A special equipment for cathodic protection construction of oil and gas well casing outer wall

Abstract

The application relates to the technical field of oil and gas well downhole casing corrosion prevention, and discloses a special equipment for oil and gas well casing outer wall cathode protection construction, which comprises a working module, and the working module comprises a drilling module and a drill body control structure which are connected with each other. The application solves the technical problems that the prior art cannot achieve the following effects: the oil and gas well casing can be accurately and controllably drilled, the drilling can meet the needs of installing anodes and related components and the needs of accurate repair afterwards, the anodes and related components can be accurately installed to the drilling positions, and the drilling can be accurately repaired and the corrosion prevention effect can be achieved.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well casing corrosion protection technology, specifically a special equipment for cathodic protection construction of the outer wall of oil and gas well casing. Background Technology

[0002] Oil and gas well casing outer wall protection generally relies on anti-corrosion coatings and cement layers. However, anti-corrosion coatings are easily damaged during oil and gas well casing construction, and cement layers are prone to cracking due to geological factors, allowing corrosive media to penetrate. Both of these protective layers can lead to severe corrosion of the oil and gas well casing outer wall. To extend the life of oil and gas wells, cathodic protection of the casing outer wall is necessary. Common cathodic protection methods for oil and gas well casing outer walls include the following:

[0003] I. Sacrificial Anode Protection Method. This method requires installing sacrificial anode blocks on the outer wall of the oil and gas well casing and placing them downhole together with the casing to ensure uniform distribution of the electric field lines. Since sacrificial anodes are consumed over time, they will eventually deplete after a certain number of years. However, due to the high cost and difficulty of replacing anodes, replacement is generally abandoned, leading to corrosion of the oil and gas well casing.

[0004] II. Forced current cathodic protection is employed, with the auxiliary anode being a deep-well anode bed. This method requires drilling a separate deep well near the protected well and installing the auxiliary anode, resulting in significant investment. This method relies on an ideal state of uniform geological conditions, similar to the cathodic protection principle of common shallow horizontal pipelines. Common shallow horizontal pipelines exhibit good cathodic protection because the differences in shallow geological conditions along the pipeline are not significant, allowing for controllable distribution of the shallow protection electric field. However, oil and gas well casings often penetrate vertically to considerable depths, some approaching 10,000 meters, penetrating various complex geological layers, including multiple water-blocking and electrical-breaking layers. The varying oxidizability of different substances in each geological layer leads to severe macro-cell corrosion between layers and severely uneven distribution of the cathodic protection current electric field, deviating significantly from the ideal state. Therefore, the actual cathodic protection effect is severely uneven; some areas are underprotected and prone to corrosion perforation, while others are overprotected, resulting in hydrogen evolution and potentially hydrogen embrittlement or cathodic stripping.

[0005] Third, based on Method 2 above, the cathodic protection power supply equipment adopts a pulsed power supply, replacing the previous DC protection current with pulsed current. The pulsed current is essentially a combination of AC and DC components. The AC component of the current penetrates geological layers with higher resistance more easily, thus optimizing the uniformity of the protective electric field. However, the DC component of the current is still significantly affected by the differences in geological layers underground, therefore the optimization effect on the uniformity of the electric field is limited, and the overall protection effect is also limited. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention provides a special equipment for cathodic protection construction of the outer wall of oil and gas well casing, which solves the technical problem that the prior art is unable to achieve the following effects: it can meet the requirements of precise and controllable opening in oil and gas well casing, so that the opening can meet the needs of installing anodes and related components, as well as the needs of accurate repair afterward, and can accurately install anodes and related components into the opening position, and can also accurately repair the opening and achieve the anti-corrosion effect.

[0007] The technical solution adopted by the present invention to solve the above problems is:

[0008] A special equipment for cathodic protection construction of the outer wall of oil and gas well casing includes a working module, which includes a drilling module and a drill body control structure that are interconnected.

