Determination of dynamic contact angles in solid-liquid-liquid systems using the Wilhelmy plate apparatus

The purpose of this work was to carry out a systematic study of the effects of brine composition and rock mineralogy on rock-oil-brine interactions taking place in petroleum reservoirs. These terms are generally lumped into a single term called wettability in petroleum engineering. The extent of wetting of the rock surface by water or oil depends on the dynamic contact angles measured in such a mode as to enable movements of the three-phase contact line. The Wilhelmy plate technique has been used in this study to measure adhesion tension (which is the product of interfacial tension and cosine of the contact angle) at the solid-liquid interface. The water-advancing and water-receding contact angles have been calculated from the adhesion tensions by making independent measurements of the liquid-liquid interfacial tensions using a du Nouy ring tensiometer. The water-advancing and receding angles have been measured in this study for pure hydrocarbons against synthetic brines of different concentrations. Polished surfaces of glass slides and dolomite have been used to simulate the reservoir rock surfaces. A nonionic surfactant (ethoxy alcohol), which is being used in Yates reservoir in West Texas for enhancing oil recovery, was used to quantify its wettability effects. The results of the systematic experimental investigation of the effects of practical variables on wettability are presented. It is found that interactions between surface-active agents at the interface of two liquids have an effect on wettability alteration. The composition and concentrations of different organic and inorganic chemical species have a major effect in making a reservoir oil-wet or water-wet.