Double-layer rotary well casing circulating flushing brine well system

Abstract

The invention provides a double-layer rotary well casing circulating flushing brine well system. The brine well system comprises a closed circulation flushing pipeline, a wellbay, a well pipe rotation driving mechanism, a bottom sand setting pipe, an outer rotary well pipe, an inner rotary well pipe and a permeable filter material layer arranged between the inner rotary well pipe and the outer rotary well pipe, and the inner rotary well pipe and the outer rotary well pipe each comprise a rotary pipe and a fixed pipe which are correspondingly provided with permeable holes. The well casing rotation driving mechanism controls the rotation pipes of the inner and outer rotation well casings to rotate, so that the two well casings are opened or closed; the closed circulating flushing pipeline comprises an overground water storage tank, an underground water storage tank and a plurality of pressurized flushing pipelines embedded in the permeable filter material layer; and a plurality of groups of nozzles are arranged on each pressurized flushing pipeline. The inner rotating well pipe and the outer rotating well pipe jointly form a closed circulating flushing loop, the path of fresh water invading the stratum is cut off, salt deposition and blockage removal in the brine extraction well through fresh water flushing are achieved, salt layer corrosion cavities caused by overflow of flushing fresh water are reduced to a great extent, and the problem of collapse around the well is solved.

Description

Technical Field

[0001] This invention relates to the field of underground brine extraction technology, specifically a double-layer rotary well casing circulation flushing brine extraction well system. Background Technology

[0002] The Qarhan Salt Lake, as the largest known potassium-magnesium salt mining area in my country, is a large-scale comprehensive salt deposit mainly composed of brine potassium-magnesium salt deposits. Its brine is rich in beneficial elements such as K⁺ and Mg²⁺. The main cations are K⁺, Na⁺, Mg²⁺, and Ca²⁺, and the main anion is Cl⁻, followed by SO₄²⁻.

[0003] The primary target of mining in the salt lake area is the intercrystalline brine hidden within the salt layers. This brine exists in the pores and fissures of the salt rock and is extracted through brine wells. Based on hydrogeological characteristics, the underground brine of the Qarhan Salt Lake is generally weakly alkaline, with a total dissolved solids (TDS) greater than 300 g / L, and the dominant anions and cations are Cl⁻, Na⁺, and Mg²⁺. During long-term mining operations, with increasing production capacity requirements, surface channel mining can no longer meet the production needs of the salt lake mining area. It is necessary to promote well mining to more efficiently and sustainably extract brine resources buried deeper and with more complex structures.

[0004] The brine of the Qarhan Salt Lake is a complex salt solution. During transportation and extraction, due to evaporation, cooling, or pressure changes, salts such as halite (NaCl) and carnallite (KCl·MgCl2·6H2O) in the brine easily reach supersaturation and crystallize. This can clog the brine pumps, pipelines, and seepage channels around the well walls, directly affecting brine extraction efficiency and even leading to production shutdowns. Flushing with fresh water can dissolve these crystals promptly, ensuring system smooth operation, and is the most common, simple, and efficient method to alleviate salt formation in brine wells. However, the saline soil in the Qarhan Salt Lake area exhibits significant dissolution properties, a characteristic that has long plagued engineering construction in the region. The underlying mechanism of dissolution lies in the large amount of soluble salts in the lake strata, which act as cementing materials in the sedimentary layers, maintaining the stability of the soil structure. When freshwater is injected into brine wells to flush them, the salt minerals in the strata dissolve rapidly, weakening the rock-soil structure and increasing porosity. Under stress, this leads to compressive deformation, forming erosion channels in the surface and deeper layers, causing well-circumferential collapse and ground subsidence. Currently, in some mining areas of the Qarhan Salt Lake with unstable geological conditions, brine wells with a radius of about ten meters require weekly backfilling and compaction to reinforce them due to salt deposition caused by freshwater flushing. Therefore, a systematic method to reduce well-circumferential collapse caused by salt deposition from freshwater flushing is urgently needed. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a dual-layer rotating well casing circulation flushing well structure system. This system can form a closed-loop internal circulation consisting of "outer rotating well casing - permeable filter media - inner rotating well casing", which reduces salt layer dissolution cavities caused by the overflow of flushing fresh water at the source. At the same time, it introduces a strong eddy effect and stirring action, which promotes the flushing and unblocking of salt deposits.

