An in-situ fracturing-enhanced oxidation remediation method for low-permeability contaminated formations based on a dedicated device

Abstract

This invention provides a method for in-situ hydraulic fracturing-enhanced oxidative remediation of low-permeability contaminated formations based on a dedicated device. The device includes a pre-fractured layer manufacturing system, a proppant-containing fractured layer manufacturing system, and an oxidative remediation system. The pre-fractured layer manufacturing system is used to manufacture the pre-fractured layer, the proppant-containing fractured layer manufacturing system is used to fracture the proppant-containing fractured layer, and the oxidative remediation system achieves rapid migration and remediation of the oxidant in the contaminated soil medium through convection and diffusion via a longitudinal arrangement of extraction, injection, and extraction. This invention integrates pre-fabricated fractures, hydraulic fracturing, and in-situ chemical oxidation, effectively promoting the steady development of in-situ hydraulic fracturing-enhanced oxidative remediation technology for low-permeability contaminated sites towards a standardized, controllable, efficient, and economical model. Furthermore, the entire equipment system is complete, the equipment is simple, the operation is straightforward, and the functions are comprehensive, effectively reducing the number of construction personnel required for contaminated site remediation and significantly lowering the professional threshold and construction costs.

Description

Technical Field

[0001] This invention relates to the field of contaminated soil remediation technology, specifically to an in-situ fracturing-enhanced oxidation remediation method for low-permeability contaminated strata based on a dedicated device. Background Technology

[0002] Rapid economic development is often accompanied by various environmental pollution problems. Since the last century, contaminated site remediation has remained a significant and urgent global environmental issue, with various remediation technologies gradually developing and improving, solving numerous challenges in contaminated site treatment. Among these, in-situ chemical oxidation is a remediation technology that injects oxidants into contaminated sites to rapidly degrade pollutants. Due to its low cost, short cycle, good effect, and simple operation, in-situ chemical oxidation remediation technology has a high proportion of field applications. However, the application of this technology in low-permeability contaminated sites is severely hindered, as the low permeability of the site greatly limits the effective diffusion and transport of oxidants, making it impossible to achieve comprehensive and rapid cleaning of the contaminated site. Based on this, researchers in this field have introduced hydraulic fracturing technology, commonly used in the oil drilling industry, into the remediation of low-permeability contaminated sites. By using hydraulic fracturing, highly permeable fracture networks are created in low-permeability strata, accelerating the transport and distribution of oxidants and increasing the oxidation remediation area in a short period of time. However, the fracture morphology created by existing hydraulic fracturing technology is affected by natural factors such as in-situ stress and water content, as well as human factors such as injection flow rate, injection method, and frequency, making it difficult to obtain controllable fracture morphology in soil media. This is why most existing fracturing technologies create fracture surfaces that extend slightly upwards, allowing only the diffusion and migration of oxidants to repair small contaminated areas around the fracture surface, resulting in extremely long overall remediation cycles. Therefore, there is an urgent need for an in-situ fracturing-enhanced oxidative remediation method that comprehensively considers the convection and diffusion effects of oxidants to achieve rapid and efficient remediation of low-permeability contaminated sites, and corresponding equipment is urgently needed for development. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides an in-situ fracturing and enhanced oxidation remediation method for low-permeability contaminated formations based on a dedicated device.

[0004] The technical solution of this invention:

[0005] A method for in-situ fracturing-enhanced oxidation remediation of low-permeability contaminated formations based on a dedicated device, wherein the dedicated device is an in-situ fracturing-enhanced oxidation remediation device for low-permeability contaminated formations, comprising a pre-fractured layer manufacturing system, a proppant-containing fractured layer manufacturing system, and an oxidation remediation system, wherein:

[0006] The pre-fractured layer manufacturing system is used to manufacture a pre-fractured layer 7 in a low-permeability contaminated formation.

[0007] The proppant-containing fracture layer manufacturing system is used to inject fracturing fluid 9 and proppant 10 into the pre-fractured layer 7 to form a regular and controllable proppant-containing fracture layer 12.

[0008] The oxidation repair system is used for in-situ chemical oxidation repair on the basis of the proppant-containing crack layer 12;

[0009] The method includes the following steps:

[0010] Step 1: Plan in advance the location of the three pre-fractured layers to be manufactured. The locations of the three pre-fractured layers are evenly spaced along the depth of the low-permeability contaminated strata.

