U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2012–3148 

January 2013

Assessment of Undiscovered Conventional Oil and Gas 

Resources of the Western Canada Sedimentary Basin, 

Canada, 2012

Introduction

The U.S. Geological Survey (USGS) recently completed 

a geoscience-based assessment of undiscovered oil and gas 

resources of provinces within the Western Canada Sedimentary 

Basin (WCSB) (table 1). The WCSB primarily comprises the 

(1) Alberta Basin Province of Alberta, eastern British Columbia, 

and the southwestern Northwest Territories; (2) the Williston 

Basin Province of Saskatchewan, southeastern Alberta, and 

southern Manitoba; and (3) the Rocky Mountain Deformed 

Belt Province of western Alberta and eastern British Columbia (fig. 1). This report is part of the USGS World Petroleum 

Resources Project assessment of priority geologic provinces 

of the world. The assessment was based on geoscience elements that define a total petroleum system (TPS) and associated 

assessment unit(s) (AU). These elements include petroleum 

The U.S. Geological Survey mean estimates of undiscovered conventional oil and gas resources from provinces 

in the Western Canada Sedimentary Basin of central Canada are 1,321 million barrels of oil, 25,386 billion cubic feet 

of gas, and 604 million barrels of natural gas liquids.

MONTANA

ONTARIO

WASHINGTON NORTH 

DAKOTA

IDAHO

Rocky Mountain 

Deformed Belt

Mackenzie 

Foldbelt

Northern Interior Basins

Regina

Saskatoon

Williston Basin

Hudson Bay 

Basin

NORTHWEST TERRITORIES

BRITISH

COLUMBIA

NUNAVUT

MANITOBA

SASKATCHEWAN

CANADA

UNITED STATES

ALBERTA

HUDSON

BAY

Alberta Basin

Canadian 

Shield

Calgary

Edmonton

Winnipeg

UNITED STATES

CANADA

Area

of map

0 100 200 MILES

0 100 200 KILOMETERS

EXPLANATION

Middle and Upper 

Cretaceous Reservoirs AU 

Triassic through Lower

Cretaceous Reservoirs AU

Mississippian through 

Permian Reservoirs AU

Upper Devonian and

Older Reservoirs AU

129° 125° 121° 117° 113° 109° 105° 101° 97° 93° 89°

60°

58°

56°

54°

52°

50°

48°

Figure 1. Extent of the Western Canada Sedimentary Basin is approximated by the outer boundaries of 

the labeled Alberta Basin Province, Williston Basin Province, and Rocky Mountain Deformed Belt Province. 

Contained are conventional assessment units (AUs) for the (1) Middle and Upper Cretaceous Reservoirs 

AU of the Middle through Upper Cretaceous Composite Total Petroleum System (TPS); (2) Triassic through 

Lower Cretaceous Reservoirs AU, and (3) Mississippian through Permian Reservoirs AU, both of the ExshawFernie-Mannville Composite TPS; and (4) Upper Devonian and Older Reservoirs AU of the Elk Point-Woodbend 

Composite TPS.
source rocks (geochemical properties and petroleum generation, 

migration, and accumulation), reservoir description (reservoir 

presence, type, and quality), and petroleum traps (trap and seal 

types, and timing of trap and seal formation relative to petroleum migration). Using this framework, the Elk Point-Woodbend Composite TPS, Exshaw-Fernie-Mannville Composite 

TPS, and Middle through Upper Cretaceous Composite TPS 

were defined, and four conventional AUs within the TPSs were 

quantitatively assessed for undiscovered resources in the WCSB 

(table 1).

Figure 1 shows assessment unit (AU) boundaries for the 

(1) Middle and Upper Cretaceous Reservoirs AU; (2) Triassic 

through Lower Cretaceous Reservoirs AU; (3) Mississippian 

through Permian Reservoirs AU; and (4) Upper Devonian and 

Older Reservoirs AU. Boundaries of the AUs (fig. 1) encompass 

the extent of potential conventional petroleum resources within 

the labeled petroleum provinces. Conventional AUs are defined 

within three total petroleum systems (fig. 2, table 1) based 

mainly on results of 1D and 4D petroleum system modeling 

documented in Roberts and others (2005) and Higley and others 

(2009). Actual TPS divisions are considerably more complex 

in the WCSB (Allan and Creaney, 1991), particularly since the 

petroleum source rock kitchen for the Alberta Basin is proximal 

to and under the Canadian Rocky Mountains, and the Williston 

Basin petroleum is sourced from the south. 

