دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a tool above which joint on the middle of drill collar stem,its shape look like watermelon,its diameter is the same as the used hole,and it is also used to expand key slot in logging.

n: a device used to enlarge the size of an existing borehole. It has teeth arranged on its outside circumference to cut the formation as it rotates.

n: a special drilling tool that can enlarge an existing hole to the required diameter.

a larger device (usually of a fixed diameter) that enlarges the wellbore to a diameter equal to or less than the upper casing drift). Compare to an under-reamer or watermelon mill or string mill.

a mill that cuts to the side, opening up windows or cutting out restrictions.

a string mill, designed to enlarge the hole.