EA006866B1 - System and method of installing and maintaining an offshore exploration and production system having an adjustable buoyancy chamber - Google Patents

Abstract

A system and method of establishing an offshore exploration and production system is disclosed, in which a well casing is disposed in communication with an adjustable buoyancy chamber and a well hole bored into the floor of a body of water. A lower connecting member joins the well casing and the chamber, and an upper connecting member joins, the adjustable buoyancy chamber and a well terminal member. The chamber's adjustable buoyancy enables an operator to vary the height or depth of the well terminal member, and to vary the vertical tension imparted to drilling and production strings throughout exploration and production operations. Also disclosed is a system and method of adjusting the height or depth of a wellhead while associated vertical and lateral forces remain approximately constant. A variety of well isolation members, lateral stabilizers and anchoring means, as well as several methods of practicing the invention, are also disclosed.

Description

FIELD OF THE INVENTION

The present invention relates in a broad aspect to the exploration and production of oil and gas, while a specific, non-limiting embodiment of the invention relates to the installation and maintenance of a system for offshore exploration and drilling, equipped with a camera with adjustable buoyancy.

State of the art

In order to search and extract hydrocarbon reserves in the world, numerous attempts have been made using a very large number of different systems and methods. Initially, these efforts were limited to ground operations, which used simple but effective drilling methods to ensure satisfactory extraction of resources from large productive deposits. However, as the number of known productive deposits decreased, in search of new resources it became necessary to explore more and more remote deposits and move on to offshore drilling. Over time, the development of powerful drilling systems and the improvement of signal processing techniques have made it possible for oil and gas producers to conduct exploration of hydrocarbon resources suitable for extraction practically anywhere in the world.

Initially, deepwater exploration and production efforts included the implementation of costly large-scale drilling operations in conjunction with the use of storage and transportation systems based on tankers. This principle, primarily, was due to the fact that most areas of offshore drilling are associated with complex and dangerous marine conditions. As a result, large-scale operations provided the most stable and cost-effective approach to the exploration and production of hydrocarbon resources. However, the preference given to large installations has the main drawback that exploration and production organizations have little incentive to use small fields. Indeed, the potential return on invested funds is usually complicated by the long time gap between exploration and the start of production (typically 3 to 7 years). In addition, the use of conventional platforms and the drilling and production equipment used with them requires large investments. Further, the complexity of legal regulation and regulation, as well as the desire to avoid any risks specific to this industry, has led to standardization, which leaves operators with few opportunities to make significant changes to the prevailing approach. As a result, offshore drilling operations have traditionally been complicated by the presence of large time gaps between investment and profit, unacceptable cost overruns and slow and inflexible production strategies determined by working conditions.

Relatively recently, offshore deposits have been discovered, in relation to which it becomes possible to avoid a significant part of the dangers and instabilities inherent in mining operations. For example, potential offshore areas for offshore areas in West Africa, Indonesia, and Brazil have been identified for which the surrounding marine and weather conditions are relatively mild and calm compared to other, less stable areas, such as the Gulf of Mexico or the North Sea. It is expected that these recently discovered sites will be able to provide favorable production performance and a high level of successful exploration results, as well as allow organizing production using simple drilling technologies similar to those used on land or offshore installations.

However, in accordance with the lognormal (lognormal) distribution, serviceable reserves tend to be distributed over a large number of small deposits. At the same time, each of them is able to produce less than is usually required in order to justify the costs of traditional large-scale production. For this reason, such areas to date have remained underdeveloped and, accordingly, their potential was not fully utilized. As a result, although a large number of potentially productive small deposits have already been discovered, for economic reasons they remain undeveloped. Given this circumstance, exploration and production organizations adapted their technologies in an effort to achieve higher profitability by reducing the scale of operations, as well as using other methods to reduce costs. As a result, production from smaller fields becomes more financially attractive, and the time gap between investment and profit is narrowing.

