限定目标点井眼方向待钻轨道设计新方法

NEW METHOD FOR HOLE TRAJECTORY DESIGN WITH A REQUIRED DIRECTION AT TARGET

限定目标点井眼方向待钻轨道设计是定向井尤其是水平井轨迹控制的重要技术之一,对于提高井眼轨迹控制精度和中靶精度有极为重要的作用。从轨道的约束个数和未知参数个数相等的原则出发,分析认为“斜面圆弧段+直线段+斜面圆弧段”是最简单且合理的剖面形式。在此基础上,提出了一种新的限定目标点井眼方向待钻轨道设计方法———逐点寻优设计法,并对其进行了改进,将二元显函数的最优值问题转化为一元显函数的最优值问题,形成了改进型逐点寻优设计法,给出了该方法的计算步骤,并进行了算例分析,证明了该设计方法的正确性。计算过程和结果表明,改进型逐点寻优设计法避开了求解非线性约束方程组,是一种有效而可靠的限定目标点井眼方向待钻轨道设计方法。

Design of hole trajectory being restricted to the required direction at its target is very important for well trajectory control in directional and horizontal well.It can be used to improve the ability of well trajectory control and target hitting.According to the principle that the number of constraints and unknowns of well trajectory should be equal,the paper provides all the possible profiles and demonstrates that a three-section profile with two planar circular arcs and one straight line is the simplest and right profile for correctional well-path with a required direction at target.On the basis of it,a new method called Path-Seeking One-by-One is presented to avoid solving the nonlinear constraint equation set.To reduce the computing time used on Path-Seeking One-by-One to reasonable range,the function with two independent variables for path-correction planning is abandoned and a new function with one independent variable is constructed.The method based on the new function is called modified Path-Seeking One-by-One.The steps of the method is described and a planning example is solved and analyzed.The result shows that the method of modified Path-Seeking One-by-One neednt solve the nonlinear constraint equation set and is an efficient and reliable method.