Deep coal seam group carbon dioxide co-sequestration integrated system and method

Abstract

The application discloses a kind of deep extreme near coal seam group carbon dioxide collaborative storage integrated system and method, system includes carbon dioxide injection system, rapid cementing material injection system and multifunctional injection device, the pipeline of carbon dioxide injection system and the pipeline of rapid cementing material injection system are all connected to target reservoir below ground surface, target reservoir includes upper coal seam, interburden layer and lower coal seam from top to bottom in sequence, multifunctional injection device is arranged in the pinnate distribution horizontal well of interburden layer.The multifunctional injection device includes inner tube, outer tube and branch pipe, the end of outer tube and branch pipe is equipped with energy-gathering cavity I, the end of inner tube is equipped with energy-gathering cavity II, the lower part of injection pipeline of carbon dioxide injection system is connected with outer tube, the lower end of injection pipeline of rapid cementing material injection system is connected with inner tube.The application is fractured to target reservoir by carbon dioxide first and then injects carbon dioxide, and realizes carbon dioxide storage by injecting rapid cementing material to interburden layer.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide sequestration, and in particular to an integrated system and method for the coordinated sequestration of carbon dioxide in a deep and extremely close coal seam group. Background Art

[0002] Carbon capture and storage (CCS) technology can reduce CO2 emissions and has broad application prospects. Consequently, numerous researchers have conducted research on CO2 geological storage. Currently, three primary geological structures are suitable for CO2 geological storage: saline-alkali aquifers, oil and gas reservoirs, and unrecoverable coal seams. CO2 storage in unrecoverable coal seams is often integrated with enhanced coalbed methane (CBM) extraction, leveraging CO2's significant competitive adsorption advantage over CH4 to achieve efficient CH4 recovery while simultaneously storing CO2.

[0003] For example, the Chinese patent with publication number CN115539130A discloses a method for enhanced coalbed methane extraction and carbon dioxide storage in unmineable coal seams. The method first fractures the unmineable coal seam by means of carbon dioxide foam pulsating fracturing, thereby expanding the reservoir transformation range, improving the coal body cracking effect, and providing a broad adsorption space for carbon dioxide storage. Then, the carbon dioxide injection and coalbed methane enhanced extraction process are started. By carrying out carbon dioxide injection and coalbed methane extraction simultaneously, carbon dioxide gas forms a closed loop between the extraction system, injection wells, unmineable coal seams and drainage wells, so that carbon dioxide gas is continuously injected into various cracks in the coal seam, continuously displacing the adsorbed methane for desorption and discharge, and adsorbing carbon dioxide gas in the coal seam until a large amount of coalbed methane is extracted, and then the unmineable coal seam is sealed to achieve carbon dioxide storage. The shortcoming of this patent is that it only considers the situation of carbon dioxide storage in a single deep coal seam. If it is used for the situation of a group of deep and close coal seams, it is impossible to achieve the injection and storage of the coal seam group at the same time through this method, and the injected carbon dioxide has the risk of leakage to other strata through the interbedded gangue layers. Summary of the Invention

[0004] In order to overcome the defects in the prior art, the present invention provides an integrated system and method for the coordinated storage of carbon dioxide in deep and close coal seams.

