دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

v: to lower the drill stem rapidly a few feet into the hole and then stop it suddenly with the drawworks brake. A surge of pressure in the mud in the drill stem and annular space results and may help to flush out debris accumulated in or on die pipe. The pressure surge may break down a formation, however, causing lost circulation, or may damage the bit if it is near the bottom.

v: Landing the drill string speedily and then braking. This operation can produce stiring pressure to clean the cutting laying up in the drill pipe. But this pressure may lead to formation fracturing or circulation loss.