MAJOR TAR SAND AND HEAVY OIL DEPOSITS OF THE UNITED...

MAJOR TAR SAND AND HEAVY OIL DEPOSITS

OF THE UNITED STATES

/9<ry

INTERSTATE OIL COMPACT COMMISSION

Acknowledgments

These acknowledgments pay tribute to the many people who helped create and produce this report. Of special note are four groups—the IOCC Tar Sand Advisory Committee, independent geologists, the various oil companies and state geological surveys, and the staff of Lewin and Associates.

The members of the IOCC Tar Sand Advisory Committee, who provided the structure for and reviewed the study, were:

Dr. J.W. Earley Gulf Minerals Mr. M.C. Noger Kentucky Geological Survey Dr. W.L. Fisher Texas Bureau of Economic Geology Dr. C. Matthews Shell Oil Company Mr. H. Ritzma Utah Geological &. Mineral Survey Dr. R. Meyer U.S. Geological Survey (Advisory) Mr. L. Marchant U.S. Department of Energy (Advisory) Mr. J.J. Stosur U.S. Department of Energy (Advisory)

Second, a number of highly qualified geologists assisted the study team in gathering data and preparing the basic resource estimates, particulary:

Geologist Area of Study

Mr. M. Noger Kentucky Mr. H. Ritzma Utah Mr. T. Henderson San Miguel Deposit, Texas Mr. J. Broz Wyoming

Third, we are especially appreciative of the contribution and sharing of information from private oil companies and various state geological surveys. From the beginning of the study, when the data collection started, and through the review of the draft deposit appraisal reports, the representatives of these organizations demonstrated a willingness to assist us and provided much useful data and valuable critiques.

The fourth category of people is the staff of Lewin and Associates who assembled the information (Kathleen McFall, Elizabeth Hayman, Jay Brash), prepared the graphics (Mary Ann Flynn), typed the text (Leonard Price, Benjamin Pullen), and edited the report (Kathy Thompson) . These talented individuals worked long hours with dedication to complete this report.

V.A. Kuuskraa E.C. Hammershaimb

Chapter g

Utah

S U M M A R Y

Utah is estimated to have 11.9 billion barrels of measured and 7.5 billion barrels of speculative tar sand resource in-place. The tar sand resource occurs in nine major and thirteen minor deposits, as summarized in the following table. Five of the major deposits are in the Uinta Basin of northeastern Utah. The remaining four major deposits are in southeastern Utah; two in the Paradox Basin, one on the Circle Cliffs Uplift and one on the the San Rafael Uplift. The thirteen minor tar sand deposits are in the Uinta Basin and the San Rafael Uplift.

Because of the great variations in topography in Utah, the bulk of the deposits have outcrop or surface exposures. Much of the previously published tar resource information for Utah has been based on extrapolating the data gathered from these outcrops and tar seeps to the subsurface. The major differences in the resource estimate for Utah in this and previous studies stems from the assembly of additional data on the extent and nature of subsurface tar accumulations.

The two largest Utah tar deposits occur in the Uinta Basin in the same lithological unit, the Green River formation of Eocene Age. The largest deposit is Sunnyside, with over 6 billion barrels in-place. Tar occurs in sediments that are equivalent, in part, to the Douglas Creek member of the Green River formation. The second largest accumulation with over 4 billion barrels in-place is the P.R. Spring deposit in the Green River formation. These deposits are thought to be the result of deltaic deposition with a sediment source from the southwest.

The third largest deposit, with nearly 3 billion barrels in-place, is the Tar Sand Triangle in southeastern Utah. The tar is found mainly in the

White Rim sandstone of Permian Age. The remaining six major deposits together contain over 5 billion barrels in-place, and are in all four geologic areas where major tar accumulations occur.

UTAH TAR SAND RESOURCE IN-PLACE

Major Deposits

• Uinta Basin P.R. Spring Hill Creek Sunnyside Whiterocks Asphalt Ridge

• Paradox Basin Tar Sand Triangle Nequoia Arch

• Circle Cliffs Uplift Circle Cliffs

• San Rafael Uplift San Rafael Swell

Subtotal

Minor Deposits

• Uinta Basin Argyle Canyon Raven Ridge Rimrock Cottonwood-Jacks

Canyon Littlewater Hills Minnie Maud Creek Pariette Willow Creek

• San Rafael Uplift Black Dragon Chute Canyon Cottonwood Draw Red Canyon Wickiup Subtotal

Total

Measured (MMB)

2,140 320

4,400 60

830

2,500 730

590

300

11,870

11,870

Speculative (MMB)

2,230 560

1,700 60

310

420 160

1,140

250

6,830

50-75 75-100

25-30

20-25 10-12 10-15 12-15 10-15

100-125 50-60 75-80 60-80 60-75

557-707

7.387-7,537

'Resource estimate from: UGMS "Oil impregnated rock deposits ol Utah," UGMS Map 47, two sheets, 1974

175

Tat Sand/Heavy Oi! Deposits

The 13 minor tar deposits are widely distributed over eastern Utah, in the Uinta Basin and the San Rafael Uplift. The total resource in-place contained in these minor deposits is estimated at 710 million barrels. In addition, there are many apparently localized tar-saturated outcrops and seeps throughout the state that do not meet the size criteria for this study.

The deposits are generally remote from major transportation points in areas of rugged terrain and have limited access to water supply. Thus, development of these deposits has been limited.

The tar-saturated outcrops of Asphalt Ridge and Sunnyside have been quarried for road paving material since the turn of the century.

Shell Oil Company undertook an in-situ thermal recovery test in the Sunnyside area in 1965. A steam generation plant and pilot injection-production systems were constructed, but steam losses, apparently due to vertical fractures in the formation accompanied by other geologic obstructions, resulted in the termination of the project in 1967. During 1966, Signal Oil and Gas Company conducted a steamflood pilot test at Sunnyside recovering 560 barrels of oil.

At Asphalt Ridge, several pilot extraction plants have been operated by oil companies at various times since 1972. In 1975 through 1978, the Laramie Energy Technology Center of the U.S. Department of Energy experimentally tested steam injection and combined reverse and forward combustion schemes to extract oil from the Asphalt Ridge N . W . deposit. Even though the development activity in these tar deposits has been low, numerous exploratory coring programs have been completed by both public agencies and private industry. Well and geologic information from these programs has served as a valuable data source for this study.

MAJOR DEPOSITS

The geographical locations of the nine major tar sand deposits in Utah are shown on Figure 104 (see page 177). Each of these ma j or deposits is discussed in the following individually.

*Thc KctilojjiV JiKimifiru thmughmit this section are based on numerous publications noted in the

Since the major deposits only occur in a limited geographical area and many of them are in the same formations, the regional geology of these deposits is discussed first. This information is summarized for the major areal subdivisions— northeastern and southeastern Utah. Thus, only the geology relevant to each deposit is discussed under the deposit descriptions.

REGIONAL GEOLOGY

Northeastern U t a h *

There are five major tar sand deposits in northeastern Utah within the Uinta Basin. This basin extends approximately 80 miles north to south and 130 miles east to west in the northeastern portion of Utah and western Colorado.

The Uinta Basin is a large, asymmetrical syn-cline bounded by positive structural elements on all sides: the Uinta Mountains on the north; the Douglas Creek Arch on the east; the Um-comphrage Uplift on the southeast; the San Rafael Swell on the southwest; and, the Wasatch Mountains on the west. The synclinal axis trends east-west. The steep north side of the basin has beds with dips ranging from six to seventy degrees, while the more gentle south flank has dips which range from two to six degrees. The west and southwest flanks dip at varying angles up to twelve degrees (Current, 1953, Byrd, 1970 and others).

The Uinta Basin was formed during the Eocene Epoch of the Tertiary Period. Stratigraphically, the principal tar impregnation is in the Green River formation. The tar-impregnated intervals overlie a transitional zone between the Green River formation (Eocene) and the older Wasatch formation (Paleocene-Eocene). The oil-impregnated zones within the Green River formation are in turn overlain by the oil shale-bearing Parachute Creek member of the Green River formation. Tar sands are also found to a lesser extent in the older Navajo sandstone of Jurassic Age, and the basal Mesaverde Group, Cretaceous Age. Figure 105 (see page 178) shows a strati-

and in the references for this section.

176

Utah

FIGURE 104

MAJOR TAR SAND DEPOSITS OF UTAH

I D A H O

A R I Z O N A

Prepared by Lewin and Associates, Inc., 1983.

177

Tor Sani/Heavy Oil Deposits

FIGURE 105

STRATIGRAPHIC COLUMN AND CORRELATION CHART-UINTA BASIN, UTAH

PERIOD N O R T H W E S T E R N U I N T A B A S I N C E N T R A L U I N T A B A S I N E A S T E R N U I N T A B A S I N

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M A J O R TAR S A T U R A T E D I N T E R V A L S

BY D E P O S I T

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SUNNYSIDE

ASPHALT RIDGE

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WHITE ROCKS

After Utah Geological Association, 1974.

178

Utah

graphic column and correlation chart of the Uinta Basin with the formations indicated that contain tar, as well as the deposits in which it occurs (Campbell and Ritzma, 1979, Ball and Bard, 1944, and others).

Three of the deposits—Sunny side, P.R. Spring and Hill Creek—occur in the same lithological unit, the Douglas Creek member of the Green River formation. In these deposits, the oil-bearing lacustrine sediments are often interbedded with essentially barren tongues of non-lacustrine sediments that are lithologically similar to the Wasatch formation. Although the lithology varies greatly over the basin, the Green River formation is composed predominantly of six major rock types. These are marlstone, sandstone or siltstone, claystone, oil shale, dolomite and limestone. Sandstone and siltstone are the major rock types that are tar-impregnated.

These three deposits have been interpreted as representing ancient deltas with a predominantly southwesterly sediment source. The depositional environment fluctuated between fluvial and shallow water lacustrine of deltaic origin. This resulted in complex interfingering of lacustrine and fluvial sediments which led to numerous tar zones in all three deposits. The complexity of the subsurface strata makes correlation of zones difficult between wells (Campbell and Ritzma, 1976, Picard, 1971, Picard and High, 1970, and others). The hydrocarbons that originated in these shallow-water lacustrine source rocks migrated only short distances within the Tertiary strata. This migration was presumably facilitated by faulting and unconformable relationships between strata (Hunt, Stewart and Dickey, 1954, Campbell and Ritzma, 1979).

The fourth major deposit, Whiterocks, is located in the northern Uinta Basin. It occurs in the Navajo sandstone of Jurassic Age which is a cross-bedded, fine-grained sandstone of eolian origin. Due to major faulting and regional deformation, the oil-impregnated rock dips southeast locally at angles of 70° or more (Covington, 1964).

Asphalt Ridge, the fifth major tar sand deposit, is in the northeastern Uinta Basin. It is a

northwest-southeast trending hogback of Upper Cretaceous and Tertiary strata. Asphalt Ridge proper is distinguished from the adjoining Asphalt Ridge N . W . deposit by a northeast trending fault. In this study, the two deposits are treated collectively.

Bitumen at Asphalt Ridge is found primarily in the basal Mesaverde group of Cretaceous Age, which is composed of several formations of marine origin. The two major formations are the Asphalt Ridge sandstone (lower) and the Rimrock sandstone. These two formations are separated by a thin shale member. The Mesaverde is unconformably overlain by Tertiary strata. The majority of the Asphalt Ridge resource is attributed to the Rimrock formation, although local impregnation is found in the Williams Fork member, also of the Mesaverde Group. The Rimrock is generally a fine-grained sandstone containing numerous chert grains. Late Cretaceous and Tertiary strata crop out along the entire length of the ridge and dip at 10 to 55 degrees southwesterly into the Uinta Basin (Kayser, 1966, Covington, 1964, Spieker, 1930, and others).

