Coal underground combustion gasification and carbon dioxide storage mining treatment method

Abstract

The invention discloses a coal underground combustion gasification and carbon dioxide sequestration mining treatment method. The method comprises the steps that S1, gas injection fracturing is conducted, specifically, fracturing gas is introduced through a gas outlet well to enable a coal seam corresponding to a gasification to-be-mined area to form a fracturing seam net; s2, combustion gasification: taking the bottom end of a gas inlet shaft of the furnace to mountain gas and the bottom end as a mining direction, discharging gas from the furnace, and discharging synthesis gas; and S3, sealing and closing the well: injecting carbon dioxide serving as displacement gas into the space to be sealed through the gas inlet well, collecting mixed gas through the gas outlet well, and then injecting high-pressure CO2 gas into the space to be sealed for sealing treatment. According to gas injection fracturing of a single furnace, a horizontal fracturing gas injection channel is adopted for carrying out gas injection fracturing treatment on the gasification to-be-mined area of the furnace located above to form a fracturing crack net, the upper furnace well and the lower furnace well can be jointly subjected to difference node follow-up according to the flow process and the difference of one flow node, and the sealing difficulty of the well and a combustion space area is reduced; and the mining efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of underground coal gasification mining, and in particular to an underground coal combustion gasification and carbon dioxide storage mining and processing method. Background Art

[0002] Underground coal gasification is the process of directly converting underground coal resources into coal gas. Underground coal gasification can efficiently convert underground coal resources into usable energy, improve coal mining efficiency, and reduce coal mining costs. Before the development of deep underground coal gasification, a lot of geological surveys and surveys are required to ensure the stability of the boreholes in the rock formation. Underground coal gasification also faces many challenges, such as the complexity of geological conditions, combustion control during gasification, environmental pollution problems, and technical difficulties, which all need to be further resolved. At present, underground coal gasification mining often adopts the method of drilling a mine from the ground, and then burning and gasifying at the bottom of the mine to produce synthesis gas. Combustion gasification will transport gasification agents to the coal combustion gasification area, and at the same time, it is necessary to collect the synthesis gas containing combustible gas. After mining, the combustion and empty area needs to be sealed and protected. The existing underground coal gasification mining process still faces many problems that need to be overcome, resulting in greater mining difficulty and low mining efficiency. Therefore, the process operation of underground coal gasification is the direction of research on the application of underground gasification technology. Summary of the invention

[0003] The purpose of the present invention is to provide a safe and efficient underground gasification mining method for underground coal combustion gasification and carbon dioxide storage mining and processing. In a single furnace, a process-based technology with three process nodes of gas injection fracturing, combustion gasification, and storage and well closure is adopted. The gas injection fracturing adopts a horizontal fracturing gas injection channel to perform gas injection fracturing treatment on the furnace gasification mining area located above to form a fracture network. The horizontal fracturing gas injection channel serves to connect the two wells, allowing the two wells to be farther apart, reducing the number of wells and the impact of the wells on the coal strata, and improving mining safety.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] A method for underground coal combustion gasification and carbon dioxide storage mining and processing, the method comprising:

[0006] S1. Gas injection fracturing: construct the gas inlet well and gas outlet well of the furnace, the bottom of the gas outlet well is horizontally extended to the bottom of the gas inlet well and is not connected, and the fracturing gas is introduced through the gas outlet well to perform gas injection fracturing on the gasification waiting area of ​​the furnace and form a fracturing network corresponding to the coal seam in the gasification waiting area. After the gas injection fracturing is completed, the bottom of the gas outlet well is horizontally extended to form a horizontal fracturing gas injection channel part and is connected to the bottom of the gas inlet well;

[0007] S2. Combustion and gasification: With the bottom of the furnace's air inlet well to the bottom of the gas outlet well as the mining direction, the gasification agent is introduced through the air inlet well to perform coal seam combustion and gasification operations on the gasification mining area of ​​the furnace, and the synthesis gas is discharged and collected through the furnace's outlet gas, and the combustible gas is separated from the synthesis gas; after the combustion and gasification of the gasification mining area of ​​the furnace is completed, a combustion empty zone is formed, and the combustion empty zone of the furnace is cooled;

[0008] S3. Sealing and closing the well: After the combustion-air gap area of ​​the furnace has been cooled down, the furnace's gas outlet well, gas outlet area and gas inlet well form a space to be sealed. Carbon dioxide is injected into the space to be sealed through the gas inlet well as a displacement gas, and the mixed gas is collected through the gas outlet well to separate the combustible gas from the mixed gas. The mixed gas is tested at the gas outlet well, and when the proportion of the displacement gas in the mixed gas reaches P%, the displacement operation is stopped. Then, the end of the space to be sealed close to the gas outlet well is blocked, and high-pressure CO2 gas is injected into the space to be sealed through the gas inlet well to seal it. Then, a cement plug is closed at one end of the space to be sealed close to the gas inlet well, and a leakage detection device is installed to monitor and alarm for leakage.

[0009] In order to better realize the present invention, the present invention includes a combined supply and processing system, which includes a synthesis gas separation system, a high-pressure carbon dioxide supply system and a gasification agent supply system. The high-pressure carbon dioxide supply system includes a CO2 gas storage tank and a high-pressure carbon dioxide control and compressor unit connected to the CO2 gas storage tank, and the high-pressure carbon dioxide control and compressor unit generates high-pressure CO2 and is used as fracturing gas for gas injection fracturing; the gasification agent supply system includes a water vapor generator, an oxygen generator, a gasification agent control station and a gas injection high-pressure pump unit, the water vapor generator is used to produce water vapor, the oxygen generator is used to produce oxygen, the gasification agent control station is respectively connected to the water vapor generator and the oxygen generator and mainly mixes water vapor and oxygen into a gasification agent and transports it to the gas injection high-pressure pump unit, the gas injection high-pressure pump unit is used to generate a high-pressure gasification agent and input it into the gasification waiting area of ​​the furnace for coal seam combustion gasification; the gas separation system is used to collect the synthesis gas generated by coal seam combustion gasification and / or the mixed gas discharged from the displacement operation and separate them to obtain combustible gas.

[0010] Preferably, the gas injection high-pressure pump group is connected to a gasification agent injection pipe at the gas outlet, the synthesis gas separation system is connected to a gas production pipe at the gas inlet, and the high-pressure carbon dioxide control and compressor group is connected to a fracturing gas injection pipe at the gas outlet; during the gas injection and fracturing stage of step S1, the fracturing gas injection pipe is connected to the gas outlet of the furnace in a sealed manner or the fracturing gas injection pipe is extended to the horizontal fracturing gas injection channel of the furnace gas outlet well and the gasification to-be-produced area above is subjected to gas injection and fracturing operations, and a gas sensor is provided at the wellhead of the furnace gas inlet well to detect whether there is gas outlet of fracturing gas;

[0011] During the combustion and gasification stage of step S2, the gas sensor of the furnace's air inlet well is removed, and the gasification agent injection pipe is tightly connected to the furnace's air inlet well, or the gasification agent injection pipe is extended into the furnace's horizontal fracturing injection channel part and advanced in the mining direction, and the gas production pipe is tightly connected to the furnace's gas outlet well. The synthesis gas produced by combustion and gasification in the furnace's gasification area enters the synthesis gas separation system through the gas production pipe and is separated to obtain combustible gas.

