High-voltage electric pulse synergistic acidizing fracturing coal seam anti-reflection device and method

Abstract

The invention discloses a high-voltage electric pulse synergistic acidizing fracturing coal seam anti-reflection device and method.The high-voltage electric pulse synergistic acidizing fracturing coal seam anti-reflection device comprises a hole packer, the hole packer comprises a high-pressure acid injection pipeline, the middle of the high-pressure acid injection pipeline is sleeved with an expansion capsule, the two ends of the expansion capsule are each provided with a fixing end, and a connecting pipe is arranged at the rear end of the high-pressure acid injection pipeline; each high-voltage electrode comprises a high-voltage electrode A section and a high-voltage electrode B section, mounting holes are formed in the two sides of the fixed end at the front end in the radial direction, springs are fixedly arranged at the bottoms in the mounting holes, the two high-voltage electrode A sections penetrate through the expansion capsule, and the front ends of the two high-voltage electrode A sections abut against the high-voltage electrode B sections to achieve electric connection. And the rear end of the high-voltage electrode section A is connected with the pulse circuit. Mineral substances can be corroded through the acidizing fracturing fluid, a coal seam hole fracture network can be dredged, the subsequent high-voltage electric pulse discharging difficulty is reduced, then high-voltage electric pulse discharging is carried out for fracturing, and the coal rock fracturing efficiency is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of coal seam fracturing, and particularly relates to a high-voltage electric pulse collaborative acid fracturing device and method for enhancing the permeability of coal seams. Background Art

[0002] The development and utilization of coal seam gas is of great strategic significance for both the safe extraction of coal and environmental protection. This is not only because gas has a high calorific value when burned and emits less waste gas during combustion, making it an efficient clean energy source. More importantly, in coal extraction activities, gas is also a disaster source that causes mine dynamic accidents. In addition, the gas discharged into the air is also a greenhouse gas, causing pollution to the atmospheric environment. However, low permeability problems are common in coal seams in China, making it difficult to extract gas. Therefore, it is of profound significance to use artificial permeability enhancement technology to effectively enhance the permeability of coal seams to achieve the goal of efficient extraction of coal seam gas and fully utilize the value of coal resources.

[0003] To improve the conductivity and permeability of coal seams, the industry has long studied and proposed various coal seam permeability enhancement methods, including borehole pressure relief, hydraulic fracturing, CO 2 fracturing, and deep-hole pre-splitting controlled blasting, etc. Among them, the borehole pressure relief method can only extract gas at one atmospheric pressure in low-permeability coal seams, resulting in low gas extraction efficiency; the hydraulic fracturing method has a significant effect on bright coal with well-developed fractures, high brittleness, and high strength, but it is not applicable to coal seams with underdeveloped joints, low brittleness, and softness; CO 2 fracturing method has a large cost when applied in deep parts, and there is a risk of coal and gas outburst due to the coal seam absorbing CO 2 oversaturation; the pre-splitting blasting method has a good application effect in hard coal with high strength, but there may be secondary disasters in soft coal seams.

[0004] CN118462127A discloses a method for indirectly fracturing a coal seam by high-voltage electric pulse composite hydraulic fracturing. By arranging a horizontal well in a hard roof, using the high-voltage electric pulse to penetrate the roof and the coal seam to form high-voltage electric pulse induced fractures, and then using the horizontal well staged fracturing technology to fracture the coal seam to form a complex fracture network in the coal seam.

[0005] CN107630717B discloses a coal seam permeability enhancement method by the coordination of electric pulse and coal seam water injection. By injecting ionic water into the coal seam to enhance the conductivity of the coal body, and then using high-voltage electric pulse to fracture the coal body, so as to generate fractures in the coal body and increase the single-hole gas extraction rate.

