A New Device for Measuring the Supercritical CO₂ Permeability in Porous Rock at Reservoir Conditions

CO₂ sequestration in geological formation is a promising approach for reducing the emission of anthropogenic CO₂. In CCS (CO₂ capture and storage) projects, understanding the permeability of supercritical CO₂ in porous rock is of great significance in predicting the migration and evaluating the long-term stability of injected CO₂. This paper describes a new developed device for measuring the CO₂ permeability coefficient in porous rock at reservoir conditions, in which the pressure and temperature of injected CO₂ are usually beyond the critical point of 7.8MPa and 31.8°. The device consists of a pressure cell, a syringe pump of CO₂, a pressure amplifier, a heating unit, and a measurement system. Two buffer tanks are set at the inlet and outlet of the seepage room respectively to keep the injection and back pressures of CO₂ stable during the test. The supercritical CO₂ flowing through the rock sample is depressurized to gaseous phase to measure its flow rate under a lower pressure condition. An average flow rate over a period of time is used to calculate the permeability coefficient of CO₂ in rock sample. An application example using a siltstone for testing proves that the device can measure the permeability coefficient of supercritical CO₂ in porous rock effectively.