RU2568459C1 - Device for well cleanout from paraffin deposits - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: device consists of a barrel, a case, ring chamber, a valve as well as ring piston and pusher. The ring chamber is coupled hydraulically to radial openings made in the barrel with its axial channel and openings made in the case over the valve with annular space in the well. From overhead the valve is fixed rigidly to the ring piston with potential sealed shutoff of radial openings in the barrel from outside. The packing is made self-sealing and above it, at hydraulic actuator, there is a centring skid with outside longitudinal channels. Upstream the centring skid between the hydraulic actuator and pusher there is a packer made assembled of alternating rubber and metal rings. Rubber rings of the packer may be compressed axially and expanded radially outward.

EFFECT: higher reliability of the device.

2 dwg

Description

The invention relates to the oil industry and is intended for flushing the well from paraffin deposits, mainly in the axial channel of the pipe tubing during operation of the well without raising the production equipment.

The circulation valve is known (see Yu.V. Zaitsev, R.A. Maksutov, O.V. Chubanov, and others. Reference manual on the gas-lift method of operating wells. - M., Nedra, 1984, pp. 85-91) consisting of a body, in the axial channel of which a sleeve with bypass holes and two bores for the rams of the pusher of a controlled tool is installed, the sleeve is sealed with seals and fixed in two positions, the valve is opened and closed by moving the sleeve until its bypass holes coincide with the holes in the case, with than for the installation and operation of the circulation valve, it is installed as part of an elevator pipe string above the packer.

The disadvantages of this device are:

- firstly, to control the circulation valve, it is necessary to use special cable technology with the cost of working time for its control;

- secondly, it is necessary to include an additional packer in the composition of the arrangement to ensure overlapping of the annular space under the circulation valve;

- thirdly, the complication of the technology for equipping the well with an elevator column, which includes a packer, which requires special operations for its landing and extraction.

A circulation valve is also known (see “Construction of gas and gas condensate wells.” VNIIGAZ Scientific Collection, Moscow, 1997, pp. 18-21), consisting of a barrel connected to an elevator pipe string, while the body covers the barrel to form an annular chamber connected by circulating openings with an axial bore of the barrel equipped with an annular piston forming a movable connection with the casing, and the annular chamber is closed below by a screwdriver and contains a thrust sleeve, and circulating openings are made in the casing body the location of the sleeve, and the housing is pressed against the annular piston on the barrel due to the force of the spring, while supplying pressure of the working fluid into the annulus, the housing moves upward relative to the barrel with the location of the circulation holes in the housing at the location of the circulation holes of the barrel, the spring is on the outside the barrel is compressed, after the pressure is released by the force of a compressed spring, the housing returns to its original position with the termination of the hydraulic connection between the annulus and the axial channel of the pipe b of the elevator column, therefore, with excessive pressure inside the axial channel of the elevator column pipes, the valve is closed.

The disadvantages of this device are:

- firstly, the limited capabilities of the device, since when installing the device as part of the pipe tubing string in wells operated by sucker rod pumps, where paraffin deposits are deposited on the inner surface of the pipe tubing string, there is a need to remove it, while the removal technology consists in feeding along the annulus through the circulation valve of the heated working fluid, and the pressure drop at which the valve opens will depend on the installation depth and spring force;

- secondly, the supply of hot fluid through the annular space below the location of the valve leads to undesirable heating of the casing and lining of the well. To avoid this, it is necessary to include an additional packer in the composition of the arrangement to ensure overlapping of the annular space under the circulation valve;

- thirdly, the complication of the technology for equipping the well with an elevator column, which includes a packer, which requires special operations for its landing and extraction.

Also known is a circulation valve (see patent RU No. 2211195, IPC ЕВВ 34/06, published on September 10, 2003 in Bull. No. 25), comprising a housing in the form of a stepped cylinder with an axial channel and a seat in the bottom, movably placed in the housing a hollow stepped spool made with an annular piston rigidly connected to it and forming an annular chamber with the housing, channels in the housing connecting the annular chamber to the annulus, and an axial channel of the housing with the annular chamber, characterized in that it is equipped with an end valve, the housing is detachable as top and the lower parts with a saddle on the upper end of the lower part of the housing, the channels in the housing connecting the annular chamber with the annular space are made longitudinal in the place of the housing connector, the channel connecting the axial channel of the housing with the annular chamber is throttled, narrowing is performed in the lower part of the detachable housing with a sealing ring, the end valve covers the upper part of the split housing and has the ability to interact with the seat on the upper end of the lower part of the housing, the progress of the hollow stepped spool is rigidly connected th him stepped annular piston end face is limited to the upper part of the housing assembly, wherein a stepped annular piston in interaction with the sealing ring forms a seal, a stepped spool is biased, and the diameter of the stepped annular piston in the lower part than in the top.