For example, in the published patent application I8 2001/0047869 A1, as well as in a number of other applications and patents related to this application, various methods for drilling deep-water wells are proposed, according to which the drilling system can be adjusted so as to achieve a higher oil recovery factor, than in traditional fixed well technologies. However, the system described in these patent publications cannot be tuned during completion of drilling, testing and well operation. In addition, this system is ineffective in cases where the wellbore begins in the vertical direction at the boundary of the silt on the seabed. The known system is also unsuitable under a wide range of surface loads and, therefore,

- 1 006866, it has limited capabilities with respect to the flexibility that is desirable for drillers in the process of actual penetration.

US Pat. No. 4,233,737 describes a method aimed at solving the problems associated with conventional vertical drilling operations. This method involves placing a group of interconnected horizontal pipes in the form of a whip directly above the seabed (in conjunction with a blowout preventer and other necessary equipment). Then, with the help of a drive or a remotely controlled mechanism, this lash is inserted with force in the horizontal direction into the drilling zone. However, this system is not flexible enough in that it cannot be used in practice at the final stages of drilling and well testing. The method proposed in this patent is all the more unable to provide the required functionality at the stages of production or operations to increase well production. In other words, the solutions of this patent may be useful only in the initial stages of well sinking, i.e. they cannot be considered as systemic solutions for the implementation and maintenance of deepwater exploration and production operations.

Other operators of offshore (offshore) rigs attempted to solve the problems associated with deepwater drilling by increasing the initial level of a subsea well by placing the submerged wellhead above an autonomous rigid tubular structure that is held in tension by a gas-filled chamber with buoyancy (lift) ) For example, as can be seen from US Pat. No. 6,196,322 B1, ANapIc Essryua1sg Tse11po1odo Ηο1άίη§ Ogoir has developed a system called artificial submarine base (IPO). This system is essentially a gas-filled chamber that has buoyancy, is connected to one or more segments of the pipe string and is installed at a depth of 180 to 300 m from the surface of the water. After the IPO head is equipped with a blowout preventer (at the drilling stage) or wellhead production fittings (at the production stage), the IPO system reports the lifting force and tension to the lower connecting component and all piping components inside it. The blowout preventer and riser at the drilling stage and wellhead production valves at the production stage are supported by the lifting force generated by the buoyancy chamber. The displacement of the borehole head is controlled within acceptable limits due to the vertical tension created due to the buoyancy of the IPO.

However, the ABapBk IPO system has several practical drawbacks. For example, the aforementioned US patent No. 6196322 directly limits the installation area of the camera, which has buoyancy, depths at which the influence of surface waves is negligible, that is, more than 150 m from the surface of the water. Specialists in the relevant technical field will understand that placing the camera at such depths is an expensive and rather risky decision. Indeed, the installation and maintenance of the system in a given position can in this case be carried out only by deep-sea divers or remotely controlled devices. In addition, in order to initiate production from the well, a relatively expensive transport system must be additionally installed between the upper part of the chamber and the bottom of the interacting surface vessel with it.

The well-known IPO system is also unsuitable for use in conjunction with an anchoring system that uses several anchors, even in situations where there is a significant probability of collision with soils that are difficult to drill. Moreover, the known system does not contain any control means for adjusting settings or vertical tension, or the depth of immersion of the wellhead during the operations of production and overhaul of the well. In addition, the said patent contains direct recommendations against the use of lateral stabilizers, which would allow the wellhead to be installed at shallow depths, which exert a stronger influence from tidal forces and surface waves.

SUMMARY OF THE INVENTION

Thus, there is clearly a widespread need to develop a system and method for installing the head of a subsea well so that operators have the ability to adjust the depth of its submersion, as well as the vertical tension applied to the pipe columns used in both exploration and production operations. There is also a need to create a system based on a camera with adjustable buoyancy that can maintain approximately constant tension acting on the corresponding drill or production string, as well as provide the ability to adjust the height of the wellhead at any time during the exploration and production stages by releasing additional stretch of stretch cables from component for adjusting the height of the camera. There is also a need to create a system for offshore exploration and production that can easily adapt to conditions of great depths or shallow waters without the need for configuration for a specific operational depth.

