邻井定向分离系数计算方法

随着丛式井和加密井设计间距的不断减小,仅利用邻井距离扫描计算和传统分离系数监测邻井距离已不能满足现场需求。定向分离系数不仅将井眼轨迹误差分析与邻井距离扫描计算结合在一起,而且考虑了参考点和比较点误差椭球的相对位置关系,与传统分离系数相比,其可以更精确地反映邻井的交碰概率,为邻井防碰决策提供更为科学的依据,以更好地满足现场需求。对比了传统分离系数和定向分离系数的区别;利用空间解析几何方法实现了法面距离扫描、最近距离扫描及水平距离扫描定向分离系数的计算,一般把最近距离扫描定向分离系数作为邻井防碰的依据。实例计算分析表明,在以定向井、大位移井为主要构成的丛式井中,传统分离系数的计算结果比定向分离系数小得多;定向分离系数在丛式井和加密井的设计和钻井过程中都具有十分重要的现场应用价值。 

Calculation Method of Adjacent Well Oriented Separation Factors

With the decreasing of adjacent well design spacing of cluster wells and infill wells,only using adjacent well distance scanning calculations and traditional separation factors to monitor the adjacent well distances of cluster wells cannot meet the demand of practical project.Wellbore trajectory error analysis and adjacent well distance scanning are combined,and the relative positions between reference point error ellipsoids and comparison point error ellipsoids are considered in the calculation of oriented separation factors.The oriented separation factors are more accurate than traditional separation factors to describe the probability of hole intersection,and the oriented separation factors can provide a more scientific basis for adjacent well anti-collision.So the oriented separation factors can better meet the demand of practical project.The difference between oriented separation factor and traditional separation factor was introduced,and the oriented separation factors of normal-plane distance scanning,the nearest distance scanning and horizontal distance scanning were obtained with the method of space analytic geometry.The oriented separation factors of the nearest distance scanning are generally used to be the basis of adjacent well anti-collision.Finally,a calculation example was given,and the result indicated that the traditional separation factors was smaller than the oriented separation factors in cluster wells which were mainly constituted by directional wells and extended reach wells,and the oriented separation factors had important field application value in the design and drilling process of cluster wells and infill wells.