Impact of porous medium desiccation during anhydrous CO2 injection in deep saline aquifers: up scaling from experimental results at laboratory scale to near-well region

Injection of CO2 in geological reservoirs or deep aquifers is nowadays studied to regulate the global warming by limiting the amount of greenhouse gases emitted by human activity into the atmosphere. CO2 is captured from exhaust gas in power plants or industrial units and then stored in underground geological reservoirs. The experience available in the oil industry concerning CO2 injection clearly shows that injectivity problems can occur due to several mechanisms like mineral dissolution but also physical alteration due to complete water desaturation of near wellbore through drying. This study presents experimental evaluations of drying of brine in sandstone samples and numerical modelling of the saturation profile evolution with two phase flow model integrating thermal effects. An up scaling/extrapolation of experimental results at laboratory scale to near-well zone is proposed highlighting the key role of injection flow rate and capillary properties on the desiccation mechanisms.