Methane in-situ combustion fracturing system and method based on shock wave ignition

Abstract

A kind of methane in-situ combustion fracturing system and method based on shock wave ignition, system: shock tube assembly includes pressure-bearing pipe body;Clamp one and two are clamped in diaphragm one and two inside pressure-bearing pipe body;Gas filling assembly includes high-pressure gas tank, high-pressure and double-membrane gas supply pipeline connected with high-pressure gas tank respectively communicate high-pressure and double-membrane chamber;Exhaust assembly includes vacuum pump, vacuum pump connected with the vacuum pumping pipeline is communicated with high-pressure and double-membrane chamber through communication pipeline one and two respectively, double-membrane exhaust pipeline is communicated with communication pipeline two;Methane combustion and explosion packer unit is the packer of being installed on pressure-bearing pipe body;Combustion-supporting agent delivery unit includes oxygen cylinder, oxygen delivery pipeline connected with oxygen cylinder communicates combustion chamber;Combustible gas concentration detector is located on oxygen delivery pipeline;Method: shock tube assembly is assembled and is lowered;High-pressure and double-membrane chamber is vacuumized;Gas is filled;Fast pressure relief;The shock wave generated is ignited and expanded into combustion and explosion.The ignition energy of the present application is high, and the combustion and explosion effect is ideal.

Description

Technical Field

[0001] This invention belongs to the field of unconventional natural gas extraction and fracturing production enhancement technology, specifically a methane in-situ combustion and explosion fracturing system and method based on shock wave ignition. Background Technology

[0002] In recent years, my country has achieved a series of major breakthroughs in the field of unconventional natural gas enhanced development technology. Hydraulic fracturing technology, as one of the mainstream technologies for large-scale unconventional natural gas extraction, has the ability to significantly improve the macroscopic permeability of reservoirs and has demonstrated broad applicability. However, traditional hydraulic fracturing stimulation schemes have many limitations, such as easily leading to a uniform fracture morphology, making it difficult to construct a complex three-dimensional reservoir fracture network structure, resulting in low extraction efficiency and unsatisfactory extraction effects.

[0003] To address these challenges, some scholars have innovatively proposed the concept of in-situ methane combustion-explosion fracturing technology. Methane, a major component of unconventional natural gas, is a flammable and explosive gas that produces a strong combustion-explosion impact effect upon explosion. By injecting various types of combustion-supporting agents into the reservoir and thoroughly mixing them with in-situ desorbed methane, and then igniting and detonating the agents once a predetermined ratio and combustion-explosion pressure conditions are met, explosive fracturing occurs inside the wellbore, thereby constructing a complex fracture network system to facilitate the efficient development of unconventional natural gas. However, existing ignition methods mostly use cables to control the downhole ignition device, which suffers from relatively low ignition energy and poor combustion-explosion effect, making it difficult to create a complex fracture network structure over a large area after the explosion. Therefore, there is an urgent need to provide a combustion-explosion fracturing system and method that can significantly enhance the effect of in-situ methane combustion-explosion fracturing. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a methane in-situ combustion and explosion fracturing system and method based on shock wave ignition. This system has a reasonable structure and simple operation. It uses shock waves for ignition, resulting in high ignition energy and an ideal combustion and explosion effect. It can construct complex fracture network structures, which is beneficial for improving the extraction efficiency and effectiveness of unconventional natural gas. This method is simple to implement, has an ideal combustion and explosion effect, reliable performance, and a high safety factor. It enables rapid heating and pressurization of the combustion and explosion gas in the wellbore and global ignition operations, effectively enhancing the in-situ combustion and explosion fracturing effect of methane. It can significantly improve the extraction efficiency and effectiveness of unconventional natural gas, and has broad application prospects and great practical value.

[0005] To achieve the above objectives, the present invention provides a methane in-situ combustion and explosion fracturing system based on shock wave ignition, comprising a shock wave ignition unit, a methane combustion and explosion containment unit, and a combustion aid delivery unit.

[0006] The shock wave ignition unit includes a shock tube assembly, a gas supply assembly, and a gas exhaust assembly; the shock tube assembly includes a pressure-bearing tube body, an end cap, a clamping device one, a clamping device two, a diaphragm one, and a diaphragm two; the pressure-bearing tube body is disposed in the target fracturing section inside the wellbore; the end cap is sealed to the upper open end of the pressure-bearing tube body; the clamping device one and the clamping device two are connected in series with alternating vertical spacing on the lower section of the pressure-bearing tube body; the diaphragm one and the diaphragm two are disposed with alternating vertical spacing inside the pressure-bearing tube body. The edges of diaphragm one and diaphragm two are respectively clamped inside clamping device one and clamping device two; a high-pressure chamber is formed inside the pressure-bearing tube between the end cap and diaphragm one, and a double-diaphragm chamber is formed between diaphragm one and diaphragm two; the gas filling assembly includes a high-pressure gas tank, a high-pressure gas supply pipeline, and a double-diaphragm gas supply pipeline; the high-pressure gas tank is installed on the ground; gas filling valve one and gas filling valve two are respectively connected in series on the high-pressure gas supply pipeline and the double-diaphragm gas supply pipeline, and the inlet ends of both gas supply pipelines are connected to the high-pressure gas tank. The gas cylinder has an outlet valve connected to the wellbore, with its outlet end extending into the wellbore. The outlet end of the high-pressure gas supply pipeline is connected to a pre-reserved injection port on the end cap. The outlet end of the dual-membrane gas supply pipeline communicates with the dual-membrane chamber through a pre-reserved injection port on the pressure-bearing pipe body. The exhaust assembly includes a vacuum pump, a vacuum extraction pipeline, and a dual-membrane venting pipeline. The vacuum pump is located on the ground. The inlet section of the vacuum extraction pipeline extends into the wellbore and is connected vertically to a connecting pipeline and a... Connecting pipe 2, connecting pipe 1 and connecting pipe 2 are respectively connected in series with connecting valve 1 and connecting valve 2 in the middle section. Connecting pipe 1 is connected to the high pressure chamber through a reserved exhaust port 1 on the pressure-bearing pipe body. Connecting pipe 2 is connected to the double membrane chamber through a reserved exhaust port 2 on the pressure-bearing pipe body. The exhaust end of the vacuum pipe is connected to the inlet end of the vacuum pump. The double membrane venting pipe is connected in series with a pressure relief valve. Its inlet end is connected to the inlet section of connecting pipe 2, and its outlet end is connected to the outside atmosphere.

[0007] The methane combustion and explosion containment unit is a packer. The packer is fitted onto the outside of the lower end of the pressure-bearing pipe and is seated in the wellbore, forming a combustion and explosion chamber between the packer, the wellbore, and the second diaphragm.

[0008] The combustion aid delivery unit includes an oxygen cylinder, an oxygen delivery pipeline, and a combustible gas concentration detector; the oxygen cylinder is located on the ground; the inlet end of the oxygen delivery pipeline is connected to the outlet valve of the oxygen cylinder, and its outlet end extends into the well shaft and communicates with the combustion and explosion chamber after passing through the packer; the combustible gas concentration detector is installed at the outlet end of the oxygen delivery pipeline.