Southeastern U t a h

The four major tar sand deposits of Southeastern Utah are: Tar Sand Triangle, Circle Cliffs, San Rafael Swell, and Nequoia Arch.

Stratigraphically, the Tar Sand Triangle deposit is found primarily in the White Rim sandstone of Permian Age and to a lesser extent in the Triassic Moenkopi. The Circle Cliffs and San Rafael Swell deposits occur in the Moenkopi formation. The exact stratigraphic position of the Nequoia Arch tar deposit is unclear, although major tar saturation is attributed to the White Rim and, to a lesser extent, the Moenkopi. Figure 106 (seepage 180) is the generalized stratigraphic column for southeast Utah with the tar-impregnated formations indicated.

The geology of the White Rim and Moenkopi is summarized below.

179

Tar Sand/Heavy Oil Deposits

FIGURE 106

GENERALIZED STRATIGRAPHIC COLUMN—SOUTHEAST UTAH

UNCONFORMITY

After Steele-Mallory. 1982.

180

Utah

White Rim Sandstone. The Whi t e Rim sandstone is part of the Cutler group of Permian Age. The sands represent a coastal dune field that was deposited by onshore winds during a period of marine transgression. Cross-bedding and laminae are common and the sands are predominantly fine to very fine-grained (Steele-Mallory, 1982). The sandstone forms an elongated northeast-southwest trending body which abruptly pinches out eastward into the non-marine Organ Rock Shale on the northwest plunge of the Monument Upwarp, stratigra-phically trapping the oil of the Tar Sand Triangle deposit (Campbell and Ritzma, 1979, Baars and Seager, 1970). The oil accumulation of the Nequoia Arch appears to be structurally controlled by a series of folds.

Tke Moenkopi Sandstone. The Moenkopi formation of Triassic Age unconformably overlies the White Rim sandstone and has been divided into five members. Major bitumen saturation occurs in the middle sandstone and siltstone unit, the Torrey member.

The Moenkopi is interpreted as stemming from a mixture of depositional environments, including shallow marine, deltaic, lacustrine and floodplain. In the zones of tar accumulation, the formation generally displays horizontal, even bedding. The Moenkopi is locally underlain by the Organ Rock Shale of Permian Age (Blakey 1970, 1977). The trapping of the oil in the Moenkopi appears to be primarily a function of stratigraphy.

Geologic data indicate that the oil of the southeastern Utah tar deposits originally migrated in excess of 100 miles southeasterly from mature, black shale source rocks of Permian Age and was first trapped in paleostructural closures in the Nequoia Arch region. The oil remigrated into the present accumulations as a result of activity in late Cretaceous, early Cenozoic time, the last of a series of orogenic events that created the Rocky Mountain Range.

I N D I V I D U A L DEPOSIT DESCRIPTION

P.R. Spring

Location. The P.R. Spring tar deposit is located

in the southeastern part of the Uinta Basin in Grand and Uintah Counties, Townships 12 through 17 South and Ranges 21 through 25 East. It covers an area of 185,000 acres. The topography is rugged, characterized by valleys and steep cliffs.

Geology. The tar impregnation at P.R. Spring is found primarily in the Douglas Creek member of the Green River formation of Eocene Age. The sands are interpreted to have originated as a prograding deltaic complex with a sediment source from the southwest (Byrd, 1970, Campbell and Ritzma, 1979).

The P.R. Spring deposit consists of seven tar-impregnated zones. A diagrammatic cross section of the deposit is shown on Figure 107 (see page 182) that illustrates the many tar-impregnated zones and their erratic nature. The tendency of the migrating oil was to settle in the numerous, vertically separate lacustrine sediments resulting in these numerous oil-impregnated zones. The sediments are primarily arkose with contributing amounts of quartz and authigenic carbonate. The intervals with tar are separated by various sedimentary units that include oil shale, such as the "Mahogany ledge" marker on Figure 107. (Picard and High, 1971).

The regional dip of the beds is gentle at two to four degrees northwest. The main structural feature is the Hill Creek Anticline which transects the southwestern part of the area from northwest to southeast. Local faulting is minor with small displacements.

Many of the bituminous sands are exposed parallel to major northward-draining valleys. Observation of outcrops and core data indicate that the overburden increases to the north, reaching a thickness of several hundred feet (Campbell and Ritzma, 1979).

Determination of Field Outline. Geological interpretation and well data were used to determine the measured and speculative field outlines. The well data consisted of 19 cores and 7 drillers logs, available from the Utah Geological and Mineral Survey and private sources.

s •5

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Utah

The general rule of classifying areas with core analyses as measured and areas with drillers logs as speculative was conservatively followed. Because of the erratic and discontinuous pay zones, extrapolation based on geology of the deposit boundary from available well data was limited to four sections, instead of nine for the measured area.

The measured P.R. Spring deposit consists of a larger main area, called the Central P.R. Spring area, that is bounded to the south by outcrops at Book Cliffs and a smaller northeastern area, called Northeast P.R. Springs, that is separated from the main area by a canyon. In addition, there are localized areas of measured resource within the speculative areas.

The measured field outline for the Central P.R. Spring area was determined from well data and dominant geographical features. The southwest border was delineated by a drainage valley. The other boundaries of the main area were determined by limited extrapolation from core and logged well data. The measured area for the Northeast P.R. Springs area was determined mainly by well data, although outcrops were used to establish field boundaries in two places. The various smaller and localized measured areas consist of four sections each, as defined by core data.

The speculative area extends on both sides of the main measured area and was determined by the trend and extent of reservoir sands to the north, east and west, as indicated by scattered well control and by outcrops to the south along canyon walls (Dahm, 1980).

A speculative resource is not extrapolated from the northeastern measured area because this area is characterized by erratic saturation with abrupt decreases in richness occurring between wells spaced as close as two miles apart and the presence of dry holes along two of the borders.

A field outline map of P.R. Spring is shown on Figure 108 (seepage 184). Also indicated is the location of wells for which data were available.

Reservoir Properties. A distinguishing characteristic of the P.R. Spring tar deposit is its

high permeability (700 md) and relatively high oil saturation, averaging 5 2 percent. Key reservoir properties are summarized below.

RESERVOIR PROPERTIES—P.R. SPRING

Depth (feet) Porosity (%)

- Range - Average Permeability (md) Oil Saturation (%) - Maximum - Average

0-300

18-30 26

700

75 52

The richest area of the P.R. Spring tar deposit contains 100 feet of pay (in several overlying zones) with a richness of over 1,000 barrels per acre-foot. This area trends northeast-southwest in the central portion of the deposit, close to the presumed original sediment source for the delta complex. The richness declines gradually toward the northeast where intervals of high saturation (50,000 barrels per acre) occur locally surrounded by leaner (0-10,000 barrels per acre) areas. The average oil content and net pay by resource contour and area are summarized below. The table shows that the richness is generally between 800 and 1,000 barrels per acre-foot and thus that the resource in-place per acre depends mainly on the net pay.

RICHNESS AND NET PAY DISTRIBUTION— P.R. SPRING

Resource Contour

• Measured Area

Barrels Per Acre-Foot

Range

Central P.R. Spring 100,000+B/A 50,000-100,000 B/A 650-1,100 10,000-30,000 B/A 400-1,300 N.E. P.R. Spring 50,000-100,000 B/A 30,000-50,000 B/A 10,000-30,000 B/A 10,000 B/A

• Speculative Area**

Central P.R. Spring 50,000-100,000 B/A 0-10,000 B/A

960-1,500

770-800

Avg.

1,060* 950 800

2,000* 1,200 1,100*

780

950* 780*

'Contour is defined by one well. "Assumed the same as the measured area contour.

Net Pay, Feet

Range Avg.

100* 40-90 65 15-64 20

25* 25-41 31

20* 7-13 10

65** 10**

Tar Sand/Heavy Oil Defwsits

FIGURE 108

FIELD OUTLINE MAP—P.R. SPRING, UTAH

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184

Utah

Bitumen Properties. The tar is characterized by high viscosity and low sulfur content, as shown below.

BITUMEN PROPERTIES—P.R. SPRING

Gravity (°API) 9 Viscosity (cp)

- 140°F 400,000 - 77° F 1,000,000

Sulfur (wt. %) 0.4

Resource In-Place. The estimated measured resource in-place at P.R. Spring is 2.1 billion barrels underlying 60,000 acres. The speculative resource in-place is estimated to be 2.2 billion barrels of oil underlying 125,000 acres. A summary of the resource estimate is shown on the following table by resource contour and area.

About 6 0 % of the measured resource is in the Central P.R. Spring area with a resource in-place above 50,000 barrels per acre. The

Northeast P.R. Spring area contains about one-quarter of the measured resource, and is generally less than 50,000 barrels in-place per acre. The majority (64 percent) of the speculative resource stretches in a band to the southwest of the main measured area. This is shown on the richness map of P.R. Spring which also gives resource contours, Figure 109 (seepage 186).

Development History. In 1982, an experimental tar mining and surface extraction plant was operating at P.R. Spring, but the results of this pilot test are not known.

Hill Creek

Location. The Hill Creek deposit covers 87,000 acres and is located in Uintah County in Townships 13 through 15 South and Ranges 19 through 21 East. The deposit is remote from all-weather roads and services in a highly dissected region which extends northward and westward from a high topographically flat area called Flat Rock Mesa.

Geology. The bitumen of the Hill Creek deposit is found primarily in two major zones of the Douglas Creek member of the Green River formation of Eocene Age. The upper zone (Zone 1) lies below major oil shale beds and above the Mahogany oil shale bed. The lower zone (Zone 2) lies below and adjacent to the Mahogany oil shale (Johnson, Marchant and Cupps, 1976). Figure 110 (see page 187) shows a general cross section and the correlation of the zones of the Hill Creek deposit of the Flat Rock Mesa area.

The Hill Creek Anticline is the major subsurface structure in the area, a northward dipping structurally asymmetric feature which lies in the southern part of the deposit. However, the oil appears to be stratigraphically trapped rather than structurally trapped.

Determination of Field Outline. Geological interpretation and well data were used to determine the measured and speculative field outlines. The well data consisted of three wells with core analysis in the southeastern part of the deposit. The core data were obtained from the Utah Geological and Mineral Survey with

ESTIMATE OF RESOURCE IN-PLACE P.R. SPRING

Resource Contour

• Measured Area

Central P.R. Spring

100,000+ B/A 50,000-100,000 B/A 10,000-30,000 B/A

Subtotal

N.E. P.R. Spring

50,000+ B/A 30,000-50,000 B/A 10,000-30,000 B/A 0-10,000 B/A

Subtotal

Total Measured

• Speculative Area

Central P.R. Spring

50-100,000 B/A 0-10,000 B/A

Total Speculative

Barrels Per Acre

(Avg.)

100,000 60,000 16,000

50,000 37,000 20,000 8,000

60,000 8,000

Areal Extent

(Acres)

2,600 20,500 7,700

30,800

2,600 5,700 2,600

17,900

28,800

59,600

23,700 101,100

124,800

Resource In-Place (MMB)

260 1,230

120

1,610

130 210 50

140

530

2,140

1,420 810

2,230

185


FIGURE 109

FIELD RICHNESS MAP—P.R. SPRING, UTAH

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LEGEND MEASURED AREA SPECULATIVE AREA OUTCROP

| | 0-10,000 B/A

|. ' .1 10,000-30,000 B/A

gg jg j 30 ,000-50 .000 B/A

50 ,000-100,000 B/A

100,000+B/A

Prepared by Lewin and Associates. Inc., 1983.

