The lateral vibration of a bottom hole assembly (BHA)has a great effect on its fatigue life,and causes well trajectory control problems.Here,a nonlinear dynamic model of BHA was set up considering the interaction between bit and rock,the dynamic coupling among axial,lateral and torsional vibrations,and the contact between BHA and a borehole well.The lateral vibration characteristics of BHA were studied by utilizing the finite element method.The results showed that the lateral vibration of bit is obvious and stochastic during drilling,and its vibration strength belongs to an unsafe level according to the standard provided by Baker Hughes INTEQ Co;with increase in the drill collar's distance from bit,its lateral vibration strength decreases exponentially,and tended to be stable after the distance reaches 50 m;the vibration strength of the drill pipe is similar to that of the drill collar near bit;the lateral vibration of BHA increases with increase in RPM(revolution per minute)or WOB (weight on bit).The study provided a new method for indicating the dynamic characteristics of BHA,and offered a guidance for choices of drilling parameters of a bottom hole assembly.%针对横向振动引起下部钻具失效的问题，基于钻头破岩钻进，并考虑钻具纵横扭耦合以及钻具与井壁随机接触，建立了系统非线性动力学模型，研究下部钻具横向振动特性。结果表明：在常用的牙轮钻头单扶下部钻具组合钻进过程中，钻头横振表现出较强的随机性，根据贝克休斯公司对钻具振动的量化标准，其强度属于剧烈分区；钻铤横振强度随其与钻头距离增大而近似呈指数递减，并在距钻头约50 m 以后趋于稳定；钻铤上接的钻杆与近钻头钻铤的横振强度相当；下部钻具横振强度随钻压、转速增大而增大。考虑了牙轮钻头破岩钻进与下部钻柱的交互影响，对进一步揭示下部钻具的横振特性以及参数优选具有积极意义。
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