In situ electrochemical corrosion measurements of carbon steel in supercritical CO₂ using a membrane-coated electrochemical probe

Growing interest in transporting supercritical carbon dioxide (scCO ₂) for enhanced oil recovery and carbon capture and storage has led to an increased interest in the corrosion behavior of pipeline steels at varying levels of water contamination. Electrochemical measurements in scCO₂ fluids have been limited by low solution conductivity even when saturated with water vapor. Recent efforts to overcome this barrier by using electrochemical probes coated with a thin membrane of ion conducting polymer are reported here. A prototype probe was tested using carbon steel and corrosion tests were performed using linear polarization resistance, electrochemical impedance spectroscopy, and electrochemical frequency modulation. While the construction of the probe had an impact on the electrolyte resistance and mass transfer impedance, the charge transfer impedance varied little across the tested probes. The probe design could be used to predict worst-case scenario corrosion rates from charge transfer control for a variety of lowconductivity environments.