Experimental Measurement of Diffusion Coefficient of CO2 in Heavy Oil Using X-Ray Computed-Assisted Tomography Under Reservoir Conditions

Abstract

Abstract Injection of carbon dioxide has shown process and economical advantages for enhancing the heavy oil and bitumen recovery by reducing viscosity under the reservoir conditions. Mass transfer is the first mechanism to occur when carbon dioxide is injected into the reservoir. Consequently, the measurement and evaluation of the diffusion coefficient is essential to develop feasible and economic technology for extraction of heavy oil and bitumen. However, not much effort has been put into the experiments of carbon dioxide and heavy oil for understanding and calculation of the gas-liquid diffusion coefficient. The purpose of this study is to evaluate the feasibility of determining experimental diffusion coefficients of carbon dioxide in heavy oil by employing X-ray Computed Assisted Tomography (CAT) and a non-iterative finite volume method, and investigate the impact of different experimental conditions on diffusion coefficients. The results indicated that the measured carbon dioxide diffusion coefficients are consistent with those reported in the literature for similar gas-heavy oil systems. X-ray Computed Assisted Tomography (CAT) and a non-iterative finite volume method were successfully applied to study the diffusivity of carbon dioxide in heavy oil. In addition, the concentration and diffusion coefficients of carbon dioxide in heavy oil depend on diffusion distance as well as on diffusion time and pressure.