A Fully Non-iterative Technique for Phase Equilibrium and Density Calculations of CO2+Brine System and an Equation of State for CO2

Abstract

Any mutual solubility or phase equilibrium calculations require iterations in order to attain desired convergence in fugacity measurements from which equilibrium compositions are obtained. In this monograph a fully non-iterative technique is approached for calculating phase equilibrium compositions of CO2 in brine water and that of H2O in CO2 rich phase. As an essential part of this computations process, an empirical volume explicit Equation of State (EoS) for CO2 with having only 8 parameters is presented. The volumetric data and calculated results of phase compositions using this EoS are compared with the literature values. They exhibit good agreement with less than 2% deviation. A modified scheme of CO2+brine density calculation is also shown. More so, the manner in which this EoS can improve computational efficiency following the non-iterative technique with respect to other EoS’s used in petroleum reservoir simulation is illustrated. This shows that the proposed technique can be even more than 1000 times faster than conventional phase equilibrium computations after integrating with numerical simulation of CO2 flows in reservoir.