- 2 006866

List of drawings

In FIG. 1 shows, in side view, a system for marine exploration and production, in which, with the aim of adjusting the height (depth) of the well head, a camera with adjustable buoyancy is used.

FIG. 2A and 2B illustrate, in side view, a system for offshore exploration and production in which the transverse and vertical forces exerted on a camera with adjustable buoyancy, while adjusting the height of the wellhead by releasing additional stretches of tension cables, are kept approximately constant.

Information confirming the possibility of carrying out the invention

In accordance with the specific, non-limiting embodiment of the invention shown in FIG. 1, a system for offshore exploration and production comprises a casing fastening 2 mounted inside a subsea well 1 and a buoyancy chamber 9. At the same time, a lower connecting component 5 is installed between the indicated mount and the adjustable buoyancy chamber. According to an option that seems to be preferable, the inside of the well 1 is accessed from above through the well bore 3, which is drilled in the surface of the seabed. Typically, the casing included in the fastener 2 is installed in the wellbore in a strong and reliable manner, after which they are fixed in position with a cement mortar in accordance with known technology. In other embodiments, casing pipes are installed with high reliability inside the wellbore 3, after which a component for transporting a fluid, such as a pipe of a smaller diameter or a string of pipes, is introduced into the formed mount. After the specified position of the introduced component for transporting the fluid is ensured, it is fixed relative to the fastening by 2 casing pipes using cementing or a packer. Specialists in this field should be clear that although the considered option corresponds to the case of a single well, without going beyond the scope of the present invention, the proposed system for offshore exploration and production can be easily adapted to work simultaneously on a group of closely spaced wells.

According to one embodiment of the invention, between the fastening 2 of the casing and the lower connecting component 5 is a component 4 for blocking the well. This component 4 for blocking the well may contain one or more ball valves, which, in the case of removal of the lower connecting component 5, can be closed and thereby effectively close the well. In other embodiments, the wellbore closure component 4 may comprise a blowout preventer or shear ram, which may be in a normally open or closed state in order to provide access to the contents of well 1 or, conversely, to block access to it.

In other embodiments, the lower connecting component 5 contains one or more docking (receiving) elements located and configured to interact with a fastener installed on the component 4 for blocking the well. Alternatively, on the contrary, the lower connection component 5 comprises a fastener element for attaching the lower connection component 5 to the receiving element provided on the well shutoff component 4. Methods and means for rigidly attaching the lower connecting component 5 to the component 4 for blocking the well are well known to those skilled in the art. These means in the context of the present invention can be based on one or more fastening technologies and, in particular, can be hydraulic couplings, various units using bolts and nuts, welds, fittings (with or without sealing gaskets), hydraulic crimping and etc.

Similarly, the lower connecting component 5 may comprise any known connecting means suitable for performing the specific functions provided by the operators of the system of the invention. For example, in various embodiments of the invention, the lower connecting component 5 comprises one or more segments of a vertical pipe, riser, or frame. In some embodiments, the lower connecting component comprises a concentric element, for example, an element for transporting a fluid with a smaller outer diameter than the inner diameter of the frame within which it is mounted.

In other embodiments, the lower connecting component 5 is connected to one or more lateral stabilizers 6, which, in conjunction with a plurality of tension cables 7, determine the horizontal displacement of the system. Due to the use of the lifting forces created by the camera 9 with adjustable buoyancy, the lower connecting component 5 is in a tense state and is held in a stable position.