[0012] Preferably, the gas separation system is also connected to a user and a storage end, and the combustible gas separated by the gas separation system is transported to the user and the storage end; the gas separation system is respectively connected to a CO2 gas storage tank and a gasifier control station, and the CO2 gas separated by the gas separation system is respectively transported to a CO2 gas storage tank and a gasifier control station, and the gasifier control station also adds CO2 gas as a new gasifier in a corresponding proportion to a gasifier mainly composed of water vapor and oxygen; when displacing the gas in the space to be sealed in the sealing and closing stage of step S3, the gasifier control station only proportions CO2 gas and injects high-pressure CO2 gas through the gasifier injection pipe, and the gas production pipe is tightly connected to the gas outlet well of the furnace, and the mixed gas displaced from the space to be sealed in the furnace enters the synthesis gas separation system through the gas production pipe and is separated to obtain combustible gas.

[0013] Preferably, before gas injection fracturing in the gasification area to be mined of the furnace, a seal is first used on the bottom of the furnace's gas outlet well to perform gas injection fracturing stage. The front section of the fracturing gas injection pipe is a gas injection distribution pipe, which is placed in the aquatic fracturing gas injection channel and connected to a number of diverter nozzles. The diverter nozzles are distributed at the bottom of the gasification area to be mined of the furnace, and the diverter nozzles of the gas injection distribution pipe inject high-pressure CO2 into the coal seam inside the gasification area to be mined and form a fracture network in the coal seam.

[0014] Preferably, the air inlet well and / or air outlet well of the furnace are constructed using drilling tools, and the bottom of the air outlet well of the furnace is horizontally extended using a drilling tool equipped with a drill bit guide system; the air inlet well and air outlet well of the furnace are both reinforced and protected by casing during the working stage.

[0015] Preferably, the drilling tool equipped with a drill bit guidance system includes a drill bit and a bent screw power drill installed at the rear end of the drill bit to drive the drill bit with power, and a downhole tractor for a horizontal fracturing and gas injection channel to provide traction power for horizontal extension construction of the drill bit. The drill bit guidance system includes a drill bit guidance tool installed on the drill bit to steer or guide the drill bit.

[0016] Preferably, the cooling of the combustion zone of the furnace also includes the following detection method: a temperature sensor for monitoring the temperature of the combustion zone is provided in the air inlet shaft of the furnace, and when the temperature sensor is lowered to the ambient temperature, the idle cooling of the combustion zone of the furnace is completed.

[0017] The present invention can realize continuous follow-up operation of all furnaces according to the process technology, and the specific method is as follows:

[0018] Select a coal mining area, plan the furnaces for continuous advancement of the coal mining area, and number them in order of furnace 1, furnace 2, furnace 3, ..., furnace N. Each furnace is processed according to the three process nodes of gas injection fracturing, combustion gasification, and sealing and closing the well;

[0019] When the gas injection and fracturing stage of furnace one is in progress or completed, the gas outlet well of furnace two is followed up; when furnace one is in the process of combustion and gasification, the gasification waiting area of ​​furnace two is subjected to gas injection and fracturing through the gas outlet well of furnace two; when the combustion and gasification of furnace one is completed, the gas outlet well of furnace one is used as the gas inlet well of furnace two, and the ignition and gasification of furnace two is followed up, and at the same time, the gas outlet well of furnace three is followed up; when furnace one is cooled down and enters the sealing and well closing stage, the gas outlet channel of furnace one near one end of the gas outlet well is blocked; when the combustion and gasification of furnace two is completed, the gas outlet well of furnace two is used as the gas inlet well of furnace three, and the gas injection and fracturing of furnace three is followed up, and at the same time, the gas outlet well of furnace four is followed up, and furnace two enters the sealing and well closing stage;

[0020] According to the above method, the process technology of the three process nodes of gas injection fracturing, combustion gasification and sealing and closing of the well in the subsequent furnace is realized in sequence.

[0021] Preferably, all furnaces complete the process technology in sequence with the outlet well of the previous furnace serving as the inlet well of the next furnace; all furnaces in the coal mining area follow up continuously in a straight line or in an S-shaped manner according to the furnace sequence.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] (1) The present invention adopts a process-based technology with three process nodes, namely, gas injection fracturing, combustion gasification, and sealing and closing of the well, in a single furnace. The gas injection fracturing adopts a horizontal fracturing gas injection channel to perform gas injection fracturing treatment on the furnace gasification mining area located above to form a fracture network. The horizontal fracturing gas injection channel serves to connect the two wells, allowing the two wells to be farther apart, reducing the number of wells and the impact of the wells on the coal strata, and improving mining safety.

[0024] (2) When the furnace is undergoing gas injection and fracturing, the bottom of the furnace's gas outlet well will extend horizontally to form a horizontal fracturing gas injection channel, so that the gas outlet well is provided with a horizontal fracturing gas injection channel, which is not connected to the gas inlet well during the gas injection and fracturing stage. High-pressure CO2 is injected into the horizontal fracturing gas injection channel of the gas outlet well through distributed diversion nozzles to perform gas injection and fracturing on the corresponding furnace gasification mining area above, so that a [fracturing network] of coal seams is formed, coal stress is released in advance, and combustion gasification safety and vaporization efficiency are improved. High-pressure CO2 injection can also effectively displace coalbed methane. Since there is a horizontal fracturing gas injection channel between the furnace's gas outlet well and the gas inlet well, the gas outlet well and the gas inlet well can be arranged at a greater distance, so that the horizontal fracturing gas injection channel of the gas outlet well can bear the distributed high-pressure CO2 gas injection and fracturing of the furnace gasification mining area. The greater distance between the wells proves that the present invention can reduce drilling and promote safe and efficient mining.

[0025] (3) In the present invention, each furnace for underground gasification exploitation carries out exploitation operations step by step according to the process-based technology of gas injection fracturing, combustion gasification, and sealing and closing well treatment. The upper and lower furnaces follow up at different nodes according to the process-based technology with a difference of one process node; the outlet well of the next furnace after gas injection fracturing serves as the inlet well of the next furnace, thus forming a shared inlet and outlet directional well. Therefore, the process method of the present invention is used for continuous follow-up, which can realize the commonality of the upper and lower furnace wells, reduce the number of drilling wells and the drilling workload, and also reduce the degree of geological damage to the coal strata, and reduce the difficulty of sealing the wells and the combustion void area.

[0026] (4) When furnace 1 of the present invention is in the process of cooling down, furnace 2 is in the process of combustion and gasification, and furnace 3 is in the process of gas injection and fracturing. At this time, furnace 4 can be started to follow up, thereby forming a differential node follow-up and the front and rear furnaces are connected to the same well and continuously coordinated to advance, which reduces the construction of some wells, and thus the mining efficiency is effectively improved; the mining can be continuously followed up in a straight line, circle or S shape in the coal mining area. Taking straight line mining as an example, multiple continuous mining straight line advancement paths can be designed and planned, and multiple differential node follow-up mining methods are carried out simultaneously, which enhances the gasification efficiency and ensures the orderly succession of multiple process nodes, resulting in fast mining and production, and increasing the total mining output, thereby greatly improving the mining efficiency.

