RU2467158C1 - Check valve for casing string - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: invention relates to oil industry and may be used in oil production, well flushing-out and development. Proposed valve comprises body, seat with axial channel accommodating seal cup fitted therein and bush with radial bore pressing said cup to seat to receive push rod with axial spring interacting with shutoff ball to press the latter against push rod face cup at its top. Push rod top face features disc shape with diameter approximating to bush ID to allow centering said rod in its axial displacement by bush walls. Bush bottom has nut with holes along its edges and axial hole to center push rod.

EFFECT: higher reliability, lower labor input.

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Description

The invention relates to the oil industry, namely to downhole production equipment, and can be used in oil production, flushing and well development.

The non-return valve is designed primarily to prevent the backflow of the working medium - cement or drilling mud, treated with chemical reagents, mineralized formation water, oil and gas at temperatures up to 100 ° C - from the annular space into the inner space of the casing string.

Known check valve for a casing string, comprising a housing, axially movable therein, a shut-off element in the form of a ball, pressed against the seat by means of a spring, and a restrictive element for the spring (RU No. 95736 U1, IPC (2006.01) E21B 34/00, published on July 10, 2010).

A disadvantage of the known design of the non-return valve is the insufficient locking effect, due to the likelihood of the displacement of the locking element from the axial position and its loose pressure against the seat.

The closest analogue of the claimed device, selected as a prototype, is a non-return valve containing a housing, a filter installed in it, which is a disk with holes, a seat with an axial channel and a sealing collar and a locking element in the form of a ball and a limiter of axial movement of the ball made in the form of a glass fixed in the saddle with radial, longitudinally elongated holes. An axially spring-loaded rod is placed in the glass, which is configured to interact with its end surface and the ball and press it against the cuff. In addition, the end surface of the upper part of the stem interacting with the ball is made with a lodgement in the form of an internal conical or spherical surface (RU No. 101489 U1, IPC (2006.01) E21B 34/10, published on January 20, 2011). Common essential features of the known and claimed devices are a housing, a filter installed in it, a seat with an axial channel and a sealing collar fixed in it and a sleeve with radial holes pressing it to the saddle, in which it interacts with a locking element made with the possibility of axial movement, made in the form ball, rod-pusher with an axial spring, which provides pressure of the locking element to the cuff.

During operation of the known non-return valve, the presence of a stem for a spring and a sealing collar increases the locking effect.

However, the disadvantages of the known valve are the unreliability of its operation and the great complexity of its manufacture.

This is due to the following reasons:

- the implementation of the locking element in the form of a ball interacting with the rod while maintaining several degrees of freedom, leads to the possibility of displacement of the ball from the axial position and press it to the saddle with some axial displacement, without providing the necessary locking effect. This displacement of the ball is also enhanced by the fact that the rod-pusher is fixed only in the bottom of the glass. In the process of flushing the casing, especially in the horizontal wellbore, due to the fact that the length of the rod is several times its diameter, it is possible to jam in the open position;

- the execution of the end surface of the upper part of the pusher rod with a lodgement in the form of an internal conical or spherical surface leads to a significant increase in the complexity of manufacturing the valve.

The basis of the invention is the task of improving the check valve for the casing, in which by means of structural changes the required locking effect is achieved, which leads to an increase in the reliability of the valve and a decrease in the complexity of its manufacture.

The problem is solved in that in the non-return valve for the casing string containing the housing, a filter installed in it, a seat with an axial channel and fixed in it with a sealing sleeve and a sleeve with radial holes pressing it against the saddle, in which an axial displacement mounted a locking element, made in the form of a ball, a rod-pusher with an axial spring, which ensures that the locking element is pressed against the cuff by the end surface of the rod-pusher in its upper part; o the end surface of the rod-pusher, in its upper part, has the shape of a disk, the diameter of which is close to the inner diameter of the sleeve and is made with the possibility of centering the rod-pusher during its axial movement by the walls of the sleeve, and a nut with holes is fixed in the lower part and an axial hole configured to center the push rod through the axial hole.

