Deep coal seam group in-situ gasification mining method based on trigger type oxygen releasing catalyst

Abstract

This invention discloses a multi-well layout method for in-situ gasification mining of deep coal seams based on triggered detonator oxygen release catalysis, belonging to the field of deep coal seam underground gasification technology. The method includes the following steps: well network layout and core equipment pre-installation, supercritical CO2 coal seam permeability enhancement pretreatment, triggered detonator foam preparation and segmented injection, acoustic-microwave synergistic triggering and reaction heat start-up, supercritical water main gasification and mixed fluid deep quality improvement, and syngas extraction and system safety shutdown. This invention achieves mass transfer channel transformation in deep, low-permeability coal seams by constructing a multi-well network, combined with precise oxygen release catalysis using triggered detonator foam, enhanced reaction by supercritical CO2 or supercritical water injection, and microwave radiation to regulate reaction temperature and trigger detonator foam rupture, thereby achieving efficient conversion of coal seam carbon resources and high-purity H2 production, ultimately achieving safe, low-carbon, and efficient in-situ mining of deep coal seams.

Description

Technical Field

[0001] This invention belongs to the field of deep coal seam underground gasification technology, specifically a multi-well arrangement method for in-situ gasification mining of deep coal seam groups based on trigger-activated oxygen release catalysis. Background Technology

[0002] In the coal mining sector, with the continuous increase in mining depth, shallow mines generally face the dilemma of increasing mining depth and accelerated resource depletion. The combined effects of deep resource potential, technological breakthroughs, and energy demand have led to deep coal seams gradually transforming from "auxiliary mining targets" to "primary mining seams." Deep coal seams typically refer to those buried at depths greater than 1000 meters. With increasing mining depth, rising ground temperature, increased ground pressure, and more complex ground stress place higher demands on roadway support, mine ventilation, dust control and cooling, and the prevention of coal and gas outbursts. The high-temperature, high-pressure, and high-stress geological environment of deep coal seams results in significant differences in the physicochemical properties and reaction kinetics of the coal compared to shallow coal seams. Harsh mining conditions and the inability of traditional mining equipment to adapt further complicate the process, posing significant technical challenges and safety risks, leading to extremely low input-output ratios and economic benefits. Therefore, the mining of deep coal seams is extremely difficult.

[0003] Underground coal gasification is an in-situ energy conversion technology that does not require physical mining of coal to the surface. It utilizes the thermal and chemical processes of pyrolysis, oxidation, and reduction in coal under high-temperature conditions to control the combustion process of underground coal seams, systematically converting solid coal into combustible gases in situ. In-situ water-oxygenation of deep coal seams can effectively solve the mining challenges of deep coal seam clusters. However, due to coal's extremely poor thermal conductivity and slow heating rate, the traditional single-injection-production method suffers from a mismatch between the extensive gasifying agent supply and the complex deep environment, leading to difficulty in precise reaction control, low efficiency, and poor safety. Furthermore, the traditional single-injection gasifying agent method cannot precisely control the spatiotemporal distribution of gasifying agent, heat, and catalyst in deep coal seams, making it difficult for reactant gases to fully contact the coal, thus hindering coal gasification.

[0004] In summary, a new method is urgently needed to address the challenges of underground mining of deep coal seams in my country. Summary of the Invention

[0005] The purpose of this invention is to solve the problems existing in the prior art and to provide a multi-well arrangement deep coal seam group in-situ gasification mining method based on trigger-type detonator oxygen release catalysis, so as to further improve the efficiency of in-situ underground mining of deep coal seams and reduce energy consumption.

[0006] This invention is achieved through the following technical solution: A multi-well arrangement method for in-situ gasification exploitation of deep coal seams based on trigger-activated oxygen release catalysis includes the following steps: S1. Supercritical fluid wells and production wells are arranged on the ground, with a double row of injection and detonation wells between them. Each row of injection and detonation wells includes multiple injection and detonation wells that are evenly distributed and spaced apart. Each injection and detonation well is equipped with an acoustic microwave co-generator at the bottom. A feather-shaped branch horizontal well is provided in the middle between the double row of injection and detonation wells. The two ends of the feather-shaped branch horizontal well are connected to the supercritical fluid well and the production well, respectively.

[0007] S2. Connect the supercritical CO2 generator and injection high-pressure pump at the wellhead of the supercritical fluid well to inject supercritical CO2 into the deep coal seam through the supercritical fluid well; turn on the acoustic microwave co-generator at the bottom of the injection well, and radiate energy into the deep coal seam by adjusting the microwave power and frequency to heat and raise the temperature of the supercritical CO2; after the supercritical CO2 is continuously injected for a period of time, stop the injection and perform well shut-in treatment to complete the coal seam permeability enhancement pretreatment.

[0008] S3. Start the detonating agent reaction preparation tank at the wellhead of the detonation well to prepare the trigger-activated detonating agent foam. Connect the high-pressure pump of the detonating agent to the injection pipeline of the detonation well. First, inject clean water into the detonation well to check the seal. After confirming that there is no leakage, switch to injecting the trigger-activated detonating agent foam and inject the trigger-activated detonating agent foam into the detonation well. After the injection is completed, let it stand to allow the trigger-activated detonating agent foam to be evenly distributed in the permeability-enhancing fractures. By monitoring the changes in wellbore pressure, if there is no abnormal drop, the injection of the trigger-activated detonating agent foam is completed.

[0009] S4. Turn on the acoustic-microwave co-generator at the bottom of the injection well, adjust the microwave power and frequency, and radiate energy into the deep coal seam to heat the foam of the trigger-type injection agent; when the temperature of the injection well is stable at 600~650℃, CO concentration ≥30%, and H2 concentration ≥12%, turn off the acoustic-microwave co-generator to complete the reaction heat start-up.

[0010] S5. Switch the injection medium of the supercritical fluid well, connect the supercritical water generator and the injection high-pressure pump, and inject supercritical water into the deep coal seam through the supercritical fluid well to maintain the water-coal ratio (S / C) of 2.5~3.3; at the same time, inject the trigger-type detonating agent foam through the detonation well to improve the gasification reaction.

[0011] S6. Connect the surface extraction equipment at the wellhead of the production well, adjust the negative pressure and extraction flow rate to the set values, extract the gasified syngas, and after desulfurization and decarbonization purification of the extracted syngas, transport it to the syngas storage tank; start the finishing procedure, gradually reduce the negative pressure of the surface extraction equipment to -0.02MPa, shut down the supercritical water generator, supercritical CO2 generator, and injection high-pressure pump, start the nitrogen purging system, purge all wellbores and surface pipelines, monitor the residual CO concentration through the CO sensor, and when the residual CO concentration is <0.1%, stop all equipment to complete the in-situ gasification mining of deep coal seams.

[0012] Furthermore, in step S1 of the above method, after drilling is completed, the deviation of the horizontal section trajectory is checked to be <0.5m to ensure that the entire section is located within the coal seam and there is no phenomenon of penetrating the roof and floor; secondly, a sealing test is performed on all well casings, pressurizing the well casing to 20~25MPa and stabilizing the pressure so that the pressure drop is <0.5MPa as the qualified range, to avoid leakage of the injected fluid in the future.

