RU2271437C1 - Casing pipe cementing device - Google Patents

Abstract

FIELD: oil production, particularly to cement casing pipes of oil and gas wells.

SUBSTANCE: device comprises baffle ring made as connection pipe plugged from bottom and provided with longitudinal grooves and radial channels provided with upper annular ledge and conical bottom surface. Lower support ring is telescopically installed in lower casing collar. The lower support ring has conical boring formed in lower end thereof and mating conical surface of the connection pipe. The support ring is provided with shear members. Free shear member ends are inserted in longitudinal connection pipe grooves. The device is provided with upper support ring having annular boring in inner surface thereof and arranged in upper collar. Inner diameter of the upper support ring is equal to outer diameter of plug. The plug is arranged at lower end of flushing pipes and made as two telescopically connected members, namely upper and lower ones. The upper member is fixed to flushing pipes. The lower one is connected to upper member through shear members and is provided with fixer formed on outer surface thereof. Radial channels, which connect flushing pipe interior with annular space, are provided above the plug. Lower and upper collars are fastened one to another by connection pipe.

EFFECT: increased air-tightness after grouting mortar injection in the well.

2 dwg

Description

The invention relates to the oil industry, in particular to the technology of cementing casing strings in oil and gas wells.

A device for cementing a casing string, made in the form of a spring-loaded poppet type check valve, is installed on the lower end of the casing string being lowered into the well (RF Patent No. 2086752, IPC 6 E 21 B 33/14, 1997).

The disadvantages of the device:

- the need to top up the well during the casing run;

- at medium and high casing descent speeds, hydraulic fracturing is possible;

- the need to create backpressure at the wellhead during flushing and injection of cement slurry;

- there is no possibility of manufacturing all valve parts from drilled materials, which may complicate further deepening of the well.

The closest in technical essence to the proposed one is a device for cementing a casing string, including a “stop ring” in the form of a pipe muffled from below with longitudinal grooves and radial channels with an annular ledge at the top and a tapered surface at the bottom, telescopic to which a lower casing string is installed at the bottom support ring equipped with shear elements, the free ends of which are included in the longitudinal grooves of the nozzle, and has a conical bore in the lower end that is adequate to the conical surface of the cartridge ubka (application No. 2003114277 of 05/14/03. Decision on the grant of a patent of 04/12/04, IPC 7 E 21 B 33/14, 2004).

The disadvantage of this device is:

- due to the fact that the cement slurry is an abrasive material, during circular circulation when the cement slurry passes through the device, the mating (sealing) surfaces erode, which leads to insufficient sealing of these surfaces and the possible passage of the grout into the casing string.

The objective of the invention is to develop a device design that would provide reliable sealing of the device after pumping cement slurry into the well.

This problem is solved by the proposed device, which includes a “stop ring” in the form of a nozzle plugged from below with longitudinal grooves and radial channels with an annular ledge at the top and a tapered surface at the bottom, telescopically to which a lower support ring equipped with shear elements is installed in the lower casing sleeve the ends of which are included in the longitudinal grooves of the nozzle, and has in the lower end a conical bore adequate to the conical surface of the nozzle.

New is that the device is equipped with an upper support ring mounted in the upper sleeve, made with an annular bore on the inner surface in the lower part, the inner diameter of which is equal to the outer diameter of the plug located at the lower end of the washing pipes and made in the form of two telescopically connected parts, the upper of which is rigidly connected to the flushing pipes, and the lower is connected to the upper part by shear elements and is equipped with a spring clip on the outer surface, above the plug I have radial channels connecting the internal cavity wash tubes with annular space, and the upper and lower pipe couplings are connected.

Figure 1 shows the proposed device in longitudinal section, lowered into the well.

Figure 2 is the same in the process of pumping cement into the well.

The device is a “stop ring”, made in the form of a pipe 1 muffled from below (Fig. 1) with an annular ledge 2 on the outer surface, provided with longitudinal grooves 3 and radial channels 4. The muffled section 5 of the pipe 1 is made on the outside with a conical surface 6, the small base of the cone of which faces the upper part, and its diameter is equal to the outer diameter of the nozzle 1. Telescopically to the nozzle 1 opposite the longitudinal grooves 3 in the lower sleeve 7 is installed lower support ring 8, equipped with shear elements 9, its odnye ends of which are in longitudinal slots 3. The lower end of the support ring 8 is formed on the inner side tapered bore 10, an adequate taper surface 6 of nozzle 1.

