Effect of Water Content on the Corrosion Behavior of Carbon Steel in Supercritical CO2 Phase with Impurities

Sufficient drying (water removal) of the CO₂ transport pipeline is required in order to prevent free water and excessive corrosion rates. The requirement for CO₂ pipelines, used for enhanced oil recovery (EOR) in the United States, is maximum 650 ppm (mole) of water. However, there is a possibility of increased corrosion rates in supercritical CO₂ phase with water vapor (below solubility level) in the presence of O₂ and SO₂. Thus, the objective of the present study is to evaluate the corrosion properties of carbon steel in supercritical CO₂/O₂/SO₂ mixtures with different amounts of water (under-saturated) related to the transmission of CO₂ to sequestration sites. The corrosion property of carbon steel was evaluated by using an autoclave with different pressures (max. 2000 psi), temperatures (max. 50^oC), and concentrations of impurities as well as water contents. The corrosion rate of samples was determined by weight loss measurements. The surface morphology and the composition of the corrosion product layers were analyzed by using surface analytical techniques (SEM, EDS, and Raman).