海洋油气柔性软管环空状态检测研究及应用

海洋油气柔性软管的环空状态检测是管道实现完整性管理的重要前提和基础。针对海洋油气柔性软管典型结构,开展了环空气体、液体和腐蚀剥离物采样、环空体积检测、外保护层泄漏检测等检测系统的主要设备及工作流程研究,并在中国南海某油田在役柔性软管现场进行了初步测试。通过环空浸没及剩余体积测试、注氮-保压-泄压全过程压力监测、气态样本组分分析、液态样本离子浓度及pH测定、固态沉积物扫描电镜和能谱仪多点测试、微区拉曼光谱测试等多种方法,评估了软管外保护层的完整性以及环空金属的腐蚀程度。结果表明,软管环空的液体可能来自于外保护层渗入的海水,液体浸没率较高且酸性较强,对环空金属的腐蚀风险较大。本文研究为海上油气柔性软管的安全保障提供了技术支撑。

Research and application of annulus state detection of offshore oil and gas flexible pipeline

The annulus state detection of offshore oil and gas flexible pipelines is an important prerequisite and basis for the integrity management of pipelines.According to the typical structure of offshore oil and gas flexible pipelines,the main equipment and work flow studies of the detection system such as sampling of annulus gas,liquid and corrosion stripping material,detection of annulus volume,and leakage detection of outer protective sheath have been implemented,and preliminary tests have been carried out on the flexible pipelines in service in the South China Sea.Through annulus immersion and residual volume test,pressure monitoring throughout the nitrogen injection-pressure holding-pressure relief,the analysis of gaseous sample composition,the determination of ion concentration and pH value of liquid sample,the SEM(scanning electron microscope)and EDS(energy dispersive spectrometer)multi-point test of solid sediment,the micro area Raman spectrum test,etc.,the integrity of the outer protective sheath and the degree of corrosion of the metal in the annulus were assessed.The results show that the liquid in the annulus of the flexible riser may come from the seawater infiltrated by the outer protective sheath,and the liquid immersion rate is high and the acidity is strong,posing high corrosion risk to the metal in the annulus.The research in this paper provides technical supports for the safety assurance of offshore oil and gas flexible pipelines.