SU1596078A1 - Device for cleaning inner surface of casings - Google Patents

Abstract

The invention relates to the mining industry and is intended for complete cleaning of the columns in the installation intervals of steel patches, packers, formation testers and other well equipment that require a tight fit to the inner wall of the column. The goal is to increase the reliability of the device in operation in conditions of large pressure drops in the well. For this purpose, a sleeve 8 is installed between the body (K) 1 of the device and the elastic balloon (EB) 7 of rubber-fabric material. The grooves and windows are made on the outer surface of the sleeve 8. The windows accommodate lamellar springs (PP) 9 with the ability to interact with EB 7 and are rigidly connected with retractable cutting plates 6 placed in the grooves of K 1. The ends of PP 9 are located in the slots of the sleeve 8 constantly abut on position relative to the sleeve 8 during operation. Under the influence of EB 7, the central part of PP 9 straightens out and overlaps the step between K 1 and extended plate 6 in longitudinal section. As a result, in this section the bend and local stretching of the elastic material EB 7 under pressure are completely excluded. 1 hp f-ly, 4 ill.

Description

The invention relates to the mining industry and is used to clean the inner surface of the casing from corrosion products, crusts of cement and clay mortars, burrs, traces of perforation and other layers. The device is intended for complete cleaning of the columns in the installation intervals of steel plasters, packers, formation testers and other well equipment that require tight adhesion to the inner wall of the column.

A device for cleaning the inner surface of the casing, having a transport and operating position. The device is transferred to the working position by creating a pressure differential after

descent into the well to the cleaning interval. The device consists of sliding dies installed in the housing slots and armed with wire brushes. In the transport position, the die is held by a return spring fixed on the outer surface of the housing with the help of linings limiting the extension of the dies. To seal the device, on each plate there is a seal placed in the groove around the perimeter of its side surface.

The drawback of the device is the low reliability of sealing due to the complex shape and large total length of tight gaps. Such a design is unsuitable for working with large

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pressure drops and forces on cutting dies for cleaning solid casing layers. In addition, when meeting with an obstacle, the plate may be tilted and jammed in the housing.

Placing the return springs, restriction plates and fixing bolts on the outer surface of the housing in the event of breakage can cause tool seizure and accidents associated with leaving the metal in the well.

Closer to the proposed technical solution is a device for cleaning the inner surface of the casing, comprising a housing with slots for retractable cutting dies, an elastic cylinder and a sleeve.

The device has an elastic stretching balloon disposed in the housing. Having expanded under the action of pressure drop, the cylinder directly acts on the rotary segments (dies), pushing them out of the housing grooves. In the housing, the pivot segments are mounted on the axles. To fasten the ends of the container, a sleeve with channels for the passage of fluid is placed inside it.

The reasons for not using this casing cleaning device are as follows.

To effectively clean siege columns from dense layers, it is necessary to press the plate with a force of several tons, which corresponds to the work of the scraper with a pressure drop of 2 to 6 MPa.

When the plate is extended into its working position, the cylinder wall expands. Under the action of pressure drop, a sharp bend and additional local stretching of the elastic material of the balloon on the ledges between the housing and the extended die occur, especially in the longitudinal section of the scraper. In addition, with a large pressure drop, the material of the balloon is pushed (flowed) into the gaps between the casing and the movable plate, followed by pinching (biting). Repeated stretching on the ledges and pinching of the elastic material would result in 1, thromium destruction of the balloon.

During casing overhauls, the scraper usually descends on pump-compressor pipes, which can only be cleaned by reciprocating movements without rotation. The scraper with swiveling dies (segments) is unsuitable for operation in such conditions, since the dies have a small almost linear contact with the perimeter of the surface being cleaned.

The device does not have a mechanism for the return of segments and the transport position after the release of pressure.

The purpose of the invention is to increase the reliability of the device in operation in conditions of large pressure drops in the well - achieved by the device comprising a housing with slots for retractable cutting sleeves, an elastic balloon and a sleeve,

0 is provided with plate springs rigidly connected to the dies, and a sleeve is installed between the housing and the elastic balloon and has grooves on the outer surface and windows in which the plate springs are interoperable with the elastic balloon, with the ends of the plate springs located in the grooves on the outer the surface of the sleeve until it stops in the case.

0 In addition, the elastic balloon is made of rubber-fabric material.

Figure 1 shows the proposed device, a General view; figure 2 - section aa in figure 1; on fig.Z - section bb in figure 1; on

5 of FIG. 4 — node I in FIG. 3 (range of variation

the position of the leaf spring in the window

bushings depending on wall thickness

casing during operation of the device).

