In the process of oil and gas field exploitation,the underground environment is complex and there are many influencing factors.CO2-O2 coexistence environment causes serious corrosion of oil well pipe steel,and there are few studies at present,so it is necessary to analyze the corrosion behavior of oil well pipe steel in CO2-O2 environment.In this paper,the corrosion mechanism of oil well pipe steel in CO2-O2 coexistence environment is studied,and the results are as follows:(1)CO2 corrosion rate drops to a very low after the early film formation,and the corrosion rate remains high in CO2-O2 coexistence environment.(2)After corrosion in a single CO2 environment,dense FeCO3 film is formed on the steel surface to protect the matrix from further corrosion,while in the CO2-O2 environment,the corrosion products are mainly FeCO3 and Fe oxides,among which Fe oxides reduce the adhesion between FeCO3 crystals and make the film loose and porous,thus promoting corrosion.(3)The temperature increase accelerates the mass transfer rate of oxygen,and the Fe oxides in the corrosion products with poor protection to the matrix increase,resulting in a sharp increase in the corrosion rate.
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