Advanced exploration

The McArthur Basin, Beetaloo Sub-basin and onshore Bonaparte Basin contain contingent gas resources and are at a relatively advanced stage of exploration.

All have reported gas discoveries and have relatively good seismic and well coverage.

To  view the distribution of petroleum wells and seismic lines across these basins  and to download attributed spatial data, please visit the Northern Territory Geological Survey's (NTGS) online web mapping  system STRIKE.

The McArthur Basin contains a number of petroleum systems, with most activity to date focussing on the late Palaeoproterozoic McArthur Group and Mesoproterozoic Roper Group (Beetaloo Sub-basin).

McArthur Basin: McArthur Group

Conventional and unconventional gas and oil resources have been the target of exploration in the McArthur Group within the Batten Fault Zone in the southern McArthur Basin. The Barney Creek Formation is a significant source rock and shale gas and -oil prospect. Conventional gas is also reservoired in relatively low-permeability rocks in the Lynott Formation and Reward Dolostone.

In 2012, Armour Energy Ltd reported gas in Cow Lagoon-1 and Glyde-1 ST1, and this was followed-up by significant oil and gas shows in Lamont Pass-3 in 2013.

In 2013, Armour Energy announced a 2C Contingent Resource of 6.0 bscf of gas from the Glyde-1 well. The resource is a shallow conventional accumulation reservoired in brecciated Coxco Dolostone Member of the Teena Dolostone underlying Barney Creek Formation source rocks within the Glyde sub-basin.

Reports and data

A more detailed description of the petroleum potential of the McArthur Basin can be found in NTGS Report 22.

Petroleum wells in the McArthur Basin are largely focussed on the Mesoproterozoic Roper Group stratigraphy within the Beetaloo Sub-basin and the Palaeoproterozoic McArthur Group stratigraphy across the McArthur Basin.

Open file petroleum company reports and all NTGS data and information on the McArthur Basin is available from the GEMIS website.

Roper Group petroleum occurrences are primarily located within the sub-surface Beetaloo Sub-basin.

This represents a structural sub-basin of the McArthur Basin that preserves the thickest sequences of highly prospective Mesoproterozoic Roper Group stratigraphy. The Sub-basin is the Northern Territory’s (NT) premier shale gas play, with substantial shale gas resources in place.

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.

Wells drilled to date by industry indicate a P50 Gas-In-Place Resource for the Velkerri B-shale alone of at least 500 Tcf, with the additional potential for liquids-rich gas in the basin. Following the successful hydraulic fracturing and production testing of the Amungee NW-1H well in 2016 (see Close et al 2017), Origin Energy announced a 2C Contingent Gas Resource Estimate of 6.6 Tcf of gas for the "B shale" member of the Velkerri Formation.

With the 2018 lifting of the moratorium of hydraulic fracturing in the NT, shale gas exploration and appraisal of the sub-basin recommenced in 2019.

Reports and data

The Beetaloo Sub-basin has the most extensive seismic coverage of all NT onshore basins and has had 20 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.

The Bonaparte Basin contains up to 15km of Phanerozoic, marine and fluvial, siliciclastic and carbonate sedimentary rocks with the thickest sections being offshore. The basin is a well established oil and gas province, with proven resources and a number of currently producing fields in offshore areas.

The onshore Bonaparte Basin in the NT contains the Weaber gas field, and oil and gas shows have also been recorded from a number of other wells. In 2011, MEC Resources, on behalf of its investee company Advent Energy Ltd, announced a 2C Contingent Resource of 11.5 bscf of natural gas at Weaber  field within Retention Lease RL-1 . The gas-bearing reservoirs are interpreted to be the Enga Sandstone of the Langfield Group within a faulted anticlinal trap.

The Keep River-1 prospect was a gas discovery that flowed a small but significant amount of gas to surface on test. Gas shows were reported from multiple fine- to medium-grained sandstones interbedded with shale in the lower Milligans Formation and from fractures within the Late Devonian succession.

Reports and data

The onshore Bonaparte Basin is covered by nearly 1,800km of 2D seismic and 13 petroleum wells. A more detailed description of the petroleum potential of the onshore Bonaparte Basin can be found in NTGS Report 22.

Open file petroleum company reports and all NTGS data and information on onshore Bonaparte Basin is available from the GEMIS website.