What is an oil platform made of? Giants at sea: offshore drilling platforms. Drilling rigs "Uralmash"

29.09.2020

About how oil is produced, I already. Today I will talk about how the Offshore Ice-Resistant Stationary Platform (OIRFP) is arranged using the example of an oil platform in the Caspian Sea.

This drilling rig started pumping oil a little less than a year ago April 28, 2010 and is designed for 30 years of operation. It consists of two parts connected by a 74-meter bridge:

118 people live in a residential block measuring 30 by 30 meters. They work in 2 shifts of 12 hours a day. The shift lasts 2 weeks. Swimming and fishing from the platform is strictly prohibited, as well as throwing any rubbish overboard. Smoking is allowed only in one place in the residential block. For a bull thrown into the sea, they are immediately fired:

The residential block is called LSP2 (Ice Resistant Stationary Platform), and the main drilling block is called LSP1:

It is called ice-resistant, because in winter the sea is covered with ice and it is designed to withstand it. The hose you see in the photo is the sea water that was used for cooling. She was taken from the sea, driven through the pipes and brought back. The platform is built on the principle of zero reset:

A support vessel constantly runs around the platform, capable of taking on board all people in the event of an accident:

Workers are transported to the station by helicopter. Fly hour:

Before the flight, everyone is instructed, and they fly in life jackets. If the water is cold, then wetsuits are also forced to wear:

As soon as the helicopter lands, 2 hoses are sent to it - they are very afraid of fires here:

Before entering the platform, all arriving passengers undergo a mandatory safety briefing. We had an extended briefing, since we got on the platform for the first time:

10.

You can only move along LSP1 in helmets, work boots and jackets, but in the residential block you can even walk in slippers, which many people do:

11.

The offshore platform is an object of increased danger, and security is given a lot of attention here:

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There are lifeboats on the accommodation block and on LSP 1, each of which can accommodate 61 people. There are 4 such boats on residential LSP2 and 2 on LSP1, that is, all 118 people can easily fit on rescue equipment - this is not the Titanic for you:

13.

Passengers from the ship are lifted on a special "elevator" that can accommodate 4 people at a time:

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Every room on every deck has evacuation direction signs - red arrows on the floor:

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All wires are neatly tucked away, low ceilings or steps are marked with red and white striped markings:

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At the end of our tour, I learned that this platform was completely built by us. I was surprised, because I was sure that she was a "foreign car" - there is no smell of a scoop here. Everything is made very carefully and from high quality materials:

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Since there are a lot of photos and information, I decided to break my story into 2 posts. Today I will talk about the residential block, and about the most interesting - about the wells and the production process - in the next post.

The captain himself led us along LSP2. The platform is a sea one, and the main thing here, as on a ship, is the captain:

19.

There is a backup CPU (Central Control Panel) in the residential block. In general, all production control (oilmen emphasize O) is carried out from another control panel located on LSP1, and this one is used as a backup:

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The working unit is clearly visible from the backup console window:

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The captain's office, and behind the door on the left is his bedroom:

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The bedspreads and colored linens are the only thing that is dissonant with the European appearance of the drilling rig:

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All cabins were open, although their owners were on shift. There is no theft on the platform, and no one closes the doors:

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2018-12-14

Offshore oil platforms are needed to develop hydrocarbon reserves in the Arctic. In Russia, foreign floating drilling rigs are mainly used. They are either bought or leased. Today, due to the US sanctions policy, the geopolitical and economic situation, it is becoming impossible to acquire new platforms from Western companies.

In Soviet times, 100% of components for drilling rigs were made at domestic enterprises. With the collapse of the Union, some of them ended up outside of Russia, and some of them completely ceased to exist.

But the need to develop the reserves of the Arctic makes us think about the state of affairs in the industry. At the beginning of the 2000s, there was no demand for offshore oil platforms. The construction of the jack-up installation "Arctic", which was laid down in 1995 and planned to be commissioned in 1998, was no longer funded. The project was completed at the beginning of this decade.

The most significant of the domestic projects was the Prirazlomnaya oil platform built in 2013, during the creation of which industrial, resource and scientific and technical structures solved the tasks assigned to them with the support of the state.

Other achievements of Russian engineers were the Berkut and Orlan offshore oil platforms. They are distinguished by their ability to withstand low temperatures and severe seismic vibrations. At the shipyard in Astrakhan in 2014, an ice-resistant platform was handed over in order to produce in the Caspian Sea.

Expensive pleasure

The development and manufacture of a modern oil platform is a process that is quite comparable in complexity to space projects. The cost of floating drilling platforms starts from $0.5-1 billion, while the insurance of objects is 2% of the property value. Rent costs hundreds of thousands of dollars daily. Such amounts have to be spent due to the fact that there are no domestic analogues.

To date, Russian plants have managed to master the creation of oil platform foundations and self-assembly of the remaining elements from foreign components. Residential modules, drilling complexes, offloading devices, power systems and other large-sized items are purchased from abroad.

Experts note that insufficiently developed transport infrastructure is also a significant problem. Delivery of building materials and equipment to production sites in the Arctic and the Far East, where the main projects are planned, requires significant costs. Access is only to the Azov, Baltic and Caspian Seas.

Despite the active actions of the Ministry of Energy and the Ministry of Industry and Trade of Russia regarding the replacement of foreign technologies, industry experts recognize the impossibility of replacing, even in the long term, foreign technologies in the construction of offshore oil platforms due to the fact that in our country there is no modern technologies to implement such projects. Due to the fact that the replaced technologies have a high cost, domestic orders are implemented at Asian shipyards. The development of domestic offshore technologies is provided for by the Federal Target Program "Development of Civil Marine Engineering", but its implementation has not yet begun.

Great plans

Russian and Asian shipyards are planning to increase output. According to the forecast of the Ministry of Energy, by 2030 the number of offshore platforms on the Russian shelf will reach 30 units. Until 2020, within the framework of current obligations, 100 projects aimed at .

There are currently 15 drilling platforms operating on the Russian shelf. Of these, eight are stationary production, designed for, as well as seven mobile platform-vessels, which are designed for drilling wells. For mobile platforms, it is also necessary to organize underwater production or build a stationary platform.

What is an oil platform and how does it work

An offshore oil platform consists of four main components - the hull, the drilling deck, the anchor system and the drilling rig. The hull is a pontoon whose base is supported by columns. Above the hull is a drilling deck that can carry hundreds of tons of drill pipes, as well as several cranes and a helipad. A drilling rig rises above the drilling deck, the task of which is to lower to the bottom, and then raise the drill. At sea, the entire structure is held in place with steel mooring cables by an anchor system.

At sea, it begins after seismic exploration by special ships with a displacement of up to 3 thousand tons. Such vessels unwind seismic streamers behind them, on which receiving devices are located to create acoustic waves using an oscillation source. Shock waves are reflected from the layers of the earth and, returning to the surface, are captured by instruments on the ship. Based on the obtained data, two-dimensional and three-dimensional seismic maps with offshore oil reserves are created.

After exploration, the drilling process begins. After the drilling process is completed, the drill is removed to seal the well so that oil does not leak out to sea. To do this, blowout prevention equipment 15 m high and weighing 27 tons is lowered to the bottom, thanks to which not a single substance will leave the well. It is capable of blocking the oil flow in 15 seconds.

When oil is found, a special oil production, storage and offloading facility will pump the oil from the bottom of the sea and send it to refineries on the shore. It should be noted that an oil platform can be anchored for decades.

