A New Method to Predict Performance of Gas Condensate Reservoirs

Abstract

Abstract Gas condensate reservoirs differ from dry gas reservoirs. Understanding of phase and fluid flow behavior relationships is essential if we want to make accurate engineering computations for gas condensate systems. Condensate dropout occurs in the reservoir as the pressure falls below the dew point, as a result of which, gas phase production decreases significantly. The goal of this study is to understand the multiphase flow behavior in gas condensate reservoirs and, in particular, focusing on estimating gas condensate well deliverability. Our new method analytically generates inflow performance relationship (IPR) curves of gas condensate wells by incorporating the effect of condensate banking as the pressure near the wellbore drops below the dew point. The only information needed to generate the IPR is the rock relative permeability data and Constant Composition Expansion (CCE) experiment. We have developed a concept of critical oil saturation near the wellbore by simulating both lean and rich condensate reservoirs and observed that the loss in productivity due to condensate accumulation can be closely tied to critical saturation. We are able to reasonably estimate re-evaporation of liquid accumulation by knowing the CCE data. We validated our new method by comparing our analytical results with fine scale radial simulation model results. We demonstrated that our analytical tool can predict the IPR curve as a function of reservoir pressure. We also developed a method for generating an IPR curve by using field data and demonstrated its application by using field data. The method is easy to use and can be implemented quickly.