Anti-corrosion method for underground shaft

Abstract

The invention provides a corrosion prevention method for an underground shaft, and belongs to the technical field of underground shaft corrosion prevention. The anti-corrosion method of the underground shaft comprises the following steps that deep wells are excavated, and the deep wells and the underground shaft are distributed at intervals; mounting an anode group and an exhaust pipe in the deep well; the deep well is filled with carbonaceous filler until the area, corresponding to the anode group, in the deep well is filled; and the anode set and the underground shaft are connected through a cable and powered on, so that the anode set and the underground shaft form a current loop, and the problem that the underground shaft is extremely prone to corrosion can be solved to a certain degree.

Description

Technical Field

[0001] This application relates to the field of underground well shaft corrosion protection technology, and more specifically, to a method for corrosion protection of underground well shafts. Background Technology

[0002] Underground well casings are typically formed by splicing together multiple sections of pipe, with a total length (which can also be understood as the depth after installation) generally ranging from 50 to 300 meters. Installed in deep underground wells, they primarily serve to support and stabilize process equipment and isolate the well from geological formations. They are currently widely used in oil storage, bridge construction, coal mining, geothermal heat pumps, and chemical production. Carbon steel, due to its superior structural strength and relatively economical price, has become the most commonly used material for manufacturing underground well casings. However, carbon steel is highly susceptible to corrosion, significantly impacting the service life of the well casing. Furthermore, various process equipment is usually installed inside the well casing as needed; corrosion of the casing further affects the functionality and lifespan of this internal equipment. Summary of the Invention

[0003] The purpose of this application is to provide a corrosion prevention method for underground well casings, which can improve the problem of underground well casings being easily corroded to a certain extent.

[0004] The embodiments of this application are implemented as follows:

[0005] This application provides a method for corrosion protection of underground well casings made of carbon steel, comprising the following steps:

[0006] Deep wells are excavated, with the deep wells and underground shafts distributed at intervals; anode groups and vent pipes are installed in the deep wells; carbonaceous filler is filled into the deep wells until the area corresponding to the anode groups is completely filled; the anode groups and underground shafts are connected by cables and energized to form a current loop between the anode groups and the underground shafts.

[0007] In the aforementioned technical solution, a deep well is excavated next to the underground well casing, and an anode assembly and vent pipe are installed in the deep well. The anode assembly and the underground well casing are then connected and energized via cables, forming a current loop between them. This utilizes cathodic protection technology to mitigate corrosion of the underground well casing. Specifically, by applying a cathodic current to the underground well casing, when the cathodic current reaches the self-corrosion potential of the casing, polarization begins to occur on the carbon steel surface. At this point, the cathodic zone disappears, and the metal oxidation and dissolution process stops, thereby reducing the probability of pitting corrosion in the carbon steel underground well casing (especially in areas of wear during installation and areas with insufficient anti-corrosion measures), thus achieving the goal of protecting the underground well casing. Filling the corresponding area of ​​the anode assembly with carbonaceous filler reduces the grounding resistance of the anode assembly, improves current distribution, and extends the service life of the anode assembly.

[0008] In some alternative implementations, the cable includes an anode cable, a cathode cable, and a main cable, with one end of the cathode cable connected to the main cable and the other end connected to the underground well shaft; the anode group is fixedly connected to the outer peripheral wall of the exhaust pipe, with one end of the anode cable connected to the anode group, and the anode cable passing through the exhaust pipe and the other end connected to the main cable.

[0009] In the above technical solution, the anode assembly is fixed to the outer peripheral wall of the exhaust pipe, so that the anode assembly and the exhaust pipe are integrated together, which has the advantages of a more compact overall structure and easy installation in deep wells; at the same time, the anode cable is run through the exhaust pipe and connected to the main cable, that is, the anode cable is laid with the help of the internal cavity of the exhaust pipe, which can effectively protect the anode cable and thus extend the service life of the anode cable.

[0010] In some alternative implementations, after filling with carbonaceous filler and before energizing the cable, a step of installing a protective cover is included, which surrounds the top of the well to seal it, and one end of an exhaust pipe extends to and through the cover for venting.

[0011] In the above technical solution, after filling with carbonaceous filler and before energizing the cable, a protective cover is installed on the top of the deep well. This can better protect the functional components inside the deep well, such as the anode group, anode cable, and exhaust pipe. Especially under extreme weather conditions such as high temperature or heavy rain, it can provide long-term and stable protection for the underground wellbore, thereby improving the corrosion resistance.

