Investigating the solid transport capability of non-newtonian fluid in annulus bend section

A directional drilling operation may include one or more bending sections along the drilling profile. These bend sections are the critical segments from the hole cleaning point of view. In this study, a computational fluid dynamic (CFD) method was used to investigate the hole cleaning behaviour in annulus bending section. Eulerian-Eulerian multiphase flow model was adopted in this study. The developed CFD model was validated with experimental data. Different non-Newtonian Herschel Bulkley fluids were used to simulate the drilling mud. Solid cuttings of different sizes (2 mm, 4 mm, and 5 mm) were used to replicate the drill cuttings. Different fluid flow rate (0.5 m/s, 1.0 m/s, 1.5 m/s and 2.0 m/s) were investigated to observe the solid settling tendency in the horizontal and bending section. Cuttings accumulation behaviour at different bending radius (10 inch. and 20 inch.) and bending angle (15°, 30°, and 60° from horizontal) were investigated. The simulation study shows that higher viscous fluid performs better hole cleaning at low mud velocity. Furthermore, a turbulent flow regime performs better solid transport in the bending section. Finally, this study summarizes the hole cleaning behaviour of a bend section for a range of fluid velocity, cuttings size and radius of curvature and inclination.