[0006] To achieve the above objectives, the present invention provides a double-layer rotating well casing circulation flushing brine well system. The brine well system includes a brine well body and a closed-loop flushing pipeline. The brine well body includes a well platform, a double-layer rotating well casing, a well casing rotation drive mechanism, and a bottom sand settling pipe. The well platform is located on the ground. The double-layer rotating well casing includes an outer rotating well casing, an inner rotating well casing, and a permeable filter layer disposed between the inner and outer rotating well casings. The outer rotating well casing includes an outer rotating pipe, an outer pipe protection pipe, and an outer pipe isolation net. The outer pipe protection pipe includes two fixed pipes disposed on the inner and outer sides of the outer rotating pipe. The outer pipe isolation net includes two layers of filter screens disposed on the outer wall of the outer outer pipe protection pipe and the inner wall of the inner outer pipe protection pipe. Corresponding water-permeable holes are provided on the outer rotating pipe and the outer pipe protection pipe. The inner rotating well casing includes an inner rotating pipe, an inner pipe protection pipe, and an inner pipe isolation net. The inner tube protection pipe includes two fixed pipes disposed inside and outside the inner rotating pipe. The inner tube isolation net is disposed on the outer wall of the outer inner tube protection pipe. Corresponding inner tube water permeable holes are provided on the inner rotating pipe and the inner tube protection pipe. The lower ends of the outer rotating pipe and the inner rotating pipe are rotatably connected to the bottom sand-collecting pipe, and the pipe openings extend out of the well platform. The pipe opening of the inner rotating pipe is higher than that of the outer rotating pipe. The well pipe rotation drive mechanism includes an outer tube drive motor and an inner tube drive motor. The outer tube drive motor is driven by the outer rotating pipe through a rotation mechanism and controls the rotation of the outer rotating pipe, so that the water permeable holes of the outer rotating pipe and the outer tube protection pipe open correspondingly or close staggeredly. The inner tube drive motor is driven by the inner rotating pipe through a rotation mechanism and controls the rotation of the inner rotating pipe, so that the water permeable holes of the inner rotating pipe and the inner tube protection pipe open correspondingly or close staggeredly.

[0007] The closed-loop flushing pipeline includes an above-ground water tank, an underground water tank, and multiple pressurized flushing pipes buried in the permeable filter layer. The multiple pressurized flushing pipes are arranged in a ring within the permeable filter layer. Each pressurized flushing pipe is laid along the height of the brine well body, with both its upper and lower ends extending out of the permeable filter layer. Multiple sets of nozzles are installed on each pressurized flushing pipe. The above-ground water tank is connected to the upper end of the multiple pressurized flushing pipes through a liquid delivery pipe, and a pressurized pump is installed on the liquid delivery pipe. The lower end of the pressurized flushing pipe extends from the outer wall of the bottom sand settling pipe and is connected to the underground water tank through a first return pipe. A control valve is installed on the first return pipe. The underground water tank and the above-ground water tank are connected through a second return pipe, and a return pump is installed on the second return pipe.

[0008] A preferred technical solution of the present invention: The brine extraction well system further includes a PLC control box, which is connected to the control terminals of the outer pipe drive motor, the inner pipe drive motor, the pressurizing pump, the control valve, and the return pump. The PLC control box controls the well pipe rotation drive mechanism to drive the outer rotating well pipe and the inner rotating well pipe to rotate and close. Then, the PLC control box controls the pressurizing pump to introduce fresh water from the surface water storage tank into the pressurized flushing pipe to flush the permeable filter layer with fresh water. The fresh water flushing pressure is controlled between 1.0 MPa and 3.0 MPa. At the same time, the PLC control box controls the control valve and the return pump to open, and pump the flushed water back to the surface water storage tank for recycling.

[0009] A preferred technical solution of the present invention is as follows: the well pipe rotation drive mechanism further includes a support frame, and both the outer pipe drive motor and the inner pipe drive motor are fixed on the support frame; an external gear is provided at the wellhead of the outer rotating pipe, and an internal gear is provided at the wellhead of the inner rotating pipe; a first transmission gear is fixedly connected to the output shaft of the outer pipe drive motor, and the first transmission gear meshes with the external gear; a second transmission gear is fixedly connected to the output shaft of the inner pipe drive motor, and the second transmission gear meshes with the internal gear.

[0010] The preferred technical solution of the present invention is as follows: the first return pipe is an annular pipe or an arc pipe, which is arranged on the outer wall of the bottom sand settling pipe, and a filter screen is provided at the connection between each pressurized flushing pipe and the first return pipe.

[0011] The preferred technical solution of the present invention is as follows: the bottom sand settling pipe is a sand settling pipe cast with corrosion-resistant cement, comprising two layers of steel pipes with smooth coatings on the inner and outer surfaces and slag cement filling the space between the two layers of steel pipes; the bottoms of the two outer protective pipes and the two inner protective pipes are all fixed to the top surface of the bottom sand settling pipe; the bottom of the outer rotating pipe is rotatably connected to the bottom sand settling pipe through an outer rotating well pipe bearing; the bottom of the inner rotating pipe is rotatably connected to the bottom sand settling pipe through an inner rotating well pipe bearing; both the outer rotating well pipe bearing and the inner rotating well pipe bearing are fixed to the top surface of the bottom sand settling pipe.

