RU2753888C1 - Device for compensation of loads on system of underwater column heads - Google Patents

Abstract

FIELD: subsea hydrocarbon production.

SUBSTANCE: invention relates to the field of subsea hydrocarbon production, in particular, to a device for compensating loads on a system of subsea casing heads, including a conductor string and a direction string. The proposed device for compensating the loads on the system of subsea casing heads, including the conductor string and the direction string, contains: a caisson; a cover defining an annular cavity from above, formed by the outer and inner annular walls, and made integrally with the caisson; a mechanism for fixing the caisson relative to the system of subsea casing heads, containing the first fixing means made with the possibility of fixing relative to the conductor string, and second fixing means adapted to be fixable relative to the direction string; linear movement means; a pump connected to the annular cavity of the caisson, a shut-off valve configured to operate to turn off the pump; and a caisson position sensor configured to be installed in the caisson fixing mechanism and capable of transmitting a signal for triggering a shut-off valve.

EFFECT: invention increases the reliability, durability and safety of operation of the system of subsea casing heads due to effective compensation of loads on the system of subsea casing heads.

5 cl, 3 dwg

Description

TECHNICAL FIELD OF THE INVENTION

The proposed invention relates to the field of subsea production of hydrocarbons, in particular, to a device for compensating loads on a system of subsea casing heads, allowing to compensate for such loads on the system of subsea casing heads as overturning moment.

LEVEL OF TECHNOLOGY

The prior art source known RU2632085C2, publ. 02.10.2017, IPC Е21В 43/017, Е21В 33/035, disclosing a system for installing flowing equipment for wells, including a caisson with walls extending downward, forming an internal volume between the walls, in which one or more ballast tanks are placed that regulate buoyancy. A pump is used to pump out water and other fluids from the internal volume.

Thus, it is known from the prior art to use a caisson in subsea well equipment to protect against environmental influences and to compensate for large loads on the equipment, in particular, the use of ballast tanks in the caisson design to prevent overturning effect on the caisson.

In addition, the prior art also known patent US5044830A, publ. 03.09.1991, IPC Е02В 17/00, revealing the structure of the gravity base for the offshore platform in the Arctic regions. This known structure has support columns, upper and lower plates having inner and outer protective walls passing between them to form a lattice structure for transferring impact energy from the outer wall to the inner wall, while the supporting columns lack means for transferring impact energy from the inner and external protective walls.

A disadvantage of the known invention according to US5044830A is that the design of the caisson shells and partitions does not allow sufficient resistance to the overturning moment.

As the closest analogue, the patent GB2566288A, publ. 03/13/2019, MPK В63В 21/27, E02D 27/52, Е21В 33/035, revealing the offshore caisson for use as a foundation and support for a subsea well for hydrocarbon production, providing integral support of the wellhead body, thereby absorbing bending moments, acting on the wellhead casing, for example, loads generated by a riser.

The disadvantages of the device according to the source GB2566288A is the lack of a mechanism for fixing the caisson relative to the system of underwater column heads, which leads to a shift and overturning of the structure as a whole.

DISCLOSURE OF THE INVENTION

The objective of the present invention is to provide a reliable, durable and safe device for compensating the loads on the system of subsea casing heads, the design of which effectively compensates for the loads acting on the system of subsea casing heads.

The technical result of the proposed invention is to improve the reliability, durability and safety of operation of the system of subsea casing heads due to improved technology for compensating the loads on the system of subsea casing heads.

The specified technical result is achieved due to the fact that the device for compensating the loads on the system of underwater column heads, including the conductor column and the direction column, contains: - a caisson having a central channel, concentrically located outer annular wall and inner annular wall, between which an annular cavity is formed; a cover that delimits the annular cavity from above and is made integrally with the caisson; - a mechanism for fixing the caisson relative to the system of underwater column heads, comprising the first fixing means made with the possibility of fixing relative to the conductor string, and the second fixing means made with the possibility of fixing relative to the direction string; - means of linear movement, made with the possibility of installing the locking mechanism relative to the inner annular wall of the caisson; - at least one pump capable of being connected to the annular cavity of the caisson and pumping out fluid from it; - caisson position sensor, made with the possibility of installation in the caisson fixation mechanism and with the possibility of transmitting a signal for actuation of the shut-off valve.

