Investigation of cuttings transport in directional and horizontal drilling wellbores injected with pulsed drilling fluid using CFD approach

Efficient cuttings transportation is a significant issue in wellbore drilling. The pulsed jet drilling technology is known to improve the rate of penetration (ROP), but lacks targeted research into its effect on cuttings transport. We presented a CFD model based on Eulerian-Eulerian method to investigate the cuttings transport characteristics in horizontal and directional wellbores injected with pulsed drilling fluid. Kinetic theory of granular flow was used to formulate the stress tensor of cuttings particles, and sliding mesh method was used to achieve the rotation of the drill pipe. The wave propagation of the flow of cuttings particles was analyzed from the variation of amplitude and frequency of the inlet velocities of pulsed drilling fluids. Effects of drilling fluid rheological properties and hole and pipe diameters on borehole cleaning in traditional and pulsed drilling were studied. Numerical results indicated that the pulsed drilling fluid contributes to borehole cleaning because it significantly reduces the cuttings concentration in the moving bed zone and increases the velocities of cuttings in the fixed bed zone. Increasing amplitude and frequency of the inlet velocity of pulsed drilling fluid also leads to a decrease of the height of cuttings bed. The pulsed drilling fluid produces higher turbulent kinetic energy and lower turbulent dissipation rate comparing with the case with a constant drilling fluid velocity. Furthermore, pulsed drilling was also proved to be universally applicable to the improvement of cuttings transport within a wide range of drilling fluid rheological parameters and hole and pipe diameters.