Heterogeneous flows of multi-component mixtures in porous media—review

The main difficulty in the mathematical simulation of two-phase flows of gas-condensate or gassed oil in reservoirs is connected with a choice of binary or ternary models of hypothetical components representing the real multi-component mixture. The reduction of the number of degrees of freedom is illustrated by a plot of dependence of Gibbs concentration parameter on pressure for some numerical solutions. These solutions are calculated on the basis of balance equations, generalized Darcy law and equilibrium phase composition for a system of methane-n-butane-decane. It is shown that a binary model is adequate for the simulation of steady, quasi-stationary and self-similar flows into a well. Mathematical simulations of well-capacity for steady flows and processes of pressure build-up are considered.The mathematical problem of gas-condensate driven by dry gas is formulated. The corresponding solution with discontinuities is discussed by means of balance laws for jumps. It is shown that in the case of gas cycling processes a ternary model is necessary as the simplest one.The different approaches to the problem are also discussed.