被动轮式推进器设计

针对连续管水平井钻进过程中存在的屈曲锁死、钻压不足等问题,设计一种基于钻柱侧向弹性的增强动力轮式推进器,可获得较高的轴向推拉力。应用钻柱纵横弯曲理论和齿轮-钻屑的几何关系,分别建立包含轮式推进器的底部钻具组合力学模型和蜗轮蜗杆卡阻力学模型,利用模型分析轮式推进器的工作特性。结果表明仅靠钻柱自重产生的推拉力有限,利用偏心垫块与推进器串联组合所产生的钻柱侧向弹性可大幅提高轴向推拉力;偏心垫块-推进器组合的轴向推拉力随两者间距的减小而增大、随偏心距增大而增大,较自重式推进器提高10倍。最大被卡钻屑尺寸随齿轮模数和齿数的增大而增大;卡阻力与钻屑和齿轮材料的强度比正相关。

Design of passive wheeled thruster

In order to solve the problems of buckling,and insufficient weight on bit in the horizontal drilling,an enhanced power wheeled thruster based on the lateral elasticity of drill string was designed to obtain higher axial thrust force.The mechanical model of the bottom hole assemble including the wheeled thruster based on the beam-column bending theory and the worm jamming model based on the gear-cuttings geometry relationship were established respectively.And then,the working characteristics of the wheeled thruster were analyzed by using these models.The results show that the axial thrust force generated by the self-weight of drill string is limited,but the lateral elasticity of drill string generated by the combination of the eccentric pad and the thruster in series can significantly increase the axial thrust force.The axial thrust force of the combination of the eccentric pad and the thruster increases with the decrease of the distance between them,and increases with the increase of the eccentricity,and the maximum thrust force is 10 times higher than that of self-weight thruster.The maximum size of the cuttings to be stuck increases with the increase of the module and the teeth number of the gear.The jamming resistance caused by the cuttings is positively related to the strength ratio of the cuttings and the gear material.