Basin-Wide Evaluation of the Uppermost Green River

Basin-Wide Evaluation of the Uppermost Green River Formation’s Oil Shale Resource, Uinta Basin, Utah and ColoradoMichael D. Vanden Berg (801-538-5419, [email protected])

Utah Geological Survey, Salt Lake City, Utahgeology.utah.gov

Due to the recent increase in crude oil prices and concerns over diminishing conventional reserves, the Utah Geological Survey has reexamined the Uinta Basin’s oil shale resource, pri-marily in the Mahogany zone of the Green River Formation. We created conversion equations by correlating available Fischer assays with corresponding density and sonic measurements as a way to predict oil yield from geophysical logs. In addition to the core-based Fischer assays obtained from 107 wells drilled specifically for oil shale, 186 oil and gas wells with oil yields calculated from digitized bulk density or sonic logs were used to create a basin-wide picture of the oil shale resource in the Uinta Basin. These widespread data were used to map oil shale thickness and richness and create isopach maps delineating oil yields of 15, 25, 35, and 50 gal-lons of shale oil per ton (GPT) of rock. From these isopach maps, new basin-wide resource numbers were calculated for each richness grade. A continuous interval of oil shale averaging 50 GPT contains an in-place oil resource of 31 billion barrels in a zone ranging up to 20 feet thick. Where the 50 GPT interval is at least 5 feet thick and less than 3000 feet deep, the in-place resource drops to 26 billion barrels. An in-terval averaging 35 GPT, with a maximum thickness of 55 feet, contains an in-place oil re-source of 76 billion barrels. Where this interval is at least 5 feet thick and less than 3000 feet deep, the total in-place resource drops to 61 billion barrels. The 25 GPT zone and the 15 GPT zone contain unconstrained resources of 147 billion barrels and 292 billion barrels, respec-tively. The maximum thickness of 25 GPT rock is about 130 feet, whereas the maximum thickness of 15 GPT rock is about 500 feet. Where these two intervals are at least 5 feet thick and less than 3000 feet deep, the 25 GPT resource drops to 111 billion barrels and the 15 GPT resource drops to 228 billion barrels. After placing several constraints on Utah’s total in-place oil shale resource, we determined that approximately 77 billion barrels of oil could be considered as a potential economic re-source. This estimate is for deposits that are at least 25 GPT; at least 5 feet thick; under less than 3000 feet of cover; not in conflict with current conventional oil and gas resources; and lo-cated only on BLM, state trust, private, and tribal lands.

ABSTRACTABSTRACT

METHODS FOR EVALUATING OIL SHALE RESOURCESMETHODS FOR EVALUATING OIL SHALE RESOURCES

GRAND

UINTAHDUCHESNE

EMERY

CARBON

WASATCH

UTAH

5S

6S

7S

8S

9S

10S

11S

12S

13S

14S

15S

16S

17S

18S

25E24E23E22E21E20E19E1W2W3W4W5W6W7W8W9W 1E

1S

2S

3S

4S

5S

6S

23E22E21E20E19E18E17E16E15E14E

Thickness - 50 GallonsPer Ton (GPT) Interval

Sonic log

Fischer assay

Bulk density log

Overburden contour (ft) - Top of 50 GPT zone

Uinta Basin boundary

County boundary

Township/Range

Road

Note: The northern boundary of the isopach zone is limited by the extent of the data;the southern boundary is delineated by the outcrop of the Mahogany zone.

