RU2515657C1 - Universal submersible structure orange for oil/gas well drilling and method of its operation - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: submerged structure operates at a depth within the range of 70 up to 120 m of the sea level. At that the base of the submerged structure is represented by a circular bearing plate/deck with process modules in the form of sectors; wells are located in the centre of the circular bearing plate/deck in the mouth module. At the base around the mouth modules in the sectors there are free moving vertical modules: living, drilling, operational, processing, power supply and conditioning ones. Inside the base of bearing plate/deck around the mouth module there are corridors: an inner and outer, at that the inner and outer corridors are interconnected by mutually perpendicular passages. Between the inner and outer corridors there is a circular ballasting container; under the outer corridor there are mutually perpendicular electric propulsion units. The method ensures operation of the above universal submersible structure.

EFFECT: improving safety and quality of performed operations both in process of well drilling and operation.

11 cl, 5 dwg

Description

The invention relates to underwater structures and is intended for the development of hydrocarbon resources in those areas of the Arctic Ocean, which for a long time or are constantly covered with ice fields difficult for Arctic icebreakers, while drilling using the traditional “surface” method is impossible.

Known subsea drilling complex for the development of hydrocarbon deposits on the shelf of the Arctic seas (M.I. Weinerman, OKEdelev - Subsea drilling complex for the development of hydrocarbon deposits on the shelf of the Arctic seas, railway "Drilling and Oil", No. 10, 2008), calculated landing on the seabed, including: an underwater drilling vessel (PBS), in which are located: a drilling rig; power equipment; a water separating column and crew accommodation, equipped with mooring, moving along guides and fixing in a predetermined position; bottom base plate (DOP), on which operational equipment and systems are installed that provide transportation of extracted raw materials to the consumer and an underwater supply vessel (PSD), designed for periodic delivery and replenishment of drilling tools, pipes and bulk materials.

PBS is formed of modules in the form of separate strong cylindrical cases, united by the outer case in a single design.

The disadvantage of this structure is: the presence of a complex and weighted shell shell of the drilling complex, which complicates the operation of the underwater drilling complex at depths of more than 300 m, i.e. the actually proposed complex (or rather, the ship) can be used at shallow depths of up to about 100 m (while the real depths of the Arctic Ocean shelf are much larger), in addition, the limited space of the PBC does not allow placing traditional designs of drilling equipment.

The invention RU 2011128912 of July 13, 2011, in which drilling is carried out traditionally, i.e. from surface semi-submersible installation (PPBU).

The disadvantage of this invention is the danger of its use due to possible breakdowns of the control system by the ice field, which will lead to an indefinite lengthening of the drilling stage of the field and potential environmental disasters.

The technical result of the claimed universal underwater structure (UPS "Orange") is:

- acceleration of field commissioning due to its year-round use;

- improving the safety and quality of work both during drilling and during operation of wells due to extremely stable conditions for the underwater structure to stay at depths from 70 to 120 m;

- reducing the metal consumption of the sealed shells of the modules, which in the surface space would require significant costs associated with increasing strength due to ice impacts, as well as reducing energy costs associated with the fight against ice slide.

The proposed technical solution is illustrated by drawings, where:

figure 1 shows a longitudinal section of a circular support base plate / deck with wellhead module;

figure 2 is a section aa in figure 1;

figure 3 - shows a longitudinal section of a General view of the Assembly 9 of the underwater structure (UPS "Orange");

figure 4 is a section bB in figure 3;

figure 5 is a perspective view of an underwater structure;

1 - circular support plate / deck with wellhead module;

2 - one of the technological / functional modules / sectors;

3 - wells;

4 - wellhead module in the form of a truncated cone;

5 - inner corridor;

6 - external corridor;

7 - perpendicular transitions between the corridors;

8 - circular sectioned ballasting tank;

9 - electric propulsion;

10 - module / sector oversized.

The underwater structure (UPS “Orange”) operates submerged to a depth in the range from 70 to 120 m from sea level. The indicated interval of depths is most acceptable for a permanent stay of the UPS “Orange” due to the fact that, starting from depths of 70-80 m from sea level, the presence of ice formations and possible effects on the underwater structure are practically not observed, and an increase in depth of over 120 m from sea level leads to a significant thickening of the shell of the underwater structure to provide resistance from the action of hydrostatic pressure of water. These depths are very close for most submarines, which makes it possible to use the usual shell thickness in their manufacture. In addition, the depths offered for a universal underwater structure are distinguished by the following advantages:

- UPS will not experience wind load, but will only be under the influence of a relatively stable in time and direction of underwater current;

- at this depth the UPS will be in conditions of almost constant temperature, which is certainly positive for technological safety and reliability of the hull;

- environmental stability will positively affect the possibility of year-round drilling (there will be no long seasonal pauses).

