Rich deposits of oil and gas have been discovered on the shelf of the Barents Sea, including the world-famous Shtokman gas condensate field with reserves of more than 3 trillion. cube m of gas. The development of this unique field alone will in the future make it possible to satisfy the gas needs of the entire north-west of Russia for many years. The Pechora Sea shelf is one of the most promising in terms of oil content among the Arctic seas of Russia. Currently, five deposits have been explored in this region. The largest of them is the Prirazlomnoye oil field with a proven oil reserve of 65.3 million tons.

Leading enterprises in oil and gas exploration of the Arctic shelf and in offshore exploration drilling are Murmansk enterprises and companies included in the ArcticShelf Association:

The shelf contains a quarter of our oil reserves and half of our gas reserves. They are distributed as follows: Barents Sea - 49%, Kara Sea - 35%, Okhotsk Sea - 15%. And only less than 1% is located in the Baltic Sea and the Caspian Sea.

The most favorable conditions for oil formation are marine, with the so-called uncompensated subsidence. In warm waters, at the bottom of the prehistoric sea, sapropel accumulated for centuries - clay soil mixed with the organic remains of dead fish, algae, mollusks and other living creatures. The biochemical stage of oil formation was going on in it. Microorganisms, with limited access to oxygen, processed proteins, carbohydrates, etc. This produced methane, carbon dioxide, water and some hydrocarbons. This stage took place a few meters from the seabed. Then the sediment became compacted: diagenesis occurred. As a result of natural processes, the bottom of the sea sank, and the sapropel was covered with materials that, due to natural destruction or water flows, were carried away from the mountains. Organic matter found itself in stagnant, oxygen-free conditions. When the sapropel dropped to a depth of 1.5 km, the underground temperature reached 100°C and became sufficient for oil formation. Chemical reactions between substances begin under the influence of temperature and pressure. Complex substances are broken down into simpler ones. Biochemical processes die out. Then the rock should be covered with salt (in the Caspian depression its thickness reaches 4 km) or clay. As the depth increases, the content of dispersed oil increases. Thus, at a depth of up to 1.5 km, gas formation occurs, at an interval of 1.5-8.5 km, the formation of liquid hydrocarbons - micro-oil - occurs at temperatures from 60 to 160°C. And at great depths at temperatures of 150-200°C, methane is formed. As the sapropel compacts, micro-oil is squeezed out into the overlying sandstones. This is the process of primary migration. Then, under the influence of various forces, the micro-oil moves up the slope. This is secondary migration, which is the period of formation of the deposit itself.

The whole process takes hundreds of millions of years. This is how oil was formed on the Barents Sea shelf.

1 Ice gas condensate

2 North – Kildinskoye

3Ludlovkhskoye gozovoye

4 Shtokman gas condensate field

5 Murmansk Gas

The project to produce the first Russian Arctic oil entered its active phase in mid-2013. Prirazlomnaya ensures the implementation of all technological operations, including drilling wells, production, storage, preparation and loading of oil to tankers. “Prirazlomnaya” is the world’s first stationary platform from which they began to produce oil on the Arctic shelf in the difficult conditions of drifting ice fields.

The platform's supporting base - the caisson - is a unique design: it bears the main load and the reliability of the entire platform depends on its reliability. It is the caisson part that allows Prirazlomnaya to successfully withstand the Arctic climate, protect all equipment and ensure the safe operation of personnel. The height of the caisson is 24.3 meters, i.e. almost equal to the height of a nine-story building.

In the caisson of the Prirazlomnaya offshore ice platform there is an oil storage facility consisting of 16 compartments, and all other technological complexes and platform systems are located above it. Oil storage tanks use a “wet” method of storing oil - that is, they are constantly filled with either oil or water. This storage method eliminates the formation of any explosive atmosphere, which is an additional condition for the safety of the platform.

The Prirazlomnaya offshore platform is equipped with two sets of direct oil loading devices (DOC), operating on the basis of a crane system and allowing tankers to be loaded from the platform’s oil storage facility. COUPONS are located at opposite ends of the platform, which makes it possible for tankers to easily approach the platform in any weather and navigation conditions.

COUPON devices are equipped with a special nasal receiving device. Oil is shipped through one of the devices depending on the direction of external loads (waves, ice drift, currents, wind). COUPON tracks tanker movements in a 180° sector. If it deviates from the sector served by one device, the tanker is unmoored and moved to another COUPON.

Oil loading scheme

Particular attention is paid to safety issues: oil shipment begins only if 30 necessary conditions are simultaneously met. The oil transfer line to the tanker is equipped with an emergency stop and closure system, which, if necessary, allows the shipment to be stopped almost instantly - in a maximum of 7 seconds.

Before the start of loading operations, the shuttle tankers "Mikhail Ulyanov" and "Kirill Lavrov", equipped with a bow loading system, carry out contactless mooring, during which the distance from the tanker to the Prirazlomnaya offshore ice sheet is 80 ± 6 m. To prevent an involuntary collision with the platform, they are equipped with a system dynamic positioning, which, despite the wind and waves, allows you to keep the tanker in place. The tanker loading speed can reach up to 10 thousand m3/hour, which allows loading a tanker with ARCO oil in 8-9 hours. Specialized vessels equipped with the latest powerful emergency oil-gathering equipment for working in winter conditions are constantly on duty near the platform.

The new grade of oil produced at the Prirazlomnoye field is called ARCO - from the initial letters English words"Arctic" and "oil". The new grade of oil first entered the world market in April 2014.

ARCO oil has a high density (about 24 API) and a sulfur content of about 2.3%, as well as a low wax content. Relatively heavy compared to conventional Russian export crude, ARCO is well suited for deep processing at refineries in northwestern Europe. It produces unique chemical products that can be used in road construction, tire production, the space and pharmaceutical industries.

