Experimental measurement and modeling of nanoparticle-stabilized emulsion rheological behavior

Emulsions have wide applications in various fields, especially in the petroleum industry. The rheological behavior of water-oil emulsions plays an important role in oil production, transportation and enhanced oil recovery methods Rheology of emulsions is affected by various factors such as dispersed phase fraction, droplet size distribution, a concentration of emulsifying agents, solid concentration, etc. Emulsion stabilization by solids, especially nanoparticles increased the stability, improved the rheological properties and consequently, incrementing the oil recovery from a subterranean formation. It can be pointed out that in very limited cases, the effects of nanoparticles on droplet size distribution of emulsion were investigated and models for prediction of the rheological behavior of solid-stabilized water-in-oil emulsions were not presented. The experiments were carried out using crude oil (petroleum) and fumed silica particle (namely Aerosil R972). In this communication, the effects of different parameters, including water volume fraction, nanoparticle concentration, shear rate, and angular frequency were investigated on the rheological behavior of water-in-oil emulsion. According to the results of rheological experiments, it can be pointed out that the influence of the nanoparticles on the viscosity of water-in-oil emulsions is mainly affected by the water/oil ratio, a number of nanoparticles, shear rate and angular frequency. Nanoparticle decreased water droplet diameter and increased the stability, elasticity and viscosity of the emulsion. In addition, for a better understanding of the effect of these parameters on the viscosity of the water-in-oil emulsions, apparent viscosity models were used. Based on the experimental data, a new equation was developed to estimate the relative viscosity of solid-free and solid-stabilized emulsions. The obtained results demonstrated that the proposed model has increased accuracy than previously published correlations. (C) 2017 Elsevier B.V. All rights reserved.