[0011] Step 2: Use the pre-cracked layer manufacturing system to manufacture the first pre-cracked layer;

[0012] Step 3: Use the proppant-containing fracture layer manufacturing system to manufacture the first proppant-containing fracture layer;

[0013] Step 4: Following the procedures in Steps 2 and 3, create two additional proppant-supported crack layers;

[0014] Step 5: The oxidative remediation system utilizes a longitudinal arrangement of extraction, injection, and further extraction to achieve rapid migration and remediation of oxidants in contaminated soil media through convection and diffusion.

[0015] Due to the adoption of the above solution, the beneficial effects of the present invention are:

[0016] This invention integrates pre-fabricated fractures, hydraulic fracturing, and in-situ chemical oxidation, effectively promoting the steady development of in-situ fracturing and enhanced oxidation remediation technology for low-permeability contaminated sites towards a standardized, controllable, efficient, and economical model. Specifically, the pre-fractured layer manufacturing system rapidly and mechanically cuts out circular horizontal fracture layers through a pre-fractured layer manufacturing well pipe, providing a fundamental guarantee for the proppant-containing fracture layer manufacturing system to fracture out regular and controllable proppant-containing circular horizontal fracture layers through proppant injection well pipe. The oxidation remediation system achieves rapid migration and remediation of oxidants in contaminated soil media through convection and diffusion via extraction, injection, and extraction in a vertical arrangement pattern. The entire equipment system is complete, simple to operate, and fully functional, reducing the number of construction personnel required for contaminated site remediation, lowering the professional threshold, and reducing construction costs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the pre-cracked layer manufacturing system in this invention.

[0018] Figure 2 This is a front view of the cross-sectional structure of the pre-fractured layer manufacturing well casing cutting rod in the shrinkage state in this invention.

[0019] Figure 3This is a front view of the cross-sectional structure of the well casing cutting rod in the pre-fractured layer manufacturing process of the present invention, under the state of elongation.

[0020] Figure 4 This is a top view of the cross-sectional structure of the well casing cutting rod in the pre-fractured layer manufacturing process of the present invention, under elongated state.

[0021] Figure 5 Left view of the well casing cutting rod in the pre-fractured layer manufacturing process of this invention in its extended state.

[0022] Figure 6 This is a schematic diagram of the proppant-containing crack layer manufacturing system of the present invention.

[0023] Figure 7 This is a schematic diagram of the oxidation repair system in this invention.

[0024] Figure label:

[0025] 1-Pre-fractured layer manufacturing well casing, 101-Soil cutting rod storage container, 102-Soil cutting rod, 103-Oil injection pipe, 2-Backfill layer, 3-Low permeability contaminated formation, 4-Well rotation instrument, 5-Positioning anchor bolt, 6-Servo oil pump, 7-Pre-fractured layer, 8-Propionate injection well casing, 9-Fracturing fluid, 10-Propionate, 11-Pressurization pump, 12-Propionate-containing fractured layer, 1201-Propionate-containing fractured layer one, 1202-Propionate-containing fractured layer two, 1203-Propionate-containing fractured layer three, 13-Chemical injection well casing, 14-Oxidizing agent, 15-Extraction well casing one, 16-Extraction well casing two, 17-Extraction fluid container one, 18-Extraction fluid container two, 19-Vacuum pump, 20-Sealing casing. Detailed Implementation

[0026] This invention proposes an in-situ fracturing enhanced oxidation remediation device for low-permeability contaminated formations, and further proposes an in-situ fracturing enhanced oxidation remediation method for low-permeability contaminated formations based on this device.

[0027] The technical solutions provided in this application will be further described below with reference to specific embodiments and accompanying drawings. The advantages and features of this application will become clearer from the following description.

[0028] An in-situ fracturing and oxidation remediation device for low-permeability contaminated formations includes: a pre-fractured layer manufacturing system, a proppant-containing fractured layer manufacturing system, and an oxidation remediation system.