[0006] Although the above method aims to enhance the effect of high-voltage electric pulse technology, it is difficult to fundamentally solve the technical problem of high field strength required for the high-voltage electric pulse to penetrate the coal seam due to the low conductivity of the coal seam. Moreover, simply using water or conductive ion solution as the medium to improve the conductivity of the coal seam is difficult to effectively dissolve the pore-fracture structure filled with minerals in the coal seam. Summary of the Invention

[0007] The present invention aims to solve the technical problems existing in the prior art, and particularly innovatively proposes a device and method for enhancing the permeability of coal seams by synergistically using high-voltage electric pulses and acid fracturing. It can first dissolve minerals through acid fracturing fluid, dredge the pore-fracture network of the coal seam, reduce the difficulty of subsequent high-voltage electric pulse discharge, and then conduct high-voltage pulse discharge for fracturing to ensure the fracturing efficiency of coal and rock.

[0008] To achieve the above object, the present invention provides a device for enhancing the permeability of coal seams by synergistically using high-voltage electric pulses and acid fracturing, which is characterized in that it includes a packer for being buried in a fracturing and permeating operation hole. The packer includes a high-pressure acid injection pipeline, an expansion capsule is sleeved outside the middle part of the high-pressure acid injection pipeline, fixed ends are arranged at both ends of the expansion capsule, and both ends of the high-pressure acid injection pipeline extend out of the fixed ends. The rear end of the high-pressure acid injection pipeline is communicated with an acid fracturing fluid supply system through a connecting pipe;

[0009] It further includes a pair of high-voltage electrodes respectively arranged on both sides of the high-pressure acid injection pipeline. Each high-voltage electrode includes a high-voltage electrode A section extending along the axial direction of the high-pressure acid injection pipeline and a high-voltage electrode B section extending along the radial direction of the high-pressure acid injection pipeline. Installation holes for accommodating the high-voltage electrode B section are arranged radially on both sides of the front fixed end. Springs are fixedly arranged at the bottoms of the installation holes, and the high-voltage electrode B section is fixed together with the springs, so that the outer end of the high-voltage electrode B section presses against the inner wall of the fracturing and permeating operation hole. Both of the high-voltage electrode A sections penetrate through the expansion capsule, and the front ends of the two high-voltage electrode A sections respectively extend into the installation holes on both sides of the front fixed end and are in contact with the high-voltage electrode B section to achieve electrical connection. The rear ends of the high-voltage electrode A sections pass through the fixed end at the rear end of the high-pressure acid injection pipeline and are connected to a pulse circuit.

[0010] In the above solution: the expansion capsule is equipped with an insulating oil supply system and expands by injecting insulating oil into the expansion capsule. Using insulating oil can avoid conduction in other parts, ensure that the current only flows through the high-voltage electrode A section and the high-voltage electrode B section, and thus is released from the high-voltage electrode B section to ensure the action range of the pulse voltage.

[0011] In the above solution: a stop valve is arranged on the connecting pipe outside the fracturing and permeating operation hole to prevent the acid fracturing fluid from flowing out of the connecting pipe and ensure the acid fracturing effect.

[0012] In the above solution: on one side of the middle part of the B section of the high-voltage electrode close to the A section of the high-voltage electrode, there is an anti-disengagement chute extending radially along the fixed end, and the front end of the A section of the high-voltage electrode extends into the anti-disengagement chute. This prevents the B section of the high-voltage electrode from disengaging, and at the same time ensures that the A section of the high-voltage electrode abuts against the B section of the high-voltage electrode, guaranteeing the stability of the electrical connection.

[0013] In the above solution: the materials of both the A section and the B section of the high-voltage electrode are based on Cu-Cr-Zr alloy, and the surfaces of the A section and the B section of the high-voltage electrode are coated with CrN coatings.

[0014] The present invention provides a method for enhancing coal seam permeability by synergistic acid fracturing with high-voltage electric pulses, including the packer described in the above solution, and further comprising the following steps:

[0015] Step 1: Select acetic acid as the acid fracturing fluid and store the acid fracturing fluid in the mixing tank;

[0016] Step 2: Arrange a plurality of parallel fracturing and permeation operation holes in the target coal seam roadway, and the spacing between the fracturing and permeation operation holes is 3 - 5 m;

[0017] Step 3: Place a packer in each fracturing and permeation operation hole, inject insulating oil into the expansion capsule through the insulating oil supply system, and make the expansion capsule fully fit the hole wall to complete hole sealing;

