2002/04/01 by I. K. Karpov · 1 citation
Engineering · #Hydrocarbon exploration and reservoir analysis #Phase Equilibria and Thermodynamics #Field-Flow Fractionation Techniques
paper · pdf · doi:10.2475/ajs.302.4.281
An approach is suggested for computation of complete or metastable equilibrium states in the multicomponent, multiphase, and multiaggregate systems with parameters of state other than fixed temperature T and pressure P. It consists in computation of a series of isobaric-isothermal equilibrium states by Gibbs energy minimization. Thus, the general problem of minimization of thermodynamic potentials other than Gibbs energy G(T,P) is reduced to a sequence of simpler problems of two- or three-criteria parametric minimization of either of five thermodynamic potentials isochoric-isothermal or Helmholtz energy A(T,V); isochoric-isentropic or internal energy at isochoric conditions U(S,V); isobaric-isentropic or enthalpy H(P,S); negative entropy at isobaric conditions and fixed enthalpy −S(P,H); and negative entropy at isochoric conditions and fixed internal energy −S(V,U). The computational scheme is simple, efficient, and reliable, because in any case it uses the IPM (Interior Points Method) algorithm for searching minimum of the non-linear total Gibbs energy function whereby one- or two-sided restrictions may be imposed on some or all dependent components in the system (Karpov and others, 1997). The new approach provides a rigorous basis for the formulation and numerical solution of the problems of chemical mass transfer under factors of state other than isobaric-isothermal. The developed algorithms and their implementation in Selektor-C program package can be used in a wide variety of scientific and practical applications. The numerical tests and examples illustrate the new technique on a model of irreversible oil-water interaction in hydrocarbon reservoirs (system Ca-Mg-C-O-H).