Inhibitors for High‐Temperature Corrosion in Oil and Gas Fields

High-temperature operations in the oil and gas industry are accompanied by metal degradations that are unique in both processes and challenges. It involves corrosion processes that take place at temperatures from 260 °C and above; usually in the absence of water and dominantly in the presence of hot gases (it is also called hot corrosion). It is a chemical reaction that takes place at the metal/gas interface at elevated temperature. Thus it out rightly disqualifies all inhibitors that are unstable or perform poorly above room temperature. Those that are stable above room temperature can be tested further at elevated temperatures up to 260 °C or more. This temperature serves as a dividing line between low-temperature corrosion and high-temperature corrosion. This is because below 260 °C water can be present and the mechanism for aqueous corrosion applies, but above this water ceases to exist and the mechanism becomes totally different. Thus, the mechanisms for high-temperature corrosion can be majorly categorized into oxidation, sulfidation, sulfidation–oxidation, chlorination, nitridation, and carburization; these are very important in the formulation of inhibitors for high-temperature applications. This chapter deals with high-temperature corrosion inhibitors for oil and gas industries where the components are exposed to various aggressive corrosive environments along with high temperature. In addition to the fact that performance of inhibitors are highly temperature dependent, a large number of inhibitors with high inhibition efficiency at low and moderate temperatures have been found to show low efficacy at elevated temperatures of the same system.