To assess the effect of non-equilibrium mass transfer on the productivity of a single well producing from a gas condensate field, a model incorporating non-equilibrium mass transfer effects was implemented into an equation-of-state (EOS) compositional reservoir simulator developed at The University of Texas at Austin.
A correlation from the literature was used to account for the effect of variables such as gas velocity and diffusion coefficients on the mass transfer coefficient. However, no mass transfer data were available for gas condensates, so a sensitivity study on the mass transfer coefficient was performed. Several simulations have been performed to evaluate the effects of the non-equilibrium mass transfer on the flow behavior in the region near the wellbore. The results from these runs were compared with those obtained under the local equilibrium assumption. Such comparisons reveal that non-equilibrium phase behavior lead to a reduction in the condensate saturation in the region near the wellbore. The mole fractions for light and heavy components in the oil phase are noticeably different. In the high velocity layers, these differences become more significant. In general, non-equilibrium effects lead to slower reductions in well productivity due to the fact that condensate dropout was reduced near the wellbore.