Corrosion Study on Wellbore Materials for the CO₂ Injection Process

• Main Authors: Le Quynh Hoa, Ralph Bäßler, Dirk Bettge, Enrico Buggisch, Bernadette Nicole Schiller, Matthias Beck
• Format: Article
• Language: English
• Published: MDPI AG 2021-01-01
• Series: Processes
• Subjects: Carbon capture storage (CCS); carbon dioxide; corrosion; carbon steels; aquifer fluid; cement
• Online Access: https://www.mdpi.com/2227-9717/9/1/115

For reliability and safety issues of injection wells, corrosion resistance of materials used needs to be determined. Herein, representative low-cost materials, including carbon steel X70/1.8977 and low alloyed steel 1.7225, were embedded in mortar to mimic the realistic casing-mortar interface. Two types of cement were investigated: (1) Dyckerhoff Variodur commercial Portland cement, representing a highly acidic resistant cement and (2) Wollastonite, which can react with CO₂ and become stable under a CO₂ stream due to the carbonation process. Exposure tests were performed under 10 MPa and at 333 K in artificial aquifer fluid for up to 20 weeks, revealing crevice corrosion and uniform corrosion instead of expected pitting corrosion. To clarify the role of cement, simulated pore water was made by dispersing cement powder in aquifer fluid and used as a solution to expose steels. Surface analysis, accompanied by element mapping on exposed specimens and their cross-sections, was carried out to trace the chloride intrusion and corrosion process that followed.