Coal seam gas injection displacement gas closed-loop optimization device and method based on production increase characteristic points

Abstract

The present invention discloses a closed-loop optimization device and method for coal seam gas injection to displace gas based on production increase characteristic points. The method first pressurizes part of the nitrogen into the displacement gas storage tank, and after the CO2 tank group replenishes the CO2 in the storage tank to a preset concentration, a binary mixed gas is injected into the coal seam at a preset pressure to displace the gas; the data collector records the pure gas flow in the gas extraction pipeline in real time, and generates the actual production increase curve through the integrated terminal and determines the starting, breakthrough and failure points; a numerical model is constructed according to the gas geological conditions, and the parameters are adjusted until the production increase curve calculated by the model matches the characteristic points of the actual production increase curve; the maximum gas production increase efficiency is used as the optimization criterion, and the theoretical optimal gas injection pressure and CO2 concentration are determined in combination with the response surface method; the gas injection parameters are changed, and the above steps are repeated until the actual production increase efficiency is lower than the threshold. The present invention performs closed-loop optimization through the production increase characteristic points of the coal seam gas injection production increase process, which helps to achieve accurate prevention and control of regional gas and efficient development.

Description

Technical Field

[0001] The present invention belongs to the field of efficient management and precise extraction of coal mine gas resources, and in particular to a coal seam gas injection and displacement gas closed-loop optimization device and method based on production increase characteristic points. Background Art

[0002] At present, the efficiency of increasing gas production in coal seam gas injection displacement areas is mainly achieved by changing the construction parameters of gas injection drilling and extraction drilling (borehole diameter, borehole spacing and number of boreholes, etc.). However, in actual production, there is a great deal of subjectivity in optimizing the gas production efficiency of the gas injection process by changing the drilling construction parameters. Although the gas production efficiency of the gas injection process can be improved by increasing the drilling construction density or increasing the borehole diameter, it also leads to a significant increase in the risk of gas injection short circuit in the coal reservoir. In addition, the initial gas pressure, permeability coefficient and adsorption characteristics of coal reservoirs in different regions are significantly different, resulting in a great deal of randomness in the selection of process parameters such as binary (CO2-N2) mixed gas ratio and gas injection pressure. In particular, during the gas injection production increase process, the reservoir parameters change in real time, and the optimal mixed gas ratio and gas injection pressure change at the same time. The optimization of on-site gas injection production increase process parameters has become the main bottleneck of gas injection production increase efficiency. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a coal seam gas injection displacement closed-loop optimization device and method based on production increase characteristic points. Based on the production increase characteristic points in a closed-loop optimization manner, according to the closed-loop mutual feedback of the on-site real-time production increase results and the numerical calculation results, the dynamic optimization of the regional gas injection production increase process parameters is realized, thereby improving the regional gas production increase effect.

[0004] The present invention adopts the following technical solutions to solve the above technical problems:

[0005] The invention provides a coal seam gas injection displacement gas closed-loop optimization device based on production increase characteristic points, comprising a construction drilling module, a displacement gas premixing module and a gas injection enhanced extraction module.

[0006] The construction drilling module is used to construct a first gas extraction borehole, a gas injection borehole and a second gas extraction borehole toward the coal reservoir through a floor gas management tunnel.

[0007] The displacement gas premixing module is used to prepare and store binary mixed gas, including a nitrogen injection pipeline, a booster pump, a first stop valve, a data collector, a displacement gas storage tank, an integrated terminal, a first pressure reducing valve, a CO2 gas tank group and a vent valve.

[0008] The gas injection enhanced extraction module is used to inject binary mixed gas into the coal seam and increase gas production by injecting and extracting at the same time, and includes a second pressure reducing valve, a one-way valve, a second stop valve, a third stop valve, a fourth stop valve, a drainage pump, and a gas drainage pipeline.

[0009] Furthermore, in the construction drilling module, the gas injection borehole is located between the first gas extraction borehole and the second gas extraction borehole; the drilling distance between the gas injection borehole and the first gas extraction borehole and the second gas extraction borehole is equal, ranging from 5 to 10m, and the drilling diameter range of the gas injection borehole, the first gas extraction borehole and the second gas extraction borehole is 0.1 to 1.6m.