[0005] The technical solution adopted by the present invention is as follows: In the first aspect, the present invention proposes an integrated system for the coordinated storage of carbon dioxide in a deep and extremely close coal seam group, including a carbon dioxide injection system for fracturing a target reservoir and injecting carbon dioxide into the target reservoir; the target reservoirs are, from top to bottom, an upper coal seam, an interbedded coal seam, and a lower coal seam; a rapid gelling material injection system for injecting rapid gelling material into the interbedded coal seam to store carbon dioxide; a multifunctional injection device, arranged in a feather-shaped branch horizontal well in the interbedded coal seam, for cooperating with the carbon dioxide injection system and the rapid gelling material injection system to inject and store carbon dioxide; the multifunctional injection device includes an outer pipe, an inner pipe, and a branch pipe, the outer pipe being arranged along the feather-shaped branch The horizontal well is arranged in the horizontal direction, and the inner pipe is located inside the outer pipe and is consistent with the extension direction of the outer pipe; the upper and lower branches of the feather-shaped branch horizontal well extend into the upper coal seam and the lower coal seam respectively; the branch pipe is located in the upper and lower branches of the feather-shaped branch horizontal well and is integrally connected with the outer pipe; the outer pipe is connected to the carbon dioxide injection system, and the inner pipe is connected to the rapid gelling material injection system; the outer pipe and the branch pipe ends are provided with an energy-gathering cavity I, and the energy-gathering cavity I is provided with multiple energy discharge ports along the circumference, and a delivery port is provided at the head; the inner pipe end is provided with an energy-gathering cavity II, and the energy-gathering cavity II is located inside the energy-gathering cavity I at the outer pipe end, and the outlet of the energy-gathering cavity II faces the delivery port.

[0006] As a further improvement of the present invention, the carbon dioxide injection system includes a carbon dioxide storage and transportation tank, a carbon dioxide injection pump, a carbon dioxide injection valve and a flow meter I, the carbon dioxide storage and transportation tank is connected to the carbon dioxide injection pump, and the carbon dioxide injection valve and the flow meter I are located on the pipeline connecting the carbon dioxide injection pump and the outer tube of the multifunctional injection device.

[0007] As a further improvement of the present invention, the rapid gelling material injection system includes a gelling material storage tank, a gelling material injection pump, a gelling material injection valve and a flow meter II. The gelling material storage tank is connected to the gelling material injection pump, and the gelling material injection valve and the flow meter II are located in the pipeline between the gelling material injection pump and the inner tube of the multifunctional injection device.

[0008] As a further improvement of the present invention, a branch magnetically controlled valve is provided at the position where the outer tube is connected to the inner tube, and a main magnetically controlled valve is provided between the outer tube and the energy-gathering cavity I at its end; the main magnetically controlled valve and the branch magnetically controlled valve are used to open and close the injection of carbon dioxide; and flow meters III are provided in the energy-gathering cavity I of the outer tube and the inner tube.

[0009] As a further improvement of the present invention, the system further includes a control terminal, and the flowmeter I, the flowmeter II, the flowmeter III, the main magnetic control valve and the branch magnetic control valve are all connected to the control terminal.

[0010] As a further improvement of the present invention, the system further comprises a packer, which is installed at the air inlet end of the multifunctional injection device to prevent carbon dioxide from rising.

[0011] In a second aspect, the present invention also proposes a method for synergistic carbon dioxide storage in a deep and close coal seam group, comprising the following steps:

[0012] S1. Select the target reservoir for feather-shaped branch horizontal well construction, including:

[0013] Step S11, determining the accurate positions of the upper coal seam, the interbedded gangue layer and the lower coal seam in the deep and close coal seam group in the stratum;

[0014] Step S12: constructing a feather-shaped branch horizontal well from the ground through the near-surface rock layer, the aquifer, the dense rock layer and the upper coal seam toward the coal seam group. The main branch of the horizontal well is located in the center of the interbedded coal seam and constructed along the interbedded coal seam. The upper branch of the horizontal well is constructed at an inclination angle of no more than 45° to the roof of the upper coal seam, and the lower branch of the horizontal well is constructed at an inclination angle of no more than 45° to the floor of the lower coal seam. After completion, the drilling operation is stopped.

