中文摘要：

靶心距计算是定向井和水平井井身质量检查中的一项重要内容，靶心距计算的核心内容是求入靶点的坐标。入靶点是井眼轨迹与某个空间平面的交点：对于定向井，该平面是圆形靶圈所在的水平面；对于水平井，该平面是靶体轴线的垂直平面。根据点与平面的有向距离的概念给出了入靶点所在井段的扫描算法，该算法能快速确定入靶点所在井段。对求解入靶点关键参数方程的数值迭代法——二分法及其收敛性能进行了详细研究，并给出了在空间圆弧、圆柱螺线、自然曲线等3种井段曲线类型情况下的详细计算公式。理论及实际算例表明，二分法是求入靶点数值解的非常有效的算法。入靶点所在井段的扫描算法和求入靶点关键参数数值解的二分法在中靶分析、邻井法面距离扫描、井眼轨迹监控中也有很重要的应用价值。图6表3参12

英文摘要：

The calculation of the distance to target center is important in the trajectory quality inspection, and its core is to solve the coordinate of the entry point to targets. The entry point is a cross point of trajectory and a spatial plane： in directional wells, this plane is the horizontal plane; in horizontal wells, it is the vertical plane of the target axis. A scanning algorithm for target entry interval is given according to the concept of directed distance from point to plane. This method can fast determine the target-entry interval. This paper studies the numerical iterative method - bisection and its convergence performance, which is used to solve the key-parameter equation of target-entry point, and gives detailed formulas for three interval curve types of spatial arc, cylindrical helical and natural curve. Theoretical and practical cases show that bisection method is very effective in solving the numerical solution of target-entering point.