[0012] In some alternative implementations, an anode junction box is installed on the inner wall of the enclosure, and the exhaust pipe includes a vertically extending main exhaust pipe and a first branch pipe and a second branch pipe located at the top of the deep well. The anode cable extends sequentially through the main exhaust pipe and the first branch pipe to the anode junction box and connects with the main cable. The second branch pipe penetrates the side wall of the enclosure.

[0013] Optionally, the first branch pipe and the second branch pipe extend in opposite directions.

[0014] In the above technical solution, the anode junction box is installed on the inner wall of the protective cover. Correspondingly, the connection points of the anode cable and the main cable are also located inside the protective cover, which can reduce the adverse effects of the external environment on the corresponding functional components and thus reduce the failure rate of the process equipment. At the same time, setting the exhaust pipe as a combination of a main exhaust pipe and two branch pipes has the advantages of reasonable layout and easy installation.

[0015] Furthermore, the two branch pipes are arranged in opposite directions to keep the electrical connection area and the exhaust area far apart, thereby making it less likely for interference to occur between different functional areas.

[0016] In some alternative implementations, the top of the underground shaft extends above the ground level.

[0017] Optionally, the top of the underground shaft may extend 0.5 to 1.2 meters above the ground.

[0018] Optionally, at least three anode groups are provided, and multiple anode groups are distributed at vertical intervals.

[0019] Optionally, the anode material of the anode assembly includes at least one of zinc, aluminum, titanium, high-silicon cast iron, magnesium alloy, and precious metal oxide.

[0020] Optionally, the carbonaceous filler material includes at least one of metallurgical coke, calcined petroleum coke, and graphite.

[0021] In the above technical solution, the top of the underground well extends above the ground, which facilitates the installation of cables and corresponding encapsulation devices.

[0022] Furthermore, multiple anode groups are provided, which can offer a longer service life.

[0023] Furthermore, the anode material and carbonaceous filler material of the anode assembly have a wide range of available types, providing numerous feasible implementation methods, thereby facilitating the promotion and application of the technical solution of this application.

[0024] In some alternative implementations, the wall thickness of the underground well is 12–30 mm.

[0025] In the above technical solution, setting the wall thickness of the underground well casing within a specific range can give the underground well casing strong corrosion resistance, thereby providing a longer service life.

[0026] In some alternative implementations, the outer perimeter wall of the underground well is also provided with an anti-corrosion layer.

[0027] Alternatively, the material of the anti-corrosion layer includes at least one of epoxy coal tar pitch, thick-film epoxy, and extruded polyethylene.

[0028] Optionally, the thickness of the anti-corrosion layer is ≥2mm.

[0029] In the above technical solution, the outer wall of the underground well is provided with an anti-corrosion layer, which can improve the corrosion resistance of the underground well.

[0030] Furthermore, the materials used for the anti-corrosion layer are of many types, providing a wide range of feasible implementations, which facilitates the promotion and application of the technical solution of this application.

[0031] Furthermore, limiting the thickness of the anti-corrosion layer to a specific range can provide better anti-corrosion effects.

[0032] In some alternative implementations, a concrete curing layer is also provided on the outer periphery of the anti-corrosion layer.

[0033] Optionally, the thickness of the concrete solidification layer is ≥100mm.

[0034] In the above technical solution, a concrete solidification layer is set on the outer perimeter of the anti-corrosion layer, which can further improve the anti-corrosion capability of the underground well.

[0035] Furthermore, limiting the thickness of the concrete solidification layer to a specific range can provide better corrosion protection.

[0036] In some alternative implementations, process equipment is installed inside the underground shaft, and a transition piece is provided on the inner peripheral wall of the underground shaft to separate the inner peripheral wall of the underground shaft from the outer peripheral wall of the process equipment.

[0037] Alternatively, the transition piece may be made of plastic, nylon, or insulating bakelite.

[0038] Optionally, multiple transition elements are provided, and the multiple transition elements are distributed at vertical intervals.

[0039] Optionally, the transition piece extends circumferentially along the underground shaft and is connected end to end.

[0040] Optionally, the thickness of the transition piece is 10–30 mm.

