RU2531667C1 - Wellhead split sealer - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: invention relates to wellhead equipment. Said sealer comprises split cylindrical case composed of two half-cases jointed together and sealed by deformed copper-bearing shims. The plane of butts of half-cases is perpendicular to direction of eccentricity of conductor string and mid string. Half-face-plate with circular groove is welded to bottom end of every half-case to receive split seal ring made of soft metal. Circular groove is turned with allowance for maximum wall thickness of conductor string and maximum eccentricity of said string and mid string. Semi-flange is welded to outer side surface of every half-case. Tie plates with angle pieces are welded between semi-flanges and half-face-plates while tie plates with strips are welded under half-face-plates. All tie plates have bores for studs with nuts while pipe is welded in one of half-cases. Semi-ring with tapered top end surface is welded to inner side surface of every half-case. Self-sealing taper rings made of resilient material and split over their height are arranged above semi-rings. Split bottom box with its halves clamped by latches is arranged above said self-sealing taper rings. Bottom box lower end surface is tapered with angle in its end surface inclination φ to sealer vertical axis defined from inequality. End top surfaces of semi-rings and self-sealing taper rings feature taper corresponding to that of split bottom box lower end surface. Top part of bottom box and semi-flanges have through bores to receive studs with nuts. Split thrust bush with threaded bores at bottom end surface is arranged above bottom box. Split thrust bush is coupled with locking inserts to make an integral part. Slips rest in inner side surface of split thrust bush.

EFFECT: reliable isolation of space between conductor string and mid string, accelerated re-equipment of acting wells.

3 dwg

Description

The invention relates to the oil and gas industry, in particular to wellhead equipment, and can be used to seal the annulus between the conductor and the intermediate string in existing wells equipped with OKK-1 single-flange column heads without jamming them.

Analysis of the current level of technology showed the following:

- at present, the mouth of a large number of operating wells, for example, in underground gas storages, is equipped with OKK-1 single-flange column heads without sealing the space between the conductor and the intermediate column. During long-term operation, cases of gas evolution are noted in this space, and eccentricity between the columns is also possible. An open mouth does not allow controlling and managing annular manifestations.

Known commercially available two-flange column head type OKK-2 (see Abubakirov V.F., Arkhangelsky V.L. and others. Drilling equipment, blowout preventer and wellhead: Reference book .: In 2 vol. T.1 - M .: LLC "IRC Gazprom", 2007, p.613), which ensures the tightness of the space between the conductor and the intermediate column. However, to install the above column head, it is necessary to dismantle the OKK-1 type column head. This requires plugging the well, removing downhole equipment, installing an insulating cement bridge, and then, after re-equipment of the mouth, drill it and develop the well. All this will significantly increase the time and cost of work. In addition, in most wells, the space between the conductor and the intermediate string is cemented, which also increases the time and labor required to clean the sealing surfaces. In addition, to install a casing head of the OKK-2 type on a conductor, it is necessary to cut a thread, which is not always possible due to worn-out and corroded pipes. If there is an eccentricity between the conductor and the intermediate column, the installation of a column head of the OKK-2 type without special devices will be impossible.

A device for sealing the wellhead with surface placement of blowout equipment (see AS No. 1799996 from 05/08/91 according to class E21B 33/035, publ. 03/07/93), including a housing with uprights of the column head rigidly connected to the conductor placed inside the riser. A support sleeve is installed between the water separating column and the conductor with a sealing element sequentially placed under it, a crown, main and additional wedges, spacer cones, tightening rods with nuts at the upper ends and spring-loaded rings. Sealing is carried out in the annular space between the conductor and the riser. The disadvantages are the following. For installation in the annular space of the device for sealing, it is necessary to cut the riser column. Moreover, the installation of the device is possible only in wells with a large gap between the columns. The small gap, as well as the presence of eccentricity between the columns will not allow the device to be mounted in annular space. In addition, the housing of the column head to the conductor is connected by welding, i.e. hot work is necessary.

Wellhead well equipment is known (see Cl. RF No. 2269641 dated January 18, 2005, class E21B 33/03, published February 10, 2006) Wellhead equipment includes a column head consisting of a housing with radial channels, a flange, and elements connection, suspension and sealing of the casing, and the pipe head. The housing and the flange of the column head are made detachable. The disadvantages of this equipment is the following. Wellhead equipment is intended for use on previously constructed wells with the installation of such equipment during major repairs of these wells. To install the equipment it is necessary: to plug the well, remove the downhole equipment, install an insulating cement bridge, after re-equipment the mouth, drill the bridge and develop the well, which will significantly increase the time and cost of work.

