针对井眼轨迹的不确定性问题提出了误差椭球姿态表征、截面误差椭圆解算、误差椭圆柱构建等方法,并进行实例计算。根据井斜角、方位角和工具面角定义,提出了井眼轨迹误差椭球姿态的表征方法;通过空间任意平面截取误差椭球,建立了截面误差椭圆的通用概念及算法,以分析井眼轨迹在水平面、铅垂面、法平面等任意平面上的误差;基于曲面相切和曲线投影理论,提出了井眼轨迹误差椭圆柱的构建方法,可评价井眼轨迹的轴向包络误差及其沿井深的变化情况。研究表明,井越深井眼轨迹误差越大;在使用常规随钻测量的深井超深井中,井眼轨迹位置误差可达数十米。提供了成套的井眼轨迹误差分析方法,用于评价井眼轨迹的监测精度及可靠性。图3表3参14
To solve the problem of borehole trajectory uncertainty, some methods such as error ellipsoid posture characterization, sectional error ellipse solution and error elliptic cylinder construction were proposed and an application example was given. According to the definition of inclination, azimuth and tool-face angle, a characterization method of error ellipsoid posture of borehole trajectory was presented. By intercepting the error ellipsoid with an arbitrary plane in space, the general concept and algorithm of sectional error ellipse were established to analyze the borehole trajectory errors in horizontal plane, plumb plane, normal plane, etc. Based on the theory of surface tangency and curve projection, a construction method of error elliptic cylinder of borehole trajectory was put forward to evaluate the axial enveloping error of borehole trajectory and its variation along well depth. The research shows that the deeper the well, the greater the borehole trajectory error will be. In deep and ultra-deep wells measured using conventional measurement while drilling (MWD), the borehole trajectory position error reaches tens of meters. The research results provide a complete set of analysis methods for borehole trajectory error, which can evaluate the accuracy and reliability of borehole trajectory monitoring.
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