[0029] like Figure 1 As shown, the pre-fractured layer manufacturing system includes: a pre-fractured layer manufacturing well casing 1, a well rotation instrument 4, a positioning anchor bolt 5, and a servo oil pump 6; wherein:

[0030] The pre-fractured layer manufacturing well casing 1 is pressed below the surface, passes through the fill layer 2, and penetrates deep into the low-permeability contaminated stratum 3, reaching the pre-planned location for manufacturing the pre-fractured layer 7; as... Figure 2As shown, the pre-fractured layer manufacturing well casing 1 is equipped with a cutting rod storage container 101, a cutting rod 102, and an oil injection pipe 103; the cutting rod storage container 101 is located near the bottom end of the pre-fractured layer manufacturing well casing 1; the cutting rod 102 is a telescopic rod with several sections, symmetrically retracting into the cutting rod storage container 101; as shown... Figure 3 , Figure 4 and Figure 5 In its extended state, the cutting rod 102 is prism-shaped except for the last section which is a quadrangular pyramid. Moreover, the base area and length of each section of the cutting rod 102 gradually increase from the outer end to the root. One end of the oil injection pipe 103 is connected to the cutting rod storage container 101, and the other end extends to the top of the pre-fractured layer manufacturing well pipe 1, and is connected to the servo oil pump 6 during operation.

[0031] The well-rotating instrument 4 is fixed and installed on the ground by positioning anchor rods 5, and is used to fix and rotate the pre-fractured layer to manufacture the well casing 1; as an example, two positioning anchor rods 5 are provided and extend into the ground; the servo oil pump 6 is placed on the ground and connected to the oil injection pipeline 103, providing power for the extension and retraction of the cutting rod 102 in the cutting rod storage container 101.

[0032] like Figure 6 As shown, the proppant-containing fracture layer manufacturing system includes: a proppant injection well casing 8, fracturing fluid 9, proppant 10, and a pressurizing pump 11; the proppant injection well casing 8 is injected below the ground surface, passes through the fill layer 2, and penetrates into the low-permeability contaminated formation 3, reaching the location of the pre-fractured layer 7, so as to further manufacture a proppant-containing fracture layer 12 based on the pre-fractured layer 7; the fracturing fluid 9 contains proppant 10 and is stored in a fracturing fluid container located on the ground surface; the fracturing fluid 9 is connected to the proppant injection well casing 8 through a pipeline; the upper end of the fracturing fluid container is connected to the pressurizing pump 11 through a pipeline; the pressurizing pump 11 is placed on the ground to provide power for the proppant 10 to be injected into the proppant injection well casing 8 along with the fracturing fluid 9.

[0033] like Figure 7 As shown, the oxidation remediation system includes: a chemical injection well pipe 13, an oxidant 14, an extraction well pipe one 15, an extraction well pipe two 16, an extraction fluid container one 17, an extraction fluid container two 18, a vacuum pump 19, and a sealing sleeve 20.

[0034] The chemical injection well pipe 13 is pressed below the ground surface, passes through the fill layer 2 and penetrates into the low-permeability contaminated stratum 3, reaching the third proppant-containing fracture layer, namely proppant-containing fracture layer 3 1203; the oxidant 14 is stored in an oxidant container, which is set on the ground surface, and the oxidant 14 is connected to the chemical injection well pipe 13 through a pipe, and the upper end of the oxidant container is connected to the pressure pump 11 through a pipe;

[0035] The extraction well pipe 15 is pressed below the ground surface, passes through the fill layer 2, and penetrates into the low-permeability contaminated formation 3, reaching the first proppant-containing fractured layer, namely proppant-containing fractured layer 1201; the extraction well pipe 16 is pressed below the ground surface, passes through the fill layer 2, and penetrates into the low-permeability contaminated formation 3, reaching the second proppant-containing fractured layer, namely proppant-containing fractured layer 1202; one end of the extraction fluid container 17 is connected to the extraction well pipe 15 via a pipe, and the other end is connected to the vacuum pump 19 via a pipe; one end of the extraction fluid container 18 is connected to the extraction well pipe 16 via a pipe, and the other end is connected to the vacuum pump 19 via a pipe; the vacuum pump 19 is placed on the ground to provide negative pressure for extracting the extraction fluid from the extraction well pipe 15 and the extraction well pipe 16 respectively.

