The Significance of CO2 Solubility in Geothermal Reservoirs

Abstract

Carbon Dioxide (CO2) has been considered as a possible working fluid in Engineered Geothermal Systems (EGS). This scenario would have the two-fold advantage of providing renewable electricity generation with simultaneous CO2 sequestration via subsurface fluid loss. In order to entertain this idea seriously, it is necessary to consider the interactions between CO2 and the reservoir rock and connate fluid. The laboratory experiments and theoretical work performed to date were designed to investigate thermodynamic effects that may occur when solubility is taken into account. A core-scale experiment measured relative permeabilities in the two-phase system, a micromodel experiment qualitatively observed the dynamic dissolution phenomenon, and theoretical analyses put findings in context and provided a framework to predict results under varied conditions.

The purpose of this research is to analyze and quantify the magnitude of dissolution effects via laboratory and theoretical work. An additional goal is to evaluate the time and length-scales of dissolution and diffusion effects relative to standard hydrodynamic behaviors.