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A RECONNAISSANCE EVALUATION OF

HEAVY HYDROCARBONS IN THE

TAR SAND TRIANGLE

prepared by

Charles Bishop

August, 1985

If DRAFT

ABSTRACT

The Tar Sand Triangle encompasses about 200 square miles in southeastern

Utah. The area consists of rough, mountainous terrain, with a climate that

varies from semiarid to arid. Sedimentary rocks exposed in the area range

from Permian Cedar Mesa Sandstone to the Triassic(?)-Jurassic Navajo

Sandstone. The main oil bearing formation is the Permian White Rim Sandstone

with a saturated zone which varies from zero to 230 feet thick. Minor

occurrences of oil are found in the Moenkopi Formation, Cedar Mesa Sandstone

and Chinle Formation. The Triangle has an average net pay zone of 112 feet

and a grade that varies from zero to 36 gallons per ton. The inferred oil

resource, in-place, is estimated at approximately 5 billion barrels. There is

also a potential resource of approximately A million barrels of oil in the

Cedar Mesa Sandstone and Moenkopi Formation.

The Tar Sand Triangle is the largest known oil-impregnated sandstone

deposit in Utah, and is a combination of six separate previously named

deposits. There are currently no oil development projects in the area, but a

number of lease holders have applied to transfer their oil and gas leases to

combined hydrocarbon leases, which would allow for their development.

Development of the area will most likely be done by an in-situ recovery method

because of favorable sandstone characteristics, rough terrain and the high

overburden ratio.

CONTENTS

ABSTRACT

INTRODUCTION

Location and Extent of Area

Geography

Drainage and Water Supply..

Climate, Soil and Wildlife.

Population

Accessibility and Roads....

METHOD OF STUDY

GEOLOGIC HISTORY AND STRUCTURE

STRATIGRAPHY

Cedar Mesa Sandstone

Organ Rock Shale ,

White Rim Sandstone

Moenkopi Formation ,

Chinle Formation

Glen Canyon Group ,

USE OF WELL LOGS ,

PROPERTIES OF HEAVY HYDROCARBONS..,

ECONOMIC GEOLOGY ,

Other tar sand deposits ,

White Canyon ,

Poison Spring Canyon

Unnamed Minor Occurrences..,

SURFACE MINING

IN-SITU RECOVERY

SUMMARY AND CONCLUSION ,

REFERENCES

ILLUSTRATIONS

Figure

1 Index map of Utah showing the location of the Tar Sand

Triangle

2 Map showing the extent of oil-impregnated sandstone and the

area evaluated in this report

3 Map showing relationship of wilderness study areas to the

Tar Sand Triangle area.

4 Map showing location of measured sections.

5 Map showing location of drill holes.

6 Map showing structure contours drawn on top of White Rim

Sandstone.

7 Map showing the variations in White Rim Sandstone thickness.

8 Other tar sand deposits in the Tar Sand Triangle area.

Tables

1 Outcrop Analysis Data

2 Generalized section of exposed rock in the Tar Sand Triangle

Plates

1 Location of prominent features and topography

2 Isopach map of the net pay zone

3 Averaged pay zone oil yield contour map

A Overburden isopach map of the White Rim Sandstone „

•<

INTRODUCTION

Location and Extent of Area

The Tar Sand Triangle encompasses about 200 square miles within Garfield

and Wayne Counties in southeastern Utah. The northern boundary is

approximately 38° 15• N latitude, the Colorado River bounds the area on the

southeast, and the Dirty Devil River forms the western edge. The Triangle

encompasses parts or all of Townships 29, 30, 30-1/2, 31 and 32 South, and

Ranges 14, 15, 16, and 17 East. The location and extent of the evaluated area

are shown by figures 1 and 2, respectively. About 40 percent of the Triangle

lies in Glen Canyon National Recreation Area, 12 percent on state

school-section land, and the remaining land is federally administered. Four

proposed wilderness study areas surround or impinge upon the deposit: the

Dirty Devil area to the northwest, Horseshoe Canyon area to the north, French

Springs/Happy Canyon area on the north end of the tar sand deposit ( about 50

percent of it falls within the area covered by this report), and Fiddler Butte

area to the west ( about 10 percent of it falls within the report area)

(Schreiner, R.A.,1984). Figure 3 shows the locations of the four wilderness

study areas relative to the Triangle. The Triangle deposit is a consolidation

of six separate, previously named tar sand deposits: Elaterite Basin, Fault

Point, Teapot Rock, Tar Cliff, Hatch Canyon and The Cove. These deposits,

when grouped together, form a triangle, hence the name Tar Sand Triangle.

