Abstract: As a core technology for the long-term economical development of shale gas, horizontal wells experience a sharp increase in borehole drag and rotational torque with lateral extension. This leads to severe differential sticking incidents that cause extreme operational challenges in weight-on-bit (WOB) loading and control, which triggers the erratic tool face orientation oscillations during sliding directional drilling, significantly compromising the wellbore trajectory control. Drilling robots apply traction force near the drill bit, assisting in WOB loading and control while overcoming borehole drag. Capable of real-time WOB modulation, drilling robots can be further employed to achieve the precise loading and adjustment of near-bit drilling parameters, thereby providing a novel technological paradigm for the trajectory control of ultra-long horizontal wells. A finite element method is utilized to establish a dynamic model of the drill string system integrated with drilling robots. This model comprehensively accounts for the effects of wellbore trajectory on friction and gravity distribution, and incorporate the dynamic coupling characteristics among reactive torque, WOB, and rate of penetration (ROP). Building upon the traction force formula, a positive feedback mechanism between traction force and WOB is introduced and integrated with the dynamic model to establish a dynamic traction control model. Based on these models, investigations into drilling parameters and trajectory control methods are conducted. By analyzing the formation mechanisms and transmission laws of drillstring reactive torque and reactive torque angle, the influence mechanisms underlying the drilling robot’s traction force on the reactive torque angle are elucidated, and a setpoint loading control method for the reactive torque angle is proposed. It is further discovered that by regulating the periodic traction velocity fluctuations, the tool face angle can be induced to fluctuate periodically around a setpoint with a specific amplitude. The fluctuation ranges and periodic regulation laws of WOB, ROP, and tool face angle are clarified, providing a theoretical basis for trajectory control based on drilling robots.

Key words: drilling robot, ultra-long horizontal well, drilling parameter, wellbore trajectory, tool face angle

摘要： 水平井作为页岩气经济长效开发的核心技术,随着水平段延伸,钻进摩擦阻力与扭转摩擦阻力急剧增大,导致严重托压,使得钻压加载与控制异常困难,引发滑动定向钻进中工具面角无序波动,显著增加井眼轨迹控制难度。钻井机器人可在近钻头处提供牵引力,在克服钻进摩擦力的同时辅助钻压加载与控制。基于其对钻压的调控作用,进一步利用钻井机器人实现近钻头钻井参数的精准加载与调节,为超长水平井井眼轨迹控制提供了全新技术路径。采用有限元方法构建钻井机器人钻柱系统动力学模型,该模型综合考虑井眼轨迹对摩擦力和重力分布的影响,融合反扭矩与钻压、钻速的动态耦合特性。在牵引力计算公式基础上,引入牵引力与钻压的正反馈作用机制,与动力学模型结合形成牵引力动态控制模型。基于上述模型,开展钻井参数与轨迹控制方法研究。通过解析钻柱反扭矩及反扭角的形成机理与传递规律,揭示了钻井机器人牵引力对反扭角的影响特性,并提出反扭角定值加载控制方法。结果表明,通过调控钻井机器人牵引速度的周期性波动,可使工具面角围绕稳定中心、以特定幅度产生周期性波动,明确了钻压-钻速-工具面角的波动范围与周期调控规律,为基于钻井机器人的轨迹控制提供了理论依据。

关键词: 钻井机器人, 超长水平井, 钻井参数, 井眼轨迹, 工具面角