U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2016–3028

May 2016 Printed on recycled paper

National and Global Petroleum Assessment 

Assessment of Undiscovered Conventional Oil and Gas Resources 

of the Cooper and Eromanga Basins, Australia, 2016

Using a geology-based assessment methodology, the U.S. Geological Survey estimated mean conventional resources of 68 million 

barrels of oil and 964 billion cubic feet of gas in the Cooper and Eromanga Basins of Australia.

Introduction

The U.S. Geological Survey quantitatively assessed the 

potential for undiscovered, technically recoverable conventional 

oil and gas resources in the Cooper and Eromanga Basins of 

Australia (fig. 1) as part of an effort to assess priority geologic 

provinces of the world. By Australian convention, a basin represents an unconformity-bounded set of genetically related strata 

and can be vertically stacked. Thus, the Warburton (Cambrian–

Devonian), Cooper (Permian–Triassic), Eromanga (Jurassic–

Cretaceous), and Lake Eyre (Tertiary) Basins are stacked (Menpes 

and Hill, 2012), with each succeeding basin areally larger than the 

preceding one. For this U.S. Geological Survey assessment, the 

Eromanga Basin Province encompasses the Cooper and Eromanga 

Basins. This study assessed the potential for undiscovered conventional oil and gas resources in the Cooper and Eromanga Basins, 

in which more than 500 conventional oil and gas fields have been 

discovered since the 1960s (IHS Energy, 2015). Given the exploration maturity, most undiscovered fields are estimated to be small 

and in stratigraphic or combination structural-stratigraphic traps 

(Apak and others, 1997).

For the assessment of conventional resources, the 

U.S. Geological Survey defined a Cooper-Eromanga Composite 

Total Petroleum System with Permian and Jurassic coals as the 

primary source rocks for oil and gas (Boult and others, 1997; 

Lowe-Young and others, 1997). Five assessment units (AUs) 

were defined within this composite total petroleum system to 

encompass oil and gas that were generated largely from coals 

and migrated and were trapped in Permian through Cretaceous 

reservoirs. Three AUs were defined within strata of the Cooper 

Basin and two within the Eromanga Basin. Most of the known 

gas fields are in the Cooper Basin, whereas most oil fields are in 

the overlying Eromanga Basin. The assessment input data for the 

five conventional AUs are shown in table 1.

Undiscovered Resource Summary

The U.S. Geological Survey quantitatively assessed 

undiscovered, technically recoverable oil and gas resources in 

five assessment units within the Cooper and Eromanga Basins 

(table 2). For undiscovered conventional resources, the mean 

totals are (1) 68 million barrels of oil (MMBO), with an F95 to 

F5 range from 39 to 108 MMBO; (2) 964 billion cubic feet of 

gas (BCFG), with an F95 to F5 range from 509 to 1,633 BCFG; 

and (3) 19 million barrels of natural gas liquids (MMBNGL), 

with an F95 to F5 range from 9 to 34 MMBNGL.

Figure 1. Map showing locations of five conventional assessment 

units in the Eromanga Basin Province, Australia.

Of the mean total conventional oil resource of 68 MMBO, 

48 MMBO (with an F95 to F5 range from 28 to 75 MMBO) 

are predicted to be in the South Eromanga Basin Mesozoic 

Conventional Reservoirs AU, and 20 MMBO (with an F95 to F5 

range from 11 to 33 MMBO) are in the North Eromanga Basin 

Mesozoic Conventional Reservoirs AU. About 80 percent of the 

undiscovered conventional gas resources are predicted to be in 

the Greater Nappamerri Trough Permian Conventional Reservoirs 

139° 140° 141° 142° 143° 144°

–25°

–26°

–27°

–28°

–29°

QUEENSLAND

SOUTH AUSTRALIA

NEW SOUTH

WALES

Source: National Park Service

Durham

Downs

Bulloo Downs

Nockatunga

Cordillo 

 Downs

AUSTRALIA

Area

of study

INDIAN

OCEAN

CORAL

SEA

TASMAN SEA

Eromanga Basin Province

Cooper Basin Conventional Assessment Units

Greater Patchawarra Trough Permian 

Conventional Reservoirs AU 

Cooper Basin 

Greater Nappamerri Trough Permian 

Conventional Reservoirs AU 

Eromanga Basin Conventional Assessment Units

South Eromanga Basin Mesozoic

Conventional Reservoirs AU 

North Eromanga Basin Mesozoic

Conventional Reservoirs AU 

EXPLANATION

Queensland Troughs Permian 

Conventional Reservoirs AU 

0 50 100 KILOMETERS

0 50 100 MILES
Table 2. Assessment results for conventional oil and gas resources in the Eromanga Basin 

Province, Australia.

