Migration of carbon dioxide in sandstone under various pressure/temperature conditions: From experiment to simulation

The pressure and temperature of a target CO2 storage reservoir can significantly affect the migration and relative permeability characteristics which can ultimately determine the carbon storage capacity and storage integrity of target formations. To understand these impacts, a CO2 core‐flooding experiment was conducted on a brine‐saturated sandstone containing a single clay interlayer perpendicular to the flow direction at a temperature of 313 K and a pressure of 8 MPa and the fluid distribution was monitored by a high‐resolution X‐ray computed tomography (X‐CT) scanner. Further, a one‐dimensional model was established to reproduce the CO2 flow behavior inside the sample under the same experimental condition and then the model was extended to different temperatures (313 and 350 K) and pressures (6, 8, 12, and 17.4 MPa). The experimental results show that the CO2 preferentially created high‐CO2‐saturation flow pathways which then expanded until they were large enough to transport the CO2 at the prescribed flow rate. The sub‐core scale heterogeneity also had significant effects on the CO2 migration, forming a barrier to downstream flow. The simulation results show that at a given temperature, the CO2 front migration velocity decreased with increasing reservoir pressure while the CO2 saturation along the pathways increased. Comparing simulations when the reservoir pressure was the same, the front‐migration velocity increased with increasing temperature, and the CO2 saturation along the pathways decreased. Meanwhile, the influence of temperature and pressure on CO2 saturation distribution was more evident in the parts of the core with high residual brine saturation. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.