Modelling Formation Damage Induced by Propagation of Single-Phase Non-Newtonian Polymer Solution in Porous Media

Abstract

Abstract Non-Newtonian high molecular weight polymers dissolve in water to increase viscosity for stable displacement of oil and gas by injected water and enhanced sweep recovery. In both microscopic and macroscopic description of geological factors controlling delivery of oil and gas from reservoir to wellbore, and hence, total eventual production, permeability is a dominant factor. Despite the role of polymers in enhancing oil recovery, polymer adsorption on rock surfaces can also cause permeability reduction, and hence, oil and gas productivity decline due to flow restrictions (formation damage). In the literature, studies on selective permeability reduction (with emphasis on mobility reduction and residual resistance factors) by polymer adsorption based on constant absolute permeability assumption are well known. However, even then, these studies are based on mathematical expressions and formulations that are subjective. There is therefore no existing model that fully considers a combination of the effects of polymer adsorption and its non-Newtonian behaviour on absolute permeability during single-phase propagation in porous media. In order to describe single-phase non-Newtonian flow in porous media, a macroscopic flow rate/pressure drop relationship that combines a mathematical description of fluid rheology must be developed. In this paper, a new method is developed in order to investigate and characterize absolute permeability alteration due to the propagation of single-phase polymer solutions in porous rock media. The validity of the proposed model is demonstrated by using experimental data sets involving single-phase polymer flooding with varying concentrations and formation permeabilites.