VERSATILE PHASE EQUILIBRIUM PACKAGE FOR COMPOSITIONAL SIMULATION.

Modeling of enhanced oil recovery applications such as miscible gas injection requires careful consideration of phase equilibria, especially between multiple liquid phases. This paper addresses the problem of phase equilibria when more than two phases are present. A cubic equation of state approach is used and both Peng-Robinson and Soave-Redlich-Kwong equations of state are considered. Solution methods implemented for finding the roots of the nonlinear system of equations include successive substitution method (SSM), accelerated and stabilized successive substitution method (ASSM), and minimum variable Newton-Raphson (MVNR) method. The phase behavior routine has been tested on various three- or four-phase systems and has been found flexible and satisfactory for phase equilibria prediction of multiple liquid phase mixtures.