测段选择对轨迹拟合精度的影响及其处理方法

Segment selection effect on directional well trajectory fitting accuracy and accurate measurement method

刘永旺 管志川 梁海明 魏凯 王伟 李春燕

LIU Yongwang GUAN Zhichuan LIANG Haiming WEI Kai WANG Wei LI Chunyan

中国石油大学石油工程学院，山东青岛　266555 长庆油田公司第二采油技术服务处，甘肃庆城　745100

Institute of Petroleum Engineering in China University of Petroleum, Qingdao 266555, China The Second Recovery Technology Service Department of Changqing Oilfield Co., Qingcheng 745100, China

目前的测斜计算方法将整个测段假设为某一种确定性质的曲线线段，而实际测段内井眼轨迹形状是未知的，因此计算得到的井眼轨迹与真实井眼轨迹间必然存在误差。为了分析测段选择对井眼轨迹拟合精度的影响，结合现场实际测斜数据，使用曲率半径法，对选择不同测段长度和选择不同测段位置2种情况下轨迹进行拟合，拟合结果表明，选择的测段长度不同时拟合的轨迹存在差异，选择的测段位置不同时拟合的轨迹亦存在差异。分析认为测段内钻进方式的频繁转换是导致该种误差的原因，提出了4种可以减小该类误差的测斜方法，并就其可实现性和存在的问题进行了探讨，以期通过精确测量、计算来实现井眼轨迹的精确定位。这对定向井精确中靶、丛式井防碰具有一定指导意义。

The current method of well survey calculation is assuming the segment is a specific curve, however, the actual well trajectory is unknown. Therefore, error exists between calculated and actual well trajectory. In order to analyze the relationship between the accuracy of trajectory fitting and segment selection，according to field data, radius of curvature method is used to match the two kinds of trajectory caused by segment selection. Fitting results show that there are errors between the fitting trajectories because of the different choice of the segment length and location. This paper makes a qualitative analysis of the causes of errors. The results show that the reason is the frequent conversion of drilling methods. Accordingly, four methods which can effectively decrease the errors of the well survey calculation are presented, and the feasibility of each method is discussed in order to acquire the exact position of wellbore trajectory by accurate measurement and calculation. The method has guiding significance to achieve perfect target of the directional well and the anti-collision of the cluster well.