U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2019–3013

June 2019

National and Global Petroleum Assessment

Assessment of Continuous Oil and Gas Resources in the 

Beetaloo Basin, Australia, 2018

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

of 429 million barrels of continuous oil and 8 trillion cubic feet of continuous gas in the Beetaloo Basin of northern Australia. 

Introduction

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

potential for undiscovered, technically recoverable continuous oil and 

gas resources in the Beetaloo Basin of northern Australia (fig. 1). The 

Mesoproterozoic Roper Group in the basin contains the Velkerri and Kyalla 

Formations, two organic-rich source formations that possibly form some of 

the oldest viable petroleum systems in the world (Jackson and others, 1986; 

Silverman and Ahlbrandt, 2011; Cox and others, 2016). The shale units of 

the Velkerri and Kyalla were deposited between 1,400 and 1,300 million 

years ago (Yang and others, 2018). Limited drilling and production testing 

have shown that these rocks may contain recoverable oil and gas resources 

(Close, Cote, and others, 2017). For rocks of this age to potentially contain 

recoverable oil and gas indicates that throughout the long period between the 

Mesoproterozoic and the present, there has been limited deformation of the 

Beetaloo Basin, and generation might have been relatively late in the burial 

history. However, the tectonic evolution of the Mesoproterozoic Beetaloo 

Basin is largely unknown, and several hypotheses have been advanced that 

include rift basin, multiphase intracontinental basin, foreland basin, and 

epicontinental basin development (Silverman and Ahlbrandt, 2011; Cox and 

others, 2016; Close, Cote, and others, 2017; Yang and others, 2018). Rocks of 

the Roper Group have not been thermally stressed beyond the gas-generation 

window (Close, Baruch, and others, 2017).

Total Petroleum Systems and Assessment Units

The USGS defined the Proterozoic Velkerri Shale Total Petroleum 

System (TPS) with the Proterozoic Middle Velkerri Shale Gas Assessment 

Unit (AU) and the Proterozoic Lower Kyalla Shale TPS with the Proterozoic 

Lower Kyalla Shale Oil AU and the Proterozoic Lower Kyalla Shale Gas AU. 

Shales from the middle part of the Velkerri Formation are overpressured and 

can have as much as 12 weight percent total organic matter, have hydrogen 

indices as high as 730 milligrams of hydrocarbon per gram of organic carbon, 

and contain Type I and Type II organic matter (Crick and others, 1988; 

Warren and others, 1998; Law and others, 2010; McConachie and others, 

2015; Revie, 2016; Close, Baruch, and others, 2017). Shales of the lower part 

of the Kyalla Formation are overpressured and can have as much as 8 weight 

percent total organic carbon, have hydrogen indices as high as 780 milligrams 

of hydrocarbon per gram of organic carbon, and contain Type I and Type II 

organic matter (Law and others, 2010; McConachie and others, 2015; Revie, 

2016; Close, Baruch, and others, 2017). The interpretation of the extent of 

the oil and gas thermal generation windows in these shales is quite variable 

(Law and others, 2010; Revie, 2016; Close, Baruch, and others, 2017). In this 

study, the oil and gas thermal windows of Revie (2016) and Close, Baruch, 

and others (2017) were used in the definition of AU boundaries with the 

understanding that these boundaries are highly uncertain. The timing of oil 

and gas generation is also highly uncertain given what little is known of the 

tectonic evolution, burial history, and paleo-heat flow. Estimates of timing of 

generation range from essentially syndepositional to early Paleozoic (Crick 

and others, 1988) or as late as the Mesozoic (Silverman and Ahlbrandt, 2011).

The geologic model for the Proterozoic Middle Velkerri Shale Gas 

AU is for oil to have been generated from Type I and Type II organic matter 

and largely cracked to gas with some portion of the gas retained within the 

shales. The geologic model for the Proterozoic Lower Kyalla Shale Oil AU 

and Proterozoic Lower Kyalla Shale Gas AU is for these shales to have been 

buried to depths within the oil- and gas-generation windows; some portion 

of the oil and gas has been retained within the shales following migration. 

Uncertainty in the assessment is related to the retention of oil and gas in these 

shales and the mapped extent of the oil and gas thermal generation windows.

The assessment input data are summarized in table 1. There are no 

geologic analogs for these Mesoproterozoic organic-rich shales, so well 

drainage areas, success ratios, and estimated ultimate recoveries are roughly 

based on data ranges from U.S. shale-oil and shale-gas accumulations.

