Efficient dual-function inhibitors for prevention of gas hydrate formation and CO2/H2S corrosion inside oil and gas pipelines

Abstract

• Waterborne polyurethanes (WPUs) were synthesized and evaluated as dual-function inhibitors. • All WPUs exhibited hydrate inhibition and anti-agglomeration effects on C1/C3 hydrates. • The corrosion inhibiting features of WPUs were revealed with several electrochemical tests. • WPUs were found to serve dual functions as hydrate and corrosion inhibitors. In this study, an effective hybrid inhibition of gas hydrates and corrosion was investigated to overcome compatibility problems between inhibitors and reduce the cost of production and transportation operations in the oil and gas industry. The newly synthesized waterborne polyurethanes (WPUs) were appraised as efficient dual-purpose gas hydrate and corrosion inhibitors through experimental and computational approaches. The onset temperatures of C1/C3 hydrates in the presence of WPUs were measured using a high-pressure autoclave to evaluate the performance of WPUs as gas hydrate inhibitors. The potential of WPUs as anti-agglomerants and the rheological behaviors of C1/C3 hydrates in the presence of WPUs were investigated using a high-pressure rheometer. All WPUs (WPU1, WPU2, WPU3, WPU4, and WPU5) were found to function as hydrate inhibitors and contribute to the prevention of agglomeration for C1/C3 hydrates. Molecular dynamics simulations revealed that the long-chained anionic parts of WPUs were adsorbed onto the hydrate surface while small cationic parts moved freely in the solution; thus, the interaction between the anions and water molecules was a dominant factor for C1/C3 hydrate inhibition. The corrosion inhibition activity of WPUs was evaluated by open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy techniques in H 2 S and CO 2 -saturated oilfield-produced water. The electrochemical measurements indicated that WPUs improved the polarization resistance of mild steel and significantly protected its surface against corrosive gases. The experimental and computational results indicated that WPUs can be used as efficient dual-function inhibitors for prevention of gas hydrate formation and CO 2 /H 2 S corrosion inside oil and gas pipelines, and also have potential as anti-agglomerant hydrate inhibitors.