RU2765454C1 - Seal assembly - Google Patents

Abstract

FIELD: drilling soil or rocks; mining.

SUBSTANCE: invention relates to operation of offshore and surface wells and can be used for sealing annular space between casing strings or for sealing annular gaps between a conductor and a pipe string hanger installed in it. Seal assembly comprises a body, a guide for interaction with the tool during lifting and lowering of the seal assembly, a stop, external and internal seals. Seal housing has the first section for location of the stop, the second section contacting with the external and internal seals, the third section serving for connection of the seal housing to the housing. Seal housing is made solid, installed in the housing by means of bushings connected by a shear pin and fixed with a shear screw. Stop has a U-shaped cross-section with a support platform for interaction with a protrusion on the pipe string.

EFFECT: technical result is increased reliability of sealing of annular space between housing of casing string suspension and housing of conductor string head and reliability of sealing assembly at application of dynamic load.

1 cl, 3 dwg

Description

Technical field

The invention relates to a device used in the operation of offshore and onshore wells, and can be used for sealing the annular annular space, or for sealing the annular gaps between the conductor and the pipe string hanger installed in it.

Prior Art

From the existing state of the art, a combined sealant for a casing head in a well on the shelf is known (RF patent No. 2709585, publ. 12/18/2019), which provides sealing of the annular gaps between the surface conductor and the technical pipe string suspension installed in it, characterized in that the sealant is made with two-stage seals and has a body and a pusher, and the body has an H-shaped profile in the form of two rings with a transverse jumper for connecting the rings, contains three contact surfaces, one of which is the inner surface in contact with the landing conical surface of the hanger of the technical pipe string, and the other two - external surfaces in contact with the conductor, forming the first stage of metal-to-metal sealing, an external sealant of high elasticity is installed between the pusher and the body to seal the surface of the conductor, and an internal seal of less elasticity is installed to seal the suspension of the technical pipe string, arr. jointly forming the second stage of compaction.

The disadvantage of this technical solution is the H-shaped profile of the body, which, when it abuts against the casing string stage, can lead to deformation of the H-shaped body and, as a result, to a deterioration in the sealing of the first stage of the metal-to-metal seal, to possible device breakdowns.

The closest to the claimed technical solution is a non-metallic sealing element (RF patent No. 2712865, publ. 01/31/2020).

Non-metallic sealing element for sealing the annulus between the casing hanger body and the body of the casing head of the casing string, containing a lower stop with an internal annular groove, a body, an upper stop, first and second intermediate thrust elements; first and second non-metallic seals; at the same time, the upper stop is made with the possibility of linear movement when the shear elements are destroyed by an amount limited by the guide pins.

The disadvantage of this technical solution is that since the body has a section containing an internal groove, and is a collet, and the section contains longitudinal cutouts that break the inner and outer sides of the collet, so weakened by the internal recess, into separate elements, with deactivated non-metallic seals, the inner and outer the sides of the collet are somewhat compressed and are not in gear engagement with the thrust element, and when a load directed along the axis of the body is applied to the end of the collet, there is an increased probability of destruction of the body, which is especially likely when a dynamic load is applied along the axis of the body.

The essence of the invention

The problem solved by the present invention is the problem of creating a sealing unit that provides reliable sealing of the annulus between the casing hanger housing and the casing head housing of the casing string under conditions of increased axial loads during operation, arising, among other things, due to thermal expansion of casing pipes in the well, and at the same time, having increased reliability when applying a dynamic load directed along its axis.

EFFECT: creation of a sealing assembly providing reliable sealing of the annular space between the casing string hanger housing and the casing head casing of the conductor string, and at the same time, having increased reliability when applying a dynamic load directed along the casing pipes axis, simplifying the design of the sealing assembly.

The technical results are achieved by the fact that the seal assembly includes outer and inner seals interacting on one side with the seal body, on the other side with the casing string hanger body and the surface casing of the conductor string, respectively, while the upper end of the seal body is solid and has a flat supporting end, which perceives the longitudinal load when the zones are sealed with non-metallic elastic elements.

Brief description of the drawings

Further in the description, a possible, but the only version of the seal assembly is given.

The essence of the invention is illustrated by drawings.

In FIG. 1 shows the seal assembly.