[0012] The preferred technical solution of the present invention is as follows: the outer rotating pipe, the outer pipe protection pipe, the inner rotating pipe, and the inner pipe protection pipe are all made of steel pipe with a wall thickness of 6mm to 8mm, and the pipe wall is uniformly provided with water-permeable holes with a porosity of 12% to 16%; the outer pipe isolation net and the inner pipe isolation net are both made of metal filter net; the outer diameter of the outer rotating well pipe is 700mm to 900mm, and the outer diameter of the inner rotating well pipe is 500mm to 600mm.

[0013] The preferred technical solution of the present invention is as follows: the infusion pipeline includes an annular or arc-shaped water pipe and a connecting pipe. The annular or arc-shaped water pipe is arranged between the outer rotating pipe and the inner rotating pipe and is positioned above the well platform. The ground water storage tank is connected to the annular or arc-shaped water pipe through the connecting water pipe. The connecting water pipe extends from the pipe opening of the outer rotating pipe into the space between the outer rotating well pipe and the inner rotating well pipe.

[0014] The preferred technical solution of the present invention is as follows: the permeable filter material layer is selected from 5mm to 10mm of gravel, the pressurized flushing pipe is selected from UPVC pipe, and a group of nozzles is arranged at intervals of 40cm to 60cm on the pressurized flushing pipe. Each group of nozzles includes four nozzles, which are horizontally distributed at an angle of 90°. The nozzles are narrow-footed solid conical nozzles.

[0015] The preferred technical solution of the present invention is as follows: the total flow rate of the fresh water flushing should be controlled at 4 to 6 times the volume of the permeable filter media layer, and the flushing time should be controlled at 80 min to 120 min.

[0016] A preferred technical solution of the present invention: the stainless steel filter media has two layers, the first layer being a 40-60 mesh stainless steel filter screen and the second layer being a 100-120 mesh stainless steel filter screen. The well pipe stainless steel filter screen is manufactured using a woven mat process.

[0017] The underground water storage is equipped with a salinity meter and a water level gauge, and the mineralization and water level of the circulating flushing fresh water are monitored through a PLC control box.

[0018] The beneficial effects of this invention are:

[0019] (1) The outer rotating well pipe and the inner rotating well pipe of the present invention together form a closed-loop flushing circuit; the flushing fluid is strictly limited to the closed loop formed by “outer rotating well pipe-permeable filter material-inner rotating well pipe”, which cuts off the path of fresh water intrusion into the formation, realizes the flushing of salt in the brine well and unblocks it, greatly reduces the salt layer dissolution cavities caused by the overflow of flushing fresh water, can solve the problem of well perimeter collapse from the source, protect the original formation structure, and maintain the stability of the well wall.

[0020] (2) Both the outer and inner rotating well pipes of the present invention adopt a three-layer coaxial structure of “protective pipe-rotating pipe-protective pipe”. The protective pipe is fixed, and the rotating pipe is driven by a surface starter and rotated by bearing support. It dynamically prevents salt deposition and self-cleaning. The middle rotating pipe wall generates a continuous relative shearing motion between the crystal particles or the attached salt deposits in the brine, which can effectively peel off and crush the salt crystals that are about to be deposited on the pipe wall. Both the inner and outer rotating well pipes are equipped with isolation nets to prevent soil from entering the water permeable holes of the pipe wall and causing blockage.

[0021] (3) Closed-loop flushing circuit optimizes the flow field and improves flushing efficiency; the closed-loop flushing circuit introduces a strong eddy effect and stirring action, which enhances the turbulent diffusion and convective shear stress between the flushing fluid and the surface of the salt deposits. At the same time, the insoluble particles or crystalline particles flushed down are carried out of the well with the circulating fluid flow, avoiding their secondary settling and blockage at the bottom of the well or at the filter.

[0022] (4) The PLC system adopts linkage control logic to control the closure of the double-layer rotating well pipe, forming a closed-loop flushing circuit, while regulating the pressure and volume of fresh water flushing, ensuring the efficient desalination and production operation of the brine well system. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 This is a cross-sectional view of the wellhead area in this invention;

[0025] Figure 3 yes Figure 1 Sectional view of AA';

[0026] Figure 4 yes Figure 1 Sectional view of BB';

[0027] Figure 5 This is a schematic diagram of the internal and external rotating well casing in this invention;

[0028] Figure 6 This is a top view of the present invention;

[0029] Figure 7 This is a schematic diagram of the inner and outer rotating well casing structure in this invention;

[0030] Figure 8 This is a schematic diagram of the inner rotating well casing protection pipe and the outer rotating well casing protection pipe in this invention;

[0031] Figure 9 This is a schematic diagram of the nozzle layout in this invention.

