A range of potential resource plays exist in South Australian basins, including shale gas, shale oil, tight gas and gas from coal, via deep coal seam gas (CSG), in situ gasification and surface syngas processes on mined coal. Exploration of these new plays is at a relatively early stage, however significant potential exists and research by explorers, the University of Adelaide and the Department of Energy and Mining to understand and evaluate new plays is progressing. Commercial recovery of gas from unconventional reservoirs requires detailed understanding of reservoir and regional geology, new fracture stimulation technologies and reservoir engineering.
Natural gas trapped in deep unconventional reservoirs (shale, siltstone, tight sandstone and coal) is a new focus for exploration in the SA Cooper Basin, spurred on by emerging export markets for gas as Liquefied Natural Gas (LNG).
At this early stage, the South Australian Cooper Basin Joint Venture (operated by Santos) and Beach Energy have established contingent gas resources in unconventional reservoirs totalling 4.6 TCF (trillion cubic feet) in the SA Cooper Basin. Contingent resources are potentially recoverable but not (yet) considered commercial due to a lack of gas marketing arrangements, and/or to technical, environmental or political barriers. This compares to the ~5.2 TCF sales gas produced from the SA Cooper Basin since 1970. However unconventional gas exploration has only just begun and undiscovered resource estimates are much higher. Beach has stated there is potential for at least 15 to 20 TCF recoverable gas in PEL 218. Santos estimates for the SACB JV licences range from a low of 22 TCF to a high of 187 TCF of raw recoverable gas.
In the SA Otway Basin in 2014 Beach Energy (operator) and Cooper Energy, drilled two deep gas exploration wells, Jolly 1 and Bungaloo 1. Beach reported encouraging results from the wells and that they have identified both deep conventional, as well as unconventional targets.
Tri-Star has been exploring in situ gasification of coal in the Walloway Basin, and for CSG and shale oil in the Arckaringa Basin.
There has been no exploration drilling for unconventional plays in other frontier basins in the State as yet, although prospective shale units are present in the State’s Neoproterozoic-Cambrian basins and prospective coals and shales exist in the Simpson and Pedirka basins.
The geologic attributes and potential extent of unconventional gas plays in the Cooper, Arckaringa, Otway, Gambier, Pedirka, Warburton and Officer basins are described in Chapter 2 of the "Roadmap for Unconventional Gas Projects in South Australia".
