A multi-coupled coal seam gas permeability enhancement extraction method and extraction device

Abstract

The present invention discloses a multi-coupled coal seam gas permeability enhancement and extraction method and extraction device, which belongs to the field of coal seam gas extraction, and includes the following steps: S1, adsorbing high-pressure carbon dioxide; S2, transporting the macroporous zeolite foam adsorbed with high-pressure carbon dioxide to a high-pressure storage tank placed in a rock tunnel at the bottom of the coal seam for standby; S3, forming a main crack; S4, expanding and extending the main crack to obtain a branch crack; S5, using the impact generated by releasing high-pressure carbon dioxide to further expand and extend the main crack and branch crack; S6, extracting gas. The present invention adopts the above-mentioned multi-coupled coal seam gas permeability enhancement and extraction method and extraction device, and uses a shock wave generator to open cracks to form main cracks, and then cooperates with water injection to open branch cracks, and high-pressure carbon dioxide to open tree-branch cracks, thereby obtaining tree-shaped cracks, and at the same time uses macroporous zeolite foam to absorb residual water, while avoiding the impact on groundwater, supporting the cracks and increasing the permeability enhancement effect.

Description

Technical Field

[0001] The present invention relates to the field of coal seam gas extraction, and in particular to a multi-coupled coal seam gas permeability enhancement extraction method and an extraction device. Background Art

[0002] my country has rich reserves of coalbed methane. The extraction of coalbed methane can not only alleviate the energy shortage, but also protect the environment and prevent gas disasters.

[0003] At present, the characteristics of coalbed methane, "high storage and low permeability", have always restricted the development of the coalbed methane industry. To solve this problem, the existing technology has further developed the following permeability enhancement technologies:

[0004] 1. Protective layer mining and permeability enhancement technology: Protective layer mining is to first mine coal seams without outburst hazards to relieve pressure on the protected layer and eliminate outburst hazards. Due to the mining impact caused by protective layer mining, the gas in the coal (rock) layer within a certain range of the roof and floor will produce mining cracks due to pressure relief and expansion, thereby greatly increasing the permeability of the coal seam. By extracting and unloading the pressure gas, the gas pressure and gas content of the coal seam can be greatly reduced.

[0005] 2. Ground hydraulic fracturing: referred to as hydraulic fracturing or fracking, it is a technology used to improve the permeability and production efficiency of underground oil and gas reservoirs. The core principle is to use high-pressure liquid to create and expand cracks in the formation, thereby improving the flow path of fluids (such as oil and natural gas), thereby increasing the production of oil or gas wells.

[0006] 3. Underground hydraulic fracturing technology: Underground hydraulic fracturing must be protected by rock sections. Generally, holes are drilled through the bottom plate tunnel to the upper coal seam, and high-pressure water is injected into the coal seam through the holes. When the coal seam exceeds the maximum fracture pressure under the action of high-pressure water, cracks will appear around the water holes and extend along the direction where the coal body bears the least vertical stress.

[0007] 4. Deep hole controlled pre-splitting blasting technology: Deep hole controlled pre-splitting blasting is different from ordinary blasting. Its characteristic is that the control hole is used to increase the free surface around the blasting hole. Under the action of explosives, an explosion cavity will be generated, and cracks more than 3 times the diameter of the gun will be generated on the wall of the cavity due to the blasting. At the same time, the explosive gas and high-pressure gas mixture generated by the blasting act together on the crack surface under the action of the explosive force along the cracks to further form a large number of crack networks.

[0008] 5. Carbon dioxide phase change fracturing technology to improve coal seam permeability: The physical properties of carbon dioxide have the following characteristics: it exists in liquid state when the temperature is below 31°C and the pressure is greater than 7.35MPa, but it starts to gasify when the temperature exceeds 31°C, and the pressure changes continuously with the temperature. Through this property of carbon dioxide, liquid carbon dioxide is injected into the blasting tube, and the liquid carbon dioxide in the storage tube is gasified and pressurized (volume expansion is more than 600 times) by triggering the heating material to heat up instantly, destroying the constant pressure shear sheet, and the release tube instantly sprays out high-pressure and high-speed supercritical carbon dioxide gas to destroy the coal (rock) body, thereby achieving the purpose of blasting fracturing.

[0009] 6. Technology of using high-pressure air to fracture coal and improve the permeability of coal seams: The high-pressure air generated by the high-pressure air compressor is instantly released through a directional release device. The formed high-pressure air flow is directionally pressed into the coal body, flows along the primary cracks in the coal body and breaks the coal body, promoting the expansion and extension of the cracks, greatly increasing the length of the cracks and forming new secondary cracks, increasing the permeability of the coal body, and achieving the purpose of improving the gas extraction efficiency of low-permeability coal seams.

