دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a walled round hole or well in the hull of a drill ship, ship-shape barge, or semisubmersible drilling rig (usually in the centre) through which the drilling assembly and other assemblies pass while a well is being drilled, completed, or abandoned.

an open shaft in a deep-sea drilling vessel, usually located in the center of the hull, through which the drilling takes place.