[0036] The proppant-containing fracture layer one 1201, proppant-containing fracture layer three 1203, and proppant-containing fracture layer two 1202 are distributed sequentially from top to bottom; the sealing sleeve 20 is pressed below the ground surface and passes through proppant-containing fracture layer one 1201, proppant-containing fracture layer three 1203, and proppant-containing fracture layer two 1202 sequentially from top to bottom, and is used to fill the vertical soil penetration channels used by the pre-fractured layer manufacturing well pipe 1 and the proppant injection well pipe 8, so as to block the connection between proppant-containing fracture layer one 1201, proppant-containing fracture layer three 1203, and proppant-containing fracture layer two 1202, and prevent dominant seepage.

[0037] The method for in-situ fracturing-enhanced oxidation remediation of low-permeability contaminated formations based on the aforementioned oxidation remediation device includes the following steps:

[0038] Step 1: Plan in advance the location of the three pre-fractured layers 7 to be manufactured. The locations of the three pre-fractured layers 7 are evenly distributed along the depth of the low-permeability contaminated strata.

[0039] Step 2: Use the pre-cracked layer manufacturing system to manufacture the first pre-cracked layer.

[0040] Place the rotating well instrument 4 on the ground and fix it with two positioning anchor rods 5 driven into the soil layer; put the pre-fractured layer manufacturing well pipe 1 into the rotating well instrument 4 and press it below the ground, then pass through the fill layer 2 and go deep into the low-permeability contaminated layer 3, until it reaches the position where the first pre-fractured layer 7 is planned to be manufactured.

[0041] A servo oil pump 6 is connected to the top of the well casing 1 manufactured in the pre-fractured layer. The servo oil pump 6 injects pressurized hydraulic oil into the cutter rod storage container 101 through the oil injection pipe 103, pushing the cutter rod 102 to extend section by section to both ends until it is fully extended.

[0042] Start the rotating well instrument 4 and control the well casing 1 for pre-fractured layer manufacturing to rotate in place. The horizontal fractured layer is created by mechanically cutting the formation through the soil cutting rod 102.

[0043] After the complete circular horizontal crack layer, i.e. the first pre-crack layer 7, is created, the servo oil pump 6 is adjusted to return oil, and the cutting rod 102 is retracted into the cutting rod storage container 101.

[0044] Then, the pre-fractured layer is pulled out to manufacture the well casing 1 and the positioning anchor rod 5, and the rotating well instrument 4 and servo oil pump 6 are cleaned up and removed from the site.

[0045] Step 3: Use a proppant-supported fracture layer fabrication system to fabricate the first proppant-supported fracture layer.

[0046] The proppant injection well pipe 8 is pressed into the vertical soil layer penetration channel used by the pre-fractured well pipe 1 along the pre-fractured layer, passing through the fill layer 2 and penetrating into the low-permeability contaminated stratum 3, until it reaches the location of the first pre-fractured layer 7.

[0047] The pressurization pump 11 is controlled to inject fracturing fluid 9 containing proppant 10 into the proppant injection well pipe 8, which then fills the first pre-fractured layer 7;

[0048] After the fracturing fluid dissipated, the first proppant-containing fracture layer 12 was successfully created, namely proppant-containing fracture layer 1201.

[0049] Then, the proppant injection well casing 8 was pulled out, and the pressurization pump 11, fracturing fluid 9 and other related equipment and materials were removed from the site.

[0050] Step 4: Referring to the operation methods in Step 2 and Step 3, create two additional proppant-containing fracture layers 12 that are evenly spaced along the depth of the low-permeability contaminated stratum, namely proppant-containing fracture layer three 1203 and proppant-containing fracture layer two 1202.

[0051] Finally, a sealing casing 20 is pressed into the vertical soil penetration channel used by the pre-fractured well casing 1 and the proppant injection well casing 8 to complete the sealing treatment of the vertical soil penetration channel and prevent dominant seepage between proppant-containing fractured layer one 1201, proppant-containing fractured layer three 1203 and proppant-containing fractured layer two 1202.

[0052] Step 5: Perform in-situ chemical oxidation remediation using the oxidation remediation system.

[0053] The extraction well pipe 15, the chemical injection well pipe 13 and the extraction well pipe 2 16 are pressed below the ground surface, pass through the fill layer 2 and penetrate into the low-permeability contaminated stratum 3, respectively connecting the proppant-containing fracture layer 1 1201, the proppant-containing fracture layer 3 1203 and the proppant-containing fracture layer 2 1202.