The proposed device may contain a group of guides configured to be placed around the system of underwater column heads in the central channel of the caisson.

The proposed device may contain a hydraulic connector for connecting a remote-controlled unmanned underwater vehicle, made with the possibility of activating the mechanism for fixing the caisson.

The first locking means and / or the second locking means of the caisson locking mechanism may include spherical bearings.

The means of linear movement can be a plurality of rail guides with a carriage.

The use of the caisson fixation mechanism relative to the underwater columnhead system in combination with the above technical features increases the efficiency of compensating the loads on the subsea columnhead system, in particular, increasing the resistance to such external influences as the overturning moment.

In the context of the present description, the words "upper", "lower", "first", "second", etc. are used as adjectives solely to distinguish the nouns to which they refer from each other, and not for the purpose of describing any specific relationship between these nouns.

BRIEF DESCRIPTION OF DRAWINGS

The following is a detailed description of the invention with reference to the drawings, in which:

in FIG. 1 schematically shows a general view of the proposed device installed relative to the system of underwater column heads;

in FIG. 2 schematically shows the locking means of the caisson locking mechanism according to one embodiment of the invention.

in FIG. 3 is a schematic top view of a caisson according to one embodiment of the invention.

CARRYING OUT THE INVENTION

The proposed device for compensating loads is illustrated in FIG. 1, installed relative to the system of subsea casing heads, including conductor string 1 and direction string 2. The proposed device for compensation of loads contains a caisson 3, which has a central channel 4, concentrically located outer annular wall 5 and an inner annular wall 6, between which an annular cavity 7 is formed. with caisson 3.

The proposed device for compensating loads also contains a mechanism 9 for fixing the caisson relative to the system of underwater column heads, containing the first fixing means 10, made with the possibility of fixing relative to the conductor column 1, and the second fixing means 11, made with the possibility of fixing relative to the column 2 of the direction. Both the first locking means 10 and the second locking means 11 of the locking mechanism 9 of the subsea string head system can be configured to comprise spherical bearings 12, as shown in FIG. 2, the spherical bearings 12 provide an additional degree of freedom. It will be apparent to a person skilled in the art that the locking mechanism 9 may be a hydraulic mechanism in which a piston moves the first and second locking means 10, 11, or mechanical. The end surface of the fixing mechanism 9 contains a hydraulic connector 13 for connecting a remotely controlled unmanned underwater vehicle, configured to actuate the mechanism 9 for fixing the caisson 3 of the underwater column head system.

The proposed device for compensating loads also contains means 14 of linear movement, made with the possibility of installing the locking mechanism 9 relative to the inner annular wall 6 of the caisson 3. In Fig. 1, it can be seen that the inner annular wall 6 of the caisson 3 has a configuration with a recess 14, which allows the installation of linear movement means 14 in it, and the linear movement means 14 are a plurality of rail guides with a carriage (not shown in the drawings), which, when the caisson 3 moves when deepening into the seabed 16 provides unloading of the mechanism 9 for fixing the caisson 3 from the forces caused by this movement.

A pump 17 is installed on the caisson 3, made with the possibility of connecting to the annular cavity 7 of the caisson 3 and pumping out of it a fluid medium, in particular seawater, which has entered the annular cavity 7 of the caisson 3 when it is lowered onto the seabed 16. FIG. 3 shows a top view of the caisson 3, on which four pumps 17 are installed, which is a special case of the number of pumps, which depends on the dimensions of the caisson and its power.