[0009] As a preferred technical solution, the drilling module includes a drill bit, a segmented drill body, a pressure drill, and a drill body loading structure connected in sequence, and also includes a drill body segment storage structure capable of storing the segmented drill body.

[0010] As a preferred technical solution, the drill body is equipped with a protective shell, the protective shell has a control interface, and the protective shell contains a working unit. The drill body control structure can open the protective shell by operating the control interface.

[0011] As a preferred technical solution, the working unit includes one or more of the following: an anode unit, a test piece unit, a sensor unit, a bushing external expansion unit, a protective insulation unit for the bushing opening, and a repair unit for the bushing opening.

[0012] As a preferred technical solution, the protective shell can be opened in one or more of the following ways: expansion screw type, umbrella type, and sliding window type.

[0013] As a preferred technical solution, the cross-sectional shape of the drill control structure is an arc.

[0014] As a preferred technical solution, it also includes a vehicle body shell and a rotating mechanism connected to the vehicle body shell, wherein the rotating mechanism is a wheel or a track.

[0015] As a preferred technical solution, the number of rotating mechanisms is at least 3 sets.

[0016] As a preferred technical solution, the rotating mechanism is distributed in a triangular or polygonal shape.

[0017] As a preferred technical solution, each set of rotating mechanisms includes two or more wheels.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] This invention is used for drilling holes outwards into the inner wall of the protected well casing, installing anodes and related components through these holes, and repairing the holes. Currently, there is no similar dedicated construction equipment that can precisely control the drilling in the well casing to meet the needs of installing anodes and related components, accurately repairing the holes afterward, precisely installing the anodes and related components in the hole positions, and precisely repairing the holes to achieve corrosion protection. This invention makes these construction processes feasible. In sacrificial anode cathodic protection, it is used to replace or add sacrificial anodes, significantly reducing construction costs. In forced current cathodic protection, it is used to install anodes and related components, making segmented forced current cathodic protection with more uniform protection feasible, thereby improving the corrosion protection effect of the outer wall of the well casing and reducing costs. Attached Figure Description

[0020] Figure 1 This is a front view of the device of the present invention placed in the casing of an oil and gas well;

[0021] Figure 2 This is a side view of the device of the present invention placed in the casing of an oil and gas well;

[0022] Figure 3 This is a top view of the device of the present invention placed in the casing of an oil and gas well;

[0023] Figure 4 This is a schematic diagram of the forced current cathodic protection principle of the outer wall of the casing of an oil and gas well, taking the three geological layers of the oil and gas well as an example.

[0024] The labels and their corresponding names in the attached diagram:

[0025] 1-Cathode protection power supply equipment;

[0026] 2-Cathode terminals of cathodic protection power supply equipment;

[0027] 3-Zero-position terminal of cathodic protection power supply equipment;

[0028] 4-Reference terminals for cathodic protection power supply equipment;

[0029] 5 - Anode terminals of cathodic protection power supply equipment;

[0030] 6-Reference cable;

[0031] 7-Cathode cable;

[0032] 8-Reference electrode;

[0033] 9-Structural boundary;

[0034] 10 - Casing wall of oil and gas wells;

[0035] 11-Auxiliary anode ground bed;

[0036] 12-Test film;

[0037] 13- Cathode cable of the test piece;

[0038] 14-Syroscope;

[0039] 15-Ammeter;

[0040] 16 - Zero-position cable of the test piece;

[0041] 17 - Large resistance;

[0042] 21-The casing wall of oil and gas wells;

[0043] 22-Body shell;

[0044] 23- Drill body control structure;

[0045] 24-Drill bit;

[0046] 25 - The drill bit being drilled;

[0047] 26 - Drill shaft in a segmented storage structure;

[0048] 27-Drill bit and drill body chamber structure;

[0049] 28 - Highest dividing line;

[0050] 29-Rotating mechanism. Detailed Implementation

[0051] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0052] Example 1

[0053] like Figures 1 to 4 As shown, in order to overcome the shortcomings of the prior art, the present invention provides a special equipment for cathodic protection construction of the outer wall of oil and gas well casing. It is mainly used to drill holes outward from the inner wall of the casing to be protected, and to install the anode and related components to the outer wall of the oil and gas well casing through the holes. After the construction is completed, the holes need to be repaired with insulating and anti-corrosion materials.

