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近年来大位移井和复杂轨迹井眼的需求不断增加 ,对井下钻井工具的研制提出了新的要求。利用现有的动力导向技术 ,钻压施加困难 ,难以发挥高效钻头的作用 ,“滑动”方式下大摩阻的存在使井底工具面的控制难度加大 ,井眼水平延伸受到限制。为减小摩阻 ,使钻柱具有更大的延伸能力 ,实现对井眼轨迹的精确控制 ,国内外纷纷致力于井下可控工具和旋转导向闭环钻井系统的研究。本文介绍了 2类可实现井下全方位控制的偏置机构及目前国内外已有的几种旋转导向闭环钻井系统。
In recent years, the demand for large-displacement wells and complicated orbit trajectories has been constantly increasing, putting forward new requirements for the development of downhole drilling tools. With the existing power steering technology, it is difficult to exert weight-on-bit, which makes it hard to exert the effect of high-efficiency drill bit. The existence of large friction in the “sliding” mode makes it more difficult to control the bottom surface of the well and the horizontal extension of the borehole is limited. In order to reduce the friction and make the drillstring have greater extensibility and realize the precise control of wellbore trajectory, many research efforts have been devoted to the controllable tools and the rotary-steering closed-loop drilling system both at home and abroad. In this paper, two kinds of biasing mechanisms that can realize all-directional control in the well and several rotary-guide closed-loop drilling systems that are available at home and abroad are introduced.