Qing Yin, Wang Lu, Zheng Yu
School of Engineering and Technology, China University of Geosciences (Beijing), Beijing 100083, China.
Micromachines (Basel). 2025 Mar 28;16(4):391. doi: 10.3390/mi16040391.
For Measurement While Drilling (MWD), the redundant Micro-Electro-Mechanical Systems Inertial Measurement Unit (MEMS-IMU) navigation system significantly enhances the reliability and accuracy of drill string attitude measurements. Such an enhancement enables precise control of the wellbore trajectory and enhances the overall quality of drilling operations. But installation errors of the redundant MEMS-IMUs still degrade the accuracy of drill string attitude measurements. It is essential to calibrate these errors to ensure measurement precision. Currently, the commonly used calibration method involves mounting the carrier on a horizontal plane and performing calibration through rotation. However, when the carrier rotates on the horizontal plane, the gravity acceleration component sensed by the horizontal axis of the IMU accelerometer in the carrier is very small, which leads to a low signal-to-noise ratio, so that the measured matrix obtained by the solution is dominated by noise. As a result, the accuracy of the installation is insufficient, and, finally, the effectiveness of the installation error compensation is reduced. In order to solve this problem, this study proposes a 45°-inclined six-position calibration method based on the selected hexagonal prism redundant structure for redundant MEMS-IMUs in MWD. Firstly, the compensation matrices and accelerometer measurement errors were analyzed, and the new calibration method was proposed; the carrier of the IMUs should be installed at an inclined position of 45°. Then, six measuring points were identified for the proposed calibration approach. Finally, simulation and laboratory experiments were conducted to verify the effectiveness of the proposed method. The simulation results showed that the proposed method reduced installation errors by 40.4% compared with conventional methods. The experiments' results demonstrated reductions of 83% and 68% in absolute measurement errors for the and axes, respectively. As a result, sensor accuracy after compensation improved by over 25% compared with traditional methods. The calibration method proposed by this study effectively improves the accuracy of redundant systems, providing a new approach for the precise measurement of downhole trajectories.
对于随钻测量（MWD）而言，冗余微机电系统惯性测量单元（MEMS - IMU）导航系统显著提高了钻柱姿态测量的可靠性和准确性。这种提高使得能够精确控制井眼轨迹并提升钻井作业的整体质量。但是冗余MEMS - IMU的安装误差仍然会降低钻柱姿态测量的准确性。校准这些误差对于确保测量精度至关重要。目前，常用的校准方法是将载体安装在水平面上并通过旋转进行校准。然而，当载体在水平面上旋转时，载体中IMU加速度计水平轴所感测到的重力加速度分量非常小，这导致信噪比很低，使得通过求解得到的测量矩阵受噪声主导。结果，安装精度不足，最终降低了安装误差补偿的有效性。为了解决这个问题，本研究针对MWD中的冗余MEMS - IMU提出了一种基于选定六边形棱柱冗余结构的45°倾斜六位置校准方法。首先，分析了补偿矩阵和加速度计测量误差，并提出了新的校准方法；IMU的载体应安装在45°的倾斜位置。然后，为所提出的校准方法确定了六个测量点。最后，进行了仿真和实验室实验以验证所提方法的有效性。仿真结果表明，与传统方法相比，所提方法将安装误差降低了40.4%。实验结果表明，对于 轴和 轴，绝对测量误差分别降低了83%和68%。结果，补偿后的传感器精度比传统方法提高了25%以上。本研究提出的校准方法有效地提高了冗余系统的精度，为井下轨迹的精确测量提供了一种新方法。
