EFFECT OF POLYMER FLUID VISCOELASTIC PROPERTIES ON THE INITIATION OF TRANSITION FROM LAMINAR TO TURBULENT FLOW REGIME AND THE DRAG REDUCTION IN THE FLOW THROUGH HORIZONTAL PIPE

摘要

This study investigated the flow of viscoelastic fluids through horizontal pipeline mainly focusing on the effect of fluid elasticity on drag reduction and onset of transition to turbulent flow regime. In order to be able to see the sole effect of fluid elasticity (independent from shear viscosity), three non-Newtonian fluids having the same shear viscosity but different viscoelastic properties were tested in the horizontal flow loop. Those fluids were the dilute solutions of partially hydmlysed polyacrylamide (HPAM) and they were prepared by using three polymer grades of HPAM (i.e. 5 × 105, 8×106, 20×106 g/gmol) in different compositions. Experiments have shown that increasing fluid elasticity resulted in higher drag reduction in pipe flow. Moreover, fluid elasticity affected the onset of turbulent flow and an earlier transition to turbulent flow regime (as compared to water flow) was only observed for the flow of fluid having the highest elastic properties. So, understanding effects of fluid elasticity on flow dynamics might improve the performance of fluids engineered for hole cleaning/cuttings transport in oil and gas well drilling or proppant transport in hydraulic fracturing operations. Also, field efforts to find solutions to problems caused by excessive dynamic pressure losses encountered in drilling horizontal or extended reach wells or in transporting hydrocarbons through pipeline might benefit from the findings of this or further extended research on this subject.