[0010] Furthermore, in the displacement gas premixing module, the nitrogen injection pipeline is connected to one end of the booster pump; the other end of the booster pump is connected to one end of the first stop valve; the other end of the first stop valve is respectively connected to one end of the second pressure reducing valve and one end of the displacement gas storage tank; one end of the vent valve is connected to one end of the displacement gas storage tank, and the other end is connected to the atmosphere; one end of the data acquisition device is connected to one end of the integrated terminal, and the other end is connected to one end of the displacement gas storage tank; the other end of the integrated terminal is connected to one end of the displacement gas storage tank; one end of the first pressure reducing valve is connected to one end of the displacement gas storage tank, and the other end is connected to one end of the CO2 gas tank group.

[0011] Furthermore, in the gas injection enhanced extraction module, one end of the second pressure reducing valve is respectively connected to one end of the first stop valve and one end of the displacement gas storage tank, and the other end is connected to one end of the one-way valve; the other end of the one-way valve is connected to one end of the second stop valve, and the other end of the second stop valve is respectively connected to the gas injection borehole and one end of the third stop valve; the other end of the third stop valve, the first gas extraction borehole, and the second gas extraction borehole are respectively connected to one end of the fourth stop valve; the other end of the fourth stop valve is connected to one end of the extraction pump; and the other end of the extraction pump is connected to the gas extraction pipeline.

[0012] Furthermore, the present invention also proposes a closed-loop optimization method for coal seam gas injection displacement gas based on production increase characteristic points, comprising the following steps:

[0013] S1. Construct the first gas extraction borehole, the gas injection borehole and the second gas extraction borehole through the bottom gas control tunnel to the coal reservoir, wherein the gas injection borehole is located between the first gas extraction borehole and the second gas extraction borehole; the borehole spacing between the gas injection borehole and the first gas extraction borehole and the second gas extraction borehole is equal, ranging from 5 to 10m, and the borehole diameters of the gas injection borehole, the first gas extraction borehole and the second gas extraction borehole are in the range of 0.1 to 1.6m, so as to avoid the displacement gas from quickly breaking through the reservoir and causing direct failure of production increase.

[0014] S2. Close the second stop valve, open the third and fourth stop valves, and start the gas extraction pump of the gas extraction pipeline to pre-extract gas from the coal reservoir until the pure gas flow in the gas extraction pipeline is less than 0.01 m 3 / min.

[0015] S3. After opening the vent valve to release the residual gas pressure in the displacement gas storage tank, close the vent valve; open the booster pump and the first stop valve of the nitrogen injection pipeline to pressurize and store part of the nitrogen in the displacement gas storage tank for standby use. When the nitrogen pressure in the displacement gas storage tank reaches the initial gas pressure, close the booster pump and the first stop valve.

[0016] S4. Regulate the first pressure reducing valve at the outlet of the CO2 gas tank group to inject CO2 into the displacement gas storage tank. When the CO2 in the storage tank reaches the preset concentration, close the first pressure reducing valve; open the second stop valve, close the third stop valve, and regulate the second pressure reducing valve to the preset gas injection pressure to inject the binary mixed gas into the coal reservoir to displace the gas.

[0017] S5. The data collector records the pure gas flow in the gas extraction pipeline in real time. When the gas injection production increase in the area fails, the second stop valve and the fourth stop valve are immediately closed.

[0018] S6. The integrated terminal receives the real-time pure gas flow in the data collector to generate the actual production increase curve, and determines the production increase characteristic points of the actual production increase curve, including the starting point Breakthrough point and failure point .

[0019] in, Indicates the start time, represents the initial flow rate, Indicates the breakthrough time of the actual production increase curve. The peak flow rate of the actual production increase curve, indicating the breakthrough point, The failure time represents the failure point of the actual production increase curve.

[0020] S7. According to the gas geological conditions, the initial gas pressure and initial coal permeability are adjusted based on the COMSOL Multiphysics numerical simulation until the breakthrough point of the increase curve calculated by the gas injection increase numerical model is reached. and failure point Breakthrough point with actual production increase curve Failure point Match.

[0021] in, Indicates the breakthrough time of the breakthrough point of the calculation of the yield increase curve, Indicates the breakthrough time of the failure point of the calculated production increase curve, Indicates the peak flow rate of the calculated breakthrough point of the production increase curve.

