Shaft protection device
By burying a combination of sacrificial anodes and reference electrodes around the outer periphery of the wellbore, and utilizing the principle of galvanic cells and potential monitoring, the corrosion problem caused by corrosive media in the wellbore within the salt cavern gas storage facility was solved, achieving a stable and economical anti-corrosion effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- PIPECHINA SOUTH CHINA CO
- Filing Date
- 2025-05-21
- Publication Date
- 2026-04-21
AI Technical Summary
In existing technologies, wellbore corrosion in salt cavern gas storage facilities is caused by corrosive media. Coating protection is easily worn, corrosion inhibitors are unstable, increasing extraction costs and making long-term effective corrosion prevention difficult.
Multiple sacrificial anodes are buried around the outer perimeter of the wellbore and connected to the wellbore via cables to form a closed loop. The sacrificial anodes are preferentially corroded using the principle of a galvanic cell, providing electrons to the wellbore to prevent corrosion. The potential is monitored by a reference electrode, and the protection measures are adjusted in real time.
It achieves stable corrosion protection for the wellbore, avoids coating wear and insufficient corrosion inhibitors, reduces mining costs, improves the adaptability and practicality of corrosion protection, and ensures long-term protection.
Smart Images
Figure CN224148179U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of pipeline corrosion protection technology, and in particular to a well shaft protection device. Background Technology
[0002] During the construction of salt cavern gas storage facilities, the wellbore is typically located in a complex and harsh underground environment containing various corrosive substances, such as formation water with high levels of chlorides, sulfates, and other salts, as well as corrosive gases like carbon dioxide and hydrogen sulfide generated during extraction. The long-term contact of these corrosive media with the wellbore makes it highly susceptible to corrosion.
[0003] In conventional techniques, a common method to prevent wellbore corrosion is to use coating protection technology, which involves applying an anti-corrosion coating to the inner wall of the wellbore to isolate it from corrosive media. Another method is to add corrosion inhibitors, injecting them into the environment surrounding the wellbore to slow down the chemical reaction rate between the wellbore metal and the corrosive media.
[0004] However, conventional corrosion prevention methods are prone to wear and peeling of coatings due to prolonged mining time and complex physical processes inside the wellbore, such as fluid erosion, temperature and pressure changes. Once the coating is damaged, corrosive media will directly contact the wellbore, accelerating the corrosion process. While adding corrosion inhibitors can slow down corrosion to some extent, it requires continuous addition, which not only increases mining costs but also makes it difficult to guarantee stable and long-term corrosion protection due to the complex and variable environment downhole. Utility Model Content
[0005] The purpose of this utility model is to provide a well casing protection device to solve the technical problem of poor well casing corrosion protection in the prior art.
[0006] Based on the above concept, the technical solution adopted by this utility model is as follows:
[0007] This utility model provides a well casing protection device, applied to the main body of a well casing, which is buried underground. Specifically, the well casing protection device includes:
[0008] Multiple sacrificial anodes are buried on the outer periphery of the well body. Along the height direction of the well body, the sacrificial anodes are arranged in at least two layers, and each layer has multiple sacrificial anodes arranged at intervals along the circumference of the well body. The multiple sacrificial anodes are connected by a cable, and the cable is connected to the well body.
[0009] The testing assembly includes a test pile and a reference electrode. The reference electrode is embedded in the outer periphery of the well body to provide a potential reference value. The test pile is connected to the well body, the sacrificial anode, and the reference electrode respectively. The test pile is used to collect the actual potential value of the well body and determine the potential status of the well body based on the potential reference value.
[0010] Preferably, the sacrificial anodes are arranged in two layers along the height direction of the well body, with four sacrificial anodes in each layer. The included angle between two adjacent sacrificial anodes is 90 degrees. The multiple sacrificial anodes in different layers correspond one-to-one, and the corresponding sacrificial anodes are arranged coaxially.
[0011] Preferably, the wellbore protection device further includes an anode marker post, wherein multiple sacrificial anodes along the same axis share one anode marker post, and the anode marker post is coaxially arranged with the corresponding sacrificial anode and located on the ground.
[0012] Preferably, four test components are provided, with multiple sacrificial anodes along the same axis sharing one test component.
[0013] Preferably, the spacing between two adjacent sacrificial anodes is greater than or equal to 2m and less than or equal to 5m.
[0014] Preferably, the test assembly further includes a reference tube, and the reference electrode is disposed inside the reference tube.
[0015] Preferably, the sacrificial anode is one of rod-shaped, column-shaped, or strip-shaped, and the axis of the sacrificial anode is buried underground perpendicular to the ground.
