دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a mobile submersible drilling structure used in arctic areas. The rig is towed onto the drilling site and submerged during periods when the water is free of ice. All equipment below the waterline is surrounded by a caisson to protect it from damage by moving ice. The drilling deck has no square comers so that moving ice can better flow around it. See submersible drilling rig.