[0022] S8. Taking the maximum gas production increase efficiency as the optimization criterion, the response surface analysis method is combined to determine the optimal gas injection pressure and optimal CO2 concentration corresponding to the maximum gas production increase efficiency, and the preset concentration and the preset gas injection pressure are adjusted to the optimal gas injection pressure and the optimal CO2 concentration respectively.

[0023] S9. Repeat steps S2-S8 until the gas production increase efficiency is lower than the preset threshold for three consecutive times, and maximize the regional gas production increase by calculating the production increase curve and the actual production increase curve in a closed-loop optimization manner.

[0024] Furthermore, in step S7, the calculation basis for matching characteristic points of the production increase curve with the actual production increase curve is as follows:

[0025] ;

[0026] in, is the absolute error limit, ; is the relative error limit, .

[0027] Furthermore, in step S8, the gas production increase efficiency expression is:

[0028] ;

[0029] in, Indicates the gas production efficiency, Indicates the preset gas injection pressure. Indicates CO2 concentration, Indicates the expiration time, It indicates the gas production increase per unit volume of coal. and is the adsorption constant, represents the coal porosity, Indicates the initial gas pressure, represents the density of coal, Indicates a unit conversion factor.

[0030] Furthermore, the preset threshold value of the gas production increase efficiency in step S9 is 1-5%.

[0031] Furthermore, the present invention also proposes an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the coal seam gas injection and gas displacement closed-loop optimization method based on increased production characteristic points are implemented as described above.

[0032] Furthermore, the present invention also proposes a computer-readable storage medium, which stores a computer program. When the computer program is run by a processor, it executes the steps of the coal seam gas injection and gas displacement closed-loop optimization method based on production increase feature points as described above.

[0033] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0034] (1) Based on the characteristics of the production increase curve of coal seam injection of binary mixed gas to displace gas, the model calculation production increase curve is matched with the actual production increase curve on site through the production increase characteristic points (initial point, breakthrough point and failure point), overcoming the blindness and randomness of using gas production increase as the basis for matching. It effectively improves the matching efficiency of the numerical model parameters for gas injection production increase, and ensures the rationality and accuracy of the selection of the numerical model parameters for gas injection production increase;

[0035] (2) Based on the increase in production characteristic points of the increase in production curve, the closed-loop feedback between the on-site real-time increase in production results and the numerical calculation results is realized, and the dynamic optimization of the regional gas injection increase in production process parameters is realized through the response surface method. This overcomes the problem of random changes in the optimal gas injection process parameters caused by the dynamic evolution of reservoir parameters during the gas injection increase in production process, and effectively improves the gas increase in production under complex coal seam conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the coal seam gas injection and gas displacement closed-loop optimization device based on the production increase characteristic points of the present invention.

[0037] Figure 2 It is a schematic diagram of the process of approximating and matching characteristic points between the actual production increase curve of the present invention and the production increase curve calculated by the model.

[0038] In the figure: 1-coal reservoir, 2-first gas extraction borehole, 3-gas injection borehole, 4-second gas extraction borehole, 5-nitrogen injection pipeline, 6-boosting pump, 7-first stop valve, 8-data collector, 9-displacement gas storage tank, 10-integrated terminal, 11-first pressure reducing valve, 12-CO2 gas tank group, 13-second pressure reducing valve, 14-check valve, 15-vent valve, 16-second stop valve, 17-third stop valve, 18-fourth stop valve, 19-extraction pump, 20-gas extraction pipeline. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The coal seam gas injection displacement gas closed-loop optimization device based on the production increase characteristic point proposed by the present invention is as follows: Figure 1 As shown, it includes a construction drilling module, a displacement gas premixing module and a gas injection enhanced extraction module.

[0041] The construction drilling module is used to construct a first gas extraction borehole 2, a gas injection borehole 3 and a second gas extraction borehole 4 toward the coal reservoir 1 through a floor gas control tunnel.

[0042] The displacement gas premixing module is used to prepare and store binary mixed gas, including a nitrogen injection pipeline 5, a booster pump 6, a first stop valve 7, a data acquisition device 8, a displacement gas storage tank 9, an integrated terminal 10, a first pressure reducing valve 11, a CO2 gas tank group 12 and a vent valve 15.

[0043] The gas injection enhanced extraction module is used to inject binary mixed gas into the coal seam and increase gas production by injecting and extracting at the same time, and includes a second pressure reducing valve 13, a one-way valve 14, a second stop valve 16, a third stop valve 17, a fourth stop valve 18, a drainage pump 19, and a gas drainage pipeline 20.

