致密气油水共存条件下L360N管线钢的微生物腐蚀行为研究  

Microbiologically Influenced Corrosion Behavior of L360N Pipeline Steel with Coexistence of Condensate and Water for Tight Gas

作　　者：王彦然 孙洪亮 卫国锋 唐永帆[1] 郑荣军 莫林[1] 郑强[3] WANG Yanran;SUN Hongliang;WEI Guofeng;TANG Yongfan;ZHENG Rongjun;MO Lin;ZHENG Qiang(Research Institute of Natural Gas Technology,PetroChina Southwest Oil&Gasfield Company,Chengdu 610213,China;PetroChina Oil Gas and New Energy Company,Beijing 100007,China;Central Sichuan Oil&Gas District,PetroChina Southwest Oil&Gasfield Company,Sichuan Suining 629000,China)

机构地区：[1]中国石油西南油气田分公司天然气研究院,成都610213 [2]中国石油油气和新能源分公司,北京100007 [3]中国石油西南油气田分公司川中油气矿,四川遂宁629000

出　　处：《表面技术》2024年第12期135-146,共12页Surface Technology

基　　金：中国石油西南油气田分公司科研项目(20220305-12)。

摘　　要：目的通过实验模拟L360N管线钢在致密气油水共存条件下的微生物腐蚀(MIC)行为,探究凝析油对MIC行为的影响。方法模拟6组凝析油体积占比不同的腐蚀环境,结合失重测试和电化学实验分析了凝析油对腐蚀速率的影响规律。通过最大可能计数法(MPN法)计数试片表面的细菌固着量。采用激光显微镜、扫描电镜(SEM)、能谱仪(EDS)、光电子能谱仪(XPS)表征分析腐蚀形态和产物形貌、成分。结果凝析油溶于水中会直接影响微生物腐蚀行为。水中存在的凝析油可显著降低L360N管线钢的均匀腐蚀速率,但不同条件下浸泡的试片表面均有明显的点蚀。所有试片表面的细菌固着量都不低于10^(4)cells/cm^(2),且都有生物膜形成,主要化学成分是Fe_(2)O_(3)和FeS。另外,在高凝析油体积占比条件下,膜内的硫化物更倾向于局部沉积,使得生物膜结构更加不均匀。电化学测试表明,随着时间的延长,各条件下的电荷转移电阻(R_(ct))和腐蚀电流密度(J_(corr))都变化至相近水平,凝析油含量升高不能长期抑制膜下固着菌的代谢活性。结论L360N管线钢在不同凝析油体积占比的油水介质中均有MIC发生。其原因在于凝析油含量升高不能完全抑制生物膜的形成,还促使生物膜结构更加不均匀,为固着菌代谢提供了适宜的环境,有利于点蚀的发生。The microbiologically influenced corrosion(MIC)behavior of L360N pipeline steel was studied in simulated tight gas produced water mixed with condensate.The effect and mechanism of condensate on MIC behavior was explored by conducting experiments.Six groups of static immersion tests were carried out under different volume proportions of mixed condensate,and the condensate concentration dissolved in water was measured by gravimetric method.The MPN method was used to count sessile cells settled on coupon surface.The weight-loss and electrochemical measurements were applied to study the influence of condensate on the corrosion rate and mechanism of L360N pipeline steel.The laser microscope was used to analyze pit depth of coupons after removal of corrosion product.Investigation of the surface and cross-sectional morphology of corrosion product was conducted by SEM.EDS and XPS were used to analyze the composition of corrosion product.The MIC behavior was closely affected by the dissolution of condensate.And the condensate concentration in water increased as volume proportion of condensate rose.The general corrosion rates in the presence of condensate were much lower than those without it.But the occurrence of pitting corrosion was observed for all coupons under different conditions.It indicated that the presence of condensate had a limited inhibition effect on pitting corrosion.With the existence of dissolved condensate,there were still a large amount of sessile cells at above 10^(4)cells/cm^(2)for both SRB and FB.The SEM analysis showed that all coupons were covered with biofilms with the composition of Fe_(2)O_(3)and FeS.It suggested that the metabolic activity could not be completely prevented by the increase of condensate concentration,and the MIC was caused for all conditions.From EDS analysis,the significant difference in S mass fraction was found among different analysis regions for the same coupon.It indicated the increase of condensate concentration contributed to the formation of more heterogeneous biofilms

关 键 词：微生物腐蚀 致密气 凝析油 生物膜 点蚀 

分 类 号：TG174[金属学及工艺—金属表面处理]