RU2298085C1 - Device for well cleaning of sand plug - Google Patents

Abstract

FIELD: oil production, particularly to repair wells involved in flushing operation.

SUBSTANCE: device comprises pipe string, connection pipe sealed from below and concentrically installed in hollow body. The hollow body is provided with cylindrical head connected to lower end of hollow body. Device also has branches, which communicate connection pipe interior with sand plug creation zone, self-packing collar with clamping nut, limiter and receiver bushing provided with central channel. The bush may perform limited axial movement with respect to the body. Connection pipe has check valve arranged over branches. Outer ribs are created over receiver bushing. Cap is installed below receiver bushing and over branches so that the cap may hermetically cooperate with central channel of receiver bushing. The receiver bushing has self-packing collar and side channels located over lower seal of self-packing collar made as inflatable sleeve. Upper sleeve end is fixedly retained by means of clamping nut in air-tight manner. Limiter is secured to receiver bushing from below and encloses the body from outer body side to provide air-tight axial displacement thereof. Upper end of connection pipe cooperates with technological bushing and provides limited axial displacement thereof in air-tight manner. The technological bushing is fixed to pipe string and is provided with radial channels, which may be communicated with pipe string interior or may be sealed with connection pipe.

EFFECT: simplified structure, increased operational efficiency and reliability.

2 dwg

Description

The invention relates to the oil industry and can be used in the routine and overhaul of wells associated with flushing wells with absorbing formations from sand plugs, mud sediments, scale, etc.

A device for washing sand plugs (ed. St. SU No. 857428, IPC 7 ЕВВ 21/00, published in BI No. 31 of 08/23/1981), comprising a housing with a concentrically placed tubing connected to a tubing string in it a pipe forming an annular cavity with it.

The disadvantage of this device is that it does not prevent the absorption of washing liquid when cleaning the perforation holes of the filter from sand plugs. Therefore, as the plug is removed from the bottom and the filter is cleaned, the absorption rate of the washing liquid increases and the circulation and the removal of sand pulp to the surface cease. In this case, suspended particles of sand and dirt are deposited in the wellbore, which leads to severe emergency situations: pipe sticking, prolonged shutdown of wells for overhaul. The cessation of flushing due to absorption of the liquid leads to the fact that the well remains unpurified from the plug and is put into operation with a low flow rate, an increased content of mechanical impurities in the produced products, which leads to premature failure of the pumping equipment or standstill of the well due to the inability to remove cork flushing.

A device for washing sand plugs (ed. St. SU No. 1081334, IPC 7 Е21В 21/00, published in BI No. 11 of 03/23/1984), comprising a housing with a concentrically placed tubing connected to a tubing string in it a pipe forming an annular cavity with it, two elastic cuffs installed in the upper and lower parts of the housing, and the coupling has radial channels for communicating the annular cavity formed by the housing and the pipe with the annulus.

The disadvantages of this device is that the cuffs are in constant contact with the walls of the well, resulting in friction, which leads to gradual wear of the cuffs during the descent of the device to the sand plug, especially in deep wells, which leads to a decrease in tightness during the washing of the sand plugs and, as a result, to an increase in the flow rate of flushing fluid in absorbing wells; in addition, in paraffin wells during the descent process, due to tight contact, the cuff may break, which reduces the efficiency of the device.

The closest in technical essence is a device for cleaning wells from sand plugs (patent RU No. 33600, IPC 7 ЕВВ 30/00, 21/00, published in BI No. 30 dated 10.27.2003), containing a pipe concentrically installed in a hollow body on which a self-sealing sleeve is installed, while it is provided with a hollow cylindrical nozzle connected to the lower part of the hollow body, provided with an installation sleeve on which the self-sealing sleeve is located, and a clamping nut mounted on the outer surface of the body, in addition, the hollow the housing has the ability to axially move a certain length relative to the installation sleeve, which allows you to create a limited load when pressing the self-sealing cuff to the walls of the well, equipped with a tip having longitudinal grooves on the outer surface and installed in the upper part of the body, equipped with four bends located radially in the hollow body and communicating the inner space of the bottom plugged with a sand plug formation zone.

The disadvantages of this device are:

- firstly, the complexity of the design, due to the large number of nodes and parts;

- secondly, when unloading the device onto the sand plug, the traction may be bent or broken, and therefore the optimal distance for effective erosion of the sand plug may be violated, and this reduces the reliability of the device;

- thirdly, in the process of cleaning a well from a sand plug, the pressure of the flushing fluid above and below the self-sealing cuff is approximately equal, as a result of which wells with low reservoir pressure absorb the flushing fluid by the layers, and therefore the removal of the eroded sand plug to surface, which reduces the efficiency of the device in such wells.