[0013] The spacing between multiple injection and detonation wells in each row is 100-150m.

[0014] The feather-shaped branch horizontal well includes a main well, with inclined branch wells evenly distributed on both sides of the main well, extending towards the production well and gradually moving away from the main well; the injection and explosion wells are located at the angle between each inclined branch well and the main well.

[0015] Furthermore, in step S2 of the above method, the outlet parameters of the supercritical CO2 generator are adjusted to 35~45℃ and 18~22MPa; the injection flow rate of the injection high-pressure pump is set to 8m³ / h. 3 / h; adjust the microwave power of the acoustic-microwave co-generator to 600-1000W and the frequency to 40-50KHz; raise the supercritical CO2 temperature to 300℃-400℃; stop the injection after 120h of continuous supercritical CO2 injection, and shut down the well for 48h.

[0016] By monitoring the changes in parameters such as permeability, fracture development, and resistivity of the injection-explosion well, the pressure is controlled to remain stable at 10.8~11.2MPa to ensure no risk of crossflow to the production well.

[0017] The pretreatment of coal seam permeability enhancement with supercritical CO2 meets two criteria: first, the permeability of the two injection wells closest to the supercritical fluid well in the dual-row injection-explosion wells is significantly improved, thus proving that the coal seam fractures are effectively enlarged; second, the pressure of the two injection wells closest to the production well in the dual-row injection-explosion wells is controlled within a stable range without sudden increases, to eliminate the risk of cross-flow to the production well; injection is stopped and the wells are shut down to allow CO2 to be fully adsorbed into the coal matrix, reserving a carbon source for the subsequent Boudouard reaction: (C(s) + CO2(sc) = 2CO(g) ΔH = +172.5kJ / mol (endothermic reaction)); after the wells are shut down, the injection-explosion wells are cored to observe whether the coal seam fracture density increases and whether there are any closed dead ends, to confirm that the permeability enhancement meets the criteria.

[0018] Furthermore, in step S3 of the above method, the triggered detonating agent foam is mainly prepared from fluorocarbon surfactants, oxygen, CuO copper-based catalysts and deionized water.

[0019] The sealing verification process specifically involves: injecting clean water into the detonation well, pressurizing it to 15-18 MPa, and stabilizing the pressure for 30 minutes until the pressure drop is less than 0.3 MPa, confirming no leakage; and injecting trigger-type detonating agent foam into the detonation well at an injection pressure of 18 MPa and a flow rate of 0.5 m³ / min. 3 / h, with a cumulative injection of 120m per well 3 After injection, let it stand for 12 hours; if the wellbore pressure is monitored and stabilized at 17~18MPa without any abnormal drop, the trigger-type detonating agent foam injection is complete.

[0020] Furthermore, in step S4 of the above method, the microwave power of the acoustic-microwave co-generator is adjusted to 600W and the frequency to 40KHz.

[0021] The heating-triggered detonator foam is controlled in two stages: the first stage is the heating period, in which the heating rate is controlled at 10~15℃ / h to avoid concentrated bursting of the detonator foam; when the temperature reaches 300~350℃, the heat preservation is paused for 2 hours to allow the heat to spread evenly; the second stage is the reaction start-up period, in which the temperature is continued to rise to 600~650℃.

[0022] During the heating process of the injection and explosion well, monitor the O2 concentration of the injection and explosion well and control the O2 concentration within the range of 5% to 8%. If the O2 concentration exceeds 8%, immediately reduce the microwave power of the acoustic microwave co-generator and turn on the nitrogen purging system at the wellhead of the injection and explosion well until the O2 concentration drops back to 5% to 8%.

[0023] The side reactions occurring in this step, including partial and complete oxidation of carbon and oxidation of hydrogen, are as follows: 2C(s) + O2(g) = 2CO(g) ΔH = -221.0 kJ / mol (exothermic reaction); C(s) + O2(g) = CO2(g) ΔH = -393.5 kJ / mol (strongly exothermic reaction); 2H2(g) + O2(g) = 2H2O(g) ΔH = -483.6 kJ / mol (strongly exothermic reaction).

[0024] Furthermore, in step S5 of the above method, the outlet parameters of the supercritical water generator are adjusted to 400~600℃ and 22~25MPa; the injection flow rate of the injection high-pressure pump is set to 1.2m³ / min. 3 / h; The injection flow rate for the supplementary trigger-type foam detonator is 0.2~0.25m³ / h. 3 / h.

[0025] The gasification reaction stage is divided into the initial basic gas production period and the later deep quality improvement period: During the basic gas production period, the composition of syngas is monitored by pressure and gas composition detectors at the wellhead of the production well. When the volume percentage of H2 is higher than 60% and the volume percentage of CO is lower than 20%, the deep quality improvement period begins.

[0026] During the advanced enhancement phase, the injection medium in the supercritical fluid well was adjusted to a mixture of supercritical water and supercritical CO2, with a volume ratio of supercritical water to supercritical CO2 of 7:3. The injection pressure was set at 25 MPa, and the injection flow rate at 1.0 m³ / min. 3 / h, CO2 is used to promote the water-gas reaction and water-gas shift reaction (C(s)+H2O(sc)=CO(g)+H2(g) ΔH=+131.3kJ / mol (endothermic reaction), CO(g)+H2O(sc)=CO2(g)+H2(g) ΔH= -41.2kJ / mol (endothermic reaction)), so as to improve the purity of H2 after purification in the production well and reduce the CO concentration.

[0027] Furthermore, in step S6 of the above method, the negative pressure is adjusted to -0.05~0.03MPa and the extraction flow rate is 25m³. 3 / min; when the production well extraction rate is less than 18m 3 When the H2 concentration is less than 10% and the carbon conversion rate is greater than 85% as determined by core sampling analysis, the final procedure is initiated. Finally, the experimental data, including carbon conversion rate, unit H2 energy consumption, and process wastewater reuse rate, are statistically analyzed to confirm that the entire process is efficient, safe, and environmentally friendly.

[0028] This invention achieves the transformation of mass transfer channels in deep, low-permeability coal seams by constructing a multi-well network (supercritical fluid wells, production wells, injection and detonation wells, and feather-shaped branch horizontal wells). It combines precise oxygen release catalysis with triggered detonation agent foam, enhanced reaction by supercritical CO2 or supercritical water injection, and microwave radiation to regulate reaction temperature and trigger-induced detonation agent foam rupture. Furthermore, it achieves efficient conversion of coal seam carbon resources and high-purity H2 production by real-time monitoring of temperature, pressure, gas composition, and catalyst activity in the reaction zone, ultimately realizing safe, low-carbon, and efficient in-situ mining of deep coal seams.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) This invention innovatively combines feather-shaped branching with multi-row horizontal injection and detonation well network design, which not only achieves the purpose of expanding the contact area between coal seams and constructing three-dimensional channels, but also combines the purpose of increasing the permeability of supercritical CO2 injection into coal seams. This not only breaks through the bottleneck of mass transfer in deep, low-permeability coal seams, but also lays the foundation for the uniform diffusion of gasifying agent and full contact between coal and gas in in-situ gasification reaction, solving the problem of "injection not going in and transmission not going far" in deep coal seams.

