The impact of extensional viscosity on oil displacement efficiency in polymer flooding

摘要

The flow behavior of polymer flooding solution can not only be described simply with shear flow field, but also with convergent and extensional flow field. The extensional viscosity of polymer solutions used in polymer flooding in Daqing Oilfield was investigated with CaBER1 extensional rheometer, and the results showed that the extensional viscosity of which is much higher than shear viscosity with three orders of magnitude. The extensional viscosity of the polymer solutions sharply increased when polymer molecules were stretched to the limit, which means that an extension stiffen phenomenon occurred. The extremely high extensional viscosity and an extension stiffen characteristic in stretching process of polymer solutions could increase capillary number substantially to raise microscopic oil displacement efficiency.