RU2598674C1 - Scraper for cleaning internal surface of pipes - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention relates to drilling wells, in particular to devices for cleaning internal surface of tubes from sediments and clay cake. Device includes hollow housing with web in axial channel, in which perpendicular to axis of housing hydraulically connected by feed channel with axial channel of housing above web and discharge channel with hollow housing axial channel under it. On outer surface at its ends there are conical threads, under them on housing there are cylindrical threads and cylindrical grooves, on which there are lock nuts, limiting axial movement of scraper elements installed on cylindrical grooves with possibility of rotation. In cylindrical bore stepped piston with blind partition in middle part is installed, with separation of inner channel. Directed outward channel is made in form of transverse slot, in which there is roller with notches on rotation axis. Other part of channel, which faces to bottom of cylindrical bore of hollow housing is made in form of inner bore, in which there is filter in form of perforated washer, together with blind partition forming intermediate chamber hydraulically connected to annular chamber under stepped piston through drain holes in its body, and through slots in body of nut is with well cavity.

EFFECT: higher efficiency, possibility of regulating process and cleaning of working surfaces.

1 cl, 3 dwg

Description

The invention relates to the field of drilling oil and gas wells, in particular to devices for cleaning the inner surface of pipes from deposits.

A device for processing a wellbore is known (see AS No. 1357549, M.cl. E21B 37/02).

The device comprises a housing and scraper elements located along its axis with different stiffness, made in the form of loops of a metal cable of different diameters. The diameters of the loops are taken different for each diameter of the cable. The loop planes are mutually perpendicular to each other.

When moving the device in the axial channel of the pipe string, the loops act on the clay layer with its destruction or its compaction during rotation of the device.

The disadvantages of the design of the device include:

- a small force of action on the clay peel, since only the elastic force from the cable loop is used, which is not enough;

- there is no impact of the jet of working fluid on the surface to be cleaned to improve the cleaning of the pipe wall from clay cake.

- in the process of launching and lifting the device into the well, there is a constant contact of the cable loops with the pipe wall, which leads to their additional wear.

Known scraper (see.with. No. 853090, M.cl. E21B 37/02).

The scraper consists of a cylindrical body, working elements pressed against the body using brace sections, fastened to the working elements with clamps and connected to each other by locks, with controlled gates made in the form of a time switch, or a pressure switch, or a thermal relay made of water-soluble material.

Scraper operation

The device is installed as part of a casing string. In this case, the working elements are in the transport position and during descent they do not come into contact with the filter cake on the wall of the well. During the descent, the liquid medium interacts with the controlled shutters of the locks, which are dissolved by the liquid medium or by heat. In this case, the sections of the bandage are opened and the working elements are squeezed out to the walls of the well and interact with the clay crust and its destruction. The products of crust destruction by the flow of working fluid are carried out from the well.

The disadvantages of the design include:

- the design has a fairly high complexity, both when assembling it, and when bringing it to its working open position;

- after performing a technological operation to clean the inner surface of the pipe from clay cake, the working elements remain in the open position. When the device is cured from the well, this can lead to their premature wear and even an emergency situation when it is possible to introduce structural elements such as a shutter and a lock into the joint of the coupling connection;

- there are no conditions for control and regulated force impact of the working elements on the clay crust.

A device for cleaning the walls of the well (see AS No. 640021, M.cl. E21B 37/02).

The device consists of a housing, at the ends of which a thread is made for connection with a drilling tool. Metal brushes consisting of a base and elastic wire elements are attached to the body. Between the brushes along the body are attached deformation limiters of the elastic elements.

The clay crust is removed by elastic elements during rotation and axial movement of the device with a drill pipe string. The diameter, which is measured between opposing elastic elements, exceeds the inner diameter of the barrel by 25 ÷ 30 mm.

This suggests that during the descent and lifting of the device from the well, the elastic elements are in constant contact with the inner surface, with the destruction of the crust. It should be noted that in this case there is a rapid wear of these elements.

In addition, the force with which the elastic elements interact with the clay crust is small and depends only on the elastic properties of the working elements and cannot be controlled. The quality of the cleaning is not enough.

A well-known universal hydromechanical scraper (see Pat. RF No. 2336410, M.cl E21B 37/02), adopted as a prototype.

The scraper consists of a hollow cylindrical body with a hollow plunger inside, supported by a return spring. At the ends of the cylindrical body, connecting threads are made, and in the middle part, windows are made in which spring-loaded scraper elements are installed, which are installed with the possibility of interaction with the hollow plunger. The hollow plunger at its ends enters into interaction with the sleeves, the upper of which is connected to the crimping seat, and the lower sleeve is connected to the sleeve of the tubing.

To close the hollow plunger and move it, a thrown fitting element is used.

When the working fluid is supplied to the axial channel of the tubing string, the hollow plunger moves down in the axial channel of the cylindrical body with the scraper elements extended from the windows until it contacts the inner surface of the pipe being cleaned.

For crimping the tubing string from the surface, a crimping element is supplied with its seating on the crimping saddle. After crimping, the element is removed to the surface by backwashing.

