Morphology and Rheology of Heavy Crude Oil/Water Emulsions Stabilized by Microfibrillated Cellulose
Svetlana N. Gorbacheva, Sergey O. Ilyin
Abstract
The application of microfibrillated cellulose and sodium dodecyl sulfate (SDS) to obtain heavy crude oil emulsions in water has been considered. First of all, the optimal concentration of cellulose in its aqueous dispersion was studied. A rheological study showed that cellulose dispersions exhibit viscoplasticity when the content of microfibrils is 0.3% or higher. At the same time, these dispersions are capable of flowing under high shear stresses only when the cellulose content does not exceed 1%. The use of 1% cellulose dispersion allows for obtaining stable direct emulsions with oil content up to 30 vol %, while a higher oil concentration leads to the phase inversion with a transition from viscoplasticity of oil-in-water emulsions to almost Newtonian behavior of water-in-oil systems. In the case of using SDS, cellulose-free oil emulsions are not resistant to creaming even in a concentrated aqueous SDS solution. The combined application of cellulose microfibrils (1%) and SDS (5%) helps to obtain stable highly concentrated direct emulsions containing up to 80 vol % heavy crude oil. Calculations have shown that the use of 50 vol % emulsion is optimal and allows for reducing energy consumption for transportation of heavy crude oil by 13 times.