RU2760447C1 - Shut-off valve for casing string - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention relates to the oil industry, in particular to the cementing of casing strings. The casing shut-off valve contains a body, hermetically fixed in the pipe string coupling, with cementing holes for the passage of cement slurry, a locking sleeve installed inside the body above the cementing holes and fixed with shear elements. The body is made in the form of a cup, the cementing holes are made in its bottom part. The bottom part of the nozzle is equipped with a sealing gasket with holes coinciding with the cementing holes of the nozzle; a conical groove is made in the lower inner part of the nozzle with the possibility of placing a retaining ring. The locking sleeve is provided with cementing holes that do not coincide with the cementing holes in the bottom of the cup. In the upper part of the locking sleeve, a saddle is made with the possibility of seating a displacement plug. A sealing elastic ring is made in the lower part of the locking sleeve. On the outer wall of the locking sleeve, cylindrical bores are made with the possibility of installing a sealing elastic ring and a locking ring.

EFFECT: increasing the reliability and tightness of the valve.

1 cl, 4 dwg

Description

The invention relates to the oil industry, in particular to the cementing of casing strings.

Known valve for the casing (author's certificate SU No. 1654547, IPC E21B 34/10, 33/14, publ. 07.06.1991, bull. No. 21), including a body, in the inner cavity of which there is a sleeve with a saddle, installed with the possibility of limited axial movement. A shut-off element with a rod, which is fixed in the shoe with a shear element, is located under the bushing. The force of the shear element is greater than the pressure of the casing string, and the stroke of the sleeve is less than the stroke of the valve stem. When the cement slurry is pumped into the annular space, the cement slurry passes through the axial channel of the bushing, displaces the shut-off element downward through the housing windows into the annular space. After the completion of cementing, the spring presses the shut-off element against the bushing seat and together with it moves it up to the stop of the bushing against the casing collar, preventing the flow of cement slurry from the annular space into the casing string.

The disadvantages of this valve are:

- the presence of a spring, which is susceptible to possible breakage during repeated compression and, as a consequence, leading to jamming of the valve;

- the absence of the possibility of instantaneous shut-off of the passage channel, since at the back pressure of the column of cement slurry from the annulus, part of the cement slurry has time to pass into the casing before the valve is activated by 100%, which in turn leads to leaving cement residues inside the casing above the valve space. solution that prevents further descent of downhole pumping equipment.

Also known is a valve for a casing string (patent RU No. 2335619, IPC Е21В 34/06, 33/14, publ. 10.10.2008, bul. No. 28), including a restrictor with a seat and side channels, a sleeve that has the ability to seal side channels of the limiter. The restrictor is plugged from the bottom and connected to the casing. The casing string is equipped from the bottom with a lower sleeve, provided at the bottom from the inside with a cylindrical recess, into which a hollow shank is inserted with the possibility of axial movement upwards, fixed in the lower position with shear pins. The bushing is rigidly mounted in the upper end of the hollow shank and has the ability to interact in the upper position with the upper plane of the seat of the limiter and hermetically overlap the side channels of the limiter from the outside. For a tight shut-off from the inside of the side channels of the limiter, a displacement plug with a sealing head from the bottom and an annular recess made on the inner surface in the upper part of the limiter is used. The annular selection of the restrictor fixes the sealing head of the displacement plug in the restrictor after the interaction of the lower end of the sealing head of the squeezing plug with the stopper plug

The disadvantages of this valve design are the presence of an additional coupling, which increases the number of threaded connections in a short section, which can lead to gaps along the threaded part, as well as unreliable attachment of the liner on the shear pins, which acts as a guide shoe for the entire casing, with the likelihood of premature shearing of the pins during running casing into the well when all kinds of ledges and caverns meet and the liner is not sealed with the inner part of the sleeve.

The closest in technical essence is a valve for casing strings (patent RU No. 2250355, IPC Е21В 34/06, 33/14, publ. 20.04.2005, bull. No. 11), including a body with a stop with a seat and side flushing channels - cementing holes, a check valve, a sleeve installed in the axial channel of the restrictor above the flushing channels (cementing holes), mounted on shear elements with the possibility of overlapping them, while the restrictor is additionally equipped with a stopper interacting with the sleeve in its lower position, while the outer surface the limiter above the side channels is equipped with an elastic ring with a stop and is made with the possibility of hermetic installation of the limiter in the required interval between the casing pipes during their assembly, and the saddle is made with a cylindrical recess on the lower plane of the limiter, and the check valve is made of poppet, spring-loaded with the possibility of rotation relative to the fastening to the limiter, consisting consisting of rigidly connected elastic cuff, centralizer and cylindrical plate, on which an annular groove is made, installed opposite the inner lower plane of the stopper, while the outer plane of the cylindrical plate is placed opposite the seat of the stopper, and the elastic cuff is located between the lower plane of the stopper and the cylindrical plate.

The disadvantages of the known valve are partially eliminated in comparison with analogs, however, it is not devoid of disadvantages. So, despite the closure of the side flushing windows after the sleeve has shifted, the main shut-off element is a cylindrical plate fixed on an elastic collar, which, when pumping cement mortar, can collapse from variable loads during cement pumping. In this case, the bottom plate will not close completely and the cement slurry, after receiving the “STOP” pressure, will begin to flow into the column.

The technical objective of the proposal is to create a reliable, sealed and easy to manufacture and operate valve design, which allows to reduce material and financial costs.