186

Utah

FIGURE 110

CORRELATION OF TAR ZONES—HILL CREEK, UTAH

7600

7400

7200

7000 TO 268 f « l

6800

,HC-2

TO 488 f « t

Salt, milts

\S£ WNW

Z O M 2

TO 500 ft«

LOCATION R18E

j J I J

9 1 ? ? * Scale, miles

R19E

-*l 0)1 0)1 k_ 1

o l =( l [

\ )

""^" \

R20E

HC-1

^ 4 i £ l 2 HC-3 A

'

R21E

-*/ <z>7 QJi

Oj if

-£v :?/

\

I

*

T13S

T14S

T15S

Alter Johnson. Marchant, Cupps, 1976.

187


additional reservoir characteristics from State and Federal reports. One of three wells showed no tar saturation in Zone 2, so the areal extent of Zone 1 is larger than that of Zone 2. The geological data draws heavily on the extensive outcrops along drainage valleys.

The measured boundaries were determined from the three cored wells using the general rule of extrapolating around the wells approximately one mile to the north and two miles south to the jointed faulted zone which runs along the length of the border. The western border of the measured area is defined by outcrops along Hill Creek Canyon.

The speculative boundaries were delineated by shows along canyon walls, except to the north, where the speculative area extends to shows of tar-impregnated sands on both sides of Hill Creek Canyon and associated drainage valleys. The deposit is controlled to the south by the continuous jointed/faulted zone and to the west by a stratigraphic pinchout of the bitumen-bearing sands. To the east, the deposit is defined by the outcropping of the reservoir sands in Willow Creek Canyon (Campbell and Ritzma, 1979). Field outline maps of Zone 1 and Zone 2 are shown on Figures 111 (see page I8Q) and 112 (seepage 190), respectively, together with the tar outcrops and location of the cored wells.

Reservoir Properties. Distinguishing characteristics of the Hill Creek reservoir properties are the variable permeability (100-1,000 md) and a combination of medium to low average porosity and oil saturation. Key reservoir properties are shown below for the two zones.

RESERVOIR PROPERTIES—HILL CREEK


- Range - Average

Permeability (md) Oil Saturation (%)

- Maximum - Average

Zonel

0-300

21-30 24

100-1,000

40 38

Zone 2

2WMO0

21-30 24

100-1,000

43 30

The area of the richest measured resource contains 30,000 barrels per acre and stretches 3 miles (Zone 1) or 2 miles (Zone 2) east from the Hill Creek Canyon and 2 miles along the north to south trending canyon. Outside this area, the resource rapidly decreases to 5,000 barrels per acre (Zone 1) or less (Zone 2) in the speculative area.

The average values for oil content and net pay by resource contour are shown below. The core data indicates that richness in both zones decreases to the east.

The Zone 1 speculative area is assumed to have reservoir characteristics similar to the lowest resource contour of the measured field. The core data indicate lower richness for Zone 2. Therefore, the barrels per acre for the speculative area Zone 2 is assumed to be one half that of the lowest measured resource contour.

RICHNESS AND NET PAY DISTRIBUTION-HILL CREEK

Resource Contour

• Measured Area


Range Avg.

Zonel 10,000-30,000+ B/A 700-710 705 0-10,000 B/A 500*

Zone 2 10,000-30,000+ B/A 0-10,000 B/A


Zone 1 0-10,000 B/A

Zone 2 0-10,000 B/A

970 375*

500"

185"

Net Pay, Feet Range Avg.

43-46 45 11*

31 14*

11

14 'Richness contour defined by one well.

' 'A ssumed the same as (Zone 1) or halt (Zone 2 where one well is dry) as the measured area contour.

Bitumen Properties. The bitumen at Hill Creek has a gravity of 9° API and a very low sulfur content of .4 weight percent.

Resource In-PIace. The measured resource in-place at Hill Creek is estimated to be 0.3 million barrels underlying 10,000 surface acres. The speculative resource in-place is estimated

188

Utah

FIGURE 111

FIELD OUTLINE MAP—HILL CREEK, UTAH Zone 1

R18E R19E R20E R21E

i) i ;' Mil.in J =l

Scale

Prepared by Lewin and Associates, tnc , 1983.

LEGEND

— MEASURED AREA • - » • • SPECULATIV€ AREA IIIIIIIIU OUTCROP

• WELLS WITH CORF. DATA

LOCATION

189

TOT Sand/Heavy Oil Deposits

FIGURE 112

FIELD OUTLINE MAP-HILL CREEK, UTAH Zone 2

R 1 8 E R 1 8 E R 2 0 E R 2 1 E

I 0 1 ? Mllds;

Sca le


o

LEGEND

MEASURED AREA SPECULATIV£ AREA OUTCROP

WELLS WITH CORE DATA

NO TAR SHOW

LOCATION

\>

CASTCTW

(MEAT

BASH

«\ UWTAy^JT

v V u r* •*» j\^\

\kL / ± # f PARADOX BASM

J ^ ^ 190

Utah

to be 0.6 billion barrels underlying 77,000 surface acres.

The majority of both the measured and speculative resource occurs in Zone 1, as shown in the following table.

ESTIMATE OF RESOURCE IN-PLACE— HILL CREEK

Resource Barrels Contour Per Acre

(Avg.)

• Measured Area

Zone 1 10,000-30,000 B/A 30,000 0-10,000 B/A 5,000

Subtotal

Zone 2 10,000-30,000 B/A 30,000 0-10,000 B/A 5,000

Subtotal

Total Measured


Zone 1 0-10,000 B/A 5,000

Zone 2

0-10,000 B/A 2,500

Total Speculat ive

Areal Extent

(Acres)

5,700 4,400

10,100

3,900 2,500

6,400

76,800

73,000

Resource In-Place

(MMB)

170 20

190

120 10

130

320

380

180

560

Figures 113 (see page 192) and 114 (see page 193) are richness maps of the Hill Creek deposit by zone. The richest areas in both zones occurs to the east of Hill Creek Canyon in the southern part of the field.

Development History. There is no known development of the Hill Creek tar deposit.

Sunnyside

Location. The Sunnyside tar sand deposit covers 78,000 acres and is located in Carbon County in Townships 12 ,13 , and 14 South and Ranges 13, 14, and 15 East. Although located in an area of rugged terrain, it is less remote than other Uinta Basin tar deposits, since it is within 10 miles of a railroad and a state highway.

Geology. The tar sands in the Sunnyside deposit are found primarily in the lacustrine sediments, equivalent in part to the Douglas Creek member of the Green River formation of Eocene Age. The member is overlain by predominantly finegrained rocks with thin but prominent oil shale beds. The deposit is interpreted as part of an ancient deltaic complex (Campbell and Ritzma, 1979).

The tar sand crops out along the western edge of the deposit. A generalized cross section shows that the tar sands consists of up to eight tar-saturated zones with interspersed thin shale barriers, Figure 115 (seepage 194).

A topographic profile of Sunnyside is also shown on Figure 115. It illustrates the dramatic changes in topography with maximum elevations of about 10,000 feet and local reliefs of up to 1,000 feet.

Structurally, the area is a homocline with dips 3 to 10 degrees east-northeasterly. The dip decreases gradually northeastward into the Uinta Basin. The deposit is characterized by abundant vertical fractures.

Determination of Field Outline. Geological interpretation and well data were used to determine the measured and speculative field outlines for the Sunnyside tar deposit. The well data consisted of 13 cores available from private sources, plus information from private reviewers about the northern and western extent of the deposit.

The tar-impregnated sandstone crops out along the western border of the deposit with additional saturated outcrops reported to the east. In the northwest, outcrops containing tar are found in sections 30 and 31 (unmapped) of Township 12 South, Range 14 East.

The boundaries of the measured area were determined as follows:

• The eastern and southern borders were defined by outcrops and modified as necessary to include areas with wells showing tar.

191


FIGURE 113

FIELD RICHNESS MAP—HILL CREEK, UTAH Zone 1

niHE R19F R20E R21E

Prepared by Lewin and Associates, Inc.. 1983.

•mm • MEASURED AREA

SPECULATIVC AREA

OUTCROP

0-10.000 B/A

10.000-30.000 B/A

192

Utah

FIGURE 114

FIELD RICHNESS MAP—HILL CREEK, UTAH Zone 2

R 1 8 E R 1 9 E R 2 0 E R21E

=J_ Sca le

I 2 Mi!«« I I


LEGEND

MEASURED AREA

SPECULATIV€ AREA

OUTCROP

0 - 1 0 . 0 0 0 B/A

1 0 . 0 0 0 - 3 0 . 0 0 0 B /A

LOCATION

193

FIGURE 115

CROSS SECTION (A-A) AND TOPOGRAPHIC PROFILE (B-B)—SUNNYSIDE, UTAH CROSS SECTION

Bituminous Sandstones

Siltstone, Shale

500 After USGS. Preliminary Map 86. 1948

Scale. Feet

Tilt

T 1 «

LOCATION RtM *H» HIM

> J ^ V SUNNY! W | \ DEPO

I T l «

T I M

TIM 1

•k^A'

V i • \

SUNHYSICC

c.

E

!

i

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M

HBON COUNTY

«ERY COUNTY

\ N 1

TOPOGRAPHIC PROFILE

B Elevation, Feet

10000

I M S f t M E T U S RISE

VERTICAL EXAGGERATION-*


Utah

• The western and northern field boundaries were defined as one section outward from the nearest cored well, as adjusted by substantiated data from private sources.

The speculative field boundaries extend east and north of the measured area. They include areas where tar-impregnated intervals crop out above the canyons to the east, and include reported bitumen occurrences to the north. Figure 116 (see page 106) is the field outline map of the Sunnyside tar sand deposit, showing the location of the cored wells and outcrops used to establish the field boundaries.

Reservoir Properties. The Sunnyside tar sand deposit is characterized by the extensive tar-impregnated intervals along the eastern edge of the deposit. Key reservoir properties for Sunnyside are summarized below.

RESERVOIR PROPERTIES-


- Range - Average


- Maximum - Average

-SUNNYSIDE

0-500

10-28 24

800-1,000

65 50

The eastern edge of the Sunnyside deposit is very rich and contains approximately 600,000 barrels per acre. This area extends two miles northwest-southeast along the central part of the outcrop. The high resource in-place is due both to high richness (over 1,000 B/AF) and considerable pay thickness of 200 to 500 feet. The richness of the deposit decreases gradually to the east and north away from the outcrop, reflecting the deltaic deposition of the sands.

The barrels per acre-foot and net pay for the measured and speculative areas are shown by resource contour in the table at the top of the next column.

RICHNESS AND NET PAY DISTRIBUTION—SUNNYSIDE

Resource Contour

• Measured Area

600,000+ B/A 300,000-600,000 B/A 100,000-300,000 B/A 50,000-100,000 B/A 0-50,000 B/A

• Speculative Area*

0-50,000 B/A

Barrels Per Acre-Foot Net Pay,

Range Avg. Range

1,050-1,450 1,100 545-650

1,150-1,400 1,280 200-450

600-1,400 975 105-210

700* 950*

t

950

'Contour is defined by one well. "Assumed the same as the measured area contour.

Feet

Avg.