Conductor sealing is carried out on the side surface. For a long period of operation of the well, the outer and inner surfaces of the conductor as a result of corrosion become unsuitable for sealing without prior treatment. Cleaning such surfaces is time consuming and impossible with deep corrosion.

When sealing eccentric columns, the design will become much more complicated and the manufacturability will decrease.

The technical result that can be obtained by carrying out the invention provides:

- reliable sealing of the space between the conductor and the intermediate column due to the implementation of the sealant detachable;

- reducing the time for re-equipping the mouth of existing wells equipped with OKK-1 single-flange column heads due to the possibility of installing a sealant without dismantling OKK-1 single-flange column heads, i.e. without killing the well and conducting other long and laborious operations;

- the ability to install a sealant with an eccentric arrangement of columns due to conductor sealing at the end;

- the exception of the operation of threading and hot work when installing the sealant, which will allow it to be mounted in the presence of pressure in the well and with possible gas evolution.

The technical result is achieved using the proposed sealant wellhead detachable, including:

mounted on the end of the conductor with the coverage of part of the length of the intermediate column eccentrically located in the conductor, a detachable cylindrical body consisting of two half-shells, joined together end-to-end and sealed with stress-strain copper-containing gaskets, the plane of the joints of the half-shells being perpendicular to the direction of the eccentricity eccentricity column;

on the lower end of each half-shell, a half-washer with a special configuration annular groove is welded on its lower end surface for a split sealing ring made of soft metal, and the annular groove is grooved taking into account the maximum thickness of the conductor wall and the maximum eccentricity of the conductor and the intermediate column, ensuring coaxiality of the detachable cylindrical the housing relative to the intermediate column;

in the upper part on the outer side surface of each half-housing, a half-flange is welded, and between the half-flanges and half-washers, tie bars with kerchiefs are welded, and under the half-tubes there are tie bars with plates, while all tie bars have tie holes for the studs with nuts, and in one of the half-shells welded pipe;

in the middle part on the inner side surface of each half-shell a half ring is welded, the upper end surface of which is made conical;

self-sealing conical rings made of elastic material and cut along the entire height are installed above the half rings, and the places of the cuts are offset from each other;

a detachable packing follower is installed above the self-sealing conical rings, the halves of which are fixed by hooks, the lower end surface of the detachable packing follower being conical, and the angle of inclination φ of its end surface to the vertical axis of the sealant is determined from the inequality

, $$\varphi \ge arctg\frac{\mathrm{one}}{f}$$

,

where: f is the coefficient of friction of the elastic material on the metal;

the upper end surfaces of the half rings and the self-sealing conical rings have a taper corresponding to the taper of the lower end surface of the split packing follower;

through holes for thrust studs with nuts installed above the split packing follower and half flanges are made in the upper part of the detachable packing follower and in the half flanges;

above the detachable packing follower, a detachable thrust sleeve with threaded holes made on the lower end surface is mounted to ensure that the upper part of the thrust studs is fixed, and the detachable thrust sleeve in the upper part is joined in a single piece by the locking inserts, the joints of which are perpendicular to the joints of the detachable thrust sleeve, and the cones are supported on the inner side surface of the detachable thrust sleeve made conically.

Thus, the claimed technical solution meets the condition of novelty.

The analysis of the inventive step showed the following: from the sources of patent documentation and scientific and technical literature no technical solutions have been identified that are based on features that match the distinctive features of the claimed technical solution, providing an achievable technical result due to the unknown properties of the structural elements of the sealant and the connections between the structural elements . Thus, the claimed essential features do not follow explicitly from the prior art, i.e. correspond to the condition of inventive step.

The design of the claimed device is illustrated by the following drawings:

figure 1 presents the frontal section of the device;

figure 2 presents a profile section of the device;

figure 3 presents a bottom view.

The wellhead sealant is detachable mounted on the end of the conductor 1 and covers part of the length of the intermediate string 2, which is eccentrically located in the conductor 1. The sealant contains a detachable cylindrical body, which consists of two half-shells 3. Half-shells 3 are connected end to end, and the joints are tightly sealed deformed copper-containing gaskets 4. The plane of the joints of the half-shells 3 is perpendicular to the direction of the eccentricity e of the conductor 1 and the intermediate column 2. At the lower end of each poluplanshayba half shell 3 is welded with an annular groove 5, 6, a specific configuration at its lower end surface of a split seal ring 7. The seal ring 7 is made of soft metal. An annular groove 6 of a special configuration is grooved taking into account the maximum wall thickness of the conductor 1 and the maximum eccentricity e of the conductor 1 and the intermediate column 2, ensuring the coaxiality of the detachable cylindrical body relative to the intermediate column 2. In the upper part on the outer side surface of each half-body 3, a half-flange is welded 8. Between coupling flanges 9 with kerchiefs 10 are welded by half flanges 8 and half-washers 5, and connecting bars 11 with plates 12 under the half-washers 5. The connecting bars 9, 11 have through tverstiya 13 by studs 14 and nuts 15. One half-shells 3 welded connection 16 to the possibility of manufacturing operations, as well as connections for pressure gauge and pressure relief valves. In the middle part on the inner side surface of each half-body 3, a half-ring 17 is welded, the upper end surface of which is made conical. Above the half rings 17, self-sealing conical rings 18 are made of elastic material. Self-sealing conical rings 18 are cut along the entire height, and the places of the cuts are offset from each other. Above the self-sealing conical rings 18, a detachable packing follower 19 is installed, the halves of which are fixed by hooks 20. The lower end surface of the packing follower 19 is conical, and the angle of inclination φ of its end surface to the vertical axis of the sealant is determined from the inequality

