Effect of pulsating flow induced by a percussive drilling tool on cuttings transport in horizontal directional drilling-A CFD study

Cuttings deposition and removal has always been a key issue in horizontal directional drilling due to its correlation with numerous problems such as rate of penetration, reduction and stuck pipe.In this paper, the relationship between the impulse flow generated by a fluidic jet hammer and cuttings removal was discussed. A Eulerian-Eulerian two-fluid model was used to simulate the cuttings transport in horizontal wells on a sliding grid basis. Results show that the flow pulsation induced by a fluidic hammer contributes to easier cuttings transport. Compared to constant flow, impulse flow showed a 22.03% improvement in more optimal borehole cleaning with the same system inlet flow rate. In addition, the asymmetric flow pulsation was more sensitive to amplitude than the sinusoidal waveform pulsation flow, and as amplitude increased, the average exit flow rate of cuttings increased by 30.95%. Cuttings transport in annular is sensitive to rate of penetration, average velocity of pulsation, pulsation amplitude and cuttings size. The effect of pulsation frequency seems to be not much significant, probably because the frequency or other parameters used in this work did in the range of optimal particle-carrying frequency. These findings can provide references for the utilization of downhole pulsating fluids by drilling tools.