Stages of development of shelf fields

1. For last decades in industrial developed countries worldwide interest in the problem of developing oil and gas resources of the seas and oceans has increased significantly. This is due, firstly, to the intensive growth in the consumption of fuel and energy raw materials in all spheres of industry and agriculture, and secondly, to the significant depletion of oil and gas resources in most oil and gas bearing areas, where the possibilities for further noticeable growth of industrial reserves on land have been exhausted .

The total surface of the World Ocean makes up 71% of the Earth's surface, of which 7% is on the continental shelf, which harbors a certain potential reserve of oil and gas.

The continental shelf, or continental shelf, in geological and topographical terms is a continuation of the land towards the sea. This is the zone around the continent from low water level to the depth at which the bottom slope changes sharply. The place where this happens is called the edge of the continental shelf. Usually the edge is conventionally placed at a depth of 200 m, but there are cases when sharp increase slope occurs at depths of more than 400 m or less than 130 m. In cases where the zone below the low water level is extremely irregular and contains depths much greater than those typical of the continental shelf, the term “borderland” is used.

Fig.1.1. Profile of the continental shelf.

In Fig. 1.1. the profile of the continental shelf is presented. The coastline 2 is followed by the continental shelf 5, beyond the edge 4 of which the continental slope 5 begins, descending into the depths of the sea. The continental slope begins on average from a depth of C = 120 m and continues to a depth of C = 200-3000 m. The average steepness of the continental slope is 5°, the maximum is 30° (off the eastern coast of Sri Lanka). Behind the foot of slope 6 there is an area of ​​sedimentary rock deposition, the so-called continental rise 7, the slope of which is less than that of the continental slope. Beyond the continental rise, the deep-water plain part of the 8th sea begins.

According to American oceanographers, the width of the continental shelf ranges from 0 to 150 km. On average, its width is about 80 km.

The study showed that the depth of the shelf edge, averaged over the entire globe, is approximately 120 m, the average slope of the continental shelf is 1.5-2 m per 1 km.

There is the following theory about the genesis of the continental shelf. Approximately 18 - 20 thousand years ago, such an amount of water was contained on continental glaciers that the sea level was significantly lower than today. In those days, the continental shelf was part of the land. As a result of melting ice, the shelf sank under water.

At one time, shelves were considered to be terraces formed as a result of wave erosion. Later they began to be considered as a product of sedimentary rocks. However, ground research data do not fully agree with any of these theories. It is possible that some areas of the shelf were formed as a result of erosion, while others were formed due to the deposition of sedimentary rocks. It is also possible that the explanation lies in both erosion and sedimentation.

Scientific and practical interest in the continental shelf has increased significantly in recent decades, and this is due to its diverse natural resources.

Results of prospecting and exploration work for oil and gas in the coastal areas of the World Ocean and on the continental shelf, carried out in last years in many countries of the world, confirm these assumptions.

By the early 1980s, more than 100 of the 120 countries with access to the sea were searching for oil and gas in areas of the continental shelf, and about 50 countries were already developing oil and gas fields. The share of oil production from offshore fields worldwide amounted to 21%, or 631 million tons, and more than 15%, or 300 billion tons, of gas.

Over the entire period of exploitation of offshore fields, at the beginning of 1982, about 10 billion tons of oil and 3.5 trillion. gas.

The largest areas of offshore oil and gas production are the Gulf of Mexico, Lake. Maracaibo (Venezuela), North Sea and Persian Gulf, which account for 75% of oil production and 85% of gas production.

Currently total number offshore production wells worldwide exceed 100 thousand, and oil is produced at sea depths of up to 300 m. Exploration drilling covers sea depths from 1200 m in the Gulf of Mexico and up to 1615 m on the island. Newfoundland (coast of Canada).

Deep prospecting and exploration drilling in water areas is carried out from artificial islands in shallow water, with jack-up floating drilling rigs (FDR) at sea depths of up to 100 m, semi-submersible floating drilling rigs (SSDR) with sea depths of up to 300-600 m, and floating drilling vessels at great depths.

Thus, at present, the main areas of offshore drilling abroad continue to be the North Sea, the Asian part of the Pacific shelf zone and the Gulf of Mexico (USA).

As experience in the development of oil and gas resources on the sea and ocean shelves shows, despite large capital investments, the extraction of hydrocarbons from offshore fields provides significant benefits. Profits from the sale of oil and gas produced on the shelf cover expenses by 4 times. Exploration and exploration costs in offshore areas range from 10 to 20% of the total costs of developing offshore fields.

Total capital investments in the development of offshore oil and gas fields depend on climatic conditions, sea depth and the remoteness of the fields from onshore service bases, on the recoverable reserves of the field, well flow rates and, finally, on scientific and technological progress in the field of automation of the entire drilling process, offshore development fields, production, field collection, preparation and transportation of oil and gas in marine conditions.

In the USA, for example, capital investments in the development of oil and gas fields vary depending on reserves from $30 million with reserves of 2 million tons to $2 billion with reserves of 300 million tons.

An important indicator of the effectiveness of capital investments in the development of oil and gas fields is the specific cost per unit of production. The largest deposits require lower unit costs for their development than deposits located in similar conditions, but with smaller reserves. So, for example, when developing small offshore fields abroad with reserves of 2-5 million tons of oil (or 2-5 billion m 3 of gas), unit costs are 180-340 dollars per 1 ton of oil produced and 150-300 dollars. per 1000 m 3 of gas. Specific costs for developing medium-sized fields with reserves of 5-50 million tons of oil or 5-50 billion gas turned out to be in the range from 84 to 140 dollars per 1 ton of oil produced and from 43 to 84 dollars per 1000 m3 of gas. For large offshore oil and gas fields with reserves of more than 50 million tons of oil or 50 billion m3 of gas, the specific costs for their development are, respectively, 60-115 dollars per 1 ton of oil and 20-30 dollars per 1000 gas.

