Soft coal seam perforation anti-reflection device and method based on high-voltage electric pulse

Abstract

The invention discloses a high-voltage electric pulse-based soft coal seam perforation anti-reflection device and method. The high-voltage electric pulse-based soft coal seam perforation anti-reflection device comprises a pulse generation system, and the pulse generation system is connected with a high-voltage electric pulse perforation device through a high-voltage electric conveying device; the high-voltage electric pulse perforating device comprises a projectile tube storage bin, a launching window and a wire feeding device, the launching window is located between the projectile tube storage bin and the wire feeding device, a high-voltage insulated cable is arranged in the middle of the interior of the projectile tube storage bin, the outer circle of the projectile tube storage bin is a double-layer concentric metal tube, and an outer ring metal tube is arranged between the double-layer concentric metal tube. The pulse generation system is responsible for converting conventional electric energy into high-voltage pulse electric energy, providing core energy for the device, and instantaneously releasing the high-voltage pulse electric energy under the triggering of a control signal to generate strong shock waves to crack a coal seam; shock waves are generated in water through high-voltage electric pulses, shots are jetted into soft coal seam fractures, the fracture connectivity is expanded, the gas permeability of the coal seam is improved, it is guaranteed that the fractures can be kept for a long time, and support is provided for the fractures.

Description

Technical Field

[0001] This invention relates to the field of coal mine disaster management technology, specifically to a perforation permeation enhancement device and method for soft coal seams based on high-voltage electric pulses. Background Technology

[0002] High-voltage electric pulse coal seam permeability enhancement technology, as a safe, environmentally friendly, and repeatable controllable method for fracturing coal and rock, is currently in a stage of rapid development and has become an important research direction for solving the problem of efficient mining of low-permeability coalbed methane in my country. Studies have shown that the process of high-voltage electric pulse breakdown of coal and rock can be divided into four stages: electric field loading, polarization, breakdown, and stabilization. Its typical mechanisms include the electrohydraulic effect and the electrofragmentation effect. Under the action of stress waves, the pore structure of coal and rock undergoes an evolutionary pattern of pore enlargement, fracturing, penetration, and expansion of fractures, thereby improving permeability. The discharge parameters determine the degree of fracture network optimization, the electrical properties of coal and rock affect the breakdown difficulty, and the mineral distribution and pore fracture characteristics control the formation of plasma channels.

[0003] Soft, low-permeability coal seams are widely distributed in my country, characterized by high gas content and poor permeability, accounting for over 95% of high-gas and outburst-prone mines. The coal seam strength coefficient is generally less than 0.5, the permeability coefficient is only 0.01 m² / (MPa²·d), and the gas content exceeds 10 m³ / t. The coal body is loose and easily broken, making borehole collapse and drill bit jamming highly likely during drilling. The coal seams often exhibit mylonitic or fractured coal structures, crumbling into powder when rubbed between the fingers, and have extremely low compressive strength. While high-voltage electrical pulses have shown good permeability enhancement effects in conventional coal seams, the resulting fractures in soft coal seams are small and difficult to maintain, resulting in a short-lived effect.

[0004] Currently, traditional technologies have poor adaptability. When conventional hydraulic technology is applied to soft coal seams, high-pressure water can easily lead to coal softening, mudding, and water-locking effects, which in turn reduces the permeability of the coal seam. Summary of the Invention

[0005] The technical problem to be solved by this invention is: how.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0007] A perforation enhancement device for soft coal seams based on high-voltage electric pulses includes a pulse generation system, which is connected to a high-voltage electric pulse perforation device via a high-voltage electric transmission device. The high-voltage electric pulse perforation device includes a shot tube storage chamber, a firing window, and a wire feeding device. The firing window is located between the shot tube storage chamber and the wire feeding device. A high-voltage insulated cable is installed in the middle of the shot tube storage chamber, and the outer ring is a double-layer concentric metal tube. An outer ring metal tube is installed between the double-layer concentric metal tubes. One end of the high-voltage insulated cable is connected to the high-voltage insulated cable, and the other end is connected to the wire feeding device. The outer ring metal tube contains several projectile tubes; one end of the outer ring metal tube faces the launch window and the other end is fitted with a bottom cover via a spring.