[0016] Preferably, the sacrificial anode is a zinc-magnesium electrode, with the inner layer of the sacrificial anode being a zinc anode and the outer layer being a magnesium anode along the radial direction of the sacrificial anode.
[0017] Preferably, the test pile has a nameplate on top, a junction box in the middle, an insulating protective shell on the outside of the junction box, and a fixed base at the bottom; the junction box has several terminals, which are connected to the sacrificial anode, the reference electrode and the well body respectively through wires.
[0018] Preferably, the wire is welded to the well body, and a portion of the wire at the weld point is fixed to the well body.
[0019] The beneficial effects of this utility model are:
[0020] This invention proposes a well casing protection device that embeds multiple sacrificial anodes around the outer periphery of the well casing and connects them to the casing via cables. Utilizing the principle of a galvanic cell, the sacrificial anodes and the casing form a closed circuit through the cables. The sacrificial anodes are typically made of a more reactive metal than the casing metal. In the underground electrolyte environment, the reactive metal more easily loses electrons and undergoes an oxidation reaction, causing the sacrificial anode to continuously corrode and dissolve. Electrons flow through the cables to the casing, which then acts as the cathode. Oxidizing substances in the solution gain electrons on the surface of the casing and undergo a reduction reaction, preventing the casing from losing electrons and corroding due to the inflow of electrons. This protects the casing from corrosion. Furthermore, at least two layers of sacrificial anodes are spaced vertically around the casing, with multiple anodes evenly distributed around the casing in each layer, forming a three-dimensional arrangement that protects all parts of the casing and avoids blind spots. Meanwhile, the layered and zoned sacrificial anode layout can specifically enhance the protective current density in corresponding areas based on the concentration gradient differences of corrosive media at different locations and depths, thereby improving the adaptability and practicality of the sacrificial anodes. Simultaneously, reference electrodes buried around the wellbore continuously measure the baseline potential of the soil environment. By comparing the actual potential of the wellbore with the baseline value, the test pile can determine whether the sacrificial anode is being consumed normally. If the actual potential of the wellbore is within a reasonable protection potential range, it indicates that the sacrificial anode is providing good protection for the wellbore; if it deviates from this range, it may indicate excessive consumption of the sacrificial anode, abnormal cable connections, or other problems, allowing for timely intervention to maintain effective protection of the wellbore. In summary, this wellbore protection device, based on the principle of a galvanic cell, preferentially corrodes itself to provide electrons to the wellbore to prevent corrosion. Simultaneously, the test components utilize the stable potential of the reference electrode as a reference, enabling the test pile to monitor the potential of the wellbore in real time, ensuring that the device always effectively protects the wellbore. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the structure of the wellbore protection device provided in this embodiment of the utility model;
[0022] Figure 2 This is a top view of the well shaft protection device provided in this embodiment of the utility model.
[0023] In the picture:
[0024] 100. Well body; 1. Sacrificial anode; 2. Cable; 3. Test assembly; 31. Test stake; 311. Nameplate; 312. Junction box; 313. Fixed base; 32. Reference electrode; 33. Reference tube; 4. Wire; 5. Anode marker stake. Detailed Implementation
[0025] The embodiments of this utility model are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this utility model, and should not be construed as limiting this utility model.
[0026] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.
[0027] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.
[0028] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.
[0029] This utility model provides a well casing protection device, which is applied to the well casing body buried underground. The device can effectively prevent underground corrosive media from corroding the well casing body.
[0030] See Figure 1 and Figure 2The wellbore protection device provided in this embodiment includes a sacrificial anode 1 and a testing component 3. Multiple sacrificial anodes 1 are embedded in the outer periphery of the wellbore body 100. Along the height direction of the wellbore body 100, at least two layers of sacrificial anodes 1 are arranged, with multiple sacrificial anodes 1 spaced apart in each layer along the circumference of the wellbore body 100. The multiple sacrificial anodes 1 are connected by cables 2, which are connected to the wellbore body 100. The testing component 3 includes a test post 31 and a reference electrode 32. The reference electrode 32 is embedded in the outer periphery of the wellbore body 100 to provide a potential reference value. The test post 31 is connected to the wellbore body 100, the sacrificial anodes 1, and the reference electrode 32, respectively. The test post 31 is used to collect the actual potential value of the wellbore body 100 and determine the potential status of the wellbore body 100 based on the potential reference value.
