海洋柔性管气体渗透机理及其防护措施的研究进展

Latest research progress in gas permeation behavior of subsea flexible pipes and its prevention measures

柔性管在海洋油气领域发挥着重要的作用。高分子材料由于自身的分子结构特点而具有气体渗透的特性,因此柔性管内部输送的气体有可能渗透进入环空,环空中渗透气体的大量聚集有可能通过力学和腐蚀作用而影响环空内部各层的性能,进而引起管道失效。为此,介绍了国外关于气体渗透行为在渗透机理、影响气体渗透测试结果的因素、使用计算模型对环空环境预测以及气体渗透防护措施等方面的最新研究进展。国外学者的研究结果表明:①柔性管的气体渗透行为符合聚合物的气体渗透机理;②使用小型测试仪器测定气体在柔性管内压密封层材料内的渗透数据时,应当在与实际工况相同的条件下进行试验;③基于小型测试获得的渗透数据,采用渗透模型预测柔性管的环空环境是可行的;④大型和现场测试结果显示,模型预测的环空环境同实测值有着很好的一致性。目前国内海洋柔性管的设计和制造尚处于起步阶段,上述研究成果和认识对于保障我国海洋柔性管的可靠性具有重要意义。

Flexible pipes are widely used in offshore oil/gas fields. However, the polymer materials used in these pipes are gas-per- meable due to its molecular characters, gases in the pipes can permeate into and accumulate in the annulus. Such accumulated gases may degrade the performance of layers in the annulus by way of mechanics and corrosion, and finally cause failures of flexible pipes. The latest researches overseas were reviewed on the mechanism of gas permeation in flexible pipes, factors influencing the results of permeation test, model prediction of annulus conditions, and preventive measures against gas permeation. Foreign research results show that firstly, the behavior of gas permeation through flexible pipes is in accordance with the mechanism of gas permeation through polymers. Secondly, the small-scale test of gas permeation should always be conducted under the same conditions as actual operations in order to get permeation data of internal pressure sheath polymer. Thirdly, it is practicable to predict the annulus condi tions of flexible pipes by using the permeation model based on data obtained from small-scale tests. Fourthly, large-scale permeation experiments and field measurements prove that the predicted annulus conditions are in good agreement with the measurements. In China, the design and manufacture of flexible pipes used in offshore oil/gas fields have just begun in recent years. The above research results will be of great significance in ensuring the reliability of flexible pipes in China.