Process Engineering Term - K

KELLY - the heavy square or hexagonal steel member suspended from the swivel through the rotary table and connected to the topmost joint of drill pipe to turn the drill stem as the rotary table turns.

KELLY BLUSHING - a device fitted to the rotary table through which the kelly passes and the means by which the torque of the rotary table is transmitted to the kelly and to the drill stem. Also called the drive bushing.

KELLY BYPASS - a system of valves and piping that allows drilling fluid to be circulated without the use of the kelly.


KELLY COCK - a valve installed at one or both ends of the kelly. When a high-pressure backflow occurs inside the drill stem, the valve is closed to keep pressure off the swivel and rotary hose.

KELLY DRIVER - a device that fits inside the head and inside of which the kelly fits. The kelly driver rotates with the kelly.

KELLY SAVER SUB - a heavy and relatively short length of pipe that fits in the drill stem between the kelly and the drill pipe. The threads of the drill pipe mate with those of the sub, minimizing wear on the kelly.

KELLY SPINNER - a pneumatically operated device mounted on top of the kelly that, when actuated, causes the kelly to turn or spin.

KEYSEAT - 1. an undergauge channel or groove cut in the side of the borehole and parallel to the axis of the hole. A keyseat results from the rotation of pipe on a sharp bend in the hole. 2. a groove cut parallel to the axis in a shaft or a pulley bore.

KICK - an entry of water, gas, oil, or other formation fluid into the wellbore during drilling. It occurs because the pressure exerted by the column of drilling fluid is not great enough to overcome the pressure exerted by the fluids in the formation drilled. If prompt action is not taken to control the kick, or kill the well, a blowout may occur.

KICK FLUIDS - oil, gas, water, or any combination that enters the borehole from a permeable formation.

KICK OFF - 1. to bring a well into production; used most often when gas is injected into a gas lift well to start production. 2. in workover operations, to swab a well to restore it to production. 3. to deviate a wellbore from the vertical, as in directional drilling.

KICK OFF POINT (KOP) - the depth in a vertical hole at which a deviated or slant hole is started; used in directional drilling.

KILL - 1. in drilling, to control a kick by taking suitable preventive measures (for example, to shut in the well with the blowout preventers, circulate the kick out, and increase the weight of the drilling mud). 2. in production, to stop a well from producing oil and gas so that reconditioning of the well can proceed.