Corrosion of N80 and Cr13 steels in brine and CO2

The corrosion behavior of the N80 casing and Cr13 steels was studied in a brine-CO2 mixture in autoclaves using electrochemical measurements and mass loss test. The brine solution contained 130 g/l NaCl, 22.2 g/l CaCl2 and 4 g/l MgCl2, representative for formation waters in North Sea wells. The objectives were to gain substantial cor-rosion data to ensure the selection of adequate casing material and to predict the service life of the casing under CO2 storage conditions. The N80 casing steel showed general corrosion and Cr13 showed pitting corrosion in the brine plus CO2 and 1%H2S. The Cr13 steel samples suffered more severe corrosion at the half-immersion position (the lower part in the liquid and the upper part in the gas phase) than at the complete immersion position