Alternatively, one or more stabilizers 6 define the horizontal displacement of the lower connecting component 5. In this case, the height (depth) of the well head 14 is controlled by varying the length of the upper connecting component 12. In some embodiments, the vertical tension of the lower connecting component 5 is maintained approximately constant, while the height ( depth) of the head 14 of the well can be adjusted. According to other options, the height (depth) of the head 14 of the well is maintained approximately constant, while the vertical tension

- 3 006866 The lower connection component 5 created by the variable buoyancy chamber 9 can be adjusted. There are also options in which both the height (depth) of the borehole head 14 and the vertical tension acting on the lower connecting component 5 are kept approximately constant, while using the transverse stabilizers 6 and one or more tension cables 7, the position is adjusted in transverse direction (horizontal plane).

In some embodiments, one or more of the tension cables 7 are individually adjustable, while in other embodiments, the adjustment of the tension cables 7 is done together. There are also options according to which the adjustment of the tension cables 7 can be carried out both jointly and individually. Variants are also contemplated in which one or more lateral stabilizers 6 are coupled to tension measuring means. This makes it possible to impart a fixed or predefined transverse tension to the lower connecting component 5 in order to more accurately control the lateral displacement of the system. In some embodiments, the tension cables 7 are fixed to the seabed by means of anchors 8, for example, self-absorbing (vacuum) anchors. Alternatively, traditional design anchors may be used.

In an embodiment of the invention, which is preferred, the adjustable buoyancy chamber 9 is approximately annular in shape, so that the lower connecting component 5 can be guided through the cavity provided in the central part of the buoyancy control chamber. In other embodiments, the adjustable buoyancy chamber 9 comprises a plurality of internal compartments. There are also options according to which each of these compartments is individually configured, i.e. to better control the buoyancy of the chamber, different amounts of air or gas (or other fluid) can be pumped into separate compartments. According to one embodiment, the adjustable buoyancy chamber 9 also contains ballast fluid that can be removed from the chamber, thereby giving the chamber greater buoyancy (lifting force) and create additional vertical tension acting on the lower connecting component 5. Specialists in this it should be understood that as a ballast fluid serving to enhance or limit buoyancy, various fluids may be used. An example of such an environment, which is both inexpensive and easily accessible, is compressed air.

In some embodiments, the variable buoyancy chamber 9 is further provided with an inlet valve for supplying ballast thereto. In this case, ballast fluid may be pumped into the chamber from an external source, for example, from the ground or from a remotely controlled mobile device via a split line. Thanks to this, the operator can achieve the desired buoyancy (lift) characteristics by supplying a certain amount of compressed gas to the chamber 9 with adjustable buoyancy. In other embodiments, the inlet valve is associated with one or more pumps or compressors, which allows the ballast fluid to be supplied under high pressure into the chamber, thereby providing a faster and more reliable change in buoyancy to the desired value.

In other embodiments, the variable buoyancy chamber 9 is further provided with an exhaust valve for removing ballast from it. In cases where air or another light fluid is injected into the chamber with adjustable buoyancy, while water or other heavy fluid is removed from the chamber, the chamber with adjustable buoyancy acquires additional buoyancy and, accordingly, increases the vertical tension acting on the lower connecting component 5. Conversely, if water or other heavy fluid is injected into the camera with adjustable buoyancy while air is being removed from the camera, the camera with adjustable buoyancy will lose Ie to buoyancy, thereby weakening the vertical tension acting on the lower connecting component 5.

In alternative embodiments, the exhaust valve is associated with one or more pumps or compressors, which allows you to remove the ballast from the chamber with adjustable buoyancy more quickly and reliably. In some embodiments, the exhaust valve is connected to a split line so that ballast removed from the buoyancy controlled chamber can be assembled on the surface or reused. In any case, the fundamental advantage of the present invention is the availability of various means of controlling the supply and removal of ballast, which makes it possible to control the buoyancy of the chamber and, accordingly, the tension parameters, as well as the height of the head 14 of the well at any time during both exploration and well operation.