[0032] In the diagram: 1. Outer rotating well casing; 100. Outer rotating pipe; 101. Outer casing protection pipe; 102. Outer casing isolation net; 103. Outer casing water perforation hole; 104. Outer rotating well casing bearing; 2. Well platform; 3. Inner rotating well casing; 300. Inner rotating pipe; 301. Inner casing protection pipe; 302. Inner casing isolation net; 303. Inner casing water perforation hole; 304. Inner rotating well casing bearing; 4. Bottom sand settling pipe; 5. Permeable filter layer; 6. External gear; 7. Internal gear; 8. Surface water tank; 9. Underground water tank; 10. Pressurized flushing pipeline; 11. Infusion pipeline; 12. Pressurized pump; 13. First return pipeline; 14. Second return pipeline; 15. Return pump; 16. Filter screen; 17. Control valve; 18. Nozzle; 19. Support frame; 20. Outer tube drive motor; 21. Inner tube drive motor; 22. First transmission gear; 23. Second transmission gear; 24. PLC control box. Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments. The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the present invention. In order to better illustrate the specific embodiments of the present invention, some parts in the drawings may be omitted, enlarged or reduced, and do not represent the actual product size. It is understandable for those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. Based on the specific embodiments of the present invention, all other specific embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] In the description of this invention, it should be noted that the terms "front", "rear", "upper", "lower", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and 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 invention.

[0035] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] The embodiment provides a dual-layer rotary well casing circulation flushing brine well system, such as Figures 1 to 9As shown, the brine extraction well system includes a brine extraction well body and a closed-loop flushing pipeline. The brine extraction well body includes a well platform 2, a double-layer rotating well casing, a well casing rotation drive mechanism, and a bottom sand settling pipe 4. The well platform 2 is located on the ground. The double-layer rotating well casing includes an outer rotating well casing 1, an inner rotating well casing 3, and a permeable filter media layer 5 disposed between the inner and outer rotating well casings. The outer rotating well casing 1 includes an outer rotating pipe 100, an outer pipe protection pipe 101, and an outer pipe isolation net 102. The outer pipe protection pipe 101 includes two fixed pipes disposed on the inner and outer sides of the outer rotating pipe 100. The outer pipe isolation net 102 includes two layers of filter media disposed on the outer wall of the outer outer pipe protection pipe 101 and the inner wall of the inner outer pipe protection pipe 101. The outer rotating pipe 100 and the outer pipe protection pipe 101 are provided with corresponding outer pipe water permeable holes 103; the inner rotating well pipe 3 includes an inner rotating pipe 300, an inner pipe protection pipe 301 and an inner pipe isolation net 302. The inner pipe protection pipe 301 includes two fixed pipes set inside and outside the inner rotating pipe 300. The inner pipe isolation net 302 is set on the outer wall of the outer inner pipe protection pipe 301. Corresponding inner pipe water permeable holes 303 are provided on the inner rotating pipe 300 and the inner pipe protection pipe 301; the lower ends of the outer rotating pipe 100 and the inner rotating pipe 300 are rotatably connected to the bottom sand settling pipe 4, and the pipe openings extend out of the well platform 2. The pipe opening of the inner rotating pipe 300 is higher than the pipe opening of the outer rotating pipe 100. The isolation net can block small particles that can pass through the gaps between the outer rotating well casing 1 and the inner rotating well casing 3, reducing wear on components such as the rotating well casing and deep well pump in the brine production system. At the same time, the well casing isolation net, together with the outer rotating well casing 1 and the inner rotating well casing 3, forms a "coarse filtration + fine filtration" combined system, which ensures sufficient flow area (responsible for the inner and outer rotating well casings) and provides fine sand-blocking capability (responsible for the isolation net).

[0037] In this embodiment, both the outer rotating well pipe bearing 104 and the inner rotating well pipe bearing 304 are fixed to the top surface of the bottom sand-collecting pipe 4. The outer rotating pipe 100, the outer pipe protection pipe 101, the inner rotating pipe 300, and the inner pipe protection pipe 301 are all made of steel pipe with a wall thickness of 6mm to 8mm. The pipe wall is uniformly provided with water-permeable holes, and the porosity is 12% to 16%. If the porosity is too low (for example, below 10%), the flow area will be too small, and the brine will generate a large head loss when flowing through the screen pipe, reducing the brine extraction efficiency. If the porosity is too high, the screen pipe will not have sufficient strength to resist compression and torsion, resulting in stress deformation, thereby causing sand prevention failure or complete blockage. Both the outer pipe isolation net 102 and the inner pipe isolation net 302 use metal filter screens to prevent soil and debris from entering the permeable holes of the outer rotating well pipe 1 and the inner rotating well pipe 3, causing blockage. The outer diameter of the outer rotating well pipe 1 is 700mm~900mm, and the outer diameter of the inner rotating well pipe 3 is 500mm~600mm. The permeable filter media layer 5 is made of 5mm~10mm gravel. Excessively fine permeable filter media has a high sand-blocking rate but is easily blocked, resulting in poor permeability and severely limiting production capacity. Furthermore, its low strength makes it prone to breakage. Excessively coarse permeable filter media has excellent permeability but cannot effectively block sand; fine formation sand will directly pass through the filter media layer, causing screen blockage and formation sand discharge. It also weakens the support for the well wall. The bottom sedimentation pipe 4 is a sedimentation pipe made of corrosion-resistant cement, which includes two layers of steel pipes with smooth coatings on the inner and outer surfaces and slag cement filling the space between the two layers of steel pipes. This is to collect and deposit solid particles in the brine, prevent damage to the wellbore and brine pump, and ensure the long-term, stable and efficient operation of brine extraction.

