Fines migration and mineral reactions as a mechanism for CO2 residual trapping during CO2 sequestration

Abstract

This study investigates fines migration and mineral reactions as a mechanism for CO2 residual trapping. We perform imbibition experiments using a sintered glass core and seven Berea sandstone cores. The cores receive four injection stages: water, CO2-saturated water, water-saturated CO2, and finally water or CO2-saturated water. During the second injection stage, the quantity of CO2-saturated water is altered to induce various degrees of fines migration and mineral reactions. These effects are found to yield residual CO2 saturations of 16%, 22% and 23% for zero, 25 and 50 pore volumes of CO2-saturated water injection, respectively. These percentages are 6–7% greater than if neither fines migration nor mineral reactions were present. This is attributed to pore plugging caused by fines migration and mineral reactions, impeding the imbibing water from displacing CO2 in the plugged pores. In addition, CO2-saturated water imbibition is found to increase residual CO2 saturation by 26–30% over that resulting from water imbibition. This is attributed to the CO2 dissolution effect during water imbibition. We therefore conclude that fines migration and mineral reactions is a CO2 residual trapping mechanism during CO2 sequestration.