Fractured soft low-permeability coal seam horizontal well gas jet pressure relief and permeability increasing experimental equipment and method

Abstract

The broken and soft low-permeability coal seam horizontal well gas jet pressure relief and permeability increasing experimental equipment comprises a base, a vertical surrounding shell and a top cover, the lower end of the vertical surrounding shell is installed on the base, the top cover is installed at the upper end of the vertical surrounding shell, and two sets of transverse and opposite hydraulic cylinders are installed on the vertical surrounding shell; the output end of the hydraulic cylinder is provided with an end cover for sealing and fixing the end part of the horizontal coal sample, a horizontal well hole penetrates through the center of the horizontal coal sample, the left end of the horizontal well hole is connected with a gas supply tank through a guide pipe III, the guide pipe III is provided with a control valve III, and the right end of the horizontal well hole is connected with a gas collection tank through a guide pipe IV; a first control valve is arranged on the fourth guide pipe, the gas collecting tank is further connected with a first simulation gas detector, a safety transverse barrel frame is arranged on the outer side of the horizontal coal sample, a confining pressure simulation mechanism is arranged on the safety transverse barrel frame, and the confining pressure simulation system comprises a confining pressure simulation system, a supply system and a collecting system which are arranged on the outer side of the horizontal coal sample in a sleeving mode.

Description

Technical Field

[0001] The invention relates to the technical field of underground gas control in coal mines, and in particular to gas jet pressure relief and permeability enhancement experimental equipment and method for horizontal wells in broken soft and low-permeability coal seams. Background Art

[0002] Broken, soft, and low-permeability coal seams are a complex geological condition often encountered in coal mining. Due to their poor permeability and soft coal seams, gas extraction becomes particularly difficult. Existing coal seam permeability enhancement technologies mainly include hydraulic fracturing, hydraulic jetting, and high-pressure rotating water jet cutting. However, the application effect of these methods in broken, soft, and low-permeability coal seams is limited, and there are some problems, such as difficulty in construction, high cost, and serious damage to coal seams. Among them, the basic principle of gas jet pressure relief and permeability enhancement technology is to use high-pressure gas jets to impact and cut coal seams to form a crack network, thereby increasing the permeability of coal seams. This technology has the advantages of simple construction, low cost, and little damage to coal seams. It is particularly suitable for gas extraction in broken, soft, and low-permeability coal seams.

[0003] The current gas jet pressure relief and permeability enhancement experiments generally involve drilling holes in coal samples and introducing high-pressure gas jets into the coal samples for pressure relief and permeability enhancement. However, it is difficult to analyze and detect the generation and development of cracks in the coal samples, resulting in less and inaccurate experimental data information on the coal samples. As a result, during the gas jet pressure relief and permeability enhancement process, as cracks in the coal samples develop, it is difficult to fully obtain and analyze the permeability data of the coal samples.

[0004] Therefore, it is necessary to provide a gas jet pressure relief and permeability enhancement experimental device and method for horizontal wells in broken soft and low permeability coal seams to solve the problems raised in the above background technology. Summary of the invention

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a gas jet pressure relief and permeability enhancement experimental equipment for horizontal wells in broken soft and low-permeability coal seams, comprising a base, a vertical enclosure and a top cover, wherein the lower end of the vertical enclosure is mounted on the base, and the top cover is mounted on the upper end of the vertical enclosure, and two groups of horizontal and opposite hydraulic cylinders are mounted on the vertical enclosure, and the output end of the hydraulic cylinder is mounted with an end cover for sealing and fixing the end of the horizontal coal sample, a horizontal wellbore is set through the center of the horizontal coal sample, and the left end of the horizontal wellbore is connected to a gas supply tank through a conduit three, and a control is provided on the conduit three. Valve three, the right end of the horizontal wellbore is connected to a gas collecting tank through a conduit four, a control valve four is arranged on the conduit four, a simulated gas detector one is also connected to the gas collecting tank, a safety cross-cylinder frame is arranged on the outside of the horizontal coal sample, the two ends of the safety cross-cylinder frame are respectively connected to the end covers at the left and right ends, a confining pressure simulation mechanism is arranged on the safety cross-cylinder frame, the confining pressure simulation system includes a confining pressure simulation system sleeved on the outside of the horizontal coal sample, a supply system for supplying simulated gas to the confining pressure simulation system and a collection system for collecting simulated gas from the confining pressure simulation system.

