Read Uintah and Ouray Indian Reservation text version

UINTAH AND OURAY RESERVATION Introduction The Uintah and Ouray Indian Reservation is located in the Uinta Basin, in northeast Utah (FIGURES UO-1 and UO-2). The terrain is High Mountain desert in the central part of the basin, which is surrounded by mountain ranges on the edge of the basin. Elevation varies from approximately 5,600 feet to over 11,000 feet above sea level. The area's main transportation conduit is U.S. Highway 40, which leads east to Salt Lake City, Utah, and west to Denver, Colorado. The ba sin covers approximately 11,500 square miles, and Ute Indian Tribe jurisdiction comprises just over 4 million acres of this area, reaching from the Utah-Colorado border west to the Wasatch Mountain range. Mineral Ownership The Uintah and Ouray Indian Reservation is a checkerboard owner ship reservation containing Ute Indian Tribe, Ute Indian Allotted, Ute Indian Tribe and Ute Distribution Corporation Jointly Managed Indian Trust minerals, along with fee (privately owned) and federal minerals. Indian properties cover approximately 1.2 million surfaceowned acres, and 400,000 mineral-owned acres within the 4 millionacre jurisdictional boundary. Ute Indian Allottees, the Ute Indian Tribe, and the Ute Distribution Corporation own both surface and mineral properties in joint management.

Currently, the Ute Tribe, Ute Allottees, and the Ute Distribution Corporation in joint management hold 102,000 acres under lease, and more than 490 wells in production. The Utah Oil, Gas, and Mining Board conduct conservation spacing in cooperation with the Ute Tribe. Spacing rules for the Altamont-Bluebell field are set at a multi-well level allowing two wells per section, while undesignated field spacing is 40 acres for oil and 640 acres for gas. Some variations or exceptions exist by special ruling and order (Anderson, 1995).

TY COUN

DAGGET UINTAH

CO UN TY TY

CO

UN

TY

NE DUCHES

C

N OU

WA S

AT C

H

COU

NTY

SU

MM

IT

STARR FLATS COTTONWOOD WASH BLUEBELL Vernal

AM ALT

ALTAMONT

ON

TT

R

END

ROOSEVELT WEST GUSHER

EAST GUSHER HORSE SHOE BEND BRENNER BOTTOM

Fort Duchesne CEDAR RIM CEDAR STARVATION FLAT MESA BLUE BENCH RANDLETT Duchesne DUCHESNE INDIAN RIDGE

AS W

GYPSUM HILLS

WONSITS VALLEY RED WASH

REFUGE WEST PLEASANT VALLEY Ouray SOUTH OURAY UTE TRAIL

RI

VE

NUTTER CANYON

CASTLE PEAK

PARIETTE BENCH MONUMENT BUTTE

CHAPITA WELLS

UTAH

C AT H

R

CHOKECHERRY CANYON COUNTY UINTAH

BITTER CREEK

COUNTY CARBON

DUCHESNE COUNTY

COUNTY

PETERS POINT

112O 41O

RANGE

111O

110O

WYOMING

109O

108O

107O

GRE EN

A UINT

MOUNTAINS UTAH DOUGLAS COLORADO CREEK ARCH

Price

FLAT ROCK

CARBON MERY

COUNTY COUNTY

UINTAH GRAND MOON RIDGE

COUNTY COUNTY

WA S

PICEANCE CREEK BASIN

40O

AT C

H

UINTA

WAS A PLAT TCH EAU

BASIN

SEGUNDO CANYON

LEGEND

N Oil Field Gas Field Reservation Boundary

0 5 10 20 30

BOOK

39O

UN CO UPMP LI AH FT G CLIFFS RE

SA N SWRA EL FAE L L

0 0

50Miles 80Kilometers

Scale, miles

Figure UO-2. Index map showing the Uintah and Ouray Indian Reservation in yellow (modified after Anonymous, 1995). Figure UO-1. Location of Uinta Basin and surrounding structural and physiographic features.

Yellow area shows approximate boundary of Uintah and Ouray Indian Reservation (modified after

Cashion, 1992).

UINTAH AND OURAY INDIAN RESERVATION

UTAH

Overview

1

Uintah and Ouray Reservation Petroleum Exploration and Development

The Uinta Basin is a rich source of many energy-producing minerals. The greatest portion of the energy resources is hydrocarbons in the form of coal, oil, gas, oil shale, and bituminous sandstone and lime stone. Resources contained within the Uintah and Ouray Reservation include conventional and unconventional hydrocarbon deposits of oil and gas, oil shale, and tar sands in major quantity; coal, uranium, sil ver, copper, gold, gypsum, and phosphate are also present in minor to mid-economic quantities. Cretaceous and older rocks contain many productive oil and gas zones. However, the major portion of the energy production from the Uinta Basin is from Tertiary rocks, and the distribution of the hydro carbons and minerals is directly related to their depositional environ ment. Uinta Basin production of oil and gas began in the late 1940's, with major development commencing in the late 1960's and expand ing in the late 1970's and early 1980's. Over 300 million barrels of oil (MMBO) have been produced from the Greater Altamont-Bluebell field alone. Conventional oil and gas deposits have been exten sively explored and developed. The Green River and Wasatch For mations contain the bulk of the producing zones, with depth to these zones ranging from 6,000 to 18,000 feet. This has resulted in the de velopment of the Greater Altamont-Bluebell oil field, and numerous undesignated smaller fields (FIGURES UO-2, UO-6). The oil produced is high in paraffin content (pour point = 120 de grees F), making it an excellent gasoline refining feedstock. It is ex tremely rich with associated natural gas, with values falling between 900 and 1700 British thermal units (Btu). Only one natural gas field has been developed, and it is located east and south of the Green and White Rivers. It is bordered by the Natural Buttes Gas Field Unit, which covers 76,000 acres. Total Ute Indian oil production approximates 1,250 barrels per day, a level that has held for the last 10 years. New well development and workover activity has been sufficient to offset the normal decline of the many oil and gas fields within the basin and the reservation area (Anderson, 1995).

north, and northeast into the basin. The northwest-southeast trending salt folds of the northern Paradox Basin plunge beneath the Book Cliffs in the southernmost part of the basin, and the two downwarps merge imperceptibly in this area. On the east, the Uinta Basin is sep arated from the Piceance Basin of northwest Colorado by the Doug las Creek Arch, which parallels the Utah-Colorado border (FIGURE UO-3). The basin is quite asymmetric. Beds on the north flank dip 10 to 35 degrees south, whereas beds on the south flank dip only 4 to 6 de grees north (Chidsey, 1993). The north flank is highly complex, with

major faulting, steep to overturned beds, and multiple unconformi ties that allow youngest Eocene rocks to lie unconformably on top of Precambrian rocks. The basin axis is close to the mountain flank and moves northward with depth. The Uinta Basin formed in Late Cretaceous and Paleocene time when, in response to rapid uplift and formation of the Uinta Moun tains, the dominant north-south tectonic and sedimentation patterns of Cretaceous time shifted to west-east. The Uintas impose a domi nant west-east trend through most of the basin; however, structures in the southeast portion have a strong northwest grain, reflecting the older buried Uncompahgre and Paradox trends.

o 110

Figure UO-3. Location and structural element map of the Uinta and Piceance Basin Provinces (modified after Gautier et al., 1995).

UT

UINTA

MTNS.

UPLIFT

WY CO

108

o

106o

SANDWASH BASIN

Craig

L IA T AX LIF UP

Vernal

40o

TA UIN IN BAS

PROVINCE BOUNDARY

E RIV E T HIT PLIF W U R

Rangely

DOU CREE GLAS K ARC H

BOOK

Price

PICEANCE CREEK BASIN

CL IF FS

SA SW N R EL AF L AE

O BO

K

L

Glenwood Springs

FS

EAGLE BASIN

TC WA SA

CL IF

Grand Junction

E R G H PA M O C N U

HR

Green River

50 MILES

AN GE

0

25 25

Geology of the Uinta Basin

0

The Uinta Basin is a major sedimentary basin in the western-central Rocky Mountain province. It is bounded by the Uinta Mountain Up lift on the north and by the Wasatch Mountain Uplift and the eastern faulted margin of the Wasatch Plateau on the west. On the southwest and south, the San Rafael Swell and the Uncompahgre Uplift border the basin (FIGURES UO-2 and UO-3). The southern basin edge is gen erally considered to be the Book and Roan Cliffs, escarpments of Up per Cretaceous and Lower Tertiary formations which dip northwest,

UT CO

50 KILOMETERS

GUNNISON UPLIFT

T IF PL U

EXPLANATION

38o

Upper Cretaceous rocks present Upper Cretaceous rocks absent Thrust fault

UPPER CRETACEOUS ABSENT BY EROSION

UINTAH AND OURAY INDIAN RESERVATION

UTAH

Geology

2

The Uinta Basin is filled with 30,000 to 32,000 feet of sediment in its northern and deepest portion (Figs. UO-4 and UO-5). Although the majority of the rocks exposed on the reservation are of Tertiary age, some pre-Tertiary age rocks are exposed on the northern and northwestern boundaries. Percentages of basin strata are subdivided as follows:

Tertiary (Eocene - Paleocene) Upper Cretaceous Triassic - Lower Cretaceous Paleozoic 55% 25% 10% 10%

UTAH

UINTA BASIN

COLORADO

PICEANCE BASIN AXIAL UPLIFT Browns Park Fm.

DOUGLAS CREEK ARCH

TERTIARY

Duchesne River Fm.

S

Uinta Fm. Green River Formation

tch Wasa

S

Colton Fm. Flagstaff Limestone North Horn Formation Price River Fm.

Fm.

Wasatch Fort Union Formations Lance Formation Lewis Shale S

S

k ree t C te rran era Cu nglom Co

S

Mesaverde Gp. Sego Sandstone

S

CHARACTER OF BEDS

EAST Alluvium, gravel surfaces, talus deposits, and other windblown deposits 0-70 0-500 1370 700-1650 1800-2400 0-5000 0-4800 0-400 0-3000 0-500 5000-6000 30-50 780-800 230 2300 80-500 1000-1500 300-800 0-200 1000-2200 0-70 0-500 1500 1800-5400 0-5000 Conglomerate, boulders 1 to 6 feet in diameter, sand and gravel Varicolored shale, sandstone, and conglomerate Shale with sandstone interbeds Green to white shale, sandstone, oil shale in middle of formation Varicolored sandstone, shale, limestone Paleocene deposits absent due to unconformity Conglomerate, sandstone, and varicolored shale Varicolored shale with sandstone interbeds Upper section - Brackish-water sandstone, sandy shale, carbonaceous shale, and coal Lower section - Marine sandstone WEST

CRETACEOUS

GEOLOGIC TIME

Quaternary

GROUP AND FORMATION

Alluvium

THICKNESS (ft.)

Castlegate Sandstone Blackhawk Fm.

S

Mancos "B"

Ma

Emery Sandstone Ferron Sandstone Tununk Shale S Mowry Shale S Dakota Sandstone Cedar Mountain Formation Frontier Formation

o nc

sS

ha

le

Pleistocene Glacial Deposits Glacial drift, alluvium, and terrace deposits Miocene

Ter tiary

S S Significant oil production Significant gas production

Bishop Conglomerate Duchesne River Formation Uinta Formation Green River Formation Wasatch Formation

Oligocene Eocene

JURASSIC

Morrison Formation Stump Formation Preuss Formation Twin Creek­Carmel Formation Navajo Sandstone

S S

Curtis Formation Entrada Sandstone

S

S Source rocks

Cretaceous Upper Cretaceous

Currant Creek Formation North Horn Formation Mesaverde Group

TRIASSIC

300-1000 800-3500 30-50

Ankareh Fm. Thaynes Limestone Woodside Shale S Park City Fm. (Phosphoria) Upper Weber Sandstone Lower Weber Sandstone Morgan Formation Round Valley Limestone Manning Canyon Shale S Humbug Fm. -- Doughnut Sh. S ? Deseret Limestone Madison Formation

eak Fm.

