The following is a collection of geothermal modelling demonstrators that support geothermal exploration. They include heat flow models at the regional scale, crustal heat transport by fluid flow at low temperature, a hot-dry rock simulator, and a geothermal, multiphase-fluid-transport engineering model. The collection also includes a suite of benchmarks and verification models.
Alex Musson (Melbourne), Mike Sandiford (Melbourne), Tim Rawlings (GeoScience Victoria), Steve Quenette (VPAC)
The Latrobe Valley is nestled in Victorias Gippsland Basin and provides, through large reserves of brown coal, more than 80% of the states electricity. This resource-rich region is of particular strategic importance for geothermal energy prospects and CO2 geosequestration potential in a future carbon-constrained and energy-avid economy. This initiative is to iteratively assimilate relevant portions of the 3D data models of GeoScience Victoria, for the purposes of constraining large-scale geothermal forward models of the LaTrobe Valley. The activity is to provide GSV with the opportunity to explore ways their new value added data can contribute to thermal, structural and fluid models and products to the local community. AuScope contributed an incremental / demonstrator activity that enabled the survey to embrace the powerful regional multiphysics software of Underworld.
AuScope infrastructure used
New models were being developed with Underworld.
Widespread misconceptions about geothermal energy are an impediment to its development and exploitation.
Alexander Musson (UoM), Mike Sandiford (UoM)
Description: Interpreted crustal temperatures in Australia can be translated into an extraordinary energy output of 1.9E13 Petajoules. For comparison, if only 1% of this energy could be harnessed before being lost to space, it would represent approximately 25,000 times our present annual consumption nationally. One of the biggest challenges in utilising this formidable reservoir of energy lies in defining geologically sensible prediction models in areas accessible to geothermal exploration and exploitation. A brief compilation of thermal modelling concepts exposes why conventional methods are not satisfactory in predicting the thermal properties of geothermal resources.
AuScope Infrastructure to be used: eScript
Traditionally the analysis of heat flow is considered as a one-dimensional steady-state and conductive heat transfer problem with a prescription of constant boundary conditions. This simplified view ignores transient effects and spatial variations which arise from heat and fluid transport as well as the heterogeneity and anisotropy of the geological subsurface.
Craig ONeill (Macquarie)
The Gunnedah Basin in eastern NSW is part of the Sydney-Gunnedah-Bowen Basin system, and an important economic resource for its extensive coal measures. More recently it has garnered attention for its geothermal potential, and is one of only two basins in NSW with active geothermal tenements. As part of a project at Macquarie University on the thermal structure and evolution of the Sydney-Gunnedah-Bowen Basin systems, a 3D model of the basins architecture has been developed, which combines information from over 150 exploration holes, and all available geophysical data. The Auscope-funded Underworld geothermal package has been used to simulate the thermal state of this basin, importing the geological models, and available thermal boundary constraints, to calculate the temperature of the Lachlan-foldbelt basement beneath the thick sedimentary cover.
AuScope Infrastructure used: Underworld
For more details – https://twiki.esscc.uq.edu.au/bin/view/ESSCC/CooperBasinReservoir
Hans Mhlhaus (UQ), Geodynamics Ltd
This project developed a model to predict the productive lifespan of a hot dry rock (HDR) geothermal reservoir in the Cooper Basin. The model takes in consideration the effect of the injection of cold fluid onto the temperature distribution of the rock. The first aim of this model was to provide Geodynamics Ltd. with an estimate of the time it takes for the reservoir to drop in temperature to value making an operation unviable. This will assist Geodynamics with long term planning for the site and an estimate of the revenue. The second aim of the model was to determine which well geometry configuration resulted in the longest reservoir lifespan. This will assist Geodynamics Ltd. in deciding which well geometry is the best for prolonging the lifespan of the reservoir. We considered a simplified 2.5 dimensional model, consisting of a water saturated layer of rock of infinite length in the horizontal directions that is 100m thick and intersected with faults. This section of rock is surrounded above and below by impermeable rock. The aims of this model are to observe the time taken for the temperature of the rock to decrease to 80% of the initial rock temperature and to see if the geometry of the wells’ location affects the temperature drawdown. There are two geometrical configurations that are being tested: a square and a triangular design.
AuScope Infrastructure used: eScript
Huilin Xing (UQ)
Engineered geothermal reservoir, such as Hot Dry Rock (HDR), Hot Fractured Rock (HFR) technology started from an idea to help fulfill future energy needs with the clean geothermal energy. The HDR/HFR concept itself is very simple but the development of the associated technology has taken significantly longer than anticipated. A novel supercomputer simulation tool is being developed to simulate the highly coupled geomechanical-fluid flow-thermal systems involving heterogeneously fractured geomaterials to target a new predictive modelling capacity with the potential to yield breakthroughs in understanding how to enhance the flow of fluid through the geothermal field and how to sustain it over decades such that the trapped heat energy can be extracted. It includes (1). visualising the microseismicity events recorded during a certain hydraulic stimulation process and to further evaluate the fracture location and evolution, geological setting and the reservoir permeability; (2). the finite element based numerical solution to model and evaluate a certain fractured geothermal reservoir under various affecting factors.
AuScope Infrastructure used: Extension of ESyS_Crustal with ARC Linkage grant.
Huilin Xing (UQ), Steve Quenette (VPAC)
Various computational models and codes are being applied to analyse the geothermal reservoir. However, no model manages to cover all the necessary aspects alone. The objective of this AuScope SAM initiative, is to set up a suite of verification / benchmarks, to provide community confidence in the available software. Specifically, this initiative aims to: verify that the computational algorithms can solve the geothermal governing equations accurately and efficiently; determine whether the geothermal simulator is fully operational without any major coding errors; evaluate if the governing equations can accurately describe the geothermal issues under various affecting factors evaluate the geothermal simulators capabilities for solving problems of practical interest.