(355a) Potential Use of Solid Nanoparticles to Mitigate Hydrate Formation in Water-in-Oil Emulsions in the Presence of Wax

Clathrate hydrates are non-stoichiometric, ice-like crystalline solids that can lead to plugging of crude oil pipelines. In addition, wax deposition leads to partial or complete blockage of crude oil pipelines. Crude oil is a complex hydrocarbon mixture that includes asphaltenes, aromatics, naphthenes, resins, and paraffins. De-convoluting the effects of solid particles and surfactants that are present in crude oil on hydrate and wax formation would improve the hydrate and wax prediction strategies. The effect of hydrophobicity of solid particles, surfactants, and water on hydrate and wax formation in water-in-oil emulsions was investigated. Cyclopentane hydrates are studied in model oil systems using surfactant and solid particles, which act as stabilizing agents. An Olympus BX53 polarized optical microscope with shear cell and temperature control (-50°C to 450°C) stage is used to quantify droplet size distribution, and hydrate crystals morphology. A DHR-3 stress controlled rheometer whose temperature can be controlled between -20°C to 150°C is used to examine the rheological behavior of hydrate forming emulsions. Furthermore, a differential scanning calorimeter (DSC) was used to determine (i) the emulsion stability, (ii) the extent of hydrate conversion, and (iii) wax appearance temperature.

The results showed that the presence of silica and water did not have a significant effect on the wax appearance temperature (WAT). In addition, the amount of hydrate formation decreased with an increase in hydrophobicity of silica nanoparticles at the water−oil interface. The presence of wax promoted hydrate formation in water-in-oil emulsions stabilized using either highly hydrophobic silica nanoparticles or a surfactant. Our data indicate that wax did not exist at the water/oil interface; therefore, wax did not serve as nucleation sites for hydrate formation. The addition of wax affected the droplet size of water-in-oil emulsions stabilized by highly hydrophobic silica nanoparticles, which, in turn, influenced hydrate formation. Also, hydrate dissociation led to destabilization of water-in-oil emulsions in the presence of wax that led to changes in the WAT. Rheological investigations were also carried out to determine the flow behavior and yield stress of hydrates in the presence of solid particles of different wettabilities in the presence of wax. Rheological Investigations also were carried out to examine the potential use of hydrophobic silica nanoparticles in hydrate mitigation strategies in surfactant stabilized water-in-oil emulsions.