With a model of foam wellbore flow and a model of foam seepage flow,a mathematical model of foam plug removal is given.The model is solved with numerical method.Distributions of foam pressure,foam quality,foam density along wellbore and wellhead and bottom pressure are discussed.Furthermore,variation of bottom hole differential pressure is given as wellhead back pressure is fixed.It shows that as foam pressure and density increases,foam quality decreases with increase of well depth and bottom hole differential pressure declines.

A muhi-component mathematical model characterizing polymer enhanced foam flooding filtration is established with mass conservation principle of foam components. Considering combination of foam generation, coalescence and migration phenomena, the model effectively reflects mechanism of oil phase foam coalescence and polymer foam stabilizing. Differential numerical solution is conducted with adaptive implicit method. Validity of the mathematical model is verified with experiment. Meanwhile, taken foam flooding pilot region of a oilfield, a numerical simulator is employed to study filtration characteristics of enhanced foam flooding. It is indicated that the foam system could exist stably in the formation and gradually advance to production wells to improve oil recovery.