Electrochemical Behavior and Corrosion Mechanism of X65 Steel in CO₂-saturated Oilfield Water

Mechanism of anodic reaction of X65 steel in CO2-saturated oilfield water was inferred from thermodynamic calculation.It was found that X65 steel was corroded through both reactions Fe→Fe2++2e and Fe+HCO-3→FeCO3+H++2e.Under the experimental condition,the reaction Fe+2H2O→Fe(OH)2+2H++2e could not take place because its equilibrium electrode potential was higher than the free corrosion potential of the steel.EIS results were consistent with the result of thermodynamic calculation.