磁性随钻测斜仪所需无磁钻具长度及影响因素研究

Research on the Length of Non-Magnetic Drilling Tools for Magnetic Inclinometer while Drilling and Its Influence Factors

钻井过程中,磁性随钻测斜仪需要放置在无磁钻具中,以避免铁磁钻具磁化后感应磁场的干扰,但针对无磁钻具长度选取及影响因素的理论研究较少。为此,利用ANSYS有限元软件,建立了三维静态均匀强磁场,模拟得到了磁性随钻测斜仪所需无磁钻具的长度,并分析了井斜角、方位角、铁磁钻具壁厚和铁磁钻具长度等因素对磁性随钻测斜仪所需无磁钻具长度的影响。分析结果表明,磁性随钻测斜仪所需无磁钻具的临界长度与井斜角、方位角无明显的相关关系,与铁磁钻具壁厚、长度正相关;根据模拟数据,分析了井斜角和方位角对方位角偏差的影响,认为当存在固定轴向干扰磁场时,方位角偏差随井斜角、方位角变化而变化,这与施工经验相吻合。无磁钻具长度的优化方法和优化结果,为实际工程应用中磁性随钻测斜仪所需无磁钻具长度的优选提供了理论依据和参考。

While drilling,a magnetic inclinometer should be placed inside the non-magnetic drilling tool to avoid the interference of magnetic fields induced by the magnetization of the ferromagnetic drilling tool.However,only a few theoretical studies focus on the influence and determination of the length of non-magnetic drilling tools.Therefore,with ANSYS,a finite element software,a 3D homogeneous strong static magnetic field was created,and the length for the non-magnetic drilling tools needed by the magnetic inclinometer were simulated,with the influences of inclination angle,azimuth angle,and the thickness and length of ferromagnetic drilling tool,etc.The results show that the critical length of the non-magnetic drilling tool had no obvious relationship with the inclination angle and azimuth angle,however,it had a positive correlation with the thickness and length of the ferromagnetic drilling tool.Based on simulated data,the influence of the inclination angle and azimuth angle on the deviation of the azimuth angle was analyzed.It was found that with a fixed axial interference magnetic field,the deviation of the azimuth angle varied with the change of inclination angles and azimuth angles,which was consistent with field practices.The optimized method and result of non-magnetic drilling tool length can serve as reference and theoretical basis for the length determination of non-magnetic drilling tool for magnetic inclinometer in actual survey practices.