An electro-dynamic coupling circulating well repair system

Abstract

The present invention discloses an electrokinetic coupling circulation well remediation system, which includes at least one main circulation well unit, a number of electrokinetic monitoring well units surrounding the main well unit, and a control unit. The main circulation well unit contains movable flexible electrodes; the electrokinetic monitoring well units contain movable flexible electrodes and have monitoring functions; the control unit tunes the working parameters of the main circulation well unit and the electrokinetic monitoring well units by identifying and judging the pollutants in the wells. The main circulation well unit provided by the present invention forms a three-dimensional circulating water flow around the circulation well through hydraulic circulation to remediate the pollutants in the formation. The pollutants in the formation enter the circulating water flow under the scouring of the water flow and are pumped to the surface remediation device; direct current power is applied to the flexible electrodes in the electrokinetic monitoring wells and the main circulation well to form an electric field, which promotes the pollutants in the low-permeability formation to enter the three-dimensional circulating water flow, realizing the remediation of the pollutants in the polluted site.

Description

Technical Field

[0001] The present invention relates to the technical field of in-situ remediation of composite contaminated sites, and particularly to an electrokinetic coupling circulating well remediation system. Background Art

[0002] With the development of social economy, the exploitation and utilization of groundwater resources by people have intensified. Moreover, due to the frequent occurrence of unreasonable disposal of various pollutants and process accidents, groundwater pollution is serious. Pollutants such as heavy metals enter the underground environment, causing serious pollution to groundwater. Currently, the main groundwater remediation technologies include ex-situ remediation technology, biodegradation technology, in-situ chemical oxidation technology, groundwater aeration remediation technology, permeable reactive barrier technology, etc. The groundwater circulating well remediation technology is a new remediation technology, which has significant advantages such as low cost, simple technology, and good effect. However, it is difficult to achieve efficient and rapid removal of site pollutants by using the circulating well technology alone. Especially in low-permeability formations, the water flow around the circulating well will have a bypass phenomenon, and the problems of remediation tailing and rebound are serious, which limits the effect of the circulating well technology.

[0003] Specifically, the groundwater circulating well (GCW) remediation technology is a remediation technology that can couple various methods such as in-situ air disturbance, vapor extraction, bioremediation, chemical oxidation, and electrochemistry remediation. It can simultaneously achieve in-situ remediation of contaminated sites for removing volatile organic compounds (VOCs), semi-volatile organic compounds (SVOCs), non-aqueous phase liquids (NAPLs), and some inorganic pollutants in the underground environment, and has good application prospects.

[0004] In the late 20th century, China began to study the technical methods of electrokinetic remediation of contaminated soil; the research methods of single electrokinetic remediation technology in China have tended to be perfect, and the latest research results mostly focus on the combination of electrokinetic remediation and other technologies. The common combination methods include: adding enhanced transport agents, ion exchange membrane method, combination with permeable reactive barrier or microbial technology, etc.; Hu Yang combined electrokinetic remediation technology with freeze-thaw leaching remediation technology, and had a good remediation effect on petroleum-contaminated soil [Hu Yang. Experimental study on freeze-thaw enhanced electrokinetic remediation of petroleum-contaminated soil [D]. Lanzhou University of Technology, 2021. DOI: 10.27206 / d.cnki.ggsgu.2021.001147.]; Zhang Mei et al. added electrolyte to the electrokinetic remediation system, achieving the purpose of enhancing the electrokinetic remediation of lead and cadmium contaminated soil [Zhang Mei, Wang Yanjun, Zhou Lai, etc. Study on electrokinetic remediation of lead and cadmium contaminated soil enhanced by electrolyte [J]. Energy Environmental Protection, 2022, 36(05): 53-59.].

[0005] A Chinese patent with the publication number CN113860662A discloses a groundwater circulation well structure, a repair system and a method. The system includes a circulation well, a pumping well, an aeration pipe, a suction pipe, a dosing system and a tail gas treatment device. The circulation well includes an outer well pipe and an inner well pipe arranged in sequence from outside to inside. A plurality of screen holes are provided on the pipe walls at the upper and lower ends of the outer well pipe. An isolation member is provided between the inner and outer well pipes, and the isolation member is located between the first screen hole and the second screen hole. The aeration pipe extends into the lower part of the inner well pipe, and the suction pipe communicates with the top of the circulation well; the pumping well is arranged near the circulation well, and screen holes are provided on the well wall at the lower end of the pumping well pipe, and the water suction pipe orifice therein is slightly lower than the phreatic water level. The groundwater repair method refers to the operation method of carrying out repair at the repair site based on the above repair system.

[0006] A Chinese patent with the publication number CN115321644A provides an electro-enhanced circulation well system and a method for treating halogenated hydrocarbons in groundwater by the electro-enhanced circulation well system. Halogenated hydrocarbons are negatively charged in groundwater. In the present invention, a plurality of electrode pairs are arranged on the periphery of the circulation well. When direct current is applied, the halogenated hydrocarbons migrate directionally to the vicinity of the anode around the circulation well, and the halogenated hydrocarbons are aggregated, and then the aggregated halogenated hydrocarbons are taken out through the circulation well, and the repair range of the circulation well with additional electrode pairs is expanded. At the same time, the halogenated hydrocarbons are concentrated, and the repair efficiency of the halogenated hydrocarbons can be greatly improved. The electrode pairs are arranged in the area polluted by organic matter and heavy metals, so that metal cations and other cations migrate to the vicinity of the cathode, and the organic matter and heavy metals can be separated, making it more convenient for the circulation well to treat the organic matter. The heavy metals migrating to the cathode are then treated according to the monitored concentration; the metal cations are dispersed and migrate to the cathodes around the pollution boundary, avoiding the blockage of the circulation well due to mineral precipitation.

[0007] A Chinese patent with the publication number CN110357348B provides an in-situ electrochemical circulation well repair method for chlorinated hydrocarbon-contaminated groundwater. Wells are drilled in the groundwater pollution area, and well pipes are installed in the wells. Among them, every two wells are in a group. In each group of wells, one well is used as an injection well and the other well is used as a pumping well. The top of the well pipe is open and the bottom is closed, and a plurality of small holes are opened on the lower pipe wall of the well pipe; an anode plate and a cathode plate are hung and placed into the injection well, and the anode plate and the cathode plate are respectively connected to the positive and negative poles of a power supply arranged outside the well through wires; the power supply is started to energize the anode plate and the cathode plate, and at the same time, a water pump is used to continuously pump the groundwater in the pumping well into the injection well to strengthen the groundwater flow circulation. The hydrogen and oxygen generated in the injection well diffuse into the aquifer under the action of the groundwater flow circulation to promote the chemical / microbial degradation of chlorinated hydrocarbons in the groundwater.

