密集丛式井磁干扰情况下防碰判断与控制方法

Anti-collision Judgment and Control Method under Magnetic Interference of Dense Cluster Wells

南堡油田密集丛式井钻井密度大,井口间距小,同一平台开发时间跨度大,新老井眼轨迹空间交叉密集,钻井防碰问题突出,特别是上部井段轨迹间距小,实钻过程中时常存在磁干扰现象,采用常规防碰扫描计算方法存在不足,不能完全满足密集井口安全钻井的需要。根据正钻井与邻井轨迹在防碰点处的几何关系,提出了井眼轨迹的异面角概念,通过异面角的分析,可判断正钻井与邻井的空间关系。在分析测量工具对套管磁场的感应距离,测点到钻头距离等的基础上,提出了切入角的概念。根据MWD磁干扰小间距、测点与钻头间的距离以及井眼轨迹的空间关系,总结出了磁干扰状态下的两种防碰关系,并建立了钻井防碰判断与控制方法。通过现场实例证明,该方法丰富了密集丛式井上部井段小间距磁干扰情况下钻井防碰与控制方法。

In Nanpu oilfield,dense cluster wells are with high drilling density,small wellhead spacing,large development time span of the same platform,and dense intersecting of new and old wellbore trajectories.The problem of drilling collision prevention is prominent,especially the track spacing of upper well sections is small,and magnetic interference often exists in the actual drilling process.The conventional anti-collision scanning calculation method is insufficient and can not fully meet the needs of safe drilling of dense wells.According to the geometric relationship between positive drilling and adjacent well trajectory at collision prevention point,the concept of out-of-plane angle of well trajectory is put forward.Through the analysis of the out-of-plane angle,the spatial relationship between the positive well and the adjacent well can be judged.On the basis of analyzing the sensing distance of the measuring tool to the casing magnetic field and the distance from the measuring point to the drill bit,the concept of the cut-in angle is proposed.According to the small spacing of MWD magnetic interference,the distance between the measuring point and the drill bit,and the spatial relationship of the borehole trajectory,two anti-collision relationships under the state of magnetic interference are summarized,and the drilling anti-collision judgment and control method are established.Field examples prove that this method enriches the methods of anti-collision and control of drilling under the condition of small spacing magnetic interference in the upper sections of dense cluster wells.