Abstract: Based on the interaction of bit and formation,the force from the rock and bit is used for the boundary condition of the end of the drill string.As simplified by the elastic bar theory and FE method,a torsional vibration model for the drill string simulates the bit/formation interaction and elastic deformation of the drill string is established.The torsional model is solved by numerical method by considering the boundary condition and initial condition.The theoretical work in this paper is the basis for the dynamic behavior and kinetics of drilling string and rock bit and for well orbit control early failure prevention.

Key words: string, rock, bit, dynamics, torsional vibration, model

摘要： 在建立了牙轮钻头与井底岩石互作用模型的基础之上,将钻头与井底岩石互作用力矩作为钻柱的下端边界条件.在适当简化的条件下,利用弹性杆理论和单元法,建立了在钻井过程中由于钻头与岩石互作用和钻柱弹性变形而导致钻柱产生扭转振动的动力学模型.在给定初始条件和边界条件的情况下,采用数值计算方法求解了钻柱扭振模型.为进一步弄清钻头、钻柱在井底的实际运动规律和动力学性能,控制井眼轨迹,预防钻杆早期失效奠定了理论基础.

关键词: 钻柱, 岩石, 钻头, 动力学, 扭振, 模型