1. n. [Drilling Fluids]

A chemical used in preparation and maintenance of an emulsion mud, which is a water mud containing dispersed oil (or a synthetic hydrocarbon). Numerous types of emulsifiers will disperse oil into water muds, including sulfonated hydrocarbons, ethyoxylated nonylphenols, alkali-metal fatty-acid soaps, lignosulfonate, lignite and lignin at high pH. Even clays, starch and carboxymethylcellulose aid emulsion mud stability.

Reference:
Rogers WF: "Oil-in-Water Emulsion Muds," in Composition and Properties of Oil Well Drilling Fluids, 3rd ed. Houston, Texas, USA: Gulf Publishing Company, 1963.

Synonyms: direct emulsifier

See: emulsion,  fatty-acid soap,  HLB number,  hydrophile-lipophile balance number,  interfacial tension,  oil-in-water emulsion,  soap,  synthetic-base fluid