In order to produce electricity from geothermal energy, high temperatures (typically around 200°C or more) are needed at less than about five kilometre depth. The Geothermal Energy Project is involved in numerical modelling to predict temperatures at different depths in order to help determine what parts of Australia might be the most prospective for geothermal energy usage.
The important parameters for a geothermal play include a heat source and rocks with low thermal conductivity covering the heat source to trap the heat. In Australia, the most important heat source is natural radioactive decay of uranium (U), thorium (Th) and potassium (K) in granites, which often have high concentrations of these elements compared with other rocks.
The Geothermal Energy Project is involved in region specific modelling of areas across Australia, as well as synthetic modelling, which looks at the geothermal potential of common geological scenarios. Both types of modelling involve construction of a 3D geological model, and determination of the temperature distribution resulting from that model.
The geothermal project is also carrying out forward gravity and thermal modelling on various common geological scenarios to investigate the importance of different parameters associated with geothermal plays. Parameters being investigated include:
- volume, depth extend and radius of granite in basement
- concentration of U, Th and K in the granite, which influences the rate at which it produces heat
- thermal conductivity and thickness of overlying sediments
- effect of folding of rock layers.
In doing synthetic modelling, each parameter is modified individually, so that the effect of different parameters can be unambiguously identified. The results can then be plotted and interrogated by explorers in a ‘first pass’ investigation of an area.
Regional study - Cooper Basin
The Cooper Basin is located in South Australia and is known to contain rocks of high temperature at shallow depths. Because it has also been targeted for petroleum exploration, there is a wealth of data available in the area so that the geological and thermal structure is very well known. This study location was chosen by the Geothermal Energy Project so that new methods could be trialled and tested against real data.
Topic contact: firstname.lastname@example.org Last updated: April 2, 2013