MODELING NON-EQUILIBRIUM MASS-TRANSFER EFFECTS FOR A GAS CONDENSATE FIELD

摘要

To assess the effect of non-equilibrium mass transfer on the productivity a single well producing from a gas condensate field, a model incorporating non-equilibrium mass transfer effects was implemented into an equation-of-state (EDS) compositional reservoir simulator developed at The University of Texas at Austin.An empirical 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 conducted. Several simulations were performed to evaluate the effects of the non-equilibrium mass transfer on the flow behavior in the region near the wellbore in a gas condensate reservoir. The results from these runs were compared with those obtained under the local-equilibrium assumption. Such comparisons reveal that non-equilibrium phase behavior led to a reduction in the condensate saturation in the region near the wellbore. The mole fractions for light and heavy components m the oil phase were noticeably different. In the high-velocity layers, these differences became more significant. In general, non-equilibrium effects led to lower reductions in well productivity because condensate dropout was reduced near the wellbore.