Corrosion Inhibition for Sour Offshore Oil and Gas Production Facilities

Abstract

Abstract Corrosion is one of the major problems in offshore infrastructure due its exposure to the harsh marine environment characterized for high salinity water, non-stable weather conditions, long exposure to ultraviolet sunlight, presence of bacteria, dissolved oxygen, and carbon dioxide in seawater, etc., that is why the oil and gas industry is constantly looking for preventive and corrective solutions to extend the service life of the facilities and improve safety operation. Most common approaches to prevent corrosion in offshore infrastructure include the use of highly corrosion resistant material and the use of anticorrosive coatings. Inhibitors are also widely used as part of the injection fluids to eliminate the corrosion of infrastructure induced by its interactions with reservoir fluids and chemicals commonly appeared in offshore production. Two of the most critical types of corrosion in oil and gas upstream are sweet corrosion that is caused by CO2 and sour corrosion that is induced by H2S. For both, most of the research is focused on their corrosion mechanisms, corrosion products, corrosion behavior modeling, and inhibitor performance. A great research effort has been directed toward CO2 corrosion, yet H2S related study is on the rise. In this study we put together a laboratory workflow to evaluate the potential of corrosion in offshore infrastructure to reduce the risks associated to the presence of corrosion. The proposed workflow is focused on the evaluation and optimization of the selection of the inhibitors for H2S related environments. The study started with an in-depth literature review to know the state of the art in the topic. An analysis of the finding indicates that most of the inhibitor studies reported are associated to CO2 environment, so we focused the study on inhibitors for H2S systems including types of inhibitors, their pros vs cons, and testing methods to evaluate their performance. Finally, based on our experience a laboratory workflow is proposed to mitigate corrosion in the early stage of production. This work demonstrates the importance of selecting the right laboratory protocol according to the corrosion type to save time and resources making the laboratory evaluation more useful and reliable.