A Theoretical Analysis On Stability Of Moving Interface In A Porous Medium For Non-Newtonian Fluids

At the present time a large class of non-Newtonian displacement of fluids are currently used in certain field projects of water flooding to obtain a better volumetric sweep efficiency in the oil displacement mechanism. For example, the polymer solutions appear to be of great practical interest in oil reservoir engineering. The main objective is the elimination of the viscous fingering effect which is directly responsible for ultimate low oil recovery.This paper deals specifically with the illustration of the rheological effects of non-Newtonian behavior of both the displacing fluid and displaced fluid in a radial displacement mechanism in a porous medium. The displacing fluid of power law fluid with yield stress and displaced fluid of Bingham are used to illustrate these effects. The frontal advance theory, which describes the flow of two immiscible fluids separated by a moving interface, has been used to illustrate the deviation from Newtonian behavior in oil displacement mechanism. The necessary and sufficient conditions for stability are derived and discussed. A linearized stability theory has been developed from which the approximate analytical solutions of the basic equations describing moving interface stability were obtained. The results obtained in this paper are relevant for an adequate understanding of the rheological effects associated with the displacing and displaced fluids on the moving interface stability. The existence of a critical value for the interface location from which the interface protuberances begin to damp out is shown.On the consideration of practical data in the oilfield, the thesis analyzed the relation of reservoir characters, oil and injection fluids rheological effects and injection velocity. The relevant results presented in this paper clearly demonstrate the theoretical support for the finding of a strategy regarding the optimal selection of rheological parameters of displacing fluid, expressed in terms of fluid and reservoir properties, in order to minimize the instability effects on the moving interface.