The claimed underwater structure is characterized by: the necessary low mobility (its self-propulsion is practically not needed); resistance to long stay under water; sufficient streamlining to hold on the same predetermined place and adjustable buoyancy. A spherical shape that is rather flattened vertically meets these requirements. And since drilling and production vessels must have autonomous energy, engineering and technical (including water supply, heating and air regeneration) and the technological services proper, which operate in separate compartments, it is more expedient to arrange them sequentially in sectors, which is similar to an orange consisting of lobules - functional sectors 2.

The underwater structure consists of a base in the form of a supporting base plate / deck 1 (see Figure 1) and technological modules in the form of sectors 2 (see figure 2 and figure 3). The base 1 is a special technical device of circular shape, with its own adjustable buoyancy, in the center of which there are wells 3, in the so-called wellhead module 4 having the shape of a truncated cone, the configuration of which is close to the derrick (essentially all of the proposed modules are analogues of separately presented traditional "upper structures" of a conventional surface-mounted platform).

Around this circular module 4, on the support-bearing plate / deck, all functional modules are located in sectors 2, including the living module, which is intended for personnel serving the vessel, and all functional modules have their own buoyancy in order to remove them (if necessary) from the structure in whole, i.e. have the freedom of vertical movement.

Inside the support-bearing plate / deck around the wellhead module 4, corridors are installed: internal 5 and external 6; inner 5 - for communication between all modules (see Figure 2), and external 6 - for communication with mooring passenger and auxiliary vessels, and the outer and inner corridors are interconnected by mutually perpendicular transitions 7. Between these corridors there is a circular ballasting around the perimeter (for the purpose of immersion at a given depth), a tank 8, partitioned (with the aim of regulating the maintenance of the entire structure in a strictly horizontal position) by individual tanks. Mutually perpendicularly located electric propulsion devices 9 are installed under the outer corridor in order to keep the entire underwater structure at a given point (known as dynamic positioning).

If any module 2 fails, the claimed underwater structure provides for its replacement with a similar one by vertical lifting; for this purpose, all modules are endowed with their own adjustable buoyancy (it is not indicated in the figures so as not to "weight" the picture); in addition, the modular principle of the UPS configuration allows you to replace any of the sector modules if necessary (for example, a serious breakdown or the completion of its functional task).

Wellhead module 4 is designed for a certain number of wells (according to our estimates, from 17 to 30, depending on the geological and technical necessity) placed at a distance of 3 m from each other and has dimensions: in the base, with a diameter of 15-20 m and a height of 25 m ( and possibly up to 50 m, based on the size of a traditional drilling “candle” of 36 m) with a diameter in the upper part of the module 12-17 m, while a special crane-beam system is placed in the upper part, on which the upper power drive with the possibility of its movement in two mutually perpendicular Yarnykh directions to ensure that the drilling of wells to be placed in rows or in concentric circles in the module.

The underwater structure (UPS “Orange”) is composed of a wellhead (in the center of the base — the base-bearing plate / deck) and technological, functional modules — which are installed round-off according to the sectoral principle that closely resembles an “orange”.

The tightness of the connection of the modules during their docking is ensured by the use of pipes of elastic design. To do this, on the outside of the abutted walls around the entire perimeter, a bed / grooves / recesses are made, in which pipes of elastic design with fastening along the length of the bed / grooves / recess are laid as a gasket. These pipes are designed for an internal pressure of 2 MPa, sufficient for a depth of stay of an underwater structure of 70-120 m. The sealing principle is that when the modules 2 are joined together and with the supporting-bearing plate 1 in an elastic pipe laid in grooves , the design pressure is created, i.e. the pipe “swells”, creating the required tightness of the modules being joined.

Then, the underwater structure equipped with all necessary modules is towed to a given point; immersed and held in depth by de-ballasting and movers; connects to the seabed with a riser / columns, after which a well drilling process is carried out.

After completion of drilling operations for the construction of a given number of wells in the field, its individual functional (in this case, drilling) modules that have completed their tasks are "separated" from the base connected to the seabed by a certain number of water separating columns (not shown in the figures) and towed to the home port for appropriate technical inspection and further use at such facilities.

