Numerical Analysis of Pressure Gradient along Casing in Helical Turbulent Flow of Power Law Fluid in Eccentric Annulus

Abstract

With the use of casing running tool (CRT), casing can be rotated and reciprocated at the same time with circulation of drilling fluid. Thus the flow in well bore was eccentric annular helical. Pressure exerted on casing was important for casing buckling analysis. A numerical model of eccentric annular helical flow of power law fluid was built in this paper. The relationship between average pressure gradient on pipe and some influence factors (pipe axial velocity, rotating angular velocity, drilling fluid circulation velocity, and axial coordination) was analyzed. Results showed that average pressure gradient caused by shear stress was only affected by average annular flow velocity, and it didn’t change along pipe length. Effect of rotating angular velocity on average pressure gradient on pipe was very small and could be negligible. A fitting function between average pressure gradient and average annular flow velocity was obtained in this end.