Mesoproterozoic Beetaloo Sub-basin

The sub-surface Beetaloo Sub-basin lies within the McArthur Basin and comprises thick sequences of sedimentary and minor volcanic rocks assigned to the following stratigraphic groups or their equivalents: the Palaeoproterozoic Tawallah and McArthur groups, and the Mesoproterozoic Nathan and Roper groups, which hosts the majority of petroleum occurrences.

Information on the geological setting of the McArthur Basin can be found in the McArthur Basin inventory.

Exploration focussed on the shale plays of the Beetaloo Sub-basin has greatly accelerated since 2010 with a number of discovery wells drilled by Origin Energy, Imperial Oil and Gas Pty Ltd, Pangea Resources Pty Ltd, Falcon Oil and Gas Australia Ltd, Santos Ltd and Amour Energy Ltd. Exploration has again rapidly accelerated since 2021 with a number of companies including Empire Energy Ltd, Tamboran Resources Ltd (and Santos Ltd) and Falcon Oil and Gas Australia Ltd (and Origin Energy) announcing significant increases in contingent resources.

Further exploration history can be found in the McArthur Basin inventory.

Petroleum

The Beetaloo Sub-basin is the Northern Territory’s premier shale gas play, with prospectivity increasing as exploration accelerates. The Beetaloo Supersystem contains at least four conventional and unconventional petroleum systems with substantial shale gas resources primarily within the Mesoproterozoic Roper Group. The most prospective shale units in the Roper Group occur within the Velkerri and Kyalla formations. Drilling of the middle Velkerri Formation has demonstrated the consistent presence of gas saturated, quartz-rich shale source rocks that are mature for gas over extensive areas, and which appear to meet all of the physical and chemical parameters for a successful shale gas play (see Revie 2017). The shallower Kyalla Formation also has high potential as a productive shale play, with large areas within the wet gas window.

Download the Shale gas and liquids factsheet PDF (3.2 MB). Additional petroleum potential can be found in the McArthur Basin inventory.

Other energy potential

Minor hydrogen gas shows have been historically recorded from the Beetaloo Sub-basin.

Mineral commodities

For an overview of the mineral prospectivity view the Geology of the Northern Territory Chapter 15 McArthur Basin.

Exploration and appraisal continue to accelerate with Contingent Resources (2C) growing and a number of wells undergoing appraisal by key operators in the Beetaloo Sub-basin.

The following table contains publicly announced best estimate of Contingent Resources (2C) in the advanced Beetaloo Sub-basin in accordance with the SPE-Petroleum Resources Management System. For a summary of Prospective Resources (P50) in the Beetaloo Sub-basin, download the Shale gas and liquids factsheet PDF (3.2 MB)

Additional resources can be found in the McArthur Basin inventory .

Santos Ltd have exploration tenure in the eastern Beetaloo Sub-basin in joint venture with Tamboran Resources Ltd. Following flow-testing by Santos at the Tanumbirini-2H and Tanumbirini-3H horizontal wells in EP161in 2022, Tamboran Resources announced in June 2023 that modelling of the production curves by an independent third-party yielded a 20-year Estimated Ultimate Recovery of ~16.8–18.5 billion cubic feet (Bcf) for a proposed ~3000 m development-scale well. In September 2022, the Unrisked 2C Contingent Gas Resource for EP161 is 1.617 trillion cubic feet (Tcf) gas. The wells were suspended in early 2023 with no further drilling or testing occurring on EP161.

Empire Energy Group Ltd continued drilling and flow-testing of wells in EP187 on the eastern margin of the Beetaloo Sub-basin. During the first half of 2023, Carpentaria-2H horizontal well, 11 km north of the Carpentaria-1 well, was reopened for extended production testing and flowed for a period of 76 days. The well produced high calorific gas at an average rate of 2.2 million cubic feet per day (mmscfd), with a final rate of 1.6 mmscfd. Following a 5 month shut-in, the Carpentaria-3Hwell, located adjacent to Carapentaria-2H, underwent extended production testing in mid-2023. The well had been drilled in late 2022 to a total depth of 4460 m, with a total horizontal section length of 2632 m of which 2374 m was within the target Velkerri-B shale. Over the 63-day duration of the second phase testing, the well averaged a flow rate of 2.7 mmscf per day, with a final rate of 2.0 mmscf per day. Following production testing, production results of both Carpentaria-2H and C-3H were being reviewed for ongoing optimisation of future fracture stimulation programs. In May 2023, Empire Energy announced a 270% increase in the 2C Contingent Resources for EP187 to 1.467 Tcf.

