RU2738716C1 - Method for bottom-hole anode earthing - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to electrochemical protection of underground structures against ground corrosion and can be used in oil and gas industry, as well as in municipal services when performing anode earthing of deep-lying in systems of electrochemical protection of main pipelines and other underground metal structures from corrosion. Method includes drilling of well, installation in pipe of current conducting composite pipes, placement in tubes of protective electrodes with output of connecting cable and filling of tube with current-conducting gel, wherein before drilling well vertical electrical probing of installation place, according to the results, anode grounding section is divided into intervals characterized by different specific electric resistance of soil, pipes are selected from current-conducting composite with specific electric resistance corresponding to each interval, and installed in well in appropriate interval so that pipes with lower electric resistance after installation were in soil with high electric resistance.

EFFECT: technical result consists in simplification of installation of bottom anode earthing, maintenance of its repairability, as well as higher efficiency of its operation due to the installation of electrodes in current conducting pipes with different specific electric resistance, which is selected taking into account the electrical resistance of soil layers.

1 cl, 1 dwg, 1 ex

Description

The invention relates to the field of electrochemical protection of underground structures from soil corrosion and can be used in the oil and gas industry, as well as in the utilities when performing anodic grounding of deep burial in the systems of electrochemical protection of main pipelines and other underground metal structures from corrosion.

It is known deep grounding, containing a garland of electrode blocks connected in series and connected to the main cable, each of which is located in a metal case filled with an activator, through which the main cable and a gas outlet pipe pass (SU 399949, IPC H01R 4/66, publ. 03.10 .73).

The disadvantage of the known devices is the complexity of transportation of grounding and its installation on the route, as well as the lack of maintainability of this design.

It is known deep grounding, consisting of an elastomeric extended electrode - an anode body of a cable-type ground electrode, and a cable for connecting to the electrode, while the space between the electrode and the borehole walls is filled with coke breeze (RF patent 2225420, publ. 03.10.2004).

The disadvantage of this device is the complexity of its installation on the route, possible uneven backfilling with a coke ground electrode, with the formation of voids, as well as the non-maintainability of this design.

Closest to the claimed invention is a method of performing anode grounding, including determining the level of groundwater and the depth of soil freezing along an underground structure, drilling below these levels of the well along the protected structure with access to the day surface of both ends of the well, installing conductive composite pipes in the well, placing in the pipes of protective electrodes with the output of connecting cables from both ends of the well, filling the well with electrically conductive material, while along the protected structure in the area where the anode grounding is performed, the transient resistance of the insulating coating of the structure is measured step by step, the area where the anode grounding is performed is divided into intervals characterized by different resistance of the coating, choose the resistance of conductive composite pipes, corresponding to each interval, install conductive composite pipes in such a way that, after placing them in the well, pipes with a certain th resistance were located in the corresponding interval (RF patent 2695101, publ. 02.07.2018).

The disadvantage of this method is that it is not directly adapted to the organization of deep anode grounding, and also when it is not taken into account the specific electrical resistance of the soil in which it is laid.

The objective of the invention is to develop a new maintainable method for performing deep anode grounding, taking into account the specific electrical resistance of the soil layers in which it is installed.

The technical result consists in simplifying the process of installing deep anode grounding, ensuring its maintainability, as well as increasing the efficiency of its operation by laying electrodes in conductive pipes with different electrical resistivity, selected taking into account the electrical resistivity of soil layers. The result of the invention is also a reduction in the cost of grounding installation.

The problem is solved by the fact that in the method of performing deep anode grounding, including drilling a well, installing conductive composite pipes in the well, placing protective electrodes in the pipes with a connecting cable outlet and filling the pipe with conductive gel, while before drilling the well, vertical electrical sounding of the site is carried out the installation, according to the results of which the section for performing anode grounding is divided into intervals characterized by different specific electrical resistance of the soil, pipes are selected from a conductive composite with a specific electrical resistance corresponding to each interval and installed in the well in the corresponding interval so that pipes with a lower electrical resistance after installation, they were in soil with high electrical resistance.

The method is illustrated in Fig., Which shows:

1 - well;

2 - soil layers with different electrical resistivity;

3 - soil surface;

4 - conductive composite pipes;

5 - protective electrode;

6 - conductive gel;

7 - cables;

8 - control and measuring point;

9 - conductor.

The method for performing deep anode grounding is as follows.

A site is selected for placing the deep anode grounding. Vertical electrical sounding of the installation site of the deep anode grounding is performed and the electrical resistivity of the soil layers 2 through which it will pass during its installation is determined. Well 1 is drilled by rotary drilling.

The section for performing deep anode grounding is divided into intervals characterized by the specific electrical resistance of the soil. Select the pipe resistance from the conductive composite corresponding to each interval.

In the drilled well, pipes made of a conductive composite 4 are installed so that after they are placed in the well, pipes with a certain resistance are located in the appropriate interval, into which protective electrodes 5 are lowered 5. Conductive gel 6 is pumped into the pipes.

Protective electrodes 5 are connected with cables 7 to the electrochemical protection system through the control and measuring point 8.

Installation of conductive pipes with different electrical resistance, depending on the specific electrical resistance of the soil layers, leads to a smooth spreading of the protective current along the entire length of the anode and, accordingly, leads to an increase in the resource of the anode grounding.

Example.

For the implementation of electrochemical corrosion protection of the main gas pipeline section, a cathodic protection station with a capacity of 1 kW was designed, operating with a fifty-meter deep anode grounding. The site for the installation of deep anode grounding was selected. At this site, measurements of the electrical resistivity of soil layers to a depth of 50 meters were carried out using the method of vertical electrical sounding. According to the results of vertical electrical sounding, it was found that there are three layers of soil with different indices of specific electrical resistance (45 Ohm⋅m, 560 Ohm⋅m, 38 Ohm⋅m).

Pipes made of a conductive composite are selected with a specific electrical resistance of a conductive composite equal to 10,000 Ohm⋅m, while for installation in soil with a specific electrical resistance of 560 Ohm⋅m, pipes made of a conductive composite with a specific electrical resistance of a conductive composite are selected equal to 10 Ohm⋅m, which leads to a smoother spreading of the protective current from the entire surface of the protective electrode.

Using equipment for rotary drilling (not shown in the figure), a well 1 with a diameter of 168 mm is drilled to a depth of 50 meters. Pipes 4 with an outer diameter of 120 mm from a conductive composite material are pulled into the borehole 1, collecting the pipe string so that the pipes with lower resistance, after installation, are in the soil with high electrical resistivity.

A protective electrode (extended flexible anode) 7 of type PVEK.AZP according to TU 3435-005-97598003-2011 with a length of 1000 m with a cable 8 extending to the day surface 3 is lowered into pipes 6 and connected to the cathodic protection station (in Fig. 3 not shown) via gage 8.

Electrically conductive gel is pumped into the pipe to create a guaranteed electrical contact between the protective electrode and conductive composite pipes. Also, the presence of the gel helps to increase the maintainability of this design.

Claims (1)

A method for performing anode grounding, including drilling a well, installing conductive composite pipes in the well, placing protective electrodes in the pipes with a connecting cable outlet, filling the pipe with conductive gel, characterized in that before drilling the well, vertical electrical sounding of the installation site is carried out, the results of which are broken the section for performing anode grounding at intervals characterized by different electrical resistivity of the soil, pipes are selected from a conductive composite with a specific electrical resistance corresponding to each interval, and they are installed in the well in the corresponding interval so that pipes with a lower electrical resistance are in the ground after installation with high electrical resistance.

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