550

310

145

100* 44*

44

Bitumen Properties. The Sunnyside bitumen has a gravity of 8°API and is characterized by high viscosity, 100,000 cp at reservoir temperature, and a low sulfur content of 0.7 weight percent.

Resource lrt'Plctce. The measured Sunnyside resource in-place is estimated to be 4.4 billion barrels underlying 35,000 acres. The speculative resource in-place is estimated to be 1.7 billion barrels underlying 44,000 acres.

About 9 0 % of the measured Sunnyside resource and 6 0 % of the acreage occurs where there are more than 100,000 barrels per acre. A summary of the resource estimate by resource contour is shown below.

ESTIMATE OF RESOURCE IN-PLACE—SUNNYSIDE

Resource Contour

*

• Measured Area 600,000+ B/A 300,000-600,000 B/A 100,000-300,000 B/A 50,000-100,000 B/A 0-50,000 B/A

Total Measured

• Speculative Area 0-50,000 B/A

Barrels Per Acre

(Avg.)

600,000 400,000 140,000 70,000 40,000

40,000

Areal Extent (Acres)

650 2,550

16,650 4,450

10,250

34,550

43,500


400 1,000 2,300

300 400

4,400

1,700

195

Jar Sand/Heavy Oil Deposits

FIGURE 116

FIELD OUTLINE MAP—SUNNYSIDE, UTAH

T 1? 8

T 13 8

T 14 a

T 16 8

M

•

f t

u

4

•

I *

u

:

n

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lt

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•

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Prepared by Lewin and Associates. Inc., 1983.

LEGEND

M ^ MEASURED AREA

• • • SPECULATIVE AREA

^ ^ OUTCROP

# WELLS WITH CORE DATA

-0 - NO TAR SHOW

196

LOCATION

Utah

Figure 117 (seepage 198) is the field richness map of the Sunnyside deposit. As shown, the richest portion of the deposit with more than 600,000 barrels per acre is located in the center of the measured area, adjacent to the western outcrop.

Development History. The b i tuminous sandstone at Sunnyside is known to have been quarried between 1892 and the late 1940s. In 1963 and 1966 Shell Oil Company experimented with an in-situ steamflood technique to evaluate the possibility of recovering oil through induced or natural fracture systems. However, the natural vertical fractures in the formation prevented the build-up of sufficient pressure or energy in the formation to drive the oil, and Shell terminated the test.

In 1966, Signal Oil conducted steam soak tests at Sunnyside using horizontal holes drilled from the outcrop. Total oil production was 560 barrels with an average oil/steam ratio of 0.042. (Energy Research Institute, 1976, Campbell and Ritzma, 1979). Currently (1983), GNC and Chevron plan to mine and surface extract the tar resource along the eastern outcrop.

Whiterocks

Location. The Whiterocks deposit covers 400 acres and is located in Uintah County in Townships 2 North and Ranges 1 West and 1 East, about 25 miles northwest of the town of Vernal. The Whiterocks Canyon is located at a right angle to the deposit and has tar impregnation on both sides.

Geology. The tar sands of the Whiterocks deposit are found in the Navajo sandstone, which dips from 70° to near vertical due to a major regional uplift and folding. Severe faulting has caused a large offset of the Navajo and other formations in the subsurface. However, within the limits of the deposit as seen at the surface, local faulting is small. Figure 118 (seepage 199) is a generalized cross section of the deposit showing the oil-impregnated formation, the steep dip and the regional faulting.

Oil impregnation occurs in the upended portion of the Navajo from the surface down to an apparent oil-water contact at approximately 600 feet. The over-and underlying stata are impervious shales of the adjacent Chinle and Carmel formations which have sealed the oil in the Navajo. It has been suggested that the oil is Tertiary and has migrated across joints and unconformities to the Jurassic Navajo. However, original paths of migration are not clear and Paleozoic source rocks have been suggested as an alternative hypothesis for the source of the hydrocarbons (Covington, 1964).

Determination of Field Outline. Geological interpretation and well data were used to determine measured and speculative field outlines. The well data consisted of nine cored wells available from private sources. The core analyses were used to delineate the measured area. Geological extrapolation of tar-impregnated sand formed the basis for the speculative resource area.

The measured boundary of the tar deposit is limited to the east by a normal fault and to the west by an unconformable contact with Tertiary strata. To the north and south, the tar saturation is sharply delineated by the extent of the Navajo sandstone.

Within the 200-acre measured area, the tar-impregnated sandstone crops out along both flanks of the Whiterocks Canyon, which cuts through the center of the deposit. In the subsurface, the tar extends down to the water/oil contact in the steeply dipping Navajo sandstone.

The speculative area consists of an additional 200 acres of tar saturation along the strike of the Navajo beneath the unconformable contact. The boundaries for the speculative area are based on previously reported geological data (Covington, 1964) and reviews by private sources.

The field outlines for the measured and speculative areas are shown on Figure 119 (see page 200). The figure also shows the location of the wells used in the analysis and the geologic features and the tar outcrops that helped establish the boundaries. As shown, the Whiterocks tar deposit

197


FIGURE 117

FIELD RICHNESS MAP-SUNNYSIDE, UTAH

1 2 Miles I I

Prepared by Lewtn and Associates, Inc., 1983.

•

LEGEND

MEASURED AREA

SPECULATIVE AREA

OUTCROP

0-50,000 B/A

50,000-100,000 B/A

100.000-300,000 B/A

300,000-600,000 B/A

600,000+ B/A

198

FIGURE 118

CROSS SECTION—WHITE ROCKS, UTAH

North

8000

-700

- 6 0 0 0

5000

4000

- 3 0 0 0

2000

- 1000

0

- -1000

2 O

< >

CO

/ o C) LU

z 2 OIL-WATER O CONTACT m J

co c/y

a>

z O

LU CO

o CO

z O

CJ

CO

o CO

z o 1 -

o LU CO

z n 1 -

o LU CO

South

After Caldwell and Covington. 1964. Scale

Tar Sand/ Heavy Oil Deposits

FIGURE 119

FIELD OUTLINE MAP—WHITE ROCKS, UTAH

R1W R1E

S c a l e

1.0 Mi les

J

LEGEND

_ _ • MEASURED AREA

» • SPECULATIVE AREA

%m. OUTCROP

• WELLS WITH CORE DATA O WELLS WITHOUT

CORE DATA ( UNCONFORMITY

D/U FAULT

T" STRIKE AND DIP _________________——-————

LOCATION

?x '•*kS •i*VA~'/"^ um*4*in

***** T jh\ 4

I +5 J WMOOX I A »

^jA^-x^-,\


M

200

Utah

has a 2,000-foot wide and a two-mile long trapezoid configuration.

Reservoir Properties. Distinguishing characteristics of the Whiterocks reservoir are the moderately low permeability, 10-125 md, and extremely high dip of up to 70°. Key reservoir properties are summarized below.



- Range - Average


- Maximum - Average

-WHITEROCKS

14-130

14-30 20

10-125

53 39

The average richness is relatively low at 600 barrels per acre-foot, but the resource in-place per acre is high because of the 500-foot thickness.

The resource in-place is thus estimated at 300,000 barrels per acre. This estimate is based on a proprie tary industry analysis of the Whiterocks deposit. In this study, selected core intervals were analyzed and estimates of oil content were derived by visual comparison of these intervals with the data from extensive core analysis. Thicknesses and correlation of saturated intervals were derived from drillers log and lithological descriptions.

The average, as well as the range of oil content and net pay for the Whiterocks deposit, is shown below.

RICHNESS AND NET PAY DISTRIBUTION—WHITEROCKS

Resource Barrels Per Contour Acre-Foot Net Pay, Feet

Range Avg. Range Avg.

• Measured Area

300,000 B/A 460-820 600 200-700 500

• Speculative Area 300,000 B/A 600* 500*

'Assumed to be the same as the measured area contour.

Bitumen Properties. The gravity of the bitumen in the Whiterocks tar deposit ranges from 4° to 12° API. The sulfur content is 0.4 weight percent.

Resource In-Place. The measured resource in-place is estimated to be 60 million barrels underlying 200 acres. The speculative resource in-place is estimated to be an additional 60 million barrels under 200 surface acres.

A summary of the resource estimate is shown below.

ESTIMATE OF RESOURCE IN-PLACE— WHITEROCKS

Resource Barrels Areal Resource Contour Per Acre Extent In-Place

(Avg.) (Acres) (MMB)

• Measured Area 300,000 B/A 300,000 200 60

• Speculative Area 300,000 B/A 300,000 200 60

Figure 120 (see page 202) is the field richness map of the Whiterocks deposit showing the oblong nature of the deposit.

Development History. In 1957 and 1958, three wells were drilled through the Navajo at Whiterocks to find conventional oil. None was found, but the presence of the thick tar sands was confirmed.

Asphalt Ridge/Asphalt Ridge N.W.

Location. The Asphalt Ridge and adjacent Asphalt Ridge N.W. deposits cover an area of 51,000 acres and are located in Uintah County in Townships 4, 5 and 6 South and Ranges 20, 21 and 22 East.

Geology. The tar sands at Asphalt Ridge and Asphalt Ridge N.W. are found primarily in the Rimrock sandstone of the Mesaverde group of Cretaceous Age. The formation crops out conspicuously along the entire length of a ridge

201


FIGURE 120

FIELD RICHNESS MAP—WHITE ROCKS, UTAH

i

Sjo z X <0.<

II

! T I 2 • N

14

23

26

R1W R1E f

13 18 J

\ Vu

24 ^ H l ^ j i i l P ^ k

25

a\

30 J L '

0 0,5 1.0 Miles \ 1 ., 1

Scale

LEGEND

• H M MEASURED AREA

« • SPECULATIVE AREA

I P | | 300.000 B/A

{ UNCONFORMITY

D/U FAULT

T" STRIKE AND DIP

17

20

29

i

M

LOCATION

^ l -*A 5^* ••' -~~~ """

I W I "TJCN. 4>

_34p= -

Prepared by Lewin and Associates. Inc.. 1983.

202

Utah

where it is unconformably overlain by the Duchesne River formation of Eocene Age,

Figure 121 (see page 204) is a schematic cross section of Asphalt Ridge that shows the outcrop of the oil-impregnated Mesaverde group sandstone and its extension into the subsurface. The deposit consists of two areas of bitumen saturation extending downdip from the outcrop. Net thickness of the tar-impregnated interval ranges from 10 to 80 feet. The depth of the deposit is approximately 500 feet near the outcrop, dipping to over 1,500 feet in a space at two miles southwest of the surface exposures. The strata dip from 10 to 55 degrees southwesterly and oil-impregnation occurs along the northwest strike of the ridge. The Rimrock sandstone varies from less than 100 feet to over 300 feet in thickness due to variable truncation of the unit prior to deposition of younger strata (Kayser, 1966).

Determination of Field Outline. Geological interpretation and well data were used to determine the measured and speculative field outlines. The well data consisted of 18 cores available from past drilling by the U.S. Department of Energy and private companies. In addition, five drillers logs were available from private sources.

The measured boundaries of the tar resource were determined by extrapolating approximately one mile to the south and west from the cored wells. The area between the two major accumulations is also assumed to be measured as indicated by shows of tar in drillers logs. The northern boundary is based on industrial review and proprietary data. To the east, the formation crops out and the boundary is controlled by geology.

The speculative area is extrapolated one to two miles (except to the north) from the measured area and assumes a continuing decrease in richness, as indicated by core data and as reported by oil shows in drillers logs and lithological descriptions. A field outline map is shown in Figure 122 (see page 205). Also shown are the location of wells for which data are available.

