涪陵页岩气田三维水平井轨道优化设计方法探讨

3D Horizontal Wellbore Trajectory Optimization Design Method in the Fuling Shale Gas Field

为了降低涪陵页岩气田三维水平井的施工难度,保障三维水平井安全高效钻进,提出了三维水平井轨道为"直井段—增斜段—稳斜段—稳斜扭方位段—稳斜段—增斜段—水平段"七段式的优化设计方法。首先根据井眼轨道的水平投影和垂直剖面建立轨道设计模型,再预设稳斜角和造斜方位角求解轨道设计模型,最后以轨道总长度最短为目标优选轨道。该方法将常规三维五段式轨道中增斜扭方位的第二个圆弧井段分为稳斜扭方位井段与铅垂面上的增斜井段进行设计,即先扭方位对准靶点方位再增斜中靶,以避免在极为关键的中靶阶段同时进行增斜与扭方位作业,降低中靶难度。采用该方法对已完钻井焦页14-3HF井重新进行轨道设计,并将设计结果与原设计轨道及实钻轨迹进行了对比,发现新设计的轨道与实钻轨迹更贴近,该井实钻时为降低施工难度就是先扭方位对准靶点方位再增斜中靶的,这表明该三维水平井轨道优化设计方法更适用于涪陵页岩气田三维水平井的轨道设计与现场施工。

In order to reduce operation difficulties in horizontal wells utilizing 3 Dwellbore trajectories and ensure safe and efficient drilling operation in the Fuling Shale Gas Field,the team proposed an optimized design method that divides the 3 Dwellbore trajectory into 7 sections,i.e.,＂vertical section— buildup section—inclination holding section—inclination holding and correction run section—inclination holding section—build-up section—horizontal section＂.In this method,the first step involved establishing the trajectory design model according to horizontal projection and vertical profile of a wellbore trajectory,and later steps involved presetting the inclination holding angle and the angle-building azimuth to solve the trajectory design model.Finally,the target trajectory was optimized based on the target of least overall trajectory length.The second circular arc section of the build-up and correction run section in the conventional 3 D five-section trajectory design was subdivided into inclination holding and correction run section and the build-up section on the vertical plane.To reduce difficulties in hitting the target,a conduct correction was run against the target azimuth which helped avoid simultaneous build-up and correction run operations in the extremely critical target hitting phase,.This method was applied in the wellbore trajectory design of previously drilled Well Jiaoye 14-3 HF.The newly designed trajectory was compared with the originally designed trajectory and it was found that the newly designed trajectory is in closer proximity to the actual one,and the well was actually drilled with the method of firstly conducting correction run against the target and then building up the angle to hit the target in order to reduce the operation difficulties,which indicates that the 3 Dhorizontal wellbore trajectory optimization design method is more suitable for the design and on-site operation of 3 Dhorizontal wells drilling in the Fuling Shale Gas Field.