Effect of sodium hydroxide on interfacial rheological properties of oil-water systems

Interfacial rheological properties of a model crude oil-water system were s tudied in the presence of sodium hydroxide. The interfacial viscosity, the non-Newtonian flow behaviour and the activation energy of viscous flow were determined as a function of shear rate, alkali concentration and aging tim e. The fundamental conclusion of the experimental results is that the inter facial viscosity drastically decreases in the presence of sodium hydroxide and the change under favorable conditions may exceed three or four orders o f magnitude. Simultaneously, the sodium hydroxide effectively suppresses th e non-Newtonian flow behaviour of the interfacial layer. The experimental o bservations are explained by simultaneous chemical processes taking place i n the boundary layer. The present data may contribute to elucidate the form ation, stability and break of alkali-containing oil-water emulsions and the y provide additional information to better understanding of the displacemen t mechanism and formulation of the alkaline flooding being as a prospectful chemical enhanced oil recovery method. (C) 1999 Elsevier Science B.V. All rights reserved.