Peng-Robinson Equation of State Extended to Handle Aqueous Components Using CPA Concept

Abstract Parameters are presented enabling the Cubic Plus Association (CPA) concept to be applied with the Peng-Robinson equation for petroleum reservoir fluids carrying water and any of the gas hydrate inhibitors, methanol, mono-ethylene-glycol, or tri-ethylene-glycol. The acid gases, CO2 and H2S, are treated as solvating components, which do not self-associate, but cross-associate with water and hydrate inhibitors. Association is not considered for the remaining petroleum reservoir fluid constituents. The presented concept and parameters enable CPA to be used in flow assurance and process simulations on produced reservoir well streams containing water and hydrate inhibitors, while retaining consistency with prior reservoir simulations carried out using the Peng-Robinson equation on the water free reservoir fluid. A comprehensive data material for the mutual solubility of gases and aqueous components and hydrate inhibition is used to determine the pure component parameters and binary interaction parameters for associating components.