极地钻井关键设备橡胶密封材料的优选

The Optimization of Rubber Sealing Materials for Key Equipment in Polar Drilling

  • 摘要: 极地的低温环境会使橡胶逐渐变硬甚至玻璃化从而丧失原有的弹性,易导致钻井泵、防喷器等关键钻井设备出现密封失效问题,影响正常生产并带来安全隐患。因此,需要对极地钻井关键设备所用橡胶密封材料进行优选。按照国家标准GB/T 528—2009和GB/T 7759.2—2014,在20~–50 ℃温度环境下对橡胶材料进行了单轴拉伸和压缩永久变形试验,将试验数据与多种常见超弹性本构模型进行拟合得到了模型参数,分析了这些本构模型在低温条件下的适用性;利用有限元分析软件ABAQUS,模拟分析了–45 ℃温度下处于工作状态的O形橡胶密封圈的密封性能,找出了设备在低温条件下容易发生密封失效的位置。分析认为,在低温、小变形条件下,Polynomial(N=2)模型和Ogden(N=3)模型能更准确地描述橡胶的力学性能;硅橡胶、气相胶、丁腈橡胶在极地环境(–45 ℃)下依然保持优越的密封性能,可以作为极地钻井关键设备用橡胶密封材料。低温下超弹性本构模型的分析和橡胶密封材料的优选,可为我国后续极地钻井提供理论指导与支持。

     

    Abstract: The unique low temperature environment of polar drilling hardens rubber gradually to the point of even vitrifying it so it loses its original elasticity. This can easily cause the sealing failure of key drilling equipment, such as mud pump and BOP, which affects normal production and brings about potential safety risks. Therefore, it is necessary to optimize the rubber sealing materials used in the key equipment for polar drilling. According to the National Standards GB/T 528—2009 and GB/T 7759.2—2014, the rubber materials were subjected to uniaxial tension and compression permanent deformation tests at the temperature of 20~–50 °C, and the test data and the hyper-elastic constitutive models of several common rubbers were fitted to obtain the model parameters, so as to analyze the applicability of these constitutive models under low temperature conditions. The sealing performance of rubber O-ring at –45 °C was simulated and analyzed by using ABAQUS finite element software, and found the location of the seal failure which is easy to occur at low temperature. According to the analysis, Polynomial (N=2) model and Ogden (N=3) model can accurately describe the mechanical properties of rubber under low temperature and small deformation conditions. Silicone rubber, gas rubber and nitrile rubber can still maintain superior sealing performance under polar environments (–45 °C), so they can be used as the rubber sealing materials for key equipment of polar drilling. The analysis of rubber super-elastic constitutive model at low temperature and the optimization of rubber sealing materials can provide theoretical guidance and support for the future polar drilling of China.

     

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