[0054] The pressurization pump 11 injects the oxidant 14 into the reagent injection well pipe 13 at a certain positive pressure, and quickly fills the proppant-containing fracture layer three 1203. At the same time, the vacuum pump 19 is controlled to extract the extractant from the proppant-containing fracture layer one 1201 to the extractant container one 17 through the extraction well pipe one 15, and from the proppant-containing fracture layer two 1202 to the extractant container two 18 through the extraction well pipe two 16. Therefore, a stable high hydraulic gradient is formed between the proppant-containing fracture layer three 1203 and the proppant-containing fracture layer one 1201 and the proppant-containing fracture layer two 1202, respectively, which promotes the rapid migration and remediation of the oxidant in the contaminated soil medium through convection and diffusion.

[0055] Regularly check the concentration of extractant in extractant container 17 and extractant container 28. When the concentration of extractant in extractant container 17 and extractant container 28 is equal to the concentration of oxidant 14, turn off the pressure pump 11 and vacuum pump 19, pull out extraction well pipe 15, chemical injection well pipe 13, extraction well pipe 26 and sealing casing 20, and clean up and remove the relevant equipment and materials from the site.

[0056] Soil samples were taken from the low-permeability contaminated stratum 3 for testing to determine the concentration of residual pollutants, conduct ecological and environmental analysis and evaluation, and complete site remediation.

[0057] The above description is merely a description of preferred embodiments of this application and is not intended to limit the scope of this application in any way. Any changes or modifications made by those skilled in the art based on the above-disclosed technical content should be considered as equivalent and valid embodiments and fall within the scope of protection of the technical solution of this application.

Claims

1. A method for in-situ fracturing and enhanced oxidation remediation of low-permeability contaminated formations based on a dedicated device, characterized in that, The specialized device is an in-situ fracturing and oxidation remediation device for low-permeability contaminated formations, comprising a pre-fractured layer manufacturing system, a proppant-containing fractured layer manufacturing system, and an oxidation remediation system, wherein: The pre-fractured layer manufacturing system is used to manufacture pre-fractured layers in low-permeability contaminated formations (7). The proppant-containing fracture layer manufacturing system is used to inject fracturing fluid (9) and proppant (10) into the pre-fractured layer (7) to form a regular and controllable proppant-containing fracture layer (12). The oxidation repair system is used for in-situ chemical oxidation repair on the basis of the proppant-containing crack layer (12); The method includes the following steps: Step 1: Plan in advance the location of the three pre-fractured layers to be manufactured. The locations of the three pre-fractured layers are evenly spaced along the depth of the low-permeability contaminated strata. Step 2: Use the pre-cracked layer manufacturing system to manufacture the first pre-cracked layer; Step 3: Use the proppant-containing fracture layer manufacturing system to manufacture the first proppant-containing fracture layer; Step 4: Following the procedures in Steps 2 and 3, create two additional proppant-supported crack layers; Step 5: The oxidative remediation system utilizes a longitudinal arrangement of extraction, injection, and further extraction to achieve rapid migration and remediation of oxidants in contaminated soil media through convection and diffusion. The pre-fractured layer manufacturing system includes: a pre-fractured layer manufacturing well casing (1), a well rotation instrument (4), a positioning anchor bolt (5), and a servo oil pump (6), wherein: The pre-fractured layer manufacturing well pipe (1) is pressed below the ground surface, passes through the fill layer (2) and penetrates into the low-permeability contaminated stratum (3), reaching the pre-planned location for manufacturing the pre-fractured layer (7); the pre-fractured layer manufacturing well pipe (1) is equipped with a cutting rod storage container (101), a cutting rod (102) and an oil injection pipe (103); the cutting rod storage container (101) is located near the bottom end of the pre-fractured layer manufacturing well pipe (1); the cutting rod (102) is a telescopic rod, equipped with... The cutting rod (102) is composed of several sections that are symmetrically contracted in the cutting rod storage container (101). When the cutting rod (102) is in the extended state, except for the last section which is a quadrangular pyramid, the remaining sections are quadrangular prisms. The base area and length of each section of the cutting rod (102) gradually increase from the outer end to the root. One end of the oil injection pipe (103) is connected to the cutting rod storage container (101), and the other end extends to the top of the pre-fractured layer manufacturing well pipe (1), and is connected to the servo oil pump (6) during operation. The well-rotating instrument (4) is fixed and installed on the ground by a positioning anchor (5) for fixing and rotating the pre-fractured layer to manufacture the well casing (1). The servo oil pump (6) is placed on the ground and connected to the oil injection pipe (103) to provide power for the extension and retraction of the cutting rod (102) in the cutting rod storage container (101).