Chinle Formation Shinarump Conglomerate Moenkopi Formation

Gartra Member

Black marine shale, thick massive sandstone, Mancos Shale (including Frontier Sandstone Member) shaly sandstone Dakota Sandstone Jurassic Triassic Permian Pennsylvanian Mississippian Upper Morrison Formation Chinle Formation Moenkopi Formation Park City Formation Weber Sandstone Morgan Formation Cross-bedded tan sandstone Varicolored shale with sandstone interbeds Shale with minor sandstone and conglomerate Shale, sandstone, siltstone, and limestone Argillaceous, sandy limestone Massive sandstone Varicolored shale and limestone with sandstone

PERM.

780-800 300-380 800 80-500 1000-1500 300-800

Cutler Formation Upper Weber Sandstone

State Bridge Fm.

PENN.

Lower Weber Sandstone Morgan Formation Minturn Formation Belden Shale

M Fo aro rm on ati on

S

MISS.

Manning Canyon Shale Humbug Formation Great Blue Formation Interbedded shale, limestone, and sandstone Molas Formation Doughnut Formation Redwall Formation Leadville Formation Deseret Formation Madison Formation Massive dolomite and limestone Sandstone, shale, carbonate No identifiable Silurian or Ordovician deposits

0-900

0-900

Madison Formation

Lower

Leadville Limestone Chaffee Fm.

0-1100 1000

0-1100 2000

Devonian Cambrian Precambrian Tintic Quartzite or Lodore Formation Uinta Mountain Group Uncompahgre Suite

p C CAMB.

Sandstone, shale, and carbonate Quartzite with shale and conglomerate Schist, gneiss, and granite

0-2000

0-2000

12,000-20,000

Figure UO-5. Diagram showing general correlation of rock units from the Uinta Basin, Utah, to the Axial Uplift, Colorado, and significant producing and source horizons (modified after Spencer and Wilson, 1988)

SIL. ORD.

Ophir Shale Lodore Sandstone Precambrian

DEV.

Pinyon P

Manitou Fm. Dotsero Fm. Sawatch Sandstone

Figure UO-4. General stratigraphic column of the Uinta Basin (modified after Anonymous, 1995).

UINTAH AND OURAY INDIAN RESERVATION

UTAH

Geology Overview 3

During Eocene time (38-50 million years ago) lar ge amounts of sediment from adjacent higher areas were deposited in lacustrine and fluvial environments in the basin. These sediments, assigned to the Wasatch, Green River, and Uinta Formations, are perhaps more than 15,000 feet thick in the center of the basin, and contain important mineral resources (FIGURE UO-6). Much of the area no w occupied by the Uinta Basin was covered by a large lake during Eocene time. Lacustrine marlstone, oil shale, limestone, siltstone, and sandstone of the Green River Formation were deposited in the lake. During the lake's expansionary periods, fluvial sediments were deposited which are now beneath and periph eral to the lacustrine sediments. These fluvial deposits form the shale, sandstone, and conglomerate of the Wasatch Formation. As the lake receded, fluvial sediments were deposited on its periphery, and eventually covered the entire area formerly occupied by the lake. These deposits comprise the Uinta Formation (Anderson,1995).

WYOMING UTAH

Uinta Formation The Late Eocene Uinta Formation consists of fluvial deposits that overlie the Green River Formation from the last phase of Lake Uinta. Later, the lake filled up with volcaniclastic material, followed by abundant bedded evaporites. Depths to the top of the formation range from 2,566 feet to 3,678 feet, with the average being 3,554 feet. Most of the production is from the Lo wer Uinta, which is a tran sitional unit between the Green River Formation and the fluvial Up per Uinta. The Lower Uinta is 350 to 450 feet thick in the Horse shoe Bend field, a reservoir that has produced over 15 BCF of nonassociated gas and 5,000 barrels of condensate. This is the only res ervoir that has produced at least 5 BCFG from the Uinta Formation, although minor production exists elsewhere in the basin (FIGURES UO-6 and UO-7). The primary dri ve mechanism is gas expansion and gravity, and the trap is an updip stratigraphic pinch-out. The average monthly gas production has been increasing since 1981 due to development drilling and new wells that were drilled in the ear ly to mid-1980s. The Uinta F ormation is rarely a primary drilling target, but it is a shal low, low cost target with potential for new discoveries (Morgan, 1993a). Green River Formation The Eocene-Paleocene Green River Formation is 2,000 to over 8,000 feet thick. It accumulated in and around ancestral Lake Flagstaff and Lake Uinta, along with the alluvial-fluvial deposits of the Wasatch Formation. The Green River Formation was de posited as thick, regionally extensive stratigraphic sequences in marginal and open lacustrine environments. Depths to the top of the formation range from 2,315 to 7,456 feet, and most wells produce from zones 3 4,000 feet below the top. The majority of the producing zones are channel sandstones about 10 to 30 feet thick, but some reservoirs produce from carbonate grainstones 10 to 20 feet in thickness (FIGURE UO8). The porosity and permeability of these zones can be either reduced or enhanced by diagenetic effects. The

COLORADO

6

R21E

1

6

R22E

Horseshoe Bend Field boundary

T 6 S

1400

Federal no. 3

31

160

0

N

18

6

00

U

31

D

UIN

Cedar Rim 2,3

Bluebell 2,3

Duchesne

Horseshoe Bend 1 Wonsits Valley 2

Walker Hollow 2

Powder Springs 2

T 7 S

2200

2,3 Altamont

Vernal

2000

TA

MOUNTAINS

Producing gas well Abandoned gas well

0 0

31 36 31

Rangeley

1 1 2 3

2

3mi

4km

Monument Butte 2

UINTA BASIN

Natural Buttes 2,3

Rock House 3

FERC Tight formation designated area

Maximum extent of Uinta Basin plays

UTAH

COLORADO

0 0

10

10 20

20 30

40

30mi 50km

Figure UO-6. The Uinta Basin with the maximum extent of play areas based on production and hy drocarbon shows. Reservoirs are labeled: 1, Uinta Formation; 2, Green River Formation; and 3, Wa satch Formation. Note outline for Federal Energy Regulatory Commission (FERC) tight formation designated area (Wasatch/Mesaverde) in the east part of the basin. Hachured line indicates approx imate limits of Tertiary units in the Uinta Basin (modified after Chidsey, 1993a).

average porosity of Green River reservoirs ranges from 5 to 20 per cent, and the permeability ranges from 0.1 to 42 millidarcies (mD). The source rocks for oil and associated g as found in the Green River Formation are interbedded organic-rich carbonate mudstones located at depths of 8,500 to 12,500 feet in the north-central part of the basin. Hydrocarbons, which were generated in deep overpres sured zones, migrated laterally along fracture systems to shallow reservoirs located on the south and east flanks of the basin. There are more than 60 kno wn reservoirs producing from the Green River Formation, 9 of which have each produced more than 5 BCFG (FIGURE UO-6). The Roosevelt reservoir was the first to pro duce gas from this formation in 1949. Monthly production peaked in the mid-1970s, and decreased to a low in 1982. It has been increas ing since then due to in-fill drilling programs in several reservoirs (Chidsey, 1993b).

Figure UO-7. Structure contour map of the Horseshoe Bend area. Datum is the top of Unit A, Uinta Formation with a contour interval of 200 ft. Only wells that have produced from the Uinta Formation are shown (modified after Morgan, 1993a).

UINTAH AND OURAY INDIAN RESERVATION

UTAH

Producing Formations

4

Wasatch Formation

The Eocene-Paleocene Wasatch Formation is up to 3,000 feet thick. It accumulated in and around ancestral Lake Flagstaff and Lake Uin ta in an intertonguing relationship with the Green River Formation. It was deposited as thick, regionally extensive stratigraphic sequen ces primarily in an alluvial-fluvial environment peripheral to the an cestral lakes. Depths to the top of the formation range from 3,147 to 10,754 feet (FIGURE UO-9). Most of the production comes from lenticular fluvial-alluvial channel and alluvial overbank sandstone deposits. The productive sandstones are usually isolated and encased in siltstones, mudstones, and shales (Figure UO-10). Porosity and permeability are generally reduced by diagenesis, so production is enhanced near or along ma jor fault and fracture zones. The average porosity ranges from 5 to 20 percent, and the permeability is 0.1 mD or lower. The source rocks for oil and associated gas found in the Wasatch Formation are organic-rich carbonate mudstones of the Green River Formation, and are located at a depth of 8,500 to 12,500 feet in the north-central part of the basin. Source rocks for the non-associated gas are organic-rich siltstones and mudstones, carbonate shales, and coals of the Mesaverde Group, located at depths of 6,000 feet or greater.

0 0 1km 1mi

There are more than 60 known res ervoirs, 5 of which have produced at least 5 BCFG (Figure UO-6). The first reservoir to produce from the Wasatch Formation was Peters Point in 1953. The total monthly gas production in creased between 1973 and 1982, and has been fairly constant since then (Chidsey, 1993c).

Wasatch Co. Duchesne Co.

Approximate base of Tertiary rocks

Natural Buttes Field

ati

on

Utah Colorado

Co

lton

Fo rm

Coastal Oil Gas Corp. CIG 62D-36-9-22

Vernal

nw sw sec. 36 T9S R22E Uintah County, Utah K.B. 4949'

Green River Formation S.P. Res.

Green

mation er For Riv

Colton

a Form

Fo r

ton

ma

Col

Price

tio

Perf.

5000

at

Green

Fo r

m

4926'-6975' (gross)

io

n

IPF

20

Alluvial-fluvial Marginal lacustrine

0 10 10 20 20mi

20

+12

00

N

0 30km

T 9 S

+1400

20

30

+18

00

Figure UO-10. Typical SPresistivity log of the Natural Buttes Wasatch reservoir, Uintah County, Utah (modified after Chidsey, 1993c).

Mesaverde Group

T.D. 7000' Completed: 4-26-81

6400

6200

00

Duchesne Co. Uintah Co.

+16

10

Figure UO-8. Structure contour map with isopach of single sandstone bed, Monument Butte reservoir, Duchesne and Uinta Counties, Utah. Structure con tours (dashed lines with contour interval of 200 ft.) are based on a datum ap proximately 150 ft. below the middle marker of the Green River Formation and show no structural closure. Net sandstone isopachs (solid lines with contour in terval of 10 ft.) are based on one of many individual productive sandstone units encased by shale or mudstone. Isopach geometry indicates deposition of sand stone by meandering streams. The trap is created by updip pinch-out of chan nel sandstone to south along regional strike (modified after Chidsey, 1993b).

6000

10

Figure UO-9. Major depositional facies and distribution of formations at the Paleocene-Eocene boundary. Note widespread Wasatch-Colton deposition in the Uinta Basin (modified after Chidsey, 1993).

5800

Open lacustrine

20 0 1

5600

5400

20

Alluvial-fluvial

W as

+10

00

atc

00

Wasatch Formation

h

N

+80

5200

R17E

Carbon Co. Emery Co.

Uintah Co. Grand Co.

