昭通区块页岩气工艺气管线腐蚀与防治

Corrosion and prevention of shale gas process pipeline in Zhaotong block

关键词:  页岩气  集输平台  CO₂  管材  腐蚀 

Key words:  shale gas  gathering and transportation platform  carbon dioxide  pipeline  corrosion

摘要:

目的 针对昭通页岩气区块集输平台管材腐蚀严重现象,开展页岩气工艺气管线腐蚀与防治研究。方法 通过分析弯头腐蚀情况,确定腐蚀产物主要为FeCO₃和FeO,并考查了CO₂含量、CO₂分压、侵蚀性CO₂、溶解氧、流速、出砂、细菌等因素对腐蚀的促进作用。结果 发现溶解氧促进的CO₂腐蚀是管材腐蚀的主要因素,流体总CO₂含量越高,分压越大,腐蚀越严重,流速和含砂对管材腐蚀同样存在促进作用,而细菌对腐蚀无明显促进作用。结论 同时筛选出了咪唑啉和曼尼希碱两类具有明显提高缓蚀性能的缓蚀剂,现场应用证明咪唑啉类缓蚀剂具有较好的缓蚀性能,缓蚀率达95%。 

Abstract:

Objective In view of serious pipe corrosion of gathering and transportation platform in southwest Zhaotong shale gas block, the study of corrosion and prevention of shale gas pipeline was carried out. Methods By analyzing the corrosion of the elbow, it was determined that the corrosion products mainly were iron carbonate and iron oxide. The promoting effects of carbon dioxide content, carbon dioxide partial pressure, erosive carbon dioxide, dissolved oxygen, flow rate, sand production and bacteria on the corrosion are investigated. Results It is found that carbon dioxide corrosion promoted by dissolved oxygen is the main factor of pipe corrosion. The higher total carbon dioxide content of the fluid and the higher the partial pressure are, the more serious the corrosion is. The flow rate and sand content of the fluid have a greater promoting effect on the corrosion, while bacteria and chloride ions have no obvious promoting effect on the corrosion. Conclusion sAt the same time, two kinds of inhibitor of imidazoline and Mannich base were selected to improve the corrosion inhibition performance. The field application showed that imidazoline inhibitors had good corrosion-inhibition performance, and the rate of corrosion-inhibition could be as high as 95%.