دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a bottomhole assembly composed of a bit and several large-diameter drill collars and stabilisers placed to allow the bottom drill collar to bend toward the vertical. The assembly works on the principle of the pendulum effect and is used to decrease drift angle. See pendulum effect.

n: a BHA (q.v.) that is designed to drop angle by allowing the drill collars towards the low side of the hole.