Seven Russian giants

Of the seven drilling platforms in Russia, five belong to Gazflot, a subsidiary of Gazprom. Two more are owned by Arktikmorneftegazrazvedka (part of the structure of Zarubezhneft), they carry out drilling orders. Most of the fixed platforms are located on the Sakhalin shelf: Molikpaq, Piltun-Astokhskaya-B and Lunskaya-A, which are used by Gazprom. The Berkut and Orlan platforms are located on the Rosneft Sakhalin-1 project. Two more - the Caspian LSP-2 and D-6 operate at the Kravtsovskoye field in the Baltic Sea - belong to LUKOIL. And finally, the Prirazlomnaya platform of the Gazprom Neft company is located in the Pechora Sea.

The upper part of the majority of Russian platforms that carry out the drilling management and control system is made abroad. For example, the topside of the Berkut platform at the Aruktun-Dagi field in the Sakhalin-1 project was built in the Republic of Korea by Samsung Heavy Industries. The Orlan platform at the Chayvo field was assembled in Japan and placed on a base made in Russia. The Prirazlomnaya platform is a drilling and technical module taken from the decommissioned Hutton platform in Norway and assembled with a base made at the Sevmash enterprise in Severodvinsk. The topsides of the Lunskoye-A and Piltun-Astokhskaya-B platforms were also made in the Republic of Korea. The Molikpaq platform has been fully transported to Sakhalin from the Canadian shelf.

According to experts, the construction of one platform with stable financing takes from 2 to 4 years, the cost of building one platform varies from $0.5 to $1 billion, depending on the declared production capacity. Most of the orders for components for drilling platforms are received by factories in the Republic of Korea. Low-tech components are produced by the Vyborg Shipbuilding Plant and the Zvezda plant. Domestic shipyards are fulfilling orders for work on the shelf of four Russian oil and gas companies, but the details have not yet been disclosed.

Sanctions against Russia hit the United States

If in Russia there are not enough offshore platforms, especially for work in the Arctic, then abroad in the last three years the opposite situation has developed. Platforms remain without contracts for underwater drilling.

Among the main reasons, industry experts cite the instability of oil prices and limited opportunities to participate in projects on the Russian shelf, which again is due to Western sanctions aimed primarily at the Russian oil industry. Here, the main emphasis is on the extraction of hydrocarbons on the Russian shelf. However, this blow ricocheted and affected American companies engaged in offshore drilling and equipment manufacturing. As a result, thanks to the prohibitions of their government, they lost their planned long-term contracts in Russia.

In the waters of North-Western Europe, the number of active offshore drilling platforms, for example, in 2017 decreased by 20 units. Due to the fact that most of them are designed for harsh natural and climatic operating conditions in the northern seas of Europe, they cannot be used in other, warmer areas. And US sanctions do not allow them to be used on the Russian shelf. As a result, drilling platforms are mothballed in anticipation of when the situation will change for the better.

The deep sea drilling market is storming

Mining companies' investment in subsea drilling has grown rapidly since the financial crisis of 2008-2009. At the same time, according to GBI Research, during 2010-2015 they should have increased annually by an average of 6.6% and eventually reach $490 billion. Most of these funds were supposed to be directed to the development of deep-sea zones - in the waters of the Gulf of Mexico, off the coast of Brazil, West Africa, as well as a number of countries in the Asia-Pacific region.

The largest Western oil and gas companies planned the construction of offshore platforms in significant quantities. However, as a result of the price crisis in the energy market in the summer of 2014, there was a decrease in funding for offshore drilling programs and, as a result, these plans were curtailed, and at a rapid pace. If in 2010 there were 389 offshore drilling rigs operating in the world, and by 2013, as a result of a systematic increase, their number amounted to 459 units, then in 2014, instead of the planned growth, it was reduced to 453 units.

Experts predicted a partial freeze on core investment programs and a delay in the commissioning of new offshore drilling rigs. Nevertheless, by 2017 the number of operating offshore drilling rigs increased to 497 units.

Offers exceeded demand

As a result of the growth of active offshore drilling rigs, supply in this market continues to significantly exceed demand. In 2016, 184 new platforms of various types were built, and in 2017 - 160 units. this technique. According to industry experts, the lack of demand and the increase in supply will be even greater in the near future due to the commissioning of new platforms ordered between 2011 and 2013.

In this regard, operators are seeking to postpone the acceptance of new 22 floating and 73 jack-up drilling rigs to 2019. In the current situation, according to analysts, out of this number, only 10 drilling rigs will be able to receive contracts immediately after commissioning.

The picture is further aggravated by the fact that the process of decommissioning offshore drilling rigs that have served their time is not proceeding at a sufficient pace to compensate for the emergence of new equipment on the market. As a result, a situation has arisen where not everyone has enough contracts that they counted on before.

According to IHS Petrodata, in two recent years the total number of offshore drilling platforms decreased by 9.5%, while the number of operating rigs decreased by 34% over the same period to 403 units.

Unemployed platforms

Active decommissioning of platforms was observed in almost all major regions of offshore oil and gas production. Recently, between 2015 and 2017, the most offshore drilling platforms were cut in Latin America - 42 units. This affected drilling operations in the seas of the Central and South America, in the Caribbean and the Gulf of Mexico. The reduction affected small operators, and the ten largest oil companies, on the contrary, only strengthened their positions during this time.

For 38 units. reduced the number of platforms in the Asia-Pacific region. The recognized regional leader, China's COSL, has retained all of its installations, but only half of them are actually in operation.

West African offshore developers have stopped drilling operations at 21 offshore rigs. In the sector of the Gulf of Mexico, where US companies operate, 16 drilling platforms stopped working. In the Middle East, 13 units have ceased production, of which eight have been mothballed in situ.

The situation with the operation of offshore platforms in the northern seas, intended for use in harsh natural and climatic conditions, mainly on the shelf of the North-West of Europe, is better than in other regions.

Despite the sharp decline in world oil prices since the second half of 2014, the utilization rate of these platforms remained at 100% until the beginning of 2015. Referring to the high cost of oil production, operators operating in the northern seas counted on additional benefits from their governments. Someone managed to get them.

In the first half of 2015, oil production in the Norwegian and British sectors of the northern shelf reached record levels. This was achieved by increasing the intensity of production of the most promising wells while reducing the total number of offshore platforms involved in the region. Their employment rate was 70%. In the winter of 2015-2016, when the price of oil reached $30 per barrel, some offshore drilling platforms in the region ceased to operate. As a result, by September 2016, another 20 installations were left without work. The overall utilization rate dropped below 40% and only by June 2017 did the load factor again reach 40%.

Will decommissioning old platforms help?

On a global scale, a situation has developed when Russia has run out of offshore platforms on the oil-producing shelf, mainly in its Arctic part. In Western countries and in the USA, on the contrary, the demand for them has fallen, and part of these capacities has become unclaimed on the market. Today, idle platforms cannot be used in Russia due to the US sanctions policy, and there is nothing to load them with. As a result, the owners of offshore platforms incur significant losses, because the cost of daily rent of an offshore platform reaches $100,000.

In the current situation, hopes for a normalization of the situation are mainly associated with the decommissioning of existing offshore installations. Operators are encouraged to take such a step average age semi-submersible fleet, significantly exceeding that of drilling vessels for deep-water operations. However, while the outlined broad plans are far from being realized, general position does not inspire operators with much optimism.