[0015] S2. Layout of carbon dioxide injection system and rapid gelling material injection system, including:

[0016] Step S21: Extend a multifunctional injection device from the surface horizontal wellhead. According to the actual construction orientation of the main branch and branches of the feather-shaped horizontal well, the outer and inner pipes of the multifunctional injection device are placed in the designed positions in the main branch of the horizontal well, and the branch pipes are placed in the branches of the horizontal well;

[0017] Step S22: Connect the lower end of the injection pipe of the carbon dioxide injection system to the outer pipe, and connect the lower end of the injection pipe of the rapid gelling material injection system to the inner pipe;

[0018] S3. Perform carbon dioxide fracturing and injection into the target reservoir, specifically including:

[0019] Step S31: The carbon dioxide in the carbon dioxide storage tank is heated and pressurized by a carbon dioxide injection pump, converted into supercritical carbon dioxide, and injected into the outer tube at a pressure greater than the target reservoir. The carbon dioxide energy release port on the side wall of the energy-gathering chamber I is opened by the control terminal. The supercritical carbon dioxide undergoes a phase transition due to changes in pressure and temperature, causing fractures in the upper coal seam, the lower coal seam, and the interbedded gangue layer.

[0020] Step S32: After fracturing, the delivery port at the front end of the energy-gathering chamber 1 is controlled to open, and carbon dioxide is continuously injected into the reservoir through the energy-releasing port and the delivery port at a constant pressure. An injection rate threshold is set, and the carbon dioxide injection amount and injection rate are monitored. When the injection rate continuously decreases below the threshold, the carbon dioxide injection into the target reservoir is completed.

[0021] S4. Rapidly injecting gelling materials into the target reservoir, specifically including:

[0022] Step S41: After the rapid gelling material in the gelling material storage tank is increased in delivery pressure by the gelling material injection pump, it enters the energy-gathering chamber II along the inner tube at a pressure greater than the reservoir pressure. The gelling material is rapidly ejected into the interbedded gangue layer through the energy discharge port and delivery port of the energy-gathering chamber I at the end of the outer tube. After entering the interbedded gangue layer, the gelling material mixes with the carbon dioxide and the rocks in the interbedded gangue layer to form a negative carbon high-porosity filling material structure, thereby solidifying the carbon dioxide flowing in the interbedded gangue layer and the carbon dioxide escaping into the interbedded gangue layer from the upper coal seam and the lower coal seam;

[0023] Step S42: continuously injecting fast-setting material into the reservoir at a constant pressure, setting an injection rate threshold, monitoring the injection amount and injection rate of the gelling material, and when the injection rate continuously decreases below the threshold, removing the multifunctional injection device from the horizontal well to complete the coordinated storage of carbon dioxide in the target reservoir.

[0024] The beneficial effects of the present invention are: the present invention introduces negative carbon filling technology for extremely close coal seam groups, realizes the coordinated storage of deep unminable extremely close coal seam groups and interbedded gangue layers, uses the deep unminable coal seams in coal mines as carbon dioxide storage space, and utilizes coal-based solid waste to prepare carbon dioxide adsorption and storage materials to achieve safe storage of carbon dioxide, and can also utilize interbedded gangue layers to dispose of solid waste on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Figure 1 This is a layout diagram of the integrated system for the coordinated storage of carbon dioxide in deep and close coal seams of the present invention;

[0027] Figure 2 It is a structural schematic diagram of a multifunctional injection device.

[0028] In the figure, 1, control terminal; 2, flowmeter I; 3, carbon dioxide injection valve; 4, carbon dioxide injection pump; 5, carbon dioxide storage and transportation tank; 6, flowmeter II; 7, cementing material injection valve; 8, cementing material injection pump; 9, cementing material storage tank; 10, near-surface rock stratum; 11, aquifer; 12, tight rock stratum; 13, upper coal seam; 14, parting; 15, lower coal seam; 16, packer; 17, multifunctional injection device; 17-1, outer pipe; 17-2, inner pipe; 17-3, branch pipe; 17-4, energy-gathering cavity I; 17-5, energy-releasing port; 17-6, conveying port; 17-7, energy-gathering cavity II; 17-8, main magnetic control valve; 17-9, branch magnetic control valve; 17-10, energy-gathering cavity outlet valve; 17-11, flowmeter III. DETAILED DESCRIPTION