According to further variants of the invention, the camera 9 with adjustable buoyancy is connected with one or more tension cables 10, designed to attach this camera to the seabed. As in the previous case, the tension ropes 10 are fixed on the seabed using the well-known anchoring technology, for example, by means of self-absorbing (vacuum) anchors or traditional anchors. One or more tension cables 10 can also provide additional stability of the system in the transverse direction, especially when performing operations involving the use of more than one well. According to one of the options one

- 4 006866 or more tension ropes 10 pass from the chamber 9 with adjustable buoyancy to the surface, where they are attached to additional chambers with adjustable buoyancy, floats, surface vessel, etc. Thus, additional tension in the transverse direction and increased stability of the system are achieved. In other embodiments, individual or joint control of the tension cables 10 is provided. In accordance with further embodiments, one or more tension cables 10 are individually or jointly adjustable.

In accordance with one of the options, the camera 9 with adjustable buoyancy is functionally connected with the component 11, perceiving vertical tension. According to another embodiment, the vertical tension sensing component 11 is provided with a tension measuring means (for example, a torque or strain gauge). The presence of such a tool allows you to apply a force that creates the vertical tension of the lower connecting component 5, in a more manageable and efficient manner. In another embodiment, the lifting force applied to the vertical tension sensing component 11 is adjusted by adjusting the length of the tension cables 10 while maintaining the buoyancy of the chamber 9 with adjustable buoyancy (i.e., the lifting force generated by it) is approximately constant. In yet another embodiment, the buoyancy of the variable buoyancy chamber 9 is controlled using one or more individually selectable outlet openings distributed over the surface of the variable buoyancy chamber through which excess ballast fluid is discharged into the sea. In this case, the open or closed state of the outlet is individually determined using the outlet controllers (such as plugs, kingstones, etc.).

In a preferred embodiment, the system according to the invention is designed so that the well head 14, which is located above the adjustable buoyancy chamber 9, is submerged to a depth where it can be serviced and checked by divers using lightweight and flexible diving equipment. In particular, the immersion depth of the borehole head may be 30-100 m. In some embodiments, the borehole head 14 is submerged only to the minimum depth necessary to provide access to the hulls of various surface vessels serving the borehole. In this case, the head 14 of the well may be at a substantially shallower depth, for example, lying in the range of 15-30 m. In alternative embodiments, taking into account specific operating conditions, the head 14 of the well may be either at a depth of less than 15 m or exceeding 100 m There are also options in which the head 14 of the well is located on or above the surface of the water, so that a blowout preventer or wellhead production armature (for example, like a Christmas tree) are installed by workers located on a service platform yoke or on board a surface vessel. Such a variant of the surface Christmas tree avoids the installation of a long riser column, which is usually necessary in the case of deep water wells. In addition, the installation of a borehole head on or near a water surface will also allow inspections and maintenance by scuba divers or crews operating from the water surface, without the need for expensive and lengthy operations using remotely controlled vehicles.

In some embodiments, the wellhead 14 may include a blowout preventer or wellhead well reinforcement. In an embodiment that is preferred, the wellhead 14 includes both a blowout preventer and wellhead wellheads to simplify operations associated with accessing the well.

In some embodiments, the lower connecting component 5 is completed at a level within the cavity existing in the central part of the annular chamber 9 with adjustable buoyancy. Starting from this level, fluids are transported upward to the wellhead through the upper connecting component 12. According to other options, the lower connecting component 5 does not end inside the cavity formed in the central part of the annular chamber with adjustable buoyancy, but passes through this cavity and then functions as the upper a connecting component 12 located between the camera with adjustable buoyancy and the borehole head. In other embodiments, between the camera 9 with adjustable buoyancy and the upper connecting component 12 is a component 11 that receives vertical tension. In this case, the lifting force generated by the camera with adjustable buoyancy is applied to this component 11 and transmitted through it to the drill or production casing located below the camera with adjustable buoyancy.