[0041] In the above technical solution, the inner peripheral wall of the underground well is provided with a transition piece to separate the inner peripheral wall of the underground well from the outer peripheral wall of the process equipment, which can prevent corrosion between different materials after the process equipment comes into contact with the underground well.

[0042] Furthermore, the transition component has a wide range of available materials, providing more feasible implementation methods, which facilitates the promotion and application of the technical solution of this application.

[0043] Furthermore, setting multiple transition elements can improve the separation effect, thereby better protecting the process equipment.

[0044] Furthermore, the transition pieces are connected end to end to form a complete closed loop, which can achieve a better separation effect.

[0045] Furthermore, limiting the thickness of the transition piece (i.e., the radial dimension) to a specific range can provide a better separation effect.

[0046] In some alternative implementations, after the process equipment is installed and sealed inside the underground shaft, the process also includes a step of evacuating the interior of the underground shaft.

[0047] Optionally, during the vacuuming step, the vacuum level inside the underground wellbore is maintained until it reaches 0.01 to 1 Pa.

[0048] In the above technical solution, after the process equipment is installed and sealed inside the underground well, the underground well is evacuated, which can effectively remove the air inside the underground well, thereby improving the corrosion resistance of the inner wall of the underground well.

[0049] Furthermore, limiting the internal vacuum level of underground well casings to a specific range can provide better corrosion resistance.

[0050] In some alternative implementations, a first flange is provided at the top of the underground shaft, a second flange corresponding to the first flange is provided at the top of the process equipment, and an anti-corrosion flange gasket is provided between the first flange and the second flange.

[0051] Optionally, both the mating surfaces of the first flange and the second flange are provided with a rust-proof layer.

[0052] In the above technical solution, based on the flange sealing connection between the underground shaft and the process equipment, an anti-corrosion flange gasket is installed between the two to separate the sealing connection between them, thereby preventing corrosion from occurring after the process equipment comes into contact with the underground shaft.

[0053] Furthermore, a rust-proof layer is provided on both the mating surfaces of the first flange and the second flange, which can further reduce the probability of corrosion after the process equipment comes into contact with the underground well. Attached Figure Description

[0054] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 A cross-sectional schematic diagram of the first type of underground well provided in the embodiments of this application;

[0056] Figure 2 A cross-sectional schematic diagram of a second type of underground well provided in an embodiment of this application;

[0057] Figure 3 A cross-sectional schematic diagram showing the connection between an underground well and process equipment via flanges, as provided in an embodiment of this application.

[0058] Figure 4 A process flow diagram of a corrosion protection method for underground well shafts provided in this application embodiment;

[0059] Figure 5 A schematic diagram of the structure after the anode assembly and exhaust pipe are installed in a deep well, as provided in an embodiment of this application;

[0060] Figure 6 This is a schematic diagram of the structure of the protective cover area after the protective cover is installed, provided in an embodiment of this application.

[0061] Figure 7 This is a schematic diagram of the structure after the anode group and the underground well are connected, as provided in the embodiments of this application.

[0062] Icons: 10-Underground well shaft; 11-Anti-corrosion layer; 12-Concrete curing layer; 13-Transition component; 14-First flange; 15-Second flange; 16-Anti-corrosion flange gasket; 17-Cathode cable; 20-Deep well; 21-Anode group; 22-Exhaust pipe; 22a-Main exhaust pipe; 22b-First branch pipe; 22c-Second branch pipe; 23-Anode cable; 24-Sheath; 25-Anode junction box; 26-Main cable. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0064] It should be noted that the terms "and / or" in this application, such as "feature 1 and / or feature 2", all refer to the three cases of "feature 1" alone, "feature 2" alone, and "feature 1" plus "feature 2".

[0065] In addition, in the description of this application, unless otherwise stated, "one or more" means two or more; the range of "numerical value a to numerical value b" includes the two endpoints "a" and "b"; and "unit of measurement" in "numerical value a to numerical value b + unit of measurement" represents the "unit of measurement" of both "numerical value a" and "numerical value b".

[0066] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0067] In the description of this application, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0068] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0069] See Figure 1 This application provides an underground well shaft 10, which is made of carbon steel and has a wall thickness of 12 to 30 mm, for example, but not limited to any one of 12 mm, 15 mm, 20 mm, 25 mm and 30 mm or any range between two of them.

