Stable Isotope Partitioning in Brine-Gas-mineral Systems Relevant to Geothermal Resources

Abstract

We present an overview of our experimental program investigating the kinetics and equilibrium of isotope partitioning in the systems: liquid-vapor, C-O-H gases, and mineral-water, conducted at Oak Ridge National Laboratory. Our research demonstrates that not only temperature, but also pressure and fluid composition, are key variables in determining equilibrium isotope partitioning between water and other materials at elevated temperatures. The kinetics of isotopic exchange in C-O-H gases and mineral-water is controlled by many other factors (grain size, mineral catalysts, fracturing in rocks). Our new, precise data on isotope fractionation, both kinetic and equilibrium, are useful for the interpretation and modeling of isotopic data from various geothermal systems.