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.