RU2644959C1 - Device for restoration of defects of operating columns of oil and gas wells - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: device includes a patch in the form of a smooth metal tube having elastic sealing rings on the ends and expanding a mandrel made in the form of several rigidly fixed, after each other, on the common rod, a variety of truncated cones. The diameter of the base of each subsequent cone is greater than the previous one. The distance between neighbouring cones is changed by changing the spacer.

EFFECT: axial force is increased when the patch is expanded, and the reliability and efficiency of the device are increased.

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Description

FIELD OF TECHNOLOGY

The invention relates to the oil and gas industry, mainly to devices for sealing casing strings and shutting down formations.

BACKGROUND

Known three-stage cutting head according to patent RU 2154148 C2, IPC ЕВВ 29/10, publ. 08/10/2000, including the main cone-punch, floating sectors located on the self-sealing cuff, as well as spring-loaded conical dies installed between the cone-punch and floating sectors with the possibility of axial and peripheral movement. When the mandrel head enters the patch, its preliminary expansion is carried out by a punch-cone, then the intermediate one is made by cone dies due to their axial and peripheral displacement, and the final one is made by floating sectors under hydraulic pressure in the system.

The main disadvantage of the described construction is its initial focus on working with corrugated plasters, which sharply limits the scope of its application. In addition, corrugated plasters cannot provide complete sealing of defective sections of the production string, since for large reservoir pressure of the fluid in the well, sometimes reaching 100 or more atmospheres, it is necessary to press the metal patch to the wall of the column by means of an elastic sealing ring. Only in this case is a guaranteed cut-off of the defective section of the column achieved. However, a large number of mating moving parts, as well as the presence of a cuff involved in the force acting on the patch, reduces the reliability of the device as a whole.

A device for repairing a casing string is disclosed in A.S. USSR № SU 1086118 A, IPC Е21В 29/00, publ. 04/15/1984, Bull. No. 14. The known device comprises a smooth metal pipe of a certain external diameter having internal wall thickenings at the ends, as well as a rod located inside the pipe with a pair of expanding mandrels sequentially fixed at the ends in the form of truncated cones. The disadvantage of this device is the increased axial force required to pull along the pipe (in fact - the patch) a pair of expanding cones, in the case when two narrowed ends of the patch expand simultaneously, which leads to additional loads on the lift, and as a result, reduces the reliability of the device as a whole . In addition, pressing the patch against the wall of the column without a sealing elastic ring does not provide complete sealing. In addition, technologically, a pipe (patch) with a thickening of the wall at the ends inward in comparison with a conventional smooth-walled pipe as a patch is more difficult and more expensive to manufacture.

The closest analogue of the claimed invention (prototype) is a device for sealing a casing string, disclosed in the description of patent RU No. 2236550 C1, class. ЕВВ 29/10, publ. 09/20/2004.

The device known from the closest analogue comprises a patch in the form of a smooth cylindrical metal pipe, a hydraulic landing tool, which is a three-cylinder hydrostatic drive, and an expanding mandrel having the shape of a truncated cone; at the ends of the patch in the annular cylindrical grooves made in it, elastic seals are placed, and the hydraulic landing tool is equipped with a hydraulic anchor.

The disadvantages of the known closest analogue of the device include a large number of complex mating precision parts of hydraulic cylinders, leading to higher prices and lower reliability of the entire structure, as well as the limited piston stroke of the hydraulic cylinders, which entails the inability to seal significant damage over the length of the casing or several sections of leaks located at a considerable distance from each other.

SUMMARY OF THE INVENTION

The task of the invention is to develop a device for the restoration of defective sections of production casing of oil and gas wells, as well as improving the reliability of the device as a whole.

The technical result of the invention is to increase the reliability and efficiency of the device by reducing the force required to pull the expanding mandrel inside the patch. The specified technical result is achieved due to the fact that the device for repairing defective sections of production casing of oil and gas wells contains a smooth metal pipe with external elastic sealing rings at the ends, inside of which there is an expanding mandrel, including a rod with several differently sized truncated cones rigidly fixed on it, the latter are located immediately after each other in ascending order of the diameters of the bases, and their vertices are directed along the movement of the rod. At the same time, the distance between the subsequent and previous cones can be changed, for example, using a replaceable spacer sleeve. In addition, the number of truncated cones in the expanding mandrel is not more than three.

