Analysis of Drilling Cuttings Discharging Efficiency of Double Head and High Slice Screw Drilling Pipe Under High Rotating Speed

In order to reveal the influencing factors of drilling cuttings discharging efficiency and laws in high speed drilling by double high slice screw drilling rod, the dynamic characters of drilling cuttings were analyzed based on discrete element method, the mass flow and torque in three conditions were obtained by EDEM. The results show that drilling cuttings are extruded to the spiral groove of screw drilling pipe through rotating and feeding; when the feeding speed is a fixed value, the mass flow and torque do not vary as the changes of rotating speed when the speed exceeds the critical speed; as to the “discharging cuttings in the hole without feeding” condition, the mass flow increases when rotating speed becomes higher, so as to the torque. However, the critical rotating speed exists in “rotating for discharging cuttings collapsed from roof” condition. When rotating speed is lower than the critical rotating speed, the mass flow increases as rotating speed increases, but the mass flow is steady when rotating speed is higher than the critical rotating speed. The larger the amount of hole collapse is, the greater the critical speed is.