Oil platform

An oil platform, also called an oil rig, offshore platform, or oil production platform, is a large structure with facilities to extract and process petroleum and natural gas that lie in rock formations beneath the seabed. These structures are very important because they help us get the oil and gas we need for many things, like fuel for cars and energy for our homes.

Many oil platforms also have places for workers to live, though sometimes there is a separate living area connected by a bridge. Most oil platforms work in areas called the continental shelf, but they can also be in lakes, near the shore, or in inland seas. Depending on where they are, the platform can be fixed to the ocean floor, made as an artificial island, or even float.

Some oil platforms store the oil they process right on the platform itself. In other cases, wells far away under the sea, called subsea wells, are connected to the platform through special tubes called flow lines and umbilical connections.

Getting oil from under the sea can be tricky for the environment because of the oil and other materials used. This has led to many discussions, like the US offshore drilling debate. There are many kinds of oil platforms, including ones that sit on the sea floor, float on the water, or move with the waves. Some of these platforms can work in water that is about 280 feet deep.

History

Jan Józef Ignacy Łukasiewicz was a Polish inventor who built the world's first modern oil refinery in 1856.

Around 1891, the first oil wells were drilled from platforms built on piles in the fresh waters of Grand Lake St. Marys in Ohio. In 1896, the first oil wells in salt water were drilled from piers extending into the Santa Barbara Channel in California.

Other early drilling happened on Lake Erie in Canada and Caddo Lake in Louisiana in the 1910s. In the 1920s, drilling occurred from concrete platforms in Lake Maracaibo, Venezuela.

In 1937, a fixed platform was used to develop an oil field in 14 feet of water off the coast of Louisiana. In 1945, President Harry Truman extended American territory to the edge of its continental shelf.

In 1954, the first jackup oil rig was built and launched in 1955. When drilling moved into deeper waters, fixed platform rigs were built, followed by jack-up rigs and semi-submersible rigs. The first purpose-built semi-submersible was launched in 1963.

The Perdido hub in the Gulf of Mexico floats in over 2,400 meters of water and was built at a cost of $3 billion.

Main offshore basins

Some important places where oil and gas are found under the sea include:

• the North Sea
• the Gulf of Mexico (offshore Texas, Louisiana, Mississippi, Alabama and Florida)
• California (in the Los Angeles Basin and Santa Barbara Channel, part of the Ventura Basin)
• the Caspian Sea (especially some big fields near Azerbaijan)
• the Campos and Santos Basins off the coast of Brazil
• Newfoundland and Nova Scotia (Atlantic Canada)
• several fields off West Africa, south of Nigeria, and west of Angola
• offshore fields in South East Asia and Sakhalin, Russia
• big oil fields in the Persian Gulf like Safaniya, Manifa and Marjan which belong to Saudi Arabia
• fields in India (Mumbai High, K G Basin-East Coast Of India, Tapti Field, Gujarat, India)
• the Baltic Sea oil and gas fields
• the Taranaki Basin in New Zealand
• the Kara Sea north of Siberia
• the Arctic Ocean off the coasts of Alaska and Canada's Northwest Territories
• the offshore fields in the Adriatic Sea

Types

Larger lake- and sea-based offshore platforms and drilling rig for oil.

• 1) & 2) Conventional fixed platforms
• 3) Compliant tower
• 4) & 5) Vertically moored tension leg and mini-tension leg platform
• 6) Spar
• 7) & 8) Semi-submersibles
• 9) Floating production, storage, and offloading facility
• 10) Sub-sea completion and tie-back to host facility

Note that jack-up drilling rigs, drillships, and gravity-based structures are not pictured here.

Fixed platforms

Main article: Fixed platform

These platforms are built on concrete or steel legs, or both, anchored directly onto the seabed, supporting the deck with space for drilling rigs, production facilities and crew quarters. Such platforms are, by virtue of their immobility, designed for very long term use (for instance the Hibernia platform). Various types of structures are used: steel jacket, concrete caisson, floating steel, and even floating concrete. Steel jackets are structural sections made of tubular steel members, and are usually piled into the seabed.

Concrete caisson structures, pioneered by the Condeep concept, often have in-built oil storage in tanks below the sea surface. These tanks were often used as a flotation capability, allowing them to be built close to shore (Norwegian fjords and Scottish firths are popular because they are sheltered and deep enough) and then floated to their final position where they are sunk to the seabed. Fixed platforms are economically feasible for installation in water depths up to about 520 m (1,710 ft).

Compliant towers

Main article: Compliant tower

These platforms consist of slender, flexible towers and a pile foundation supporting a conventional deck for drilling and production operations. Compliant towers are designed to sustain significant lateral deflections and forces, and are typically used in water depths ranging from 370 to 910 metres (1,210 to 2,990 ft).