[0030] 2) This invention combines a trigger-type detonating agent foam composed of oxygen, surfactant and catalyst with directional heating by an acoustic microwave generator. It not only further monitors the changes in O2 concentration in the reaction zone in real time, but also reasonably controls the pyrolysis reaction temperature within the optimal range of water-gas reaction. Furthermore, it enhances carbon conversion with the help of catalysts, thereby achieving safe and controllable in-situ gasification of deep coal seams and achieving the goal of high-efficiency quality improvement.

[0031] 3) This invention addresses the high carbon content of anthracite by introducing supercritical water injection to drive the water-gas hydrogen production reaction, achieving the initial conversion of carbon into hydrogen. Subsequently, a mixture of supercritical water and supercritical CO2 is introduced to further deepen the water-gas shift reaction to reduce CO content, thereby achieving efficient conversion of anthracite carbon resources and obtaining high-purity H2. This further improves the purity of H2 purified from the syngas production well, solving the problem of "low H2 purity and difficulty in removing impurities" in the traditional gasification process, and meeting the high-purity H2 requirements of coal chemical industry, fuel cells, and other applications.

[0032] 4) This invention also incorporates pre-installed thermocouples, gas sensors, and gas monitoring units to collect real-time temperature and pressure changes in the reaction zone and transmit changes in syngas concentrations such as O2, CO, and H2 to the ground system in real time. This dynamically monitors the in-situ gasification reaction status of the deep coal seam, ensuring a stable and efficient reaction. Furthermore, in the final stage, a nitrogen purging system is used to purge the wellbore and pipelines to eliminate the risk of explosion and leakage, achieving zero coal gangue discharge throughout the entire experiment. This not only reduces the development cost of deep coal seams but also aligns with the goal of clean coal utilization. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the well network layout in Embodiment 1 of the present invention.

[0034] Figure 2 This is a schematic diagram of the well network layout in Embodiment 2 of the present invention.

[0035] Figure 3 This is a schematic diagram of the well network layout in Embodiment 1 of the present invention.

[0036] Figure 4 This is a schematic diagram of the main body of the invention, which describes the promotion of preheating and fracturing of deep coal seams under the action of acoustic microwave-assisted supercritical CO2.

[0037] Figure 5 This is a schematic diagram of the particle structure of the trigger-type detonator in this invention.

[0038] Figure 6 This is a schematic diagram of the explosion process of the trigger-type detonator particles under microwave irradiation in this invention.

[0039] Figure 7 This is a schematic diagram illustrating the enhanced blasting effect of microwave-triggered detonating agent in deep coal seams according to the present invention.

[0040] In the diagram: 1. Supercritical fluid well; 2. Injection and detonation well; 3. Feather-shaped branch horizontal well; 4. Production well; 5. Roof; 6. Coal seam; 7. Floor; 8. Acoustic-microwave co-generator; 8-1. Electrochemical sensor; 8-2. Microwave; 8-3. Microwave generator; 9. First valve; 10. Flow meter; 11. High-pressure pump; 12. Storage tank; 13. Supercritical fluid storage tank; 14. Second valve; 15. Injection high-pressure pump; 16. Supercritical water generator; 17. Supercritical CO2 generator; 18. Injection and detonation agent high-pressure pump; 19. Surface control center; 20. Injection and detonation agent control system; 21. Injection and detonation agent reaction. 21. Preparation tank; 22. In-vessel stirring device; 23. Detonating agent foam transport control center; 24. Detonating agent mixing tank; 25. Foaming agent storage tank; 26. First transfer pump; 27. Second transfer pump; 28. Oxygen tank; 29. ​​Catalyst storage tank; 30. Nitrogen purging system; 31. Dry nitrogen storage tank; 32. Pressure and gas composition monitoring table; 33. Ground extraction equipment; 34. Supercritical CO2 particles; 35. Oxygen particle molecules; 36. Porous catalyst particles; 37. Green biodegradable outer layer; 38. Microwave-sensitive shell; 39. Adsorption sites; 40. Detonating agent cracks; 41. Metal active sites. Detailed Implementation

[0041] like Figures 1 to 7As shown, this invention provides a multi-well layout method for in-situ gasification mining of deep coal seams based on trigger-activated detonating agent oxygen release catalysis. It constructs a full-coverage channel through feather-shaped branched horizontal wells (3) and a multi-row network of injection and monitoring wells (injection and detonation wells 2). This method combines supercritical CO2 injection to enhance coal seam permeability and eliminate mass transfer blind zones, with microwave-assisted induced trigger-activated detonating agent precisely controlling the release of oxygen and catalyst to achieve uniform coal seam heating and catalytic gasification. Furthermore, the synergistic effect of supercritical water and supercritical CO2 deepens the water-gas shift reaction, significantly improving carbon conversion rate and hydrogen purity, thus achieving efficient, safe, and low-carbon in-situ gasification mining of deep, low-permeability coal seams.

[0042] The method of the present invention specifically includes the following steps: S1. Well network layout and core equipment pre-installation The well network layout includes: supercritical fluid wells 1 and production wells 4 arranged on the surface, with the bottoms of supercritical fluid wells 1 and production wells 4 extending through the roof 5 and into the coal seam 6; a double row of injection and detonation wells 2 arranged on the surface between supercritical fluid wells 1 and production wells 4, with the bottom of one row of injection and detonation wells 2 extending through the roof 5 and into the coal seam 6, and the bottom of the other row of injection and detonation wells 2 extending through the roof 5 and the coal seam 6 to the top of the floor 7; each row of injection and detonation wells 2 includes multiple evenly distributed and spaced injection and detonation wells 2, and the arrangement of injection and detonation wells 2 in each row... The spacing between the injection and detonation wells is 100-150m. Each injection and detonation well 2 is equipped with an acoustic-microwave co-generator 8 at its bottom. A feather-shaped branch horizontal well 3 is located in the middle between the two rows of injection and detonation wells 2. The feather-shaped branch horizontal well 3 is located in the coal seam 6. The two ends of the feather-shaped branch horizontal well 3 are connected to the supercritical fluid well 1 and the production well 4, respectively. The feather-shaped branch horizontal well 3 includes a main well. Inclined branch wells are evenly distributed on both sides of the main well, extending towards the production well 4 and gradually away from the main well. The injection and detonation well 2 is located at the angle between each inclined branch well and the main well.

[0043] After drilling is completed, the deviation of the horizontal section trajectory is checked to be less than 0.5m to ensure that the entire section is located within the coal seam and there is no penetration of the roof and floor. Next, a sealing test is carried out on all well casings. The well casing is pressurized to 20~25MPa (20, 23, 25MPa, etc. can be selected in specific implementation) and the pressure is stabilized so that the pressure drop is less than 0.5MPa to be within the qualified range, so as to avoid leakage of the injected fluid in the future.

[0044] The core equipment includes: an acoustic-microwave co-generator 8, a first valve 9, a flow meter 10, a high-pressure pump 11, a storage tank 12, a supercritical fluid storage tank 13, a second valve 14, an injection high-pressure pump 15, a supercritical water generator 16, a supercritical CO2 generator 17, an injection detonator high-pressure pump 18, a ground control center 19, an injection detonator control system 20, an injection detonator reaction preparation tank 21, an in-vessel stirring device 22, an injection detonator foam transport control center 23, an injection detonator mixing tank 24, a foaming agent storage tank 25, a first delivery pump 26, a second delivery pump 27, an oxygen tank 28, a catalyst storage tank 29, a nitrogen purging system 30, a dry nitrogen storage tank 31, a pressure and gas composition monitoring table 32, and a ground extraction equipment 33.

