CO₂ Corrosion Behavior of N80Q Steels under 90 ℃Underground Environment of Certain Oil Field

Abstract

In order to provide reference suggestions for selection of materials for the actual underground corrosion environment of a certain oil field，a high-pressure autoclave was used to simulate the CO2 corrosion behavior of N80Q steel pipes prepared by the 25Mn2，1CrRE and 2Cr steel under 90 ℃and 1.0 m/s in the underground corrosive environment of the oil field.Additionally，scanning electron microscopy，energy dispersive spectroscopy and X-ray diffraction were utilized to characterize corrosion product films of three types of steel.Results showed that the three steels mainly exhibited uniform corrosion characteristics at 90 ℃，and the difference in average corrosion rates was not significant.Meanwhile，the corrosion product films consisted of a relatively dense double-layered structure，and their composition were main FeCO3 and a small amount of FeOOH.The research suggested that Fe3C as an anode in the corrosion film could generate FeCO3 and FeOOH，which led to a significant decrease in corrosion rate at 90 ℃.

Keywords

• co₂ corrosion；low-alloy steel；anodic protection effect