Picture of a Drill Rig - Definitions

Blowout prevention equipment: The assembly of well control equipment including preventers, spools, valves, and nipples connected to the top of the wellhead to prevent the uncontrolled escape of oil or gas during drilling operations.

Casing: Havy steel pipe that lines the walls of the hole to prevent the wall of the hole from caving in, to prevent movement of fluids from one formation to another, and to aid in well control.

Cement: Used to fill the space between the wall of the hole and the casing. Together with the casing, this prevents caving of the hole, prevents movement of fluids (water, oil, or gas) between rock layers, confines production to the well bore, and provides a means to controls pressure.

Crown block: An assembly of sheaves or pulleys mounted on beams at the top of the derrick. The drilling line is run over the sheaves down to the draw works.

Derrick: A large load-bearing structure, usually bolted construction of metal beams. In drilling, the standard derrick has four legs standing at the corners of the substructure and reaching to the crown block. The substructure is an assembly of heavy beams used to elevate the derrick and provide space underneath to install the blowout preventer, casing head, and other equipment.

Draw works: The hoisting mechanism on a drilling rig. It is a large winch that spools off or takes in the drilling cable or line, which raises or lowers the drill pipe and drill bit.

Drill bit: The cutting or boring element used in drilling oil and gas wells. Most bits used in rotary drilling are roller-cone bits. The bit consists of the cutting elements and the circulating element. The circulating element permits the passage of drilling fluid and uses the hydraulic force of the drilling mud to improve drilling rates.

Drill pipe: The heavy seamless steel tubing used to rotate the drill bit and circulate the drilling mud. Each section of drill pipe is about 30 feet long and is fastened together by means of threaded tool joints.

Engines: Any of various types of power units such as a hydraulic, internal combustion, air, or electric motor that develops energy or imparts rotary motion that can be used to power other machines.

Kelly: The heavy square or hexagonal steel member suspended from the swivel through the rotary table and connected to the topmost section of drill pipe to turn the drill pipe as the rotary table turns.

Mud pit: Originally, an open pit dug in the ground to hold drilling mud or waste materials such as well bore cuttings or mud sediments. Steel tanks are much more commonly used for these purposes now, but they are still usually referred to as pits.

Mud pump: A large, high-pressure reciprocating pump used to circulate the mud on a drilling rig.

Rotary drive: The machine used to impart rotational power to the drill string while permitting vertical movement of the pipe for drilling. Modern rotary machines have a special component, the rotary or master bushing, to turn the kelly bushing, which permits up and down movement of the kelly while the drill pipe is turning.

Standpipe: A rigid metal conduit that provides the pathway for drilling mud to travel about one-third of the way up the derrick, where it connects to a flexible hose (kelly hose), which the connects to the swivel.

Swivel: A mechanical device that suspends the weight of the drill pipe, provides for the rotation of the drill pipe beneath it while keeping the upper portion stationary, and permits the flow of drilling mud from the standpipe without leaking.

Traveling block: An arrangement of pulleys or sheaves which moves up or down in the derrick through which the drilling cable is strung to the rotary drive.