Characterization of dissolution process during brine injection in Berea sandstones: an experiment study

Abstract

A clear understanding of the mass transfer properties during fluid injection into porous media is of importance to the safety of CO₂ storage. In this study, several experiments were conducted to elucidate the displacement and dissolution processes of gaseous and supercritical CO₂ in Berea sandstones using the X-ray CT technology. The initial CO₂ distribution before brine injection was related to the pore structure of the sandstones. Transient images during brine injection at different flow rates showed a transformation from displacement to dissolution, and the dissolution fronts were affected by the core heterogeneity and flow rates. Then, the CO₂ saturation was determined by imaging analysis. Both supercritical and gaseous CO₂ saturation decreased sharply, meaning that dissolution dominated the flow process. The dissolution time could be correlated in terms of the flow rate, initial gas saturation and heterogeneity of the sandstone. The relationships between CO₂ volume content and specific surface area were verified to qualitatively predict the influence of heterogeneity. The dynamic concentration and mass transfer coefficient were obtained, which gave the information for the mass transfer rate during CO₂ storage.