[0018] Step 4: Connect each packer to the acid fracturing fluid supply system; the acid fracturing fluid supply system includes a fracturing pump with an inlet communicating with the mixing tank, the outlet of the fracturing pump is connected to a connecting flange through a fracturing fluid pipeline, and a filter, a hydraulic pressure gauge, a fluid mass flowmeter, and a throttle valve are arranged on the fracturing fluid pipeline;

[0019] Step 5: Start the fracturing pump, pump the fracturing fluid out of the mixing tank and transport it to the high-pressure acid injection pipeline, so as to inject the fracturing fluid into the fracturing and permeation operation holes;

[0020] Step 6: Stop the fracturing pump, close the stop valve, remove the connecting flange, disconnect the fracturing fluid injection, and keep the fracturing fluid under pressure in the coal seam for a certain time to complete the acid fracturing operation;

[0021] Step 7: After completing the acid fracturing operation, connect the packer to the pulse circuit;

[0022] The pulse circuit includes a capacitor module, the positive pole of the capacitor module is connected with a positive pole circuit, the positive pole circuit is used for electrically connecting the packer and the positive pole of the capacitor module, a discharge switch is arranged on the positive pole circuit, the controlled end of the discharge switch is connected to a charge and discharge controller, the negative pole of the capacitor module is connected with a negative pole circuit, the negative pole circuit is used for electrically connecting the packer and the negative pole of the capacitor module, and an oscilloscope is arranged on the negative pole circuit;

[0023] When connecting the pulse circuit, take two adjacent hole plugging devices as a group. The two hole plugging devices in the same group are respectively connected to the positive circuit and the negative circuit, and are both connected to the same positive circuit or negative circuit as another adjacent hole plugging device;

[0024] Step 8: Conduct the first discharge; close the discharge switch by operating the charge-discharge controller to conduct the first discharge;

[0025] Step 9: Observe the current-voltage curve collected by the oscilloscope to judge the high-voltage electric pulse discharge effect. If the discharge effect is not achieved, repeat Step 8 until the discharge effect is satisfied;

[0026] Step 10: Switch the circuit; switch the hole plugging device at the odd or even number to be connected to the positive circuit or the negative circuit, and make the two hole plugging devices in the same group be both connected to the same positive circuit or negative circuit, and be respectively connected to the positive circuit and the negative circuit as another adjacent hole plugging device;

[0027] Step 11: Conduct the second discharge; close the discharge switch by operating the charge-discharge controller to conduct the second discharge; and observe the current-voltage curve collected by the oscilloscope to judge the high-voltage electric pulse discharge effect. If the discharge effect is not achieved, repeat this step until the discharge effect is satisfied;

[0028] Step 12: Push the hole plugging device towards the bottom of the fracturing penetration operation hole, and repeat Steps 8 to 11 to achieve single and / or repeated discharges of high-voltage electric pulses at different positions in the same borehole;

[0029] Step 13: Release the residual electric energy in the capacitor module to complete the high-voltage electric pulse discharge operation.

[0030] Step 14: Extract the insulating oil in the expansion capsule, take out the hole plugging device, and complete the operation of enhancing coal seam permeability by high-voltage electric pulse assisted acid fracturing.

[0031] In the above solution: the capacitor module is equipped with a capacitor protection module. The charging end of the capacitor module is connected to one end of the charging protection module, and the other end of the charging protection module is connected to the power supply.

[0032] In the above solution: Step 8 further includes the following steps:

[0033] Charge before discharge, check whether the capacitor protection module and the charging protection module are well connected to the capacitor module, turn on the power supply, charge the capacitor module through the power supply, and then conduct the discharge after the voltage in the capacitor module reaches the set value.

[0034] In summary, the beneficial effects of the present invention are as follows: The set packer can not only perform acid fracturing, but also connect to a pulse circuit to release pulse voltage, with diverse functions, meeting the technical requirements of "acid fracturing - high-voltage discharge" integration; the high-voltage electrode B sections provided on both sides form a double-electrode structure, which can release pulse voltage to both sides of the fracturing penetration operation hole and connect to a packer on one side to form a circuit, thereby realizing secondary fracturing of the coal seam through pulse voltage. At the same time, in combination with the coal seam permeability enhancement method by fracturing, the electrodes are replaced to form a circuit connected to the packer on the other side, which can limit the fracturing range of the pulse voltage and ensure the fracturing efficiency of the coal seam, avoiding the situation of fracturing dead angles at some positions; meanwhile, the set spring enables the high-voltage electrode B section to have a certain free expansion and contraction amount, which can effectively contact the borehole wall and enhance the high-voltage electric pulse discharge effect.