Wells Having Oil Shale Assay Data

- Salt Lake Base & Meridian- Uinta Special Meridian

Mahogany zone outcrop

County seat

>0-5 ft

5-10 ft

10-15 ft

15-20 ft

1000

2000

3000

4000

5000

6000

7000

8000

9000

2000

3000

4000

5000

6000

700080

00

1000

Vernal

Duchesne

Northern boundary of study area

Thickness

>0-5

5-10

10-15

15-20

Total

Oil Shale Resource - 50 GPT Zone

8.0

14.1

6.4

2.1

30.5

Billion bbls Billion bbls

5.8

12.2

5.7

2.1

25.7

TotalIn-Place

Less than3000 ft deep

Note: Totals may not equal sum of components because ofindependent rounding

Feet

CO

LOR

AD

O

0 10 20 305Miles

0 10 20 305Kilometers

2E

13EScale 1:575,000

Continuous interval averaging Continuous interval averaging 50 GPT

GRAND

UINTAHDUCHESNE

EMERY

CARBON

WASATCH

UTAH

5S

6S

7S

8S

9S

10S

11S

12S

13S

14S

15S

16S

17S

18S


1S

2S

3S

4S

5S

6S

23E22E21E20E19E18E17E16E15E14E


Sonic log

Fischer assay

Bulk density log



County boundary

Township/Range

Road




County seat

>0-5 ft

5-10 ft

10-20 ft

20-30 ft

1000

2000

3000

4000

5000

6000

7000

8000

9000

2000

3000

4000

5000

6000

700080

00

1000

Vernal

Duchesne


CO

LOR

AD

O

0 10 20 305Miles


2E

13EScale 1:575,000

30-40 ft

40-55 ft

Thickness

>0-5

5-10

10-20

20-30

30-40


3.2

8.5

24.3

17.7

14.7


1.7

4.1

19.9

15.3

12.4

TotalIn-Place



Feet

40-55

Total

7.7

76.1

7.7

61.1


Continuous interval averagingContinuous interval averaging 35 GPT

GRAND

UINTAHDUCHESNE

EMERY

CARBON

WASATCH

UTAH

5S

6S

7S

8S

9S

10S

11S

12S

13S

14S

15S

16S

17S

18S


1S

2S

3S

4S

5S

6S

23E22E21E20E19E18E17E16E15E14E


Sonic log

Fischer assay

Bulk density log



County boundary

Township/Range

Road



Mahogany zone outcropCounty seat

>0-5 ft

5-20 ft

20-40 ft

40-60 ft

1000

2000

3000

4000

5000

6000

7000

8000

9000

2000

30004000

5000

6000

70008000

1000

Vernal

Duchesne


CO

LOR

AD

O

0 10 20 305Miles


2E

13EScale 1:575,000

60-80 ft

80-100 ft

100-130 ft

Thickness

>0-5

5-20

20-40

40-60

60-80


1.5

15.1

38.8

31.5

18.7


1.2

7.9

27.1

24.7

14.9

TotalIn-Place



Feet

80-100

100-130

23.4

18.4

19.8

17.0

Total 147.4 112.6


Continuous interval averaging Continuous interval averaging 25 GPT

GRAND

UINTAHDUCHESNE

EMERY

CARBON

WASATCH

UTAH

5S

6S

7S

8S

9S

10S

11S

12S

13S

14S

15S

16S

17S

18S


1S

2S

3S

4S

5S

6S

23E22E21E20E19E18E17E16E15E14E


Sonic log

Fischer assay

Bulk density log



County boundary

Township/Range

Road




County seat

>0-15 ft

15-100 ft

100-200 ft

200-300 ft

1000

2000

3000

4000

5000

6000

7000

8000

9000

2000

30004000

5000

6000

700080

00

1000

Vernal

Duchesne


CO

LOR

AD

O

0 10 20 305Miles


2E

13EScale 1:575,000

300-400 ft

400-500 ft

Thickness

>0-15

15-100

100-200

200-300

300-400


3.4

82.8

72.3

40.8

69.0


2.7

49.2

51.7

32.0

68.8

TotalIn-Place



Feet

400-500

Total

23.9

292.3

23.9

228.3


Continuous interval averaging Continuous interval averaging 15 GPT1.6 2.5Bulk density (g/cm3)

R-8

Mahogany Bed

0 80Oil yield from Fischer assay (GPT)

1900

2000

2100

2200

2300

2400

2500

2600

2700

2800

2900

Dep

th (f

t)

Oil yield (GPT)

2680

2700

2720

2740

2760

2780

2800

0 20 40 60 80

Dep

th (f

t)

2611

2631

2651

2671

2691

2711

2731

Dep

th (f

t)

4304733453 - Oil yield calculated from bulk density logU045 - Oil yield measured by Fischer assay from core

Average GPT of datasets:- Gas well = 21.4 GPT- U045 = 21.7 GPT

Step 1:Step 1: Digitized density and sonic logs from oil shale wells

Step 2:Step 2: Compared digitized density and sonic logs to Fischer assay analyses measured on core

0 20 40 60 80Oil yield from Fischer assay (GPT)

2.4 2.2 2.0 1.8 1.61900

2100

2300

2500

2700

2900

Bulk density (g/cm3)

Dep

th (f

t)R-8

MahoganyZone (R-7)

B-groove

R-6

L-5

R-5

L-4

R-4

A-groove

Uinta Formation

Green RiverFormationEO

CEN

EPA

LEO

CEN

EC

RET

AC

EOU

S

Parachute CreekMember

Wasatch Formation

Mesaverde Group

Douglas Creek Member

0 20 40 60 801850

2050

2250

2450

Oil yield (GPT)

