浅析某新建高含硫湿天然气采气管线的内防腐措施

Analysis of Internal Corrosion Protection Measures for a Newly Built High-sour Wet Natural Gas Pipeline

分析了湿天然气采气管线的内防腐的现状、危害程度、主要影响因素,并结合某高H_2S、CO_2、Cl^-、高产、高温、高压气田湿酸性天然气采气管线的工程实例,阐述了在酸性环境中为避免管线因硫化物而引起应力开裂时如何选取合适的管材并辅助合适的电化学腐蚀控制措施,以及流速控制加注缓蚀剂、加强管道的腐蚀监测和定点壁厚检测等内腐蚀控制措施,最后得出对于存在H_2S-CO_2-Cl^-腐蚀环境的新建采气管线采用缓蚀剂+碳钢的综合防腐措施效果最好,不仅可以保证管道使用寿命,腐蚀速率也由原来的≤0.06mm/a降低到≤0.045mm/a。

The present situation, the damage degree and the main influencing factors of internal corrosion protection of wet natural gas pipeline are analyzed. Taking the sour natural wet gas pipeline in a high H2S, CO2 and CI content, high-production, high-temperature and high-pressure gasfield as an example, it is expounded how to select the material of the pipeline and the suitable electrochemical corrosion control measures in order to avoid the stress cracking caused by sulfideof the pipeline, and how to select the internal corrosion control measures such as controlling the flow speed of natural gas, adding corrosion inhibitor, strengthening the corrosion monitoring and wall thickness detection of the pipeline, etc. Finally it is held that, for the natural gas pipeline newly constructed in the corrosion environment with H2S, CO2 and CI-, the corrosion prevention measures of ＂corrosion inhibitor ＋ carbon steel＂ is of the best anti-corrosion effect, it not only can guarantee the service life of the pipeline, but also reduce corrosion rate from original less than or equal 0.060 mm/a（ to less than or equal to 0.045 mm/a.