[0006] Further, as a preference, the confining pressure simulation system includes a sealing cylinder, the inner walls of the left and right ends of the sealing cylinder are respectively installed with end rings, the interior of the sealing cylinder is provided with an air-permeable micro-elastic cloth cylinder in contact with the outer surface of the horizontal coal sample, the left and right ends of the air-permeable micro-elastic cloth cylinder are respectively connected to the inner walls of the end rings at the left and right ends, a confining pressure cavity is formed between the sealing cylinder, the air-permeable micro-elastic cloth cylinder and the end rings at the left and right ends, a plurality of retaining elastic rods vertically pressing against the outer surface of the horizontal coal sample are evenly and densely distributed on the cylinder wall of the sealing cylinder, and the chambers of the confining pressure cavity are also respectively connected to pressure sensors and temperature control systems.

[0007] Further, as a preference, the retaining elastic rod includes a sealing sleeve penetrating the wall of the sealing cylinder, a support rod penetrating the sealing sleeve, a protective pad is installed on the end of the support rod located inside the confining pressure chamber, the protective pad is connected to the sealing sleeve by a spring, and the protective pad is in contact with the breathable micro-elastic cloth tube.

[0008] Furthermore, preferably, a spiral guide baffle is also provided on the inner cylinder wall of the sealing cylinder, and the baffle cross-sectional width of the spiral guide baffle is smaller than the chamber cross-sectional thickness of the confining pressure chamber.

[0009] Further, preferably, the temperature control system includes a controller, a heating wire and a temperature sensor, the heating wire is arranged along the spiral direction of the spiral guide baffle, the controller is connected to the heating wire, and the temperature sensor is connected to the chamber of the confining pressure chamber.

[0010] Further, preferably, the supply system comprises a simulated gas supply tank, and the simulated gas supply tank is connected to the upper left end of the confining pressure chamber through a conduit 1, and a control valve 1 is installed on the conduit 1.

[0011] Further, as a preference, the collection system includes a simulated gas collection tank, which is connected to the lower right end of the confining pressure chamber through a second conduit, a second control valve is installed on the second conduit, and a second simulated gas detector is also connected to the simulated gas collection tank.

[0012] Further, as a preference, the safety cross-cylinder frame includes sleeve covers respectively installed on the outside of the end covers, a cross-cylinder sleeved on the outside of the confining pressure simulation system is provided between the sleeve covers on the left and right sides, the left and right ends of the cross-cylinder are respectively connected to the sleeve covers on the left and right sides, and elastic ring pads are installed on the contact surfaces of the cross-cylinder and the sleeve covers.

[0013] Furthermore, as a preference, slide rails are installed on the left and right sides of the upper end of the base, and the left and right covers are respectively connected to the left and right slide rails.

[0014] An experimental method for gas jet pressure relief and permeability enhancement in horizontal wells of broken soft low permeability coal seams includes the following steps:

[0015] S1: Apply horizontal pressure to the horizontal coal sample through the hydraulic cylinders on the left and right sides;

[0016] S2: continuously introduce simulated gas into the confining pressure chamber through the supply system, continuously collect the simulated gas in the confining pressure chamber through the collection system, apply pressure to the outside of the horizontal coal sample, detect the pressure of the confining pressure chamber through the pressure sensor, and control the temperature of the confining pressure chamber through the temperature control system;

[0017] S3: The permeability-enhancing gas is continuously introduced into the gas permeability-enhancing tube through the gas supply tank, and the permeability-enhancing gas in the gas permeability-enhancing tube is continuously collected through the gas collection tank. The jet pressure of the permeability-enhancing gas in the gas permeability-enhancing tube on the horizontal coal sample is controlled through the coordinated regulation of control valve three and control valve four.

