Oil and gas platforms or offshore drilling rigs are constructed for extracting, storing and processing petroleum and natural gas lying beneath the ocean floor. These platforms are of different types, such as fixed, spar type, semi-submersible, etc.

The largest number of oil rigs are located in the Gulf Of Mexico and owned by the US government, followed by the Persian Gulf and the Far East.

With advancements in the energy sector and maritime engineering, such structures have been built to withstand the toughest conditions while reducing their environmental impact. Endowed with the latest technologies to maximise productivity, these are pivotal for meeting the global oil demands.

Most platforms are equipped with basic amenities as workers live on these structures to oversee the operations. Accidents in these facilities can be disastrous for marine and human life; hence, they have world-class security systems for detecting any potential leakages.

Described below are the five biggest oil platforms in the world.

Berkut oil rig

Berkut is the biggest oil and gas platform in the world, situated near the Russian coastline facing the Pacific Ocean, near the island of Sakhalin, close to the Japanese mainland. It is truly an engineering marvel, weighing about 200,000 tonnes and 35 m deep from the seafloor. It is estimated that the platform’s maximum oil extraction capacity is 4.5 million tonnes annually.

Constructed to tap the expansive Arkutun-Dagi oil reserves spanning more than 50 kilometres from the coast of Russia into the Okhotsk Sea, this platform was one of the most expensive and challenging projects undertaken by a consortium of major oil companies from the US, Japan, India and Russia who spent 12 billion dollars on Berkut or Golden Eagle. The name of this platform underlines its economic significance for Russia, and the government has estimated the revenue earnings from the rig to be more than 9 billion dollars in the next ten years.

Before the platform was built, 27 wells were dug to extract oil, which would be transported to the Chaivo oil refining plant.

Lastly, it would be sent to the oil terminal at the Dekastri port through a pipeline for export worldwide. The main structure, the platform, rests on four strong pillars rising above the sea. It was designed by Russian Engineers and built in the port of Vostochny in the eastern Russian region, utilising 53,000 m3 and 26,000 tonnes of concrete and steel. One of the levels was built in Daewoo Shipbuilding and Marine Engineering yard in South Korea by 4500 men and brought 2600 km offshore to the oil field using gigantic lifting equipment.

Located in a harsh zone with floating arctic icebergs, the platform has been designed to operate even in extremely low temperatures and comprises a unique electricity system to keep functioning during the freezing Russian winters. It can resist ice caps as thick as 2 m due to its novel concrete lining, which would also protect the platform from huge waves as high as 19 m and can also withstand the highest magnitude earthquakes.

The platform measures 105 m lengthwise 61 m breadthwise, while its height is 145 m. It weighs 42,000 tonnes and has many levels installed with modules, emergency equipment, a security system, a rig, a processing unit, a living area, a helipad, and other facilities. It runs on four gas turbines and three generators to offer optimum efficiency.

Perdido

The Perdido oil and gas platform is the second biggest in the world located near the US Gulf of Mexico. It became operational in 2010 and is operated by one of the biggest oil companies, Shell Oil. The project was quite challenging in terms of geographical restraints since the gulf is ridden with typhoons and hurricanes.

Hence the platform had to be durable to withstand hurricanes and extremely low temperatures. The water depth of the structure from the seabed is around 8000 feet and extracts oil and gas from the Great White, Tobago and Silverfield; three low-pressure oil reserves of the region. The platform extracts 100,000 barrels of oil and 200 million m3 of gas every day.

Featuring a unique classic spar design, it was constructed in Finland by the construction company Technip. The spar measures 170 m and its hull was as tall as the Eiffel tower and as heavy as 11000 vehicles. Around 12,500 experts were involved in the designing, construction and assemblage of one of the world’s deepest oil production facilities, whose platform weighs 53,000 tonnes and whose decks are as expansive as 2 soccer grounds.

Numerous barges and carriers transported the spar and platform from Finland to the Gulf of Mexico. Mooring it correctly was a cumbersome task that took more than 22 hours, with the team operating despite a fast-approaching hurricane Gustav. The structure withstood the strong hurricane due to its internal ballast system, which floods the tanks and keeps the platform stable while reducing movement with the high waves and strong winds and minimising the pressure on the pipes carrying oil and gas to the platform from the seafloor.

The platform comprises three levels comprising a processing plant, living spaces for about 175 workers and a drilling rig. It also has a water purification and desalination system, a restaurant, gyms, TV rooms, emergency equipment and an internet connection.

It has a highly advanced security system and rescue boats capable of accommodating 25 workers in case of an accident. The platform has a helipad that is big enough to land 2 helicopters capable of carrying 23 workers each in case of a hurricane.

Petronius

The Petronius oil platform is situated in the Gulf of Mexico, close to New Orleans in the US. The construction of this fixed, compliant tower-type rig began in 1997 and ended in 2000. Lying at an underwater depth of more than 530 m, it was envisaged to exploit the Petronius oil field found in the 1990s and named after the famous Roman author serving in the court of Roman Emperor Nero.

The rig was once the highest independent structure before being overtaken by the Burj Khalifa in Dubai. Its construction was especially ridden with many technical problems since it was undertaken in the 90s and cost around 500 million dollars. It was constructed by Mc Dermott International Limited, which was also responsible for its assemblage, while the engineering contract was given to WH Linder and Associates.

Before its construction, 16 oil wells were drilled and connected with oil pipelines. Usually, the platforms are made to be stable to resist movement due to waves or winds, but this structure sways with the tidal currents however it has a strong foundation achieved due to numerous pilings extending from the upper structure to the seabed. It is 1869 feet high and weighs 41,000 tonnes.

It has two levels weighing 8000 tonnes, comprising essential equipment and living rooms for workers, pipelines, operations room and a drilling rig along with 21 slots for oil wells. The facility extracts more than 60,000 barrels and 3,100,000 m3 of oil and natural gas every day.

One of its modules weighing around 4000 tonnes was fixed in 1998 however the comparatively lighter module weighing 3500 tonnes could not be installed as the lifting wires broke, damaging the installation equipment. It was rebuilt and put in place by an 8000-ton capacity crane.

Hibernia platform

The Hibernia oil rig is roughly 314 kilometres from St John, Newfoundland, in Canada. It was constructed to exploit the oil reserves in Hibernia and the Avalon, one of the oldest in the world. Lying at depths of more than 3500 m underwater, these fields are thought to contain over 3 billion barrels of petroleum. They were found in 1979, and the construction of the Hibernia oil platform began in 1991 and was completed in seven years. It produces over 1400 barrels of oil every day. Operated by ExxonMobil, it is owned by numerous companies jointly, such as Murphy Oil and Chevron.

Since the region has inhospitable weather conditions with strong northern winds, fog, and huge floating icebergs, a GBS was considered an ideal choice for giving the structure the desired stability and durability to endure these conditions while working at its maximum capacity. Additional wells were drilled in 2008 to increase production.

The structure comprises a 106 m cement caisson made of concrete, protected by a surrounding steel structure to resist icebergs. The GBS comprises facilities for storing 1.4 million barrels of oil. The oil from these tanks is transported using an oil tanker serving this facility.

The 38,000-tonne decks are supported by four shafts with a height of 100 m. One of the levels contains the automated control and emergency alarm system, while the lowest has temperature control and pipelines.

These decks also comprise rooms capable of accommodating 190 workers, modules, life-saving equipment, rescue vessels and a helipad. The different components of the rig were built in the world’s best manufacturing facilities, with the modules being brought from Italy and the Daewoo shipbuilding yard from Korea.

The components were transported through barges to the installation site and placed over the GBS platform. The world’s fourth-biggest oil platform, weighing 600,000 tonnes, was then completed.

Olympus oil platform

The fifth-biggest oil and gas platform, Olympus, was constructed to exploit the Mars fields in the Gulf of Mexico, 200 kilometres south of New Orleans, US. The installation of this platform was part of a project aimed to expand the life of the oilfields till 2050 and further if possible.

Starting in 2010, it was completed in three years, involving more than 24,000 workers in the construction and assembling phase. The platform’s base was built by Samsung Industries in the South Korean Daewoo Shipbuilding yard and brought to the installation site using barges. Oil was first extracted from the rig in 2014.

It is a tension-leg type platform moored just a kilometre from the old platform and is the largest in the Gulf of Mexico region and the 7th biggest facility owned by the Shell Company. The platform extracts and processes more than 360,000 barrels of oil daily through the 48 oil wells that draw out oil from underwater depths of 6500 m.

The Mars field was founded in 1989, and production was started in 1997. It is crucial for meeting US energy demands and is an important natural resource for the nation. Standing at 405 feet and weighing 122,000 tonnes, Olympus combines the latest technologies and modern amenities for its 195 workers.

The living area is spread over four floors and includes pantries, gymnasiums, a small first-aid room with medical personnel and emergency evacuation equipment. The platform’s supporting pillars are coated with special corrosion-resistant paint.

You might also like to read:

• Life On An Oil Rig: Do You Know What It Takes?
• What are Jack Up Drilling Rigs?
• Different Types Of Offshore Oil and Gas Production Structures
• Types Of Mobile Offshore Drilling Units (MODU)
• What is an Offshore Barge? 

