1. n. [Drilling Fluids]

The elapsed time for mud to circulate from the suction pit, down the wellbore and back to surface. Circulation time allows the mud engineer to catch "in" and "out" samples that accurately represent the same element of mud in a circulating system. Circulation time is calculated from the estimated hole volume and pump rate and can be checked by using tracers such as carbide or rice granules.

Synonyms: cycle time

See: lag time,  mud engineer,  mud tracer,  mud-in sample,  mud-out sample,  suction pit