Contaminated soil treatment method and system based on horizontal well injection in-situ reaction zone

Abstract

The invention relates to the technical field of contaminated soil treatment, in particular to a contaminated soil treatment method and system based on a horizontal well injection in-situ reaction zone. The method comprises the steps of planning an expected treatment area according to a pollution area and an underground environment condition; obtaining a governable range of a single horizontal well; according to the expected treatment area and the treatment range of the single horizontal well, the arrangement number and arrangement mode of the horizontal wells and the arrangement distance between the horizontal wells when the number of the horizontal wells is multiple are determined, and a horizontal well group is arranged in the planned expected treatment area; selecting a repairing agent according to pollutant components, and injecting the repairing agent into the expected treatment area by utilizing the arranged horizontal well group, so that the area dip-dyed by the repairing agent is close to the expected treatment area; and the area dip-dyed by the repairing agent is an in-situ reaction zone. According to the method, the optimal in-situ reaction zone is planned in advance based on the pollution area and the underground environment condition, and the remediation agent is combined, so that efficient treatment of stock pollution and risk management and control of incremental pollution can be realized.

Description

Technical Field

[0001] The present application relates to the technical field of contaminated soil treatment, and in particular to a contaminated soil treatment method based on horizontal well injection in-situ reaction zone and a contaminated soil treatment system based on horizontal well injection in-situ reaction zone. Background Art

[0002] With the rapid development of social economy and industrialization, the pollution problem of industrial sites has become increasingly serious, among which organic pollution is particularly prominent and has the characteristics of high concentration, high toxicity, and poor water solubility. Generally speaking, pollutants enter the soil through leakage, sedimentation or other means to form pollution sources, and migrate downward into the groundwater under the action of gravity and surface water infiltration. Then, they continue to spread to the surroundings and downstream with the flow of groundwater to form a pollution plume, thus forming a contaminated site that evolves over time. If these contaminated sites are not repaired and risk controlled in a timely manner, they will cause far-reaching harm to the environment and human health. Therefore, it is of great significance to adopt targeted technologies and materials to achieve long-term and effective risk control of contaminated sites.

[0003] In the field of site pollution remediation, horizontal wells, as core engineering technologies, have functions such as reagent injection, hot air injection, and multiphase extraction. For example, the in-situ remediation method for contaminated soil and groundwater disclosed in publication number CN114309053A, in which the horizontal well has the function of reagent injection, and the contact area between the remediation agent and the contaminated medium is increased by increasing the contact area between the horizontal well and the contaminated layer, thereby improving the remediation efficiency. CN114345915A discloses a system and method for in-situ remediation of organic contaminated soil. The invention utilizes the injection and extraction functions of the horizontal well to remove pollutants through the cyclic effects of injecting hot steam, multiphase extraction, and injecting oxidizing agents. CN113753981A discloses a method for treating quaternary groundwater and soil pollution. This method utilizes the advantage of the large contact area between the horizontal well and the contaminated area, and extracts the contaminated water in the contaminated area through the horizontal well and treats it.

[0004] The above removal of existing pollution is a necessary link in the treatment of contaminated sites. However, groundwater presents the characteristics of stratified flow in the site. The free pollutants in the upstream groundwater will migrate and diffuse with the flow of groundwater. At the same time, accompanied by the desorption of pollutants in the soil medium, the incremental pollution problem of remediation and treatment becomes a key issue in the treatment process. Therefore, in addition to the remediation work, the risk control of contaminated sites for incremental pollution has become the research focus of site pollution control. As an important technology for site pollution risk control, the in-situ reaction zone can be implemented on site, avoiding the risks and costs brought about by sampling, transportation and treatment. In addition, the in-situ reaction zone technology can achieve adaptive repair by selecting different reaction media, microorganisms and reaction conditions according to the characteristics of the pollutants and the requirements of treatment, and has greater flexibility. For example, the columnar reaction zone structure and method for risk control and repair of contaminated plots disclosed in Publication No. CN108526205A, the invention is to construct at least one row of reaction wells perpendicular to the flow direction of groundwater in the contaminated plot downstream of the contaminated plot, and to construct an in-situ reaction zone in combination with the reagent material filled in the reaction well. During the treatment process, the long-term control and repair of the contaminated site is achieved by replacing the internal materials. However, the number of wells required to construct an in-situ reaction zone by vertical wells is large, and the filled reagents are prone to form preferential flow in vertical wells that penetrate heterogeneous formations, affecting the integrity of the in-situ reaction zone construction.

