Phase segregation, shear thinning and rheological behavior of crude oil-in-water emulsions

This work reports an experimental investigation of the oil segregation effect during the rheological evaluation of concentrated oil-in-water (O/W) emulsions. The results demonstrated that alkyl alcohols can significantly affect the rheological behavior of O/W emulsions. The addition of n-octanol and n-decanol to the emulsifying agent formulation produces a critical shear rate, promotes a sharp break in the flow curves and leads to a sharp viscosity drop, which was attributed to wall depletion. This phenomenon is related to the displacement of the dispersed phase away from the solid-boundary, which generates a low-viscosity oil-depleted layer that acts as a lubricating layer. The incidence of slippage depends on the alkyl-chain length and the concentration of the alcohol. The lubrication layer will promote energy savings during emulsified oil pumping and result in significant economic benefits to the petroleum industry.