Non-monotonicity of the Contact Angle from NaCl and MgCl2 Concentrations in Two Petroleum Fluids on Atomistically Smooth Surfaces

Abstract

Wetting and alteration of wetting are among the most important material properties of fluid–fluid–substrate systems in biological and industrial systems. An important industrial application of wetting and wetting alteration is related to displacement of crude oil by water injection in porous media. Water injection in oil reservoirs has been used since the early periods of oil production. Recently, it has been discovered that the salt concentration in the injected water may have a significant effect on the oil recovery. The process is under active research for the need of an improved understanding. In this work, we investigate the governing elements of surface wettability with two different crude oils on two atomistically smooth surfaces (mica and quartz) and one smooth surface (calcite) as a function of the salt concentration (0–3 M) and type (mono- versus divalent). We investigate the change of wettability from NaCl and MgCl2 salts over a wide concentration for the first time. The measurements are based ...