The technical problem is solved by the proposed shut-off valve for the casing, containing a body hermetically fixed in the coupling joint of the pipe string, with cementing holes for the passage of cement slurry, a shut-off sleeve installed inside the body above the cementing holes and fixed with shear elements.

The novelty is that the body is made in the form of a cup, the cementing holes are made in its bottom part, while the bottom part of the cup is equipped with a sealing gasket with holes coinciding with the cementing holes of the cup, a conical groove is made in the lower inner part of the cup with the possibility of placing a retaining ring, the locking sleeve is equipped with cementing holes that do not coincide with the cementing holes of the bottom part of the cup, a saddle is made in the upper part of the locking sleeve with the possibility of seating a displacement plug, and in the lower part there is a sealing elastic ring, while cylindrical bores are made on the outer wall of the locking sleeve with the possibility of installation sealing elastic ring and retaining ring.

Also new is that the retaining ring is made in the form of a split spring ring.

FIG. 1 shows a longitudinal section of a casing shut-off valve according to the invention.

FIG. 2 shows a view A-A showing the bottom part of the locking sleeve with holes made.

FIG. 3 shows the shut-off valve in the working position when closed with a cement plug in a longitudinal section.

FIG. 4 shows a view BB with the image of a sealing gasket with holes that repeat the holes on the bottom of the case.

The casing stop valve contains a body, which is made in the form of a nozzle 1 (see Fig. 1), hermetically fixed in the coupling joint of the pipe string, between the casing nipples 3 and 4 by the stop 5 and the elastic ring 6 located above, with cementing holes 7 for the passage of the grout. The cementing holes 7 are made in the bottom part of the cup 1, are located eccentrically, directed downward (the axes of the holes 7 are directed parallel to the axis of the body). In this case, the bottom part of the cup 1 is equipped with a sealing gasket 8 with holes coinciding with the cementing holes 7 (see Fig. 4) of the cup 1 (see Fig. 1). In the lower inner part of the nozzle 1, a conical groove 9 is made with the possibility of accommodating a retaining ring 10. Also, the check valve includes a locking sleeve 11 installed inside the body above the cementing holes 7 and fixed with shear elements 12. The locking sleeve 11 is provided with cementing holes 13 (see Fig. 2), located eccentrically and not coinciding with the cementing holes 7 (see Fig. 1) of the bottom of the nozzle 1, allowing the cement slurry to freely pass through them. In the upper part of the locking sleeve 11, a saddle 14 is made with the possibility of seating a displacement plug 15 (see Fig. 3) or a ball (not shown in Figs. 1-4), and in the lower part there is a sealing elastic ring 16 (see Fig. 1 , 3), allowing hermetically to install the locking sleeve 11 (see Fig. 1). In this case, cylindrical bores 17 and 18 are made on the outer wall of the locking sleeve 11 with the possibility of installing a sealing elastic ring 16 and a locking ring 10, respectively. And the retaining ring 10 can be made in the form of a split spring ring.

The casing shut-off valve works as follows.

The assembled shut-off valve is delivered to the well and installed in a sleeve connection between the nipples of the casing pipes 3 and 4 (see Figs. 1 and 3) of the lower end of the string and pressed with an elastic ring 6.

In the process of running the casing into the well to the target depth, the liquid in the well flows freely from bottom to top through the cementing holes 7 and 13 of the nozzle 1 and the locking sleeve 11 (see Fig. 1), respectively, filling and flushing the inner space of the casing. After reaching the bottom of the well, the cementing material is pumped into the casing. After pumping the calculated amount of displacement fluid, the squeezing plug 15 (see Fig. 3) or the ball (not shown in Figs. 1-4) sits in the seat 14 (see Fig. 1) and, when the pressure rises to the calculated value, it shifts the locking sleeve 11 In this case, shear elements 12 are cut off, the locking sleeve 11 moves down to the stop against the bottom of the body glass 1. In this case, the locking ring 10 enters the grip in the tapered groove 9 of the housing 1, is placed in it, reliably fixing the locking sleeve 11 in the lower position, while the flushing holes 7 and 13 (see Fig. 3) are overlapped by the free area between the holes.

Thus, at the moment of obtaining the "STOP" pressure, the shut-off sleeve 11 (see Fig. 1) instantly reliably closes the flushing holes 7 and 13, excludes the return flow of cement slurry from the annular space of the well into the casing. The tightness of the device is ensured, as well as the prevention of leaving a part of the cement slurry inside the casing above the valve.

The proposed valve for the casing string has a simple, reliable and sealed design, which increases the quality of its assembly and reliability in operation, reduces the total time for well construction, and therefore saves material and financial costs during manufacture and operation.

Claims (2)

1. A shut-off valve for a casing string, comprising a body, hermetically fixed in the coupling joint of a pipe string, with cementing holes for the passage of cement slurry, a shut-off sleeve installed inside the body above the cementing holes and fixed with shear elements, characterized in that the body is made in the form of a glass , the cementing holes are made in its bottom part, while the bottom part of the cup is equipped with a sealing gasket with holes coinciding with the cementing holes of the cup, a conical groove is made in the lower inner part of the cup with the possibility of placing a retaining ring, the locking sleeve is equipped with cementing holes that do not coincide with the cementing holes holes in the bottom part of the glass, in the upper part of the locking sleeve there is a saddle with the possibility of seating a displacement plug, and in the lower part there is a sealing elastic ring, while on the outer wall of the locking sleeve there are cylindrical spacing chucks with the possibility of installing a sealing elastic ring and a retaining ring. 2. A casing stop valve according to claim 1, characterized in that the stop ring is made in the form of a split spring ring.

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