The disadvantages of this device are:

- firstly, low reliability due to the fact that the device is included in the pipes of the pipe string and is installed at a predetermined depth during operation of the well with a rod pump, therefore, unauthorized formation of the hydrodynamic connection of the axial channel of the pipe string with the annular space under the influence of hydrostatic pressure is possible in the axial channel of the pipe tubing, above the installation site of the circulation valve;

- secondly, it is necessary to include an additional packer in the composition of the arrangement to ensure overlapping of the annular space under the circulation valve;

- thirdly, the complication of the technology for equipping the well with an elevator column, which includes a packer, which requires special operations for its landing and extraction.

The closest in technical essence is the circulation valve (see patent RU No. 2483195, IPC ЕВВ 34/06, published on 05/27/2013 in bull. No. 25), consisting of a barrel, a barrel is installed on the barrel, blocked by a stopper in the upper part , with a seat, in the annular chamber between the body and the barrel there is a valve supported on the seat, below is an annular piston connected to a pusher equipped with an expanding cone, on the outer surface of which a longitudinal groove is made, the annular piston is supported by a spring, and the annular chamber hydraulic It is precisely connected by radial holes made in the barrel with its axial channel and holes made in the body above the valve with the annulus of the borehole; below the location of the expanding cone, a hydraulic cylinder is mounted on the barrel, in which a piston with a cuff is installed, covering the sleeve rigidly connected to the bottom of the hydraulic cylinder and forming an annular gap with the barrel, which is constantly hydraulically connected by the drainage channel to the cavity of the well, the annular chamber under the piston is constantly hydraulically connected by the channel and a hole with the axial bore of the barrel, a groove is made on the outer surface of the expanding cone to provide hydraulic connection between the annulus above the cuff and the borehole below the installation location of the circulation valve.

The disadvantages of this device are:

- firstly, the complexity of the design, due to the large number of nodes and parts (expandable cone, sleeve, etc.);

- secondly, the high cost associated with a large number of technological parts difficult to manufacture (a longitudinal groove on the outer surface of the expanding cone, an annular gap and a drainage channel in the bottom of the hydraulic cylinder, etc.);

- thirdly, the low reliability of the operation, due to the rapid failure of the device due to the valve installed separately from the annular piston in the annular chamber between the body and the barrel, because after several cycles of operation by the action of hot fluid supplied to the annulus of the valve, at the same time separating the holes in the housing and the radial holes in the barrel loses its tightness, while the fluid flows freely from the tubing string into the annulus and back (between the radial holes in ol annular chamber through the openings in the housing), moreover, the device has a centralizer that when the device is descending the wellbore may cause damage (breaking) of the inner sleeve of the borehole wall;

- fourthly, when washing a well with hot fluid, a high overpressure is created in the annulus of the well, which can lead to a loss of tightness of the cuff (the cuff is torn). In addition, after flushing the well with hot fluid, it is necessary to transfer the hot fluid located in the annulus above the device (above the cuff) through a complex system of drainage channels into the annulus below the device (below the cuff).

An object of the invention is to simplify the design of the device without loss of operating efficiency, as well as reducing the cost of manufacturing the device by eliminating technologically difficult parts from the design of the device, increasing the reliability by finalizing the valve structure located in the annular chamber of the device, and eliminating damage to the cuff during the descent of the device into the well and the exclusion of loss of tightness of the device during the washing process due to the installation of the packer.

The stated technical problem is solved by a device for washing a well from paraffin deposits, consisting of a barrel, a housing mounted on the barrel and blocked in the upper part by a plug, an annular chamber formed between the housing and the barrel, a valve located in the annular chamber, and also installed in the annular chamber below the valve of the annular piston spring-loaded from the bottom of the housing, the pusher rigidly connected to the annular piston, the annular chamber is hydraulically connected by radial holes made in the barrel with it axial channel and apertures formed in the housing above the valve annulus with the wellbore.