[0070] Carbon steel has become the most commonly used manufacturing material for underground well casings 10 due to its superior structural strength and relatively economical price. However, carbon steel is highly susceptible to corrosion, which significantly affects the service life of the underground well casing 10. In this application, by setting the wall thickness of the underground well casing 10 within a specific range, the underground well casing 10 can be endowed with strong corrosion resistance, thereby providing a longer service life.

[0071] See Figure 1 As an example, the outer perimeter wall of the underground well 10 is also provided with an anti-corrosion layer 11.

[0072] In this embodiment, an anti-corrosion layer 11 is provided on the outer peripheral wall of the underground well 10, which can improve the corrosion resistance of the underground well 10.

[0073] As an example, the material of the anti-corrosion layer 11 includes at least one of epoxy coal tar pitch, thick-film epoxy, and extruded polyethylene.

[0074] In this embodiment, the material of the anti-corrosion layer 11 has many available types, which can provide many possible implementation methods, thereby facilitating the promotion and application of the technical solution of this application.

[0075] As an example, the thickness of the anti-corrosion layer 11 is ≥2mm, for example, but not limited to any one of 2mm, 4mm, 6mm, 8mm and 10mm or any range between two.

[0076] In this embodiment, limiting the thickness of the anti-corrosion layer 11 to a specific range can provide a better anti-corrosion effect.

[0077] See Figure 1As an example, the outer perimeter of the anti-corrosion layer 11 is also provided with a concrete curing layer 12.

[0078] In this embodiment, a concrete curing layer 12 is provided on the outer periphery of the anti-corrosion layer 11, which can further enhance the anti-corrosion capability of the underground well shaft 10.

[0079] As an example, the thickness of the concrete solidification layer 12 is ≥100mm, for example, but not limited to any point value or any range between 100mm, 110mm, 120mm, 130mm and 140mm.

[0080] In this embodiment, the thickness of the concrete curing layer 12 is further limited to a specific range, which can provide a better anti-corrosion effect.

[0081] It is understandable that, since the concrete curing layer 12 is relatively thick and has a complex composition, its corrosion resistance is closely related to its many internal parameters. Based on this, the material of the concrete curing layer 12 can be optimized.

[0082] As an example, in the material of the concrete curing layer 12, the concrete grade used is not lower than C25, the maximum water-cement ratio is 0.4, the impermeability grade is P10, the chloride ion content in the cementitious material is less than 0.08%, and the alkali content in the cementitious material is less than 3 kg / m³. 3 Minimum dosage of cementitious materials: 320 kg / m³ 3 The chloride ion migration coefficient is less than 5 after 28 days.

[0083] It should be noted that the above parameters of the material of the concrete curing layer 12 are not fixed and can be adjusted according to actual needs.

[0084] In other possible implementations, polymer cement concrete with a corresponding corrosion resistance rating may also be selected.

[0085] It should be noted that the underground shaft 10 is made of carbon steel, while the internal process equipment is typically made of stainless steel. Contact between the two makes corrosion highly likely. The main reasons are: firstly, carbon migration from the carbon steel causes chromium in the stainless steel to form chromium carbide, which reduces the corrosion resistance of the stainless steel, leading to carburizing corrosion; secondly, there is a potential difference between stainless steel and carbon steel, resulting in an electrochemical reaction upon contact, causing electrochemical corrosion. Therefore, when stainless steel process equipment is installed inside the carbon steel underground shaft 10, direct contact between the two must be prevented.

[0086] See Figure 2As an example, a process device (not shown in the figure) is installed inside the underground shaft 10, and a transition member 13 is provided on the inner peripheral wall of the underground shaft 10 to separate the inner peripheral wall of the underground shaft 10 from the outer peripheral wall of the process device.

[0087] In this embodiment, the inner peripheral wall of the underground shaft 10 is provided with a transition member 13 for separating the inner peripheral wall of the underground shaft 10 from the outer peripheral wall of the process equipment, which can prevent corrosion between different materials after the process equipment comes into contact with the underground shaft 10.

[0088] As an example, the transition piece 13 is made of plastic, nylon, or insulating bakelite.

[0089] In this embodiment, the material of the transition member 13 has many available types, which can provide many possible implementation methods, thereby facilitating the promotion and application of the technical solution of this application.

[0090] See Figure 2 As an example, multiple transition elements 13 are provided, and the multiple transition elements 13 are distributed at vertical intervals, for example, three transition elements 13 can be provided at intervals.

