Studies on water-in-oil products from crude oils and petroleum products

► We find that oils and petroleum will either take up water or not – to any extent. ► Oils that take up water do as three types; stable, meso-stable or entrained water. ► Stable emulsions have lifetimes of weeks to months and meso-stable up to a week. ► Entrained water types retain water by viscosity and lose water slowly after formation. ► The distinct water-containing types are correlated to bulk oil composition. Water-in-oil mixtures such as emulsions, often form and complicate oil spill countermeasures. The formation of water-in-oil mixtures was studied using more than 300 crude oils and petroleum products. Water-in-oil types were characterized by resolution of water at 1 and 7days, and some after 1year. Rheology measurements were carried out at the same intervals. The objective of this laboratory study was to characterize the formed water-in-oil products and relate these properties to starting oil properties. Analysis of the starting oil properties of these water-in-oil types shows that the existence of each type relates to the starting oil viscosity and its asphaltene and resin contents. This confirms that water-in-oil emulsification is a result of physical stabilization by oil viscosity and chemical stabilization by asphaltenes and resins. This stabilization is illustrated using simple graphical techniques. Four water-in-oil types exist: stable, unstable, meso-stable and entrained. Each of these has distinct physical properties.