A downhole screw-type electrochemical induced fouling device

Abstract

The utility model belongs to the oilfield oil production well pipe column antifouling technical field, concretely relates to a downhole spiral electrochemical induced scale formation device. Including the lifting nipple, the lifting nipple lower end connects the outer shell, the outer shell inner wall inlays the outer shell insulation bushing, is equipped with a plurality of outer shell liquid inlet holes on the outer shell, is equipped with the bushing liquid inlet hole corresponding with the outer shell liquid inlet hole on the outer shell insulation bushing, is equipped with the center tube in the outer shell insulation bushing, the top of center tube is equipped with solid battery, the wall of center tube welds spiral blade, is equipped with the liquid outlet hole on the center tube, the lower end fixed insulation support of center tube. Reduce the pump frequency, single well annual maintenance cost reduces about 30%; The device can be reused, and the maintenance cost is low; Compared with the traditional scale inhibition technology, the effective period is longer, the scale formation efficiency is improved by more than 50%, and there is no chemical pollution.

Description

Technical Field

[0001] This utility model belongs to the field of oilfield well tubing anti-scaling technology, specifically relating to a downhole spiral electrochemical induced scaling device. Background Technology

[0002] As oilfield development time increases and overall well water cut rises, the incompatibility between produced fluids and injected water, as well as casing failure water, intensifies, leading to increasingly prominent wellbore scaling problems. Scale buildup easily causes pump and valve leakage and malfunction, shortens pump inspection cycles in high water-cut wells, and increases operating costs. In some high-yield casing failure wells where long-life packers have been used, scale settling can easily prevent the insertion of the casing pipe from being reinserted, complicating the operational procedures.

[0003] Existing technologies such as solid scale inhibitors and scale inhibitors are affected by factors such as well temperature and well pressure, with an effective period of only about 6 months, and the reduction in scaling rate is limited (0.4-0.68 mm / year), which cannot meet the needs of the field. Therefore, there is an urgent need for a high-efficiency and long-lasting anti-scaling device. Utility Model Content

[0004] The purpose of this invention is to provide a downhole spiral electrochemical induced scaling device to solve the problems of existing scale inhibition technologies having a short effective period and limited scale inhibition effect due to the influence of well temperature and well pressure.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A downhole spiral electrochemical induced scaling device includes a lifting sub, the lower end of which is connected to an outer shell. An insulating liner is embedded in the inner wall of the outer shell. The outer shell has several liquid inlet holes. The insulating liner has liner liquid inlet holes corresponding to the liquid inlet holes. A central tube is provided inside the insulating liner. A solid battery is provided at the top of the central tube. Spiral blades are welded to the wall of the central tube. The central tube has a liquid outlet hole. An insulating support is fixed at the lower end of the central tube.

[0006] The inner wall of the central tube is lined with a central tube insulating liner, which is made of anti-scaling PVC material.

[0007] The lower end of the outer shell is connected to a lower connector. The lower end of the lower connector is provided with an internal oil pipe. Several sand discharge holes are opened at the inclined step on the outer side wall of the lower connector. A bladeless sedimentation chamber is provided on the central tube at the position corresponding to the liquid inlet hole of the outer shell. The sand discharge holes are connected to the sedimentation chamber.

[0008] An insulating bracket is provided at the outer end of the central tube, and the insulating bracket is fixed to the lower end of the central tube by threads.

[0009] The outer end of the insulating bracket is equipped with a compression cap. The structure consisting of the insulating bracket and the compression cap is located inside the lower connector. The sealing pressure of the compression cap is ≥15MPa.

[0010] A variable-fastening connector is provided between the lifting section and the outer shell.

[0011] The upper limit of the liquid inlet hole in the outer casing is aligned with the lower end face of the spiral blade.

[0012] The outer casing insulating liner is made of anti-scaling and insulating PVC material. The upper and lower end faces of the central tube insulating liner are aligned with the upper and lower end faces of the central tube, respectively. The outer casing insulating liner forms electronic isolation with the solid battery and the spiral blades.

