基于加速度计和磁强计的方位测量与校正技术研究

根据随钻测量的要求,描述了基于三轴加速度计与三轴磁强计测量钻具方位的方法,并针对铁磁性材料造成干扰磁场对方位测量引入的误差,提出了两种利用当地地磁场进行方位校正的方法--直接校正法和间接校正法,前者通过校正公式直接进行校正,后者通过循环递推逐次收敛于真实的方位.在原理分析的基础上,得出具体的校正算法,并通过数据仿真进行验证.结果表明,两种校正方法均能消除钻具干扰磁场的影响,获得准确的方位角,因此可以大大减少无磁钻铤的长度,节省钻进成本.

Research on azimuth measurement and correction technique with accelerometer and magnetometer

According to the demands for attitude measurement while drilling, this paper introduces an approach for determining the azimuth with three mutually orthogonal accelerometers and magnetometers. In order to compensate for the effects of perturbing magnetic fields associated with magnetized sections of the drill collar, two correction techniques-direct correction and indirect correction are proposed, which rely on the knowledge of local geomagnetic field. The former adopts direct correction formula, and the latter adopts constant convergence algorithm. The correction algorithm and corresponding correction process are described. Finally the correction validity is proved by simulation data. Results show that the correction techniques can eliminate the bad effects by perturbing magnetic fields and determine the accurate azimuth, so they can minimize the length of non-magnetic drill collar and save drilling costs greatly.