[0038] An embodiment provides a dual-layer rotary well casing circulation flushing brine production well system, such as... Figure 1 and Figure 6 As shown, the well casing rotation drive mechanism includes an outer casing drive motor 20 and an inner casing drive motor 21. The outer casing drive motor 20 is connected to the outer rotating casing 100 via a rotation mechanism and controls the rotation of the outer rotating casing 100, causing the outer rotating casing 100 and the outer casing water permeable holes 103 of the outer casing protective pipe 101 to open correspondingly or close offset from each other. The inner casing drive motor 21 is connected to the inner rotating casing 300 via a rotation mechanism and controls the rotation of the inner rotating casing 300, causing the inner rotating casing 300 and the inner casing water permeable holes 303 on the inner casing protective pipe 301 to open correspondingly or close offset from each other. The well pipe rotation drive mechanism can be opened in a corresponding manner or closed in a staggered manner; the well pipe rotation drive mechanism also includes a support frame 19, and the outer pipe drive motor 20 and the inner pipe drive motor 21 are both fixed on the support frame 19; an outer gear 6 is provided at the wellhead of the outer rotating pipe 100, and an inner gear 7 is provided at the wellhead of the inner rotating pipe 300; the output shaft of the outer pipe drive motor 20 is fixedly connected to a first transmission gear 22, which meshes with the outer gear 6; the output shaft of the inner pipe drive motor 21 is fixedly connected to a second transmission gear 23, which meshes with the inner gear 7.

[0039] An embodiment provides a dual-layer rotary well casing circulation flushing brine production well system, such as... Figures 1 to 9 As shown, the closed-loop flushing pipeline includes an above-ground water storage tank 8, an underground water storage tank 9, and multiple pressurized flushing pipes 10 buried in the permeable filter layer 5. The multiple pressurized flushing pipes 10 are arranged in a ring within the permeable filter layer 5. Each pressurized flushing pipe 10 is laid along the height direction of the brine well body, and both its upper and lower ends extend out of the permeable filter layer 5. Multiple sets of nozzles 18 are installed on each pressurized flushing pipe 10. The above-ground water storage tank 8 is connected to the upper end of the multiple pressurized flushing pipes 10 through a liquid delivery pipe 11, and a pressurized pump 12 is installed on the liquid delivery pipe 11. The lower end of the pressurized flushing pipe 10 extends from the outer wall of the bottom sand settling pipe 4 and is connected to the underground water storage tank 9 through a first return pipe 13. A control valve 17 is installed on the first return pipe 13. The underground water storage tank 9 and the above-ground water storage tank 8 are connected through a second return pipe 14, and a return pump 15 is installed on the second return pipe 14. The first return pipe 13 is an annular or arc-shaped pipe, which is installed on the outer wall of the bottom sand settling pipe 4. Each pressurized flushing pipe 10 is provided with a stainless steel filter screen 16 at the connection between it and the first return pipe 13. The stainless steel filter screen 16 has two layers: the first layer is a 40-60 mesh stainless steel filter screen, and the second layer is a 100-120 mesh stainless steel filter screen. The well pipe stainless steel filter screen adopts a woven fabric process, which has high structural strength, uniform mesh, and is not easily deformed.

[0040] In the embodiments, such as Figure 4 As shown, the infusion pipeline 11 includes a ring-shaped or arc-shaped water pipe and a connecting pipe. The ring-shaped or arc-shaped water pipe is laid between the outer rotating pipe 100 and the inner rotating pipe 300, and is positioned higher than the well platform 2. The above-ground water storage tank 8 is connected to the ring-shaped or arc-shaped water pipe through the connecting water pipe. The connecting water pipe extends from the opening of the outer rotating pipe 100 into the space between the outer rotating well pipe 1 and the inner rotating well pipe 3. The pressurized flushing pipeline 10 is made of UPVC pipe, which has good corrosion resistance and a smooth inner wall that is not prone to scaling. Figure 9 As shown, a set of nozzles 18 are arranged at intervals of 40 cm to 60 cm on the pressurized flushing pipe 10. Each set of nozzles includes four nozzles, which are horizontally distributed at an angle of 90°. The nozzles 18 are narrow-legged solid conical nozzles, and the material is brass with good comprehensive performance of wear resistance and corrosion resistance.

