U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2018–3071

January 2019

National and Global Petroleum Assessment

Assessment of Continuous Gas Resources in the Montney 

and Doig Formations, Alberta Basin Province, Canada, 2018

Introduction

The U.S. Geological Survey (USGS) quantitatively assessed 

the potential for undiscovered, technically recoverable continuous 

(unconventional) gas resources in the Triassic Montney and Doig 

Formations of the Alberta Basin Province of Canada (fig. 1). In this 

study, the upper Montney Formation siltstones were assessed as a 

tight-gas accumulation (Chalmers and Bustin, 2012), and the Doig 

Formation phosphatic shales were assessed as a potential shale-gas 

accumulation (Chalmers and others, 2012).

Total Petroleum Systems and Assessment Units

The USGS defined an Upper Montney Total Petroleum 

System (TPS) and a Doig TPS. The upper part of the Montney 

Formation consists of organic-bearing siltstones that represent 

distal shelf, slope, and basinal turbidite deposits. These siltstones 

contain mainly Type II organic matter, have organic carbon contents 

of as much as 4 weight percent, have hydrogen index values of 

as much as 450 milligrams of hydrocarbon per gram of organic 

carbon, are overpressured, and can be as much as 200 meters thick 

(Chalmers and Bustin, 2012; Schmitz and others, 2014; Crombez 

and others, 2017). Phosphatic shales of the Doig Formation contain 

Type II organic matter, have organic carbon contents of as much 

as 11 weight percent, have hydrogen index values of as much as 

485 milligrams of hydrocarbon per gram of organic carbon, are 

overpressured, and are as much as 180 meters thick (Chalmers 

and Bustin, 2012). Thermal maturity maps of the Doig Formation 

show that much of the formation (and underlying part of the upper 

Montney) is thermally mature for gas generation in the western 

part of the basin where the upper part of the Montney and Doig are 

overpressured (Creaney and others, 1994; Ducros and others, 2017). 

Late Cretaceous through Paleogene foreland burial is generally considered to have thermally matured Montney and Doig source rocks 

(Chalmers and Bustin, 2012; Ducros and others, 2017).

The geologic model for the Upper Montney TPS is for oil and 

gas to have been generated in distal organic-bearing siltstones, the oil 

to have cracked to gas within the overpressured zone, and some of the 

gas to have been retained within the upper part of the Montney Formation siltstones following migration. The Upper Montney Tight Gas 

Assessment Unit (AU) was defined to encompass areas of organicrich siltstones within the overpressured gas-generation window. The 

geologic model for the Doig TPS is for oil and gas to have been 

generated from condensed, phosphatic Middle Triassic shales from 

Late Cretaceous–Paleogene burial. Within the overpressured area, 

oil thermally cracked to gas, which was partially retained within the 

shales following migration updip into conventional traps. The Doig 

Shale Gas AU was defined to encompass areas of organic-rich shale 

within the overpressured gas-generation window.

Assessment input data are summarized in table 1. Input data 

from wells within drainage areas in the upper part of the Montney 

are based mainly on Schmitz and others (2014) and Kwan (2015). 

Drainage areas (for shales of the Doig Formation), success ratios, 

and estimated ultimate recoveries of wells are taken from geologic 

analogs in the United States.

Figure 1. Map showing the two continuous assessment units (AUs) 

in the Montney and Doig Formations of the Alberta Basin Province in 

Canada. Province boundary is from Klett and others (1997). 

ALBERTA

BRITISH

COLUMBIA

126° W 122° W 118° W 114° W

54° N

52° N

56° N

58° N

0 100 KILOMETERS 50

0 50 100 MILES

Base map from U.S. Department of the Interior National Park Service

Doig Shale Gas AU

Upper Montney TPS and Doig TPS

Alberta Basin Province boundary (part)

Upper Montney Tight Gas AU

EXPLANATION

Alberta Basin Province boundary is

shown in plum.

USA

CAN

CAN

USA

PACIFIC

OCEAN

BRITISH

COLUMBIA

YUKON NORTHWEST

TERRITORIES

ALBERTA

SASKATCHEWAN

Map

area

Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean

resources of 47.6 trillion cubic feet of gas and 2.2 billion barrels of natural gas liquids in the Montney and Doig Formations of the 

Alberta Basin Province in Canada.
For More Information

Assessment results are also available at the USGS Energy Resources Program website at https://energy.usgs.gov.

Montney and Doig Formations Assessment Team

Christopher J. Schenk, Tracey J. Mercier, Marilyn E. Tennyson, Thomas M. Finn, Cheryl A. Woodall, Phuong A. Le, Michael E. Brownfield, 

Kristen R. Marra, and Heidi M. Leathers-Miller 

ISSN 2327-6916 (print) ISSN 2327-6932 (online) https://doi.org/10.3133/fs20183071

Table 1. Key input data for two continuous assessment units (AUs) in the Montney and Doig Formations of the Alberta Basin Province in Canada.

[AU, assessment unit; %, percent; EUR, estimated ultimate recovery per well; BCFG, billion cubic feet of gas. Well drainage area, success ratio, and EUR are defined 

partly using U.S. tight-gas and shale-gas analogs. The average EUR input is the minimum, median, maximum, and calculated mean. Shading indicates not applicable]

Assessment input data—

Continuous AUs

Upper Montney Tight Gas AU Doig Shale Gas AU

Minimum Mode Maximum Calculated 

mean Minimum Mode Maximum Calculated mean

Potential production area of AU (acres) 1,000 5,650,500 11,301,000 5,650,833 1,000 2,000,000 11,301,000 4,434,000

Average drainage area of wells (acres) 160 200 240 200 80 120 160 120

Untested area (%) 85 90 95 90 91 95 99 95

Success ratio (%) 75 85 95 85 10 50 90 50

Average EUR (BCFG) 0.6 1.5 2.5 1.536 0.4 0.8 1.4 0.825

AU probability 1.0 1.0

Table 2. Results for two continuous assessment units (AUs) in the Montney and Doig Formations of the Alberta Basin Province in Canada.