[0008] This application establishes a pulse generation system, a high-voltage electric transmission device, and a high-voltage electric pulse perforation device. The pulse generation system is responsible for converting conventional electrical energy into high-voltage pulse electrical energy to provide the core energy for the device. Under the trigger of a control signal, the energy is released instantaneously to generate a strong shock wave that fractures the coal seam. The high-voltage electric pulse generates shock waves in the water and propels projectiles into the soft coal seam fractures, expanding the fracture connectivity, increasing the permeability of the coal seam, and ensuring that the fractures can be maintained for a long time, thus providing support for the fractures.

[0009] As a further aspect of the present invention: the projectile tube includes an outer capless glass bottle containing a projectile, the end of the glass bottle facing the launch window being a silicone pad, and the other end of the glass bottle facing the bottom cover having an opening.

[0010] As a further aspect of the present invention: the projectile tube includes a blank glass bottle, an iron sand glass bottle, and a ceramic abrasive glass bottle, wherein the iron sand glass bottle is located between the blank glass bottle and the ceramic abrasive glass bottle, and the ceramic abrasive glass bottle is positioned near the bottom cover, while the blank glass bottle is positioned near the launch window.

[0011] As a further aspect of the present invention: a connecting support is provided between the double-layer concentric metal tubes for supporting them, and one end of the connecting support extends out of the double-layer concentric metal tubes and connects to the wire feeding device.

[0012] As a further aspect of the present invention: the connecting support pillar adopts a metal structure, and is arranged in three groups in a ring array, all supported between double-layer concentric metal tubes, with several shot tubes distributed between two adjacent connecting supports.

[0013] As a further aspect of the present invention: the high-voltage power transmission device adopts a segmented push rod with built-in cable.

[0014] This invention also discloses a permeation enhancement method for a perforation enhancement device based on high-voltage electric pulses in soft coal seams, comprising: S1. Place N1 empty glass bottles, one iron sand glass bottle, and N ceramic glass bottles in sequence from the outlet inside the outer ring metal tube, and then seal the outlet of the outer ring metal tube with the bottom cap. S2. After drilling to the coal seam, continue drilling rock boreholes of equal length to the coal seam. After pulling out the drill bit, send the high-voltage electric pulse perforation device into the borehole, connect the high-voltage electric transmission device to send the high-voltage electric pulse perforation device to the perforation position, inject water into the hole, and seal the hole; use the pulse generation system to perforate the coal seam. S3. If the air shot, iron shot, and ceramic pellets are fired in sequence, the air shot glass bottle, iron shot glass bottle, and ceramic pellet glass bottle tube will be blasted in sequence. The air shot creates cracks in the coal seam, the iron shot expands the cracks in the coal seam, and the ceramic pellets maintain the cracks in the coal seam. S4. After perforation, remove the push rod of the high-voltage power transmission device, leave the cable in the borehole, remove the outer end of the cable, and seal the borehole.

[0015] As a further aspect of the present invention: the iron sand particle size is M2, and the ceramsite particle size is M1, wherein M2>M1.

[0016] As a further aspect of the present invention: the total number of glass bottles that cause coal seam breakage after the addition of the projectile is determined in the laboratory to be Nmax; In step S3, during the processes of empty bullet injection, iron shot injection, and ceramic pellet injection, the total number of empty bullet glass bottles, iron shot glass bottles, and ceramic pellet glass bottles is less than Nmax.

[0017] As a further aspect of the present invention: the minimum perforation voltage intensity Wmax is determined in the laboratory when the coal seam is broken after the addition of the projectile; In step S3, the perforation voltage intensity during the empty ejection hole, iron shot perforation, and ceramsite perforation processes is all less than Wmax.

[0018] Compared with the prior art, the beneficial effects of the present invention are: First, this application sets up a pulse generation system, a high-voltage electric transmission device, and a high-voltage electric pulse perforation device. The pulse generation system is responsible for converting conventional electrical energy into high-voltage pulse electrical energy to provide the core energy for the device. Under the trigger of the control signal, the energy is released instantaneously to generate a strong shock wave that fractures the coal seam. The high-voltage electric pulse generates shock waves in the water and sprays projectiles into the soft coal seam fractures, expanding the fracture connectivity, increasing the permeability of the coal seam, and ensuring that the fractures can be maintained for a long time, thus providing support for the fractures.

