ИСТИНА

In recent years, the problem of production, transportation, and refining of heavy crude oil is becoming more and more relevant due to the depleted reserves of light crude oils. The main challenge of producing heavy oil is its high viscosity, which can reach up to 10 Pa•s. The general methods of reducing the viscosity of heavy crude oils include pipeline heating, deasphalting, mixing with lighter oil fractions and hydrocarbon solvents, but all of these methods have significant drawbacks. Current trend is emulsification of heavy oil in water for transportation through the existing pipelines with further separation of the emulsion into two distinct liquid phases at the outlet of the pipe. The purpose of most studies is to select emulsifiers to produce stable oil emulsions for their further transpiration. Generally, various surfactants are applied for stabilization, but great interest is the use of solid particles, which leads to the formation of Pickering emulsions characterized by greater stability than traditional oil-in-water systems. Clay, silica, and cellulose are usually used as such particles, but only cellulose has such advantages as biodegradability and renewability. To reduce the viscosity of heavy crude oil, it was decided to use nanocellulose (namely nanofibrillated cellulose due to the simplicity of its production), as well as sodium dodecyl sulfate (SDS) as an additional stabilizer. As a result, two series of emulsions containing either nanocellulose alone or in combination with SDS were obtained. When studying the morphology and rheology of samples, it turned out that the use of cellulose particles led to the formation of emulsions stable for a long time – at least six months. However, by using cellulose alone it is not possible to emulsify more than 40 vol.% of heavy crude oil, because at its higher concentrations inverse emulsions were formed. The introduction of SDS changes the situation and allows obtaining concentrated oil-in-water emulsions contained up to 80 vol. % of heavy crude oil; moreover, the resulting emulsions have lower yield stress and effective viscosity, while their application allows reducing energy costs for the transportation of heavy oil up to 13 times.