RU2754743C1 - Casing valve - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention relates to the oil industry, in particular to the cementing of casing strings. The casing valve contains a body with an axial channel, a saddle with axial and side channels, and a restricting sleeve. The lateral channels of the seat are radial, the inner cavity of the body is equipped with an annular recess communicating the upper and lower internal cavities of the valve through the radial channels of the seat, and an annular groove. The saddle is equipped with protrusions on the lower end, equipped with a retaining ring and fixed with shear pins with the possibility of limited longitudinal downward movement when the displacement plug is seated and fixed in the annular groove. Sealing elements are installed in the lower part of the saddle, which have the ability to tightly close the radial channels of the saddle. The restrictor sleeve is recessed and has an annular shoulder to limit the downward movement of the seat.

EFFECT: simplified valve design, increased reliability and efficiency of casing cementing.

1 cl, 3 dwg

Description

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

Known valve for casing (utility model patent RU No. 38193, IPC Е21В 34/10, 33/08, publ. 05/27/2004, bull. No. 15), containing a body, a stop with axial and side channels, a sleeve installed in axial channel of the limiter on the shear elements from above with the possibility of hermetically closing the side channels. The limiter is installed in the body with the possibility of limited axial movement, while the sleeve is equipped with radial holes with partial mutual overlap corresponding to the lateral channels of the limiter and is equipped with a plug at the bottom, and an annular protrusion with channels on top, and the annular protrusion is fixed in the body.

The disadvantages of this valve design are:

- firstly, the passageways for filling the string during the run have a small area, which can cause the effect of "pistoning". They can also become clogged with sludge during the descent process;

- secondly, there is a possibility that the restrictor, after the pressure is released inside the string, will not fully rise up to the annular ledge. As a result, the side channels may remain partially open and the cement from the annulus will again fall into the casing, which will lead to poor-quality cementing of the casing, or it will be necessary to keep the casing under pressure during the cement hardening operation.

The closest in technical essence is a valve for casing strings (patent RU No. 2335619, IPC Е21В 34/06, 33/14, publ. 10.10.2008, bull. No. 28), including a stopper with a seat and side channels, a sleeve that tight overlap of the 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 coupling, 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 sleeve is rigidly installed 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 recess 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 restrictor plug.

The disadvantages of this valve design are:

- firstly, unreliable seating of the squeezing plug into the restrictor, which can lead to breakage of the plug from the restrictor after the pressure inside the casing is released and the bottom of the casing is filled with cement from the annulus;

- secondly, 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 when running the casing into the well, when meeting all kinds of ledges and caverns, which can lead to the problem of filling the casing during running.

The technical challenge is to create a reliable and simple valve design for the casing, which allows guaranteed filling of the casing with downhole fluid during running, efficiently performing the cementing operation and hermetically closing the bottom of the casing after cementing.

The technical problem is solved by a casing valve, which includes a body with an axial channel, a saddle with axial and side channels, and a restricting sleeve.

The novelty is that the side channels of the seat are radial, the internal cavity of the body is equipped with an annular recess communicating the upper and lower internal cavities of the valve through the radial channels of the seat, and an annular groove, while the seat is equipped with protrusions on the lower end, is equipped with a retaining ring and is fixed with shear pins with the possibility of limited longitudinal movement downward when the squeezing plug is seated and fixed in the annular groove, and in the lower part of the saddle there are sealing elements that can tightly overlap the radial channels of the saddle, and the restricting sleeve is equipped with depressions and is equipped with an annular shoulder limiting the saddle movement downward.

Figure 1 shows the proposed valve for the casing in the transport position with a partial longitudinal section.

FIG. 2 is a bottom view.

FIG. 3 shows the proposed casing valve in working position with a partial longitudinal section.

The valve for the casing includes a body 1 (Fig. 1, 2) with an axial channel 2, a seat 3 with an axial 4 and side channels 5 and a restricting sleeve 6.

