Abstract: Stick-slip motion is a vibration that affects drilling efficiency and downhole drill-string safety. The Power-V can provide an effective deviation control force and also induce stick-slip vibration of drill-string in vertical drilling systems. This study investigates the stick-slip vibration characteristics of a drill-string induced by Power-V. The interaction between Power-V and the wellbore, and the contact model between the bit and formation were studied. The action mechanism of Power-V was extensively analyzed, and its influence on torsional vibration was investigated using the finite element method for drill-string dynamics. The results show that the interaction between Power-V and the borehole wall significantly increases the friction between the drill-string and borehole wall, resulting in an increase in the friction torque and inducing downhole stick-slip vibration. The measured vibration data confirmed the interaction between Power-V and the borehole as the key factor causing the stick-slip vibration of the drill-string. This study is significant in revealing the causes of stick-slip vibration and maximizing the use of Power-V.

Key words: stick-slip vibration, drill-string dynamics, vibration signal measurement, Power-V