[0019] Secondly, this application first uses a blank ejector hole to blast a blank glass bottle to create cracks in the coal seam; then it uses an iron shot hole to blast an iron shot glass bottle to expand the cracks in the coal seam; finally, it uses a ceramic pellet hole to blast a ceramic pellet glass bottle tube to maintain the cracks in the coal seam, and then continues to use electric blasting to maintain the flow rate, thereby maintaining the cracks generated during the permeability enhancement process of the soft coal seam. Finally, in this application, the mesh size of the iron sand is greater than that of the ceramsite. The larger the mesh size, the smaller the diameter. Since the mesh size of the iron sand is greater than that of the ceramsite, the diameter of the ceramsite is greater than that of the iron sand. Therefore, when the iron sand enters the coal seam, it causes cracks in the coal seam, and the ceramsite, which has a larger diameter than the iron sand, can block the cracks and maintain the cracks. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the perforation enhancement device for soft coal seams based on high-voltage electric pulses according to an embodiment of the present invention; Figure 2 This is a cross-sectional view of the high-voltage electric pulse perforation device according to an embodiment of the present invention; Figure 3 This is a cross-sectional view of the bullet tube storage compartment according to an embodiment of the present invention; Figure 4 This is a flowchart of a perforation enhancement device for soft coal seams based on high-voltage electric pulses, according to an embodiment of the present invention. Figure 5 This is a schematic diagram of the wire feeding device according to an embodiment of the present invention; Figure 6 This is a cross-sectional schematic diagram of the drum magazine feeding system according to an embodiment of the present invention; Explanation of reference numerals in the attached figures: 1. Pulse generation system; 2. Water injection and sealing system; 3. High-voltage electric transmission device; 4. High-voltage electric pulse perforation device; 401. Projectile tube storage compartment; 402. Launching window; 403. Wire feeding device; 4011 High-voltage insulated cable; 4012 Double-layer concentric metal tube; 4013 Outer ring metal tube; 4014 Spring; 4015 Shot tube; 40151 Glass bottle; 40152 Shot; 4016 Silicone pad; 4017 Bottom cover; 4018 Connecting support; 4031 Vibration power supply system; 4032 Solenoid valve; 4033 Drum feed system. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Example 1 Reference Figure 1 A perforation enhancement device for soft coal seams based on high-voltage electric pulses includes a pulse generation system 1, a water injection sealing system 2, a high-voltage electric transmission device 3, and a high-voltage electric pulse perforation device 4.

[0023] The pulse generation system 1 is responsible for converting conventional electrical energy into high-voltage pulse electrical energy, providing the core energy for the device. This energy is released instantaneously upon triggering a control signal, generating a strong shock wave that fractures the coal seam. The water injection sealing system 2 keeps the high-voltage pulse perforation device 4 submerged in water.

[0024] The high-voltage power transmission device 3 can be an insulation layer installed on the outside of the inner conductor of a high-voltage insulated cable, or it can be a segmented built-in cable push rod. The insulation strength of the high-voltage power transmission device 3 varies according to the needs, with an increase of more than 30kV in underground coal seams and more than 50kV in surface coal seams.

[0025] The high-voltage electric pulse perforation device 4 generates a shock wave by electrically detonating a metal wire to launch a projectile.

[0026] Reference Figure 2 and Figure 3 The high-voltage electric pulse perforation device 4 includes a shot tube storage chamber 401, a firing window 402, and a wire feeding device 403, wherein the firing window 402 is located between the shot tube storage chamber 401 and the wire feeding device 403; the outer shells of the shot tube storage chamber 401 and the wire feeding device 403 are both made of stainless steel.

[0027] The shot tube storage chamber 401 is equipped with a high-voltage insulated cable 4011 in the middle and a double-layer concentric metal tube 4012 on the outer ring. An outer ring metal tube 4013 is provided between the double-layer concentric metal tubes 4012. The high-voltage insulated cable 4011 and the high-voltage insulated cable 3 are made of the same material and are connected by a quick connection structure. The other end of the high-voltage insulated cable 4011 is connected to the metal wire in the wire feeding device 403. The pulse generation system 1 converts conventional electrical energy into high-voltage pulse electrical energy and uses the high-voltage insulated cable 4011 to drive the metal wire to explode, thereby achieving the purpose of shot tube blasting and generating a strong shock wave to crack the coal seam.

