RU2536067C2 - Metal in-well pipe section destruction and device to this end - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: electrochemical cell is created with anode making the section of pipe to be destructed and cathode making the tubular structure located opposite the destruction point. Electrolyte is fed to pipe wall and forced continuously from the surface over flow string via active zone, that is, annulus between section to be destructed and tubular cathode. Voltage is fed to cause electrochemical anode dissolution of pipe section. This process is realised with the help of two or more electrochemical cells. One or more cells are used for destruction of pipe section or sections. Another part is used to generate supply voltage for induction of electric current and composed of galvanic elements arranged as close as possible to the zone of galvanic cell soluble section.

EFFECT: reduced power losses, simplified production and operation.

2 cl, 3 dwg

Description

The invention relates to the oil and gas industry and can be used to destroy a section of a metal pipe in a well during its construction and repair work requiring partial removal of pipe sections.

Known [1, 2, 3] are methods of destroying a portion of a metal pipe in a well by creating an electrochemical cell to carry out the process of electrochemical anodic dissolution of a portion of the pipe.

Patent for invention 2227201 describes a method for destroying a pipe section in a well, comprising supplying an electrolyte pipe to a wall to be destroyed and an electric current device through a cable to create an electrochemical anodic dissolution of the pipe section, the electrolyte being continuously pumped from the surface through a tubing string pipes through the annular space between the housing and the tubular casing and further into the electrochemical cell - the active zone, while the process parameters are supported in following limits:

the electrolyte temperature is from 0 to + 200 ° C, the electrolyte pressure is from 0.1 to 40 MPa, while using a pulsed electric current at a voltage of from 0.1 to 1000 V, and the electrolyte pumping is stopped when the termination of the flow of electric current is detected, which stops automatically after complete destruction of the pipe section.

The disadvantages of this method include the large loss of electricity in the cable, the complexity of manufacture and high labor costs.

In the patent for invention 2370625, a method for destroying a pipe section in a well is provided, according to which a device comprising an electrochemical cell with a wall of a pipe to be destroyed is lowered into a hole to a depth of a metal pipe to be destroyed, and an annular gap between the destroyed metal pipe section being an anode and the device on which the cathode is located, an electrolyte is supplied. A constant or pulsed modulated electric current is supplied to the anode and cathode with a frequency of 10-100 kilohertz and electrolysis is carried out until the pipe section is completely dissolved. To reduce losses in the supply cable, DC-DC converters (high-voltage direct current to low voltage converter) are used. To increase the rate (dissolution) of the destruction of a section of a metal pipe, the electric current of the electrochemical cell is periodically interrupted. To maintain (efficiency) the speed of the process, the acid pH of the electrolyte is maintained in the range from 0 to 8, and the voltage in the electrochemical cell is in the range from 1 to 4 V. When the pipe section corresponding to the cathode length is completely destroyed, the flow of electric current automatically stops, which is recorded by the wellhead device and then stop the flow of electrolyte into the well.

The disadvantages of this method include the presence of a cable for supplying electricity to the working area, large losses of electricity in the cable, temperature limiting the functioning of electronic equipment, the complexity of manufacture and operation, and large labor costs.

Utility Model Patent 77633 shows a device for destroying a pipe section in a well, consisting of a tubular structure, constituting an electrochemical cell with a wall of a pipe to be destroyed, to which voltage is supplied from a DC-DC converter (high-voltage direct current to low voltage converter), and the active zone of the electrochemical cell serves electrolyte.

The disadvantages of the device in question include the presence of an electric power supply cable to the working area, the inability to work at temperatures above 150 ° C, and the complexity of manufacturing and operation.

The problem solved by the invention is that to create an electric current in the electrochemical cell during the destruction of a section of a metal pipe in the well, galvanic cells located in the cell operating area are used, which eliminates the need for an electric cable and an electronic converter. In this case, the electrolyte is supplied from the surface along the tubing string, while the process parameters are maintained within the following limits:

- temperature 20-250 ° C;

- electrolyte pressure - 2-45 MPa.

