渤海某油田储层埋藏深,温度高达183℃,井底压力48.6MPa,天然气组分中含较高浓度CO2和少量H2S,生产过程中偶发油管腐蚀现象,造成油套环空带压.以A1井油管腐蚀为例,通过开展腐蚀形貌分析、腐蚀产物化验及腐蚀模拟实验,分析管材腐蚀主要诱因,并开展环空保护液性能评价实验,优化防腐策略.研究结果表明:CO2分压、温度是腐蚀主控因素,同时发现氯离子浓度高会加剧超级13Cr材质腐蚀速度;生产工况下淡水基环空保护液防腐性能优于海水基环空保护液,未发生明显点蚀;该井按照新防腐策略成功在现场完成工程应用,生产至今管柱未发现明显腐蚀,油套环空压力正常,生产平稳.
In Bozhong oilfield,the reservoir is buried deep,the temperature is 183℃,the bottom hole pressure is 48.6MPa,and the natural gas components contain relatively high concentration of CO2 and a small amount of H2S,which causes occasional tubing corrosion during production,resulting in oil sleeve annulus pressure.Taking the corrosion of tubing in well A1 as an example,this paper analyzes the main causes of pipe corrosion by carrying out corrosion morphology analysis,corrosion product testing and corrosion simulation experiment,and carries out the performance evaluation experiment of annular protective fluid to optimize the anti-corrosion strategy.The results show that the partial pressure of CO2 and temperature are the main factors of corrosion,and the high concentration of chloride ions will accelerate the corrosion rate of S13Cr material.The fresh-based annular protection solution has the best anti-corrosion performance,and no obvious pitting corrosion occurs,and the formate annular protection solution pitting corrosion is the most serious.The well has been successfully applied in the field according to the anti-corrosion strategy,and no obvious corrosion has been found in the string so far,and the annulus pressure in the oilfield is normal and the production is stable.