A Study of Newly Compound Impactor Aiming to Mitigate Stick-Slip Vibration on Drill Bit for Deep Formations

Existing torsion impactor used in the oil field has obvious defects, especially the failure to effectively enhance bit weight. This paper elaborates a brand newly designed compound impactor, in addition, the hydraulic performance of drive unit-the mixed flow impeller is respectively analysed to demonstrate the feasibility of the impactor. This innovative scheme owns an integrated motion just using one independent mechanical device, resulting in an impact loading on the bit in the axial and circumferential simultaneously. However, the theoretical model of a single stage impeller is provided to show the ideal hydraulic characteristic curve. Numerical simulation is investigated to reveal the relationship between the output torque and relative factors, including the flow rate, rotation velocity, and the incident angle of the guide wheel. Compared with earlier single axial vibrator and current torsion impactor driven by a screw or turbine, the remarkable significance of this project is the realization of a high-frequency compound shock on rocks and the reduction of the tool length owing to the utilizing of the mixed flow impeller. Both theoretical analysis and numerical results indicate the new power device can achieve equivalent output torque with a smaller size in comparison to the turbine. The tool provides a revolutionary method to prevent stick-slip vibration on drill bit, Moreover, the composite motion of bit exert by the tool increases the rock fragmentation efficiency. Another characteristic of this tool is the replacement of multi-stages turbines with a single flow impeller, leading to an equivalent output torque with a shorter length.