Design disadvantages:

- the use of a crimping element and a waste choke element to control the scraper significantly increase the cost of working time;

- when using a waste choke element that prevents the free flow of working fluid into the cavity of the well, it is difficult to obtain a flow with a sufficiently high speed to ensure the removal of mechanical particles to the surface;

- it is known that pipes for casing strings according to GOST 632-80 have ellipse and difference. In this regard, if there is a connection between the scraper elements and the rigid surface of the hollow plunger, it is difficult to destroy the clay crust on the pipe wall along the major axis of the ellipse, i.e. when in contact with the pipe body along the minor axis of the ellipse, the scraper elements located along the major axis of the ellipse do not reach the pipe surface in this section, which reduces the efficiency of the cleaning process;

- the device is centered inside the pipe being cleaned due to the scraper elements, which can lead, as noted earlier, to uneven loading of each of them during rotation and axial movement;

- mechanical particles may enter between the mating surfaces of the hollow plunger and the cylindrical body, which may serve as an obstacle to the full return of the movable elements to the transport position.

The technical result that can be obtained by implementing the invention:

- regulation of the contact effect on the surface of the clay crust around the entire perimeter of the processed pipe;

- direct effect of a jet of working fluid on the treated surface covered with clay crust at the point of contact of the roller with it;

- actuating the device in a predetermined interval of the well with subsequent return to its original position;

- ensuring cleaning by a jet of working fluid of the working surface of the roller;

- balancing the torque on the housing due to the multidirectional longitudinal grooves on the outer surface of the scraper elements.

The technical result is achieved by the fact that the scraper for cleaning the inner surface of the pipes consists of a hollow body with connecting conical threads at the ends, scraper elements installed with the possibility of interaction with the inner surface of the pipes in the working position, and the hydraulic drive of the scraper elements.

The axial channel of the hollow body in the middle part is separated by a jumper with a cylindrical bore inside, hydraulically connected to the inlet and outlet channels with the axial channel of the hollow body.

The hydraulic actuator is made in the form of a spring-loaded step piston located in a cylindrical bore. A transverse groove is made in the body of the stepped piston from the outer side facing the well cavity, and the inner bore from the opposite side, separated by a blank partition. The transverse groove is equipped with a roller on the axis of rotation, having a notch on the outer surface. A perforated washer is installed in the inner bore, which forms an intermediate chamber with a blind partition, which is hydraulically connected by drainage holes made in the body of the step piston, with the cavity of the cylindrical bore and the cavity of the well. In addition, the intermediate chamber is hydraulically connected by a calibrated hole made in the body of the blind partition to the cavity of the transverse groove at the location of the roller.

Scraper elements are made in the form of rings freely placed on cylindrical grooves made on the outer surface of the hollow body above and below the location of the jumper. The restriction from the axial movement of the scraper elements is carried out due to the lock nuts mounted on the hollow body.

Scraper elements have notches made at an angle to the longitudinal axis of the hollow body and in different directions, i.e. right and left directions.

The design of the device for cleaning the inner surface of the pipes is shown in the drawings, where:

- in FIG. 1 - a General view of the device in the context, in the transport, initial position of the parts;

- in FIG. 2 is a General view of the device in the context when the opening of the working elements to contact with the inner surface of the pipe covered with clay peel;

- in FIG. 3 is a cross-sectional view of the device at the location of the hydraulic actuator.

The device consists of a hollow body 1 with a jumper 2 in the middle of the axial channel 3, in which a cylindrical bore 4 is made perpendicular to the axis of the hollow body 1, hydraulically connected by an inlet channel 5 with an axial channel 3 of the hollow body 1 above the jumper 2 and the outlet channel 6, s the axial channel 3 of the hollow body 1 under the jumper 2. On the outer surface of the hollow body 1 at the upper and lower ends, tapered threads 7 and 8 are made for communication with the pipe string.

Under the location of the tapered threads 7 and 8, cylindrical threads 9 and 10 are made, on which lock nuts 11 and 12 are fixed. Under the lock nuts 11 and 12, cylindrical grooves 13 and 14 are made on the body of the hollow body 1, on which freely, with the possibility of rotation, scraper elements 15 and 16 are installed in the form of rings.

The outer diameters of the scraper elements 15 and 16 are larger than the outer diameter of the lock nuts 11 and 12. A number of longitudinal grooves 17 are made on the outer surfaces of the scraper elements 15 and 16 (see FIG. 2) in different directions with an inclination to the axis of the hollow body 1.

A hydraulic drive is arranged in the cylindrical bore 4 of the hollow body 1, which is a step piston 18 with a blind partition 19 inside, dividing the internal channel of the step piston 18 into two parts, one of which is made in the form of a transverse groove 20, in which a roller is placed on the axis of rotation 21 22 with a notch on the outer surface.

On the opposite side, an internal bore 23 is made in the body of the stepped piston 18, in which a perforated washer 24 is placed, which acts as a filter, forming an intermediate chamber 25 with a blind partition 19 hydraulically connected to the annular chamber 26 under the stepped piston 18 through drainage holes 27.