[0045] The supercritical CO2 generator 17 and supercritical water generator 16 are both connected to the injection high-pressure pump 15. The injection high-pressure pump 15 is connected to the supercritical fluid storage tank 13, which is connected to the storage tank 12. The storage tank 12 is connected to the high-pressure pump 11, which is connected to the supercritical fluid well 1. A second valve 14 is installed between the injection high-pressure pump 15 and the supercritical fluid storage tank 13, and a first valve 9 and a flow meter 10 are installed between the high-pressure pump 11 and the supercritical fluid well 1. The ground control center 19 is connected to the detonating agent high-pressure pump 18, which is connected to the detonation well 2. An acoustic-microwave co-generator 8 is installed at the bottom of each detonation well 2. The acoustic-microwave co-generator 8 mainly consists of a microwave generating device. It consists of 8-3 and electrochemical sensor 8-1; pressure and gas composition monitoring table 32 and ground extraction equipment 33 are connected to production well 4; oxygen tank 28 is connected to second transfer pump 27, catalyst storage tank 29 is connected to first transfer pump 26, first transfer pump 26, second transfer pump 27 and foaming agent storage tank 25 are all connected to detonating agent mixing tank 24, detonating agent mixing tank 24 is connected to detonating agent reaction preparation tank 21, detonating agent reaction preparation tank 21 is connected to detonating agent high pressure pump 18, detonating agent reaction preparation tank 21 is equipped with in-vessel stirring device 22, detonating agent reaction preparation tank 21 is equipped with detonating agent control system 20 and detonating agent foam movement control center 23; nitrogen purging system 30 is connected to dry nitrogen storage tank 31.

[0046] S2. Supercritical CO2 Coal Seam Permeability Enhancement Pretreatment Connect the supercritical CO2 generator 17 and the injection high-pressure pump 15 at the wellhead of supercritical fluid well 1. Adjust the outlet parameters of the supercritical CO2 generator 17 to 35~45℃ (35, 40, 45℃, etc. can be selected in specific implementations) and 18~22MPa (18, 20, 22MPa, etc. can be selected in specific implementations). Set the injection flow rate of the injection high-pressure pump 15 to 8m³ / min. 3 / h, supercritical CO2 is injected into the deep coal seam through supercritical fluid well 1; the acoustic-microwave co-generator 8 at the bottom of injection well 2 is turned on, and the microwave power of the acoustic-microwave co-generator 8 is adjusted to 600~1000W (600, 800, 1000W, etc. can be selected in specific implementations) and the frequency is 40~50KHz (40, 45, 50KHz, etc. can be selected in specific implementations) to radiate energy into the deep coal seam to heat and raise the temperature of supercritical CO2 to 300℃~400℃ (300, 250, 400℃, etc. can be selected in specific implementations); the injection of supercritical CO2 is stopped after 120h, and the well is shut down for 48h, thereby completing the pretreatment of coal seam permeability enhancement.

[0047] By monitoring the changes in parameters such as permeability, fracture development, and resistivity of injection well 2, the pressure is controlled to be stable at 10.8~11.2MPa (10.8, 11.0, 11.2MPa, etc. can be selected during specific implementation) to ensure that there is no risk of crossflow to production well 4.

[0048] In this step, the pretreatment of coal seam permeability enhancement with supercritical CO2 meets two criteria: First, the permeability of the two injection wells 2 near the supercritical fluid well 1 in the double-row injection well 2 is significantly improved, thus proving that the coal seam fractures are effectively enlarged; second, the pressure of the two injection wells 2 near the production well 4 in the double-row injection well 2 is controlled within a stable range without sudden rise, so as to eliminate the risk of crossflow to the production well 4; injection is stopped and the wells are shut down to allow CO2 to be fully adsorbed into the coal matrix, reserving a carbon source for the subsequent Boudouard reaction; after the wells are shut down, the drill string of injection well 2 is cored to observe whether the coal seam fracture density increases and whether there are any closed dead ends, so as to confirm that the permeability enhancement meets the criteria.

[0049] S3. Trigger-activated detonating agent foam preparation and segmented injection Start the detonating agent reaction preparation tank 21 at the wellhead of detonation well 2 to prepare trigger-activated detonating agent foam; connect the high-pressure pump 18 of the detonating agent to the injection pipeline of detonation well 2, and first inject clean water into detonation well 2 to check the seal. Specifically, inject clean water into detonation well 2, pressurize it to 15~18MPa (15, 16, 18MPa, etc. can be selected in specific implementation), stabilize the pressure for a period of time, so that the pressure drop is <0.3MPa, confirming that there is no leakage; after confirming that there is no leakage, switch to injecting trigger-activated detonating agent foam, inject trigger-activated detonating agent foam into detonation well 2, and inject it at an injection pressure of 18MPa and a flow rate of 0.5m³. 3 / h; After injection, let stand for 12 hours to allow the trigger-activated detonator foam to be evenly distributed in the permeability-enhancing fractures. By monitoring the wellbore pressure to stabilize at 17~18MPa without any abnormal drop, the trigger-activated detonator foam injection is complete.

[0050] S4. Acoustic-microwave synergistic triggering and thermal initiation of reaction. Turn on the acoustic-microwave co-generator 8 at the bottom of the injection well 2, adjust the microwave power of the acoustic-microwave co-generator 8 to 600W and the frequency to 40KHz, and radiate energy into the deep coal seam to heat the foam of the trigger-type injection agent; when the temperature of the injection well 2 is stable at 600~650℃ (600, 630, 650℃, etc. can be selected in specific implementation), the CO concentration is ≥30%, and the H2 concentration is ≥12%, turn off the acoustic-microwave co-generator 8 to complete the reaction heat start-up.

[0051] In this step, the heating-triggered detonating agent foam is controlled in two stages: the first stage is the heating period, where the heating rate is controlled at 10~15℃ / h (10, 13, 15℃ / h, etc. can be selected in specific implementations) to avoid concentrated bursting of the triggered detonating agent foam; when the temperature reaches 300~350℃ (300, 330, 350℃, etc. can be selected in specific implementations), the heat preservation is paused for 2 hours to allow the heat to spread evenly; the second stage is the reaction initiation period, where the temperature is continued to rise to 600~650℃ (600, 630, 650℃, etc. can be selected in specific implementations).

[0052] During the heating process of injection well 2, the O2 concentration of injection well 2 is monitored and controlled within the range of 5% to 8%. If the O2 concentration exceeds 8%, the microwave power of the acoustic microwave co-generator 8 is immediately reduced and the nitrogen purging system 30 at the wellhead of injection well 2 is turned on until the O2 concentration drops back to 5% to 8%.