Our reference
Surface platforms
To extract oil under the water column, drilling platforms are used, which are placed on floating structures. Pontoons, self-propelled barges are used as swimming facilities. Offshore drilling platforms have certain design features, so they can float on the water. Depending on the depth of the oil or gas field, different drilling rigs are used.
floating platform
Floating platforms are installed at a depth of 2 to 150 m and can be used in different conditions. A floating drilling platform is an advantageous structure, since even with a small size, it can pump out a large volume of oil or gas, which makes it possible to save on transportation costs. Such a platform spends several days at sea, then returns to the base to empty the tanks.
Stationary platform
A stationary offshore drilling platform is a structure that consists of a topside structure and a supporting base. It is fixed in the ground. Design features such systems are different, so there are several types of stationary installations.

Gravity - the stability of these structures is ensured by the own weight of the structure and the weight of the received ballast.

Pile - gain stability due to piles driven into the ground.

Mast - the stability of these structures is provided by braces or the required amount of buoyancy.

Depending on the depth at which oil and gas development is carried out, all stationary platforms are divided into deep-water and shallow-water platforms.
Climbing platform
Jack-up drilling platforms are similar to drilling barges, but the former are more modernized and advanced. They rise on masts-jacks, which rest on the bottom. Structurally, such installations consist of 3–5 supports, which are lowered to the bottom for drilling operations. Such structures can be anchored. The self-elevating floating platform can operate at depths up to 150 meters. These installations rise above the surface of the sea thanks to columns that rest on the ground.
Semi-submersible installation
The semi-submersible oil drilling platform is one of the most popular offshore drilling rigs, as it can be operated at a depth of over 1,500 meters. Floating structures can dive to considerable depths. The installation is complemented by vertical and inclined braces and columns, which ensure the stability of the entire structure. The upper body of such systems is living quarters, which are equipped with the latest technology and have the necessary supplies.

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Introduction

Geologists explore both land and seas and oceans.

Natural gas fields are not only on land. There are offshore deposits - oil and gas are sometimes found in the depths hidden by water.

Nearly 70 percent of the Earth's surface is under water; no wonder exploration companies are turning their attention to sub-ocean bedrock and sediment as a source of minerals. This so-called "offshore mining" is nothing new. The first offshore exploration work was carried out in the 1960s and 1970s, If most of the Earth's surface is covered with water, then why is the method offshore production growing so slowly? There are two explanations for this: politics and technological limitations. Before the UN Conference on the Law of the Sea, there was no agreement on how much of the sea shelf belongs to the country, and where international waters begin. Now that ownership issues have been settled, technology has advanced, and commodity prices have skyrocketed, the issue of offshore exploration is becoming more and more acute.

In our time, the issue of improving offshore drilling rigs, how to make oil production in the waters more productive and safe, is quite acute.

History of offshore oil production

The beginning of offshore oil production dates back to the 20s of the nineteenth, when in the city area. Baku, 20-30 m from the shore, they built wells isolated from the water, from which they scooped offshore oil from shallow horizons. Usually such a well was operated for several years. In 1891, an inclined well was drilled on the California coast of the Pacific Ocean, the bottom of which deviated to a distance of 250 m from the coast, and for the first time opened productive seams of an offshore deposit. Since then, the Californian shelf has become the main target for prospecting, exploration and production of hydrocarbons under the Pacific Ocean floor.

The world's first offshore oil field appeared in 1924 near the city of Baku, where they began to drill wells in the sea from wooden islands, which later began to be fixed with steel piles cemented in the seabed. The grounds for drilling wells for the purpose of developing offshore oil fields began to be created in the CCCP in the early 1930s. 20th century.

In the late 1940s and early 1950s, the trestle method of oil production was widely used in the Caspian Sea. Similar offshore oil fields with a sea depth of 15-20 meters were also built in the Gulf of Mexico and in Venezuela. Construction of floating technical means for the development of offshore oil fields began mainly in the 50s of the 20th century with the creation of drilling platforms.

Systematic search for oil deposits in the waters of the seas and oceans began in 1954. In 1965, only 5 countries of the world carried out offshore oil production, in 1968 - 21 countries, in 1973 more than 30 countries, in 1984 more than 40 states extract gas and oil oceans and over 140 search for them on the shelves.

Geography of deposits

Works for oil and gas cover vast areas of the oceans. In the sedimentary layer of the bottom of which about 1000 deposits have been discovered.

The main reserves of oil and gas are on the continental shelf; in a number of areas of the World Ocean, the continental slope and the oceanic bed are also considered oil and gas bearing. Oil and gas fields have been discovered on the shelves of 60 countries. More than 500 deposits are being developed off the US coast, about 100 - in the North Sea, more than 40 - in the Persian Gulf. Oil has been discovered and is being produced on the shelves of North and South America, Europe, Southeast Asia, Africa, Australia, New Zealand and a number of other water areas. In the CCCP, the traditional oil-producing region is the Caspian Sea.

In the Atlantic Ocean and its seas openly a large number of offshore oil and gas fields that are being intensively developed. The richest offshore oil and gas regions in the world include the Gulf of Mexico, the Maracaibo lagoon, the North Sea, the Gulf of Guinea, which are being intensively developed. Three major oil and gas provinces have been identified in the Western Atlantic:

1) from the Denis Strait to the latitude of New York (industrial reserves near Labrador and south of Newfoundland);

2) offshore Brazil from Cape Kalkanyar to Rio de Janeiro (more than 25 fields have been discovered);

3) in the coastal waters of Argentina from the Gulf of San Jorge to the Strait of Magellan. According to estimates, promising oil and gas bearing areas make up about 1/4 of the ocean, and the total potential recoverable oil and gas resources are estimated at more than 80 billion tons.

On the relatively developed shelf of the province, vast oil and gas basins of the North, Irish, Baltic and Mediterranean seas are exploited. On the territories adjacent to the sea, large deposits of hydrocarbon raw materials have been explored. A number of deposits are of global importance

The bowels of the Pacific Ocean are rich in oil and natural gas, but only a small part of them has been studied and developed. The reserves of potential oil and gas resources are estimated at 90–120 billion tons (30–40% of the reserves of the World Ocean). More than 3 billion tons have been transferred to the category of explored and recoverable reserves, and 7.6 billion tons have been classified as promising and forecast. Underwater developments are carried out mainly at depths of up to 100 m and at a distance of 90-100 km from the coast. The main offshore oil and gas production areas are: the southern part of the California shelf and the waters of Cook Bay (USA), the Bass Strait (Australia), the coastal waters of the Malay Archipelago, Brunei and Indonesia, the Bohaiwan Bay (PRC), the waters of Guayaquil Bay (Ecuador) and the shelf zone of Peru. Extensive prospecting and exploration work is being carried out on the shelf of Sakhalin, the South China Sea, and in the Strait of Magellan. Oil and gas are produced on the shelves of the provinces, many of the deposits of the coastal zone (are of world importance.) The most intensive development of the marine industry has been in Indonesia, Malaysia, and Singapore. Indonesia is the region's largest producer of oil and oil products (total reserves, including the shelf, are about 8 billion tons), and tin ore. Continental offshore oil and gas fields are concentrated off the coast of the islands of Java and Madura, in the northern part of the Western Strait and near the western and east coast islands of Kalimantan.

Oil and gas production is increasing in the state of Sarawak (Miri), on the shelf of the northwestern part of the island of Kalimantan and off the Malay Peninsula

The bowels of the northeastern coastal regions and the continental shelf of the province are also rich in hydrocarbons (Alaska, the Los Angeles area and the coastal waters of California),

Oil fields (Chiapos) are exploited in the coastal states of Mexico, oil reserves have been explored on the coast of Colombia, and oil and gas fields are being developed quite successfully in Ecuador. However, in the countries of the Eastern Province on the Pacific coast, deposits are less common than in the interior and on the Atlantic coast.

