修正轨道设计的自然曲线法

NATURAL CURVE METHOD FOR CORRECTING WELL PATH DESIGN

修正轨道设计一直是井眼轨道监控技术中的研究热点。以往的修正轨道设计方法多采用空间圆弧法和圆柱螺线法 ,它们都是采用两段式剖面。空间圆弧法是在第一个井段上同时完成对井斜和方位的调整 ,然后稳斜稳方位钻进 ;而圆柱螺线法则是在两个井段上分别调整井斜角和方位角。文章提出的自然曲线法可以在每个井段上都存在方位的变化 ,从而解决了造斜段伴随方位变化的轨道设计和考虑方位漂移的轨道设计问题。当某个井段上没有方位变化时 ,计算模型会得到简化 ,并由此验证了圆柱螺线法只是自然曲线法的一个特例。文中给出了上述 3种典型情况下的修正轨道设计方法和设计实例。

The well path correction design is always a research hotspot in the well trajectory monitoring and control. As the traditional methods, the spatial arc method (minimum curvature method) and cylinder helix method (radius of curvature method) are commonly used for well path correction. Both of them consist of two well sections. According to the spatial arc method, the inclination and azimuth are simultaneously rectified on the first section, and then the drilling goes on with stable inclination and azimuth: but according to the cylinder helix method, the inclination and azimuth are corrected respectively on the two sections. The natural curve method presented in this paper gives a model of path correction with the azimuth changing on every section. Accordingly, the problems on the design of deflecting interval path with the azimuth change and the bit walk on each section are solved. This model can be simplified if there is no azimuth change on any section. It is proved that the cylinder helix method is a special case of the natural curve method. The design methods and examples for those above 3 typical cases are provided in this paper.