RU2211307C1 - Device for stage cementing of casing string - Google Patents

Abstract

FIELD: oil producing industry; applicable in casing string cementing in two stages in oil and gas wells. SUBSTANCE: device has valve-coupling, case and check valve. Valve-coupling includes body with radial channels. Case is fitted on body and forms cavity with it. Check valve includes shutoff member in form of metal cylinder. Cylinder lower end is made in form of cone contacting case cone end, and cylinder upper end is spring-loaded. Body radial channels accommodate dead plugs extending inside body for engagement with shear unit. Shear unit is lowered into well on rope or cable. Shear unit consists of rod with conical external shoulder in lower part. Shear unit is connected from atop with weighing member and cable head. Rod from external side is made with cylindrical hollow over large part of length. Located in cylindrical hollow is circular stop and movable collet with two-sided circular stop on upper end and one-sided external stops on lower ends. EFFECT: higher reliability of cement mortar injection of the second stage. 2 dwg

Description

 The invention relates to the oil industry and can be used for cementing casing in two stages in oil and gas wells. The device can also find application in the secondary opening of formations.

 A known clutch for stepped casing cementing, including a housing with circulation holes and plugs installed in them, an abutment to close the housing sleeve, a landing sleeve under the separation tube [1].

The disadvantages of the device:
- the internal section of the coupling is less than the internal section of the casing due to the damper closing the circulation holes;
- when drilling cement stone inside the coupling, depressurization of the column is possible due to the destruction of the damper protruding into the inside of the column.

 The closest in technical essence to the proposed one is a device containing a valve coupling, lowered into the well as a part of a casing string, including a housing with radial channels, a housing worn on the housing and forming a cavity with it, and a check valve that includes a shut-off element [2] .

 The known device has a low operational reliability.

 Due to the small passage of the valve, several such devices are installed on the casing. And since the valve shutoff element is made of elastically deformable material, the valve control is difficult to control, it is possible that one valve is triggered and another one does not work, or their operation is not simultaneous, which casts doubt on the efficiency and reliability of the cement mortar injection operation of the second stage and ensuring the proper quality of the cement stone behind the casing the column.

 The objective of the invention is to provide a device with higher operational reliability and ensuring the guaranteed success of the operation for the injection of cement mortar of the second stage.

 This problem is solved by the proposed device containing a valve coupling, comprising a housing with radial channels, a casing, worn on the housing and forming a cavity with it, and a check valve that includes a shut-off element.

 What is new is that the check valve closure is a metal cylinder, the lower end of which is made under a cone in contact with the conical end of the casing, and the upper end is spring-loaded; deaf hollow plugs are installed in the radial channels, protruding into the body with the possibility of interaction with a shear assembly, lowered into the borehole on a rope or cable and consisting of a rod with a conical outer ledge in the lower part and connected from above with a weighting agent and cable head, and the rod with an external the side is made with a cylindrical sample over most of the length in which an annular stop is fixed, fixed by shear elements, and a movable collet with a double-sided ring stop is installed on the upper and nostoronnimi external fitting at the lower end.

Figure 1 shows a longitudinal section of a valve coupling lowered into the well as part of a casing, and a shear assembly at the time after the injection of cement mortar of the first stage;
figure 2 - the time of injection of the cement mortar of the second stage.

 The device consists of a valve coupling (Fig. 1), which includes a housing 1 with radial channels 2, in which blind hollow plugs 3 are installed, protruding into the interior of the housing and having a weakened cross-section 4. A housing 5 is mounted on the housing, the upper end of which is made conical and in contact with the conical surface of the lower end of the shut-off element of the check valve 6. Between the upper end of the shut-off element and emphasis 7, a spring 8 is installed.

 The shear assembly of the device contains a rod 9 with a conical outer ledge 10 in the lower part, and the upper part is connected to a weighting agent 11 (1-3 pcs tubing), which, in turn, is connected to the cable head 12. The rod 9 with the outer the side is made with a cylindrical sample 13 at most of the length in which the annular stop 14 is located, fixed by shear elements 14a, and a movable collet 15 is installed, having a double-sided ring stop 16 at the upper and one-sided outer stops 17 at the lower ends.

 The device operates as follows.

 The casing string 18 (FIG. 1) with a shoe 19, a cementing valve 20 and a seat 21 is lowered into the well to the design depth. A casing valve is installed in the casing string, which should be located above the roof of the reservoir 22 (~ 150-200 m).

 The calculated volume of cement of the first stage is pumped into the siege string using a separation plug 23. After the Stop signal is received, the cement slurry is stopped and immediately a shear device is lowered into the casing or cable 24 into the casing, which, reaching the blank hollow plugs 3 stops. In this case, the lower stops 17 of the collet 15 will fall below the blind plugs 3, and the upper emphasis 16 will sit on them with the outer side. This moment is determined by the unloading of the cable. Then the cable is tensioned, the collet 15 and the stem 9 move up until the collet with the lower stops 17 rests against the blind hollow plugs 3, the rod continues to move upward and enters its outer ledge 10 into the collet, and the latter with its inner ring stop 16 rests against the annular ledge 14 on the rod 9.

 With further cable tension, the plugs are destroyed, which occurs at a load of no more than 3 tf, while the cable load drops sharply, after which the shear assembly is raised to the surface and the annulus is flushed above the coupling valve in order to remove excess cement mortar. After waiting for the hardening of cement (OZZ) into the well, lower the tubing string 25 to the coupling valve (Fig. 2). Then the mouth is sealed and the calculated volume of cement of the second stage is pumped through the valve sleeve. After the cessation of the sale, the check valve 6 reliably closes the annulus. By reverse or direct washing, excess cement slurry is removed from the casing, tubing is removed and the borehole well is left.

 In the event that the hollow plugs did not collapse under a load of up to 3 tf, with further cable tension, the shear elements 14a holding the annular stop 14 are destroyed, thereby releasing the collet 15 and thereby preventing an emergency.

 The use of destructible hollow plugs, a spring-loaded metal non-return valve with a large throughput and a shear assembly increases the reliability of the device as a whole and guarantees high quality of the operation for pumping cement of the second stage and cement stone behind the casing.

Sources of information
1. A.S. USSR 1694861, MKI E 21 V 33/14, 1991 (analog).

 2. RF patent 2029066, MKI 6 E 21 V 33/13, published. 02/20/1995, (prototype).

Claims (1)

 A device for stepwise cementing of a casing string comprising a valve sleeve including a housing with radial channels, a casing worn on the housing and forming a cavity with it, and a check valve comprising a shut-off member, characterized in that the shut-off member of the check valve is a metal cylinder, the lower end of which is made under the cone in contact with the conical end of the casing, and the upper end is spring-loaded, blind hollow plugs are installed in the radial channels, which protrude into the inside of the housing action with a shear assembly, lowered into the well on a rope or cable and consisting of a rod with a conical outer ledge in the lower part and connected from above with a weighting agent and cable head, and the rod on the outside is made with a cylindrical selection for most of the length in which the annular an emphasis fixed by shear elements and a movable collet with a double-sided annular emphasis on the upper and one-sided outer stops at the lower ends.

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