Visualization and Quantitative Analysis of Shale Properties Under CO2 Fluid-Rock Interaction: Implication for CO2 Geological Storage

Abstract CO2 flooding technology effectively enhances shale oil production while enabling CO2 sequestration. Changes in pore structure and wettability during the flooding process can significantly influence CO2 storage safety. This study investigates the effects of supercritical CO2 (SCCO2) treatment on the pore structure and wettability of shale oil reservoirs. Advanced techniques, including AMICS Automated Mineralogy System (AMICS), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR), were employed to evaluate alterations in mineral composition, pore structure, chemical functional groups, and water/shale contact angles using a contact angle goniometer. Results show that SCCO2 treatment reduces dolomite content, increasing average pore size and pore connectivity. Furthermore, increased hydrophilic functional groups decrease water contact angles, thereby enhancing hydrophilicity and improving sequestration efficiency. These findings offer insights for shale oil recovery and CO2 storage safety evaluation.