Foamy Oil Flow in Porous Media

Certain heavy oils which foam under severe depressurization give rise to increased production and an increased rate of production under solution gas drive. The phenomenon seems to be related to the chemistry of these oils which not only stabilize foam but also stabilize dispersion of gas bubbles at lower volume ratios. We present here a mathematical model of this phenomenon which depends only on the velocity through D’Arcy’s law, the pressure and the dispersed gas fraction. The theory governs only in situations in which the bubbles do not coalesce to produce the percolation of free gas. In this theory the bubbles move with the oil as they evolve. The main empirical content of the theory enters through the derivation of solubility isotherms which can be obtained from PVT data; modeling of nucleation, coalescence, bubble drag laws and transfer functions are avoided. The resulting theory is hyperbolic and nonlinear. The nonlinear equations for steady flow through a sandpack are solved by quadrature and give rise to good agreements between theory and the experiments of Maini & Sarma [1994] without fitting constants.