1. n. [Drilling Fluids]
A chemical used to break emulsions (that is, to separate the two phases). The type of demulsifier selected depends on the type of emulsion, either oil-in-water or water-in-oil. Demulsifiers are used in the chemical analysis of oil and synthetic muds and to treat produced hydrocarbons.
See: emulsion, hydrocarbon, oil mud, oil-in-water emulsion, synthetic-base mud, water-in-oil emulsion