Well Annular Velocity

Annular velocity is the speed of fluid moving up the annulus and it must be high enough to transport cuttings generated while drilling from the wellbore.

The annular velocity around drill pipe must be used to determine if it is good enough for hole cleaning because it is the lowest velocity in the wellbore. If the annular velocity around the drill pipe is good enough for hole cleaning purpose, it will definitely be sufficient for hole cleaning around drill collars, BHA and tool joints.

Reference: www.drillingformulas.com