Numerical simulation of Drill Pipe Rotation effects on Fluid Velocity Profile of Horizontal Annulus in Foam Drilling

摘要

Pipe rotation effects on axial pressure drop are actually caused by velocity re-distribution in annulus. There has not been much study on foam drilling with drillpipe rotation. The effect of drillpipe rotation on fluid velocity with different eccentricities was investigated by numerical simulation in this paper. Simulation results show that the maximum axial velocity core is shifted by pipe rotation, the higher the pipe rotary speed, the greater the shift. The shift direction of the axial velocity core depends on pipe eccentricity. At a smaller eccentricity, the core shifts to the same direction as pipe rotation. At a bigger eccentricity, the core shifts to the opposite direction of pipe rotation. In an annulus with a cuttings bed, pipe rotation creates a secondary flow from the point of view of the tangential flow. It is the secondary flow that shifts the axial velocity core to the opposite direction of pipe rotation. The shift of the axial velocity core has a significant, positive effect on hole cleaning. The results of this paper are particularly useful for drilling design in foam drilling operations.