Diffusivity analyzing of supercritical CO2 and crude oil at elevated temperature and pressure using the dynamic pendant drop volume method

Enhanced oil recovery (EOR) by injecting CO2 into oil reservoirs not only provides additional oil production but also reduces a large amount of greenhouse gas CO2 emissions. For CO2 EOR practices, the diffusion coefficient of CO2 and crude oil system has significant theoretical importance and practical applications. In this study, we employed the dynamic pendant drop volume analysis method to investigate the diffusion characteristics between supercritical carbon dioxide (scCO2) and crude oil under high-temperature and high-pressure conditions. The experimental results confirm that diffusion between CO2 and crude oil enhances significantly with the increasing system pressure. In contrast, the influence of temperature is relatively complex, which exhibits a two-stage characteristic: during the lower pressure stage, the temperature dependence is relatively weak, whereas at elevated pressures, the diffusion coefficient increases markedly with rising temperature. The experimentally obtained scCO2–oil diffusion coefficient in this study offers extensive data support for EOR applications.