[0031] The well casing protection device proposed in this utility model involves embedding multiple sacrificial anodes 1 around the outer periphery of the well casing body 100 and connecting the sacrificial anodes 1 to the well casing body 100 via cables 2. Utilizing the principle of a galvanic cell, the sacrificial anodes 1 and the well casing body 100 form a closed circuit through the cables 2. The sacrificial anodes 1 are typically made of a more reactive metal than the metal of the well casing body 100. In the underground electrolyte environment, the reactive metal more easily loses electrons and undergoes an oxidation reaction, causing the sacrificial anodes 1 to be continuously corroded and dissolved. Meanwhile, electrons flow through the cables 2 to the well casing body 100, which then acts as the cathode. Oxidizing substances in the solution gain electrons on the surface of the well casing body 100 and undergo a reduction reaction. This prevents the well casing body 100 from losing electrons and corroding due to the inflow of electrons, thereby protecting the well casing body 100 and preventing corrosion. Furthermore, at least two layers of sacrificial anodes 1 are spaced vertically around the well casing, with multiple sacrificial anodes 1 evenly distributed around the well casing in each layer, forming a three-dimensional arrangement of upper and lower layers and dispersed around the perimeter. This arrangement can protect all parts of the well casing 100 and avoid protection blind spots. Simultaneously, the layered and zoned layout of the sacrificial anodes 1 can specifically enhance the protective current density in corresponding areas based on the concentration gradient differences of corrosive media at different locations and depths, improving the adaptability and practicality of the sacrificial anodes 1. Meanwhile, the reference electrode 32 buried around the well casing 100 continuously measures the reference potential of the soil environment. By comparing the actual potential of the well casing 100 with the reference value, the test pile 31 can determine whether the sacrificial anodes 1 are being consumed normally. If the actual potential of the well casing 100 is within a reasonable protection potential range, it indicates that the sacrificial anodes 1 are providing good protection for the well casing 100; if it deviates from this range, it may indicate excessive consumption of the sacrificial anodes 1, abnormal cable 2 connections, or other problems, allowing for timely implementation of appropriate measures to maintain effective protection of the well casing 100. In summary, this well casing protection device is based on the principle of a galvanic cell, which preferentially corrodes itself to provide electrons to the well casing body 100 to prevent its corrosion. At the same time, the test component 3 uses the stable potential of the reference electrode 32 as a reference, so that the test pile 31 can monitor the potential of the well casing body 100 in real time, ensuring that the device always effectively protects the well casing body 100.
[0032] The specific structure and working principle of the wellbore protection device are described below.
[0033] The sacrificial anode 1 protects the wellbore body 100 through the principle of a galvanic cell. In this embodiment, the sacrificial anode 1 is a zinc-magnesium electrode. Along the radial direction of the sacrificial anode 1, the inner layer is a zinc anode, and the outer layer is a magnesium anode. The zinc anode layer has stable self-corrosion characteristics and can provide a continuous basic protective current in neutral and weakly alkaline environments. The outer magnesium anode layer corrodes preferentially due to its higher electrochemical activity, quickly establishing a strong polarized electric field in the early stage, rapidly inhibiting the electrochemical corrosion reaction on the surface of the wellbore body 100. Through the layered design, the outer magnesium anode is consumed first to cope with the high corrosion risk period, while the inner zinc anode continues to play a role after the magnesium layer is depleted, forming a staged protection mechanism and extending the overall service life of the sacrificial anode 1.
[0034] Preferably, the outer layer of the magnesium anode is provided with a honeycomb etched structure, which can increase the reaction surface area and improve the initial corrosion rate.
[0035] It is worth noting that the sacrificial anode 1 should be thoroughly moistened with water before being buried underground. A moist environment can accelerate the movement of ions, reduce the resistance of the solution, and enable the sacrificial anode 1 to release electrons more quickly and efficiently. This allows the soil or electrolyte environment around the sacrificial anode 1 to reach a good conductivity state more quickly, so that the well body 100 can be protected more quickly.
[0036] In other embodiments, the sacrificial anode 1 can also be an aluminum alloy anode or a pure zinc anode, etc. The material is not limited here, as long as the above functions can be achieved.
[0037] Preferably, the sacrificial anode 1 is a rod, column, or strip shape. The axis of the sacrificial anode 1 is buried underground perpendicular to the ground surface. When buried vertically, the axis of the sacrificial anode 1 aligns with the direction of gravity, allowing for close contact between the sacrificial anode 1 and the surrounding soil. This reduces gaps caused by soil settlement and ensures uniform penetration of corrosive media (such as formation water) along the surface of the sacrificial anode 1. In this embodiment, the sacrificial anode 1 is rod-shaped. The rod-shaped structure provides a larger surface area with the same material usage, accelerating the anode reaction rate and thus increasing the protective current output per unit volume. In other embodiments, the sacrificial anode 1 can also be adapted to be strip-shaped or columnar.
