An auxiliary anode device for a cluster well group cathodic protection system

Abstract

The present invention provides an auxiliary anode device for a cluster well group cathodic protection system, comprising an external connection steel wire cable, a suspension and lowering connection rainbow, a metal shell, an auxiliary anode internal parallel cable, a single anode cable, a filler and a single anode; the suspension and lowering connection rainbow is arranged at the upper end of the metal shell, and the single anode is multiple and arranged in parallel in the metal shell; each single anode is connected to the auxiliary anode internal parallel cable through the corresponding single anode cable; the upper end of the external connection steel wire cable is located outside the suspension and lowering connection rainbow, and the lower end passes through the suspension and lowering connection rainbow and is connected to the upper end of the auxiliary anode internal parallel cable in the metal shell; the filler is filled in the metal shell. The device is easy to transport and simple to install. When put into production, it can effectively reduce the grounding resistance of the single anode, thereby achieving the purpose of increasing its life and reducing system energy consumption.

Description

Technical Field

[0001] The invention belongs to the field of cathodic protection, and in particular relates to an auxiliary anode device of a cluster well group cathodic protection system. Background Art

[0002] Cathodic protection includes impressed current cathodic protection and sacrificial anode cathodic protection. The impressed current cathodic protection system generally consists of an external DC power supply, auxiliary anode, reference electrode and connecting cable. 60% of the power of the entire protection system is consumed in the auxiliary anode grounding resistance. Therefore, how to reduce the grounding resistance of the auxiliary anode becomes the key to affecting the service life and energy saving of the impressed current cathodic protection system.

[0003] Existing impressed current cathodic protection is mainly used for urban pipe networks and ground pipeline cathodic protection. Cathodic protection of casing in oil and gas field systems is rarely used. The cathodic protection system of cluster wells in oil and gas fields is aimed at protecting casing 200-1500m underground, and its anode bed is generally 100-300m deep underground. The system of the present invention is mainly designed for the cathodic protection system of cluster wells.

[0004] Among the existing anode patents, there are many patents on sacrificial anodes, such as patent number ZL03211028.6 (buried steel pipeline bracelet anode), which is a sacrificial anode for protecting steel pipes buried in oil fields from corrosion. Patent number ZL201020175853.6 (casing anti-corrosion multi-point grounding sacrificial anode device), which is a sacrificial anode for protecting oilfield casing. Patent number ZL201220591945.1 (sacrificial anode device for controlling corrosion in storage tanks), is a sacrificial anode device for preventing corrosion in storage tanks.

[0005] There are few patents on auxiliary anodes for impressed current cathodic protection, only patent number ZL20179504.6 (non-uniform diameter buried anode), which is a shallow auxiliary buried anode for protecting buried pipelines by impressed current cathodic protection. There is no 100-300m deep buried auxiliary anode used in casing cathodic protection.

[0006] Therefore, it is necessary to carry out research on the auxiliary anode of the cathodic protection system of cluster wells in oil and gas fields to reduce the grounding resistance of the auxiliary anode and achieve the dual effects of increasing the service life of the cathodic protection system and saving energy. Summary of the invention

[0007] In order to overcome the existing problems of short service life and low energy conservation, the present invention provides an auxiliary anode device for a cluster well group cathodic protection system. The present invention can effectively reduce the grounding resistance of the auxiliary anode by installing the auxiliary anode (single anode) in a metal shell and adding filler in the metal shell, thereby achieving the purpose of increasing its service life and reducing system energy consumption.

[0008] The technical solution adopted by the present invention is:

[0009] An auxiliary anode device of a cluster well group cathodic protection system comprises an external connecting steel wire cable, a suspended and lowered connecting rainbow, a metal shell, an auxiliary anode internal parallel cable, a single anode cable, a filler and a single anode; the suspended and lowered connecting structure is arranged at the upper end of the metal shell, and the single anode is multiple and arranged in parallel in the metal shell; each single anode is connected to the auxiliary anode internal parallel cable through a corresponding single anode cable; the upper end of the external connecting steel wire cable is located outside the suspended and lowered connecting structure, and the lower end passes through the suspended and lowered connecting structure and is connected to the upper end of the auxiliary anode internal parallel cable in the metal shell; a baffle is provided on the upper inner part of the metal shell, and the filler is filled in the metal shell at the lower end of the baffle; the metal shell at the upper end of the baffle is filled with a resistance reducing agent; the single anode is located in the metal shell below the baffle.