[0005] In summary, in the field of contaminated site remediation, based on the technical advantages of horizontal wells in injection and extraction, it can basically meet the removal of groundwater stock pollution. At the same time, the in-situ reaction zone technology has application value in the risk control of incremental site pollution. However, for the coexistence of stock pollution and incremental pollution on the site, the existing technology is still insufficient. Summary of the invention

[0006] The purpose of the embodiments of the present application is to provide a method and system for the treatment of contaminated soil based on horizontal well injection in-situ reaction zones.

[0007] In order to achieve the above-mentioned objectives, the first aspect of the present application provides a method for treating contaminated soil by injecting an in-situ reaction zone through a horizontal well, the method comprising: obtaining the underground environmental conditions at the location of the contaminated soil; obtaining the pollutant composition and the contaminated area of ​​the contaminated soil; planning a desired treatment area according to the contaminated area and the underground environmental conditions; obtaining the treatable range of a single horizontal well; determining the number and method of laying out the horizontal wells and the spacing between the horizontal wells when there are multiple horizontal wells according to the desired treatment area and the treatable range of the single horizontal well; laying out a horizontal well group in the planned desired treatment area according to the determined number, method and spacing of the horizontal wells; selecting a repair agent according to the pollutant composition, and injecting the repair agent into the desired treatment area using the laid out horizontal well group so that the area impregnated with the repair agent is close to the desired treatment area; wherein the area impregnated with the repair agent is the in-situ reaction zone.

[0008] Based on the first aspect, in some embodiments of the present application, the planning of the desired treatment area according to the contaminated area and the underground environmental conditions includes: judging whether the location of the contaminated soil meets the conditions for laying horizontal wells according to the underground environmental conditions; if the conditions for laying horizontal wells are met, the desired treatment area is planned to completely cover the entire contaminated area.

[0009] Based on the first aspect, some embodiments of the present application also include: if the conditions for laying horizontal wells are not met, the groundwater flow direction of the contaminated area is obtained; along the groundwater flow direction, the desired treatment areas are planned upstream and downstream of the contaminated area respectively.

[0010] Based on the first aspect, in some embodiments of the present application, the selected repair agents include: high-efficiency repair agents and long-acting repair agents; the repair agents are injected into the desired treatment area using a well-arranged horizontal well group, including: injecting high-efficiency repair agents into the desired treatment area using a well-arranged horizontal well group; after completing the injection of the high-efficiency repair agent, monitoring the physical and chemical indicators of the contaminated area, and determining the injection time of the long-acting repair agent based on the changes in the physical and chemical indicators; injecting the long-acting repair agent into the desired treatment area using the well-arranged horizontal well group within the determined injection time.

[0011] Based on the first aspect, in some embodiments of the present application, the method further includes: setting monitoring wells around and in the middle of the contaminated area, and the monitoring wells are used to monitor the physical and chemical indicators of the contaminated area.

[0012] Based on the first aspect, in some embodiments of the present application, the high-efficiency repair agent is an in-situ oxidation repair agent, an in-situ reduction repair agent or an in-situ microbial repair agent; the active ingredient in the in-situ oxidation repair agent is a combination of one or more of persulfate, potassium permanganate and hydrogen peroxide; the active ingredient in the in-situ reduction repair agent is a combination of one or two of ferrous sulfate and nano zero-valent iron; the active ingredient in the in-situ microbial repair agent is a combination of one or more of Bacillus licheniformis, Bacillus subtilis, Dehalogenococcus, Shewanella, and anaerobic white rot fungi.

[0013] Based on the first aspect, in some embodiments of the present application, the effective ingredient in the long-acting repair agent is a combination of one or more of a supplementary repair agent, a pH adjuster, a microbial carbon source, and an oxygen-releasing material.

[0014] Based on the first aspect, in some embodiments of the present application, the method also includes: acquiring environmental data; predicting the future spread range of the current contaminated area based on the environmental data; and planning the desired treatment area according to the predicted spread range and the treatable range of a single horizontal well.

[0015] Based on the first aspect, in some embodiments of the present application, the environmental data includes on-site soil quality, groundwater level, groundwater direction and groundwater flow rate.

[0016] Based on the first aspect, in some embodiments of the present application, the horizontal well group is located in a homogeneous formation.

