Quantization of the water presence effect on the diffusion coefficients of the CO2/oil system with the dynamic pendant drop volume analysis technique

Abstract

In this paper, the effect of the presence of water on the diffusion characteristics of CO2/oil system was quantified. Five oil samples of n-decane, n-dodecane, n-tetradecane, n-hexadecane and liquid paraffin were used. With the help of dynamic pendant drop volume analysis technique, the diffusion coefficients of the CO2/oil systems with water were determined within the temperature and pressure ranges of 40–80 °C and 2–6 MPa. The results showed that the diffusion coefficients for the water-containing systems were obviously lower than the corresponding systems without water, indicating that the presence of water could retard the diffusion process between CO2 and oil. Lower oil viscosity always corresponds to a higher diffusion coefficient of the system. Due to the variation of water solubility in the system, the diffusion coefficients between CO2 and oil increased with the increase in pressure, whereas the diffusion coefficient decreased with the increase in temperature for the water-containing system.