[0027] (5) The present invention has clear requirements or monitoring when each process node is completed and handed over. For example, when gas injection fracturing is completed, gas outflow from the fracture network is monitored by a gas sensor. When CO2 storage and well closure treatment is completed, leakage monitoring and alarm are performed by a leakage detection device installed at the wellhead, both of which ensure the efficiency and safety performance of follow-up mining work. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a layout structure and working principle diagram of the furnace in the gas injection fracturing process stage in Example 2;

[0029] Figure 2 for Figure 1 A schematic diagram of the structure of the combined supply and processing system;

[0030] Figure 3 It is a layout structure and working principle diagram of the furnace in the combustion and gasification process stage in Example 2;

[0031] Figure 4 The layout structure and working principle diagram of the furnace in the sealing and closing process stage in Example 2;

[0032] Figure 5 This is a schematic diagram of the principle that furnace 1 and furnace 2 share furnace 1 well in embodiment 2;

[0033] Figure 6 for Figure 1 A partial enlarged schematic diagram of .

[0034] The names corresponding to the reference numerals in the accompanying drawings are:

[0035] 1-gasification agent control station, 2-water vapor generator, 3-oxygen generator, 4-gas injection high-pressure pump group, 41-gasification agent injection pipe, 5-CO2 gas storage tank, 6-high-pressure carbon dioxide control and compressor group, 61-fracturing gas injection pipe, 7-synthesis gas separation system, 71-gas production pipe, 8-user and storage end, 9-gas injection distribution pipe, 10-casing, 11-drill bit, 12-drill bit guide tool, 13-bent screw power drill, 14-horizontal fracturing gas injection channel downhole tractor, 15-gas injection control valve, 16-diverter nozzle, 17-packer, 18-gas sensor, 19-fracturing fracture network, 20-grouting pipeline, 21-cement stone sealing block, 22-combustion cavity, 23-temperature sensor, 24-cement plug, 25-leakage detection device. DETAILED DESCRIPTION

[0036] The present invention is further described in detail below in conjunction with embodiments:

[0037] Embodiment 1

[0038] like Figure 1 to Figure 4 As shown, a method for underground coal combustion gasification and carbon dioxide storage mining and processing, the method comprising:

[0039] S1. Gas injection fracturing: The gas inlet and outlet wells of the construction furnace are connected. The bottom of the outlet well extends horizontally to the bottom of the gas inlet well and is not connected (see Figure 1 During the gas injection fracturing stage, the horizontal fracturing gas injection channel extending horizontally from the bottom of the outlet well is not connected to the bottom of the inlet well. For details, see Figure 1The connected position in the middle is indicated by a dotted line indicating that it is not connected), and fracturing gas is introduced through the gas outlet well to perform gas injection fracturing on the gasification mining area of ​​the furnace and form a fracturing network 19 (the fracturing network 19 improves the efficiency of subsequent combustion and gasification) corresponding to the coal seam in the gasification mining area; the horizontal fracturing gas injection channel extending horizontally from the bottom of the gas outlet well of the present invention can increase the distance between the gas inlet well and the gas outlet well, and can complete the gas injection and fracturing operation within a large distance between the gas inlet well and the gas outlet well, so that the number of construction wells in the entire coal mining area is greatly reduced, the impact on the coal strata is effectively reduced, and the safety performance of underground combustion and gasification is improved; at the same time, a horizontal fracturing gas injection channel is used to perform gas injection and fracturing from the bottom toward the gasification mining area of ​​the furnace, which can greatly improve the efficiency of gas injection and fracturing, and thus improve the efficiency of subsequent combustion and gasification. After the gas injection and fracturing is completed, the bottom of the gas outlet well is horizontally extended to form a horizontal fracturing gas injection channel portion and is interconnected with the bottom of the gas inlet well (after the gas injection and fracturing is completed, the horizontal fracturing gas injection channel extending horizontally from the bottom of the gas outlet well is connected to the bottom of the gas inlet well, see Figure 3 The connected positions are indicated by solid lines).

[0040] S2, Combustion gasification: The mining direction is from the bottom of the furnace inlet well to the bottom of the gas outlet well (with Figure 3 For example, the mining direction is from right to left), the gasification agent is introduced through the gas inlet well to carry out coal seam combustion gasification operation in the gasification mining area of ​​the furnace, and the gas is discharged and collected through the furnace outlet (the coal seam combustion gasification operation produces a synthesis gas containing combustible gas, which is discharged through the gas outlet well and collected at the end of the gas outlet well, and then the synthesis gas is separated and treated to finally obtain the required combustible gas), and the combustible gas is separated from the synthesis gas. After the combustion and gasification of the gasification mining area of ​​the furnace is completed, a combustion empty zone is formed, and the combustion empty zone of the furnace is cooled.

[0041] S3. Sealing and closing the well: After the combustion zone of the furnace is cooled down, the gas outlet well, combustion zone and gas inlet well of the furnace form a space to be sealed. Carbon dioxide is injected into the space to be sealed through the gas inlet well as a displacement gas, and the mixed gas is collected through the gas outlet well to separate the combustible gas from the mixed gas. The mixed gas is detected at the gas outlet well. When the displacement gas (carbon dioxide as the displacement gas) in the mixed gas reaches P%, the displacement operation is stopped. Then, one end of the space to be sealed close to the gas outlet well is blocked, and high-pressure CO2 gas is injected into the space to be sealed through the gas inlet well for sealing (coal combustion gasifies into carbon slag, which remains in the combustion zone. In order to protect the combustion zone, high-pressure CO2 gas needs to be injected for sealing and protection). Then, a cement plug is closed at one end of the space to be sealed close to the gas inlet well and a leakage detection device is installed for leakage monitoring and alarm (the leakage detection device monitors whether there is gas discharge from the underground after mining. If there is gas discharge, it means that there is leakage in the sealing and further measures need to be taken).

[0042] According to the above method, the furnace gas injection fracturing (i.e. step S1), combustion gasification (i.e. step S2), sealing and closing the well (i.e. step S3) are a process node process.

[0043] Furthermore, the present invention can realize continuous follow-up operation of all furnaces according to the process technology, and the specific method is as follows:

[0044] A coal mining area is selected, and the furnaces for continuous advancement of operations in the coal mining area are planned. The furnaces are numbered in sequence as Furnace 1, Furnace 2, Furnace 3, ..., Furnace N. Each furnace follows the standardized process of three process nodes: gas injection fracturing, combustion gasification, and sealing and well closure.