Disclaimer: The authors’ views expressed in this article do not necessarily reflect the views of Marine Insight. Data and charts, if used, in the article have been sourced from available information and have not been authenticated by any statutory authority. The author and Marine Insight do not claim it to be accurate nor accept any responsibility for the same. The views constitute only the opinions and do not constitute any guidelines or recommendations on any course of action to be followed by the reader.

5 Biggest Oil Platforms in the World appeared first on Marine Insight - The Maritime Industry Guide

With wide-ranging applications in commercial, financial, transportation and industrial sectors, Oil and natural gas are two resources that drive the world economies.

The global offshore drilling market size stood at 32 billion US dollars in 2018 but is expected to cross the 90 billion mark by the end of this decade.

In this article, let us review the 10 biggest offshore drilling giants.

1. Schlumberger

The biggest offshore drilling company, Schlumberger is a prominent name in the maritime energy sector. It has a worldwide presence in more than 120 countries and employs over 100,000 professionals including technicians, engineers and research personnel working closely for developing industry-changing technologies that are safer and cleaner.

It was established in 1926 by Conrad and Marcel Schlumberger, two brothers hailing from Alsace, France. Since then it has come a long way by carving out its name as the highest revenue generator among all its competitors and offering reliable services to its international clients. The company recorded annual revenue of around 48 billion dollars in 2017. It is headquartered in Paris, France and has branch offices in Houston, London and the Hague.

It collaborates with international oil companies offering services like data processing, testing of oil wells, site evaluation, drilling and lifting operations etc. It also provides consultatory and management services.

The company has completed the biggest projects in Saudi Arabia, Libya, Turkmenistan and Russia, nations with the world’s largest oil reserves. It has a complex structure and subsidiary companies in Panama, the Netherlands and the British Virgin Islands. It regularly trades on the London, Paris and New York Stock Exchanges.

According to the Global 500 list published by Fortune Magazine, Schlumberger bagged the 287th position in 2016 and has always been one of the top 300 corporations in the world with a large revenue turnover.

2. Halliburton

Founded in 1919 by an American businessman named Erle P. Halliburton, the company is the second biggest products and services provider for the ever-changing requirements of the energy sector. It has a diverse workforce representing over 140 different nationalities in more than 75 countries across the globe. It is based in Houston, United States but has another main office in Dubai.

The company envisages its aim to assist customers in maximising the profitability of their reservoir. It aids in locating the reservoir sites, manages data, undertakes drilling works, constructs oil wells and oversees the management of the asset. In fact, most of the major hydraulic fracturing contracts are bagged by Halliburton.

It also offers geothermal management services including directional drilling and non-portland cement systems. The enterprise uses advanced logging techniques to identify geothermal reservoirs and fractures. It carefully employs pressure drilling to reduce lost circulation. Most importantly, it is known for the usage of novel stimulation methods for enhancing the productivity of the asset.

The company states its mission of providing affordable solutions and underlines the need for transitioning into a low carbon future by combining technological expertise with efficient use of available resources.

In the last three years, it focussed on the complete digitisation of oilfield technologies for boosting operational efficiency by providing real-time information to its clients regarding the status of their projects. Hence, it generated annual revenue of 22,408 billion dollars in 2019.

3. Fluor Corporation

Fluor Corporation is the world’s third-biggest offshore drilling company and a major producer of anti-pollution products. It provides services through its subsidiary companies operating in the oil and gas sector, industries and manufacturing, engineering and construction. The Global 500 list ranked it as the 196th biggest corporation since it recorded annual revenue of around 15.66 billion dollars in 2021.

It was established as a construction enterprise in 1912 by John Simon Fluor and progressed rapidly by constructing oil refineries and other offshore infrastructure for the oil and gas sector. Today, around 55,000 professionals are working for Fluor in more than 50 countries. However, it is headquartered in Irving, Texas, the United States.

It was involved in many complex projects such as the construction of the Al-Zour oil refinery in Kuwait, Nuclear Laboratories in Canada, the Open pit copper mine in Peru and the LNG Canada export facility to name a few. It received many awards from organisations like the International Society for Pharmaceutical Engineering and the Project Management Institute. The company highlights its vision to generate cost-effective innovative solutions for maximising the client’s capital efficiencies.

4. Baker Hughes

Baker Hughes provides a range of services pertaining to the oil and natural gas sector including Casing and Lining Drilling, cementing, drilling automation, providing rig equipment, coiled tubing services, drill bits, drilling fluids, optimization services and so on.

The company is also present in the industrial technology sector and offers industrial asset management and advisory services to its clients. Power generation is possible using NovaLT turbines serving the refining, mining, cement and processing industries.

It has completely digitised its operational structure and smartly uses Artificial intelligence for allowing remote asset monitoring, virtual testing and diagnostics for decreasing costs and increasing performance.

Headquartered in Houston, US, it has employed 54,000 professionals and operates in more than 120 countries. It has research laboratories and manufacturing units in India, Saudi Arabia, Norway, Germany, Australia, Singapore etc. Baker Hughes earned a handsome revenue of 20.705 billion dollars in 2020. Also, the company exited Russia in March ‘22 due to the imposition of international sanctions, a result of the Russian attack on Ukraine.

5. Transocean

Established in 1973, Transocean came into existence after Sonat Incorporated merged with several small drilling companies. It is based in Vernier, Switzerland and generates annual revenue of approximately 7 billion dollars. The company is present in more than 30 countries across the world with major offices located in the United States, Scotland, Brazil, Malaysia, Indonesia, Norway etc.

The company owns and operates a fleet of 49 offshore drilling units comprising ultra-deepwater oil rigs, out of which 15 are located in extremely harsh environments. Around 85 per cent of the company’s rigs were delivered in the last 8 years, hence it is known for the most diverse and flexible rigs in the industry. The upcoming rigs feature their patented hybrid technology for optimum reservoir productivity. It also constructed the ultra-deepwater drillship named Deepwater Titan.

Transocean frequently organises training and internship programs for those wanting to join the company and also for its employees totalling 10,000.

6. Ensco Plc

A provider of offshore drilling services across the globe, Ensco Plc owns a diverse fleet consisting of 39 oil rigs, 13 ultra-deepwater drillships, semisubmersibles and modern jack-ups. Based in London, UK, the company earns annual revenues of over a billion US dollars and is run by a team of 5400 professionals. The company operates in strategic basins such as the US Gulf of Mexico, Brazil, Middle East, Asia, Africa, Pacific Rim.

It is known for one of the most technologically advanced fleets in the petroleum industry and has the world’s biggest jack-up fleet conducting operations in Middle Eastern waters and the cruel environment of the North Sea.

The submersibles are installed with a hybrid mooring technology that allows drilling up to a depth of 1500 to 10,000 feet while the ultra-deepwater drillships can go up to 12,000 feet. The company promises its clients proficient drilling operations and efficient reservoir management.

7. Diamond Offshore Drilling

Diamond Offshore Drilling is an offshore drilling contractor in the oil and gas sector offering oil well construction and asset management services to independent companies as well as government-owned enterprises. Established in 1989, it is headquartered in Texas, USA and has branch offices in Southeast Asian nations, North America and Scandinavian countries like Norway. In 2017, the company earned annual revenues of around 1.5 billion dollars.

It enjoys a significant position in the energy industry as it owns 12 offshore drilling rigs comprising 8 floating platforms and 4 drillships.

The company is renowned for its innovative technologies such as the Pressure Control by Hour Service, developed in collaboration with Baker Hughes and the Sim-Stack technology which speeds up the drilling operations manifold. According to the company officials, this technology helped the company to complete one of the most challenging projects in the Gulf Of Mexico before the scheduled completion date.

8. Rowan Companies

Primarily engaged in digging offshore oil and natural gas wells, Rowan Companies has existed for more than 90 years in the energy sector. It was founded in 1923 in Britain as Rowan Drilling, by Charles Rowan and Arch Rowan who had some experience in the oil and gas sector. The company is based in London, England and has annual revenue earnings of more than 1.4 billion dollars. It was acquired by London based Ensco Plc in 2019 and was renamed Ensco Rowan Plc and trades on the New York Stock Exchange under the ticker ESV.

The company is known for operating one of the youngest fleets in the industry consisting of more than 30 jack-up rigs and 4 drillships. It has drills in Louisiana, the Gulf of Mexico, Alaska, the Middle East, the North Sea and West Africa. The Gorilla class heavy duty offshore drilling rigs can reach a depth of 35,000 feet whereas the ultra-deepwater rigs can drill down to 40,000 feet.

9. Noble Corporation

Noble Corporation provides offshore-drilling services in the oil and gas sector with a fleet of around 20 mobile offshore drilling units comprising 12 floaters and 8 jack-up rigs focussing on deep-water and jack-up drilling operations in established as well as emerging markets across the world. Its clients include independent companies and also government-owned enterprises. The company has been in the offshore drilling sector since 1985 and is known for possessing one of the most versatile fleets in the energy industry.