A shut-off valve 18 is connected to the caisson, made with the possibility of blocking the flow of fluid from the annular cavity 7 into the pump 17. The valve 18 receives a command to close the pump 17 in the event of the actuation of the sensor 19 of the position of the caisson 3 located in the locking mechanism 9. More specifically, the sensor 19 is configured to fit between the locking mechanism 9 and the direction column 2. Since the outer diameter of the conductor column 1 is less than the diameter of the direction column 2, the first and second fixing means 10, 11 are installed in the fixing mechanism 9 with the formation of a stepped structure, for this purpose the inner surface of the fixing mechanism 9 also has a stepped configuration with a step, which makes it possible to install the sensor 19 positions in the ledge zone in such a way that when the caisson is immersed to the required depth H, the sensor is triggered, while the depth H is determined by a specialist in engineering geology for each specific case, depending on the nature of the seabed soil and the required amount of load compensation. The sensor 19 of the position of the caisson 3 is triggered by transmitting a signal to the control system (not shown in the drawings), which generates a command to operate the shut-off valve 18 to turn off the pump 17 and the fluid from the annular cavity 7 stops flowing into the pump 17.

Additionally, the proposed device for compensating loads may contain a group of guides 20, each of which is configured to be placed in the central channel 4 of the caisson 3 around the system of underwater column heads.

According to one embodiment of the proposed device, the inner box 3 is divided into segments 21, as shown in FIG. 3, wherein fluid is pumped out from each segment 21 simultaneously.

The principle of operation of the proposed device for compensating the loads is as follows. The proposed device is lowered into the installation site with a removable tool for lowering and lifting. When lowering, guides 20 can additionally be used, centering the device relative to the system of underwater column heads, in particular, relative to the column 2 of the direction. When the caisson 3 reaches the seabed 16, the pump 17 is automatically turned on and the fluid is pumped out from the annular cavity 7 of the caisson 3, as a result of which a pressure difference between the environment and the annular cavity 7 of the caisson 3 is created, due to which the caisson 3 is buried in the seabed. At the moment of deepening the caisson 3 to the required value H, the position sensor 19 is triggered and transmits a signal to the control system (not shown in the drawings), which generates a command to operate the shut-off valve 18 to turn off the pump 17 and the fluid from the annular cavity 7 stops flowing into the pump 17.

Further, with the help of a remotely controlled unmanned vehicle, the mechanism 9 for fixing the caisson 3 is activated, while the first fixing means 10 are fixed relative to the conductor column 1, and the second fixing means 11 are fixed relative to the column 2 of the direction, in other words, the first fixing means 10 are pressed against the column 1 conductor and pressing the second fixing means 11 to the column 2 of the direction. Thus, the required degree of rigidity of fixing the system of subsea casing heads is provided. When the caisson 3 is deepened into the seabed 16, forces arise due to the movement of the caisson 3, the unloading of the fixing mechanism 9 from these forces is provided by means 14 of linear movement.

Modifications and improvements to the above-described embodiment of the present invention, without departing from the scope of the claims, will be apparent to those skilled in the art. The present description is presented by way of example only and does not impose any restrictions on the scope of protection of the invention. Thus, the scope of protection of the invention is limited only by the scope of the appended claims.

Claims (11)

1. A device for compensating loads on a system of subsea casing heads, including a conductor string and a direction string, containing: - a caisson having a central channel, concentrically located outer annular wall and an inner annular wall, between which an annular cavity is formed; a cover that delimits the annular cavity from above and is made integrally with the caisson; - a mechanism for fixing the caisson relative to the system of underwater column heads, comprising the first fixing means made with the possibility of fixing relative to the conductor string, and the second fixing means made with the possibility of fixing relative to the direction string; - means of linear movement, made with the possibility of installing the locking mechanism relative to the inner annular wall of the caisson; - at least one pump capable of being connected to the annular cavity of the caisson and pumping out a fluid from it, - a shut-off valve designed to operate to shut off the pump; - caisson position sensor, made with the possibility of installation in the caisson fixation mechanism and with the possibility of transmitting a signal for actuation of the shut-off valve. 2. The device according to claim. 1, containing a group of guides made with the possibility of placement around the system of underwater column heads in the central channel of the caisson. 3. The device according to claim. 1, containing a hydraulic connector for connecting a remotely controlled unmanned underwater vehicle, made with the possibility of activating the mechanism for fixing the caisson. 4. The apparatus of claim. 1, wherein the first locking means and / or the second locking means of the caisson locking mechanism include spherical bearings. 5. The device according to claim. 1, in which the means of linear movement are a plurality of rail guides with a carriage.

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