Tensleep TZ/ROZ Study, Bighorn Basin

A Revolutionary Concept on Oil Recovery

Peigui Yin Shaochang Wo

Sharon Verdun-Reyes Matthew Johnson

Glen Murrell David Mohrbacher

July 14, 2011

ARI, 2006

Main Pay Zone (MPZ), Transition Zone (TZ) & Residual Oil Zone (ROZ)

Jennings, 1987

0 20 40 60 80 100

So (%)

0

40

80

120

160

200

Thic

kne

ss (

ft)

MP

Z TZ

Pe

rfo

rati

on

RO

Z (1

00

% w

ater

Pro

du

ction

)

Bighorn Basin Tensleep

Tensleep Sandstone

Bighorn Basin

Structural Contour Map of Tensleep Sandstone

Zapp, 1953

Tensleep Sandstone Potentiometric Map

Bredehoeft et al., 1992

Topics

• Tensleep TZ/ROZ in Bighorn Basin.

• Mechanisms for Thick TZ/ROZ.

• Active ROZ CO2-EOR Production in Permian Basin.

• Comments and Future Study.

Tensleep TZ/ROZ in Bighorn Basin

• Below main pay zone within existing reservoirs.

• Around existing reservoirs.

• Non-productive structures (green fields).

• Oil Properties are similar in TZ/ROZ and MPZ

0 0.05 0.1 0.15 0.2 0.25

Porosity0 0.05 0.1 0.15 0.2 0.25

Porosity

0 20 40 60 80 100

1217

1196

1175

1154

1133

1112

1091

1070

So

(%)

Ele

va

tio

n (

ft)

0 20 40 60 80 100

-194

-219

-244

-272

-297

-322

-347

-372.5

So (%)

Ele

va

tio

n (

ft)

0 20 40 60 80 100

1223

1204

1185

1166

1147

1128

1109

1090

So (%)

Ele

vati

on

(ft

)

Below Main Pay Zone within Existing Reservoirs.

0 0.05 0.1 0.15 0.2 0.25

Porosity

A B C

Thick permeable intervals with high So not produced during primary and secondary production

Total Tensleep thickness: 180 ft Average perforation thickness: 47 ft

Perforation Interval in a Tensleep Reservoir

0 20 40 60 80 100

-194

-219

-244

-272

-297

-322

-347

-372.5

So (%)

Ele

va

tio

n (

ft)

0 0.05 0.1 0.15 0.2 0.25

Porosity

0 20 40 60 80 100

55.5

40

24.5

9

-6.5

-22

-37.5

-53

So (%)

Ele

vati

on

(ft

)

0 0.05 0.1 0.15 0.2 0.25

Porosity

0 20 40 60 80 100

787.5

769.5

751.5

733.5

715.5

697.5

679.5

661.5

So (%)

Ele

vati

on

(ft

)

0 20 40 60 80 100

879.5

852

824.5

797

769.5

742

714.5

687

So (%)

Ele

vati

on

(ft

)

0 0.05 0.1 0.15 0.2 0.25

Porosity

Non-commercial Wells around Existing Reservoirs

Wells with high So, but not economically viable by primary and secondary recovery techniques

320410 C L Zwemer 1 57N-97W-21 Bighorn Basin

Core Photos, Non-productive Well

0 20 40 60 80 100

44

32

21

-10

-21

-31

-41

-51

320410

So

Ele

va

tio

n (

ft)

306499

320139

306465

320410

2921388

2920992

0 20 40 60 80 100

40

29

15

-11

-21

-30

-39

-48

320410

So (%)

Ele

vati

on

(ft

)

2920043

0 20 40 60 80 100

-430.5

-433.5

-436.5

-439.5

-442.5

-446.5

-452.5

-458.5

2920043

So (%)

Ele

va

tio

n (

ft)

0 20 40 60 80 100

-16

-32

-44

-51

-70.8

-77

-84

-95

320139

So (%)

Ele

vati

on

(ft

)

0 20 40 60 80 100

837

834

831

828

825

822

819

816

813

306499

So (%)

Ele

vati

on

(ft

)

0 20 40 60 80 100

1448

1444

1440

1436

1432

1428

1419

1415

2921388

So (%)

Ele

vati

on

(ft

)

0 20 40 60 80 100

1127

1105

1083

1061

1039

1016

994

972

2920992

So (%)

Ele

vati

on

(ft

)

