The five conventional assessment units of the Eromanga Basin Province. USGS; base from the National Park Service.
As part of its assessment of the world's priority geologic provinces, the U.S. Geological Survey estimated the undiscovered, technically recoverable conventional oil and gas in the Cooper and Eromanga Basins of Australia, using a geology-based method.
The basins
- Stacked basins: by Australian convention, a basin is a set of related rock layers bounded by unconformities, so basins can sit on top of one another. Here the Warburton (Cambrian–Devonian), Cooper (Permian–Triassic), Eromanga (Jurassic–Cretaceous) and Lake Eyre (Tertiary) basins are stacked, each larger than the one below.
- The province: for this assessment, the Eromanga Basin Province covers the Cooper and Eromanga Basins.
- A mature area: more than 500 conventional oil and gas fields have been found since the 1960s, so most undiscovered fields are expected to be small, in stratigraphic or combined structural-stratigraphic traps.
The petroleum system
The USGS defined a Cooper-Eromanga Composite Total Petroleum System, with Permian and Jurassic coals as the main source rocks. Oil and gas generated mostly from those coals migrated into Permian through Cretaceous reservoirs. Five assessment units (AUs) were defined — three in the Cooper Basin, where most known gas fields are, and two in the overlying Eromanga Basin, home to most oil fields.
Results
| Mean | Range (F95–F5) | |
|---|---|---|
| Oil | 68 million barrels | 39–108 million |
| Gas | 964 billion cubic feet | 509–1,633 billion |
| Natural gas liquids | 19 million barrels | 9–34 million |
Where it is
| Assessment unit | Mean undiscovered (F95–F5) |
|---|---|
| South Eromanga Basin Mesozoic Conventional Reservoirs | oil 48 million barrels (28–75) |
| North Eromanga Basin Mesozoic Conventional Reservoirs | oil 20 million barrels (11–33) |
| Greater Nappamerri Trough Permian Conventional Reservoirs | gas 365 billion cubic feet (226–540) |
| Queensland Troughs Permian Conventional Reservoirs | gas 290 billion cubic feet (135–525) |
| Greater Patchawarra Trough Permian Conventional Reservoirs | gas 112 billion cubic feet (40–244) |
The three Permian units of the Cooper Basin hold about 80 percent of the undiscovered conventional gas; all the oil is in the two Eromanga units.
F95 means a 95 percent chance of at least that amount; F5, a 5 percent chance.
Sources
Based on Assessment of Undiscovered Conventional Oil and Gas Resources of the Cooper and Eromanga Basins, Australia, 2016, by the Eromanga Basin Province Assessment Team (Christopher J. Schenk and others), USGS Fact Sheet 2016–3028, U.S. Geological Survey (DOI), citing Menpes and Hill (2012), IHS Energy (2015), Apak and others (1997), Boult and others (1997) and Lowe-Young and others (1997); a work of the United States government in the public domain. The map comes from the fact sheet's PDF. Full results: the USGS Energy Resources Program.
Licence: CC0 1.0 (public domain) · Adapted from pubs.usgs.gov
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