Using Microscopic Observations of Cyclopentane Hydrate Crystal Morphology and Growth Patterns To Estimate the Antiagglomeration Capacity of Surfactants

The crystal growth and morphology of cyclopentane (CP) hydrates at a quiescent water/oil interface in the presence of ten different surfactants were observed under a microscope. In most cases the oil was CP, but for some of the observations a 50/50 vol% mixture of CP and n-octane (n-C8) (or n-dodecane (n-C12)) was used instead. For some of the surfactants, gas hydrates formed from a methane (CH4)/propane (C3H8) gas mixture at a quiescent water/n-C8 interface were also observed. The capacity of the surfactants to prevent the hydrate particles from agglomerating was assessed by measuring torque on oil-dominated systems (70 vol%) in a stirred autoclave at subcoolings of 6 °C and 10 °C for the CP hydrates and CH4/C3H8 hydrates respectively. The oil phases were the same as those used in the morphology study. In the case of CP hydrates, the agglomeration state of the system was directly observed by opening the autoclave at the end of the hydrate formation. The size of the CP-hydrate particles was measured and t...