Initiation of Localized Corrosion on N80 Carbon Steel in High-pressure and High-temperature CO₂ Enhanced Oil Recovery Production Fluids

The corrosion behavior of N80 steel was investigated in an oil-water mixed condition at pressure of 10 MPa and temperature of 80 ℃, simulating the production fluids of CO₂ enhanced oil recovery (EOR) in Shengli oilfield. It was found that the corrosion morphology was highly dependent on the size of water droplets in a water-in-oil emulsion. When water droplets were small, the contact time of water droplets on steel surface was short and the corrosion product particles were small, leading to shallow localized pits. When water droplets were larger than a critical size, water droplets might be flattened and could wet the surface for a longer time, producing a larger patch of corrosion product and accelerating corrosion damages.