[0044] In the construction drilling module, the gas injection borehole 3 is located between the first gas extraction borehole 2 and the second gas extraction borehole 4; the drilling distance between the gas injection borehole 3 and the first gas extraction borehole 2 and the second gas extraction borehole 4 is equal, ranging from 5 to 10m, and the drilling diameter range of the gas injection borehole 3, the first gas extraction borehole 2 and the second gas extraction borehole 4 is 0.1 to 1.6m.

[0045] In the displacement gas premixing module, the nitrogen injection pipeline 5 is connected to one end of the booster pump 6; the other end of the booster pump 6 is connected to one end of the first stop valve 7; the other end of the first stop valve 7 is respectively connected to one end of the second pressure reducing valve 13 and one end of the displacement gas storage tank 9; one end of the vent valve 15 is connected to one end of the displacement gas storage tank 9, and the other end is connected to the atmosphere; one end of the data acquisition device 8 is connected to one end of the integrated terminal 10, and the other end is connected to one end of the displacement gas storage tank 9; the other end of the integrated terminal 10 is connected to one end of the displacement gas storage tank 9; one end of the first pressure reducing valve 11 is connected to one end of the displacement gas storage tank 9, and the other end is connected to one end of the CO2 gas tank group 12.

[0046] In the gas injection enhanced extraction module, one end of the second pressure reducing valve 13 is respectively connected to one end of the first stop valve 7 and one end of the displacement gas storage tank 9, and the other end is connected to one end of the one-way valve 14; the other end of the one-way valve 14 is connected to one end of the second stop valve 16, and the other end of the second stop valve 16 is respectively connected to the gas injection borehole 3 and one end of the third stop valve 17; the other end of the third stop valve 17, the first gas extraction borehole 2, and the second gas extraction borehole 4 are respectively connected to one end of the fourth stop valve 18; the other end of the fourth stop valve 18 is connected to one end of the extraction pump 19; the other end of the extraction pump 19 is connected to the gas extraction pipeline 20.

[0047] In this example, a working face of Chen Silou Coal Mine in Yongcheng City, Henan Province is used as the background. The average thickness of the coal seam is 6m. According to the gas parameter measurement results, the average gas pressure of the coal seam is 1.8MPa, and the average gas content is 11.8 m 3 / t.

[0048] The present invention also proposes a coal seam gas injection and gas displacement closed-loop optimization method based on production increase characteristic points, comprising the following steps:

[0049] S1. Construct the first gas extraction borehole, gas injection borehole and second gas extraction borehole through the bottom plate gas control tunnel to the bottom plate rock tunnel, wherein the gas injection borehole is located between the first gas extraction borehole and the second gas extraction borehole; the borehole spacing between the gas injection borehole and the first gas extraction borehole and the second gas extraction borehole is equal to 10m, and the borehole diameters of the gas injection borehole, the first gas extraction borehole and the second gas extraction borehole are 1.0m to avoid the displacement gas from quickly breaking through the reservoir and causing direct failure of production increase.

[0050] S2. Close the second stop valve, open the third and fourth stop valves, and start the gas extraction pump of the gas extraction pipeline to pre-extract gas from the coal reservoir until the pure gas flow in the gas extraction pipeline is less than 0.01 m 3 / min.

[0051] S3. After opening the vent valve to release the residual gas pressure in the displacement gas storage tank, close the vent valve. Open the booster pump and the first stop valve of the nitrogen injection pipeline to pressurize and store part of the nitrogen in the displacement gas storage tank for standby use. When the nitrogen pressure in the displacement gas storage tank reaches the initial gas pressure, close the booster pump and the first stop valve.

[0052] S4. Adjust the first pressure reducing valve at the outlet of the CO2 gas tank group to inject CO2 into the displacement gas storage tank. When the CO2 in the storage tank reaches the preset concentration, close the first pressure reducing valve. Open the second stop valve, close the third stop valve, and adjust the second pressure reducing valve to the preset gas injection pressure to inject binary mixed gas into the coal reservoir to displace the gas.

[0053] During the initial production increase, the preset concentration of CO2 in the displacement gas storage tank is 50%, and the preset injection pressure satisfies:

[0054] ;

[0055] in, Indicates the preset gas injection pressure. Indicates the initial gas pressure.

