The Influence of Different Rocks on Drillstring Stick-Slip Vibration

This paper establishes a torsional model of a two-degree-of-freedom drill string system composed of a rotary table and bottom-hole assembly, constructs a friction model between the drill bit and rocks, and considers the influence of five different rock types on the stick-slip vibration of the drill string system. The stick-slip vibration of the drill string system is analyzed under changes in top drive torque, top drive rotational speed, and weight on bit. The results show that different rocks cause varying degrees of stick-slip vibration due to their distinct friction coefficients: rocks with higher friction coefficients are more prone to induce stick-slip vibration. Meanwhile, increasing rotational speed and torque, as well as reducing weight on bit, can mitigate the impact of stick-slip vibration. This study provides assistance for systematic research on the influence of different rocks on drill string stick-slip vibration.