2. The in-situ fracturing and enhanced oxidation remediation method for low-permeability contaminated formations based on a dedicated device as described in claim 1, characterized in that, The proppant-containing fracture layer manufacturing system includes: a proppant injection well casing (8), fracturing fluid (9), proppant (10), and a pressurization pump (11), wherein: The proppant injection well casing (8) is pressed below the ground surface, passes through the fill layer (2) and penetrates into the low-permeability contaminated stratum (3), reaching the location of the pre-fractured layer (7) so as to further create a proppant-containing fractured layer (12) based on the pre-fractured layer (7). The fracturing fluid (9) contains proppant (10) and is stored in a fracturing fluid container; the fracturing fluid (9) is connected to the proppant injection well pipe (8) through a pipeline; the upper end of the fracturing fluid container is connected to a pressurizing pump (11) through a pipeline; the pressurizing pump (11) is placed on the ground to provide power for the proppant (10) to be injected into the proppant injection well pipe (8) along with the fracturing fluid (9).

3. The in-situ fracturing and enhanced oxidation remediation method for low-permeability contaminated formations based on a dedicated device as described in claim 1, characterized in that... The oxidation remediation system includes: a chemical injection well casing (13), an oxidant (14), an extraction well casing one (15), an extraction well casing two (16), an extraction fluid container one (17), an extraction fluid container two (18), a vacuum pump (19), and a sealing casing (20), wherein: The injection well pipe (13) is pressed below the ground surface, passes through the fill layer (2) and penetrates into the low-permeability contaminated stratum (3), reaching the third proppant-containing fracture layer, namely proppant-containing fracture layer three (1203); the oxidant (14) is stored in an oxidant container, and the oxidant (14) is connected to the injection well pipe (13) through a pipe, and the upper end of the oxidant container is connected to the pressure pump (11) through a pipe; The extraction well pipe (15) is pressed below the ground surface, passes through the fill layer (2) and penetrates into the low-permeability contaminated stratum (3), reaching the first proppant-containing fracture layer, namely proppant-containing fracture layer one (1201). The extraction well pipe 2 (16) is pressed below the ground surface, passes through the fill layer (2) and penetrates into the low-permeability contaminated stratum (3), reaching the second proppant-containing fracture layer, namely proppant-containing fracture layer 2 (1202). One end of the extraction liquid container (17) is connected to the extraction well pipe (15) through a pipe, and the other end is connected to the vacuum pump (19) through a pipe. One end of the extraction liquid container two (18) is connected to the extraction well pipe two (16) through a pipe, and the other end is connected to the vacuum pump (19) through a pipe; The vacuum pump (19) is placed on the ground to provide negative pressure power for extracting the extractant from extraction well pipe one (15) and extraction well pipe two (16), respectively. The proppant-containing fracture layer one (1201), proppant-containing fracture layer three (1203), and proppant-containing fracture layer two (1202) are distributed sequentially from top to bottom; the sealing sleeve (20) is pressed below the ground surface and passes through proppant-containing fracture layer one (1201), proppant-containing fracture layer three (1203), and proppant-containing fracture layer two (1202) sequentially from top to bottom, and is used to fill the vertical soil penetration channel used by the pre-fractured layer manufacturing well pipe (1) and the proppant injection well pipe (8).