[0056] S5. The data collector records the pure gas flow in the gas extraction pipeline in real time. When the gas injection production increase in the area fails, the second stop valve and the fourth stop valve are immediately closed.

[0057] S6. The integrated terminal receives the real-time pure gas flow in the data collector to generate the actual production increase curve, and determines the production increase characteristic points of the actual production increase curve, including the starting point Breakthrough point and failure point .

[0058] The starting point is the starting point of the production increase curve, the breakthrough point is the point where the pure flow of the production increase curve begins to decrease, and the failure point is the point where the pure flow of the production increase curve decreases to the initial gas pure flow.

[0059] in, Indicates the start time, represents the initial flow rate, Indicates the breakthrough time of the actual production increase curve. The peak flow rate of the actual production increase curve, indicating the breakthrough point, The failure time represents the failure point of the actual production increase curve.

[0060] S7. According to the gas geological conditions, the initial gas pressure and initial coal permeability are adjusted based on COMSOL Multiphysics numerical simulation until the breakthrough point of the calculation increase curve of the gas injection increase production numerical model is reached. and failure point Breakthrough point with actual production increase curve Failure point Match.

[0061] in, Indicates the breakthrough time of the breakthrough point of the calculation of the yield increase curve, Indicates the breakthrough time of the failure point of the calculated production increase curve, Indicates the peak flow rate of the calculated breakthrough point of the production increase curve.

[0062] The basis for matching the characteristic points of the calculated production increase curve and the actual production increase curve is as follows:

[0063] ;

[0064] in, is the absolute error limit, ; is the relative error limit, .

[0065] The characteristic value matching results of the characteristic points of the production increase curve calculated by the gas injection production increase numerical model based on the actual process parameters at different optimization times and the actual production increase curve are shown in Table 1. Among them, the single closed-loop production increase optimization process includes the gas production increase curve matching process. Figure 2 As shown in the figure, during the adjustment of the parameters of the gas injection production increase model, the breakthrough point and failure point of the model production increase curve gradually approach the breakthrough point and failure point of the actual production increase curve until the matching criteria are met, indicating that the matching process of the single closed-loop optimization process is completed.

[0066] Table 1 Matching results of characteristic points of production increase curve in optimization process

[0067] Optimization times Actual breakthrough time / (d) Model breakthrough time / (d) Actual failure time / (d) Model failure time / (d) <![CDATA[Model increased production peak flow rate / (m 3 / min)]]> <![CDATA[Actual peak flow rate of increased production / (m 3 / min)]]> 1 5.2 5.5 18.6 19.0 0.096 0.089 2 12.3 12.1 25.6 26.1 0.152 0.150 3 12.0 12.5 22.1 22.0 0.148 0.152 4 10.3 10.0 19.5 20.0 0.128 0.133 5 8.2 8.8 15.0 15.2 0.113 0.120 6 5.5 5.0 8.2 8.5 0.085 0.081 7 3.0 3.8 5.1 5.0 0.042 0.039 8 2.1 2.0 4.8 5.2 0.031 0.030 9 2.0 1.9 3.1 3.2 0.015 0.019 10 2.0 2.2 3.1 2.9 0.012 0.008

[0068] S8. Taking the maximum gas production increase efficiency as the optimization criterion, the response surface analysis method is combined to determine the optimal gas injection pressure and the optimal CO2 concentration corresponding to the maximum gas production increase efficiency, and the preset concentration and the preset gas injection pressure are adjusted to the optimal gas injection pressure and the optimal CO2 concentration respectively.

[0069] The expression of gas production increase efficiency is:

[0070] ;

[0071] in, Indicates the gas production efficiency, Indicates the preset gas injection pressure. Indicates CO2 concentration, Indicates the expiration time, It indicates the gas production increase per unit volume of coal. and is the adsorption constant, represents the coal porosity, Indicates the initial gas pressure, represents the density of coal, Indicates a unit conversion factor.

[0072] S9, repeat steps S2-S8 until the gas production efficiency is lower than the preset threshold for three consecutive times, and maximize the regional gas production by calculating the production increase curve and the actual production increase curve in a closed-loop optimization manner. The preset threshold of the gas production efficiency is 5%, and the actual gas production efficiency, the theoretical optimal gas production efficiency, and the changes in the injection pressure CO2 concentration are shown in Table 2.