[0091] In this embodiment, multiple transition pieces 13 are provided to improve the separation effect, thereby better protecting the process equipment.

[0092] As an example, the transition piece 13 extends circumferentially along the underground shaft 10 and is connected end to end.

[0093] In this embodiment, the transition piece 13 is connected end to end to form a complete closed loop, which can achieve a better separation effect.

[0094] As an example, the thickness of the transition piece 13 is 10 to 30 mm, for example, but not limited to any one of 10 mm, 15 mm, 20 mm, 25 mm and 30 mm or any range between two of them.

[0095] In this embodiment, limiting the thickness (i.e., the radial dimension) of the transition member 13 to a specific range can provide a better separation effect.

[0096] As an example, after the process equipment is installed and sealed inside the underground shaft 10, the process also includes a step of evacuating the interior of the underground shaft 10.

[0097] In this embodiment, after the process equipment is installed and sealed inside the underground shaft 10, a vacuum is drawn into the underground shaft 10, which can effectively remove the air inside the underground shaft 10, thereby improving the corrosion resistance of the inner wall of the underground shaft 10.

[0098] As an example, during the evacuation process, the vacuum level inside the underground wellbore 10 is maintained at 0.01 to 1 Pa, for example, but not limited to any one of 0.01 Pa, 0.1 Pa, 0.2 Pa, 0.4 Pa, 0.6 Pa, 0.8 Pa, and 1.0 Pa, or any range between two of them.

[0099] In this embodiment, the internal vacuum degree of the underground well 10 is further limited to a specific range, which can provide better corrosion resistance.

[0100] See Figure 3 As an example, the top of the underground shaft 10 is provided with a first flange 14 (made of carbon steel), the top of the process equipment is provided with a second flange 15 (made of stainless steel) corresponding to the first flange 14, and an anti-corrosion flange gasket 16 is provided between the first flange 14 and the second flange 15.

[0101] In this embodiment, based on the flange sealing connection between the underground shaft 10 and the process equipment, an anti-corrosion flange gasket 16 is set between the two to separate the sealing connection between the two, thereby preventing corrosion from occurring after the process equipment comes into contact with the underground shaft 10.

[0102] As an example, both the mating surfaces of the first flange 14 and the second flange 15 are provided with an anti-rust layer (not shown in the figure).

[0103] In this embodiment, a rust-proof layer is further provided on both the mating surface of the first flange 14 and the mating surface of the second flange 15, which can further reduce the probability of corrosion after the process equipment comes into contact with the underground well shaft 10.

[0104] As an example, the mating surface of the second flange 15 is provided with a C-shaped chamfer.

[0105] It should be noted that for the structure of the underground shaft 10 itself and the structure or components of the process equipment and the underground shaft 10 connected by flange sealing, which are not specifically described or limited in the scheme, they can be set according to the conventional selection in the field.

[0106] In this application, in addition to adjusting the structure of the underground well 10 and the way the process equipment is matched with the underground well 10, the researchers have also creatively applied cathodic protection technology to the corrosion protection of the underground well. The method of combining cathodic protection technology with the corrosion protection of the underground well is as follows:

[0107] Deep wells are excavated, with the deep wells and underground shafts distributed at intervals; anode groups and vent pipes are installed in the deep wells; carbonaceous filler is filled into the deep wells until the area corresponding to the anode groups is completely filled; the anode groups and underground shafts are connected by cables and energized to form a current loop between the anode groups and the underground shafts.

[0108] In this application, a deep well is excavated next to the underground well casing, and an anode assembly and an exhaust pipe are installed in the deep well. The anode assembly and the underground well casing are then connected and energized via a cable, forming a current loop between them. This utilizes cathodic protection technology to mitigate corrosion of the underground well casing. Specifically, by applying a cathodic current to the underground well casing, when the cathodic current reaches the self-corrosion potential of the casing, polarization begins to occur on the carbon steel surface. At this point, the cathodic zone disappears, and the metal oxidation and dissolution process stops, thereby reducing the probability of pitting corrosion in the carbon steel underground well casing (especially in areas of wear during installation and areas with insufficient anti-corrosion measures), thus achieving the purpose of protecting the underground well casing. Filling the corresponding area of ​​the anode assembly with carbonaceous filler is to reduce the grounding resistance of the anode assembly, improve current distribution, and thus extend the service life of the anode assembly.

[0109] As an example, a process flow diagram of the corrosion protection method for underground well shafts is provided. Figure 4 .