Reservoir Properties. Key reservoir properties for Asphalt Ridge are shown in the following table.


Depth (feet) Porosity (%) Permeability (md) Oil Saturation (%)

- Maximum - Average

-ASPHALT RIDGE

20-600 27

1,000+

60 48

The two outcrops are the richest areas of the measured field. The richness ranges from 300 to more than 1,200 barrels per acre-foot; the net pay ranges from 35 to 50 feet. The average barrels per acre-foot and net thickness by resource contour are summarized below.

DISTRIBUTION OF RICHNESS AND NET PAY —ASPHALT RIDGE

Resource Contour


Range Avg.

• Measured Area 60,000+ B/A 700-1,200 850 20-60,000 B/A 580-950 775 0-20,000 B/A 300-1,000 400

• Speculative Area 0-20,000 B/A 400*

"Assumed the same as measured area contour.

Net Pay, Feet

Range Avg.

25-83 50 22-100 35 7-60 35

35*

Bitumen Properties. The tar sand at Asphalt Ridge is very viscous at over 1,000,000 cp, and low in sulfur content at 0.4 weight percent.

Resource In-PIace. The measured resource in-place at Asphalt Ridge is estimated to be 0.8 billion barrels underlying 29,000 acres. The speculative resource in-place is estimated to be 0.3 billion barrels under 22,000 surface acres.

A summary of the resource estimate is shown below.

SUMMARY OF RESOURCE IN-PLACE

Resource Contour

• Measured Area 60,000+ B/A 20-60,000 B/A 0-20,000 B/A

Total


Barrels Per Acre

(Avg.)

40,000 28,000 14,000

14,000

—ASPHALT RIDGE


3,200 11,000 14,700

28,900

22,000

Resource In-PIace (MMB)

190 440 200

830

310

203

FIGURE 121

CROSS SECTION—ASPHALT RIDGE, UTAH

SOUTHWEST

UINTA BASIN ASPHALT RIDGE

OIL-IMPREGNATED S SANDSTONES

NORTHEAST

ASHLEY A' VALLEY

OLIGOCENE , _*_5000

HORIZONTAL AND VERTICAL SCALES EQUAL

Alter Ritzma, 1974, Campbell, 1975.

N

Prlea

8

g

5'

Utah

FIGURE 122

FIELD OUTLINE MAP—ASPHALT RIDGE, UTAH

T 4 S

T 6 8

•

31

•

S I

\

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0

_ 0

• t t

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>

1

M

. -

\ >

M

R20E

1 0 1 2 1 > t i . ^ i

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11

0 •

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3

_....

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0

^ _

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• • •

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—

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k

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H

M

-

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M

•

as

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•

• ^ • >< • o

3

^

R22E

g^ ^

1 1

M

I

M

J 6 3

R23E

R21E R22E

LEGEND

M M * MEASURED AREA

•»*. SPECULATIVE AREA

^ = OUTCROP

9 WELLS WITH CORE DATA

O WELLS WITHOUT CORE DATA

LOCAT ON

Prepared by Lewin and Associates. Inc., 1983

205


Figure 123 (see page 207) shows a richness map of the Asphalt Ridge deposit. There are two areas with the greatest richness; one at each of the tar-impregnated outcrops containing over 60,000 barrels per acre.

Development History. Tar sands have been quarried from the Asphalt Ridge deposit since the early 1900s, primarily for road paving material.

In addition, several pilot extraction tests have been operated by oil companies at various times since 197 2. The most recent reported pilot tests at Asphalt Ridge were by the Laramie Energy Technology Center of the U.S. Department of Energy. In 1975 through 1978, they completed experimental testing of a combined reverse-forward combustion and a steam injection scheme at Asphalt Ridge, N .W. It was concluded that additional testing of the methods was necessary. There is no present activity at the deposit (Johnson eta l . , 1978, 1981, Mar chant et al., 1979).

Tar Sand Triangle

Location. The Tar Sand Triangle deposit covers an area of 148,000 acres and is located in Wayne and Garfield Counties, between the Dirty Devil and Colorado Rivers. It lies primarily in Townships 30, 30Vi, 3 1 , and 32 South, and Ranges 15, 16, and 17 East. The deposit is in a remote location of rugged topography with a maximum relief of 3,700 feet.

Geology. The tar-impregnated sands of the Tar Sand Triangle deposit are found in the Whi te Rim sandstone and the Moenkopi formation.

The Whi te Rim is a relatively uniform sandstone consisting of medium to coarse quartz grains with excellent reservoir characteristics.

The petroleum is locally trapped by cross-bedding planes and regionally by the White Rim's eastward stratigraphic pinchout.

The elevation above the tar zone and the unconformable contacts between rock units are

shown on Figure 124 (see page 208). This diagrammatic cross section of the White Rim sandstone along the northeast portion of the Tar Sand Triangle deposit shows that the formation crops out to the east and that the strata dip to the west and south at about 1 to 3 degrees.

Along the eastern outcrop the White Rim is characterized by eolian cross-bedding, which markedly contrasts with the deltaic/lacustrine horizontal bedding of the Moenkopi. This is illustrated on Figure 124, which shows the complex depositional environments of the Tar Sand Triangle tar deposit, as determined from the well-exposed and extensive outcrop area.

Determination of Field Outline. Geological interpretation and well data were used to determine the measured and speculative field outlines. The well data consisted of 14 cored wells available from proprietary sources and 10 drillers logs available from the literature and private sources. The overall field outline for the Tar Sand Triangle is established to the east by major truncation of the reservoir sands and to the south and west by the gradual loss of tar saturation.

The measured boundaries of the White Rim tar resource were determined as follows:

• The eastern border coincides with the formation truncation and outcrop.

• The southern and western borders were defined by dry holes and wells with low tar saturation and net pay.

• The northern boundary of the deposit was drawn by extending the measured field outline one section outward from the nearest well with a show.

The speculative area extends south of the measured area, based on repor t s of tar-impregnated outcrops. Figure 125 (seepage 209) shows the field outline of the White Rim deposit and the wells used in the analysis.

Tar occurs in the Moenkopi formation in the same general area as the White Rim sandstone, although the areal extent of the deposit is smaller.

Uiah

FIGURE 123

FIELD RICHNESS MAP—ASPHALT RIDGE, UTAH

R20E R21E

R20E

1 0 1 2 Miles

SCALE

i

H

R23E

R21E R22E

LEGEND

MEASURED AREA

SPECULATIVE AREA

OUTCROP

0 - 1 0 , 0 0 0 B/A

10,000 - 20 ,000 B/A

20,000-60,000 B/A

6 0 , 0 0 0 + B/A

LOCATION

Prepared by Lewin and Associates, Inc., 1983

207

FIGURE 124

GENERALIZED CROSS SECTION—TAR SAND TRIANGLE, UTAH

CROSS SECTION

7000 -,

6000

5000

4000 Elevat ion f e e t

PROJECTED WEDGE-EDGE OF WHITE RIM SANDSTONE

R

J '

i

/

H— 4-1

1

i.3 C

X

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"

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5000

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DETAIL

SEAWARD LAGOONAL W E

----:; MOENKOPI FORMATION K;^ : ~_-^-~;- ~:A

^ - ^ > { l ^ i r ^ M O R G A N ROCK SHALE -;_

o FEET 50

100 U

3 MILES 1/2

SCALE

1

Alter Baars and Seager, 1970.

Utah

FIGURE 125

FIELD OUTLINE MAP—TAR SAND TRIANGLE, UTAH White Rim Sandstone

R15E R16E

UTAH

GOVT.

o

o

o

O7

L * .

IO | TEXAS PRODUCTION

R U E

30 S

LEGEND

MM MEASURED AREA

• •• SPECULATIVE AREA

Will OUTCROP

A WELL WITH w CORE DATA

O WELL WITHOUT CORE DATA

< • NO TAR SHOW

LOCATION

Prepared by Lewin and Associates, Inc.. 1983.

209


RICHNESS AND NET PAY DISTRIBUTION—TAR SAND TRIANGLE

Resource Barrels Per Contour Acre-Foot Net Pay, Feet


• Measured Area White Rim 100,000+ B/A 960* 110* 50,000-100,000 B/A 600-930 650 100-140 110 20,000-50,000 B/A 580-600 600 25-50 50 0-20,000 B/A 415-500 450 28-30 30

• Speculative Area White Rim 0-20,000 B/A 4 5 0 " 3 0 "

Moenkopi 20,000+ B/A 500* 60* 0-20,000 450-570 500 4-16 12

'Contour defined by one welt. "Assumed the same as the measured area contour.

The entire deposit has been classified as speculative due to limited well control. Figure 126 (see page 211) shows the field outline of the Moenkopi bitumen-impregnated area of the Tar Sand Triangle and the location of five cored wells and several dry wells defining the extent of the deposit. These wells are the same as shown for the White Rim.

Reservoir Properties. A distinguishing characteristic of the Tar Sand Triangle is the cross-bedded and highly variable reservoir sands. Key reservoir properties are shown below.

RESERVOIR PROPERTIES-TAR SAND TRIANGLE


- Range - Average

Oil Saturation (%) - Maximum - Average

White Rim

200-1,300

14-25 22

62 40

Moenkopi

200-1,500

14-21 17

46 40

The richness of Whi te Rim is low at 650 barrels per acre or less, except in the richest area, where there are 960 barrels per acre. Also, this area is characterized by having a significantly larger net pay of 110 feet than the remainder of the deposit. The highest resource in-place per acre is in the central northeast part of the White Rim deposit with an average of 100,000 barrels per acre. The resource in-place decreases sharply to the east toward the outcrop, with a more gradual reduction to the west.

Oil saturation in the Moenkopi sandstone in the Tar Sand Triangle area is considerably less extensive than in the White Rim. The central portion of the deposit appears to have the largest amount of resource in-place at 20,000 barrels per acre.

The range and average oil content and net pay of the White Rim and Moenkopi tar deposits at Tar Sand Triangle are shown in the following table.

Resource In-PIace. The measured resource of the Tar Sand Triangle is an estimated 2.5 billion barrels of resource in-place underlying 93,000 acres. The speculative resource in-place is estimated to be 0.4 billion barrels under 55,000 surface acres. The White Rim sandstone contains all the 2.5 billion barrels of measured and 100 million barrels of the speculative resource in-place. The Moenkopi sandstone is estimated to contain 320 million barrels of tar resource in-place, all of it classified as speculative. A summary of the resource estimate by formation is shown below.

ESTIMATE OF RESOURCE IN-PLACE— TAR SAND TRIANGLE

Resource Contour

• Measured Area White Rim 100,000+B/A 50,000-100,000 B/A 20,000-50,000 B/A 0-20,000 B/A

Total Measured • Speculative Area

White Rim 0-20,000 B/A Moenkopi 20,000+ B/A 0-20,000 B/A Subtotal

Total Speculative

Barrels Per Acre

(Avg.)

100,000 70,000 30,000 13,500

8,000

30,000 6,000


5,800 12,800 17,900 36,000

92,800

12,800

3,000 38,000 42,000 54,800


580 900 540 480

2,500

100

90 230 320 420

210

Utah

FIGURE 126

FIELD OUTLINE MAP—TAR SAND TRIANGLE, UTAH Moenkopi Sandstone

R15E R16E R17E

I O I TEXAS

PRODUCTION

p a » H t a a H i M M M |

m » l " • < ? - •

I- .6,-

T -30

S

' — PH LLIPS O F R E N C H S£

I WAYNE CO. GARFIELD CO.

