ИСТИНА

The problem with production and transportation of heavy crude oils is their high viscosity, which can be reduced through deasphalting. However, the result is asphaltenes that have to be disposed of somehow. Asphaltenes are natural surfactants that are part of crude oils and stabilizing waterin-oil emulsion extracted during oil production. This hints at the opportunity for rational utilization of asphaltenes. This research examines the possibility of obtaining water-in-oil emulsions stabilized only with asphaltenes. Asphaltenes were dissolved in ester oil in which water or aqueous solutions of various substances were then emulsified. Several series of emulsions was prepared, differing in asphaltene concentration as well as disperse phase content and its type. In addition, solutions of asphaltenes were prepared in order to understand the role of viscosity of continuous phase in determination of emulsion rheology. For both asphaltene solutions and water-in-oil emulsions, their rheology was studied in detail: flow curves and frequency dependences of storage and loss moduli were obtained and analyzed. As it turns out, about 3% of asphaltenes is sufficient to make water-in-oil emulsions resistant to coalescence of droplets. However, water droplets form spatial agglomerates, which lead to the viscoelastic and viscoplatic behavior of these emulsions. An increase in the concentration of asphaltenes and/or the water phase result in an increase in the effective viscosity of the emulsions and their yield stress. At the same time, replacing water with aqueous solutions of various substances does not cause the emulsions to lose their resistance to coalescence and fundamental changes in their rheology. This opens up the possibility of using such emulsions as well as utilizing asphaltenes.