, $$\varphi \ge arctg\frac{\mathrm{one}}{f}$$

,

where: f is the coefficient of friction of the elastic material on the metal.

The upper end surfaces of the semirings 17 and the self-sealing conical rings 18 have a taper corresponding to the conicity of the lower end surface of the detachable packing follower 19. In the upper part of the detachable packing follower 19 and in the half flanges 8, through holes 21, 22 are made for thrust studs 23 with nuts 24, 25. Nuts 24 mounted above the split packing follower 19 and nuts 25 above the half flanges 8. Above the split packing follower 19, a detachable thrust sleeve 26 is mounted. The split thrust sleeve 26 has threaded holes 27 made on its lower end face surfaces for fixing the upper part of the thrust studs 23. The detachable thrust sleeve 26 in the upper part is joined in a single part by the locking inserts 28, the joints of which are perpendicular to the joints of the split thrust sleeve 26. The cones are supported on the inner side surface of the split thrust sleeve 26, made conically, .

The sealant at the wellhead is installed in the following order.

To create a stress-strain state of copper-containing gaskets 4 previously at the factory, the half-shells 3 with copper-containing gaskets 4 are pulled together by studs 14 until a tight joint is formed. In this case, the copper-containing gaskets 4 are deformed and partially float inside the detachable cylindrical body. Next, the inner surface of the detachable cylindrical body above the half rings 17 is completely cleaned and, when assembled, the detachable cylindrical body is delivered to the well. After disconnecting the half-shells 3 before mounting on the well, copper-containing gaskets 4 retain the shape of the mating surfaces and remain in a stress-strain state, therefore, during installation they do not float inside the split cylindrical body, providing reliable sealing of the space between the split cylindrical body and the intermediate column 2.

Before installing the sealant at the wellhead (FIGS. 1, 2), the upper end of the conductor 1 is cut with a roller pipe cutter and the end surface is cleaned. The direction of the eccentricity e is determined between the conductor 1 and the intermediate column 2. On the prepared end of the conductor 1, half-bodies 3 are installed with an annular groove 6 of a special configuration (Fig. 3), made on the lower end surface of the half-washers 5, and they are joined together end to end, tightened with studs 14 tie rods 9 and tie rods 11. The joints of the half-shells 3 are sealed with stress-strain copper-containing gaskets 4. The assembled detachable cylindrical body is lifted into the annular groove 6 Hoc configurations stacked split sealing ring 7 made of a soft metal. Next, the detachable cylindrical body with a split sealing ring 7 is mounted on the end of the conductor 1 so that the plane of the joints of the half-shells 3 is perpendicular to the direction of the eccentricity e of the conductor 1 and the intermediate column 2, and the detachable cylindrical body is aligned with the intermediate column 2.

In the annular space between the detachable cylindrical body and the intermediate column 2, self-sealing conical rings 18 are laid on the half rings 17, the taper of which compensates for the unevenness of the annular space, providing reliable sealing of the annular space. The displacement of the cut points of the self-sealing conical rings 18 relative to each other allows you to overlap the cut places with the whole part of the ring. In this case, the split ring pack works like a continuous ring pack. Two assemblies are pre-assembled, each of which consists of half of a detachable thrust sleeve 26 with screwed thrust pins 23, nuts 24, half of a detachable packing follower 19 and nuts 25. Install them above the detachable cylindrical body so that the lower end of the detachable packing follower 19 rests against the self-sealing conical rings 18, and the thrust pins 23 entered the corresponding through holes 21 of the detachable packing followers 19 and through holes 22 of the half flanges 8. The lower end surface of the detachable packing followers 19 perform a cone and the angle of inclination φ of its end surface to the vertical axis of the sealant is determined from the inequality

, $$\varphi \ge arctg\frac{\mathrm{one}}{f}$$

,

where: f is the coefficient of friction of the elastic material on the metal.

