Evaluation of high shear inhibitor performance in C02-containing flowinduced corrosion and erosion-corrosion environments in the presence and absence of iron carbonate films

Carbon steel pipeline degradation occurs as a result of erosion-corrosion during oil and gas production. Sand particles contribute to this effect when they are present in conjunction with a high flow velocity. In carbon dioxide (CO2) environments, and under certain conditions, the corrosion rate of the steel can be reduced by the formation of a protective iron carbonate (FeCO3) layer. This work assesses the ability of FeCO3 to protect the underlying steel in flow-induced corrosion and erosion-corrosion environments. Autoclave tests are performed at 60 degrees C and 100 bar in a 1 wt%NaCl CO2-saturated solution for a duration of 48 h to develop 60 mu m thick FeCO3 films. The film-covered samples were then transferred into a submerged impinging jet (SIJ) apparatus to assess their ability to resist both flow-induced corrosion and erosion-corrosion environments at 25 degrees C and a flow velocity of 15 m/s (both with and without 1000 mg/L sand). Tests were also conducted in the presence of a commercially available corrosion inhibitor to evaluate the interaction. Results indicate that the FeCO3 layer is able to considerably suppress corrosion of the carbon steel substrate. Experiments in the presence of both the FeCO3 film and corrosion inhibitor demonstrated that there is a notable synergistic effect between these two components in providing resistance to erosion-corrosion.