Degradation of Synthetic Polymers during Radial Injection in a Sandstone

Summary Minimizing mechanical degradation during injection of polymer solutions for polymer flooding is important to avoid excessive use of polymer chemicals. Mechanical degradation leads to a reduction in the viscosity of the polymer solution. The near-well zone has been identified as critical for mechanical degradation. There are several studies on degradation during linear flow in normal cylinder shaped core samples, but very few on the actual radial flow occurring in the near-well zone. Here we report degradation results from core floods in sandstones with a geometry close to a real well bore. The results show that mechanical degradation follows the observed shear thickening of the polymer solution. It is also shown that the degradation is well described by the shear rate in the sandstone. The onset of degradation occurs at 1000–3000 1/s.