[0028] Reference Figure 2 and Figure 3 The high-voltage insulated cable 4011 is located inside the double-layer concentric metal tube 4012. The outer ring metal tube 4013 has an outlet on the side near the emission window 402. The other side of the outer ring metal tube 4013 is equipped with a bottom cover 4017, which has threads that can be opened.

[0029] Reference Figure 2 and Figure 3 A spring 4014 is installed on the inner side of the outer ring metal tube 4013 near the base. Several projectile tubes 4015 are provided inside the outer ring metal tube 4013. n projectile tubes 4015 form a group. The base of the projectile tube 4015 faces the launch window 402. The projectile tube 4015 is made of glass. The outer part is an open glass bottle 40151, which contains projectiles 40152. One end of the glass bottle 40151 is a silicone pad 4016, and the other end is open. The open end is set towards the bottom cover 4017. The projectile tube 4015 consists of empty glass canisters, iron shot glass canisters, and ceramic pellet glass canisters. Several empty glass canisters and several ceramic pellet glass canisters are provided, and one iron shot glass canister is provided. The empty glass canisters are positioned near the firing window 402, and the ceramic pellet glass canister is positioned near the bottom cover 4017. The iron shot glass canister is located between the empty glass canisters and the ceramic pellet glass canister. During subsequent perforation, the explosion of the empty glass canisters causes the drill hole to create a crack. Upon explosion, the glass and silicone pad break apart and eject from the firing window 402. After the iron shot glass canister explodes, the iron shot enters the drill hole to widen the crack. Finally, after the ceramic pellet glass canister explodes, the ceramic pellet enters the drill hole to maintain the crack. The number of empty glass canisters and ceramic pellet glass canisters is not limited in this application and can be adjusted on-site according to the desired effect. The bottom cover 4017 is opened, and the empty glass canisters, iron shot glass canisters, and ceramic pellet glass canisters are sequentially pushed into the outer ring metal tube 4013 through the bottom cover opening.

[0030] Spring 4014 can press and push the projectile out of the projectile tube storage chamber 401. The projectile 40152 is divided into iron sand and ceramic particles of different sizes. The connecting support 4018 is installed in the middle of the double-layer concentric metal tube 4012 to support the double-layer concentric metal tube 4012. There are three connecting supports 4018 in this article, which are equally distributed in the middle of the double-layer concentric metal tube 4012. They can also be set to six, nine or twelve, etc., according to actual needs. This application does not limit them. The specific parameters can be adjusted according to the on-site construction effect.

[0031] Reference Figure 2 and Figure 3 The middle of the launch window 402 contains the end contact of the high-voltage insulated cable 4011 and the metal wire of the wire feeding device 403. The outer ring consists of a spring 4014 that pushes out the shot tube 4015 and a connecting support 4018. The connecting support 4018 fixes the shot tube storage chamber 401 and the metal wire feeding device 403. After the explosion, the metal wire feeding device 403 continuously delivers the metal wire to the launch window 402.

[0032] Reference Figure 5 and Figure 6The wire feeding device 403 has a sealed area separated by a partition for installing a vibration power supply system 4031. On the other side of the partition, a solenoid valve 4032 and a magazine feeding system 4033 are installed. The vibration power supply system 4031 is equipped with a vibration sensor. When it senses the vibration of a wire explosion, it supplies power to the solenoid valve 4032 for 30 seconds. The solenoid valve 4032 is connected to the vibration power supply system 4031 via a cable and is located in the middle of one side of the magazine feeding system 4033. Under the action of the vibration power supply system 4031, the solenoid valve 4032 pushes the wire in the spiral groove towards the launch window 402, making contact with the end contact of the high-voltage insulated cable 4011. The high-voltage insulated cable 4011 then detonates the wire, achieving the purpose of blasting the projectile tube. The magazine feeding system 4033 has a spiral groove inside, a spring installed on the outer shell, and a push rod on the other side. Several wires are placed inside the spiral groove. When the solenoid valve 4032 is reset, the spring drives the drum magazine feeding system 4033 to rotate. The push rod can push the metal wire toward the center of the spiral groove to occupy the position of the metal wire pushed out by the solenoid valve 4032. After the metal wire explodes, the next metal wire can be pushed in the same way. It should be noted that the drum magazine feeding system 4033 is consistent with the principle of the drum magazine in the current field.