[0038] Preferably, the bottom of the sacrificial anode 1 slopes outward from top to bottom to form an expanded diameter section, thereby improving the pull-out strength and enhancing the stability of the sacrificial anode 1.
[0039] Two layers of sacrificial anodes 1 are arranged along the height of the well body 100, ensuring more effective protection for all areas of the well body 100 from shallow to deep, thus increasing the vertical protection coverage of the well body 100. Each layer contains four sacrificial anodes 1, with a 90-degree angle between adjacent anodes 1. This ensures that all parts of the well body 100 receive electrons uniformly from the sacrificial anodes 1 in the circumferential direction, preventing insufficient protection in certain areas due to distance from the sacrificial anodes 1, and effectively improving the uniformity of corrosion protection in the circumferential direction of the well body. The multiple sacrificial anodes 1 in different layers correspond one-to-one, and the corresponding sacrificial anodes 1 are coaxially arranged. This orderly correspondence facilitates the installation and maintenance of the sacrificial anodes 1. Operators can more clearly locate the position of each sacrificial anode 1 during installation, and during subsequent maintenance, if inspection or replacement of a specific sacrificial anode 1 is required, the corresponding component can be found more easily, improving the efficiency of maintenance work.
[0040] Furthermore, the wellbore protection device also includes an anode marker post 5. Multiple sacrificial anodes 1 along the same axis share one anode marker post 5, improving resource and space utilization and avoiding the need to set up a separate anode marker post 5 for each sacrificial anode 1, thus saving material costs and installation space. The anode marker post 5 is coaxially set with the corresponding sacrificial anode 1 and located on the ground, thereby effectively serving as a positioning and warning device. This facilitates operators in quickly and accurately locating the underground sacrificial anode 1 during installation and maintenance, and also alerts unrelated personnel in the vicinity, preventing them from unknowingly engaging in excavation, construction, or other activities that could damage the sacrificial anode 1.
[0041] Among them, the anode marker post 5 can be a post body, sign, etc., and its specific form is not limited here, as long as it can achieve the purpose of marking and warning.
[0042] Preferably, the spacing between two adjacent sacrificial anodes 1 is greater than or equal to 2m and less than or equal to 5m. This prevents uneven current distribution due to excessively small spacing, resulting in over-protection in some areas and under-protection in others. It also prevents excessively large spacing, which would increase the amount of sacrificial anodes 1 used, raising material costs, and potentially creating a weak protection area in the well body 100 between the two sacrificial anodes 1. In this embodiment, the distance between the upper sacrificial anode 1 and the ground is 2m, the distance between the lower sacrificial anode 1 and the ground is 5m, and the spacing between the two sacrificial anodes 1 is 3m.
[0043] Preferably, the distance between the sacrificial anode 1 and the well body 100 is greater than or equal to 5m.
[0044] The specific spacing parameters between two adjacent sacrificial anodes 1 need to be adjusted according to the actual situation. If there are three or more sacrificial anodes 1, the spacing between different layers of sacrificial anodes 1 can be the same or different, and there is no limitation here.
[0045] The test component 3 uses the test pile 31 and the reference electrode 32 to determine the potential status of the well body 100 by using the actual potential value of the well body 100 and the potential reference value of the reference electrode 32.
[0046] In this embodiment, four test components 3 are provided, with multiple sacrificial anodes 1 along the same axis sharing one test component 3. This allows for the determination of the potential status of relevant areas based on the same set of reference standards. This makes the actual potential value of the wellbore body 100 and the potential status determination based on the reference electrode 32 more consistent and comparable, facilitating accurate analysis of the protection status of specific areas of the wellbore body 100. Furthermore, this design avoids the circuit complexity associated with setting up a separate test component 3 for each sacrificial anode 1. When maintenance, calibration, or troubleshooting of the test component 3 is required, technicians can more clearly locate and handle problems.
[0047] The reference electrode 32 is embedded in the outer periphery of the well body 100 to provide a potential reference value. Specifically, the test assembly 3 also includes a reference tube 33, in which the reference electrode 32 is disposed. The reference tube 33 prevents the reference electrode 32 from directly contacting various corrosive substances and soil particles in the underground environment, avoiding physical damage or chemical corrosion to the reference electrode 32, thereby extending its service life and ensuring that it can provide an accurate potential reference value stably for a long time, thus guaranteeing the reliability of the potential measurement function of the test assembly 3.