[0009] Furthermore, to facilitate fully automated control, a controller is also included. This controller is connected to a combustible gas concentration detector, outlet valve one, outlet valve two, gas filling valve one, gas filling valve two, pressure relief valve, connecting valve one, connecting valve two, and a vacuum pump. More preferably, a power supply module and a wireless communication module are also included. The power supply module is connected to the controller for providing power, and the wireless communication module is connected to the controller for establishing a communication link between the controller and an external terminal.

[0010] Furthermore, in order to facilitate the clamping operation of diaphragms one and two, and at the same time, to ensure the overall sealing effect and pressure bearing strength after clamping, the pressure bearing tube body includes an upper tube body, a middle tube body and a lower tube body that are coaxially distributed from top to bottom;

[0011] The clamping device includes an upper diaphragm flange, a lower diaphragm flange, a sealing ring, and fastening bolts. The upper diaphragm flange is fixedly fitted onto the outside of the lower end of the upper section of the pipe body. The lower diaphragm flange is fixedly fitted onto the outside of the upper end of the middle section of the pipe body and is distributed vertically opposite to the upper diaphragm flange. The sealing ring is disposed between the upper diaphragm flange and the lower diaphragm flange. Multiple fastening bolts are evenly inserted into multiple pairs of bolt holes between the upper diaphragm flange and the lower diaphragm flange, and the two are locked and fixedly connected. The outer edge of the diaphragm is disposed between the upper diaphragm flange and the lower diaphragm flange and is fitted and connected to the inner edge of the sealing ring.

[0012] The clamping device two includes an upper clamping flange two, a lower clamping flange two, a sealing ring two, and two fastening bolts two. The upper clamping flange two is fixedly fitted onto the outside of the lower end of the middle section of the pipe body. The lower clamping flange two is fixedly fitted onto the outside of the upper end of the lower section of the pipe body and is distributed vertically opposite to the upper clamping flange two. The sealing ring two is disposed between the upper clamping flange two and the lower clamping flange two. Multiple fastening bolts two are evenly inserted circumferentially into multiple pairs of screw holes between the upper clamping flange two and the lower clamping flange two, and lock the two together. The outer edge of the diaphragm two is disposed between the upper clamping flange two and the lower clamping flange two, and is fitted and connected to the inner edge of the sealing ring two.

[0013] As a preferred embodiment, both diaphragm one and diaphragm two are made of industrial pure aluminum film.

[0014] Furthermore, to ensure a good sealing effect at the connection, the end cap and the pressure-bearing pipe body are sealed together by a graphite sealing ring.

[0015] Furthermore, in order to facilitate convenient control of the connection status between the high-pressure gas supply pipeline and the dual-membrane gas supply pipeline and the high-pressure gas tank, the first outlet valve is a three-way valve, and is connected to the inlet end of the high-pressure gas supply pipeline and the inlet end of the dual-membrane gas supply pipeline respectively.

[0016] Furthermore, in order to ensure the effective formation of the shock wave and to ensure the combustion and explosion effect, the high-pressure gas tank is filled with pure hydrogen, pure helium, pure nitrogen, or pure argon, or a mixture of hydrogen, helium, nitrogen, and argon in a set ratio.

[0017] In this invention, an end cap is sealed at the upper open end of the pressure-bearing pipe. Simultaneously, clamps one and two, connected in series with the pressure-bearing pipe, are used to assemble diaphragms one and two into the interior of the pipe. This allows the inner cavity of the pressure-bearing pipe to be divided into three sections from top to bottom using the diaphragms one and two, which are spaced apart vertically. The section between the end cap and diaphragm one forms a high-pressure chamber, the section between diaphragms one and two forms a double-diaphragm chamber, and the section below diaphragm two can be directly connected to the wellbore. Connecting pipes one and two, located in the air inlet section of the vacuum pump, connect the high-pressure chamber and the double-diaphragm chamber, respectively. This facilitates vacuuming of both chambers using a vacuum pump. Separate connecting valves one and two are installed on connecting pipes one and two, respectively, allowing for independent control to effectively ensure that the vacuum levels in both the high-pressure chamber and the double-diaphragm chamber meet operational requirements. By connecting the high-pressure gas supply pipeline and the double-membrane gas supply pipeline, which are connected to the high-pressure chamber and the double-membrane chamber respectively, it is convenient to add driving gas to the high-pressure chamber and the double-membrane chamber after the vacuuming operation. By separately installing filling valves one and two on the high-pressure gas supply pipeline and the double-membrane gas supply pipeline, it is possible to effectively ensure that the filling pressure of both the high-pressure chamber and the double-membrane chamber meets the operational requirements through independent control. A packer is fitted at the lower end of the pressure-bearing pipe and is seated inside the wellbore. This packer effectively seals the annulus between the pressure-bearing pipe and the wellbore, thereby forming a combustion and explosion chamber below diaphragm one. An oxygen delivery pipeline connected to an oxygen cylinder passes through the packer and connects to the combustion and explosion chamber, facilitating the injection of oxygen into the combustion and explosion chamber. The installation of a combustible gas concentration detector allows for real-time monitoring of the concentration data of the mixed combustible and explosive gases in the combustion and explosion chamber, enabling timely determination of whether the required standards for combustion and explosion have been met. A double-membrane venting line is connected to the second connecting line, and a pressure relief valve is connected in series with the double-membrane venting line. On the one hand, the pressure relief valve can ensure efficient and smooth vacuuming operations when closed, and on the other hand, it can rapidly depressurize the double-membrane chamber when open. Since the double-membrane chamber is located between the high-pressure chamber and the combustion and explosion chamber, the pressure difference effect can cause the first and second diaphragms to rupture rapidly in sequence. This allows the driving gas in the high-pressure chamber to quickly break through the first and second diaphragms under the action of the pressure difference and enter the combustion and explosion chamber, where a shock wave can be rapidly generated. Thus, the action of the shock wave can cause the combustion and explosion gas to spontaneously ignite. This process can generate multiple ignition points simultaneously, thereby effectively increasing the ignition energy. Based on this, it can rapidly expand into combustion and explosion, which can significantly enhance the combustion and explosion effect and is conducive to creating a complex and ideally connected crack network structure over a large area after the combustion and explosion.The system in this invention can generate a huge pressure difference instantaneously through vacuuming, pressurizing, and rapidly depressurizing, thereby enabling instantaneous membrane rupture. At the moment of rupture, a shock wave is formed in the low-pressure section. The temperature and pressure of the mixed gas in the low-pressure end and the connected combustion chamber rise sharply under the action of the shock wave, and ignition and explosion occur under the influence of the reflected shock wave. The temperature and pressure increase effect of the shock wave and the overall ignition mode can significantly promote the methane combustion effect, significantly improving the reservoir modification effect of in-situ methane combustion fracturing. Selecting a suitable membrane rupture method is a key step in generating a stable shock wave in the shock tube. The innovative double-diaphragm structure of this invention features convenient operation, rapid response, and good reusability.