It is based in London, UK and earned annual revenue of around 1.2 billion dollars in 2021. The company has more than 2500 employees and has branch offices in the United States, Canada, Switzerland, Luxembourg, Malaysia, Qatar, Myanmar, Saudi Arabia etc.

10. Seadrill

The 10th biggest offshore drilling company is Seadrill, established in 2005 by a Norwegian business tycoon named John Fredriksen. The company has focussed on adopting and developing new innovative maritime technologies and improving digital connectivity for better management of the clients’ assets. It also operates training institutes offering technical and leadership training in the maritime and subsea sectors.

The company is incorporated in Hamilton, Bermuda but headquartered in London. It has another main office in Houston and several regional offices in over 20 countries, employing over 4000 professionals.

The company owns and operates 35 drilling rigs and maintains a standardised fleet using its rig asset management platform offering real-time information regarding the asset’s functioning and performance analysis. It also owns 10 drillships and 4 semisubmersibles. The company earns revenues of over 1 billion US dollars every year.

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• Top 10 Biggest RoRo Ships In The World

Disclaimer: The authors’ views expressed in this article do not necessarily reflect the views of Marine Insight. Data and charts, if used, in the article have been sourced from available information and have not been authenticated by any statutory authority. The author and Marine Insight do not claim it to be accurate nor accept any responsibility for the same. The views constitute only the opinions and do not constitute any guidelines or recommendations on any course of action to be followed by the reader.

Top 10 Biggest Offshore Drilling Companies in the World appeared first on Marine Insight - The Maritime Industry Guide

What Is A Jack-Up Platform Or Barge?

A Jack-Up Platform is a floating barge that has movable legs attached to the hull. These legs can be retracted and extended vertically, meaning that once it makes contact with the sea bed, the platform begins to move upwards and out of the water.

The hull on which these legs are built is water-tight, buoyant, and similar to a ship. It has ballast tanks, living spaces (if required), a bridge for operators to work from, and machinery for lowering and raising the legs. Jack Up refers to how the legs are jacked up or down.

The first thing to note is that Jack Up platforms are primarily used in shallow and intermediate water depths. They perform well in depths up to around 120 meters.

At deeper depths, they face issues in structural compliance (discussed later). Jack Ups can be used for drilling and installation operations, and our mobile units as compared to other gravity-based structures.

They can be either towed like other barges or have propulsion units at the aft that move the structure under its own power. The self-propelled variants are less common due to the large power that such units consume.

Instead, tugs with higher-than-average bollard pull are used.

They are also stable since they have widely-spaced supporting legs. The number of these legs depends on the type and functionality of the barge but is usually 3, 4, 6, or 8.

The buoyancy of the hull means that the structure can lift objects out of the water, such as turbines, smaller vessels, or offshore drilling platforms.

Jack ups are one of the most common types of offshore platforms, with over 700 barges in service as of 2019. The first jack-up used in India was procured by ONGC and built-in Hiroshima, Japan.

The tallest jack-up rig to date is the 214-meter-tall Noble Lloyd (the height refers to the height of the platform legs).

The Origin And Development Of Jack Up Barges

The concept for jack-up platforms stemmed from the need for a vessel that could install offshore structures easily. The offshore oil and gas industry was still in the early stages of setting up in the mid-1900s (from around 1940 onwards).

Once explorations were conducted into the feasibility of setting up underwater wellheads, the problem was installing an O&G platform.

Colonel Leon B. DeLong of the United States Army was a part of the Army Corps of Engineers, who worked with temporary military platforms for troops to use.

Post World War 2, he began working on an idea to use jack-up platforms in Greenland for army operations. He refined this idea and designed the DeLong Platform.

Once he left the army in 1949, he started his own organization called the DeLong Engineering and Construction Company. There, the idea of using jack-up platforms for the O&G industry was brought up and DeLong’s team began working on it.

In 1950, he began working on a contract for Magnolia Petroleum (a famous and reputed petroleum company of the early 20th century) to design and build a 6-leg jack-up barge.

In 1952, DeLong began collaborating with McDermott International Inc (an American engineering and construction company currently operating out of Panama). They designed the DeLong-McDermott No. 1 for another major O&G company- Humble Oil (which is known today as Exxon).

The No. 1 was a MODU i.e., it was mobile and could be towed. The design also featured an innovative feature- spud cans, designed to stabilize and improve sea bed gripping.

Over time, the DeLong-McDermott company was taken over by The Offshore Company (known today as Transocean Ltd. based out of Vernier, Switzerland).

However, their idea was used by other companies to revolutionize the offshore industry and increase the number of platforms that could be set up. Zapata Offshore in collaboration with the LeTourneau Company worked on the machinery that operated the legs and looked at reducing the structural weight.

Today, jack-up barges are the most common type of offshore platform and can be found across the world’s oceans- from the Gulf of Mexico to the Pacific Rim.

How Do Jack Up Barges And Standalone Platforms Function?

A jack-up barge is comprised of 4 main parts:

1. The buoyant and water-tight hull on which machinery and deck space is located,
2. The legs that are used to jack the platform vertically,
3. The machinery that is used to move the legs (located on the hull), and
4. The bottommost region of the legs, known as the footing. Spud cans are a common type of footing used in modern jack-up platforms.

The hull is an enclosed structure made of steel, capable of withstanding hydrodynamic loads while floating and stationary. The machinery is stored on the hull and it is usually divided into 3 decks.

The uppermost deck is where the living quarters and helideck are. It is also used as a storage site for heavy machinery and essential items. The intermediate deck is known as the equipment deck, where the drilling rig equipment is housed. It also includes the machinery that is used to move the legs vertically.

Lastly, the lowermost deck is used to store grout/drill mud (in the case of drilling rigs) and store the drilled oil and gas. Over its lifetime, the hull can assume 2 main modes of operations:

1. Floating – During transit and when the legs do not touch the sea bed i.e., fully dependent on buoyancy for supporting the hull weight.
2. Standing – When the legs are anchored in the sea bed with the footing i.e., the weight is supported either solely by the leg reaction force or partially with buoyancy on the hull (if it is in contact with the water).

The jack-up legs are either solid or truss and provide the unit with its unique name. Solid legs are more expensive but are resistant to heavy wave forces.

They are not very common due to the high cost associated with them. Truss legs, on the other hand, make use of legs that are triangulated structural members and provide support in both tension and compression.

They are cheaper to build and can be used in most wave conditions. The advantage with truss members is that the wave resistance is significantly reduced, making the structure transparent to sub-surface hydrodynamic forces.

The type of machinery used to retract and extend the legs vary depending on the platform, but the most commonly used systems are:

1. The mechanical rack and pinion mechanism, and,
2. The hydraulic ram pin-in-hole mechanism.

The rack and pinion system makes use of a gear mechanism that works by rotating a pinion about a rack positioned on the leg. The pinion (on the hull) is part of the hull and climbs up and down the leg using motors that power it.

The hydraulic system is also very common and makes use of a series of rams that can slot into holes along the platform leg. It works by sequentially moving the ram into the hole, hydraulically moving the hull, and then locking it into place. There are 4 rams- 2 upper pins and 2 lower pins, separated by a vertical piston.

In case the deck is being lowered into the water, the ram pins first lock into their holes. Then, the upper pins release, the pistons contract, and then the upper pins move downwards.

Then, they lock into place, the lower pins release, the pistons extend, and then the lower pins again lock into place. This way, the mechanism retracts and extends the legs (the process is in reverse in the case of raising the hull).

Lastly, the footing is used to secure the base of the legs to the sea bed. The most common footing design is the spud can. This is a large flat disk that is slightly inclined upwards on the top surface, closer to the axis. It is used to improve the leg grip and prevent the footing from sinking into soft soil.

Now that we have discussed the various parts, let us look at the operation of installing the jack-up platform.

There are 6 main steps:

1. The jack-up barge is towed to the installation site, with minimal machinery and equipment on board. Any loose items on deck are secured to prevent any accidents during the subsequent operations.

2. The legs are then lowered into the water until it reaches the sea bed.

3. Then, the leg-extending machinery pushes the legs further into the sea bed, while the hull floats.

4. A step known as preloading is then undertaken, whereby the hull is ballasted to full capacity.

5. The hull is then de-ballasted, and it begins to climb the legs, away from the surface.

6. Finally, the hull exits the water and maintains a sufficient air gap. Lastly, any moorings are removed, and the jack-up barge is allowed to face environmental loads without any external protection.

Most of these steps are self-explanatory. However, preloading is an often confusing operation because it seems unnecessary.

When the legs are already in the sea bed, what is the need to ballast the hull? The reason is that the substratum is often unstable and can shift once environmental loads are allowed to act.

To allow the spud cans to properly grip the soil and the legs to sink into the sea bed, the downward load on them is increased by ballasting the hull. This increases the weight acting on the spud cans and secures them in place.

Preloading is a safety procedure since it ensures that the soil can take the hull weight without slipping. In case of foundation failure at this stage, the hull will only sink below the surface, while there will be no fatalities.