Technologies of offshore oil production. Rig Types

The overall system for oil and gas production in offshore oil and gas fields usually includes the following elements:

one or more platforms from which production wells are drilled,

· pipelines connecting the platform to the shore;

Onshore installations for processing and storage of oil,

loading devices

A drilling rig is a complex technical structure designed for offshore oil and gas production.

Coastal deposits often continue on the part of the mainland located under water, which is called the shelf. Its borders are the coast and the so-called edge - a clearly defined ledge, beyond which the depth rapidly increases. Usually the depth of the sea above the crest is 100-200 meters, but sometimes it reaches up to 500 meters, and even up to one and a half kilometers, for example, in the southern part of the Sea of \u200b\u200bOkhotsk or off the coast of New Zealand. Different technologies are used depending on the depth. In shallow water, fortified "islands" are usually built, from which drilling is carried out. This is how oil has long been extracted from the Caspian fields in the Baku region. The use of this method, especially in cold waters, is often associated with the risk of damage to oil-producing "islands" floating ice. For example, in 1953, a large ice mass that broke away from the shore destroyed about half of the oil wells in the Caspian Sea. Less commonly used technology is when the desired area is edged with dams and water is pumped out of the resulting pit. At a sea depth of up to 30 meters, concrete and metal overpasses were previously built, on which equipment was placed. The flyover was connected to the land or was an artificial island. Subsequently, this technology has lost its relevance.

If the field is located close to land, it makes sense to drill an inclined well from the shore. One of the most interesting modern developments is remote control of horizontal drilling. Specialists control the passage of the well from the shore. The accuracy of the process is so high that you can get to the desired point from a distance of several kilometers. In February 2008, Exxon Mobil Corporation set a world record for drilling such wells as part of the Sakhalin-1 project. The length of the wellbore here was 11,680 meters. Drilling was carried out first in a vertical and then in a horizontal direction under the seabed at the Chayvo field, 8-11 kilometers from the coast. The deeper the water, the more sophisticated technologies are applied. At depths up to 40 meters, stationary platforms are built (Fig. 4), but if the depth reaches 80 meters, floating drilling rigs (Fig. 4) equipped with supports are used. Up to 150-200 meters, semi-submersible platforms operate (Fig. 4.5), which are held in place with anchors or complex system dynamic stabilization. And drilling ships are subject to drilling at much greater sea depths. Most of the "wells-record holders" were carried out in the Gulf of Mexico - more than 15 wells were drilled at a depth exceeding one and a half kilometers. The absolute record for deep water drilling was set in 2004 when Transocean and ChevronTexaco's Discoverer Deel Seas drillship began drilling a well in the Gulf of Mexico (Alaminos Canyon Block 951) at a sea depth of 3,053 meters.

In the northern seas, which are characterized by difficult conditions, stationary platforms are often built, which are held at the bottom due to the huge mass of the base. Hollow "pillars" rise up from the base, in which the extracted oil or equipment can be stored. First, the structure is towed to its destination, flooded, and then, right into the sea, the upper part is built on. The plant on which such structures are built is comparable in area to a small city. Drilling rigs on large modern platforms can be moved to drill as many wells as needed. The task of the designers of such platforms is to install the maximum of high-tech equipment in the minimum area, which makes this task similar to designing a spaceship. To cope with frost, ice, high waves, drilling equipment can be installed right on the bottom. The development of these technologies is extremely important for countries with a vast continental shelf.

Interesting facts The Norwegian platform "Troll-A", a bright "representative" of the family of large northern platforms, reaches 472 m in height and weighs 656,000 tons. (Fig. 6)

The Americans consider 1896 to be the start date of the offshore oil field, and its pioneer is the oilman Williams from California, who drilled wells from the embankment he built.

In 1949, 42 km from the Absheron Peninsula, on the overpasses built to extract oil from the bottom of the Caspian Sea, a whole village called Oil Rocks was built. Employees of the enterprise lived in it for weeks. The Oil Rocks Trestle can be seen in one of the James Bond films - “The world is not enough.” The need to maintain the underwater equipment of drilling platforms significantly influenced the development of deep-sea diving equipment. To quickly close the well in an emergency - for example, if a storm prevents the drillship from remaining in place - a kind of plug called a "preventer" is used. The length of such preventers reaches 18 m, and the weight is 150 tons. The beginning of the active development of the offshore shelf was facilitated by the global oil crisis that erupted in the 70s of the last century.

After the embargo was announced by the OPEC countries, there was an urgent need for alternative sources of oil supplies. Also, the development of the shelf was facilitated by the development of technologies that by that time had reached such a level that would allow drilling at significant sea depths.

The Groningen gas field, discovered off the coast of Holland in 1959, not only became Starting point in the development of the North Sea shelf, but also gave the name to the new economic term. Economists called the Groningen effect (or Dutch disease) a significant appreciation of the national currency, which occurred as a result of an increase in gas exports and had a negative impact on other export-import industries.

Let us consider in more detail the technologies for drilling wells in water areas and the types of drilling rigs.

There are the following methods of drilling wells in water areas (Fig. 8):

1. from offshore fixed platforms;

2. gravity offshore stationary platforms;

3. Jack-up drilling rigs;

4. semi-submersible drilling rigs;

5. drilling ships.

An offshore fixed platform is a drilling base resting on the bottom of the water area and rising above sea level. Since at the end of the operation of the well, the MSP remains at the site of construction, the offshore well drilling scheme, in contrast to the onshore well construction scheme, provides for the presence of a riser string that isolates the well from the water column and connects the underwater wellhead to the drilling site of the offshore stationary platform. Wellhead equipment (preventors, casing string heads, a device for draining flushing fluid from the well to the cleaning systems) is also mounted on the MSP.

Four or five tugs are required to tow the platform to the well site. Usually, other auxiliary vessels (port tractors, escort vessels, etc.) also participate in the towing of the MRP. In good weather, the average towing speed is 1.5 - 2.0 kt/h.

Gravity offshore fixed platform is a drilling base made of reinforced concrete and steel. It is built in deep-water bays and then delivered by tugboats to the point of drilling production and exploration wells. The GMSP is intended not only for drilling wells, but also for the extraction and storage of black gold before it is shipped by tankers to the place of processing. The platform has a large weight, so no additional devices are required to hold it at the drilling point.

After the development of the field, all wells are mothballed, the unit is disconnected from the wellheads, separated from the seabed and transported to a new point within the given area or to another region of drilling and oil and gas production. This is the advantage of the HMSP over the MSP, which, after the development of the field, remains in the sea forever.

The jackup floating drilling rig has a sufficient buoyancy margin, which is of great importance for its transportation to the drilling site along with drilling equipment, tools and the necessary stock Supplies. At the drilling site, with the help of special lifting mechanisms and supports, the jack-up rig is installed on the seabed. The body of the installation is raised above sea level to a height inaccessible to sea waves. In terms of the method of installing preventer devices and the method of connecting the drilling site with the underwater wellhead, the jack-up rig is similar to the MSP. To ensure the reliability of well operation, casing strings are suspended under the rotor table. Upon completion of drilling and after the development of the exploration well, liquidation bridges are installed and all casing strings are cut below sea level.