[0048] Specifically, the test pile 31 has a nameplate 311 on its top, which facilitates quick identification of the test pile 31's purpose, area, relevant parameters, and other key information by staff, improving work efficiency. A junction box 312 is located in the middle of the test pile 31, and an insulating protective shell is provided outside the junction box 312 to prevent it from getting damp or corroded, and to avoid electrical faults such as short circuits or leakage affecting the normal operation of the test pile 31. A fixed base 313 is located at the bottom of the test pile 31, providing stable support. The junction box 312 contains several terminals, which are connected to the sacrificial anode 1, the reference electrode 32, and the well body 100 via wires 4, respectively, preventing signal crosstalk between different circuits. The terminals adopt a standardized interface design, allowing connection to the test pile 31 through the reserved socket without disassembling the junction box 312.
[0049] Preferably, the conductor 4 is welded to the well body 100, which ensures good electrical contact between the conductor 4 and the well body 100 and reduces contact resistance. In this embodiment, both the cable 2 and the conductor 4 are copper core wires.
[0050] Furthermore, in the complex underground environment where the main shaft 100 is located, various dynamic forces exist, such as ground movement and fluid impact. If the conductor 4 is only connected to the main shaft 100 by welding, the weld may break due to fatigue under long-term external forces. Therefore, a portion of the conductor 4 at the weld is fixed to the main shaft 100, which can disperse external forces, prevent the weld from bearing excessive stress alone, and reduce the risk of loosening or breakage at the connection between the conductor 4 and the main shaft 100.
[0051] The above embodiments merely illustrate the basic principles and characteristics of this utility model. This utility model is not limited to the above embodiments. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.
Claims
1. A wellbore protection device applied to a wellbore body (100) that is buried in the ground, characterized by, The wellbore protection device includes: Multiple sacrificial anodes (1) are buried on the outer periphery of the well body (100). Along the height direction of the well body (100), the sacrificial anodes (1) are arranged in at least two layers, and each layer is provided with multiple sacrificial anodes (1) arranged at intervals along the circumference of the well body (100). The multiple sacrificial anodes (1) are connected by cables (2), and the cables (2) are connected to the well body (100). The test component (3) includes a test pile (31) and a reference electrode (32). The reference electrode (32) is embedded in the outer periphery of the well body (100) to provide a potential reference value. The test pile (31) is connected to the well body (100), the sacrificial anode (1), and the reference electrode (32) respectively. The test pile (31) is used to collect the actual potential value of the well body (100) and determine the potential status of the well body (100) based on the potential reference value.
2. The wellbore protector of claim 1, wherein, The sacrificial anode (1) is arranged in two layers along the height direction of the well body (100), with four sacrificial anodes (1) in each layer. The included angle between two adjacent sacrificial anodes (1) is 90 degrees. Multiple sacrificial anodes (1) in different layers correspond one-to-one, and the corresponding sacrificial anodes (1) are arranged coaxially.
3. The wellbore protector of claim 2, wherein, The well protection device also includes an anode marker post (5). Multiple sacrificial anodes (1) along the same axis share one anode marker post (5). The anode marker post (5) is coaxially arranged with the corresponding sacrificial anode (1) and located on the ground.
4. The wellbore protector of claim 2, wherein, The test assembly (3) is provided in four parts, and multiple sacrificial anodes (1) along the same axis share one test assembly (3).
5. The wellbore protector of claim 1, wherein, The spacing between two adjacent sacrificial anodes (1) is greater than or equal to 2m and less than or equal to 5m.
6. The wellbore protector of claim 1, wherein, The test assembly (3) also includes a reference tube (33), and the reference electrode (32) is disposed inside the reference tube (33).
7. The wellbore protector of any one of claims 1-6, wherein, The sacrificial anode (1) is one of rod, column or strip, and the axis of the sacrificial anode (1) is buried underground perpendicular to the ground.
8. The shaft protection device according to any one of claims 1-6, characterized in that, The sacrificial anode (1) is a zinc-magnesium electrode. Along the radial direction of the sacrificial anode (1), the inner layer of the sacrificial anode (1) is a zinc anode, and the outer layer of the sacrificial anode (1) is a magnesium anode.
9. The shaft protection device according to any one of claims 1-6, characterized in that, The test pile (31) has a nameplate (311) on top, a junction box (312) in the middle, an insulating protective shell on the outside of the junction box (312), and a fixed base (313) at the bottom of the test pile (31). The junction box (312) has several terminals, which are connected to the sacrificial anode (1), the reference electrode (32) and the well body (100) respectively through wires (4).
10. The wellbore protector of claim 9, wherein, The wire (4) is welded to the well body (100), and part of the wire (4) at the weld point is fixed to the well body (100).