[0054] In fact, for all cathodic protection methods on the outer wall of pipelines, the anode must be placed outside the outer wall of the pipeline in order to protect the outer wall of the pipeline.

[0055] Regarding the first technical method in the background, for oil and gas wells that need to replace or add sacrificial anodes, if the construction is carried out by drilling from the inner wall of the protected well casing outwards, the replacement or addition cost will be greatly reduced.

[0056] Regarding methods two and three in the background technology, segmented forced current cathodic protection is required to achieve a more uniform and controllable distribution of the protective electric field, solve the macrocell corrosion problem, and eliminate under-protection or over-protection phenomena. On the other hand, methods two and three in the background technology involve drilling additional wells outside the oil and gas well to install auxiliary anodes, which is not conducive to installing multiple auxiliary anodes with different parameters according to geological stratification for segmented protection. If multiple auxiliary anodes are buried vertically in the same deep well, severe interference occurs between the anodes, rendering the segmented protection ineffective; if multiple auxiliary anodes are buried in different deep wells, many more wells need to be drilled, resulting in excessive costs. The equipment provided by this invention can drill holes from the inner wall of the protected well casing outwards for construction, meeting the requirement of setting multiple non-interfering anodes in segmented forced current cathodic protection, making segmented forced current cathodic protection feasible, and significantly reducing anode installation costs.

[0057] The technical solution adopted in this invention is:

[0058] 1. Based on the underground traveling trolley, it includes wheels or tracks, the trolley body shell 22, working modules, and monitoring cameras. The working modules are basically located inside the trolley body shell.

[0059] 2. The working module is mainly responsible for three functions: first, drilling; second, installing the anode and related components to the outside of the oil and gas well casing (the casing wall 21 of the oil and gas well) through the opening; and third, repairing the opening.

[0060] 3. The three functions of the working module are mainly realized through two parts: the drilling module and the drill body control structure 23 (illustrated as a notched ring for simplicity, where the notch represents the space for the next drill body to be loaded). The drilling module includes the drill bit 24, segmented drill bodies (including the drill body currently drilling 25 and the drill body 26 in the segmented storage structure), the segmented storage structure, the pressure drilling and drill body loading structure 27, and the electric motor. Multiple different drill body segments enable various functions of the working module. The drill body can carry multiple working units, including an anode unit, a test piece unit, other necessary sensor units, a casing external reaming unit, and a protective insulation and repair unit for casing openings. The segmented storage structure stores the segmented drill bits sequentially, like bullets in a magazine.

[0061] 4. During drilling, after the drill bit is fully inserted into the casing, the drill body segments are added behind the drill bit by the press drill and drill body loading structure, and then the drilling operation continues. Once the drill body is drilled to the appropriate position, the drill body control structure can operate the control interface of the drill body from behind the drill body. Operation types include:

[0062] Open the protective shells of the anode unit drill body, the test piece unit drill body, and other required sensor unit drill bodies to put them into working condition. The opening structure can adopt various methods such as expansion screw type, umbrella type, and sliding window type.

[0063] The reaming structure of the drill body of the casing external reaming unit is unfolded to enable reaming operation. The unfolded structure is similar to an expansion screw. After unfolding, the drill body can rotate to enlarge the hole diameter in the environmental medium, opening up space for the work of other drill body units.