The side channels 5 of the seat 3 are radial (hereinafter referred to as radial channels). The inner surface of the body 1 is equipped with an annular recess 7, which communicates the upper and lower internal cavities of the valve through the radial channels 5 of the seat 3 in the process of running the casing string, and an annular groove 8. In this case, the seat 3 is equipped with protrusions 9 at the lower end, is equipped with a retaining ring 10 and is fixed shear pins 11 (Fig. 1) with the possibility of limited longitudinal movement of the saddle 3 (Fig. 1, 2) downward when the displacement plug 12 (Fig. 2) is fitted and fixed in the annular groove 8 (Fig. 1, 2) of the housing 1 with a retaining ring 10. Thus, after seating the displacement plug 12 (Fig. 2) and cutting the pins 11 (Fig. 1), the saddle 3 (Figs. 1, 2) moves down and is fixed (locked) in the annular groove 8 of the housing 1, reliably fixing the saddle 3 in this position. In the lower part of the saddle 3, sealing elements 13 are installed (Figs. 1-3), which have the possibility of hermetically closing the radial channels 5 (Figs. 1, 2) of the saddle 3. At the same time, due to the sealing elements 13, for example, made of oil and petrol resistant rubber, ( Fig. 1-3) ensures the tightness of the overlap of the upper and lower inner cavity of the valve. The axial rotation of the seat 3 is excluded (Figs. 1, 2). Moreover, the restricting sleeve 6 is provided with depressions 14 and is equipped with an annular shoulder 15 that limits the movement of the seat 3 downward. When moving down, the saddle 3 with the protrusions 9 with the lower end abuts against the depressions 14, which, when drilling out the saddle 3, prevent its axial rotation.

The casing valve works as follows.

A casing valve in the casing (not shown in FIGS. 1-3) is run into the well. In the process of running, the casing string is filled with downhole fluid through the axial channel 2 (Figs. 1, 2) of the housing 1, then enters the annular selection 7 and through the radial channels 5 of the seat 3. Upon reaching the predetermined interval of the well, the cementing operation is started according to the known technology. The calculated amount of cement slurry is pumped in, then the squeezing plug 12 is dropped (Fig. 2) and the cement slurry is pumped into the annulus. When the displacement plug 12 reaches the seat 3, it enters the axial channel 4 of the seat 3, closes the side channels 5, while the hydraulic pressure inside the casing increases, and at a certain (design) pressure, the pins 11 are sheared (Fig. 1). The saddle 3 with the displacement plug 12 (Fig. 2) moves downward until the seat 3 stops against the annular shoulder 15 of the restricting sleeve 6. In addition, the radial channels 5 are sealed off from the axial channel 2 of the housing 1 by sealing elements 13 (Fig. 3). And the retaining ring 10 (Fig. 2) of the saddle 3 is locked in the corresponding annular groove 8 of the housing 1, while reliably fixing the saddle 3 from axial movement. Thus, a stop pressure is obtained. After that, the pressure inside the casing is released and it is checked whether the seat 3 holds the pressure created by the cement slurry in the annulus. After that, the column is left for the cement slurry hardening operation.

If the technology requires drilling a valve, then a bit is lowered on the drill string and the valve is drilled out (for this it must be made of an easily drillable material). The rotation of the saddle 3 around its axis is excluded due to the fact that the saddle 3 is provided at the lower end with protrusions 9 (Fig. 1), which fall into the corresponding recesses 14 of the restrictive sleeve 6.

The proposed casing valve has a simple and reliable design, allows for guaranteed filling of the casing with downhole fluid during running, efficiently performing the cementing operation and hermetically closing the bottom of the casing after cementing.

Claims (1)

A valve for a casing string, including a body with an axial channel, a seat with axial and side channels and a restricting sleeve, characterized in that the side channels of the seat are radial, the inner cavity of the body is equipped with an annular recess communicating the upper and lower internal cavities of the valve through the radial channels of the seat, and an annular groove, while the saddle is equipped with protrusions on the lower end, is equipped with a retaining ring and is fixed with shear pins with the possibility of limited longitudinal movement downward when the displacement plug is seated and fixed in the annular groove, and sealing elements are installed in the lower part of the saddle that have the ability to tightly overlap the radial channels of the seat, and the restricting sleeve is provided with depressions and is equipped with an annular shoulder that limits the movement of the seat downward.

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