The Adavale Basin underlies the Galilee, Eromanga and Lake Eyre basins in central Queensland and has a sedimentary record spanning the Early Devonian to Late Devonian/Early Carboniferous. A range of depositional environments existed across the Adavale Basin, from dry alluvial plains to restricted marine embayments. The interplay of these environments over time has set up conventional and unconventional hydrocarbon opportunities, including the Gilmore gas discovery.
Hydrocarbon and other resource opportunities in the Adavale Basin are a focus of the Australian Government’s Trusted Environmental and Geological Information (TEGI) scientific program. Geoscience Australia (GA) is collaborating with CSIRO to understand areas of future resource potential and provide transparent, trusted baseline data and information to support resource development and better environmental outcomes.
Seven play intervals are assessed for resource potential in the Adavale Basin. From oldest to youngest, these are the Gumbardo, Eastwood, Log Creek, Lissoy, Cooladdi, Etonvale, and Buckabie sequences, representing distinct palynology-defined chronostratigraphic intervals.
A systematic and consistent assessment used the existing thirty-nine petroleum exploration wells and supplemented with sequence stratigraphic data were analysed in the ArcGIS ‘Player’ extension. We identified twenty-five play elements, such as reservoir, seal and charge, and the gross depositional environment interpreted for each play. Well-point maps were used to identify spatial variation in risk for each play element occurring using a split-risking methodology that represented play chance and repeatability.
Implicitly, the methodology is data-driven, rather than model-driven, and areas of sparse data results in considerable uncertainty across each play element. The reliance on well information is driven by the sparsity of seismic data across the Adavale Basin.
Risk maps for each play were generated to indicate qualitative prospectivity of the Adavale Basin. Composite common risk segment maps of the conventional hydrocarbon prospectivity outline the proven play area around the Gilmore and Log Creek gas accumulations and indicate potential for future discoveries. Two zones of unconventional hydrocarbon play potential have been identified, one around the Gilmore area extending to the northeast and the other further north, centred over the Swaylands-1 exploration well.
With further geological, geophysical and environmental information, our methodology and initial results can be used as a tool to assist policy makers to guide and prioritise areas for energy exploration, especially in identifying hydrocarbon and carbon capture and storage opportunities in the Adavale Basin.
This Abstract was submitted/presented to the 2022 Central Australian Basins Symposium IV 29-30 August (https://agentur.eventsair.com/cabsiv/).