[0053] S5. Supercritical water main gasification and deep upgrading of mixed fluids Switch the injection medium in supercritical fluid well 1, connect the supercritical water generator 16 and the injection high-pressure pump 15, adjust the outlet parameters of the supercritical water generator 16 to 400~600℃ (400, 500, 600℃, etc. can be selected in specific implementations) and 22~25MPa (22, 23, 25MPa, etc. can be selected in specific implementations), and set the injection flow rate of the injection high-pressure pump 15 to 1.2m. 3 Supercritical water is injected into the deep coal seam through supercritical fluid well 1 at a rate of / h, maintaining a water-to-coal ratio (S / C) of 2.5~3.3 (2.5, 2.8, 3.3, etc. can be selected for specific implementation); simultaneously, trigger-type detonating agent foam is injected through detonation injection well 2 at a flow rate of 0.2~0.25m³. 3 / h (0.2 or 0.25m can be selected for specific implementation) 3 / h, etc., to enhance the gasification reaction.

[0054] In this step, the gasification reaction stage is divided into the initial basic gas production period and the later deep upgrading period: During the basic gas production period, the syngas composition is monitored by the pressure and gas composition monitoring table 32 at the wellhead of production well 4. When the volume percentage of H2 is higher than 60% and the volume percentage of CO is lower than 20%, the deep quality improvement period begins.

[0055] During the deep quality improvement period, the injection medium in supercritical fluid well 1 was adjusted to a mixture of supercritical water and supercritical CO2, with a volume ratio of supercritical water to supercritical CO2 of 7:3. The injection pressure was set at 25 MPa, and the injection flow rate at 1.0 m³ / min. 3 / h, CO2 is used to promote water-gas reaction and water-gas shift reaction, so as to improve the purity of H2 after purification in production well 4 and reduce the CO concentration.

[0056] S6. Syngas Extraction and System Safety Closure Connect the surface extraction equipment 33 at the wellhead of production well 4, adjust the negative pressure to -0.05~0.03MPa, and the extraction flow rate to 25m³ / h. 3 / min, extracting syngas from gasification, and then purifying the extracted syngas through desulfurization and decarbonization treatment before transporting it to the syngas storage tank; when the extraction rate of production well 4 is less than 18m³ / min. 3 When the H2 concentration is less than 10% and the carbon conversion rate detected by core analysis is greater than 85%, the closing procedure is initiated. The negative pressure of the surface extraction equipment 33 is gradually reduced to -0.02MPa. The supercritical water generator 16, supercritical CO2 generator 17, and injection high-pressure pump 15 are shut down. The nitrogen purging system 30 is turned on to purge all wellbores and surface pipelines. The residual CO concentration is monitored by the CO sensor. When the residual CO concentration is <0.1%, all equipment is stopped, and the in-situ gasification mining of deep coal seams is completed.

[0057] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore merely examples and should not be used to limit the scope of protection of the present invention. It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning understood by those skilled in the art to which this invention pertains. Example 1

[0058] A deep anthracite coal seam with a burial depth of 1050m and a thickness of 30m was selected, meeting the experimental conditions for "in-situ gasification of deep coal seams". This is suitable for the multi-well arrangement of deep coal seam group in-situ gasification mining based on trigger-type detonator oxygen release catalysis as described in this invention.

[0059] like Figure 1 , Figures 3 to 7 As shown, the specific mining method includes the following steps: S1. Well network layout and core equipment pre-installation A well network is established, comprising a supercritical fluid well 1 and a production well 4 located on the surface, a double-row injection-explosion well 2 located between the supercritical fluid well 1 and the production well 4 on the surface, and a feather-shaped branch horizontal well 3 located in the middle of the double-row injection-explosion well 2. Each injection-explosion well 2 is equipped with an acoustic-microwave co-generator 8 at its bottom; the two ends of the feather-shaped branch horizontal well 3 are connected to the bottom of the supercritical fluid well 1 and the bottom of the production well 4, respectively, with a distance of 1m from the bottom plate 7 and a distance of 5m from the top plate 5.

[0060] S2. Supercritical CO2 Coal Seam Permeability Enhancement Pretreatment ① Connect the supercritical CO2 generator 17 (model KCO2-8000-M) and the injection high-pressure pump 15 to the wellhead of supercritical fluid well 1. Adjust the outlet parameters of the supercritical CO2 generator 17 to 45℃ and 22MPa, and set the flow rate of the injection high-pressure pump 15 to 8m³ / min. 3 / h, supercritical CO2 liquid is injected into the deep coal seam through supercritical fluid well 1. At the same time, the acoustic-microwave co-generator 8 at the bottom of injection well 2 is turned on, and the microwave power is set to 600W and the frequency to 40KHz, radiating energy into the deep coal seam to heat and increase the supercritical CO2 temperature to 300℃.

[0061] ② Monitor the permeability changes of injection well 2 to verify the fracture filling effect, and control the pressure to stabilize at 10.8~11.2MPa to ensure no risk of crossflow to production well 4.

[0062] ③ After continuous injection for 120 hours, stop and allow the well to simmer for 48 hours to allow CO2 to be fully adsorbed into the coal matrix. Then, turn off the acoustic-microwave co-generator 8 at the bottom of injection-explosion well 2. Core sampling of injection-explosion well 2 shows that the coal seam fracture density has increased significantly and there are no dead ends, thus completing the permeability enhancement.

[0063] S3. Trigger-activated detonating agent foam preparation and segmented injection ① Start the detonating agent reaction preparation tank 21 at the wellhead of detonation well 2 to prepare trigger-type detonating agent foam. The trigger-type detonating agent foam is mainly prepared from the following raw materials in parts by mass: 0.8-1.2 parts of fluorocarbon surfactant, 15-18 parts of oxidant, 0.5-0.8 parts of CuO copper-based catalyst, and 79-82.7 parts of deionized water solvent. The foam meter test showed a foaming ratio of 150 times, a half-life of ≥30 min, and a dispersion uniformity of trigger-type detonating agent foam >95%.

[0064] ② Connect the high-pressure pump 18 for the detonating agent to the injection pipeline of the detonation well 2. First, inject clean water to pressurize it to 18MPa and stabilize the pressure for a period of time until the pressure drop is <0.3MPa. After confirming there is no leakage, switch to the trigger-type foam detonating agent injection mode, setting the injection pressure to 18MPa and the flow rate to 0.5m³ / h. 3 / h, during the injection process, the Cu content in injection well 2 is monitored. 2+The concentration is adjusted to ensure that the foam of the trigger-activated detonator can be evenly diffused within the coal seam.

[0065] ③ After injection, let it stand for 12 hours. By monitoring, the pressure in wellbore 2 of the injection and detonation well stabilized at 17~18MPa with no abnormal drop, and the distribution of the injection and detonation agent was completed.

[0066] S4. Acoustic-microwave synergistic triggering and thermal initiation of reaction. ① Turn on the acoustic-microwave co-generator 8 at the bottom of each injection well 2, set the microwave power to 600W and the frequency to 40KHz, and radiate energy to the coal seam to heat the foam of the injection trigger-type injection detonator.

[0067] ② Control the heating rate of injection well 2 at 10~15℃ / h to avoid concentrated foam rupture. When the temperature reaches 120℃, maintain the temperature for 2 hours, and then continue to heat up to 600~650℃; during this period, monitor the O2 concentration through the sensor and control it at 5%~8%. If the O2 concentration exceeds 8%, immediately start the nitrogen purging system 30 at the wellhead of injection well 2.