[0045] When the gas injection and fracturing stage of furnace one is in progress or completed, follow up with the construction of the gas outlet well of furnace two. During the combustion and gasification process of furnace one, gas injection and fracturing are carried out on the gasification and mining area of ​​furnace two through the gas outlet well of furnace two. When the combustion and gasification of furnace one is completed, the gas outlet well of furnace one is used as the gas inlet well of furnace two, and the ignition and gasification of furnace two are followed up, and the gas outlet well of furnace three is followed up. When furnace one is cooled down and enters the sealing and well closing stage, the gas outlet channel of furnace one close to one end of the gas outlet well is blocked (such as Figure 4 As shown, the gas outlet channel is the channel between the gas outlet well and the gas inlet well, and the channel includes a combustion and air zone, see Figure 4 , block the bottom of the outlet well of furnace one close to the outlet channel. At this time, the outlet channel is blocked at one end close to the outlet well, but the outlet well can still be used as the inlet well of the next furnace). When the combustion and gasification of furnace two is completed, the outlet well of furnace two is used as the inlet well of furnace three, and the gas injection and fracturing of furnace three is followed up. At the same time, the outlet well of furnace four is followed up, and furnace two enters the sealing and well closure stage. And so on, follow up the construction of furnaces five, six, ..., N in sequence; during the follow-up operation, the outlet well of the front furnace is used as the inlet well of the rear furnace (no need to construct an inlet well later, which effectively reduces the number of wells and improves mining efficiency and safety).

[0046] According to the above method, the process technology of gas injection fracturing, combustion gasification and sealing and closing of a process node of the subsequent furnace is realized in sequence.

[0047] The following example illustrates the continuous follow-up operation of the furnace according to the process technology. Take furnace 1 as the first furnace (the first furnace needs to construct the inlet and outlet wells, and the subsequent furnaces only construct the outlet wells and use the outlet wells of the previous furnace as the inlet wells). Since furnace 1 is the first furnace, furnace 1 is used as an example to introduce the gas injection fracturing technology method.

[0048] Gas injection fracturing method: The bottom of the outlet well of furnace 1 extends horizontally to the bottom of the inlet well of furnace 1 and is not connected (see Figure 1, horizontal drilling construction is carried out from the bottom of the gas outlet well of furnace one and extended horizontally to form a horizontal fracturing gas injection channel. At this time, the end of the extended horizontal fracturing gas injection channel should not be connected to the bottom of the gas inlet well, so that the gas outlet well of furnace one as a whole forms an L-shaped mine, and the L-shaped mine is not connected to the gas inlet well of furnace one at this time, and the L-shaped mine is a separate mine). The gas outlet well of furnace one is used to perform gas injection fracturing on the gasification mining area of ​​furnace one (because the L-shaped mine is a separate mine, the gasification mining area of ​​furnace one can be treated with gas injection fracturing. The gasification mining area of ​​furnace one is Figure 1 The right side area of ​​the middle gas outlet well), after the gas injection and fracturing is completed, the bottom of the gas outlet well is horizontally extended to the bottom of the gas inlet well and connected to each other (they are not connected during the gas injection and fracturing process, and are connected only after the gas injection and fracturing is completed).

[0049] The above is an introduction to the gas injection fracturing method using furnace one as an example. The furnace two in the technology of the present invention follows up the underground gasification operation of furnace one. After the gas injection fracturing of furnace one is completed, the gas outlet well of furnace one serves as the gas inlet of furnace two (the upper and lower furnaces share a directional well, which can be called the inlet and outlet directional well), and furnace two has an inlet well and an outlet well. Furnace two also performs gas injection fracturing in the gasification area to be mined of furnace two according to the above-mentioned gas injection fracturing method. Furnace three follows up the underground gasification operation of furnace two, and furnace three also adopts the above-mentioned gas injection fracturing method, and so on. The next furnace follows up the previous furnace, and the next furnace performs gas injection fracturing in the corresponding gasification area to be mined according to the above-mentioned gas injection fracturing method.

[0050] Gas injection fracturing is followed by combustion gasification. Since Furnace 1 is the first furnace (subsequent furnaces will follow in sequence), Furnace 1 is taken as an example to introduce the combustion gasification technology.

[0051] Combustion gasification method: A proportioned gasifying agent is introduced into the bottom of the inlet well of furnace 1 (at this time, the outlet well of furnace 1 is connected to the bottom of the inlet well), and the coal seam combustion gasification operation is carried out in the gasification area of ​​furnace 1 from the bottom of the inlet well to the bottom of the outlet well, and the synthesis gas is collected through the outlet well of furnace 1. The synthesis gas contains combustible gas and other substances that need to be removed and separated (such as water vapor, carbon dioxide, etc.), which are subsequently separated by the synthesis gas separation system 7 and the combustible gas is obtained (generally, the combustible gas will be further separated to meet different uses) and transported to the use and storage end 8.

[0052] The above is an introduction to the combustion gasification method using furnace 1 as an example. In the technology of the present invention, furnace 2 follows the underground gasification operation of furnace 1, and furnace 3 follows the underground gasification operation of furnace 2. When furnace 1 is in combustion gasification, furnace 2 performs gas injection fracturing. The bottom of the gas outlet well of furnace 2 horizontally extends to the bottom of the gas outlet well of furnace 1 (the gas outlet well of furnace 1 is regarded as a spare gas inlet well of furnace 2) and is not connected. The gas outlet well of furnace 2 is used to perform gas injection fracturing on the gasification waiting area of ​​furnace 2. The gas injection fracturing operation of furnace 2 is performed according to the aforementioned gas injection fracturing method.

[0053] After the combustion and gasification in furnace one is completed, furnace two performs combustion and gasification operations according to the above-mentioned combustion and gasification method. After the combustion and gasification in furnace two is completed, furnace three then performs combustion and gasification operations according to the above-mentioned combustion and gasification method, and so on. The next furnace follows the previous one and performs combustion and gasification operations in the corresponding gasification area to be mined according to the above-mentioned combustion and gasification method.

[0054] When the combustion gasification and synthesis gas collection of the gasification and mining area of ​​furnace one are completed, the bottom of the gas outlet well of furnace two is horizontally extended to the bottom of the gas inlet well and connected to each other, and the gasification and mining area of ​​furnace one becomes a combustion and empty area. "When the combustion gasification and synthesis gas collection of the gasification and mining area of ​​furnace one are completed, the bottom of the gas outlet well of furnace two is horizontally extended to the bottom of the gas inlet well and connected to each other" is the condition for furnace two to follow furnace one, that is, when or after the synthesis gas collection operation of furnace one is completed, the bottom of the gas outlet well of furnace two is horizontally extended to the bottom of the gas inlet well of furnace two (at this time, the gas inlet well of furnace two and the gas outlet well of furnace one are the same well, called the gas inlet and outlet directional well) and connected to each other.

[0055] The above takes the idle cooling treatment of furnace one in the combustion empty zone as an example. The furnace two in the technology of the present invention follows the underground gasification operation of furnace one, and furnace three follows the underground gasification operation of furnace two. When furnace one is idle and cooled, furnace two performs combustion gasification, furnace three performs gas injection fracturing, and furnace four starts construction. After the combustion and gasification of furnace two is completed, it follows up and enters the sealing and well closure.

