Wellbore integrity and corrosion of low alloy and stainless steels in high pressure CO2 geologic storage environments: An experimental study

CO2 corrosion behavior of three different steels that are commonly used as casing material in CO2 geologic storage environments (i.e., 1018 carbon steel, 5Cr steel, and 13Cr steel) was studied at 30 and 80 bar CO2 partial pressures and 60 °C in the presence of a simulated brine for the Weyburn-Midale reservoir system. Electrochemical techniques including linear polarization resistance (LPR), and potentiodynamic polarization measurements, were used to monitor the corrosion rate during experiments and study the corrosion mechanism. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and Raman spectroscopy were used for surface analysis. A weight loss technique was also employed to measure the corrosion rate. Carbon steel showed very high corrosion rates of ∼20 mm/y under the test conditions of this research. 5Cr steel can be considered as a replacement for the carbon steel under these conditions by the reduction in the corrosion rate by a factor of 3. However, corrosion rate was still high (∼6 mm/y). 13Cr steel showed the best corrosion resistance under testing conditions employed for this research, and can be considered as the best option for combating high pressure CO2 corrosion if materials selection is considered as the best option for corrosion mitigation.