RU2603110C1 - Method of placing cement plug in cased well and device therefor - Google Patents

Abstract

FIELD: oil industry.

SUBSTANCE: invention relates to oil and gas industry and can be used during testing and repair of oil and gas wells with installation of a cement bridge. Method comprises lowering into a well on a working string a device consisting of shoe assembly, shank and packer-anchor. Then well is washed, followed by successive pumping of first buffer liquid, grouting mortar, a second buffer fluid and displacement fluid. Cement plug is passed between backfill solution and second buffer liquid. Shoe assembly is located in lower interval of placing cement plug, and in upper interval of placing cement plug is placed packer-anchor, consisting of packer assembly and anchor unit, fixed by a shear pin. Packer-anchor also includes a check valve. When cement plug passes through packer assembly separating plug removes hollow pin and opens delivery channel to communicate hydraulic chamber with intra-string space. After placing cement plug in shoe unit, anchor unit is actuated by raising pressure, as a result of which packer-anchor is fixed in casing string and detached from working string. Cement plug is fixed in shoe assembly. Grouting mortar is placed in range of placing cement plug in annular space between casing and shank, as well as above packer-anchor at its margin for replacement of volume, released after lifting shank with shoe assembly from interval of installing cement bridge. Second buffer fluid and displacement liquid are placed inside shank and working string. Then working string with shank is lifted to interval of arrangement of packer-anchor. When shoe assembly exits packer-anchor, closure of closing check valve is provided, covering central channel of packer-anchor. Further, using spring-loaded cams through shoe assembly of working string, axial load is generated on upper part of packer-anchor and packing is performed. By further increase of pressure in working string in shoe assembly, circulation holes are opened and second buffer fluid is used to wash out excess grouting mortar from interval above installation of packer-anchor. Then working string with shank and shoe assembly is lifted to surface.

EFFECT: technical result is higher reliability, safety, reduced volume of technological operations and preservation of mineral resources during installation of cement plug.

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Description

The invention relates to the oil and gas industry and can be used in testing and repair of oil and gas wells.

There is a method of installing a cement bridge in a well, in which a shoe is lowered to the lower boundary of the cement bridge in a well on a tubing string. Moreover, before lowering into the well between the tubing string and the shoe, a nozzle with radial holes is installed, above which the nozzle is equipped with an annular groove with an annular narrowing, and below it a landing saddle of a smaller inner diameter than the inner diameter of the annular narrowing. Between the cement mortar and the squeezing liquid, a squeezing plug with a fixing head is installed, which is fixed in the annular groove of the annular narrowing after the cement mortar is pumped into the annulus. After that, the pipe is lifted on the tubing string to the upper boundary of the cement bridge and an overpressure is created sufficient to push the cork through the annular narrowing and fix it in the seat saddle with the radial channels of the pipe through which excess cement is washed out. Excludes the dilution of the cement due to the tight overlap of the pipe space in the tubing string when lifting the pipe to the upper boundary of the cement bridge [RF Patent No. 2435937, E21B 33/16, publ. 12/10/2011].

The disadvantages of this method is the inability to install a small length of cement bridges under pressure and with high accuracy.

There is a method of installing cement bridges under pressure in a cased hole, which includes a descent into the well on the tubing string of the packer together with a circulation valve located on the starting device, after which, by dropping the shut-off ball into the tubing, a starting device is actuated that fixes the packer in the production string with the help of retractable dies and at the same time opens the circulation channels through which the well is flushed, cement mortar is pushed into the specified interval, then it is sealed from the wellhead and squeeze the cement mortar under pressure into the formation or annulus through the perforations of the production string, then, without reducing the pressure, unpack the packer sealing element by tightening the tubing string while closing its circulation holes and disconnecting the starting device, leaving it under pressure cement mortar in the under-packer zone, after which the pressure in the tubing is reduced, the wellhead is depressurized, excess cement slurry is washed out from the overpacker oh zone and raise to the surface of the tubing along with the starting device [RF Patent No. 22487824, E21B 33/13, publ. 03/10/2005].

The disadvantages of this method is the inability to ensure complete replacement of the process fluid under the packer with grouting mortar, as well as the limitations of the use of this method at intervals with impermeable and poorly permeable formations.

