1. n. [Drilling Fluids]

An oil mud designed and maintained with a minimum of colloid-sized solids, typically by omitting fatty-acid soap and lime, and minimizing organophilic clays and fluid-loss additives. Relaxed filtrate oil mud increases drilling rate. A disadvantage is that filter cake formed on sands is not tight, can quickly become very thick, and can cause pipe to stick by differential pressure.

Synonyms: low-colloid oil mud

See: differential pressure sticking,  filtration,  gilsonite,  oil-mud emulsifier,  organophilic clay