The essence of the invention is illustrated in the drawing, where Fig.1 shows a longitudinal section of a check valve for a casing string.

The check valve for the casing string includes a housing 1, in which the front internal and rear external connection threads are made, which are used to integrate the valve into the pipe string. In the housing 1, a seat 2 with an axial channel 3 is fixed by means of a threaded connection. The tightness of the connection of the saddle 2 with the housing 1 is ensured by a sealing ring 4. A sealing sleeve 5 is installed in the saddle 2, made of an elastic material, for example, rubber. The sleeve 5 is pressed against the saddle 2 by a sleeve 6 with radial holes, fixed in the saddle 2 by means of a threaded connection, in which a rod-pusher 7 with an axial spring is installed 8. The end surface of the rod-pusher 7 in its upper part (in the direction of flow), having the shape of a disk 9, can interact with a locking element made in the form of a ball 10. In the lower part of the sleeve 6, a nut 11 is fixed (for example, by means of a thread) with holes 12 in a circle and an axial hole. A rod-pusher 7 is mounted in the axial hole of the nut 11, on which an axial spring 8 is mounted, abutting, on the one hand, in the disk 9, and on the other, in the nut 11. Radial holes 13 are made in the upper part of the sleeve 13. In the housing 1, seat 2 is equipped with a filter 14.

The implementation of the rod-pusher, the end surface of which in its upper part has the shape of a disk, provides centering of the rod-pusher during its axial movements, thereby achieving the necessary locking effect when the end surface of the rod-pusher acts on the locking element (ball), which leads to increased reliability valve operation.

An arrangement of nuts with holes in a circle in the lower part of the sleeve ensures, firstly, the free passage of the working medium from the space under the plunger rod disk, which ensures its movement towards the nut, and secondly, the passage of the lower part of the plunger rod through the axial hole of the nut improves centering of the push rod, which increases the reliability of the valve.

The execution of the end surface of the rod-pusher, in its upper part, in the form of a disk, reduces the complexity of its manufacture.

The check valve for the casing operates as follows. When direct washing, the flow of the working medium passes through the holes of the filter 14, the axial channel 3 of the seat 2, being cleaned of foreign objects and mechanical impurities. The cleaned flow creates pressure on the locking element 10, made in the form of a ball, which presses on the disk 9 of the rod-pusher 7, displacing it strictly in the axial direction, regardless of the location of the valve in space. When the rod-pusher 7 is moved to the lower part of the sleeve 6, an axial spring 8 is compressed, which is located between the disk 9 and the nut 11. When displaced by the flow of the ball 10 into the lower part of the sleeve 6, a gap is formed between it and the sealing sleeve 5, through which the flow passes of the working medium and then leaves the valve through the radial holes 13 and the holes 12 located in a circle in the nut 11. When washing is stopped, the axial spring 8 is unclenched and moves the push rod 7 and ball 10, firmly and reliably pressing ball 10 against the sealing collar those 5, preventing the backflow of the working medium from the annular space into the annular. Moving, the rod-pusher 7 is centered by the walls of the sleeve 6 with its upper part, having the shape of a disk 9, and the lower part with the walls of the axial hole of the nut 11.

Thus, the design of the inventive valve for the casing string provides an increase in the reliability of the valve and a decrease in the complexity of its manufacture.

Claims (1)

A check valve for a casing string, comprising a housing, a filter installed in it, a seat with an axial channel and a sealing collar fixed in it and a sleeve with radial holes pressing it to the seat, in which it interacts with a locking element made in the form of a ball with the possibility of axial movement , a rod-pusher with an axial spring, ensuring that the locking element is pressed against the cuff by the end surface of the rod-pusher in its upper part, characterized in that the end surface of the rod-pusher in its upper part it has the shape of a disk, the diameter of which is close to the inner diameter of the sleeve and is made with the possibility of centering the pusher rod when it is moved axially by the walls of the sleeve, and in the lower part of the sleeve a nut is fixed with holes in a circle and an axial hole, made with the possibility of centering the push rod through the axial hole.