N80 Oil Tube Steel Corrosion Behavior in Different CO2 Saturated Brine

The experiment was carried out to illustrate the corrosion behavior of N80 exposed to CO2 -saturated brine conditions through electrochemical experiments, corrosion mass loss methods and surface analysis. With the increase of the CO2 pressures and temperatures, the corrosion product films were gradually thicken but non-uniform. The corrosion products on the sample surface were crystalline and/or amorphous structures, mainly composed of FeCO3 . With the increase of CO2 pressures at 50 degrees C, the corrosion rate would gradually experience three stages, and when the CO2 pressure was 2MPa, the corrosion rate was up to the maximum value and the surface of sample had the characteristics of pit erosion and mesa corrosion. With the rise of temperatures at 10 MPa, the corrosion rates of N80 pipeline steel increased slowly from 65 degrees C to 80 degrees C because of the thicker corrosion products, but the pitting corrosion increased because the FeCO3 and CaCO3 would be amorphous structures.