[0064] The protective insulation and repair unit of the casing opening is unfolded. The unfolded structure is similar to an expansion screw. After unfolding, the protective insulation material expands and completely covers and presses the metal surface of the casing opening, so that the casing opening is sealed and repaired and protected, while also being able to withstand the pressure difference between the inside and outside of the casing.

[0065] 5. The car body shell is mainly responsible for three functions: first, to provide a protected space for the working module, so that the working module can work in an environment free from oil, water and sludge pollution; second, to balance the pressure inside and outside the car body shell; and third, to install a flow guide to reduce the resistance of the car in the fluid.

[0066] 6. The trolley's outer shell primarily stores air. When the trolley enters a high-pressure environment, some external liquid flows into the outer shell, compressing the existing air and achieving pressure balance. This prevents external liquid from entering the interior through the gap between the drill bit and the body due to pressure difference, thus avoiding contamination. Simultaneously, the majority of the working module operates within the compressed air inside the trolley, preventing contamination and interference.

[0067] 7. When the trolley travels within the casing of an oil and gas well, other fluids flow within the well. In oil and gas production wells, the fluid flows from bottom to top, while in injection wells or water injection wells, the fluid flows from top to bottom. To minimize disturbances during trolley movement and to reduce the impact on oil and gas well operations, the trolley's outer shell should be designed with a shape that minimizes resistance: the lower and upper parts of the trolley's outer shell should be pointed, and its projection along the casing's cross-section should be long and narrow.

[0068] 8. On the other hand, in order to balance the fluid resistance in the oil and gas well, a cable can be added above the trolley to apply auxiliary tension, and a weight can be added to the trolley to balance both the fluid resistance and the buoyancy of the trolley.

[0069] 9. The trolley's wheels or tracks should include at least three sets of wheels or tracks (rotating mechanism 29), generally four or more sets are more stable. They should be arranged in a triangular or polygonal pattern within the casing, abutting against the inner wall of the casing to ensure the trolley's stability in the cross-sectional direction within the casing. Each set of wheels or tracks should contain at least two wheels to ensure the trolley's stability in the axial direction of the casing. The trolley's wheels or tracks can be selected according to actual needs; wheels consume less energy and have lower costs, while tracks provide stronger adhesion.

[0070] Figure 1 In the middle, the highest dividing line 28 for external liquid to flow into the vehicle body shell is divided into two compartments by a horizontal partition. The two compartments are connected. The lower compartment is the external liquid inflow compartment, and the upper compartment is the compressed air compartment, which is also the space where the working module is located.

[0071] Example 2

[0072] like Figures 1 to 4 As shown, as a further optimization of Embodiment 1, this embodiment also includes the following technical features based on Embodiment 1:

[0073] This embodiment uses the application of the present invention in the construction of segmented forced current cathodic protection on the outer wall of an oil and gas well casing as an example. Figure 1 , Figure 2 , Figure 3 , Figure 4 The geological strata of this oil and gas well are divided into upper, middle and lower layers. The upper layer contains oxidizing minerals and has a high oxygen content. The middle layer is a dense water-resistant layer. The lower layer contains oil and gas resources and some reducing minerals.

[0074] Figure 4 The components include:

[0075] 3 sets of cathodic protection power supply equipment 1;

[0076] Cathode terminal 2 of the cathodic protection power supply equipment;

[0077] Zero-position terminal 3 of the cathodic protection power supply equipment;

[0078] Reference terminal 4 of the cathodic protection power supply equipment;

[0079] Anode terminal 5 of the cathodic protection power supply equipment;

[0080] The reference cable 6 is shared by 3 sets of cathodic protection power supply equipment;

[0081] The cathode cable 7 is shared by 3 sets of cathode protection power supply equipment;

[0082] The reference electrode 8 is shared by 3 sets of cathodic protection power supply equipment;

[0083] Stratigraphic boundary line 9;

[0084] Oil and gas well casing wall thickness 10;

[0085] Auxiliary anode ground bed 11, and anode cables individually connected to the anode terminals of their respective cathodic protection power supply equipment;

[0086] Test piece 12, and the connected cathode cable and zero-position cable;

[0087] The cathode cable 13 of the test piece is connected to the cathode cable shared by three sets of cathode protection power supply equipment via a thyristor.