A device for installing a cement bridge under pressure in a cased hole is known, including a packer with a sealing element made in the form of a toroidal ring enclosed in a perimeter split, closed on the outside and with a gap on the inside, a metal shell, retractable dies, the packer is equipped with a spring trigger device, located on the bottom of the housing of the trigger device.

The disadvantage of this device is the complexity of the spring starting device and the inability to eliminate mixing between the process fluids in the pipe string and in the interval of installation of the cement bridge [RF Patent No. 22487824, E21B 33/13, publ. 03/10/2005].

The challenge faced by the invention is to develop a reliable and safe method for installing a cement bridge in a cased hole.

Achievable technical result, which is obtained as a result of the creation of the invention, is to ensure reliability, increase safety, reduce technological operations and preserve mineral resources when installing a cement bridge.

The task and the technical result for the object - the method is achieved by the fact that in the method of installing a cement bridge in a cased well, including the descent into the well on the working string of the device, consisting of shoe assembly, liner and packer-armature, flushing the well and sequential injection of the first buffer fluid , cement slurry, a second buffer fluid and squeezing fluid, while between the cement slurry and the second buffer fluid pass the separation plug, the shoe assembly is placed in the bottom during the installation interval of the cement bridge, and in the upper interval the packer-anchor is placed, consisting of a packer assembly and an anchor assembly fixed by a shear pin, and also including a check valve, when the separation plug passes through the packer assembly, the separation plug knocks the hollow pin and opens the discharge channel for communication of the hydraulic chamber with the annular space, and after the separation plug is inserted into the shoe unit, the anchor unit is activated by increasing the pressure, as a result of which the packer the core is fixed on the casing and detached from the working string, and the separation plug is fixed in the shoe unit, while the cement slurry is placed in the interval of the cement bridge installation in the annular space between the casing and the liner, as well as above the packer-anchor based on its replacement margin the volume released after lifting the shank with the shoe assembly from the interval of installation of the cement bridge, the second buffer fluid and displacement fluid are placed inside the shank and the working column, s Then the working column with the shank is lifted to the interval of placement of the packer armature, at the moment the shoe assembly leaves the packer armature, the check valve closes the central channel of the packer armature, and then using the sliding cams, an axial axle is created through the shoe assembly load on the upper part of the packer-anchor and packer is produced, by subsequent increase in pressure in the working column in the shoe node, circulation holes are opened and excessively washed with a second buffer liquid a good grouting mortar from the interval above the packer-anchor installation, then the working column with a liner and shoe assembly is raised to the surface.

The task and the technical result for the object - the device - are achieved by the fact that the device for installing a cement bridge in a cased well, lowered into the well on the working string, includes a shoe assembly, a shank and a packer-anchor, while the shoe assembly is connected to the shank, consists of housings with circulation openings and spring-loaded cams fixed in it on the axes, a housing sleeve is placed in the housing overlapping the circulation holes, longitudinally made on the outer surface of the landing sleeve grooves for the possibility of entry of spring-loaded cams into them, and annular grooves are made in the inner surface of the bushing for fixing the separation plug, while the bushing is fixed in the housing using retractable pins located in the longitudinal grooves of the bushing, and interacting with the spring-loaded cams, the shank consists of sleeveless tubing, a spring centralizer is fixed in the lower part of the shank, the packer-anchor consists of a packer assembly and an anchor assembly, fix They are equipped with a shear pin on the rod, and also include a check valve, the packer-anchor is connected to the working string during descent, and after descent at a specified interval, it is fixed in the casing, the discharge channel is closed in the rod, closed by a hollow pin, the rod is connected to the working column and shank while the outer surface of the rod is part of a plunger pair with a piston of the anchor assembly, which form a hydraulic chamber with the packer-armature body.

The claimed group of inventions meets the requirement of unity of invention, since it forms a single inventive concept, moreover, one of the objects of the group — the device — is intended to implement another claimed object of the group — the method. In this case, both objects are aimed at solving the same problem with obtaining a single technical result.

Reliability, increased safety and preservation of the subsoil is ensured by the fact that the shoe assembly is located in the lower interval of the cement bridge installation, and the anchor packer is placed in the upper interval of the cement bridge installation, which eliminates the need to trap the process fluid in the reservoir, and also reduces the number of technological operations when installing a cement bridge, since they, for the most part, are carried out automatically.