[0010] 7. Hydraulic punching: Hydraulic punching uses high-pressure water to act on coal seams through drill holes, destroying the coal body structure, changing the coal body structure, and flushing out the coal body to create more cavities in the coal seam, changing the stress changes around the drill hole, releasing a large amount of gas, achieving local pressure relief, increasing the permeability of the coal seam, and having a significant effect on the extraction effect of the coal seam.

[0011] 8. Hydraulic cutting: Hydraulic cutting technology is to use high-pressure water to cut and increase the permeability of the pre-permeable coal body through the drill hole. A large number of gaps are produced in the drill hole through cutting, which improves the permeability of the coal seam, destroys the physical structure of the coal body, increases the gas extraction volume of a single hole, and provides good conditions for gas flow.

[0012] 9. Large diameter drilling permeability enhancement technology: After drilling in coal seams, the stress around the drilling holes changes, and the size of the pressure relief area around the drilling holes is proportional to the diameter of the drilling holes. When the diameter of the drilling holes increases to a certain extent, the pressure relief radius of the drilling holes can be greatly increased, the exposed surface area of ​​the coal body can be expanded, and the permeability of the coal seams can be increased.

[0013] It can be seen that the existing permeability enhancement technologies are mostly studied in a single direction, but the coal seam environment is complex, and the cracks produced by using a single permeability enhancement technology are relatively small, and the permeability enhancement effect is poor. Summary of the invention

[0014] In order to solve the above problems, the present invention provides a multi-coupled coal seam gas permeability enhancement and extraction method and extraction device, which uses a shock wave generator to open cracks to form main cracks, and then cooperates with water injection to open branch cracks, and high-pressure carbon dioxide to open tree-shaped cracks, thereby obtaining tree-shaped cracks. At the same time, large-pore zeolite foam is used to absorb residual water to avoid affecting groundwater while supporting the cracks and increasing the permeability enhancement effect.

[0015] To achieve the above object, the present invention provides a multi-coupled coal seam gas permeability enhancement and extraction method, comprising the following steps:

[0016] S1. preparing a macroporous zeolite foam, and using the prepared macroporous zeolite foam to adsorb high-pressure carbon dioxide, wherein the pressure of the high-pressure carbon dioxide adsorbed by the macroporous zeolite foam is 25 MPa to 30 MPa;

[0017] S2, using a high-pressure pipeline to transport the macroporous zeolite foam adsorbing high-pressure carbon dioxide to a high-pressure storage tank placed in a rock tunnel on the bottom of the coal seam for standby use;

[0018] S3, directional drilling and synchronous formation of main cracks by shock waves: a directional drilling rig arranged in a rock tunnel at the bottom of a coal seam is used to drill multiple sections of the coal seam in an inclined upward direction, and after each section of drilling after extending into the coal seam section is completed, the hollow drill rod is withdrawn by a set distance, and an annular shock wave generating mechanism is pushed into the hollow drill rod by a tubing pushing method until the annular shock wave generating mechanism extends out of the hollow drill rod of the current section and contacts the circumferential side of the borehole, the annular shock wave generating mechanism is turned on, and the generated shock wave acts on the coal seam on the circumferential side of the borehole to generate main cracks, and the drilling is repeated until the borehole passes through the coal seam section and enters the coal seam roof by a set distance, then the drilling is terminated, and the hollow drill bit and the hollow drill rod are withdrawn;

[0019] S4, seal the end face of the borehole and connect high-pressure water, use the high-pressure water to impact the main crack position, expand and extend the main crack to obtain branch cracks, and after a set time, pump out the water in the borehole;

[0020] S5, pushing the injection pipe connected to the high-pressure storage tank into the drill hole, and spraying the macroporous zeolite foam adsorbed with high-pressure carbon dioxide at the position aligned with the main crack position and the branch crack position, after the macroporous zeolite foam adsorbed with high-pressure carbon dioxide enters the main crack and the branch crack, the high-pressure carbon dioxide is released, and the impact generated by the release of the high-pressure carbon dioxide is used to further expand and extend the main crack and the branch crack, and form tree cracks on the basis of the branch crack, thereby obtaining cracks with a tree structure, and at the same time, the macroporous zeolite foam that has released the high-pressure carbon dioxide absorbs the residual water in the cracks with the tree structure to expand, and supports the cracks with the tree structure;

[0021] S6. Withdraw the injection pipe and connect the negative pressure adsorption device at the drilling location to extract the gas.

