一种新型含Al低Cr合金钢在模拟油田采出液环境下的CO2腐蚀行为

以自行设计开发的新型3Cr2Al低合金钢为研究对象，采用高温高压磁力驱动反应釜进行饱和CO₂模拟油田采出液环境下的腐蚀模拟实验，通过失重法获取腐蚀速率评价其耐蚀性能，并结合扫描电子显微镜、能谱分析、电化学测试等表征手段，研究腐蚀产物膜结构及成分特征，探讨耐蚀机理。相比3Cr钢，3Cr2Al钢中少量Al的添加提高了材料的抗CO₂腐蚀性能，在短周期(20 h)和长周期(144 h)条件下，其腐蚀速率分别下降15%和69%，这种耐蚀性能的提升主要是由于3Cr2Al钢表面产物膜中不仅有Cr的富集，同时还有Al的富集，提高了产物膜对基体的保护性。溶液中的氯离子对产物膜中Al的富集存在一定影响，在低氯溶液环境中，3Cr2Al钢表面腐蚀产物膜中Al/Fe原子比明显高于其Cr/Fe原子比，Al的富集更明显；当提高溶液氯离子浓度，腐蚀产物膜中Al/Fe原子比相比低氯溶液明显降低，Al的富集程度减弱，阳极极化曲线半钝化现象消失。

CO2 Corrosion Behaviour of A Novel Al-containing Low Cr Steel in A Simulated Oilfield Formation Water

The corrosion behavior of a new developed 3Cr2Al steel in a simulated high-temperature and high-pressure oilfield formation water was studied by means of weight loss method and electrochemical technique, as well as scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) etc. Results show that compared with the plain 3Cr steel, the corrosion rate of 3Cr2Al steel decreases significantly. By short period (about 20 h) test and long period (about 144 h) test, the corrosion rate for 3Cr2Al decreases about 15% and 69%, respectively. The addition of a small amount of Al could improve the CO₂ corrosion resistance of the 3Cr2Al steel to certain extent. This is mainly due to the fact that not only the Cr-, but also the Al-enrichment did emerge in the corrosion product on the steel surface, which thereby improves the protectiveness of the corrosion product scale. In the solution with lower Cl^- concentration, the Al/Fe atomic ratio in the corrosion product is much higher than the Cr/Fe atomic ratio, namely, the enrichment of Al is more obvious. If the Cl^- concentration in the solution increases, the Al/Fe atomic ratio in the corrosion product scale decreased significantly, the enrichment of Al is weakened, correspondingly, the semi-passivation disappeared.