| swab [swäb] MINING ENGINEERING 1. A pistonlike device provided with a rubber cap ring that is used to clean out debris inside a borehole or casing. 2. The act of cleaning the inside of a tubular object with a swab. PETROLEUM ENGINEERING In petroleum drilling, to pull the drill string so rapidly that the drill mud is sucked up and overflows the collar of the borehole, thus leaving an undesirably empty borehole. |