[BCFG, billion cubic feet of gas; NGL, natural gas liquids; MMBNGL, million barrels of natural gas liquids. Results shown are fully risked estimates. F95 represents 

a 95-percent chance of at least the amount tabulated; other fractiles are defined similarly. Fractiles are additive under the assumption of perfect positive correlation. 

Shading indicates not applicable]

Total petroleum systems 

and assessment units (AUs)

AU

probability

Accumulation 

type

Total undiscovered resources

Gas (BCFG) NGL (MMBNGL)

F95 F50 F5 Mean F95 F50 F5 Mean

Upper Montney Total Petroleum System

Upper Montney Tight Gas AU 1.0 Gas 9,969 32,192 59,143 33,072 479 1,574 3,109 1,655

Doig Total Petroleum System

Doig Shale Gas AU 1.0 Gas 2,665 12,101 34,603 14,544 100 471 1,443 582

Total undiscovered continuous resources 12,634 44,293 93,746 47,616 579 2,045 4,552 2,237

Undiscovered Resources Summary

The USGS quantitatively assessed continuous gas resources in two 

assessment units (table 2). For undiscovered, technically recoverable 

continuous gas resources, the mean totals are 47,616 billion cubic feet 

 Montney-Doig system—Implications for hydrocarbon migration pathways 

and unconventional resources potential, in AbuAli, M.A., Moretti, I., and 

Norgård Bolås, H.M., eds., Petroleum system analysis—Case studies: 

American Association of Petroleum Geologists, Memoir 114, p. 117–134.

Klett, T.R., Ahlbrandt, T.S., Schmoker, J.W., and Dolton, G.L., 1997, Ranking 

of the world’s oil and gas provinces by known petroleum volumes: U.S. 

Geological Survey Open-File Report 97–463, 1 CD–ROM. [Also available 

at https://pubs.usgs.gov/of/1997/ofr-97-463/97463.html.]

Kwan, M.A., 2015, The evolution of the Montney completion design—

Completion-driven well performance compared to Lower 48 plays, 

in Unconventional Resources Technology Conference, Austin, Texas, 

July 24–26, 2017, Proceedings: Society of Exploration Geophysicists, 

American Association of Petroleum Geologists, Society of Petroleum 

Engineers, URTeC 2691110, 5 p., accessed on July 30, 2018, at https://

www.onepetro.org/conference-paper/URTEC-2691110-MS.

Schmitz, R., Nevokshonoff, G., and Haysom, S., 2014, An integrated approach to development optimization in Seven Generations’ Kakwa liquids rich Montney play, in Unconventional 

Resources Technology Conference, Denver, Colorado, August 

25–27, 2014, Proceedings: Society of Exploration Geophysicists, 

American Association of Petroleum Geologists, Society of Petroleum 

Engineers, URTeC 1934952, 20 p., accessed on July 30, 2018, at 

https://library.seg.org/doi/pdf/10.15530/urtec-2014-1934952.

References Cited

Chalmers, G.R.L., and Bustin, R.M., 2012, Geological evaluation of 

Halfway–Doig–Montney hybrid gas shale–tight gas reservoir, northeastern 

British Columbia: Marine and Petroleum Geology, v. 38, no. 1, p. 53–72.

Chalmers, G.R.L., Bustin, R.M., and Bustin, A.A.M., 2012, Geological 

controls on matrix permeability of the Doig-Montney hybrid shalegas–tight-gas reservoir, northeastern British Columbia (NTS 093P), in

Geosciences British Columbia Summary of Activities 2011: Geoscience 

British Columbia, Report 2012-1, p. 87–96.

Creaney, S., Allan, J., Cole, K.S., Fowler, M.G., Brooks, P.W., Osadetz, 

K.G., Macqueen, R.W., Snowdon, L.R., and Riediger, C.L., 1994,

Petroleum generation and migration in the Western Canada Sedimentary

Basin, chap. 31 of Mossop, G., and Shetsen, I., comps., Geological atlas

of the Western Canada Sedimentary Basin: Canadian Society of Petroleum Geologists and Alberta Research Council, p. 455–468.

Crombez, V., Baudin, F., Rohais, S., Riquier, L., Euzen, T., Pauthier, S., Ducros, 

M., Caron, B., and Vaisblat, N., 2017, Basin scale distribution of organic 

matter in marine fine-grained sedimentary rocks—Insight from sequence 

stratigraphy and multi-proxies analysis in the Montney and Doig Formations: 

Marine and Petroleum Geology, v. 83, p. 382–401.

Ducros, M., Sassi, W., Vially, R., Euzen, T., and Crombez, V., 2017, 2-D 

basin modeling of the Western Canada Sedimentary Basin across the

of gas (BCFG), or 47.6 trillion cubic feet of gas, with an F95–F5 fractile 

range from 12,634 to 93,746 BCFG and 2,237 million barrels of 

(associated) natural gas liquids (MMBNGL), or 2.2 billion barrels of 

(associated) natural gas liquids, with an F95–F5 fractile range from 579 

to 4,552 MMBNGL.