1900 MCFGPD 3 BWPD

4800

n

4600

Ri

tion

ve r

4400

UINTAH AND OURAY INDIAN RESERVATION

UTAH

Producing Formations

5

Mesaverde Group

Gas from Mesaverde Group reservoirs is found in both structural and stratigraphic traps. Some reservoirs, like those in Natural Buttes Field, are part of larger, basin-centered gas traps where the gas collects downdip from more permeable water-filled reservoirs. Average depth to the top of productive reservoirs ranges from 1300 to >8500 feet. The terminology of the Mesaverde Group is complex, due to fa cies changes that occurred as the Cretaceous Interior Sea trans gressed and regressed along its western margin in the Piceance-Uinta Basin area. The Mesaverde consists of three dominant reservoir facies: lenticular, fluvial sandstones of the Williams Fork Forma tion, coals that occur in the basal portion of the Williams Fork For mation, and extensive shoreline-marine sandstones of the Iles For mation. The fluvial sandstones of the Williams Fork Formation are ap proximately 4000 feet thick in the eastern part of the Piceance Ba sin, thinning to <2000 feet on the Douglas Creek Arch and 2200 2900 feet in Natural Buttes Field in the Uinta Basin. These sandstones are lithic arkoses and feldspathic arenites containing authigenic quartz and carbonate cement. They have low porosities, ranging from 7-12%, and low matrix permeabilities (<0.1 mD) due to the abundance of authigenic clays. The shoreline-marine sandstones of the lower Mesaverde Iles Formation were deposited during transgressive and regressive cycles along northeast-southwest trending shorelines. These sandstones merge with fluvial facies to the northwest and the Mancos Shale to the southeast. The most productive members are the Cozzette, Cor coran, and Castlegate Sandstones. The Castlegate Sandstone is a clean, fine-grained, subarkose to sublitharenite, with low porosity and permeability due to pore-filling authigenic clays. It was deposited along ancient shorelines or as offshore bars. In the southeastern part of the Uinta Basin, 50-70 feet thick Castlegate sandstones produce from structural traps at depths of 8000 feet. Permeabilities range from 0.5-0.9 mD. All fields that produce from the Castlegate involve some type of structural closure, and several close against faults. Production rates are enhanced by the associated tectonic fractures. Source rocks for gas produced from the fluvial sandstones at Natural Buttes Field are coals and carbonaceous shales. The source for the shoreline-marine sandstones is probably the Mancos Shale.

Porosities of the Mesaverde Group sandstones remain unusually sta

ble over a large vitrinite reflectance interval (FIGURES UO-11 and UO-

12), implying that sparsely explored deep central basins may hold some promise (Tremain, 1993).

30

POROSITY, IN PERCENT

Figure UO-11. Plot of core-plug porosity vs. reflectance for 25th and 75th porosity percentiles (joined by vertical lines) of nonmarine sandstone intervals of the Mesaverde Group, Uinta and Piceance Creek Basins. Mesaverde data are compared with type curve and to 10th and 90th porosity percentiles representing sandstones in general. Note that the porosity does not decrease within the win dow of hydrocarbon generation (Ro of 0.070-1.8%) (modified after Nuccio et al., 1992).

25 20

90th percentile

15

10 9 8 7 6 5 4 3

Type curve 10th percentile

2

Figures UO-12A and 12B. Map showing the region (pink area) between Ro 0.70 and 1.8%, where porosity of sandstones at the base of the Mesaverde Group does not decrease as a function of increasing Ro. This region defines the area of optimum gas recovery for A, Upper Mesaverde; B, Lower Mesa verde (modified after Nuccio et al., 1992).

111o 00' 110o45' 110o30' 110o15' 110o00' 109o45' 109o30' 109o15' 109o00'

25th to 75th PERCENTILES

1

0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.5 2.0 2.5 3.0

VITRINITE REFECTANCE, IN PERCENT

A

40o30'

111o 00'

110o45'

110o30'

110o15'

110o00'

109o45'

109o30'

109o15'

109o00'

B

COLORADO

Jensen Altamont Jensen

Altamont 2.00 40o15' Duchesne

40o15' Duchesne

40o00' 1.10

40o00'

1.5

0

1.

10

39o45'

0.75

Rive r

39o45'

ver

Gree n

39o30'

39o30'

Gree

Price

Price

n Ri

0.75

0.60

39o15'

0 0 10

10 20

20

30 MILES

0.50

39o15'

0 0 10

10 20

20

30 MILES

0.65

30 KILOMETERS

30 KILOMETERS

UINTAH AND OURAY INDIAN RESERVATION

UTAH

COLORADO

Vernal

40o30'

Vernal

UTAH

UTAH

Producing Formations

6

Mancos Shale As of December 1990, almost 359.5 BCF of natural gas have been produced from Upper Cretaceous Mancos Shale reservoirs (FIGURE UO-13). Most of the production comes from the silty, tight gas sand stone reservoirs of the Mancos B (also called the Emery Sandstone) in the middle of the Mancos Shale. Gas is also produced from the Mancos A/Morapos Sandstone, a conventional, clean sandstone found in the upper transition zone between the Mancos Shale and the overlying Mesaverde Group (FIGURE UO-14). The Douglas Creek North Field has produced >5 BCFG from the Upper Mancos/Morapos Sandstone (figure 13). In this area, the Up per Mancos consists of up to 34 feet of mud to coarse-grained, wellsorted sandstone with 20% porosity and 100 mD permeability. It was deposited as shelf sands in a marginal-marine setting, and is probably time-equivalent to the Castlegate Sandstone. The Mancos B consists of 500 to >1000 feet of finely interbed ded and discontinuous claystone, siltstone, and very fine- to finegrained sandstone, with an average net pay interval of 30-250 feet. It is characterized by low porosities and permeabilities, with porosities ranging from 10-11% on the Douglas Creek Arch, to <2% on the flanks. Permeabilities are <0.1 mD on the average. Mancos B sedi ments were deposited on a northerly prograding submarine slope or foreslope, approximately 100 miles to the east of the time-equivalent Emery shoreline in Utah (Noe, 1993a).

S

Argo Unit 2-20

sec 20, T5S, R102W

Cities Service USA 1

sec 7, T4S, R102W

Nat. Assoc. Pet Govt. 1

sec 6 T3S, R102W

N

Superior Unit 3 S.P. R Texas Douglas Cr. 1

sec 9 T2S,R101W

Phillips Unit B-1

sec 18, T1S, R101W

G. E. Kadane Moran 1

sec 2, T1N, R101W

sec 1 T3S, R102W

S.P.

R Mesaverde Group

An ch

SP

R

S.P.

R

S.P.

R

os nc Ma

1000

or

To n gu e

e U. S

go ego

U. Se g

o

S.P.

R

3000

3000

L. S

L. Sego

A

1000

nc

os

A

(Mo

rapo

s)

1000

Ma

Buck T ongue

(Morap

os)

1000

S.P.

R

Mancos Shale

2000

1000

Gas fields

<5BCF >5BCF

m 0

ft 0

A'B' C'

2000

Douglas Cr. N. Philadelphia Cr.

2000

Utah

Colorado

FERC tight sand areas Approximate line of section Mancos Marine Sandstone play

4000

Rangeley

4000

Silt

Mark er

100 500

Lower Horse Draw Douglas Cr. W. Douglas Cr.

BA SIN

TA

UIN

Cathedral

Man

2000

Dragon Trail

Ma n (E cos me ry) B

cos B

2000

200 750

REEK ARCH B A

300

1000

DOUGLAS C

N

C

E

UTAH C COLORADO

UN

BA

5000

EA

Datum

20,000 6,000 40,000 ft

5000

PI

C

3000 ft

above

Douglas Creek fault

sea level

CO

SI

MP AH

N

0 0

GR

12,000 m

E UP LIF T

Vertical exaggeration 50:1

Grand Junction 0 10 10 20 20 30 40 30mi 50km

PARADOX BASIN

0

sa Me lta De

Figure UO-14. South to north structural cross section along the Douglas Creek Arch of the Mancos B interval and other sandstones in the transitional zone between the Mancos Shale and Mesaverde Group (modified after Noe, 1993a).

Figure UO-13. Gas fields of the Upper Cretaceous Mancos Shale (modified after Noe, 1993a)

UINTAH AND OURAY INDIAN RESERVATION

UTAH

Producing Formations

7

Dakota Sandstone, Cedar Mountain Formation, Morrison Formation The Dakota Sandstone, Cedar Mountain Formation, and Morrison Formation are similar in lithologic succession. Each contains a basal, continuous, conglomeratic sandstone or conglomerate, like the Salt Wash Member of the Morrison Formation, the Buckhorn Conglomerate of the Cedar Mountain Formation, and the lower part of the Dakota Sandstone. This is overlain by interbedded shales and lenticular sandstones, like the Brushy Basin Member of the Morrison and the upper units of the Cedar Mountain and Dakota (Figure UO15). The basal conglomeratic units are braided stream deposits, while the upper units of the Morrison and Cedar Mountain Formations are thought to be floodplain and meandering stream deposits. The Upper Dakota was deposited in a complex coastal setting con-

Figure UO-16. Three dimensional model of Dakota Sandstone depositional environments at Hell's Hole Field (modified after Moretti et al., 1992).

L VAL AL

EY

ALL

UVI

PL

AIN

AS CO

L TA

Distributary Channel

FO

H RS

OR

E

TYPE LOG

San Arroyo Field

Braided Stream Coastal Plain with Marshes Cross Bedding Beach Ridges

SH

E OR

CE FA

D A K O TA S I LT

D A K O TA SANDSTONE

Foreshore Sand Shoreface Slope and Sand

C E D A R M O U N TA I N F O R M AT I O N

50 25 0

FEET

Highlands Marine Shale

MORRISON F O R M AT I O N

MILES 0 1 2 3

Buckhorn Member Brushy Basin Member

Figure UO-17. Structure contour map of the top of the Entrada Sandstone, San Arroyo/Westwater area, Grand County, Utah. The area that is productive from the Entrada Sandstone is colored in pink. The Bar X Field has produced less than 5 BCF of gas from the Entrada Sandstone. Contour interval is 500 feet (modified after Morgan, 1993b).

4800 5000

Salt Wash Member

sisting of coastal plain, fluvial, swamp, marsh, tidal flat, delta, beach, and nearshore marine environments (Fig. UO-16). The Morrison Formation is approximately 350-450 feet thick, the Cedar Mountain Formation is approximately 0-150 feet thick, and the Dakota Sandstone is approximately 40-250 feet thick (Noe, 1993b). Entrada Sandstone In northeastern Utah, the Entrada Sandstone consists of dune and interdune eolian deposits associated with the northerly retreat of a Jurassic sea. The sandstones are gray to orange, fine- to mediumgrained, well-sorted and cross-bedded. Gas and some oil are produced from traps formed by anticlinal closures on Laramide structures. Three Entrada reservoirs have produced >44 BCF gas; most of this production comes from San Arroyo Field (FIGURE UO-17). Average depth to the top of the reservoir varies from 5250 feet at San Arroyo to 6700 feet at Wilson Creek Field in Colorado. Average net pay thickness in the Uinta Basin is 118 feet at Westwater Field. Average porosity ranges from 16% at San Ar-

royo to 24% at Westwater. Source rocks for San Arroyo and Westwater Fields may have been organic-rich marine deposits of the Permian Phosphoria and Pennsylvanian Paradox Formations (Morgan, 1993b).

R 24 E

D 0 0 1 1 2 3 4 mi U

R 25 E

D U U D

R 26 E

-500

2 3 4 5 6 km 0

1000

San Arroyo

T 16 S

Figure UO-15. Type log from the San Arroyo Field (modified after Hill and Bereskin, 1993).

UINTAH AND OURAY INDIAN RESERVATION

UTAH

5200 5400

R 23 E

-50 0

0

500

Bar X

1

500

000

D U D U 500 D U

Westwater

50 0

ENTRADA SANDSTONE

T 17 S

150

0

20

00

25

00

Producing Formations

8

Weber Sandstone

The Weber Sandstone is a fine-grained, subarkosic to quartz arenite of eolian origin deposited during Desmoinesian, Missourian, and Wolfcampian time. In Rangely Field, productive eolian sands were deposited in dune, interdune, and extradune environments (FIGURE UO-19). These sandstones are either cross-laminated or massivelybedded, the cross-laminated lithofacies being the major producer with an average porosity of 12%. Permeability along laminae averages 2 mD, while permeability across laminae averages 0.4 mD. Cumulative production from the Weber Sandstone as of 1990 is

Fluvial Dune Extra Dune Extra

5700

Dune

Extra Dune

724.7 BCF of associated gas and 772 MMBO. The Rangely Weber reservoir contributed 98.9% of the total gas production (FIGURE UO18). Average depth to the top of the Weber is 6500 feet, and the trapping mechanism in all Weber reservoirs is anticlinal closure (Hemborg, 1993).