[0018] The system has a reasonable structure and simple operation. It can instantly generate high-temperature and high-pressure shock waves in the combustion and explosion space and ignite the gas through the shock waves. Its ignition energy is high, which can significantly enhance the combustion and explosion effect. It can construct a complex fracture network structure, which is conducive to improving the extraction efficiency and extraction effect of unconventional natural gas.

[0019] This invention also provides a method for in-situ combustion and explosion fracturing of methane based on shock wave ignition, employing a methane in-situ combustion and explosion fracturing system based on shock wave ignition, comprising the following steps:

[0020] Step 1: Collect geological parameters and exploration data of the target reservoir, and determine the inflation pressure of the high-pressure chamber and the dual-membrane chamber according to the reservoir conditions, and then select the appropriate membrane 1 and membrane 2.

[0021] Step 2: Clamp diaphragm 1 and diaphragm 2 into clamp 1 and clamp 2 respectively, and seal the end cap onto the upper open end of the pressure tube body to complete the assembly of the shock tube assembly; at the same time, fit the packer onto the outside of the lower end of the pressure tube body.

[0022] Step 3: Lower the shock tube assembly into the target fracturing section inside the wellbore and set the packer inside the wellbore;

[0023] Step 4: Keep the exhaust valve 1 and the pressure relief valve closed, start the vacuum pump, open the connecting valve 1 and the connecting valve 2, and use the vacuum pipeline to perform vacuuming operations on the high-pressure chamber and the double-membrane chamber. When the high-pressure chamber reaches the set vacuum level 1, close the connecting valve 1. When the double-membrane chamber reaches the set vacuum level 2, close the connecting valve 2.

[0024] Step 5: Control the opening of the second gas outlet valve to deliver oxygen from the oxygen delivery pipeline into the combustion and explosion chamber. At the same time, use the combustible gas concentration detector to collect the concentration signal of the combustible gas in the combustion and explosion chamber in real time and send it to the controller. The controller obtains the concentration data of the combustible gas based on the concentration signal. When the concentration data of the combustible gas reaches the set threshold, control the closing of the second gas outlet valve and let it stand for a set time to allow the combustible gas to mix fully.

[0025] Step Six: Open the outlet valve one, and open the filling valve one and filling valve two. Use the high-pressure gas supply line and the double-membrane gas supply line to fill the high-pressure chamber and the double-membrane chamber with the driving gas from the high-pressure gas tank. When the high-pressure chamber reaches the set filling pressure one, close the filling valve one. When the double-membrane chamber reaches the set filling pressure two, close the filling valve two. After both filling valves one and two are closed, close the outlet valve one.

[0026] Step 7: Control the pressure relief valve to open, and use the double-diaphragm venting pipeline to quickly depressurize the double-diaphragm chamber, causing the pressure difference between the high-pressure chamber and the double-diaphragm chamber to increase instantaneously. The instantaneously increased pressure difference causes the gas in the high-pressure chamber to break through diaphragm one and diaphragm two at high speed and enter the combustion and explosion chamber. Driven by the high-speed airflow, the combustion and explosion gas generates compression waves that quickly superimpose to form a shock wave. The compression effect of the shock wave causes the temperature and pressure of the combustion and explosion gas in the combustion and explosion chamber to rise sharply. At the same time, when the combustion and explosion gas is compressed again by the reflected shock wave formed after being reflected from the end of the combustion and explosion chamber, its temperature and pressure rise further, thus causing global self-ignition within a microsecond time and rapidly expanding into combustion and explosion.

[0027] As a preferred option, in step five, the time is set to 1 to 2 hours.

[0028] As a preferred option, in step six, the inflation pressure two is half of the inflation pressure one.

[0029] This invention provides a shock wave ignition-based in-situ methane combustion and explosion fracturing system and method, aiming to offer a novel technical path and solution for the further optimization and upgrading of unconventional natural gas development technologies. Specifically, the charging pressure of the high-pressure chamber and the dual-membrane chamber is first determined based on the target reservoir conditions, and suitable diaphragms one and two are selected to effectively ensure that diaphragms one and two can rapidly break under the subsequent pressure differential. Then, a packer fitted to the lower end of the pressure-bearing pipe is seated in the wellbore, facilitating the formation of a combustion and explosion chamber below diaphragm two that is isolated from the upper wellbore space, the dual-membrane chamber, and the high-pressure chamber, thus effectively ensuring the subsequent combustion and explosion effect. Next, a vacuum pump is used to evacuate the high-pressure chamber and the dual-membrane chamber, which not only removes gases from both chambers that adversely affect shock wave generation or the subsequent combustion and explosion process, but also effectively ensures that a larger amount of driving gas can be charged subsequently. Then, driving gases at different pressures are injected into the high-pressure chamber and the dual-membrane chamber, respectively. The pressure relief valve is then opened to rapidly depressurize the dual-membrane chamber. Since the dual-membrane chamber is located between the high-pressure chamber and the combustion chamber, the driving gas, through the pressure difference effect, rapidly causes diaphragms one and two to rupture sequentially and enter the combustion chamber. Driven by the high-speed airflow, the combustion gas generates compression waves that quickly form shock waves. The compression effect of these shock waves causes a sharp increase in the temperature and pressure of the mixed gas within the combustion chamber. When the gas is further compressed by the reflected shock waves formed after being reflected by the combustion chamber, its temperature and pressure increase even further, subsequently leading to spontaneous combustion and the generation of multiple ignition points, which then rapidly expand into a combustion explosion, significantly enhancing the combustion explosion effect. In this way, the shock waves, high-pressure gas, and high-temperature effects generated by the combustion explosion can be effectively utilized to synergistically impact the target reservoir, promoting the development of fractures within the wellbore and forming a complex fracture network, greatly improving the recovery rate.

[0030] This invention utilizes the principle of shock waves to rapidly generate shock waves under pressure differential. Leveraging the shock wave's ability to heat substances to extremely high temperatures within microseconds, a combustible mixture can rapidly ignite and explode under high temperature and pressure. Due to the extremely high initial temperature and pressure, compared to normal temperature and pressure conditions, the high-temperature, high-pressure conditions result in a greater number of activated molecules in the gas mixture, significantly increasing the probability of molecular collisions and releasing more total energy. Simultaneously, the energy density released per unit time is also significantly increased. Furthermore, the instantaneous pressure of high-temperature, high-pressure combustion can reach hundreds of megapascals, while the pressure of normal temperature explosions is typically below 2 MPa. Therefore, the combustion process of this invention releases more energy, generates a stronger shock wave, produces greater destructive force, and has a wider impact range, thus significantly enhancing the effect of in-situ methane combustion and fracturing. In addition, the combustion energy can be precisely controlled by adjusting the driving gas injection pressure, and multiple shock wave combustion and explosion operations can be performed consecutively to more effectively enhance the effect of in-situ methane combustion and fracturing. Compared to conventional ignition methods, the shock wave ignition method in this invention can rapidly increase the initial temperature and pressure of the mixed gas in the combustion well, and generate stronger combustion and explosion impact energy through overall heating and ignition, effectively enhancing the combustion and explosion efficiency.

