A jackup rig or a self-elevating unit is a type of mobile platform that consists of a buoyant

hull Hull may refer to: Structures * The hull of an armored fighting vehicle, housing the chassis * Fuselage, of an aircraft * Hull (botany), the outer covering of seeds * Hull (watercraft), the body or frame of a sea-going craft * Submarine hull Ma ...

fitted with a number of movable legs, capable of raising its hull over the surface of the sea. The buoyant hull enables transportation of the unit and all attached machinery to a desired location. Once on location the hull is raised to the required elevation above the sea surface supported by the sea bed. The legs of such units may be designed to penetrate the sea bed, may be fitted with enlarged sections or footings, or may be attached to a bottom mat. Generally jackup rigs are not self-propelled and rely on

tugs A tugboat or tug is a marine vessel that manoeuvres other vessels by pushing or pulling them, with direct contact or a tow line. These boats typically tug ships in circumstances where they cannot or should not move under their own power, such ...

heavy lift ship A heavy-lift ship is a ship, vessel designed to move very large loads that cannot be transported by normal ships. They are of two types: *''Semi-submersible'' ships that take on water ballast to allow the load—usually another vessel—to ...

s for transportation. Jackup platforms are almost exclusively used as exploratory oil and gas drilling platforms and as offshore and wind farm service platforms. Jackup rigs can either be triangular in shape with three legs or square in shape with four legs. Jackup platforms have been the most popular and numerous of various mobile types in existence. The total number of jackup drilling rigs in operation numbered about 540 at the end of 2013. The tallest jackup rig built to date is the Noble Lloyd Noble, completed in 2016 with legs tall.

Name

Jackup rigs are so named because they are self-elevating with three, four, six and even eight movable legs that can be extended (“jacked”) above or below the hull. Jackups are towed or moved under self propulsion to the site with the hull lowered to the water level, and the legs extended above the hull. The hull is actually a water-tight barge that floats on the water's surface. When the rig reaches the work site, the crew jacks the legs downward through the water and into the sea floor (or onto the sea floor with mat supported jackups). This anchors the rig and holds the hull well above the waves.

History

An early design was the DeLong platform, designed by Leon B. DeLong. In 1949 he started his own company, DeLong Engineering & Construction Company. In 1950 he constructed the ''DeLong Rig No. 1'' for Magnolia Petroleum, consisting of a barge with six legs. In 1953 DeLong entered into a

joint venture A joint venture (JV) is a business entity created by two or more parties, generally characterized by shared ownership, shared returns and risks, and shared governance. Companies typically pursue joint ventures for one of four reasons: to acce ...

with

McDermott McDermott or MacDermott is an Irish surname and the anglicised version of Mac Diarmada (also spelled Mac Diarmata), the surname of the ruling dynasty of Moylurg, a kingdom that existed in Connacht from the 10th to 16th centuries. The last ruling ...

, which built the ''DeLong-McDermott No.1'' in 1954 for

Humble Oil Humble Oil and Refining Co. was an American oil company founded in 1911 in Humble, Texas. In 1919, a 50% interest in Humble was acquired by the Standard Oil of New Jersey which acquired the rest of the company in September 1959. The Humble bran ...

. This was the first mobile offshore drilling platform. This barge had ten legs which had ''spud cans'' to prevent them from digging into the seabed too deep. When DeLong-McDermott was taken over by the

Southern Natural Gas Company Southern Natural Gas Company, headquartered in Birmingham, Alabama, is a natural gas pipeline company that was founded in 1928 and is currently a joint venture between Kinder Morgan and Southern Company. The company was a division of Birmingham-b ...

, which formed The Offshore Company, the platform was called ''Offshore No. 51''. In 1954, Zapata Offshore, owned by

George H. W. Bush George Herbert Walker BushBefore the outcome of the 2000 United States presidential election, he was usually referred to simply as "George Bush" but became more commonly known as "George H. W. Bush", "Bush Senior," "Bush 41," and even "Bush th ...

, ordered the ''Scorpion''. It was designed by

R. G. LeTourneau Robert Gilmour "R. G." LeTourneau (; November 30, 1888 – June 1, 1969), born in Richford, Vermont, was a prolific inventor of technologies related to earthmoving machinery, and founder of LeTourneau Technologies and LeTourneau University. H ...

and featured three electro-mechanically operated lattice type legs. Built on the shores of the

Mississippi River The Mississippi River is the main stem, primary river of the largest drainage basin in the United States. It is the second-longest river in the United States, behind only the Missouri River, Missouri. From its traditional source of Lake Ita ...

by the LeTourneau Company, it was launched in December 1955. The ''Scorpion'' was put into operation in May 1956 off Port Aransas, Texas. The second, also designed by LeTourneau, was called ''Vinegaroon''.

