Effect of temperature and inhibitor injection frequency on corrosion inhibition of mild carbon steel in sweet environment

Corrosion is a common issue encountered in the oil gas industry posing challenges like reduced oil and gas production, reduced life of equipment and thus increased operational cost. Thus, mitigation of corrosion in oil and gas industry is of high importance since the economic damage due to corrosion is tremendously high. Carbon steel is one of the most commonly used material in oil and gas industry. However, it is susceptible to severe corrosion degradation in CO2 environment. Since mild carbon steel corrosion resistance is very poor in harsh environments, the use of corrosion inhibitors is considered as one of the suitable and economical methods [1]. Most of the commercial corrosion inhibitors comprises of amine, which adsorbs on the metal surface and inhibits the corrosion processes. There are various factors, which influence the adsorption, and efficiency of corrosion inhibitors, such as molecular structure of the inhibitors, inhibitor concentration, exposure time, electrolyte chemistry, and temperature of the system, etc. Temperature has a great influence on the rate of corrosion and its variation is a very useful parameter for investigating the inhibitor adsorption mechanism. The effect of temperature is very complex parameter but it provides the probability of calculating thermodynamic adsorption and kinetic corrosion parameters, which help in determining the type of adsorption of the studied inhibitor. Another effect, inhibitor injection frequency that is correlated to inhibitor efficiency is also dependent on the time, temperature and concentration of the inhibitor. For lower concentration, the inhibitor efficiency fall with rise in temperature and time. That is because of the physical adsorption with occurs initially and for higher concentration range the chemical adsorption of the inhibitors occurs on the metal surface.