[0056] Sealing and well closing method: After the furnace completes combustion and gasification, the next step is to wait for the combustion and gas zone of the furnace to cool down. The furnace's gas outlet well, gas outlet well, and gas inlet well form a space to be sealed. Carbon dioxide is injected into the space to be sealed through the gas inlet well as a displacement gas, and the mixed gas is collected through the gas outlet well to separate the combustible gas from the mixed gas. The mixed gas is tested at the gas outlet well, and when the proportion of the displacement gas in the mixed gas reaches P%, the displacement operation is stopped. Then, the end of the space to be sealed close to the gas outlet well is blocked, and high-pressure CO2 gas is injected into the space to be sealed through the gas inlet well to seal it. Then, a cement plug is closed at one end of the space to be sealed close to the gas inlet well, and a leakage detection device is installed to monitor and alarm for leakage. After the first furnace is sealed and the well closed, furnace two will be sealed and the well closed according to the above-mentioned sealing and well closing treatment method. After the second furnace is sealed and the well closed, furnace three will be sealed and the well closed according to the above-mentioned sealing and well closing treatment method. And so on. The next furnace follows the previous one and the next furnace will seal and close the corresponding combustion zone according to the above-mentioned sealing and well closing treatment method.

[0057] It should be noted that the sealing and well closure treatment is the process after the gas injection fracturing and combustion gasification operations. Since there is no close follow-up process for the front and rear furnaces like gas injection fracturing and combustion gasification, it can be handled in sequence according to the order of the furnaces. Among them, the sealing and well closure treatment includes the cooling process of the combustion and air zone of the furnace (which can be called idle cooling), CO2 displacement operation (relying on CO2 gas as a displacement gas to displace the mixed gas containing combustible gases in the space to be sealed) and CO2 sealing and well closure (injecting high-pressure CO2 gas for CO2 sealing. At the beginning of CO2 sealing, one end of the space to be sealed is blocked, and after the CO2 sealing operation is completed, the other end of the space to be sealed is blocked, thereby realizing the well closure treatment). The cooling of the combustion void area, CO2 displacement operations, and CO2 storage and well closure in the sealing and well closure treatment are handled sequentially according to the front and rear furnaces. The specific treatment time is determined according to the actual situation. It is impossible to follow up closely with the front and rear furnaces. The cooling time of the combustion void area of ​​the front and rear furnaces may be different. The CO2 displacement operations and CO2 storage and well closure of the front and rear furnaces can also be handled together.

[0058] After the combustion and gasification of the gasification and mining area of ​​furnace 2 and the collection of synthetic gas are completed, the gasification and mining area of ​​furnace 2 becomes a combustion-free area, and the bottom of the gas outlet well of furnace 3 is horizontally extended to the bottom of the gas inlet well and connected to each other. After the temperature is lowered, furnace 1 is plugged, high-pressure CO2 is sealed and the well is closed. Furnace 1 undergoes the process of gas injection fracturing, combustion and gasification, and sealing and well closure of steps S1 to S3. Similarly, furnace two, furnace three, etc. all follow the standardized process of gas injection fracturing, combustion gasification, and sealing and well closure treatment. The above-mentioned standardized process includes one process node of gas injection fracturing, combustion gasification, and sealing and well closure treatment. The front and rear furnaces are one process node apart (that is, the front and rear furnaces are one process node apart) for follow-up operations. If the three process nodes are respectively arranged as the first, second, and first process nodes, then if the rear furnace is at the second process node, the front furnace is at the first process node, and so on, the three process node operations of all furnaces are followed up in sequence, and each furnace follows the standardized process of gas injection fracturing, combustion gasification, and sealing and well closure treatment.

[0059] In some embodiments, all furnaces complete the process technology in sequence according to the gas outlet well of the previous furnace as the gas inlet well of the next furnace. All furnaces in the coal mining area follow up continuously in a straight line or in an S-shaped manner according to the furnace sequence; taking linear mining as an example, multiple continuous mining linear advancement paths can be designed and planned, and multiple differential node follow-up mining methods are carried out simultaneously, which enhances the gasification efficiency and ensures the orderly succession of multiple process nodes, fast mining and production, and increases the total mining output, greatly improving the mining efficiency.

[0060] Embodiment 2

[0061] like Figure 1 to Figure 5As shown, a method for underground coal combustion gasification and carbon dioxide storage mining and processing, the method comprising:

[0062] S1. Gas injection fracturing: The gas inlet and outlet wells of the construction furnace are connected. The bottom of the outlet well extends horizontally to the bottom of the gas inlet well and is not connected (see Figure 1 During the gas injection fracturing stage, the horizontal fracturing gas injection channel extending horizontally from the bottom of the outlet well is not connected to the bottom of the inlet well. For details, see Figure 1 The connected position in the middle is indicated by a dotted line indicating that it is not connected), and fracturing gas is introduced through the gas outlet well to perform gas injection fracturing on the gasification mining area of ​​the furnace and form a fracturing network 19 (the fracturing network 19 improves the efficiency of subsequent combustion and gasification) corresponding to the coal seam in the gasification mining area; the horizontal fracturing gas injection channel extending horizontally from the bottom of the gas outlet well of the present invention can increase the distance between the gas inlet well and the gas outlet well, and can complete the gas injection and fracturing operation within a large distance between the gas inlet well and the gas outlet well, so that the number of construction wells in the entire coal mining area is greatly reduced, the impact on the coal strata is effectively reduced, and the safety performance of underground combustion and gasification is improved; at the same time, a horizontal fracturing gas injection channel is used to perform gas injection and fracturing from the bottom toward the gasification mining area of ​​the furnace, which can greatly improve the efficiency of gas injection and fracturing, and thus improve the efficiency of subsequent combustion and gasification. After the gas injection and fracturing is completed, the bottom of the gas outlet well is horizontally extended to form a horizontal fracturing gas injection channel portion and is interconnected with the bottom of the gas inlet well (after the gas injection and fracturing is completed, the horizontal fracturing gas injection channel extending horizontally from the bottom of the gas outlet well is connected to the bottom of the gas inlet well, see Figure 3 The connected positions are indicated by solid lines).

[0063] S2, Combustion gasification: The mining direction is from the bottom of the furnace inlet well to the bottom of the gas outlet well (with Figure 3 For example, the mining direction is from right to left), the gasification agent is introduced through the gas inlet well to carry out coal seam combustion gasification operation in the gasification mining area of ​​the furnace, and the gas is discharged and collected through the furnace outlet (the coal seam combustion gasification operation produces a synthesis gas containing combustible gas, which is discharged through the gas outlet well and collected at the end of the gas outlet well, and then the synthesis gas is separated and treated to finally obtain the required combustible gas), and the combustible gas is separated from the synthesis gas. After the combustion and gasification of the gasification mining area of ​​the furnace is completed, a combustion empty zone is formed, and the combustion empty zone of the furnace is cooled.