An object of the invention is to simplify the design of the device, as well as improving the reliability and efficiency of the device in wells with absorbing formations having low reservoir pressure.

The technical problem is solved by a device for cleaning a well from a sand plug, containing a pipe string, a nozzle plugged from below and concentrically mounted in a hollow body, which is equipped with a cylindrical nozzle mounted on the lower end of the hollow body, and bends connecting the inner space of the pipe with the sand plug formation zone self-sealing cuff with a clamping nut, a stopper and a mounting sleeve with a central channel, made with the possibility of limited axial movement of the relative but a hollow shell.

What is new is that the pipe is additionally equipped with a check valve above the taps, above the installation sleeve externally, with ribs, and below the installation sleeve, but above the taps, with a plug made with the possibility of tight interaction with the central channel of the installation sleeve, while the installation sleeve is equipped with a self-sealing sleeve and side channels located above the lower seal of the self-sealing cuff, made in the form of an inflatable sleeve, the upper end of which is rigidly and hermetically fixed clamping above the lateral channels of the installation sleeve, and the limiter is rigidly attached from below to the installation sleeve and covers the hollow body from the outside, with the possibility of tight axial movement, while the upper end of the pipe interacts with the possibility of limited tight axial movement with the technological sleeve rigidly connected to the pipe string and equipped with radial channels, which are made with the possibility of communication with the interior of the pipe string or hermetic shutoff pipe.

Figure 1 shows the proposed device in longitudinal section in the working position. Figure 2 shows a section aa of the proposed device.

A device for cleaning a well from a sand plug contains a pipe string 1 (see FIG. 1), a pipe 2 plugged from below and concentrically mounted in a hollow body 3, which is equipped with a cylindrical nozzle 4 mounted on the lower end of the hollow body 3, bends 5 connecting the inner space of the pipe 2 with a sand plug formation zone (not shown), a self-sealing sleeve 6 with a clamping nut 7, a stop 8 and an installation sleeve 9 with a central channel 10. The installation sleeve 9 is made with the possibility of limited axial displacement escheniya relative to the hollow body 3.

The pipe 2 is additionally equipped with a check valve 11 above the taps 4. Above the installation sleeve 9, ribs 12 are made outside (see Fig. 2), and below the installation sleeve 9 (see Fig. 1), but above the taps 5, there is a plug 13 (see Fig. 1), made with the possibility of tight interaction with the Central channel 10 of the installation sleeve 9.

The installation sleeve 9 is equipped with a self-sealing sleeve 6 and side channels 14 located above the lower seal of the self-sealing sleeve 6, made in the form of an inflatable sleeve 15. The upper end of the inflatable sleeve 15 is rigidly and hermetically fixed with a clamping nut 7 above the side channels 14 of the installation sleeve 9.

The limiter 8 is rigidly attached from below to the installation sleeve 9 and encloses the hollow body 3 from the outside with the possibility of tight axial movement 3. The upper end of the pipe 2 interacts with the possibility of limited tight axial movement with the technological sleeve 16, rigidly connected to the pipe string 1 and equipped with radial channels 17, which made with the possibility of communication with the inner space of the pipe string 1 or tight shutoff pipe 2.

Unauthorized fluid flows on mating surfaces are eliminated by o-rings 18, 19.

The device operates as follows.

The device assembly in the transport position on the pipe string 1 (for example, the tubing string) is lowered into the well until the device interacts with a toothed crown 20 (see Fig. 1), which is equipped with a stopper 8 with a sand plug in the well from below, during the descent of the device, the liquid in the well through the radial channels 17 of the process sleeve 16 enters the pipe string 1.

Next, the pipe string 1 is unloaded with the device at the end to the sand plug to be cleaned (control is carried out by the weight indicator installed at the wellhead), while the pipe 2 rises up relative to the process sleeve 16 and hermetically seals the radial channels 17 from the inside.

Unloading of the device is continued, while the technological sleeve 16, falling down, acts from above on the pipe 2, which together with the hollow body 3 moves down relative to the installation sleeve 9 and the limiter 9 rigidly connected with it until the technological sleeve 16 rests against the ribs from above 12 (see FIGS. 1 and 2), made externally at the top of the installation sleeve 9. The gear crown 20 of the limiter 8 fixes the device relative to the sand plug. Then, flushing fluid begins to be pumped into the annulus of the well (not shown).