Gamma ray Depth (API units) 0 150 (ft) 30

5600

Density porosity (%)

10

Sedimentary structure

Depth (ft)

- 5800

Dune Fluvial Dune Extra Dune

111o 41o

GREEN RIVER BASIN WYOMING UTAH ult

fa

Henry's Fork fault

110o

109o

108o

U i nt

a f a u lt

WYOMING COLORADO

Extra

- 5820

MOFFAT ROUTT

5800

Fla n k North

SAND WASH BASIN

5900

U

s Ba ta in

i

Yampa fault

Wolf C

r e e k f a ult Skull Cr. anticline

Willow Creek f a

Danforth Hills Elk Springs Moffat Winter Valley Maudlin Gulch

Craig

Dune Dune

6000

Ashley Valley Altamont - Bluebell Wonsits Valley

ult

Thornburg

Dune Fluvial Extra Fluvial Extra

Dune Complex

WASATCH

ry fault nda ou nb

S plit Mtn lin Vernal a ntic es

Extra Dune

Dune

- 5840

Extra

N

40o

Rangely

- 5860

UINTA BASIN

DUCHESNE UINTAH

>5BCF Weber associated gas fields <5BCF Weber associated gas fields Major oil and gas fields without Weber production Precambrian outcrop Weber Sandstone play

0 0 10 10 20 40 30 40 60 50 mi 80 km

UTAH COLORADO Do

Red Wash

Cre uglas ek A rch

White River uplift PICEANCE BASIN

RIO BLANCO

Gran d ho gbac k

Fluvial

6100

Extra

Unc

omp

Extra

6200

ahg

re

Fluvial Dune Fluvial Extra

GARFIELD MESA UTAH COLO

6300

Fluvial

upl

ift

Glenwood Springs

Extra Dune

Fluvial

- 5880

- 5900

Fluvial

Extra= Extradune Burrows Root casts

Figure UO-18. Location map of Rangely Field and other major and minor Weber Sandstone reservoirs (modified after Hemborg, 1993).

Horizontal lamination

Crosslamination

Convolute lamination

Figure UO-19. Wireline log and core description of the No. 139Y UPRR, Rangely Field. Core shows one cycle of Weber deposition (modified after Hemborg, 1993)

UINTAH AND OURAY INDIAN RESERVATION

UTAH

Producing Formations

9

Play Summary

The United States Geological Survey identifies several petroleum plays in the Uinta-Piceance Basin Province and classifies them as Conventional and Unconventional (Gautier et al., 1995). The discussions that follow are limited to those with direct significance for future petroleum development in the Uintah and Ouray Indian Reservation (TABLE 1).

Play Types

Conventional Plays- Discrete deposits, usually bounded by a downdip water contact, from which oil, gas or NGL can be extracted using traditional development practices, including production at the surface from a well as a consequence of natural pressure within the subsurface reservoir, artificial lifting of oil from the reservoir to the surface where applicable, and the maintenance of reservoir pressure by means of water or gas injection. Unconventional Plays- A broad class of hydrocarbon deposits of a type (such as gas in tight sandstones, gas shales, and coal-bed gas) that historically has not been produced using traditional development practices. Such accumulations include most continuous-type deposits.

Uinta-Piceance Basin 486,712 MBO 1,992,627 MMCFG 40,262 MBNGL Undiscovered resources and numbers of fields are

for Province-wide plays. No attempt has been made to estimate number of undiscovered fields within the Uintah and Ouray Indian Reservation.

(chance of success) (min., mean, max.) Gas (500, 3000, 6000)ft Oil (1000, 5000, 14000)ft

Reservation: Geologic Province: Province Area: Reservation Area:

Uintah and Ouray Uinta-Piceance Basin 40,000 sq. miles (25.6 million acres) 6250 sq. miles (4 million acres)

USGS Designation

Total Production in

Province as of 1996 Oil:

Gas:

NGL:

Oil or Gas Known Accumulations

Play Type

Description of Play

Undiscovered Accumulations > 1 MMBOE Play Probability Drilling depths

Field Size and Number

Field Size (median, mean) Gas (15 BCFG, 18.9 BCFG) Oil (2 MMBO, 2.8 MMBO) No. of Undiscovered Fields (min., median, max., mean) Gas (2, 6, 15, 7.1) Oil (4, 13, 30, 14.7)

Pay Thickness

Porosity/Permeability

Uinta Tertiary Oil and Gas Play

2002

1

Upper Cretaceous Conventional Play

Fluvial and lacustrine sandstones in the Wasatch and Green River Formations.

Both

Gas (917,288 MMCFG) Oil (485,592 MBO)

Variable

10-15%/v, low to 1000 md

1

2

Cretaceous Dakota

to Jurassic Play

2003

Shallow sandstones of the Mesaverde Group.

Mostly Gas

Gas (129,540 MMCFG)

Field Size (median, mean) Gas (12 BCFG, 15.2 BCFG) No. of Undiscovered Fields (min., median, max., mean) Gas (10, 23, 50, 25.9)

1

Gas (500, 3500, 6000)ft

up to 80 feet

8-18%/<0.1md

2004

3

Permian-Pennsylvanian Sandstones and Carbonates Play

2005

Fluvial Dakota Sandstone,

discontinuous fluvial Morrison Sandstone, blanket eolian Entrada Sandstone.

90% Gas

10% Oil

Gas (579,169 MMCFG)

Field Size (median, mean)

Gas (10 BCFG, 13.1 BCFG)

Oil (1 MMBOE, 1.5 MMBOE) No. of Undiscovered Fields (min., median, max., mean) Gas (3, 15, 25, 14.6) Oil (1, 2, 4, 2.2)

1

Gas (500, 3500, 6000)ft Oil (1000, 4000, 6500)ft

Dakota - 25 feet Buckhorn - 26 feet Morrison - 11 feet

10-25%/

Unknown Permeability

Very high risk Permian-Pennsylvanian sandstones and carbonates.

Mostly Oil

4

Basin Margin Subthrusts Play

(hypothetical)

2014

Oil EUR (980.5 MMBO) Gas EUR (>706 BCFG)

Field Size (median, mean) Oil (9 MMBO, 25.0 MMBO) No. of Undiscovered Fields (min., median, max., mean) Oil (1, 4, 15, 5.7)

1

Oil (6000, 10000, 12000)ft

275 feet

11-14%/ Unknown Permeability

5

Cretaceous Self-Sourced Fractured Shales Play

(hypothetical, continuous)

2009

Closures beneath thrusts, reservoirs range from Paleozoic to Tertiary in age.

Both

N/A

Field Size (median, mean) Oil (2 MMBO, 5.3 MMBO) Gas (15 BCFG, 25.0 BCFG) No. of Undiscovered Fields (min., median, max., mean) Oil (1, 2, 7, .05) Gas (1, 3, 10, .07)

0.18

Oil (5000, 12000, 18000)ft Gas (5000, 14000, 25000)ft

Unknown

6

Tight Gas Uinta Tertiary East Play

(continuous)

2015

Upper Mancos fractured shale. Best fracturing occurs in brittle siltstones, carbonates, and

calcareous shales.

Both

Oil EUR(14 MMBO)

Per well EUR estimates vary

1

Oil/Gas (500, 2800, 6000)ft

10->50 feet

10-20%/0.01-100md

7

Tight Gas Uinta Tertiary West Play

(hypothetical, continuous)

2016

Medium- to fine-grained fluvial

sandstones interbedded with

mudstones, siltstones, shales, and some coal of the Wasatch Fm.

Gas

N/A

N/A

1

Gas (3000, 6400, 10500)ft

up to 80 feet

<5-9%/<0.1md

8

Basin Flank Uinta

Mesaverde Play

(hypothetical, continuous)

2018

Medium- to fine-grained fluvial sandstones interbedded with mudstones, siltstones, shales, and some coal of the Wasatch Fm.

Gas

N/A

N/A

1

Gas (4500, 7500, 11000)ft

up to 80 feet

4-8%/<0.01md

9

Deep Synclinal Uinta

Mesaverde Play

(hypothetical, continuous)

2020

Based on widespread occurrence of tight, gas-saturated continental and marginal marine sandstone.

Gas

N/A

N/A

1

Gas

(8000, 9500, 15000)ft

4->12%/<0.1md

10

Table 1. Play summary chart.

Based on expected occurrence of

gas-saturated tight Mesaverde Sandstone at depths >15,000 feet.

Gas

N/A

N/A

1

Gas (15000, 20000, 25000)ft

N/A

3-8% Unknown permeability

Conventional play type

Unconventional/Hypothetical play type

UINTAH AND OURAY INDIAN RESERVATION

UTAH

Play Summary Table

10

Summary of Play Types The United States Geological Survey has identified many petroleum plays in the Uinta-Piceance Basin Province, classifying them as Conventional and Unconventional. The discussions that follow are limited to those plays with direct significance for future petroleum development on the Uintah and Ouray Indian Reservation. Most of the following is extracted from USGS CD-ROMs DDS-30 and 35 (Gautier et al., 1995). Table 1 is a summary of applicable USGS plays of the Uinta-Piceance Basin Province pertaining to the Uintah and Ouray Reservation.

Conventional Plays Definition - Discrete deposits, usually bounded by a downdip water contact, from which oil, gas, or NGL can be extracted using traditional development practices, including production at the surface from a well as a consequence of natural pressure within the subsurface reservoir, artificial lifting of oil from the reservoir to the surface where applicable, and the maintenance of reservoir pressure by means of water or gas injection.

260 MMBO and 378 BCFG; however, the field is being actively downspaced from 640 acres per well to 320 acres per well. This additional drilling should significantly increase recovery.

Exploration status and resource potential: The conventional gas

Analog Example: Greater Altamont - Bluebell

Figures: UO-20 and UO-21 Location: T 1 N - 4 S, R 2 E - 7 W, on Reservation Producing formations: Wasatch and Green River Formations Other significant shows: Mesaverde Sandstone, gas; Uintah Formation, gas and oil Lithology: Fluvial sandstone, lacustrine sandstones, limestones, dolomites Type of drive: Solution gas Net pay thickness: Multiple zones with variable thickness Porosity: 2-20%, average >10% Permeability: Variable in individual pay sections, ranges from very low up to 1,000 mD in unconsolidated sands Estimated primary 316 MMBO, 360.5 BCFG, 330.2 MMBW recovery: Other major analog fields: Greater Natural Buttes Monument Buttes Red Wash Walker Hollow Wonsits Valley

PLAY 1 - UINTA TERTIARY OIL AND GAS PLAY

The Uinta Tertiary Oil and Gas Play is based on oil and gas accumulations primarily in stratigraphic traps in fluvial and lacustrine sandstones in the Wasatch and Green River Formations. The play area is limited updip by the presence of brackish and fresh water in rocks near the outcrop. Reservoirs: Reservoir sandstones of the Wasatch and Green River Formations are Paleocene and Eocene in age and are predominant41 o ly litharenites and feldspathic litharenites over most of the basin. Some lacustrine limestones produce in the deeper part of the basin. Porosities range from <10 percent in the deep Altamont-Bluebell field area to >15 percent at shallower depths (<4,000 feet).

109 o

part of this play is fairly well explored, but a maximum of 15 conventional fields greater than 6 BCFG may be found, according to U.S.G.S. estimates (Table 1). Because of the very large volume of oil generated deep in the basin, a maximum of 30 oil fields greater than 1 MMBO may remain to be found.