[0010] The hanging and lowering connection structure is welded to the upper end of the metal shell.

[0011] The hanging and lowering connection structure is a hanging and lowering connection rainbow or a conversion joint.

[0012] The plurality of single anodes are evenly distributed from top to bottom along the central axis of the metal shell.

[0013] The single anode is a combination of one or more of a high silicon cast iron anode, a noble metal oxide anode, a graphite anode and a platinum anode.

[0014] The filler comprises coke particles and inorganic salts, and the mass ratio of the coke particles to the inorganic salts is 1:1-2.

[0015] The coke particles are spherical and have a particle size ranging from 2 mm to 5 mm.

[0016] The inorganic salt comprises sodium chloride and potassium chloride, and the weight ratio of sodium chloride to potassium chloride is 1:1-3.

[0017] The wall thickness of the metal shell is at least 5 mm, small holes with a diameter of 1 mm are evenly distributed on the metal shell, and the lower end of the metal shell is a cone.

[0018] The metal shell is made of chromium-nickel stainless steel.

[0019] The beneficial effects of the present invention are:

[0020] The present invention connects a plurality of single anodes in parallel to form an auxiliary anode which is then arranged in a metal shell and fillers are added in the metal shell, which can effectively reduce the grounding resistance of the auxiliary anode, thereby increasing its life and reducing system energy consumption.

[0021] The present invention facilitates the transportation and installation of the auxiliary anode device and can effectively reduce the grounding resistance of the auxiliary anode when put into production, thereby achieving the purpose of increasing its service life and reducing system energy consumption.

[0022] In the present invention, small holes are evenly distributed on the metal shell. Formation water enters the device through the small holes evenly distributed around the metal shell and contacts the filler around the monomer anode. The coke particles in the filler absorb water to reduce the grounding resistance of the monomer anode. At the same time, the inorganic salts NaCl and KCl in the filler dissolve in the formation water, thereby improving the conductivity of the filler and reducing the grounding resistance of the monomer anode.

[0023] In the present invention, the metal shell is made of chromium-nickel stainless steel and has strong corrosion resistance.

[0024] In the present invention, the lower end of the metal shell adopts a parabolic cone, and the whole body is formed by one-time casting, which is convenient for preventing the metal shell from being damaged during subsequent transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the present invention.

[0026] In the figure, the reference numerals are: 1. external connection steel wire cable; 2. hanging and lowering connection structure; 3. metal shell; 4. auxiliary anode internal parallel cable; 5. single anode cable; 6. filler; 7. single anode. DETAILED DESCRIPTION

[0027] Embodiment 1:

[0028] In order to overcome the problems of short service life and low energy saving in the prior art, the present invention provides Figure 1 The auxiliary anode device of a cluster well group cathodic protection system shown in the figure can effectively reduce the grounding resistance of the auxiliary anode by installing the auxiliary anode in a metal shell and adding fillers in the metal shell, thereby achieving the purpose of increasing its service life and reducing system energy consumption.

[0029] An auxiliary anode device of a cluster well group cathodic protection system comprises an external connecting steel wire cable 1, a hanging and lowering connecting structure 2, a metal shell 3, an auxiliary anode internal parallel cable 4, a single anode cable 5, a filler 6 and a single anode 7; the hanging and lowering connecting structure 2 is arranged at the upper end of the metal shell 3, and the single anode 7 is multiple and arranged in parallel in the metal shell 3; each single anode 7 is connected to the auxiliary anode internal parallel cable 4 through the corresponding single anode cable 5; the upper end of the external connecting steel wire cable 1 is located outside the hanging and lowering connecting structure 2, and the lower end passes through the hanging and lowering connecting structure 2 and is connected to the upper end of the auxiliary anode internal parallel cable 4 in the metal shell 3; a baffle is provided in the upper part of the metal shell 3, and the filler 6 is filled in the metal shell 3 at the lower end of the baffle; the metal shell 3 at the upper end of the baffle is filled with a resistance reducing agent; the single anode 7 is located in the metal shell 3 below the baffle.

