دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: any of a variety of drilling bits that have no moving parts. As they are rotated on bottom, elements of the bit make hole by being pressed into the formation and being dragged across it. See fishtail bit.

n: A drilling bit that has no cones or bearings but consists of a single unit with a cutting structure and circulation passageways. The fishtail bit was an early example of a drag bit, but is no longer in common use. Diamond bits are also drag bits.

n: a drilling bit with cutting edges of hard alloys. Developed about 1900, and first used with the rotary system of drilling, it is still useful . drilling very soft formations. Also called drag bit

n: the balde bit whose wings shape seem like fish tail

a drag bit with no moving parts, rotated like a conventional metal drilling bit.

n: a drag bit with four blades. See bit. fishtail bit.

n: drag bit with blade which is used to break formation with four.