Friction Drag Characteristics of Non-Newtonian Weighted Fracturing Fluids in Pipe Flows

Non-Newtonian weighted fracturing fluids are used to carry out hydraulic fracturing operations into the deep and ultra-deep earth for oil and gas extraction, though their flow and friction drag characteristics are largely unknown. This study aims to understand the abovementioned characteristics. An engineering-oriented cost-effective numerical scheme is deployed, incorporating LES with a generalized Newtonian fluid constitutive equation, for predicting the non-Newtonian pipe flow and friction drag coefficient Cf. The weighted fracturing fluid is described as a power-law fluid, i.e., viscosity μ(γ˙)=Kγ˙n−1, where both K and n are coefficients related to fluid rheology, and γ˙ is the shear rate. The influences of fluid density ρ, mean velocity U and pipe diameter D, as well as K and n on Cf were documented and compared with a water pipe flow. It was found that Cf = f1 (K, n, ρ, U, D) may be reduced to Cf = f2 (Reg), where the scaling factor Reg = ρU2−nDn/(K8n−1) is the generalized Reynolds number. This scaling law can reasonably well predict the friction drag variation in the pipe flow of non-Newtonian weighted fracturing fluids throughout a range of interests and engineering applications.