Sufficient drying (water removal) of carbon dioxide (CO2) in transport pipelines is required to prevent
breaking-out of free water and consequent excessive corrosion rates. The drying requirement for CO2
pipelines, used for enhanced oil recovery (EOR) in the United States, is a maximum of 650 ppm (mole)
of water. However, there is a possibility of increased corrosion rates in supercritical CO2 phase with
water vapor (below its solubility level) in the presence of oxygen (O2) and sulfur dioxide (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
operating at different pressures (maximum 2000 psi), temperatures (maximum 50oC), and
concentrations of O2 and SO2 impurities as well as water content. The corrosion rate of samples was
determined by weight loss measurements. The surface morphology and the composition of the
corrosion product layers were analyzed using surface analytical techniques (scanning electron
microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD)).
Key words: Supercritical CO2, CO2 corrosion, H2O, O2, SO2, carbon steel, carbon capture and storage