In FIG. 1, 2 and 3 show a diagram of a method for installing a cement bridge in a cased hole using a packer anchor. In FIG. 1 shows an arrangement of a device lowered into a well during the interval of installation of a cement bridge; FIG. Figure 2 shows the operations of the end of the grouting grouting, fixing the separation plug in the shoe assembly, unpacking the packer anchor from the work string, and fixing the packer anchor in the casing. In FIG. Figure 3 shows the operations of packing, closing the non-return valve blocking the central channel, opening the circulation holes and washing out the excess cement slurry from the overpacker zone.

A device for installing a cement bridge in a cased hole, lowered into the well on the working string 1, includes a shoe assembly 2, a liner 3 and a packer-anchor 4. The shoe assembly 2 is connected to the liner 3. The shoe assembly 2 consists of a housing 5 with circulation holes 6 and spring-loaded cams fixed on it on the axes 7. In the housing 5 there is a seat sleeve 8 overlapping the circulation holes 6. Along the outer surface of the seat sleeve 8, longitudinal grooves 9 are made for spring-loaded cams 7 to enter into them, and An annular groove 10 is made for the inner surface of the bushing 8 to fix the separation plug 11. The bushing 8 is fixed in the housing 5 using retractable pins 12 located in the longitudinal grooves 9 and interacting with the spring-loaded cams 7. The shank 3 consists of sleeveless tubing ( not shown), a spring centralizer 13 is fixed in the lower part of the shank 3. The packer-anchor 4 consists of a packer assembly 14 and an anchor assembly 15 fixed by a shear pin 16 on the rod 17, and also includes a reverse cl apan 18. The packer-anchor 4 is connected to the working string 1 during descent, and after descent to the specified interval it is fixed in the casing 19. In the rod 17 there is a discharge channel 20 closed by a hollow pin 21. The rod 17 is connected to the working column 1 and the shank 3 wherein the outer surface of the rod 17 is part of a plunger pair with a piston 22 of the anchor assembly 15, which form a hydraulic chamber 24 with the housing 23 of the packer-armature 4.

The method by means of the device is as follows.

On the working column 1 (Fig. 1), a device for installing a cement bridge descends into the well at a predetermined interval, including a shoe assembly 2, a liner 3 and a packer-anchor 4. In this case, the packer-anchor 4 consists of a packer assembly 14 and an anchor assembly 15. During the descent into the well, the packer-anchor 4 is fixed with a shear pin 16 on the rod 17 and connected to the working column 1. The shoe assembly 2 is placed in the lower interval of the cement bridge installation, and the packer-anchor 4 is in the upper interval of the cement bridge installation. Then the well is washed and the first buffer fluid (not shown), grouting fluid 25, the second buffering fluid 26 and squeezing fluid are sequentially pumped, and between the grouting mortar 25 and the second buffering fluid 26 a separation plug 11 is passed. During the grouting grouting 25, when passing the separation plug 11 through the packer-anchor 4 knocks the hollow pin 21 and opens the discharge channel 20 for communication of the hydraulic chamber 24 with the annular space, thereby activating the anchor node 15. At the end of selling cement slurry 25, the separation plug 11 sits in the landing sleeve 8, located in the housing 5 of the shoe node 2, is fixed in it using ring grooves 10 and overlaps the central channel (not shown) of the shoe node 2 (Fig. 2) . After that, the pressure is increased in the work string 1, which is transmitted through the injection channel 20 to the hydraulic chamber 24 and to the piston 22 of the anchor assembly 15. As a result, the anchor assembly 15 is activated, the packer-anchor 4 is fixed in the casing and detached from the work string 1. In this case, the cement slurry 25 is placed in the interval of installation of the cement bridge in the annular space between the casing 19 and the liner 3, as well as above the packer-anchor 4 based on its stock to replace the volume released after lifting liner 3 with shoe unit 2 from the interval of installation of the cement bridge. The second buffer liquid 26 and the squeezing liquid (not shown) are placed inside the shank 3 and the working column 1. Then, the working column 1 with the shank 3 and the shoe assembly 2 is lifted to the interval of placement of the packer anchor 4. When the shoe assembly 2 passes through the packer anchor 4 spring-loaded cams 7 are retracted into the longitudinal grooves 9 of the housing 5, thereby transmitting force to the pins 12, which move and release the landing sleeve 8 in the housing 5. The spring centralizer 13, when passing through the packer-anchor 4, is compressed to its morning diameter. At the moment the shoe assembly 2 exits the packer armature 4, the check valve 18 is closed, blocking the central channel (not shown) of the packer armature 4. After that, using the spring-loaded cams 7, the axial load is created through the shoe assembly 2, the working column 1 the upper part of the packer-anchor 4, as a result of this, the packing and sealing of the upper interval of installation of the cement bridge is carried out (Fig. 3). A subsequent increase in pressure in the workstring 1 in the shoe assembly 2 opens the circulation openings 6 and, using the second buffer 26 and squeezing (not shown) liquids, the excess cement slurry 25 is washed out of the interval above the packer-anchor installation 4. Then, the workstring 1 with the rod 17, the shank 3 and the shoe assembly 2 are raised to the surface.