[0018] Compared with the prior art, the present invention provides a gas jet pressure relief and permeability enhancement experimental device and method for horizontal wells in broken soft and low permeability coal seams, which has the following beneficial effects:

[0019] In the present invention, the pressure required for jet pressure relief and permeability enhancement provided by gas permeability enhancement is provided by gas pressure in a sustainable flow mode, so that the jet pressure of the gas permeability enhancement tube on the horizontal coal sample is more stable and safe. Through the supply system and the collection system in the confining pressure simulation mechanism, the simulated pressure on the side of the horizontal coal sample is also provided by the simulated gas pressure in a sustainable flow mode. Through the real-time detection records of the simulated gas detector one and the simulated gas detector two, the data information record of the permeability conditions of the horizontal coal sample generated by the development of the cracks is obtained more accurately, so as to obtain various data information on the jet pressure relief and permeability enhancement experiment of the horizontal well in the broken soft and low permeability coal seam, such as the data information on the crack development, the crack permeability and the judgment of the completion of the crack permeability enhancement under the required simulated temperature and simulated pressure, thereby improving the understanding of the gas jet pressure relief and permeability enhancement in the horizontal well of the broken soft and low permeability coal seam. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the gas jet pressure relief and permeability enhancement experimental equipment for horizontal wells in broken soft and low permeability coal seams of the present invention;

[0021] Figure 2 It is a partial structural schematic diagram of the gas jet pressure relief and permeability enhancement experimental equipment for horizontal wells in broken soft and low permeability coal seams of the present invention;

[0022] Figure 3 It is a schematic diagram of the supply system and collection system structure of the present invention;

[0023] Figure 4 It is the structural schematic diagram of location A;

[0024] In the figure: 1, base; 2, vertical enclosure; 3, top cover; 4, hydraulic cylinder; 5, end cover; 6, confining pressure simulation mechanism; 7, safety horizontal cylinder frame; 8, gas supply tank; 9, gas collection tank; 10, gas permeability enhancement tube; 11, horizontal coal sample; 12, simulated gas detector 1; 61, supply system; 62, confining pressure simulation system; 63, collection system; 64, pressure sensor; 65, spiral guide baffle; 66, temperature control system; 611, simulated gas supply tank; 612, conduit 1; 613, control valve 1; 621, sealing enclosure; 622, end ring; 623, Breathable micro-elastic cloth tube; 624, confining pressure chamber; 625, retaining elastic rod; 6251, support rod; 6252, sealing plug sleeve; 6253, protective pad; 6254, spring; 631, simulated gas collection tank; 632, conduit two; 633, control valve two; 634, simulated gas detector two; 661, thermostat; 662, heating wire; 663, temperature sensor; 71, sleeve cover; 72, horizontal cylinder; 73, elastic ring pad; 74, slide rail; 81, conduit three; 82, control valve three; 91, conduit four; 92, control valve four; 111, horizontal wellbore. DETAILED DESCRIPTION