[TPS, total petroleum system; AU, assessment unit; 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 accumulations, all 

liquids are included under the NGL (natural gas liquids) category. 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] 

Assessment input data

South Eromanga Basin Mesozoic 

Conventional Reservoirs AU Minimum Median Maximum Calculatedmean

Number of oil fields 1 50 120 52

Number of gas fields 1 10 30 10.6

Sizes of oil fields (MMBO) 0.5 0.7 10 0.92

Sizes of gas fields (BCFG) 3 6 10 6.1

AU probability 1.0

North Eromanga Basin Mesozoic 

Conventional Reservoirs AU Minimum Median Maximum Calculatedmean

Number of oil fields 1 25 72 26.5

Number of gas fields 1 6 18 6.4

Sizes of oil fields (MMBO) 0.5 0.7 2 0.75

Sizes of gas fields (BCFG) 3 5 8 5.1

AU probability 1.0

Greater Nappamerri Trough Permian 

Conventional Reservoirs AU Minimum Median Maximum Calculatedmean

Number of gas fields 1 30 60 30.7

Sizes of gas fields (BCFG) 3 9 100 11.8

AU probability 1.0

Greater Patchawarra Trough Permian 

Conventional Reservoirs AU Minimum Median Maximum Calculatedmean

Number of gas fields 1 10 60 11.7

Sizes of gas fields (BCFG) 3 9 25 9.5

AU probability 1.0

Queensland Troughs Permian 

Conventional Reservoirs AU Minimum Median Maximum Calculatedmean

Number of gas fields 1 40 144 43.5

Sizes of gas fields (BCFG) 3 6 25 6.7

AU probability 1.0

Total petroleum 

system (TPS) and

assessment units (AUs)

AU

probability

Accumulation

type

Total undiscovered resources

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

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

Cooper-Eromanga Composite TPS

South Eromanga Basin 

Mesozoic Conventional 

Reservoirs AU

1.0

Oil 28 46 75 48 48 82 138 86 0 1 1 1

Gas 35 61 109 65 1 1 2 1

North Eromanga Basin 

Mesozoic Conventional 

Reservoirs AU

1.0

Oil 11 19 33 20 6 12 23 13 0 0 0 0

Gas 19 31 54 33 0 0 1 1

Greater Nappamerri Trough 

Permian Conventional 

Reservoirs AU

1.0 Gas 226 354 540 365 3 5 8 5

Greater Patchawarra Trough 

Permian Conventional 

Reservoirs AU

1.0 Gas 40 96 244 112 1 3 7 3

Queensland Troughs 

Permian Conventional 

Reservoirs AU

1.0 Gas 135 267 525 290 4 7 15 8

Total undiscovered 

conventional resources 39 65 108 68 509 903 1,633 964 9 17 34 19

AU (mean of 365 BCFG, with an F95 

to F5 range from 226 to 540 BCFG), 

Greater Patchawarra Trough Permian 

Conventional Reservoirs AU (mean 

of 112 BCFG, with an F95 to F5 

range from 40 to 244 BCFG), and 

the Queensland Troughs Permian 

Conventional Reservoirs AU (mean of 

290 BCFG, with an F95 to F5 range 

from 135 to 525 BCFG).

References Cited

Apak, S.N., Stuart, W.J., Lemon, N.M., 

and Wood, G., 1997, Structural 

evolution of the Permian–Triassic 

Cooper Basin, Australia—Relation 

to hydrocarbon trap styles: American 

Association of Petroleum Geologists 

Bulletin, v. 81, no. 4, p. 533–555.

Boult, P.J., Ryan, M.J., Michaelsen, 

B.H., McKirdy, D.M., Tingate, P.R., 

Lanzilli, Elio, and Kagya, M.L.N., 

1997, The Birkhead–Hutton (!) petroleum system of the Gidgealpa area, 

Eromanga Basin, Australia, in Howes, 

J.V.V., and Noble, R.A., eds., Proceedings of an International Conference on 

Petroleum Systems of Southeast Asia 

and Australasia, Jakarta, Indonesia, 

May 21–23, 1997: Jakarta, Indonesian 

Petroleum Association, p. 213–235.

IHS Energy, 2015, International petroleum exploration and production database: Englewood, Colo., IHS Energy.

Lowe-Young, B.S., Mackie, S.I., and 

Heath, R.S., 1997, The CooperEromanga petroleum system, 

Australia—Investigation of essential 

elements and processes, in Howes, 

J.V.V., and Noble, R.A., eds., Proceedings of an International Conference on 

Petroleum Systems of Southeast Asia 

and Australasia, Jakarta, Indonesia, 

May 21–23, 1997: Jakarta, Indonesian 

Petroleum Association, p. 199–211.

Menpes, S.A., and Hill, A.J., 2012, 

Emerging continuous gas plays in 

the Cooper Basin, South Australia: 

American Association of Petroleum 

Geologists Search and Discovery 

Article #10422, 7 p.

Table 1. Key assessment input data for conventional assessment units in the Eromanga Basin 

Province, Australia.

[AU, assessment unit; MMBO, million barrels of oil; BCFG, billion cubic feet of gas. Shading indicates not applicable]

For More Information

Assessment results are available at the U.S. Geological Survey Energy Resources Program Web site at http://energy.usgs.gov/.

Eromanga Basin Province Assessment Team

Christopher J. Schenk, Marilyn E. Tennyson, Tracey J. Mercier, Timothy R. Klett, Thomas M. Finn, Phuong A. Le, 

Michael E. Brownfield, Stephanie B. Gaswirth, Kristen R. Marra, Sarah J. Hawkins, Heidi M. Leathers-Miller, and Janet K. Pitman

ISSN 2327-6916 (print) ISSN 2327-6932 (online) http://dx.doi.org/10.3133/fs20163028