Hydrate plugging during deep-sea hydraulic fracturing presents a severe operational risk, traditionally managed with high-volume, environmentally problematic thermodynamic inhibitors. This study investigates the complex morphological and kinetic influence of two common fracturing thickeners, polyacrylamide (PAM) and guar gum (GG), on methane hydrate formation using a high-pressure visualization autoclave. The results reveal that these polymers exhibit a pronounced “dual effect”. In the nucleation stage, both polymers act as potent kinetic inhibitors, substantially prolonging the nucleation induction time, with optimal performance observed at 3000 ppm for PAM and 1000 ppm for GG. This inhibition is mechanistically attributed to polymer–water hydrogen bonding that restricts water mobility and imposes an energetic barrier to clathrate cage formation, a conclusion supported by NMR T2 relaxation spectra. Paradoxically, following nucleation, the polymers accelerate bulk crystal growth to rates significantly exceeding those in pure water. This is driven by a critical morphological transformation: under shear, the viscous fluids entrain gas into a stable microbubble dispersion, while the polymers act as effective antiagglomerants. This prevents the formation of a passivating solid plug, instead creating a high-surface-area, mobile slurry that sustains rapid, bulk-volume growth. This dual function provides an inherent, two-stage safety protocol: a prolonged operational window during injection and the formation of a transportable slurry during shut-in. By reframing conventional thickeners as multifunctional flow assurance agents, this work establishes a theoretical basis for a safer, more cost-effective hydrate management strategy.
Peng et al. (Fri,) studied this question.