Molecular Investigation of CO2 Solubility and Diffusion in Crude Oil

Abstract

It is important to know solubility and molecular diffusion coefficients of gas under reservoir CO₂ Enhanced Oil Recovery. In this paper, a set complete device has been established to measure solubility and molecular diffusion coefficients of gas to improve the empirical formula and chart. Based on the experiment, molecular diffusion coefficients and solubility is evaluated, which provides the fundamental data to CO₂ Enhanced Oil Recovery. The solubility vs. pressure linear relationship and molecular diffusion coefficients vs. pressure linear relationship are obtained in a certain pressure range at different temperature conditions. In addition, experiments with shearing are also designed to simulate the real dissolving process of carbon dioxide in oil under reservoir conditions, which can be influenced by the mechanical dispersion. The results demonstrated that the molecular diffusion coefficients are 10-⁶m2/s for 600 r/min at  105°C however, the molecular diffusion coefficients are 10-⁷m2/s in the case without stirring at 105°C, the mass transfer process is accelerated by stirring.

Keywords: CO2, enhanced oil recovery, mechanical dispersion