Geography

The Tar Sand Triangle is part of the inner canyonlands of the Colorado

Plateau Physiographic Province in southeastern Utah. The topography of the

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Figure 1. Index map of Utah showing the location of the Tar Sand Triangle

RI4E RISE KICE RITE

miles

Approximate ou tc rop of che White Rim Sandstone

Boundary of area evaluated in t h i s report

;:•:; Area unde r l a in by heavy hydrocarbons

Figure 2. Map showing the extent of oil-impregnated sandstone and the area evaluated in this report

•.III. «.•((. •.ire.

*••!»' — —*•»!»

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JOlUklt

mmm Approximate boundaries of the Dirty Devil, French Spring*/ Happy Canyon, Horseshoe Canyon and Fiddler Butte Nilderness Study Areas

Approximate boundary of the Federal Tar Sand Triangle Special Tar

Sand Leasing Area

Oil-Impregnated Outcrops Campbell and Ritzma, 1979

Boundary of area evaluated in this report

Figure 3. Map showing relationship of wilderness study areas to the Tar Sand Triangle area (Modified from Schreiner, R.A.,1984)

area has been formed by the differential erosion of the various gently dipping

lithologic units which consist of sandstones, shales, siltstones, claystones,

and conglomerates, and through the distribution and influence of joints and

faults. The resulting topography consists of vertical cliffs, incised

canyons, flat-topped mesas and buttes. Plate 1 shows the location of some

prominent features and the topography of the area.

The most conspicuous physiographic feature, when viewed from the Colorado

River looking westward, is the Orange Cliffs, which stand 300 to 400 feet in

height and run north-south through R. 15 and 16 E.. Sunset Pass, located in

sections 21, 22, T. 31 S., R. 16 E., is the only place where the massive

cliffs are breached. Here, a pair of east-west trending faults bound the pass

and dissect the cliffs.

The Black Ledge is another prominent platform on the east side of the

Triangle, and is situated topographically below the Orange Cliffs. It is

formed by the cliffs and benches of the White Rim Sandstone in the south and

the Moss Back Member of the Chinle Formation in the north. The Black Ledge

stands from 100 to 300 feet in height and is up to 2 miles in width.

Badland-slope topography characterizes the Black Ledge where there is a broad

upper bench.

Below the cliffs formed by the Black Ledge in the southern parts of the

area, there is a broad platform formed by the Cedar Mesa Sandstone. It is

approximately 7 miles wide in the north, tapering to 1 mile wide in the

south. The Colorado River bounds this triangular platform on the east, and

its tributaries dissect the platform. This area contains numerous scenic

attractions such as The Maze, The Land of Standing Rock and Waterhole Flat.

The Dirty Devil River has formed an incised canyon on the west side of the

Triangle and runs roughly north-south. Above this canyon is a wide platform

with isolated mesas and buttes formed by the differential erosion of the

Wingate Sandstone. Its sloping bases are composed of the Chinle and the

Moenkopi Formations.

Drainage and Water Supply

All rivers and streams in the area are within the Colorado River drainage

system. The principal rivers are the Colorado River and the Dirty Devil

River. There are very few perennial springs in the area. Most springs flow

in response to precipitation and, consequently, are dry most of the time.

Process water for the future development of the Triangle will most likely

come from the Dirty Devil River since Colorado River water is tied up in

complex water rights problems (Keefer and McQuivey, 1979). The Dirty Devil

River has an outflow at its mouth of 73,890 acre-feet per year with a total

dissolved solids discharge of 197,465 tons per year (Utah Division of Water

Resources, 1977).

Climate, Soil and Wildlife

The climate of the Triangle varies from semiarid to arid, with the average

annual rainfall ranging between 6 and 10 inches. The greatest precipitation

occurs in the higher elevations, such as Gordon Flats in T. 30 S. R. 16 E.,

during the summer months, and is usually in the form of cloudbursts which

often produce flash floods. Winters are dry with snowfall usually totaling

about 8 inches, maximum (Bureau of Land Management, 1983). Temperatures in

the Triangle can be extreme with summer temperatures reaching over 100 F and

winter temperatures falling below 0°F.

The surface area is covered by approximately 20 percent rock outcrop with

soils comprising the other 80 percent. The soils are residual, formed

primarily by physical weathering, chiefly by wind and water erosion, and are

derived from the major stratigraphic units in the area. They tend to be high

in clay and are usually sandy (Bureau of Land Management, 1983). The soils

can be distinguished by their locations. Thin wind-blown deposits are found

on the high mesas and buttes, thicker colluvial deposits are found at the

bases of cliffs, and in the canyon bottoms a deeper alluvial soil layer is

found.

