Acacia sap will protect oil and gas equipment from corrosion.

The article with the findings has been published in the journal "Corrosion Science." The research has been funded by the Ministry of Education and Science of Russia and the National Natural Science Foundation of China.

Corrosive damage to equipment for the extraction, transportation, and processing of mineral resources accounts for nearly a quarter of accidents in the oil and gas industry. The use of special chemical compounds—corrosion inhibitors—is the most effective and accessible method for combating corrosion. However, many of these inhibitors may contain toxic elements that pose a risk to the environment. Consequently, there is a growing interest in "green" inhibitors derived from biological sources that are safe for the ecosystem. Specifically, biopolymers and plant extracts from fruits, leaves, and flowers are being considered as components.

Natural gas is now a cleaner and more environmentally friendly alternative to oil and coal due to its lower carbon dioxide emissions. In recent years, its consumption has steadily increased, but available deposits are becoming increasingly depleted. To meet global gas demands, extraction must occur in harsher conditions, particularly in acidic environments saturated with hydrogen sulfide, where corrosion is one of the most significant challenges encountered.

To develop more environmentally friendly inhibiting substances, biopolymers based on carbohydrates sourced from natural origins are being actively studied. These include cellulose, starch, pectin, chitosan, dextrin, alginates, and natural gums. The latter are high-molecular carbohydrates extracted as sap or resin from trees and various plants. The use of gums allows for the creation of complexes with metal ions and the formation of a protective layer on the surface, shielding it from corrosion.

Biopolymers have already demonstrated their potential as inhibitors in the oil and gas industry. However, their durability and stability in acidic environments are not as effective. This issue can be addressed by adding other polymers to enhance their thermal stability.

Scientists from PNIPU and KFU have developed entirely new inhibitors based on gum arabic, specifically acacia gum, into which polyurethane has been incorporated. The synthesized product will help prevent corrosion of carbon steel during gas extraction in acidic environments.

"Gum arabic is typically obtained from the stems and branches of acacia. Due to its properties, it effectively prevents corrosion of various metals and alloys, such as steel and aluminum, in different environments (acidic, alkaline, and neutral). Its qualities provide exceptional surface coverage even at minimal concentrations and excellent long-term corrosion protection," explains Dmitry Martyushev, professor of oil and gas technologies at PNIPU and Doctor of Technical Sciences.

The polytechnic researchers synthesized three polyurethanes with grafted (attached to the structure) molecules of gum arabic at varying degrees of grafting and subjected them to experimental and theoretical studies as potential inhibitors for acidic environments. The synthesis involved two main stages: the production of polyurethane prepolymers and their subsequent gradual attachment to the chemical structure of gum arabic at different concentrations (10.4%, 17.2%, and 25.4%).

"The studies showed that pure gum arabic can moderately reduce corrosion in acidic environments by 74% protection. The incorporation of polyurethane into its structure significantly enhances the inhibiting activity to 94-95%. The most optimal amount of polyurethane incorporation was found to be 17.2%, and further attachment does not lead to significant changes," shared Dmitry Martyushev.

"These results demonstrate that modifying the structure of gum arabic effectively improves its properties, making it a promising eco-friendly inhibitor for the gas industry, as only 17.2% consists of polyurethane," explains Abdolreza Farhadian, senior researcher at the Department of Oil and Gas Engineering at KFU.

The polytechnic researchers tested the inhibitor's effectiveness in acidic environments and found a reduction in surface damage and the formation of corrosion products on the metal. It forms a protective layer that acts as a barrier, preventing the interaction of corrosive elements with the surface.

The environmentally friendly biological inhibitor developed by scientists at PNIPU and KFU is a promising alternative to conventional substances for combating corrosion. Its application will enhance the durability of equipment used in acidic environments and the resilience of the global oil and gas industry.