[0035] The set acid fracturing fluid can dissolve coal body minerals through acid solution, initially dredge pore fissures, and improve the electrical conductivity of the coal body, effectively reducing the difficulty of coal seam breakdown; on this basis, the high-voltage electric pulse technology is applied. Not only can a complex fracture network be further expanded on the pore fissures formed by acid fracturing to enhance the effect of the high-voltage electric pulse technology, but also the potential influence of the reaction products of the acid fracturing technology blocking the channels can be effectively weakened. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of a device for enhancing the permeability of a coal seam by synergistically applying high-voltage electric pulses and acid fracturing according to the present invention.

[0037] Figure 2 is Figure 1 an enlarged schematic diagram of part A in

[0038] Figure 3 is a schematic diagram of a method for enhancing the permeability of a coal seam by synergistically applying high-voltage electric pulses and acid fracturing according to the present invention when connecting to an acid fracturing fluid supply system.

[0039] Figure 4 is a schematic diagram of a method for enhancing the permeability of a coal seam by synergistically applying high-voltage electric pulses and acid fracturing according to the present invention when connecting to a pulse circuit.

[0040] Figure 5 is a schematic diagram of the circuit connection during two high-voltage electric pulse operations in a method for enhancing the permeability of a coal seam by synergistically applying high-voltage electric pulses and acid fracturing according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The present invention will be further described below through embodiments in combination with the drawings:

[0042] As Figures 1 to 5 shown, a method for enhancing the permeability of a coal seam by synergistically applying high-voltage electric pulses and acid fracturing includes the following steps:

[0043] Step 1: Configure the acid fracturing fluid according to the minerals contained in the target coal seam 1, and store the acid fracturing fluid in the mixing tank 15. The acid fracturing fluid selects acetic acid CH 3 COOH as the acid fracturing working fluid; among them, the present invention selects acetic acid CH 3 COOH as the acid fracturing working fluid. This acid solution has weak ionization and slow reaction, which can significantly extend the effective action radius. Further, acetic acid reacts with iron mineral nodules in coal to form a complex, effectively avoiding the risk of secondary precipitation. The free metal ions generated during the dissolution process can significantly increase the conductivity of the reservoir medium, form a physical property response synergy mechanism with the high-voltage electric pulse technology, improve the discharge energy efficiency, and the cavitation effect generated by the electric pulse can promote the diffusion and penetration of the acid solution. The two produce a synergistic effect through the multi-field coupling action of electricity-chemistry-force.

[0044] Step 2: Arrange a plurality of parallel fracturing and penetration operation holes 2 in the roadway of the target coal seam 1. The spacing between the fracturing and penetration operation holes 2 is 3 - 5 m; to ensure the acidification effect, it is recommended that the hole depth of the operation hole is not less than 80 m, the hole diameter is not less than 100 mm, and the sealing hole depth is not less than 16 m.

[0045] Step 3: Place a packer 4 in each fracturing and penetration operation hole 2, inject insulating oil into the expansion capsule 43 through the insulating oil supply system, and make the expansion capsule 43 completely fit the hole wall to complete the sealing;

[0046] The packer 4 is used to be buried in the fracturing and penetration operation hole 2, and includes a high-pressure acid injection pipeline 44. An expansion capsule 43 is sleeved outside the middle of the high-pressure acid injection pipeline 44. The expansion capsule 43 is equipped with an insulating oil supply system and expands by injecting insulating oil into the expansion capsule 43. Fixed ends 42 are arranged at both ends of the expansion capsule 43, and both ends of the high-pressure acid injection pipeline 44 extend outside the fixed ends 42. A connecting pipe for communicating with the acid fracturing fluid supply system is arranged at the rear end of the high-pressure acid injection pipeline 44. A connecting flange 6 for connecting with the acid fracturing fluid supply system is arranged at the rear end of the connecting pipe. A stop valve 5 is arranged on the connecting pipe located outside the fracturing and penetration operation hole 2.

