Research on the dynamics of drillstring considering bit–rock nonlinear interaction

This study focuses on the nonlinear dynamic characteristics of the bottom hole assembly (BHA). One of the most important features of this work is that the nonlinear interaction model of polycrystalline diamond compact (PDC) bit and rock is proposed. The PDC bit dynamic characteristics are used as the boundary conditions of the drillstring dynamic model. To more realistically simulate the drillstring dynamics, the drillstring dynamic model is established with the beam finite element method and solved by the generalized-α method. The model is verified by the field data. The PDC bit dynamic characteristics are analyzed, and the effects of weight on bit, rotation speed and rock drillability on the drillstring dynamic behavior are discussed. We hope that our research will aid in the development of the drillstring dynamics in the future.