[0025] Reference Figure 1-Figure 4 The present invention provides a technical solution: a gas jet pressure relief and permeability enhancement experimental device for a horizontal well in a broken soft low-permeability coal seam, comprising a base 1, a vertical enclosure 2 and a top cover 3, wherein the lower end of the vertical enclosure 2 is mounted on the base 1, the top cover 3 is mounted on the upper end of the vertical enclosure 2, two groups of horizontal and opposite hydraulic cylinders 4 are mounted on the vertical enclosure 2, the output end of the hydraulic cylinder 4 is mounted with an end cover 5 for sealing and fixing the end of a horizontal coal sample 11, a horizontal wellbore 111 is set through the center of the horizontal coal sample 11, the left end of the horizontal wellbore 111 is connected to a gas supply tank 8 through a conduit 3 81, and the conduit 3 81 is connected to a gas supply tank 8. A control valve 3 82 is provided on the pipe 3 81. The right end of the horizontal wellbore 111 is connected to a gas collection tank 9 through a conduit 4 91. A control valve 4 92 is provided on the conduit 4 91. A simulated gas detector 12 is also connected to the gas collection tank 9. A safety horizontal cylinder frame 7 is provided on the outside of the horizontal coal sample 11. The two ends of the safety horizontal cylinder frame 7 are respectively connected to the end caps 5 at the left and right ends. A confining pressure simulation mechanism 6 is provided on the safety horizontal cylinder frame 7. The confining pressure simulation system 6 includes a confining pressure simulation system 62 sleeved on the outside of the horizontal coal sample 11, and a confining pressure simulation system 62 for supplying a simulated gas to the confining pressure simulation system 62. A gas supply system 61 and a collection system 63 for collecting simulated gas from a confining pressure simulation system 62; wherein the end cover 5 is aligned with the lateral end of the horizontal coal sample 11; wherein, that is, the control valve three 82 and the control valve four 92 cooperate to regulate the pressure of the permeability-enhancing gas in the gas permeability-enhancing tube 10, the gas supply tank 8 continuously introduces the permeability-enhancing gas into the gas permeability-enhancing tube 10 through the conduit three 81, the gas collection tank 9 continuously collects the permeability-enhancing gas in the gas permeability-enhancing tube 1 through the conduit four 91, and regulates the gas permeability-enhancing gas jet required to be released from the gas permeability-enhancing tube 10 to the coal sample 11 pressure, and permeability enhancement is performed on the coal sample 11; wherein, a simulated gas detector 12 detects and records the simulated gas concentration change curve of the gas collecting tank within the unit flow rate, so as to analyze and grasp the permeability enhancement situation of the horizontal coal sample 11, and after the experiment is completed, calculate the total gas content in the gas collecting tank 9, so as to grasp and analyze the horizontal coal sample 11 in the process of permeability enhancement, after the simulated gas in the permeability enhancement horizontal coal sample 11 is introduced into the horizontal wellbore 111, the situation changes with the permeability enhancement gas introduction conduit four 91 entering the gas collecting tank 9, so as to improve the accuracy of permeability enhancement and permeability analysis of the horizontal coal sample 11.

[0026] In this embodiment, the confining pressure simulation system 62 includes a sealing cylinder 621, and the inner walls of the left and right ends of the sealing cylinder 621 are respectively installed with end rings 622. The interior of the sealing cylinder 621 is provided with an air-permeable micro-elastic cloth cylinder 623 in contact with the outer surface of the horizontal coal sample 11. The left and right ends of the air-permeable micro-elastic cloth cylinder 623 are respectively connected to the inner walls of the end rings 622 at the left and right ends. A confining pressure cavity 624 is formed between the sealing cylinder 621, the air-permeable micro-elastic cloth cylinder 623 and the end rings 622 at the left and right ends. The cylinder wall of the sealing cylinder 621 is evenly and densely distributed with a plurality of retaining elastic rods 625 vertically pressing against the outer surface of the horizontal coal sample 11. The chamber of the confining pressure cavity 624 is also respectively connected with a pressure sensor 64 and a temperature control system 66; wherein, when the horizontal coal sample 11 is connected to the gas permeability enhancement tube During the permeability enhancement process 10, the cracks in the horizontal coal sample 11 of the broken soft low-permeability coal seam will continue to increase radially until the cracks extend to the outer surface of the horizontal coal sample 11. At this time, since the horizontal coal sample 11 is still subjected to the pressure of the hydraulic cylinder 4 and the pressure of the confining pressure simulation mechanism 6, the contact surface between the outside of the horizontal coal sample 11 and the hydraulic cylinder 4 and / or the confining pressure simulation mechanism 6 will be detached. Through the micro-elastic properties of the retaining elastic rod 625 and the breathable micro-elastic cloth tube 623, when the fracturing cracks of the horizontal coal sample 11 continue to increase radially, a stable supporting force that cooperates with the deformation of the horizontal coal sample 11 can be provided to the surface of the horizontal coal sample 11, thereby simulating the retaining supporting force of the retaining horizontal coal sample 11, so that the outside of the horizontal coal sample 11 can still be subjected to a stable simulated pressure.

[0027] In this embodiment, the retaining elastic rod 625 includes a sealing sleeve 6252 that passes through the wall of the sealing sleeve 621, and a support rod 6251 passes through the sealing sleeve 6252. A protective pad 6253 is installed at the end of the support rod 6251 located inside the confining pressure chamber 624. The protective pad 6253 is connected to the sealing sleeve 6252 by a spring 6254, and the protective pad 6253 is in contact with the breathable micro-elastic cloth tube 623.

