2608 Evaluation of CO_2 sorption behavior of rocks using volumetric method for CO_2 geological sequestration
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It is an important step to understand the capacity of host reservoir rocks for CO_2 storage in order to assess the potential of CO_2 geological sequestration. In this study, CO_2 sorption capacity of rocks (granite and sandstone) under air dry and water saturated conditions was evaluated experimentally at temperatures of 33, 40 and 50℃, and pressures up to 20 MPa using a volumetric method. As a result, sorption isotherms for CO_2 showed that the CO_2 sorption capacity of both the rocks increased with the increasing CO_2 pressure, and decreased with the increasing temperature under both the air dry and water saturated conditions. The amount of CO_2 sorption are significantly larger than theoretical value based on a solubility model, which assumes that CO_2 injected within water-filled reservoir will dissolve into pore water. These CO_2 sorption capacities could not fully be explained by CO_2 dissolution in water alone. Furthermore, it has been shown very interestingly that the amount of CO_2 sorption measured for the air dry condition was close to that obtained for water saturated condition. The amount of CO_2 sorption for the sandstone is approximately two times larger than that of the granite. This investigation may point out the significance of CO_2 sorption onto rock minerals for the possible mechanism in CO_2 geological sequestration.