[0022] Preferably, step S1 specifically includes the following steps:

[0023] S11, preparation of macroporous zeolite foam:

[0024] S111, synthesizing NaA zeolite seed crystals: firstly, weighing raw materials according to the ratio of SiO2:Al2O3:Na2O:H2O=2:1:9:700, and dissolving the raw materials in deionized water and stirring until uniform, then adding the prepared NaA zeolite seed crystals into the deionized water, stirring, using the NaA zeolite seed crystals to promote the formation of crystal nuclei, and then performing hydrothermal crystallization for a set time until the NaA zeolite seed crystals are obtained, wherein the hydrothermal temperature is 80°C to 120°C, and the hydrothermal time is 2 days;

[0025] S112. Selection and pretreatment of macroporous carrier: Select α~Al2O3 or γ~A l 2O3 is used as a macroporous support, and the macroporous support is cleaned, dried and acid-washed to remove impurities and increase surface active sites;

[0026] S113, seed deposition: the NaA zeolite seed synthesized in step S111 is uniformly deposited and attached to the surface of the macroporous support prepared in step S112 by coating, dipping or spraying;

[0027] S114, secondary growth: performing secondary growth on the macroporous carrier with NaA zeolite seeds attached thereto under hydrothermal conditions, so as to promote the NaA zeolite seeds to continue to grow on the surface of the macroporous carrier and inside the pores, forming a continuous zeolite layer, and obtaining a macroporous zeolite foam, wherein the pore diameter of the macroporous zeolite foam is 20um to 100um, wherein the hydrothermal conditions are: a hydrothermal temperature of 75°C to 85°C, a hydrothermal time of 20 hours to 35 hours, and a vacuum degree of 200 to 300Pa;

[0028] S12, adsorption of high pressure carbon dioxide:

[0029] S121, pretreatment: degassing at high temperature to remove residual gas or moisture occupying the pores of the macroporous zeolite foam, wherein the temperature condition is 180°C to 200°C;

[0030] S122, high-pressure gas introduction: after the pretreated macroporous zeolite foam is placed in a high-pressure container, high-pressure carbon dioxide gas is introduced, and under set conditions, carbon dioxide molecules are adsorbed by the micropores and mesopores of the macroporous zeolite foam until adsorption equilibrium is reached, wherein the set conditions are: temperature of 50° C. to 100° C., pressure of 80 bar to 150 bar, and time of 10 h to 15 h;

[0031] S123, storing the prepared large-pore zeolite foam in a high-pressure silo.

[0032] Preferably, in step S3, the length of each borehole is 5m to 10m; the hollow drill rod is retracted by a set distance not less than the length of the annular shock wave generating mechanism; the intensity of the shock wave is 180MPa to 199MPa; the borehole passes through the coal seam section and enters the coal seam roof at a set distance of 50cm to 100cm.

[0033] Preferably, in step S4, the water pressure of the high-pressure water is 0.5 MPa to 1 MPa, and the water temperature is 110° C. to 120° C.

[0034] The extraction device of the multi-coupled coal seam gas permeability enhancement extraction method comprises a drilling device placed in the rock tunnel of the coal seam floor, a shock wave generating device, a high-pressure water injection device and a macroporous zeolite foam injection device, wherein the drilling device is a directional drilling machine, and the output end of the directional drilling machine is sequentially provided with at least one hollow drill rod and a hollow drill bit;

[0035] The shock wave generating device comprises at least one connecting rod which penetrates into the hollow drill rod and an annular shock wave generating mechanism which is arranged at one end of the connecting rod which extends into the hollow drill rod. The annular shock wave generating mechanism comprises a plurality of shock wave generators which are arranged in a circular array around the connecting rod. The plurality of shock wave generators are fixedly connected to the connecting rod via radial elastic telescopic rods, and each connecting rod is aligned with each hollow drill rod respectively.

[0036] Preferably, the radial elastic telescopic rod includes an outer tube with one end fixedly connected to the outer circumferential side of the connecting rod, an inner tube radially slidably connected to the other end of the outer tube, and a compression spring arranged between the outer tube and the inner tube, and a shock wave generator is fixed to one end of the inner tube away from the outer tube.