[0028] In this embodiment, a spiral guide baffle 65 is further provided on the inner cylinder wall of the sealing cylinder 621, and the baffle cross-sectional width of the spiral guide baffle 65 is smaller than the chamber cross-sectional thickness of the confining pressure chamber 624; that is, a certain gap is left between the spiral guide baffle 65 and the surface of the horizontal coal sample 11 to facilitate the appearance of cracks and dislocations on the outer surface of the horizontal coal sample 11. The provision of the spiral guide baffle 65 is conducive to making the flow of gas in the confining pressure chamber 624 more uniform and smooth, so as to facilitate more uniform penetration of simulated gas into the interior of the horizontal coal sample 11, thereby improving the accuracy of simulated gas detection data.

[0029] In this embodiment, the temperature control system 66 includes a controller 661, a heating wire 662 and a temperature sensor 663. The heating wire 662 is arranged along the spiral direction of the spiral guide baffle 65. The controller 661 is connected to the heating wire 662. The temperature sensor 663 is connected to the chamber of the confining pressure chamber 624 so as to make the temperature distribution in the confining pressure chamber 624 uniform.

[0030] In this embodiment, the supply system 61 includes a simulated gas supply tank 611, and the simulated gas supply tank 611 is connected to the upper left end of the confining pressure chamber 624 through a conduit 1 612, and a control valve 1 613 is installed on the conduit 1 612.

[0031] In this embodiment, the collection system 63 includes a simulated gas collection tank 631, which is connected to the lower right end of the confining pressure chamber 624 through a second conduit 632, on which a second control valve 633 is installed, and the simulated gas collection tank 631 is also connected to a second simulated gas detector 634; the second simulated gas detector 634 detects and records the simulated gas concentration change curve of the simulated gas within the unit flow rate, so as to analyze and grasp the permeability enhancement situation of the horizontal coal sample 11, and after the experiment is completed, calculate the total gas content in the simulated gas collection tank 631, so as to grasp the situation of the simulated gas penetrating into the horizontal coal sample 11 during the permeability enhancement process of the horizontal coal sample 11, so as to improve the accuracy of the permeability enhancement and permeability analysis of the horizontal coal sample 11.

[0032] In this embodiment, the safety cross-cylinder frame 7 includes sleeve covers 71 respectively installed on the outside of the end covers 5, and a cross-cylinder 72 is provided between the left and right sleeve covers 71 and is sleeved on the outside of the confining pressure simulation system 62. The left and right ends of the cross-cylinder 72 are respectively connected to the left and right sleeve covers 71, and an elastic ring pad 73 is installed on the contact surface between the cross-cylinder 72 and the sleeve cover 71.

[0033] In this embodiment, slide rails 74 are further installed on the left and right sides of the upper end of the base 1, and the left and right covers 71 are respectively connected to the left and right slide rails 74.

[0034] In specific implementation, it includes the following steps:

[0035] S1: Apply horizontal pressure to the horizontal coal sample 11 through the hydraulic cylinders 4 on the left and right sides;

[0036] S2: Simulated gas is continuously introduced into the confining pressure chamber 624 through the supply system 61, and the simulated gas in the confining pressure chamber is continuously collected through the collection system 63, and the outer side of the horizontal coal sample 11 is pressurized, and the pressure of the confining pressure chamber 624 is detected by the pressure sensor 64, and the temperature of the confining pressure chamber 624 is controlled by the temperature control system 66, wherein the pressure sensor 64 is set according to the desired simulated confining pressure, and the temperature control system 66 is set according to the desired simulated temperature simulation, and the pressure in the confining pressure chamber 624 reaches the pressure value set by the pressure sensor 64 through the coordinated regulation of the control valve 1 613 and the control valve 2 633, and when the flow in the confining pressure chamber 624 is stable, it indicates that the permeability inside the horizontal coal sample 11 is in a stable state;