[0030] In the present invention, the resistance reducing agent is NaSO4, the place where the resistance reducing agent is filled is a closed space, and the baffle is preferably a soluble magnesium-aluminum alloy isolation plate. The present invention facilitates the transportation and installation of the auxiliary anode, and can effectively reduce the grounding resistance of the auxiliary anode when put into production, thereby achieving the purpose of increasing its life and reducing system energy consumption.

[0031] When the auxiliary anode device provided by the present invention is buried in the ground bed, the formation water enters the cavity through the holes on the metal shell 3 and contacts the filler 6 and the magnesium-aluminum alloy isolation plate (baffle). The inorganic salt in the filler 3 dissolves to reduce the auxiliary anode grounding resistance. After the magnesium-aluminum alloy isolation plate contacts and dissolves with the formation water, on the one hand, the NaSO4 in the cavity further dissolves to increase the conductivity of the ground bed and reduce the auxiliary anode grounding resistance. On the other hand, the cavity is a closed space, and the gas generated when the auxiliary anode is working can migrate upward and enter the cavity, reducing the effect of gas resistance and further reducing the auxiliary anode grounding resistance.

[0032] like Figure 1 As shown, the present invention connects multiple single anodes 7 in parallel to form an auxiliary anode and then arranges it in the metal shell 3. The present invention facilitates the transportation and installation of the auxiliary anode device. When it is put into production, it can effectively reduce the grounding resistance of the auxiliary anode, thereby achieving the purpose of increasing its life and reducing system energy consumption. When the present invention is immersed in formation water, the formation water enters the present invention through the small holes evenly distributed around the metal shell 3, contacts the filler 6 around the single anode 7, absorbs water through the filler 6, and reduces the grounding resistance of the single anode 7. At the same time, part of the filler 6 can be dissolved in the formation water, which increases the conductivity of the filler 6 and further reduces the grounding resistance of the single anode 7.

[0033] Embodiment 2:

[0034] Based on Example 1, in this embodiment, preferably, the hanging and lowering connection structure 2 is welded to the upper end of the metal shell 3.

[0035] Preferably, the hanging and lowering connection structure 2 is a hanging and lowering connection rainbow or a conversion joint.

[0036] In the present invention, the hanging and lowering connecting rib is bowl-shaped, and the edge of the bowl-shaped opening is welded to the upper end of the metal shell 3.

[0037] The hanging and lowering connection structure 2 in the present invention facilitates the lowering of the external steel wire cable 1. The hanging and lowering connection structure 2 can also be a conversion joint, which is connected and lowered by a steel pipe thread.

[0038] Preferably, the plurality of single anodes 7 are evenly distributed from top to bottom along the central axis of the metal shell 3 .

[0039] Preferably, the single anode 7 is a combination of one or more of a high silicon cast iron anode, a noble metal oxide anode, a graphite anode and a platinum anode.

[0040] The silicon content in the high silicon cast iron anode in the present invention is 14-16%, preferably 14.5%, 15%, and 15.5% in the present invention. In the present invention, the noble metal oxide anode is preferably an MMO noble metal oxide anode. The single anode 7 in the present invention can be changed to other anodes according to production needs, which will not be described one by one in the present invention. The single anode 7 in the present invention can be a single monomer or a plurality of monomers used in combination, and the number of single anodes 7 is increased or decreased according to the set life and demand. In the present invention, the single anodes 7 are preferably 3, 4, 5, or 6.

[0041] Preferably, the filler 6 comprises coke particles and inorganic salts, and the mass ratio of the coke particles to the inorganic salts is 1:1-2.

