Apparent viscosity prediction of non-Newtonian water-in-crude oil emulsions

A new viscosity model for predicting non-Newtonian emulsions is proposed. Empirical and theoretical relationships are developed to describe the apparent viscosity vs. water cut behavior of the water-in-crude oil emulsions. Based on Pal and Rhodes model [Pal, R., Rhodes, E., 1989. Viscosity/concentration relationships for emulsions. J. Rheol. 33 (7), 1021–1045] and experimental data, an improved Pal and Rhodes model including the effective water cut theory and the relationship between non-Newtonian behavior and water cut is developed. In the new model, the effective water cut factor Ke has been divided into two factors, Ke(γ) and Ke(ϕ), to express the influence of the shear rate and the water cut on viscosity, respectively; and the factor Ke(ϕ) is found to be power function of water cut. The proposed model can predict relative (apparent) viscosity of water-in-crude oil emulsions over the range of the maximum and minimum water cut. Validated with experimental data, 7 (1 heavy oil and 6 waxy oils) sets of water-in-crude oil emulsions in different water cut and shear rate, the result shows that the average deviation of improved model (8.9%) is smaller than the original model (27.1%).