煤层气欠平衡钻井旋转控制头壳体密封环应力分析

Analysis on Shell Sealing Ring Stress of Rotating Control Head in Coal Bed Methane Underbalance Drilling

煤层气欠平衡钻井旋转控制头壳体密封环在现场使用容易发生破坏。对旋转控制头聚四氟乙烯密封环密封性能进行有限元仿真分析,探讨密封环体应力分布规律、密封面的接触应力变化规律以及他们与压缩量的关系。结果表明:聚四氟乙烯锥角密封环的2个密封面主要接触区域接触应力分布均匀且大小基本相等,适用于旋转控制头壳体密封;但密封环体应力分布不均,锥面拐角处(两侧)存在严重压应力集中,可能导致密封环两侧产生压塑性变形而破坏失效。分析结论得到工程使用的验证,论证了分析的可靠性与实用性。

The shell sealing ring of the rotating control head（RCH） in coal bed methane（CBM） underbalance drilling is frequently damaged when used on the spot. The sealing properties of polytetrafluoroethylene （PTFE） sealing ring of RCH shell was analyzed by finite element method. The distribution rules of sealing ring stress, the variation of contact stress, and the relationship between them and the amount of compression were investigated. The results indicate that the distribution of contact stress is even and almost the same among the two main contact area of sealing of PTFE conical sealing rings, which is suitable to be used for shell sealing of RCH. However, the distribution of stress of sealing ring is uneven, and it may lead to plastic deformation and failure on both sides of the sealing ring for the compressive stress concentrated on the comer of the sealing ring cone （both sides）. The analysis results achieve the same result as in practical engineering, and it proves the analysis is reliable and practical.