[0013] The solid-state battery is a magnesium-indium alloy negative ion battery, and the solid-state battery is connected to the top of the central tube by a threaded connection.

[0014] The pitch of the helical blades is 80-120mm, and the height is 15-20mm.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This invention employs a lifting section to provide a connection base between the device and the upper structure, enabling downhole lifting, installation, and maintenance. The outer shell, as the main load-bearing structure, can withstand downhole environmental pressure and protect internal components from external impacts. The corresponding inlet holes of the outer shell and liner guide the well fluid into the device in an orderly manner, ensuring that the well fluid accurately enters the reaction zone. The solid-state battery on the central tube can actively release negative ions, breaking the limitations of existing passive scale inhibition and guiding scale formation in a directional manner. The spiral blades can change the flow state of the well fluid, promoting the concentrated precipitation of scale on the blade surface and preventing scale deposition in key parts of the wellbore. The outlet hole can discharge the treated well fluid, forming a complete fluid circulation and ensuring the continuous and stable operation of the device.

[0016] Furthermore, the internal tubing of the lower connector enables the connection between the device and the lower tubing string, improving the device's adaptability for installation in the well; the bladeless settling chamber slows down the well fluid carrying sand particles, causing the sand particles to settle and separate, preventing sand particles from interfering with scale precipitation with the well fluid, and also preventing sand particles from wearing down internal components; the sand discharge hole can discharge the settled sand particles out of the device, preventing sand particles from accumulating and clogging the settling chamber or entering subsequent flow channels, reducing the risk of wellbore blockage caused by the mixing of sand particles and scale, and ensuring the long-term stable operation of the device.

[0017] Furthermore, the threaded fixing method ensures a firm connection between the insulating bracket and the central tube, guarantees the axial positioning accuracy of the central tube downhole, prevents displacement of the central tube due to well fluid impact or vibration, and maintains the fitting accuracy of each component; the insulating bracket can isolate the central tube from the lower connector, prevent negative ions from being conducted to the lower connector through the central tube, ensure that negative ions only act in the spiral blade area, improve the targeting of induced scaling, and prevent negative ion leakage from reducing the scaling induction effect.

[0018] Furthermore, the clamping cap forms an axial clamp on the insulating support, ensuring the sealing between the insulating support and surrounding components, and preventing high-pressure well fluid from leaking from the bottom of the device. The high-pressure seal can adapt to the complex pressure environment downhole, avoid well fluid leakage interfering with the working environment of internal components, ensure the sealing reliability of the device under high-pressure conditions, and extend the stable working cycle of the device downhole.

[0019] Furthermore, the variable-thread connector can be adapted to different specifications of lifting subs and housings, solving the connection problems of different pipe diameters and thread types; enabling the device to flexibly adjust the connection method according to the actual tubing string specifications in the well, eliminating the need to design separate devices for different tubing strings, improving the installation adaptability of the device under different well conditions and different tubing string configurations, and enhancing the versatility of the device.

[0020] Furthermore, this orifice design allows the well fluid flowing in from the inlet to directly enter the spiral blade area, avoiding stagnation or short circuits of the well fluid before entering the blade area; it ensures full contact between the well fluid and the spiral blade, and uniform distribution in the blade area without contact dead corners, maximizing the utilization of the spiral blade surface area, promoting uniform precipitation of scale on the blade surface, and improving the efficiency of induced scaling.

[0021] Furthermore, the anti-scaling PVC material is corrosion-resistant and does not easily form scale, which can extend the service life of the outer casing insulation liner, prevent scale buildup in the liner from clogging the inlet hole, and ensure smooth liquid intake; the electronic isolation function can prevent the negative ions released by the solid battery from being lost through conduction through the outer casing, ensuring that the negative ions are concentrated in the area where the spiral blades contact the well fluid, improving the utilization efficiency of negative ions, enhancing the induced scaling effect, and preventing electrochemical corrosion of the outer casing due to electronic conduction.

