Fluid Characterization of a Retrograde Gas Condensate Reservoir for the Simulation Study

Abstract Correct selection of Equation of State (EOS) model is required for proper fluid characterization of retrograde gas condensate fluid so that PVT behavior in the simulation model can be correctly defined. This paper describes the methodology used for establishing the criteria for selecting the most representative PVT laboratory analysis when several PVT analyses are available. The steps for Equation of State (EOS) modeling from the selected PVT report of a retrograde gas condensate fluid sample, which will be used in compositional reservoir simulation model, are also presented in the paper. One of the important steps in the proposed methodology is to examine the available PVT analysis results for accuracy, consistency and validity. The Whitson Torp (K-value flash) method which is based on mass balance has been used for evaluating experimental data by calculating percentage difference between reported values and calculated values of oil composition, molecular weight of C7+ and specific gravity of C7+ at abandonment pressure. EOS models have been developed using two well- known PVT analyses software. Three parameter Peng-Robinson EOS was selected for EOS modeling. The EOS model was tuned by regressing the Binary Interaction Coefficients and other critical properties of pseudo components. After regression, the fluid composition was lumped into five components to reduce simulation time while preserving the inherent nature of the EOS model. The developed EOS model has been used for material balance and simulation studies.