[0037] Preferably, the high-pressure water injection device includes a water tank and a first pressure pump, the upper and lower ends of the water tank are respectively connected to a return pipe and an injection pipe, the return pipe is provided with a water pump, the injection pipe is provided with a first pressure pump, and the injection pipe and the return pipe are provided with sealing rings at one end away from the water tank, one side of the sealing ring protrudes to form a sealing column, the sealing column is adapted to the inner wall of the borehole, and an annular air bag is provided on the side of the sealing column facing the inner wall of the borehole.

[0038] Preferably, the macroporous zeolite foam injection device comprises a high-pressure storage tank and a second pressure pump connected to the high-pressure storage tank, the high-pressure storage tank is provided with a pressure sensor, and the pressure sensor is electrically connected to the second pressure pump via a controller;

[0039] A feed port is provided at the top of the high-pressure storage tank, and the feed port is connected to a high-pressure silo placed on the ground through a high-pressure pipeline, and an airflow generator is provided on the high-pressure pipeline;

[0040] A discharge port is provided at the top of the high-pressure storage tank, and the discharge port is connected to one end of an injection pipe. The other end of the injection pipe extends into the drilled hole, and the end of the injection pipe extending into the drilled hole is a blind end. A spiral guide channel is provided on the inner circumference side of the injection pipe near the blind end, and a discharge port is opened on the injection pipe at a position corresponding to the discharge end of the spiral guide channel.

[0041] Preferably, the discharge port is tangent to the outer circumference of the injection tube.

[0042] The present invention has the following beneficial effects:

[0043] 1. The main cracks are formed by using a shock wave generator, and then the branch cracks are opened by water injection, and the tree branch cracks are opened by high-pressure carbon dioxide, so as to obtain tree-shaped cracks. At the same time, the residual water is absorbed by the macroporous zeolite foam to avoid the impact on the groundwater, support the cracks, and increase the permeability enhancement effect;

[0044] 2. After each section of drilling is completed, the shock wave generator is used to impact the coal seam to form a main crack. Compared with the traditional drilling process, the shock wave is used to create cracks at one time. The segmented shock wave crack can avoid gas outbursts caused by concentrated impact. At the same time, it is easy to grasp the location of the shock wave according to the length of the drill rod, which is convenient for determining the location of the subsequent branch cracks.

[0045] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a flow chart of a multi-coupled coal seam gas permeability enhancement and extraction method of the present invention;

[0047] Figure 2 It is a layout diagram of a drainage device of a multi-coupled coal seam gas permeability enhancement drainage method of the present invention;

[0048] Figure 3 A radial cross-sectional view of a sealing ring of a drainage device of a multi-coupled coal seam gas permeability enhancement drainage method of the present invention;

[0049] Figure 4 It is a layout diagram of the discharge port of a drainage device of a multi-coupled coal seam gas permeability enhancement drainage method of the present invention;

[0050] Figure 5 This is a layout diagram of an annular shock wave generating mechanism for a multi-coupled coal seam gas permeability enhancement and extraction method of the present invention.

[0051] Among them: 1. Coal seam roof; 2. Coal seam; 3. Coal seam floor; 4. Drill hole; 5. Hollow drill rod; 6. Directional drilling rig; 7. Return pipe; 8. Water storage tank; 9. Water injection pipe; 10. Injection pipe; 11. High-pressure storage tank; 12. Second booster pump; 13. Sealing ring; 14. Annular airbag; 15. Sealing column; 16. Spiral guide channel; 17. Discharge port; 18. Connecting rod; 19. Radial elastic telescopic rod; 20. Shock wave generator. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical scheme and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention are further described in detail in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not intended to limit the embodiments of the present invention. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions.

[0053] It should be noted that the terms "include", "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or devices.

[0054] Like reference numerals and letters denote similar items in the following drawings, and thus, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0055] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are directions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0056] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting", "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0057] like Figure 1 As shown, a multi-coupled coal seam gas permeability enhancement and extraction method comprises the following steps:

[0058] S1. preparing a macroporous zeolite foam, and using the prepared macroporous zeolite foam to adsorb high-pressure carbon dioxide, wherein the pressure of the high-pressure carbon dioxide adsorbed by the macroporous zeolite foam is 25 MPa to 30 MPa;

[0059] Step S1 specifically includes the following steps:

[0060] S11, preparation of macroporous zeolite foam:

[0061] S111, synthesizing NaA zeolite seed crystals: firstly, weighing raw materials according to the ratio of SiO2:Al2O3:Na2O:H2O=2:1:9:700, and dissolving the raw materials in deionized water and stirring until uniform, then adding the prepared NaA zeolite seed crystals into the deionized water, stirring, using the NaA zeolite seed crystals to promote the formation of crystal nuclei, and then performing hydrothermal crystallization for a set time until the NaA zeolite seed crystals are obtained, wherein the hydrothermal temperature is 80°C to 120°C, and the hydrothermal time is 2 days;