[0110] To better understand the technical solution, each step will be explained in detail below.

[0111] S1 is a deep well excavation site, with deep wells and underground shafts distributed alternately.

[0112] It should be noted that there is no limit to the excavation depth of deep wells, which can be adjusted according to actual needs.

[0113] As an example, in step S1, the excavation depth of the deep well is 60 to 100 m, for example, but not limited to any one of the depths of 60 m, 70 m, 80 m, 90 m and 100 m or any range between two of them.

[0114] It should be noted that the distance between the deep well and the underground shaft is not limited and can be adjusted according to actual needs. For example, the distance can be 20 to 50 meters, or any one of 20 meters, 30 meters, 40 meters and 50 meters or any range between two of them.

[0115] It should be noted that the radial dimension of the deep well is not limited and can be adjusted according to actual needs. For example, the diameter of the deep well can be 200 to 400 mm, such as, but not limited to, any one of the diameters of 200 mm, 250 mm, 300 mm, 350 mm and 400 mm or any range between two.

[0116] S2 installs the anode assembly 21 and the exhaust pipe 22 in the deep well 20. (To better understand the technical solution, a structural diagram of the deep well 20 after the anode assembly 21 and the exhaust pipe 22 have been installed is provided for further explanation. Please refer to the diagram for details.) Figure 5 ).

[0117] It should be noted that the number of anode groups 21 is not limited and can be adjusted according to actual needs.

[0118] As an example, at least three anode groups 21 are provided, and multiple anode groups 21 are distributed at vertical intervals.

[0119] In this embodiment, multiple anode groups 21 are provided, which can provide a longer service life.

[0120] As an example, multiple anode groups 21 are distributed in parallel.

[0121] It should be noted that the number of anodes in each anode group 21 is not limited and can be adjusted according to actual needs. For example, each anode group 21 includes two anodes connected in series.

[0122] As an example, the anode material of anode group 21 includes at least one of zinc, aluminum, titanium, high-silicon cast iron, magnesium alloy and precious metal oxide.

[0123] In this embodiment, the anode material of the anode group 21 has a variety of available types, which can provide a variety of implementation methods, thereby facilitating the promotion and application of the technical solution of this application.

[0124] As an example, exhaust pipe 22 is made of PVC.

[0125] It should be noted that the inner diameter of the exhaust pipe 22 is not limited and can be adjusted according to actual needs.

[0126] It should be noted that the relative positional relationship between the anode group 21 and the exhaust pipe 22 is not limited and can be adjusted according to actual needs.

[0127] As an example, the anode assembly 21 is fixedly connected to the outer peripheral wall of the exhaust pipe 22.

[0128] In this embodiment, the anode assembly 21 is fixed to the outer peripheral wall of the exhaust pipe 22 so that the anode assembly 21 and the exhaust pipe 22 are integrated together, which has the advantages of a more compact overall structure and easy installation in the deep well 20.

[0129] It should be noted that the installation of anode group 21 also involves the laying of anode cable 23. Considering the rationality of the laying, the routing of anode cable 23 can be optimized.

[0130] As an example, one end of the anode cable 23 is connected to the anode assembly 21, the anode cable 23 passes through the exhaust pipe 22, and the other end is connected to the main cable 26.

[0131] In this embodiment, with the anode assembly 21 fixed to the outer peripheral wall of the exhaust pipe 22, the anode cable 23 is threaded through the exhaust pipe 22 and connected to the main cable 26. That is, the anode cable 23 is laid with the help of the internal cavity of the exhaust pipe 22, which can effectively protect the anode cable 23 and thus extend the service life of the anode cable 23.

[0132] S3 fills the deep well 20 with carbonaceous filler until the area in the deep well 20 corresponding to the anode group 21 is completely filled.

[0133] It should be noted that the carbon paper filler is used to fill the corresponding area of ​​the anode group 21 in order to reduce the grounding resistance of the anode group 21, thereby extending the service life of the anode group 21.

[0134] As an example, the materials used for carbonaceous fillers include at least one of metallurgical coke, calcined petroleum coke, and graphite.

[0135] In this embodiment, the carbonaceous filler material has many available types, which can provide many possible implementation methods, thereby facilitating the promotion and application of the technical solution of this application.