The annular chamber 26, in turn, communicates with the cavity of the well through grooves 28 made in the body of the nut 29 mounted on a thread in the hollow body 1 and pressing the step piston 18 to the bottom 31 of the cylindrical bore 4 through the spring 30. At the end of the step piston 18, facing the bottom 31, a number of longitudinal grooves 32 are made for free flow of the working fluid from the inlet channel 5 into the cavity of the cylindrical bore 4 and then through the outlet channel 6 into the axial channel 3 of the hollow body 1 under the jumper 2.

To ensure the cleaning of the outer surface of the roller 22 from clay particles, a calibrated hole 33 is made in the blind partition 19.

Device operation

The conical thread 7 at the upper end of the hollow body 1, the device is connected to the pipe string tubing and is introduced into the well at a calculated depth. The wellhead is equipped with fittings to which the pump unit is connected. In the axial channel 3 of the hollow body 1 of the device, the fluid is supplied under pressure. Under the action of a differential pressure, the stepped piston 18 moves inside the cylindrical bore 4 in the direction to the inner surface of the processed pipe coated with clay cake, with the contact of the roller 22. In this case, the scraper elements 15 and 16 are pressed by their surface to the surface of the processed pipe from the opposite side. The device is placed inside with an offset from the axis of the well, i.e. with eccentricity.

The rotation of the tubing string and the hollow body 1 of the device is reported. In this case, the working fluid through the inlet channel 5 with a predetermined flow rate enters the cylindrical bore 4 and then through the perforations in the body of the perforated washer 24 it enters the intermediate chamber 25 and then through the drainage holes 27 in the body of the step piston 18 is fed into the annular chamber 26, hydraulically connected with a well cavity. Through the grooves 28 in the body of the nut 29, the working fluid acts on the surface of the roller 22 to remove adhering clay particles.

A part of the flow rate of the working fluid through the calibrated hole 33 in the body of the blind partition 19 is also supplied to the surface of the roller 22 with its cleaning when the fluid flows around it, thereby preventing the cavity of the transverse groove 20 in the body of the step piston 18 from clogging with clay particles. When the hollow body 1 rotates, the roller 22 rotates on the axis of rotation 21 and rolls around the inner surface of the pipe with the effect of notches between the longitudinal grooves 17 on the clay layer. At the same time, the scraper elements 15 and 16, rotating on cylindrical grooves 13 and 14 relative to the hollow body 1, are run on the inner surface of the pipe being cleaned with the protrusions between the longitudinal grooves 17 and its destruction exposed to the clay crust. By smoothly moving the device down together with the tubing string, the clay crust is sequentially destroyed to remove deposits of the inner surface of the pipe while maintaining torque transmission. The transmission of torque to the hollow body 1 can also be carried out by using a downhole screw motor (not shown in the drawing).

When the hollow body 1 rotates, the roller 22 moves along the perimeter of the pipe being cleaned with rotation around the axis of rotation 21 with pressing and interaction of the scraper elements 15 and 16 onto the clay cake layer when they are rolled around the inner surface of the pipe being cleaned.

The flow of the working fluid flowing through the grooves 28 in the body of the nut 29 is summed up with the flows flowing from the calibrated hole 33 in the body of the blind partition 19 and the flow through the discharge channel 6 into the axial channel 3 into the well cavity. The total flow of the working fluid clay particles are removed from the well through the annulus.

At the end of the process of removing clay peel from the inner surface of the pipe, the transmission of torque to the hollow body 1 of the device is stopped and the pressure of the working fluid is relieved. By the force of the pre-compressed spring 30, the stepped piston 18 returns into the cylindrical bore 4. The hollow body 1 with the roller 22 and scraper elements 15 and 16 is located axisymmetrically to the axis of the processed pipe. By pulling the tubing string, the device is pulled to the surface.

Claims (1)

A scraper for cleaning the inner surface of the pipes, consisting of a hollow body with connecting conical threads at the ends, scraper elements installed with the possibility of contact with the inner surface of the pipes in the working position, hydraulic scraper elements, characterized in that the axial channel of the hollow body is divided by a jumper in the middle part with a cylindrical bore inside, hydraulically connected inlet and outlet channels with the axial channel of the hollow body, the hydraulic actuator is made in the form of a spring-loaded mortar a piston in a cylindrical bore, in which a transverse groove and an internal bore are made, separated by a blind partition, the transverse groove provided with a roller on the axis of rotation with a notch on the outer surface, and a perforated washer installed in the inner bore, forming an intermediate chamber hydraulically connected with the blind partition drainage holes in the body of a stepped piston with a cavity of a cylindrical bore and a calibrated hole in the body of a blind partition with a cavity of the transverse groove in place azmescheniya roller, the scraper elements are designed as rings arranged loosely on a cylindrical groove formed on the outer surface of said hollow body above and below the location of the jumper, limited axial movement of lock nuts fastened to the hollow body.

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