多因素协同作用下的页岩气井下管道腐蚀分析

Corrosion Analysis of Shale Gas Downhole Pipes Under Synergistic Action of Multiple Factors

国内西南地区某页岩气井下管道出现了不同程度的腐蚀,存在较大的安全隐患。为明确腐蚀类型和机理,开展了井下管道腐蚀分析。研究方法主要包括宏观观察、微观观察和成分分析、流体力学仿真。结果表明:冲刷-CO_(2)-SRB(硫酸盐还原菌)多因素协同作用下的腐蚀是页岩气井下管道的主要腐蚀类型。运行初期SRB的生长与富集造成了局部腐蚀,加入杀菌剂后SRB腐蚀停止,CO_(2)腐蚀在已经形成的局部腐蚀位置继续发展,液带砂和气带砂等流体冲刷作用促进了相关腐蚀的发生、发展。

The downhole pipes of a shale gas in southwestern China experience varying degrees of corrosion,posing significant safety hazards.To clarify the types and mechanisms of corrosion,downhole pipes corrosion analysis research was conducted.The research methods mainly included macro observation,micro observation and composition analysis,fluid dynamics simulation.The results indicate that corrosion under the multi factor synergistic effect of erosion-CO_(2)-SRB(sulfate-reducing bacteria)is the main type of corrosion for pipelines under shale gas wells.The growth and enrichment of SRB in the early stage of operation cause local corrosion.After adding fungicides,SRB corrosion stops,and CO_(2)corrosion continues to develop in the already formed local corrosion location.The flushing effect of fluids such as liquid sand and gas sand promotes the occurrence and development of related corrosion.