[0031] This method is simple to implement, has ideal combustion and explosion effects, reliable performance, and a high safety factor. It enables rapid heating and pressurization of combustion and explosion gases in the wellbore and global multi-point ignition operations. It can effectively enhance the in-situ combustion and explosion fracturing effect of methane and significantly improve the extraction efficiency and effect of unconventional natural gas. It has broad application prospects and great practical value. Attached Figure Description

[0032] Figure 1 This is an assembly diagram of the methane in-situ combustion and explosion fracturing system in this invention;

[0033] Figure 2 This is a schematic diagram of the structure of the methane in-situ combustion and explosion fracturing system in this invention;

[0034] Figure 3 This is a schematic diagram of the assembly of clamp one, clamp two and pressure-bearing pipe body in this invention;

[0035] Figure 4 This is a block diagram of the control section in this invention.

[0036] In the diagram: 1. Pressure-bearing pipe body; 2. End cap; 3. Clamp one; 4. Clamp two; 5. Diaphragm one; 6. Diaphragm two; 7. High-pressure chamber; 8. Double-diaphragm chamber; 9. High-pressure gas tank; 10. High-pressure gas supply line; 11. Double-diaphragm gas supply line; 12. Vacuum pump; 13. Vacuum extraction line; 14. Double-diaphragm venting line; 15. Packer; 16. Explosion chamber; 17. Oxygen cylinder; 18. Oxygen delivery line. 19. Combustible gas concentration detector; 20. Upper section pipe; 21. Middle section pipe; 22. Lower section pipe; 23. Upper diaphragm flange one; 24. Lower diaphragm flange one; 25. Fastening bolt one; 26. Sealing ring one; 27. Lower diaphragm flange two; 28. Lower diaphragm flange two; 29. ​​Fastening bolt two; 30. Sealing ring two; 31. Connecting pipeline one; 32. Connecting pipeline two; 33. Well shaft. Detailed Implementation

[0037] The invention will now be further described with reference to the accompanying drawings.

[0038] like Figures 1 to 4 As shown, the present invention provides a methane in-situ combustion and explosion fracturing system based on shock wave ignition, including a shock wave ignition unit, a methane combustion and explosion containment unit, and a combustion-supporting agent delivery unit;

[0039] The shock wave ignition unit includes a shock tube assembly, a gas supply assembly, and a gas exhaust assembly; the shock tube assembly includes a pressure-bearing tube body 1, an end cap 2, a clamping device 3, a clamping device 4, a diaphragm 5, and a diaphragm 6; the pressure-bearing tube body 1 is disposed in the target fracturing section inside the wellbore 33; the end cap 2 is sealed to the upper open end of the pressure-bearing tube body 1; the clamping device 3 and the clamping device 4 are connected in series with the lower section of the pressure-bearing tube body 1 at intervals; the diaphragm 5 and the diaphragm 6 are disposed with intervals inside the pressure-bearing tube body 1, and are respectively disposed at the positions of the clamping device 3 and the clamping device 4. The edges of diaphragm 5 and diaphragm 6 are respectively clamped inside clamping device 3 and clamping device 4; a high-pressure chamber 7 is formed inside the pressure-bearing tube 1 between end cap 2 and diaphragm 5, and a double-diaphragm chamber 8 is formed between diaphragm 5 and diaphragm 6; the gas filling assembly includes a high-pressure gas tank 9, a high-pressure gas supply pipeline 10, and a double-diaphragm gas supply pipeline 11; the high-pressure gas tank 9 is placed on the ground and filled with driving gas; a gas filling valve 1 and a gas filling valve 2 are respectively connected in series on the high-pressure gas supply pipeline 10 and the double-diaphragm gas supply pipeline 11, and the two gas supply pipelines (high-pressure gas supply pipeline 10 and double-diaphragm gas supply pipeline 11) are connected in series. The inlet end of each gas pipeline 11 is connected to the outlet valve on the high-pressure gas tank 9, and its outlet end extends into the wellbore 33. The outlet end of the high-pressure gas supply pipeline 10 is connected to a pre-reserved injection port on the end cap 2, and then communicates with the high-pressure chamber 7 through the pre-reserved injection port. The outlet end of the dual-membrane gas supply pipeline 11 communicates with the dual-membrane chamber 8 through a pre-reserved injection port on the pressure-bearing pipe body 1. The exhaust assembly includes a vacuum pump 12, a vacuum extraction pipeline 13, and a dual-membrane venting pipeline 14. The vacuum pump 12 is located on the ground. The inlet section of the vacuum extraction pipeline 13 extends into the wellbore 33. Connecting pipe 1 31 and connecting pipe 2 32 are connected at intervals. Connecting valve 1 and connecting valve 2 are connected in series in the middle sections of connecting pipe 1 31 and connecting pipe 2 32 respectively. Connecting pipe 1 31 is connected to high pressure chamber 7 through reserved exhaust hole 1 on pressure bearing pipe 1. Connecting pipe 2 32 is connected to double membrane chamber 8 through reserved exhaust hole 2 on pressure bearing pipe 1. The outlet end of vacuum pipe 13 is connected to the inlet end of vacuum pump 12. A pressure relief valve is connected in series on the double membrane vent pipe 14. Its inlet end is connected to the inlet section of connecting pipe 2 32, and its outlet end is connected to the outside atmosphere.

[0040] The methane combustion and explosion containment unit is a packer 15. The packer 15 is fitted onto the outside of the lower end of the pressure-bearing pipe body 1 and is seated in the wellbore 33, forming a combustion and explosion chamber 16 between the packer 15, the wellbore 33 and the diaphragm 6.

[0041] The combustion accelerator delivery unit includes an oxygen cylinder 17, an oxygen delivery pipeline 18, and a combustible gas concentration detector 14. The oxygen cylinder 17 is located on the ground and is filled with a combustion accelerator, preferably oxygen. The inlet of the oxygen delivery pipeline 18 is connected to the outlet valve of the oxygen cylinder 17, and its outlet extends into the well shaft 33. After passing through the packer 15, it connects to the combustion and explosion chamber 16. The combustible gas concentration detector 14 is installed at the outlet of the oxygen delivery pipeline 18 and is used to collect the concentration signal of the mixed combustion and explosion gas in the combustion and explosion chamber 16 in real time and send it to the controller. The controller obtains the concentration data of the mixed combustion and explosion gas based on the concentration signal of the mixed combustion and explosion gas and determines whether the concentration data of the mixed combustion and explosion gas reaches the optimal combustion and explosion concentration equivalent ratio (set threshold).

