Mast
Derrick and Mast are tall steel structures built to support the loads of the drilling tools which can weigh many tones. The tallest Derricks or Masts are about 200 ft where as the shortest is about 65 ft. The Mast structure is assembled in horizontal position and then raised to vertical as a single unit on a pivot point using the power of drawworks or hydraulic pistons. Whereas Derrick is assembled vertically by bolting one piece at a time.
Land Rig
A drilling rig that is located in the dry land is called land rig. Land rigs are of various kinds and vary in size depending on their load capacity and power to drill wells of certain depth. They can broadly be classified as light duty, medium duty, heavy duty and very heavy duty depending on their depth capacity to drill wells.
Kelly
Kelly is a steel tubular with hexagonal or square profile. It is connected between swivel and drill string. Kelly acts as a conduit for drilling fluid to be circulated from mud pump through drill string. Kelly passes through the kelly drive bushing with matching profile. Kelly drive bushing sits in the master bushing of the rotary table. The square or hexagonal profile of the kelly locks it in with the drive bushing and helps in transmitting rotary motion of rotary table to the drill string through kelly.
Jack Up Rig
A jack-up rig stands on legs that penetrate the seabed to provide stability. The rig’s deck is elevated above the water, providing safety from tidal motions and waves. Depending on the Rig capacities, they are primarily deployed for developmental or exploratory drilling in water depths up to 500 feet deep. Jack-up rigs usually have the mast on a cantilever with longitudinal and transverse motion.
Hoisting Equipment
A set of equipment is used for raising or lowering the drill string. The hoisting arrangement on a rig consists of Drawworks, Derrick or Mast, Crown Block, Travelling Block and Drilling Line.
Heavy Lift Vessel
Heavy lift vessel is a special purpose cargo ship that is used for moving offshore rigs long distance. The process is called 'dry tow'. Offshore Jack Up rigs are not self propelled units and need to be towed using tug bats from one location to another. If the two locations are too far from each other, this towing may take a very long time. To reduce the rig mobilization time, the rig is loaded on to a Heavy Lift Vessel. HLV can sail at a much faster speed thus reducing the rig mobilization time considerably.
Drawworks
Drawworks is a hoisting equipment on the drilling rig. Drilling line is wrapped around the drum of the drawworks. Rotating the drum makes it possible to move the travelling block up or down. Drawworks consists of a drum, cathead and brake bands.
Drawworks are rated in horse power depending on their capacity to lift the heaviest weight.
Drill Ship
A Drill Ship, also known as a Floater, is like a ship. It has a drilling rig and all associated equipment for drilling a well. It has a self-propulsion mechanism and can venture into ultra-deepwater to drill remote offshore locations. Drill ships are used for drilling wells in 1,000 feet to 10,000 feet water depths. Drillships use advanced dynamic positioning systems to maintain their position over the drilling location without anchors. These rigs are highly mobile and can be quickly deployed to different locations.
Drilling Rig
Drilling Rig is a structure and a package of various equipment used for drilling a well. Broad classification of a drilling rig is 'Land Rig' and 'Offshore Rig'. Offshore rigs are further classified based on their capacity to operate in certain water depths as 'Inland rig', 'Jack Up Rig', 'Drill Ship' and 'Semi-submersible rig'. Different parts of a drilling rig are derrick, substructure, engines, generator, drilling tubulars, hoisting equipment, pumps, steel tanks, solid control equipment etc.
Drilling Line
Drilling line is made up of steel wires and looks like wire rope. One end of the drilling line is clamped on the dead line anchor in the substructure of the rig. The drilling line passes over pulleys of travelling block and crown block and is wrapped around the drawworks drum. Its fast end is attached to the drawworks. Drilling line ranges from 7/8 to 2 inches in diameter depending on the load capacity of the rig.
Derrick
Derrick and Mast are tall steel structures built to support the loads of the drilling tools which can weigh many tones. The tallest Derricks or Masts are about 200 ft where as the shortest is about 65 ft. The Mast structure is assembled in horizontal position and then raised to vertical as a single unit on a pivot point using the power of drawworks or hydraulic pistons. Whereas Derrick is assembled vertically by bolting one piece at a time.
Crown Block
Crown Block is a mechanical arrangement of one or more pulleys on a common axel. It is mounted on the top of the derrick or mast. Drilling line passes over these pulleys and over the pulleys of the travelling block. This arrangement helps in hoisting or lowering the travelling block by winding or unwinding the drilling line of the Drawworks drum.
CIDS
CIDS is an acronym for "Concrete Inland Drilling System". It's a bottom supported MODU that is used for drilling wells in arctic conditions and is also known as "Arctic Submersible". CIDS or Arctic submersible rig is used for drilling arctic wells in shallow waters. In winter, ice blocks tend to flow with the ocean current and apply enough force to damage the jack up legs or barge hulls. Hence reinforced hulls called "Caisson" are used with arctic submersible rigs. CIDS is towed to location when the sea is ice free and Caissons are submerged into sea bottom to allow uninterrupted operations even with ice flow.
Caisson
Caisson is a reinforced hull that is used in Arctic Submersible rig. In winter, ice blocks tend to flow with the ocean current and apply enough force to damage the jack up legs or barge hulls. Hence reinforced hulls called "Caisson" are used with arctic submersible rigs. The rig is towed to location when the sea is ice free and Caissons are submerged into sea bottom to allow uninterrupted operations even with ice flow.
Burner Booms
Burner Booms or Flare Booms are arrangement of gas, oil & diesel lines with water spraying nozzles that is used on rigs / platforms for flaring oil and gas flowing from the the well.
Tree Saver Sub
Tree Saver Sub, also known as Wellhead Isolation Tool (WIT) is used for isolating and avoiding exposure of wellhead to the treating fluid and pressures. The tool is inserted through the tree & wellhead bore through the tubing hanger into the tubing. It has a seal that seals in the tubing avoiding the wellhead exposure to the treating fluid and pressures.
Wellhead Isolation Tool
Wellhead Isolation Tool (WIT) also known as Tree Saver Sub is used for isolating and avoiding exposure of wellhead to the treating fluid and pressures. The tool is inserted through the tree & wellhead bore through the tubing hanger into the tubing. It has a seal that seals in the tubing avoiding the wellhead exposure to the treating fluid and pressures.
Shear Sub
Shear Sub is a sub that is usually part of test tree assembly used for subsea wellheads. The string is spaced out to position the shear sub across share ram. In critical situation needing an emergency disconnect, shear ram will be activated to shear the DST string from shear sub. The sheared string can be retrieved with the help of an overshot and latch assembly later.