1. n. [Enhanced Oil Recovery, Drilling Fluids]

A chemical that preferentially adsorbs at an interface, lowering the surface tension or interfacial tension between fluids or between a fluid and a solid. This term encompasses a multitude of materials that function as emulsifiers, dispersants, oil-wetters, water-wetters, foamers and defoamers. The type of surfactant behavior depends on the structural groups on the molecule (or mixture of molecules). Hydrophile-lipophile balance (HLB) number helps define the function that a molecular group will perform.

See: amides,  amines,  breaker,  cloud point,  defoamer,  dispersant,  drilling detergent,  emulsifier,  foaming agent,  gas hydrate,  HLB number,  hydrophile-lipophile balance number,  hydrophilic,  interfacial tension,  lyophilic,  lyophobic,  quaternary amine,  spotting fluid,  surface tension