Four-Component Gas/Water/Oil Displacements in One Dimension: Part III, Development of Miscibility

• Published in: Transport in porous media Vol. 79; no. 2; pp. 225 - 247
• Main Authors: LaForce, Tara, Orr, Franklin M.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-09-2009; Springer; Springer Nature B.V
• Subjects: Civil Engineering; Classical and Continuum Physics; Conservation laws; Cubic equations; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Eigenvalues; Engineering and environment geology. Geothermics; Equations of state; Exact sciences and technology; Exact solutions; Geotechnical Engineering & Applied Earth Sciences; Hydrocarbons; Hydrogeology; Hydrology. Hydrogeology; Hydrology/Water Resources; Industrial Chemistry/Chemical Engineering; Mathematical analysis; Mathematical models; Miscibility; Natural gas; Partitioning; Pollution, environment geology; Reservoirs; Sedimentary rocks; Vaporization; Miscible gas drive; Minimum miscibility pressure; Hyperbolic system; Three-phase flow; Compositional model; carbon dioxide; models; eigenvalues; hydrocarbons; reservoirs; pressure; transport; velocity; water; miscibility; displacements; injection; porous media; Analytical solution
• ISSN: 0169-3913; 1573-1634
• DOI: 10.1007/s11242-008-9311-z

The structure of the system of conservation laws in fully compositional three-phase, four-component flow is examined for the first time. Two of the eigenvalues can be found analytically for this flow regime, regardless of the equation of state used to model the phase behavior. A cubic equation of state is used to calculate the gas/oil phase behavior and Henry’s law is used to represent the partitioning of hydrocarbons between the hydrocarbon and water phases. Sample analytical solutions are found for Riemann problems modeling the injection of carbon-dioxide and water into an oil reservoir. Finally, the structure of the solutions at the minimum miscibility pressure (MMP) for the hydrocarbon system is studied. We show that when water is injected simultaneously with gas at the MMP, multicontact miscible displacement of the oil by the injected gas develops only if the fraction of water in the injected fluid is below a critical value. For water fractions above the critical value, water flowing at a high velocity forces the composition path of the solution to remain in the three-phase region in which two hydrocarbon phases are present. We study both condensing and vaporizing gas drives to demonstrate that this result is general.