The fluid flow from the annulus of the well enters from above into the central channel 10 of the installation sleeve 9, and then into the annular space between the pipe 2 and the installation sleeve 9 and then through the hollow body 3 through its cylindrical nozzle 4 enters the sand plug, eroding it. In this case, the fluid flow entering the central channel 10 of the installation sleeve 9 through the side channels 14 of the installation sleeve 9 inflates from the inside an inflatable sleeve 15, which is pressed against the inner walls of the well, while the pressure drop above and below the inflatable sleeve 15 additionally compresses the latter to the walls of the well hermetically separating the annulus of the well.

Further, the sand plug in the form of a water-sand mixture (not shown), washed out by the fluid flow, rises from the zone of formation of the sand plug and falls into branches 5 and further into the pipe 2 and is carried to the day surface along the pipe string 1.

As the sand plug is eroded, the pipe string 1 is lowered downward, and if necessary (depending on the height of the sand plug) they increase, while the pumping of the flushing fluid into the annular space of the well continues. The erosion of the sand plug continues until the flow of the sandy mixture washed out of the well visually decreases or the circulation ceases. This means that the sand plug is washed out to the formation, which began to absorb the flushing fluid and therefore the flow of fluid in the device no longer ensures that the sandy mixture in the pipe string 1 rises to the surface.

To remove the water-sand mixture located inside the pipe string 1 above the check valve 11 of the device, the pipe string 1 is raised from the wellhead by about 2-3 meters, first the process sleeve 16 goes out of contact with the ribs 13, then the process sleeve 16 is rigidly connected to the pipe string 1, rises upward relative to the pipe 2, while opening the radial channels 17 of the technological sleeve 16. At the same time, the technological sleeve 16 drags the pipe 2 and the hollow core rigidly connected to it mustache 3, causing limited axial movement relative to the installation sleeve 9 and the limiter 8 rigidly connected to it, a plug 13 mounted on the nozzle 2, hermetically seals from below the central channel 10 of the installation sleeve 9, while the fluid flow through the side channels 14 of the installation sleeve 9 continues to act on the inflatable sleeve 15, while continuing to press it against the walls of the well due to the pressure difference above and below it. As a result, the formation zone of the sand plug and the formation are hermetically cut off from the space of the well located above the device.

By supplying flushing fluid to the annulus of the well through open radial channels 17 of the process sleeve 16, the fluid flow enters the pipe string 1 above the check valve 11, which prevents the fluid from flowing down into the sand plug formation zone, from where the sandy water mixture is washed to the surface in a gutter or barn.

To continue cleaning the well from the sand plug, the pipe string 1 is lowered down until the device is unloaded onto the sand plug, after which the whole cycle of work described above is repeated. At the end of the well cleaning from the sand plug, the device is removed from the well.

The proposed device for cleaning wells from sand plugs has a simple structure and a more durable limiter, in addition, it is effective especially in wells having absorbing formations, due to cutting off the latter with subsequent washing out of the sandy mixture from the pipe string, thereby reducing the time for cleaning the well and financial savings.

Claims (1)

A device for cleaning a well from a sand plug, containing a pipe string, a nozzle plugged from below and concentrically mounted in a hollow body, which is equipped with a cylindrical nozzle mounted on the lower end of the hollow body, and bends connecting the inner space of the pipe with a sand plug formation zone, a self-sealing cuff with a clamping nut, a limiter and an installation sleeve with a central channel, made with the possibility of limited axial movement relative to the hollow body, characterized The fact that the pipe is additionally equipped with a check valve above the bends, above the installation sleeve externally, with ribs, and below the installation sleeve, but above the bends, with a plug made with the possibility of tight interaction with the central channel of the installation sleeve, while the installation sleeve is equipped with a self-sealing sleeve and side channels located above the lower seal of the self-sealing cuff, made in the form of an inflatable sleeve, the upper end of which is rigidly and hermetically fixed with a clamping nut above new channels of the installation sleeve, the limiter being rigidly attached from below to the installation sleeve and enveloping the hollow body with the possibility of tight axial movement, the upper end of the pipe interacting with the possibility of limited tight axial movement with the technological sleeve rigidly connected to the pipe string and equipped with radial channels, which are made with the possibility of communication with the interior of the pipe string or tight shutoff pipe.

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