CO2 Exsolution – challenges and Opportunities in Subsurface Flow Management

Abstract

This paper summarizes the results of a 4-year study regarding the implications of CO₂ exsolution on geological carbon storage security and subsurface flow management, including core-flood experiments, micro-model studies, pore-scale modeling, and relative permeability calculations. When separate phase CO₂ exsolves from carbonated water in sandstones, water relative permeability drops significantly. The relative permeability of exsolved CO₂ is disproportionately reduced compared to drainage due to the dispersed morphology of exsolved CO₂ bubbles in the pore space. Our studies suggest that CO₂ exsolution provides an opportunity for mobility control in subsurface processes. The low mobility of exsolved CO₂ suggests that risks of groundwater contamination due to this phenomenon are small.