考虑磁偏角时空变化的实钻轨迹精准定位  

Positioning the drilled borehole trajectories considering the magnetic declination change in space-time

作　　者：刘修善[1] 

机构地区：[1]中国石油化工股份有限公司石油工程技术研究院,北京100101

出　　处：《石油学报》2017年第6期705-709,共5页Acta Petrolei Sinica

基　　金：国家重大科技专项(2011ZX05005-006)资助

摘　　要：现行的井眼轨迹监测方法以网格北为指北基准,没有考虑子午线收敛角和磁偏角沿井眼轨迹和随时间的变化,致使北坐标、东坐标等参数明显存在误差。建立了以真北方向为指北基准的井口坐标系,通过揭示井口坐标系与大地坐标系之间的转换关系,提出了高精度井眼轨迹监测方法。这种高精度监测方法考虑了磁偏角的时空变化,利用国际地磁参考场随时随地求取磁偏角,并且不涉及子午线收敛角问题。结果表明:高精度监测方法与现行监测方法算得的垂深和水平长度相同,但北坐标、东坐标、水平位移和平移方位等参数不同。在地图投影变形大、地磁场变化大的地区钻井,尤其是钻大位移井,现行监测方法的计算误差可达数米,因此应使用高精度监测方法。The currently used borehole trajectory monitoring method takes grid north as the reference datum without considering the changes of meridian convergence angle and magnetic declination along the borehole trajectory over time,leading to an apparent error in parameters such as north coordinate and east coordinate.In this study,the wellhead coordinate system was established by taking true north direction as the reference datum to reveal the conversion relationship between the wellhead coordinate system and geodetic coordinate system,so as to present a high precision borehole trajectory monitoring method.The spatiotemporal variation of magnetic declination was taken into account in this method.It can calculate the magnetic declination at anytime and anywhere using the international geomagnetic reference field,not involving the meridian convergence angle.The results show that the high precision monitoring method and the current monitoring method yield the same results for vertical depth and horizontal curvilinear departure length,but different for the parameters such as north coordinate,east coordinate,horizontal displacement and its azimuth.During the drilling in the areas with large map projection deformation and great magnetic field changes,especially drilling the extended-reach wells,the current monitoring method may have the calculation error up to several meters,so the high precision monitoring method should be used.

关 键 词：钻井理论 定向钻井 井眼轨迹 监测方法 定位方法 

分 类 号：TE243[石油与天然气工程—油气井工程]