When developing offshore fields, a significant part of capital investments is directed to the construction and installation of platforms, operational equipment and pipeline construction, which for medium-sized oil fields amounts to 60-80%. Therefore, the unit costs of developing offshore fields are significantly affected by sea depth. For example, at a sea depth of 120 m in Brazil, they amount to $100 per 1 ton of oil produced, while on the lake. Maracaibo in Venezuela with water depths of 5 m - $6.

In the North Sea, the specific costs per 1 ton of oil produced are $48 at sea depths of 80 m and $60-80 at depths over 100 m, while in the Persian Gulf, due to large well flow rates, the specific costs of developing oil fields at sea depths of 90 m are only $16/t.

In the Gulf of Mexico, unit costs from fields at sea depths of 50 m turned out to be equal to $20.

Promising direction development of oil and gas resources located at great depths - the creation and widespread implementation of underwater systems for the exploitation of offshore fields. Leading research and design institutes in developed countries are working on this problem.

In the North Sea, underwater well development has been carried out since 1971 at sea depths of 70-75 m, first at the Ekofisk field and then at the Argill field.

An analysis of the efficiency of developing offshore fields abroad showed that the net income received for the entire period of development of medium-sized fields (with reserves of more than 20 million tons of oil or more than 50 billion gas) amounts to more than $1 billion.

The economic benefit from the development of offshore fields in the USA and Mexico amounted to up to $10 for every dollar spent. As oil prices increase, the economic efficiency of offshore field development increases accordingly.

The exploitation of offshore fields is considered profitable with minimal recoverable oil reserves of 2.3 million tons and 6.2 billion gas in the Gulf of Mexico; 7.9 million tons of oil and 15.9 billion in Cook Inlet; 18.5 million tons of oil and 45.3 billion tons of gas in the Beaufort Sea.

The payback period for capital investments in the preparation and development of large oil and gas fields (with reserves of more than 50 million tons) is up to one year, and in Arctic conditions this period increases to 10-20 years.

The experience of developing oil and gas fields in the Caspian Sea also shows the economic feasibility of this work.

When developing any riches of the sea, a person has to create special technical technological means taking into account the peculiarities of their development.

Long-term practice of developing offshore oil and gas fields both in our country and abroad shows that for the effective use of their reserves, traditional methods of development and operation used on land are not always acceptable.

The experience of developing oil and gas fields in the Caspian Sea, accumulated by Azerbaijani oil workers in close collaboration with workers in other industries of the country, makes it possible to reveal and show the characteristic technical and technological features of oil and gas production at sea, rational methods for their intensification, as well as the main factors contributing to the increase oil recovery of reservoirs.

The features of the development of offshore oil and gas fields include the following.

I. Creation, taking into account the harsh marine hydrometeorological conditions, of special hydraulic structures of new floating technical facilities (floating crane installation vessels, service vessels, pipe-laying barges and other special vessels) for geophysical, geological prospecting work and the construction of oil field facilities at sea and their maintenance during the development process , drilling, operation and repair of wells, as well as during the collection and transportation of their products.

II. Drilling directional clusters of wells from individual stationary platforms, from overpass platforms, on artificially created islands, from jack-up and semi-submersible floating installations and other structures both above and below water.

III.Solution of additional technical, technological and
economic tasks in designing the development of oil, gas and gas condensate fields. These include:

1. Widespread use of analytical methods for a more complete study of the characteristics of oilfield processes. To control the processes of offshore oil and gas production, information only about a specific point in the reservoir is not enough; it is important to know the integral parameters that characterize the reservoir as a whole. Simulation models most adequately reflect the real object. It has been established that when modeling it is possible to use a sampling method, which allows one to determine integral parameters from a sufficiently small sample of data.

The use of this and other mathematical methods, as well as various diagnostic methods using computers, is becoming an urgent necessity, since with their help it is possible to successfully solve the issues of designing and managing the processes of rational and efficient development of offshore oil and gas fields.

2. Selection when designing the most rational well pattern for a given field or reservoir, which should have such a density that compaction is not required, since in marine conditions this is associated with extremely great difficulties due to the already existing field development system and the network of underwater communications , when the placement of new hydraulic structures for drilling additional wells may be impossible.

3. Selection of rational designs and the number of stationary platforms, trestle platforms, floating production decks and other structures for placing the optimal number of wells on them (depending on the depth of the formations, the timing of the wells, the distance between their wellheads, their flow rates expected with the existing wellheads) pressures, etc.).

4. The use of progressive methods of intensifying oil and gas production to increase oil and gas recovery from reservoirs, while not allowing the methods of influencing the reservoir to lag behind the rate of production, is the main principle.

5. Application of intensification methods to increase the coverage of the formation both in area and in its thickness (in multi-layer fields).

To rationally solve the technical and economic problems of developing oil and gas fields and in the interests of speeding up their exploitation, it is necessary to widely apply methods of joint separate exploitation of multi-layer deposits.

This will accelerate the pace of development of multi-layer fields and reduce the number of production wells.

6. Accelerating the construction of wells by creating reliable equipment and advanced technology for drilling directional target wells with the necessary deviation from the vertical and ensuring the autonomy of the work of drilling crews (so that their work does not depend on the hydrometeorological conditions of the sea) in the cramped conditions of platforms, overpass and other sites, which allows for short term complete the drilling of all designed wells and only after that begin their development, eliminating the need for simultaneous drilling and operation of wells.