[0042] The filler 6 in the present invention will be located below the formation water level when it is put into production and operation in an underground anode bed 100-300m deep, and then the present invention will be immersed in the formation water. The formation water enters the device through the small holes evenly distributed around the metal shell 3 and contacts the filler 6 around the monomer anode 7. The coke particles in the filler 6 will absorb water and reduce the grounding resistance of the monomer anode 7. At the same time, the inorganic salts NaCl and KCl in the filler 6 are dissolved in the formation water, thereby improving the conductivity of the filler 6 and reducing the grounding resistance of the monomer anode 7.

[0043] Preferably, the coke particles are spherical and have a particle size ranging from 2 mm to 5 mm.

[0044] In the present invention, the coke particles are spherical, with a resistivity of <50Ω·cm, a particle size range of 2mm to 5mm, a carbon content of >85%, and a density of >1.7g / cm 3.

[0045] In the present invention, preferably, the inorganic salt includes sodium chloride and potassium chloride, the weight ratio of sodium chloride to potassium chloride is 1:1-3, and the particle size range is less than 2 mm. Other inorganic salts can also be selected according to the anode performance to meet the needs.

[0046] In the present invention, the hanging and lowering connection structure 2 and the metal shell 3 are connected by welding, and the tensile strength of the welding point is greater than twice the weight of the auxiliary anode device.

[0047] Preferably, the wall thickness of the metal shell 3 is at least 5 mm, small holes with a diameter of 1 mm are evenly distributed on the metal shell 3, and the lower end of the metal shell 3 is a cone.

[0048] Preferably, the metal shell 3 is made of chromium-nickel stainless steel.

[0049] In the present invention, the metal shell 3 has a wall thickness of 5 mm, small holes with a diameter of 1 mm are evenly distributed around it, and a parabolic cone is used at the lower end, and the whole body is formed by one-time casting. The present invention facilitates the transportation and installation of the auxiliary anode, and can effectively reduce the grounding resistance of the auxiliary anode when it is put into production, thereby achieving the purpose of increasing its life and reducing system energy consumption.

[0050] The metal shell 3 in the present invention is made of chromium-nickel stainless steel, and can also be changed to other metal materials according to different sound field requirements. The length is determined according to the number of anodes and the length of each anode. The wall thickness is 5mm, and small holes with a diameter of 1mm are evenly distributed around. The lower end adopts a parabolic cone, and the whole body is formed by one-time casting. The present invention is convenient for transportation and installation, and can effectively reduce the grounding resistance of the auxiliary anode when put into production, thereby achieving the purpose of increasing its life and reducing system energy consumption.

[0051] Embodiment 3:

[0052] Based on Example 1 or 2, in this embodiment, there is provided an auxiliary anode device of a cluster well group cathodic protection system consisting of an external connecting steel wire cable 1, a suspended lowering connection structure 2, a metal shell 3, an auxiliary anode internal parallel cable 4, a single anode cable 5, a filler 6 and a single anode 7.

[0053] 1. Select the auxiliary anode device provided by the present invention. In the embodiment, the single anode 7 preferably adopts MMO precious metal oxide anode. According to the effective period of 15 years of the cathodic protection system, 6 single anodes are connected in parallel.

[0054] In this embodiment, the filler 6 is selected from coke particles and inorganic salts in a mass ratio of 1:1. The coke particles are spherical, with a resistivity of 45Ω·cm, a particle size range of 2mm to 5mm, a carbon content of >85%, and a density of >1.7g / cm 3The inorganic salt is composed of NaCl and KCl in a weight ratio of 1:2, and the inorganic salt particle size range is less than 2 mm. The metal shell 3 is made of chromium-nickel stainless steel, with a wall thickness of 5 mm, and small holes with a diameter of 1 mm are evenly distributed around it. The lower end adopts a parabolic cone, and the whole body is cast in one step. In the present invention, a hanging lowering connection structure 2 is provided to facilitate the lowering of the external steel wire cable 1.

[0055] 2. Drilling the anode well adopts a two-opening wellbore structure: first, use a Φ311mm drill bit to drill through the loess layer to 180m (0-30 meters is the loess layer), and then put into this section a steel casing section with a diameter of Φ219mm, a wall thickness of 6mm, and a threaded connection; then use a Φ180mm drill bit to drill to the designed depth of 220m, and then clean the wellbore until the water quality at the inlet and outlet is consistent.