[0037] S3: Permeability-enhancing gas is continuously introduced into the gas permeability-enhancing tube 10 through the gas supply tank 8, and the permeability-enhancing gas in the gas permeability-enhancing tube 10 is continuously collected through the gas collection tank 9. The jet pressure of the permeability-enhancing gas applied by the gas permeability-enhancing tube 10 to the horizontal coal sample 11 is controlled through the coordinated regulation of the control valve three 82 and the control valve four 92, so as to relieve pressure and enhance permeability of the horizontal coal sample 11. When the gas concentration within the unit flow detected by the simulated gas detector one 12 is in a relatively stable fluctuation range, and the gas concentration within the unit flow detected by the simulated gas detector two 634 is in a relatively stable fluctuation range, it indicates that under the conditions of the required simulated temperature, simulated pressure and the preset permeability-enhancing flow pressure of the gas permeability-enhancing tube, the permeability-enhancing and permeability experimental data of the horizontal coal sample 11 are recorded by continuously introducing flow, thereby improving the understanding of gas jet pressure-unloading and permeability-enhancing in horizontal wells of broken soft and low permeability coal seams, so as to facilitate aligned mining.

[0038] The above description is only a preferred specific implementation manner of the invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the invention, which should be covered by the protection scope of the present invention.

Claims

1. A gas jet pressure relief and permeability enhancement experimental device for a horizontal well in a broken soft low-permeability coal seam, comprising a base (1), a vertical enclosure (2) and a top cover (3), wherein the lower end of the vertical enclosure (2) is mounted on the base (1), and the top cover (3) is mounted on the upper end of the vertical enclosure (2), and is characterized in that: Two groups of horizontal and opposite hydraulic cylinders (4) are installed on the vertical enclosure (2), and an end cover (5) for sealing and fixing the end of the horizontal coal sample (11) is installed on the output end of the hydraulic cylinder (4). A horizontal wellbore (111) is set through the center of the horizontal coal sample (11), and the left end of the horizontal wellbore (111) is connected to a gas supply tank (8) through a conduit three (81), and a control valve three (82) is provided on the conduit three (81). The right end of the horizontal wellbore (111) is connected to a gas collection tank (9) through a conduit four (91), and a control valve four (92) is provided on the conduit four (91). 2), the gas collection tank (9) is also connected to a simulated gas detector (12), a safety horizontal cylinder frame (7) is provided on the outside of the horizontal coal sample (11), the two ends of the safety horizontal cylinder frame (7) are respectively connected to the end covers (5) at the left and right ends, and a confining pressure simulation mechanism (6) is provided on the safety horizontal cylinder frame (7), and the confining pressure simulation system (6) includes a confining pressure simulation system (62) sleeved on the outside of the horizontal coal sample (11), a supply system (61) for supplying simulated gas to the confining pressure simulation system (62), and a collection system (63) for collecting simulated gas from the confining pressure simulation system (62).

2. The gas jet pressure relief and permeability enhancement experimental equipment for horizontal wells in crushed soft and low-permeability coal seams according to claim 1 is characterized in that: The confining pressure simulation system (62) comprises a sealing enclosure (621), the inner walls of the left and right ends of the sealing enclosure (621) are respectively installed with end rings (622), the interior of the sealing enclosure (621) is provided with an air-permeable micro-elastic cloth tube (623) in contact with the outer surface of the horizontal coal sample (11), the left and right ends of the air-permeable micro-elastic cloth tube (623) are respectively connected to the inner walls of the end rings (622) at the left and right ends, a confining pressure chamber (624) is formed between the sealing enclosure (621), the air-permeable micro-elastic cloth tube (623) and the end rings (622) at the left and right ends, a plurality of retaining elastic rods (625) vertically directed toward the outer surface of the horizontal coal sample (11) are evenly and densely distributed on the wall of the sealing enclosure (621), and the chamber of the confining pressure chamber (624) is also respectively connected to a pressure sensor (64) and a temperature control system (66).

3. The gas jet pressure relief and permeability enhancement experimental equipment for horizontal wells in crushed soft and low-permeability coal seams according to claim 2 is characterized in that: The retaining elastic rod (625) includes a sealing sleeve (6252) penetrating the wall of the sealing sleeve (621), a support rod (6251) penetrating the sealing sleeve (6252), a protective pad (6253) installed at the end of the support rod (6251) located inside the confining pressure chamber (624), the protective pad (6253) and the sealing sleeve (6252) are connected by a spring (6254), and the protective pad (6253) is in contact with the breathable micro-elastic cloth tube (623).

