Deposition Behavior of the Asphaltene-Stabilized Emulsion and its Interfacial Rheology at Oil-Brine Interface

Asphaltenes are polyaromatic molecules in crude oil that are known to precipitate and deposit in pipelines, leading to significant flow assurance problems. Asphaltenes are surface-active and stabilize water-in-oil emulsions by flocculating and coagulating at interfaces. Stability of these emulsions is widely studied, but their role on the deposition behavior in the multiphase flow system is unclear. In this study, we elucidate the deposition behavior of asphaltene-stabilized water/brine-in-oil emulsions in microfluidics and further use the double-wall ring (DWR) rheometer to characterize the rheological responses of the asphaltene interface. The interface formed with 1mM to 1M of NaCl and CaCl₂ showed different rheological responses at oil-brine interface as well as the deposition rate in microfluidic devices. Higher salinity lowered the elasticity of the interface resulting in larger emulsions and eventually altered the blockage of the microchannel. Also, various oil-to-water ratios (water concentration: 0 wt% to 20 wt%) are studied. Lower the ratio gives rise to higher deposition rate. Finally, this multiphase deposition in microchannel is characterized by confocal laser scanning to determine the composition of the deposit. This combined imaging in microfluidics and interfacial rheology platform provides an effective method to understand deposition rate of the emulsions to the interfacial rheological properties.