Above the "stop ring" in the upper sleeve 11 is located the upper support ring 12 with an inner ring bore 13.

The device is equipped with a plug installed on the lower end of the washing pipes 14 and made in the form of two telescopically connected parts 15 and 16, the upper 15 of which are rigidly connected to the washing pipes 14, and the lower 16 is connected to the upper 15 by shear elements 17 and has a latch on the outer surface 18 in the form of a spring ring. Radial channels 19 are made above the plug and centralizers 20 are installed.

The couplings 7 and 11 are connected by a pipe 21. The device is equipped with seals 22. Details of the “stop ring”, the upper support ring 12 and the plug 16 are made of drillable materials.

The device operates as follows.

After the well has been prepared, the casing 23 is lowered to the design depth at the lower end of which the proposed device with shoe 24 is installed. The fluid flows freely into the casing. The annulus is sealed. Then, a column of flushing pipes 14 is lowered into the casing 23 with a plug at the end (15, 16), which passes through the upper support ring 12, is seated on the “stop ring” and partially unloaded. Under the influence of the load, the shear elements 9 are destroyed, after which the flushing pipes are raised to the position shown in figure 2, the annular space 25 is sealed at the mouth and the well is flushed. After that, grouting mortar is pumped through flushing pipes 14, radial channels 19, “stop ring” and shoe 24 into the annulus of the well, which, after it is exited to the mouth, is sent to the capacity of the casting unit and circular circulation is carried out, constantly monitoring the density of the grouting mortar at the inlet and well exit.

After stabilization of the cement slurry by density (this moment occurs after about one hour of circulation), the circular circulation is stopped and the calculated volume of the squeezing liquid is pumped through the washing pipes 14, leaving about 100 liters of the cement slurry in the washing pipes. Injection pressure is relieved. Under the influence of the pressure differential created by the column of grouting mortar in the annulus and directed from the bottom up, the plugged pipe 1 moves upward relative to the lower support ring 8 and wedges at the contact point of the conical surfaces 6 and 10, blocking the casing from the annular space. The washing pipes 14 are raised to the position where the plug enters the upper support ring 12 and the latch 18 abuts against the stop of the annular bore 13, while the radial channels 19 will be above the upper supporting ring 12. By direct or reverse washing through the annular space 25 and the washing pipes 14 remove the remaining cement slurry from the washing pipes 14. After that, the washing pipes are stretched, the shear elements 17 are destroyed, the plug parts 15 and 16 are disconnected, and the lower part 16 together with the “stop ring” above zhno overlap section of the casing from the cement slurry penetration due to the annulus. Flushing pipes with the upper part 15 plugs are lifted to the surface and the well is left on the OZZ (waiting for cement to harden).

Due to the fact that during the circular circulation of the cement slurry, the latter does not erode the sealing surfaces in the area of the upper support ring, reliable and guaranteed sealing of the bottom of the casing is achieved.

Claims (1)

A device for cementing a casing string in a well, including a “stop ring” in the form of a pipe plugged from below with longitudinal grooves and radial channels, with an annular ledge at the top and a tapered surface at the bottom, telescopically to which a lower support ring is provided in the lower casing sleeve equipped with shear elements whose free ends are included in the longitudinal grooves of the nozzle, and having a conical bore in the lower end that is adequate to the conical surface of the nozzle, characterized in that it is provided with an upper coupling with the upper support ring installed in it, made with an annular bore on the inner surface in the lower part, the inner diameter of which is equal to the outer diameter of the plug located at the lower end of the washing pipes and made in the form of two telescopically connected parts, the upper of which is rigidly connected with the washing pipes, and the lower one is connected to the upper part by shear elements and is equipped with a spring clip on the outer surface; above the plug there are radial channels connecting the inner strips there are flushing tubes with annular space, the lower and upper couplings being connected by a nozzle.

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