[0047] On both sides of the high-pressure acid injection pipeline 44, a pair of high-voltage electrodes are respectively arranged. The high-voltage electrodes both include a high-voltage electrode A section 45 extending along the axial direction of the high-pressure acid injection pipeline 44 and a high-voltage electrode B section 46 extending along the radial direction of the high-pressure acid injection pipeline 44. On both sides of the front fixed end 42, mounting holes for accommodating the high-voltage electrode B section 46 are arranged along its radial direction, and the outer ends of the high-voltage electrode B sections 46 are always located outside the mounting holes. Springs 47 are fixedly arranged at the bottoms of the mounting holes, and the high-voltage electrode B sections 46 are fixed together with the springs 47, so that the outer ends of the high-voltage electrode B sections 46 are pressed against the inner wall of the fracturing and permeation operation hole 2. The high-voltage electrode A sections 45 all penetrate through the expansion capsule 43. The front ends of the two high-voltage electrode A sections 45 respectively extend into the mounting holes on both sides of the front fixed end 42 and are in contact with the high-voltage electrode B sections 46 to achieve electrical connection. And the rear ends of the high-voltage electrode A sections 45 pass through the fixed end 42 at the rear end of the high-pressure acid injection pipeline 44 and are connected to the pulse circuit.

[0048] The rear ends of the two high-voltage electrode A sections 45 on the packer 4 are both fixed together through the same conductive copper clamp 41, and the conductive copper clamp 41 is used to connect the pulse circuit.

[0049] On one side of the middle part of the high-voltage electrode B section 46 close to the high-voltage electrode A section 45, an anti-slip groove 46a extending along the radial direction of the fixed end 42 is arranged, and the front end of the high-voltage electrode A section 45 extends into the anti-slip groove 46a. The anti-slip groove 46a is used to prevent the high-voltage electrode B section 46 from sliding out of the mounting holes on both sides of the fixed end 42.

[0050] Moreover, the materials of the high-voltage electrode A section 45 and the high-voltage electrode B section 46 are both based on Cu-Cr-Zr alloy, and the surfaces of the high-voltage electrode A section 45 and the high-voltage electrode B section 46 are coated with a 3μm-thick CrN coating by PVD process, ensuring the high conductivity, high temperature resistance and acid corrosion resistance of the electrode material, and having a relatively low cost and good engineering popularization value.

[0051] Step 4: Connect each packer 4 to the acid fracturing fluid supply system; the acid fracturing fluid supply system includes a fracturing pump 14 with an inlet communicating with a mixing tank 15. The outlet of the fracturing pump 14 is connected to a connecting flange 6 through a fracturing fluid pipeline 7. A filter 13, a hydraulic pressure gauge 12, a fluid mass flowmeter 11 and a throttle valve 10 are sequentially arranged on the fracturing fluid pipeline 7 along the liquid flow direction. A connecting flange 6 is also arranged at the front end of the fracturing fluid pipeline 7 for communicating with the connecting flange 6 of the connecting pipe;

[0052] Step 5: Start the fracturing pump 14, pump the fracturing fluid out of the mixing tank 15 and transport it through the fracturing pump 14, filter 13, throttle valve 10, fluid mass flowmeter 11, high-pressure pipeline 7, high-pressure flange 6, stop valve 5 to the high-pressure acid injection pipeline 44, so as to inject the fracturing fluid into the fracturing and permeation operation hole 2;

[0053] Step 6: Stop the fracturing pump 14, close the stop valve 5, remove the connecting flange 6, disconnect the fracturing fluid injection, and keep the fracturing fluid under pressure in the coal seam for 36 h to complete the acid fracturing operation;

[0054] Step 7: After completing the acid fracturing operation, connect the packer 4 to the pulse circuit;

[0055] The pulse circuit includes a capacitor module 16. The capacitor module 16 is equipped with a capacitor protection module 17. One end of the charging terminal of the capacitor module 16 is connected to one end of the charging protection module 19, and the other end of the charging protection module 19 is connected to the power supply 18.