7. Correspondence of the durability and reliability of hydraulic engineering and other structures to the development periods of oil and gas fields, i.e., the period of maximum oil extraction from the deposit and the entire field as a whole.

IV. Creation of specialized onshore bases for the manufacture of hydraulic structures, modular technological complexes, floating facilities and other objects for drilling, oil and gas production, construction and maintenance of offshore oil production complexes.

V. Creation of the latest, more advanced technical means for the development, operation and repair of wells in offshore conditions.

VI. Solving the issues of simultaneous drilling, operation and repair of wells at small distances between their wellheads, when this is associated with a long construction period.

VII. Creation of small-sized, high-power, reliable block automated equipment in a modular design to speed up the construction of drilling facilities, operation and repair of wells and the arrangement of platforms for the collection and transport of extracted products in offshore conditions.

VIII. Solving research and design problems to create a new, completely different from traditional technology and equipment for drilling, operating and repairing wells with an underwater wellhead location and servicing these objects both underwater and on special floating facilities.

IX. Development of equipment and technology for the development of sea and ocean shelves in particularly harsh hydrometeorological conditions, when it is necessary to create very expensive structures for drilling, development, oil and gas production, transportation of products in conditions of drifting ice, icebergs, frequent hurricanes
winds, strong bottom currents, etc.

X. Creation of special technical means and technological processes, as well as floating installations and physical and chemical substances that ensure protection marine environment, as well as the air basin during geological prospecting, geophysical and drilling operations, operation and repair of wells, collection and transportation of their products and maintenance of the multifaceted oil field facilities of developed offshore oil and gas fields.

XI. Solving a set of problems to create technical means and take special measures for labor protection of personnel, which is dictated by the need to safely carry out work in a limited area under increased noise, vibration, humidity and other harmful conditions, when the creation of cultural, social and sanitary measures to protect the health of offshore oil and gas producers especially important.

XII. Special physical and psychological preparation of workers and engineering personnel for work in marine conditions. Training offshore oil and gas producers on safe methods of work when developing underwater fields. Wherein Special attention should be given to the training of divers and aquanauts, since the accelerated and safe execution of work on the development of great sea depths and uninterrupted maintenance of offshore oil and gas production processes largely depend on their professional training.

XIII. Creation of a hydrometeorological service and observation points for forecasting and timely provision of short-term and long-term information on weather conditions required for offshore oil workers to take safety measures.

XIV. Providing fire safety teams and services for the prevention and elimination of gas and oil gushers with special equipment for carrying out work to localize and eliminate gushers and fires in marine conditions.

Taking into account these features and compliance with the requirements for the rational development of oil and gas fields.

2. In the practice of constructing oil and gas wells at sea, geological exploration drilling is carried out from floating drilling units (FDR):

Drilling ships;

Drilling barges;

Floating installations of self-elevating, semi-submersible and submersible types.

One of the main factors influencing the choice of the type of drilling watercraft (DFS) is the depth of the sea at the drilling site.

PBS are primarily classified according to the method of their installation above the well during the drilling process, separating them into two main groups (classes):

1. Supported when drilling on the seabed:

Floating submersible drilling rigs (FDU - submersible drilling rigs).

Jack-up floating drilling rigs (jack-up rigs);

2. Drilling while floating:

Semi-submersible drilling rigs (SSDR);

Drilling vessels (DS).

Submersible drilling rigs (SDUs) are used for work in shallow water. As a result of the lower displacement hulls or stabilizing columns being filled with water, they are installed on the seabed. The working platform is above the water surface both during the drilling process and during transportation.

Jack-up floating drilling rigs (JDRs) are used primarily in exploratory drilling in offshore oil and gas fields in water areas with water depths of 30-120 m or more. Jack-up rigs have large hulls, the buoyancy reserve of which ensures towing the unit to the place of work with the necessary technological equipment, tools and material. The supports are raised during towing, and at the drilling point the supports are lowered to the bottom and sunk into the ground, and the hull is raised along these supports to the required design height above sea level.

Semi-submersible drilling rigs (SSDR) and drilling vessels (DS) are in working condition afloat and are held using anchor systems or a dynamic stabilization system.

SSDRs are used for geological exploration work at water depths from depths of 90-100 m to 200-300 m with an anchor holding system above the mouth of a drilled well and over 200-300 m with a dynamic stabilization (positioning) system.

Drilling vessels (DS), due to their higher maneuverability and speed of movement, greater autonomy compared to SSDRs, are mainly used for drilling prospecting and exploration wells in remote areas at sea depths of up to 1500 m or more. Large reserves (up to 100 days of operation) ensure the drilling of several wells, and high speed movement (up to 24 km/h) - their quick relocation from a completed well drilling to a new point. The disadvantage of BS, compared to SSDRs, is their relatively greater limitation in operation depending on sea conditions. Thus, the vertical pitch of the BS during drilling is allowed up to 3.6 m, and the SSDR - up to 5 m. Since the SSDR has greater stability (due to the immersion of the lower pontoons up to 30 m or more) compared to the BS, the vertical pitch of the SSDR is 20 -30% wave height. Thus, the drilling of SSDR wells is practically carried out at significantly higher sea conditions than when drilling with BS. The disadvantage of a SSDR is the low speed of movement from a completed well to a new point.

The efficiency of offshore drilling depends on many natural, technical and technological factors, including the type of offshore drilling substrate used (Fig. 1.2). The choice of a rational type, design and parameters of an offshore drilling base is also influenced by many factors: purpose, depth of water and rocks, design, initial and final diameters of the well, hydrological and meteorological characteristics of the work, rock properties, drilling method, power and mass characteristics located on the basis of drilling mechanisms, equipment and tools.