[0017] In the second aspect, the present application provides a contaminated soil treatment system using horizontal well injection in-situ reaction zones, including: a horizontal well group construction unit, including: a first module, used to obtain the underground environmental conditions of the location of the contaminated soil; a second module, used to obtain the pollutant components and contaminated areas of the contaminated soil; a third module, used to plan the desired treatment area according to the contaminated area and the underground environmental conditions; a fourth module, used to obtain the treatable range of a single horizontal well; a fifth module, used to determine the number and method of horizontal well layout and the layout spacing between the horizontal wells when there are multiple horizontal wells according to the desired treatment area and the treatable range of a single horizontal well; a horizontal well group layout unit, used to layout the horizontal well group in the planned desired treatment area according to the determined number, method and spacing of the horizontal wells; a repair agent injection unit, used to use the laid horizontal well group to inject a repair agent corresponding to the pollutant component into the desired treatment area, so that the area impregnated with the repair agent is close to the desired treatment area; wherein the area impregnated with the repair agent is the in-situ reaction zone.

[0018] Based on the second aspect, in some embodiments of the present application, the repair agent injection unit includes: a repair agent storage tank for storing the repair agent; a stirring device for evenly stirring the repair agent injected into the horizontal well; and a pump system for transporting the evenly stirred repair agent to the contaminated area through the horizontal well.

[0019] Based on the second aspect, in some embodiments of the present application, it further includes: a monitoring unit for monitoring the physical and chemical indicators of the polluted area.

[0020] The contaminated soil treatment method and system based on horizontal well injection in-situ reaction zone provided in this application have at least the following beneficial effects:

[0021] 1) Compared with vertical wells, it avoids large-scale soil excavation and construction, reducing the risk of implementing site pollution control in production enterprises with densely distributed equipment and facilities;

[0022] 2) Compared with the method of using vertical wells to construct in-situ reaction zones, the use of horizontal well technology reduces the number of wells to be built and reduces the cost of well construction;

[0023] 3) Based on the contaminated area and underground environmental conditions, the optimal expected treatment area (in-situ reaction zone) is planned in advance, and combined with the repair agent, it can achieve both efficient treatment of existing pollution and risk control of incremental pollution.

[0024] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the accompanying drawings:

[0026] Figure 1 The application diagram of the contaminated soil treatment system of the embodiment of the present application is schematically shown;

[0027] Figure 2 A schematic diagram of the horizontal layout of a horizontal well group in an embodiment of the present application is shown;

[0028] Figure 3 A schematic diagram of the cross layout of horizontal well groups in an embodiment of the present application is shown;

[0029] Figure 4 A schematic diagram of the vertical arrangement of a horizontal well group in an embodiment of the present application is shown;

[0030] Figure 5 The schematic diagram of the layout of the horizontal well group for treating the contaminated site 1 in the embodiment of the present application is shown schematically;

[0031] Figure 6 The schematic diagram of the layout of the horizontal well group for treating the contaminated site 2 in the embodiment of the present application is shown schematically;

[0032] Figure 7 The schematic diagram of the layout of the horizontal well group for treating the contaminated site three in the embodiment of the present application is shown schematically;

[0033] Figure 8 The schematic diagram of the vertical well group layout for treating the polluted site 1 in the comparative example of the present application is shown schematically.

[0034] Description of Reference Numerals

[0035] 1-Horizontal well group; 2-Remediation agent injection unit; 3-Monitoring unit. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the specific implementation methods described herein are only used to illustrate and explain the embodiments of the present application, and are not used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0037] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), such directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0038] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0039] Example 1

[0040] This embodiment provides a method for treating contaminated soil by injecting an in-situ reaction zone into a horizontal well, the method comprising:

[0041] S1. Obtain the underground environmental conditions at the location of the contaminated soil;

[0042] Specifically, in this embodiment, the underground environment of the location of the contaminated soil needs to be explored first to determine whether the location is suitable for laying horizontal wells. For example, contaminated soil is often located under some industrial buildings, and there may be some complex underground pipeline systems. Rash excavation may easily cause pipeline breakage or leakage, so it is necessary to determine whether the horizontal well can be laid near the contaminated soil.

[0043] S2. Obtain the pollutant composition and contaminated area of ​​the contaminated soil;

[0044] In this step, it is necessary to determine the pollutant composition of the contaminated soil so that the right medicine can be prescribed in the subsequent steps. In addition, it is also necessary to determine the contaminated area, that is, the scope of the contaminated soil (here refers to the three-dimensional scope rather than the plane scope), to provide a theoretical basis for the subsequent determination of the number and distribution of horizontal wells.

[0045] S3. Plan the desired treatment area based on the contaminated area and underground environmental conditions;

[0046] For example, if in step S1, it is determined that the location of the contaminated soil has the conditions for horizontal deployment according to the underground environmental conditions, then it can be considered that the desired treatment area completely covers the entire contaminated area. For example, if in step S1, it is determined that the location of the contaminated soil does not have the conditions for horizontal deployment according to the underground environmental conditions, then it can be considered to plan the desired treatment area (especially the downstream) upstream and downstream of the (groundwater flow) in the contaminated area to intercept the further spread of pollutants.

