Study of Non-Newtonian fluid flow in porous media at core scale using analytical approach

Abstract

Characterizing in situ polymer rheology in porous media is critical before further implementation of polymer injection in oilfield. Polymer as non-Newtonian fluid has unique behavior whose viscosity changes over various shear rate. This behavior creates unsuitable conditions which can lead to ineffective sweep efficiency improvement. The challenging issue in characterizing the in situ polymer rheology is how to construct the in situ Power Law model since the in situ viscosity cannot be measured directly. In this study, we use an analytical model to construct the in situ Power Law model. The model combines material balance equation, modified Darcy equation for non-Newtonian fluid flow, and equation of state. The model is solved for early (transient) time and late (steady-state) time. Coreflooding results in Berea Sandstone with 2000 and 500 ppm HPAM polymer injection are used for model’s simulations. Rheometer measurements are also used for comparison. The overall simulation results show there is no difference in flow behavior index between rheometer and porous media. The same fluid definitely gives the same flow behavior index through different measurement methods. However, there is significant difference in flow consistency index. It is caused by the effect of porous media’s tortuosity. The quantity of the skin parameter also depicts the thinning and thickening phenomena.