煤层水力自旋转射流钻头设计

DESIGN ON HYDRAULIC SELF-REVOLVING JET BITS FOR CBM DRILLING

高压旋转水射流技术在钻大井径、长连续孔方面具有明显优势,在煤层中钻井又具有高效、节能、钻孔大、成孔规则、破岩效率高等优点,因此在煤层气地面径向水平井技术和井下采空区钻长直井技术中广为应用。主要从理论上分析了旋转射流和射流旋转各自的流动规律、破岩过程及破岩机理,并在此基础上分析了旋转射流钻头各设计参数的取值范围,结合已有的经验值,优化设计了可控外壳旋转内导叶轮、可控中心轴旋转内导叶轮、偏置可控外壳自旋转、偏置可控中心轴自旋转等4种水力旋转式钻扩孔射流钻头。这些钻头适用于在煤层中钻孔及安全排放瓦斯气体。

High pressure revolving water jet technology has an obvious advantage in drilling large hole diameter and long continuous holes and is also characterized by high efficiency,energy saving,large and regular borehole,high rock-breaking efficiency when drilling coal seams.As a result,it is widely applied to drilling radial horizontal wells on ground and long straight holes in exhausted area for CBM development.So,this article,mainly based on the theories,analyzes the flowing rules of revolving jet and jet rotation,its rock-breaking process and mechanism individually.It also analyzes the range of each design parameter value of revolving jet bit on the base of mentioned above and designs the following four hydraulic self-revolving jet bits for expanding drilling optimistically which are suitable for coal drilling and safe gas discharge:controllable shell revolving inner guide impeller,controllable central axis revolving inner guide impeller,biased controllable shell self-revolving bit,and biased controllable central axis self-revolving jet etc.