Sorption Characteristics of CO₂ on Rocks and Minerals in Storing CO₂ Processes

Abstract

As CO₂ is injected into pore spaces of water-filled reservoir rocks, it displaces much of the pore fluids. In short terms (several to tens of years), the greater part of the injected CO₂ is predicted to stay as free CO₂ , i.e. in a CO₂ rich dense phase that may contain some water. This paper investigates the sorption characteristics for rocks (quartzose arenite, greywacke, shale, granite and serpentine) and minerals (quartz and albite) in the CO₂ rich dense phase. The measurements were conducted at 50°C and 100°C, and pressures up to 20 MPa. Our results demonstrated that significant quantities of CO₂ were sorbed with all the samples. Particularly, at 50°C and 100°C, quartzose arenite showed largest sorption capacity among the other samples in higher pressures (>10 MPa). Furthermore, comparison with model prediction based on the pore filling model, which assumed that CO₂ acts as filling pore spaces of the rocks and minerals, suggested the importance of the sorption mechanism in the CO₂ geological storage in addition to the pore-filling mechanism. The present results should be pointed out that the sorption characteristics may have significant and meaningful effect on the assessment of CO₂ storage capacity in geological media.