The main hydrological and meteorological characteristics of the shelf that influence the choice of a rational type of drilling foundation are the following: sea depth in the drilling area, the degree of its waves, wind strength, ice conditions and visibility.

The maximum depth of the shelf in most marine areas is 100-200 m, but in some areas it reaches 300 m or more. Until now, the main object of geological research on shelves has been areas in coastal areas with water depths of up to 50 m and rarely 100 m. This is explained by the lower cost of exploration and development of fields at shallower depths and a fairly large shelf area with depths of up to 50 m. Confirmation of the shallowness of large shelf areas there are corresponding data on the seas washing the shores of Russia: the depth of the Sea of ​​​​Azov does not exceed 15 m; the average depth of the northern part of the Caspian Sea (area 34,360 square miles) is 6 m, the greatest – 22 m; the prevailing depths of the Chukchi Sea are 40 – 50 m, 9% of the area with depths of 25 – 100 m; 45% of the area of ​​the Laptev Sea with depths of 10 -50 m, 64% - with depths of up to 100 m; in the western and central parts of the East Siberian Sea the predominant depths are 10–20 m, in the eastern parts 30–40 m, the average sea depth is 54 m; the prevailing depths of the Kara Sea are 30 – 100 m, the depths of the coastal shallows are up to 50 m; the prevailing depths of the Baltic Sea are 40 - 100 m, in the bays - less than 40 m; average depth White Sea 67 m, in bays - up to 50 m; the prevailing depths of the Barents Sea are 100-300 m, in the South-Eastern part 50-100 m; the depths of the Pechora Bay (length about 100 km, width 40-120 km) do not exceed 6 m.

The main shelf zone explored by geologists is a strip with a width ranging from hundreds of meters to 25 km.

Structural mapping

Exploration

Ice regime

Coastal outlines

Bottom topography

Bottom soil

Temperature

Rice. 1.2. Factors influencing the effectiveness of offshore well drilling

The distance of well placement points from the shore when drilling from fast ice depends on the width of the fast ice strip and for the Arctic seas reaches 5 km.

The Baltic, Barents, Okhotsk Seas and the Tatar Strait do not have conditions for quickly sheltering watercraft in the event of a storm due to the lack of closed and semi-closed bays. Here, it is more effective to use autonomous MODUs for drilling, since when using non-autonomous installations it is difficult to ensure the safety of personnel and the safety of the installation in stormy conditions. Working near steep, steep and rocky shores that do not have a sufficiently wide beach area poses a great danger. In such places, when a non-autonomous MODU breaks away from its anchors, its death is almost inevitable.

In the shelf areas of the Arctic seas there are almost no equipped berths, bases and ports, therefore, issues of life support for drilling rigs and ships serving them (repair, refueling, shelter during a storm) must be given attention here special meaning. In all respects, the best conditions are found in the Japanese and Russian inland seas. When drilling in areas remote from possible shelter sites, a weather forecast warning service must be well established, and the watercraft used for drilling must have sufficient autonomy, stability and seaworthiness.

Mining and geological conditions are characterized mainly by the thickness and physical and mechanical properties of the rocks intersected by the well. Shelf deposits are usually composed of loose rocks with inclusions of boulders. The main components of bottom sediments are silts, sands, clays and pebbles. Sandy-pebble, loam, sandy loam, sandy-silty, etc. deposits can form in different proportions. 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% of drilled wells and 10-12% wells from their total number.

The thickness of loose sediments rarely exceeds 50 m and varies from 2 to 100 m. The thickness of layers of certain rocks ranges from several centimeters to tens of meters, and the intervals of their occurrence in depth do not obey any pattern, with the exception of silts, which are in most cases located at bottom surface, reaching 45 m in “calm” closed bays.

Bottom sediment rocks, with the exception of clays, are incoherent and easily destroyed during drilling (II-IV categories in terms of drillability). The walls of the wells are extremely unstable and, without fastening, collapse after they are exposed. Often, due to significant water content of rocks, quicksand are formed. Lifting cores from such horizons is difficult, and drilling them is possible mainly by advancing the bottom of the well with casing pipes.

Under the loose sediments lies the weathering crust of bedrock with the inclusion of acute-angled pieces of granites, diorites, basalts and other rocks (up to category XII in terms of drillability).

A rational method of drilling a well is one that ensures sufficiently high-quality completion of the task at hand with minimal labor and material costs. The choice of this drilling method is based on a comparative assessment of its effectiveness, determined by many factors, each of which, depending on the geological and methodological requirements, purpose and drilling conditions, can be of decisive importance.

B.M. Rebrik recommends considering the effectiveness of a drilling method as a complex concept and combining factors into groups that reflect an essential aspect of the well drilling process or characterize the technical means intended for this purpose. In particular, he suggests that the effectiveness of the method of drilling engineering-geological wells should be determined by three groups of factors: engineering-geological, technical and economic.

In principle, this grouping is also acceptable for drilling wells for other purposes. When choosing a rational drilling method, it should be assessed first and foremost by a factor that reflects the intended purpose of the well. If two or more drilling methods are identified that provide, even if different, but sufficient quality for completing the task, one should continue to evaluate them based on other factors. If the compared methods do not provide a high-quality solution to the geological or technical problem for which drilling is being carried out, then evaluating them, for example, by productivity and economic efficiency has no practical meaning.

The factors influencing the process and efficiency of offshore drilling are specific. They limit or completely exclude the possibility of using some methods and technical means recognized as effective for drilling wells for the same purpose on land. Based on this, it is proposed to evaluate the effectiveness of methods for drilling exploration wells at sea according to four indicators: geological information content, operational and technological capabilities, technical efficiency, and economic efficiency.

