دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a small-diameter pipe or scabbard under the derrick floor in which a jiont of drill pipe is temporarily stored for later connection to the drill string.

a hole in the rig floor designed to hold a joint of pipe. The rat hole (a term also used for the borehole below the pay zone) holds the Kelly when it has to be disconnected.