[0062] S112. Selection and pretreatment of macroporous carrier: Select α~Al2O3 or γ~A l 2O3 is used as a macroporous support, and the macroporous support is cleaned, dried and acid-washed to remove impurities and increase surface active sites;

[0063] S113, seed deposition: the NaA zeolite seed synthesized in step S111 is uniformly deposited and attached to the surface of the macroporous support prepared in step S112 by coating, dipping or spraying;

[0064] S114, secondary growth: performing secondary growth on the macroporous carrier with NaA zeolite seeds attached thereto under hydrothermal conditions, so as to promote the NaA zeolite seeds to continue to grow on the surface of the macroporous carrier and inside the pores, forming a continuous zeolite layer, and obtaining a macroporous zeolite foam, wherein the pore diameter of the macroporous zeolite foam is 20um to 100um, wherein the hydrothermal conditions are: a hydrothermal temperature of 75°C to 85°C, a hydrothermal time of 20 hours to 35 hours, and a vacuum degree of 200 to 300Pa;

[0065] S12, adsorption of high pressure carbon dioxide:

[0066] S121, pretreatment: degassing at high temperature to remove residual gas or moisture occupying the pores of the macroporous zeolite foam, wherein the temperature condition is 180°C to 200°C;

[0067] S122, high-pressure gas introduction: after the pretreated macroporous zeolite foam is placed in a high-pressure container, high-pressure carbon dioxide gas is introduced, and under set conditions, carbon dioxide molecules are adsorbed by the micropores and mesopores of the macroporous zeolite foam until adsorption equilibrium is reached, wherein the set conditions are: temperature of 50° C. to 100° C., pressure of 80 bar to 150 bar, and time of 10 h to 15 h;

[0068] S123, storing the prepared large-pore zeolite foam in a high-pressure silo.

[0069] S2, using a high-pressure pipeline to transport the macroporous zeolite foam adsorbing high-pressure carbon dioxide to a high-pressure storage tank 11 placed in a rock tunnel on the coal seam floor 3 for standby use;

[0070] S3, directional drilling 4 and synchronous formation of main cracks by shock waves: a directional drilling machine 6 arranged in a rock tunnel of the coal seam floor 3 is used to drill multiple sections of the coal seam 2 upwards, and after each section of drilling 4 after extending into the coal seam 2 is completed, the hollow drill rod 5 is withdrawn to a set distance, and an annular shock wave generating mechanism is pushed into the hollow drill rod 5 by a tubing pushing method until the annular shock wave generating mechanism extends out of the hollow drill rod 5 of the current section and contacts the circumferential side of the borehole 4, the annular shock wave generating mechanism is turned on, and the generated shock wave acts on the coal seam 2 on the circumferential side of the borehole 4 to generate main cracks, and the process is repeated until the borehole 4 passes through the coal seam 2 section and enters the coal seam roof 1 by a set distance, then the drilling 4 is terminated, and the hollow drill bit and the hollow drill rod 5 are withdrawn;

[0071] In step S3, the length of each section of the borehole 4 is 5m to 10m; the hollow drill rod 5 is retracted by a set distance not less than the length of the annular shock wave generating mechanism; the intensity of the shock wave is 180MPa to 199MPa; the borehole 4 passes through the coal seam section 2 and enters the coal seam roof 1 by a set distance of 50cm to 100cm.

[0072] S4, seal the end face of borehole 4 and connect high-pressure water, use high-pressure water to impact the main crack position, expand and extend the main crack to obtain branch cracks, and after a set time, pump out the water in borehole 4;

[0073] In step S4, the water pressure of the high-pressure water is 0.5 MPa to 1 MPa, and the water temperature is 110° C. to 120° C.

[0074] S5, pushing the injection pipe 10 connected to the high-pressure storage tank 11 into the borehole 4, and spraying the macroporous zeolite foam adsorbed with high-pressure carbon dioxide at the position aligned with the main crack position and the branch crack position. After the macroporous zeolite foam adsorbed with high-pressure carbon dioxide enters the main crack and the branch crack, the macroporous zeolite adsorbed with high-pressure carbon dioxide loses the high-pressure environment, and the high-pressure carbon dioxide is released. The main crack and the branch crack are further expanded and extended by the impact generated by the release of the high-pressure carbon dioxide, and tree cracks are formed on the basis of the branch cracks, thereby obtaining cracks with a tree structure. At the same time, the macroporous zeolite foam that has released the high-pressure carbon dioxide absorbs the residual water in the cracks with the tree structure to expand and support the cracks with the tree structure.