[0136] It should be noted that after the carbonaceous filler is filled, the complete filling process also includes the process of backfilling the deep well 20 with original soil and gravel in sequence. The specific backfilling standard can be adjusted according to actual needs. For example, the standard for backfilling original soil is to stop when the top of the original soil is 8m away from the wellhead of the deep well 20, and the standard for backfilling gravel is to stop when the top of the gravel is 10cm away from the wellhead of the deep well 20.

[0137] S4 is equipped with a protective cover 24, which surrounds the top of the deep well 20 to seal the deep well 20. One end of the exhaust pipe 22 extends to and passes through the protective cover 24 for exhaust. (For better understanding of the technical solution, a structural diagram of the corresponding area of ​​the protective cover 24 is provided here for further explanation. Please refer to the diagram for details.) Figure 6 ).

[0138] In this embodiment, the installation of the protective cover 24 can better protect the functional components such as the anode group 21, anode cable 23 and exhaust pipe 22 inside the deep well 20, especially under extreme weather conditions such as high temperature or heavy rain, so as to protect the underground well 10 for a long time and stably, thereby improving the corrosion resistance effect.

[0139] It should be noted that the specific form of the shield 24 is not limited and can be set according to the conventional choices in this field.

[0140] As an example, the material of the protective cover 24 is concrete, and the bottom of the protective cover 24 extends below the ground. The dimension of the protective cover 24 below the ground is not limited, for example, it can be 0.5m.

[0141] As an example, the top of the shield 24 extends 0.5m above the ground.

[0142] As an example, the top of the cover 24 has a removable concrete cover plate.

[0143] In this embodiment, the top of the protective cover 24 is designed to be detachable, which facilitates the inspection or replacement of the various functional components inside.

[0144] It should be noted that the installation of the protective cover 24 also involves many aspects such as the installation of the anode junction box 25, the routing of the anode cable 23, and the laying of the exhaust pipe 22. Considering the rationality of the layout, the setting of the corresponding functional devices in this area can be optimized.

[0145] As an example, the inner wall of the shield 24 is equipped with an anode junction box 25, and the exhaust pipe 22 includes a vertically extending exhaust main pipe 22a and a first branch pipe 22b and a second branch pipe 22c located at the top of the deep well 20. The anode cable 23 extends sequentially through the exhaust main pipe 22a and the first branch pipe 22b to the anode junction box 25 and is connected to the main cable 26. The second branch pipe 22c penetrates the side wall of the shield 24.

[0146] In this embodiment, the anode junction box 25 is installed on the inner wall of the protective cover 24. Correspondingly, the connection points of the anode cable 23 and the main cable 26 are also located inside the protective cover 24, which can reduce the adverse effects of the external environment on the corresponding functional components and thus reduce the failure rate of the process equipment. At the same time, the exhaust pipe 22 is set in the form of a main exhaust pipe 22a and two branch pipes, which has the advantages of reasonable layout and easy installation.

[0147] As an example, the first branch pipe 22b and the second branch pipe 22c extend in opposite directions.

[0148] In this embodiment, the two branch pipes are further arranged in opposite directions so that the electrical connection area and the exhaust area are far apart, thereby making it less likely for interference to occur between different functional areas.

[0149] S5 connects and energizes the anode group 21 and the underground well shaft 10 via a cable, so that the anode group 21 and the underground well shaft 10 form a current loop (for better understanding of the technical solution, a schematic diagram of the structure after the anode group 21 and the underground well shaft 10 are connected is provided here for further explanation; please refer to [link to relevant documentation]). Figure 7 It should be noted that a constant potential instrument is also installed on the main cable 26 to act as a power source. The specifications of the constant potential instrument are not limited and can be adjusted according to actual needs, for example, a constant potential instrument with specifications of (40V / 20A).

[0150] In steps S2 and S4, the connection method between the anode cable 23 and the main cable 26 has been illustrated. Accordingly, a cathode cable 17 also needs to be set. Specifically, one end of the cathode cable 17 is connected to the main cable 26, and the other end is connected to the underground well shaft 10.

[0151] It should be noted that, considering the ease of installation of the cathode cable 17, the installation method of the underground shaft 10 can be optimized.

[0152] As an example, the top of the underground shaft 10 extends above the ground.

[0153] As an example, the top of the underground shaft 10 extends 0.5 to 1.2 meters above the ground.

[0154] In this embodiment, the top of the underground shaft 10 extends above the ground, facilitating the installation of the cathode cable 17 and the corresponding encapsulation devices.