[0047] Among them, the formation of the desired treatment area depends on the arrangement of horizontal wells and the impregnation of the repair agent.

[0048] S4. Obtain the manageable range of a single horizontal well;

[0049] In this embodiment, the repair agent is injected into the underground contaminated area by utilizing the process of horizontal well drilling. The repair agent will diffuse around the axis of the horizontal well. Since the positions of the laid horizontal wells are relatively fixed, the influence range of the repair agent injected into a single horizontal well is limited. The treatable range in this step can be understood as the above-mentioned range of infection of the repair agent.

[0050] S5. Determine the number and arrangement method of the horizontal wells and the arrangement spacing between the horizontal wells when there are multiple horizontal wells according to the expected treatment area and the treatable range of a single horizontal well;

[0051] Since it is expected that the (three-dimensional) area of ​​the in-situ reaction zone formed at the end can be as close as possible to the desired treatment area, the spacing between the horizontal wells can be determined according to the treatment range of a single horizontal well, and then the number and layout of the horizontal wells can be determined in combination with the size and structural characteristics of the desired treatment area. The layout methods include but are not limited to parallel layout (such as Figure 2 As shown), cross layout (as shown Figure 3 as shown) and vertically (as shown Figure 4 as shown) and other methods.

[0052] S6. Arrange a horizontal well group in the planned desired treatment area according to the determined arrangement quantity, arrangement method and arrangement spacing of the horizontal wells;

[0053] S7. Select a repair agent according to the pollutant composition, and use the arranged horizontal well group to inject the repair agent into the desired treatment area so that the area impregnated by the repair agent is close to the desired treatment area; wherein the area impregnated by the repair agent is the in-situ reaction zone.

[0054] The advantages of using horizontal wells in this embodiment are: (1) Horizontal wells are easier to construct in relatively uniform formations, which weakens the preferential flow effect during the injection diffusion process and ensures the effective construction of the in-situ reaction zone. (2) The construction of the in-situ reaction zone based on horizontal well injection can avoid large-scale soil excavation and construction, and reduce the risk of implementing site pollution control in production enterprises with densely distributed equipment and facilities; (3) Compared with the method of using vertical wells to construct in-situ reaction zones, the use of horizontal well technology reduces the number of wells built and reduces the cost of well construction.

[0055] Example 2

[0056] For the repair agent in Example 1, it can be mainly divided into two categories in this embodiment, specifically including: high-efficiency repair agent and long-term repair agent. Different repair agents can be matched according to the composition of pollutants and the degree of pollution to form a variety of action modes. Among them, the high-efficiency repair agent includes in-situ oxidation repair agent, in-situ reduction repair agent and in-situ microbial repair agent; the in-situ oxidation repair agent selects any one or more of oxidants such as persulfate, potassium permanganate, hydrogen peroxide, etc. as the effective ingredient; the in-situ reduction repair agent selects one or two of ferrous sulfate and nano zero-valent iron as the effective ingredient; the in-situ microbial repair agent selects one or more of Bacillus licheniformis, Bacillus subtilis, Dehalogenated Coccidioides, Shewanella, and anaerobic white rot fungi as the effective ingredient. After the high-efficiency repair agent is injected to initially form the in-situ reaction zone, a special long-term repair agent is injected into the horizontal well. According to the composition of the pollutants, supplementary repair agents, pH adjusters, microbial carbon sources, oxygen-releasing materials and other ingredients are selected, and the type of repair agent in the injection stage is matched to make a special long-term repair agent with a sustained release function. After injection, the purpose of long-term risk control of contaminated sites can be achieved by supplementing the in-situ reaction zone with remediation agents, adjusting the pH of the underground environment, and enhancing the activity of microorganisms.

[0057] Since the action time, injection timing and injection method of high-efficiency repair agents and long-term repair agents are different, the impregnation process of the repair agent mainly includes two situations: 1) For high-efficiency repair agents, the high-efficiency repair agents are injected into the contaminated area by high-pressure injection during the horizontal well drilling process, and then diffuse from the injection point to the surrounding areas; 2) For long-term repair agents, after the horizontal well is formed, the long-term repair agent is sent to the contaminated area through the channel provided by the horizontal well, and then diffuses to the surrounding areas with the horizontal well as the center.