[0064] S3. Sealing and closing the well: After the combustion zone of the furnace has been cooled down (the cooling down of the combustion zone of the furnace also includes the following detection method: a temperature sensor 23 for monitoring the temperature of the combustion zone is provided in the furnace's air inlet well. When the temperature sensor 23 drops to the ambient temperature, the combustion zone of the furnace has been idle and cooled down), the furnace's air outlet well, the combustion zone, and the air inlet well form a space to be sealed. Carbon dioxide is injected into the space to be sealed through the air inlet well as a displacement gas, and the mixed gas is collected through the air outlet well to separate the combustible gas from the mixed gas. The mixed gas is detected at the air outlet well. When the proportion of the displacement gas (using carbon dioxide as the displacement gas) detected in the mixed gas reaches P%, the displacement operation is stopped. Then, seal the end of the space to be sealed close to the gas outlet well, and inject high-pressure CO2 gas into the space to be sealed through the gas inlet well for sealing (coal combustion gasifies into carbon slag, which remains in the combustion void area. In order to protect the combustion void area, it is necessary to inject high-pressure CO2 gas for sealing and protection). Then, seal the cement plug at one end of the space to be sealed close to the gas inlet well and install a leakage detection device for leakage monitoring and alarm (the leakage detection device monitors whether there is gas discharge from the underground after mining. If there is gas discharge, it means that there is leakage in the sealing and further measures need to be taken). The method of injecting high-pressure CO2 gas for sealing is as follows:

[0065] One end of the gas inlet of the furnace and the gas outlet channel (including the combustion zone) between the gas inlet and the gas outlet well is blocked by a cement stone blocking block 21 (a grouting pipe 20 is provided in this embodiment to construct the cement stone blocking block 21). Then, high-pressure CO2 gas is injected into the gas outlet channel and the combustion zone of the furnace for sealing. Then, a cement plug 24 is sealed at the other end of the gas outlet channel (a grouting pipe 20 is provided in this embodiment to construct the cement plug 24). Finally, a leakage detection device 25 is installed at the wellhead of the gas inlet well and / or the gas outlet well for leakage monitoring and alarm.

[0066] In order to better realize the supply of carbon dioxide for gas injection fracturing, the proportioned supply of gasifying agent for combustion gasification, and the collection and separation of combustion gasification synthesis gas, the present invention includes a combined supply and processing system (the combined supply and processing system is arranged on the ground of the underground coal gasification mining area; preferably, a movable system can be constructed to move with the advancement of mining), the combined supply and processing system includes a synthesis gas separation system 7, a high-pressure carbon dioxide supply system and a gasifying agent supply system, the high-pressure carbon dioxide supply system includes a CO2 gas storage tank 5 and a high-pressure carbon dioxide control and compressor unit 6 connected to the CO2 gas storage tank 5, the high-pressure carbon dioxide control and compressor unit 6 generates high-pressure CO2 and is used as fracturing gas for gas injection fracturing. The gasification agent supply system includes a water vapor generator 2, an oxygen generator 3, a gasification agent control station 1 and a gas injection high-pressure pump group 4. The water vapor generator 2 is used to produce water vapor, and the oxygen generator 3 is used to produce oxygen. The gasification agent control station 1 is connected to the water vapor generator 2 and the oxygen generator 3 respectively and mixes water vapor and oxygen into a gasification agent, which is transported to the gas injection high-pressure pump group 4. The gas injection high-pressure pump group 4 is used to generate high-pressure gasification agent and input it into the gasification area to be mined by the furnace for coal seam combustion gasification. The gas separation system 7 is used to collect the synthesis gas generated by coal seam combustion gasification and / or the mixed gas discharged by the displacement operation and separate it to obtain combustible gas. The combined supply and processing system of the present invention can move along the advancement path of the underground gasification exploitation of the furnace. The combined supply and processing system includes a synthesis gas separation system, a high-pressure carbon dioxide supply system and a gasifying agent supply system. The synthesis gas separation system realizes the separation and processing of the combustible gas, CO2 and water vapor collected during the exploitation of the synthesis gas, wherein the CO2 and water vapor can be recycled. The high-pressure carbon dioxide supply system supplies the carbon dioxide required for the gas injection and fracturing stage and the CO2 storage and well closure treatment stage of the present invention. The gasifying agent supply system can set the required ratio of gasifying agent (mainly oxygen and water vapor, with a small amount of CO2 and other substances added) according to the sampled rock formation and supply it to the gasification area to be mined for combustion and gasification operations.

[0067] In some embodiments, the outlet end of the gas injection high-pressure pump group 4 is connected to a gasification agent injection pipe 41, the inlet end of the synthesis gas separation system 7 is connected to a gas production pipe 71, and the outlet end of the high-pressure carbon dioxide control and compressor group 6 is connected to a fracturing gas injection pipe 61. During the gas injection and fracturing stage of step S1, the fracturing gas injection pipe 61 is connected to the gas outlet well of the furnace in a closed manner or the fracturing gas injection pipe 61 is extended to the horizontal fracturing gas injection channel part of the furnace outlet well and the gasification to-be-produced area above is subjected to gas injection and fracturing operations, and a gas sensor 18 is provided at the wellhead of the furnace inlet well to detect whether there is gas outlet of fracturing gas.

[0068] In some embodiments, during the combustion and gasification stage of step S2, the gas sensor 18 of the furnace's air inlet well is removed, the gasifying agent injection pipe 41 is tightly connected to the furnace's air inlet well, or the gasifying agent injection pipe 41 is extended into the furnace's horizontal fracturing injection channel part and advances in the mining direction, and the gas production pipe 71 is tightly connected to the furnace's gas outlet well. The synthesis gas produced by combustion and gasification in the gasification area of ​​the furnace passes through the gas production pipe 71 and enters the synthesis gas separation system 7 and is separated to obtain combustible gas.

[0069] In some embodiments, the gas separation system 7 is also connected to the user and the storage end 8, and the combustible gas separated by the gas separation system 7 is transported to the user and the storage end 8. The gas separation system 7 is connected to the CO2 gas storage tank 5 and the gasification agent control station 1 respectively, and the CO2 gas separated by the gas separation system 7 is transported to the CO2 gas storage tank 5 and the gasification agent control station 1 respectively. The gasification agent control station 1 also adds CO2 gas as a new gasification agent in the corresponding proportion of the gasification agent mainly composed of water vapor and oxygen. The gasification area of ​​the furnace is sampled and studied. Some coal strata have water vapor and oxygen as the main components and their corresponding gasification agents are proportioned. Some coal strata also need to proportion an appropriate amount of CO2 gas in the gasification agent. Therefore, the gas separation system 7 can supply a part of CO2 gas to the gasification agent control station 1. Specifically, if the gasification agent control station 1 requires CO2 gas, a part of CO2 gas is metered and input. The CO2 gas separated by the gas separation system 7 is transported to the CO2 gas storage tank 5 respectively, so as to replenish the carbon dioxide gas in the CO2 gas storage tank 5, and allow the carbon dioxide gas generated in the combustion zone to circulate and replenish the CO2 gas storage tank 5, and be used for gas injection fracturing (gas injection fracturing uses high-pressure CO2 injection for fracturing), sealing and well closure treatment (sealing and well closure treatment also uses high-pressure CO2 injection to achieve displacement and sealing), etc. During the gas displacement of the space to be sealed in the sealing and closing stage of step S3, the fracturing gas injection pipe 61 is connected to the gas inlet well of the furnace or the fracturing gas injection pipe 61 is penetrated into the bottom of the gas inlet well of the furnace (preferably, the gasification agent control station 1 of the present invention can mix the gas containing only CO2 gas and pressurize it through the gas injection high-pressure pump group 4 to form high-pressure CO2 gas, and then directly use the gasification agent gas injection pipe 41 to carry out gas displacement), and the gas production pipe 71 is tightly connected to the gas outlet well of the furnace, and the mixed gas displaced from the space to be sealed in the furnace enters the synthesis gas separation system 7 through the gas production pipe 71 and separates the combustible gas. The gasifier control station 1 of the present invention can only mix CO2 gas and output only high-pressure CO2 gas through the gas injection high-pressure pump group 4 and the gasifier gas injection pipe 41; therefore, when the gas in the space to be sealed is displaced in the sealing and closing stage of step S3, the gasifier control station 1 only mixes CO2 gas and injects high-pressure CO2 gas through the gasifier gas injection pipe 41, and the gas production pipe 71 is tightly connected to the gas outlet well of the furnace. The mixed gas displaced from the space to be sealed in the furnace enters the synthesis gas separation system 7 through the gas production pipe 71 and is separated to obtain combustible gas.