[0041] In the embodiments, such as Figure 1 and Figure 6As shown, the brine extraction well system also includes a PLC control box 24. The PLC control box 24 is connected to the control terminals of the outer pipe drive motor 20, the inner pipe drive motor 21, the pressurizing pump 12, the control valve 17, and the return pump 15. The PLC control box 24 controls the well pipe rotation drive mechanism to drive the outer rotating well pipe 1 and the inner rotating well pipe 3 to rotate until the water permeable holes on the walls of the two well pipes are staggered and closed. Then, the PLC control box 24 controls the pressurizing pump 12 to introduce fresh water from the surface water storage tank 8 into the pressurized flushing pipe 10 to flush the permeable filter layer 5 with fresh water. At the same time, the PLC control box 24 controls the control valve 17 and the return pump 15 to open, and pump the flushed water back to the surface water storage tank 8 for recycling. When the outer rotating well pipe 1 and the inner rotating well pipe 3 are closed, the PLC control box 18 adjusts the above-ground water storage tank 8 to add fresh water. The pressurization pump 12 then injects the fresh water through the delivery pipe 11 into the pressurized flushing pipe 10, from which it is sprayed out from the nozzles 18, pressurizing and flushing the filter media. The flushed fresh water is collected by the underground water storage tank 9 and then pumped back to the above-ground water storage tank 8 by the return pump 15 and return pipe. When the inner rotating well pipe 3 and the outer rotating well pipe 1 are rotated open to allow brine production, the PLC control box 18 controls the control valve 17 to close. In this embodiment, the PLC control box 18 controls the closing of the rotating well pipes and regulates the pressure and volume of the fresh water flushing to ensure efficient desalination and production operation of the entire brine well system. In this embodiment, the fresh water flushing pressure is controlled between 1.0 MPa and 3.0 MPa to overcome the resistance of formation and well pipe salt deposition and to deliver water into the filter media area without damaging the well pipes and filter pipes. The total flow rate of freshwater rinsing should be controlled at 4 to 6 times the volume of the permeable filter media layer 5, and the rinsing time should be controlled at 80 to 120 minutes. This ensures that the freshwater has sufficient residence time in the filter media area to fully dissolve the salt crystals.

[0042] The double-layer rotary well casing circulating flushing brine well device system of this invention operates as follows: First, the PLC control box 24 adjusts the above-ground water storage tank 8 to introduce fresh water. Next, the PLC control box 24 adjusts the well casing rotation drive mechanism to drive the outer rotary well casing gear 6 and the inner rotary well casing gear 7 respectively, thereby controlling the water permeability holes on the fixed pipe of the outer rotary pipe 100 and the outer pipe protection pipe 101 to be staggered and closed, and the water permeability holes on the fixed pipe of the inner rotary pipe 300 and the inner pipe protection pipe 303 to be staggered and closed. Simultaneously, the control valve 17 is opened to form a closed-loop flushing circuit with the pressurized flushing pipeline 10, the pressurized pump 12, the return pump 15, the above-ground water storage tank 8, the underground water storage tank 9, the infusion pipeline 11, the first return pipe 13, and the second return pipe 14. Subsequently, the PLC control box 24 adjusts the pressurized pump 12 to apply pressure, pumping fresh water into the pressurized flushing pipeline 10 to flush and unblock the salt deposits in the permeable filter layer 5. Simultaneously, the PLC control box 24 regulates the return pump 15 to extract and reuse fresh water. In this embodiment, a salinity meter and a water level gauge are installed inside the above-ground water storage tank 8, and the PLC control box 24 monitors the salinity and water level of the circulating flushing fresh water. When the salinity of the circulating fresh water reaches 150 g / L~180 g / L, the PLC control box 24 controls the above-ground water storage tank 8 to empty the circulating fresh water and reintroduce fresh water. When the salinity of the circulating fresh water is lower than 150 g / L~180 g / L, the concentration difference between the solid and liquid surfaces of salt crystals in the brine well is extremely large, the dissolution rate is fast, and the return water carries crystals strongly.