The essence of the solution of the problem (the destruction of the section of the metal pipe in the well) is carried out by creating an electrochemical cell, the anode of which is the section of the pipe to be destroyed, and the cathode is the tubular structure installed opposite the fracture site. To this end, electrolyte is supplied to the wall of the pipe to be destroyed from the surface along the tubing string. Passing through the active zone of the electrochemical cell - the annular space between the destructible section of the metal pipe and the tubular cathode, while applying electrical voltage to the electrodes of the electrochemical cell, the process of electrochemical anodic dissolution of the pipe section occurs. The process is carried out using two or more electrochemical cells, and some of them, one or more, are used to destroy a section or sections of the pipe, and the other part, one or more, is used as galvanic cells to obtain an electrical supply voltage. The galvanic cells that create the necessary electric current are as close as possible to the area of the dissolving area, which reduces losses in the connecting wires. A galvanic cell is formed by a pair of metals, for example aluminum - copper, and an electrolyte flowing through them, for example, an aqueous solution of NaCl.

The invention is illustrated by drawings (figure 1, 2, 3)

The device for destroying a section of a metal pipe in a well (Fig. 1) consists of a destructible pipe 1, which is an anode, and a tubular structure 4, which is a cathode, which make up the electrochemical cell, through which the electrolyte supplied through the tubing 2 flows. Next to the electrochemical cell there are galvanic cells 3. One of these cells is shown in FIG. 2 and consists of a casing 5, two active metal elements 6 and 7, an insulator 8 and a leaking electrolyte 9.

The galvanic cells are interconnected, as shown in figure 3. In the galvanic cells 10, the connection occurs with the help of special inserts 11, allowing to connect the cathode of the first galvanic cell with the anode of the second galvanic cell.

The operation of the device is as follows. The electrolyte is pumped through the tubing through galvanic cells to the active zone of the electrochemical cell, where the metal pipe dissolves. The galvanic cells generate voltage and create enough current for the operation of the electrochemical cell.

The present invention involves solving the problem of destroying a section of a metal pipe in a well without supplying cable electricity to an electrochemical cell.

Information sources

1. IPC E21B 29/02 RU 2227201 C2 METHOD OF DESTRUCTION OF A PART OF A PIPE IN A WELL AND A DEVICE FOR ITS IMPLEMENTATION Published on 04/20/2004.

2. IPC E21B 29/02 RU 2370625 C1 METHOD OF DESTRUCTION OF A PART OF A PIPE IN A WELL (OPTIONS) Published on October 20, 2008.

3. IPC E21B 29/02 RU 77633 U1 DEVICE FOR ELECTROCHEMICAL DESTRUCTION OF A PIPE PART IN A WELL Published on 10/27/2008.

Claims (2)

1. A method of destroying a portion of a metal pipe in a well by creating an electrochemical cell, the anode of which is a portion of the tube being destroyed, and the cathode is a tubular structure opposite the fracture site, by supplying electrolyte to the wall of the pipe to be destroyed by continuously pumping it from the surface along the pump compressor pipes through the active zone of the electrochemical cell - the annular space between the destroyed part of the metal pipe and the tubular cathode, and the voltage to create a process of electrochemical anodic dissolution of a pipe section, characterized in that the process is carried out using two or more electrochemical cells, some of them, one or more, are used to destroy the section or sections of the pipe, and the other part of them, one or more , used to obtain an electrical supply voltage to create an electric current in the form as close as possible to the area of the soluble area of the galvanic cells formed by a pair of metals, for example aluminum - copper, and the electrolyte flowing through them, for example an aqueous solution of NaCl. 2. A device for destroying a pipe section in a well according to method 1, consisting of two or more electrochemical cells, characterized in that some of them, one or more, carry out the process of electrochemical anode destruction of the pipe section when the electrolyte is supplied, and the other part is one or several - are used as galvanic cells to create an electric current in the electrochemical cell of the destruction of the pipe section.

Images