The conclusions from this study are given in Section 5.Ģ. The proposed correlation is compared with literature correlations in Section 4. The present experimental procedure is described in Section 3.
The models for suspension viscosity as a function of temperature and dispersed phase concentration are described in Section 2. The main objective of this study is to present a method to estimate accurately the variation of kinematic viscosity of W/O emulsions with temperature and water volume fraction. From this data, the rheological behavior of water-in-oil emulsions can be studied. With the objective of evaluating correlations of the viscosity with the temperature and volume fraction of dispersed phase, the effective viscosities of several synthetic W/O emulsions are measured using different crude oils, varying shear rate, temperature and volume fraction of dispersed phase. Very few experimental data are available in the literature and there is only one correlation for describing the variation of the viscosity of water-in-oil emulsions with temperature and volume fractions (Ronningsen, 1995). There are several correlations between the relative viscosity (l r) of the W/O emulsions and their water volume content and oil phase density (Pal, 1998, 2001). It is known that the viscosity of a W/O emulsions is strongly augmented by increasing its water volume ratio and by decreasing the temperature (Krieger and Dougherty, 1959). In general, these W/O emulsions form spontaneously due to the presence of natural surfactants existing in the oil phase and are stable. Journal of Petroleum Science and Engineering 48 (2005) 169–184 Sometimes, the water is added to oil phase on purpose in order to produce stable W/O emulsions of fuel oils with improved combustion characteristics. In these cases, the water content rarely attains high percentage values. The W/O emulsions can also form accidentally during the refining operations, storage and distribution. doi:10.1016/j.petrol.2005.06.014Ĭrude oil production and the water content can be as high as 60% in volume. They form naturally during * Corresponding author. Introduction Water-in-oil (W/O) emulsions are very common in the petroleum industry. Keywords: Viscosity Rheology Water-in-oil emulsions Data correlationġ. The proposed equation gives good correlation between the measured viscosities of water-in-oil emulsions as a function of temperature and the volume fraction of water. The ASTM equation, method D-341, for describing viscosity as a function of temperature is extended to include the variation of dispersed phase volume fraction. Using six different crude oils, the effective viscosities of several synthetic water-in-oil emulsions are measured at atmospheric pressure using a dynamic viscosimeter for different shear rates, temperatures and volume fractions of the dispersed phase. The effective viscosity of water-in-oil emulsions depends mainly on the volume fraction of dispersed phase and temperature, along with several minor effects, such as shear rate, average droplet size, droplet size distribution, viscosity and density of oil. 68452, CEP 21949-900, Rio de Janeiro, Brazil Received 28 October 2004 received in revised form 7 June 2005 accepted 25 June 2005Ībstract Water-in-oil emulsions are important in the petroleum industry in production operations, where the water content of the emulsion can be as high as 60% in volume, also in petroleum refining operations where generally the water content is low. Petroleo Brasileiro S.A., Rua General Canabarro, 500, Maracana˜, Rio, CEP 2057-900, Brazil b Petroleo Brasileiro S.A., Cenpes, Cidade Universita´ria, Brazil c LATCA–Laborato´rio de Termodinaˆmica e Cine´tica Aplicada–Escola de Quı´mica, Departamento de Engenharia Quı´mica, Universidade Federal do Rio de Janeiro, UFRJ, Cidade Universita´ria, C.P. Oliveira b, Jorge Navaes Caldas a, Krishnaswamy Rajagopal c,* a Journal of Petroleum Science and Engineering 48 (2005) 169 – 184 Viscosity of water-in-oil emulsions: Variation with temperature and water volume fraction Marco A.
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