Resource Summary

The USGS assessed undiscovered conventional oil and gas 

resources for provinces in the WCSB (table 1). Undiscovered, 

technically recoverable conventional resources mean totals 

are 1,321 million barrels of oil (MMBO), 25,386 billion cubic 

feet of gas (BCFG), and 604 million barrels of natural gas 

liquids (MMBNGL). Mean undiscovered resources for the (1) 

Middle and Upper Cretaceous Reservoirs AU are 110 MMBO, 

2,530 BCFG, and 69 MMBNGL; (2) Triassic through Lower 

Cretaceous Reservoirs AU are 571 MMBO, 15,728 BCFG, and 

400 MMBNGL; (3) Mississippian through Permian Reservoirs 

AU include 185 MMBO, 3,210 BCFG, and 42 MMBNGL; 

and (4) Upper Devonian and Older Reservoirs AU totals are 

455 MMBO, 3,918 BCFG, and 93 MMBNGL. 

Sources of Data

The primary source of well history and production data 

used in this assessment was the IHS Energy EnerdeqTM Desktop 

Canada database (2011). Other data sources are documented in 

Higley and others (2005, 2009). The Energy Resources Conservation Board (Energy Resources Conservation Board, 2011) 

contains pertinent geoscience and energy-reserves information 

accessed for this study. 

Assessment Team

Western Canada Sedimentary Basin Assessment Team: 

Debra K. Higley (Task Leader; higley@usgs.gov) and Review 

Committee: Ronald R. Charpentier, Troy A. Cook, Timothy 

R. Klett, Richard M. Pollastro, Christopher J. Schenk (Project 

Leader), Marilyn E. Tennyson, and Craig J. Wandrey. Further 

information on this and other World Petroleum Resources 

Project basins can be accessed at http://energy.usgs.gov/OilGas/

AssessmentsData/WorldPetroleumAssessment.aspx. 

Table 1. Western Canada Sedimentary Basin conventional resource assessment results.

[MMBO, million barrels of oil. BCFG, billion cubic feet of gas. MMBNGL, million barrels of natural gas liquids. Results shown are fully risked estimates. For 

gas fields, all liquids are included under the NGL (natural gas liquids) category. Undiscovered gas resources are the sum of nonassociated and associated gas. F95 

represents a 95-percent chance of at least the amount tabulated. Other fractiles are defined similarly. Largest expected oil field size is in MMBO; largest expected gas 

field is in BCFG. Fractiles are additive under the assumption of perfect positive correlation. Gray shading indicates not applicable. TPS, total petroleum system; AU, 

assessment unit.]

 Total petroleum systems 

 (TPS) 

and assessment units (AU)

Field 

type largest 

Expected 

field size

Total undiscovered resources

Oil (MMBO) Gas (BCFG) NGL (MMBNGL)

F95 F50 F5 Mean F95 F50 F5 Mean F95 F50 F5 Mean

Middle through Upper Cretaceous Composite TPS

Middle and Upper Cretaceous 

Reservoirs AU

Oil 1.2 74 107 154 110 112 168 247 172 0 0 1 0

Gas 13.0 1,595 2,302 3,327 2,358 47 67 98 69

Exshaw-Fernie-Mannville Composite TPS

Triassic through Lower 

Cretaceous Reservoirs AU

Oil 0.6 386 557 805 571 810 1,175 1,698 1,204 1 2 3 2

Gas 14.4 9,799 14,173 20,459 14,524 268 388 560 398

Mississippian through Permian 

Reservoirs AU

Oil 0.9 125 180 261 185 324 472 687 484 1 1 1 1

Gas 38.7 1,826 2,660 3,846 2,726 27 40 58 41

Elk Point-Woodbend Composite TPS

Upper Devonian and Older 

Reservoirs AU

Oil 3.3 306 444 641 455 390 573 835 587 0 1 1 1

Gas 25.1 2,241 3,253 4,698 3,331 62 90 129 92

Total conventional

resources 891 1,288 1,861 1,321 17,097 24,776 35,797 25,386 406 589 851 604
PLIOCENE 

MIOCENE

OLIGOCENE

EOCENE

Fernie GpUpper Fernie

Ishbel Group

Spray Lakes Group

Beaverhill Lake Group

Elk Point Group

Interlake Group -

Winnipeg Fm.