A semi-submersible floating drilling rig consists of a hull that includes the actual drilling platform with equipment and pontoons connected to the platform by stabilizing columns. In the working position at the drilling point, the pontoons are filled with the estimated amount of sea water and submerged to the estimated depth under water; in this case, the effect of waves on the platform is reduced. Since the SSDR is subject to rolling, it is impossible to rigidly connect it to the underwater wellhead using a riser (riser). Therefore, in order to prevent the destruction of the ligament of the mouth - SSBU, the riser column is provided with a telescopic connection with a sealing assembly and airtight swivel joints of the FOC. with a floating facility and subsea wellhead blowout equipment The tightness of the moving elements of the riser string must ensure the isolation of the well from sea water and the safety of operations under acceptable operating conditions.

The MFDR is delivered to the drilling site by tugboats and kept on it by an anchor system during the entire period of drilling and well testing. Upon completion of its construction, the SSDR is removed from the drilling point and distilled to a new location

In the construction of deep offshore oil and gas wells, a drilling ship is used, on which all the drilling and auxiliary equipment and the necessary supply of consumables is found Pa the drilling point of the BS is under its own power; its speed reaches 13 knots / h (24 km / h). Above the drilling point, the vessel is held by a dynamic positioning system, which includes five thrusters and two lead screws that are constantly in operation.

BOP subsea equipment is installed on the seabed after the BS is placed at the drilling point, it is connected to the wellhead using a riser with a diverter, two swivel joints and a telescopic joint to compensate for vertical and horizontal movements of the drilling vessel during the well construction process.

The main factor influencing the choice of the type of floating drilling equipment is the depth of the sea at the drilling site. Until 1970, jack-up drilling rigs were used for drilling wells at depths of 15--75 m, at present - up to 120 m and more. -300 m and more.

Drilling ships, due to their higher maneuverability and speed of movement, greater autonomy compared to SSDR, are used in drilling prospecting and exploration wells in remote areas at water depths up to 1500 m and more. The large stocks of consumables available on the vessels, designed for 100 days of operation of the unit, ensure successful drilling of wells, and the high speed of the vessel's movement ensures their quick relocation from a drilled well to a new point. In contrast to the MODU for the BS, there are large limitations in operation, depending on the sea state. Thus, when drilling, the heaving of drilling ships is allowed up to 3.6 m, and for the MODU - up to 5 m. 20--30% of the wave height. Thus, drilling of wells with MFDR is carried out at a significantly higher sea state than when drilling with BS. The disadvantages of a semi-submersible floating drilling rig include a low speed of movement from a drilled well to a new point. A new direction in underwater oil production is the creation of underwater production complexes (Fig. 9), which provide normal atmospheric conditions for the work of operators. Equipment and materials (cement, clay, pipes, aggregates, etc.) are delivered to drilling platforms by supply vessels. Decompression chambers are also installed on them and necessary equipment for diving and a number of auxiliary works. The produced oil is transported to the shore using offshore pipelines, which are laid on the high seas with the help of specialized pipe-laying vessels. Along with pipelines, systems with offshore berths are used. Oil is delivered to the berth through an underwater pipeline and then through flexible hoses or risers to tankers.

Drilling for oil and gas in arctic conditions

Drilling for oil and gas in arctic conditions has its own characteristics and depends on the ice conditions and the depth of the sea.

There are 3 ways of drilling in these conditions: from a floating vessel; co ice; c a bottom-mounted platform or vessel capable of withstanding the action of ice. Great experience in drilling from ice has been accumulated in Canada, where they drill at a depth of up to 300 m. In the absence of a thick ice base and significant depths, massive floating caisson structures are used, equipped with thrusters, capable of functioning without a man of the year and resisting the action of moving ice, waves, wind and currents. Auxiliary vessels are used to break large ice floes and remove icebergs. In the presence of large icebergs, the removal of which is difficult, the caisson operational structure is disconnected from the bottom and set aside with the help of thrusters.

Main oil production areas

Already, about 20% of oil is extracted from the bottom of the seas and oceans. By some estimates, half of the Earth's oil reserves are located offshore and in deeper waters.

In the Gulf of Mexico, signs of oil were found at a depth of more than 3000 m. The main areas of offshore oil production are the Gulf of Venezuela, the shelves of the Gulf of Mexico and the state of California, the Persian Gulf, some areas of the Gulf of Guinea (off West Africa), the North Sea, shallows off the coast of Alaska, Peru, Ecuador, as well as the Caspian Sea, the waters of Lake. Maracaibo and Cook Bay.

Offshore oil production in Russia

Exploration and exploitation of marine underwater resources is more than two centuries old. Scientists and oilmen have long paid attention to the numerous seeps of oil and gas from the bottom of the sea in the coastal waters of some islands of the Apsheron and Baku archipelagos, especially in the Baku Bay.

In 1781 - 1782. a squadron of Russian ships engaged in the study of the Caspian Sea visited the area of \u200b\u200babout. Residential. The team noticed a film on the surface of the sea, which was recorded in the logbook of one of the ships. The Russian academician G.V. Abich (Fig. 12). Studying the islands of the Caspian Sea, he drew attention to the outflows of oil and gas from the bottom of the sea near some of the islands. In his work devoted to the study of mud volcanoes, he, in particular, pointed to the presence of oil and gas in the bowels under the bottom of the Caspian Sea in the area of Oil Rocks in the Bibi-Heybat Bay.

At the beginning of the 19th century Baku resident Gadzhi Kasumbek Mansurbekov decided to start extracting oil from the bottom of the sea in the Bibi-Heybat bay. For this purpose, in 1803, he built two wells, lined with wooden log cabins, 18 and 30 meters from the shore. These wells, which produced a significant amount of oil, were in operation until 1825, when they were destroyed by a storm.

After that, interest in offshore oil production arose again in late 1873 - early 1874. A group consisting of oilman Robert Nobel, skipper Robert Miller, Libava resident B. de Boer and fleet lieutenant Konstantin Iretsky turned to the Mining Department. They petitioned for the allotment of 10 acres of the seabed to them in the Bibi-Heybat Bay for the organization of oil production. This petition met with fierce resistance from the oil owners Zubalov and Dzhakeli, owners of oil fields on the shore of this bay. They protested to the Baku Governor, justifying their objections by the fact that the towers would prevent their ships from delivering the necessary materials for drilling and production to the berths built on the shore of the bay. Only in 1877 did the Mining Directorate refuse a request to provide plots on the sea.

The next petitioners were V.K. Zglenitsky, N.I. Lebedev and I.S. Zakovenko, who applied to various authorities in 1896, 1898, 1900 and 1905 for permission to offshore drilling. In 1896, mining engineer V.K. Zglenitsky filed a pardon with the State Property Administration of the Baku Governorate and Dagestan Region, in which he asked to be given a section of the seabed for oil exploration and production. The Department of State Property refused, citing the fact that the sea and the seabed are not under its jurisdiction.

The next time the petition was submitted to the Minister of Agriculture and State Property and left unanswered. Only after a second appeal, the Ministry of Agriculture and State Property submitted the petition for consideration by the Mining Department, which, without understanding the essence of the proposal, spoke out negatively. The refusal was justified by the fact that oil produced at sea would be more expensive than on land, the organization of the oil industry at sea would cause great damage to fisheries, and the presence of towers in the sea and, possibly, open oil fountains would interfere with navigation. However, the department acknowledged the need to deeply study the presence of oil reservoirs under the seabed. In 1897, the study of this issue was transferred to N.I. Lebedev, who, by his research, confirmed the oil-bearing capacity of the layers of the Baku Bay. As a result, the Mining Department makes the following decision: “In those parts of the seabed where geological research has already established the presence of oil and where the presence of oil fields will not harm fishing and navigation, oil production can be allowed, but not directly, but after filling it with earth.”

