扩眼器在定向造斜段的应用可行性研究

Research on reamer's applicability in directional kick off intervals

随钻扩眼器可有效扩大下部井眼直径,对于优化井身结构、提高完井质量、提高钻进效率、降低后续作业风险具有重要意义。随钻扩眼时该工具相当于一个满眼扶正器,在直井段工作时扩眼器具有防斜作用,但在定向段随钻扩眼时该工具将改变常规造斜钻具的造斜特性,因此该工具在定向造斜段应用的可行性需要研究。以一套常用造斜钻具为例,计算了其初始造斜率以及直接扩眼工况和随钻扩眼工况的造斜率,发现使用扩眼器后对原有钻具组合的造斜特性影响很大。为达到原有造斜要求,通过单独和组合调整BHA参数(主要有螺杆钻具弯角、上稳定器外径、上稳定器距离钻头距离等)获得与原有BHA造斜特性基本相当的多种方案,这说明扩眼器可在既定的造斜要求下完成定向随钻扩眼钻进施工。

Reaming while drilling can enlarge diameter of lower borehole effectively, and it is very significant for optimizing wellbore configuration, improving drilling efficiency and completion quality, and decreasing subsequent operating risks. While drilling in straight hole, it could be regarded as a packing centralizer and it could prevent from slanting, however, reaming while drilling in oriented section would alternate the angle buildup of common buildup assembly, so further research on its applicability in oriented section was needed. Taking a suit of common buildup assembly as an example, initial buildup rate and buildup rate of direct reaming and reaming while drilling were calculated, and found it influence the buildup rate of original downhole assembly a lot. To obtain good angle buildup effects, BHA parameters（bend angle of helicoid hydraulic motor, outside diameter of upper centralizer, the distance between upper centralizer and drill bit, and so on） was adjusted, and it meant that reaming while drilling could be implemented in accordance with the established requirements.