Vegetation in the Triangle is typical of the Colorado Plateau, where

altitude is the main determinant as to the type of vegetation and where it

grows. The lower elevations are dominated by sagebrush, shadscale,

rabbitbrush, grasses, and ephedra, with cottonwood trees found along streams.

At higher elevations, plnyon pine, juniper, rabbitbrush, greasewood, sagebrush

and grasses are common.

Animals found in the area include mule deer, coyote, antelope, mountain

lion, wild burros, several species of birds, and desert bighorn sheep which

were introduced to the area in 1982. No threatened or endangered species have

been identified in the Triangle (Bureau of Land Management, 1983). Wildlife

populations are not extensive, and the restrictive nature of the habitat makes

those existing populations sensitive to disruption.

Population

There is no established human population in the Triangle, though the area

is visited by people tending stock or enjoying the back county. The closest

established domicile is the Hans Flat Ranger Station, about four miles to the

north.

Accessibility and Roads

The Tar Sand Triangle can be reached only by four wheel drive vehicle over

graded and unimproved dirt roads. There are three main routes into the area.

(1) From Hanksville, the area is accessed by traveling 20 miles north on

Highway 24, turning right onto the Hans Flat Ranger Station road, and

following the road southeast into the Tar Sand Triangle area. (2) The area can

be reached from the Poison Spring Canyon road, 30 miles south of Hanksville on

Highway 95 (This road fords the Dirty Devil River). (3) A third access road

leaves Highway 95, one mile north of Hite, and travels eastward along the base

of the Orange Cliffs.

There are numerous small aircraft landing strips scattered throughout the

area, but the only maintained air strip is at the Hans Flat Ranger Station.

The others were constructed mainly for oil and mineral exploration in the area

and are not maintained.

&CTHOD OF STUDY

Twenty-three stratigraphic sections were measured on the east side of the

Triangle (locations of the measured sections are shown in Figure A). Access

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• Measured Sec t ion and Sample Location o Sample Locat ion

Numbers Refer to Table 1

Figure 4. Map showing l o c a t i o n of measured s e c t i o n s and samples

for measuring sections of the White Rim Sandstone is limited because its steep

cliffs are breached in only a few places. In the course of measuring and

describing the stratigraphic sections, oil saturation was noted and samples

were taken. In an attempt to reduce sample bias, the samples were collected

at each measured sections at intervals that were proportional to the thickness

of the section.

The oil-impregnated outcrop samples were analyzed by TerraTek Core

Services using mass fraction analysis. Natural bulk density, grain density,

residual fluid saturation, and gallons per ton were determined. Residual

fluid saturation was determined by using the Dean-Stark low temperature

solvent extraction method. Grain densities were determined by Boyle's Law

techniques, and bulk volumes were determined by an Archimedes displacement

method. The results of these analyses are given in Table 1.

Geophysical logs and/or core data from 25 drill holes in the area were

also examined; figure 5 shows the location of these holes. These data were

used to determine the depth and thickness of the White Rim Sandstone, and were

correlated with measured sections to help determine the geometry of the tar

sand deposit.

GEOLOGIC HISTORY AND STRUCTURE

In Pennsylvanian-Permian time, orogenic activity in southeastern Utah and

southwestern Colorado produced major structural features, including the

Uncompahgre and Monument Uplifts. During the Early Permian Period, the

Uncompahgre Uplift was supplying large amounts of detrital material to

southeastern Utah. These terrestrial sediments interfingered with marine

Table 1 TAR SAND TRIANGLE

Outcrop Analysis Data

Sample Number

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

Mass Fraction Oil H20

(%)

1.9

1.5

0.5

0.3

0.7

0.4

3.0

0.4

14.9

1.0

0.8

0.8

0.2

1.0

1.5

0.5

0.5

1.8

0.6

1.2

0.3

1.7

2.0

(*)

<0.1

<0.1

<0.1

<0.1

<0.1

0.0

<0.1

0.0

<oa

0.1

0.1

0.0

0.0

0.2

0.3

0.1

0.6

0.1

0.0

0.3

0.0

0.2

1.0

Grain Density

(gm/cm )

2.63

2.66

2.63

2.66

2.65

2.65

2.65

2.64

2.64

2.65

2.63

2.64

2.65

2.63

2.61

2.63

2.72

2.66

2.63

2.64

2.64

2.64

2.61

'Nat.Bulk Density

(gm/cm )