[0008] The existing loop well technology for contaminated site remediation has at least the following deficiencies: The loop well technology mainly relies on water flow circulation to promote the migration of polluted solutes in the three-dimensional aquifer environment around the well. However, in heterogeneous formations, especially in formations with lens-like permeable layers, water flow will bypass, making it difficult to remediate the pollution in low-permeability formations. Currently, there are no successfully replicated and popularized loop well site application cases in China. Especially for the aquifer pollution problem in formations with lens bodies, there is little research on the application of loop wells. At present, the main structures of the loop wells used are also mostly customized and purchased from foreign manufacturers, lacking the ability of independent research and development. Summary of the Invention

[0009] The object of the present invention is to provide an electrokinetic coupling loop well remediation system to solve the problems existing in the above-mentioned prior art. By combining the loop well technology and the electrokinetic technology, it promotes the migration of pollutants in the formation, especially in low-permeability formations, and promotes the pollutants to enter the three-dimensional circulating water flow and be captured by the loop well. At the same time, for low-permeability areas, the guide rail type lifter is adjusted, and the electrokinetic monitoring wells around the loop well are fully utilized. The electrodes in the loop well and the electrodes in the electrokinetic monitoring wells form an electric field, realizing precise promotion and remediation of low-permeability formations, improving the pollutant migration ability, shortening the pollutant extraction time, increasing the pollutant removal rate, and effectively solving the problem of water flow bypass in low-permeability formations by the loop well.

[0010] To achieve the above object, the present invention provides the following solution: The present invention provides an electrokinetic coupling loop well remediation system, including

[0011] One or more loop well main well units, the loop well main well units form a three-dimensional circulating water flow around the loop well through hydraulic circulation for remediating pollutants in the formation; a loop well main well monitor is arranged in the loop well main well units, and the loop well main well units are divided into upper and lower well sections without hydraulic connection by a barrier. The first well section is the well pipe above the barrier, and the second well section is the well pipe below the barrier; the loop well main well units are provided with two screen sections, and the two screen sections are respectively arranged in the two well sections. The first screen section is lower than the groundwater level of the phreatic aquifer, and the second screen section is higher than the bottom plate of the phreatic aquifer. The distribution range of pollutants is between the first screen section and the second screen section; the barrier is provided with a reserved pore allowing the water pipe to pass through, and a circle of movable flexible electrodes is arranged along the inner side of the well wall of the barrier, and the flexible electrodes are installed at the barrier.

[0012] Several electrokinetic monitoring well units surrounding the loop well main well units, and electrokinetic monitoring well monitors are arranged in the electrokinetic monitoring well units; the well walls of the electrokinetic monitoring well units are all composed of slotted pipes, and water can pass through all positions; a circle of movable flexible electrodes is also arranged on the well walls of the electrokinetic monitoring well units.

[0013] A control unit, which is used to receive the electrical signals of the electrokinetic monitoring well monitor and the main well monitor of the circulation well, identify and make control judgments on the detection results of pollutants in the well. The control unit is also used to tune the working parameters of the main well unit of the circulation well and the electrokinetic monitoring well unit, so as to promote the hydraulic transmission in the main well unit of the circulation well and repair the combined pollution of different types of pollutants.

[0014] Preferably, the first sieve section and the second sieve section are composed of several through holes cut in the wall of the main well of the circulation well. The water injection centrifugal pump pushes the circulating water to enter the first water pipe in the first well section through the second valve from the water injection main pipe. The water flows from the first water pipe to the first well section and then enters the groundwater aquifer through the first sieve section; due to the water head difference, the water flows towards the second sieve section, passes through the second sieve section and enters the second well section and then into the second water pipe, and finally enters the pumping main pipe through the first valve and is pumped out by the pumping centrifugal pump.

[0015] Preferably, there are at least 16 insulating columns evenly distributed in a circular shape and closely attached to the well wall in the first well section and the second well section. The insulating columns penetrate through the barrier upwards to the bottom area of the first sieve section and downwards to the top area of the second sieve section.

[0016] Preferably, at least 16 insulating columns evenly distributed in a circular shape and closely attached to the well wall are also arranged at the positions corresponding to the first well section and the second well section of the main well unit of the circulation well in the electrokinetic monitoring well unit. The insulating columns extend upwards to the bottom area of the first sieve section and downwards to the top area of the second sieve section.

[0017] Preferably, the insulating columns are parallel to the well wall to form insulating tracks. There are four guide rail type elevators connected to copper rings at the upper and lower parts in the insulating tracks of the main well unit of the circulation well and the electrokinetic monitoring well unit, and the flexible electrodes are closely attached to the insulating tracks; the guide rail type elevators can control the lifting of the copper rings along the insulating tracks; the diameter of the copper ring is smaller than the diameter of the circle formed by the insulating columns; the copper rings at the first sieve section of the main well unit of the circulation well and the corresponding positions in the electrokinetic monitoring well unit are connected to the DC power supply through wires.

[0018] Preferably, the flexible electrodes of the main well unit of the circulation well and the electrokinetic monitoring well unit are divided into four pieces, and the middle of the flexible electrodes is fixed at the barrier or the insulating column; the flexible electrodes of the main well unit of the circulation well and the electrokinetic monitoring well unit are located between the copper rings and the insulating columns.

[0019] Preferably, according to the different positions of the low-permeability formation, the guide rail type elevators are adjusted to control the lifting of the two copper rings in the well, so that the low-permeability formation is within the range of the two copper rings, and targeted repair of pollutants in the low-permeability formation can be realized, and pollutants in the low-permeability formation can be promoted to enter the three-dimensional hydraulic circulation area of the circulation well.

[0020] The present invention has achieved the following beneficial technical effects compared with the prior art:

[0021] The electrokinetic coupling circulation well repair system of the present invention includes at least one main circulation well unit, several electrokinetic monitoring well units surrounding the main well unit, and a control unit. The main circulation well unit forms a three-dimensional circulating water flow around the circulation well through hydraulic circulation to repair pollutants in the formation. The main well contains movable flexible electrodes; the electrokinetic monitoring well unit contains movable flexible electrodes and has a monitoring function; the control unit tunes the working parameters of the main circulation well unit and the electrokinetic monitoring well unit by identifying and judging the pollutants in the well, achieving the effects of promoting enhanced hydraulic transmission in low-permeability formations and efficiently repairing the combined pollution of different types of pollutants by the circulation well. The main circulation well unit provided by the present invention forms a three-dimensional circulating water flow around the circulation well through hydraulic circulation to repair pollutants in the formation. Pollutants in the formation enter the circulating water flow under the scouring of the water flow and are pumped to the surface repair device; direct current power is applied to the flexible electrodes in the electrokinetic monitoring well and the main circulation well to form an electric field, promoting the entry of pollutants in the low-permeability formation into the three-dimensional circulating water flow, and realizing the repair of pollutants in the polluted site. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1-A Simplified schematic diagram of the connection relationship of the module of the well group anion repair device provided by a preferred embodiment of the present invention;

[0024] Figure 1-B Simplified schematic diagram of the connection relationship of the module of the well group cation repair device provided by a preferred embodiment of the present invention;

[0025] Figure 2 Top view of the layout positions of the main circulation well unit and the electrokinetic monitoring well unit provided by a preferred embodiment of the present invention;

[0026] Figure 3 Simplified schematic diagram of the connection relationship of the module of the well group repair device provided by a preferred embodiment of the present invention;

[0027] Figure 4 Schematic diagram of the structure of the main circulation well unit provided by a preferred embodiment of the present invention;

[0028] Figure 5 Schematic diagram of the structure of the electrokinetic monitoring well unit provided by a preferred embodiment of the present invention;

[0029] Figure 6 Schematic diagram of the structure at the plane of the guide rail lifter according to a preferred embodiment of the present invention.