[0075] In this embodiment, the extension length of the annular shock wave generating mechanism can be recorded to match the occurrence position of the main crack.

[0076] S6. Withdraw the injection pipe 10 and connect the negative pressure adsorption device at the position of the borehole 4 to extract the gas.

[0077] like Figure 2 to Figure 5 As shown, the extraction device of the multi-coupled coal seam 2 gas permeability enhancement extraction method comprises a drilling device 4 placed in a rock tunnel of a coal seam floor 3, a shock wave generating device, a high-pressure water injection device and a large-pore zeolite foam injection device, wherein the drilling device 4 is a directional drilling rig 6, and the output end of the directional drilling rig 6 is sequentially provided with at least one section of hollow drill rod 5 and a hollow drill bit; the shock wave generating device comprises at least one section of connecting rod 18 penetrating into the hollow drill rod 5 and an annular shock wave generating mechanism arranged at one end of the connecting rod 18 extending into the hollow drill rod 5, the annular shock wave generating mechanism comprises a plurality of shock wave generators 20 arranged in a circular array around the connecting rod 18, the plurality of shock wave generators 20 are fixedly connected to the connecting rod 18 via a radial elastic telescopic rod 19, and each section of the connecting rod 18 is aligned with each section of the hollow drill rod 5 respectively. The radial elastic telescopic rod 19 includes an outer tube with one end fixedly connected to the outer circumferential side of the connecting rod 18, an inner tube radially slidably connected to the other end of the outer tube, and a compression spring arranged between the outer tube and the inner tube. A shock wave generator 20 is fixed to the end of the inner tube away from the outer tube. By arranging the radial elastic telescopic rod 19, it is convenient for the annular shock wave generating mechanism to pass through the hollow drill rod 5. Under the action of the restoring force of the compression spring, the annular shock wave generating mechanism is pressed toward the inner wall of the borehole 4, so that the annular shock wave generating mechanism contacts the coal seam 2, thereby improving the permeability enhancement effect.

[0078] The high-pressure water injection device includes a water storage tank 8 and a first pressure pump. The upper and lower ends of the water storage tank 8 are respectively connected with a return pipe 7 and a water injection pipe 9. The return pipe 7 is provided with a water pump. A filter is fixed inside the water storage tank 8 of this embodiment and below the return pipe 7. The first pressure pump is provided on the water injection pipe 9. The ends of the water injection pipe 9 and the return pipe 7 away from the water storage tank 8 are both provided with a sealing ring 13. One side of the sealing ring 13 protrudes to form a sealing column 15. The sealing column 15 is provided with a water injection port. The sealing column 15 is adapted to the inner wall of the borehole 4, and the sealing An annular airbag 14 is provided on the side of the mouth column 15 facing the inner wall of the borehole 4. After the sealing column 15 of the water injection pipe 9 is inserted into the borehole 4, the annular airbag 14 is inflated until the annular airbag 14 presses against the inner wall of the borehole 4 to achieve the sealing of the end face of the borehole 4. Then, the first pressure pump is turned on to inject pressurized water into the borehole 4. After a set time, the annular airbag 14 is evacuated, the water injection pipe 9 is pulled out, and the return pipe 7 is inserted in the same way. The water pump is turned on to pump the water in the borehole 4 into the water storage tank 8 again to achieve recycling.

[0079] Preferably, the macroporous zeolite foam injection device comprises a high-pressure storage tank 11 and a second pressure pump 12 connected to the high-pressure storage tank 11, and a pressure sensor is provided on the high-pressure storage tank 11, and the pressure sensor is electrically connected to the second pressure pump 12 via a controller;

[0080] A feed port is provided at the top of the high-pressure storage tank 11, and the feed port is connected to a high-pressure silo placed on the ground through a high-pressure pipeline, and an airflow generator is provided on the high-pressure pipeline;

[0081] A discharge port 17 is provided at the top of the high-pressure storage tank 11, and the discharge port 17 is connected to one end of the injection tube 10. The other end of the injection tube 10 extends into the borehole 4, and the end of the injection tube 10 extending into the borehole 4 is a blind end, and a spiral guide channel 16 is provided on the inner circumference side of the injection tube 10 close to the blind end, and a discharge port 17 is opened on the injection tube 10 at a position corresponding to the discharge end of the spiral guide channel 16, and the discharge port 17 is tangent to the outer circumference of the injection tube 10; this embodiment is provided with multiple layers of spiral guide channels 16, and each layer of spiral guide channels 16 corresponds to a discharge port 17.