O SUPERIOR UTAH SO.

GOVT.

l b . . . . . . . . . . J I

«-4-

o MOBIL

ROBBERS ROOST

K ^

-P

S #

3#I

/ £-w* £

£

31 S

N

3 0 ^ --6

LEGEND

• I SPECULATIVE AREA

o

WELL WITH CORE DATA

W E L L WITHOUT C O R E D A T A

NO TAR SHOW

LOCATION

Prepared by Lew in and Assocta tes. Inc.. 1983.

211

/ * / ( r e (,

Oil Deposits

27 (see page 213) and 128 (see page e field richness maps of the White oenkopi sandstone of the Tar Sand

Development History. There is no known development of the Tar Sand Triangle although a number of development proposals and considerable delineation drilling have been reported.

Nequoia Arch

Location. The Nequoia Arch deposit covers an area of over 100,000 acres and is located in Wayne and Emery Counties in Townships 25 through 28 South and Ranges 13 through 16 East. The area is characterized by its low relief and considerable depth of burial of the tar-impregnated interval.

Geology. The Nequoia Arch deposit is found on the Nequoia Arch anticlinal feature also known as the Flattop Anticline (Kelly, 1978). The tar has apparently accumulated in closed subsurface structures in the White Rim and Moenkopi formations. Very little additional stratigraphic or structural information is available.

Determination of Field Outline. Geological interpretation and well data were used to determine the measured and speculative field outlines. The well data consisted of seven cores and 15 drillers logs collected from proprietary sources. Eight of these wells were dry with no show of tar. The deposit has been divided into two areas; a north deposit and south deposit. These two deposits are structurally separated by the prevalent folds of the area.

The measured boundaries of the tar resource are based on dry holes, core data and drillers logs, using the general rule of extrapolating between and outward from cored wells based on geology.

The speculative boundaries of the area are based on structural and geological information from industrial sources.

The field outline map of the Nequoia Arch tar deposit is shown on Figure 129 (see page 215) along with the locations of wells used to establish the boundaries for the deposit.

Reservoir Characteristics. The average richness for both the northern and southern accumulations is about 500 barrels per acre-foot. The resource of the northern deposit is less than 20,000 barrels per acre, while the southern deposit is characterized by local areas of rich saturation containing over 30,000 barrels per acre, mainly due to its greater thickness. The average oil content and net pay resource contour is shown below.

RICHNESS AND NET PAY DISTRIBUTION—NEQUOIA ARCH DEPOSIT

Resource Contour

• Measured Area

North Deposit 10,000-20,000 B/A

South Deposit 30,000+ B/A 20,000-30,000 B/A 10,000-20,000 B/A 0-10,000 B/A

• Speculative Area North Deposit 0-10,000 B/A South Deposit 10,000-20,000 B/A 0-10,000 B/A


Range

500-520

500-530 500-1,400 520-550 500-530

Avg.

500

500 500 530 515

500*

530* SIS-

'Assumed the same as measured area contour.


25-66

60-80 44-55 19-44

1-15

28

65 48 25 8

28'

25* 8'

Resource In'Phxce. The measured resource in-place of the Nequoia Arch deposit is estimated to be 730 million barrels, underlying 63,000 surface acres. The speculative resource in-place is estimated to be 160 million barrels, underlying 39,000 surface acres.

The majority of the measured resource, 420 million barrels, is in the South Deposit. The majority of the speculative resource, 130 million barrels, is on the southern extension of the North Deposit. A summary of the resource estimate is shown in the table on page 216.

Utah

FIGURE 127

FIELD RICHNESS MAP—TAR SAND TRIANGLE, UTAH White Rim Sandstone

R15E R16E R17E

SCALE 1 0 1 2 Miles

LEGEND

^mt MEASURED AREA

• • I SPECULATIVE AREA

l l l l l l OUTCROP

| | 0-20.000 B/A

\ •' \ 20,000 - 50.000 B/A

P / . \ l 50.000 - 100,000 B/A

HBJ 100,000 B/A

LOCATION

Prepared by Lewin and Associates, inc.. 1983.

213


FIGURE 128

FIELD RICHNESS MAP—TAR SAND TRIANGLE, UTAH Moenkopi Sandstone

R15E

I P -

RISE R17E

T -30

S

k —

WAYNE CO. GARFIELD CO.

I?,1

— J -

^

*S & .

7*

/ J?

$P

31 S

N

7 1 / -30 V2 8

LEGEND

• a a SPECULATIVE AREA

• ^J 0 - 20,000 B/A

:-' •'": 20.000 B/A

LOCATION

v\ *V U * 1 A UP1FT !

(ASTM* ''"I,? \ 1

Prepafed by Lewin and Associates, Inc., 1983.

214

Utah

FIGURE 129

FIELD OUTLINE MAP—NEQUOIA ARCH, UTAH 5 y ^ - u ? * ^ JQ££~*-

LEGEND

• M MEASURED AREA • • • SPECULATIV€ AREA • WELLS WITH CORE DATA O WELLS WITHOUT CORE DATA

<^> NO TAR SHOW


215


ESTIMATE OF RESOURCE IN-PLACE— NEQUOIA ARCH

Resource Contour

• Measured Area

North Deposit 10,000-20,000 B/A

South Deposit 30,000+ B/A 20,000-30,000 B/A 10,000-20,000 B/A 0-10,000 B/A

Subtotal

Total Measured


North Deposit 0-10,000 B/A

South Deposit 10,000-20,000 B/A 0-10,000 B/A

Subtotal

Total Speculative

Barrels Per Acre

(Avg.)

14,000

32,000 24,000 14,000 4,000

4,000

14,000 4,000

Areal Extent

(Acres)

22,400

1,900 5,700 9,600

23,000

40,200

62,600

33,300

900 4,500

5,400

38,700

Resource In-Place

(MMB)

310

60 140 130 90

420

730

130

10 20

30

160

Figure 130 (see page 217) is the field richness map of the Nequoia Arch tar deposit. Because of limited data, the North Deposit is assumed to have a relatively uniform distribution of richness. The resource contours in the South Deposit follow the depositional characteristics of the deposit.

Development History. There is no known development of the Nequoia Arch deposit.

Circle Cliffs

Location. The Circle Cliffs tar sand deposit covers an area of about 20,000 acres and is located primarily in Townships 34 and 35 South and Ranges 7 and 8 East in Garfield County, about 25 miles southeast of the town of Boulder, Utah. The deposit is in a remote area surrounded by cliffs and mesas on the western margin of the Colorado Plateau.

Geology. Tar sands are found primarily in the middle member of the Moenkopi formation on the eastern and western flanks of the Circle Cliffs Uplift, a large, doubly plunging anticline (Davidson, 1967). Due to erosion, the tar-impregnated middle member is locally absent around the anticlinal axis, so the deposit has been divided into two parts—an East Flank and a West Flank. Oil-impregnated sandstone crops out along both sides of the Circle Cliffs Anticline and serves to delineate the extent of the tar deposit. While the steep East Flank has dips ranging from 25 degrees to near vertical. The West Flank dips at moderate rates of 2 to 3 degrees. Figure 131 (see page 218) shows a schematic cross section of the Circle Cliffs deposit illustrating the stratigraphic position of the deposit.

Determination of Field Outline. Geological interpretation, extensive mapping of the outcrop areas, and well data were used to determine the measured and speculative field outlines. The well data consists of four cores available from private sources.

The measured area of the Circle Cliff tar deposit is located in the West Flank and consists of a subsurface area defined by the four wells and the outcrop. The boundaries of the measured area were defined as follows:

• To the east, the field boundary extends to the outcrops.

• To the north and south, the field boundary for the measured area extends approximately one mile from cored wells.

• To the west, the deposit is assumed to extend one mile into the subsurface from the outcrop, based on a previously published study (Ritzma, 1974).

The speculative part of the deposit in the West Flank is determined from the previously referenced study by Ritzma that showed the field outline stretching the length of the outcrop and extending laterally about one mile.

The East Flank is categorized as speculative because of limited data. The area lies in the

Z16

Utah

FIGURE 130

FIELD RICHNESS MAP—NEQUOIA ARCH, UTAH

GRAND COUNTY

WAYNE COUNTY

CANYQNLANDS NATIONAL PARK

N

LEGEND

• MEASURED AREA • SPECULATIVE AREA

"I 0-10,000 B/A

I; ' ;| 10,000-20,000 B/A

20,000-30,000 B/A

30,000+ B/A

LOCATION


217

FIGURE 131

GENERALIZED CROSS SECTION—CIRCLE CLIFFS DEPOSIT, UTAH

After Bitzma. 1974

Utah

Capitol Reef National Park and so no subsurface data has been gathered. The field boundaries for the East Flank are based on the location of tar-impregnated outcrops and extension of the deposit one mile from the outcrop into the subsurface. The deposit is characterized by moderate to rich oil saturation, believed to be equal to or higher than that of the West Flank (Davidson, 1967).

The field outline of the Circle Cliffs deposit and the outcrops are shown on Figure 132 (see page 220) along with the location of the wells for which data were available.

Reservoir Properties. Distinguishing characteristics of the Circle Cliffs tar deposit are its low porosity (15%) and shallow depth of burial (50 to 400 feet). Key reservoir properties are summarized below.



- Range - Average


- Average

-CIRCLE CLIFFS

50-400

13-17 20 80

The richness and net pay of the measured area of tar accumulation are determined from core data. The outcrop area is assumed to have a tar-impregnated thickness equal to one-half that measured in subsurface cores. The speculative portion of the field is assumed to have reservoir characteristics similar to those of the measured area. The average oil content and net pay by resource contour is shown below.

DISTRIBUTION OF RICHNESS AND NET PAY—CIRCLE CLIFFS

Resource Contour


Range Avg.


• Measured Area West Flank 100,000+ B/A 1,050-1,400 1,225 83-105 0-100,000 B/A 1,250*

(Continued at top ol next column)

95 45

DISTRIBUTION OF RICHNESS AND NET PAY—CIRCLE CLIFFS

(Continued Irom previous column)

Resource Contour

Barrels Per Acre-Foot Net Pay, Feet


• Speculative Area*

West Flank 100,000+ B/A 0-100,000 B/A

East Flank 100,000+ B/A 0-100,000 B/A

1,225 1,250

1,225 1,250*

95 45

95 45

'Contour defined by one welt. "Assumed to be halt the subsurface net pay. "Assumed the same as the measured area contours.

Bitumen Properties. The gravity of the bitumen ranges from (-7)° to 2° API. It has been suggested that the oil was originally heavy oil that has subsequently been degraded by deep erosion, invasion of fresh water, and bacterial action.

Resource In-Place. The measured resource in-place at Circle Cliffs is estimated to be 560 million barrels underlying 6,400 surface acres. The speculative resource in-place is estimated to be 1,140 million barrels underlying 14,000 surface acres. The majority of the resource, both the measured and speculative, is assumed to be in the subsurface, in the, 100,000+ B/A contour. A summary of the resource estimate is shown below.

ESTIMATE OF RESOURCE IN-PLACE—

Resource Contour

• Measured West Flank 100,000+ B/A

CIRCLE CLIFFS

0-100,000 B/A*

Total Measured • Speculative

West Flank 100,000+ B/A 0-100,000 B/A* Subtotal

Barrels Per Acre

(Avg.)