In some embodiments, the upper connecting component 12 further comprises a well shutoff component 13, which may comprise one or more ball valves or blowout preventers. These valves are used to interrupt the flow of fluids in the event that the head 14 of the well is removed or taken out of service, for example, in connection with tests or maintenance. Specialists in this field should be clear that the specific types and specific location of the shutoff valves as part of the component 13 included in the system according to the invention can be selected in a flexible way. The only essential requirement is that these valves must be able to open the fluid flow from the well.

- 5 006866 zhina 1, and also to block this flow during the periods of testing and maintenance, as well as in emergency cases associated with ensuring the safety of work.

For example, the head 14 of the well can be equipped with gushing, so that a flexible pipe from a surface vessel can be connected to the system according to the invention, after which the well can be launched. Alternatively, the borehole head 14 may terminate with a blowout preventer in order to eliminate the possibility of an ejection during drilling. In other options already mentioned, the well head 14 may include a blowout preventer and wellhead well reinforcement in order to simplify operations associated with access to the well.

In FIG. 2A and 2B show specific but non-limiting embodiments of the invention. These options relate to a system and method for forming a height-adjustable wellhead. The system includes a lower pipeline 21 for transporting fluids, an inner casing 22, an outer casing 23, and a well head 24. In some embodiments, a well shutoff component 25 is installed above the wellhead 24, allowing, when desired, to shut off or lock the well.

In the example of FIG. 2A, this well shutoff component 25 includes one or more ball valves that can be selectively opened or closed by an operator. The lower connecting component 26 contains one or more internal sealed seals 27 and a calibrated polished channel 28, and an element 29 for transporting fluids is installed inside this component. The height of this element within the housing of the lower connecting component 26 can be adjusted depending on the vertical lifting forces generated by the camera 30 with adjustable buoyancy. The pipeline determining the height of the upper connecting component located between the camera 30 with adjustable buoyancy and the head 36 of the well may have a different length. In some embodiments, an element 35 for blocking the well, such as a ball valve or blowout preventer, may be associated with an upper connecting component located between the chamber 30 and the well head 36.

In some embodiments, the system of the invention is secured to the seabed with one or more anchor braces 31 connected to first vertical tension means 32a. In this case, raising or lowering the camera 30 with adjustable buoyancy is carried out by winding (releasing) and winding one or more tension cables 37, which are located between the second means 32b, perceiving vertical tension, and means 33 for adjusting the height of the camera with adjustable buoyancy. When the adjustable buoyancy chamber 30 rises, a vertical tension is applied to the vertical tension sensing member 34, which in turn raises the well head 36, i.e. moves it towards the surface.

According to the exemplary embodiment shown in FIG. 2B, the height of the borehole head 36 and the height of the fluid transporting member 29 are controlled by increasing the length of the tension cables 37 by means of adjustable buoyancy chamber height adjustment means 33. In this case, the tension of the anchor braces 31 and the tension cables 37 both in the vertical and transverse directions remains approximately constant. In one embodiment, during this adjustment process, the vertical tension acting on the lower connection component 26 is also kept approximately constant, since the fluid transporting element 29 moves vertically inside the case of the lower connection component 26. According to another embodiment, the system further includes a second chamber with adjustable buoyancy, which serves to maintain a constant tension acting on the lower connecting to component 26 during the execution of the described height adjustment of the wellhead.

The description given is for illustration only and should not be construed as describing all possible aspects of the present invention. Indeed, although the present invention has been presented and described by way of examples of several preferred options, it will be understood by those skilled in the art that various other modifications and additions can be made to the form and details of the invention without departing from the scope and scope of the invention.