[0068] ③ When the temperature of injection well 2 is stable within the range of 600~650℃, and the CO concentration is ≥30% and the H2 concentration is ≥12%, turn off the acoustic microwave co-generator 8 to complete the reaction heat start-up.

[0069] S5. Supercritical water main gasification and deep upgrading of mixed fluids ① Switch the injection medium of supercritical fluid well 1, start the supercritical water generator 16 (model SCW-1200-M) and injection high-pressure pump 15, adjust the outlet parameters of supercritical water generator 16 to 450℃ and 22MPa, and set the injection flow rate of injection high-pressure pump 15 to 1.2m³ / min. 3 / h, supercritical water is injected into the deep coal seam through supercritical fluid well 1 to maintain a water-to-coal ratio (S / C) of 2.8; simultaneously, it is injected through detonation well 2 and detonating agent high-pressure pump 18 at a rate of 0.2m 3 / h flow rate replenishment of trigger-activated detonator foam, thereby increasing the concentration of trigger-activated detonator foam to enhance the gasification reaction.

[0070] ② Syngas composition was monitored using the pressure and gas composition monitoring table 32 at the wellhead of production well 4. On day 16, the day the main gasification was started, the H2 volume percentage exceeded 40% and the CO volume percentage exceeded 20%. On day 20, the H2 volume percentage increased to over 70% and the CO volume percentage decreased to below 10%. On day 21, the deep quality improvement stage began. The fluid in supercritical fluid well 1 was adjusted to a mixture of supercritical water and supercritical CO2, with a volume ratio of 7:3. The injection pressure was set at 25 MPa and the injection flow rate at 1.0 m³ / s. 3 / h, deepen the water-gas conversion reaction, so that the purity of H2 after purification in production well 4 is ≥92% and CO≤3%.

[0071] S6. Syngas Extraction and System Safety Closure ① The surface extraction equipment 33 connected to the wellhead of production well 4 is set to a negative pressure of -0.05~0.03MPa and an extraction flow rate of 25m³ / h. 3 The extracted syngas is desulfurized and decarbonized and then transported to the syngas storage tank at a rate of / min.

[0072] ② When the extraction rate of production well 4 is less than 18m 3 When the H2 concentration is less than 10% and the carbon conversion rate is greater than 85% as determined by core sampling analysis, the finalization procedure is initiated.

[0073] ③ Gradually reduce the negative pressure of the surface extraction equipment 33 to -0.02MPa, shut down the supercritical water generator 16, the supercritical CO2 generator 17, and the injection high-pressure pump 15, start the nitrogen purging system 30 to purge all wells and surface pipelines for 24 hours, and after monitoring the residual CO concentration to <0.1%, stop all equipment to complete the in-situ gasification mining of deep coal seams. Example 2

[0074] A deep anthracite coal seam with a burial depth of 1250m and a thickness of 20m was selected. This method is adapted to the in-situ gasification mining of deep coal seam groups using a multi-well layout based on trigger-activated oxygen release catalysis, as described in this invention.

[0075] like Figure 2 , Figures 4 to 7 As shown, the specific mining method includes the following steps: S1. Well network layout and core equipment pre-installation Two sets of well networks as described in Example 1 are arranged, with a row of injection and explosion wells 2 arranged between the two sets of well networks, totaling two supercritical fluid wells 1, two production wells 4, two feather-shaped branch horizontal wells 3, and five rows of injection and explosion wells 2.

[0076] S2. Supercritical CO2 Coal Seam Permeability Enhancement Pretreatment ① Connect the supercritical CO2 generator (model 17, KCO2-8000-M) and the injection high-pressure pump 15 to the wellhead of supercritical fluid well 1. Adjust the outlet parameters of the supercritical CO2 generator 17 to 45℃ and 25MPa, and set the flow rate of the injection high-pressure pump 15 to 8m³ / min. 3 / h, supercritical CO2 liquid is injected into the deep coal seam through supercritical fluid well 1 to increase permeability by utilizing the replacement and adsorption characteristics of supercritical CO2, while pre-extracting some gas to reduce the risk of gas explosion in the early stage of gasification; at the same time, the acoustic microwave co-generator 8 at the bottom of the injection well 2 is turned on, the microwave power is set to 1000W and the frequency is 50KHz, and energy is radiated into the deep coal seam to heat and increase the supercritical CO2 temperature to 300℃.

[0077] ② Monitor the permeability changes of injection well 2 to verify the fracture filling effect, and control the pressure to stabilize at 10.8~11.2MPa to ensure no risk of crossflow to production well 4.

[0078] ③ After continuous injection for 120 hours, stop and allow the well to simmer for 48 hours to allow CO2 to be fully adsorbed into the coal matrix. Then, turn off the acoustic-microwave co-generator 8 at the bottom of injection-explosion well 2. Core sampling of injection-explosion well 2 shows that the coal seam fracture density has increased significantly and there are no dead ends, thus completing the permeability enhancement.

[0079] S3. Trigger-activated detonating agent foam preparation and segmented injection ① Start the detonating agent reaction preparation tank 21 at the wellhead of detonation well 2 to prepare trigger-type detonating agent foam. The trigger-type detonating agent foam is mainly prepared from the following raw materials in parts by mass: 1.0-1.5 parts of fluorocarbon surfactant, 18-22 parts of oxidant, 0.8-1.2 parts of copper-based-palladium composite catalyst, and 75.3-80.2 parts of deionized water solvent; extend the half-life of the trigger-type detonating agent foam to 120 min to enhance the gas desorption promotion effect.

[0080] ② Connect the high-pressure pump 18 for the detonating agent to the injection pipeline of the detonation well 2. First, inject clean water and pressurize it to 18MPa, then stabilize the pressure for 30 minutes until the pressure drop is <0.3MPa. After confirming there is no leakage, switch to the trigger-type foam detonating agent injection mode, setting the injection pressure to 18MPa and the flow rate to 0.5m³ / h. 3 / h, during the injection process, the concentration of copper-based-palladium composite catalyst is monitored to ensure that the foam of the trigger-type injection detonator can be uniformly diffused within the coal seam.

[0081] ③ After injection, let it stand for 12 hours. By monitoring, the pressure in wellbore 2 of the injection and detonation well stabilized at 17~18MPa with no abnormal drop, and the distribution of the injection and detonation agent was completed.

[0082] S4. Acoustic-microwave synergistic triggering and thermal initiation of reaction. ① Turn on the acoustic-microwave co-generator 8 at the bottom of each injection well 2, set the microwave power to 800W and the frequency to 50KHz, and radiate energy to the coal seam to heat the foam of the injection trigger-type injection detonator.

[0083] ② Control the heating rate of injection well 2 at 10~15℃ / h to avoid concentrated foam rupture. When the temperature reaches 120℃, maintain the temperature for 2 hours, and then continue to heat up to 600~650℃; during this period, monitor the O2 concentration through the sensor and control it at 5%~8%. If the O2 concentration exceeds 8%, immediately start the nitrogen purging system 30 at the wellhead of injection well 2.