The vacant seats on the supporting base plate / deck are lowered using underwater tugs, by ballasting, the technological / production modules brought for the underwater structure, which are intended for further development of the field.

Such a layout of the modules on the basis allows you to remove those functional modules that have fulfilled their tasks, and instead of them install new ones in the vacant sectors, thus, after the completion of well construction, the drilling modules are replaced with technological ones: collection and preparation of reservoir products, pump and compressor stations. In this case, the extracted modules can be used in other fields.

Energy, water treatment, air conditioning and residential modules remain in place, provided that their performance indicators are able to meet new requirements.

The design of the circular base-bearing plate / deck allows, if necessary, the use of modules of different sizes (depending on the dimensions of the equipment to be placed), provided that the contours of the internal walls of the modules are congruent; this is clearly shown in FIG. 4 at 10, where the external (“perimetric”) wall of one of the modules extends beyond the contours of the overall dimensions of the entire underwater structure.

The sectorial shape of the complex allows you to push the external “wall” of the module a certain distance beyond the contours of the base-bearing plate, if only a technical solution of congruent equality is performed: between the end surfaces of sections 2 and the surface of the wellhead module 1, as well as between the side surfaces of sections 2. allows you to optimally place equipment on the basis, in accordance with the technological sequence of operations.

External corridor 6 allows you to accept and withdraw personnel from the underwater structure to the external environment, in special self-propelled capsules (SC), which are moored to the vessel (not shown in the figures). SC volume and dimensions are designed for the transportation of personnel and rather light bulky oversized cargo (the capsule provides special gateways for transfer / reception of bulky goods, such as casing and drill pipes, cement, clay powder, various chemicals, etc.) for moored passenger and / or auxiliary vessels.

Claims (11)

1. An underwater structure operating at a depth in the range from 70 to 120 m from sea level, including: a base in the form of a circular support-bearing plate / deck; wells are placed in the center of the base of the support-bearing plate / deck, in the wellhead module; on the basis of around the wellhead module in the sectors, functional modules with freedom of vertical movement are installed: residential, drilling, production, technological, energy and air conditioning; inside the base around the wellhead module the corridors are installed: internal and external; moreover, the outer and inner corridors are interconnected by mutually perpendicular transitions; between the inner and outer corridors a circular ballastable sectioned tank is installed; mutually perpendicularly located electric propulsors are installed under the outer corridor. 2. The underwater structure according to claim 1, characterized in that the base is a technical device of a circular shape with its own adjustable buoyancy. 3. The underwater structure according to claim 1, characterized in that the wellhead module has the shape of a truncated cone. 4. The underwater structure according to claim 1, characterized in that the internal corridor is used for communication between all modules, and the external corridor is used for communication with mooring passenger and auxiliary vessels. 5. The underwater structure according to claim 1, characterized in that the circular ballastable tank is partitioned around the perimeter by individual tanks with the aim of immersing to a given depth and regulating the maintenance of the entire structure in a horizontal position. 6. The underwater structure according to claim 1, characterized in that in the wellhead module, the well centers are located at a distance of 3 m from each other; the wellhead module has the following dimensions: diameter at the base of 15-20 m, height from 25 to 50 m, diameter at the top of the module 12-17 m; in the upper part of the wellhead module there is a special crane-beam system on which the upper power drive is installed with the possibility of its movement in two mutually perpendicular directions to ensure drilling of all wells placed in rows or along concentric circles. 7. The underwater structure according to claim 1, characterized in that the tightness of the connection of the modules when they are docked is ensured by using an elastic pipe that withstands an internal pressure of 2 MPa when the modules are docked. 8. The underwater structure according to claim 1, characterized in that it uses modules of different sizes, depending on the dimensions of the equipment being placed. 9. The underwater structure according to claim 1, characterized in that the external corridor is used to receive and withdraw personnel from the vessel to the external environment, through self-propelled capsules designed for transportation of personnel and a fairly light oversized cargo. 10. The method of operation of the underwater structure of claim 1, characterized in that the structure is immersed and held at a given depth using de-ballasting and propulsors; the base of the platform is connected by a water separating column / columns with the seabed; carry out year-round drilling of wells; after completion of drilling, the drilling modules are replaced by vertical lifting using ballasting and underwater tugs with technological / production modules for operating these wells, while the residential, production, energy and conditioning modules remain in place. 11. The method of operation of the underwater structure of claim 10, characterized in that when any module fails, it is replaced with a similar one by vertical lifting; all modules are endowed with their own adjustable buoyancy.

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