Abstract
Carbon dioxide (CO2) geological sequestration is an immediately available and technologically feasible method to achieve a substantial reduction in CO2 emissions to the atmosphere. Injected CO2 permeates in deep saline aquifers from the injection point and CO2 migrates upward. In order to evaluate the storage site and assess the CO2 leakage risks and storage costs, fundamental visualization and study of immiscible two-phase flow in sandstone are required. The behavior of CO2 in water-saturated Berea sandstone has been observed using a microfocus X-ray computed tomography with high spatial resolution. Three dimensional CO2 distribution was clearly reconstructed, and the effects of the sandstone micro-heterogeneity was noted. Bedding structure strongly determined the CO2 permeation area, and a strong correlation was seen between the local porosity and CO2 saturation CO2 gradually permeated in the axial direction with increasing saturation in higher porosity beddings. The application of these observations to CO2 sequestration in deep saline aquifers is outlined.
