The Geothermal Energy Potential of the West Onshore Canning Basin, Western Australia

Abstract The energy transition and advances in geothermal energy exploitation have revitalized interest in geothermal power in Australia, evidenced by a rebound in geothermal energy exploration acreage releases by several states and subsequent industry uptake. The natural, regenerative heat of the earth is a practically limitless pool of energy without the intermittency of other sources of renewable energy. Advancements in geothermal technology are dismantling the geological barriers that have limited its adoption. These innovations, primarily derived from unconventional petroleum drilling and completion techniques, have directed geothermal investigation towards Enhanced Geothermal Systems (EGS) in hot dry rocks (HDR), particularly crystalline basements. In 2023, the Department of Energy, Mines, Industry Regulation and Safety (DEMIRS) awarded six geothermal exploration permits (GEP), with two of these located in the northwest of Western Australia within the onshore Canning Basin. The onshore Canning Basin consists of Ordovician to Cretaceous sediments up to 18 km thick overlain on a Proterozoic-Archean basement of varying composition. The Area of Investigation (AOI) for this study encompasses over 66 000 km2 of the west onshore Canning Basin; namely the Broome Platform and Willara Sub-basin in addition to the Munro Arch and Mowla Terrace. The USGS's volumetric heat-in-place (HIP) calculation methodology was utilized to quantify the geothermal resource size of the west onshore Canning Basin using a fit-for-purpose basement model from existing sparse geological and geophysical datasets. The P90 HIP across the AOI was determined to be 5.5x107 PJ with an average of 830 PJ/km2. The region of most prospective basement HIP was found to be the southwestern edge of the Willara Sub-basin with the majority of HIP highs measured across the AOI primarily driven by shallow basement, at depths less than 500 m. Volumetric estimations of energy recovery are premature in this study due to the sparse datasets available in the calculation. To determine a recoverable power quantity further studies and exploration well drilling with flow testing needs to be undertaken.