Reliable measurement of the CO
2
diffusion coefficient in consolidated oil-saturated porous media is critical for the design and performance of CO
2
-enhanced oil recovery (EOR) and carbon capture and storage (CCS) projects. A thorough experimental investigation of the supercritical CO
2
diffusion in
n
-decane-saturated Berea cores with permeabilities of 50 and 100 mD was conducted in this study at elevated pressure (10–25 MPa) and temperature (333.15–373.15 K), which simulated actual reservoir conditions. The supercritical CO
2
diffusion coefficients in the Berea cores were calculated by a model appropriate for diffusion in porous media based on Fick's Law. The results show that the supercritical CO
2
diffusion coefficient increases as the pressure, temperature and permeability increase. The supercritical CO
2
diffusion coefficient first increases slowly at 10 MPa and then grows significantly with increasing pressure. The impact of the pressure decreases at elevated temperature. The effect of permeability remains steady despite the temperature change during the experiments. The effect of gas state and porous media on the supercritical CO
2
diffusion coefficient was further discussed by comparing the results of this study with previous study. Based on the experimental results, an empirical correlation for supercritical CO
2
diffusion coefficient in
n
-decane-saturated porous media was developed. The experimental results contribute to the study of supercritical CO
2
diffusion in compact porous media.
CO2-enhanced shale gas recovery (CO2-ESGR) sequestrates anthropogenic CO2 and improves the profitability of shale gas exploitation. This work investigated the adsorption behaviors of CO2 and CH4 on shale from China at 20, 40, 60 and 80 °C. The pressure ranges for CO2 and CH4 were 1–5 and 1–15 MPa, respectively. The excess adsorbed amount of CH4 increased with increasing pressure from the beginning to the end, while the maximum excess CO2 adsorption was observed at approximately 4 MPa. The absolute average deviations (AADs) of CO2 and CH4, determined by the Langmuir + k model, were 2.12–3.10% and 0.88–1.11%, respectively. Relatively good adsorptivity for CO2 was exhibited when the pressure was less than 5 MPa, which was beneficial to the implementation of CO2-ESGR. With continuous increases in pressure, the adsorption capacity of CO2 was weaker than that of CH4, suggesting that the injected CO2 would reduce the partial pressure of CH4 for CO2-ESGR and the displacement effect would no longer be significant. In addition, the adsorption rate of CO2 was much faster than that of CH4. CO2 was more active in the competitive adsorption and it was advantageous to the efficiency of CO2-ESGR.
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