深井中钻柱动力学机理研究

为合理设计深井中的钻柱结构，提高钻具寿命，防止井下断钻具事故，讨论了钻柱的纵向振动、横向振动、扭转振动及进动之间的相互耦合关系，并指出了钻柱振动的危害和减少振动的现场措施。介绍了两种研究钻柱振动动力学的方法──有限元法和机械阻抗法。经举例说明深井中大井眼小钻铤的危害性，认为大井眼小钻铤的环空较大，钻铤的刚度较弱，在轴向力作用下易屈曲，激发横向振动，且钻铤的横向变形较大，因振动引起的交变应力也较大；纵向振动易出现动力失稳而诱发横向振动，横向振动又易诱发扭转振动。建议使用大井眼大钻铤设计方案。

Dynamic mechanism of drillstring in deep well

To design reasonable drillstring assembly in deep wells, improve the service life of drill tools and prevent the tools from rupturing, the coupling relations among the longitudinal vibration, lateral vibration, torsional vibration and precession of the drillstring is investigated, and the harmfulness of drillstring vibration is pointed out and measures for reducing vibraion are presented. Two methods for dynamic study of drillstring vibration, finite element method and mechanical impedance method, are inteduced. The harmfulness of using small drill collar in deep holes with large diameters is illustrated. It is recommended to adopt the design scheme of using large drill collar in large holes.