Geological information content is determined by the specific tasks of drilling exploration wells. When exploring mineral deposits, the geological information content of drilling methods is assessed by the quality of the sampled core. The core must provide a geological section and the actual parameters of the deposit: the lithological and granulometric composition of the drilled deposits, their water content, the boundaries of the productive formation, the size of the metal contained in it (during placer exploration), the content of useful components, the content of fine material and clay additives (during exploration of building materials ) and so on. To accurately determine these parameters, it is necessary to prevent enrichment or depletion of the selected core samples for each sampling interval.

The operational and technological capabilities of the drilling method are determined by the quality of the assigned task, its technical and economic efficiency.

The criteria for assessing technical efficiency are: instantaneous, average, trip, technical, park, cyclic drilling speeds; productivity per shift, season; time for performing individual operations, drilling the entire well or its individual interval; wear of equipment, casing pipes and tools; versatility; metal consumption; energy intensity; power; transportability of drilling equipment, etc.

All types of speeds and drilling productivity are determined by the time spent on performing a particular process or operation. When choosing a drilling method for sea conditions, the time factor is one of the most important criteria. Using high-speed drilling methods and technologies, many of the exploration wells can be started and completed during periods of good weather and daylight hours. This will allow you to avoid emergency situations that arise in the event of mothballing an undrilled well due to nightfall, storm, etc.

Economic criteria

Offshore oil production

We are on a drilling platform - a complex technical structure designed for oil production on the sea shelf. Coastal deposits often continue on the underwater part of the continent, which is called the shelf. Its boundaries are the shore and the so-called edge - a clearly defined ledge, behind which the depth rapidly increases. Usually the depth of the sea above the edge is 100-200 meters, but sometimes it reaches 500 meters, and even up to one and a half kilometers, for example, in the southern part Sea of ​​Okhotsk or off the coast of New Zealand.

Depending on the depth, different technologies are used. 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, often carries the risk of damaging 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. A less common technology is used when the desired area is surrounded by dams and water is pumped out from the resulting pit. At sea depths of up to 30 meters, concrete and metal overpasses were previously built on which equipment was placed. The overpass was connected to land or was an artificial island. Subsequently, this technology 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 monitor 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 well bore here was 11,680 meters. Drilling was carried out first in a vertical and then in a horizontal direction under seabed at the Chaivo field, 8-11 kilometers from the coast.

The deeper the water, the more complex technologies are used. At depths of up to 40 meters, stationary platforms are built, but if the depth reaches 80 meters, floating drilling rigs equipped with supports are used. Up to 150-200 meters, semi-submersible platforms operate, which are held in place using anchors or a complex dynamic stabilization system. And drilling ships can drill at much greater sea depths. Most of the “record-breaking wells” were carried out in the Gulf of Mexico - more than 15 wells were drilled at a depth of more than one and a half kilometers. The absolute deepwater drilling record was set in 2004, when the Transocean and ChevronTexaco drillship Discoverer Deel Seas began drilling a well in the Gulf of Mexico (Alaminos Canyon Block 951) at a sea depth of 3053 meters.

In the northern seas, which are characterized by difficult conditions, stationary platforms are often built, which are held on the bottom due to the huge mass of the base. Hollow “pillars” rise up from the base, in which extracted oil or equipment can be stored. First, the structure is towed to its destination, flooded, and then built right into the sea. top part. The plant where 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 designers of such platforms is to install a maximum of high-tech equipment in a minimum area, which makes this task similar to design spaceship. To cope with frost, ice, and high waves, drilling equipment can be installed directly at the bottom.

The development of these technologies is extremely important for our country, which has the most extensive continental shelf in the world. Most of it is located beyond the Arctic Circle, and the development of these harsh spaces is still very, very far away. According to forecasts, the Arctic shelf may contain up to 25% of global oil reserves.

Interesting Facts

• The Norwegian Troll-A platform, a striking representative of the family of large northern platforms, reaches 472 m in height and weighs 656,000 tons.
• Americans consider the date of the beginning of the offshore oil field to be 1896, and its pioneer is oilman Williams from California, who drilled wells from an embankment he built.
• In 1949, 42 km from the Absheron Peninsula, an entire village called Neftyanye Kamni was built on overpasses built to extract oil from the bottom of the Caspian Sea. Employees of the company lived there for weeks. The Oil Rocks overpass can be seen in one of the James Bond films - “The World Is Not Enough.”
• The need to maintain subsea equipment on drilling platforms has significantly influenced the development of deep-sea diving equipment.
• To quickly close a well in an emergency - for example, if a storm prevents the drilling ship from remaining in place - a type of plug called a "preventer" is used. The length of such preventers reaches 18 m, and their weight is 150 tons.
• The beginning of active development of the sea shelf was facilitated by the global oil crisis that erupted in the 70s of the last century. After the announcement of the embargo by 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, which by that time had reached 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 the starting point for the development of the North Sea shelf, but also gave the name to a new economic term. Economists called the Groningen effect (or Dutch disease) a significant increase in the value of the national currency, which occurred as a result of increased gas exports and had a negative impact on other export-import industries.

"Offshore mining" in books

PRODUCTION

From the book Hiking and Horses author Mamontov Sergey Ivanovich

PRODUCTION Residents told us that there was panic during the evacuation of the city. One of the trains went off the rails and blocked the tracks. “There, across the river, there are a lot of trains, and everything, everything was thrown into them.” I went to Colonel Shapilovsky. “Well.” Take two carts and some soldiers and

Production

From the author's book

Loot to the Lords of the mountains, forests and rivers of Russia. When the first frosts arrive, the air is especially tasty. It is filled with the aroma of withered herbs and imbued with frosty freshness. The grass, caught by the frost, crunches pleasantly underfoot, leaving wet boots on

Production

From the book Jews in Russia: the most influential and rich author Rebel Alina

Extraction Prohibitive legislation did not allow Jews to become full participants in the mining industry, which also rapidly developed in Russia in the 19th century. For example, in the Kingdom of Poland, Jews could mine coal only on land that belonged to them.