2.20

2.24

2.22

2.18

2.50

1.90

2.22

2.27

2.04

2.37

2.17

2.19

2.05

2.16

2.27

2.10

2.22

2.33

2.20

2.19

2.53

2.24

2.24

Gallons/Ton

4.5

3.5

1.2

0.7

1.8

0.9

7.2

1.0

35.8

2.4

2.0

2.3

0.4

1.7

3.7

1.1

1.1

4.3

1.5

2.9

0.7

4.0

4.8

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sediments that were being deposited to the west. The Cedar Mesa Sandstone,

Organ Rock Shale, and the White Rim Sandstone of the Cutler Group were

deposited during this period (Steele-Mallory, 1982).

The Triangle area is structurally very simple. Sedimentary units gently

dip to the northwest. Figure 6 shows structural contours drawn on top of the

White Rim Sandstone. Faulting has played only a minor part in shaping the

area. Faults usually have small displacements, trend west or northwest, and

are usually associated with small grabens. Sunset Pass, the most significant

graben, is formed by the largest faults in the area. Much of the scenic

beauty and rock structure of the area results from jointing which trends

southwest-northeast and northwest-southeast.

The oils found in the White Rim Sandstone were originally trapped in a

pinch-out of the formation as it onlapped the Permian (?) Monument Upwarp

(Campbell and Ritzma, 1979). These oils were eventually exposed to

percolating oxygenated, meteoric waters that carried bacteria into the

reservoir. These bacteria destroyed the light oil fractions thus increasing

the gravity and viscosity of the residue (Breger, 1981). The heavy

oil-impregnated sands were eventually exposed by erosion.

STRATIGRAPHY

Sedimentary rocks exposed in the Triangle area range in age from the

Permian Cedar Mesa Sandstone to the Jurassic Navajo Sandstone, and have an

aggregate thickness of more than 2800 feet (Baker, 1946). Table 2 shows a

generalized section of the area.

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T M 3

T 3 0 S

T S O 1/2 S

T S I 8

T S Z 8

T 33 S

6 1 * fe miles

F i g u r e 6. S t r u c t u r e contour map drawn on top of the White Rim Sandstone

SYSTEM FORMATION THICKNESS

ffwt) DESCRIPTION

JURASSIC

TRIASSIC Navajo Sandstone

& s

a Kayenta Formation

Wingate Sandstone

Chinle Foramation

•unconformity*

Moenkopl Formation

PERMIAN •unconformity-

White Rim Sandstone

Organ Rock Shale

Cedar Mesa Sandstone

420-552

270-294

270-723

265-555

326-684

0-600

117-550

700-800

White, tan, and buff, very f ine to medium grained, well rounded, well sorted sandstone. Thickly and in t r ica te ly crossebedded. Calcareous and si l l iceous cement. Some lent icular sandy shales and limestone.

I r regular ly interbedded red, reddish-brown, gray shale, s i l tstone and f ine to medium-grained sandstone, local ly conglomeratic. Contact with the Navajo Sandstone is t ransi t ional in some area.

Reddish-brown, buff and grayish-orange, very f ine to f ine grained sandstone. Massive crossSeddino, poorly to well-indurated. Weather in to vert ical c l i f f s .

Purples, reds, browns, grays, fine-grained rindstone, mudstone, s i l ts tone and some conglomerate. Forms slopes and c l i f f s . Lowest member in the area is the Moss Back Member, a f ine to medium grained conglomeratic sandstone. There are seven members.

Reddish-brown ana greenish-gray, f ine grained f i ss i l e mudstone, s i l ts tone and sandstone. Thinly and even bedded. Commonly ripple-marked, veins of gypsum, local ly petrol i ferous. In some area the lower parts have been bleached possibly due to reduction of i ron because of the assouated hydrocarbons, has local interformational angular unconformity.

White, gray, buff , f ine to medium grained, well sorted, rounded to subnxrded sandstone. Poorly cemented and f r iab le . Massive cross-bedding in lower un i t . Petrol i ferous through out most of the area.

Reddish-brown s i l ts tone, s i l t y sarJstone, and sandy shale. Weathers in to f lu ted surface. Some bleaching at the upper contact.

Light-gray to tan, f ine to coarse grained sandstone. Thick-bedded and cross-bedded. Petroliferrous at several locations

Table 2. Generalized section of exposed rock In the Tar Sand Triangle of southern Utah (Modified from Baker, A.A.,1946).