In December 2023, Empire Energy announced it had acquired AGL Ltd’s Rosalind Park Gas Plant in order to accelerate the path to Carpentaria Pilot Project production and reduce the capital expenditure required to commence gas sales. The company announced that they are focused on progressing the Pilot Project towards a final investment decision, targeting a sales gas production rate of up to 25 terajoules (TJ) per day utilising the existing McArthur River Pipeline.

Tamboran Resources, in joint venture with Bryan Sheffield and Falcon Oil and Gas Ltd, is the operator on three permits in the central part of the Beetaloo Sub-basin (EP 98, 117 and 76). In the first half of 2023, Tamboran stimulated and flow-tested the Amungee 2H development well, 60 km east of Daly Waters, which was drilled in late 2022 to a total depth of 3883 m, including a 1275 m horizontal section. The company commenced fracture stimulation of the well across 24 stages in February 2023. The well achieved gas breakthrough, but modelling and independent third-party analysis of fluids recovered from the well identified potential skin inhibiting gas and water flow, with average gas flow rates of 0.97 mmscfd over the first 50 days of testing. In late September 2023, Tamboran commenced drilling the Amungee 3H well, which was drilled to a total depth of 3837 m in 17.9 days, including a 1150 m horizontal section within the Mid Velkerri B Shale.

In August 2023, Tamboran Resources commenced drilling of the Shenandoah South 1H well in EP117, which reached a total vertical depth of 3300 m, intersecting ~90 m of Mid-Velkerri B-shale with strong gas shows. In February 2024, Tamboran announced that the well achieved an average 30-day initial production (IP30) flow rate of 3.2 mmscfd over the 501 m, 10 stage stimulated length within the Mid Velkerri B Shale, normalized to 6.4 mmscfd over 1000 m, Testing was carried out following the installation of production tubing and a three-week soaking period to allow for water used in the stimulation process to be absorbed by the shale. This was the highest normalised flow-rate achieved in the Beetaloo Sub-basin to date.

Based on the result from the Shenandoah South 1H well, Tamboran announced the company has confidence to progress the proposed 40 mmscfd Pilot Project in the Shenandoah South region. Tamboran is targeting first production from the project in first half 2026, which is expected to deliver volumes into the Territory gas market over a 10-year plateau period, subject to completion of a binding Gas Sales Agreement, construction of necessary midstream infrastructure, and funding and key stakeholder approvals. The proposed Pilot Project is planned to include six upfront development wells drilled to 3050 m to achieve plateau production, as well as the construction of compression facility and a 35 km pipeline link to the Amadeus Gas Pipeline.

EP258 was granted to Top End Energy Ltd. the first new permit granted in the Territory since 2015.

See onshore exploration activity .

The Beetaloo Sub-basin has the most extensive seismic coverage of all NT onshore basins and concentrated exploration wells drilled.

Open file petroleum company reports and all NTGS data and information on the Beetaloo Sub-basin is available from the GEMIS website.

Ahmad M, Dunster JN and Munson TJ, 2013. Chapter 15: McArthur Basin: in Ahmad M and Munson TJ (compilers) ‘Geology and mineral resources of the Northern Territory’. Northern Territory Geological Survey, Special Publication 5

Jarrett AJM,  Munson TJ, Williams B, Bailey, AHE, Palu, T, 2022. Petroleum supersystems in the greater McArthur Basin, Northern Territory, Australia: prospectivity of the world’s oldest stacked systems with emphasis on the McArthur Supersystem, The APPEA Journal 62

Munson, TJ, 2014 NTGS Report 22: Petroleum geology and potential of the onshore Northern Territory

Northern Territory Geological Survey,  2017. Overview of known conventional and unconventional petroleum potential in the Northern Territory, Information brief for the Scientific Inquiry into Hydraulic Fracturing in the Northern Territory

Williams, B, 2019, NTGS Record 2019-015: Definition of the Beetaloo Sub-basin

Williams B, 2020. Definition of the Beetaloo Sub-basin in AGES 2020 Conference Proceedings. Northern Territory Geological Survey