New insights into methane hydrate inhibition with blends of vinyl lactam polymer and methanol, monoethylene glycol, or diethylene glycol as hybrid inhibitors

Gas hydrate inhibition is a relevant topic of flow assurance. Thermodynamic hydrate inhibitors (THIs) and kinetic hydrate inhibitors (KHIs) are applied to prevent gas hydrates formation in oil and gas production facilities. We have carried out extensive experimental studies to further develop the hybrid inhibition strategy involving KHI/THI formulations. We determined methane hydrate equilibrium conditions for an aqueous solution of methanol, MEG, and DEG (<50 mass%). Subsequently, we studied the kinetics of methane hydrate nucleation and growth for an aqueous solution of commercial vinyl lactam KHI and its blends with alcohols. KHI loses its ability to inhibit hydrate nucleation at >= 20 mass% methanol. Adding MeOH to KHI solution also accelerated the growth of methane hydrate. The addition of glycols to KHI increases the hydrate onset subcooling. KHI/MEG blends are optimal for hybrid inhibition as they demonstrate the enhanced delay of gas uptake and reduced rate of methane hydrate growth.CO 2022 Elsevier Ltd. All rights reserved.

Automated summary

Gas hydrate inhibition is an important topic in flow assurance. The hybrid inhibition strategy involving kinetic hydrate inhibitors (KHIs) and thermodynamic hydrate inhibitors (THIs) has been developed through extensive experimental studies. Methane hydrate equilibrium conditions were determined for aqueous solutions of methanol, MEG, and DEG (<50 mass%). The kinetics of methane hydrate nucleation and growth were studied for aqueous solutions of commercial vinyl lactam KHI and its blends with alcohols. A blend of KHI and MEG is optimal for hybrid inhibition, showing enhanced delay of gas uptake and reduced rate of methane hydrate growth.