A NEW EMPIRICAL CORRELATION FOR PREDICTING EFFECTIVE MOLECULAR DIFFUSIVITY OF GAS-HEAVY OIL-POROUS MEDIA SYSTEMS

摘要

Molecular diffusivity is an essential parameter for modeling of mass transfer in enhanced oil recovery processes. How-ever, experimentally determined diffusivities for light gas-heavy oil systems in the presence of porous media are rela-tively rare. A few correlations are available in the literature that predict diffusivity of gases into heavy oil in presence of porous media. In this work the pressure-decay method was applied to obtain effective molecular diffusion of CO_2, CH_4 and N_2-heavy oil systems in both bulk and porous media systems at different temperatures. The diffusivity of gases in heavy oil was determined by matching the numerically calculated pressures to the measured data. A new empirical correlation for predicting molecular diffusivity of gases in porous media was proposed that depended upon temperature, oil viscosity and molecular weight of diffusing gases. The results of proposed correlation matched satisfactorily with the experimental data. Measured diffusion coefficients were in the range of available data in the literature for different heavy oils. The simplicity of the experimentally derived correlation makes it attractive for application in modeling and simulation of miscible enhanced oil recovery processes in similar heavy oils.