[0022] Furthermore, the solid-state battery is a magnesium-indium alloy negative ion battery. Magnesium-indium alloy negative ion batteries can stably release negative ions and are less affected by downhole environmental factors, and can continuously provide negative ions for a long time, solving the problem of short effective period of existing scale inhibition technology. The threaded connection method ensures that the battery is firmly connected to the central tube, and facilitates subsequent battery replacement and maintenance. When the battery life expires, it can be quickly replaced by disassembling the thread, reducing the complexity of removing the whole device for maintenance and lowering maintenance costs.

[0023] Furthermore, the spiral blades have specific pitch and height, which can effectively increase the contact area between the well fluid and the blades, while slowing down the flow rate of the well fluid in the blade area. This allows the well fluid sufficient time to react with the negative ions released by the solid battery, promoting the full adhesion of scale to the blade surface and preventing scale from depositing in other parts of the wellbore after flowing out of the blade area with the well fluid. This improves the effect of centralized scale control, ensures the cleanliness of key parts of the wellbore, and reduces operational failures caused by scaling. Attached Figure Description

[0024] Figure 1This is an external view of the structure of a downhole spiral electrochemical induced scaling device according to the present invention; Figure 2 This is a schematic diagram of the internal structure of a downhole spiral electrochemical induced scaling device according to the present invention.

[0025] Labeling Explanation: 1. Lifting Subsection; 2. Variable Clip Connector; 3. Outer Housing; 3-1. Liquid Inlet Hole of Outer Housing; 4. Insulating Liner of Outer Housing; 4-1. Liquid Inlet Hole of Liner; 5. Solid-State Battery; 6. Central Tube; 6-1. Liquid Outlet Hole; 6-2. Spiral Blade; 7. Insulating Liner of Central Tube; 8. Lower Connector; 8-1. Sand Drain Hole; 9. Insulating Support; 10. Compression Cap. Detailed Implementation

[0026] To further understand the present invention, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments. It should be understood that the embodiments are merely illustrative and not intended to limit the scope of the invention.

[0027] To further illustrate the technical means and effects of this utility model in achieving its intended purpose, the specific implementation methods, structural features and effects of this utility model are described in detail below with reference to the accompanying drawings and embodiments.

[0028] like Figure 1 and Figure 2 As shown in the figure, this embodiment proposes a downhole spiral electrochemical induced scaling device, which mainly consists of a lifting sub 1, a variable coupling 2, an outer shell 3, an outer shell liquid inlet 3-1, an outer shell insulating liner 4, a liner liquid inlet 4-1, a solid battery 5, a central tube 6, a liquid outlet 6-1, spiral blades 6-2, a central tube insulating liner 7, a lower connector 8, a sand discharge hole 8-1, an insulating support 9, and a clamping cap 10.