Operation

A jackup rig is a barge fitted with long support legs that can be raised or lowered. The jackup is maneuvered (self-propelled or by towing) into location with its legs up and the hull floating on the water. Upon arrival at the work location, the legs are jacked down onto the seafloor. Then "preloading" takes place, where the weight of the barge and additional ballast water are used to drive the legs securely into the sea bottom so they will not penetrate further while operations are carried out. After preloading, the jacking system is used to raise the entire barge above the water to a predetermined height or "air gap", so that wave, tidal and current loading acts only on the relatively slender legs and not on the barge hull. Modern jacking systems use a

rack and pinion rack and pinion is a type of linear actuator that comprises a circular gear (the '' pinion'') engaging a linear gear (the ''rack''). Together, they convert between rotational motion and linear motion: rotating the pinion causes the rack to be d ...

gear arrangement where the pinion gears are driven by hydraulic or electric motors and the rack is affixed to the legs. Jackup rigs can only be placed in relatively shallow waters, generally less than of water. However, a specialized class of jackup rigs known as premium or ultra-premium jackups are known to have operational capability in water depths ranging from .

Types

Mobile offshore Drilling Units (MODU)

This type of rig is commonly used in connection with oil and/or natural gas drilling. There are more jackup rigs in the worldwide offshore rig fleet than other type of mobile offshore

drilling rig A drilling rig is an integrated system that Drilling, drills wells, such as oil or water wells, or holes for piling and other construction purposes, into the earth's subsurface. Drilling rigs can be massive structures housing equipment used to ...

. Other types of offshore rigs include

semi-submersibles Semi-submersible may refer to a self-propelled vessel, such as: *Heavy-lift ship, which partially submerge to allow their cargo (another ship) to float into place for transport *Narco-submarine, some of which remained partially on the surface *S ...

(which float on pontoon-like structures) and

drillship A drillship is a merchant vessel designed for use in exploratory offshore drilling of new oil and gas wells or for scientific drilling purposes. In recent years the vessels have been used in deepwater and ultra-deepwater applications, equipped ...

s, which are ship-shaped vessels with rigs mounted in their center. These rigs drill through holes in the drillship hulls, known as moon pools.

Turbine Installation Vessel (TIV)

This type of rig is commonly used in connection with

offshore wind turbine Offshore may refer to: Science and technology * Offshore (hydrocarbons) * Offshore construction, construction out at sea * Offshore drilling, discovery and development of oil and gas resources which lie underwater through drilling a well * Of ...

installation.

Barges

''Jackup rigs'' can also refer to specialized

barge A barge is typically a flat-bottomed boat, flat-bottomed vessel which does not have its own means of mechanical propulsion. Original use was on inland waterways, while modern use is on both inland and ocean, marine water environments. The firs ...

s that are similar to an oil and gas platform but are used as a base for servicing other structures such as offshore wind turbines, long bridges, and drilling platforms. File:NewCarissa dismantled by KarlissaA and B July 2008 panorama merge.jpg, Jackup barges being used to dismantle a ship that was wrecked at sea. File:Scroby Sands Wind Farm 2981489897.jpg, Jackup barge servicing a

Vestas Vestas Wind Systems A/S is a Danish manufacturer, seller, installer, and servicer of wind turbines that was founded in 1945. The company operates manufacturing plants in Denmark, Germany, the Netherlands, Taiwan, India, Italy, Romania, the Un ...

V80-2 MW

wind turbine A wind turbine is a device that wind power, converts the kinetic energy of wind into electrical energy. , hundreds of thousands of list of most powerful wind turbines, large turbines, in installations known as wind farms, were generating over ...

of the Scribe Sands wind farm. File:Bailey bridge barge.webp, 3D design of

PLA Navy landing barges The ''Shuiqiao'' (水桥 ― water bridge) class of amphibious assault barges have been built for China's People's Liberation Army Navy by COMEC. A set of three barges is used to form an extended causeway and pier from deep water to land. Two s ...

References

{{reflist Oil platforms Ship types