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.
invert-emulsion oil mud,