The jack-up can be repeatedly preloaded to ensure that it is secured in a stable soil region. During preloading, the hull is brought out of the water to a height of around 1.5 meters. Since there is an abrupt weight transfer from buoyancy to the leg reactions, there is a chance of sudden impact loads.

For this reason, failure simulations should be undertaken to check safety at impact conditions. To prevent the chance of failure, geotechnical investigations are carried out to determine the suitability of a site for setting up the jack-up platform.

Once these steps are completed, the equipment and machinery required for drilling are installed on the different decks. When it is time to shift to a new location, the spud cans are loosened by pumping water through nozzles (to dislodge it from the soil or clay), the legs retracted, and the hull immersed in the water.

An interesting thing to note is that during the floating transit mode, the legs can be used to handle wind and wave loading. By lowering the legs further into the water (without touching the sea bed), the vessel becomes less responsive to wave loads and more stable. This is particularly useful when used in conjunction with ballasting.

How Do Jack Up-And-Fixed Drilling Platforms Work?

Other than working as a standalone platform or barge, jack-ups can also be used to drill oil from the sea bed in more complex operations. Such a jack-up platform is composed of 2 main parts:

1. The fixed unit, and
2. The jack-up unit

These 2 units are located adjacent to each other and work in tandem. They are connected by structural members to provide added stability. Since the jack-up is one of the most stable structures, it can be used for motion-sensitive tasks such as drilling.

The first step in the installation is for the fixed unit to be towed to the site. The fixed unit can be of different types depending on the drilling requirement and is generally a jacket structure. It has limited machinery and houses storage facilities for drilled oil and gas.

Then, the jack-up platform is brought to the site, moored at a fixed distance from the fixed unit, and then jacked up. The jacking height is such that it is nearly level with the deck of the fixed unit.

The main structural consideration for this is that there should be a suitable air gap of around 1.5 – 3 meters between the water’s surface and the underside of both structures.

Once the steps from the previous sections are followed, the platform is ready for the final process. Long cantilever beams are placed between both units and fixed to the decks.

While welded joints are occasionally used, riveted and bolted structures are more common since it is easier to install and dissipates stress better than welded joints.

The cantilever beams are checked for safety and stability, and to ensure that they can be used to cross between both platforms. They often include winch harnesses that can be used to haul goods and material across the gap.

There are also dedicated beams for pipelines that ferry oil and gas from the jack-up platform to the storage facilities on the fixed unit. It may use a system of interlocked beams to add strength to the structure.

Since the jack-up platform is stable, it is used for motion-sensitive tasks such as drilling. It also hosts structures such as the drilling rig, derrick cranes, and helideck.

On the other hand, storage is on the fixed platform. Living quarters are often on the jack-up since they should ideally be located away from the storage depots. The positioning of the fixed unit depends on the expected direction of the wind.

The flare stack which is used to vent fumes is positioned on the fixed unit in such a way that it is leeward i.e., downstream from the wind. This prevents poisonous gases and fumes from fouling the living quarters.

The Types Of Jack Up Barges

Since jack-up barges are ideal for different purposes, they have been modified to suit the varied needs of different industries. In this section, we look at the 4 common types of jack-up barges.

1. Mobile Offshore Drilling Units (MODUs)

A MODU is a type of drilling platform that is not unique to jack-ups. It refers to a class of floating platforms that can be moved across different locations. Unlike older variants of oil rigs that were cemented or firmly connected to the sea bed, MODUs can be detached from supports and towed elsewhere. By fitting drilling equipment on the deck and using a series of connectors and equipment to link it with a wellhead on the sea bed, the jack-up can be converted to an oil drilling platform. The primary modifications to a conventional jack-up are the onboard storage facilities (for the drilled oil) and structures that are required by drilling equipment (such as the Christmas Tree and Blow Out Preventer).

2. Turbine Installation Vessel (TIV)

Offshore wind turbines are commonly found in areas such as the North Sea (near Nordic countries). When several turbines are set up nearby, it is known as a wind farm. These farms are capable of providing a significant amount of power to the neighbouring countries. Their upkeep is an important factor that must be considered before installation. The main challenge in the North Sea wind farms is the high wave heights, strong winds, and violent currents. Even at other locations, repair and maintenance crafts could face problems while attempting to approach the turbine. The stability of the installing and repair vessel is of paramount importance in this field.

By using jack-up barges, installation and repair can be easily achieved since it presents a stable platform. They work just like conventional jack-ups- their legs are lowered, preloaded, and then the platform elevated off the water’s surface. Once this is complete, a series of piles are driven into the seabed for the turbine’s base to be laid. Then, the column with the hub and blades at the top is lowered from the side of the jack-up until it connects with the base. Once the installation is complete, the barge can simply lower itself, lift its legs off, and sail to the next location.

A famous jack-up TIV is the MPI Resolution (aka Mayflower Resolution) that uses a system of 6 legs and hydraulic machinery to install multiple wind turbines. She can elevate to a height of 3 – 46 meters and was the first jack-up TIV.

3. Modified Heavy Lift Vessel (m-HLV)

Heavy Lift Vessels (HLVs) are ships and floating barges capable of lifting heavy structures from the surface of the sea or elevated support columns. For instance, the top offshore platform builders are situated in South Korea, Japan, and China.

However, the platforms are often destined for locations such as the North Sea, the Gulf of Mexico, and the African coastline. Other than semi-submersibles, the vast majority of platforms cannot be floated or towed to their installation site and require another vessel to lift and transport them. This is where HLVs come in.

Jack-up barges can be modified to function as HLVs. A traditional HLV works by ballasting to below the structure and then de-ballasting until it can lift the structure off the surface. However, jack-ups work by positioning the platform under the structure, preloading, elevating till it can lift the structure out, loosening the sea bed supports, and then retracting the legs. It can only be used in regions with shallow water due to the restrictions on leg lengths.

The m-HLV is heavily reinforced about the midship region to prevent sagging and structure failure. The main challenge during the lifting operation is that the platform should not raise too high above the surface, since it requires buoyancy to support the weight of the structure once the legs are retracted. Detailed calculations on the optimal draft of the jack-up are calculated before the operation to minimize the chance of failure.

4. Regularized Barges

Lastly, the jack-up platform can be used as a regular barge for transporting goods. They do not perform any specialized functions like the jack-ups mentioned above but can be used as modified barges that transport 2 main types of cargo– large and unwieldy (such as turbines), and smaller vessels (for service, repair, or deployment). Their legs are generally unused when transporting goods, but the benefit is that when not transporting goods, they can double up as a standard jack-up.

Considerations While Designing, Building, And Using Jack Up Barges/Platforms

Jack-up barges, like any floating vessel, require certain design, structural, and safety considerations to be kept in mind while designing and building them. These are as follows:

1. During preloading, impact load stability and strength must be monitored to prevent point overloading and subsequent failure.

2. Spud cans should be tested in shallow conditions to confirm that the components, such as the nozzles, are working.

3. If the installation site is soft or clayey, the spud cans can be joined together to form a continuous mat-like structure, known as a mud mat.

4. The foundation must be checked to ensure that it can support the hull and machinery weight. Along with preloading, punch through must also be check to ensure that the structure is resting on a firm and hard surface. This reduces the chance of damage during storms or other adverse weather conditions.

5. Uplift forces and spud can break out forces that will act on footings that have been in place for a long period. They can cause structural damage to the footing, legs, and even the hull. The maximum break-out forces occur in clay, and when the spud can is raised by about 0.1 to 02 times its diameter. Cavitation of the lower surface also begins to occur. To prevent this, water jetting through nozzles, prior excavation of soil, cyclic loading, or a combination of these methods can be used.

6. High-strength steel is subject to embrittlement when the oxygen content is low (as is the case underground) and when hydrogen gas is formed due to the cathodic protection system used to prevent rusting. Sufficient care must be taken to inspect the legs for embrittlement or signs of damage.

7. The hull must be located at least 1.5 – 3 meters above the surface, to prevent waves from stripping away the weld joints. While this may seem like a minor problem, it is prevalent in the North Sea region.

8. Safety studies and analysis should be undertaken using the probabilistic method and must account for normally unexpected environmental forces based on 100 years.

9. At very deep-water depths, the spud cans act as hinges, meaning that they become very compliant with environmental forces. They can no longer remain stiff, and the structure is in danger of being loosened from the sea bed. To prevent this, the operating depth is kept at 120 meters. In the case of large platforms that can function at depths of over 200 meters, they use multiple legs that use larger spud cans with more surface area.

For joint drilling platforms that make use of both fixed and jack-up platforms, there are other considerations to be kept in mind. These are as follows:

1. The height of the jack-up should be fixed since if there is a mismatch between the jack-up and fixed units, the cantilever cross beams will come under extraordinary stress and eventually buckle or fail. This could have catastrophic consequences, including the complete structure breaking down. Oil may leak into the ocean, and the lives of staff and crew onboard would be put at risk.

2. The cross beams should be secured after much consideration and planning. This is because people use the beams to cross over, and drilled products also pass through them. In case of an accident, it could lead to a loss of life and property. Extensive tests and simulations are carried out to ensure the cantilever beams are safe for use.