4. The in-situ fracturing and enhanced oxidation remediation method for low-permeability contaminated formations based on a dedicated device as described in claim 1, characterized in that, Step 2 includes: Place the rotating well instrument (4) on the ground and fix it with two positioning anchor rods (5) driven into the soil layer; put the pre-fractured layer manufacturing well pipe (1) into the rotating well instrument (4) and press it below the ground, then pass through the fill layer (2) and go deep into the low-permeability contaminated stratum (3) until it reaches the position where the first pre-fractured layer (7) is planned to be manufactured. A servo oil pump (6) is connected to the top of the well casing (1) in the pre-fractured layer. The servo oil pump (6) injects pressurized oil into the cutter rod storage container (101) through the oil injection pipe (103), pushing the cutter rod (102) to extend section by section to both ends until it is fully extended. Start the rotating well instrument (4) and control the well casing (1) for pre-fractured layer manufacturing to rotate in place. The horizontal fractured layer is created by mechanically cutting the formation through the soil cutting rod (102). After the complete circular horizontal crack layer, i.e. the first pre-crack layer (7), is manufactured, the servo oil pump (6) is adjusted to return oil, and the cutting rod (102) is retracted into the cutting rod storage container (101). Then, the pre-fractured layer manufacturing well casing (1) and positioning anchor rod (5) are pulled out, and the rotating well tool (4) and servo oil pump (6) are cleaned and removed from the site.

5. The in-situ fracturing and enhanced oxidation remediation method for low-permeability contaminated formations based on a dedicated device as described in claim 1, characterized in that, Step 3 includes: The proppant injection well pipe (8) is pressed into the vertical soil layer penetration channel used by the well pipe (1) in the pre-fractured layer below the ground surface, through the fill layer (2) and into the low-permeability contaminated stratum (3), until it reaches the location of the first pre-fractured layer (7); The pressurization pump (11) injects fracturing fluid (9) containing proppant (10) into the proppant injection well casing (8), thereby filling the first pre-fractured layer (7). After the fracturing fluid dissipates, the first proppant-containing fracture layer (12) is formed, namely proppant-containing fracture layer one (1201). Then, pull out the proppant injection well casing (8) and remove the booster pump (11) and fracturing fluid (9) from the site.

6. The in-situ fracturing and enhanced oxidation remediation method for low-permeability contaminated formations based on a dedicated device as described in claim 1, characterized in that, Step 4 includes: Two additional proppant-containing fracture layers (12) are created along the depth of the low-permeability contaminated strata, namely proppant-containing fracture layer three (1203) and proppant-containing fracture layer two (1202). A sealing casing (20) is pressed into the vertical soil penetration channel used by the pre-fractured well casing (1) and the proppant injection well casing (8) to complete the sealing treatment of the vertical soil penetration channel and prevent dominant seepage between proppant fracture layer one (1201), proppant fracture layer three (1203) and proppant fracture layer two (1202).

7. The in-situ fracturing and enhanced oxidation remediation method for low-permeability contaminated formations based on a dedicated device as described in claim 1, characterized in that, Step 5 includes: The extraction well pipe 1 (15), the chemical injection well pipe (13) and the extraction well pipe 2 (16) are pressed below the ground surface, pass through the fill layer (2) and penetrate into the low-permeability contaminated stratum (3), respectively connecting the proppant-containing fracture layer 1 (1201), the proppant-containing fracture layer 3 (1203) and the proppant-containing fracture layer 2 (1202). The pressurization pump (11) is controlled to inject the oxidant (14) into the reagent injection well pipe (13) under positive pressure, and quickly fill the proppant-containing fracture layer three (1203); at the same time, the vacuum pump (19) is controlled to extract the extractant from the proppant-containing fracture layer one (1201) to the extractant container one (17) through the extraction well pipe one (15), and from the proppant-containing fracture layer two (1202) to the extractant container two (18) through the extraction well pipe two (16); a stable high hydraulic gradient is formed between the proppant-containing fracture layer three (1203) and the proppant-containing fracture layer one (1201) and the proppant-containing fracture layer two (1202), respectively, which promotes the rapid migration and remediation of the oxidant in the contaminated soil medium by convection and diffusion; Regularly check the concentration of extract in extract container 1 (17) and extract container 2 (18). When the concentration of extract in extract container 1 (17) and extract container 2 (18) is equal to the concentration of oxidant (14), turn off the pressurizing pump (11) and vacuum pump (19), pull out extraction well pipe 1 (15), chemical injection well pipe (13), extraction well pipe 2 (16) and sealing casing 20, and clean up and remove the relevant equipment and materials. Soil samples were taken from the low-permeability contaminated stratum (3) for testing to determine the concentration of residual pollutants, conduct ecological and environmental analysis and evaluation, and complete site remediation.

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