[0029] The top of the lifting sub 1 is equipped with a tubing hanger groove for connecting the upper tailpipe and bearing the weight of the tubing string, enabling the lifting and lowering of the device. The upper end of the variable-thread connector 2 connects to the lifting sub 1, and the lower end connects to the outer shell 3. The variable-thread connector 2 can adapt to different pipe diameters and different thread types, including pipe diameters from φ73mm to φ88.9mm and thread type conversions from EU threads to NU threads. The outer shell 3 is located at the lower end of the lifting sub 1. The outer shell 3 is a cylindrical hollow shell that serves as the main load-bearing structure of the device, bearing downhole pressure. An insulating liner 4 is embedded in the inner wall of the outer shell 3, and the insulating liner 4 is made of anti-scaling and insulating PVC material. The lower end of the outer shell 3 is also provided with a lower connector 8. Several outer shell liquid inlet holes 3-1 are evenly distributed on the side wall of the connection end between the outer shell 3 and the lower connector 8. The outer shell insulating liner 4 is provided with a liner liquid inlet hole 4-1 corresponding to the outer shell liquid inlet hole 3-1. A central tube 6 is provided inside the outer shell insulating liner 4. A solid battery 5 is provided at the top of the central tube 6. The solid battery 5 is a magnesium indium alloy negative ion battery. The solid battery 5 is threadedly connected to the top of the central tube 6. The solid battery 5 is used to release negative ions and react with Ca in the well fluid. 2+ Ba 2+The combination of cations accelerates the scaling reaction. A spiral blade 6-2 is welded to the outer wall of the central tube 6. The inlet hole 3-1 on the outer casing guides the well fluid into the spiral blade area. The upper limit of the inlet hole 3-1 is aligned with the lower end face of the spiral blade 6-2 to ensure uniform fluid distribution. An outlet hole 6-1 is provided on the section of the central tube 6 connecting to the solid-state battery 5. The spiral blade 6-2 on the central tube 6 has a blade pitch of 80-120 mm and a height of 15-20 mm. The lower end of the central tube 6 is threadedly connected to the insulating support 9. A bladeless sedimentation chamber is provided on the central tube 6 corresponding to the inlet hole 3-1 on the outer casing. The lower end of the outer casing 3 is also provided with a lower connector 8. The lower end of the lower connector 8 is configured as an internal oil pipe thread. Several sand discharge holes 8-1 are opened at the inclined step of the outer side wall of the lower connector 8. The sand discharge holes 8-1 are connected to the sedimentation chamber. The sand discharge holes 8-1 use fluid pressure difference to discharge the precipitated sand particles to the outside of the tube column. The sand discharge holes 8-1 are connected to the lower part of the tube column to form a fluid passage. The inner side of the central tube 6 is also lined with a central tube insulating liner 7. The central tube insulating liner 7 is made of anti-scaling and insulating PVC material. The central tube insulating liner 7 is used to isolate the fluid from the metal body to prevent electrochemical corrosion, while ensuring the smooth flow of fluid through the outlet hole 6-1. The lower end of the central tube 6 is provided with an insulating support 9. The insulating support 9 is fixed to the lower end of the central tube 6 by threads to ensure the axial positioning accuracy of the central tube 6 and to provide electronic insulation for the central tube 6, isolating the central tube 6 from the lower connector 8 to prevent negative ion leakage. The outer casing insulating liner 4, insulating support 9, central tube insulating liner 7, solid battery 5 and spiral blade 6-2 form electronic isolation. The outer end of the insulating support 9 is connected to a compression cap 10 with internal threads. The sealing pressure of the compression cap 10 is ≥15MPa. The compression cap 10 is an annular pressure cap structure to compress the insulating support 9. The structure formed by the insulating support 9 and the compression cap 10 is located inside the lower connector 8 to ensure axial sealing of the device and prevent well fluid from leaking from the bottom.

[0030] The well fluid first flows in through the outer shell inlet 3-1 on the side wall of the outer shell 3, and then through the liner inlet 4-1 on the outer shell insulating liner 4, which corresponds to the outer shell inlet 3-1, before entering the flow channel area formed by the outer shell insulating liner 4, the central tube 6, and the spiral blades 6-2. When the well fluid flows through the spiral blades 6-2 welded to the outer wall of the central tube 6, the flow velocity decreases from 1.5 m / s to 0.3 m / s because the spiral blades 6-2 increase the fluid contact area (specific surface area increases by 3 times). At this time, the solid battery 5 at the top of the central tube 6 releases negative ions (Mg). 2- In 3- ), and Ca in the well fluid 2+ Ba 2+Once the cations have fully contacted and combined, the scaling reaction is accelerated, and the resulting scale gradually adheres to the surface of the spiral blade 6-2. Subsequently, the well fluid carrying sand particles continues to flow and enters the bladeless sedimentation chamber located on the central tube 6 at the corresponding inlet port 3-1 of the outer casing. Inside the sedimentation chamber, the sand particles separate from the well fluid due to gravity and settle. The settled sand particles pass through the connection structure between the lower end of the central tube 6 and the lower connector 8, entering the sand discharge hole 8-1 on the inclined step of the outer wall of the lower connector 8. Utilizing the pressure difference within the well, the sand particles are discharged from the sand discharge hole 8-1 to the outside of the tubing string. After scaling and sand separation, the clean well fluid flows through the outlet port 6-1 at the upper end of the central tube 6 into the interior of the central tube 6, through the central tube insulating liner 7, and finally upwards into the upper tubing string, completing the well fluid treatment cycle. When scale accumulates on the surface of the spiral blade 6-2 or the solid-state battery life is nearing its end, the device is used to lift and lower the short section 1 for physical descaling and battery replacement. After maintenance, it can be lowered back into the well for reuse.