Dep

th (f

t)

0

10

20

30

40

50

60

70

80

1.6 1.8 2.0 2.2 2.4 2.6


y = -85.5x + 213.5R2 = 0.84

Oil

yiel

d fr

om F

isch

er a

ssay

(GPT

)

Step 3:Step 3: Derived equations using a reduced major axes fit relating GPT to the sonic or density logs

1.4 1.6 1.8 2.0 2.2 2.4 2.60

10

20

30

40

50

60

70

80

90

y = -80.894x + 203.996

Reduced major axes fit relating density to shale oil yield

- Data from 8 oil shale wells (R2 ranging from 0.71 to 0.87)

50 70 90 110 130 150

Sonic (ft/sec)

0

10

20

30

40

50

60

70

80

90

y = 0.7656x - 49.237

Reduced major axes fit relating sonic to shale oil yield

- Data from 4 oil shale wells (R2 ranging from 0.64 to 0.77)

Oil

yiel

d fr

om F

isch

er a

ssay

(GPT

)


Oil

yiel

d fr

om F

isch

er a

ssay

(GPT

)

USGS - Coyote Wash 1 well (U044)Uintah County - T9S R23E Sec. 22

Ground truth verses calculated yield from two nearby wells

Step 6:Step 6: Determined maximum thickness of oil shale averaging 15, 25, 35, and 50 GPT

Continuous interval averaging 15 GPT - 426 ft




Step 7:Step 7: Created isopach maps in ArcGIS

Step 8:Step 8: Calculated resource numbers for each richness zone (15, 25, 35, 50 GPT)- Calculated volumes in ArcGIS for each richness zone at several thickness intervals- Used the density of each richness to convert volume to mass - 50 GPT = 1.90 g/cm3

- 35 GPT = 2.09 g/cm3

- 25 GPT = 2.21 g/cm3

- 15 GPT = 2.34 g/cm3

- Used richness (i.e., 50 gallons per ton) to convert mass to barrels

A-Groove

B-Groove

R-6

L-5

R-5

L-4

R-4

R-7 (Mahogany Zone)

Stratigraphy of the Parachute Creek Member of the upper Green River Formation illustrated by bulk density and oil yield plots from the USGS Coyote 1 well (U044). “R” refers to a rich oil shale zone and “L” refers to a lean oil shale zone (stratigraphic nomenclature for oil shale zones derived from Donnell and Blair, 1970 and Cashion and Donnell, 1972).

UPPER GREEN RIVER FORMATION STRATIGRAPHYUPPER GREEN RIVER FORMATION STRATIGRAPHY

DUCHESNE

UINTAH

WASATCH

CARBON

EMERY

GRAND

UTAH

Duchesne RiverWhite River

Green River

Fischer assay from oil shale core - 107 wellsCalculated oil yield from density logs - 167 wellsCalculated oil yield from sonic logs - 19 wells

Step 4:Step 4: Digitized density and sonic logs from oil and gas wells throughout the Uinta Basin

Step 5:Step 5: Calculated oil yield logs for oil and gas wells using derived equations

Wells with Fischer assays from core are mostly clustered near the Mahogany zone outcrop in Uintah County. These ground truth data were supplemented with oil yield data calculated from den-sity and sonic logs from oil and gas wells located throughout the basin. Since density logs display a better cor-relation with oil yield, preference was given to these logs.

Mahoganyzoneoutcrop

Uinta Basin

USGS - Coyote Wash 1 well (U044)Uintah County - T9S R23E Sec. 22

Outcrop of the Green River Formation along the White River, Uintah County, Utah.

Utah oil shale sample from the White River mine.

Outcrop of the upper Green River Formation, Parachute Creek Member, Hell’s Hole Canyon, eastern Uintah County, Utah.

Mahogany Zone

RESULTS - NEW OIL SHALE RESOURCE ESTIMATES CONSTRAINED BY GRADERESULTS - NEW OIL SHALE RESOURCE ESTIMATES CONSTRAINED BY GRADETotal in-place resource Total in-place resource 30.5 billion barrels Total in-place resource Total in-place resource 76.1 billion barrels

Total in-place resource Total in-place resource 292.3 billion barrelsTotal in-place resource Total in-place resource 147.4 billion barrels

AAPG 2009 - Denver, UT - Panel 1

Oil shale mined from the White River mine in eastern Uintah County, Utah

Documents

Basin-Wide Evaluation of the Uppermost Green River