This decision did not force V.K. Zglenitsky to abandon his project, and in 1900 he again applied to the Caucasian Mining Administration for granting him the right to extract oil in the Bibi-Heybat Bay. The department sent this petition to the Ministry of Agriculture and State Property with its conclusion, which stated that the project was dangerous in terms of fire and oil production in offshore areas could be allowed only after the creation of an artificial territory by filling the sea in the allotted areas. Project V.K. Zglenitsky was submitted for consideration by the technical commission of the ministry. According to the project, drilling of wells was envisaged from separate sites built on wooden piles driven into the ground. In order to avoid sea pollution and loss of oil in the event of a release, it was planned to build a tank for 3000 tons on the base. pumping equipment. The technical commission did not accept the project and, like the Mining Department, spoke in favor of developing offshore oil areas only after they were backfilled with soil. At the same time, she recognized that it is possible to allocate 300 acres (one acre is a little more than 1 ha) for backfilling in the Bibi-Heybat Bay. After discussing this issue in the Cabinet of Ministers on June 30, 1901, the Mining Department decided to backfill part of the water area of the Bibi-Heybat Bay. According to this decision, 300 acres allocated for backfilling were divided into plots of 4 acres each. It was brought to the attention of the oil owners about the delivery of these sites at a price of 125 thousand rubles. An executive committee, consisting of oil owners, was created to manage the backfilling work, which began work at the end of 1905, when 50 plots had already been leased.

However, despite the decision of the Mining Department on the possibility of developing offshore deposits only after backfilling the allotted territories with soil, at the end of 1905 engineer N.S. Zakovenko with a petition to allow drilling of wells using a floating drilling rig located on a caisson-pontoon. Although the experts gave a high rating to this project, it was also rejected by the Mining Department, which motivated the rejection by the unfinished design of the project. The project of backfilling the bay was finally abandoned. According to the project, a section of the sea of 300 acres was previously subject to fencing with a stone pier. To manage the backfilling of the bay, the executive committee invited engineer P.N. Pototsky, who worked in Kherson on the construction of a canal at the mouth of the Dnieper.

The construction of the barrier pier, begun in January 1910, was completed in the middle of 1911, after which the Sormovo Society began backfilling. For this purpose, the Sormovo Shipbuilding Plant built a special dredging caravan consisting of two dredgers with a capacity of 1100 hp each. s, two refulers, six tugs, ten barges with a capacity of 1100 m3 and two auxiliary vessels. The work lasted 8.5 years, and 193 acres (or 211 hectares) of the seabed were covered. April 28, 1920 was established in Azerbaijan Soviet authority, and on May 24, enterprises involved in the extraction and processing of oil were nationalized. From the first days of nationalization, Baku's oil workers began to restore and reconstruct the oil industry. In a short time, work on backfilling the bay was also resumed. The first stage of filling with an area of 27 hectares was completed within two years. Already in 1922, the first exploratory wells were laid on the territory reclaimed from the sea. At the beginning of 1923, 10 wells were in drilling. The labors of oil workers in the development of oil fields from the artificially created territory were crowned with success. The first well completed on April 18, 1923 gave a fountain of clean oil.

The exceptionally good results obtained during the drilling and operation of the first wells prompted us to increase the pace of development of the backfilled oil area and begin work on backfilling the second stage in accordance with the developed P.N. Potocki project.

The results obtained during drilling of wells and studies carried out by geologists have shown that rich deposits go into the sea, far beyond the backfilled territory. Then the idea came up to drill wells from specially constructed islands in the open sea. Back in 1925, a powerful fountain hit from a well drilled from a free-standing wooden base built in the Bibi-Heybat Bay. Well 61, completed by drilling from this island, is the first in the world to be drilled offshore. This successful experience led to the fact that work on the development of oil deposits lying under the seabed continued with the drilling of separate wells.

In the five years following the commissioning of well 61, 262 wells were drilled and 6,600 thousand tons of oil and a significant amount of gas were produced. At first, artificial islands were built by driving wooden piles into the ground, mounted on two paired boats - kirzhims. Up to 300 long piles were required to base one well. The need to import timber from the northern regions of the country, as well as the seasonality of delivery, seriously hampered the development of work to bring rich oil deposits into exploitation. The disadvantage was that the piles could not be driven in areas of the sea, where the bottom is composed of strong rocks, with the presence of underwater rocks. Only in 1934, young engineers N.S. Timofeev and K.F. Mikhailov proposed and put into practice a method for the construction of offshore individual foundations on metal bored-fill piles. The development of offshore deposits in the coastal waters of about. Artem.

Thus, it can be stated that the exploration and development of offshore oil fields by the methods of creating artificial territories and building individual island-type foundations were carried out for the first time in the sea in the USSR in the bay of Ilyicha (former Bibi-Eybatskaya).

Until the beginning of the Great Patriotic War there was a systematic work on the development of the underwater resources of the Caspian Sea. War-induced redeployment of drillers along with equipment to the east of the country led to a sharp reduction in drilling work everywhere, including at sea. With the end of the war and the gradual return of drillers to Azerbaijan, drilling operations resumed. At sea, exploration and production drilling has been carried out for a long time at shallow depths from individual foundations of N.S. Timofeeva, B.A. Raginskiy and other oilmen.

Due to frequent storms, the construction of the foundations was delayed. This greatly hindered the development of offshore oil and gas fields. Separate wells laid on the coast and carried out by directional drilling in the sea did little to contribute to the maximum increase in production from the Caspian Sea. All this led to the appearance of the construction of block bases, individual components of which were manufactured at a mechanical plant and transported to the shore, closer to the planned drilling area. The first such drilling rig designed by L.A. Mezhlumova was installed in the area of about. Artem in 1948. With the creation of a new, more efficient stationary base, offshore drilling operations gained wide scope. The needs of the post-war country in oil necessitated the commissioning of new rich deposits. In this regard, the issue of exploration and production of oil in offshore areas has become acute.

Given the availability of positive geological and exploration data, in 1948 it was decided to lay an offshore exploration well in the Neftyanye Kameny area. The first industrial gusher of oil on Oil Rocks hit on November 7, 1949. This was an event that heralded the discovery of a unique oil and gas field in the Caspian.

Of great importance in the accelerated development of offshore oil and gas fields was the introduction of offshore platforms and high-performance methods of their construction, developed by B.A. Raginsky, A.O. Asan-Nuri, N.S. Timofeev and others. In 1951, the construction of overpasses began at the Oil Rocks field. By 1964, more than 200 km of overpasses and near-overpass platforms were built in the sea, sea depths up to 40 m were explored. On the basis of large-scale exploration and development of offshore oil areas, a new branch of the oil and gas industry emerged - the development of offshore oil and gas fields. Based on the generalization and systematization of the experience of development and exploitation of offshore oil and gas deposits, a number of provisions and principles of equipment and technology for offshore oil and gas production were developed. At present, the length of overpasses in the Caspian Sea exceeds 350 km, depths up to 70 m have been mastered. In 1980, a floating semi-submersible drilling rig (SSD) Kaspmorneft was built, built by order of the Ministry of Gas Industry by Rauma Repola in Finland and equipped with powerful drilling equipment , which allows drilling exploration wells with a depth of 6000 m at a water column of up to 200 m.

During the development period from 1949 to 1980, more than 260 million tons of oil and more than 135 billion m3 of gas were produced from the fields of the South Caspian. In the USSR, already in 1978, a special department was created under the Ministry of Gas Industry for the development of offshore offshore fields. In 1990, almost 100 thousand people worked in the department.

