| Abstract |
The objective of our research program is to improve the productivity of geothermal operations and exploration by developing computer modeling technologies which accurately characterize the chemistry of many important geothermal systems and energy production processes. Our thermodynamic models are based on equations of state (EOS) which describe the free energy of gas-solid-water systems for wide ranges of temperature, pressure and composition. Different EOS approaches are used to treat aqueous systems under upper crustal conditions, where temperatures are below 300?C and pressures close to one atmosphere, and deep crustal/mantle systems which can reach supercritical conditions. The former incorporates the Pitzer electrolyte theory. New EOS, incorporating methodology such as the corresponding states and one fluid assumption or thermodynamic perturbation theory, are used to treat the increased compressibility of brines as T,P conditions near and surpass the critical region. To model XTPV space with few experimental data, molecular dynamics simulated ìdataî are used to constrain the behavior of the free energy. Models constructed using these different approaches can reliably reproduce downhole chemistry, chemical behaviors encountered during energy extraction, such as scaling, flashing and miscibility, and the high temperature and pressure chemistry associated with deep reservoirs that will be tapped in the future. Our research program emphasizes effective transfer of our technologies. We have developed application software to facilitate the use of our modeling codes. A website now in development will expedite code distribution. Visualization postprocessing code, which takes advantage of internet capabilities, will process model calculations and display them in ways which help improve the fundamental understanding of the chemical phenomena occurring in present and future geothermal systems. |