Rheological Properties of Methane Hydrate Slurries Formed From AOT plus Water plus Oil Microemulsions

The in situ formation and flow properties of methane hydrates formed from water-in-oil microemulsions composed of water, dodecane, and aerosol OT surfactant.(AOT) were studied using a unique high pressure rheometer. AOT microemulsions have high stability (order of months), well-characterized composition, and yield reproducible results compared to hydrate studies in water-in-crude oil emulsions. Viscosity increases on the order of minutes upon hydrate formation, and then decreases on the order of hours'. If significant unconverted water remained after: the initial formation event, then viscosity increases time, as methane slowly dissolves': and converts additional water to hydrate In addition to transient, formation Measurements, yield stresses and flow curves are Measured for a set of experimental conditions. Hydrate slurry viscosity and yield stress increase with increasing water volume fraction, increasing initial pressure, :decreasing temperature, and decreasing formation shear rate.