PRODUCTION

From the book Military mysteries of the Third Reich author Nepomnyashchiy Nikolai Nikolaevich

PRODUCTION (Based on materials from P. Knyshevsky and the newspaper “Moskovsky

2. Extraction

From the book Holy War by Reston James

2. Booty Of course, the city of Acre fell only thanks to the arrival of numerous French and English troops at its walls. But, as soon as they took this city, Richard and Philip began to divide the spoils among themselves, as if they alone had won this wonderful victory. Both

Pontida found on the shelf

From the book of Atlantis of the sea Tethys author

Pontida, found on the shelf However, most modern researchers are very skeptical about the hypotheses expressed by Pachulia and Solovyov. No traces of Dioscuria were found at the bottom of the Sukhumi canyon. But many finds were found on land, on the banks of the Sukhumi

Cities on the shelf

From the book of Ages and Water author Kondratov Alexander Mikhailovich

Cities on the Shelf PREVIOUS PAGE SHOWN: Ancient Phoenician ships (above). The pier of the ancient port on the Adriatic of the Yugoslav city of Dubrovnik. During the Middle Ages it played an important role in Mediterranean trade (middle panel, right). Venice. Ensemble

Production

From the book Creators and Monuments author Yarov Roman Efremovich

Shukhov had never seen anything like this before. Small fenced areas; in the corner of each there is a wooden tower with wooden outbuildings on the sides. How many are there? One, two, three... “Many,” said Sokolovsky. - Since oil production changed hands a few years ago

From the book Codex Russian Federation on administrative offenses (Administrative Code of the Russian Federation) author State Duma

From the book Code of the Russian Federation on Administrative Offenses author Laws of the Russian Federation

Article 8. 20. Illegal transfer of mineral and (or) living resources on the continental shelf and (or) in the exclusive economic zone of the Russian Federation Loading, unloading or transshipment on the continental shelf and (or) in the exclusive economic zone

From the book Code of the Russian Federation on Administrative Offences. Text with changes and additions as of November 1, 2009. author author unknown

Article 8.20. Illegal transfer of mineral and (or) living resources on the continental shelf and (or) in the exclusive economic zone of the Russian Federation Loading, unloading or transshipment on the continental shelf and (or) in the exclusive economic zone

From the book Criminal Code of Ukraine in jokes author Kivalov S V

Article 244. Violation of the legislation on the continental shelf of Ukraine 1. Violation of the legislation on the continental shelf of Ukraine, which caused significant harm, as well as failure of the person responsible for the operation of technological installations or other sources

Again about the Arctic shelf

From the book Newspaper Trinity Option # 42 author Trinity Option Newspaper

Again about the Arctic shelf Alexey Ivanov (Institute earth's crust SB RAS, Irkutsk) Let the foreigner, the rogue, remember, Let him wrap it around his mustache: Our Arctic shelf He won’t grab the treasured bite. This is our reliable guarantee - If anything happens, he will answer with his head - Glorious

LOOK FOR ATLANTIS ON THE SHELF

From the book 2008_43 (591) author Newspaper Duel

LOOK FOR ATLANTIS ON THE SHELF Views of gloomy depths crawl across the monitor screen. Vague shadows of what used to be beautiful ships, but now formless blocks froze at the bottom. Thus, with a demonstration of underwater filming footage taken during the recently ended joint

24. Can booty be taken from a strong man, and can captured people be taken from a victor? 25. Yes! Thus says the Lord: And those who are captives of the mighty will be taken away, and the spoil of the tyrant will be delivered; for I will contend with your adversaries, and I will save your sons; 26. And feed your oppressors

From the book The Explanatory Bible. Volume 5 author Lopukhin Alexander

24. Can booty be taken from a strong man, and can captured people be taken from a victor? 25. Yes! Thus says the Lord: And those who are captives of the mighty will be taken away, and the spoil of the tyrant will be delivered; for I will contend with your adversaries, and I will save your sons; 26. and

Rosneft and Gazprom are postponing geological exploration and the start of production at 31 offshore oil and gas fields for a period of two to 12 years. As a result, plans for oil production in the Arctic could decrease by almost 30%

Arctic, research expedition (Photo: Valery Melnikov/RIA Novosti)

Less oil from the shelf

Rosnedra agreed with Rosneft and Gazprom to postpone the dates of geological exploration and the start of production at 31 sites on the shelf of the Arctic, Far Eastern and southern seas, according to the department’s materials (RBC has a copy). At the request of Rosneft, plans for geological exploration at 19 sites were adjusted, and at another 12 for the needs of Gazprom and its subsidiary Gazprom Neft. We are talking about postponing the timing and scope of seismic exploration by an average of two to five years, and the timing of well drilling by an average of three years in each case.

The most significant delays in the commissioning of the largest fields - two sections of Gazprom's Shtokman field will be commissioned no earlier than 2025 instead of the previously planned 2016. And the Dolginskoye field of Gazprom Neft with reserves of 200 million tons of oil equivalent - from 2019 to 2031. The largest number of areas where company plans have been revised are located in the Pechora Sea (nine areas), eight in the Barents Sea, seven in the Okhotsk Sea, four in the Kara Sea, two in the Black Sea and one in the East Siberian Sea. For other fields, the start dates for production are not specified at all: they will be determined based on the results of completion of geological exploration.

An official representative of the Ministry of Natural Resources confirmed to RBC that Rosnedra at the request of companiesshelf licenses were updated. “Changes are made when documented. First of all, we are talking about changes in the economic and geological conditions of projects, including a slight change in the timing of drilling wells,” -Nikolai Gudkov, head of the press service of the Ministry of Natural Resources, told RBC.At the same time, companies are exceeding their obligations for seismic exploration on the shelf, he claims.