[0058] Specifically, the injection steps of the two repair agents are as follows:

[0059] A1. Use the laid horizontal well group to inject high-efficiency repair agent into the desired treatment area;

[0060] A2. After injecting the high-efficiency repair agent, monitor the physical and chemical indicators of the polluted area and determine the injection time of the long-term repair agent based on the changes in the physical and chemical indicators;

[0061] A3. Use the laid out horizontal well group to inject long-term repair agent into the desired treatment area within the determined injection time.

[0062] Among them, the injection time can be determined by monitoring the physical and chemical indicators in the contaminated area. Specifically, the physical and chemical indicators include the redox point, pH value and groundwater pollutant concentration in the contaminated area. For example, when it is detected that the groundwater pollutant concentration has not dropped to the preset value after a period of injection of the high-efficiency repair agent, additional repair agents (long-term repair agents) can be added. Furthermore, the detection of the above physical and chemical indicators can be achieved by setting monitoring wells around and in the middle of the contaminated area. Here, reference can be made to the existing monitoring methods, which will not be elaborated here.

[0063] Example 3

[0064] In this application, the essence of soil remediation is to use the biochemical reaction between the remediation agent and the pollutants to achieve neutralization or generate harmless substances, but usually this process takes a long time, during which the pollutants may spread. In order to avoid the pollutants from spreading beyond the scope of the in-situ reaction zone, resulting in the diffused pollutants being unable to be contacted by the remediation agent, this embodiment considers predicting the future diffusion range of the polluted area based on the current polluted area and the surrounding environment data, and then planning the expected treatment area based on the future diffusion range and the treatable range of a single horizontal well. Exemplary, the polluted area in the next two years is predicted so that the expected treatment area completely covers the predicted polluted area.

[0065] The environmental data include on-site soil quality, groundwater level, groundwater direction and groundwater flow rate.

[0066] Example 4

[0067] This embodiment provides a contaminated soil treatment system using horizontal well injection in-situ reaction zone, such as Figure 1 As shown, the system comprises:

[0068] Horizontal well group 1;

[0069] A horizontal well group 1 construction unit is used to construct a horizontal well group 1, and the horizontal well group 1 construction unit includes:

[0070] The first module is used to obtain the underground environmental conditions at the location of the contaminated soil;

[0071] The second module is used to obtain the pollutant composition and contaminated area of ​​the contaminated soil;

[0072] The third module is used to plan the desired remediation area based on the contaminated area and underground environmental conditions;

[0073] The fourth module is used to obtain the manageable range of a single horizontal well;

[0074] The fifth module is used to determine the number and method of horizontal well layout and the layout spacing between horizontal wells when there are multiple horizontal wells according to the expected treatment area and the treatable range of a single horizontal well;

[0075] The sixth module is used to lay out the horizontal well group 1 in the planned expected treatment area according to the determined layout quantity, layout method and layout spacing of the horizontal wells;

[0076] The repair agent injection unit 2 uses the arranged horizontal well group 1 to inject the pre-selected repair agent into the desired treatment area, so that the area impregnated by the repair agent is close to the desired treatment area; wherein the area impregnated by the repair agent is the in-situ reaction zone.

[0077] Specifically, the repair agent injection unit 2 includes: a repair agent storage tank for storing the repair agent; a stirring device for evenly stirring the repair agent injected into the horizontal well; and a pump system for delivering power for efficient repair agent injection during the horizontal well drilling process and for the subsequent long-term repair agent addition process.

[0078] The repair agent injection unit 2 is arranged at the horizontal wellhead position on the ground (such as Figure 1 As shown in the figure, it includes a repair agent storage tank, a stirring device, a pump system and a delivery pipeline. The repair agent stirring device is used to ensure that the injected material is in a mixed and homogeneous state; the pump system should have a pressure control function based on PLC feedback regulation. During the injection stage, the pressure in the well is detected and the output pressure of the pump is adjusted (the output pressure must be greater than the pressure in the well to ensure the smooth delivery of the repair agent); the delivery pipeline needs to have a certain degree of corrosion resistance, and is used for direct contact with pollutants and the delivery of repair agents with different characteristics.

[0079] Furthermore, the system also includes a monitoring unit 3. Specifically, the detection unit includes a detection well for monitoring the physical and chemical indicators of the polluted area, wherein the physical and chemical indicators include indicators such as dissolved oxygen, redox point, pH value, temperature and groundwater pollutant concentration in the monitoring well.

[0080] Furthermore, the monitoring unit 3 also includes a drilling data monitoring module, in which the Beidou high-precision positioning system and the drill bit status sensing system are integrated, which are used to monitor the real-time position, shape, drilling direction and other information of the drill bit during the drilling process, and then guide and control the drilling direction of the well drilling bit. In this way, the horizontal well group 1 (including the number of layouts, layout methods and layout spacing) planned in advance can be completed accurately and efficiently.

