Influence of Alkali and Surfactants on Near-Wellbore- and Reservoir Viscosities of Polymers for EOR Applications Available to Purchase

Knowledge of the injectivity behaviour of polymer solutions for enhanced oil recovery (EOR) is of vital importance for the successful implementation of a polymer flood in the field. Shear thickening, which is observed for solutions of hydrolysed poly-acrylamides, can lead to exceeding tubing head pressures and to exceeding of the formation parting pressure. Shear degradation at the formation contact will cause reduced sweep efficiency in the reservoir and diminished economics. While numerous experiments were performed investigating the rheology of polymers, no experiments concerning the visco-elastic properties of Alkali Surfactant Polymer (ASP) slugs are known to the authors. The questions we are answering are (1) what is the impact of Alkali and Surfactants on the near-wellbore apparent viscosity of polymer solutions and (2) how is the viscosity of polymer solutions influenced at the conditions seen deep in the reservoir. In this study, we extended previous work to the interaction of polymer slugs with alkaline and surfactants in a wide range of concentrations in view of potential alkaline-surfactant-polymer (ASP) pilot under near-wellbore and reservoir conditions. Extensive core floods on outcrop core confirmed the general trend of shear thickening. Surfactants on the other hand also lead to an increase in in viscosity deeper in the reservoir. The results of the experiments can be used as input data for simulation of injectivity and displacement efficiency of ASP slugs.