关键词: 减阻率, 　湍流, 　管流, 　聚合物, 　剪切应力

Abstract: Drag reduction performance of slick water is one of the key factors affecting fracturing, but the physical mechanism has still not been clearly identified. This paper aims to build a drag reduction modeling of polymer additives dissolved in hydrocarbon in pipe flow on the basis of Giesekus constitutive equation, which was validated by the loop experiment later. The model was applied to calculate the drag reduction rate of polyacrylamide tetrapolymer additive (DR800) in turbulent flow. Indoor loop experiments were introduced for parameter validation and model verification. Although the physical mechanism has still not been clearly identified, the modeling was aimed to explain the contribution of different components: viscous shear stress, Reynolds shear stress and viscoelastic shear stress. It turned out that as the complexity of the flow increased, the viscous contribution and viscoelastic contribution decreased while the turbulence contribution increased. In low Reynolds numbers, viscoelastic shear stress contributed most to friction coefficient while the turbulence can be neglected. In high Reynolds numbers, the contribution of turbulence increased rapidly thus to be the dominating part of the overall contribution, followed by viscoelasticity, and the least was viscous shear stress. By performing consistent comparisons between modeling and experimental results, it can be seen that the model can predict the drag reduction rate of DR800 in a range, which can be used for field production and guidance.

Key words: Drag reduction, Turbulent, Pipe flow, Polymer, Shear stress