Abstract: The dynamics of roller cone bit under the interaction of drilling string,bit and rock during the drilling process was investigated. According to Hamilton's principle and finite element method,the models for vertical,lateral and torsion coupled vibration of full-hole drilling strings were established.On the basis of many experiments,the mechanics model for the interaction of roller cone bit and rock was established.On the system dynamics,the dynamics model for roller cone bit under the interaction of drilling string and rock was established. The solving method for the nonlinear system dynamics model of roller cone bit was presented.The dynamics emulation software for bit system was finished. Using the emulation software,the emulation tests under different drilling operational parameters,geometric parameters of drilling tool and different rock property were finished.The research work can help reveal the motion rule of drilling string and bit,dynamics characters and failure meachanism.It also offers theoretical reference and technical basis for scientific prediction and control of well trajectory.

Key words: roller bit, dynamics property, drilling string, coupled vibration, rock, interaction, mathematical model, emulation software

摘要： 研究了钻井过程中钻柱、钻头、岩石相互作用下的牙轮钻头动力学特性.根据汉弥尔顿原理和有限单元法,建立了全井钻柱纵向、横向扭转耦合振动动力学模型.在大量单元实验的基础上,建立了牙轮钻头与岩石相互作用力学模型.从系统动力学的角度出发,建立了基于钻柱、岩石相互作用下的牙轮钻头动力学模型.研究了牙轮钻头非线性系统模型的数值求解方法,编制了钻头动力学特性仿真分析软件,在不同钻井操作参数、钻具(钻柱、钻头)几何参数、地层性质条件下,对牙轮钻头动力学特性进行了仿真.明确了钻井过程中井下钻柱及钻头的运动规律、动力学特性、失效机理,为科学合理地预测和控制井眼轨迹提供了理论依据和技术手段.

关键词: 牙轮钻头, 动力学特性, 钻柱, 耦合振动, 岩石, 相互作用, 数学模型, 仿真软件