Synthesis and evaluation of anionic guar gum derivatives as dual-function inhibitors for methane hydrate formation and metal corrosion in oil and gas pipelines

This study investigated anionic guar gum derivatives as dual-purpose inhibitors for methane hydrate formation and metal corrosion in oil and gas pipelines. Sulfonated guar gum (SHG), phosphorylated guar gum (PGG), and guar gum grafted acrylamide (GG-g-PAM) were synthesized and evaluated for their kinetic hydrate inhibition and corrosion inhibition properties. The results demonstrated that all anionic guar gums exhibited superior inhibition effects compared to native guar gum and polyvinylpyrrolidone (PVP), with GG-g-PAM achieving the highest maximum subcooling of 10.47 °C at the concentration of 0.5 wt%. SHG showed the most pronounced effect during the hydrate growth stage, and exhibited the best corrosion inhibition efficiency as well, with a significant inhibition efficiency (>92 %) at 0.5 wt%, surpassing other additives and a commercial imidazoline inhibitor. The formation of a protective film on carbon steel, enhanced by anionic groups, was confirmed through increased contact angles and reduced corrosion rates. Electrochemical impedance spectroscopy (EIS), polarization curves and SEM-EDX spectra further substantiated the effectiveness of the anionic guar gums in preventing carbon steel corrosion in CO₂-saturated environments. The findings underscore the potential of anionic guar gum, particularly SHG, as a sustainable and effective bio-based additive for simultaneous hydrate inhibition and corrosion protection in oil and gas pipelines.