Computational Fluid Dynamics Simulation For Cuttings-Liquid Flow Through Horizontal Eccentric Annuli

The interactions between cuttings and drilling fluid in horizontal eccentric annuli were simulated and observed using ANSYS CFX 14 Computational Fluid Dynamics (CFD) software. CFD software program has proven to be a successful tool in studying fluid flow in bit hydraulic and gas liquid flow in pipeline and separator. In this project, the effect of drilling mud flow rate and the impact of the Rate of Penetration (ROP) on flow patterns, cuttings concentration and pressure losses were investigated and validated against flow loop tests conducted by Dr. Reza Ettehadi Osgouei.
It is essential to transport cuttings generated in drilling operations to the surface for disposal. Improper hole cleaning will lead to costly drilling problems such as increase of pipe sticking potential, higher drag and torque, slower rate of penetration, formation of fractures and wellbore steering problems. As the well inclination from vertical axis increases, the cuttings transport is further complicated. In this project, the cuttings transport in horizontal eccentric annulus is investigated.
The results obtained from the simulations are successful. As the drilling mud flow rate increases, the flow pattern was observed changing from stationary bed to dispersed flow, which complies with experimental results and literature findings. Increase in flow rate also increased the annulus pressure drop but decreased the cuttings concentration. The increment in ROP leads to more cuttings generated and poorer hole cleaning. In conclusion, drilling mud flow rate and ROP are both significant factors in hole cleaning operations. The higher the flow rate, the higher the efficiency of hole cleaning, whereas the higher the ROP, the less efficient is the hole cleaning.