A representative of Gazprom Neft told RBC that the postponement of the start of production at the Dolginskoye field was due to the need for additional geological study, as an influx of gas was discovered, as well as economic reasons. Representatives of Rosneft and Gazprom did not respond to RBC’s requests.

By 2035, oil production on the Arctic shelf will be 31-35 million tons, Deputy Minister of Energy Kirill Molodtsov said at the Arctic 2016 conference in February. Previously, the draft Energy Strategy talked about achieving 35-36 million tons by this date in the Arctic, and in general on the shelf - 50 million tons per year. In addition, by 2035, at least 10% of all gas in the country should be produced on the shelf (total production in the country will be 821-885 billion cubic meters), the document states. In 2015, the companies produced 18.8 million tons of oil on the Russian shelf, 16 million tons of which on the shelf of the Sea of ​​Okhotsk, mainly at the Sakhalin-1 and Sakhalin-2 projects. And on the Arctic shelf, only 800 thousand tons were produced at the Prirazlomnoye field (owned by Gazprom Neft).

Due to the postponement of development of offshore fields, production in the Arctic by 20 30 year will be only 13 million tons, which is 27.8% less than plannedvolume (18 million), calculated Head of the Shelf Laboratory, Deputy Director of the Institute of Oil and Gas Problems of the Russian Academy of Sciences Vasily Bogoyavlensky. As a result, oil production on the Russian Arctic shelf in the next 10-15 years will not be able to compensate for the decline in production at existing fields on land, he told RBC.

Shelf of Rosneft and Gazprom

According to the subsoil law, licenses for offshore work are issued only to state-owned companies with relevant experience, namely Gazprom and Rosneft. Gazprom, according to the corporate magazine, owns 33 licenses to use the subsoil of the Russian continental shelf, and has four more licenses subsidiary company Gazprom Neft as an operator. Rosneft, according to the company, has 55 licenses on the shelf.

"Long Perspective"

“By the end of 2025, on the shelf of the Barents Sea, Gazprom must complete 20 thousand linear kilometers of 2D seismic exploration and 9 thousand square meters. km - 3D, and also drill 12 exploration wells, - says an article from the Gazprom corporate magazine (RBC has a copy). —Gazprom specialists believe that it is not only practically impossible to develop such volumes, but also impractical. It is obvious that drilling in areas in the Barents Sea, based on the current situation, is a fairly long-term prospect.” The fact is that since the summer of 2014, prices for Brent oil have fallen fourfold (in January 2016 they reached a minimum of $27 per barrel) and have not fully recovered - now oil is trading around $52 per barrel.

However, last year Gazprom did not completely curtail geological exploration on the shelf, but greatly reduced its pace, especially in terms of drilling, as follows from the corporate magazine. By order of Gazprom, in 2015 seismic exploration was carried out on only 6.7 thousand km, although over the past few years a total of 34 thousand km have been studied. The increase in proven hydrocarbon reserves based on the results of geological exploration on land and sea, according to Gazprom, in 2015 reached 582 million tons of standard fuel against the plan of 536 million tons.

Rosneft is currently developing the shelf more intensively, but is drilling wells only where it works together with foreign partners. This summer, the company plans to drill two wells at the Magadan-1 field in the Sea of ​​Okhotsk together with Statoil. But drilling in the Kara Sea at Universitetskaya-1 has been postponed indefinitely, since the partner of the state-owned company Exxon cannot participate in the project due to sanctions.

Before 2025, it will be more likely to begin oil production at those offshore fields of Rosneft where the company works with Western or Asian partners: in the Tuapse trough and the Western Black Sea area (Exxon and Eni), Magadan-1 (Statoil), Universitetskaya (Exxon ), Medynsko-Varandeysky area in the Barents Sea (CNPC) and North-Veninskoye field in the Sea of ​​Okhotsk (Sinopec). Participation in financing and access to technology depend on partners. Some of the projects have been frozen due to sanctions, says RBC’s interlocutor at Rosneft.

The most expensive and time-consuming part of offshore work is drilling wells. The average cost of drilling one well on the Arctic shelf is the Dean of the Geological Faculty of the Russian State University of Oil and Gas named after. Sergei Lobusev estimated Gubkin at $200-500 million. For example, the cost of drilling the Universitetskaya-1 well of Rosneft in the Kara Sea to open the Pobeda field exceeded $700 million. But in order to drill at least one well, it is also necessary to contract a drilling rig installation. And US and EU sanctions prohibit the provision of technologies and services for drilling to depths of more than 130 m to Russia.

According to Alexey Belogoriev, Deputy Director for Energy at the Institute of Energy and Finance, in the Energy Strategy until 2035 and the General Scheme for the Development of the Oil Industry of the Russian Federation until 2035, previous plans for offshore oil and gas production will be revised downward. According to the expert, there is no point in expecting the start of oil and gas production from new offshore fields before 2025. “This will not be economically viable at oil prices below $90 per barrel. In addition, there are no appropriate technologies for drilling in the Arctic, and access to Western ones is difficult due to sanctions,” he believes. According to the expert, the lost volumes of oil production on the shelf can be replaced by more intensive geological exploration on land and increasing the oil recovery factor.

"Now because of low prices for oil and gas, offshore development has slowed around the world. Companies are freezing work on the shelf. For us, this opportunistic delay plays into our hands. We have fallen behind in the deployment of our shipbuilding cluster at Far East“,” TASS quotes Deputy Prime Minister Dmitry Rogozin’s speech at a meeting of the Arctic Commission in early June.