111 o

UTAH

Uinta

110 o

N

WYOMING

uplift

UTAH COLORADO

A

SW

Altamont - Bluebell fields

A'

NE

Vernal

' 9000

Duchesne

A'

0' 800

Uinta and Duchesne River outcrop

' 00 70

40 o

40 00 '

Colton outcrop

0' 00 5

A

North Horn outcrop

Price Green River outcrop

0' 00 3

Green River outcrop

Wasatch outcrop

0 0 10 10 20 20 30 40 30 mi 50km

39 o

Figure UO-20. Combined thickness of the Green River, Wasatch/Colton, and North Horn Formations with outcrop areas indicated. Contour interval is 1000 feet. Cross section AA' is shown in Figure UO-21 (modified after Chidsey, 1993a).

Source rocks: The source rocks for much of the non-associated Wasatch gas in the basin 9000 are the underlying Cretaceous Mesaverde gasprone coals, shales, and mudstones, but some 6000 Duchesne River Fm. may have a Tertiary origin. In the northern No part of the basin, oil is the predominant hyrth Green River Fm. Col 3000 Ho ton drocarbon. This oil comes from lipid-rich larn Fm. Fm Uinta Fm. . (p custrine shales and marlstones in the Green art SL ) River Formation. A complex mixing of oil and gas from different sources has resulted in -3000 more gas fields at shallower depths and preNo r th dominantly oil in deeper reservoirs. This is Ho -6000 Colton Fm. rn F the opposite of what occurs in many other bam. (pa r t) sins. &M -9000 esa Timing and migration: The Mesaverde ver ft m de Gro Group began generating gas in the Early Terti2000 up 6000 Area of fluid-pressure ary, and the Green River Formation began gradients >0.5 psi/ft generating oil and gas in the Middle Tertiary 1000 3000 Paleozoic-Mesozoic rock to the present. The deep (>10,000 feet) Terti12 8 16 20 mi 4 ary oil fields are highly overpressured as a re0 sult of present-day hydrocarbon generation. 0 5 10 15 20 km Traps: The traps are mostly stratigraphic, but some structural-stratigraphic traps occur, such as the Red Wash Field area (EUR 175 Figure UO-21. Generalized southwest to northeast cross section of Tertiary rocks in the Uinta Basin showing major facies, MMBO, 373 BCFG). The largest producing intertonguing relationships, and stratigraphic names. Area of fluid-pressure gradients >0.5 psi/ft indicated in red. Line of section is area is the greater Altamont-Bluebell area, shown in Figure UO-11 (modified after Chidsey, 1993a). which has an estimated ultimate recovery of

Wasatch Fm.

60 00 '

UINTAH AND OURAY INDIAN RESERVATION

UTAH

CONVENTIONAL PLAY TYPE: Uinta Tertiary Oil and Gas Play 11

UPPER CRETACEOUS CONVENTIONAL PLAY

This is primarily a gas play in sandstones of the Mesaverde Group at shallow depths in both the Piceance and Uinta Basins; however, dis covered fields are mostly in the Piceance Basin. Fields are localized by structure, but stratigraphic traps have also been found. The play is limited downdip where the reservoirs become unconventional (tight) and is limited updip by fresh-water flushing. The Mesaverde part of this play has some areal overlap with tight Mesaverde reser voirs. The tight rocks are generally beneath and/or downdip of con ventional Mesaverde reservoirs.

Reservoirs: The reservoir rocks are Cretaceous Mesaverde Group sandstones deposited in marginal-marine, fluvio-deltaic, and fluvial environments. Some very fine-grained sandstone and siltstone reser voirs were deposited in a shallow-marine shelf environment seaward of, and in part beneath, the Mesaverde Group. These reservoirs in clude the Mancos Shale "B" and equivalents, but much of the Mancos "B" fields are tight and developed by drilling, although there is some potential for field growth. Source Rocks: The Mesaverde Group source beds are organic shales (including some coals) interbedded with sandstones. Timing and Migration: Time of generation is Late Tertiary to pres

R18E

Ri ve r

R21E

R22E

R23E

A

31

MILES

A'

GREEN RIVER FM.

T

re e n

9 S

G

A'

Ri

WASATCH FM. 2000 FT.

Figure UO-23. Diagrammatic west-east cross section showing stratigraphy of the Greater Natural Buttes Field and position of Wasatch producing sandstones that overlie the Mesaverde. Line of section is shown in Figure UO 14 (modified after Osmond, 1992).

W te hi

A

T

r ve

10 S

NORTH HORN FM.

OUP E GR VERD MESA FT. 2500

Outline of gas field Outline of oil field Line of cross section Fault (E-W) dashed where uncertain Gilsonite vein (NW-SE) dashed where uncertain

N

0 0

6mi 10km

T

11 S

E TON NDS E SA GAT TLE CAS

MANCOS SHALE

SU RF AC E

Figure UO-22. Map of the Greater Natural Buttes Gas Field (modified after Osmond, 1992).

UINTA FM. 0-1700

Gray-Green Shale and Fluvial Sandstone

PRODUCTION Horseshoe Bend 12 Miles N of GNB

ent.

Traps: Traps are predominantly structural-stratigraphic and strati

R 20 E R 21 E R 22 E R 23 E

Gilsonite Veins

EOCENE

graphic. Accumulations are found at depths of <1,000 feet to 6,000 feet, with a median depth of 3,500 feet.

Exploration Status: The conventional part of the play is well ex

GREEN

T 8 S

Lacustrine and Marginal Lacustrine Gray-Green Shale, Marlstone and Sandstone

RIVER FM. 3800' 'H' MARKER MAHOGANY OIL SHALE BED White River, 5 Miles North of GNB OIL with ASSOCIATED GAS Red Wash/Wonsits to N and NE Monument Butte and Other Fields to W GAS Greater Natural Buttes, SE Red Wash/Powder Springs 9 Miles NE of GNB

plored in the Piceance Basin and only moderately explored in the Uinta Basin. Because of the large volume of gas generated by Me saverde source beds, the U.S.G.S. estimates that a minimum of 10 and a maximum of 50 conventional fields may be discovered (Table 1). Analog Field Greater Natural Buttes

Figures: UO-22 to UO - 25 T 8-10 S, R 19-23 E (SLB&M), T 36 S, R 25-26 E (SLPM), Uinta County, Utah, on Reservation Producing formations: Green River Formation, Wasatch Formation Mesaverde Group Other significant shows: None Lithology: Fluvial and lacustrine sandstones, limestones, dolomites Type of drive: Pressure depletion Net pay thickness: Individual sands may be up to 80 feet in thickness Porosity: 8-18%, average 12% (logs) Permeability: Generally less than 0.1 mD Estimated ultimate recovery: 0.5 BCFG Other major analog fields: Devil's Playground Red Wash Wonsits Valley Location:

+0 _

-5

00

Field Outline

Ui nta hS Sa lt L peci a ak e M l Me rid eri dia ian n

00 -5

+0 _

00 +5

T 9 S

DOUGLAS CREEK MEMBER

0 00 +1

WASATCH Red Shale and Fluvial Sandstone FM.

T 1 0 S

Greater Natural Buttes Peters Point, 20 Miles SW of GNB

+500

2000' We s

t

NORTH HORN - FLAGSTAFF Varicolored Shales, Fluvial Sandstone, Lacustrine Limestone and Coal 'OHIO CRK CGL' - BEDS AT DARL CYN' Sandstone with Dark Chert Pebbles Farrer FM. Tight Sands and Siltstones, Gray Shale and Coal IM MA TU RE FO MA RG TU RE AS NELSEN FM. - 700FT. COAL BEARING

+1000

Datum: Top Wasatch Formation Contour Interval: 500 feet

PALEO CENE

C R E TA C E O U S

T 1 1 S

MESAVERDE GROUP 2200' - 2900'

Greater Natural Buttes

Figure UO-24. Structural contour map of Natural Buttes Field. Bold line depicts approximate Reservation boundary (modified after Hill and Bereskin, 1993).

Ea

st

MANCOS SHALE - 5000' (Marine)

Figure UO-25. Stratigraphic column for Greater Natural Buttes (GNB) Field, showing formations which produce oil and gas in GNB and nearby fields (modified after Osmond, 1992).

Dakota Sandstone (Fluvial)

Upper Level for Gas Generation Cuts Down, Stratigraphically, + Eastward Across GNB from 1000' Above Mesaverde to below the Base of Mesaverde; Based on Coal Rank High Volitile A Bituminous Ro 0.85% (Nuccio and Johnson 1986)

Book Cliffs 30 Miles S of GNB

UINTAH AND OURAY INDIAN RESERVATION

UTAH

CONVENTIONAL PLAY TYPE:

Upper Cretaceous Conventional Play 12

CRETACEOUS DAKOTA TO JURASSIC PLAY

R 22 E

26 25

R 23 E

30

R 24 E

29 28

TYPE LOG

FENCE CANYON FIELD

Uintah and Carbon Counties, Utah

San Arroyo Field

This is primarily a conventional reservoir play, but tight reservoirs are mixed with the conventional rocks. The discovered fields are mostly structurally controlled. Based on known fields, it appears to be predominantly a gas play (90 percent gas, 10 percent oil). The Cretaceous Dakota Group (including the Cedar Mountain Formation) and the Jurassic rocks were combined into one play by the U.S.G.S. because many fields produce from rocks of both ages and any struc ture drilled has the potential for accumulations in both. The Wilson Creek Field is the southeasternmost structure along a series of pro ducing structures that includes the Maudlin Gulch Field. The downdip limits of the play are where the rocks become tight and reservoirs are unconventional (>6,000 feet).

Reservoirs: The Cretaceous Dakota reservoirs vary from lenticular

from the Dakota Group (including the Cedar Mountain Formation) and the Jurassic Entrada Sandstone (FIG URES 27 and 28). Many of the fields have significant amounts of nitrogen and CO2 (as much as 25 percent).

Exploration status and resource potential: The play is maturely de-

- 710

TEXACO 3 F E N C E C A N YO N

D A K O TA S I L T

- 753 - 990

35 36 31 32

- 342

SP

7800

IEL

D A K O TA

MANCOS SHALE DAT U M

33

SANDSTONE

T 15 S

- 617

40 0

- 523

-1570

DA KOTA S I LT MARKER DA KOTA S S C E DA R M T N . F M . BU C K H O R N CGL. MORRISON FM.

7900

0 60 0 80 0 0 10 00 12 0 - 140 00 - 16 -

- 828

OOOOOOO

C E D A R M O U N TA I N F O R M AT I O N

4800

8000

veloped for large fields, but subtle structures and stratigraphic traps may contain as many as 25 significant accumulations (TABLE 1).

31

32

33

34

UINTAH CO CARBON, CO

35

OOOOO

T 15.5 S

6

Buckhorn Member Brushy Basin Member

8100

3 FENCE CANYON

8200

MORRISON F O R M AT I O N

- 1121

5

- 351

4 3 2

5000

to continuous, and are predominantly fluvial in the play area. The Jurassic reservoirs range from discontinuous fluvial sandstones of the Morrison Formation to blanket eolian sandstones of the Entrada Sandstone. Porosities range from <11 percent to about 25 percent.

Source rocks: Source rock data for this play are lacking in the pub

T 16 S

91

PERFS: 7978-8016 Ft. 8079-8106 Ft.

IPF: 877 MCFGPD COMPLETED: 9-29-61

- 13 GEOLOGY BY JOHN OSMOND

lic record, but some dark shales, mudstones, and thin coals are pres ent in the Dakota Group. The overlying marine Cretaceous Mowry and Mancos Shales are both known source beds (mostly oil prone).

Timing and migration: The hydrocarbons were probably generated

STRUCTURE MAP

DAT U M : TO P O F DA KOTA S I LT

0

2000'

4000'

1 MILE

Salt Wash Member

5200

Figure UO-26. Structure map and typical electric log from Fence Canyon Field (modified after Hill and Bereskin, 1993).

in Late Cretaceous to Early Tertiary time, and some may have mi

grated into younger Tertiary structures.