4. The gas jet pressure relief and permeability enhancement experimental equipment for horizontal wells in crushed soft and low-permeability coal seams according to claim 2 is characterized in that: A spiral guide baffle (65) is also provided on the inner cylinder wall of the sealing surrounding cylinder (621), and the baffle cross-sectional width of the spiral guide baffle (65) is smaller than the chamber cross-sectional thickness of the confining pressure chamber (624).

5. The gas jet pressure relief and permeability enhancement experimental equipment for horizontal wells in crushed soft and low-permeability coal seams according to claim 4 is characterized in that: The temperature control system (66) comprises a controller (661), a heating wire (662) and a temperature sensor (663); the heating wire (662) is arranged along the spiral direction of the spiral guide baffle (65); the controller (661) is connected to the heating wire (662); and the temperature sensor (663) is connected to the chamber of the confining pressure chamber (624).

6. The gas jet pressure relief and permeability enhancement experimental equipment for horizontal wells in crushed soft and low-permeability coal seams according to claim 2 is characterized in that: The supply system (61) includes a simulated gas supply tank (611), and the simulated gas supply tank (611) is connected to the upper left end of the confining pressure chamber (624) through a conduit 1 (612), and a control valve 1 (613) is installed on the conduit 1 (612).

7. The gas jet pressure relief and permeability enhancement experimental equipment for horizontal wells in crushed soft and low-permeability coal seams according to claim 2 is characterized in that: The collection system (63) comprises a simulated gas collection tank (631), wherein the simulated gas collection tank (631) is connected to the lower right end of the confining pressure chamber (624) via a second conduit (632), a second control valve (633) is installed on the second conduit (632), and a second simulated gas detector (634) is also connected to the simulated gas collection tank (631).

8. The gas jet pressure relief and permeability enhancement experimental equipment for horizontal wells in crushed soft and low-permeability coal seams according to claim 1 is characterized in that: The safety cross-tube frame (7) comprises sleeve covers (71) respectively mounted on the outside of the end covers (5), a cross-tube (72) sleeved on the outside of the confining pressure simulation system (62) is arranged between the sleeve covers (71) on the left and right sides, the left and right ends of the cross-tube (72) are respectively connected to the sleeve covers (71) on the left and right sides, and an elastic ring gasket (73) is installed on the contact surface between the cross-tube (72) and the sleeve cover (71).

9. The gas jet pressure relief and permeability enhancement experimental equipment for horizontal wells in crushed soft and low-permeability coal seams according to claim 8 is characterized in that: Slide rails (74) are also installed on the left and right sides of the upper end of the base (1), and the left and right covers (71) are respectively connected to the left and right slide rails (74).

10. A gas jet pressure relief and permeability enhancement experimental method for horizontal wells in crushed soft and low permeability coal seams, which uses the gas jet pressure relief and permeability enhancement experimental equipment for horizontal wells in crushed soft and low permeability coal seams as described in claims 2-9, characterized in that: It includes the following steps: S1: Applying horizontal pressure to the horizontal coal sample (11) through the hydraulic cylinders (4) on the left and right sides; S2: continuously introducing simulated gas into the confining pressure chamber (624) through the supply system (61), continuously collecting the simulated gas in the confining pressure chamber through the collection system (63), applying pressure to the outer side of the horizontal coal sample (11), detecting the pressure of the confining pressure chamber (624) through the pressure sensor (64), and controlling the temperature of the confining pressure chamber (624) through the temperature control system (66); S3: The permeability-enhancing gas is continuously introduced into the gas permeability-enhancing tube (10) through the gas supply tank (8), the permeability-enhancing gas in the gas permeability-enhancing tube (10) is continuously collected through the gas collection tank (9), and the jet pressure of the permeability-enhancing gas applied by the gas permeability-enhancing tube (10) to the horizontal coal sample (11) is controlled through the coordinated regulation of the control valve three (82) and the control valve four (92).

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