FLUID–FLUID AND SOLID–FLUID INTERFACIAL INTERACTIONS IN PETROLEUM RESERVOIRS

The distribution and flow behavior of crude oil, gas and brine in the porous rock medium of petroleum reservoirs are controlled largely by the interactions occurring at the interfaces within the various fluids and by the interactions between the fluids and the rock surface. With an objective to correlate the macroscopic multiphase flow behavior with fundamental interfacial interactions, the recent developments in the field of fluid–fluid and solid–fluid interactions and their applications in petroleum engineering are presented in this contribution. A computerized drop shape analysis technique and its application to the measurement of fluid–fluid interfacial tension at elevated pressures and temperatures are discussed. A recently developed technique that is capable of measuring dynamic (advancing and receding) contact angles at realistic conditions encountered in petroleum reservoirs is presented. Its effectiveness in making reproducible and rapid measurements relative to the conventional techniques is demonstrated with several reservoir case studies. Attempts are made to correlate the interfacial phenomena of adhesion and spreading in solid–liquid–liquid systems with dynamic contact angles as well as to extend the applicability of the critical surface tension concept from the conventional solid-liquid-vapor systems to the rock-oil-brine systems of interest in petroleum engineering. These interfacial concepts have been applied to the practical problems of asphaltene destabilization from crude oils and the effect of temperature on wettability alteration in heavy oil fields. A simple procedure is outlined to enable the estimation of interfacial adhesion forces and to demonstrate the significant role they play relative to the capillary forces in retaining the fluids within the porous rock medium.