Traps: The known traps are predominantly structural, and some

SAN ARROYO FIELD

R25E R26E

5400

1300

U TA H COLORADO

have stratigraphically modified the accumulation. Many of the fields

are situated on surface anticlines; they tend to be large and were discovered relatively early in the exploration cycle. San Arroyo-East Canyon (EUR 174 BCFG) was discovered in 1955 and produces

17 00

1200

Figure UO-28. Type log from the San Arroyo Field (modified after Hill and Bereskin, 1993).

ENTRADA SANDSTONE

Analog Example: San Arroyo

Figures: UO-27, UO-28 Location: Producing formations: Other producing zones: T 16 S, R 25-26 E, (SLPM), Grand County, Utah, just east of Reservation Dakota Sandstone Castlegate Sandstone, Cedar Mountain and Buckhorn Conglomerate Members of the Cedar Mountain Formation, Brushy Basin and Salt Wash Members of the Morrison Formation, Entrada Sandstone None Interbedded sandstone and shale (Dakota), variegated mudstone with sandstone lenses (Cedar Mountain), sandstone to conglomerate (Buckhorn Member), shale with occasional sandstone beds (Morrison), sandstone (Entrada) Gas expansion 13-80 feet, variable 10-20% NA Not calculated

Analog Example: Fence Canyon

Figure 26 Location: Producing formations: Other significant shows: Lithology: Type of drive: Net pay thickness: Porosity: Permeability: Estimated ultimate recovery: Other major analog fields: T 15-16 S, R 22-23 E, (SLB&M), Uinta and Grand Counties, Utah, on Reservation Dakota Sandstone, Buckhorn Conglomerate, Morrison Formation Cretaceous Mancos Shale Sandstone, white, fine-medium grained, conglomeratic Gas expansion Dakota - 25 ft., Buckhorn - 26 ft., Morrison - 11ft. 10-16% Unknown 10 BCFG Evacuation Creek, Hell's Hole, Park Mountain, San Arroyo

DATUM: TOP OF DAKOTA SILT CONTOUR INTERVAL: 100 FT.

A N TI

16

1400

00

T 16 S

20 00 19

15

00

17

00

00

18

00

Other significant shows: Lithology:

BA

C LI

R

N

SA

-X

E AN

N

TI

AR

C LI

R

N

O

E

YO

Type of drive: Net pay thickness: Porosity: Permeability: Estimated primary recovery:

S A N A R R OYO U N I T

Figure UO-27. Structural contour map of San Arroyo Field (modified after Hill and Bereskin, 1993).

UINTAH AND OURAY INDIAN RESERVATION

UTAH

CONVENTIONAL PLAY TYPE:

Cretaceous Dakota to Jurassic Play 13

Analog Field: Greater Hell's Hole

Figures: UO-29 to UO-31 Location: T 10 S, R 25 E, (SLB&M), Uinta County, Utah; T 1-2 S, R 104 W, Rio Blanco County, Colorado, east of Reservation Dakota Group Mesaverde shales and coals, Mancos Shale (B), Weber Sandstone (Maroon), Leadville Sandstone Gas depletion 25 ft. average, max 57 ft., min 5.5 ft. 14-18% 0.1-10 mD 26.2 BCFG, 65,000 BC

Producing formations: Other significant shows: Lithology: Type of drive: Net pay thickness: Porosity: Permeability: Estimated ultimate recovery:

LEY VAL AL UVI ALL

PL AL ST OA C

AIN

Distributary Channel Braided Stream Coastal Plain with Marshes Cross Bedding Beach Ridges Foreshore Sand

FO

R

H ES

OR

E

COMPOSITE TYPE LOG

HELL'S HOLE FIELD

6600

SH

E OR

CE FA

Dakota Silt

Marine Shale

Shoreface Slope and Sand Highlands Marine Shale

50 25 0 0 1 FEET

Upper Dakota A

6700

Shoreface to Foreshore Marine Sands

Figure UO-30. Three dimensional model of Dakota Sandstone depositional environments at Hell's Hole Field. (modified after Moretti et al., 1992).

MILES 2 3

107O

111O

Upper Dakota B

Shoreface Marine Sands

110O

109O

108O

107O 41O 40O

Middle Dakota C

6800

Coastal Plain, Fluvial Channel, Overbank

DAGGET

UINTA

MOUNTAINS

SAND WASH BASIN

MOFFAT

AXIAL

Lower Dakota D

Braided Alluvial Channels

ALTAMONT

UINTAH DUCHESNE

RED WASH

UTAH COLORADO

ARCH

Rangely Field

UINTA

6900

NATURAL BUTTES

PICEANCE

RIO BLANCO

PICEANCE CR. N. DOUGLAS

BASIN

Figure UO-29. Composite type log for the Dakota section at Hell's Hole, Rio Blanco County, CO, and Uintah County, UT (modified after Moretti et al., 1992).

CARBON

Hell's Hole Area

AR

CH

GARFIELD

WYOMING

AS

Continental Mud, Silt, and Sand

GRAND

D

7000

O

U

G

L

CR

Morrison

EE K

BASIN

MESA

TD 0 100 200 30 20 10 0 -10

UTAH

COLORADO

0 10 20 50 mi.

39O

Figure UO-31. Map showing the Hell's Hole area (modified after Moretti et al., 1992).

UINTAH AND OURAY INDIAN RESERVATION

UTAH

CONVENTIONAL PLAY TYPE: Cretaceous Dakota to Jurassic Play 14

PLAY TYPE 4

PERMIAN-PENNSYLVANIAN SANDSTONES AND CARBONATES PLAY

This is primarily a play for structural and stratigraphic traps in Permian and Pennsylvanian sandstones and carbonates. The objective reservoirs were deposited in predominantly marine and eolian environments. Some redbeds occur, but are not part of the prospective facies. The eastern part of the play is bounded by the expected limit of porous sandstone. The southern boundary is limited by expected presence of structural and stratigraphic traps in the Uinta Basin; the northern limit is based on the expected limit of conventional reservoirs. This play is thought by the U.S.G.S to be very high risk.

Reservoirs: The Permian-Pennsylvanian reservoirs are both sand-

The two producing fields in the play are Ashley Valley Field in Utah (EUR 25.5 MMBO) and Rangely Field in Colorado (EUR 955 MMBO, 706 BCFG). Ashley Valley produces from about 4,000 feet and Rangely from 5,500 to more than 6,000 feet. The play depths for undiscovered accumulations range from 6,000 to 12,000 feet. The play below 8,000 feet is relatively unexplored by drilling, but is

Analog Example: Rangely

Figures: UO-18, 19, 32, 33

Location: Producing formations: Other significant shows: Lithology: Type of drive: Net pay thickness: Porosity: Permeability: Estimated ultimate recovery: Other major analog fields: Rio Blanco County, Colorado, east of Reservation Weber Sandstone None Sandstone Combination 275 feet 15% 25 mD 904 MMBO Ashley Valley, Thornburg

41o

112 o

111 o

110 o

109 o

108 o

107 o

stone and carbonate. The sandstones have good reservoir quality at shallow depths (<8,000 feet). The carbonates are expected to be porous at least as deep as 12,000 feet. The shallow sandstones (Weber Sandstone) have about 11-14 percent porosity in the only two discovered fields in the play.

Source rocks: The source rocks for the discovered oil fields are not

Salt Lake City

WEBER SANDSTONE WEBER SANDSTONE

Vernal Craig

FRONT RANGE UPLIFT

Gor e

40 o

UTAH COLORADO

known, but the Park City (Phosphoria) Formation was probably the source, requiring long-range migration. Some local Pennsylvanian marine shales may also be a source.

Timing and migration: The hydrocarbons must have migrated pri-

OQUIRRH GROUP

fau lt

n zo

or to Tertiary tectonism, so generation was probably during the Upper Cretaceous.

Exploration status and resource potential: Only two fields have

MAROON FORMATION

e

MAROON FORMATION

Glenwood Springs

Price

Garm

been found in the province, both of which are related to anticlinal closures, and both of which produce oil. The play is for oil with associated gas, but it is possible that some gas fields of less than minimum size (6 BCFG) may also be found. Several Pennsylvanian sandstone and carbonate reservoirs produce on closures just outside the province in the Maudlin Gulch Field area (Danforth Hills Anticline).

Un

esa

fault

FRYINGPAN MEMBER

zone Grand Junction

PAKOON o DOLOMITE 39

Salina

ELEPHANT CANYON FORMATION

CUTLER FORMATION

Green River fa u lt z o

co mp ah gr e

loessite SAWATCH UPLIFT

UNCOMPAHGRE

ne

UPLIFT

Highland area of high to moderate relief Highland area of low to moderate relief Alluvial fan, alluvial plain, delta plain Eolian dune field

Sabkha, playa, restricted shallowmarine setting Shallow- or nearshore-marine sand-rich environment Offshore-marine sand-rich environment Carbonate shelf, platform, or reef

0 0

30 mi 50 km

60 mi 100 km

Figure UO-32. Map showing the Early Wolfcampian paleogeography of the Uinta-Piceance Basin Region during maximum transgression (modified after Johnson et al., 1992).

UINTAH AND OURAY INDIAN RESERVATION

UTAH

CONVENTIONAL PLAY TYPE:

Permian-Pennsylvanian Sandstones and Carbonates Play

15

Era System

Series

Leonardian

Eastern Uinta Basin

Park City Fm

Piceance Basin

Park City Fm

PLAY TYPE 5 BASIN MARGIN SUBTHRUSTS PLAY (HYPOTHETICAL) This play is primarily for closures beneath high- to low-angle thrusts. Figure UO-3 shows some of the flanking thrusts present along the northern to eastern part of the province. The play is hypothetical, and both oil and gas should be present. The only nearby analog is the Tepee Flats Field in the eastern Wind River Basin-Casper Arch area. Here, thick, unfractured Cretaceous marine shale provides a seal for an oil and gas accumulation in the Upper Cretaceous Frontier Formation. Reservoirs: The reservoirs for this play range in age from Paleozoic to Tertiary. Reservoir quality may be poor, especially for prospects deeper than 12,000 feet. The Mississippian carbonates are expected to be porous in most parts of the play. Source rocks: The source rocks are within the subthrust section. Possible source

PERMIAN

rocks containing more than 1 percent total organic carbon (TOC) are found in the Lower Tertiary, Upper Cretaceous, and Pennsylvanian Belden Shale (FIGURE UO-33). The Jurassic Curtis Formation may be a local source bed. Timing and migration: The timing is uncertain, but most of the thrusting took place during the Laramide Orogeny. Traps: Traps are most likely structural and structural-stratigraphic (FIGURES UO-34 and UO-35). Play depths should range from 5,000 feet to as much as 25,000 feet. Exploration status and resource potential: The play is almost unexplored by drilling and only moderately explored by seismic mapping. Based on the abundant fields near the thrusts in the Uinta Basin, a median field size of 2 MMBO and 15 BCF of non-associated gas, and a maximum field size of approximately 50 MMBO and 150 BCFG are estimated for this play.

Maroon Fm

Wolfcampian

Weber Ss

Weber Ss

Schoolhouse Tongue

Maroon Fm

PALEOZOIC

Virgilian

?

PENNSYLVANIAN

Morrison Fm

Weber Ss

Weber Ss

Missourian

?

Maroon Fm

Desmoinesian

Morgan Fm

Mintum Fm

Atokan

Round Valley Ls

Morgan Fm

A

Belden Sh

Morrowan

Figure UO-33. Nomenclature and correlation for the Weber Sandstone in the East Uinta and Piceance Basins. Unconformities indicated by white patches (modified after Hemborg, 1993).