[0030] List of reference numerals

[0031] 1: DC power supply; 2: water pipe of the monitoring well; 3: guide rail type lifter a; 4: insulating column; 5: guide rail type lifter b; 6: well wall; 7: pumping centrifugal pump; 8: connecting negative wire; 9: main well monitor of the circulation well; 10: repair device; 11: injection centrifugal pump; 12: electrokinetic monitoring well section; 13: first valve; 14: second valve; 15: third valve; 16: fourth valve; 17: control unit; 18 connecting positive wire; 19: injection main pipe; 20: electrokinetic monitoring well monitor; 21: low permeability formation; 22: phreatic water level; 23: second screen section; 24: first screen section; 25: barrier; 26: second well section; 27: first well section; 28: first water pipe; 29: second water pipe; 30: copper ring above the barrier; 31: copper ring below the barrier; 32: flexible electrode; 33: pumping main pipe; 34: storage tank; 35: high permeability formation; 36: plume; 100: main well unit of the circulation well; 101: electrokinetic monitoring well unit; 102: well group unit composed of the circulation well and the motor monitoring well. Detailed implementation manners

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0033] The object of the present invention is to provide an electrokinetic coupling circulation well repair system to solve the problems existing in the above-mentioned prior art. By combining the circulation well technology and the electrokinetic technology, it promotes the migration of pollutants in the formation, especially in the low permeability formation, and promotes the pollutants to enter the three-dimensional circulating water flow and be captured by the circulation well. At the same time, for the low permeability area, the guide rail type lifter is adjusted, and the electrokinetic monitoring wells around the circulation well are fully utilized. The electrodes in the circulation well and the electrodes in the electrokinetic monitoring well form an electric field, realizing precise promotion and repair of the low permeability formation, improving the pollutant migration ability, shortening the pollutant extraction time, increasing the pollutant removal rate, and effectively solving the phenomenon of flow around the circulation well in the low permeability formation.

[0034] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific implementation manners.

[0035] AsFigures 1-A to 6 As shown in the figure, the present invention provides an electrokinetic coupling circulation well repair system, which includes at least one circulation well main well unit 100, several electrokinetic monitoring well units 101 surrounding the main well unit, and a control unit 17. The circulation well main well unit 100 forms a three-dimensional circulating water flow around the circulation well through hydraulic circulation to repair pollutants in the formation. The main well contains a movable flexible electrode 32. The electrokinetic monitoring well unit 101 contains a movable flexible electrode 32 and an electrokinetic monitoring well monitor 20 with monitoring functions. The control unit 17 tunes the working parameters of the circulation well main well unit 100 and the electrokinetic monitoring well unit 101 by identifying and judging the pollutants in the well unit, so as to achieve the effects of promoting the repair of pollutants in low-permeability formations and efficiently repairing different types of pollutants in the circulation well.

[0036] The circulation well main well unit 100 provided by the present invention forms a three-dimensional circulating water flow around the circulation well through hydraulic circulation to repair pollutants in the formation. Pollutants in the formation enter the circulating water flow under the scouring of the water flow and are pumped to the surface repair device. A DC power supply 1 is connected to the flexible electrodes 32 in the electrokinetic monitoring well unit 101 and the circulation well main well unit 100 to form an electric field, which promotes the entry of pollutants in the low-permeability formation into the three-dimensional circulating water flow, realizing the repair of pollutants in the polluted site.

[0037] The present invention combines the circulation well technology and the electrokinetic technology to promote the migration of pollutants in the formation, especially in low-permeability formations, and promotes the entry of pollutants into the three-dimensional circulating water flow to be captured by the circulation well. At the same time, for low-permeability areas, the guide rail type lifter is adjusted to make full use of the electrokinetic monitoring well units 101 around the circulation well. The electrodes in the circulation well main well unit and the electrodes in the electrokinetic monitoring well unit 101 form an electric field, realizing precise promotion and repair of low-permeability formations, improving the pollutant migration ability, shortening the pollutant extraction time, increasing the pollutant removal rate, and effectively solving the problem of bypass flow of the circulation well in low-permeability formations. The control unit 17 is connected to the monitor, the centrifugal pump and the valve, and adjusts the pump speed of the centrifugal pump and the opening and closing of the valve according to the monitor data to achieve the directional removal of pollutants in the polluted site.

[0038] The present invention combines the circulation well main well unit 100 and the monitoring wells (electrokinetic monitoring well units 101) around the circulation well to form a circulation well repair system suitable for complex formation conditions, short repair time and larger repair range, so as to achieve the purpose of being applicable to the repair of polluted sites in low-permeability formations.

[0039] According to a preferred embodiment, the main well unit 100 of the circulation well is provided with two screen sections, which are composed of a number of through holes cut in the well wall 6 of the circulation well; the position of the first screen section 24 of the main well unit 100 of the circulation well is lower than the groundwater level, the position of the second screen section 23 is higher than the bottom of the aquifer, and the bottom of the well is sealed; the positions of the first and second screen sections should cover the distribution range of pollutants in the aquifer, so that the circulation well can repair the entire plume as much as possible, and the three-dimensional circulation water flow can fully scour the polluted formation; the well wall 6 of the electrokinetic monitoring well unit 101 is entirely composed of slotted pipe, and water can pass through all positions. Among them, there are two positive and negative circulation water flow patterns in the two screen sections of the main well unit 100 of the circulation well, and the control unit 17 is used to regulate the centrifugal pump to realize the switching of the circulation water flow pattern.

[0040] Preferably, the switching of the circulation water flow pattern can more fully scour the underground aquifer, making it easier for pollutants to enter the three-dimensional circulation water flow and be pumped out by the circulation well for treatment, reducing the repair blind area and increasing the removal rate of pollutants.

[0041] According to a preferred embodiment, there is a barrier 25 between the upper and lower screen sections of the main well unit 100 of the circulation well to separate the first and second screen sections, forming upper and lower well sections; the barrier 25 of the main well unit 100 of the circulation well can be set in the middle of the first and second screen sections to obtain the best three-dimensional circulation water flow, with the strongest scouring ability for pollutants in the formation, and it is easier for pollutants to enter the three-dimensional circulation water flow and be pumped out by the circulation well for treatment.