Claims (17)

CLAIM 1. A system for offshore exploration and production, comprising (a) a casing (2) in contact with a subsea well, (b) a camera (9) with adjustable buoyancy, and (c) a lower connecting component (5) installed between the casing column (2) and chamber (9) with adjustable buoyancy. 2. The system according to claim 1, characterized in that it further comprises (a) one or more chambers (9) with adjustable buoyancy or - 6 006866 (b) a casing in contact with a well made in the surface of the seabed; or (c) a well shutoff component (4) mounted between an adjustable buoyancy chamber (9) and a lower connecting component (5), wherein (ί) a well shutoff component (4) comprises one or more ball valves or a blowout preventer preferably provided with a shear ram, or (ίί) the lower connecting component (5) preferably comprises a receiving element for interacting with a fastening element provided on the component (4) for blocking the well, or a receiving element for interactions actions with a fastening element available on the component (4) for blocking the well. 3. The system according to claim 1, characterized in that the lower connecting component (5) further comprises (a) a riser or (b) a vertical pipeline; or (c) a framework; or (d) a fluid transporting element mounted inside said lower connecting component and preferably made adjustable in height depending on the lifting force generated by the variable buoyancy chamber (9). 4. The system according to claim 1, characterized in that the lower connecting component is connected with one or more transverse stabilizers (6), and (a) one or more transverse stabilizers (6) are adjustable transverse stabilizers or (b) one or more lateral stabilizers (6) are connected to one or more tension cables (7), and (ί) one or more tension cables (7) includes one individually adjustable tension cable or individually adjustable tension cables or (ίί) one or more tension cables wire ropes (7) us with one or more anchors (8). 5. The system according to claim 2, characterized in that one or more chambers (9) with adjustable buoyancy are made in the form of chambers having an approximately annular shape, and the lower connecting component (5) is carried out in the axial direction through the cavity formed in one of cameras with adjustable buoyancy, having an approximately annular shape. 6. The system according to claim 2, characterized in that one or more chambers (9) with adjustable buoyancy contain internal compartments. 7. The system according to claim 1, characterized in that the chamber (9) with adjustable buoyancy contains (a) ballast in the form of a fluid, preferably in the form of compressed gas, or (b) an inlet valve for supplying the ballast to the chamber, the inlet valve being connected (ί) with one or more detachable lines and with a remotely controlled mobile unit or (and) with a pump, or (ίίί) with a compressor; or (c) an exhaust valve for removing ballast from the chamber, the exhaust valve being connected (ί) to one or more detachable lines and to a remotely controlled mobile unit, and / or to a pump, or (ίίί) to a compressor. 8. The system according to claim 1, characterized in that the camera (9) with adjustable buoyancy (a) is connected to one or more tension cables (10), and (ί) one or more of the tension cables (10) includes one individually an adjustable tension cable or individually adjustable tension cables enter or (ίί) one or more tension cables (10) are connected to one or more anchors; or (b) is operatively coupled to a component (11) sensing vertical tension and preferably operably connected to a tension measuring means, preferably comprising a torque sensor; or (c) immersed in water to a depth of 30-100 m; or (d) immersed in water to a depth of less than 30 m; or (e) immersed in water to a depth of more than 100 m; or (e) is connected to an upper wellbore component, preferably comprising (ί) a ball valve or (ίί) a blowout preventer, preferably provided with a shear ram; or (g) is connected to the upper connecting component (12), which is preferably connected to the head (14) of the well, preferably containing (ί) wellhead exploitation fittings or (ίί) blowout preventer, or (ίίί) and wellhead exploitation fittings and blowout preventer . 9. The system according to claim 1, characterized in that the head (14) of the well mounted above the chamber (9) with adjustable buoyancy is located above the surface of the water. - 7 006866 10. A method of installing and maintaining in a predetermined position a system of marine exploration and production, including the following operations: (a) installing the casing (2) in the subsea well; and (b) installing the lower connecting component (5) between the specified casing (2) and the chamber (9) with adjustable buoyancy. 