[0082] Therefore, the present invention adopts the above-mentioned multi-coupled coal seam gas permeability enhancement and extraction method and extraction device, opens cracks through a shock wave generator to form main cracks, and then cooperates with water injection to open branch cracks, and high-pressure carbon dioxide to open tree-shaped cracks, thereby obtaining tree-shaped cracks. At the same time, large-pore zeolite foam is used to absorb residual water to avoid affecting groundwater while supporting the cracks and increasing the permeability enhancement effect.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A multi-coupled coal seam gas permeability enhancement and extraction method, characterized in that: The following steps are involved: S1. preparing a macroporous zeolite foam, and using the prepared macroporous zeolite foam to adsorb high-pressure carbon dioxide, wherein the pressure of the high-pressure carbon dioxide adsorbed by the macroporous zeolite foam is 25 MPa to 30 MPa; S2, using a high-pressure pipeline to transport the macroporous zeolite foam adsorbing high-pressure carbon dioxide to a high-pressure storage tank placed in a rock tunnel on the bottom of the coal seam for standby use; S3, directional drilling and synchronous formation of main cracks by shock waves: a directional drilling rig arranged in a rock tunnel at the bottom of a coal seam is used to drill multiple sections of the coal seam in an inclined upward direction, and after each section of drilling after extending into the coal seam section is completed, the hollow drill rod is withdrawn by a set distance, and an annular shock wave generating mechanism is pushed into the hollow drill rod by a tubing pushing method until the annular shock wave generating mechanism extends out of the hollow drill rod of the current section and contacts the circumferential side of the borehole, the annular shock wave generating mechanism is turned on, and the generated shock wave acts on the coal seam on the circumferential side of the borehole to generate main cracks, and the drilling is repeated until the borehole passes through the coal seam section and enters the coal seam roof by a set distance, then the drilling is terminated, and the hollow drill bit and the hollow drill rod are withdrawn; The extraction device of the multi-coupled coal seam gas permeability enhancement extraction method comprises a drilling device placed in the rock tunnel of the coal seam floor, a shock wave generating device, a high-pressure water injection device and a macroporous zeolite foam injection device, wherein the drilling device is a directional drilling machine, and the output end of the directional drilling machine is sequentially provided with at least one hollow drill rod and a hollow drill bit; The shock wave generating device comprises at least one connecting rod inserted into the hollow drill rod and an annular shock wave generating mechanism arranged at one end of the connecting rod extending into the hollow drill rod, the annular shock wave generating mechanism comprises a plurality of shock wave generators arranged in a circular array around the connecting rod, the plurality of shock wave generators are fixedly connected to the connecting rod via radial elastic telescopic rods, and each connecting rod is aligned with each hollow drill rod; The high-pressure water injection device includes a water storage tank and a first pressure pump. The upper and lower ends of the water storage tank are respectively connected with a return pipe and a water injection pipe. The return pipe is provided with a water pump. The water injection pipe is provided with a first pressure pump. The ends of the water injection pipe and the return pipe away from the water storage tank are both provided with sealing rings. One side of the sealing ring protrudes to form a sealing column. The sealing column is adapted to the inner wall of the borehole, and an annular air bag is provided on the side of the sealing column facing the inner wall of the borehole. The macroporous zeolite foam injection device comprises a high-pressure storage tank and a second pressure pump connected to the high-pressure storage tank, a pressure sensor is arranged on the high-pressure storage tank, and the pressure sensor is electrically connected to the second pressure pump via a controller; A feed port is provided at the top of the high-pressure storage tank, and the feed port is connected to a high-pressure silo placed on the ground through a high-pressure pipeline, and an airflow generator is provided on the high-pressure pipeline; A discharge port is provided at the top of the high-pressure storage tank, the discharge port is connected to one end of the injection pipe, the other end of the injection pipe extends into the borehole, and the end of the injection pipe extending into the borehole is a blind end, and a spiral guide channel is provided on the inner circumference side of the injection pipe close to the blind end, and a discharge port is provided on the injection pipe at a position corresponding to the discharge end of the spiral guide channel; S4, seal the end face of the borehole and connect high-pressure water, use the high-pressure water to impact the main crack position, expand and extend the main crack to obtain branch cracks, and after a set time, pump out the water in the borehole; S5, pushing the injection pipe connected to the high-pressure storage tank into the drill hole, and spraying the macroporous zeolite foam adsorbed with high-pressure carbon dioxide at the position aligned with the main crack position and the branch crack position, after the macroporous zeolite foam adsorbed with high-pressure carbon dioxide enters the main crack and the branch crack, the high-pressure carbon dioxide is released, and the impact generated by the release of the high-pressure carbon dioxide is used to further expand and extend the main crack and the branch crack, and form tree cracks on the basis of the branch crack, thereby obtaining cracks with a tree structure, and at the same time, the macroporous zeolite foam that has released the high-pressure carbon dioxide absorbs the residual water in the cracks with the tree structure to expand, and supports the cracks with the tree structure; S6. Withdraw the injection pipe and connect the negative pressure adsorption device at the drilling location to extract the gas.