[0056] The positive electrode of the capacitor module 16 is connected to a positive electrode circuit 8. The positive electrode circuit 8 is used to electrically connect the packer 4 to the positive electrode of the capacitor module 16. A discharge switch 21 is provided on the positive electrode circuit 8, and the controlled end of the discharge switch 21 is connected to the charge-discharge controller 20. The negative electrode of the capacitor module 16 is connected to a negative electrode circuit 9. The negative electrode circuit 9 is used to electrically connect the packer 4 to the negative electrode of the capacitor module 16. An oscilloscope 22 is provided on the negative electrode circuit 9.

[0057] When connecting the pulse circuit, take two adjacent packers 4 as a group. The two packers 4 in the same group are respectively connected to the positive electrode circuit 8 and the negative electrode circuit 9, and are both connected to the same positive electrode circuit 8 or negative electrode circuit 9 as another adjacent packer 4;

[0058] Specifically, the circuit connection scheme is as Figure 4 shown. Through this arrangement method, without the condition of extracting the acidification and discharge integrated packer, the global technical effect of the target area can be achieved through two high-voltage electric pulse discharge operations.

[0059] Step 8: Conduct the first discharge;

[0060] Before discharging, charge. Check whether the capacitor protection module 17 and the charging protection module 19 are well connected to the capacitor module 16. Turn on the power supply 18 and charge the capacitor module 16 through the power supply 18.

[0061] After the voltage in the capacitor module 16 reaches the set value, then conduct the discharge. When discharging, operate the charge-discharge controller 20 to close the discharge switch 21 to conduct the first discharge.

[0062] The current starts from the capacitor module 16, passes through the positive electrode circuit 8, flows through the conductive copper clamp block 41, the high-voltage electrode section A 45, and the high-voltage electrode section B 46 to reach the hole wall of the fracturing penetration hole 2, penetrates through the coal seam 1 to reach another fracturing penetration hole 2, and is connected to the capacitor module 16 via the negative electrode circuit 9 to form a discharge loop.

[0063] And the area broken down by the high-voltage pulse voltage in this step is as Figure 5As shown in the upper part, it is the coal seam 1 area between the packers 4 of the same group;

[0064] Step 9: Observe the current-voltage curve collected by the oscilloscope 22 to judge the high-voltage electric pulse discharge effect. If the discharge effect is not achieved, repeat Step 8 until the discharge effect is satisfied;

[0065] Step 10: Switch the circuit; switch the packers 4 at the odd or even number to connect to the positive circuit 8 or the negative circuit 9, and make the two packers 4 in the same group connect to the same positive circuit 8 or negative circuit 9. At the same time, the packer 4 with the switched circuit and another adjacent packer 4 are respectively connected to the positive circuit 8 and the negative circuit 9.

[0066] Step 11: Conduct the second discharge. Close the discharge switch 21 through the operation of the charge-discharge controller 20 to conduct the second discharge; the area broken down by the high-voltage pulse voltage in this step is as Figure 5 shown in the lower part, which is the coal seam 1 area between adjacent packers 4 of different groups;

[0067] And observe the current-voltage curve collected by the oscilloscope 22 to judge the high-voltage electric pulse discharge effect. If the discharge effect is not achieved, repeat this step until the discharge effect is satisfied;

[0068] In particular, multiple discharges can be designed according to the actual occurrence conditions of the coal seam 1 to achieve the best coal seam fracturing effect.

[0069] Step 12: Push the packer 4 towards the bottom of the fracturing and penetration operation hole 2, and repeat Steps 8 to 11 to achieve single and / or repeated discharges of high-voltage electric pulses at different positions in the same borehole, and strengthen the high-voltage electric pulse discharge operation effect.

[0070] Step 13: Release the residual electric energy in the capacitor module 18 to complete the high-voltage electric pulse discharge operation.

[0071] Step 14: Draw out the insulating oil in the expansion capsule 43, take out the packer 4, and complete the operation of enhancing the permeability of the coal seam by high-voltage electric pulse coordinated acid fracturing.