Cedar Mesa Sandstone

The Cedar Mesa Sandstone of the Cutler Group outcrops in the steep canyon

walls of Cataract Canyon and forms a bench or platform extending back to the

Orange Cliffs. The surface of this platform is characterized by a series of

cliffs, mesas, buttes, spires, and steep-walled canyons. The unique shapes

assumed by the eroded sandstone have been controlled by fracture systems that

run throughout the area. The Maze and The Land of Standing Rocks are two

examples of this unique combination of erosion and jointing.

The Cedar Mesa is a friable, light-gray to tan, fine-to coarse-grained

sandstone. It is comprised almost entirely of angular-to rounded quartz

grains, many of which have a frosted surface. Calcium carbonate is the

cementing agent, though many of the sand grains are coated with secondary

silica (Baker, 1946). This formation is thick bedded and highly cross bedded

with the foresets dipping predominantly toward the southeast. It is most

likely a near-shore, shallow water accumulation of marine sands (Barrs, 1975).

The upper part of the Cedar Mesa is petroliferous at several outcrop

locations. It has also been reported to contain oils in some wells.

Saturation seems to be discontinuous and only involves the upper 30 feet,

immediately below the contact with the Organ Rock Shale.

Organ Rock Shale

The Permian Organ Rock Shale of the Cutler Group outcrops above the broad

platform of Cedar Mesa. It is an interbedded arkosic red siltstone, silty

sandstone, and silty mudstone that is poorly sorted and is predominantly

calcium carbonate cemented. The depositional environment of the Organ Rock

seems to have been marginal marine lowlands that were dominated by streams,

flood plains, and tidal flats (Barrs, 1975).

The Organ Rock is usually devoid of oil, except for some vertical

fractures that contain almost pure hydrocarbon. These fractures appear to

have acted like conduits channeling the oil from the White Rim Sandstone to

the upper Cedar Mesa Sandstone. The upper portion of the Organ Rock Shale

appears altered and bleached throughout the Triangle, perhaps a result of iron

reduction due to the proximity of the overlying hydrocarbons in the White Rim

Sandstone.

White Rim Sandstone

The Permian White Rim Sandstone is the upper of two light colored

sandstone units within the Cutler Group. It forms the vertical walls of an

inner bench between the Cedar Mesa and the Orange Cliffs. The White Rim is

composed of two depositional units. The lower of the two units was deposited

in a eolian environment while the upper unit is marine in origin and involved

some reworking of the lower unit. The lower, thicker unit consists of

large-scale, high-angle, cross-bedded quartzarenite; both tangential and

angular types of cross bedding are found. The grains are usually fine to

medium in size, subangular to rounded, and well sorted, with secondary quartz

overgrowths. The principal cementing agent is calcite, although the sand is

usually poorly cemented and very friable. The lowest unit comprises most of

the formation and is sharply cut and scoured by the overlying unit. The upper

unit forms a thin veneer that ranges from zero to about 20 feet in thickness.

It is fine to medium grained, with occasional large clasts from the reworked

lower unit (Chan, M.A., and Huntoon, J.F., 1984).

There is considerable variation in the thickness of the White Rim

Sandstone in the area. This variation is related to paleotopographic relief

and the reworking of the lower unit during deposition of the upper unit

(Huntoon, J.F., and Chan, M.A., 1984). Thickness ranges from 230 feet thick

in Red Cove to zero near The Gap. A few miles north, just west of The Gap in

Elaterite Basin in the southern part of the Triangle, it is over 200 feet

thick. At the mouth of the Dirty Devil River, it is about 75 feet thick, and

east of the Cove it is about 60 feet thick. Variations in the White Rim

thickness are shown in Figure 7.

The White Rim conformably overlies the Organ Rock Shale; the contact is

usually sharp and well defined. In the southern and western part of the

Triangle, the upper contact is marked by an unconformity characterized by

conglomeratic materials of the upper unit of the White Rim. In the northern

parts of the area, the White Rim is overlain by a fine-grained, altered, lower

unit of the Moenkopi Formation.

The White Rim is important because it is the major oil-impregnated unit in

the Triangle. The characteristics of the White Rim that make it an ideal

reservoir rock are its porosity, which averages about 23 percent, and its

permeability of about 300 millidarcles. It contains one pay zone that varies

from zero to over 200 feet in thickness.