Reducing the pulling force of the expanding mandrel is based on the effect of combining non-contact deformation zones during cold expansion of pipes. This effect consists in the fact that during cold deformation of the pipe by the punch in the form of a series of truncated cones, the axial pulling force of the punch decreases by 1.5 ... 2 (!) Times in comparison with the expansion of the pipe by one cone to the same size, ceteris paribus due to the formation waves of free deformation between adjacent cones (A.M. Rosenberg, O.A. Rosenberg `` Mechanics of plastic deformation in the processes of cutting and deforming drawing '' - Kiev: Naukova Dumka, 1990, pp. 154-155; pp. 158 -159).

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clear from the description, which is not restrictive and given with reference to the accompanying drawings, which depict:

FIG. 1 is a general view of a device for repairing defective sections of production casing strings of oil and gas wells.

1 - production casing; 2 - patch; 3 - elastic sealing ring; 4 - thrust; 5 - expanding mandrel.

FIG. 2 is a view A in FIG. 1 in scale, a longitudinal section of the device.

6 - the first cone; 7 - subsequent cone; 8 - replaceable spacer sleeve; 9 - rod expanding mandrel; 10 - threaded sleeve; 11 - stopper.

DETAILED DESCRIPTION OF THE INVENTION

A device for repairing defective sections of oil and gas production casing strings contains a patch (2) in the form of a thin-walled smooth pipe with external elastic sealing rings (3) at the ends and an expanding mandrel (5) located inside the patch (2) and consisting of a rod (9) with the first (6) and subsequent (7) truncated cones rigidly fixed on it, located immediately after each other, and the distance '' L '' between them can be changed using a removable spacer sleeve (8). To fix the cones (6) and (7), a threaded sleeve (10) with a stop (11) is used. The rod (9) is connected with the rig of the drilling rig (not shown) by means of a rod (4), for example, a string of tubing (tubing).

A device for recovering defective sections of production casing oil and gas wells works as follows.

The device is lowered into the well on a thrust (4), for example, on a tubing string, until the leakage zone of the production string (1) is between the elastic sealing rings (3) of the patch (2). Moreover, the latter, depending on the nature and location of defects in the production string (1), can be extended by composing from separate sections, for example, using low-profile threaded connections. After that, one of the known methods is the anchoring of the patch (2) in the production casing (1). Using a hoist (not shown), the rod (4) begins to move upward, the first cone (6) of the expanding mandrel (5) enters the patch (2) and pre-expands it. Then the expansion of the patch (2) continues the subsequent cone (7), having a larger base diameter than the previous first cone (6). After that, the main process of expanding the patch (2) by both cones at the same time begins, while the working force of pulling the expanding mandrel (5), consisting of several cones located directly after each other, inside the patch (2) is much less (1.5 ... 2 times) in comparison with the same extension with just one cone. Depending on the radial dimensions, wall thickness and characteristics of the patch material (2), it is possible to achieve the maximum reduction of the working expansion force by changing the distance '' L '' between the cones using interchangeable spacer sleeves (8) or using three similar cones as part of the expanding mandrel. A further increase in the number of cones does not lead to a significant decrease in the axial force and even slightly increases it due to an increase in the friction forces of the cones against the walls of the patch (2). The process of expanding the patch (2) (or its sectional assembly) lasts until the cones (6) and (7) have passed its entire length. The patch (2) is expanded and tightly pressed against the walls of the production string (1), while the elastic sealing rings (3) cut off the leakage zone from the well cavity. After that, the expanding mandrel (5) is lifted from the well.

Thus, the present invention allows to obtain a device for the repair of defective (including extended) sections of production casing of oil and gas wells, which increases the reliability and efficiency. The device has a fairly simple design, and the technology of working with it is easily feasible.

The invention has been disclosed above with reference to a specific embodiment. Other specialists may be obvious to other embodiments of the invention, without changing its essence, as it is disclosed in the present description. Accordingly, the invention should be considered limited in scope only by the following claims.

Claims (1)

A device for repairing defective sections of oil and gas production casing strings, comprising a patch in the form of a smooth-walled metal pipe having elastic sealing rings on the ends and an expanding mandrel made in the form of coaxially and sequentially arranged punches in the form of truncated cones of no more than three, with a maximum diameter each subsequent one is larger than the previous one, characterized in that in order to reduce the axial force during the expansion of the patch, the distance between osednimi cones is changed with a removable spacer.

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