[0042] To facilitate fully automated control, a controller is also included, which is connected to the combustible gas concentration detector 14, outlet valve one, outlet valve two, gas filling valve one, gas filling valve two, pressure relief valve, connecting valve one, connecting valve two, and vacuum pump 12. Preferably, the controller is a PLC controller.

[0043] In order to facilitate the clamping operation of diaphragms one and two, and to ensure the overall sealing effect and pressure resistance after clamping, the pressure-bearing tube 1 includes an upper tube 20, a middle tube 21 and a lower tube 22 that are coaxially distributed from top to bottom.

[0044] The clamping device 3 includes an upper diaphragm flange 23, a lower diaphragm flange 24, a sealing ring 26, and fastening bolts 25. The upper diaphragm flange 23 is fixedly fitted onto the outside of the lower end of the upper section of the pipe body 20. The lower diaphragm flange 24 is fixedly fitted onto the outside of the upper end of the middle section of the pipe body 21, and is distributed vertically opposite to the upper diaphragm flange 23. The sealing ring 26 is disposed between the upper diaphragm flange 23 and the lower diaphragm flange 24. Multiple fastening bolts 25 are evenly inserted circumferentially into multiple pairs of screw holes between the upper diaphragm flange 23 and the lower diaphragm flange 24, and are locked and fixedly connected. The outer edge of the diaphragm 5 is disposed between the upper diaphragm flange 23 and the lower diaphragm flange 24, and is fitted and connected to the inner edge of the sealing ring 26. This effectively ensures the sealing performance of the diaphragm 5 and effectively prevents air leakage.

[0045] The clamping device 24 includes an upper clamping flange 27, a lower clamping flange 28, a sealing ring 30, and fastening bolts 29. The upper clamping flange 27 is fixedly fitted onto the outside of the lower end of the middle section pipe body 21. The lower clamping flange 28 is fixedly fitted onto the outside of the upper end of the lower section pipe body 22, and is distributed vertically opposite to the upper clamping flange 27. The sealing ring 30 is disposed between the upper clamping flange 27 and the lower clamping flange 28. Multiple fastening bolts 29 are evenly inserted circumferentially into multiple pairs of screw holes between the upper clamping flange 27 and the lower clamping flange 28, and lock the two together. The outer edge of the diaphragm 26 is disposed between the upper clamping flange 27 and the lower clamping flange 28, and is fitted and connected to the inner edge of the sealing ring 30. This effectively ensures the sealing performance of the diaphragm 26 and prevents air leakage.

[0046] The dual-membrane chamber 8, serving as the filter section connecting the high-pressure chamber 7 and the combustion chamber 16, is crucial for generating shock waves. The selection of diaphragm 5 and diaphragm 6 is of paramount importance. Both diaphragm 5 and diaphragm 6 are made of the same model and are made of industrial pure aluminum membranes, conforming to specifications based on material, type, and membrane rupture pressure difference. More preferably, diaphragm 5 and diaphragm 6 are pre-treated with high-temperature annealing to reduce the hardness of the aluminum membrane, increase its plasticity, and increase the membrane rupture pressure difference. Furthermore, cross grooves of different widths and thicknesses are engraved to further reduce the hardness of the aluminum membrane, facilitating an increase in the membrane rupture pressure difference. At the same time, this effectively prevents fragments from splashing during the rupture process.

[0047] To ensure a good seal at the connection, the end cap 2 and the pressure-bearing pipe body 1 are sealed together by a graphite sealing ring.

[0048] To facilitate convenient control of the connection status between the high-pressure gas supply pipeline and the dual-membrane gas supply pipeline and the high-pressure gas tank, the first outlet valve is a three-way valve, which is connected to the inlet end of the high-pressure gas supply pipeline 10 and the inlet end of the dual-membrane gas supply pipeline 11 respectively.

[0049] To ensure the effective formation of the shock wave and to ensure the combustion and explosion effect, the high-pressure gas tank 9 is filled with pure hydrogen, pure helium, pure nitrogen, or pure argon, or a mixture of hydrogen, helium, nitrogen, and argon in a set ratio.

[0050] In this invention, an end cap is sealed at the upper open end of the pressure-bearing pipe. Simultaneously, clamps one and two, connected in series with the pressure-bearing pipe, are used to assemble diaphragms one and two into the interior of the pipe. This allows the inner cavity of the pressure-bearing pipe to be divided into three sections from top to bottom using the diaphragms one and two, which are spaced apart vertically. The section between the end cap and diaphragm one forms a high-pressure chamber, the section between diaphragms one and two forms a double-diaphragm chamber, and the section below diaphragm two can be directly connected to the wellbore. Connecting pipes one and two, located in the air inlet section of the vacuum pump, connect the high-pressure chamber and the double-diaphragm chamber, respectively. This facilitates vacuuming of both chambers using a vacuum pump. Separate connecting valves one and two are installed on connecting pipes one and two, respectively, allowing for independent control to effectively ensure that the vacuum levels in both the high-pressure chamber and the double-diaphragm chamber meet operational requirements. By connecting the high-pressure gas supply pipeline and the double-membrane gas supply pipeline, which are connected to the high-pressure chamber and the double-membrane chamber respectively, it is convenient to add driving gas to the high-pressure chamber and the double-membrane chamber after the vacuuming operation. By separately installing filling valves one and two on the high-pressure gas supply pipeline and the double-membrane gas supply pipeline, it is possible to effectively ensure that the filling pressure of both the high-pressure chamber and the double-membrane chamber meets the operational requirements through independent control. A packer is fitted at the lower end of the pressure-bearing pipe and is seated inside the wellbore. This packer effectively seals the annulus between the pressure-bearing pipe and the wellbore, thereby forming a combustion and explosion chamber below diaphragm one. An oxygen delivery pipeline connected to an oxygen cylinder passes through the packer and connects to the combustion and explosion chamber, facilitating the injection of oxygen into the combustion and explosion chamber. The installation of a combustible gas concentration detector allows for real-time monitoring of the concentration data of the mixed combustible and explosive gases in the combustion and explosion chamber, enabling timely determination of whether the required standards for combustion and explosion have been met. A double-membrane venting line is connected to the second connecting line, and a pressure relief valve is connected in series with the double-membrane venting line. On the one hand, the pressure relief valve can ensure efficient and smooth vacuuming operations when closed, and on the other hand, it can rapidly depressurize the double-membrane chamber when open. Since the double-membrane chamber is located between the high-pressure chamber and the combustion and explosion chamber, the pressure difference effect can cause the first and second diaphragms to rupture rapidly in sequence. This allows the driving gas in the high-pressure chamber to quickly break through the first and second diaphragms under the action of the pressure difference and enter the combustion and explosion chamber, where a shock wave can be rapidly generated. Thus, the action of the shock wave can cause the combustion and explosion gas to spontaneously ignite. This process can generate multiple ignition points simultaneously, thereby effectively increasing the ignition energy. Based on this, it can rapidly expand into combustion and explosion, which can significantly enhance the combustion and explosion effect and is conducive to creating a complex and ideally connected crack network structure over a large area after the combustion and explosion.The system in this invention can generate a huge pressure difference instantaneously through vacuuming, pressurizing, and rapidly depressurizing, thereby enabling instantaneous membrane rupture. At the moment of rupture, a shock wave is formed in the low-pressure section. The temperature and pressure of the mixed gas in the low-pressure end and the connected combustion chamber rise sharply under the action of the shock wave, and ignition and explosion occur under the influence of the reflected shock wave. The temperature and pressure increase effect of the shock wave and the overall ignition mode can significantly promote the methane combustion effect, significantly improving the reservoir modification effect of in-situ methane combustion fracturing. Selecting a suitable membrane rupture method is a key step in generating a stable shock wave in the shock tube. The innovative double-diaphragm structure of this invention features convenient operation, rapid response, and good reusability.

