Emulsions of water in asphaltene-containing oils 1. Droplet size distribution and emulsification rates

Abstract

Emulsions of simulated sea water in three crude oils and in a model oil consisting of n-heptane, m-xylene and asphaltenes were examined by optical microscopy to obtain droplet diameters which were found to fit the log-normal distribution function. The rate of formation of interfacial area with respect to stirring time in the crude oil emulsions was first order. Values of S m, the limiting area stabilised, increased with increasing asphaltene content while k, the rate constant, decreased. Addition of surfactants to either the oil phase or to the aqueous phase before mixing slowed the formation of Kuwait crude emulsions and increased S m. This effect could result from a decrease in the oil/water interfacial tension causing a change in the equilibrium contact angle between asphaltene particles and the interface.