Nonlinear Dynamics of Directional Drilling with Bit-rock Interactions
Abstract
For the sake of exploring the motion and vibration law of drilling system and its mechanical properties during the gas drainage process, the nonlinear dynamics model of drilling system taken into account the interaction between drill string and rock, the contacts between drill string and borehole is proposed. Firstly, the coal-rock effect and gradual evolution characteristics of drilling failure are deeply analyzed, the nonlinear dynamics and constitutive equation of drilling system based on the Drucker-Prager failure criterion is established. Furthermore, aim at studying of the performance and characteristics of the nonlinear dynamics model by using FEA method, the explicit and implicit combination algorithm is taken into account to deal with the dynamic model. Finally, the case imitation results demonstrate that the motion and vibration of drilling system presented the complex non-linear, the longitudinal, lateral and torsional vibration of drill bit increase with the increase of WOB and rotational speed. A technological basis is provided for drill strings dynamics and vibration analysis of kilometers directional rig.