[0070] In some embodiments, before gas injection and fracturing in the gasification zone of the furnace, see Figure 1 , Figure 6 First, a packer 17 is used to seal the bottom of the gas outlet well of the furnace during the gas injection and fracturing stage. The front section of the fracturing gas injection pipe 61 is a gas injection distribution pipe 9. The gas injection distribution pipe 9 is connected to a horizontal fracturing gas injection channel and is provided with a plurality of diverter nozzles 16 (each diverter nozzle 16 is equipped with a gas injection control valve 15). Each diverter nozzle 16 is distributed at the bottom of the gasification mining area of ​​the furnace. Each diverter nozzle 16 of the gas injection distribution pipe 9 injects high-pressure CO2 into the coal seam inside the gasification mining area and forms a fracture network in the coal seam.

[0071] In some embodiments, the inlet well and / or outlet well of the furnace are constructed by drilling tools, and the bottom of the outlet well of the furnace is horizontally extended by drilling tools equipped with a drill bit guide system. The inlet well and outlet well of the furnace are reinforced and protected by casing 10 during the working stage. Preferably, the drilling tool equipped with a drill bit guide system in this embodiment includes a drill bit 11 and a bent screw power drill 13 installed at the rear end of the drill bit 11 to drive the drill bit 11, and a horizontal fracturing gas injection channel downhole tractor 14 to serve as traction power for the horizontal extension construction of the drill bit 11. The drill bit guide system includes a drill bit guide tool 12 installed on the drill bit 11 to steer or guide the drill bit.

[0072] Furthermore, the present invention can realize continuous follow-up operation of all furnaces according to the process technology, and the specific method is as follows:

[0073] A coal mining area is selected, and the furnaces for continuous advancement of operations in the coal mining area are planned. The furnaces are numbered in sequence as Furnace 1, Furnace 2, Furnace 3, ..., Furnace N. Each furnace follows the standardized process of three process nodes: gas injection fracturing, combustion gasification, and sealing and well closure.

[0074] When the gas injection and fracturing stage of furnace one is in progress or completed, follow up with the gas outlet well of furnace two. During the combustion and gasification process of furnace one, gas injection and fracturing are carried out on the gasification area to be mined of furnace two through the gas outlet well of furnace two. When the combustion and gasification of furnace one is completed, the gas outlet well of furnace one is used as the gas inlet well of furnace two, and the ignition and vaporization of furnace two are followed up, and at the same time, the gas outlet well of furnace three is followed up. When furnace one is cooled down and enters the sealing and well closure stage, the gas outlet channel of furnace one near one end of the gas outlet well is blocked. When the combustion and gasification of furnace two is completed, the gas outlet well of furnace two is used as the gas inlet well of furnace three, and the gas injection and fracturing of furnace three is followed up, and at the same time, the gas outlet well of furnace four is followed up, and furnace two enters the sealing and well closure stage. According to the above method, the process technology of the three process nodes of gas injection and fracturing, combustion and gasification, and sealing and well closure of subsequent furnaces is realized in sequence.

[0075] In some embodiments, all furnaces complete the process technology in sequence according to the gas outlet well of the previous furnace as the gas inlet well of the next furnace. All furnaces in the coal mining area follow up continuously in a straight line or in an S-shaped manner according to the furnace sequence; taking linear mining as an example, multiple continuous mining linear advancement paths can be designed and planned, and multiple differential node follow-up mining methods are carried out simultaneously, which enhances the gasification efficiency and ensures the orderly succession of multiple process nodes, fast mining and production, and increases the total mining output, greatly improving the mining efficiency.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for underground coal combustion gasification and carbon dioxide storage mining and processing, characterized by: The methods include: S1. Gas injection fracturing: construct the gas inlet well and gas outlet well of the furnace, the bottom of the gas outlet well is horizontally extended to the bottom of the gas inlet well and is not connected, and the fracturing gas is introduced through the gas outlet well to perform gas injection fracturing on the gasification waiting area of ​​the furnace and form a fracturing network corresponding to the coal seam in the gasification waiting area. After the gas injection fracturing is completed, the bottom of the gas outlet well is horizontally extended to form a horizontal fracturing gas injection channel part and is connected to the bottom of the gas inlet well; S2. Combustion and gasification: The mining direction is from the bottom of the furnace's air inlet well to the bottom of the air outlet well. The gasification agent is introduced through the air inlet well to carry out coal seam combustion and gasification operations on the gasification mining area of ​​the furnace, and the synthesis gas is discharged and collected through the furnace's air outlet well, and the combustible gas is separated from the synthesis gas; after the combustion and gasification of the gasification mining area of ​​the furnace is completed, a combustion empty zone is formed, and the combustion empty zone of the furnace is cooled down; S3. Sealing and closing the well: After the combustion-air gap area of ​​the furnace has been cooled down, the furnace's gas outlet well, gas outlet area and gas inlet well form a space to be sealed. Carbon dioxide is injected into the space to be sealed through the gas inlet well as a displacement gas, and the mixed gas is collected through the gas outlet well to separate the combustible gas from the mixed gas. The mixed gas is tested at the gas outlet well, and when the proportion of the displacement gas in the mixed gas reaches P%, the displacement operation is stopped. Then, the end of the space to be sealed close to the gas outlet well is blocked, and high-pressure CO2 gas is injected into the space to be sealed through the gas inlet well to seal it. Then, a cement plug is closed at one end of the space to be sealed close to the gas inlet well, and a leakage detection device is installed to monitor and alarm for leakage.