WEST

Evanston Fm (Te) Wasatch Fm (Tw) 1 Pineview

Pineview Field

1 Newton Sheep 3-3 UPRR 2-1 Bingham 4-10S 2-5 Bingham, 3-9 UPRR 2-1 A 3-2 UPRR

A'

EAST

+8000'

R7E

Evanston Fm (Ke)

Kk

32

Oil-Water contact (-3415') -3800 -3600 -3400 -3200 -3000 -2800

35

T 3 N

r Fm (K Frontie

Aspen Sh (Ka

f)

Tw Was -Tf Fow atch kes?

+6000'

Te

+4000'

Te Ke

)

Ke

Jsp

+2000'

Kk Kk Kk

Kelvin F

m (Kk)

Sea level

Jsp

0 80 00 -3 -36

A

5

0 -260 400 -2

A'

T 2 N

/Preu Stump

ss Ss

(Jsp)

Jsp

)

-2000'

N

8

Dry Hole Twin Creek completion

-30 -32 00 -34 00 0 -36 0 00 -38 00

-3

-3 -320 40 0 0

-28

00

0 00

e Twin Cre

k Ls (Jtc

Oil Water

-4000'

Nugget S

Ankareh

s (Jn)

)

thru st

11

Oil-Water contact (-3415')

Fm (TR a

R

Hilliard Sh (Kh)

-6000'

s (T Thaynes L

m rF

t)

Absar

oka

0 0 1km

1 mi

Twin Creek and Nugget completion Nugget completion

-8000'

Figure UO-34. Typical geometry of a shallow east-trending structure, Pineview Nugget Reservoir, Summit County, Utah (not on reservation). Gas is trapped in an asymmetrical thrusted anticline in the hanging wall of the Absaroka Thrust system. Structure contour map of the top of the Nugget Sandstone (modified after Hjellming, 1993).

ve Ri ar br) Be (K

Ka

Frontier Fm (Kf)

-10000'

Woodside Sh (TR w)

B

CONVENTIONAL PLAY:

Figure UO-35. Cross section through the reservoir. Line of section shown in Figure UO-34 (modified after Hjellming, 1993).

UINTAH AND OURAY INDIAN RESERVATION

UTAH

Basin Margin Subthrusts Play (Hypothetical)

16

DEFINITION: Unconventional Plays Unconventional Play- A broad class of hydrocarbon deposits of a type (such as gas in "tight" sandstones, gas shales, and coal-bed gas) that historically has not been produced using traditional development practices. Such accumulations include most continuous-type depos its.

BE

tural flexures is considered quite high, perhaps more than 50 percent; also, there is high potential for finding many areas of small produc tion, and perhaps as many as 10 larger fields (Table 1).

112 o 41o

LT

111 o

110 o WYOMING

109 o

108 o SAND WASH BASIN

Location:

Cretaceous Self-Sourced Fractured Shales Play (Hypothetical)

Oil is produced from fractured Upper Cretaceous Mancos Shale and its equivalents. The best fracturing occurs in brittle siltstones, carbo nates, and calcareous shales. The play outline is based by the U.S.G.S. on the known occur rence of production and the tectonic features associated with known and suspected potential. In the play, the best open fractures occur at the maximum flexure on anticlines or monoclines. Fractures also produce well where shear zones or faults occur. The play boundary is fairly easy to define except in the area between Rangely and the Axial Uplift, where proprietary seismic data indicate the presence of several subsurface thrusts, including thrusts associated with the White River Field structure.

Reservoirs: The reservoirs are open fractures in brittle siltstones, carbonates, and calcareous and siliceous shales. The producing inter vals vary from 10 feet to more than 50 feet thick. The fracturing is highly variable, and one well in the play has produced over 1 MMBO. Source rocks: The enclosing marine shales are the source rocks. The richness varies from about one percent to more than four percent TOC, based on unpublished information. Timing and migration: The oil was probably generated in the Late

Producing formations: Other significant shows: Lithology: Type of drive: Net pay thickness: Porosity: Permeability:

Rio Blanco County, Colorado west of Reservation Mancos, Mancos (B) Shale Morapos Formation Sandstone Pressure depletion and water drive 30-250 feet 2-20% 0.01-100 mD

OROGENIC

Analog Example: Greater Douglas Creek FIGURES UO-13, UO-14

A UINT

UPLIFT

40o

PI

UINTA BASIN

CE

River

NB SC

C

AN

R

EE

CE

K

OK BO

WAS ATC H

SI BA

AU

SEVIER

CL IF FS

N

TIGHT GAS UINTA TERTIARY EAST PLAY

39o

This play is based on well-established gas production from the Uteland Butte, Chapita, and Buck Canyon zones of the Tertiary Wasatch Formation. Updip to the south and east, the play limit is based on an increase in reservoir quality and a change to mostly conventional res ervoirs that have gas-water contacts, which are included in the Uinta Tertiary Oil and Gas Play. Downdip to the north, the play boundary is defined as the point where it becomes predominantly an oil play and is included in Play Type 1. The western limit is along the Green River drainage, where the play becomes higher risk and has been as sessed separately by the U.S.G.S. as Tight Gas Uinta Tertiary West Play (Play Type 8). The overall Wasatch tight gas plays (7 and 8) are based on vitrinite reflectance (Ro) levels in the underlying Creta ceous Mesaverde Group. Rice and others (1992) and Fouch and oth ers (1992) showed that Wasatch gas has migrated upward from the Mesaverde Group and that the play occurs between the basal Mesaverde Ro limits at 1.1-1.5 percent.

Reservoirs: Reservoir rocks are generally medium- to fine-grained

PLATE

SA N SW RAF EL AE L L

HENRY MOUNTAINS 38o

LE RC FS CI IF FT CL PLI U

UN CO M PA HG RE UP LI FT

Green

Tertiary during maximum burial.

Traps: The traps are formed by the enclosing unfractured, more

plastic shale, which contains less silt and carbonate than the brittle facies. The largest accumulation in the play is found in Rangely Field (EUR 14 MMBO). The highest concentration of oil wells pro ducing from the Mancos Shale at Rangely is along the south flank of the structure at the point of maximum flexure.

Exploration Status and Resource Potential: The play is moderate

0 0

30 mi 50 km

60 mi 100 km

ly well explored by vertical wells but nearly unexplored by slant- and horizontal-hole drilling. The U.S.G.S. assumed a low success ratio for the overall play area. Although this play is classified as a continuous-type play (e.g., tight gas), production should be localized by in dividual fractured structures and fracture trends. EUR estimates per well are extremely variable and, although the play is treated as a continuous-type occurrence, the U.S.G.S also simulat ed individual undiscovered fields or "sweet spots" within it to assist in assessment. On this basis, the success ratio in well-mapped struc

feldspathic litharenites and litharenites deposited primarily in fluvial environments. They are interbedded with mudstones, siltstones, shales, and some coal. Porosity ranges from less than 5 percent to more than 9 percent. The reservoirs range in depth from about 3,000 feet to about 10,500 feet, having a median depth of 6,400 feet.

Source rocks: The predominant source of the gas is in the underly

EXPLANATION

Tertiary volcanic and intrusive rocks Tertiary sedimentary rocks Precambrian sedimentary rocks Precambrian metamorphic rocks Precambrian intrusive rocks

Contact Fault Thrust fault Gas well that provided core samples: NB, Natural Buttes field SC, Southman Canyon field

ing Mesaverde Group (Fouch and others, 1992; Nuccio and others, 1992; Rice and others, 1992).

Figure UO-36. Generalized geologic map of the Uinta Basin Province showing location of cored wells (modified after Pitman et al., 1986)

UNITAH AND OURAY INDIAN RESERVATION

UTAH

UTAH COLORADO

UNCONVENTIONAL PLAY TYPE:

Cretaceous Self-Sourced Fractured Shales Play (Hypothetical)

17

Play 8: TIGHT GAS UINTA TERTIARY WEST PLAY

(HYPOTHETICAL) This play is the western extension of Tight Gas Uinta Tertiary East Play (Play Type 7) and is separated from Play 7 along the Green Riv er drainage. Although the river is a surface feature, it more or less coincides with a westward decrease in drilling activity and reservoir quality. It is higher risk than Play 7 and, on this basis, it was decided by the U.S.G.S to use separate assessment parameters.

Reservoirs: This play draws on the same reservoirs as Play 7, yet porosities are somewhat lower here, ranging from less than 4 percent to about 8 percent in reservoir sandstones. The play depths range from about 4,500 feet to 11,000 feet, with a median depth of 7,500 feet. Source rocks: The underlying Mesaverde Group is the gas source. The play limits approximately coincide with maturation levels of Ro 1.1-1.5 percent in gas-prone source beds in the basal part of the Me saverde Group. Timing and migration: Gas generation began in the Late Tertiary

Play 9: BASIN FLANK UINTA MESAVERDE PLAY

(HYPOTHETICAL)

This play is based on the widespread occurrence of tight, gas-saturated continental and marginal marine sandstone. The south, east, and west limits of the play are based on thermal maturation levels in the basal part of the Mesaverde Group. The reservoirs grade updip into more conventional Mesaverde reservoirs having gas-water contacts (see Up per Cretaceous Conventional Play Type 2). Mesaverde burial depths greater than 15,000 feet designate the downdip (north) play boundary (Fouch and others, 1994).

Reservoirs: The reservoirs are fine- to medium-grained litharenites to feldspathic litharenites, becoming coarser to the west. Most reservoir permeabilities are <0.1 md. Porosities range from <4 percent to >12 percent, averaging about 8 percent (FIGURES UO-11 and UO-12) (Nuccio and others, 1992). Play depth varies from 8,000 feet to 15,000 feet, having a median of 9,500 feet. Source rocks: Source rocks are gas-prone, thermally mature coals,

1890

A

1280

B

1910

1300

Carbonate marker

1930

1320

Wasatch formation (upper part)

DEPTH IN METERS

interval

and may be continuing presently in the Mesaverde in the deeper parts of the basin; however, it is possible that vertical gas migration from the Mesaverde may not be as effective as it is in Play 7.

Traps: Traps are both stratigraphic and diagenetic. Exploration status: There is considerably less drilling activity in this play relative to Play 7. The play is only sparsely to moderately explored by drilling.

Tuscher formation

carbonaceous shales, and mudstones of the Mesaverde Group (FIG URES UO-11 and UO-12).

Timing and migration: Gas generation began in the Tertiary and may

1950

1340

be continuing to the present in the deeper parts of the play. The basal Mesaverde has a thermal maturity greater than Ro 1.1 percent.

interval

Traps: Traps are both stratigraphic and diagenetic. Exploration status: The play is essentially unexplored due to depth, economics, poor reservoir quality, and the fact that it is mostly overlain by oil- and gas-producing rocks of the Tertiary Green River Formation.

1990 1 10 100

1380 1 10 100

RESISTIVITY,

OHM-M 2/M

Figure UO-37. Electric log profile of cored wells (modified after Pitman et al., 1986).

UINTAH AND OURAY INDIAN RESERVATION

UTAH

Cored

1970

Cored

1360

Unconventional Play 8: Tight Gas Uinta Tertiary East and West Plays 18

DEEP SYNCLINAL UINTA MESAVERDE PLAY (HYPOTHETICAL) This play is based on the expected occurrence of gas-saturated, tight Mesaverde sandstones at depths greater than 15,000 feet. The limits of the play are based on depth and reservoir quality. This play bor ders Play 9 and involves the same suite of rocks.

Reservoirs: Reservoir rocks are sandstones interbedded with mud

Source rocks: Gas-prone organic material interbedded with sandstone

has generated large volumes of gas.

Salt Lake City

111o

110o

109o

108o

Timing and migration: Gas generation commenced in the Tertiary,

Lake Mtns

and may be continuing at the present time. The thermal maturity of

the Mesaverde is in excess of Ro 1.5 percent, and the deeper rocks

exhibit >Ro 2.0 percent.