In this article, we have seen how instrumental jack-up barges are to various industries such as the offshore oil and gas sector and the offshore energy sector. They allow large and complex machinery to be installed simply and efficiently. However, safety is an important aspect while working offshore, and this must be kept in mind at all times.

You might also like to read:

• Life On An Oil Rig – Do You Know What It Takes?
• Types Of Mobile Offshore Drilling Units (MODU)
• Offshore Well Drilling: A General Overview
• Understanding Offshore Lifting Operations And Engineering Analysis
• Different Types Of Offshore Oil and Gas Production Structures
• How Subsea Components Of ROV Sustain Tremendous Seawater Pressure?

Disclaimer: The authors’ views expressed in this article do not necessarily reflect the views of Marine Insight. Data and charts, if used, in the article have been sourced from available information and have not been authenticated by any statutory authority. The author and Marine Insight do not claim it to be accurate nor accept any responsibility for the same. The views constitute only the opinions and do not constitute any guidelines or recommendation on any course of action to be followed by the reader.

The article or images cannot be reproduced, copied, shared or used in any form without the permission of the author and Marine Insight.

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Single point mooring (SPM) is a floating buoy/jetty anchored offshore to allow the handling of liquid cargo such as petroleum products for tanker ships.

SPM is mainly used in areas where a dedicated facility for loading or unloading liquid cargo is not available. Located at a distance of several kilometres from the shore facility and connected using sub-sea and sub-oil pipelines, these single-point mooring (SPM) facilities can even handle vessels of massive capacity such as VLCC.

Single point mooring (SPM) serves as a link between the shore facilities and the tankers for loading or offloading liquid and gas cargo. Some of the major benefits of using SPM are:

• Ability to handle extra large vessels
• Doesn’t require ships to come to the port and thus saves fuel and time
• Ships with high drafts can be moored easily
• Large quality cargo can be easily handled

How Single Point Mooring (SPM) Work? 

The offshore-anchored loading buoy is divided into different parts having dedicated functionality.

Mooring and anchoring systems, buoy bodies and product transfer systems are the main parts of the SPM.

The SPM is moored to the seabed using a mooring arrangement, which includes anchors, anchor chains, chain stoppers etc. The mooring arrangement is such that it permits the buoy to move freely within defined limits, considering wind, waves, current, and tanker ship conditions. The buoy is anchored to the seabed using anchor chains (legs) which are attached to the anchor point (gravity based or piled) on the seabed. Chain stoppers are used to connect the chains to the buoy.

The part of the Single Point Mooring System (buoy body) which is floating above the water has a rotating part which connects to the tanker. The rotating part allows the tanker to get stable at its desired position around the buoy. The tanker is usually moored to the buoy by means of a hawser arrangement, which consists of nylon or polyester ropes shacked to an integrated hook on the buoy deck. Chafe chains are connected at the tanker end of the hawser to prevent damage from tanker fairlead. The mooring systems used for such offshore operations follow the standards put forth by Oil Companies International Marine Forum (OCIMF).

The product transfer system is located at the heart of the mooring buoy. The system transfers products to the tanker from the Pipeline End and Manifold (PLEM) (geostatic location) located on the seabed. Flexible hoses known as risers connect the subsea pipelines to the buoy’s product transfer system. The buoy is connected to the tankers using floating hose strings, which are provided with breakaway couplings ( A particular type of coupling with a breakpoint which will break at a predetermined break load, activating internal valves which will automatically close at both ends and prevent further release of products.) to prevent oil spills.

Single Point Mooring Systems use a swivel system which connects the Pipeline End and Manifold (PLEM) to the buoy. The product swivel system provides the flexibility of movement to the tankers during the transfer of products. This movable pipe-connection system prevents premature hose failure due to traction or bending stresses.

General overview of how single point mooring (SPM) system works

• The tanker ship is moored to the buoy for loading or unloading of cargo.
• A boat landing space on the buoy deck provides access to the buoy for setting up the connections and securing the ship.
• Fenders are used to protect the buoy from unexpected movement of the ship due to bad weather.
• Lifting and handling equipment on the buoy allows for handling of hoses connections and safety tools.
• Once the connections are made, valves are operated from the electrical substation.
• Necessary alarm systems and navigational aids are provided as safety precautions.
• Liquid cargo is transferred from the geostatic location (Pipeline End and Manifold (PLEM)) to the tanker using the product transfer system of the single-point mooring system.

A General Video on Single Point Mooring Operation

Additional Reference 

Single Point Mooring Maintenance and Operations Guide 

Single Point Mooring Maintenance and Operations Guide sets out guidelines for operators of SPM terminals and provides a framework and set of procedures that are based on the extensive experience of several companies. It primarily deals with the two most common types of SPM, the CALM (Catenary Anchor Leg Mooring) and the SALM (Single Anchor Leg Mooring).

You may also like to read – How Subsea Components Of ROV Sustain Tremendous Seawater Pressure?

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Offshore lifting is a common operation in offshore construction or installation projects at sea. In this article, we will discuss offshore lifting operations and associated engineering analysis, safety precautionary measures, contingency plans, and challenges involved in lifting.

When is offshore lifting required?

• During offshore installation, i.e., Installing any process module, structure at the operation site
• When shore crane cannot perform the lifting. Sometimes, when a vessel is berthed port side, but it’s required to lift up or install equipment in starboard side, which cannot be reached by the shore crane
• Shore crane with limited lifting capacity: Generally shore crane lifting capacity is only up to 200 tonnes. Equipment exceeding the capacity of the shore crane is usually lifted using floating crane

Examples of offshore lifting

• Offshore module lifting: Offshore vessels like FPSO, FLNGs have various process modules like chemical injection package, sulphate removal system, water injection system, etc.
• Offshore jacket platform installation in the offshore site
• New helideck installation

Challenges involved in offshore lifting

• Dynamic nature of ocean environment
• Lifting gears strength

We will address these challenges and will explain in detail, how to tackle these problems.

For example, a process module to be installed on FPSO. Let’s assume the weight of the module is about 1000 Tonnes.

Let’s consider the weight of the module is about 1000 Tonnes. The most basic requirement is the lifting crane supposed to be of a capacity higher than 1000 tonnes (As per norms, crane safe working load to be at least 1.25 times the weight of the equipment). Let us discuss how the load of the module is transferred to the crane. Load of the equipment is transferred to the crane through the lifting pad eyes, spreader beams, lifting wires, shackles etc. (In general, these are called as lifting gears). Hence all the lifting gears involved in the load transfer must be able to withstand the load imposed during the lifting operation. To analyse whether a lifting gear can withstand a given load, we must first estimate the load imposed on the lifting gear.

In the above lifting arrangements, the 1000 tonne module is lifted using 4-pad eyes. Hence each pad eye is subjected to a load of 250 tonnes. The sling wires transfer the load to the lifting beam. There are four wires used, hence each wire is subjected to 250 tonnes (For time being we will ignore effects due to sling angle). The sling wire transfers the load to the lifting beam. In this case, the lifting beam is subjected to 1000 tonnes (Note: the two pad eyes that transfer the load is subjected to 500 tonnes each).

SLING GEOMETRY

In the above load assessment, we assumed the sling angle to be 90 degrees. In reality, it is not 90 degree. The point of suspension of the equipment should always be in line with the centre of gravity of the equipment to avoid tilting of the equipment.

HOW LOADING CHANGES WITH SLING ANGLE?

Loading changes drastically with the sling angle. Following tables depicts the comparison of loading at 90®, 60®, 30® .

From the above table, we can understand how loads can drastically increase with the reduction in sling angles. Sling angle factors are critical in load assessment. Following Sling angle factors are given in ANSI B30.9.

LIFTING BEAM

-In figure 3, the lifting arrangement was depicted without the use of lifting beam. Usage of lifting beam helps to reduce the sling angle and thereby load on the sling.

From the above figure, it is evident how sling angle is increased using spreader beam (Ø>Q).

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LIFTING BEAM ANALYSIS

Bending and Buckling strength of the beam has to be assessed and proven they are within the requirement.

BENDING STRENGTH

Using Euler beam equation, we can find Bending stress s = M * I/y

Where s is Bending stress, M is the Maximum bending moment, while “I” is the second moment of area and y is the distance from the neutral axis.

In this case, the maximum bending moment can be evaluated as F1H* d.

The second moment of area is πr4/4 (Since the cross section of the spreader beam is circular.

As per class, s evaluated should not be greater than 0.6 * yield strength of the spreader beam material.

Note that in the above evaluation, the weight of the beam is ignored.

BUCKLING STRENGTH

F1H and F2H are potential forces to buckle the beam. Buckling check can be done by evaluating the Euler critical load. If the subjected load is greater than the Euler critical load then the beam will buckle.
Euler critical load P is given by : π2EI/(KL)2

Where E is the young’s modulus of the beam material, I is the Moment of Inertia , K is effective length factor and L is the unsupported length.

Effective Length Factor

Below figure can be used to find out the effective length factor (K).

In addition to the buckling check, compressive stress due to the forces F1H, F2H must be less than 0.6* yield strength of the material.