[0081] Example 5

[0082] Based on the methods and systems provided in the above embodiments 1 to 4, in this embodiment, a certain contaminated soil is treated, as follows:

[0083] Through the on-site investigation of an organic pollution site, it was determined that the main pollutants in the pollution site are petroleum hydrocarbons. The treatment range is 40m*30m, and the pollutants are horizontally distributed in the 4-6m underground stratum. The soil on site is sandy soil and silty sand, the groundwater level is 4.5m, the groundwater direction is 322° northwest, and the groundwater flow rate is 0.03m / d.

[0084] According to the above investigation results, five horizontal wells were arranged horizontally. The horizontal wells were arranged along the direction of groundwater flow, with a horizontal spacing of 5m to form a horizontal well group. Figure 5 The drilling entry and exit points are selected, and the well completion parameters of each section of the horizontal well are designed according to the distribution of the contaminated area.

[0085] The injection unit is set at the excavation point. After the horizontal well drilling stage is completed, the end of the drill pipe is connected to the reaming drill bit, and the reaming drill bit is connected to the injection nozzle of the injection unit. The effective ingredient of the high-efficiency repair agent in the injection stage is hydrogen peroxide. Finally, the horizontal well screen casing unit is connected. The well pulling back process begins, during which the in-situ repair agent is radially injected using the injection nozzle according to the drill bit position.

[0086] Five monitoring wells are set up around and in the middle of the contaminated area. By monitoring the redox points, pH value and groundwater pollutant concentration in the monitoring wells, the injection time of the long-acting remediation agent is determined and the overall remediation effect is evaluated.

[0087] According to the changes in physical and chemical indicators and pollutant concentration monitoring data, long-term repair agents are injected. The effective ingredient of the long-term repair agent is slow-release sodium persulfate, which plays a role in supplementing electron acceptors and maintaining underground redox potential. Some data of monitoring wells in the polluted area after the implementation of the overall project are shown in Table 1 below.

[0088] Table 1 Geophysical and chemical indicators and pollutant concentration monitoring data

[0089]

[0090] The redox potential was maintained at a high level during the treatment period, the concentration of petroleum hydrocarbon pollutants decreased significantly within 30 days, and no tail rebound phenomenon occurred within 90 days.

[0091] Example 6

[0092] Based on the methods and systems provided in the above embodiments 1 to 4, in this embodiment, a certain contaminated soil is treated, as follows:

[0093] Through the on-site investigation of an organic pollution site, it was determined that the main pollutant in the pollution site was benzene, and the pollution source was located at a pipeline leakage point in the site (repair work has been completed). Through the necessary pollutant migration simulation research, the diffusion distribution of the pollution plume in the next two years was depicted. According to the on-site construction conditions, the treatment range was delineated as 78m*58m, and the treatment range was within the 3-9m underground stratum. The soil on site was sandy soil and silty sand, the groundwater level was 4m, the groundwater direction was 280° west, and the groundwater flow rate was 0.18m / d.

[0094] According to the above investigation and research results, three horizontal wells of different depths are arranged in a cross pattern. The intersection of the horizontal wells is located at the center of the pollution source, and the vertical spacing between the wells is 3m, forming a horizontal well group as shown in the following figure. Figure 6 The drilling entry and exit points are selected, and the well completion parameters of each section of the horizontal well are designed according to the distribution of the contaminated area.

[0095] An injection unit is set up at the excavation point. After the horizontal well drilling phase is completed, the end of the drill pipe is connected to the reaming drill bit, and the reaming drill bit is connected to the injection nozzle of the injection unit. The effective component of the high-efficiency repair agent in the injection phase is a microbial agent. Finally, the horizontal well screen casing unit is connected. The well pulling back process begins. During this period, the in-situ repair agent is radially injected using the injection nozzle according to the drill bit position. After the injection phase is completed, the long-term repair agent is injected. The material components include stabilizers, oxygen release agents, pH regulators, and growth factors, which play a role in regulating the microbial growth environment.

[0096] Four monitoring wells were set up around and in the middle of the contaminated area to monitor geophysical and chemical indicators in the monitoring wells and the concentration of groundwater pollutants. Some data of the monitoring wells in the contaminated area after the overall project was implemented are shown in Table 2 below.

[0097] Table 2 Geophysical and chemical indicators and pollutant concentration monitoring data

[0098]

[0099] During the treatment period, dissolved oxygen was maintained at a high level, the toluene concentration decreased by 92.6% in 90 days, the xylene concentration decreased by 93.0% in 90 days, and there was no tailing rebound phenomenon within 180 days.

