页岩气地面集输系统微生物腐蚀影响因素分析

Analysis of Factors Influencing Microbiological Corrosion in Shale Gas Surface Gather⁃ing and Transportation System

页岩气井压裂过程中因未能对压裂液进行充分杀菌,压裂液中带入大量SRB、TGB和IB等微生物,造成地面集输系统微生物腐蚀穿孔。我国对页岩气微生物腐蚀影响因素研究起步较晚,相关研究和报道较少,限制了腐蚀防治技术的发展。为此,选择了页岩气田常用的L360N材料在环路腐蚀模拟实验装置中进行实验,利用激光共聚显微镜观察点蚀深度,计算腐蚀速率,分析各因素对腐蚀的影响情况。实验结果表明:集输系统微生物腐蚀主要影响因素是微生物浓度和温度,腐蚀速率随微生物浓度的增加而增加,最高点蚀速率的温度在30℃左右;固相颗粒含量在直管段中对点蚀速率基本无影响,但在弯头内壁外侧有冲蚀作用,可加剧点蚀;添加减阻剂可促进微生物腐蚀,杀菌后腐蚀速率显著降低。

During the fracturing process of shale gas well,a large number of microorganisms such as SRB,TGB,and IB are brought into the fracturing fluid due to insufficient sterilization of the fracturing fluid,which results in microbial corrosion and perforation in the surface gathering system.At present,the research on Influencing factors of microbiological corrosion of shale gas in China has just started,and there are few related researches and reports,which limits the development of corrosion control technology.Therefore,L360N material commonly used in the shale gas field is selected for experiments in the loop corrosion simulation experimental device.The laser co-focal scanning microscope is used to observe the pitting depth,calculate the corrosion rate and analyze the influence of various factors.The results show that the main influencing factors of microbiological corrosion are the microbial concentration and temperature.The corrosion rate increases with the increase of microbial concentration,and the temperature of the highest pitting rate is about 30℃.The content of solid particles has no effect on the pitting rate in the straight pipe,but it has an erosion effect on the outside of the elbow inner wall,which intensifies the pitting.The addition of drag reducers can promote microbial corrosion,and the corrosion rate can decrease significantly after sterilization.