PAD EYE STRESS ANALYSIS

FORCE ANALYIS

Pad eye is subject ted following forces:
1) Shear force
2) Axial force
3) Normal force

The tension T should be resolved in 3d to estimate the shear force ( the force that is parallel to the plane), axial force ( the force that is in-line with the axis of pad eye ), normal force ( the force that is normal to the plane).

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SHEAR STRESS

Shear stress = shear force/shear area.

Shear stresses are to be less than 0.4 times the yield stress.

BEARING STRESS

Bearing stress is the contact pressure onto a body. It is given by Design load/bearing area.

Bearing stresses are to be less than 0.9 times the yield stress.

BENDING STRESS

As seen earlier, Using Euler being equation we can find Bending stress s = M * I/y

Where s is Bending stress, M is the Maximum bending moment, while “I” is the second moment of area and y is the distance fro the neutral axis.

Bending stresses are to be less than 0.6 times the yield stress.

NOTE: Pad eye bore has to be compatible to the lifting shackle. For example, 20 Tonnes pad eye bore diameter should be large enough for a 20 Tonne shackle pin.

EQUIVALENT STRESS

As we have seen earlier the loading on the pad eyes are multiaxial, hence there is a combination of shear and bending. Vonmisses stress gives an equivalent stress that can be used to assess the strength in multiaxial loading condition.

DYNAMIC EFFECTS

Offshore lifting is dynamic in nature due to the ocean waves, currents, wind forces etc. It is important to include the dynamic effects into the calculation as these can significantly influence the results.

CRANE TIP MOTIONS

Relative motion between the crane tip (carrying the object to be lifted) and the waves should be established. The time period of crane tip motion can be formulated as follows:

T = 2π x √((M +A33 + θ)/k)

where

m = mass of hoisting line per unit length [kg/m]

L = length of hoisting line [m]

M = mass of object in air [kg]

A33 = heave added mass of object [kg]

K = stiffness of hoisting system

θ = adjustment factor taking into account the effect of the mass of hoisting line and possible soft springs.

The Crane tip motion period is compared with the significant wave period and ensured both are not close to causing resonance.

DYNAMIC AMPLIFICATION FACTOR

All the formulae we saw earlier in this article did not account for dynamic effects. They are good to use in a static condition (still water condition). Lifting in dynamic conditions requires slight modification to the formula. All the equation has to be multiplied by a factor called dynamic amplification factor.

Total force = Force (Static) X DAF.

Various classification societies have given recommended DAF for various scenarios which can be used in the calculations. DAF can also be established from model testing.

BUMPER AND GUIDES

Bumper and guides are positioned in such a way to prevent the lifting object (for example module) to strike against any other structure or object during the lifting operation.

LIFTING A SUBMERGED OBJECT

Load on the crane ( and lifting gears) lifting a submerged object can be evaluated by the following equation:

F(static) = Mg – ρVg.

Where M is the mass of the object.

g is acceleration due to gravity, 9.81m2/s.

ρ is the density of water.

V is the displaced volume of the submerged object.

SAFETY PRECAUTIONS DURING OFFSHORE LIFTING

• Perform risk assessment prior to the lifting
• Mooring analysis and ensure mooring lines are intact
• Detailed lifting plan
• The lifting zone completely cordoned off. Only authorised personnel are allowed to access the lifting zone
• Lifting should be headed by a lifting supervisor
• Lifting team should include: Lifting supervisor, rigger, signalman, banks man, crane operator.
• Lifting team should be properly briefed prior to lifting
• Clash check should be done in the lifting route( or path) and ensure no obstruction during lifting operation
• Prior to lifting, inspect all the lifting gears and ensure they are all intact and fit for use
• Ensure all the sea fastenings are removed from the equipment to be lifted and it is free to lift
• In any case, no one should be under the suspended load

CONTINGENCY PLANS

High speed gust wind (Before lifting)

• Counter check on the mooring lines.
• Add additional mooring lines as precautionary measures.
• Hold the lifting operation until the situation is normal.

High-speed gust wind (After lifting)

• Keep all mooring lines tensioned.
• Tugs to push or pull to against wind force;
• Add additional mooring lines as precautionary measures.

Mooring Line Broken

• Deploy tugs to control the vessel movement.
• Add additional mooring lines to control the vessel movement

Floating Crane grounded

• Constantly monitor the hook load and vessel floating status.
• Taking sounding over a period of time to ensure the vessel in intact.

The article gives a brief summary of offshore lifting. In addition to the topics covered (Sling geometry, Sling wire analysis, Lifting beam analysis, Pad eye analysis and Dynamic effects during lifting) in the article, mooring analysis, motion analysis does play a critical role in offshore lifting analysis. These topics are profound, hence will be dealt separately in a different article.

You may also like to read:

What is Basic Offshore Safety Induction and Emergency Training (BOSIET)? 

How Subsea Components Of ROV Sustain Tremendous Seawater Pressure? 

Disclaimer: The authors’ views expressed in this article do not necessarily reflect the views of Marine Insight. Data and charts, if used, in the article have been sourced from available information and have not been authenticated by any statutory authority. The author and Marine Insight do not claim it to be accurate nor accept any responsibility for the same. The views constitute only the opinions and do not constitute any guidelines or recommendation on any course of action to be followed by the reader.

The article or images cannot be reproduced, copied, shared or used in any form without the permission of the author and Marine Insight. 

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The process of oil well drilling at deep sea starts with locating offshore reservoir and using mobile drilling units for the drilling process. Once the the job of temporary drilling units is over, permanent offshore gas/oil production structures or platforms are installed for carrying out further processes.

Well Drilling is a process of drilling a hole in the ocean floor for extraction of natural resources. It is a challenging part of the exploration and development process that is carried out in several stages.

Moreover, drilling a well under difficult conditions such as freezing sea water temperatures and strong sea bed currents with pressures enough to crack even high tensile metals, is extremely taxing. Drilling structures are therefore so designed that they could withstand the nature of external subsea forces.

After the companies possibly ascertain of a site and employ the drilling units in position, wells are drilled on the sea floor using high tech drilling equipment in order to extract either natural gas or oil. The main stages of installing a deep sea drilling well are:

1.Spudding – This is the first stage in the drilling process, where drilling is carried in an open hole location by one of the mobile drilling units, initially with 36” casing being forced up to 100 meters into the sea floor. This 36” casing is the backbone of the well creating a foundation for further drilling. This process is followed by drilling to deeper depths and by continuously adding lesser sized casings until the desired drilling depth is reached.

Setting up the BOP Stack – Once the casings are secured and cementing, a well head or a guide base is set up on the sea floor above the casing unit, the Marine Riser and the Blow Out Preventer is lowered to be setup at the well head which provide continuity from the drilling deck on the Mobile drilling unit to the well for further drilling processes.

Drilling – After the initial setups of the drilling stages are complete; the drill bits and drill collars, drill pipes, turntables on the drilling units’ deck and derrick work in unison and under tension to cut through the rocks and dig out wells that allow oil or natural gas to flow through the casings and ‘up’ to the receiving platform in a very controlled manner.

Drilling at sea means a lot is at stake! Exploration, production and transportation of oil and gas, pollution caused when handling these fossils, development and utilisation of the drilling machinery and related specialised equipment, skilled man-power, etc. are some of the hazards faced when drilling offshore.

Petroleum companies have developed many techniques over the years to satisfy the voracious demands. Earlier, there were lesser alternatives to conventional drilling in shallow waters. Today, the oil and gas explorations and offshore developments have given rise to newer technologies in order to sustain fossil fuel enslavement.

You may also like to read – How Subsea Components Of ROV Sustain Tremendous Seawater Pressure?

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The planned construction of an OTEC (Ocean Thermal Energy Conversion) power plant in the Southern Chinese high seas sets the bar for all potential global OTEC construction and development. The power plant is intended to be a joint venture between two business giants, US-based engineering corporation Lockheed Martin and Hong Kong-based construction consortium Reignwood. The power plant will provide and sustain the energy requirements of the holiday resort township to be developed by the Reignwood consortium.

Once operational, the power plant will be able to generate up to at least 10 mega watts of energy, enough to sustain the energy requirements of a smaller metropolis.

The Chinese high seas were specifically chosen as a preferred location for the power plant. The warmness of the oceanic water in the tropics accounts for a greater degree of variation between the surface and sub-water temperatures which results in great enhanced workability for the power plant.

In addition to its comparatively higher energy generating capacity, the proposed OTEC power plant will also offer the following benefits:

• Consistent and round-the-clock production of energy without any stoppages or interruptions

• Substantial reduction in the emanating of noxious gases

• Substantial reduction in conventional fuel consumption costs

According to the engineering experts of the project, the energy generated through the power plant can also be transferable to other areas like desalination of water resources and providing fuel to electricity-driven automobiles. A highly ambitious venture in terms of its monetary investment, the OTEC power plant nevertheless promises to bring in significant yields to both investing parties.