[0084] ③ When the temperature of injection well 2 is stable within the range of 600~650℃, and the CO concentration is ≥30% and the H2 concentration is ≥12%, turn off the acoustic microwave co-generator 8 to complete the reaction heat start-up.

[0085] S5. Supercritical water main gasification and deep upgrading of mixed fluids ① Switch the injection medium of supercritical fluid well 1, start the supercritical water generator 16 (model SCW-1200-M) and injection high-pressure pump 15, adjust the outlet parameters of supercritical water generator 16 to 450℃ and 24MPa, and set the injection flow rate of injection high-pressure pump 15 to 1.2m³ / min. 3 / h, supercritical water is injected into the deep coal seam through supercritical fluid well 1 to maintain a water-to-coal ratio (S / C) of 2.7; simultaneously, it is injected through detonation well 2 and detonation agent high-pressure pump 18 at a rate of 0.25m 3 / h flow rate replenishment of trigger-activated detonator foam, thereby increasing the concentration of trigger-activated detonator foam to enhance the gasification reaction.

[0086] ② Syngas composition was monitored using the pressure and gas composition monitoring table 32 at the wellhead of production well 4. On day 13, the day the main gasification was started, the H2 volume ratio exceeded 50% and the CO volume ratio exceeded 20%. On day 18, the H2 volume ratio increased to over 70% and the CO volume ratio decreased to below 10%. On day 19, the deep quality improvement stage began. The fluid in supercritical fluid well 1 was adjusted to a mixture of supercritical water and supercritical CO2, with a volume ratio of supercritical water to supercritical CO2 of 7:3. The injection pressure was set at 25 MPa and the injection flow rate at 1.0 m³ / s. 3 / h, deepen the water-gas conversion reaction, so that the purity of H2 after purification in production well 4 is ≥95% and CO≤2%.

[0087] S6. Syngas Extraction and System Safety Closure ① The surface extraction equipment 33 connected to the wellhead of production well 4 is set to a negative pressure of -0.05~0.03MPa and an extraction flow rate of 25m³ / h. 3 The extracted syngas is desulfurized and decarbonized and then transported to the syngas storage tank at a rate of / min.

[0088] ② When the extraction rate of production well 4 is less than 18m 3 When the H2 concentration is less than 10% and the carbon conversion rate is greater than 85% as determined by core sampling analysis, the finalization procedure is initiated.

[0089] ③ Gradually reduce the negative pressure of the surface extraction equipment 33 to -0.02MPa, shut down the supercritical water generator 16, the supercritical CO2 generator 17, and the injection high-pressure pump 15, start the nitrogen purging system 30 to purge all wells and surface pipelines for 24 hours, and after monitoring the residual CO concentration to <0.1%, stop all equipment to complete the in-situ gasification mining of deep coal seams.

[0090] In the accompanying drawings of the above embodiments, Figure 2 , 3This diagram illustrates the layout of a deep coal seam well network and the preheating and fracturing of the deep coal seam under the action of supercritical CO2 injection. The roof 5 and floor 7 form a sealed space to ensure the stability of coal seam 6 as the core reaction zone. In the surface system, the foaming agent storage tank 25, oxygen tank 28, and catalyst storage tank 29 send raw materials to the injection agent mixing tank 24 for premixing via the first delivery pump 26 and the second delivery pump 27. The mixture then enters the injection agent reaction preparation tank, where it is mixed by the in-tank stirring device 22 and regulated by the injection agent control system 20 to generate trigger-type injection agent foam. The injection agent foam migration control center 23 monitors its migration performance, and finally, after being pressurized by the injection agent high-pressure pump 18, it is injected into the coal seam through the injection well 2. The supercritical fluid storage tank 13 supplies materials to the supercritical water generator 16 and the supercritical CO2 generator 17. The prepared supercritical fluid is pressurized by the injection high-pressure pump 15 and injected through the supercritical fluid well 1. The fluid is injected into the coal seam to enhance permeability. The auxiliary fluid in the storage tank 12 is precisely regulated and injected through the high-pressure pump 11, the first valve 9, and the flow meter 10. The feather-shaped branch horizontal well 3 expands the contact area between the fluid, the trigger-type detonating agent foam, and the coal seam, and guides the medium. The microwave generator 8-3 generates microwaves 8-2, which are focused on the trigger-type detonating agent foam area by the acoustic microwave co-generator 8 to trigger its rupture and release of oxygen and catalyst. The electrochemical sensor 8-1 monitors the downhole temperature, pressure, gas composition, and catalyst activity in real time. The data is transmitted to the ground control center 19, which links the first valve 9, the second valve 14, the flow meter 10, and the pressure and gas composition monitoring table 32 to achieve full-process control. The reaction products are collected in the production well 4 through the feather-shaped branch horizontal well 3 and extracted by the surface extraction equipment 33. At the end of the operation, the dry nitrogen storage tank 31 is purged through the nitrogen purging system 30 to ensure the safety of the operation.

[0091] Figure 4 , 5 Sections 6 and 7 illustrate the structural diagram of the triggered detonator particles and the process of blasting enhancement in deep coal seams under microwave irradiation. The triggered detonator particles mainly consist of oxygen particles 35, porous catalyst particles 36, a green biodegradable outer layer 37, a microwave-sensitive shell 38, and adsorption sites 39. When the triggered detonator particles are exposed to microwaves 8-2 generated by the microwave generator 8-3, the microwaves 8-2 further promote the triggered detonation of the particles, causing detonator cracks 40 to appear on the surface of the particles and expand further. This releases the oxygen particles 35 and the metal active sites 41 inside the porous catalyst particles 36, which then come into contact with the deep coal seam and participate in the pyrolysis and gasification reaction process.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A multi-well arrangement method for in-situ gasification mining of deep coal seams based on trigger-activated oxygen release catalysis, characterized in that, Includes the following steps: S1. Supercritical fluid well (1) and production well (4) are arranged on the ground, and a double row of injection and detonation wells (2) are set between them. Each row of injection and detonation wells (2) includes multiple injection and detonation wells (2) evenly distributed and spaced apart. Each injection and detonation well (2) is equipped with an acoustic microwave co-generator (8) at the bottom. A feather-shaped branch horizontal well (3) is set in the middle between the double row of injection and detonation wells (2). The two ends of the feather-shaped branch horizontal well (3) are connected to the supercritical fluid well (1) and the production well (4) respectively. S2. Connect the supercritical CO2 generator (17) and the injection high-pressure pump (15) at the wellhead of the supercritical fluid well (1) to inject supercritical CO2 into the deep coal seam through the supercritical fluid well (1); turn on the acoustic microwave co-generator (8) at the bottom of the injection explosion well (2) to radiate energy into the deep coal seam by adjusting the microwave power and frequency to heat up the supercritical CO2 temperature; after the supercritical CO2 is continuously injected for a period of time, stop the injection and perform well shut-in treatment to complete the coal seam permeability enhancement pretreatment; S3. Start the detonating agent reaction preparation tank (21) at the wellhead of the detonating well (2) to prepare the trigger-type detonating agent foam. Connect the detonating agent high-pressure pump (18) to the injection pipeline of the detonating well (2). First, inject clean water into the detonating well (2) to check the sealing. After confirming that there is no leakage, switch to injecting the trigger-type detonating agent foam and inject the trigger-type detonating agent foam into the detonating well (2). After the injection is completed, let it stand to allow the trigger-type detonating agent foam to be evenly distributed in the permeability-enhancing fracture. When there is no abnormal drop in the wellbore pressure, the injection of the trigger-type detonating agent foam is completed. S4. Turn on the acoustic-microwave co-generator (8) at the bottom of the injection well (2), adjust the microwave power and frequency, and radiate energy to the deep coal seam to heat the foam of the trigger injection agent; when the temperature of the injection well (2) is stable at 600~650℃, CO concentration ≥30%, and H2 concentration ≥12%, turn off the acoustic-microwave co-generator (8) to complete the reaction heat start-up. S5. Switch the injection medium of the supercritical fluid well (1), connect the supercritical water generator (16) and the injection high-pressure pump (15), inject supercritical water into the deep coal seam through the supercritical fluid well (1) to maintain the water-coal ratio of 2.5~3.3; simultaneously inject the trigger-type injection foam through the injection explosion well (2) to improve the gasification reaction; S6. Connect the surface extraction equipment (33) at the wellhead of the production well (4), adjust the negative pressure and extraction flow rate to the set value, extract the gasified syngas, and after desulfurization and decarbonization of the extracted syngas, transport it to the syngas storage tank; start the finishing procedure, gradually reduce the negative pressure of the surface extraction equipment (33) to -0.02MPa, shut down the supercritical water generator (16), supercritical CO2 generator (17), and injection high pressure pump (15), start the nitrogen purging system (30), purge all wells and surface pipelines, monitor the residual CO concentration through the CO sensor, and when the residual CO concentration is <0.1%, stop all equipment operation to complete the in-situ gasification mining of deep coal seams.