Undiscovered Resources Summary

The USGS quantitatively assessed the potential for continuous oil 

and gas resources within the Beetaloo Basin (table 2). The estimated mean 

totals for undiscovered resources are 429 million barrels of oil (MMBO) 

with an F95–F5 range from 0 to 1,135 MMBO; 8,044 billion cubic feet of 

gas (BCFG), or 8 trillion cubic feet of gas, with an F95–F5 range from 0 to 

23,749 BCFG; and 278 million barrels of natural gas liquids (MMBNGL) 

with an F95–F5 range from 0 to 867 MMBNGL.

Birdum

AUSTRALIA

NORTHERN TERRITORY

GULF OF 

CARPENTERIA

16° S

18° S

132° E 134° E 136° E

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

WESTERN

AUSTRALIA

NORTHERN

TERRITORY

QUEENSLAND

SOUTH

AUSTRALIA NEW

SOUTH

WALES

VICTORIA

TASMANIA

INDIAN

OCEAN

CORAL

SEA

PACIFIC

OCEAN

TASMAN

SEA

Map

area

0 30 60 KILOMETERS

0 30 60 MILES

EXPLANATION

Proterozoic Lower Kyalla

 Shale Oil AU

Beetaloo Basin

Proterozoic Lower Kyalla

 Shale Gas AU

Proterozoic Middle Velkerri

 Shale Gas AU

Figure 1. Map showing the location of three continuous assessment 

units (AUs) in the Beetaloo Basin of northern Australia.
Table 1. Key input data for three continuous assessment units in the Beetaloo Basin, northern Australia.

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

defined partly using U.S. shale-oil 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

Proterozoic Middle Velkerri Shale Gas AU Proterozoic Lower Kyalla Shale Gas AU

Minimum Mode Maximum Calculated mean Minimum Mode Maximum Calculated mean

Potential production area of AU (acres) 240 3,436,000 6,873,000 3,436,413 240 2,686,000 5,372,000 2,686,080

Average drainage area of wells (acres) 60 120 180 120 60 120 180 120

Success ratio (%) 10 50 90 50 100 100 100 100

Area untested in AU (%) 100 100 100 100 10 50 90 50

Average EUR (BCFG) 0.04 0.4 2.0 0.488 0.04 0.1 1.5 0.169

AU probability 0.9 0.9

Assessment input data—

Continuous AU

Proterozoic Lower Kyalla Shale Oil AU

Minimum Mode Maximum Calculated mean

Potential production area of AU (acres) 240 1,454,000 2,908,000 1,454,080

Average drainage area of wells (acres) 60 140 220 140

Success ratio (%) 10 50 90 50

Area untested in AU (%) 100 100 100 100

Average EUR (MMBO) 0.01 0.08 0.3 0.092

AU probability 0.9

Table 2. Results for three continuous assessment units in the Beetaloo Basin, northern Australia.

[MMBO, million barrels of oil; 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

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

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

 Proterozoic Velkerri Shale Total Petroleum System

Proterozoic Middle Velkerri Shale Gas AU 0.9 Gas 0 4,631 17,544 6,155 0 145 617 205

 Proterozoic Lower Kyalla Shale Total Petroleum System

Proterozoic Lower Kyalla Shale Gas AU 0.9 Gas 0 982 5,490 1,631 0 37 227 65

Proterozoic Lower Kyalla Shale Oil AU 0.9 Oil 0 347 1,135 429 0 197 715 258 0 6 23 8

Total undiscovered 

continuous resources 0 347 1,135 429 0 5,810 23,749 8,044 0 188 867 278

Beetaloo Basin Assessment Team

Christopher J. Schenk, Tracey J. Mercier,

Cheryl A. Woodall, Thomas M. Finn, Kristen R. Marra,

Michael E. Brownfield, Heidi M. Leathers-Miller, and

Ronald M. Drake II

For More Information

Assessment results are also available at the

USGS Energy Resources Program website at https://

energy.usgs.gov.

References Cited

Close, D., Baruch, E., Cote, A., Altmann, C., Mohinudeen, F., Richards, B., and Stonier, 

S., 2017, Unconventional gas potential in the Northern Territory, Australia—

Exploring the Beetaloo sub-basin: American Association of Petroleum Geologists, 

Search and Discovery Article No. 10933, 13 p., accessed October 19, 2018, at http://

www.searchanddiscovery.com/pdfz/documents/2017/10933close/ndx_close.pdf.htm

l?q=%252BauthorStrip%253Aclose+-isMeetingAbstract%253Amtgabsyes.