Tension-leg platform

Main article: Tension-leg platform

TLPs are floating platforms tethered to the seabed in a manner that eliminates most vertical movement of the structure. TLPs are used in water depths up to about 2,000 meters (6,600 feet). The "conventional" TLP is a 4-column design that looks similar to a semisubmersible. Proprietary versions include the Seastar and MOSES mini TLPs; they are relatively low cost, used in water depths between 180 and 1,300 metres (590 and 4,270 ft). Mini TLPs can also be used as utility, satellite or early production platforms for larger deepwater discoveries.

Spar platforms

Main article: Spar (platform)

Spars are moored to the seabed like TLPs, but whereas a TLP has vertical tension tethers, a spar has more conventional mooring lines. Spars have to-date been designed in three configurations: the "conventional" one-piece cylindrical hull; the "truss spar", in which the midsection is composed of truss elements connecting the upper buoyant hull (called a hard tank) with the bottom soft tank containing permanent ballast; and the "cell spar", which is built from multiple vertical cylinders. The spar has more inherent stability than a TLP since it has a large counterweight at the bottom and does not depend on the mooring to hold it upright. It also has the ability, by adjusting the mooring line tensions (using chain-jacks attached to the mooring lines), to move horizontally and to position itself over wells at some distance from the main platform location.

Eni's Devil's Tower located in 1,710 m (5,610 ft) of water in the Gulf of Mexico, was the world's deepest spar until 2010. The world's deepest platform as of 2011 was the Perdido spar in the Gulf of Mexico, floating in 2,438 metres of water. It is operated by Royal Dutch Shell.

The first truss spars were Kerr-McGee's Boomvang and Nansen. The first (and, as of 2010, only) cell spar is Kerr-McGee's Red Hawk.

Semi-submersible platform

Main article: Semi-submersible platform

These platforms have hulls (columns and pontoons) of sufficient buoyancy to cause the structure to float, but of weight sufficient to keep the structure upright. Semi-submersible platforms can be moved from place to place and can be ballasted up or down by altering the amount of flooding in buoyancy tanks. They are generally anchored by combinations of chain, wire rope or polyester rope, or both, during drilling and/or production operations, though they can also be kept in place by the use of dynamic positioning. Semi-submersibles can be used in water depths from 60 to 6,000 metres (200 to 20,000 ft).

Floating production systems

Main article: Floating production, storage and offloading

The main types of floating production systems are FPSO (floating production, storage, and offloading system). FPSOs consist of large monohull structures, generally (but not always) shipshaped, equipped with processing facilities. These platforms are moored to a location for extended periods, and do not actually drill for oil or gas. Some variants of these applications, called FSO (floating storage and offloading system) or FSU (floating storage unit), are used exclusively for storage purposes, and host very little process equipment. This is one of the best sources for having floating production.

The world's first floating liquefied natural gas (FLNG) facility is in production.

Jack-up drilling rigs

Main article: Jackup rig

Jack-up Mobile Drilling Units (or jack-ups), as the name suggests, are rigs that can be jacked up above the sea using legs that can be lowered, much like jacks. These MODUs (Mobile Offshore Drilling Units) are typically used in water depths up to 120 metres (390 ft), although some designs can go to 170 m (560 ft) depth. They are designed to move from place to place, and then anchor themselves by deploying their legs to the ocean bottom using a rack and pinion gear system on each leg.

Drillships

Main article: Drillship

A drillship is a maritime vessel that has been fitted with drilling apparatus. It is most often used for exploratory drilling of new oil or gas wells in deep water but can also be used for scientific drilling. Early versions were built on a modified tanker hull, but purpose-built designs are used today. Most drillships are outfitted with a dynamic positioning system to maintain position over the well. They can drill in water depths up to 3,700 m (12,100 ft).

Gravity-based structure

Main article: Gravity-based structure

A GBS can either be steel or concrete and is usually anchored directly onto the seabed. Steel GBS are predominantly used when there is no or limited availability of crane barges to install a conventional fixed offshore platform, for example in the Caspian Sea. There are several steel GBS's in the world today (e.g. offshore Turkmenistan Waters (Caspian Sea) and offshore New Zealand). Steel GBS do not usually provide hydrocarbon storage capability. It is mainly installed by pulling it off the yard, by either wet-tow or/and dry-tow, and self-installing by controlled ballasting of the compartments with sea water. To position the GBS during installation, the GBS may be connected to either a transportation barge or any other barge (provided it is large enough to support the GBS) using strand jacks. The jacks shall be released gradually whilst the GBS is ballasted to ensure that the GBS does not sway too much from target location.

Normally unmanned installations (NUI)

Main article: Normally unmanned installation

These installations, sometimes called toadstools, are small platforms, consisting of little more than a well bay, helipad and emergency shelter. They are designed to be operated remotely under normal conditions, only to be visited occasionally for routine maintenance or well work.

Conductor support systems

Main article: Conductor support systems

These installations, also known as satellite platforms, are small unmanned platforms consisting of little more than a well bay and a small process plant. They are designed to operate in conjunction with a static production platform which is connected to the platform by flow lines or by umbilical cable, or both.

