最小曲率法测斜计算中的数值方法

最小曲率法是测斜计算、井眼轨道设计中最常用的方法之一,在井眼轨迹计算中有广泛的应用。本文研究了最小曲率法计算机数值计算中的几个细节问题,给出了零井斜角测点的方位角定义,阐述了零井斜角测点方位角的二义性。分析了坐标增量计算过程,给出了减小三角函数计算次数的算法。对小弯曲角情形的坐标计算使用高精度近似公式代替容易产生除法溢出的直接计算,提高了计算过程的稳定性和计算精度。对水平投影长度的计算给出了使用Gauss数值积分法的精确计算方法。本文提出的方法可以用于使用最小曲率法时的井眼轨道计算的计算机软件开发,提高计算机软件的计算稳定性和计算精度。对涉及井眼轨迹计算的其他实际问题如定向井中靶分析预测、井眼轨迹控制、井身质量检查等都有一定的参考价值。

THE NUMERICAL METHOD IN INCLINOMETRY CALCULATION WITH MINIMUM-CURVATURE METHOD

Minimum-curvature method is one of the most common methods in inclinometry calculation and well track design. It is widely used in well track computation.Several details of computer numerical calculation with minimum-curvature method are studied in the paper. It gives out the azimuth definition of zero hole deviation angle of measuring point and formulates the ambiguity of azimuth.It also analyzes computation process of coordinates increment and gives out the algorithm of time calculation by decreasing trigonometric function.As to coordinates computation of small bend angle, the approximate formula of high precision is used instead of direct calculation which produces division overflow easily, which improves stability and computational accuracy of computation process.Gauss numerical methods of integration is used to calculate the horizontal projection length accurately.The method can be used in computer software development for well track calculation with minimum-curvature method to improve computational stability and accuracy of computer software.It is valuable for other practical problems involved in well track calculation such as target-hitting analysis predication of an oriented well, well path control and wellbore quality inspection, etc.