Gas Hydrate and Corrosion Inhibition Performance of the Newly Synthesized Polyurethanes: Potential Dual Function Inhibitors

Gas hydrate plugging and corrosion are two major flow assurance problems in oil and gas transmission pipelines. Since an incompatibility problem can occur during the simultaneous injection of gas hydrate and corrosion inhibitors, efficient dual function inhibitors would be an advantage. This study reports several newly synthesized waterborne polyurethanes (WPUs) that have a high potential as both corrosion inhibitors and gas hydrate kinetic ones. The length of the side substituents in different parts of the polymer and the ratio of polyethylene glycol (PEG) 400/1,2-butanediol were varied. The hydrate inhibition ability of WPUs was assessed using sapphire rocking cells (RCS6); weight loss, open circuit potential, and potentiodynamic polarization tests were employed to estimate their anti-corrosion activity. It was revealed that butyl derivatives (ethyl-butyl and methyl-butyl combinations) showed slightly better inhibition performance than commercial hydrate inhibitor poly(N-vinyl caprolactam) at 0.25 wt %, while partial replacement of PEG 400 with 1,2-butanediol reduced the inhibition activity. The gravimetric and electrochemical measurements confirmed that WPUs can suppress significantly the mild steel corrosion in both distilled and oilfield produced water saturated with CO2. Almost complete corrosion inhibition (96% and 98%) was achieved with 0.25 wt % of ethyl-butyl and methyl-butyl derivatives (without 1,2-butanediol), respectively. These findings indicate that WPUs can be considered as potential dual function reagents for inhibiting the gas hydrate formation and mild steel corrosion in CO2 saturated environments.