In FIG. 2 shows a combined seal for a casing head in an offshore well (RF patent No. 2709585, publ. 12/18/2019).

In FIG. 3 shows a non-metallic sealing element (RF patent No. 2712865, published on January 31, 2020).

Detailed description of the invention

In FIG. 1 shows the seal assembly.

The seal assembly consists of:

1 - emphasis;

2 - internal seal;

3 - bushing;

4 - shear pin;

5 - ring;

6 - retainer;

7 - guide;

8 - cracker;

9 - retaining ring;

10 - body;

11 - shear screw;

12 - locking screw;

13 - ring;

14 - bushing;

15 - external seal;

16 – seal housing;

17 - persistent segment.

The body 10 is connected to the guide 7 by means of the retaining ring 9, between which there are crackers 8. Crackers 8 and clamps 6 provide rigid fixation of the body 10 with the conductor string 24 and the casing hanger body 23, respectively. Guide section 7, which interacts with the tool for raising and lowering the seal assembly, is made in the form of the number "1", which allows the tool to be hooked when raising and lowering the seal assembly. Sleeves 3 and 14 are installed on the body 10, which are connected by a shear pin 4 and fixed with a shear screw 11. The displacement of the sleeves is determined by the locking screw 12. Rings 5 and 13 are installed between the sleeves 3.14 and the seal housing 16, ensuring the dismantling of the seal assembly. The inner seal 2 and the outer seal 15 are installed on the seal body 16, as well as the stop 1, which is fixed by the thrust segment 17 with a locking ring.

The device works as follows.

The seal assembly is lowered by the seal setting tool, which is installed on the drill pipe hanger, into the space between the conductor string and the casing hanger body until it rests against the protrusion on the outer surface of the casing hanger body. When abutting against the protrusion, the axial load on the seal assembly increases, due to this, the seal body 16 moves all the way into the thrust segment 17. Further, after the destruction of the shear pin 4, the space between the seal body 16 and the surface of the conductor string and the casing hanger body with using the outer seal 15 and the inner seal 2 under the influence of the moving bushings 14 and 3. After the seal body 16 rests against the body 10, the ring 9 moves into the guide 7 and the crackers 8 and clamps 6 are installed.

The implementation of the seal housing 16 is solid, without deep grooves with elements in the form of a collet, with a support end interacting with the housing 10, eliminates the possibility of breakage of the seal housing 16, and the implementation of the stop 1 in a U-shaped form with a platform for resting against the protrusion of the pipe string eliminates the probability of breakage of the stop 1.

The application of an axial load upwards leads to the movement of the guide 7, the housing 10, the seal housing 16 upwards, while the shear screw 11 is destroyed and the pressure on the ends of the non-metallic seals 2 and 15, non-metallic seals 2 and 15 disappears due to the forces of elasticity of the material from which the seals are made 2 and 15 are reduced in cross-section and take on a normal shape, the seal assembly is unlocked and ready to be lifted.

In FIG. 2 shows a combined seal for a casing head in an offshore well (RF patent No. 2709585, publ. 12/18/2019).

The combined seal according to the RF patent No. 2709585 consists of:

18 - body;

19 - shear element;

20 - internal seal;

21 - pusher;

22 - fixing groove;

23 – casing hanger housing;

24 - conductor column;

25 - guide;

26 - elastic ring;

27 - elastic ring;

28 - fixing groove;

29 - outer seal.

Installation of the combined seal is carried out as follows.

The compactor is lowered into the well on a special tool, which, after applying the maximum weight load, is disconnected and lifted onto the platform.

As soon as the inner contact surface touches the landing cone surface on the hanger of the technical pipe string 23, a force will appear perpendicular to the axis of the well.

With further axial load of the tool through the pusher 21, the shear element 19 will receive the load.

The contact surface with tension will sit on the landing cone surface, the shear element 19 will be sheared.

The pusher 21 will begin to deform the outer seal of high elasticity 19 and the inner seal of less elasticity 20.

The force during deformation of the outer 29 and inner 20 seals is transferred to the body 18, it is elastically deformed in the radial direction.

Housing 18, choosing the side clearance, will press the outer contact surfaces to the conductor.

At this moment, the guide 25 will work, which will push the clamps in the form of split elastic rings 26 and 27 into the locking grooves 28 and 22 on the conductor 24 and the hanger of the technical pipe string 23, thereby fixing the seal, connecting the conductor 24 and the hanger of the technical pipe string 23 with a rigid connection through pusher 21.

