Modelling provides insights into geothermal systems
15 November 2012
Geoscience Australia scientists have developed a new and innovative modelling tool that will help improve the understanding of how Australian geothermal systems work. This new tool maps geothermal potential using existing geological data sets, to fill in the gaps of currently sparse temperature data sets.
A range of geological scenarios were modelled, varying the size, geometry and thermal properties of granite, upper crust and overlying sediment. These properties were set within the context of existing knowledge of their natural ranges developed over many decades of geological mapping within Australia.
The scientists at Geoscience Australia were able to use the supercomputer at the National Computational Infrastructure facility hosted by the Australian National University, which along with new software, meant that more than half a million models were able to be run. Using the supercomputer not only sped up the modelling and interpretation process, but allowed the models to be calculated at much greater resolution than previously possible.
Geoscience Australia’s Dr David Lescinsky said the results of the modelling indicate that the temperature at depth during a simulation was largely found to be a function of the size of the granite body, the rate of heat production of the granite, and the thickness and thermal conductivity of the overlying insulating sediment layer.
The interpretation process focussed on identifying the most geologically favourable conditions for achieving temperatures of 160°C, and at depths shallower than three kilometres. This is the temperature and depth which are considered to be optimal for economic utilisation of geothermal resources.
Dr Lescinsky noted that the modelling results suggest that exploration efforts should focus on mapping granites bodies with high heat production values buried beneath sediments of high insulating value.
The next step is to apply the new knowledge to identify areas of highest potential for geothermal energy throughout Australia. The modelling provides better understanding of what key parameters exploration efforts need to focus on, such as a minimum size of granite, and the minimum thickness of sedimentary insulator for required temperature at depth.
Details of the geothermal modelling study will be presented at the Australian Geothermal Energy Conference which is being held in Sydney this week.
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