1. n. [Drilling Fluids]

A chemical additive that creates an emulsion, a dispersion of one immiscible liquid into another, by reducing the interfacial tension between the two liquids to achieve stability.

Two emulsion types are used as muds:

• oil-in-water (or direct) emulsion, known as an "emulsion mud"
• water-in-oil (or invert) emulsion, known as an "invert-emulsion mud."

The former is classified as a water-base mud, and the latter as an oil-base mud.

Antonyms: demulsifier

See: coalescence,  creaming,  dispersant,  fatty acid,  fatty-acid soap,  interfacial tension,  invert-emulsion oil mud,  oil-mud emulsifier,  surface tension,  surfactant,  water-mud emulsifier