Permeability, selectivity and distinguishing criterion of silicone membrane for supercritical CO2 and N2 in the porous media

The possibility of leakage of CO2 from a geological storage reservoir is of serious concern to stakeholders. In this work, high–pressure-temperature laboratory experiments were performed to demonstrate the application of a silicone membrane-sensor system in the monitoring of subsurface gases, especially in the leakage scenario. Mass permeation, membrane resistance to gas permeation, and the gas flux across the membrane are reported for two gases, namely, CO2 and N2. Mass permeation of CO2 through the membrane was more than ten times higher than that of N2, under similar conditions. It was also found to increase with the geological depths. The gas flux remains higher for CO2 as compared to N2. From the results, a simple criterion for distinguishing the presence of the different gases at various geological depths was formulated based on the rate of permeation of gas through the membrane. Results and techniques in this work can be employed in the detection/monitoring of subsurface gas transport, especially in geological carbon sequestration.