The device consists of a housing 1 with connecting connectors 2 and 3 for connecting to the column pipe 4 and chisels 5. Sliding cutting dies 6 are located in the housing grooves. A sleeve is installed between the housing 1 and the elastic cylinder 7

5 8, having longitudinal windows in places corresponding to the cutting dies 6. Each window is covered with a leaf spring 9. The flat ends of the spring are placed in grooves on the outer surface

0 sleeves 8 and abut against housing 1. A central concave part of the spring penetrates through the window into the inner part of sleeve 8. Each spring is connected to the die 6 with a screw 10. The ends of the elastic balloon are securely

5 are fixed in the sleeve 8 with cones 11 by means of push nuts 12, ensuring tightness at working pressure. The elastic balloon is made of rubber-fabric material, in particular in the form of a pressure hose. The diameter of the cylinder is chosen such that the length of its perimeter cross section along the external surface, in the absence of internal pressure, is equal to the length of the perimeter of the internal cross section of the scraper along the sleeve and

5 leaf springs corresponding to the extended position of the plate.

To completely overlap the surface being cleaned during the reciprocating movement of the scraper, retractable dies are placed in two rows, three in each, with

offset by 60 °. Dies 6 and body 1 are provided with corresponding shoulders 13 and 14 to limit the advancement of the dunnies in the open hole.

The device works as follows.

In the transport position, the cutting dies 6 are drawn into the grooves of the housing 1 by plate springs 9, which run down the ends and into the body, act as the central part through the windows into the internal cavity of the sleeve 8, creating deflections (longitudinal folds) on an elastic cylinder 7

In the cleaning interval, circulation through the lowered column is restored and an overpressure of 3-6 MPa is created in the cavity of the bladder 7. I will act through the spring 9. The elastic balloon will push the die 6, pressing it with an appropriate force to the surface being cleaned. In this case, the central part of the spring, straightening out, enters the window of the sleeve 8. At the same time, the longitudinal folds of the elastic balloon are straightened and it fits tightly against the leaf spring. The casing can be cleaned either by a reciprocating movement of the scraper or by rotating it down smoothly.

The design of the device has the following significant advantages.

The flat ends of the leaf spring 9 constantly abut against the body of the scraper and practically do not change their position relative to the sleeve 8 during operation. The central part of the spring, placed in the longitudinal window of the sleeve 8., is straightened out by the action of the cylinder and overlaps the step between the housing and the extended die in the longitudinal section of the scraper. As a result, in this section the bend and local stretching of the elastic material of the balloon under pressure are completely eliminated.

When the plate is extended out of the housing groove before contact with the surface being cleaned, the cylinder is practically not loaded, since it overcomes the resistance of only the spring being rectified. In the working position when cleaning in the cross section of the scraper between the sleeve 8 and the spring 9, a slight step may be caused by different wall thicknesses of the casing

and cleaning layer. Fig. 4 shows the limits of variation of the ledge depending on the difference in the thickness of the pipes produced. The largest step h for production columns is ± 2.75 mm.

Under the action of overpressure, the longitudinal folds of the balloon are expanded, and the fit of the ledges takes place practically without stretching the elastic material.

In the device, the balloon operates without stretching due to straightening of the longitudinal folds.

Reinforcing the fabric several times increases the strength of the rubber walls

cylinder, warning of leakage and pinching of elastic material in the gaps between the sleeve 8 and the leaf spring 9 in the entire range of operating pressures. Each die has an autonomous floating placement in the scraper nest. When it encounters an obstacle on the wall of the casing (metal inflows, etc.,), the die freely extends into the body without creating the danger of tool seizure.

Claims (2)

1. A device for cleaning the inner surface of casing strings, comprising a housing with slots for retractable cutting dies, an elastic cylinder and a sleeve, which is equipped with a means for increasing its reliability in operation under conditions of large pressure drops in the well. plate springs rigidly connected to the dies, and the sleeve is installed between the housing and the elastic balloon and has grooves on the external surface and windows in which the leaf springs are placed with the possibility of interaction with the elastic balloon. moreover, the ends of the plate springs are located in grooves on the outer surface of the sleeve until it stops in the housing. 2. The device pop. 1. distinguishing - with the fact that the elastic cylinder is made of rubber fabric material. /four one .one /four Yu FIG. 2 Bj 3 1 pobeonuto Fy