Abstract

Polymer flooding has been used to enhance oil production and reduce water cut for a long time. However there are still many fundamental challenges in characterizing the multi-phase fluid flow, even the single-phase fluid flow, associated with polymer flooding. For example, it is difficult to measure and calculate two-phase polymer solution/oil relative permeability. One of the difficulties comes from the non-Newtonian and time-dependent properties of polymer solutions; another comes from the change in absolute permeability caused by the adsorption of polymer on rock surfaces. Almost all of the methods for computing relative permeability are based on the assumption that the absolute permeability is constant. It will be helpful to further understand the mechanisms and develop more reliable methods for calculating two-phase polymer solution/oil relative permeability by investigating the single-phase polymer flooding more profoundly. In this study, a new method has been developed to calculate the pseudo permeability during single-phase polymer flooding. The non-Newtonian property of the polymer solutions was considered in the proposed method. A series of polymer flooding experiments using different concentrations of polymers were designed and conducted to study the single-phase flow of polymer solution in rocks with different permeabilities. The values of the pseudo permeability of single-phase polymer flooding were then calculated using the new method. It has been found that the relationships between the pseudo permeability and the reciprocal of shear rate were linear. The pseudo polymer flooding permeability extrapolated at the infinite shear rate was close to the brine flush permeability after polymer injections in most of the cases.

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