Effect of Temperature, HCO3- and Cl- on Corrosion Behavior of J55 Steel in OilWell ProducedWater for Ansai Oilfield postprint

Abstract: The concentration of HCO3- and Cl- in oil well produced water of Ansai oilfield Layer 2 are 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 is 80 ℃, 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 greater than or equal to 5 g/L. There were Warburg impedance when the concentration of HCO3- is 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 HCO3- , but less with the change of temperature. The corrosion product film is thicker and more uniform at 80 ℃ rather than at 45 ℃.