Deadwood Fm. -

Basal Sandstone

PALEOCENE

Upper

Lower

Upper

Middle

Lower

Upper

Middle

Lower

Upper

Lower

Upper

Middle

Lower

Upper

Middle

Lower

 2.6

55.8

65.5

99.6

161

176

200

228

245

251

271

299

318

328

345

359

385

397

416

444

488

542

Paleozoic Mesozoic 

Cenozoic

119

150

Devonian Carboniferous Triassic Jurassic Cretaceous Tertiary

Era System Series

QUATERNARY Mississippian

Perm.

Penn.

Alberta - Generalized

 Stratigraphy

Age 

Ma.

Silurian Cam- brian Ordo- vician

Petroleum System

Element

Overburden

Seal

Reservoir

Seal

Source/Seal/

Seal/Reservoir

Banff Formation Source(?)/Seal/Reservoir

Exshaw, Bakken Fms. Source/Reservoir

Wabamun Group, Winterburn Group Seal/Reservoir

Reservoir

Duvernay Formation

Rundle Group

Nordegg,Gordondale Members

Poker Chip Shale Member

Mannville Gp.Upper

Mannville

coal

Ostracode zone

Lower

Mannville

Colorado Group Colorado Shale

Paskapoo Fm.

Edmonton Gp.

Belly River Fm.

Lea Park Fm.

Cardium Fm.

Second White

Speckled Shale

Fish Scale zone

Viking Fm.

Joli Fou Shale

Woodbend Group

Doig Fm.

Schooler 

Creek Group

Montney Fm.

 Seal

 Reservoir

 Reservoir

Seal

Seal/Source

Seal/Source

 Reservoir

Source

Source/Reservoir

Seal/Reservoir

Figure 2.

Source/Reservoir

Source

Source/Reservoir

Seal/Reservoir

Seal/Reservoir

Unconformity

Figure 2. Generalized stratigraphic section of mainly the Alberta portion of the Western Canada Sedimentary Basin showing age ranges 

of the Middle through Upper Cretaceous Composite TPS (yellow), Exshaw-Fernie-Mannville Composite TPS (pink), and Elk Point-Woodbend 

Composite TPS (blue). Lithologies include primarily shale or marl (gray), sandstone (stipple), carbonates (white), and coal (black). Mossop 

and Shetsen (1994) was the primary source for lithofacies types. Modified from Higley and others (2009). (Fm(s), Formation(s); Gp., Group; 

Mem., Member; Perm., Permian; Penn., Pennsylvanian.)
References Cited

Allan, J., and Creaney, S., 1991, Oil families of the Western 

Canada Basin: Bulletin of Canadian Petroleum Geology, 

v. 39, no. 2, p. 107–122.

Energy Resources Conservation Board, 2011, Alberta’s energy 

reserves 2010 and supply/demand outlook 2011–2020: 

Calgary, Alberta, Energy Resources Conservation Board 

ST98-2011, 263 p.

Higley, D.K., Henry, M.E., and Roberts, L.N.R., 2005, Petroleum system modeling of the Western Canada Sedimentary 

Basin—Isopach grid files: U.S. Geological Survey Open-File 

Report 2005–1421, 14 p. (Also available at http://pubs.usgs.

gov/of/2005/1421.) 

Higley, D.K., Lewan, M.D., Roberts, L.N.R., and Henry, 

M.E., 2009, Timing and petroleum sources for the Lower 

Cretaceous Mannville Group oil sands of northern Alberta 

based on 4-D modeling: American Association of Petroleum 

Geologists Bulletin, v. 93 no. 2, p. 203–230.

IHS Energy, 2011, IHS Energy EnerdeqTM Desktop Canada 

database: Unpublished database available from IHS 

Energy, 15 Inverness Way East, Englewood, Colo., 

80112.

Mossop, G., and Shetsen, I., comps., 1994, Geological 

atlas of the Western Canada Sedimentary Basin: Calgary, 

Alberta, Canadian Society of Petroleum Geologists and 

Alberta Research Council, accessed June 1, 2012, at 

http://www.ags.gov.ab.ca/publications/wcsb_atlas/

atlas.html.

Roberts, L.N.R., Higley, D.K., and Henry, M.E., 2005, 

Input data used to generate one-dimensional burial history models, central Alberta, Canada: U.S. Geological 

Survey Open-File Report 2005–1412, 14 p. (Also available at http://pubs.usgs.gov/of/2005/1412/.) 

Cascade Mountain, located in the Bow River Valley and bordering Banff in the Canadian Rockies of Alberta. Photo by Debra Higley.