Traps: Traps are both stratigraphic and diagenetic.

40o

UINTA

H TC SA S WA MTN

MOUNTAINS

Vernal

Oil field

Gas field Greater Red Wash field

B'

Greater AltamontBluebell Duchesne field

A

Roosevelt

PLA TEA U

PRICE CANYON

Dou

Exploration status: The play is not well explored, due to the fact

stones, siltstones, shales, and some coals. Porosity is generally lower that primary interest in the area is in the overlying Tertiary reservoirs.

than in Play 9, and although there is almost no drilling, the U.S.G.S. expects porosity to be <8 percent to about 3 percent, having a median of 5-6 percent (Table 1). Reservoir depths are >15,000 feet, as deep as 25,000 ft, and have a median of 20,000 feet (FIGURES UO-42 through UO-44).

Utah Lake B

BOOK

Pariette Bench field Island field

Ri

ve

r

WHITE

Rangely

A'

Natural Buttes field

gla s Arc Creek h

CL

Gr ee

Price

IF

FS

UINTA BASIN

PICEANCE CREEK BASIN

Parachute Creek

RIVER

n

UPLIFT

Rifle Glenwood Springs

Sunnyside Tar Sand

BO OK

FS IF CL

WASATCH

39o

FA E

CL

A

AltamontBluebell

1 2 3 4 5

A'

Pariette Bench

6 7

PL

IFT

LU

IF

FS

SA

Island

8

0 0 25 20

50 Kilometers 40 Miles

Co

l

a or

do

Ri

ve

r

UTAH COLORADO

Green River

N

RA

BOOK

Grand Junction

MO ELK UNT AIN S

Approximate outline of Uinta and Piceance Creek Basins

U N R G H PA T M IF O L C UP E

0.50% Rm

0.75% Rm 1.10% Rm

Figure UO-38. Index map of the Uinta and Piceance Creek Basins area showing location of cross-sections A-A' (Figure UO-43) and B-B' (Figure UO-44) (modified after Nuccio et al., 1992).

Eocene Paleocene

Mesaverde Group

Figure UO-40. Cross section B-B', which extends from outcrops on the southwest flank of the Uinta Basin through the Altamont-Bluebell Field. Producing intervals for some of the basin's fields are projected into the line of section. See Figure UO-42 for line of section (modified after Nuccio et al., 1992).

B

Sunnyside Tar Sand Natural Buttes Island

Cr Ter ti eta ary ce ou s

B'

Altamont - Bluebell fields (A-B) Pariette Bench Redwash Field (RW) Duchesne, Monument Horseshoe Bend 9000 6000 3000 Uinta Fm. SL -3000

2.0% Rm

No r th

Co

Duchesne River Fm.

lton

Ho rn

Tertiary

Green River Fm. Open Lake; Type I Green River Fm. Marginal Lacustrine Mixed Lake and Fluvial Type I, II, and III Colton and Wasatch Fms. Alluvial; Type III Tertiary and U. Cretaceous North Horn Fm. Alluvial and minor lake Type I, II, and III Gas Well Oil Well Dry Hole Oil producing zone Gas producing zone

Upper Cretaceous

Nonmarine Tuscher and Farrer Fms. Braided and meandering fluvial; Type III Neslen Fm. Coastal Plain; Type III Marine Sego Sandstone Shore, nearshore Mancos Shale Open marine; Type II and III Buck Tongue of Mancos Shale Castlegate SS and Blackhawk Fm.; Type III; Littoral and shelf 650 ft 0 16 mi

Fm . Fm . (p ar t )

Green River Fm.

Nor th

Hor nF m. (pa r t) &

AB

Wasatch Fm.

BW

Colton Fm.

-6000 -9000

ft 6000

m 2000 1000 4 0 0 5 10 15 20 km 8 12 16 20 mi GAS

Me sav erd e

Gro up

Figure UO-39. Cross section A-A' through the Uinta Basin, Utah, showing types of kerogen found at various stratigraphic intervals, levels of thermal maturity (Rm lines), and associated hydrocarbon producing zones. See Figure UO 42 for line of section (modified after Nuccio et al., 1992).

3000

Paleozoic-Mesozoic rock OIL & GAS

UINTAH AND OURAY INDIAN RESERVATION

UTAH

UNCONVENTIONAL PLAY:

Deep Synclinal Uinta Mesaverde Play (Hypothetical) 19

REFERENCES

Anderson, R. C., 1995, ed., The Oil and Gas Opportunity on Indian Lands: Exploration Policies and Procedures, Bureau of Indian Affairs. Anonymous, 1995, Uintah and Ouray Reservation, in Anderson, Rob ert C., ed., The Oil and Gas Opportunity on Indian Lands: Explo ration Policies and Procedures, 1995 Edition, Bureau of Indian Affairs, p.93-106.

co Bureau of Mines and Mineral Resources, Socorro, New Mex ico, p. 104. Hill, Bradley G., and Bereskin, S. Robert, eds., 1993, Oil and Gas Fields of Utah: Utah Geological Association Publication 22, Salt Lake City, Utah, U.S.A. Hjellming, Carol A., ed., 1993, Atlas of Major Rocky Mountain Gas Reservoirs: New Mexico Bureau of Mines and Mineral Resour ces, Socorro, New Mexico.

County, Utah, in Fouch, T.D., Nuccio, V.F., and Chidsey, T.C., Jr., eds., Hydrocarbon and Mineral Resources of the Uinta Ba sin, Utah and Colorado: Utah Geological Association Guide book 20, Salt Lake City, Utah U.S.A. Pitman, J.K., Anders, D.E., Fouch, T.D., and Nichols, D.J., 1986, Hydrocarbon Potential of Nonmarine Upper Cretaceous and Lower Tertiary Rocks, Eastern Uinta Basin, Utah, in Spencer, Charles W., and Mast, Richard F., eds., Geology of Tight Gas Reservoirs, AAPG Studies in Geology #24. Rice, D.D., Fouch, T.D., and Johnson, R.C., 1992, Influence of source rock type, thermal maturity and migration on composi tion and distribution of natural gases, Uinta Basin, Utah, in Fouch, T.D., Nuccio, V.F., and Chidsey, T.C., Jr., eds., Hydrocar bon and mineral resources of the Uinta Basin, Utah and Colora do: Utah Geological Association Field Symposium, 1992, Guidebook 20, p. 95-109. Spencer, Charles W., and Wilson, Robert J., 1988, Petroleum Geology and Principal Exploration Plays in the Uinta-Piceance-Eagle Ba sins Province, Utah and Colorado: U.S. Geological Survey Open-File Report 88-450-G. Tremain, Carol M., 1993, Mesaverde Group, in Hjellming, Carol A., ed., Atlas of Major Rocky Mountain Gas Reservoirs: New Mex ico Bureau of Mines and Mineral Resources, Socorro, New Mexico, p. 97-98.

Cashion, W.B., 1992, Oil-Shale resources of the Uintah and Ouray In Johnson, Samuel Y., Chan, Marjorie A., and Konopka, Edith A.,1992, Pennsylvanian and Early Permian Paleogeography of the Uintadian Reservation, Uinta Basin, Utah, in Fouch, T.D., Nuccio, V.F., Piceance Basin Region, Northwestern Colorado and Northeast and Chidsey, T.C., Jr., ed., Hydrocarbon and Mineral Resources ern Utah: U.S. Geological Survey Bulletin 1787-CC. of the Uinta Basin, Utah and Colorado: Utah Geological Associ ation Guidebook 20, Salt Lake City, Utah U.S.A., Utah Geologi Moretti, George, Jr., Lipinski, Paul, Gustafson and Slaughter, Arville, cal Association. 1992, Dakota Sandstone deposition and trap door structure of Hells Hole Field , eastern Uinta basin, Utah and Colorado, in Chidsey, Thomas C. Jr., 1993a, Uinta Basin [UN] Plays-Overview, in Fouch, T.D., Nuccio, V.F., and Chidsey, T.C., Jr., eds., Hydrocar Hjellming, Carol A., ed., Atlas of Major Rocky Mountain Gas bon and Mineral Resources of the Uinta Basin, Utah and Reservoirs: New Mexico Bureau of Mines and Mineral Resour Colorado: Utah Geological Association Guidebook 20, Salt ces, Socorro, New Mexico, p. 83. Lake City, Utah U.S.A. Chidsey, Thomas C. Jr., 1993b, Green River Formation, in Hjellming, Morgan, Craig D., 1993a, Uinta Formation, in Hjellming, Carol A., Carol A., ed., Atlas of Major Rocky Mountain Gas Reservoirs: ed., Atlas of Major Rocky Mountain Gas Reservoirs: New Mex New Mexico Bureau of Mines and Mineral Resources, Socorro, ico Bureau of Mines and Mineral Resources, Socorro, New New Mexico, p. 85-86. Mexico, p. 84. Chidsey, Thomas C. Jr., 1993c, Wasatch Formation, in Hjellming, Morgan, Craig D., 1993b, Entrada Sandstone, in Hjellming, Carol A., Carol A., ed., Atlas of Major Rocky Mountain Gas Reservoirs: ed., Atlas of Major Rocky Mountain Gas Reservoirs: New Mex New Mexico Bureau of Mines and Mineral Resources, Socorro, ico Bureau of Mines and Mineral Resources, Socorro, New New Mexico, p. 87. Mexico, p. 104. Fouch, Thomas D., Nuccio, Vito F., Osmond, John C., Macmillan, Noe, David C., 1993a, Mancos Marine Sandstones, in Hjellming, Logan, Cashion, William B., and Wandrey, Craig J., 1992, Oil Carol A., ed., Atlas of Major Rocky Mountain Gas Reservoirs: and gas in uppermost Cretaceous and Tertiary rock, Uinta Basin, New Mexico Bureau of Mines and Mineral Resources, Socorro, Utah, in Fouch, T.D., Nuccio, V.F., and Chidsey, T.D. Jr.ed., Hy New Mexico, p. 99-100. drocarbon and Mineral Resources of the Uinta Basin, Utah and Colorado: U.S. Geological Association Guidebook 20, Salt Lake Noe, David C., 1993b, Dakota Sandstone, Cedar Mountain Forma City, Utah U.S.A. tion, and Morrison Formation, in Hjellming, Carol A., ed., Atlas of Major Rocky Mountain Gas Reservoirs: New Mexico Bureau Fouch, T.D., Schmoker, J.W., Boone, L.E., Wandrey, C.J., Crovelli, of Mines and Mineral Resources, Socorro, New Mexico, p. 101 R.A., and Butler, W.C., 1994, Nonassociated gas resources in 102. low-permeability sandstone reservoirs, lower Tertiary Wasatch Formation, and Upper Cretaceous Mesaverde Group, Uinta Ba Nuccio, V.F., J.W. Schmoker, and T.D. Fouch, 1992, Thermal maturi sin, Utah: U.S. Geological Survey Open-File Report (in press). ty, porosity, and lithofacies relationships applied to gas genera tion and production in Cretaceous and Tertiary low permeability Gautier, Donald L., Dolton, Gordon L., Takahashi, Kenneth I., and (tight) sandstones, Uinta Basin, Utah, in Fouch, T.D., Nuccio, Varnes, Katherine L., eds., 1995 National Assessment of United V.F., and Chidsey,T.C., Jr., eds., Hydrocarbon and mineral re States Oil and Gas resources- Results, Methodology, and Sup sources of the Uinta Basin, Utah and Colorado: Utah Geologi porting Data: U.S. Geological Survey Digital Data Series DDS cal Association Field Symposium, 1992, Guidebook 20, p. 77 30 1995. 93. Hemborg, H. Thomas, 1993, Weber Sandstone, in Hjellming, Carol A., ed., Atlas of Major Rocky Mountain Gas Reservoirs: New Mexi Osmond, John C., 1992, Greater Natural Buttes gas field, Uintah

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