[0042] The barrier 25 of the main well unit 100 of the circulation well is set at the central horizontal position of the low-permeability formation. First of all, the barrier 25 should be within the middle range of the two screen sections. The difficulty of removing pollutants in the low-permeability formation is an important factor restricting the repair time of the circulation well. By adjusting the position of the barrier 25 between the first and second screen sections and setting it at the center of the low-permeability formation, it is easier to repair the low-permeability formation, effectively reducing the repair time and accelerating the repair rate. The barrier 25 is provided with at least reserved pores allowing water pipes to pass through, and a flexible electrode 32 passes through the inner side of the well wall 6 along the barrier 25 and fixes the middle of the electrode at the barrier 25.

[0043] The electrokinetic monitoring well unit 101 is not provided with a barrier 25. The electrokinetic monitoring well has both the function of forming an electric field and monitoring. Not setting a barrier 25 can better play the monitoring function of the electrokinetic monitoring well;

[0044] According to a preferred embodiment, the bottom of the first sieve section 24 of the main well unit 100 of the circulation well, the top of the second sieve section 23, and the barrier 25 are connected by at least 16 insulating columns 4 evenly distributed in a circle along the well wall 6, for the purpose of fixing the flexible electrode 32 in combination with the rail-type elevator; the electrokinetic monitoring well unit 101 is provided at the positions corresponding to the first and second sieve sections of the main well and is connected by at least 16 insulating columns 4 evenly distributed in a circle along the well wall 6; preferably, the insulating columns 4 of the main well unit 100 of the circulation well and the electrokinetic monitoring well unit 101 are parallel to the well wall 6 to form a track, and the insulating columns 4 are distributed close to the well wall.

[0045] There are four rail-type elevators connected to copper rings up and down in the insulating tracks of the main well unit 100 of the circulation well and the electrokinetic monitoring well unit 101 to press the flexible electrode 32 tightly against the insulating track. The included angle between the connecting lines of the two opposite rail-type elevators is a right angle. The copper ring and the flexible electrode 32 are fixed on the insulating column track through the four rail-type elevators, and the DC power supply 1 is connected to the copper ring through a wire. The diameters of the copper rings of the main well unit 100 of the circulation well and the electrokinetic monitoring well unit 101 are slightly smaller than the diameter of the circle formed by the insulating columns 4, so that the flexible electrode 32 can be tightly attached to the insulating column.

[0046] The rail-type elevators of the main well unit 100 of the circulation well and the electrokinetic monitoring well unit 101 can control the lifting of the copper ring along the track, form an electric field through the electrodes in the circulation well and the electrodes in the electrokinetic monitoring well, realize precise promotion and repair of low-permeability formations, improve the pollutant migration ability, shorten the extraction time of pollutants, improve the removal rate of pollutants, and effectively solve the problem of bypass flow of the circulation well in low-permeability formations.

[0047] According to a preferred embodiment, the flexible electrode 32 of the main well unit 100 of the circulation well and the electrokinetic monitoring well unit 101 is divided into four pieces, fixed in the middle at the barrier 25 or the insulating column 4. The flexible electrode 32 is located between the copper ring and the insulating column 4. The four flexible electrodes 32 are four quarter circles respectively and form a circle around 16 insulating columns 4. The width at both ends of the flexible electrode 32 should be greater than three times the difference in diameter between the copper ring and the circle of the insulating column 4 to prevent the flexible electrode from detaching from the middle of the copper ring and the insulating column circle.

[0048] The four flexible electrodes 32 of the main well unit 100 of the circulation well and the electrokinetic monitoring well unit 101 are connected to the DC power supply 1 through the copper rings at the first sieve section of the main well of the circulation well and the corresponding positions of the electrokinetic monitoring well. When the electrokinetic field is formed, only the electrodes within the range of the upper and lower copper rings form an electric field, and the excess electrode material is tightly attached to the well wall; according to the different positions of the low-permeability formation, the rail-type elevator is adjusted to control the lifting of the two copper rings in the well, so that the low-permeability formation is within the range of the two copper rings, realizing precise repair of the pollutants in the low-permeability formation.

[0049] According to a preferred embodiment, the main well unit 100 of the circulation well is divided into upper and lower well sections by a barrier 25; the first well section 27 is the well pipe above the barrier 25, and the second well section 26 is the well pipe below the barrier 25; wherein, the first well section 27 includes a first screen section 24, a flexible electrode 32, a copper ring and a guide rail lifter; the second well section 26 is arranged in the same way as the first well section 27. Two water pipes are arranged in the well. The first water pipe 28 is near the first screen section 24, and the second water pipe 29 is near the second screen section 23.

[0050] The water pipes are powered by a centrifugal pump; the first water pipe 28 connects the first well section 27 with the surface repair device or the water storage tank 34, and valves are respectively arranged near the connection of the surface repair device or the water storage tank 34 on the water pipe; the end of the second water pipe 29 is at the second well section 26, passes through the barrier 25 and enters the first well section 27 to be connected with the water storage tank 34 or the surface repair device, and the valves are arranged in the same way as the upper well pipe.

[0051] According to a preferred embodiment, a first monitor and second to fifth monitors are arranged at the main well outlet pipe of the circulation well and the electrokinetic monitoring well; the control unit 17 is connected to the monitors, the centrifugal pump, the DC power supply 1 and the valves, and adjusts the pump speed of the centrifugal pump and the opening and closing of the valves according to the monitor data. The control unit 17 controls the opening and closing of the valves to regulate the flow channels of the water pipes, then the control unit 17 controls the water pumps connected to the water pipes, and then the control unit 17 regulates the DC power supply 1, so as to achieve the best repair effect on the pollutants in the composite formation.

[0052] Embodiment 1

[0053] This embodiment provides an electrokinetic coupling circulation well repair system. Refer to Figure 1-A , the repair device includes at least one main well unit 100 of the circulation well, four electrokinetic monitoring well units 101 surrounding the main well unit and a control unit 17. The main well unit 100 of the circulation well forms a three-dimensional circulating water flow around the circulation well through hydraulic circulation to repair the pollutants in the formation, and the main well contains a movable flexible electrode 32; the electrokinetic monitoring well unit 101 contains a movable flexible electrode 32 and has a monitoring function; the control unit 17 identifies and makes control judgments on the detection results of the pollutants in the well by receiving the electrical signals of the main well monitor 9 of the circulation well and the electrokinetic monitoring well monitor 20, and tunes the working parameters of the main well unit 100 of the circulation well and the electrokinetic monitoring well unit 101, so as to achieve the effect of promoting the enhanced hydraulic transmission in the circulation well and efficiently repairing the composite pollution of different types of pollutants.

