Effect of CO2 and pressure on the stability of steels with different amounts of chromium in saline water

CO2-induced corrosion of casing and tubing steels is a relevant safety issue for compressing emission gasses into deep geological layers (CCS, Carbon Capture and Storage). The influence of CO2 and pressure of the surrounding media on steels is demonstrated in laboratory experiments providing a corrosive environment similar to a geological onshore CCS-site in the Northern German Basin (T = 60 °C, p = 1 - 100 bar, Stuttgart Aquifer, CO2-flow rate of 3 l/h, 700–8000 h exposure time). Corrosion kinetics and microstructures were characterized using specimens of heat treated 42CrMo4 (1.7225, casing) and soft annealed X46Cr13 (1.4034, tubing).

► Corrosion behaviour of X20Cr13, X46Cr13 and 42CrMo4 under CCS conditions.
► Long term exposure of samples (up to 1 year) in laboratory experiments.
► Kinetic, microstructural and phase analysis of the corrosion products.
► Influence of pressure is shown by different phases and lower corrosion rate.