海洋15000 m双井口井架设计及结构分析

Design and Structure Analysis of the 15 000 m Dual Derrick for Offshore Drilling

钻机井架的结构设计分析将直接影响钻机的使用寿命,现有的分析计算仅限于K形井架和单井口塔形井架的主体结构,而井架上的天车、二层台及一些附加设备对井架的静强度有较大的影响。鉴于此,建立了完整的双井口井架模型,包括天车和二层台等结构,并且把被简化的排管机等设备以质量点的形式添加到模型相应的位置,分析井架的静强度,使得计算结果更准确,更贴合实际。采用专业有限元分析软件SAFI对井架的正常作业工况、自存工况和拖航工况进行了分析优化,使其达到质量最轻、结构最优,并能满足强度和刚度要求。同时,为了分析井架的动力学特性,对其进行了模态分析,得出井架的1阶振型位于顶驱的振动频率范围内,容易产生共振;井架前后片架和天车滑轮起重架刚度较弱,在井架共振时结构不稳定。研究结果对于超深井双井口井架的现场应用和进一步优化具有一定的参考作用。

The structural design analysis of the drilling rig derrick will directly affect the service life of the rig.The current analytical calculations are mostly focused on the main structure of the K-shaped derrick and the single wellhead tower derrick,while the crane,the monkey board and some additional equipment on the derrick has a great influence on the static strength of the derrick. In view of this,a 15 000 m dual derrick for semi-submersible drilling platforms has been developed,which can meet the requirements of dual wellhead operations. The derrick consists of two combined tower-shaped derricks with dual drilling systems that could significantly reduce drilling time. Both of the two derricks meet the maximum static hook load of 12 700 k N and designed environmental load requirements. The finite element analysis software SAFI was used to analyze and optimize the derrick under normal working condition,self-storage condition and towed working conditions,so as to attain the lightest weight and the optimal structure,and meet the strength and stiffness requirements. To analyze the dynamic characteristics of the derrick,the modal analysis is carried out. The first-order vibration mode of the derrick is in the vibration frequency range of the top drive,which is easy to generate resonance. The rigidity of the front and rear frame of the derrick and the crane pulley frame is weak,which lead to an unstable structure when the derrick resonates. The research fills the gap in the research and development of the domestic dual derrick for ultra-deep wells.