دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a roller cone bit that is specially designed for air or gas drilling. It is very similar to a regular bit, but features screens over the bearings to protect them from clogging with cuttings and thicker hardfacing on the shirttail to protect them from abrasive, high-velocity air or gas drilling fluid.

n: on a roller cone bit, a coneshaped steel device from which the manufacturer either mills or forges steel teeth, or into which the manufacturer inserts tungsten carbide buttons. Most roller cone bits have three cones, which roll, or rotate, on bearings as the bit rotates. As the cones roll over the formation, the cutters on the cone scrape or gouge the formation to remove the rock.

n: a drilling bit with tungsten carbide inserts on the cones that resemble plugs or buttons. See roller cone bit.

nn: The cone bit which is installed with obtuse tungsten carbide insert.

n: a conical-shaped metal device into which cutting teeth are formed or mounted on a roller cone bit. See roller cone bit.

n: See bit cone.

n: a roller bit in which the cutters are conical. See bit.

n: See roller cone bit.

n: the amount by which lines drawn through the centre of each cone of a bit fail to meet in the centre of the bit. For example, in a roller cone bit with three cones, three lines can be drawn through the centre of each cone and extended to the centre of the bit If these cone centrelines do not meet in the bits centre, the coles are said to be offset In general, bits designed for drilling soft formations have more offset than cones for hard formations, because offset affects the angle at which the bit teeth contact the formation. Since soft formations require a gouging and scraping action by bit teeth, high offset achieves the necessary action.

n: Refers to the situation that the axiss of cone dont convergence at the centre line of cone bit.

n: See roller cone bit.

n: locking of a cone on a roller cone bit so that it will not turn when the bit is rotating. Cone skidding results in the flattening of the surface of the cone in contact with the bottom of the hole.

n: The phenomenon that the cone of bit is freezed in.

n: a drilling tool that, when placed in the drill stem just above a roller cone bit, delivers high-frequency percussion blows to the rotating bit. Hammer drilling combines the basic features of rotary and cable-tool drilling (i.e.. bit rotation and percussion).

n: a kind of satellite drilling tool which is installed in bottom of the pipe and the top of cone bit and which can create high frequency impact effect

n: see tungsten carbide bit.

n: a type of roller cone bit in which the cutting structure consists of the specially designed tungsten carbide cutter set into the cones.