AN EQUATION OF STATE COMPOSITIONAL MODEL

A description is given of an implicit, three-dimensional formulation for simulating compositional-type reservoir problems. The model treats three-phase flow in Cartesian (x-y-z) or cylindrical (r- THETA -z) geometries. Applicability ranges from depletion or cycling of volatile oil and gas condensate to miscible flooding operations involving either outright or multicontact-miscibility. The formulation uses an equation of state for phase equilibrium and property calculations. The equation of state provides consistency and smoothness as gas-and oil-phase compositions and properties converge near a critical point. This avoids computational problems near a critical point associated with use of different correlations for K values as opposed to phase densities.