Moenkopi Formation

The Triassic Moenkopi Formation is predominantly a sllty sandstone and

Standard Oil Bert Mesa 1

Skyline Oil Federal 6-11

O

Mountain Fuel Dirty Devil 4

O

Oil Development Gordon Flats 16-1

Oil Development ° ordon Flats 19-1

Phi l l ips French Seep 1

Tea Pot 1 (outcrop)

Black Ledge 2 (outcrop)

e Well A Outcrop

Figure 7. Variations in the White Rim Sandstone thickness

shale with some included limestones. It is typically dull red brown with

numerous greenish-gray beds, probably due to a high glauconite content. The

Moenkopi was deposited within a mixture of environments including shallow

seas, deltas, lacustrine, playas and flood plains (Robeck, 1958). It forms

the badland slopes found above the White Rim Sandstone in the southern part of

the Triangle, and cliffs with minor slopes above the White Rim Sandstone in

the north. At the base of the Moenkopi, above the White Rim Sandstone, is a

unit consisting of shales and sandy siltstones. This unit is distinctive

because of its bleached appearance and a local angular discordance in the

Elaterite Basin area. In this report it is considered part of the Moenkopi

Formation, but it has been considered an unnamed upper unit of the Cutler

Group (Baker A.A., 1946).

The Moenkopi Formation has been reported to contain heavy oils in some

wells. Heavy oils were also noted in isolated outcrops. This localized

saturation seems to be of small extent and is possibly isolated by

discontinuous sands.

Chinle Formation

The Late Triassic Chinle Formation forms slopes and ledges. It consists

principally of interbedded mudstones, limestones, sandstones, claystones and

conglomerates (Robeck, 1958). The Chinle consists of continental deposits of

fluvial and lacustrine origin (Baars and Molenaar, 1971). Members of the

Chinle Formation are not distinctive in the area with the exception of the

lowest member, the Moss Back Member, which forms cliffs above the Moenkopi

Formation. No oil was observed in outcrops but some have been reported from

wells.

Glen Canyon Group

The Glen Canyon Group formations include, in ascending order of

occurrence, the Triassic Wingate Sandstone, the Triassic Kayenta Formation,

and the Triassic(?)-Jurassic Navajo Sandstone. Combined they form the massive

Orange Cliffs. The Wingate Sandstone is a well-sorted, fine-grained,

pale-orange to light-brown sandstone (Baars and Molenaar, 1971), and contains

large scale trough cross bedding, probably indicating an eolian depositional

environment. The Kayenta Formation is a fine- to medium-grained sandstone

with interbedded shales and limestones. It is a reddish-purple sandstone with

sedimentary structures indicating a fluvial environment of deposition. The

Navajo Sandstone is composed of well-rounded, well-sorted, fine-to

medium-grain, buff- to pale-orange sandstone. It is well-known for its large

scale cross bedding of eolian origin (Baars and Molenaar, 1971). The Glen

Canyon Group was not observed to have any hydrocarbon potential within the

area.

USE OF HO.L LOGS

Geophysical logs used in the evaluation of the Triangle came from holes

that were drilled primarily for oil and gas exploration. A few of the holes

were drilled specifically to explore the hydrocarbon potential of the White

Rim Sandstone. Logging suites examined consisted of a combination of Gamma

Ray, Neutron, SP, and Laterologs. Recognition of the White Rim Sandstone is

relatively easy on most logs, due to the physical differences between it and

the units below and above it.

PROPERTIES OF HEAVY HYDROCARBONS

Wood and Ritzma (1972) determined the °API gravity of the heavy oils to

range from -3.6 to 9.6; Bunger, Thomas and Dorrence (1979) determined an

°API gravity of 11.1 for the deposit. The elementary composition of the

oils, as determined by the above authors, has the following ranges of values,

given in weight percent.

C 69.6-85.2 0 1.1

H 5.8-11.8 N 2.67-6.27

S 3.13-6.27 other up to 18

The atomic mass ratio C:H corresponds to a composition range of 1:1 to 1:1.7

with an average composition of C:H = 1:1.4, and an average formula of

(CH^ ^ ) n . An average molecular weight of 578 has been reported for the

oils within the deposits.

ECONOMIC GEOLOGY

The area underlain by heavy oil-impregnated sandstone was determined from

outcrops, measured sections, and well data. Only one dominant zone of heavy

oil-impregnated sandstone was evaluated; it was within the White Rim Sandstone

and varied from zero to 230 feet in thickness. The termination of the deposit

on the southeast is caused by the erosional development of the Orange Cliffs.

The absence of heavy oil-impregnated sandstone to the west and north is

possibly due to the original oil-water contact.

Oil seeps are found in many locations within the Triangle. The most

noteworthy are those found in Elaterite Basin, where almost the entire outcrop

of White Rim Sandstone contains heavy, and often bleeding accumulations of

oil. During the summer, numerous seeps become active and asphalt flows from

the cross stratification of the bottom and top set planes of the cross bedded

sandstone.