0 20 40 60 80 100

-490

-500

-510

-520

-530

-540

-566

-576

306465

So (%)

Ele

vati

on

(ft

)

Oil Saturation Obtained from Core Analysis

Traps with Oil Saturation not High Enough for Primary and Secondary Recovery (Green Fields)

0 20 40 60 80 100

1125

1113

1102

1089

1078

1065

1054

1042

320762

So

(%)

Ele

vati

on

(ft

)

Well Located in Non-commercial Structure (Green Field)

56

N

96W

1 2 3

10 11 12

0 0.05 0.1 0.15 0.2 0.25

320762

PorosityTectonic information from Ploeg, 1985)

Total thickness of Tensleep Sandstone: 142 ft.

3706-3750 ft, sandstone, even light brown heavy oil stain, free oil droplets in samples and within pore spaces, even dark yellow fluorescence, strong petroleum odor. 10-12% log porosity. Perf: 3718-3728 ft (10 ft thick). No production, plug & abandon.

Another Green Field Example

Tectonic information from Ploeg, 1985)

3734

3754

3774

3794

3814

3834

3854

3874

3894

3914

0 20 40 60 80 100

Produce 75 bbls/day with 70% water cut constant over one year

So (%)

De

pth

(ft

)

Perforatio

n

Data from Aufricht, 1965

Example Showing So, Perforation, and Water Cut

Tensleep Reservoirs Aufricht, 1965

• Oil-water transition zone of several hundred feet in thickness.

• Transition zone with So of 80% still produce with extremely high water cuts.

• OOIP approaching 1000 barrels per acre foot may produce at water cuts greater than 95%.

• Intervals with Sw of 15 to 30% are commercially interest for primary and secondary recovery techniques.

ROZ CO2-EOR Potential

• ARI estimated TZ/ROZ OIP in 13 Bighorn Basin Tensleep Productive reservoirs: 4.4 BBbls – These 13 Tensleep reservoirs with cumulative production: from 345.4 to 6.2 MMBbls

13 Bighorn Basin Tensleep Reservoirs

MPZ

OOIP

(BBbls)

MPZ

Remaining OIP

(BBbls)

TZ/ROZ

OIP

(BBbls)

Total Reserve

for CO2-EOR

(BBbls)

1. CO2-miscible fields: 8

2. CO2-immiscible fields: 5

4.5 3.1 4.4 7.5

CO2-EOR recovery: 11% 0.34 0.48 0.82

CO2-EOR recovery: 30% 0.93 1.32 2.25

<

< <

GC Analysis

Reservoir Oil From Non-productive Wells

Oil Properties are similar in TZ/ROZ and MPZ

MPZ

TZ/ROZ

TZ/ROZ

TZ/ROZ

Brown Field

Green Field

Green Field

A Revolutionary Development for Production and Exploration

Primary & secondary

CO2-EOR

CO2-EOR

CO2-EOR

0 20 40 60 80 100

So (%)

0

40

80

120

160

200

Thic

kne

ss (

ft)

MPZ

TZ

Original

CO

2 -EOR

Po

ten

tial CO2-EOR Potential

0 20 40 60 80 100

So (%)

0

40

80

120

160

200

Thic

kne

ss (

ft)

MPZ

TZ

Current

Pe

rfo

rati

on

Pe

rfo

rati

on

ROZ (100% water Production)

ROZ (100% water Production)

?

Mechanisms for Thick TZ/ROZ

• Tertiary oil migration from stratigraphic to structural traps creates rich TZ/ROZ.

• Heavy oil reservoirs favor to generate thick TZ/ROZ.

• Reservoir heterogeneity retards gravity separation of oil from water, resulting a thick TZ with uneven oil saturation.

• Strong hydrodynamic flow aids to generate rich TZ/ROZ.

Late Permian Paleogeographic Map (Phosphoria Period)

Wyoming

Idaho

Southeast Idaho

Central Wyoming

Miller et al., 1991

HC source rock region

Oil Migrated into Tensleep Through Unconformity

Modified from Stone, 1967

Oil Accumulated in Stratigraphic Traps before Laramide Orogeny

Folds and Thrust Faults Generated during Laramide Orogeny

A

B

Zapp, 1953

9500’ thick

Post-Tensleep Strata

Re-Migration of Oil Creating Rich TZ/ROZ

Bighorn Mountain

Bighorn Basin

Oil

Oil

Oil

TOZ/ROZ

TOZ/ROZ

TOZ/ROZ

A B

Meteoric water Flushing

Oil flushed downdip or escaped updip

Tensleep outcropped

After Laramide (Paleocene-Eocene)

