Definition - What does Weeper Sub mean?
A weeper sub is a piece of machinery that ejects fluid to keep the bore lubricated and clear of debris for subsequent drilling and reaming passes. The weeper sub is smaller in diameter than the bore and thus performs no cutting action.
Trenchlesspedia explains Weeper Sub
As the weeper sub passes through the borehole it ejects fluid from multiple nozzles to provide a wet environment for drilling or reaming and to wash the cuttings into the drilling fluid for returns. Weeper subs are sometimes used as a preventative measure when the drilling is done over long distances as well as to minimize the amount of drilling fluid needed at the drill bit, reducing the risk of frac-outs. Weeper subs can dramatically reduce the amount of torque needed during the reaming phase. This saves time, as the reamer will not have to be retracted due to high torque levels.