Impact of corrosion products on performance of imidazoline corrosion inhibitor on X65 carbon steel in CO₂ environments

The impact of pre-corrosion on the performance of an imidazoline-based corrosion inhibitor was evaluated with respect to inhibition of uniform and localised corrosion in CO2-environments. Corrosion protection was found to be a function of two factors, inhibitor adsorption/film formation and presence of corrosion products. This effect was most significant in the presence of a continuous FeCO3-rich layer with high coverage of the steel surface, resulting in the inhibitor only providing ∼25 % of the overall protection afforded by the corrosion inhibitor and FeCO3. The presence of corrosion products had a significant influence on inhibitor adsorption and on corrosion pit depth.