[0100] Example 7

[0101] Based on the methods and systems provided in the above embodiments 1 to 4, in this embodiment, a certain contaminated soil is treated, as follows:

[0102] Through an on-site investigation of an organic pollution site, it was determined that the main pollutant in the pollution site was petroleum hydrocarbons, and the pollution source was located at a pipeline leakage point in the site (repair work has been completed). Due to the complex underground pipeline system at this location, according to the on-site construction conditions, a pollution risk prevention and control project was selected 40m downstream of the groundwater at this point. The upstream treatment range was delineated as 110m*30m, and the downstream treatment range was 130m*30m. The treatment range was within the 3-8m underground stratum. The soil on site was sand and silt, the groundwater level was 4.2m, the groundwater flow direction was from northwest to southeast, and the groundwater flow rate was 0.10m / d.

[0103] According to the above investigation and research results, two horizontal wells of different depths are arranged vertically in the upstream perpendicular to the direction of groundwater flow, with a vertical spacing of 5m, for the purpose of rapid restoration of the polluted area; two horizontal wells of different depths are arranged vertically in the downstream perpendicular to the direction of groundwater flow, with a vertical spacing of 5m, to form a pollution risk control surface, with reducing the site pollution risk as the main governance goal, forming a horizontal well group as shown in the attached Figure 7 shown.

[0104] The injection unit is set at the excavation point. After the horizontal well drilling phase is completed, the end of the drill pipe is connected to the reaming drill bit, and the reaming drill bit is connected to the injection nozzle of the injection unit. During the injection phase, the upstream well composition of the high-efficiency repair agent is hydrogen peroxide, and the downstream well composition is sodium persulfate. Then the horizontal well screen casing unit is connected. The backhaul well process begins, during which the in-situ repair agent is radially injected using the injection nozzle according to the drill bit position.

[0105] Four monitoring wells are set up around and in the middle of the contaminated area. By monitoring the geophysical and chemical indicators and groundwater pollutant concentrations in the monitoring wells, the injection time of the long-acting remediation agent is determined and the overall remediation effect is evaluated.

[0106] According to the changes in geophysical and chemical indicators and pollutant concentration monitoring data, a long-term repair agent was injected into the downstream well group. The effective component of the material is slow-release sodium persulfate. Some data of the monitoring wells after the implementation of the overall project are shown in Table 3 below.

[0107] Table 3 Geophysical and chemical indicators and pollutant concentration monitoring data

[0108]

[0109] The redox potential was maintained at a high level during the treatment period, the concentration of petroleum hydrocarbon pollutants decreased by more than 95.1% within 30 days, and there was no tail rebound phenomenon within 90 days.

[0110] Comparative Example 1

[0111] Corresponding to Example 5, under the same site conditions, the vertical well direct push injection method was used to construct the in-situ reaction zone. Figure 8 As shown. Sodium persulfate was selected as the first injection repair agent. Some data of the monitoring wells after the overall project was implemented are shown in Table 4 below.

[0112] Table 4 Geophysical and chemical indicators and pollutant concentration monitoring data

[0113]

[0114] Using this method, the agent response time is long during the treatment cycle, the pollutant concentration decreases slowly and the tailing problem is obvious.

[0115] It should be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of further restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0116] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for treating contaminated soil by injecting an in-situ reaction zone into a horizontal well, characterized in that: The method comprises: Obtain the underground environmental conditions at the location of the contaminated soil; Obtain the pollutant composition and contaminated area of ​​contaminated soil; Plan the desired remediation area based on the contaminated area and underground environmental conditions; Obtain the manageable range of a single horizontal well; Determine the number and method of horizontal well layout and the spacing between horizontal wells when there are multiple horizontal wells according to the expected treatment area and the treatable range of a single horizontal well; According to the determined number, method and spacing of horizontal wells, horizontal well groups are laid out in the planned desired treatment area; A repair agent is selected according to the composition of the pollutants, and the repair agent is injected into the desired treatment area using a well-arranged horizontal well group, so that the area impregnated by the repair agent is close to the desired treatment area; wherein the area impregnated by the repair agent is the in-situ reaction zone.

2. The method for treating contaminated soil by injecting in-situ reaction zones in horizontal wells according to claim 1, characterized in that: The desired treatment area is planned according to the contaminated area and underground environmental conditions, including: Determine whether the location of the contaminated soil is suitable for laying horizontal wells based on the underground environmental conditions; If the conditions for laying horizontal wells are met, the desired treatment area will be planned to completely cover the entire polluted area.