[0051] The system has a reasonable structure and simple operation. It can instantly generate high-temperature and high-pressure shock waves in the combustion and explosion space and ignite the gas through the shock waves. Its ignition energy is high, which can significantly enhance the combustion and explosion effect. It can construct a complex fracture network structure, which is conducive to improving the extraction efficiency and extraction effect of unconventional natural gas.

[0052] This invention also provides a method for in-situ combustion and explosion fracturing of methane based on shock wave ignition, employing a methane in-situ combustion and explosion fracturing system based on shock wave ignition, comprising the following steps:

[0053] Step 1: Collect geological parameters and exploration data of the target reservoir, and determine the inflation pressure of the high-pressure chamber 7 and the double-membrane chamber 8 based on the reservoir conditions, and in combination with the preset combustion pressure and temperature, and then select the appropriate membrane 1 5 and membrane 2 6.

[0054] Step 2: Clamp diaphragm 5 and diaphragm 6 into clamp 3 and clamp 4 respectively, and seal end cap 2 onto the upper open end of pressure tube 1 to complete the assembly of shock tube assembly; at the same time, fit packer 15 onto the outside of the lower end of pressure tube 1.

[0055] Step 3: Lower the shock tube assembly into the target fracturing section inside the wellbore 33 and set the packer 15 inside the wellbore 33;

[0056] Step 4: Keep the exhaust valve 1 and the pressure relief valve closed, start the vacuum pump 12, and open the connecting valve 1 and the connecting valve 2. Use the vacuum pumping pipeline 13 to perform vacuum pumping on the high-pressure chamber 7 and the double-membrane chamber 8. When the high-pressure chamber 7 reaches the set vacuum level 1, control the connecting valve 1 to close. When the double-membrane chamber 8 reaches the set vacuum level 2, control the connecting valve 2 to close. Preferably, pressure sensors 1 and 2 are connected to the connecting pipelines 1 and 2 respectively. Pressure sensors 1 and 2 are used to collect pressure signals 1 and 2 of the high-pressure chamber 7 and the double-membrane chamber 8 in real time during the vacuum pumping process and send them to the controller. The controller obtains the vacuum level 1 of the high-pressure chamber 7 and the vacuum level 2 of the double-membrane chamber 8 based on the pressure signals 1 and 2.

[0057] Step 5: Control the opening of the second gas outlet valve, and use the oxygen delivery pipeline 18 to deliver oxygen from the oxygen cylinder 17 to the combustion and explosion chamber 16. At the same time, use the combustible gas concentration detector 14 to collect the concentration signal of the combustible gas (mixture of methane and oxygen) in the combustion and explosion chamber 16 in real time, and send it to the controller. The controller obtains the concentration data of the combustible gas based on the concentration signal of the combustible gas. When the concentration data of the combustible gas reaches the set threshold, control the closing of the second gas outlet valve, and let it stand for a set time to allow the combustible gas to mix fully.

[0058] Step Six: Control the opening of the outlet valve 1, the filling valve 1, and the filling valve 2 to inject the driving gas from the high-pressure gas tank 9 into the high-pressure chamber 7 and the double-membrane chamber 8 using the high-pressure gas supply line 10 and the double-membrane gas supply line 11, respectively. When the high-pressure chamber 7 reaches the set filling pressure 1, control the closing of the filling valve 1. When the double-membrane chamber 8 reaches the set filling pressure 2, control the closing of the filling valve 2. After both filling valves 1 and 2 are closed, control the closing of the outlet valve 1. Preferably, pressure sensors 1 and 2 on the connecting lines 1 and 2 can be used to collect the pressure signal 3 in the high-pressure chamber 7 and the pressure signal 4 in the double-membrane chamber 8 in real time during the filling process. The controller obtains the filling pressure 1 and filling pressure 2 based on the pressure signals 3 and 4, respectively.

[0059] Step 7: Control the pressure relief valve to open, and use the double-diaphragm venting line 14 to quickly depressurize the double-diaphragm chamber 8, so that the pressure difference between the high-pressure chamber 7 and the double-diaphragm chamber 8 increases instantaneously. The instantaneously increased pressure difference causes the gas in the high-pressure chamber 7 to break through diaphragm 5 and diaphragm 6 at high speed and enter the combustion and explosion chamber 16 (low-pressure section). Under the impetus of the high-speed airflow, the combustion and explosion gas generates compression waves and quickly superimposes to form a shock wave. The compression effect of the shock wave causes the temperature and pressure of the combustion and explosion gas in the combustion and explosion chamber 16 to rise sharply. At the same time, when the combustion and explosion gas is compressed again by the reflected shock wave formed after being reflected by the end of the combustion and explosion chamber 16, its temperature and pressure rise further, and then global self-ignition occurs within a microsecond time and rapidly expands into combustion and explosion.

[0060] As a preferred option, in step five, the time is set to 1 to 2 hours.

[0061] As a preferred option, in step six, the inflation pressure two is half of the inflation pressure one.

[0062] This invention provides a shock wave ignition-based in-situ methane combustion and explosion fracturing system and method, aiming to offer a novel technical path and solution for the further optimization and upgrading of unconventional natural gas development technologies. Specifically, the charging pressure of the high-pressure chamber and the dual-membrane chamber is first determined based on the target reservoir conditions, and suitable diaphragms one and two are selected to effectively ensure that diaphragms one and two can rapidly break under the subsequent pressure differential. Then, a packer fitted to the lower end of the pressure-bearing pipe is seated in the wellbore, facilitating the formation of a combustion and explosion chamber below diaphragm two that is isolated from the upper wellbore space, the dual-membrane chamber, and the high-pressure chamber, thus effectively ensuring the subsequent combustion and explosion effect. Next, a vacuum pump is used to evacuate the high-pressure chamber and the dual-membrane chamber, which not only removes gases from both chambers that adversely affect shock wave generation or the subsequent combustion and explosion process, but also effectively ensures that a larger amount of driving gas can be charged subsequently. Then, driving gases at different pressures are injected into the high-pressure chamber and the dual-membrane chamber, respectively. The pressure relief valve is then opened to rapidly depressurize the dual-membrane chamber. Since the dual-membrane chamber is located between the high-pressure chamber and the combustion chamber, the driving gas, through the pressure difference effect, rapidly causes diaphragms one and two to rupture sequentially and enter the combustion chamber. Driven by the high-speed airflow, the combustion gas generates compression waves that quickly form shock waves. The compression effect of these shock waves causes a sharp increase in the temperature and pressure of the mixed gas within the combustion chamber. When the gas is further compressed by the reflected shock waves formed after being reflected by the combustion chamber, its temperature and pressure increase even further, subsequently leading to spontaneous combustion and the generation of multiple ignition points, which then rapidly expand into a combustion explosion, significantly enhancing the combustion explosion effect. In this way, the shock waves, high-pressure gas, and high-temperature effects generated by the combustion explosion can be effectively utilized to synergistically impact the target reservoir, promoting the development of fractures within the wellbore and forming a complex fracture network, greatly improving the recovery rate.

