Study On Formation And Characteristic Of Corrosion Product Layer Of Low-chronium Steel

Aautoclave tests and SEM, EDS, XRD technologies were used to study CO2 and H2S corrosion behavior of 3Cr110 and P110 steel tubing under the high temperature and pressure environment of oilfield environment. Electrochemical characteristics of samples with corrosion product layer were studied.The results showed that corrosion product was formed by FeCO3 under CO2 corrosion environment, localized corrosion resistance of 3Cr110 was stronger than P110. With the test time increased, the corrosion rate of 3Cr110 and P110 gradually slowed down, the ability which corrosion product hindered ion migration increased. With the temperature increased, the corrosion rate of 3Cr110 and P110 gradually slowed down.Corrosion product was formed by FeS under CO2 and H2S corrosion environment, corrosion resistance of 3Cr110 was stronger than P110. With the H2S pressure increased and the CO2 pressure reduced, the corrosion rate of 3Cr110 and P110 reduced. With the temperature reduced, the corrosion rate decreased.After corrosion products formed, the transfer resistance of 3Cr110 was bigger than P110, so, protective effect of 3Cr110 was better than P110.The corrosion products of 3Cr110 and P110 were Characteristic with semiconductor. The temperature of film formed affected the conductive mechanism of film. With the temperature of film formed increased, the film corrosion pore resistance increases.With the increase of Cl- concentration, corrosion resistance of simples covered with corrosion product reduced, and concentrations of the donor and acceptor concentrations of corrosion product have increased, the possibility of localized corrosion was larger in defect region.