Modelling Supercritical Geothermal Flows Using TOUGH2

Abstract

There is growing interest in the development of deep geothermal resources, and a related need for models of them. At the high pressures and temperatures found in such systems, supercritical conditions can occur, which most numerical geothermal simulators are not presently capable of modelling. This paper describes a new modified version of the TOUGH2 simulator, capable of modelling supercritical conditions. The modifications are based around the updated IAPWS-97 thermodynamic formulation, and the use of density and temperature as primary thermodynamic variables under supercritical conditions. Results from a suite of test problems are in agreement with the work of other authors. This gives confidence that the simulator can be used for modelling deep geothermal reservoirs.