深层煤岩气地面集输系统的腐蚀因素及防腐措施研究

    Research on Corrosion Factors and Anti-corrosion Measures of Surface Gathering and Transportation System for Deep Coalbed Methane

    • 摘要: 针对深层煤岩气地面集输管线内壁的腐蚀问题,系统分析了腐蚀产物的组成及其分布规律,探讨了腐蚀驱动机制及影响因素,并评估了缓蚀剂的应用效果。结果表明,L245N管线内壁腐蚀产物主要由氧化铁和碳酸钙组成,其中碳酸钙含量由外向内递减,而氧化铁含量则呈递增趋势。腐蚀过程主要由铁的氧化反应驱动,采出水中的高钙离子浓度是导致碳酸钙结垢的主要原因。环境因素如温度升高、Cl-浓度增加、溶解氧的存在以及Fe3+/Fe2+氧化还原循环均会加速腐蚀速率。在无氧条件下,羟基乙叉二膦酸(HEDP)缓蚀剂表现出优异的缓蚀性能,但在富氧环境中缓蚀效率下降。304不锈钢在富氧环境中展现出较好的耐蚀性和稳定性。HEDP缓蚀剂通过形成保护膜阻碍铁的溶解,其作用机制主要为阳极抑制,显著提高了材料的电化学稳定性。HEDP分子在Fe(110)表面的吸附能为负值,且吸附能绝对值随温度升高显著降低。

       

      Abstract: Aiming at the inner wall corrosion of ground gathering pipelines for deep coalbed methane, the composition and distribution of corrosion products were systematically analyzed, the driving mechanism and influencing factors of corrosion were discussed, and the application effects of corrosion inhibitors were evaluated. The results show that the corrosion products on the inner wall of the L245N pipeline are mainly composed of iron oxide and calcium carbonate, and the content of calcium carbonate decreases from outside to inside, while the content of iron oxide increases. The corrosion process is mainly driven by the oxidation reaction of iron, and the high calcium ion concentration in the produced water is the main cause of calcium carbonate scaling. Environmental factors such as increased temperature, increased Cl- concentration, the presence of dissolved oxygen, and the Fe3+/Fe2+redox cycle all accelerate the corrosion rate. Hydroxyethylidene diphosphonic acid(HEDP) exhibits excellent corrosion inhibition in oxygen-free environment, but its efficiency decreases in oxygen-rich environment. 304 stainless steel shows good corrosion resistance and stability in an oxygen-rich environment. HEDP inhibits the dissolution of iron by forming a protective film, and its mechanism is mainly anode inhibition, which significantly improves the electrochemical stability of the material. The adsorption energy of HEDP on the surface of Fe(110) is negative, and the absolute adsorption energy decreases significantly with the increase of the temperature.

       

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