[0029] Figure 1 The deep extreme near coal seam group carbon dioxide collaborative storage integrated system is shown, where the deep refers to coal seams with a buried depth greater than 1500m, which are difficult to mine under the existing technical means and suitable for carbon dioxide storage. The extreme near coal seam group refers to coal seams with a very close spacing (spacing between upper and lower seams within 5m), where mining one coal seam will have a significant impact on another coal seam, or one coal seam is bifurcated into two coal seams in some areas. The thin rock stratum between the two coal seams can be regarded as a parting.

[0030] The collaborative storage integrated system of the present application comprises a carbon dioxide injection system, a rapid cementing material injection system and a multifunctional injection device 17, wherein the carbon dioxide injection system comprises a carbon dioxide injection pump 4, a carbon dioxide storage and transportation tank 5 and an injection pipeline, a flowmeter I 2 and a carbon dioxide injection valve 3 are arranged on the injection pipeline, and the flowmeter I 2 and the carbon dioxide injection valve 3 are connected with a control terminal 1. The rapid cementing material injection system comprises a cementing material injection pump 8, a cementing material storage tank 9 and an injection pipeline, a flowmeter II 6 and a cementing material injection valve 7 are arranged on the injection pipeline, and the flowmeter II 6 and the cementing material injection valve 7 are connected with the control terminal 1.

[0031] From Figure 1 It can be seen that the geological layers from the surface downward are a near-surface rock stratum 10, an aquifer 11, a tight rock stratum 12, an upper coal seam 13, a parting 14 and a lower coal seam 15, wherein the upper coal seam 13, the parting 14 and the lower coal seam 15 are set as target reservoirs.

[0032] As Figure 2As shown, the main body of the multifunctional injection device 17 is arranged within the interbedded coal layer 14 in the target reservoir. A pinnate-shaped horizontal well is constructed within the interbedded coal layer 14. The main branch of the horizontal well extends horizontally along the interbedded coal layer 14, and the upper and lower branches extend at inclined angles into the upper coal seam 13 and lower coal seam 15. Multifunctional injection device 17 is deployed within the pinnate-shaped horizontal well. Multifunctional injection device 17 comprises an outer tube 17-1, an inner tube 17-2, and branch tubes 17-3. Outer tube 17-1 is arranged horizontally, inner tube 17-2 is located within outer tube 17-1 and also arranged horizontally. Branch tubes 17-3 are telescopic tubes that fold on both sides of outer tube 17-1. Each branch tube 17-3 is connected to outer tube 17-1 and is arranged within each branch of the pinnate-shaped horizontal well. At the ends of branch tube 17-3 and outer tube 17-1, energy-gathering chambers I17-4 are provided. Energy-discharging ports 17-5 are circumferentially arranged on the shell wall of energy-gathering chamber I17-4, and a delivery port 17-6 is located at the front end. Within energy-gathering chamber I17-4 at the end of outer tube 17-1, energy-gathering chamber II17-7 is located. Energy-gathering chamber II17-7 communicates with the end of inner tube 17-2. An energy-gathering chamber outlet is located at the front end of energy-gathering chamber II17-7, facing delivery port 17-6. The outlet of energy-gathering chamber II17-7 is equipped with an energy-gathering chamber outlet valve 17-10.

[0033] A branch magnetically controlled valve 17-9 is installed at the junction of outer tube 17-1 and branch tube 17-3. A main magnetically controlled valve 17-8 is installed between the end of outer tube 17-1 and energy-focusing chamber I 17-4. A flowmeter III 17-11 is also installed within energy-focusing chamber I 17-4. These branch magnetically controlled valves 17-9, main magnetically controlled valve 17-8, flowmeter III 17-11, and energy-focusing chamber outlet valve 17-10 are all connected to control terminal 1.

