Rheological and dissociation characteristics of cyclopentane hydrate in the presence of amide-based surfactants and Span 80: From slurry to particle

This study first investigates the flow modification effects of a mixture of Span 80 and amide-based surfactants (DPLA and DPCA) on hydrate slurries using a rheometer. The results show that, although the mixed system shortens the critical time for hydrate formation compared to the pure Span 80 system, the peak and stable viscosities of the hydrate slurry decrease significantly when the concentrations of DPLA or DPCA reach medium to high levels (with reductions of 68.8 %–78.6 % for peak viscosity and 87.4 %–91.7 % for stable viscosity). The combination of 0.6 wt% Span 80 with DPLA and 0.8 wt% Span 80 with DPCA demonstrated the best hydrate inhibition performance. Subsequently, hydrate decomposition experiments were conducted on three systems containing Span 80, Span 80+DPCA, and Span 80+DPLA. The viscosity variations during the hydrate slurry decomposition process and the hydrate particle decomposition time were obtained. The results indicate that the viscosity of the slurry decreases almost linearly with temperature rise before decomposition. The addition of DPCA and DPLA reduced the decomposition temperature of cyclopentane hydrate in water-in-oil systems to approximately 0 °C. Additionally, for the first time, this study employed a micromechanical force measurement device combined with a micro-infrared thermography camera to capture morphological and thermal imaging features during the decomposition of hydrate particles. This research not only offers new perspectives for understanding the thermal stability of hydrates and the decomposition mechanism of hydrate plugs, but also provides potential control strategies for field applications in managing hydrate blockages.