Growth trend in oil and gas production (1928-1965) (Figure 13)

Offshore oil and gas production, which began in the Caspian, has now spread to other seas and oceans. Intensive consumption of fuel and energy raw materials was the reason that by the beginning of the 1980s. More than 100 of the 120 countries with access to the sea have been searching for oil and gas on the continental shelf, with about 50 countries developing offshore oil and gas fields. According to the Geneva Convention of 1958, the territory of the sea up to a depth of 200 m, adjacent to the coastline, belongs to the territory of the country, and then the free zone begins. The largest offshore production areas are the Gulf of Mexico, Lake. Maracaibo (Venezuela), the North Sea and the Persian Gulf, which account for 75% of world oil production and 85% of gas. At present, the total number of offshore production wells worldwide exceeds 100,000, and oil is extracted from sea depths up to 300-600 m. In terms of offshore drilling and oil production from offshore fields, the United States, Norway and Great Britain are ahead. In the United States, offshore exploration is subsidized by the government, and the amount of subsidies is up to 80% of total cost project. Over 20 years, from 1960 to 1980, oil production on the continental shelf increased 7 times - from 110 to 720 million tons and amounted to 25% of the total world production. At present, oil extracted from offshore fields accounts for about 30% of all world production, and gas - even more. Offshore oil production is carried out using submersible and semi-submersible drilling platforms. In our country, there are few drilling rigs that are used in Western countries, since they are expensive. In addition, these are complex engineering structures. One of the largest installations has a height of 170 m, weighs 10 million tons, has four supports, each of which could include a three-section nine-story building. A crane with a lifting capacity of 2.5 thousand tons works on it. It can lift a five-story 100-apartment building. Up to 48 wells can be drilled from such a rig, and production is up to 8 million tons of oil, which is equal to the entire annual production of the Caspian Sea. The cost of such an installation is 2 billion dollars. Four floating drilling rigs are operated in Russia (Fig. 14), purchased at one time in Canada. They are installed in the Barents Sea and on Sakhalin. To develop the Russian continental shelf, a consortium was created, which included Japan and the United States.

offshore oil drilling

offshore drilling conditions

The offshore drilling process is influenced by natural, technical and technological factors (Fig. 15). These include hydrometeorological, geomorphological and mining-geological conditions.

Hydrometeorological conditions are characterized by sea waves, its ice and temperature conditions , fluctuations in water level (tides - low tides, surges - surges) and the speed of its flow, visibility (fogs, low clouds, snowstorms, precipitation). For most of the seas washing the shores of Russia (Japanese, Okhotsk, Bering, White, Barents, Tatar Strait), the following average frequency of wave heights is typical,%: up to 1.25 m (3 points) - 57; 1.25 - 2.0 m (4 points) - 16; 2.0 - 3.0 m (5 points) - 12.7; 3.0 - 5.0 (6 points) - 10. The average frequency of wave heights up to 3.0 m in the Baltic, Caspian and Black Seas is 93%, 3.0 -5.0 m - 5%. The coastal zone of the Arctic seas is covered with immovable landfast ice for most of the year. Navigation here is possible only 2 - 2.5 months a year. In severe winters in closed bays and bays of the Arctic seas, drilling from ice and fast ice is possible. It is dangerous to drill from ice during periods of ice melting, breaking and drifting. At the same time, drifting ice smooths out the swell. This is especially true for the Kara, Laptev, East Siberian and Chukchi seas. Here, the average frequency of wave heights up to 3 m is 92%, 3 - 5 m - 6.5%. For drilling in water areas, negative air temperatures are dangerous, causing icing of the drilling base and equipment and requiring a lot of time and labor to bring the power equipment to readiness after settling. The drilling time at sea is also limited by reduced visibility, which during the ice-free period is more often observed at night and in the morning. The effect of reduced visibility on offshore drilling can be mitigated by the use of state-of-the-art radar guidance and radio communication technology on the rig and onshore. Drilling foundations are exposed to the action of currents in the sea associated with wind, tidal and general water circulation. The speed of currents in some seas reaches high values (for example, in the Sea of Okhotsk, up to 5 m/s). The impact of currents changes in time, in speed and direction, which requires constant monitoring of the position of the floating drilling rig (MODU) and even rearranging its anchors. Work with currents above 1 m/s is possible only with reinforced anchor devices and means of their distribution. In the zone of high tides, the bottom of a large part of the coastal water area is exposed and the so-called inaccessibility zone increases sharply, into which drilling ships cannot deliver installations. The height of the tides, even in the neighboring seas and their areas, is different. So, in the Sea of Japan, the tides are practically not noticeable, and in the northern part of the Sea of \u200b\u200bOkhotsk they reach 9-11 m, forming at low tide many kilometers of strips of bare bottom. Geomorphological conditions are determined by the outlines and structure of the shores, the topography and soil of the bottom, the remoteness of the points of laying wells from land and equipped ports, etc. The shelves of almost all seas are characterized by small bottom slopes. Isobaths with a mark of 5 m are located at a distance of 300 - 1,500 m from the coast, and with a mark of 200 m - 20 - 60 km. However, there are gutters, valleys, depressions, banks. The bottom soil, even in small areas, is heterogeneous.

Sand, clay, silt alternate with accumulations of shells, gravel, pebbles, boulders, and sometimes with rock outcrops in the form of reefs and individual stones. At the first stage of the development of offshore deposits of solid minerals, the main object of geological study is areas in coastal areas with water depths of up to 50 m. This is due to the lower cost of exploration and development of deposits at shallower depths and a fairly large shelf area with depths of up to 50 m. Single exploratory wells drilled in depressions up to 100 m deep. The main zone of the shelf, explored by geologists, is a strip with a width of hundreds of meters to 25 km. The remoteness of well locations from the shore when drilling from ice fast ice depends on the width of the fast ice strip and reaches 5 km for the Arctic seas. The Baltic, Barents, Okhotsk Seas and the Tatar Strait do not have conditions for quick shelter of boats in case of a storm due to the lack of closed and semi-closed bays. Here, for drilling, it is more efficient to use autonomous RDUs, since when using non-autonomous installations, it is difficult to ensure the safety of personnel and the safety of the installation in storm conditions. A great danger is the work at the steep steep and rocky shores, which do not have a sufficiently wide beach area. In such places, when a non-autonomous PBU breaks down from anchors, its death is almost inevitable. There are almost no equipped berths, bases and ports in the Arctic shelf areas, therefore, the issues of life support for drilling rigs and the ships serving them (repair, refueling, shelter during a storm) must be given special importance here. In all respects, the best conditions are in the Japanese and inland seas of Russia. When drilling in areas remote from possible shelters, a weather forecast warning service should be well established, and the watercraft used for drilling should have sufficient autonomy, stability and seaworthiness. Mining and geological conditions are characterized mainly by the thickness and physical and mechanical properties of the rocks crossed by the well. Shelf deposits are usually loose rocks with boulders included. The main components of bottom sediments are silts, sands, clays and pebbles. In various proportions, sand-pebble deposits, loam, sandy loam, sandy-silt, etc. can form. For the shelf of the Far Eastern seas, bottom sediment rocks are represented by the following types,%: silts - 8, sands - 40, clays - 18, pebbles - 16, others - 18. Boulders are found within 4 - 6% in the section of drilled wells and 10 - 12% of wells from their total number. The thickness of loose deposits rarely exceeds 50 m and varies from 2 to 100 m. The thickness of interlayers of certain rocks varies from a few centimeters to tens of meters, and the intervals of their manifestation in depth do not follow any regularity, with the exception of silts, which in most cases are located on bottom surface, reaching 45 m in “calm” closed bays. Silts in the upper layers are in a liquefied state, at great depths they are somewhat compacted: shear resistance 16 - 98 kPa; angle of internal friction 4 -- 26°; porosity 50 - 83%; humidity 35 - 90%. Sands have cohesion that is practically equal to zero, the angle of internal friction is 22 - 32 °, porosity is 37 - 45%. The shear resistance of clays is 60-600 kPa; consistency index 0.18--1.70; porosity 40 - 55%; humidity 25 -- 48 % . The rocks of bottom sediments, with the exception of clays, are incoherent and are easily destroyed during drilling (categories II - IV in terms of drillability). The walls of the wells are extremely unstable and, without fixing, after their exposure, they collapse. Often, due to the significant watering of the rocks, quicksands are formed. The core recovery from such horizons is difficult, and their drilling is possible mainly ahead of the bottom hole with casing pipes.