Claims

1. A high-voltage electric pulse synergistic acid fracturing coal seam permeability enhancement device, characterized by: The invention comprises a hole sealer (4) for embedding in a fracturing permeation operation hole (2), the hole sealer (4) comprising a high-pressure acid injection pipeline (44), a middle portion of the high-pressure acid injection pipeline (44) is covered with an expansion capsule (43), both ends of the expansion capsule (43) are provided with fixed end heads (42), and both ends of the high-pressure acid injection pipeline (44) extend out of the fixed end heads (42), and the rear end of the high-pressure acid injection pipeline (44) is connected to an acid fracturing fluid supply system through a connecting pipe; The invention also includes a pair of high-voltage electrodes respectively arranged on both sides of the high-voltage acid injection pipeline (44), wherein the high-voltage electrodes each include a high-voltage electrode segment A (45) extending axially along the high-voltage acid injection pipeline (44) and a high-voltage electrode segment B (46) extending radially along the high-voltage acid injection pipeline (44), and mounting holes for accommodating the high-voltage electrode segment B (46) are arranged radially on both sides of the front fixed end (42), and a spring (47) is fixedly arranged at the bottom of the mounting hole, and the high-voltage electrode segment B (46) and the spring (47) are connected to each other. The two high-voltage electrode segments (45) are fixed together so that the outer end of the high-voltage electrode segment B (46) is pressed against the inner wall of the fracturing permeation operation hole (2), and the two high-voltage electrode segments A (45) both penetrate the expansion capsule (43). The front ends of the two high-voltage electrode segments A (45) extend into the mounting holes on both sides of the fixed end (42) at the front end, and are abutted against the high-voltage electrode segment B (46) to achieve electrical connection, and the rear end of the high-voltage electrode segment A (45) passes through the fixed end (42) at the rear end of the high-pressure acid injection pipeline (44) and is connected to the pulse circuit.

2. A high-voltage electric pulse synergistic acid fracturing coal seam permeability enhancement device according to claim 1, characterized in that: The rear ends of the two high-voltage electrode A sections (45) are fixed together by a same conductive copper clamp (41), and the conductive copper clamp (41) is used to connect a pulse circuit.

3. A high-voltage electric pulse synergistic acid fracturing coal seam permeability enhancement device according to claim 2, characterized in that: The expansion capsule (43) is equipped with an insulating oil supply system and expands by injecting insulating oil into the expansion capsule (43).

4. The high-voltage electric pulse synergistic acid fracturing coal seam permeability enhancement device according to claim 1 is characterized by: A stop valve (5) is provided on the connecting pipe outside the fracturing permeation operation hole (2).

5. The high-voltage electric pulse synergistic acid fracturing coal seam permeability enhancement device according to claim 1, characterized in that: An anti-slip groove (46a) extending radially along the fixed end (42) is provided on one side of the middle of the high-voltage electrode segment B (46) close to the high-voltage electrode segment A (45), and the front end of the high-voltage electrode segment A (45) extends into the anti-slip groove (46a).

6. The high-voltage electric pulse synergistic acid fracturing coal seam permeability enhancement device according to claim 1, characterized in that: The material of the high-voltage electrode section A (45) and the high-voltage electrode section B (46) is a Cu-Cr-Zr alloy matrix, and the surface of the high-voltage electrode section A (45) and the high-voltage electrode section B (46) is covered with a CrN coating.