[0054] Refer to Figure 4, the main well of the circulation well is divided into upper and lower well sections without hydraulic connection by the barrier 25; the first well section 27 is the well pipe above the barrier 25, and the second well section 26 is the well pipe below the barrier 25; the main well unit 100 of the circulation well is provided with two screen sections, which are respectively arranged in the two well sections and are composed of several through holes cut in the well wall 6 of the circulation well. The centrifugal pump 11 pushes the circulating water flow from the injection main pipe 19 through the second valve 14 into the first water pipe 28 of the first well section 27. The water flow goes from the first water pipe 28 to the first well section 27 and then enters the groundwater aquifer through the first screen section 24. Due to the head difference, the water flow flows towards the second screen section 23. The water flow passes through the second screen section 23, enters the second well section 26, then enters the second water pipe 29, passes through the first valve 13 and enters the pumping main pipe 33 and is pumped out by the centrifugal pump for pumping water.

[0055] See Figure 5 , the barrier 25 is at least provided with a reserved pore allowing the second water pipe 29 to pass through. There is a flexible electrode 32 passing through the inner side of the well wall 6 along the barrier 25 and fixing the middle of the electrode at the barrier 25. There is no barrier in the well of the electrokinetic monitoring well unit 101, and the well wall 6 is entirely composed of slotted pipes. The monitoring well water pipe 2 is arranged in the electrokinetic monitoring well. The electrokinetic monitoring well has both the function of forming an electric field and monitoring. Without setting a barrier, the monitoring function of the electrokinetic monitoring well can be better exerted; the control unit 17 controls the rotation direction and speed of the pumping and injection centrifugal pumps, so that the main well unit 100 of the circulation well forms a three-dimensional circulating water flow with reversible flow direction.

[0056] The barrier 25 of the main well unit 100 of the circulation well is arranged at the central horizontal position of the low-permeability formation 21. The barrier 25 should first be within the range between the two screen sections. The difficult removal of pollutants in the low-permeability formation 21 is an important factor restricting the repair time of the circulation well. By adjusting the position of the barrier 25 between the first and second screen sections and setting it at the center of the low-permeability formation 21, it is easier to repair the low-permeability formation 21, effectively reducing the repair time and accelerating the repair rate.

[0057] Set the position of the first screen section 24 of the main well of the circulation well more than 2 m below the phreatic water level, and the position of the second screen section 23 is higher than the bottom of the aquifer, and the bottom of the well is sealed; the positions of the first and second screen sections are set to cover as much as possible the distribution range of pollutants in the aquifer. The water flow pattern of the circulation well has two circulation modes: positive and reverse.

[0058] See Figure 2 , the layout method of the main well unit 100 of the circulation well and the monitoring well unit is square layout. One main well unit 100 of the circulation well is surrounded by four monitoring well units arranged in a square with the circulation well as the center. Preferably, the layout method can be to arrange several monitoring wells in a triangular, hexagonal or other ways.

[0059] See Figure 6, there are 16 insulating columns 4 evenly distributed in a circular shape and closely attached to the well wall 6 in the first and second well sections of the circulation well. The insulating columns 4 penetrate through the barrier 25 upwards to the bottom area of the first sieve section 24 and downwards to the top area of the second sieve section 23. Four of the insulating columns 4 are used as the tracks of the guide rail type elevator, and there are 4 guide rail type elevators in the first and second well sections respectively; in the insulating tracks of the main well and the electro-dynamic monitoring well of the circulation well, the guide rail type elevator is connected to the copper ring to closely attach the flexible electrode 32 to the insulating track. The included angle between the connecting lines of two opposite guide rail type elevators is a right angle. The copper ring and the flexible electrode 32 are fixed on the track of the insulating column 4 through four guide rail type elevators, and the DC power supply 1 is connected to the copper ring through a wire. The diameter of the copper ring in the main well and the electro-dynamic monitoring well of the circulation well is slightly smaller than the diameter of the circle formed by the insulating columns 4, so that the flexible electrode 32 can closely attach to the insulating column 4.

[0060] See Figure 6 , the flexible electrodes 32 in the main well and the electro-dynamic monitoring well of the circulation well are divided into four pieces, fixed in the middle at the barrier 25 or the insulating column 4. The flexible electrode 32 is located between the copper ring and the insulating column 4. The four flexible electrodes 32 are four quarter circles respectively, surrounding the 16 insulating columns 4 to form a circle. The width at both ends of the flexible electrode 32 should be more than three times the difference in diameter between the copper ring and the circle of the insulating columns 4 to prevent the flexible electrode 32 from detaching from the middle of the copper ring and the circle of the insulating columns 4.

[0061] The four flexible electrodes 32 of the main well unit 100 and the electro-dynamic monitoring well unit 101 of the circulation well are connected to the DC power supply 1 through the copper rings at the first sieve section 24 of the main well of the circulation well and the corresponding positions of the electro-dynamic monitoring well. When an electric field is formed by the electric power, only the electrodes within the range of the upper and lower two copper rings form an electric field, and the excess electrode material closely attaches to the well wall 6; according to the different positions of the low-permeability formation 21, the guide rail type elevator is adjusted to control the lifting of the two copper rings in the well, so that the low-permeability formation 21 is within the range of the two copper rings, realizing the precise repair of the pollutants in the low-permeability formation 21.

[0062] The control unit 17 is connected to the monitor, the DC power supply 1, the centrifugal pump and the valve. The monitor 9 of the main well of the circulation well is arranged at the outlet water pipe of the wellhead to monitor the change of pollutant concentration; the monitor 20 of the electro-dynamic monitoring well is connected to the water pipe 2 of the electro-dynamic monitoring well to monitor the change of pollutant concentration in real time. The control unit 17 receives the data from the monitor 9 of the main well of the circulation well and the monitor 20 of the electro-dynamic monitoring well, and adjusts the pump speed of the centrifugal pump, the switch of the DC power supply 1 and the opening and closing of the valve to realize the directional removal of pollutants in the polluted site.

[0063] Among them, the first well section 27 includes the first sieve section 24, the flexible electrode 32, the first water pipe 28, the copper ring and the guide rail type elevator; the second well section 26 is arranged in the same way as the first well section 27. Monitors, the injection main pipe 19, the pumping main pipe 33, the injection centrifugal pump 11, the pumping centrifugal pump 7, the repair device 10, the water storage tank 34 and the control unit 17 are arranged on the ground.

