Pseudo-component Delumping for Multiphase Equilibrium in Hydrocarbon-Water Mixtures

摘要

An analytical and consistent delumping procedure is implemented for fluids of petroleum interest containing water, non-hydrocarbon gases (such as N_2, CO_2, and H_2S) and hydrocarbon (HC) compounds. Two sorts of difficulties are associated with these fluids: they often exhibit three or more equilibrium phases, and their thermodynamics cannot be described by conventional cubic equations of state (EoS). In this work, the Soreide-Whitson modification of the Peng-Robinson EoS, in which different binary interaction parameters are used in the aqueous and non-aqueous phases, is used. The method is successfully tested on two cases in the two- and three-phase regions: one synthetic HC/N_2/CO_2/H_2O fluid and a "real" water/reservoir fluid.