[0034] The lower end of the pipeline of the carbon dioxide injection system is connected to the outer pipe 17 - 1 of the multifunctional injection device 17 , and the lower end of the pipeline of the rapid gelling material injection system is connected to the inner pipe 17 - 2 of the multifunctional injection device 17 .

[0035] The present invention also discloses a method for synergistic carbon dioxide storage in a deep and close coal seam group, comprising the following steps:

[0036] S1. Select the target reservoir for feather-shaped branch horizontal well construction. The specific process is as follows:

[0037] First, determine the exact positions of the upper coal seam 13, the interbedded gangue layer 14 and the lower coal seam 15 in the deep and near coal seam group in the stratum, and construct a feather-shaped branch horizontal well from the ground through the near-surface rock layer 10, the aquifer 11, the dense rock layer 12 and the upper coal seam 13 to the coal seam group. The main branch of the horizontal well is located in the center of the interbedded gangue layer 14 and is constructed at the designed position along the direction of the interbedded gangue layer 14. The upper branch of the horizontal well is constructed to the roof of the upper coal seam with an inclination of no more than 45°, and the lower branch of the horizontal well is also constructed to the bottom of the lower coal seam with an inclination of no more than 45°. After completion, stop drilling.

[0038] S2. Deploy the carbon dioxide and rapid gelling material injection system. The specific process is as follows:

[0039] A multifunctional injection device 17 is inserted from the surface horizontal wellhead. Based on the actual construction orientation of the main branch and branches of the feather-shaped horizontal well, the main branch of the multifunctional injection device 17 is placed at the designed position within the main branch of the horizontal well. Branch pipes 17-3 on the multifunctional injection device 17 are deployed upon reaching the upper branch position of the horizontal well and extended into the upper branch to the interior of the upper coal seam 13. The lower branch of the multifunctional injection device 17 is deployed upon reaching the lower branch position of the horizontal well and extended into the lower branch to the interior of the lower coal seam 15. A packer 16 is placed between the upper coal seam 13 and the dense rock formation 12. The lower end of the CO2 injection system pipeline is connected to the outer pipe 17-1 of the multifunctional injection device 17, and the lower end of the rapid gelling system pipeline is connected to the inner pipe 17-2 of the multifunctional injection device 17, thus completing the pipeline connection between the CO2 injection system and the rapid gelling material injection system and the multifunctional injection system.

[0040] S3. Perform carbon dioxide fracturing and injection into the target reservoir. The specific process is as follows:

[0041] After confirming that the main magnetically controlled valve 17-8 and the energy-gathering chamber outlet valve 17-10 are closed, the carbon dioxide injection valve 3 is opened. Control terminal 1 is then used to control the opening of all branch magnetically controlled valves 17-9 and the main magnetically controlled valve 17-8. The carbon dioxide in the carbon dioxide storage tank 5 is heated and pressurized by the carbon dioxide injection pump 4, transforming it into supercritical carbon dioxide. This enters the energy-gathering chamber 117-4 of the multifunctional injection device 17 along the outer tube 17-1 at a pressure greater than that of the reservoir, causing the carbon dioxide to accumulate within the shell and generate a high pressure. Control terminal 1 is then used to control the opening of the energy release port 17-5. Due to the changes in pressure and temperature, the supercritical carbon dioxide undergoes a phase transition, rapidly fracturing the upper coal seam 13, the lower coal seam 15, and the interbedded coal layer 14.

[0042] After fracturing, the delivery port 17-6 is opened through the control terminal 1, and carbon dioxide is continuously injected into the reservoir through the energy release port 17-5 and the delivery port 17-6 at a constant pressure. The injection rate threshold is set, and the carbon dioxide injection amount and injection rate are monitored by the flow meter I2. When the injection rate of the outer pipe 17-1 or different branch pipes 17-3 continues to drop below the threshold, the main magnetic control valve 17-8 and the branch magnetic control valve 17-9 are closed. After all the magnetic control valves are closed, the carbon dioxide injection valve 3 is closed. The carbon dioxide injection steps of the upper coal seam 13, the interbedded gangue layer 14 and the lower coal seam 15 are completed.