Close, D., Cote, A., Baruch, E., Altmann, C., Mohinudeen, F., Richards, B., and Ilett, 

R., 2017, Proterozoic shale gas plays in the Beetaloo Basin and the Amungee 

NW-1H discovery, in 2017 Annual Geoscience Exploration Seminar, Alice Springs, 

Northern Territory, Australia, March 28–19, 2017, Proceedings: Northern Territory 

Geological Survey, p. 91–97, accessed October 19, 2018, at http://www.paltar.com.au/

AGES2017_DC.pdf.

Cox, G.M., Jarrett, A., Edwards, D., Crockford, P.W., Halverson, G.P., Collins, A.S., 

Poirier, A., and Li Zheng-Xiang, 2016, Basin redox and primary productivity within 

the Mesoproterozoic Roper Seaway: Chemical Geology, v. 440, p. 101–114.

Crick, I.H., Boreham, C.J., Cook, A.C., and Powell, T.G., 1988, Petroleum geology 

and geochemistry of Middle Proterozoic McArthur Basin, Northern Australia 

II—Assessment of source rock potential: American Association of Petroleum 

Geologists Bulletin, v. 72, no. 12, p. 1495–1514.

Jackson, M.J., Powell, T.G., Summons, R.E., and Sweet, I.P., 1986, Hydrocarbon 

shows and petroleum source rocks in sediments as old as 1.7x109

 years: Nature, 

v. 322, p. 727–729.

Law, B., Ahlbrandt, T., and Hoyer, D., 2010, Source and reservoir rock

 attributes of Mesoproterozoic shales, Beetaloo Basin, Northern Territory, 

Australia: American Association of Petroleum Geologists, Search and 

Discovery Article No. 110130, 42 p., accessed October 19, 2018, at 

http://www.searchanddiscovery.com/documents/2010/110130law/

ndx_law.pdf?q=%2BauthorStrip%3Ahoyer+-isMeetingAbstract%3Amtgabsyes.

McConachie, B.A., Stanmore, P., McLean-Hodgson, L., Kushkarina, A., and Lewis, 

E., 2015, Unconventional gas reservoir productivity in Australian Proterozoic 

rocks—Studies from the McArthur, Beetaloo, Mount Isa, and Amadeus: American 

Association of Petroleum Geologists, Search and Discovery Article No. 80501, 

33 p., accessed October 19, 2018, at http://www.searchanddiscovery.com/

documents/2015/80501mcconachie/ndx_mcmonachie.pdf?q=%2BauthorStrip%3A

mcconachie+-isMeetingAbstract%3Amtgabsyes.

Revie, D., 2016, From the back of the shed to the forefront of exploration—What 

the NTGS core store is revealing about the Roper Group shales of the greater 

McArthur Basin, in 2016 Annual Geoscience Exploration Seminar, Alice Springs, 

Northern Territory, Australia, March 15–16, 2016, Proceedings: Northern Territory 

Geological Survey, 29 p., accessed October 19, 2018, at https://geoscience.nt.gov.

au/gemis/ntgsjspui/handle/1/82743.

Silverman, M., and Ahlbrandt, T., 2011, Mesoproterozoic unconventional plays 

in the Beetaloo Basin, Australia—The World’s oldest petroleum systems: 

American Association of Petroleum Geologists, Search and Discovery 

Article No. 10295, 41 p., accessed October 19, 2018, at http://www.

searchanddiscovery.com/documents/2011/10295silverman/ndx_silverman.

pdf?q=%2BauthorStrip%3Asilverman+-isMeetingAbstract%3Amtgabsyes.

Warren, J.K., George, S.C., Hamilton, P.J., and Tingate, P., 1998, Proterozoic 

source rocks—Sedimentology and organic characteristics of the Velkerri 

Formation, Northern Territory, Australia: American Association of Petroleum 

Geologists Bulletin, v. 82, no. 3, p. 442–463.

Yang, B., Smith, T.M., Collins, A.S., Munson, T.J., Schoemaker, B., Nicholls, 

D., Cox, G., Farkas, J., and Glorie, S., 2018, Spatial and temporal variation 

in detrital zircon age provenance of the hydrocarbon-bearing upper Roper 

Group, Beetaloo Sub-basin, Northern Territory, Australia: Precambrian 

Research, v. 304, p. 140–155.

ISSN 2327-6916 (print) ISSN 2327-6932 (online) https://doi.org/10.3133/fs20193013