[0088] The thyristor 14 connects or disconnects the cathode cable of the test piece according to the corresponding anode potential;

[0089] Ammeter 15 is connected to the cathode cable of the test piece;

[0090] The zero-position cable 16 of the test piece is connected to the zero-position terminal of its corresponding cathodic protection power supply device;

[0091] The large resistance 17 between the thyristor and the corresponding anode connecting cable.

[0092] Under normal circumstances, the upper and lower layers are in a state of equal positive and negative charge, separated by the middle layer, making it difficult for matter to exchange or influence each other. After the oil and gas well is drilled through, the casing connects the electron channels of the upper and lower layers, causing oxidizing minerals and oxygen in the upper layer to gain electrons through the casing, while reducing minerals in the lower layer provide electrons. The difference in charged ion concentration between the upper and lower layers drives the exchange of positive and negative charges, forming a battery circuit. Therefore, electrons continuously flow into the casing from the lower layer, while iron ions flow into the surrounding medium, forming macrocell corrosion.

[0093] If methods two or three from the background section are used instead of segmented cathodic protection, the resistivity of the upper and lower layers is relatively low, while the resistivity of the middle water-resistant layer is relatively high. If the anode bed is placed in the upper or middle layer, the middle and lower casings are difficult to protect; if the anode bed is placed in the lower layer, the middle casing is difficult to protect, and the upper casing is directly protected by the macrocell current. Therefore, segmented forced current cathodic protection is needed for the casing of this oil and gas well to make the protective electric field distribution more uniform and controllable, solve the macrocell corrosion problem, and eliminate under-protection or over-protection phenomena.

[0094] On the other hand, methods two and three in the background technology involve drilling additional wells outside the oil and gas well to install auxiliary anodes, which is not conducive to installing multiple auxiliary anodes with different parameters according to geological stratification for segmented protection. If multiple auxiliary anodes are buried vertically in the same deep well, the mutual interference between the anodes is severe, rendering the segmented protection ineffective; if multiple auxiliary anodes are buried in different deep wells, many more wells need to be drilled, resulting in excessive costs. The equipment provided by this invention can drill holes from the inner wall of the protected well casing outwards for construction, meeting the requirement of setting multiple non-interfering anodes in segmented forced current cathodic protection, making segmented forced current cathodic protection feasible, and significantly reducing anode installation costs.

[0095] The specific implementation process of the segmented forced current cathodic protection of the oil and gas well casing should involve drilling holes from the inside out for the upper, middle and lower layers of the oil and gas well casing, and placing auxiliary anodes and test pieces respectively.

[0096] Each of the upper, middle, and lower anodes is connected to the corresponding anode terminal of the cathodic protection power supply equipment through an independent anode cable.

[0097] Each of the three test pieces, upper, middle, and lower, is connected to the zero-position terminal of the corresponding cathodic protection power supply equipment through an independent zero-position cable.

[0098] In this embodiment, each of the upper, middle, and lower layers is equipped with independent cathodic protection power supply equipment, test pieces, and anodes. The corresponding cathodic protection parameters are calculated based on the different oxidation characteristics and other geological parameters of each layer.

[0099] In the specific construction process, taking the installation of the anode as an example, the installation procedure is as follows:

[0100] 1. Drill holes in the casing of oil and gas wells from the inside out;

[0101] 2. After connecting the reaming unit drill body to the drill bit, continue drilling while simultaneously sending the reaming unit drill body outside the casing;

[0102] 3. After connecting the anode external filler unit drill body to the front drill body, continue drilling. At the same time, send the anode external filler unit drill body to the outside of the casing. The anode external filler can generally be coke-like material. When unfolding, the filler can be pressed laterally into the environmental medium through an expansion screw type structure.