OTEC Power Plant: Operational System

• Consisting of turbine systems placed above the surface of the water, the OTEC power plant will primarily involve boiling a liquid by channelizing the warm surface waters of the ocean

• The liquid utilised will be one having a comparative lower boiling point so as to offset faster boiling

• The next step would involve an equally rapid cooling of the thus boiled liquid passed through pipes to the under-water turbine systems positioned underwater

• Energy would be generated by this constant process of the fluid being boiled and cooled

OTEC Power Plant: Future Expectations

The utilisation of OTEC power plants has been considered as an alternative fuel generation system since the late 20^th century.

The Chinese OTEC power plant however lays the foundation of its work ability in the widest of sense even allowing for potential constructional plans to be discussed for OTEC power plants capable of generating to up to 100 mega watts of energy. If such power plants do come into existence, it will result in a massive sustaining of the global ecology by harnessing safer and surer methods of energy generation.

You may also like to read – How Subsea Components Of ROV Sustain Tremendous Seawater Pressure?

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The world’s first wave farm was the result of a pioneering effort between Pelamis, the British engineering giant, Enersis, a Portuguese company specialising in alternate energy development and an Australian company Babcock and Brown that provided the required substructure for the WEC.

The main equipment used to channelize and harness the tidal power was provided by Pelamis, based on the engineering module developed by Enersis. Details about the wave farm’s technical characteristics of the offshore wave farm can be explained as under:

Aguçadoura Wave Farm: Technical Specifications

• The offshore wave farm consisted of three main cylindrical tubing, each 120 metres long, positioned in the high seas

• Each of these three cylindrical tubing were further bifurcated into four separate segments and each segment was connected to the other by way of flexible joints

• The friction between each of the segments caused by the repetitive tidal action allowed the engine systems built within the tubing, to generate the necessary tidal energy

• The engine systems were propelled hydraulically

The entire cost of equipping and installing the Aguçadoura wave farm totalled to over US$ 11 million. However in terms of its cost-to-benefit ratio, the wave farm had potential to provide fuel to over 1,500 households in its native country.

The maximum energy generating capacity of the WEC was reported to be around 2.25 mega watts which at that time, was a more than satisfactory statistic.

Technical Problems and the Future of the Wave Farm

Although the world’s first wave farm was highly successful, resultant technical glitches accounted for its abrupt withdrawal from the commercial set-up. The financial difficulties of the Australian firm also accounted for newer collaborators who took over the consequent proceedings of the WEC project. This also affected and hampered the operational viability of the wave farm.

Presently, Pelamis has been engaged in researching activities to restart the offshore wave farm. If the technical analyses are successful, the re-launched WEC would generate substantially greater amounts of wave energy as compared to the earlier Aguçadoura Wave Farm model.

References: principlepowerinc, cleanenergyactionproject, inhabitat

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In the previous article, we found out how a prospective gas and oil site is searched offshore and what types of mobile drilling platforms are used. Offshore oil and gas exploration requires a constant support from offshore vessels in order to transport temporary drilling units and in fixing fixed units.

After the temporary offshore drilling units have completed their jobs of initial oil / gas production, the site is replaced by permanent offshore oil / gas production structures or platforms. Mentioned below are some of the main types of permanent oil production systems that are used.

1. Floating Offshore Production Systems: Semi-submersibles and Drill ships are designed to remain afloat hundreds of miles in deep waters. Though floating in nature, they are also a type of permanent oil production systems.

The idea of commissioning these specialized drilling units is to cater for oil and gas production and also be capable of pumping oil / gas to the receiving stations via flexible risers.

Floating, Production, Storage and Offloading (FPSO) is also a type of floating system which is used for production and storage of oil/gas at the sea. Some of the famous FPSOs are Maersk’s FPSOs , Munin Award Winning FPSO, and Shell’s Preclude- The Largest Floating structure in the world.

2. Tension leg platforms (TLP): TLP structures are also a part of the floating production systems which a capable of providing buoyant production facilities. They are moored to the sea bed via the tendons fixed vertically to the structure. The foundation of TLP’s intricate mooring pattern is kept stationary by piling.

They experience more of horizontal stresses due to waves as compared to the vertical movements which are restricted by the tendons fixed to the foundation. These structures are able to drill at depths beyond 5,000 feet and are more stabilized as compared to the other ultra deep water drilling units.

3. Spar Platforms: For drilling wells beyond 10,000 feet, naval architects have designed a type of drilling and production platform which has a hollow cylindrical hull that can descend upto a sea depth of 200 meters. This are called Spar Platforms. It is secured to the ocean floor by a complex network of cables and tendons.

The weight of the cylindrical hull stabilises the drilling platform and caters for the drilling risers to descend upto the drilling well on the sea floor.

4. Subsea Production System: As the name suggests, this system is based on the idea where wellheads are mounted on the sea floor after the wells have been drilled by one of the many deep sea drilling platforms.

The wellheads are remotely controlled and their automated system is so designed that it allows for transporting the oil or gas directly to the production facilities using a network of undersea pipelines and risers.

Apart from those mentioned above, shuttle tankers are also used in offshore oil production systems.

As technology advancements are progressively made, deep water exploration possess superior challenges for all the operating parties. These massive structures are home to some highly improved and advanced systems, machineries and equipments for carrying out the coveted job of offshore drilling.

Image Credits: loc-group, offshore-technology, myspacecdn, subseaworldnews

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MODU or mobile offshore drilling unit is a term for floating drilling units such as semi-submersibles, jack-up rigs etc.

Oceans have provided us with the bulk of fossil fuels and they still continue to do so. Since decades, petroleum companies have been on a constant lookout for the availability of reserves around the globe.

When the land reserves were getting emptied up due to the constant scooping and drilling, the ever increasing demand for oil and gas had to be extended to the resource-rich oceans.

Offshore drilling and platform development has catered billions of tonnes of natural resources to the global markets over time. Subsea drilling and the related work are considered operationally challenging and financially taxing.

In this article, we’ll try to explain in brief on what goes into drilling oil wells at sea and how gigantic rigs and support platforms have made ultra-deepwater resources available to the world markets.

Locating the offshore oil and gas reservoirs and use of MODU

To decide on a site with a potential oil/gas payout, Geologists and Geo-Scientists work their ways in and around the information collected off the areas with possible oil or gas reservoirs.

Survey vessels with or without Dynamic Positioning systems are hired for seismic surveys. These maritime vessels are equipped with sophisticated equipment, machinery and laboratories, which are able to scan the sea bed to understand the rock formations and find out natural resources lying underneath.

Sound waves are sent, received and decoded from the modern day survey vessel to give Scientists and Geologists sizeable 3D images in order to analyse and discover potential oil and natural gas pockets hidden between the porous rocks underneath the sea.

Site acquiring

Once the site is identified and selected, boundaries are surveyed and earmarked by the local governing body for Energy and Resources. Studies for impact on the environment are carried out. After determining the potential energy sites, oil companies are then called for auctions on unleashed blocks and are asked to submit their bids for a particular block. Naturally, the highest to bid gets the right to drill.

Drilling techniques

After the potential energy-rich blocks are legally cleared, oil companies pursue their investments by employing mobile drilling units that are temporarily acquired and are able to move on to other sites. Permanent structures such as Oil and Natural Gas Platforms are fitted if a location proves energy affluent.

Types of Mobile Offshore Drilling Units Or MODU

Mobile offshore drilling units (MODU) are classified into a number of structures, namely:

1. Drilling barges

They are mostly utilized for shallow water drilling in calm water conditions. Drilling equipment is placed on to the barges’ decks and towed to the site by tugs. Anchors hold the barges in the position where drilling is to be carried out.

2. Jack-up Rigs

These self-contained drilling structures are as good as the drilling barges only to the exception that these massive structures are positioned onto the site by lowering and rooting their three or four giant legs on the sea floor.

The barges are then lifted up above water and are more stable than the floating rigs to be able to drill up to 100 meters. Read more about Jack-up rigs here.

3. Submersible Rigs

These rigs are pontoon-based which allow for water ballasting and de-ballasting in order to position, anchor and re-float the massive structure. All necessary drilling equipment is fitted on the platform’s deck, similar to the drilling barges and jack-up rigs.

The only conspicuous change in these structures is that the drilling and production facilities are rested on stilts that are raised to some height above the pontoons. Their operations are limited to shallow waters due to their submersible design.

4. Semi-Submersible Rigs 

A Semi-Submersible rig is a Mobile Offshore Drilling Unit better known as MODU, which is designed for offshore drilling in ultra-deep waters of the oil and gas-rich areas across the globe. They are partially submerged in water during drilling operations and are normally moored to the sea bed by anchors.

They are technically advanced drilling units which are designed to accommodate platform or decks containing heavy machinery and expensive drilling equipment and are supported by columns for support and stability in the treacherous waters. This design of partial submerging the platform to water is primarily conceptualized for stability reasons and chosen for the very same reason over another highly capable breed of drilling units known as the drill-ships.