The implementation of this method of installing a cement bridge allows you to get the following advantages compared to the traditionally used technology for installing cement bridges:

- significantly or completely decreases the mixing zone of cement slurry with process fluids in the interval of installation of the cement bridge;

- hermetically close with the help of a packer-anchor the upper interval of the bridge installation, creating the conditions for the formation of a reliable cement stone;

- to exclude the operation of sealing the mouth when installing a cement bridge;

- perform all operations in one run and exclude from the process cycle the time to wait for the cement to harden;

The simplicity of the design of the device allows you to perform standard operations to change the internal pressure in the working column and its axial movement to implement the installation of a cement bridge.

Claims (2)

1. A method of installing a cement bridge in a cased hole, including a descent into the well on the working string of a device consisting of a shoe assembly, a liner and a packer armature, flushing the well and sequentially pumping the first buffer fluid, grouting fluid, second buffer fluid and squeezing fluid, a separation plug is passed between the cement slurry and the second buffer fluid, the shoe assembly is located in the lower interval of the cement bridge installation, and in the upper interval of the cement bridge installation of the bridge, a packer-anchor is placed, consisting of a packer assembly and an anchor assembly fixed by a shear pin, and also including a check valve, when the separation plug passes through the packer assembly with a separation plug, the hollow pin is knocked down and the discharge channel is opened for the hydraulic chamber to communicate with the annular space, and after planting the separation plug in the shoe assembly by raising the pressure actuates the anchor assembly, as a result of which the packer-anchor is fixed on the casing and detached from the working the columns, and the separation plug is fixed in the shoe unit, while the cement slurry is placed in the interval of the cement bridge installation in the annular space between the casing and the liner, and also above the packer-anchor based on its stock to replace the volume released after lifting the liner with the shoe unit from the interval of installation of the cement bridge, the second buffer liquid and squeezing liquid are placed inside the liner and the working column, then the working column with the liner is raised to the interval the packer-anchor, at the moment the shoe assembly leaves the packer-anchor, the check valve closes the central channel of the packer-anchor is closed, after which, using the sliding cams, the axial load on the top of the packer-anchor is created through the shoe assembly by the working column and produce packing, followed by increasing the pressure in the working column in the shoe node, open the circulation holes and, using a second buffer liquid, wash the excess cement slurry from the interval above the packer-anchor installation, then bochuyu column shoe and shank assembly raised to the surface. 2. A device for installing a cement bridge in a cased hole, designed to be lowered into the well on a working string, including a shoe assembly, a liner and a packer-anchor, while the shoe assembly connected to the liner consists of a casing with circulation holes and mounted on it axes with spring-loaded cams, a landing sleeve is placed in the housing overlapping the circulation holes, longitudinal grooves are made on the outer surface of the landing sleeve to allow spring-loaded cams to enter, and annular grooves are made for the inner surface of the bushing to fix the separation plug, while the bushing is fixed in the housing with the help of retractable pins located in the longitudinal grooves of the bushing and interacting with spring-loaded cams, the shank consists of sleeveless tubing, the bottom of the shank is fixed spring centralizer, packer-anchor consists of a packer assembly and an anchor assembly, fixed with a shear pin on the rod, and also includes a check valve, during descent, the core anchor is connected to the working string, and after descent at a predetermined interval, it can be fixed in the casing, the discharge channel is closed by a hollow pin, the stem is connected to the working string and shank, while the outer surface of the stem is part of a plunger pair with the piston of the anchor assembly, which form a hydraulic chamber with the packer-anchor body.

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