Water-soluble polymers inhibit methane hydrate formation: A molecular dynamics simulation study

Abstract

The formation and stability of methane hydrates have significant implications for energy development and carbon capture and storage (CCS) technologies. This study employs molecular dynamics simulations to investigate the influence of commonly used reservoir modification polymers (PAM, HPAM, and PAA) on methane hydrate formation. The results indicate that the inhibition mechanisms of these polymers primarily manifest in three aspects: their ability to occupy active sites on the hydrate surface, adsorb methane molecules in the solution, and form hydrogen bonds with water molecules. Furthermore, the effectiveness of these mechanisms largely depends on the number of carboxyl groups on the polymer chains. Specifically, HPAM exhibits optimal inhibition performance due to its moderate methane adsorption capacity and rigid molecular structure, which minimize bubble formation, facilitate hydrogen bonding, and effectively occupy hydrate surface active sites. In contrast, PAA demonstrates inferior inhibition effects because its molecular chains tend to curl, reducing their ability to occupy active sites, while excessive methane adsorption weakens hydrogen bond formation with water molecules. PAM shows intermediate inhibition performance due to its weaker methane adsorption capacity and moderately rigid molecular chains. This study advances the understanding of the molecular mechanisms underlying polymer-mediated inhibition of methane hydrate growth.