[0064] As Figure 1-A shown, the main well unit 100 of the circular well is in the mode of upward injection and downward pumping. When the centrifugal pump for pumping water 7 is started, the water level near the second well section 26 drops, and the water flow in the groundwater aquifer migrates to the vicinity of the second well section 26. Due to the action of the centrifugal pump, the water flow enters the second well section 26 through the second screen pipe, and then enters the second water pipe 29. The second water pipe 29 passes through the barrier 25, enters the main pumping pipe 33 through the first valve 13, and enters the repair device 10 through the centrifugal pump for pumping water 7; the pollutants in the groundwater are fully removed and separated through the repair device 10, and the treated groundwater enters the storage tank 34 through the pipeline; when the centrifugal pump for injection water 11 is started, due to the action of the centrifugal pump, the treated groundwater enters the main injection pipe 19 from the storage tank 34 and passes through the centrifugal pump for injection water 11, enters the first water pipe 28 through the second valve 14, and then enters the first well section 27. Due to the higher water head, the treated groundwater in the first well section 27 enters the groundwater aquifer through the first screen section 24, thus forming a three-dimensional circulating water flow to scour the polluted groundwater aquifer.

[0065] The three-dimensional circulating water flow of the circular well is prone to flow-around phenomenon in the low-permeability formation 21, making it difficult to remove the pollutants in the low-permeability formation 21. After the hydraulic circulation of the circular well is constructed, according to the formation drilling situation, the up-and-down movement of the guide-rail type lifter in the well is controlled, so that the flexible electrode 32 between the two copper rings above and below the barrier 25 includes the low-permeability formation 21, so that the electric field formed by the anode and cathode electrodes in the circular well and the electrokinetic monitoring well can accurately act on the low-permeability formation 21.

[0066] The flexible electrode 32 in the circular well is connected to the positive pole of the DC power supply 1 through the wire 18, and the electrokinetic monitoring well surrounding the circular well is connected to the negative pole of the DC power supply 1. When the voltage of the DC power supply 1 is turned on, the current starts from the positive pole of the power supply, enters the copper ring 30 above the barrier 25 in the circular well along the wire 18, and then enters the flexible electrode 32, making the flexible electrode 32 passing through the barrier 25 serve as the anode. The anions in the groundwater migrate towards the circular well, and the cations migrate towards the electrokinetic monitoring well. The electrons start from the negative pole of the power supply, enter the copper ring at the corresponding position of the electrokinetic monitoring well and the circular well along the wire, and then enter the flexible electrode 32 to make it serve as the cathode, forming an electric field between the two electrodes in the circular well and the electrokinetic monitoring well.

[0067] The control unit 17 identifies and makes control judgments on the detection results of pollutants in the well by receiving the electrical signals from the monitor. Preferably, after running for a period of time, when the change in the pollutant concentration at the monitoring well is small, the control unit 17 increases the pump speed of the centrifugal pump and the voltage of the DC power supply 1 to increase the influence range of the injection well and repair the contaminated site; preferably, after running for a period of time, when the pollutant concentration at the monitoring well is almost completely removed, the control unit 17 reduces the pump speed of the centrifugal pump and the voltage of the DC power supply 1; preferably, after running for a period of time, when the monitor shows that the pollutant remediation is completed, the control unit 17 shuts off the DC power supply 1, and the injection well continues to run for a period of time to prevent the tailing phenomenon.

[0068] The action of the electric field force is not affected by the permeability coefficient, making it easier for pollutants in the low-permeability formation 21 to migrate and enter the three-dimensional circulating water flow of the injection well more quickly, and the pollutants are more easily captured and repaired.

[0069] The main well unit 100 of the injection well and the electrokinetic monitoring well unit 101 surrounding the injection well form a set of injection well repair devices suitable for complex formation conditions, short repair time, and larger repair range, realizing precise promotion and repair of the low-permeability formation 21, improving the pollutant migration ability, shortening the pollutant extraction time, increasing the pollutant removal rate, effectively solving the problem of the injection well flowing around in the low-permeability formation 21, and thus achieving the purpose of being applicable to the repair of contaminated sites in the low-permeability formation 21.

[0070] In the repair device, the main well unit 100 of the injection well can also select the upward pumping and downward injection mode. Start the pumping centrifugal pump, the water level near the first well section 27 drops, and the water flow in the groundwater aquifer migrates to near the first well section 27. Due to the action of the centrifugal pump, the water flow enters the first well section 27 through the first screen pipe, and then enters the first water pipe 28, enters the pumping main pipe 33 through the second valve 14, and enters the repair device 10 through the pumping centrifugal pump; the pollutants in the groundwater are fully removed and separated through the repair device 10, and the treated groundwater enters the storage tank 34 through the pipeline; start the injection centrifugal pump 11. Due to the action of the centrifugal pump, the treated groundwater enters the injection main pipe 19 from the storage tank 34 and passes through the injection centrifugal pump 11, enters the second water pipe 29 through the first valve 13. The second water pipe 29 passes through the barrier 25 and then enters the second well section 26. Due to the higher water head, the treated groundwater in the second well section 26 enters the groundwater aquifer through the second screen section 23, thus forming a three-dimensional circulating water flow to scour the contaminated groundwater aquifer. The repeated content will not be elaborated.

[0071] Embodiment 2

[0072] This embodiment is a further improvement of Embodiment 1, and the repeated content will not be elaborated.

[0073] This embodiment provides a repair device for an electrokinetic coupling circulating well group in a composite formation. Refer to Figure 3 , the repair device includes at least two main circulating well units 100, six electrokinetic monitoring well units 101 surrounding the main well units, and a control unit 17. The main circulating well unit 100 forms a three-dimensional circulating water flow around the circulating well through hydraulic circulation to repair pollutants in the formation, and the main well contains a movable flexible electrode 32; the electrokinetic monitoring well unit 101 contains a movable flexible electrode 32 and also has a monitoring function; the control unit 17 identifies and makes control judgments on the detection results of pollutants in the well by receiving the electrical signals of the monitor, and tunes the working parameters of the main circulating well unit 100 and the electrokinetic monitoring well unit 101 to achieve the effect of promoting enhanced hydraulic transmission in the circulating well and efficiently repairing the combined pollution of different types of pollutants. One main circulating well unit 100 and the four electrokinetic monitoring wells surrounding it form a repair well group 102, and two or more repair well groups 102 form a repair well group.

[0074] Refer to Figure 2 , the layout of the main circulating well unit 100 and the monitoring well unit is a square layout. One main circulating well unit 100, and the four surrounding monitoring well units are arranged in a square with the circulating well as the center to form a repair well group 102, and multiple repair well groups 102 are arranged in a square to form a repair well group.

[0075] The electrokinetic coupling circulating well group repair device is applicable to the situation of a large polluted site. Multiple groups of circulating well repair well groups 102 are arranged to achieve the multi-well joint repair of the circulating well. Preferably, start the pumping and injection centrifugal pump. All the main circulating well units 100 are in the upper pumping and lower injection mode. After forming a three-dimensional circulating water flow, start the DC power supply 1 to form an electric field to promote the migration of pollutants in the low-permeability formation 21. The control unit 17 understands the repair situation through the data of the monitors in the polluted site; preferably, the pollutants migrate along the water flow direction to form a pollution plume 36. After the pollutants in the circulating well and the surrounding electrokinetic monitoring wells in the most downstream area of the pollution plume 36 are repaired, cut off the DC power supply 1 of the circulating well and the surrounding electrokinetic monitoring wells in the most downstream area of the pollution plume 36 through the control unit 17, and control the centrifugal pump of the circulating well in the most downstream area of the pollution plume 36 to continue working to form a three-dimensional circulating water flow barrier to block the diffusion of pollutants. After the pollutants in the second downstream area of the pollution plume 36 are repaired, turn off other units except the pumping and injection unit of the well group 102 in the second downstream area and the pumping and injection unit in the most downstream area to maintain the blocking effect of the three-dimensional hydraulic circulation barrier, and gradually advance until the repair is completed.

