In the simulating high temperature and high pressure oilfield environment containing COe, the structure characteristics and ion passing selectivity of corrosion scale were experimentally researched for conventional NS0 steel and 4% Cr containing NS0 steel. The results shown that the iron carbonate scale formed on conventional NS0 steel has cation passing selectivity, so that the protection properties of the scale is relatively poor for metallic matrix material, and the scale relatively easily enhance the formation of pitting. The amorphous compound Cr(OH)3 scale formed on 4% Cr containing N80 steel has anion passing selectivity, it is able to remarkably reduce corrosion rate and prevent the formation of pitting.
Key Words:co2 corrosion, Corrosion scales, N80 steel, Cr-containing N80 steel, ion passing selectivity