As one of the most advanced international drilling technologies at present, rotary steering has been extensively applied to large-displacement, long-distance horizontal, and complex structural wells with numerous advantages, such as strong steering deflecting capacity and good borehole quality. Push-the-bit rotary steering is nowadays commercially applied on a large scale. In the bottom hole assembly (BHA) design of push-the-bot rotary steering drilling, flexible pup joints are the main components that exert an important effect on the exertion of steering deflecting capacity of push-the-bit rotary steering tools. The effect of flexible pup joints on steering capacity of BHA used in the push-the-bit rotary steering drilling process was investigated through a finite element analysis and their action laws were summarized. The results indicated that in order to optimize the deflecting capacity of rotary steering drilling tools, flexible pup joints should be installed cooperatively so as to obtain greater steering drilling capacity. In the rotary steering drilling process, as the outer diameter of flexible pup joints increased, the maximum stress of the BHA decreased. Side cutting force of the drill would increase with the length of pup joints, but this would result in degradation of anti-torsion performance of the BHA.

中文翻译：

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柔性短节对推钻式旋转转向偏转力影响的有限元分析

旋转导向作为目前国际上最先进的钻井技术之一，具有导向偏转能力强、钻孔质量好等诸多优点，已广泛应用于大排量、长距离水平、复杂结构井。推钻式旋转转向现在已大规模商业应用。在推进式旋转导向钻具的底部钻具组合（BHA）设计中，柔性短节是影响推进式旋转导向工具导向偏转能力发挥的主要部件。通过有限元分析研究了柔性短节对推钻旋转导向钻井过程中BHA导向能力的影响，总结了其作用规律。结果表明，为了优化旋转导向钻井工具的偏转能力，应配合安装柔性短节，以获得更大的导向钻井能力。在旋转导向钻井过程中，随着柔性短节外径的增大，BHA的最大应力减小。钻头的侧切削力会随着短节长度的增加而增加，但这会导致BHA的抗扭性能下降。