11. The method according to claim 10, characterized in that it further includes the following operations: (a) one or more adjustable buoyancy chambers (9) are connected to the casing (2) and preferably the casing (2) is cemented inside the borehole (3) drilled in the seabed, (b) between the camera (9) with an adjustable using buoyancy and a lower connecting component (5), component (4) is installed to shut off the well, and component (4) is used to shut off the well, containing (ί) one or more ball valves, or (ίί) a blowout preventer, preferably equipped with a shear ram, or (ίίί) mounting ele a moment for attaching said component to a receiving element present on the lower connecting component (5), or (ίν) a receiving element for interacting with a fastening element present on the lower connecting component (5). 12. The method according to claim 10, characterized in that the installation of the lower connecting component (5) further includes (a) installing a riser or (b) installing a vertical pipeline; or (c) installing the frame; or (d) installing an element for conveying fluids inside said lower connecting component, the length of one or more tension cables being adjusted to adjust the position of the element for conveying fluids in height; or (e) linking the lower connecting component to one or more transverse stabilizers (6), wherein (ί) the lower connecting component (5) is connected to one or more adjustable transverse stabilizers or (or) one or more transverse stabilizers (6) are connected to one or more tension cables (7), preferably with one or more adjustable tension cables, or one or more tension cables (7) are connected to one or more anchors (8). 13. The method according to claim 11, characterized in that it further includes the following operations: (a) install one or more chambers (9) with adjustable buoyancy, made in the form of chambers having an approximately annular shape, and preferably conduct the lower connecting component (5) in the axial direction through the cavity formed in one or more chambers with adjustable buoyancy, having an approximately annular shape; or (b) install one or more chambers (9) with adjustable buoyancy, containing internal compartments. 14. The method according to claim 10, characterized in that the camera (9) with adjustable buoyancy, containing (a) ballast in the form of a fluid, preferably compressed gas; or (b) an inlet valve for supplying ballast to it, wherein (ί) the inlet valve is connected to one or more disconnected lines and with a remotely controlled mobile unit or (ίί) the inlet valve is connected to the pump, or (ίίί) the inlet valve is connected to the compressor ; or (c) an exhaust valve for discharging ballast from it, wherein (ί) an exhaust valve is connected to one or more detachable lines and a remotely controlled mobile unit or (ίί) an exhaust valve is connected to a pump, or (ίίί) an exhaust valve is connected to a compressor . 15. The method according to claim 10, characterized in that the camera (9) with adjustable buoyancy (a) is connected with one or more tension cables (10), and (ί) the camera (9) with adjustable buoyancy is connected with one or more tension cables individually adjustable cables, or (ίί) tie one or more tension cables (10) to one or more anchors; or (b) is coupled to a vertical tension sensing component (11), which is preferably operatively associated with a tension measuring means, and functional linking of the vertical tension sensing component to a tension measuring means includes the use of a tension measuring means in the form of a load cell; or (c) immersed in water to a depth of 30-100 m; or - 8 006866 (g) is immersed in water to a depth of less than 30 m; or (e) immersed in water to a depth of more than 100 m; or set the head (14) of the well above the chamber (9) with adjustable buoyancy, placing the specified head (14) above the surface of the water; or bind the adjustable buoyancy chamber (9) to a well shutoff component (4), preferably containing (ί) a ball valve and / or blowout preventer, preferably equipped with a shear ram, or bind the variable buoyancy chamber (9) to the upper connecting component (12), preferably associated with the head (14) of the well, and the upper connecting component is preferably additionally associated (ί) with a blowout preventer or (and) with wellhead production valves, or (ίίί) and with stiven operational fittings, and with blowout preventer. 16. The use of a system for offshore exploration and production comprising (a) a casing (2) installed in a subsea well, (b) a camera (9) with adjustable buoyancy, and (c) a lower connecting component (5) installed between the casing (2) and a chamber (9) with adjustable buoyancy, for exploration and production of oil and gas. 17. Oil and gas produced using the method of installing and maintaining in a predetermined position a system of marine exploration and production, including the following operations: (a) installing the casing (2) in the subsea well; and (b) installing the lower connecting component (5) between the specified casing (2) and the chamber (9) with adjustable buoyancy.