Abstract
CO2 corrosion of mild steel pipeline a common problem that cannot be ignored in the oil and gas industry. At present, a big challenge is to simulate the real corrosive conditions in term of the solution chemistry within a closed system and high gas flow velocity for natural gas field in the deep water in the laboratory, and results in the traditional evaluation methods such as mass loss cannot be able to provide an accurate experimental results. In this paper, the corrosion behavior of carbon steel with/without the presence of corrosion inhibitor were tested in a high pressure and high gas velocity flow loop. The corrosion rates of corrosion inhibitor at different concentrations were monitored by high resolution inductance probe under different wall shear stress. The results show that the inhibitor efficiency can be achieved by increasing the concentration of the inhibitor, as well as the wall shear stress increases for the adsorption-type inhibitor. However, for the higher wall shear stress, due to the high baseline corrosion rate, it is impossible to reduce the corrosion rate to the ideal value even if the concentration of the inhibitor is too high. If the corrosion inhibitor is continuously injected, the inhibitor molecule can adsorb on the metal surface more quickly with the increase of wall shear stress, and the final inhibition efficiency is basically the same. Nevertheless, when the inhibitor is stopped, the desorption rate of the inhibitor increases with the increase of wall shear stress, and the inhibitor is more likely to fail.