100,000 50,000

100,000 56,000


4,500 1,900

6,400

3,800 3,800 7,600

(Continued on page 222)


450 110 560

380 210 590

219


FIGURE 132

FIELD OUTLINE MAP—CIRCLE CLIFFS, UTAH

R6E ,R7E R8E R9E

' <

GARFIELD

tft >

* . \ u

CO.

^

J N

T 34 S

T 35 S

T 36 S

1 0 1 2 Mi les \ , hi

SCALE

LEGEND

wm—m MEASURED AREA

man/ OUTCROP

% WELL WITH CORE DATA

LOCATION

n M. V v

•*** \ j t \ 4

\w


220

Utah

ESTIMATE OF RESOURCE IN-PLACE— CIRCLE CLIFFS

(Continued from page 219)

Resource Barrels Areal Resource Contour Per Acre Extent In-Place

(Avg.) (Acres) (MMB)

East Flank 100,000+ B/A 100,000 4,500 450 0-100,000 B/A* 50,000 1,900 100

Subtotal 6,400 550

Total Speculat ive 14,000 1,140

"The 0-100,000 B/A contour describes the outcrop area.

Figure 133 (see page 222) is the field richness map of the Circle Cliffs tar deposit showing the two main areas of the deposit.

Development History. There is no known development of the Circle Cliffs tar deposit.

San Rafael Swell

Location. The San Rafael Swell tar deposit covers an area of over 51,000 acres and is located in central Utah, Emery County, in Townships 23 and 24 South and Ranges 9, 10 and 11 East.

Geology. Tar sands of the San Rafael deposit are found primarily in the middle member (Torrey member) of the Moenkopi formation of Trias-sic Age.

The deposit is located on the San Rafael Uplift where tar-impregnated strata crop out along Red Canyon and Temple Wash (Township 24 East, Ranges 9 and 11 South, respectively). Structurally, the area is a prominent domal upwarp in sedimentary rocks.

Figure 134 (see page 223) is a cross section of the San Rafael deposit. It is a diagrammatic representation of the tar zones and illustrates their stratigraphic position in the deltaic sediments. This cross section of the San Rafael deposit displays the horizontal and even bedding typical of the formation (Blakey, 1970). The oil-impregnated middle member, at this locality, originated during a deltaic/fluvial depositional sequence and is overlain and underlain by members of different lithologies confining the oil to deltaic sediments.

Determination of Field Outline. Geological interpretation and well data were used to determine the measured and speculative field outlines. The well data consisted of five cores and three drillers logs available from proprietary sources.

The measured boundaries were determined from well data using the general rules of extrapolating one section outward and interconnecting measured areas where the geology appears favorable.

The speculative area is found to the south and east of the measured area where shows of tar have been reported in drillers logs. The outline of the speculative area was determined using the general extrapolation rule of one section from the nearest well or from the measured area.

The field outline of the San Rafael Swell tar deposit and the location of wells used in determining the field outline are shown on Figure 135 (see page 224).

Reservoir Properties. The central area of the measured field is 20 feet thick and has 1,200 barrels per acre-foot. The remainder of the measured deposit appears to be characterized by relatively uniform richness estimated at 1,500 barrels per acre-foot, with an average net pay of 7 feet, ranging from 5 to 10 feet. Additional reservoir characteristics are not known.

Core data do not indicate appreciable change in richness. Therefore the barrels per acre-foot assumed for the speculative area are the same as those for the measured area. The average oil content and net pay by resource contour is shown below.

DISTRIBUTION OF RICHNESS AND NET PAY-SAN RAFAEL SWELL

Resource Contour

• Measured Area 20,000+ B/A 0-20,000 B/A


'Assumed the same as the

Barrels Per Acre-Foot Net Pay, Feet


755-1,665 1,200 12-33 20 370-2,600 1,500 5-10 7

1,500* 7* measured area contour-


FIGURE 133

FIELD RICHNESS MAP—CIRCLE CLIFFS, UTAH

R6E

11

\R7E

» t*\Bg8&

12

Wat/*/

*2»HK%I

"•?•

GARFIELD

^ R8E

^S^ftimm*

WM 101-

i " " " " ^^^fesfHUR

W I U I J

CO.

rr^,

R9E

1 1 N

1 0 1 2 M i l e s I I I I

SCALE

. LEGEND

MEASURED AREA

SPECULATIVE AREA

OUTCROP ( 5 0 , 0 0 0 B /A)

100,000 B/A

LOCATION

Prepared byLewin and Associates, Inc.. 1983.

T 34 S

T 35 S

T 36 S

222

FIGURE 134

CROSS SECTION—SAN RAFAEL SWELL DEPOSIT, UTAH

I GRASSY TRAIL (40 miles)

SAN RAFAEL CENTRAL SAN RAFAEL RIVER (20 miles) SWELL (20 miles) -MUDDY RIVER

• ^ ^ H " - ^ m m _ • — - — — — _ _ _ _ _ _ _ J »

= ^ ^ = _ = .£= =_-=_-~--^. "2^3: •= MOODY CANYON MEMBER j r ~ = ^ - r l - ^ ~/=? < ^ - = T ^ - _ ^ = _ V r > ^

I I I l -SINBAD LIMESTONEH-H- ' ' ' ' ' ' ' ' ' '

After Blakey. 1977.

GENERAL LOCATION OF CROSS SECTION

Salt

Varnal

tvProvo

^ • P r l c a

N Ralaal UpHft

»ay Trail

luddy Mo*"! Ivar

A"

c


FIGURE 135

FIELD OUTLINE MAP—SAN RAFAEL SWELL, UTAH

R9E R10E R11E

4

3

(

• 7

-^

10 31

EME

h

? • —

• M M U M

L _

RY <

| —

lata

) 0 .

I

1

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I 36

1 o

1 — 1

, '

1"

26 • M l 36

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S

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3 1

» • r

•

-•

•

j^ AT

u h

so I I

/ s 12 I T

-t / .

1

0

0 I

Scale

LEGEND

i m » MEASURED AREA

• • • « • SPECULATIVE AREA

# WELL WITH CORE DATA

O WELL WITHOUT CORE DAT/»

- 0 - NO TAR SHOW

i

1

V

y \

! F " "

1 ;

—

. 12

^m^m

V

o

6

7

• rl I ssjUM •

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si

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LOCATION

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224

Utah

Resource In-Place. The measured San Rafael Swell resource in-place is estimated to be 300 million barrels underlying 26,000 surface acres. The speculative resource in-place is estimated to be 250 million barrels underlying 26,000 acres. The majority of the resource is contained in the 0-20,000 B/A contour, as shown below.

ESTIMATE OF RESOURCE IN-PLACE— SAN RAFAEL SWELL

Resource Contour

• Measured Area

20,000+ B/A 0-20,000 B/A Subtotal


0-20,000 B/A

Barrels Per Acre

(Avg.)

20,000 10,000

10,000


3,200 22,400

25,600

25,600


70 230

300

250

Figure 136 (seepage 226) is the field richness map of the San Rafael Swell deposit. It shows

that the richest area is found in the east-central part of the deposit.

Development History. There is no known development of the San Rafael deposit.

MINOR DEPOSITS

There are a total of thirteen bitumen deposits in Utah that each contain between 10 and 100 million barrels of resource in-place and thus are classified as minor deposits. Eight of these deposits are found in the Uinta Basin and five in southeastern Utah. Figure 137 (seepage 227) shows the location of the thirteen minor tar deposits.

The resource in-place and general stratigraphic position is summarized in the following table. The resource estimates were prepared by the Utah Geological Survey.

In addition, numerous tar seeps are scattered throughout eastern and central Utah (from UGMS Map 47, 2 sheets, 1974).

MINOR TAR SAND DEPOSITS OF UTAH

Deposit*

Uinta Basin Argyle Canyon Raven Ridge Rimrock Cottonwood-Jacks Canyon Little Water Hills Minnie Maude Creek Pariette Willow Creek

Southeastern Utah Black Dragon Chute Canyon Cottonwood Draw Red Canyon Wickiup

Total

"Source: "Oil Impregnated Rock Depos

County

Duchesne Uintah Carbon, Duchesne Carbon, Duchesne Uintah Carbon, Duchesne Duchesne, Uintah Duchesne, Utah, Wasatch

Emery Emery Emery Emery Emery

ts ot Utah", UGMS, Map 47, two sheets, 1974.

Formation, Geologic Age

Green River, Eocene Green River, Eocene Wasatch and Green River, Green River, Eocene Duchesne River, Eocene Green River, Eocene Uinta, Eocene Green River, Eocene

Moenkopi, Triassic Moenkopi, Triassic Moenkopi, Triassic Moenkopi, Triassic Moenkopi, Triassic

Eocene


50-75 75-100 25-30 20-25 10-12 10-15 12-15 10-15

100-125 50-60 75-80 60-80 60-75

557-707

225


FIGURE 136

FIELD RICHNESS MAP—SAN RAFAEL SWELL, UTAH

R9E R10E R11E

so >1

EMERY

i i Scale

2 Mllut,

—

M

LEGEND

MEASURED AREA

SPECULATIVE AREA

0 - 20,000 B/A

20,000* B/A

LOCATION

[V> u*n* ^ m

****" N J K ' N (

my-


226

Utah

FIGURE 137

MINOR TAR SAND DEPOSITS OF UTAH

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! W Y O M I N G

! W\S • S A L C ' T L Y A K E ^ UINTA UPLIFT

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KEY UINTA BASIN

1 - ARGYLE CANYON 2 - RAVEN RIDGE 3 - RIMROCK 4 - COTTONWOOD-JACKS CANYON 5 - LITTLEWATER HILLS 6 - MINNIE MAUDE CREEK 7 - PARIETTE 8 - WILLOW CREEK

SOUTHEASTERN UTAH 0 - BLACK DRAGON

10 - CHUTE CANYON 11 - COTTONWOOD DRAW 12 - RED CANYON 13 - WICKIUP

A R I Z

After UGMS Map 47. Sheet 1. 1974.

V / ^ \

I #7 f \ UINTA BASIN /*-*

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227


The two deposits containing the largest amounts of tar resource, Raven Ridge and Black Dragon, are discussed below.

Raven Ridge. The Raven Ridge tar deposit is located on the northern flank of the Uinta Basin, extending partially into Colorado in Townships 6 and 7 South and Ranges 24 and 25 East. Tar-impregnated sandstone is found scattered along the northwest trending hogbacks of the Eocene and Green River formations, mostly in the Parachute Creek member (Sanborn and Goodwin, 1965). The strata dip southwest into the Uinta Basin.

Based on one core analysis, the deposit is characterized by the following properties.

Porosity (%) 27 Oil Saturation (%) 30 Net Pay (feet) 10 Barrels Per Acre-Foot 625 .

Assuming the deposit covers 16,000 acres (U.G.M.S.), the resource in-place is estimated at approximately 100 million barrels.

Black Dragon. The Black Dragon tar deposit is located on the San Rafael Uplift in Townships 21 and 22 South and Range 13 East. The deposit is located wholly within the Moenkopi formation, primarily in sandstone, although the associated siltstones and mudstones are also tar-impregnated. The known extent of the deposit is about 3 miles east-west and 2 miles north-south (Blakey, 1970).

The total maximum thickness of the Blacl Dragon deposit, based on outcrop observatior is reported to be over 100 feet (Blakey, 1970) The subsurface extent of this deposit to th< north and east is unknown. The resource in-place as estimated by U.G.M.S. is 100 to 125millior barrels.