2. The multi-well arrangement deep coal seam in-situ gasification mining method based on trigger-activated oxygen release catalysis according to claim 1, characterized in that: In step S1, after drilling is completed, the deviation of the horizontal section trajectory is checked to be <0.5m to ensure that the entire section is located within the coal seam and there is no phenomenon of penetrating the roof and floor. Next, a sealing test is carried out on all well casings. The well casing is pressurized to 20~25MPa and stabilized so that the pressure drop is <0.5MPa, which is within the qualified range, to avoid leakage of the injected fluid in the future. The spacing between multiple injection and blasting wells (2) in each row is 100-150m; The feather-shaped branch horizontal well (3) includes a main well, and inclined branch wells are evenly distributed on both sides of the main well, extending towards the production well (4) and gradually away from the main well; the injection and explosion well (2) is located at the angle between each inclined branch well and the main well.

3. The multi-well arrangement deep coal seam in-situ gasification mining method based on trigger-activated oxygen release catalysis according to claim 1, characterized in that: In step S2, adjust the outlet parameters of the supercritical CO2 generator (17) to 35~45℃ and 18~22MPa; set the injection flow rate of the injection high-pressure pump (15) to 8m³ / min. 3 / h; Adjust the microwave power of the acoustic-microwave co-generator (8) to 600-1000W and the frequency to 40-50KHz; raise the supercritical CO2 temperature to 300℃-400℃; stop the injection after 120h of continuous supercritical CO2 injection and shut down the well for 48h. By monitoring the changes in parameters such as permeability, fracture development, and resistivity of the injection well (2), the pressure is controlled to be stable at 10.8~11.2MPa to ensure no risk of crossflow to the production well (4); The pretreatment of coal seam permeability enhancement with supercritical CO2 meets two compliance conditions: First, the permeability of the two injection wells (2) near the supercritical fluid well (1) in the double-row injection well (2) is significantly improved, thus proving that the coal seam fractures are effectively enlarged; Second, the pressure of the two injection wells (2) near the production well (4) in the double-row injection well (2) is controlled within a stable range without sudden rise, so as to eliminate the risk of crossflow to the production well (4); The injection is stopped and the well is shut down to allow CO2 to be fully adsorbed into the coal matrix, so as to reserve carbon source for the subsequent Boudouard reaction; After the well is shut down, the core of the injection well (2) is taken to observe whether the coal seam fracture density increases and there are no closed dead ends, so as to confirm that the permeability enhancement meets the standard.

4. The multi-well arrangement deep coal seam in-situ gasification mining method based on trigger-activated oxygen release catalysis according to claim 1, characterized in that: In step S3, the triggered detonating agent foam is mainly prepared from fluorocarbon surfactants, oxygen, CuO copper-based catalysts and deionized water.

5. The multi-well arrangement deep coal seam in-situ gasification mining method based on trigger-activated oxygen release catalysis according to claim 1, characterized in that: In step S4, the microwave power of the acoustic-microwave co-generator (8) is adjusted to 600W and the frequency to 40KHz; The heating-triggered detonating agent foam is controlled in two stages: the first stage is the heating period, in which the heating rate is controlled at 10~15℃ / h to avoid concentrated bursting of the detonating agent foam; when the temperature reaches 300~350℃, the heat preservation is paused for 2 hours to allow the heat to spread evenly; the second stage is the reaction start-up period, in which the temperature is continued to rise to 600~650℃. During the heating process of the injection well (2), monitor the O2 concentration of the injection well (2) and control the O2 concentration within the range of 5% to 8%. If the O2 concentration exceeds 8%, immediately reduce the microwave power of the acoustic microwave co-generator (8) and turn on the nitrogen purging system (30) at the wellhead of the injection well (2) until the O2 concentration drops back to 5% to 8%.

6. The multi-well arrangement deep coal seam in-situ gasification mining method based on trigger-activated oxygen release catalysis according to claim 1, characterized in that: In step S5, adjust the outlet parameters of the supercritical water generator (16) to 400~600℃ and 22~25MPa; set the injection flow rate of the injection high-pressure pump (15) to 1.2m. 3 / h; The injection flow rate for the supplementary trigger-type foam detonator is 0.2~0.25m³ / h. 3 / h; The gasification reaction stage is divided into the initial basic gas production period and the later deep quality improvement period: During the basic gas production period, the syngas composition is monitored by the pressure and gas composition monitoring table (32) at the wellhead of the production well (4). When the volume ratio of H2 is higher than 60% and the volume ratio of CO is lower than 20%, the deep quality improvement period begins. During the deep quality improvement period, the injection medium of the supercritical fluid well (1) was adjusted to be a mixture of supercritical water and supercritical CO2, with a volume ratio of supercritical water to supercritical CO2 of 7:

3. The injection pressure was set to 25 MPa and the injection flow rate to 1.0 m³ / min. 3 / h, CO2 is used to promote water gas reaction and water gas conversion reaction, so as to improve the purity of H2 after purification in production well (4) and reduce CO concentration.

7. The multi-well arrangement deep coal seam in-situ gasification mining method based on trigger-activated oxygen release catalysis according to claim 1, characterized in that: In step S6, adjust the negative pressure to -0.05~0.03MPa and the extraction flow rate to 25m³ / h. 3 / min; when the production well (4) pumping rate is less than 18m 3 When the H2 concentration is less than 10% and the carbon conversion rate detected by core sampling is greater than 85%, the closing procedure is initiated.

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