海洋石油海底管道面临的内腐蚀风险及对策

Internal Corrosion Risk and Solution of Offshore Oilfield Pipeline

内腐蚀是海上油气田海底管道面临的最重要的失效因素之一。为了研究海底管道各种内腐蚀的腐蚀机理、检测技术及预防手段,分析了CO2/H2S腐蚀、垢下腐蚀、微生物腐蚀的腐蚀机理、检测方法及应对措施,最终根据实验得出,对于CO2/H2S腐蚀,当CO2分压0.1MPa时,随着H2S浓度的增加,在25ppm处存在拐点,腐蚀速率最低,而大于5000ppm后腐蚀速率快速上升,可运用腐蚀挂片和探针进行检测,其预防措施为加入缓蚀剂并配合清管;对于海底管道的垢下腐蚀,通常为酸性腐蚀,检测方法为在海底管道两端安装旁路式内腐蚀检测系统,其预防措施为加入缓蚀剂、防垢剂、杀菌剂并配合清管作业;在海底管道中硫酸盐还原菌可能造成强烈的腐蚀,当海底管道介质中存在CO2气体时,CO2分压增加对硫酸盐还原菌的繁殖起到抑制作用,其检测方法为微生物测试法、海底管道进出口端H2S含量比较法,内腐蚀旁路检测系统。最终得出结论海底管道的主要腐蚀因素、各个因素之间的关系、内腐蚀的控制策略及建立海底管道内腐蚀RBI分析方法。

Internal corrosion is one of the most important factors resulting to pipeline failure. In order to research the corrosion mechanism and inspection method and prevent measures,analysis corrosion mechanism and inspection method of CO2 and H2 Sand under-deposited acid corrosion and microbial corrosion. Finally, according to the experiment, when CO2 partial pressure 0.1 MPa, with the increase of H2S, there is an inflection point at 25 ppm, at which the corrosion rate is the lowest, if the concentration of H2S more than 5000 ppm, the corrosion rate increase rapidly. the corroded hanging piece and probe can be used to test corrosion rate,corrosion inhibitor and pigging is used to prevent corrosion. The corrosion of offshore pipelines is usually acid corrosion, the inspection method is to install a bypass internal corrosion detection system at both ends of the offshore pipeline. The preventive measures include adding inhibitors, anticrustator, bactericide and pigging operations. Sulfate reducing bacteria may cause strong corrosion in offshore pipeline, when CO2 exists in the medium of the offshore pipeline, the increase of CO2 partial pressure can inhibit the reproduction of the sulfate reducing bacteria. The detection method is the microbiological test method, the H2S content comparison method at the inlet and outlet and the internal corrosion by-pass detection system. Finally the main corrosion factors of the offshore pipeline,and the relationship between the various factors,and the controlstrategy of internal corrosion,and the RBI analysis method for the corrosion of the offshore pipeline are established.