SU810936A1 - Device for repairing the casing of a borehole - Google Patents

Description

one

The invention relates to the field of the oil and gas industry and is intended for the repair of boreholes in order to restore the tightness of the casing.

A device for repairing a leaky casing is known, comprising a barrel, an element for covering the damage filled with a liquid, a source of high pressure gas {.

The disadvantage of this device is the poor quality of the repair. This is explained by the fact that when a plaster is installed in a casing pipe, the device can be displaced outside the repaired area in the presence of a pressure drop in the well, as well as when high pressure gas flows out from the source, due to the axial forces that occur.

The closest solution known is a borehole casing repair device comprising a barrel, a fracture block filled with fluid, a high pressure gas source and a packer having a housing with a sealing member 2 mounted on it.

The disadvantage of this device is the low reliability of the device due to the absence of flow channels in the barrel and its body.

The aim of the invention is to increase the reliability of the device.

This goal is achieved by the fact that the barrel and body are spring-loaded relative to each other and are made with flow channels.

The drawing shows a diagram of a device for repairing a casing string of a borehole.

The device comprises a barrel 1, on which between the supports 2 and 3 is fixed an element for covering the damage 4, filled with liquid 5. Inside the element 4 on the barrel 1 there is a charge of explosive 6 with an electric detonator 7. On the barrel 1 there is a coaxially movable packer having a body 8 with the sealing element 9 and the source of high pressure gas 10 and held in the initial position relative to the barrel 1 by the spring 11. The source of high pressure gas 10 is a powder brush with a filament embedded in it (in the drawing is not shown), and is located on the case of the packer 8. In the case of the packer 8 and the barrel 1 there are channels 12 for the flow of fluid during the descent of the device into the well. A guide bushing 13 and a centralizer 14 with a pressure sensor 15 are located at the ends of the barrel 1. The pressure sensor is designed to detect the surface magnitude and nature of the pressure change in the pressure vessel during repair. The device is lowered into the repair section of the casing string 16 on the electric cable 17.

Device works as follows.

After it is lowered into the well, the signal supplied from the surface of the incandescent filament ignites the gunpowder used as a source of high pressure gas 10. Gases released during the combustion of gunpowder displace the liquid from the repaired section of the casing column. gas cavity, the pressure in which exceeds the hydrostatic. When a high pressure gas outflows from the source, under the action of the axial forces arising from this, the source together with the packer moves along the barrel 1 down to the stop. In doing so, the channels 12 and the cross section of the casing string overlap. The further movement of the entire device is prevented by the fluid in the column under the packer. The overpressure in the gas cavity that forms above the packer, acting on it as a piston, compensates for the axial forces arising during the movement of gas-liquid flow in the pipes, which also prevents the device from displacing from the repaired section of the casing string 16. As the gas cavity expands, the pressure it becomes equal and less hydrostatic. At this moment, a signal is supplied from the surface to the electric detonator 7, with which the explosive charge 6 is exploded. The element for covering the damage under the action of the resulting shock waves and detonation products expands and presses tightly against the walls of the casing.

there are holes in it. After installing the bridging element, the barrel with the packer is removed to the surface.

For repairing a casing with a diameter of 146 mm, a device was used in which the element to bridge the damage 4 was a cylindrical tube with a diameter of 114 mm, with a wall thickness of 5 mm, and a length of 4 m. The charge of explosive 6 consisted of pieces of a detonating cylinder LH- AT. An explosive cartridge of the PVGU-5 was used as a detonator. A powder block with a diameter of 100 mm with a central channel of 40 mm and a weight of 15 kgf was used as a source of high-pressure gas. A light-deforming sheath assembled from mutually overlapping metal plates was used as a packer. To measure the magnitude and nature of the pressure change in the well, a pressure sensor 15, type DM, was used. The device will allow the installation of the patch in the casing string strictly in a given interval of well depth, which improves the quality of repair.

Claims (2)

Invention Formula A casing repair device for a borehole, comprising a barrel, a fault covering element filled with fluid, a high pressure gas source and a packer having a housing with a sealing element mounted on it, characterized in that, in order to increase the reliability of the device, the barrel and the housing are spring-loaded relative to each other and made with flow channels. Sources of information taken into account in the examination 1. US patent No. 3175618, cl. 166-63, publ. 1961. 2. USSR author's certificate in application number 2654241/03, cl. E 21B 29/02, 1978. //