7. A method for increasing the permeability of coal seams by high-voltage electric pulse synergistic acid fracturing, comprising the sealer (4) according to any one of claims 1 to 6, characterized in that: The following steps are also included: Step 1: Select acetic acid as the acid fracturing fluid, and store the acid fracturing fluid in a mixing tank (15); Step 2: Arrange a plurality of parallel fracturing and penetration operation holes (2) in the tunnel of the target coal seam (1), wherein the spacing between the fracturing and penetration operation holes (2) is 3 to 5 m; Step 3: a sealing device (4) is placed in each fracturing penetration operation hole (2), and insulating oil is injected into the expansion capsule (43) through the insulating oil supply system, so that the expansion capsule (43) completely fits the hole wall to complete the sealing; Step 4: Connect each hole sealer (4) to an acid fracturing fluid supply system; the acid fracturing fluid supply system comprises a fracturing pump (14) whose inlet is connected to a mixing tank (15); the outlet of the fracturing pump (14) is connected to a connecting flange (6) via a fracturing fluid pipeline (7); and the fracturing fluid pipeline (7) is provided with a filter (13), a hydraulic pressure gauge (12), a fluid mass flow meter (11) and a throttle valve (10); Step 5: Start the fracturing pump (14), pump the fracturing fluid out of the mixing tank (15) and transport it to the high-pressure acid injection pipeline (44), so as to inject the fracturing fluid into the fracturing permeation operation hole (2); Step 6: Stop the fracturing pump (14), close the stop valve (5), remove the connecting flange (6), disconnect the fracturing fluid injection, and allow the fracturing fluid to react under pressure in the coal seam for a certain period of time to complete the acid fracturing operation; Step 7: After the acid fracturing operation is completed, the sealer (4) is connected to the pulse circuit; The pulse circuit comprises a capacitor module (16), the positive electrode of the capacitor module (16) is connected to a positive electrode circuit (8), the positive electrode circuit (8) is used to electrically connect the hole sealer (4) and the positive electrode of the capacitor module (16), a discharge switch (21) is provided on the positive electrode circuit (8), the controlled end of the discharge switch (21) is connected to a charge and discharge controller (20), the negative electrode of the capacitor module (16) is connected to a negative electrode circuit (9), the negative electrode circuit (9) is used to electrically connect the hole sealer (4) and the negative electrode of the capacitor module (16), and an oscilloscope (22) is provided on the negative electrode circuit (9); When connecting the pulse circuit, two adjacent hole sealers (4) are taken as a group, and the two hole sealers (4) in the same group are respectively connected to the positive circuit (8) and the negative circuit (9), and are connected to the same positive circuit (8) or negative circuit (9) as the other adjacent hole sealer (4); Step 8: Perform the first discharge; by operating the charge and discharge controller (20) to close the discharge switch (21), the first discharge is performed; Step 9: Observe the current-voltage curve collected by the oscilloscope (22) to determine the discharge effect of the high-voltage electric pulse. If the discharge effect is not achieved, repeat step 8 until the discharge effect is achieved. Step 10: Switching the circuit; switching the sealers (4) located at the odd number or the even number to be connected to the positive circuit (8) or the negative circuit (9), and making the two sealers (4) in the same group connected to the same positive circuit (8) or the negative circuit (9), and making the sealers (4) adjacent to each other to be connected to the positive circuit (8) and the negative circuit (9) respectively; Step 11: Perform a second discharge by operating the charge and discharge controller (20) to close the discharge switch (21) to perform a second discharge; and observe the current and voltage curve collected by the oscilloscope (22) to determine the discharge effect of the high-voltage electric pulse. If the discharge effect is not achieved, repeat this step until the discharge effect is achieved. Step 12: Push the sealer (4) toward the bottom of the fracturing and permeation operation hole (2), and repeat steps 8 to 11 to achieve single and / or repeated discharge of high-voltage electric pulses at different points in the same borehole; Step 13: releasing the residual electric energy in the capacitor module (18) to complete the high-voltage electric pulse discharge operation. Step 14: extract the insulating oil in the expansion capsule (43), take out the hole sealer (4), and complete the high-voltage electric pulse coordinated acid fracturing coal seam permeability enhancement operation.

8. A method for increasing coal seam permeability by high voltage electric pulse coordinated acid fracturing according to claim 7, characterized in that: The capacitor module (16) is equipped with a capacitor protection module (17); the charging end of the capacitor module (16) is connected to one end of the charging protection module (19); and the other end of the charging protection module (19) is connected to a power source (18).

9. A method for increasing coal seam permeability by high voltage electric pulse coordinated acid fracturing according to claim 8, characterized in that: Step 8 also includes the following steps: Before discharging, the capacitor protection module (17) and the charging protection module (19) are checked to see if they are well connected to the capacitor module (16), the power supply (18) is turned on, the capacitor module (16) is charged by the power supply (18), and the capacitor module (16) is discharged after the voltage in the capacitor module (16) reaches a set value.

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