To evaluate the in-place oil resources, a net pay zone isopach map (Plate

2), and a grade map (Plate 3) were prepared. It was assumed that all

boreholes and measured sections were vertical and that the top of the net pay

zone and its base formed parallel planes. Using these assumptions, the volume

of the resource was represented by prisms (Pearson, 1981). An area for the

surface plane was calculated for each prism and then multiplied by an average

thickness of the net pay zone. It was further assumed that the oil grade of

the deposit changed gradually and continuously as a linear function along a

straight line connecting any two adjacent sample points. The average grade of

each prism was calculated as the arithmetic mean of the three samples.

The Triangle has an average net pay zone of 112 feet and an average grade

of 3.6 gallons per ton within the 193 square miles of the evaluated area.

Inferred barrels of oil resource in-place is 5.01 billion barrels, all in the

White Rim Sandstone. Also, possible resources of 1.8 million barrels and 2

million barrels are estimated for the Cedar Mesa Sandstone below, and the

Moenkopi Formation above, respectively. This in-place resource is

considerably less than an earlier estimate of 12.5-16 billion barrels

(Campbell and Ritzma, 1979), but is more than a recent estimate of 2.5 billion

barrels (Interstate Oil Compact Commission, 1984). More drill hole

information would be needed to more accurately determine the in-place resource.

Other tar sand deposits

Other tar sand deposits, including White Canyon, Poison Spring Canyon and

other unnamed minor occurrences in the area are shown in figure 8. They occur

in the Moenkopi Formation, Organ Rock Shale, White Rim Sandstone, and the

Cedar Mesa Sandstone.

White Canyon

The White Canyon deposit is located in Townships 34 and 35 South, Ranges

15 and 16 East. The oil occurs in the Organ Rock Shale and Moenkopi Formation

(Ball Associates, Ltd.,1964). No information is available on the resources in

place.

Poison Spring Canyon

The Poison Spring Canyon deposit is located in Township 31 South, Range 13

East. The oil occurs in the Moenkopi Formation and is confined to an area

located along a fault. No information is available on the resources in place.

Unnamed Minor Occurrences

Several unnamed minor occurrences of oil-impregnated sandstone are found

throughout the area, and occur in the Cedar Mesa Sandstone and White Rim

Sandstone. No information is available on the resources in place.

R.12 E. R.13 E. R.1A E. R.15 E. R.16 E. R.17 E.

V S.Mr- V

~\ Clfspat'as Chair

i i *"w

,J GUEN CANY TAR SAND TRIANGLE- r

^ ELATERITi •Li^Ni 'WAYNE co. _/ -•.-•• .r ! | ----r--a-- l f i /

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T.34 S.

T.35 S.

miles

U Area underlain by heavy hydrocarbons

F igu re 8 . Other t a r sand d e p o s i t s in t h e Tar Sand Tr i ang le a rea . (From Utah Geological and Mineral Survey, Map 68)

SURFACE MINING

The Triangle area consists of rough, mountainous terrain with varying

overburden thickness. The net pay zone within the White Rim Sandstone has an

average thickness of 112 feet, is found in only one stratlgraphlc horizon, and

is not of uniform thickness or grade.

The experience of the Canadian Athabasca tar sands mining operation

indicates that a stripping ratio of one-to-one or less is desirable for mining

(Kuuskraa, V.A., and Doscher, T.M., 1978). Applying this one-to-one stripping

ratio to the Triangle indicates that about 100 feet of overburden can be

removed. Based on the overburden map of the area (Plate 4) and using this

stripping ratio, only about 10 percent of the Tar Sand Triangle can be surface

mined.

IN-SITU RECOVERY

Extraction of heavy oils in-sltu can be done either by injecting steam or

other hot fluids into the oil bearing formation, or by in-situ combustion.

Both of these methods heat the reservoir rock and the heavy oil contained

within them. The heating causes a reduction in viscosity of the oil,

producing a greater sweep efficiency in the reservoir. Both methods also

requires the reservoir rock to have high porosity, high permeability, and the

presence of enough overburden to maintain pressure caused by the high pressure

injection of fluids into the ground.

The White Rim Sandstone has approximately 23 percent porosity and 300

millidarcy permeability. These characteristics favor a combustion method. If

it is assumed that 1000 feet of overburden are required to maintain the

pressure to drive the combustion front at depth, only 20 percent of the area

is amenable to this type of recovery. If less overburden is needed to

maintain the required pressure, the area would be greater.

