Development of Inflow Performance Relationship Model in High Temperature, High Pressure Gas-Condensate Reservoirs.

Inflow Performance Relationships (IPRs) are important element for reservoir engineers in the design of new wells and also for monitoring and optimizing existing wells. IPRs are used to determine optimum production of gas rate and condensate rate in a well for any specified value of average reservoir pressure and predict the performance.
Jokhio and Tiab proposed a simple method of establishing IPR for gas-condensate wells. The method uses transient pressure test data to estimate effective permeability as a function of pressure. Effective permeability data used to convert production bottomhole flow pressure into pseudopressure to establish well performance. Despite the effectiveness of the method, single phase correlations were used in PVT calculations of each phase, which over simplified the fluid flow in gas-condensate wells. Single phase dry gas equations do not reflect the multiphase flow behaviour of gas-condensate wells below the dew point. Due to this limitation Jokhio and Tiab method modified by this study and new analytical IPRs for gas condensate well proposed.
The major improvement of the above method is incorporating new viscosity correlation developed by this study and using two-phase compressibility factor for predicting gas-condensate inflow performance. Viscosity is a key parameter in inflow performance modelling and was used to predict pseudopressure function. Therefore, the main contribution of this study is development of viscosity correlation which is a critical issue in predicting gas condensate inflow performance both above and below the dew point. Optimization techniques and nonlinear regression used to develop a new viscosity correlation for gas condensate reservoirs under depletion. New Viscosity correlation and two-phase compressibility factor used for better reflection of fluid flow in near wellbore region.
The application of the new model is illustrated with field example for current IPR curves. Compositional simulation study of the well performed in PIPSIM. The proposal approach provides reasonable estimates of simulator input reservoir properties (e.g. IPRs). The presented method is successfully applied to the actual reservoir. Accuracy of the new method compared with compositional simulation study. New method provides a tool for quick estimation of gas condensate wells without need of relative permeability curves and expensive and time consuming compositional simulation.