[0076] Embodiment 3

[0077] This embodiment is a further improvement of Embodiment 1 and Embodiment 2, and the repeated content will not be elaborated.

[0078] This embodiment provides an electrokinetic coupling circulation well remediation system and method, which is applicable to the remediation of contaminated multi-type composite formations. The remediation system and method at least include: a main circulation well unit 100, four electrokinetic monitoring well units 101 surrounding the main well unit, and a control unit 17. The main circulation well unit 100 forms a three-dimensional circulating water flow around the circulation well through hydraulic circulation to remediate pollutants in the formation, and the main well contains a movable flexible electrode 32; the electrokinetic monitoring well unit 101 contains a movable flexible electrode 32 and also has a monitoring function; the control unit 17 identifies and makes control judgments on the detection results of pollutants in the well by receiving the electrical signals of the monitor, and tunes the working parameters of the main circulation well unit 100 and the electrokinetic monitoring well unit 101 to achieve the effects of promoting enhanced hydraulic transmission in the circulation well and efficiently remediating the combined pollution of different types of pollutants.

[0079] When remediating a contaminated site in a composite formation, a circulation well remediation well group or well cluster is selected according to the scope of the contaminated site. When remediating a larger contaminated site, the remediation device and layout method can be referred to Figure 2 and Figure 3 ; when the contaminated site is small, the remediation device and layout method can be referred to Figure 1-A and Figure 2 . When the contaminated site only contains anionic pollutants, the remediation system and method are as shown in Embodiment 1. The anionic pollutants in the aquifer migrate towards the circulation well under the action of the electric field force, and thus enter the three-dimensional hydraulic circulation of the circulation well. Due to the action of the centrifugal pump, the water flow enters the second well section 26 through the second screen pipe, and then enters the second water pipe 29. The second water pipe 29 passes through the barrier 25, enters the pumping main pipe 33 through the first valve 13, and enters the remediation device 10 through the pumping centrifugal pump; the anionic pollutants in the groundwater are fully removed and separated through the remediation device 10, and the treated groundwater enters the storage pool 34 through the pipeline; start the injection centrifugal pump 11. Due to the action of the centrifugal pump, the treated groundwater enters the injection main pipe 19 from the storage pool 34 and passes through the injection centrifugal pump 11, enters the first water pipe 28 through the second valve 14, and then enters the first well section 27. Due to the higher water head, the treated groundwater in the first well section 27 enters the groundwater aquifer through the first screen section 24, thus forming a three-dimensional circulating water flow to scour the contaminated groundwater aquifer.

[0080] When the contaminated site only contains cationic pollutants. As Figure 1-B, the repair device, system and method can also repair the cation pollution in the contaminated groundwater. In the main well of the circulation well, the circulation mode is selected as upward pumping and downward injection, and the centrifugal pump is started to form a three-dimensional circulating water flow; the flexible electrode 32 in the circulation well is connected to the negative pole of the DC power supply 1 through a wire, and the electrokinetic monitoring wells surrounding the circulation well are connected to the positive pole of the DC power supply 1. The voltage of the DC power supply 1 is turned on. Electrons start from the negative pole of the power supply, enter the copper ring 30 above the barrier 25 in the circulation well along the wire 18, and then enter the flexible electrode 32, making the flexible electrode 32 passing through the barrier 25 act as the cathode. The cation pollutants in the groundwater migrate towards the vicinity of the circulation well, and the anions migrate towards the electrokinetic monitoring wells. The current starts from the positive pole of the power supply, enters the copper ring 30 at the corresponding position of the electrokinetic monitoring well and the circulation well along the wire, and then enters the flexible electrode 32 to make it act as the anode. An electric field is formed between the two electrodes in the circulation well and the electrokinetic monitoring well.

[0081] Preferably, the cation pollutants are affected by the electric field force in the aquifer and migrate towards the circulation well, thus entering the three-dimensional hydraulic circulation of the circulation well. Due to the action of the centrifugal pump, the water flow enters the second well section 26 through the second sieve tube, and then enters the second water pipe 29. The second water pipe 29 passes through the barrier 25, enters the pumping main pipe 33 through the first valve 13, and enters the repair device 10 through the pumping centrifugal pump; the cation pollutants in the groundwater are fully removed and separated through the repair device 10, and the treated groundwater enters the storage tank 34 through the pipeline; the injection centrifugal pump 11 is started. Due to the action of the centrifugal pump, the treated groundwater enters the injection main pipe 19 from the storage tank 34 and passes through the injection centrifugal pump 11, enters the first water pipe 28 through the second valve 14, and then enters the first well section 27. Due to the higher water head, the treated groundwater in the first well section 27 enters the groundwater aquifer through the first sieve section 24, thus forming a three-dimensional circulating water flow to scour the contaminated groundwater aquifer.

[0082] When the contaminated site contains both cation and anion pollutants. Such as Figure 1-A and 1-BAs shown, start the centrifugal pump for water extraction. The water level near the second well section 26 drops, and the water flow in the groundwater aquifer migrates to the vicinity of the second well section 26. Due to the action of the centrifugal pump, the water flow enters the second well section 26 through the second screen pipe, and then enters the second water pipe 29. The second water pipe 29 passes through the barrier 25, enters the main water extraction pipe 33 through the first valve 13, and enters the remediation device 10 through the centrifugal pump for water extraction; the anionic pollutants in the groundwater are fully removed and separated through the remediation device 10, and the treated groundwater enters the storage tank 34 through the pipeline; start the centrifugal pump for water injection 11. Due to the action of the centrifugal pump, the treated groundwater enters the main water injection pipe 19 from the storage tank 34 and passes through the centrifugal pump for water injection 11, enters the first water pipe 28 through the second valve 14, and then enters the first well section 27. Due to the higher water head, the treated groundwater in the first well section 27 enters the groundwater aquifer through the first screen section 24, thus forming a three-dimensional circulating water flow to scour the polluted groundwater aquifer.

