Rheology of water-in-oil emulsions

Mauricio Barçante¹; Aurora P. Gramatges²; Mônica F. Naccache¹

¹ Pontifícia Universidade Católica do Rio de Janeiro - Departamento de Engenharia Mecânica; ² Pontifícia Universidade Católica do Rio de Janeiro - Departamento de Química

doi:10.20906/CPS/COB-2015-1253

Resumo

In this paper, we study the rheology of water-in-oil emulsions. These emulsions can be used as model fluids, which, with the addition of certain components (e.g. Cyclopentane), are able to form hydrates at atmospheric pressure. Hydrate formation is a major issue in the oil industry; therefore it is of great interest the study of the phenomena. The emulsions were prepared with water cut ranging from 20 to 40% and with two different oils: mineral oil Morlina S2 BL 10, reported viscosity of 10 mm²/s at 40 °C, and Morlina S2 B 150, reported viscosity of 150 mm²/s at 40 °C. In all cases, a surfactant blend, composed by Span 80 and Dioctyl sodium sulfosuccinate (AOT), was added, with two different concentrations: 1% and 5 wt% surfactant mixture in respect to the total emulsion weight. The best composition of the surfactant mixture was determined experimentally using the HLB system, with Span 80 fraction ranging from 100 to 75% and AOT fraction ranging from 0 to 25%, totaling 1 wt % surfactant mixture. The water-in-oil emulsions were stirred by hand and with a high-speed homogenizer. The rheology characterization was performed using Physica MCR 301 and MCR 501 rheometers. The results obtained show the stability of the water-in-oil emulsions through time, and the effect of water cut, oil viscosity and emulsifier concentration on the viscosity, storage and dissipation modulus. The analysis of the experimental data allows the correct choice of the model fluid to be used in future hydrate formation experiments.

Palavras-chave: Rheology; water-in-oil emulsion; hydrate