[0033] Example 2 High-voltage electrical pulse-based perforation permeation enhancement method for soft coal seams: Drilling into the coal seam can be done on the surface, underground, or through the coal seam, or through the roof and floor.

[0034] In the laboratory, determine the minimum perforation voltage intensity W1 that causes fractures in the coal seam and the number of glass bottles N1 (the number of empty glass bottles). In the laboratory, determine the minimum perforation voltage intensity W2 that causes cracks in the coal seam after the projectile is launched, and the number of glass bottles N1+1 (the number of empty projectile glass bottles + iron sand glass bottles, with one iron sand glass bottle). In the laboratory, the minimum perforation voltage intensity Wmax and the number of glass bottles Nmax (Nmax is the limit number of glass bottles for coal seam breakage) were determined for coal seam breakage. Then, the number of ceramic glass bottles N (ceramic) was determined. <Nmax-N1-1。

[0035] During construction, in the outer ring metal pipe 4013, the projectile pipes 4015 are sequentially placed with N1 empty bullet glass bottles, one iron sand glass bottle with an iron sand particle size mesh number of M2, and N(Tao) ceramsite glass bottles with a ceramsite particle size mesh number of M1 from the outlet. Note that the mesh number M2 is greater than the mesh number M1; it should be noted that the larger the particle size mesh number, the smaller the diameter. Since the mesh number of iron sand particles is greater than that of ceramsite particles, the diameter of ceramsite particles is greater than that of iron sand particles. Therefore, when the iron sand particles enter the coal seam, cracks are generated in the coal seam, and the ceramsite with a diameter larger than the iron sand particles can just block the cracks to achieve the effect of maintaining the cracks.

[0036] After the drilling construction encounters coal, continue to construct rock drill holes with the same length as the coal encounter length. After the drill is lifted, send the high-voltage electric pulse perforation device 4 into the drill hole, and connect the high-voltage electric transmission device 3 to send the high-voltage electric pulse perforation device 4 to the perforation position; use the water injection sealing system 2 to inject water into the hole and seal the hole; use the pulse generation system 1 to perforate the coal seam.

[0037] Perform empty bullet perforation in sequence. N1 empty bullet glass bottles are detonated, and the voltage intensity at this time is W1; then perform iron sand perforation. N1 + 1 (the number of empty bullet glass bottles + iron sand glass bottles) glass bottles are detonated, and the value range of the voltage intensity W at this time is: 0.8 Wmax > W > W2 (that is, the voltage intensity is between generating cracks and generating fragmentation in the coal seam); finally, perform ceramsite perforation. In the ceramsite perforation step, the coal seam cannot be fragmented, and the number of ceramsite glass bottles N(Tao) < Nmax - N1 - 1, and the voltage intensity at this time is intensity < 0.8 Wmax.

[0038] It should be noted that the specific voltage intensity and the number of glass bottles can be adjusted according to the actual situation on site, and this application does not make any limitations.

[0039] In order to better maintain the cracks in the coal seam, after perforation, remove the push rod of the high-voltage electric transmission device 3, keep the cable in the drill hole, remove the outer end of the cable, and seal the drill hole. Every certain period of time (such as 10 minutes), connect the outer end of the cable to perform high-voltage electric pulse permeability enhancement without metal wires. After the flow rate of the extraction drill hole in the affected area (the width and length of the coal seam are between 10 and 20 m) decreases, connect the outer end of the cable to perform high-voltage electric pulse permeability enhancement without metal wires.

[0040] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A perforation permeation enhancement device for soft coal seams based on high-voltage electric pulses, characterized in that, Includes a pulse generation system (1), which is connected to a high-voltage pulse perforation device (4) via a high-voltage electric transmission device (3); The high-voltage electric pulse perforation device (4) includes a shot tube storage chamber (401), a firing window (402), and a wire feeding device (403). The firing window (402) is located between the shot tube storage chamber (401) and the wire feeding device (403). The shot tube storage chamber (401) has a high-voltage insulated cable (4011) in the middle and a double-layer concentric metal tube (4012) on the outer ring. An outer ring metal tube (4013) is provided between the double-layer concentric metal tubes (4012). One end of the high-voltage insulated cable (4011) is connected to the high-voltage electric transmission device (3), and the other end is connected to the wire feeding device (403). The outer ring metal tube (4013) is provided with a plurality of projectile tubes (4015); one end of the outer ring metal tube (4013) facing the launch window (402) is open, and the other end is fitted with a bottom cover (4017) by a spring.