SUMMARY AND CONCLUSION

The Tar Sand Triangle oil-impregnated sandstone deposit is the largest in

Utah. An area of 193 square miles was identified using outcrop and well

data. Samples from the deposit range in oil content from 0 to 36 gallons per

ton. The deposit is estimated to contain 5.01 billion barrels of resources

in-place, with additional possible resources of 1.8 million barrels within the

Cedar Mesa Sandstone and 2 million barrels within the Moenkopi Formation.

The conversion of existing oil and gas leases to combined hydrocarbon

leases would allow the development of the oil-impregnated sandstone resource.

At present a number of energy companies and individuals hold oil and gas

leases, and have filed to have these conversions made. Federal land status

decisions could hinder development of the area since approximately 40 percent

of the Triangle is included in the Glen Canyon National Recreation Area and

four wilderness areas have been proposed within or near the deposit.

REFERENCES

Baars, D.L., 1975, The Permian system of Canyonlands country: Four Corners Geol. Soc. Guidebook, 8th Field Conf., Canyonlands.

Baars, O.L., and Molenaar, CM., 1971, Geology of Canyonlands and Cataract Canyon: Four Corners Geological Society, Sixth Field Conference.

Baars, D.L., and Seager, W.R., 1970, Stratigraphic control of petroleum in the White Rim Sandstone (Permian) in and near Canyonlands National Park, Utah: AAPG Bull. v. 54, no. 5.

Baker, A.A., 1946, The geology of the Green River Desert-Cataract Canyon region, Emery, Wayne, and Garfield counties, Utah: USGS Bull. 951.

Ball Associates, Ltd., 1964, Surface and shallow oil-impregnated rocks and shallow oil fields in the United Ststes: U.S. Bureau of Mines, Monograph 12.

Breger, I.A., 1981, Geochemical considerations regarding the origin of heavy crude oils suggestions for exploration, in The Future of Heavy Crude and Tar Sands: UNITAR, McGraw Hill.

Bunger, J.W., Thomas, K.P., and Dorrence, S.N., 1979, Compound types and properties of Utah and Athabasca tar sand bitumens: FUEL, vol. 58, March.

Bureau of Land Management, 1983, Draft site specific analysis-Horseshoe Canyon Wilderness Area(UT-050-237): Richfield, Utah

Campbell, J.A., Ritzma, H.R.,1979, Geology and petroleum resources of the oil-impregnated sandstone deposits of Utah: Utah Geological and Mineral Survey, Special Studies 50.

Chan, M.A.,and Huntoon, J.F., 1984, Complex interaction of eolian and marine sedimentation in Permian White Rim Sandstone, Elaterite Basin, southeast Utah (Abstract): AAPG Bull. V. 68, no. 7.

Huntoon, J.F., and Chan, M.A., 1984, Permian paleotopography and deposltional patterns - White Rim Sandstone, Elaterite Basin, southeast Utah (Abstract): AAPG Bull. V. 68, no.7

Jayakar, K.M., 1979, The thermal recovery of oil from tar sands: Unpublished Masters thesis, University of Utah.

Keefer, T.N., and McQuivey, R.S., 1979, Water availability for development of major tar sands in Utah: U.S. Department of Energy.

Kruuskraa, V.A., and Doscher, T.M., 1978, The economic potential of domestic tar sands: U.S. Department of Energy.

Pearson, M., 1981, Oil Sands: Reservoir of Orebody?: The future of Heavy Crude and Tar Sands, UNITAR, McGraw Hill

Robeck, R.C., 1958, Chinle and Moenkopi Formations, southeastern Utah: Intermountain Association of Petroleum Geologists, Ninth Field Conference.

Schreiner, R. A., 1984, Mineral investigation of the Dirty Devil, French Springs/ Happy Canyon, and Horseshoe Canyon wilderness study area, Wayne County, Utah: U. S. Bureau of Mines

Steele-Mallory, B. A., 1982, The depositional environment and petrology of the White Rim Sandstone Member of the Permian Cutler Formation, Canyonlands National Park, Utah: Open-file United States Geological Survey.

Utah Division of Water Resources, 1977, Hydrologic inventory of the Dirty Devil study unit: Utah Department of Natural Resources.

Utah Geological and Mineral Survey, 1983, Energy resources map of Utah: Utah Geological and Mineral Survey, Map 68.

Wood, R.E., and Ritzma, H.R., 1972, Analyses of oil extracted from oil-impregnated sandstone deposits in Utah: Utah Geological and Mineral Survey, Special Studies 39.

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