2. The underground coal combustion gasification and carbon dioxide storage mining and processing method according to claim 1 is characterized by: The invention comprises a combined supply and processing system, wherein the combined supply and processing system comprises a synthesis gas separation system (7), a high-pressure carbon dioxide supply system and a gasifying agent supply system, wherein the high-pressure carbon dioxide supply system comprises a CO2 gas storage tank (5) and a high-pressure carbon dioxide control and compressor unit (6) connected to the CO2 gas storage tank (5), wherein the high-pressure carbon dioxide control and compressor unit (6) generates high-pressure CO2 and serves as fracturing gas for gas injection fracturing; the gasifying agent supply system comprises a water vapor generator (2), an oxygen generator (3), a gasifying agent control station (1) and a gas injection high-pressure gas generator (2). The invention relates to a gasification pump group (4), a water vapor generator (2) for producing water vapor, an oxygen generator (3) for producing oxygen, a gasification agent control station (1) connected to the water vapor generator (2) and the oxygen generator (3) respectively, and using water vapor and oxygen as the main components to mix and match the gasification agent into a gasification agent, which is then transported to the gas injection high-pressure pump group (4), and the gas injection high-pressure pump group (4) is used to generate high-pressure gasification agent and input it into the gasification area of ​​the furnace for coal seam combustion and gasification; the gas separation system (7) is used to collect the synthesis gas generated by coal seam combustion and gasification and / or the mixed gas discharged by the displacement operation and separate them to obtain combustible gas.

3. The underground coal combustion gasification and carbon dioxide storage mining and processing method according to claim 2 is characterized by: The gas outlet of the gas injection high-pressure pump group (4) is connected to a gasification agent gas injection pipe (41), the gas inlet of the synthesis gas separation system (7) is connected to a gas production pipe (71), and the gas outlet of the high-pressure carbon dioxide control and compressor group (6) is connected to a fracturing gas injection pipe (61); during the gas injection and fracturing stage of step S1, the fracturing gas injection pipe (61) is connected to the gas outlet well of the furnace in a closed manner or the fracturing gas injection pipe (61) is extended to the horizontal fracturing gas injection channel part of the furnace gas outlet well and the gasification waiting area above is subjected to gas injection and fracturing operations, and a gas sensor (18) is provided at the wellhead of the furnace gas inlet well to detect whether there is gas outlet of fracturing gas; During the combustion and gasification stage of step S2, the gas sensor (18) of the furnace's air inlet well is removed, the gasifying agent injection pipe (41) is connected to the furnace's air inlet well in a sealed manner, or the gasifying agent injection pipe (41) is extended to the furnace's horizontal fracturing injection channel and advanced in the mining direction, the gas production pipe (71) is connected to the furnace's gas outlet well in a sealed manner, and the synthesis gas generated by combustion and gasification in the furnace's gasification waiting area enters the synthesis gas separation system (7) through the gas production pipe (71) and is separated to obtain combustible gas.

4. The underground coal combustion gasification and carbon dioxide storage mining and processing method according to claim 2 is characterized by: The gas separation system (7) is also connected to a user and a storage end (8), and the combustible gas separated by the gas separation system (7) is transported to the user and the storage end (8); the gas separation system (7) is respectively connected to a CO2 gas storage tank (5) and a gasification agent control station (1), and the CO2 gas separated by the gas separation system (7) is respectively transported to a CO2 gas storage tank (5) and a gasification agent control station (1), and the gasification agent control station (1) also adds CO2 gas as a new gasification agent in a corresponding proportion to a gasification agent mainly composed of water vapor and oxygen; During the gas displacement of the space to be sealed in the sealing and closing stage of step S3, the gasification agent control station (1) only mixes CO2 gas and injects high-pressure CO2 gas through the gasification agent injection pipe (41), and the gas production pipe (71) is tightly connected to the gas outlet well of the furnace. The mixed gas displaced from the space to be sealed in the furnace enters the synthesis gas separation system (7) through the gas production pipe (71) and is separated to obtain combustible gas.

5. The underground coal combustion gasification and carbon dioxide storage mining and processing method according to claim 3 is characterized by: Before gas injection fracturing in the gasification mining area of ​​the furnace, a packer is first used to perform a gas injection fracturing stage sealing operation on the bottom of the furnace's gas outlet well. The front section of the fracturing gas injection pipe (61) is a gas injection distribution pipe (9). The gas injection distribution pipe (9) is placed in the horizontal fracturing gas injection channel and is connected to a plurality of diversion nozzles (16). The diversion nozzles (16) are distributed at the bottom of the gasification mining area of ​​the furnace. The diversion nozzles (16) of the gas injection distribution pipe (9) inject high-pressure CO2 into the coal seam inside the gasification mining area and form a fracturing crack network in the coal seam.

6. The underground coal combustion gasification and carbon dioxide storage mining and processing method according to claim 1 is characterized by: The furnace's air inlet well and / or air outlet well are constructed using drilling tools, and the bottom of the furnace's air outlet well is horizontally extended using a drilling tool equipped with a drill bit guide system; the furnace's air inlet well and air outlet well are both reinforced and protected by casing (10) during the working stage.

7. The underground coal combustion gasification and carbon dioxide storage mining and processing method according to claim 6 is characterized by: The drilling tool equipped with a drill bit guide system comprises a drill bit (11), a bent screw power drill (13) installed at the rear end of the drill bit (11) and used to drive the drill bit (11), and a horizontal fracturing gas injection channel downhole tractor (14) used to provide traction power for horizontal extension construction of the drill bit (11). The drill bit guide system comprises a drill bit guide tool (12) installed on the drill bit (11) and used to steer or guide the drill bit.

8. The underground coal combustion gasification and carbon dioxide storage mining and processing method according to claim 1 is characterized by: The furnace combustion zone cooling also includes the following detection method: a temperature sensor (23) for monitoring the combustion zone temperature is arranged in the furnace air intake shaft; when the temperature sensor (23) is lowered to the ambient temperature, the furnace combustion zone idle cooling is completed.

9. The underground coal combustion gasification and carbon dioxide storage mining and processing method according to any one of claims 1 to 8, characterized in that: Also includes the following methods: Select a coal mining area, plan the furnaces for continuous advancement of the coal mining area, and number them in order of furnace 1, furnace 2, furnace 3, ..., furnace N. Each furnace is processed according to the three process nodes of gas injection fracturing, combustion gasification, and sealing and closing the well; When the gas injection and fracturing stage of furnace one is in progress or completed, the gas outlet well of furnace two is followed up; when furnace one is in the process of combustion and gasification, gas injection and fracturing are carried out on the gasification waiting area of ​​furnace two through the mountain gas well of furnace two; when the combustion and gasification of furnace one is completed, the gas outlet well of furnace one is used as the gas inlet well of furnace two, and the ignition and gasification of furnace two are followed up, and at the same time, the gas outlet well of furnace three is followed up; when furnace one is cooled down and enters the sealing and well closing stage, the mountain gas channel of furnace one near one end of the gas outlet well is blocked; when the combustion and gasification of furnace two is completed, the mountain gas well of furnace two is used as the gas inlet well of furnace three, and the gas injection and fracturing of furnace three is followed up, and at the same time, the gas outlet well of furnace four is followed up, and furnace two enters the sealing and well closing stage; According to the above method, the process technology of the three process nodes of gas injection fracturing, combustion gasification and sealing and closing of the well in the subsequent furnace is realized in sequence.

10. The underground coal combustion gasification and carbon dioxide storage mining and processing method according to claim 9, characterized in that: All furnaces complete the process technology in sequence with the outlet well of the previous furnace serving as the inlet well of the next furnace; all furnaces in the coal mining area follow up continuously in a straight line or in an S-shaped manner according to the furnace sequence.

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