228

Utah

REFERENCES

Baars, D.L., and Seager W.R. , 1970, Stratigraphic control of petroleum in Whi te Rim Sandstone (Permian) in and near Canyonlands National Park, Utah: American Association of Petroleum Geologists Bulletin, May, 1970.

Ball, J .O., and Bard, C.F., 1944, Hydrocarbons of the Uinta Basin of Utahand Colorado: Quarterly, Colorado School of Mines, Jan., 1944.

Blakey ,R.C, 1970, Preliminary report of oil-impregnated sediments of the San Rafael Swell, 1970.

Blakey, R.C., 1977, Petroliferous lithosomes in the Moenkopi Formation southern Utah, in Utah Geology: Utah Geological and Mineral Survey, v. 4, no. 2.

Bowman, J.L., 1969, Oil impregnated sandstone between Dirty Devil and Colorado and Green Rivers, Garfield and Wayne Counties, Utah: Paper Presented to Rocky Mountain Section American Association of Petroleum Geologists, Feb. 26, 1969.

Byrd, W.D. , 1970, P.R. Spring oil-impregnated sandstone deposit, Uin tah and Grand Counties, Utah: Utah Geological and Mineral Survey Special Studies 3 1 .

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

Campbell, J.A., and Ritzma, H.R., 1976, Structural geology and petroleum potential of the south flank of the Uinta Mounta in Uplift: American Association of Petroleum Geologists Bulletin, v. 60 .

Cashion, W.B. , 1967, Geology and fuel resources of the Green River formation southeastern Uinta Basin, Utah and Colorado: Geological Survey Professional Paper 548.

Clark, F.R., 1926, Economic geology of the Castelgate, Well ington and Sunnyside quadrangles, Carbon County, Utah; U.S . Geological Survey Bulletin 793 .

Covington, R.E., 1957, The bituminous sandstonesof the Asphalt Ridge area, Northeastern Utah: Intermountain Association of Petroleum Geologists, 8th Annual field conference.

Covington, R.E., 1964, Bituminous sands with viscous crude oils, in First Intermountain Symposium on Fossil Hydrocarbons, Proceedings: Salt Lake City, Utah, Brigham Young University, Salt Lake Center for Continuing Education.

Covington, R.E., 1964, Bituminous sandstone in the Uinta Basin: In te rmounta in Association of Petroleum Geologists, 13th Annual Field Conference.

Covington, R.E., 1964, Thermal recovery may bring industry's quiet revolution: The Oil and Gas Journal .

Covington, R.E., 1965, Some possible applications of thermal recovery in Utah: Journal of Petroleum Technology.

Current, A.M., 1953, A review of the geology and activities in the Uinta Basin, in Quarterly, Colorado School of Mines.

Dahm, J.N., 1980, Tar sand reserves P.R. Spring deposit, Uintah and Grand Counties, Utah: Utah Geological and Mineral Survey, Open File Report 27.

Davidson, E.S., 1967, Geology of the Circle Cliffs area, Garfield and Kane Counties, Utah: Bulletin, U.S . Geological Survey.

Energy Consulting Associates, Inc., 1975, An evaluation of the P.R. Spring oil impregnated sandstone deposits, Uintah and Grand Counties, Utah.

Eyring Research Institute, 1976, Evaluation of the Utah oil sand resource: Draft Final Report, Bureau of Mines Contract no. JO 122035.

Gilluly, James, 1928, Geology and oil and gas prospects of part of the San Rafael Swell, Utah: Bulletin, U.S. Geological Survey.

Glassett, J .M. and Joel, A., 1928, The product ion of oil from intermountain west tar sands deposits: Bulletin, U.S . Geological Survey.

Gywnn, J .W., 1971, Instrumental analysis of tars and their correlation in oil-impregnated sandstone beds, Uintah and Grand Counties, Utah: Utah Geological and Mineral Survey Special Studies 37 .

Hunt , J.M., Steward, Francis, and Dickey, P.A., 1954, Origin of hydrocarbons in Uinta Basin: American Association of Petroleum Geologists Bulletin, Aug., 1954.

Johnson, L.A., Fahy, L.J., and Romanowski , L.J., 1978, An echoing in situ combustion oil recovery project in a Utah tar sand: SPE Paper 7 5 1 1 .

Johnson, L.A., Fahy, L.J., Romanowski, L.J., and Thomas, K.P., 1981, An evaluation of steamflood experiment in a Utah tar sand deposit: SPE Paper 10228.

Johnson, L.A., Marchant, L , C , and Cupps, C.Q, , 1975, Properties of Utah tar sand—Asphalt Wash area, P.R. Spring Deposit: U.S . Bureau of Mines Report of Investigation 8030 .

229


REFERENCES

Johnson, L.A., Marchant, L.C., and Cupps, C.Q., 1975 Properties of Utah tar sand—North Seep Ridge area, P.R. Spring Deposit: U.S. Energy Research and Development Administration, Laramie Energy Research Center Report of Investigation, ERDA LERC/RI-75/6.

Johnson, L.A., Marchant, L.C., and Cupps, C.Q., 1975, Properties of Utah tar sands—South Seep Ridge area, P.R. Spring Deposit: U.S. Bureau of Mines Report of Investigation 8003.

Johnson, L.A., Marchant L.C., and Cupps, C.Q., 1976, Properties of Utah tar sands—Flat Rock Mesa area Hill Creek Deposit: U.S. Energy Research and Development Administration, Laramie Energy Research Center Report of Investigation, ERDA LECR/RI-76/5.

Kayser, R.B., 1968, Bituminous sandstone deposits Asphalt Ridge: Utah Geological and Mineral Survey special Studies 19.

Kelly, V.C., 1978, Tectonics of the region of the Paradox Basin, in Guidebook to the geology of the Paradox Basin: Intermountain Association of Petroleum Geologists, 98th Annual Field Conference.

Marchant, L.C., Cupps, C.Q., andStosur, J.J., 1979, Current activity and production from U.S. tar sands in First international conference on the future of heavy oil and tar sand: United Nations Institute for Training and Research, 1979.

Murany, E.E., 1982, Wasatch Formation of the Uinta Basin, guidebook to the geology and mineral resources of the Uinta Basin: Intermountain Association of Petroleum Geologists, 13th Annual field Conference.

Peterson, P.R., 1975, Lithologic logs and correlations of coreholes, P.R. Spring and Hill Creek oil-impregnated sandstone deposits, Uintah County, Utah: Utah Geological and Mineral Survey Report of Investigation, 100.

Peterson, P.R., and Ritzma, H.R., 1974, Informational core drilling in Utah's oil-impregnated sandstone deposits, southeast Uinta Basin, Uintah County, Utah: Utah Geological and Mineral Survey Report of Investigation 88.

Picard, M.D., 1971, Petrographic criteria for recognition of lacustrine and fluvial sandstone, P.R. Spring oil-impregnated sandstone area, Southwest Uinta Basin, Utah: Utah Geological and Mineral Survey, Special Studies 36.

(Continued)

Picard, M.D., and High L.R., Jr., 1970, Sedimentology of oil-impregnated lacustrine and fluvial sandstone, P.R. Spring Area, S.E. Uinta Basin, Utah: Utah Geological and Mineral Survey Special Studies 33.

Pruitt, R.G., Jr., 1961, The mineral resources of Uintah County: Utah Geological and Mineral Survey Bulletin 71.

Ritzma, H.R., 1980, Oil-impregnated sandstone deposits, Circle Cliffs Uplift, Utah: Utah Geological Association.

Ritzma, H.R., 1973, Exploration and development of oil shale and oil-impregnated rocks: Quarterly, Colorado School of Mines.

Sanborn, A.F., and Goodwin, J.C., 1965, Green River formation at Raven Ridge, Uintah County, Utah: Trie Mountain Geologist.

Schic, R.B., 1966, Drillers; probing Utah's French Seep area: Oil and Gas Journal.

Shea, G.S., and Higgins, R.V., Separation and utilization studies of bitumens from bituminous sandstones of the Vernal and Sunnyside Utah deposit: Bureau of Mines Report of Investigation 4871.

Speiker, E.M., 1930, Bituminous sandstone near Vernal, Utah: Bulletin, U.S. Geological Survey.

Steele-Mallory, B. A., 1982, The depositional environment and petrology of the White Rim sandstone member of the Permiam Cutler Formation, Canyon Lands National Park, Utah: U.S. Geological Survey Open File Report F2-204.

Thurber, J.L., and Welbourn, M.E., 1977, How Shell attempted to unlock Utah tar sands: Petroleum Engineer.

United States Geological Survey, 1948, Oil and Gas Investigations: Preliminary Map 86.

Untermann, G.E., and B.R., 1964, Geology of Uintah County: Bulletin, Utah Geological and Mineral Survey.

Utah Geological Association, 1974, Energy resources of the Uinta Basin, Utah: Annual Field Conference.

Utah Geological and Mineral Survey, 1974, Oil impregnated north deposit of Utah: Map 47, 2 sheets.

Chapter 10

Wyoming

S U M M A R Y

Wyoming is estimated to have 120 million barrels of measured and 70 million barrels of speculative bitumen resource in-place. This resource occurs in one major and one minor deposit, as shown below.

WYOMING BITUMEN RESOURCE IN-PLACE

Measured (MMB)

Speculative (MMB)

Major Deposit Burnt Hollow 120

Minor Deposit Rattlesnake Hills — Total 120

25

45 70

The major deposit is the 4,600-acre Burnt Hollow deposit of Permian Age in northwest Wyoming. The deposit has two areas; a northern area at the Burnt Hollow anticline where tar occurs at about 700 feet, and a southern area at Devil's Canyon and Alva Dome where the tar is found at 1,000 feet. Resource calculations indicate that the Burnt Hollow deposit contains 120 million barrels of measured and 25 million barrels of speculative resource in-place.

The minor deposit in Wyoming is at Rattlesnake Hills. It is estimated to have 45 million barrels of speculative resource in-place underlying 1,500 acres.

Beyond these two tar sand deposits, there are over seventy reported surface occurrences of petroleum-impregnated rocks and oil seeps. They are very small and most of them occur where producing formations crop out or appear to be connected through faults to underlying conventional oil fields.

The development of the Wyoming tar resource has consisted of three thermal pilots; two at Burnt Hollow and one at Rattlesnake Hills.

MAJOR DEPOSITS

The geographical location of the Burnt Hollow deposit is shown on Figure 138 (seepage 232), a map showing structural features in Wyoming.

Burnt Hol low

Location. The Burnt Hollow tar sand deposit covers 4,600 surface acres and is located in Crook County, northeastern Wyoming, in Townships 64 to 65 North, Ranges 63 to 64 West . It is approximately 3 miles east of the town of Hulett in the Black Hills uplift.

Geology.* The tar at Burnt Hollow is trapped in sandstone in the Upper Minnelusa formation of Permian Age. This formation consists of a complex rock sequence of marine, near shore, and eolian sediments that range in age from Early Pennsylvanian through Early Permian in the northern Black Hills. The rocks are principally sandstone with variable amounts of anhydrite, limestone and dolomite. Figure 139 (see page 233) is a stratigraphic column of the Burnt Hollow area of Wyoming.

The Minnelusa formation crops out on the periphery of the Black Hills Uplift, and the entire section is well exposed at several locations. There is a regional thinning from south to north as well as thinning from west to east across Crook County, Wyoming. Gross formation thicknesses range from 1,000 feet in the southwestern portion of the county to 500 feet near the northeast corner.

*Tfiis ReoloRic discussion is based on industry sources and on Tenner, "Heavy oil in Minnelusa in northern Black Hills," (1968).

231

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