[0031] The above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although the utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this utility model. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this utility model should be covered within the protection scope of the claims of this utility model.

Claims

1. A downhole spiral electrochemically induced scaling device, characterized in that, It includes a lifting section (1), the lower end of the lifting section (1) is connected to the outer shell (3), the inner wall of the outer shell (3) is fitted with an outer shell insulating liner (4), the outer shell (3) is provided with a number of outer shell liquid inlet holes (3-1), the outer shell insulating liner (4) is provided with a liner liquid inlet hole (4-1) corresponding to the outer shell liquid inlet hole (3-1), the outer shell insulating liner (4) is provided with a central tube (6), the top of the central tube (6) is provided with a solid battery (5), the inner wall of the central tube (6) is lined with a central tube insulating liner (7), the outer wall of the central tube (6) is welded with a spiral blade (6-2), and the central tube (6) is provided with an outlet hole (6-1).

2. The downhole spiral electrochemical induced scaling device according to claim 1, characterized in that, The central tube insulating liner (7) is made of scale-resistant and insulating PVC material.

3. The downhole spiral electrochemical induced scaling device according to claim 1, characterized in that, The lower end of the outer shell (3) is connected to the lower connector (8). The lower end of the lower connector (8) is provided with an inner oil pipe. Several sand discharge holes (8-1) are opened at the inclined step on the outer side wall of the lower connector (8). A bladeless sedimentation chamber is provided on the central tube (6) at the position corresponding to the liquid inlet hole (3-1) of the outer shell. The sand discharge holes (8-1) are connected to the sedimentation chamber.

4. The downhole spiral electrochemical induced scaling device according to claim 3, characterized in that, An insulating bracket (9) is provided at the lower end of the central tube (6), and the insulating bracket (9) is fixed to the lower end of the central tube (6) by thread.

5. A downhole spiral electrochemical induced scaling device according to claim 4, characterized in that, The outer end of the insulating bracket (9) is provided with a compression cap (10). The structure consisting of the insulating bracket (9) and the compression cap (10) is located inside the lower connector (8). The sealing pressure of the compression cap (10) is ≥15MPa.

6. The downhole spiral electrochemical induced scaling device according to claim 1, characterized in that, A variable snap joint (2) is provided between the lifting section (1) and the outer shell (3).

7. The downhole spiral electrochemical induced scaling device according to claim 1, characterized in that, The upper limit of the liquid inlet hole (3-1) of the outer shell is aligned with the lower end face of the spiral blade (6-2).

8. The downhole spiral electrochemical induced scaling device according to claim 1, characterized in that, The outer casing insulating liner (4) is made of anti-scalding insulating PVC material. The upper and lower end faces of the central tube insulating liner (7) are aligned with the upper and lower end faces of the central tube (6), respectively. The outer casing insulating liner (4), insulating support (9), central tube insulating liner (7) form electronic isolation with the solid battery (5) and spiral blades (6-2).

9. A downhole spiral electrochemical induced scaling device according to claim 8, characterized in that, The solid battery (5) is a magnesium indium alloy negative ion battery, and the solid battery (5) is threadedly connected to the top of the central tube (6).

10. A downhole spiral electrochemically induced scaling device according to claim 9, characterized in that, The pitch of the helical blade (6-2) is 80-120mm, and the height is 15-20mm.

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