Friction Pressure Correlations of Newtonian and Non-Newtonian Fluids through Concentric and Eccentric Annuli

Abstract

Abstract An experimental study has been conducted to investigate the effects of eccentricity on friction pressure loss calculations for drilling and stimulation fluids. Reynolds number in the range of 800 to 100,000 allowed the analysis of friction pressure losses of non-Newtonian fluids in both concentric and eccentric annuli in laminar and turbulent flow regimes. Analysis of Fanning friction factors as a function of generalized Reynolds number showed that the effects of eccentricity are significant when annular friction pressure losses are estimated. The results demonstrated that the annular pressure losses in a fully eccentric annulus can be as low as 40% of the value in concentric annulus. It was observed that the effect of eccentricity is more evident as the fluid concentration increases. From experimental data obtained in this study, new correlations are proposed to calculate friction pressure losses in concentric and eccentric annuli for laminar and turbulent flow regimes. Though not ideal, these new correlations estimate friction losses in annuli much closer than the previously published equations.