[0043] S4. Rapidly inject gelling material into the target reservoir. The specific process is as follows:

[0044] The main magnetic control valve 17-8 is opened. After the rapid gelling material in the rapid gelling material storage tank 9 is increased in delivery pressure by the gelling material injection pump 8, it enters the energy-gathering chamber II 17-7 of the multi-functional injection device 17 main body along the inner tube 17-2 at a pressure greater than the reservoir pressure, so that the delivered rapid gelling material is gathered to increase the fluid pressure in the chamber. Then, the energy-gathering chamber outlet valve 17-10 is opened through the control terminal 1, and the rapid gelling material is rapidly ejected into the interbedded coal layer 14 through the energy discharge port 17-5 and the delivery port 17-6. After entering the interbedded coal layer 14, the rapid gelling material mixes with the carbon dioxide and the rocks of the interbedded coal layer 14 to form a negative carbon high-porosity filling material structure (CGIF). After the rapid gelling material is mixed with the carbon dioxide and the rocks of the interbedded coal layer 14 to form the CGIF, it can further solidify the carbon dioxide flowing in the interbedded coal layer 14 and the carbon dioxide escaping into the interbedded coal layer from the upper coal seam 13 and the lower coal seam 15.

[0045] Then, the rapid gelling material is continuously injected into the reservoir at a constant pressure, and the injection rate threshold is set. The injection amount and injection rate of the rapid gelling material are monitored by the flow meter III17-11. When the injection rate continues to drop below the threshold, the main magnetic control valve 17-8 and the energy-gathering cavity outlet valve 17-10 are closed, and the multifunctional injection device 17 is removed from the horizontal well to complete the coordinated storage of carbon dioxide in the target reservoir.

[0046] The present invention provides an energy release port 17-5 to release the pressure and energy of the accumulated high-pressure carbon dioxide or rapid gelling material, which on the one hand causes the coal seam and the interbedded gangue layer to crack, and on the other hand utilizes the kinetic energy after pressure relief to increase the injection distance of the carbon dioxide or rapid gelling material and accelerate the plume speed into the coal seam and the interbedded gangue layer.

[0047] Compared with the existing technology, the present invention can, on the one hand, use carbon dioxide to fracture the upper coal seam 13, the lower coal seam 15 and the interbedded gangue layer 14. After fracturing, carbon dioxide can be injected into the upper coal seam 13, the lower coal seam 15 and the interbedded gangue layer 14, and then a fast-setting material is injected into the interbedded gangue layer 14 to seal the carbon dioxide. At the same time, the fast-setting material can be consumed. The fast-setting material is made of coal-based solid waste (fly ash, etc.), and the solid waste can be recycled so that it does not pollute the environment.

[0048] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Various changes that can be made within the scope of knowledge possessed by technicians in the relevant technical field without departing from the spirit of the present invention are all within the scope of protection of the claims of the present invention.

