Emulsion stabilization by means of combined surfactant multilayer (D-phase) and asphaltene particles

The emulsion stability of systems containing paraffinic, aromatic or naphthenic acid, water and heptane/toluene was investigated at different pH. High pH (around 11) gave rise to o/w emulsions with high stability. A decrease in pH reduced the emulsion stability significantly. In order to prepare stable w/o emulsions, D-phase samples were used. In addition to the multilayer stabilization, asphaltene nano-particles were mixed with the D-phase samples and used as stabilizers. It was shown that a combination of 60% asphaltene particles and 40% D-phase gave the most stable w/o-emulsions. All w/o-emulsion stabilities were evaluated by means of critical electric fields (E-crit). This investigation verifies the importance of D-phase stabilization in combination with asphaltene particles in systems with acidic heavy crude oil (including bitumen) and water. (C) 2003 Elsevier B.V. All rights reserved.