二氧化碳驱注采井常用油套管钢的腐蚀行为

摘要

采用高温高压反应釜研究了N80、P110、3Cr、5Cr等4种油套管钢材在现场采出液中的抗CO2腐蚀性能,结合扫描电镜(SEM)、能谱仪(EDS)和X射线衍射(XRD)等手段,观察分析了腐蚀产物膜形貌和成分.结果表明:随着温度的上升,4种钢材腐蚀速率均呈现出先增大后减小的趋势,最大值出现在中温区,N80、P110、5Cr钢在90℃时腐蚀速率达到最大,3Cr钢在80℃时腐蚀速率最大;4种钢材腐蚀类型主要为均匀腐蚀,未发现局部腐蚀,腐蚀产物主要为FeCO3,含Cr钢腐蚀产物出现多层结构,主要成分除了FeCO3,还有非晶态的腐蚀产物Cr(OH)3;N80、P110钢的腐蚀产物细小、致密、均匀覆盖在基体表面,腐蚀速率较低;3Cr、5Cr钢的腐蚀产物覆盖不均匀、与基体结合力弱、附着性不强,易脱落,造成整体腐蚀速率较高.%The CO2 corrosion resistance properties of four kinds of tubing materials N80,P110,3Cr and 5Cr in fluid were studied using an autoclave.The morphology and components of corrosion products were studied by SEM,EDS and XPS.The results showed that the corrosion rates of those four kinds of materials increased first and then decreased as temperature increased,and the peak values of the corrosion rates all occurred in medium temperature zone.For N80,P110 and 5Cr,the peak value of the corrosion rates occurred at 90 ℃.The most serious corrosion happened at 80 ℃ for 3Cr.The corrosion type of the materials was uniform corrosion,and localized corrosion was not found.The major component of corrosion products was FeCO3.The components of corrosion products with multilayer structure on 3Cr and 5Cr were FeCO3 and amorphous compound Cr(OH)3.The films of corrosion products of N80 and P110 were fine,compact and uiform on the surface,so the corrosion rates were low.The films of corrosion products on 3Cr and 5Cr were uneven and easy to drop,so the corrosion rates were relatively high.