摘要
A specific model is elaborated for stick-slip and bit-bounce vibrations,which are dangerous dynamic phenomena typically encountered in the context of rotary drilling applications.Such a model takes into account two coupled degrees of freedom of drill-string vibrations.Moreover,it assumes a state-dependent time delay and a viscous damping for both the axial and torsional vibrations and relies on a sawtooth function to account for the cutting force fluctuation.In the frame of this theoretical approach,the influence of rock brittleness on the stability of the drill string is calculated via direct integration of the model equations.The results show that the rock brittleness has a great influence on the rotational speed and bit depth.
基金
This work was sponsored by the Major Science and Technology Project of the CNPC under Grant ZD2019-183-005.