Particularly large examples

Main article: List of tallest oil platforms

Deepest platforms by type

This is a list of oil wells based on the depth of the water where they were drilled. It does not include how deep they go underground, which in some cases is over 10,000 metres.

Other deep structures and fixed platforms, by water depth:

• Baldpate Platform, 502 m (1,647 ft)
• Pompano Platform, 393 m (1,289 ft)
• Benguela-Belize Lobito-Tomboco Platform, 390 m (1,280 ft)
• Gullfaks C Platform, 380 m (1,250 ft)
• Tombua Landana Platform, 366 m (1,201 ft)
• Harmony Platform, 366 m (1,201 ft)

Other metrics

The Hibernia platform in Canada is the world's heaviest offshore platform, located on the Jeanne d'Arc Basin, in the Atlantic Ocean off the coast of Newfoundland. This gravity base structure (GBS), which sits on the ocean floor, is 111 metres (364 ft) high and can store 1.3 million barrels (210,000 m³) of oil. The platform looks like a small concrete island with special edges to stay safe from icebergs. The GBS has tanks for storing oil and is filled with heavy materials to keep it in place, weighing 1.2 million tons.

Royal Dutch Shell created the first Floating Liquefied Natural Gas (FLNG) facility, located about 200 km off the coast of Western Australia. It is the largest floating offshore structure. It is about 488m long and 74m wide, and when fully loaded, it weighs around 600,000t.

History of deepest offshore oil wells

This is a list of oil wells based on the depth of the water where they were drilled. It does not include how deep they go underground, which in some cases is over 10,000 metres.

Maintenance and supply

An oil production platform can make its own energy and water. It has machines to generate electricity, clean seawater, and process oil and gas so it can be sent to land through pipes or to ships. Important parts of this process include the wellhead, production manifold, production separator, glycol for drying gas, gas compressors, water injection pumps, and equipment for measuring and moving oil and gas.

Big platforms sometimes need help from smaller support ships, like the British Iolair, when there is an emergency. Usually, supply ships called PSVs bring food and supplies to the platforms. Other ships, called AHTS vessels, can also bring supplies, move platforms to new places, and help in emergencies.

Crew

Oil platforms need many different types of workers to run smoothly. Some of the key roles include:

• The offshore installation manager, who makes important decisions during their shift.
• Operations Team Leader.
• Offshore Methods Engineer, who plans how the platform is set up.
• Offshore Operations Engineer, the main technical expert on the platform.
• Various operators for navigation, safety systems, and equipment like cranes.
• Technicians for maintaining machinery and checking tank levels.
• Catering staff for cooking and cleaning.
• Maintenance workers for electrical, mechanical, and instrument systems.
• A fully qualified medic.
• Radio operator for communications.
• Store Keeper for supplies.

If the platform is involved in drilling, there will also be a drill crew including roles like driller, derrickhand, and welder. Well services crews handle special tasks related to the wells.

Drawbacks

The nature of oil platforms—extracting oil and gas under difficult conditions—means there are risks. Accidents can happen, and sometimes they are serious.

Oil platforms can also affect the environment. In some places, old platforms are left in the water to become homes for sea creatures, which helps fish populations.

Effects on the environment

Offshore oil production can sometimes harm the environment. Oil spills from tankers or pipelines carrying oil from platforms to land can be a big problem. There is also water that comes up with the oil and gas, called produced water, which can be salty and may have harmful substances.

When hurricanes approach, oil platforms are shut down. In the Gulf of Mexico, more oil platforms can affect the weather. These platforms release gases that warm the water, which can help hurricanes form. Scientists are looking at new ways to reduce harmful gases from oil platforms, such as using heat to change natural gas into cleaner energy.

Repurposing

Old oil platforms that are not taken apart can be used for new jobs. Some are used to push CO₂ into rocks under the ocean. A few have even been changed to help launch rockets into space, and more are being made for big space launches.

In Saudi Arabia, people are planning to turn old oil rigs into a theme park.

Challenges

Working in the ocean to get oil and gas is harder than on land because the sea is tough and far away. Engineers have to create big, strong facilities to handle this. Some platforms float and stay in place with special ropes, which can be cheaper in deep water but make it trickier to drill and get the oil.

The ocean can make it much harder to get the oil out of the ground because of the water pressure and the energy needed to bring the oil up. Many modern oil operations happen far below the sea, with water cleaned and sent back into the ocean instead of brought up to the platform. This helps use even deeper water areas and deal with problems like moving ice.

Living and working on an oil platform is like being in a small town. Workers live there for weeks and need food, sleep, and support. In places like the North Sea, helicopters bring workers for two-week shifts. Supplies come by ship, and space is tight, so planning is very important. Many jobs are now done from land using video calls, which is easier for older workers and helps keep more people on shore. Using equipment deep under the sea also makes it easier to add more tools without needing more space on the platform.