[0063] This invention utilizes the principle of shock waves to rapidly generate shock waves under pressure differential. Leveraging the shock wave's ability to heat substances to extremely high temperatures within microseconds, a combustible mixture can rapidly ignite and explode under high temperature and pressure. Due to the extremely high initial temperature and pressure, compared to normal temperature and pressure conditions, the high-temperature, high-pressure conditions result in a greater number of activated molecules in the gas mixture, significantly increasing the probability of molecular collisions and releasing more total energy. Simultaneously, the energy density released per unit time is also significantly increased. Furthermore, the instantaneous pressure of high-temperature, high-pressure combustion can reach hundreds of megapascals, while the pressure of normal temperature explosions is typically below 2 MPa. Therefore, the combustion process of this invention releases more energy, generates a stronger shock wave, produces greater destructive force, and has a wider impact range, thus significantly enhancing the effect of in-situ methane combustion and fracturing. In addition, the combustion energy can be precisely controlled by adjusting the driving gas injection pressure, and multiple shock wave combustion and explosion operations can be performed consecutively to more effectively enhance the effect of in-situ methane combustion and fracturing. Compared to conventional ignition methods, the shock wave ignition method in this invention can rapidly increase the initial temperature and pressure of the mixed gas in the combustion wellbore, and generate stronger combustion and explosion impact energy through overall heating and ignition, effectively enhancing combustion and explosion efficiency. This method is simple to implement, has ideal combustion and explosion effects, reliable performance, and a high safety factor. It enables rapid heating and pressurization of the combustion and explosion gas in the wellbore and global multi-point ignition operations, effectively enhancing the in-situ combustion and explosion fracturing effect of methane, and significantly improving the extraction efficiency and effect of unconventional natural gas. It has broad application prospects and great practical value.

Claims

1. A methane in-situ combustion and explosion fracturing system based on shock wave ignition, comprising a shock wave ignition unit, characterized in that, It also includes a methane combustion and explosion containment unit and a combustion-supporting agent delivery unit; The shock wave ignition unit includes a shock tube assembly, a gas supply assembly, and a gas exhaust assembly; the shock tube assembly includes a pressure-bearing tube body (1), an end cap (2), a clamping device one (3), a clamping device two (4), a diaphragm one (5), and a diaphragm two (6); the pressure-bearing tube body (1) is located in the target fracturing section inside the wellbore (33); the end cap (2) is encapsulated at the upper open end of the pressure-bearing tube body (1); the clamping device one (3) and the clamping device two (4) are connected in series on the lower section of the pressure-bearing tube body (1) at intervals; the diaphragm one (5) and the diaphragm two (6) are arranged at intervals inside the pressure-bearing tube body (1), and the diaphragm... The edges of diaphragm 1 (5) and diaphragm 2 (6) are respectively clamped inside clamp 1 (3) and clamp 2 (4); the interior of the pressure-bearing tube (1) forms a high-pressure chamber (7) between end cap (2) and diaphragm 1 (5), and a double-diaphragm chamber (8) between diaphragm 1 (5) and diaphragm 2 (6); the gas filling assembly includes a high-pressure gas tank (9), a high-pressure gas supply pipeline (10) and a double-diaphragm gas supply pipeline (11); the high-pressure gas tank (9) is set on the ground; gas filling valve 1 and gas filling valve 2 are respectively connected in series on the high-pressure gas supply pipeline (10) and the double-diaphragm gas supply pipeline (11), and the gas inlet ends of the two gas supply pipelines are connected to... The outlet valve on the high-pressure gas tank (9) is connected to the wellbore (33), and the outlet end of the high-pressure gas supply pipeline (10) is connected to the reserved air injection hole on the end cap (2). The outlet end of the double-membrane gas supply pipeline (11) is connected to the double-membrane chamber (8) through the reserved air injection hole on the pressure-bearing pipe body (1). The exhaust assembly includes a vacuum pump (12), a vacuum pumping pipeline (13), and a double-membrane venting pipeline (14). The vacuum pump (12) is installed on the ground. The air inlet section of the vacuum pumping pipeline (13) extends into the wellbore (33) and is connected to the connecting pipeline (3) at intervals above and below. 1) and connecting pipe 2 (32), connecting pipe 1 (31) and connecting pipe 2 (32) are respectively connected in series with connecting valve 1 and connecting valve 2 in the middle section. Connecting pipe 1 (31) is connected to high pressure chamber (7) through reserved exhaust hole 1 on pressure-bearing pipe body (1). Connecting pipe 2 (32) is connected to double membrane chamber (8) through reserved exhaust hole 2 on pressure-bearing pipe body (1). The outlet end of vacuum pipe (13) is connected to the inlet end of vacuum pump (12). The double membrane venting pipe (14) is connected in series with pressure relief valve. Its inlet end is connected to the inlet section of connecting pipe 2 (32). Its outlet end is connected to the outside atmosphere. The methane combustion and explosion sealing unit is a packer (15). The packer (15) is fitted on the outside of the lower end of the pressure-bearing pipe body (1) and is seated in the well barrel (33). A combustion and explosion chamber (16) is formed between the packer (15), the well barrel (33) and the second diaphragm (6). The combustion aid delivery unit includes an oxygen cylinder (17), an oxygen delivery pipeline (18), and a combustible gas concentration detector (14); the oxygen cylinder (17) is set on the ground; the inlet end of the oxygen delivery pipeline (18) is connected to the outlet valve of the oxygen cylinder (17), and its outlet end extends into the well shaft (33) and communicates with the combustion and explosion chamber (16) after passing through the packer (15); the combustible gas concentration detector (14) is installed at the outlet end of the oxygen delivery pipeline (18).

2. The in-situ methane combustion and explosion fracturing system based on shock wave ignition according to claim 1, characterized in that, It also includes a controller, which is connected to a combustible gas concentration detector (14), gas outlet valve one, gas outlet valve two, gas filling valve one, gas filling valve two, pressure relief valve, connecting valve one, connecting valve two and vacuum pump (12).

