温度、HCO_3^-和Cl^-对J55钢在安塞油田采出水中腐蚀行为的影响

Effect of Temperature, HCO_3^- and Cl^- on Corrosion Behavior of J55 Steel in Oil Well Produced Water for Ansai Oilfield

针对安塞油田长2油井采出水中HCO_3^-及Cl^-浓度相对较高造成的J55套管腐蚀穿孔严重的问题,利用动电位极化法和电化学阻抗法研究了温度、HCO_3^-和Cl^-浓度对J55钢腐蚀行为的影响规律,利用扫描电镜(SEM)对比分析了45和80℃试片实验后的表面形貌。结果表明:温度、HCO_3^-和Cl^-浓度对J55钢腐蚀的影响规律相似,分别在温度为80℃时、HCO_3^-浓度为7 g/L和Cl^-浓度为10 g/L时出现腐蚀速率的极大值,使腐蚀电流最大和电荷转移电阻最小;HCO_3^-浓度不小于5 g/L时,J55钢阳极极化曲线出现钝化;温度不小于60℃和HCO_3~ˉ浓度不小于5 g/L时,电化学阻抗谱出现Warburg阻抗,并且Warburg阻抗随HCO_3^-浓度变化较大,随温度变化较小;80℃时试片表面的腐蚀产物膜较45℃时更厚且均匀。

The concentration of HCO3^-and Cl^-in oil well produced water of Ansai oilfield Layer 2are relatively higher, causing problems of local corrosion and serious perforation of J55 casing pipeline. Effect of temperature, HCO3^- and Cl^-on corrosion behavior of J55 steel in the oil well produced water was studied by using potentiodynamic polarization and electrochemical impedance spectroscopy（EIS）. The corrosion morphology of J55 samples tested at 45 and 80 ℃ was examined by SEM. The results showed that temperature, HCO3^-and Cl^-exhibit similar effect on the corrosion of J55 steel, the corrosion rate of J55 steel exhibits a maximum, correspondingly a maximum of corrosion current and a minimum of the charge transfer resistance when the temperature is80 ℃, the concentration of HCO3^-is 7 g/L and the concentration of Cl^-is 10 g/L respectively. Besides, passivation occurred during anodic polarization when the concentration of HCO3^-is greaterthan or equal to 5 g/L. There were Warburg impedance when the concentration of HCO-3is greater than or equal to 5 g/L and the temperature is greater than or equal to 60 ℃ respectively. The Warburg impedance changed largely with the change of concentration of HCO-3, but less with the change of temperature. The corrosion product film is thicker and more uniform at 80 ℃ rather than at 45 ℃.