Platform disasters

Accidents during oil production (Fig. 17) on the continental shelf Gas and oil production on the sea shelf is inevitably accompanied by various kinds of accidents. These are sources of severe pollution of the marine environment at all stages of work. The causes and severity of the consequences of such accidents can vary greatly, it depends on the specific set of circumstances, technical and technological factors. We can say that each individual accident unfolds according to its own scenario.

The most typical causes are equipment breakdowns, human errors and extreme natural events such as hurricane winds, seismic activity and many others. The main danger of such accidents, spills or releases of oil, gas and masses of other chemicals and components, leads to severe consequences for the environment. Such accidents have a particularly strong impact when they happen close to the coast, in shallow water and in places with slow water circulation.

Accidents at the drilling stage Such accidents are primarily associated with unexpected releases of liquid and gaseous hydrocarbons from the well as a result of the drill passing through zones with high pressure. Perhaps only oil spills from tankers can be compared with such accidents in terms of force, severity, and frequency. They can be conditionally divided into two main categories. The first involves an intense and prolonged blowout of hydrocarbons, which happens when the pressure in the drilling zone becomes abnormally high and conventional plugging methods fail. This is especially common in the development of new deposits. Just such an accident happened during the development of the Sakhalin-1 field. The second type of incidents is associated with regular episodes of hydrocarbon leakage during the entire drilling period. They are not as impressive as the rather rare cases of gushing, but the impact they have on the marine environment is quite comparable, due to their frequency.

Pipeline accidents

Complex and long underwater pipelines have been and remain one of the main environmental risk factors in offshore oil production. There are several reasons for this, they vary from material defects and fatigue, to tectonic movements of the bottom and damage by anchors and bottom trawls. Depending on the cause and nature of the damage, the pipeline can become a source of both a small and a large oil leak or release.

The largest accidents on oil platforms

March 1980 The Alexander Keilland oil platform in the North Sea broke due to "metal fatigue" and capsized. 123 people died.

· September 1982 Ocean Ranger oil platform (USA) capsized in the North Atlantic, killing 84 people.

· February 1984 One person was killed and 2 injured in an explosion on an oil platform in the Gulf of Mexico off the coast of Texas.

· August 1984 An explosion and fire on the Petrobras platform off the coast of Brazil killed 36 people and injured 17.

· July 1988 The biggest disaster in history - on the Occidental Petroleum's Piper Alpha oil platform, as a result of an explosion following a gas leak, 167 people died.

· September 1988 4 people died in the explosion and subsequent flooding of an oil platform owned by Total Petroleum Co. (France), off the coast of Borneo.

· September 1988 Explosion and fire on the Ocean Odyssey oil platform in the North Sea, killing one person.

· May 1989 Three people are injured in an explosion and fire at a Union Oil Co. oil platform. (USA) off the coast of Alaska.

· November 1989 Penrod Drilling Co. oil platform explosion. in the Gulf of Mexico, 12 people were injured.

August 1991 Explosion at Shell's oil production

· January 1995 Explosion on a Mobil-owned oil platform off the coast of Nigeria, killing 13 people.

· January 1996 3 people were killed and 2 injured in an explosion on the Morgan oil platform in the Gulf of Suez.

· July 1998 2 people were killed in an explosion on the Glomar Arctic IV oil platform.

· January 2001 Two people died in a fire on the Petrobras gas platform off the coast of Brazil.

· March 16, 2001 P-56 exploded off the coast of Brazil - the largest oil platform in the world, which belonged to Petrobras. 10 oil workers were killed. On March 20, after a series of devastating explosions, the platform sank, causing irreparable damage. environment region and total losses, which, according to experts (including lost profits), exceed one billion US dollars. In Brazil, this message caused mass protests: over the past three years, 99 incidents have occurred at the company's enterprises.

· October 15, 2001 According to the conclusions of environmentalists, the extensive construction of oil platforms on the Sakhalin shelf endangered the population of the protected gray whale. The oil company Sakhalin Energy has begun dumping toxic waste from its production into the Sea of Okhotsk.

Types of offshore platforms:

fixed oil platform;

offshore oil platform, freely fixed to the bottom;

semi-submersible oil drilling platform;

mobile offshore platform with retractable legs;

drilling ship;

floating oil storage (FSO) - a floating oil storage facility capable of storing oil or storing and shipping offshore;

floating oil production, storage and offloading unit (FPSO) - a floating structure capable of storing, offloading and producing oil;

oil platform with stretched supports (floating base with tension vertical anchorage).

The four main components of an oil platform: hull, drilling deck, anchor system and drilling rig allow solving the problems of exploration and production of black gold in high water conditions.

The hull is essentially a pontoon with a triangular or quadrangular base supported by huge columns. Above the hull is a drilling deck that can support hundreds of tons of drill pipes, several cranes and a full-sized helipad. A drilling rig rises above the drilling deck, the task of which is to lower / raise the drill to the seabed. At sea, the entire structure is held in place by an anchor system. Several winches pull tightly on steel mooring lines anchored to the ocean floor, holding the platform in place.

Principle of operation

The process of oil production begins with seismic exploration. At sea, seismic exploration is carried out with the help of special ships, usually with a displacement of up to 3,000 tons. Such vessels unwind seismic streamers behind them, on which hydrophones (receiving devices) are located and create acoustic waves using an oscillation source (air guns). Shock acoustic waves are reflected from the layers of the earth, and, returning to the surface, are captured by hydrophones. Thanks to such data, two-dimensional and three-dimensional seismic maps are created, which show potential reservoirs with hydrocarbons. However, no one can guarantee that he has found oil until it gushes from the well.

So, after exploration, the drilling process begins. For drilling, the team assembles the drill in sections. Each section is 28 meters high and consists of iron pipes. For example, the EVA-4000 oil platform is able to connect a maximum of 300 sections, which allows you to go deep into the earth's crust for 9.5 km. Sixty sections an hour, the drill is lowered at that rate. After drilling, the drill is removed to seal the well so that oil does not leak into the sea. To do this, blowout control equipment or a preventer is lowered to the bottom, thanks to which not a single substance will leave the well. The preventer with a height of 15 m and a weight of 27 tons is equipped with control equipment. It acts like a huge sleeve and is able to block the oil flow in 15 seconds.

When oil is found, the oil platform can move to another location to search for oil, and a floating oil production, storage and offloading unit (FPSO) arrives in its place, which pumps oil from the Earth and sends it to refineries onshore.

An oil platform can be anchored for decades, regardless of any surprises of the sea. Its task is to extract oil and natural gas from the bowels of the seabed, separating the polluting elements and sending oil and gas to the shore.