Experimental and modeling studies on the viscosity of (diesel oil + water + anti-agglomerant) system at high pressures

• Viscosity of water-in-oil emulsions containing hydrate anti-agglomerants was measured.
• Relative viscosity of emulsion increases exponentially with decreasing of temperature.
• Relative viscosity of emulsion increases almost linearly with increasing of pressure.
• A viscosity correlation involved temperature, pressure, droplet size, and water cut was built.

The viscosities of water-in-oil emulsions containing two kinds of hydrate anti-agglomerants were experimentally measured at three water cuts (10, 20, and 30 vol%) under (275.2–293.2) K and pressures up to 20 MPa. The experimental results indicate that the relative viscosity of the emulsion shows an exponential growth to some extent with the decrease of temperature for a given pressure and water cut, but increases almost linearly with the increase of pressure for all isotherms investigated. It also increases with increasing water volume fraction. The mean droplet sizes of water-in-oil emulsions show an exponential growth with the increase of temperature for a given water cut. An improved viscosity correlation as a function of temperature, pressure, mean droplet size, and water cut was proposed. The average relative deviations of the calculated results from the viscosity correlation were 4.4% and 4.0% for water-in-oil emulsions containing two kinds of anti-agglomerants, respectively.