Application of the computer code TOUGH2 to the simulation of supercritical conditions in geothermal systems

Abstract At the high pressures and temperatures found in deep geothermal systems, supercritical conditions can occur. Current numerical geothermal simulators are either not capable of modelling these conditions, or can do so only at significantly reduced computation speed. This paper describes modifications to the TOUGH2 simulator to extend its applicability. It employs the updated IAPWS-97 thermodynamic formulation, and uses density and temperature as primary thermodynamic variables under supercritical conditions. Results from test problems are in agreement with results produced by other simulators, giving confidence that the simulator can be used for modelling deep geothermal reservoirs.

[1]  Wolfgang Wagner,et al.  International equations for the saturation properties of ordinary water substance. Revised according to the international temperature scale of 1990 , 1993 .

[2]  H. Hardee,et al.  Superconvecting geothermal zones , 1981 .

[3]  G. M. Shook,et al.  Multi-purpose simulation , 1993 .

[4]  Lester Haar.  Nbs/Nrc Steam Tables , 1984 .

[5]  Richard J. Chalaturnyk,et al.  Adapting TOUGH2 for general equations of state with application to geological storage of CO2 , 2004, Comput. Geosci..

[6]  B. L. Cox,et al.  Numerical experiments on convective heat transfer in water-saturated porous media at near-critical conditions , 1990 .

[7]  H. Kretzschmar,et al.  The IAPWS Industrial Formulation 1997 for the Thermodynamic Properties of Water and Steam , 2000 .

[8]  S. Ingebritsen,et al.  The computer model Hydrotherm, a three-dimensional finite-difference model to simulate ground-water flow and heat transport in the temperature range of 0 to 1,200 degrees C , 1994 .

[9]  S. Ingebritsen,et al.  Fluid flow and heat transport near the critical point of H2O , 1994 .

[10]  W. Kissling.  Deep hydrology of the geothermal systems in the Taupo Volcanic Zone, New Zealand , 2004 .

[11]  H. Preston‐Thomas,et al.  The International Temperature Scale of 1990 (ITS-90) , 1990 .

[12]  E. Oelkers,et al.  SUPCRT92: a software package for calculating the standard molal thermodynamic properties of minerals, gases, aqueous species, and reactions from 1 to 5000 bar and 0 to 1000 ° C , 1992 .

[13]  James W. Johnson,et al.  Critical phenomena in hydrothermal systems; state, thermodynamic, electrostatic, and transport properties of H 2 O in the critical region , 1991 .

[14]  A. GrantM.  Permeability reduction factors at Wairakei. , 1977 .

[15]  W. Kissling,et al.  The spatial distribution of the geothermal fields in the Taupo Volcanic Zone, New Zealand , 2005 .

[16]  T. Brikowski.  Modeling Supercritical Systems With Tough2: Preliminary Results Using The EOS1sc Equation Of State Module , 2001 .

[17]  Tsuneo Ishido,et al.  Numerical investigation of production behavior of deep geothermal reservoirs at super-critical conditions , 1998 .