2. The perforation and permeation enhancement device for soft coal seams based on high-voltage electric pulses according to claim 1, characterized in that: The projectile tube (4015) includes an outer open glass bottle (40151) containing a projectile (40152). One end of the glass bottle (40151) facing the launch window (402) is a silicone pad (4016), and the other end of the glass bottle (40151) facing the bottom cap glass bottle (4017) has an opening.

3. The perforation and permeation enhancement device for soft coal seams based on high-voltage electric pulses according to claim 1, characterized in that: The projectile tube (4015) includes a blank glass bottle, an iron sand glass bottle, and a ceramic particle glass bottle, wherein the iron sand glass bottle is located between the blank glass bottle and the ceramic particle glass bottle, and the ceramic particle glass bottle is located near the bottom cover (4017), while the blank glass bottle is located near the launch window (402).

4. The perforation and permeation enhancement device for soft coal seams based on high-voltage electric pulses according to claim 1, characterized in that: A connecting support (4018) is provided between the double-layer concentric metal tubes (4012) for supporting them. One end of the connecting support (4018) extends out of the double-layer concentric metal tubes (4012) and is connected to the wire feeding device (403).

5. The perforation and permeation enhancement device for soft coal seams based on high-voltage electric pulses according to claim 4, characterized in that: The connecting support column (4018) adopts a metal structure and is arranged in three sets in a ring array, all supported between double-layer concentric metal tubes (4012). Several shot tubes (4015) are distributed between two adjacent connecting supports (4018).

6. The perforation and permeation enhancement device for soft coal seams based on high-voltage electric pulses according to claim 1, characterized in that: The high-voltage power transmission device (3) uses a segmented push rod with built-in cable.

7. A method for enhancing permeability in soft coal seams using a high-voltage electrical pulse-based perforation device as described in any one of claims 1-6, characterized in that, include: S1. Place N1 empty glass bottles, one iron sand glass bottle, and N (ceramic) ceramic glass bottles in the outer ring metal tube (4013) from the outlet in sequence, and then seal the outlet of the outer ring metal tube (4013) with the bottom cover (4017). S2. After drilling to the coal seam, continue drilling rock boreholes of equal length to the coal seam. After starting drilling, send the high-voltage electric pulse perforation device (4) into the borehole, connect the high-voltage electric transmission device (3) to send the high-voltage electric pulse perforation device (4) into the perforation position, inject water into the hole and seal the hole; use the pulse generation system (1) to perforate the coal seam. S3. If the air shot, iron shot, and ceramic pellets are fired in sequence, the air shot glass bottle, iron shot glass bottle, and ceramic pellet glass bottle tube will be blasted in sequence. The air shot creates cracks in the coal seam, the iron shot expands the cracks in the coal seam, and the ceramic pellets maintain the cracks in the coal seam. S4. After perforation, remove the push rod of the high-voltage power transmission device (3), leave the cable in the hole, remove the outer end of the cable, and seal the hole.

8. The perforation permeation enhancement method for soft coal seams based on high-voltage electric pulses according to claim 7, characterized in that: The iron sand has a particle size of M2 and the ceramsite has a particle size of M1, where M2 > M1.

9. The perforation permeation enhancement method for soft coal seams based on high-voltage electric pulses according to claim 7, characterized in that: In the laboratory, the total number of glass bottles required to cause coal seam breakage after the addition of projectiles is determined to be Nmax. In step S3, during the processes of empty bullet injection, iron shot injection, and ceramic pellet injection, the total number of empty bullet glass bottles, iron shot glass bottles, and ceramic pellet glass bottles is less than Nmax.

10. The method for enhancing the perforation permeability of soft coal seams based on high-voltage electrical pulses according to claim 7, characterized in that: In the laboratory, the minimum perforation voltage intensity Wmax was determined to be required for coal seam fracturing after the addition of projectiles. In step S3, the perforation voltage intensity during the empty ejection hole, iron shot perforation, and ceramsite perforation processes is all less than Wmax.

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