[0103] 4. After connecting the anode unit drill body to the front drill body, continue drilling while simultaneously sending the anode unit drill body outside the casing;

[0104] 5. After connecting the anode external insulation unit drill body to the front drill body, continue drilling. At the same time, send the anode external insulation unit drill body to the outside of the casing. After the anode external insulation unit drill body is deployed, an insulation area can be set in the environmental medium behind the anode bed to prevent a large amount of anode current from flowing directly to the nearest end of the oil and gas well casing through the gap liquid in the borehole, which would weaken the protective current at the far end of the pipeline.

[0105] 6. After connecting the extension drill body to the front drill body, continue drilling to deliver the front drill body to the target depth;

[0106] 7. Using the drill body control structure, unfold the drill body of the reaming unit to carry out the reaming operation;

[0107] 8. After the hole is enlarged, connect the extended drill body to the front drill body and send the anode external filler unit drill body to the enlarged hole position. Then, use the drill body control structure to unfold the anode external filler unit drill body and press the filler into the environmental medium laterally.

[0108] 9. After connecting the extended drill body to the front drill body, send the anode unit drill body to the packing position, and then use the drill body control structure to unfold the anode unit drill body and press it into the packing laterally;

[0109] 10. After connecting the protective insulation and repair unit drill body with the casing opening to the front drill body, send the anode outer insulation unit drill body to the rear of the anode bed. Then, using the drill body control structure, unfold the anode outer insulation unit drill body to block the shortest route between the rear of the anode and the oil and gas well casing.

[0110] 11. At this point, the drill bit of the protective insulation and repair unit for the casing opening has been inserted into the casing opening, with part of it outside the casing and part of it inside the casing. At this point, the drill bit control structure is used to unfold it, so that the protective insulation material is laterally squeezed against the inner and outer walls of the casing opening to repair the casing opening.

[0111] 12. Secure the installed anode to the inner wall of the well casing, through the opening, and run it from the inner wall to the ground for further testing and installation work.

[0112] Based on the above construction process, it can be seen that before installation, the drill body sections should be placed sequentially in the drill body segment storage structure. After the drill bit and drill body are placed, the equipment counterweight needs to be installed, and then the top of the trolley is connected with a cable and placed in the oil and gas well casing to lower it to the installation position for installation.

[0113] In the actual construction process, installing the test piece is simpler than installing the anode. The installation procedure is as follows:

[0114] 1. Drill holes in the casing of oil and gas wells from the inside out;

[0115] 2. After connecting the test piece unit drill body to the drill bit, continue drilling while simultaneously sending the test piece unit drill body outside the casing;

[0116] 3. After connecting the protective insulation and repair unit drill body with the casing hole to the front drill body, continue drilling to deliver the test piece unit drill body to the target depth;

[0117] 4. Using the drill body control structure, unfold the drill body of the test piece unit;

[0118] 5. Using the drill body control structure, unfold the drill body of the protective insulation and repair unit for the casing opening, and repair the casing opening;

[0119] 6. Secure the installed test piece to the inner wall of the oil and gas well casing through the cable connected by the opening, and extend it from the inner wall to the ground for further testing and installation work on the ground.

[0120] As described above, the present invention can be implemented well.

[0121] All features disclosed in all embodiments of this specification, or steps in all methods or processes implied in the disclosure, may be combined and / or extended or replaced in any way, except for mutually exclusive features and / or steps.

