导向钻井工具冗余姿态测量与系统重构方法

Redundant posture measurement and system reconfiguration method of steering drilling tool

为实现调制式导向钻井工具井眼轨迹的精确可靠控制,导向钻井工具井下姿态的实时测量至关重要。针对恶劣工况下测量系统可靠性差的问题,提出了一种非正交四轴重力加速度计的姿态测量方法,给出了对应的姿态参数求解和信号有效性判定公式。针对小井斜状态下姿态参数测不准问题,提出了四轴重力加速度计初始倾斜安装的非正交测量方法,显著提高了测量精度。针对井下恶劣工况中加速度计易损易失效问题,提出了双冗余非正交四轴重力加速度计测量方法,给出了双冗余重力加速度计关联信号的相互转换公式,讨论了依据信号特征判定重力加速度计故障的方法及故障诊断流程,并据此建立了系统重构方案。水力驱动测试实验表明,工具姿态测量准确,控制平台角度位置稳定。

Real-time downhole posture measurement of steering drilling tool is vital to realize exact reliable control on the well trajectory of modulated steering drilling tool.Aiming at the poor reliability of measurement system under atrocious working environment,this study proposes a posture measurement method based on nonorthogonal quadri-axle gravity accelerometers,and the corresponding posture parameter solution and signal effectiveness judgment formulas are also given.As for inaccurate posture parameter under the status of small borehole deviation,a nonorthogonal measurement method is proposed,which depends on the quadri-axle gravity accelerometers installed with an initial tilt,so as to improve the measurement accuracy.To cope with problems that the accelerometer tends to fail or be destroyed in atrocious downhole environment,a measurement method is presented based on dual redundant nonorthogonal quadri-axle gravity accelerometers.Then the mutual conversion formula between relative signals of dual redundant gravity accelerometer is given.Moreover,this study discusses the judgment method and diagnosis process of gravity accelerometer fault based on signal characteristics,based on which a system reconfiguration scheme is established accordingly.The hydraulic driving test results indicate that tool posture measurement is accurate,and the stable control of platform angle is achieved.