Claims

1. An integrated system for the coordinated storage of carbon dioxide in deep and close coal seams, characterized by: include A carbon dioxide injection system is used for fracturing a target reservoir and injecting carbon dioxide into the target reservoir; the target reservoir is, from top to bottom, an upper coal seam (13), an interbedded gangue layer (14), and a lower coal seam (15); A rapid gelling material injection system is used to inject rapid gelling material into the interbedded gangue layer (14) to seal carbon dioxide; A multifunctional injection device (17) is arranged in a feather-shaped branch horizontal well in the interbedded gangue layer (14), and is used to cooperate with the carbon dioxide injection system and the rapid gelling material injection system to inject carbon dioxide and seal it; the multifunctional injection device (17) comprises an outer pipe (17-1), an inner pipe (17-2) and a branch pipe (17-3), the outer pipe (17-1) is arranged in the horizontal direction of the feather-shaped branch horizontal well, the inner pipe (17-2) is located inside the outer pipe (17-1) and is consistent with the extension direction of the outer pipe (17-1); the upper and lower branches of the feather-shaped branch horizontal well extend into the upper coal seam (13) and the lower coal seam (15) respectively; the branch pipe (17-3) is located in the upper and lower branches of the feather-shaped branch horizontal well and is connected to the outer pipe (17-2). (17-1) are integrally connected; the outer tube (17-1) is communicated with a carbon dioxide injection system, and the inner tube (17-2) is communicated with a rapid gelling material injection system; the ends of the outer tube (17-1) and the branch tube (17-3) are both provided with an energy-gathering cavity I (17-4), the energy-gathering cavity I (17-4) is provided with a plurality of energy discharge ports (17-5) along the circumferential direction, and a delivery port (17-6) is provided at the head; the end of the inner tube (17-2) is provided with an energy-gathering cavity II (17-7), the energy-gathering cavity II (17-7) is located inside the energy-gathering cavity I (17-4) at the end of the outer tube (17-1), and the outlet of the energy-gathering cavity II (17-7) is directed toward the delivery port (17-6) of the energy-gathering cavity I (17-4) at the end of the outer tube (17-1).

2. The integrated system for the coordinated storage of carbon dioxide in deep and close coal seams according to claim 1 is characterized in that: The carbon dioxide injection system comprises a carbon dioxide storage and transportation tank (5), a carbon dioxide injection pump (4), a carbon dioxide injection valve (3) and a flow meter I (2); the carbon dioxide storage and transportation tank (5) is connected to the carbon dioxide injection pump (4); the carbon dioxide injection valve (3) and the flow meter I (2) are located on a pipeline connecting the carbon dioxide injection pump (4) and the outer tube (17-1) of the multifunctional injection device (17).

3. The integrated system for the coordinated storage of carbon dioxide in deep and close coal seams according to claim 2 is characterized in that: The rapid gelling material injection system comprises a gelling material storage tank (9), a gelling material injection pump (8), a gelling material injection valve (7) and a flow meter II (6); the gelling material storage tank (9) is connected to the gelling material injection pump (8); the gelling material injection valve (7) and the flow meter II (6) are located on a pipeline between the gelling material injection pump (8) and the inner tube (17-2) of the multifunctional injection device (17).

4. The integrated system for the coordinated storage of carbon dioxide in deep and close coal seams according to claim 3 is characterized in that: A branch magnetic control valve (17-9) is provided at a position where the outer tube (17-1) is connected to the branch tube (17-3), and a main magnetic control valve (17-8) is provided between the outer tube (17-1) and the energy-gathering cavity I (17-4) at its end; the main magnetic control valve (17-8) and the branch magnetic control valve (17-9) are used to open and close the injection of carbon dioxide; and a flow meter III (17-11) is provided in the energy-gathering cavity I (17-4) of the outer tube (17-1) and the branch tube (17-3).

5. The integrated system for the coordinated storage of carbon dioxide in deep and close coal seams according to claim 4 is characterized in that: The system further comprises a control terminal (1), and the flowmeter I (2), the flowmeter II (6), the flowmeter III (17-11), the main magnetic control valve (17-8) and the branch magnetic control valve (17-9) are all connected to the control terminal (1).

6. The integrated system for the coordinated storage of carbon dioxide in deep and close coal seams according to claim 1 is characterized in that: It also includes a packer (16), which is installed at the air inlet end of the multifunctional injection device (17) to prevent carbon dioxide from flowing upward.