2. A multi-coupled coal seam gas permeability enhancement and extraction method according to claim 1, characterized in that: Step S1 specifically includes the following steps: S11, preparation of macroporous zeolite foam: S111, synthesizing NaA zeolite seed crystals: firstly, weighing raw materials according to the ratio of SiO2:Al2O3:Na2O:H2O=2:1:9:700, and dissolving the raw materials in deionized water and stirring until uniform, then adding the prepared NaA zeolite seed crystals into the deionized water, stirring, using the NaA zeolite seed crystals to promote the formation of crystal nuclei, and then performing hydrothermal crystallization for a set time until the NaA zeolite seed crystals are obtained, wherein the hydrothermal temperature is 80°C to 120°C, and the hydrothermal time is 2 days; S112, selection and pretreatment of macroporous carrier: select α-Al2O3 or γ-Al2O3 as macroporous carrier, and wash, dry and acid-wash the macroporous carrier to remove impurities and increase surface active sites; S113, seed deposition: the NaA zeolite seed synthesized in step S111 is uniformly deposited and attached to the surface of the macroporous support prepared in step S112 by coating, dipping or spraying; S114, secondary growth: performing secondary growth on the macroporous carrier with NaA zeolite seeds attached thereto under hydrothermal conditions, so as to promote the NaA zeolite seeds to continue to grow on the surface of the macroporous carrier and inside the pores, forming a continuous zeolite layer, and obtaining a macroporous zeolite foam, wherein the pore diameter of the macroporous zeolite foam is 20um to 100um, wherein the hydrothermal conditions are: a hydrothermal temperature of 75°C to 85°C, a hydrothermal time of 20 hours to 35 hours, and a vacuum degree of 200 to 300Pa; S12, adsorption of high pressure carbon dioxide: S121, pretreatment: degassing at high temperature to remove residual gas or moisture occupying the pores of the macroporous zeolite foam, wherein the temperature condition is 180°C to 200°C; S122, high-pressure gas introduction: after the pretreated macroporous zeolite foam is placed in a high-pressure container, high-pressure carbon dioxide gas is introduced, and under set conditions, carbon dioxide molecules are adsorbed by the micropores and mesopores of the macroporous zeolite foam until adsorption equilibrium is reached, wherein the set conditions are: temperature of 50° C. to 100° C., pressure of 80 bar to 150 bar, and time of 10 h to 15 h; S123, storing the prepared large-pore zeolite foam in a high-pressure silo.

3. A multi-coupled coal seam gas permeability enhancement and extraction method according to claim 2, characterized in that: In step S3, the length of each borehole is 5m to 10m; the hollow drill rod is retracted by a set distance not less than the length of the annular shock wave generating mechanism; the intensity of the shock wave is 180MPa to 199MPa; the borehole passes through the coal seam section and enters the coal seam roof at a set distance of 50cm to 100cm.

4. A multi-coupled coal seam gas permeability enhancement and extraction method according to claim 3, characterized in that: In step S4, the water pressure of the high-pressure water is 0.5 MPa to 1 MPa, and the water temperature is 110° C. to 120° C.

5. A multi-coupled coal seam gas permeability enhancement and extraction method according to claim 1, characterized in that: The radial elastic telescopic rod comprises an outer tube with one end fixedly connected to the outer circumference of the connecting rod, an inner tube radially slidably connected to the other end of the outer tube, and a compression spring arranged between the outer tube and the inner tube. A shock wave generator is fixed to one end of the inner tube away from the outer tube.

6. A multi-coupled coal seam gas permeability enhancement and extraction method according to claim 1, characterized in that: The discharge port is tangent to the outer circumference of the injection tube.

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