EFFECT OF SODIUM-HYDROXIDE ON INTERFACIAL RHEOLOGICAL PROPERTIES OF OIL WATER SYSTEMS/

Interfacial rheological properties of a model crude oil/water system w ere studied in the presence of sodium hydroxide. The interfacial visco sity, the non-Newtonian flow behaviour and the activation energy of th e viscous flow were determined as a function of shear rate, alkali con centration and ageing time. The fundamental conclusion of the experime ntal results is that the interfacial viscosity drastically decreases i n the presence of alkaline materials and the change under favourable c onditions may exceed 3 or 4 orders of magnitude. Simultaneously, sodiu m hydroxide effectively suppresses the non-Newtonian flow behaviour of the interfacial layer. The effect of temperature and ageing time is m uch smaller in the presence of alkaline materials than in oil/dist. wa ter systems. The activation energy of the viscous flow found for oil/N aOH containing systems is between 5-10 kJ/mol which represents only on e tenth of the original values. The experimental observations are expl ained by simultaneous chemical processes taking place in the boundary layer. The present data may contribute to elucidate the formation, sta bility and break of alkali-containing oil/water emulsions and they pro vide additional information to better understanding of the displacemen t mechanism and formulation of the alkaline flooding being a prospectf ul chemical enhanced oil recovery method.