磁力随钻测斜仪轴向磁干扰校正方法

针对磁力随钻测斜仪在受到轴向磁干扰时会出现方位角测量结果不准确的问题，在介绍磁力随钻测斜仪测量原理的基础上，研究了Russell法和短钻铤测量修正法2种间接磁干扰校正方法的原理及迭代计算过程，提出了矢量和法和钻具截面法2种直接磁干扰校正方法，并对这4种方法进行了数据仿真分析。数据仿真结果表明，直接校正方法计算简单，但具有一定的局限性；间接校正方法计算复杂，但具有较好的准确性。在其他井眼参数不变的条件下，方位角偏差随干扰磁场增强而增大；在轴向干扰磁场固定的情况下，方位角偏差随井斜角增大而增大，井斜角相同时，0°~360°范围内方位角偏差先增大后减小，呈现对称性；井眼轨迹接近水平东西方向时，轴向磁干扰的校正效果最差。4种校正方法均可以降低轴向磁干扰对方位角测量精度的影响，减少无磁钻铤的使用长度，具有较好的现场实用性。 

Correction Methods for Axial Magnetic Interference of the Magnetic Inclinometer while Drilling

When the magnetic inclinometeris subjected to axial magnetic interference while drilling,the measured azimuth is inaccurate.To deal with this problem,the measurement principle of magnetic inclinometer while drilling was introduced.Then,the principle and iterative calculation process of two indirect magnetic interference correction methods(i.e.,the Russell method and the short drill collar measurement correction method)were analyzed,and two direct magnetic interference correction methods(i.e.,vector sum method and drilling tool section method)were proposed.And finally,numerical simulations were performed for these four methods.Results indicated that direct correction methods are simple,but their calculation is limited in several ways.Indirect correction methods are complicated,but their calculation accuracy is higher.Meanwhile,the azimuth deviation increases with the increase of the interference magnetic fields while the other borehole parameters are unchanged.When the axial interference magnetic field is fixed,the azimuth deviation increases when the inclination angle increases.When the inclination angle is the same,the azimuth angle increases first and then decreases in the range of 0°-360°,revealing the symmetry.When the well trajectory is close to horizontal EW orientation,the correction effect of axial magnetic interference is the worst.All the four correction methods can be better applied in field. They can decrease the influence of axial magnetic interference on the measurement accuracy of the azimuth angle and reduce the service length of non-magnetic drill collar.