[0155] It should be noted that for processes in steps S1 to S5 that are not specifically described or limited, they can be set according to the conventional selection in this field.

[0156] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A method for corrosion protection of underground well casings, wherein the underground well casing is made of carbon steel, characterized in that, Includes the following steps: Deep wells are excavated, with the deep wells and underground well shafts distributed at intervals; An anode assembly and an exhaust pipe are installed in the deep well; Carbonaceous filler is filled into the deep well until the area in the deep well corresponding to the anode group is completely filled. The anode group and the underground well are connected by a cable and energized to form a current loop.

2. The corrosion prevention method for underground well shafts according to claim 1, characterized in that, The cable includes an anode cable, a cathode cable, and a main cable. One end of the cathode cable is connected to the main cable, and the other end is connected to the underground well. The anode assembly is fixedly connected to the outer peripheral wall of the exhaust pipe. One end of the anode cable is connected to the anode assembly, and the anode cable passes through the exhaust pipe with its other end connected to the main cable.

3. The corrosion prevention method for underground well shafts according to claim 2, characterized in that, After the carbonaceous filler is filled and before the cable is energized, the procedure includes installing a protective cover that surrounds the top of the well to seal it, and one end of the exhaust pipe extends to and through the protective cover for venting.

4. The corrosion prevention method for underground well shafts according to claim 3, characterized in that, An anode junction box is installed on the inner wall of the protective cover. The exhaust pipe includes a vertically extending main exhaust pipe and a first branch pipe and a second branch pipe located at the top of the deep well. The anode cable extends sequentially through the main exhaust pipe and the first branch pipe to the anode junction box and connects with the main cable. The second branch pipe penetrates the side wall of the protective cover. Optionally, the first branch pipe and the second branch pipe extend in opposite directions.

5. The corrosion prevention method for underground well shafts according to claim 1, characterized in that, The top of the underground shaft extends above the ground level; Optionally, the top of the underground well extends 0.5 to 1.2 meters above the ground surface; Optionally, at least three anode groups are provided, and the plurality of anode groups are distributed at vertical intervals; Optionally, the anode material of the anode group includes at least one of zinc, aluminum, titanium, high-silicon cast iron, magnesium alloy and noble metal oxide; Optionally, the carbonaceous filler material includes at least one of metallurgical coke, calcined petroleum coke, and graphite.

6. The corrosion prevention method for underground well casings according to any one of claims 1 to 5, characterized in that, The wall thickness of the underground well is 12-30 mm.

7. The corrosion prevention method for underground well casings according to any one of claims 1 to 5, characterized in that, The outer wall of the underground well is also provided with an anti-corrosion layer; Optionally, the material of the anti-corrosion layer includes at least one of epoxy coal tar pitch, thick-film epoxy, and extruded polyethylene; Optionally, the thickness of the anti-corrosion layer is ≥2mm.

8. The corrosion prevention method for underground well shafts according to claim 7, characterized in that, The outer periphery of the anti-corrosion layer is also provided with a concrete solidification layer. Optionally, the thickness of the concrete solidification layer is ≥100mm.

9. The corrosion prevention method for underground well casings according to any one of claims 1 to 5, characterized in that, The underground shaft is equipped with process equipment, and the inner peripheral wall of the underground shaft is provided with a transition piece to separate the inner peripheral wall of the underground shaft from the outer peripheral wall of the process equipment. Optionally, the transition piece is made of plastic, nylon, or insulating bakelite; Optionally, multiple transition members are provided, and the multiple transition members are distributed at vertical intervals; Optionally, the transition member extends circumferentially along the underground shaft and is connected end to end; Optionally, the thickness of the transition member is 10 to 30 mm.

10. The corrosion prevention method for underground well shafts according to claim 9, characterized in that, After the process equipment is installed and sealed inside the underground well, the process also includes a step of evacuating the inside of the underground well. Optionally, the vacuuming step continues until the internal vacuum level of the underground well is 0.01 to 1 Pa.

11. The corrosion prevention method for underground well casings according to claim 9, characterized in that, The top of the underground shaft is provided with a first flange, and the top of the process equipment is provided with a second flange corresponding to the first flange, and an anti-corrosion flange gasket is also provided between the first flange and the second flange. Optionally, both the mating surfaces of the first flange and the second flange are provided with a rust-proof layer.

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