Prediction of CO2 Diffusion Coefficient in Condensate by Pressure Decay Method

Summary Gas injection to reservoir is carried out for various reasons, including pressure maintenance, enhanced oil recovery and greenhouse gas storage. The molecular diffusion coefficient is one of the most important mechanisms in describing the mass transfer in gas injection to reservoirs. Currently, for calculating the molecular diffusion coefficient, indirect methods especially pressure decay method are used. The most important point in this method is the useage of appropriate model and analyze the experimental results. In this study, the diffusion coefficient of CO2 in condensate is calculated using pressure decay methods. Then analytical methods for analyzing experimental data from the pressure decay method have been evaluated. The result show that equilibrium boundary condition matches well to experimental data. Because of the low viscosity of the condensate, it can be assumed that the interphase is Continuous and the surface Resistance is low. While the non-equilibrium and pseudo-equilibrium boundary condition has reported the diffusion coefficient more than its actual value.