What is new is that the valve is rigidly connected from above to the annular piston with the possibility of tight cut-off from the outside of the radial holes in the barrel, while the cuff is self-sealing, passing from the bottom up, and above the self-sealing cuff on the hydraulic cylinder, a centralizer is rigidly mounted with longitudinal channels outside, above the centralizer between the hydraulic cylinder and a pusher mounted packer, made of prefabricated from alternating rubber and metal rings, and the rubber rings of the packer have the possibility of axial compression and p dially outwardly expanding sealing annulus of the well when downward axial movement of the pusher when creating excess pressure in the annular chamber.

In FIG. 1 shows the proposed device during the operation of the well.

In FIG. 2 shows the proposed device when washing a column of elevator pipes from paraffin deposits.

A device for flushing a well from paraffin deposits consists of a barrel 1 (see Fig. 1), which is part of an elevator pipe string (not shown in Figs. 1 and 2), and a body 2 (see Fig. 1) mounted on the barrel 1 and blocked at the top by a stopper 3.

The device also includes an annular chamber 4 formed between the housing 2 and the barrel 1, a valve 5 located in the annular chamber 4, and also installed in the annular chamber 4 below the valve 5, the annular piston 6 spring-loaded 7 from the bottom of the housing 2, the pusher 8, rigidly connected with annular piston 6.

The annular chamber 4 is hydraulically connected by radial holes 9 made in the barrel 1 with its axial channel 10 and holes 11 made in the housing 2 above the valve 5 with the annular space 12 of the well 13.

On the barrel 1 below the pusher 8, the hydraulic cylinder 14 is rigidly fixed, on which the cuff 15 is mounted.

The valve 5 is made annular and is rigidly connected from above to the annular piston 6 with the possibility of hermetically cutting off the outside of the radial holes 9 in the barrel 1.

The cuff 15 is made self-sealing, passing from the bottom up. Above the self-sealing cuff 15 on the hydraulic cylinder 14 is rigidly mounted centralizer 16 with longitudinal channels 17 from the outside.

Above the centralizer 16, between the hydraulic cylinder 14 and the pusher 8, a packer 18 is installed, made of a composite of alternating rubber 19 and metal 20 rings.

The rubber rings 19 of the packer 18 have the possibility of axial compression and radial expansion outward with sealing of the annular space 12 of the well 13 with the axial movement of the pusher 8 down while creating excessive pressure in the annular chamber 4.

The proposed device operates as follows.

The proposed device assembly is installed as part of an elevator pipe string (not shown in FIGS. 1 and 2) and is lowered into a well 13 to a predetermined depth below the level of paraffin deposits in the pipe elevator string. In addition, during the descent of the tubing string into the well 13, it is equipped with a sucker rod pump (not shown in FIGS. 1 and 2).

During the descent of the device into the well 13, damage to the self-sealing cuff 15 is eliminated due to the fact that the centralizer 16 is rigidly mounted on the hydraulic cylinder 14 above the self-sealing cuff 15 with longitudinal channels 17 outside, which allow the downhole fluid to flow from bottom to top through the device, while the centralizer 16 ensures alignment device and axis of the well 13, resulting in increased reliability of the device.

Turn on the well pump and start the well 13 in operation. The well pump lifts the formation fluid in the axial channel of the elevator column from the space 21 below the self-sealing sleeve 15.

The hydrostatic pressure of the liquid column existing in the annular space 12 of the borehole 13, for which the spring 7, for example, 7.0 MPa, is transmitted to the annular chamber 4 through the openings 11 of the housing 2, as a result of which the valve 5 seals the radial openings 9 in the barrel 1 from the outside, which excludes the flow of extracted products from the axial channel 10 of the barrel 1 of the device into the annular chamber 4.

The hydrostatic pressure of the liquid column existing in the annular space 12 of the borehole 13 acts from above on the self-sealing cuff 15, which seals the annular gap between the borehole 13 and the pipe lift string (not shown in Figs. 1 and 2), which eliminates the flow of liquid from top to bottom in the annulus the space 12 of the well 13.