[0043] The inner rotating well casing 3 and the outer rotating well casing 1 of this invention both adopt a three-layer coaxial structure of "protective layer-sandwich tube-protective layer", wherein the protective layer is fixed, and the sandwich tube rotates through a drive mechanism and supported by bearings. Its advantages are: a closed-loop flushing circuit. Fresh water is strictly confined to the closed loop formed by "outer rotating well casing 1-permeable filter layer 5-inner rotating well casing 3", cutting off the path of fresh water intrusion into the formation, realizing fresh water flushing and unblocking of salt deposits in the brine well, greatly reducing salt layer dissolution cavities caused by fresh water overflow during flushing, and solving the problem of wellbore collapse from the source; dynamic anti-salt deposition and self-cleaning. A continuous relative shearing motion is generated between the intermediate rotating pipe wall and the crystalline particles or already attached salt deposits in the brine, which can effectively peel off and crush salt crystals that are about to be deposited on the pipe wall; optimized flow field and improved flushing efficiency. The closed flushing circuit introduces a strong eddy current effect and stirring action, enhancing the turbulent diffusion and convective shear stress between the flushing fluid and the surface of the salt deposits. Simultaneously, insoluble or crystalline particles flushed down are carried out of the well by the circulating fluid, preventing secondary settling and blockage at the well bottom or filter; protecting the original formation structure and maintaining wellbore stability. The fixed outer casing 101 is fixed to the well platform 2 at the top, serving as a permanent casing. It supports the wellbore and isolates the formation, preventing direct friction and disturbance between the rotating body and the fragile salt rock formation.

[0044] The above description is merely one embodiment of the present invention, and while it is detailed and specific, it should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A double-layer rotary well casing circulation flushing brine production well system, characterized in that: The brine extraction well system includes a brine extraction well body and a closed-loop flushing pipeline. The brine extraction well body includes a well platform (2), a double-layer rotating well casing, a well casing rotation drive mechanism, and a bottom sand settling pipe (4). The well platform (2) is located on the ground. The double-layer rotating well casing includes an outer rotating well casing (1), an inner rotating well casing (3), and a permeable filter material layer (5) disposed between the inner and outer rotating well casings. The outer rotating well casing (1) includes an outer rotating pipe (100), an outer pipe protection pipe (101), and an outer pipe isolation net (102). The outer pipe protection pipe (101) includes a filter material layer (5) disposed between the outer rotating pipe and the inner rotating pipe. Two fixed pipes are provided on the inner and outer sides of the rotating pipe (100). The outer pipe isolation net (102) includes two layers of filter screens provided on the outer wall of the outer outer pipe protection pipe (101) and the inner wall of the inner outer pipe protection pipe (101). Corresponding outer pipe water permeable holes (103) are provided on the outer rotating pipe (100) and the outer pipe protection pipe (101). The inner rotating well pipe (3) includes an inner rotating pipe (300), an inner pipe protection pipe (301) and an inner pipe isolation net (302). The inner pipe protection pipe (301) includes two fixed pipes provided on the inner and outer sides of the inner rotating pipe (300). Two fixed pipes are provided. The inner pipe isolation net (302) is set on the outer wall of the outer inner pipe protection pipe (301). Corresponding inner pipe water permeable holes (303) are provided on the inner rotating pipe (300) and the inner protective pipe (301). The lower ends of the outer rotating pipe (100) and the inner rotating pipe (300) are rotatably connected to the bottom sand sinking pipe (4). The pipe openings extend out of the well platform (2). The pipe opening of the inner rotating pipe (300) is higher than the pipe opening of the outer rotating pipe (100). The well pipe rotation drive mechanism includes an outer pipe drive motor (20) and an inner pipe drive motor (21). The outer tube drive motor (20) is connected to the outer rotating tube (100) via a rotating mechanism and controls the rotation of the outer rotating tube (100), so that the water permeable holes (103) of the outer rotating tube (100) and the outer tube protective tube (101) open correspondingly or close staggeredly; the inner tube drive motor (21) is connected to the inner rotating tube (300) via a rotating mechanism and controls the rotation of the inner rotating tube (300), so that the water permeable holes (303) of the inner rotating tube (300) and the inner tube protective tube (301) open correspondingly or close staggeredly. The closed-loop flushing pipeline includes an above-ground water storage tank (8), an underground water storage tank (9), and multiple pressurized flushing pipes (10) buried in the permeable filter layer (5). The multiple pressurized flushing pipes (10) are arranged in a ring within the permeable filter layer (5). Each pressurized flushing pipe (10) is laid along the height direction of the brine well body, and both its upper and lower ends extend out of the permeable filter layer (5). Multiple sets of nozzles (18) are installed on each pressurized flushing pipe (10). The above-ground water storage tank (8) is connected to the brine well via a liquid delivery pipe (11). The upper end of the pressurized flushing pipe (10) is connected to the infusion pipe (11), and a pressurized pump (12) is provided on the infusion pipe (11). The lower end of the pressurized flushing pipe (10) extends from the outer wall of the bottom sand settling pipe (4) and is connected to the underground water storage tank (9) through the first return pipe (13). A control valve (17) is provided on the first return pipe (13). The underground water storage tank (9) and the above-ground water storage tank (8) are connected through the second return pipe (14). A return pump (15) is provided on the second return pipe (14).