During the installation of the sealant, its distortions, misalignment, as well as the ovality of the intermediate column 2 are possible. Technological clearances are provided in the detachable packing follower 19 to compensate for them. At high contact loads, plastic flow of elastic material into these clearances is possible. This is prevented by the frictional force arising from the contact of the lower end conical surface of the split packing follower 19 with the surface of the self-sealing conical rings 18. A sufficient friction force occurs when the angle of inclination φ is determined from the above inequality.

Example. The detachable packing follower 19 is made of steel 45, the lower end conical surface of which is processed according to roughness class 4. Self-sealing conical rings 18 are made of rubber grade IRP-1294. With dry friction of rubber on steel, the friction coefficient is 0.4-1.0 (see Yavorsky Y. Rezina in automobiles / translated from Polish. Edited by V.M. Kharchevnikov. - L.: Mechanical Engineering, 1980. p. 21, Internet Site: http://shinyavto.ru/books/rezina_v_avto/rezina_v_avto_21.html.) It was experimentally established in laboratory conditions that the coefficient of friction of the above grade of rubber on steel 45 without lubricant is equal to f = 0.7, then the angle the slope φ of the end surface of the split packing follower 19 to the vertical axis of the sealant is determined from the inequality

, $$\varphi \ge arctg\frac{\mathrm{one}}{0.7}$$

,

i.e. φ≥55 °. We take φ = 60 °.

The upper end surfaces of the semirings 17 and the self-sealing conical rings 18 have a taper corresponding to the taper of the lower end surface of the split packing follower 19, i.e. 60 °, which will provide reliable sealing due to the uniformly tightened self-sealing conical rings 18.

After installing these layouts, the halves of the detachable packing follower 19 are connected in a single part by hooks 20, and the halves of the detachable thrust sleeve 26 are connected by means of fixing inserts 28. After that, the dies 29 are installed in the space formed between the inner side surface of the detachable thrust sleeve 26 and the intermediate column 2. First, the conductor 1 is sealed at the end, moving the nuts 25 down along the thrust studs 23 and thereby transmitting axial force through the half flanges 8 of the detachable cylindrical body at a time eznoe sealing ring 7. Then, the nuts 24 moving down the crush resistant studs 23 split packing follower 19 with a contact pressure not exceeding yield strength of rubber, sealing the space between the split body and the intermediate column.

Thus, we can conclude that the proposed technical solution meets the condition of industrial applicability.

The claimed technical solution meets the criterion of patentability, namely the condition of novelty, inventive step and industrial applicability.

Claims (1)

The wellhead sealer is detachable, mounted on the end of the conductor with coverage of a part of the length of the intermediate string eccentrically located in the conductor, including a detachable cylindrical body, consisting of two half-shells, joined together end-to-end and sealed with stress-strain copper-containing gaskets, with the plane of the joints of the half-corps head the conductor and the intermediate column, and at the lower end of each half-shell a half-plate with a ring is welded a special configuration groove on its lower end surface for a split sealing ring made of soft metal, and the annular groove is grooved taking into account the maximum thickness of the conductor wall and the maximum eccentricity of the conductor and the intermediate column, ensuring coaxiality of the detachable cylindrical body relative to the intermediate column, and in the upper a part on the outer side surface of each half-shell is welded a half flange, and between welded half flanges and half-washers There are tie bars with kerchiefs, and under the half-washers there are tie bars with plates, while all tie bars have through holes for the studs with nuts, and a pipe is welded into one of the half-shells, with a half-ring welded in the middle part on the inner side surface of each half-shell the end surface of which is made conical, while self-sealing conical rings made of elastic material and cut along the entire height are installed over the half rings, and the places of the cuts are offset flax other, and above the self-sealing cone rings mounted detachable packing follower halves which hooks are fixed, the lower end surface of the split packing follower is made cone-shaped, and its inclination angle φ to the vertical end surface of the dock axis determined from the inequality
$$\varphi \ge arctg\frac{\mathrm{one}}{f}$$

,
where: f is the coefficient of friction of the elastic material on the metal,
the upper end surfaces of the semicircles and the self-sealing cone rings have a taper corresponding to the conicity of the lower end surface of the detachable packing follower, and through holes for thrust studs with nuts installed above the detachable packing follower and half flanges are made in the upper part of the detachable packing follower and in the half flanges, while above the connector a grooveback mounted detachable thrust sleeve with threaded holes made on the lower end surface, ensuring the fixation of the upper part dowels, moreover, the split thrust sleeve in the upper part is joined into a single part by the locking inserts, the joints of which are perpendicular to the joints of the split thrust sleeve, and the dies rest on the inner side surface of the split thrust sleeve.

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