斜直井眼中钻柱的动力学特性分析

Analysis of dynamic characteristics of drillstring in straight hole

胡以宝 狄勤丰 姚建林 姚永汉

HU Yibao DI Qinfeng YAO Jianlin YAO Yonghan

上海大学上海市应用数学和力学研究所，上海　200072

Shanghai Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072, China

为研究和控制钻柱动力学特性，分析斜直井眼中全井钻柱的受力变形特点，建立了钻柱动力学模型，利用节点迭代法解决了利用整体有限元法计算钻柱动力学特性较困难的问题，并应用节点迭代有限元法研究了钻柱的涡动轨迹和涡动速度等动力学特性。在转盘转速为120 r/min时,在给定的钻柱结构下，井深5256 m处的涡动速度达252 r/min，井深261~732 m处的钻柱应力波动幅值约为15 MPa。结果表明，钻柱内的这种应力波动或涡动特征是导致钻柱失效的重要因素，控制钻柱内的动态应力水平对钻柱失效事故的降低十分重要。

This paper is to study and control the dynamic characteristics of drillstring in a straight hole. The stress and deformation of drillstring is analyzed and a dynamic model of drillstring is established. The dynamic characteristics including whirl orbit and whirl speed of drillstring are studied through finite element method. The whirl speed at depth 5256 m reaches 252 r/min while the table rotary speed is only 120 r/min. The stress fluctuation at depth 261-732 m rises up to 15 MPa. The results show that the stress fluctuation in drillstring is the major factor for drillstring failure, and the control of the drillstring dynamic stress is important to minimize the drillstring failure.