252 to 1,256 feet, 

1,348 to 1,354 feet, and 1,368 to 1,375 feet in the 

well; live oil was bleeding from fractures in the 

lower zone. Surface mapping indicates that the 

well was located on the hanging wall (fig.3) of the 
Thompson imbricate thrust above the buried Absaroka thrust plate (fig. 2). Live oil shows at these 

shallow depths are a positive indication that oil 

and gas are being generated and are migrating 

within the rock system on the Absaroka thrust 

plate in this general area. The same formations, 

reservoir and source rocks (fig. 4), and trapping 

structures are present here, as well as a favorable 

thermal-maturation history, in a framework similar to that in the productive southern area of the 

thrust belt (figs. 2 and 3). 

Tracts 34-3 Islands and 34-4 Islands (U.S. Bureau of Land Management, 1981a) in cluster 6 (C. 

A. Sandberg, Idaho, chapter F), eastern Bonneville County, Idaho, are rated to have a medium 

oil and gas potential. The surface area of this cluster consists of volcanic cover (not prospective for 

oil and gas); however several old, shallow wildcat 

wells drilled nearby indicate that sedimentary 

rocks are present in the subsurface. These tracts, 

therefore, are rated as possessing medium oil and 

gas potential. The small part of a tract, referred 

to as cluster 18, in Utah at the western end of the 

Uinta Mountains, is rated as having low petroleum potential. (C. M. Molenaar and C. A. 

Sandberg, Utah, chapter K). The remaining tracts 

in the Wyoming-Utah-Idaho thrust belt.are rated 

to have a zero or unknown petroleum potential. 

SUMMARY 

The Wyoming-Utah-Idaho thrust belt possesses 

the following critical requirements that make it a 

major oil and gas producing province: 

1. The presence of four dominant regional thrust 

trends that act as controlling factors in localizing 

oil and gas fields. 

2. Proved occurrence of similar trap types on the 

hanging wall (overthrust block) of three of the regional thrust trends. 

3. Organic-rich, thermally mature source rocks 

ranging in age from Cretaceous through Devonian. 

4. Thick, porous and permeable clastic and carbonate reservoir rocks productive of oil and gas. 

5. The discovery of 26 new oil and gas fields and 

indicated new production in additional recent 

wildcat wells, during the past 8 years. 

There are approximately 500,000 acres of qesignated and proposed Wilderness Lands within the 

Wyoming-Utah-Idaho thrust belt. Eighty-five percent of these lands are assessed as having high to 

medium petroleum potential (high potential, 78.5 

percent, and medium potential, 6.5 percent). An 

additional 1.2 percent are judged to have low petroleum potential, with the remaining 13.8 percent 

as having zero petroleum potential. · 

REFERENCES CITED 

Conrad, J. F., 1977, Surface expression of concentric folds and 

apparent detachment zone (decollment) ne~r Cokeville, 

Wyoming, in Wyoming Geological Association Guidebook 

Symposium, 29th Annual Field Conference, Rocky Mountain thrust belt geology and resources, p. 385--39Q. 

Halbouty, M. T., ed., 1980, Giant oil and gas fields of the decade 1968-1978: American Association of Petroleum 

Geologists Memoir 30, 596 p. 

Hayes, K. H., 1976, A discussion of the geology of the southeastern Canadian Cordillera and its comparison to the 

Idaho-Wyoming-Utah fold and thrust belt, in Hill, J. G., 

ed., Rocky Mountain Association of Geologists Symposium 

on geology of the Cordilleran Hinzeline, p. 59-82. 

Hoffman, M. E., and Balcells-Baldwin, R. N., 1982, Gas giant 

of the Wyoming thrust belt: Whitney Canyon-Carter 

Creek field, in Geologic studies of the Cordilleran thrust 

belt, Powers, R. B., ed., Rocky Mountain Association of 

Geologists, v. 2, p. 613-618. 

Johnston, R. R., 1980, North American drilling activity in 

1979: American Association of Petroleum Geologists Bulletin, v. 64, no. 9, p. 1295-1330. 

Lageson, D. R., Lowell, J. D., Lamerson, P. R., and Royse, 

Frank, Jr., 1980, Wyoming-Utah Overthrust Belt structural style, field guide to American Association of Petroleum Geologists, Trip No. 5, June, 1980,· Denver, Colorado, 34 p. plus maps and photos. 

Lamerson, P. R., and Royse, Frank, Jr., 1980, Thrust belt 

structures, Part B, in Wyoming-Utah overthrust belt 

structural style, field guide to American Association of Petroleum Geologists, Trip No. 5, June 1980, Denver, Colorado, 34 p. plus maps and photos. 

Maher, P. D., 1976, Rewarding Peneview field in Utah presents complex geology, high risk: Oil and Gas Journal, 

June 14, p. 96-99. 

Petroleum Information Corporation, Denver, Colorado, 1981, 

The Overthrust Belt, 251 p. 

Powers, R. B., 1977, Assessment of oil and gas resources in 

the Idaho-Wyoming Thrust Belt, in Wyoming Geological 

Association Guidebook, 29th Annual Field Conference, 

Rocky Mountain thrust belt geology and resources, p. 

629--637. 

--1980, Oil and gas potential of the Wyoming-Utah-Idaho 

overthrust belt in relation to its Canadian Foothills thrust 

belt analog (abs.): American Association of Petroleum 

Geologists Bulletin, v. 54, no. 5, p. 767. 

--1983, Geologic framework and petroleum potential of 

the greater Bob Marshall Wilderness Area, western Montana thrust belt: U.S. Geological Survey, Open-File Report, 21 p. [in press]. 

N13 
Rodgers, John, 1963, Mechanics of Appalachian foreland folding in Pennsylvania and West Virginia: American Association of Petroleum Geologists Bulletin, v. 47, no. 8, p. 

1527-1536. 

Royse, Frank, Jr., 1979, Structural geology of the western 

Wyoming-northern Utah thrust belt and its relation to oil 

and gas; American Association of Petroleum Geologists 

Distinguished Lecture: Oil and Gas Journal, February 12, 

v. 77, no. 7, p. 155--156. 

Royse, Frank, Jr., Warner, M. A., and Reese, D. L., 1975, 

Thrust belt structural geometry and related stratigraphic 

problems, Wyoming-Idaho-northern Utah, in Rocky 

Mountain Association of Geologists Symposium on deep 

drilling frontiers in the central Rocky Mountains, p. 41-54. 

N14 

U.S. Bureau of Land Management, 1981a, State of Idaho wilderness status map, scale 1:1,000,000. 

--1981b, State of Utah wilderness status map, scale 

1:1,000,000. 

--1981c, State of Wyoming wilderness status map, scale 

1:1,000,000. 

Warner, M. A., 1982, Source and time of generation of hydrocarbons in Fossil Basin, western Wyoming thrust belt, in 

Geologic studies of the Cordilleran thrust belt, Powers, R. 

B., ed., Rocky Mountain Association of Geologists, v. 2, p. 

805--816. 

Ver Ploeg, A. J., and DeBruin, R. H., 1982, The search for oil 

and gas in the Idaho-Wyoming-Utah salient of the overthrust belt; Geological Survey of Wyoming, Report of Investigations no. 21, 108 p.