水平井钻柱仿蚯蚓振/蠕动载荷传递及控制机理研究

The influence of the drilling string vibration transmitting on the drilling efficiency and the maximum horizontal extension of horizontal well, has become a hot but also difficult research topic in horizontal well drilling technology. Based on the demand of multi-point excitation, and referencing its use pattern of earthworms on friction during borrowing and creeping, this project proposed the “Earthworm Bionic Vibration/Wriggle Load Transmitting Method” for horizontal wells. Considering the various factors, including the wellbore characteristics, drill string vibration/wriggle, mud cake and cutting bed, the calculation model of friction coefficient between drill string and borehole wall is established to reveal the friction mechanism between drill string and borehole wall. The finite element model of vibration/wriggle for the drill string in horizontal wells, which includes the vibrator’s stiffness and the lateral force induced by the dual-directional multi-point excitation, is established, also the judge criterion of motion, inducing condition and excitation method of vibration/wriggle are established. Sifting the dominating factors which influence the load transmitting under vibration or wriggle condition and carrying out experiment verifying the calculation result. The “Earthworm Bionic Vibration/Wriggle Load Transmitting Controlling Method”, which is based on the hook hanging load, the amplitude and frequency of vibration, the vibrator position and other factors, is established. The research results provide theoretical support for the horizontal well drilling, the wellbore trajectory design and calculation of friction torque in the drilling pipe mechanics.

水平井钻柱载荷传递影响水平井钻进效率和极限延伸距离，已成为当前水平井钻井技术领域研究的热点和难点问题。本项目基于多点激振减摩阻需求，借鉴蚯蚓在打洞和爬行过程中对摩擦力的分解和利用方式，提出“水平井钻柱仿蚯蚓振/蠕动载荷传递方法”。建立考虑井壁特性、钻柱振/蠕动、泥饼和岩屑床等因素的钻柱与井壁之间摩擦系数的计算模型，揭示钻柱与井壁的摩擦作用机制；引入振动短节自身刚度、多点双向激振、钻柱屈曲引起的附加井壁接触力，建立水平井钻柱振动/蠕动载荷传递有限元模型，建立钻柱振/蠕动状态判别标准，分析其诱发条件和激发方法；筛选影响钻柱振动、蠕动两种状态下载荷传递的主控因素并进行实验验证；建立基于大钩悬重、振动短节数量和位置、激振力幅值和频率等因素的水平井钻柱仿蚯蚓振/蠕动载荷传递控制方法。研究成果为水平井钻进、井眼轨迹设计、管柱力学中摩阻扭矩计算提供理论依据。

本项目基于蚯蚓运动原理提出钻柱蠕动载荷传递方法，不同于传统弹性送钻模式下单纯追求减小钻柱与井壁之间摩阻的思路，该方法反其道而行通过利用反向运动钻柱段与井壁之间的摩阻促进钻柱传递载荷。首先，建立考虑振动短节多点双向延迟激振、粘滞摩擦和钻头边界的钻柱动力学模型及求解方法；其次，分析弹性和蠕动式送钻模式下的钻柱载荷传递和运动特征，提出并论证了“提高粘滞和反向运动钻柱段比例”是蠕动式载荷传递方法提高钻柱载荷传递效率的内在机制；最后，开展室内实验验证模型计算结果。研究结果证明了所提出的蠕动式载荷传递方法的可行性，对于提高长水平段水平井的载荷传递效率和极限延伸距离，推动非常规和深水油气资源的高效、低成本开发具有重要意义。