2. The double-layer rotary well casing circulation flushing brine production well system according to claim 1, characterized in that: The brine extraction well system also includes a PLC control box (24), which is connected to the control terminals of the outer pipe drive motor (20), the inner pipe drive motor (21), the pressurizing pump (12), the control valve (17), and the return pump (15). The PLC control box (24) controls the well pipe rotation drive mechanism to drive the outer rotating well pipe (1) and the inner rotating well pipe (2) to rotate and close. Then, the PLC control box (24) controls the pressurizing pump (12) to introduce fresh water from the surface water storage tank (8) into the pressurized flushing pipe (10) to flush the permeable filter material layer (5). The fresh water flushing pressure is controlled between 1.0 MPa and 3.0 MPa. At the same time, the PLC control box (24) controls the control valve (17) and the return pump (15) to open, and pump the flushed water back to the surface water storage tank (8) for recycling.

3. A double-layer rotary well casing circulation flushing brine production well system according to claim 1 or 2, characterized in that: The well pipe rotation drive mechanism also includes a support frame (19), and the outer pipe drive motor (20) and the inner pipe drive motor (21) are both fixed on the support frame (19); an outer gear (6) is provided at the wellhead of the outer rotating pipe (100), and an inner gear (7) is provided at the wellhead of the inner rotating pipe (300). The output shaft of the outer pipe drive motor (20) is fixedly connected to a first transmission gear (22), which meshes with the outer gear (6). The output shaft of the inner pipe drive motor (21) is fixedly connected to a second transmission gear (23), which meshes with the inner gear (7).

4. A double-layer rotary well casing circulation flushing brine production well system according to claim 1 or 2, characterized in that: The first return pipe (13) is an annular or arc-shaped pipe, which is installed on the outer wall of the bottom sand settling pipe (4). Each pressurized flushing pipe (10) is connected to the first return pipe (13) with a filter screen (16).

5. A double-layer rotary well casing circulation flushing brine production well system according to claim 1 or 2, characterized in that: The bottom sand settling pipe (4) is a sand settling pipe cast with anti-corrosion cement, including two layers of steel pipes with smooth coating on the inner and outer surfaces and slag cement filled between the two layers of steel pipes; the bottoms of the two outer protective pipes (101) and the two inner protective pipes (301) are fixed to the top surface of the bottom sand settling pipe (4); the bottom of the outer rotating pipe (100) is rotatably connected to the bottom sand settling pipe (4) through the outer rotating well pipe bearing (104); the bottom of the inner rotating pipe (300) is rotatably connected to the bottom sand settling pipe (4) through the inner rotating well pipe bearing (304); the outer rotating well pipe bearing (104) and the inner rotating well pipe bearing (304) are both fixed to the top surface of the bottom sand settling pipe (4).

6. A double-layer rotary well casing circulation flushing brine production well system according to claim 1 or 2, characterized in that: The outer rotating pipe (100), outer pipe protection pipe (101), inner rotating pipe (300) and inner pipe protection pipe (301) are all made of steel pipe with a wall thickness of 6mm to 8mm. The pipe wall is uniformly provided with water-permeable holes with a porosity of 12% to 16%. The outer pipe isolation net (102) and the inner pipe isolation net (302) are both made of metal filter net. The outer diameter of the outer rotating well pipe (1) is 700mm to 900mm, and the outer diameter of the inner rotating well pipe (3) is 500mm to 600mm.

7. A double-layer rotary well casing circulation flushing brine production well system according to claim 1 or 2, characterized in that: The infusion pipeline (11) includes a ring or arc-shaped water pipe and a connecting pipe. The ring or arc-shaped water pipe is laid between the outer rotating pipe (100) and the inner rotating pipe (300) and is higher than the well platform (2). The ground water storage tank (8) is connected to the ring or arc-shaped water pipe through the connecting water pipe. The connecting water pipe extends from the pipe opening of the outer rotating pipe (100) into the space between the outer rotating well pipe (1) and the inner rotating well pipe (3).

8. A double-layer rotary well casing circulation flushing brine production well system according to claim 1 or 2, characterized in that: The permeable filter layer (5) is made of 5mm~10mm gravel. The pressurized flushing pipe (10) is made of UPVC pipe. A set of nozzles (18) is arranged on the pressurized flushing pipe (10) at intervals of 40cm~60cm. Each set of nozzles includes four nozzles, which are horizontally distributed at an angle of 90°. The nozzles (18) are narrow-footed solid conical nozzles.

9. A double-layer rotary well casing circulation flushing brine production well system according to claim 2, characterized in that: The total flow rate of fresh water rinsing should be controlled at 4 to 6 times the volume of the permeable filter media layer (5), and the rinsing time should be controlled at 80 min to 120 min.

10. A double-layer rotary well casing circulation flushing brine production well system according to claim 4, characterized in that: The filter screen (16) has two layers: the first layer is a 40-60 mesh stainless steel filter screen, and the second layer is a 100-120 mesh stainless steel filter screen.

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