3. A methane in-situ combustion and explosion fracturing system based on shock wave ignition according to claim 1 or 2, characterized in that, The pressure-bearing pipe body (1) includes an upper pipe body (20), a middle pipe body (21) and a lower pipe body (22) that are coaxially distributed from top to bottom. The clamping device 1 (3) includes an upper clamping flange 1 (23), a lower clamping flange 1 (24), a sealing ring 1 (26), and fastening bolts 1 (25); the upper clamping flange 1 (23) is fixedly fitted on the outside of the lower end of the upper section pipe body (20); the lower clamping flange 1 (24) is fixedly fitted on the outside of the upper end of the middle section pipe body (21), and is distributed vertically opposite to the upper clamping flange 1 (23); the sealing ring 1 (26) is disposed between the upper clamping flange 1 (23) and the lower clamping flange 1 (24); multiple fastening bolts 1 (25) are evenly inserted in multiple pairs of screw holes between the upper clamping flange 1 (23) and the lower clamping flange 1 (24) and lock the two together; wherein, the outer edge of the diaphragm 1 (5) is disposed between the upper clamping flange 1 (23) and the lower clamping flange 1 (24), and is fitted and connected to the inner edge of the sealing ring 1 (26); The clamping device 2 (4) includes an upper clamping flange 2 (27), a lower clamping flange 2 (28), a sealing ring 2 (30), and a fastening bolt 2 (29); the upper clamping flange 2 (27) is fixedly fitted on the outside of the lower end of the middle section pipe body (21); the lower clamping flange 2 (28) is fixedly fitted on the outside of the upper end of the lower section pipe body (22), and is distributed vertically opposite to the upper clamping flange 2 (27); the sealing ring 2 (30) is disposed between the upper clamping flange 2 (27) and the lower clamping flange 2 (28); multiple fastening bolts 2 (29) are evenly inserted circumferentially into multiple pairs of screw holes between the upper clamping flange 2 (27) and the lower clamping flange 2 (28), and lock the two together; wherein, the outer edge of the diaphragm 2 (6) is disposed between the upper clamping flange 2 (27) and the lower clamping flange 2 (28), and is fitted and connected to the inner edge of the sealing ring 2 (30).

4. The in-situ methane combustion and explosion fracturing system based on shock wave ignition according to claim 3, characterized in that, Both the first diaphragm (5) and the second diaphragm (6) are made of industrial pure aluminum film.

5. The in-situ methane combustion and explosion fracturing system based on shock wave ignition according to claim 4, characterized in that, The end cap (2) and the pressure-bearing pipe body (1) are sealed together by a graphite sealing ring.

6. The in-situ methane combustion and explosion fracturing system based on shock wave ignition according to claim 5, characterized in that, The first air outlet valve is a three-way valve, and is connected to the air inlet of the high-pressure air supply pipeline (10) and the air inlet of the double-membrane air supply pipeline (11) respectively.

7. A methane in-situ combustion and explosion fracturing system based on shock wave ignition according to claim 6, characterized in that, The high-pressure gas tank (9) is filled with pure hydrogen, pure helium, pure nitrogen, or pure argon, or a mixture of hydrogen, helium, nitrogen, and argon in a set ratio.

8. A method for in-situ combustion and explosion fracturing of methane based on shock wave ignition, employing a methane in-situ combustion and explosion fracturing system based on shock wave ignition as described in any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: Collect geological parameters and exploration data of the target reservoir, and determine the inflation pressure of the high-pressure chamber (7) and the double membrane chamber (8) according to the reservoir conditions, and then select the appropriate membrane 1 (5) and membrane 2 (6). Step 2: Clamp diaphragm 1 (5) and diaphragm 2 (6) in clamp 1 (3) and clamp 2 (4) respectively, and seal the end cap (2) on the upper open end of the pressure tube body (1) to complete the assembly of the shock tube assembly; at the same time, put the packer (15) on the outside of the lower end of the pressure tube body (1); Step 3: Lower the shock tube assembly into the target fracturing section inside the wellbore (33) and set the packer (15) inside the wellbore (33); Step 4: Keep the exhaust valve 1 and the pressure relief valve closed, start the vacuum pump (12), open the connecting valve 1 and the connecting valve 2, and use the vacuum pipeline (13) to perform vacuuming operations on the high pressure chamber (7) and the double membrane chamber (8). When the high pressure chamber (7) reaches the set vacuum level 1, close the connecting valve 1. When the double membrane chamber (8) reaches the set vacuum level 2, close the connecting valve 2. Step 5: Control the opening of the second gas outlet valve, and use the oxygen delivery pipeline (18) to deliver the oxygen in the oxygen cylinder (17) to the combustion and explosion chamber (16). At the same time, use the combustible gas concentration detector (14) to collect the concentration signal of the combustible gas in the combustion and explosion chamber (16) in real time and send it to the controller. The controller obtains the concentration data of the combustible gas based on the concentration signal of the combustible gas. When the concentration data of the combustible gas reaches the set threshold, control the second gas outlet valve to close and let it stand for a set time to allow the combustible gas to mix fully. Step 6: Control the opening of the outlet valve 1, control the opening of the filling valve 1 and filling valve 2, and use the high-pressure gas supply line (10) and the double-membrane gas supply line (11) to inject the driving gas in the high-pressure gas tank (9) into the high-pressure chamber (7) and the double-membrane chamber (8) respectively. When the high-pressure chamber (7) reaches the set filling pressure 1, control the closing of the filling valve 1. When the double-membrane chamber (8) reaches the set filling pressure 2, control the closing of the filling valve 2. After both filling valves 1 and 2 are closed, control the closing of the outlet valve 1. Step 7: Control the pressure relief valve to open and use the double-membrane venting pipeline (14) to quickly depressurize the double-membrane chamber (8), so that the pressure difference between the high-pressure chamber (7) and the double-membrane chamber (8) increases instantaneously. The instantaneously increased pressure difference causes the gas in the high-pressure chamber (7) to break through the first diaphragm (5) and the second diaphragm (6) at high speed and enter the combustion and explosion chamber (16). Under the impetus of the high-speed airflow, the combustion and explosion gas generates compression waves and quickly superimposes to form a shock wave. The compression effect of the shock wave causes the temperature and pressure of the combustion and explosion gas in the combustion and explosion chamber (16) to rise sharply. At the same time, when the combustion and explosion gas is compressed again by the reflected shock wave formed after being reflected by the end of the combustion and explosion chamber (16), its temperature and pressure further increase, and then global self-ignition occurs within a microsecond time and rapidly expands into combustion and explosion.

9. The in-situ combustion and explosion fracturing method for methane based on shock wave ignition according to claim 8, characterized in that, In step five, the time is set to 1 to 2 hours.

10. The in-situ combustion and explosion fracturing method for methane based on shock wave ignition according to claim 8, characterized in that, In step six, inflation pressure two is half of inflation pressure one.

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