In this position, the well 13 is in operation (see Fig. 1).

The device in comparison with the prototype has a simple design, and if necessary, work to remove paraffin deposits on the inner surface of the pipe pipe string stops the well 13, for which the well pump is turned off.

Next, hot fluid is supplied under excess pressure, for example, using a pump unit of the CA-320 brand, into the annulus 12 of the well 13. The hot fluid through the openings 11 of the casing 2 enters the annular chamber 4.

Under the action of excess pressure, for example, 10.0 MPa, which affects the cross-sectional area of valve 5 and the annular piston 6 (see figure 2), the valve 5 moves down and is located below the radial holes 9 in the barrel 1, which allows hot fluid into the axial channel 10 of the barrel 1, at the same time, the pusher 7 is axially moved relative to the barrel 1 and the hydraulic cylinder 14 fixed on it. As a result, the rubber rings 19 of the packer 18 are compressed in the axial direction and expand radially outward, while oiskhodit sealing annulus 12 of the well 13 above the self-sealing collar 15, the radial holes 9 of the barrel 1 communicates an axial passage 10 of the barrel 1 with the annulus 12 of the well 13 through the holes 11 of the housing 2.

The proposed device has high reliability due to refinement of the design of the valve located in the annular chamber of the device, while the valve 5 is rigidly connected to the annular piston 6 (forced action) and tightly closes only the radial holes 9 of the barrel 1.

After performing this operation to remove paraffin deposits, the flow of hot fluid under pressure is stopped.

When washing the well 13 with hot fluid in the annular space 12 of the well 13, a high overpressure is created, as noted above 10.0 MPa, while the packer 18, mounted above the self-sealing cuff 15 and made of a composite of alternating rubber 19 and metal 20 rings, is sealed position i.e. the rubber rings 19 are hermetically pressed against the inner walls of the borehole 13 (see FIG. 2), which excludes the self-sealing sleeve 15 from being perceived to have high overpressure (10 MPa), while the self-sealing sleeve 15 is not damaged (does not break).

At the end of the flushing, the supply of hot fluid to the annular space 12 of the well 13 is stopped, the pressure in the annular space 12 and in the tubing string are equalized, while due to the return force of the spring 7 (see Fig. 1), the valve 6 returns to its original position and blocks the radial holes 9 in the barrel 1.

Turn on the pump and start the well 13 in operation.

In the annular space 12 of the well 13, the self-sealing cuff 15 is made to pass from the bottom up, which allows the associated gas that is released from the oil to freely migrate into the cavity of the annular space 12 of the well 13 above the device during operation of the sucker rod pump and to prevent the complex system of drainage channels from being executed in the device. The proposed device in comparison with the prototype has a low manufacturing cost due to the exclusion from the design of the device of technologically difficult parts to manufacture, namely a longitudinal groove on the outer surface of the expandable cone, an annular gap and a drainage channel in the bottom of the hydraulic cylinder.

The proposed device for flushing wells from paraffin deposits has a simple design, low cost of manufacturing the device, high reliability and eliminates the loss of tightness of the device during the washing of the pipe string from paraffin deposits.

Claims (1)

A device for washing a well from paraffin deposits, consisting of a barrel, a housing mounted on the barrel and blocked by a plug in the upper part, an annular chamber formed between the housing and the barrel, a valve located in the annular chamber, and also installed in the annular chamber below the annular piston valve, spring-loaded from the bottom of the housing, a pusher rigidly connected to the annular piston, the annular chamber is hydraulically connected by radial holes made in the barrel with its axial channel, and holes made in the casing above the valve with the annular space of the well, characterized in that the valve is rigidly connected from above to the annular piston with the possibility of hermetically cutting off the outside of the radial holes in the barrel, while the cuff is self-sealing, passing from bottom to top, and above the self-sealing cuff, the centralizer is rigidly mounted with longitudinal channels outside, above the centralizer, a packer is installed between the hydraulic cylinder and the pusher, made of prefabricated from alternating rubber and metal rings, m rubber rings of the packer have the possibility of axial compression and radial expansion outward with sealing of the annulus of the well with axial movement of the pusher down while creating excessive pressure in the annular chamber.

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