Oil migrated and accumulated in structure top

Trapper Canyon Tar Sands

East Flank of Bighorn Basin An Example of Present Hydrocarbon Distribution

Map form Ver Ploeg, 1985

Madison

Big Horn

Gallatin

& Tensleep

Phosphoria

Reservoir with Tilted OWC

320767

Perforation Bottom Deepening from NE to SW

After Lawson and Smith (1966)

Reservoir with Horizontal OWC

Oil-Water-Contact

Oil

TZ/ROZ

Tensleep

Madison

Big Horn

Gallatin

& Tensleep

Phosphoria

Amsden

Stratigraphic Trap

Oil

TZ/ROZ

Mechanism of Secondary Hydrocarbon Migration and Entrapment

• Driving force: buoyancy caused by difference of density between hydrocarbon and water.

• Resistant force: capillary pressure. – Radius of pore throats.

– Hydrocarbon-water interfacial tension.

– Wettability of reservoir rocks.

θ

R

R: Radius of pore throat. θ: contact angle of oil and water against the solid.

From Schowalter, 1979

HC

Water

16

% S

w

80

% S

w

Water Saturation Percent Pore Space

He

igh

t (f

t)

Reservoir A

Reservoir B

Reservoir C

Pc = h(rwg – rog)

Thickness Difference Due to Oil Density

16% Sw 80% Sw

Res

erv

oir

A

(1

4 A

PI)

Res

erv

oir

B

(2

3 A

PI)

Res

ervo

ir C

(34

AP

I)

From Aufricht, 1965

16

% S

w 16

% S

w 80

% S

w

80

% S

w

50

0 f

t

10

0 f

t

50

ft

Heavy Oil Reservoirs with Thick TZ/ROZ

TZ

Water Saturation, Percent Pore Space

Wat

er

Cu

t, P

erc

en

t

Reservoir A

Reservoir B

Reservoir C

Water Cut as Functions of Relative Permeability and Oil Viscosity

Reservoir A 14 API

500 cp

Reservoir B 23 API

10 cp

Reservoir C 34 API

1 cp

From Aufricht, 1965

𝑾𝒂𝒕𝒆𝒓 𝒄𝒖𝒕, % = 𝟏𝟎𝟎 × 𝒇𝒘 =𝟏𝟎𝟎

𝟏 +𝝁𝒘𝝁𝒐

𝒌𝒐𝒌𝒘

70% Water Cut

6% water Cut 1% Water Cut

Hydrodynamic Traps Contributed by Bed Thinning, Faulting, or Bending

Levorson, 1966

Pedry, 1975

ACTIVE ROZ CO2-EOR PROJECTS IN PERMIAN

BASIN

GOLDSMITH FIELD (1)

-920

-1300

Sub

sea Elevatio

n (ft)

Goldsmith San Andres Unit Seminole San Andrews Unit

ROZ Oil Saturation

2010 CO2 Flooding Conference

API: 30-50o

Thurmond. 2010

Goldsmith San Andres Unit

Goldsmith San Andres Unit Seminole San Andres Unit

Oil Production Increase by Including ROZ CO2-EOR

Thurmond, 2010 2010 CO2 Flooding Conference

Oil

Oil Cut

ROZ Phase II

ROZ & MPZ Have Consistent Properties in Permian Basin

• Core oil saturation is consistent.

• Reservoir quality is consistent.

• Bulk oil composition is consistent.

• Chemical process behavior is consistent.

Concluded by Thurmond for Goldsmith San Andres Unit, 2010

Ideas and Future Study

• Recognition of thick Tensleep TZ/ROZ in Bighorn Basin. – TZ/ROZ below main pay zone.

– TZ/ROZ around current reservoirs.

– TZ/ROZ in non-commercial structures.

• New discovery of CO2-EOR resources in Bighorn basin. • EOR resources not counted by traditional main pay zones.

• There will be high potential for CO2-EOR, and even a new wave of exploration for EOR targets.

• Further integrate the TZ/ROZ concept in Tensleep reservoirs.

• Evaluation of all non-productive structures (green fields).

• Search for rich TZ/ROZ fairways.

• Estimation of CO2-EOR potential in TZ/ROZ.

• Communication and cooperative with oil companies.

Thanks

?