[0056] 3. Use steel wire to connect the hanging and lowering connection structure 2 of the present invention to the external connection steel wire cable 1. The external connection steel wire cable 1 adopts a polyvinyl chloride cable, and the polyvinyl chloride cable is preferably VV32-1Kv-1*16mm 2 , and then the present invention is lowered to the bottom of the well to complete the well.

[0057] Embodiment 4:

[0058] Based on Example 1 or 2, in this embodiment, there is provided an auxiliary anode device of a cluster well group cathodic protection system consisting of an external connecting steel wire cable 1, a suspended lowering connection structure 2, a metal shell 3, an auxiliary anode internal parallel cable 4, a single anode cable 5, a filler 6 and a single anode 7.

[0059] 1. The auxiliary anode device provided by the present invention is selected. In the embodiment, the single anode 7 adopts MMO precious metal oxide anode. According to the calculation of the effective period of the cathodic protection system of 15 years, 6 single anodes are connected in parallel.

[0060] Filler 6, composed of coke particles and inorganic salts, with a mass ratio of 1:1. The coke particles are spherical, with a resistivity of 45Ω·cm, a particle size range of 2mm to 5mm, a carbon content of >85%, and a density of >1.7g / cm 3 The inorganic salt is composed of NaCl and KCl with a weight ratio of 1:2 and a particle size range of less than 2 mm.

[0061] Use a conversion joint and lower the airway.

[0062] 2. Drilling the anode well adopts a two-opening wellbore structure: first, use a Φ311mm drill bit to drill through the loess layer to 180m (0-30 meters is the loess layer), and then put into this section a steel casing section with a diameter of Φ219mm, a wall thickness of 6mm, and a threaded connection; then use a Φ180mm drill bit to drill to the designed depth of 220m, and then clean the wellbore until the water quality at the inlet and outlet is consistent.

[0063] 3. Use steel wire to connect the hanging and lowering connection structure 2 of the present invention to the external connection steel wire cable 1. The external connection steel wire cable 1 is made of polyvinyl chloride cable, preferably VV32-1Kv-1*16mm 2 , and then the present invention is lowered to the bottom of the well to complete the well.

[0064] Embodiment 5:

[0065] Based on Example 1 or 2, in this embodiment, there is provided an auxiliary anode device of a cluster well group cathodic protection system consisting of an external connecting steel wire cable 1, a suspended lowering connection structure 2, a metal shell 3, an auxiliary anode internal parallel cable 4, a single anode cable 5, a filler 6 and a single anode 7.

[0066] 1. Select the auxiliary anode device provided by the present invention,

[0067] (1) In this embodiment, the single anode 7 is a high silicon cast iron anode. Based on the effective period of the cathodic protection system of 15 years, 8 single anodes are connected in parallel.

[0068] (2) Filler 6, composed of coke particles and inorganic salts, with a mass ratio of 1:1. The coke particles are spherical, with a resistivity of 45Ω·cm, a particle size range of 2mm to 5mm, a carbon content of >85%, and a density of >1.7g / cm 3 The inorganic salt is composed of NaCl and KCl with a weight ratio of 1:2 and a particle size range of less than 2 mm.

[0069] (3) The connecting structure 2 is suspended and lowered to facilitate the lowering of the steel wire.

[0070] (4) The metal shell 3 is made of chromium-nickel stainless steel, has a wall thickness of 5 mm, has small holes with a diameter of 1 mm evenly distributed around it, has a parabolic cone at the lower end, and is formed by one-step casting.

[0071] 2. Drilling the anode well adopts an open wellbore structure: first use a Φ311mm drill bit to drill through the loess layer to 250m (0-80 meters is the loess layer), and then clean the wellbore.

[0072] 3. Use the plastic-sprayed steel air guide tube with an outer diameter of 42 and an inner diameter of 32 to connect the conversion joint 2 of the present invention to the external connection steel wire cable 1. The external connection steel wire cable 1 is made of polyvinyl chloride cable, preferably VV32-1Kv-1*16mm 2 , and then lower the device to the bottom of the well to complete the well.