3. The method for treating contaminated soil by injecting in-situ reaction zones in horizontal wells according to claim 2, characterized in that: Also includes: If the conditions for laying horizontal wells are not met, the groundwater flow direction in the contaminated area is obtained; Along the direction of groundwater flow, the desired treatment areas are planned upstream and downstream of the polluted area.

4. The method for treating contaminated soil by using horizontal well injection in-situ reaction zone according to claim 1, characterized in that: The selected repair agents include: high-efficiency repair agents and long-lasting repair agents; Use the arranged horizontal well group to inject the repair agent into the desired treatment area, including: Use the laid out horizontal well group to inject high-efficiency repair agents into the desired treatment area; After the injection of the high-efficiency repair agent is completed, the physical and chemical indicators of the polluted area are monitored, and the injection time of the long-acting repair agent is determined based on the changes in the physical and chemical indicators; The long-acting repair agent is injected into the desired treatment area using the arranged horizontal well group within the determined injection time.

5. The method for treating contaminated soil by using horizontal well injection in-situ reaction zone according to claim 4 is characterized in that: The method further comprises: Monitoring wells are set around and in the middle of the polluted area, and the monitoring wells are used to monitor the physical and chemical indicators of the polluted area.

6. The method for treating contaminated soil by using horizontal well injection in-situ reaction zone according to claim 4, characterized in that: The high-efficiency repair agent is an in-situ oxidation repair agent, an in-situ reduction repair agent or an in-situ microbial repair agent; The active ingredient in the in-situ oxidation repair agent is a combination of one or more of persulfate, potassium permanganate and hydrogen peroxide; The active ingredient in the in-situ reduction repair agent is one or a combination of ferrous sulfate and nano zero-valent iron; The active ingredients in the in-situ microbial repair agent are a combination of one or more of Bacillus licheniformis, Bacillus subtilis, Dehalogenobacterium spp., Shewanella spp., and anaerobic white rot fungi.

7. The method for treating contaminated soil by using horizontal well injection in-situ reaction zone according to claim 4, characterized in that: The effective ingredients in the long-acting repair agent are a combination of one or more of a supplementary repair agent, a pH regulator, a microbial carbon source, and an oxygen-releasing material.

8. The method for treating contaminated soil by using horizontal well injection in-situ reaction zone according to claim 1, characterized in that: The method further comprises: Obtain environmental data; Predict the future spread of current contaminated areas based on environmental data; Plan the desired treatment area based on the predicted diffusion range and the treatable range of a single horizontal well.

9. The method for treating contaminated soil by using horizontal well injection in-situ reaction zone according to claim 8, characterized in that: The environmental data include on-site soil quality, groundwater level, groundwater direction and groundwater flow rate.

10. The method for treating contaminated soil by using horizontal well injection in-situ reaction zone according to any one of claims 1 to 9, characterized in that: The horizontal well group is arranged in a relatively homogeneous formation.

11. A contaminated soil treatment system using horizontal well injection in-situ reaction zone, characterized in that: include: Horizontal well group construction unit, including: The first module is used to obtain the underground environmental conditions at the location of the contaminated soil; The second module is used to obtain the pollutant composition and contaminated area of ​​the contaminated soil; The third module is used to plan the desired remediation area based on the contaminated area and underground environmental conditions; The fourth module is used to obtain the manageable range of a single horizontal well; The fifth module is used to determine the number and method of horizontal well layout and the layout spacing between horizontal wells when there are multiple horizontal wells according to the expected treatment area and the treatable range of a single horizontal well; A horizontal well group layout unit is used to layout the horizontal well group in the planned expected treatment area according to the determined layout quantity, layout method and layout spacing of the horizontal wells; The repair agent injection unit is used to inject a repair agent corresponding to the pollutant composition into the desired treatment area using the arranged horizontal well group, so that the area impregnated by the repair agent is close to the desired treatment area; wherein the area impregnated by the repair agent is the in-situ reaction zone.

12. The contaminated soil treatment system using horizontal well injection in-situ reaction zone according to claim 11 is characterized in that: The repair agent injection unit comprises: A repair agent storage tank, used for storing the repair agent; A stirring device, used to evenly stir the repair agent injected into the horizontal well; A pump system is used to transport the well-mixed remediation agent to the contaminated area through a horizontal well.

13. The contaminated soil treatment system using horizontal well injection in-situ reaction zone according to claim 11 is characterized in that: Also includes: Monitoring unit, used to monitor the physical and chemical indicators of the polluted area.

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