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NSW geothermal project

In response to renewed interest in geothermal exploration, the Geological Survey of NSW (GSNSW) commissioned new modelling and analysis to improve the understanding of geothermal prospectivity across NSW. Built on previous geothermal studies by the GSNSW dating back over 2 decades, the project delivers key results within a report that is accompanied by a statewide geothermal data package.

Thermal map of NSW showing variations in temperature from the top of basement

Project overview

The project incorporated new seismic data, 3D modelling, wells and petrophysical data into a new methodology for predicting heat flow and crustal temperatures. GSNSW engaged Geognostics Australia Pty Ltd to deliver revised mapping of the geothermal potential in 3 prospective areas in NSW, the Murray–Darling, Sydney–Gunnedah–Bowen and Clarence–Moreton basins. 

The project delivers a summary report by the GSNSW, and 4 companion reports by Geognostics:

  • Geothermal prospectivity of NSW 
  • NSW SEEBASE report 
  • Murray–Darling–Oaklands basins geothermal modelling report 
  • Sydney–Gunnedah–Bowen basins geothermal modelling report 
  • Clarence–Moreton Basin geothermal report 

The 3 basin reports include:

  • basement heat flow
  • total/surface heat flow
  • temperature at top basement
  • geothermal gradient
  • predicted temperatures at 1, 2, 3, 4 and 5 km depths
  • atlas-style report
  • summary of model confidence
  • simplified model of basin stratigraphy

The reports can be downloaded from DIGS and the data packages from Geoscience data packages.

Key findings

The Murray–Darling, Sydney–Gunnedah and Clarence–Moreton basins were modelled with predicted temperatures over 100°C, between depths of 2–3 km, and are considered prospective for geothermal energy.

  • Sydney–Gunnedah–Bowen Basin – the central Sydney Basin and Munmorah area has sufficient sediment cover for predicted temperatures to exceed 100°C within moderate drilling depths.
  • Clarence–Moreton Basin – high predicted temperatures (~120°C and higher) at moderate to deep drilling depths in the northeastern Lismore Trough and southwestern Grafton Trough.
  • Murray–Darling Basin – temperatures of >100°C at depths of 2.5 to 3.0 km and deeper across significant portions of the Darling Basin troughs.

Exploration opportunities
NSW is underexplored for geothermal energy. This new modelling and analysis, in conjunction with ongoing improvements in drilling technology and improved or novel engineering solutions to tap into geothermal energy increases the opportunites for exploration success. 

Strategic industry relevance
Geothermal energy has the capacity to provide scalable, dispatchable base load power to the electricity grid without the carbon footprint of fossil fuel generated electricity. Furthermore there is key geothermal prospectivity along the eastern seaboard where the majority of electricity in NSW is consumed.

Conclusion

NSW is considered prospective for geothermal resources that may be suitable for electricity generation. NSW is well placed to supply markets, leveraging the mining and industrial capabilities available, in conjunction with supportive government policy.