旋转扶正底部钻具组合滑动钻进受力分析与优化

Force analysis and optimization of rotary steerable bottom hole assemblies in slide drilling

摘要:

为解决传统水平井“单弯单稳”底部钻具组合在滑动钻进时的托压和井斜问题，提高钻进效率和井下安全，创新性地提出一种旋转扶正底部钻具组合，基于前期的现场试钻效果和数据资料，并应用纵横弯曲梁理论建立底部钻具力学模型，重点对钻头侧向力与扶正器摩阻进行计算，模拟分析了不同结构参数、井身参数和钻井参数下力学性能变化规律。结果表明：螺杆弯角度数的改变对钻头侧向力和扶正器摩阻的影响并不明显，根据实际情况，不推荐使用弯角过大的螺杆，以减小井壁对钻具的磨损；扶正器外径与钻头到扶正器距离对钻头侧向力和摩阻的影响较为显著，在对结构参数进行优化时，可结合不同井身参数，主要采取调整扶正器外径和位置的方式满足不同造斜需求；为提高钻进效率和井下安全，推荐该钻具组合采用的扶正器外径范围为0.214~0.215 m，弯角度数范围为1.5°~2.5°，扶正器到钻头距离为0.4~1 m，弯点到扶正器距离为1.4~1.8 m。研究结果可指导旋转扶正底部钻具组合结构参数的优化设计，指导该工具的现场应用，以提高造斜段滑动钻进的造斜效果，降低托压风险，具有工程指导意义。

Abstract:

To address drag resistance and inclination control issues during slide drilling with traditional “single-bend single-stabilizer” bottom hole assemblies （BHAs） in horizontal wells， improving drilling efficiency and downhole safety， this study innovatively proposes a rotating stabilizer BHA. Based on previous field trial results and data， a mechanical model of the bottom hole assembly was established using longitudinal and transverse beam bending theory， focusing on calculating drill bit lateral force and stabilizer friction resistance. Simulations analyzed changes in mechanical performance under varying structural parameters， wellbore parameters， and drilling parameters. The results indicate that： Changes in the positive displacement motor bending angle have no significant effect on drill bit lateral force or stabilizer friction resistance. Considering practical conditions， using motors with excessively large bending angles is not recommended to minimize drilling tool wear caused by the wellbore wall； The outer diameter of the stabilizer and the distance from the drill bit to the stabilizer significantly influence drill bit lateral force and friction. When optimizing structural parameters， these stabilizer attributes can be primarily adjusted in conjunction with wellbore parameter conditions to meet different inclination requirements； To enhance drilling efficiency and downhole safety， it is recommended to employ this assembly with a stabilizer outer diameter range of 0.214 to 0.215 meters， a bending angle range of 1.5 to 2.5 degrees， a distance from the stabilizer to the drill bit of 0.4 to 1 meter， and a distance from the bending point to the stabilizer ranging from 1.4 to 1.8 meters. These findings can guide the optimization design of the rotating straightening bottom hole assembly’s structural parameters， support its field application， improve inclination control during sliding drilling in deviated sections， reduce pressure support risks， and possess practical engineering significance.