7. A method for the coordinated storage of carbon dioxide in a deep and close coal seam group, based on the coordinated storage integrated system according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Select the target reservoir for feather-shaped branch horizontal well construction, including: Step S11, determining the accurate positions of the upper coal seam (13), the interbedded gangue layer (14) and the lower coal seam (15) in the deep and close coal seam group in the stratum; Step S12, constructing a feather-shaped branch horizontal well from the ground through the near-surface rock layer (10), the aquifer (11), the dense rock layer (12) and the upper coal seam (13) to the coal seam group, wherein the main branch of the horizontal well is located at the center of the interbedded gangue layer (14) and is constructed along the direction of the interbedded gangue layer (14), the upper branch of the horizontal well is constructed to the top plate of the upper coal seam (13) at an inclination angle of no more than 45 degrees, and the lower branch of the horizontal well is constructed to the bottom plate of the lower coal seam (15) at an inclination angle of no more than 45 degrees, and the drilling work is stopped after completion; S2. Layout of carbon dioxide injection system and rapid gelling material injection system, including: Step S21: Extend the multifunctional injection device (17) from the surface horizontal wellhead, and according to the actual construction orientation of the main branch and the branch of the feather-shaped branch horizontal well, place the outer pipe (17-1) and the inner pipe (17-2) of the multifunctional injection device (17) into the designed position in the main branch of the horizontal well, and place the branch pipe (17-3) into the branch of the horizontal well; Step S22: Connect the lower end of the injection pipeline of the carbon dioxide injection system to the outer pipe (17-1), and connect the lower end of the injection pipeline of the rapid gelling material injection system to the inner pipe (17-2); S3. Perform carbon dioxide fracturing and injection into the target reservoir, specifically including: Step S31: The carbon dioxide in the carbon dioxide storage tank (5) is heated and pressurized by the carbon dioxide injection pump (4) to be converted into supercritical carbon dioxide, and injected into the outer tube (17-1) at a pressure greater than that of the target reservoir. The carbon dioxide energy release port (17-5) on the side wall of the energy-gathering chamber I (17-4) is opened by the control terminal (1). The supercritical carbon dioxide undergoes a phase transition due to changes in pressure and temperature, thereby fracturing the upper coal seam (13), the lower coal seam (15), and the interbedded coal layer (14). Step S32: After fracturing, the delivery port (17-6) at the front end of the energy-gathering chamber I (17-4) is controlled to open, and carbon dioxide is continuously injected into the reservoir through the energy-releasing port (17-5) and the delivery port (17-6) at a constant pressure. An injection rate threshold is set, and the carbon dioxide injection amount and injection rate are monitored. When the injection rate continuously decreases below the threshold, the carbon dioxide injection into the target reservoir is completed. S4. Rapidly injecting gelling materials into the target reservoir, specifically including: Step S41, after the rapid gelling material in the gelling material storage tank (9) is increased in delivery pressure by the gelling material injection pump (8), it enters the energy-gathering chamber II (17-7) along the inner tube (17-2) at a pressure greater than the reservoir pressure, and the gelling material is rapidly ejected into the interbedded gangue layer (14) through the energy discharge port (17-5) and the delivery port (17-6) of the energy-gathering chamber I (17-4) at the end of the outer tube (17-1). After entering the interbedded gangue layer (14), the gelling material is mixed with carbon dioxide and the rocks of the interbedded gangue layer (14) to form a negative carbon high-porosity filling material structure, so as to solidify the carbon dioxide flowing in the interbedded gangue layer (14) and the carbon dioxide escaping from the upper coal seam (13) and the lower coal seam (15) into the interbedded gangue layer (14); Step S42: continuously injecting fast-setting material into the reservoir at a constant pressure, setting an injection rate threshold, monitoring the injection amount and injection rate of the gelling material, and when the injection rate continuously decreases below the threshold, removing the multifunctional injection device (17) from the horizontal well to complete the carbon dioxide coordinated storage work in the target reservoir.

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