CO_2凝析气田碳钢管道穿孔失效分析

Analysis on Perforation and Failure of Carbon Steel Pipes in CO2 Condensate Gas Field

某CO2凝析气田集输工艺采用气液混输,站场内管道采用碳钢+缓蚀剂方案。气田地面集输试运行后,产气量剧增,在碳钢管网中的部分流场突变区域发现了穿孔泄漏。通过对材料理化检验、腐蚀特征分析,并结合管输介质的流速和流态对碳钢管道的失效原因进行了综合分析,结果表明:流动加速腐蚀是碳钢管道壁厚减薄穿孔破坏的主要原因,流速、流态是影响流动加速腐蚀的重要因素。现场失效案例说明即使流速按APl 14E规定进行控制,仍不能完全确保管道不遭受流动加速腐蚀,在工程设计中还应考虑一些其他的措施和手段来降低流动腐蚀风险。

Adopted is the gas-liquid two phase transportation process in certain condensate gas field with CO2 and applied is the option of carbon steel plus corrosion inhibitor for in-station pipeline corrosion control.After its surface gathering and transportation system was test run,gas output increased rapidly and perforation and gas leakage occurred in some flow field mutation areas of the carbon steel pipeline network.Adopted is the material physical and chemical test method to check the quality of the pipeline material.Analyzed are corrosion morphologies of the pipeline material and corrosion products in its inner walls and identified are main corrosion behaviors.Compared are different flow velocities and flow regimes in pipelines with different diameters,comprehensively analyzed are different failure causes of carbon steel pipelines in combination with current international knowledge on corrosion behaviors and the analysis results show that flow-accelerated corrosion is main factor to induce the perforation leak of the pipe.Field service experience shows that carbon steel pipe may suffer flow-accelerated corrosion even though flow velocity is controlled according to APl 14E.Some measures shall be considered during design to mitigate such corrosion.