5. Drill ships

These vessels are advantageous over the other drilling units such as the semi-submersibles due to their ultra-deepwater drilling capability and easy mobility. They are basically maritime vessels modified to drill wells in oil and gas fields. They are adapted to provide complete offshore drilling solutions to the clients across the globe. They are equipped with exhaustive mooring and positioning systems and are able to propel from one well to another without outside assistance.

are fitted with expensive machinery and drilling equipment which are similar to the ones fitted on any other drilling unit. Since they are required to work in ultra-deepwater areas ranging up to 3000 meters, all supplies and equipment are catered by the offshore workboats. The drillships have a drilling deck and are equipped with a moon pool, and are somewhat similar in design as the other drilling units. The drilling equipment that passes the moon pool is connected to the ‘sub-sea well’ via the ‘riser pipe’ (which is flexible to some extent).

In the next article, we will learn about the different types of permanent offshore oil/gas production structures or platforms used for offshore drilling.

You may also like to read – Seismic Vessel: Main Features and Equipment

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Let’s find out..

Imagine a can of soda water submerged at the depth of 3000 meters of water, and at this depth there is approximately 3000 psi of water pressure acting on the walls of the can. What do you think will happen to the can? The obvious answer is that the can will implode!!!

So how do we ensure that the can sustains this tremendous pressure?

There could be few possible solution;

a) Make the walls of can thicker

b) Use a compensation system.

Option ‘a’ seems simple but it is not a very cost effective solution, plus it will add unnecessary weight to the component, which trust me, no one will want on a ROV (making ROV as light as possible is vital).

That brings us to the compensation System. So what really is compensation system?

The operating principle behind any compensation system is the fact that for a fluid-filled volume, any compressive pressure applied to the outside must be countered by an equal or greater force inside.

The compensator consists of a piston, one side of which is exposed to the ambient pressure, with the other side directly connected to the oil-filled housing. Doing this will ensure that at any depth, the pressure inside the housing is equal to the pressure outside.

The spring provides additional force against the piston, resulting in the pressure inside the housing being slightly higher than ambient. This simple feature ensures that in the event of a leak, oil will flow out of the housing, instead of seawater flowing into it. For this reason, the compensator contains one or more gallons of oil, which is used to back-fill the housing in the event of a small leak.

Imagine the soda can attached to the end of a compensation system and now say for example, the ROV dives at 300 meters of depth, the external pressure acting on the walls of can is approximately around 300 psi, however, this time due to compensator attached to this can, the pressure inside the can is equal to external pressure, thereby ensuring the structural integrity of the can. 

This is how components of ROV sustain high pressures at great depths.

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Maersk Oil, an entity of AP Moller Maersk Group, has opened a new $ 100 m global research centre at Qatar with an aim to unlock the potentials of Al Shaheen oil field.

The Maersk oil Research Centre is a Joint venture of  TNO (Europe’s largest independent companies in the area of technology development and technical consultancy) and Maersk Oil which will emphasis on developing technology to improve oil recovery under its Enhanced Oil Recovery project for its ultra large oil well.

This Project will include students, engineers and researcher from different universities of Qatar, and thus enhance the capabilities of the participants and benefit Maersk Oil Research.

The big amount of $ 100 million will be invested in developing high ambition technology in the oil sector along with talent development of Qatar.

Following are few projects for which research is being done by Maersk oil at Qatar Science and Technology Park:

• Improving the oil recovery by advance scanning equipment at digital core lab

• Maersk oil’s Patent “Drone” Technology which helps in finding where the oil is produced in long horizontal well.

Maersk oil already holds a Guinness world record of drilling the longest horizontal well in the world.

Reference & Image Credit: maerskoil

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Offshore wind turbines have been criticized for quite some time now for the low efficiency that they deliver. One main drawback behind this problem is that some of the power generated by the wind turbine is often lost while feeding the power into the grid, for this has to be done right when the blades are spinning. However, a new offshore turbine system – SeaTwirl is designed to kinetically and efficiently store the energy generated.

The SeaTwirl system is a massive flywheel at the sea. The structure consists of a vertical wind turbine with a hollow torus ring at the bottom. This arrangement is located above the surface of the water; rest all lies below the sea water level.

The whole structure is supported by an axle at the centre of the turbine. A hollow cylindrical body float body is mounted on this axle and is also connected to a generator. As the wind blows, the turbine along with the axle rotates.

Water acts as low-friction roller bearing and allows the turbine and axle to rotate even when the wind stops. The wind energy is converted into power by the generator and can be transferred to the shore via seabed cables.

The torus ring plays an important role to provide the required momentum even when the wind stops. During high wind, water is drawn up the float, into the torus ring. This adds weight around the periphery of the circular turbine and increases the centrifugal force, keeping the spinning for a longer time. When the turbine slows down, the water runs back down the float.

A prototype (one-fifth scale) of the SeaTwirl was tested off the coast of Sweden and has been reported to produce favourable results. According to the reports, it is expected that a 430 meter SeaTwirl will be able to produce 4.5 megawatts of mean power. Moreover, as much of the weight of the system will be supported by sea power, the production cost is expected to be lower than that of conventional offshore wind turbines.

References SeaTwirl

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Scottish marine engineering corporation Aquamarine Power is coming up a never-seen-before wave farm module in the high seas off the Lewis coast in the North-western Scottish province. Once operational, the wave energy farm is expected to power nearly 30,000 households at a maximum energy capacitance of 40 mega watts.

The highly ambitious project will be manned by Aquamarine Power’s ancillary engineering corporation Lewis Wave Power though the help of Oyster energy generating systems. Oyster is Aquamarine Power’s leading tidal energy machinery system and is currently utilised in a variety of similar tidal energy generation projects being carried out by the engineering corporation.

Lewis Wave Energy Farm Salient Features

The wave energy farm is the company’s entry to the prestigious ‘Saltire Prize Challenge.’ The Challenge is regarded to be a unique platform to showcase commercial viability of such alternate energy generation systems across Scotland. Aside from Aquamarine Project, there are four other companies that are competing in the Challenge this year.

The Lewis Wave Energy Farm is expected to be a strong contender in the Saltire Challenge on account of the following characteristics:

• Sustainable harnessing of one of the biggest natural endowments of Scotland

• Utilisation of adequate tidal energy machinery systems – around 60 to ensure absolute viability of the project

• Large scale energy generation capacitance with adequate harnessing capacitance

• Project carried out with full support and assistance of the local population thus adding to its popularity and viability

Saltire Project Challenge: A Scottish Manifestation

The Saltire Challenge is a highly ingenious brain-child instituted by Scottish authorities for maritime engineering development. Strictly focused towards projects that detail generating alternate energy through waves and tides, the Saltire Challenge offers a prize award of about British £ 10 million alongside recognition as the Challenge’s winner.

The Challenge is open to companies, squads coming together for a particular alternate energy generation project and even sole-entity people. Depending on the viability and commercial prospects of the project, any of these entities merit a chance toreceive the monetary award once adjudged winners.

Image Credits: offshorewind

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In a first-of-its-kind, the Japanese marine engineering giants Mitsui have come up with an ingenious alternative power generation system. The power generation system will effectively utilise both wind energy and oceanic currents to generate electricity. Expected to be set up in the Japanese high seas, these tidal-wind energy turbines are expected to generate electricity nearly double of what the present traditional wind energy generating turbine models produce.

The Savonius Keel and Wind Turbine Darrieus (SKWID) System: Details and Characteristics

Known as the SKWID turbine system, the tidal-wind energy turbines have been uniquely constructed. Since the energy generating system is expected to channelize both wind and tidal energy, the turbine system has been constructed with a perpendicular axis of rotation. According to experts involved in the construction and testing of the equipment, this aspect of the turbine system allows it to be installed and highly effective even in the most volatile high seas.

The equipment gains its name from the two engineering giants providing each of the separate equipment in the hybrid tidal-wind turbine system. The equipment’s tidal energy turbines have been provided by Savonius while the wind energy turbines are of Darrieus’ make. Some of the other technical high-points of the SWKID system can be further pinpointed as follows:

• The wind energy turbine of the SKWID turbine system will extend above the surface of the oceanic waters to nearly 50 metres

• The tidal energy turbine system located sub-surface is said to have a circumference of almost 15 metres

• The energy generating equipment has been affixed on the deck area of the SWKID equipment. This is expected to allow easy upkeep of the equipment whenever required

• SWKID doesn’t require any external power boosting to start its initial operations. This makes the tidal-wind turbine system highly suitable to the present-day needs

• The equipment can effectively channelize the weakest of tides and the harshest of blowing oceanic winds from any direction to generate high levels of electricity

• Total output from the Savonius Keel and Wind Turbine Darrieus System is expected to generate electricity for almost 300 homes

• The turbine system is highly feasible for remote locations and also for those areas requiring immediate critical electricity supply

Savonius Keel and Wind Turbine Darrieus System: Looking at the Future

The Savonius Keel and Wind Turbine Darrieus System has laid the foundations for future marine engineering channels. Maritime experts from all over the world have been quite appreciative of the exceptional alternate energy generating system.

Though the turbine system is still under the test stages, these votes of confidences from various sources have guaranteed the success of the equipment. This has thus paved the way for similar or far more advanced models of alternate energy sources channelizing the maritime field.

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