Investigation of the Relationship between CO2 Reservoir Rock Property Change and the Surface Roughness Change Originating from the Supercritical CO2-Sandstone-groundwater Geochemical Reaction at CO2 Sequestration Condition

Laboratory experiments were performed to investigate the property change of sandstones, resulting from scCO2-rock-groundwater reaction for 150 days under CO2 sequestration conditions. The average surface roughness value (SRrms) increased more than 3.5 times during early 90 days, suggesting that the weathering process of sandstone occurs in the early reaction time after CO2 injection. The average porosity of sandstones increased by 8.8% and P wave velocity decreased by 5.7%. The trend of rock property change and SRrms change showed in a logarithmic manner, indicating that the physical property change of reservoir rocks directly comes from CO2 related geochemical reaction.