Corrosion Behavior of N80 Steel in CO₂ Flooding Produced Water

For investigate the corrosion behavior of N80 steel at different depths of wells during production， high-temperature and highpressure reactors were used to simulate the corrosion conditions of CO2 flooding wells.The corrosion products and morphology were analyzed using methods such as weight loss，scanning electron microscopy (SEM)，and three-dimensional optical measurement analysis.Results showed that at a CO2 partial pressure of 0 MPa， the uniform corrosion and pitting corrosion rates of N80 steel were lower than those in other corrosive environments under CO2 partial pressures.With the increase of well depth and CO2 partial pressure， the uniform corrosion rate of N80 steel showed an overall trend of first increasing and then decreasing.At depths of 600 m and 2 000 m， the trend of maximum pitting corrosion rate and uniform corrosion rate was the same.At 1 200 m， the maximum pitting corrosion rate gradually increased with the increase of CO2 concentration.Besides， with the increase of well depth and CO2 concentration， the corrosion product film of N80 steel became denser and formed a two-layer corrosion product film mainly composed of FeCO3.