Shear-Thinning and Shear-Thickening Behavior of Polymer in Core Flooding: Experimental and Numerical Investigations

Polymer flooding is a widely used chemical enhanced oil recovery (EOR) technique that can decrease the water–oil mobility ratio and enhance sweep efficiency. In this study, the non-monotonic rheological behavior of a co-polymer, SAP, is established in bulk rheology tests. A key objective is to numerically model the shear-thickening and shear-thinning behaviors of a polymer solution in a core-plug based on core flooding data; and analyze influential factors on polymer in situ rheological behavior and their effects on oil production and pressure. Toward this end, a novel method that integrates the pore network model (PNM), core flooding experiments, and reservoir simulation is developed to investigate the non-Newtonian behavior of the polymer in a core-plug. The polymer core flooding simulation model was history-matched with experimental results for cumulative oil recovery, water cut, and pressure drop across the core-plug. The effects of two variable parameters, namely, the residual resistance factor (RRF) and inaccessible pore volume (IPV), on the pressure drop across the core-plug were numerically investigated. The shear-thickening behavior is more pronounced in the near-inlet and near-outlet sides of the core-plug sample at the late stage due to high-flow velocities. The pressure drop across the core-plug increases with increasing RRF, and when RRF = 1.8, the pressure drop in the simulation model is the closest to the experimental results. Moreover, an increase in the IPV can cause an earlier polymer breakthrough because more pore bodies are rendered inaccessible.