Understanding the thermodynamic behavior of each flowing phase in a petroleum reservoir allows for accurate quantification of these phases. This work explains how to develop and run a thermodynamic model to reliably forecast the equilibrium behavior of oil-gas-brine systems across a reasonable pressure and temperature range. The 3-phase negative flash method is tested against previously published data in the literature. The multiphase flash approach is used to develop linearized physical operators utilizing an Operator Based Linearization (OBL) modeling technique that allows for the nonlinear solution of governing equations to include various complicated physics. To our knowledge, this is the first implementation to the coupling of 3-phase flash calculations for hydrocarbons and brines have been using fugacity-activity models with a a sophisticated, high-efficiency linearization technique. Such coupling improves the efficiency and flexibility of physical phenomena modeling of the fluid flow in porous subsurface reservoirs.

The properties of fluids flowing in a petroleum reservoir are quantified by understanding the thermodynamic behavior of each flowing phase in the system. This work describes proper techniques to formulate and execute a thermodynamic model for accurately predicting the equilibrium behavior of oil-gas-brine systems within the practical range of pressure and temperature. The three-phase flash algorithm is validated against published data from the available literature. The multiphase flash procedure is implemented to generate linearized physical properties by using an Operator Based Linearization (OBL) modelling technique allowing for a combination of multiple complex physics in the nonlinear solution of governing equations. This is the first implementation of three-phase flash calculations for hydrocarbons and brines based on fugacity-activity models coupled with an advanced highly efficient linearization scheme. Our approach increases the efficiency and flexibility of the modelling process of physical phenomena such as fluid flow in porous subsurface reservoirs.