[0073] The present invention can effectively reduce the grounding resistance of the single anode 7 by installing the single anode 7 in the metal shell 3 and optimizing the filler 6 around the anode body, thereby achieving the purpose of increasing its life and reducing system energy consumption. At the same time, the auxiliary anode device provided by the present invention is convenient for transportation and installation.

[0074] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. Any design that is the same or similar to the present invention belongs to the protection scope of the present invention. The device structure and method steps not described in detail in the present invention are all prior art and will not be further described in the present invention.

Claims

1. An auxiliary anode device for a cluster well group cathodic protection system, characterized in that: The invention comprises an external connection steel wire cable (1), a hanging and lowering connection structure (2), a metal shell (3), an auxiliary anode internal parallel cable (4), a single anode cable (5), a filler (6) and a single anode (7); the hanging and lowering connection structure (2) is arranged at the upper end of the metal shell (3), and the single anode (7) is multiple and arranged in parallel in the metal shell (3); each single anode (7) is connected to the auxiliary anode internal parallel cable (4) through the corresponding single anode cable (5); the upper end of the external connection steel wire cable (1) is located outside the hanging and lowering connection structure (2), and the lower end passes through the hanging and lowering connection structure (2) and is connected to the upper end of the auxiliary anode internal parallel cable (4) in the metal shell (3); a baffle is provided on the upper inner part of the metal shell (3), and the filler (6) is provided on the upper inner part of the metal shell (3). ) is filled in the metal shell (3) at the lower end of the baffle; the metal shell (3) at the upper end of the baffle is filled with a resistance reducing agent; the place where the resistance reducing agent is filled is a closed space; the monomer anode (7) is located in the metal shell (3) below the baffle; the filler (6) includes coke particles and inorganic salts, and the mass ratio of the coke particles to the inorganic salts is 1:1-2; the coke particles are spherical and their particle size ranges from 2mm to 5mm; the inorganic salts include sodium chloride and potassium chloride, and the weight ratio of sodium chloride to potassium chloride is 1:1-3; the baffle is a soluble magnesium-aluminum alloy isolation plate; the wall thickness of the metal shell (3) is at least 5mm, and small holes with a diameter of 1mm are evenly distributed on the metal shell (3), and the lower end of the metal shell (3) is a cone; the external connecting wire cable (1) is a polyvinyl chloride cable.

2. The auxiliary anode device of the cluster well group cathodic protection system according to claim 1, characterized in that: The hanging and lowering connection structure (2) is welded to the upper end of the metal shell (3).

3. The auxiliary anode device of the cluster well group cathodic protection system according to claim 2, characterized in that: The hanging and lowering connection structure (2) is a hanging and lowering connection rainbow or a conversion joint.

4. The auxiliary anode device of the cluster well group cathodic protection system according to claim 1, characterized in that: The plurality of single anodes (7) are evenly distributed from top to bottom along the central axis of the metal shell (3).

5. The auxiliary anode device of the cluster well group cathodic protection system according to claim 4, characterized in that: The single anode (7) is a combination of one or more of a high silicon cast iron anode, a noble metal oxide anode, a graphite anode and a platinum anode.

6. The auxiliary anode device of the cluster well group cathodic protection system according to claim 1, characterized in that: The metal shell (3) is made of chromium-nickel stainless steel.

7. A method for using an auxiliary anode device of a cluster well group cathodic protection system according to any one of claims 1 to 6, characterized in that: When the auxiliary anode device of the cluster well group cathodic protection system is placed at the bottom of the well completion and immersed in formation water, the formation water enters the device through small holes evenly distributed around the metal shell (3), contacts the filler (6) around the single anode (7), absorbs water through the filler (6), and reduces the grounding resistance of the single anode (7). At the same time, part of the filler (6) can be dissolved in the formation water, thereby increasing the conductivity of the filler (6) and reducing the grounding resistance of the single anode (7).

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