The tool automatically detaches and rises to the platform.

Sealant installation is complete.

To remove the seal, another tool is used, which is captured by the guide 25 and lifts it up with an axial upward movement.

The proposed technical solution makes it possible to increase the reliability of sealing the conductor and the suspension of the technical pipe string during well operation on the shelf and to simplify the process operations.

The H-shaped stop is designed to work with the tapered surfaces of the technical string and conductor string being sealed, and when it rests against the protrusion on the technical string and the conductor string, there is a possibility of deformation or destruction of the ends of the H-shaped stop.

In contrast to the technical solution presented in the patent of the Russian Federation No. 2709585 (publ. 12/18/2019), in the proposed technical solution, the stop is made in section not in an H-shaped form, but in an inverted U-shaped form, has a support platform for interacting with the protrusion on the technical pipe string, which eliminates the possibility of destruction of the stop end when applying a dynamic load directed along the seal axis.

In FIG. 3 shows a non-metallic sealing element (RF patent No. 2712865, published on January 31, 2020).

The sealing element according to the patent of the Russian Federation No. 2712865 consists of:

30 - non-metallic seal;

31 - thrust element;

32 - column head of the conductor column;

33 - top stop;

34 - non-metallic seal;

35 - body;

36 - emphasis;

37 – casing hanger.

To activate the non-metallic sealing element, that is, the compression of the non-metallic seals 30 to ensure that these non-metallic seals 30 fit to the bodies 32 and 37 of the casing head of the conductor string 32 and the casing hanger 37, when the body 35, intermediate thrust elements 31 and the upper stop 33 are moved, the third section body 35 moves in the inner annular groove of the lower stop 36, overcoming the force arising from the compression of non-metallic seals 30.

With a given movement of the housing 35 by an amount equal to the width of the spring ring in the inner annular groove of the lower stop 36, sufficient to compress the non-metallic seals 30, ensuring their fit to the casings 32 and 37 of the casing head of the conductor string and the casing hanger and sealing, the spring ring moves into longitudinal recess of the third section of the housing 35 and prevents the reverse movement of the housing 35, while maintaining the compression of the non-metallic seals 30.

If it is necessary to deactivate the non-metallic seals 30, the upper stop 33 is moved away from the non-metallic seals 30, destroying the shear elements 34, thus the deactivation force depends on the choice of the number of shear elements 34 (from 2 to 10). The movement of the upper stop 33 relative to the intermediate stops 31 is limited by the guide pins, but is sufficient to remove the end element of the upper stop 33 from the space formed by the first and second rows of collet segments of the first section of the housing 35.

After this extraction, the first and second rows of the collet segments of the first section of the body 35 are able to compress from the force from the non-metallic seals 30. When the first and second rows of the collet segments of the first section of the body 35 are compressed, they disengage from the toothed profile of the intermediate thrust elements 31, which allows the non-metallic seals 30 to expand.

In contrast to the technical solution presented in patent No. 2712865 (published on January 31, 2020), in the proposed technical solution, the body 35 is made of a solid body and does not have segments in the form of a collet with gearing.

The implementation of the seal assembly with a solid body, without collet segments, the execution of the stop in the U-shaped inverted form, having a support platform for interacting with the protrusion on the technical pipe string, the presence of all this makes it possible to achieve technical results, which consist in creating a seal assembly that provides reliable sealing of the annular space between the casing hanger body and the casing head casing of the conductor string, and at the same time, having increased reliability when applying a dynamic load directed along the axis of the casing, simplifying the design of the seal assembly.

Claims (2)

1. The seal assembly, consisting of a body, attached to it by a guide for interacting with the tool when raising and lowering the seal assembly, a seal body having a first area for placing the stop, a second area in contact with the outer and inner seals, a third area used for attaching seal body to the body, stop, outer and inner seals, characterized in that the seal body is made of a solid body, is installed in the body by means of bushings connected by a shear pin and fixed with a shear screw, and the stop has a U-shaped section with a support platform for interacting with the protrusion on pipe string. 2. The sealing unit according to claim 1, characterized in that the guide section designed to interact with the tool when raising and lowering the sealing unit is made in the form of the number "1".

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