[0083] The flexible electrode 32 in the circulating well is connected to the positive pole of the DC power supply 1 through a wire, and the electrokinetic monitoring wells surrounding the circulating well are connected to the negative pole of the DC power supply 1. Turn on the voltage of the DC power supply 1. The current starts from the positive pole of the power supply, enters the copper ring above the barrier 25 in the circulating well along the wire, and then enters the flexible electrode 32, making the flexible electrode 32 passing through the barrier 25 act as the anode. The anions in the groundwater migrate towards the vicinity of the circulating well, and the cations migrate towards the electrokinetic monitoring wells. The electrons start from the negative pole of the power supply, enter the copper ring at the corresponding position between the electrokinetic monitoring well and the circulating well along the wire, and then enter the flexible electrode 32 to make it act as the cathode. The two electrodes in the circulating well and the electrokinetic monitoring well form an electric field to remove the anionic pollutants in the polluted site.

[0084] After the remediation of the anionic pollutants in the polluted site is completed, the main well circulation mode of the circulating well is selected as up-drawing and down-injecting, and the centrifugal pump is started to form a three-dimensional circulating water flow; the flexible electrode 32 in the circulating well is connected to the negative pole of the DC power supply 1 through a wire, and the electrokinetic monitoring wells surrounding the circulating well are connected to the positive pole of the DC power supply 1. Turn on the voltage of the DC power supply 1. The electrons start from the negative pole of the power supply, enter the copper ring above the barrier 25 in the circulating well along the wire, and then enter the flexible electrode 32, making the flexible electrode 32 passing through the barrier 25 act as the cathode. The cations in the groundwater migrate towards the vicinity of the circulating well, and the anions migrate towards the electrokinetic monitoring wells. The current starts from the positive pole of the power supply, enters the copper ring at the corresponding position between the electrokinetic monitoring well and the circulating well along the wire, and then enters the flexible electrode 32 to make it act as the anode. The two electrodes in the circulating well and the electrokinetic monitoring well form an electric field to remove the cationic pollutants in the polluted site.

[0085] The flexible electrodes 32 in the circulating well and the electrokinetic monitoring well form a circle around the insulating column 4, forming a three-dimensional space electric field with the circulating well as the radiation center, which fully promotes the migration of pollutants in the low-permeability formation 21, shortens the extraction time of pollutants, improves the removal rate of pollutants, effectively solves the phenomenon of flow around the circulating well in the low-permeability formation 21, and thus achieves the purpose of being applicable to the remediation of polluted sites in the low-permeability formation 21.

[0086] It should be noted that for those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention, and any reference signs in the claims should not be regarded as limiting the claimed rights.

[0087] Specific examples are used in the present invention to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. An electrokinetic coupling cyclic well repair system, characterized in that: including one or more main circulation well units, which form a three-dimensional circulating water flow around the circulation well through hydraulic circulation for repairing pollutants in the formation; a main circulation well monitor is arranged in the main circulation well unit. The main circulation well unit is divided into upper and lower well sections without hydraulic connection by a barrier. The first well section is the well pipe above the barrier, and the second well section is the well pipe below the barrier. The main circulation well unit is provided with two screen sections, which are respectively arranged in the two well sections. The first screen section is lower than the groundwater level of the phreatic aquifer, and the second screen section is higher than the bottom plate of the phreatic aquifer. The distribution range of pollutants is between the first screen section and the second screen section. The barrier is provided with reserved pores allowing water pipes to pass through, and a circle of movable flexible electrodes is arranged along the inner side of the well wall and passes through the barrier. The flexible electrodes are installed at the barrier; several electrokinetic monitoring well units surrounding the main circulation well unit, and an electrokinetic monitoring well monitor is arranged in the electrokinetic monitoring well unit; the well wall of the electrokinetic monitoring well unit is entirely composed of slotted pipes, and water can pass through all positions; a circle of movable flexible electrodes is also arranged on the well wall of the electrokinetic monitoring well unit; the flexible electrodes in the electrokinetic monitoring well unit and the main circulation well unit are connected to a DC power supply to form an electric field; a control unit, which is used to receive the electrical signals of the electrokinetic monitoring well monitor and the main circulation well monitor and identify and control the detection results of pollutants in the well. The control unit is also used to tune the working parameters of the main circulation well unit and the electrokinetic monitoring well unit so as to promote the hydraulic transmission in the main circulation well unit and repair the combined pollution of different types of pollutants.

2. The electrokinetic coupling cyclic well repair system according to claim 1, characterized in that: The first screen section and the second screen section are composed of several through holes cut in the well wall of the main circulation well. The injection centrifugal pump pushes the circulating water flow from the injection main pipe through the second valve into the first water pipe in the first well section. The water flow goes from the first water pipe to the first well section and then enters the groundwater aquifer through the first screen section; due to the head difference, the water flow flows towards the second screen section, passes through the second screen section, enters the second well section and then enters the second water pipe, and finally enters the pumping main pipe through the first valve and is pumped out by the pumping centrifugal pump.

3. The electrokinetic coupling cyclic well repair system according to claim 1, characterized in that: There are at least 16 insulating columns evenly distributed in a circle and closely attached to the well wall in the first well section and the second well section. The insulating columns penetrate through the barrier and extend upwards to the bottom area of the first screen section and downwards to the top area of the second screen section.

4. The electrokinetic coupling cyclic well repair system according to claim 3, characterized in that: At the positions corresponding to the first well section and the second well section of the main circulation well unit in the electrokinetic monitoring well unit, there are also at least 16 insulating columns evenly distributed in a circle and closely attached to the well wall. The insulating columns extend upwards to the bottom area of the first screen section and downwards to the top area of the second screen section.

5. The electrokinetic coupling cyclic well repair system according to claim 4, characterized in that: The insulating column is parallel to the wellbore to form an insulating track. There are four guide rail type elevators at the upper and lower parts in the insulating tracks of the main well unit of the circulation well and the electrokinetic monitoring well unit, which are connected to the copper rings, and the flexible electrodes are closely attached to the insulating track. The guide rail type elevator can control the lifting of the copper ring along the insulating track. The diameter of the copper ring is smaller than the diameter of the circle formed by the insulating column. The copper rings at the first sieve section of the main well unit of the circulation well and the corresponding position of the electrokinetic monitoring well unit are connected to the DC power supply through wires.

6. The electrokinetic coupling cyclic well repair system according to claim 1, characterized in that: The flexible electrodes of the main well unit of the circulation well and the electrokinetic monitoring well unit are divided into four pieces on average, and the middle of the flexible electrode is fixed at the barrier or the insulating column. The flexible electrodes of the main well unit of the circulation well and the electrokinetic monitoring well unit are located between the copper ring and the insulating column.

7. The electrokinetic coupling cyclic well repair system according to claim 5, characterized in that: According to the different positions of the low-permeability formation, adjust the lifting of the two copper rings in the well by the guide rail type elevator so that the low-permeability formation is within the range of the two copper rings, so as to realize the targeted repair of the pollutants in the low-permeability formation and promote the pollutants in the low-permeability formation to enter the three-dimensional hydraulic circulation area of the circulation well.

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