[0122] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Based on the technical essence of the present invention, any simple modifications, equivalent substitutions, and improvements made to the above embodiments within the spirit and principles of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A special equipment for cathodic protection construction of the outer wall of oil and gas well casing, characterized in that, It includes a working module, which consists of interconnected drilling modules and a drill body control structure; The drilling module includes a drill bit, a segmented drill body, a pressure drill and a drill body loading structure connected in sequence, and also includes a drill body segment storage structure that can store the segmented drill body. The drill body is equipped with a protective shell, which has a control interface. Inside the protective shell is a working unit. The drill body control structure can open the protective shell by operating the control interface. The working unit includes one or more of the following: anode unit, test piece unit, sensor unit, bushing external hole enlargement unit, bushing hole protection and insulation unit, and bushing hole repair unit; The steps for installing the anode are as follows: 1) Drill holes in the casing of oil and gas wells from the inside out; 2) Connect the reaming unit drill body to the drill bit and continue drilling, while simultaneously sending the reaming unit drill body outside the casing; 3) After connecting the anode external packing unit drill body to the front drill body, continue drilling. At the same time, send the anode external packing unit drill body to the outside of the casing. The anode external packing uses coke-like materials. When unfolding, the packing is pressed laterally into the environmental medium through an expansion screw-type structure. 4) After connecting the anode unit drill body to the front drill body, continue drilling while simultaneously sending the anode unit drill body outside the casing; 5) After connecting the anode external insulation unit drill body to the front drill body, continue drilling. At the same time, send the anode external insulation unit drill body to the outside of the casing. After the anode external insulation unit drill body is deployed, set up an insulation area in the environmental medium behind the anode bed to prevent the anode current from flowing directly to the nearest end of the oil and gas well casing through the gap liquid in the borehole, which would weaken the protection current at the far end of the pipeline. 6) After connecting the extension drill body to the front drill body, continue drilling to deliver the front drill body to the target depth; 7) Using the drill body control structure, the drill body of the reaming unit is unfolded to carry out the reaming operation; 8) After the hole is enlarged, connect the extended drill body to the front drill body and send the anode external filler unit drill body to the enlarged hole position. Then, use the drill body control structure to unfold the anode external filler unit drill body and press the filler into the environmental medium laterally. 9) After connecting the extended drill body to the front drill body, send the anode unit drill body to the packing position, and then use the drill body control structure to unfold the anode unit drill body and press it laterally into the packing. 10) After connecting the protective insulation and repair unit drill body with the casing opening to the front drill body, send the anode outer insulation unit drill body to the rear of the anode bed, and then use the drill body control structure to unfold the anode outer insulation unit drill body to block the shortest route between the rear of the anode and the oil and gas well casing. 11) At this time, the drill body of the protective insulation and repair unit of the casing opening has been inserted into the casing opening, part of it is outside the casing and part of it is inside the casing. At this time, the drill body control structure is used to unfold it, so that the protective insulation material is laterally squeezed on the inner and outer walls of the casing opening to repair the casing opening. 12) Secure the installed anode cable, which is connected through the opening, close to the inner wall of the oil and gas well casing, and run it from the inner wall to the ground for further testing and installation work on the ground.

2. The special equipment for cathodic protection construction of the outer wall of oil and gas well casing according to claim 1, characterized in that, The protective case can be opened in one or more of the following ways: expansion screw type, umbrella type, sliding window type.

3. The special equipment for cathodic protection construction of the outer wall of oil and gas well casing according to claim 1, characterized in that, The cross-sectional shape of the drill control structure is an arc.

4. A special equipment for cathodic protection construction of the outer wall of oil and gas well casing according to any one of claims 1 to 3, characterized in that, It also includes the vehicle body shell and a rotating mechanism connected to the vehicle body shell, the rotating mechanism being wheels or tracks.

5. A special equipment for cathodic protection construction of the outer wall of oil and gas well casing according to claim 4, characterized in that, The number of rotating mechanisms is at least 3 sets.

6. A special equipment for cathodic protection construction of the outer wall of oil and gas well casing according to claim 4, characterized in that, The rotating mechanism is distributed in a triangular or polygonal pattern.

7. A special equipment for cathodic protection construction of the outer wall of oil and gas well casing according to claim 4, characterized in that, Each rotating mechanism includes two or more wheels.

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