[0073] Table 2 Parameter changes of coal seam gas injection closed-loop optimization process based on production increase characteristic points

[0074] Optimization times Actual gas production increase efficiency / (%) Theoretical optimal gas production efficiency / (%) Preset gas injection pressure / (MPa) <![CDATA[CO2 concentration / (%)]]> 1 10.25 21.13 0.6 0 2 63.12 80.91 1.6 55 3 60.09 73.23 1.2 65 4 49.17 60.85 1.2 50 5 30.19 45.94 0.6 60 6 20.18 39.08 0.6 65 7 9.37 15.16 0.6 85 8 4.05 10.16 0.4 100 9 2.85 8.14 0.2 100 10 1.28 5.31 0.2 100

[0075] In order to further demonstrate the actual optimization effect of the method proposed in the present invention, a group of boreholes is also constructed in the area adjacent to the coal reservoir, but the borehole spacing is set to 5m.

[0076] In addition, through on-site sampling and testing of gas content, it was found that the average residual gas content of the regional coal reservoir was 9.2m 3 / t. However, when the coal seam gas injection closed-loop optimization method based on the production increase characteristic points of this application is adopted, the average residual gas content of the regional coal reservoir is only 5.3 m 3 / t, which is much lower than the residual gas content of the existing method of optimizing gas injection production efficiency by reducing the borehole spacing. The above results show that the method proposed by the present invention has better optimization effect and is more suitable for gas injection displacement gas production increase under complex geological conditions in actual production.

[0077] The present invention also proposes an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of the coal seam gas injection and gas displacement closed-loop optimization method based on production increase characteristic points described above are implemented.

[0078] The present invention also proposes a computer-readable storage medium, which stores a computer program. When the computer program is run by a processor, it executes the steps of the coal seam gas injection and gas displacement closed-loop optimization method based on production increase feature points as described above.

[0079] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A closed-loop optimization method for gas displacement by coal seam gas injection based on production increase characteristic points, characterized in that: The following steps are involved: S1. Constructing a first gas extraction borehole, a gas injection borehole and a second gas extraction borehole through a floor gas control tunnel toward the coal reservoir, wherein the gas injection borehole is located between the first gas extraction borehole and the second gas extraction borehole; and the borehole spacing between the gas injection borehole and the first gas extraction borehole and the second gas extraction borehole is equal; S2. Close the second stop valve, open the third and fourth stop valves, and start the gas extraction pump of the gas extraction pipeline to pre-extract gas from the coal reservoir until the pure gas flow in the gas extraction pipeline is less than 0.01 m 3 / min; S3, after opening the vent valve to release the residual gas pressure in the displacement gas storage tank, close the vent valve; open the booster pump and the first stop valve of the nitrogen injection pipeline, pressurize and store part of the nitrogen in the displacement gas storage tank for standby use, and when the nitrogen pressure in the displacement gas storage tank reaches the initial gas pressure, close the booster pump and the first stop valve; S4, adjust the first pressure reducing valve at the outlet of the CO2 gas tank group to inject CO2 into the displacement gas storage tank, and when the CO2 in the storage tank reaches the preset concentration, close the first pressure reducing valve; open the second stop valve, close the third stop valve, adjust the second pressure reducing valve to the preset gas injection pressure to inject the binary mixed gas into the coal reservoir to displace the gas; S5. The data collector records the pure gas flow in the gas extraction pipeline in real time. When the gas injection production increase in the area fails, the second stop valve and the fourth stop valve are immediately closed; S6. The integrated terminal receives the real-time pure gas flow in the data collector to generate the actual production increase curve, and determines the production increase characteristic points of the actual production increase curve, including the starting point Breakthrough point and failure point ; in, Indicates the start time, represents the initial flow rate, Indicates the breakthrough time of the actual production increase curve. The peak flow rate of the actual production increase curve, indicating the breakthrough point, The failure time representing the failure point of the actual production increase curve; S7. According to the gas geological conditions, simulate and adjust the initial gas pressure and initial coal permeability until the breakthrough point of the production increase curve calculated by the gas injection production increase numerical model is reached. and failure point Breakthrough point with actual production increase curve Failure point Match; in, Indicates the breakthrough time of the breakthrough point of the calculation of the yield increase curve, Indicates the breakthrough time of the failure point of the calculated production increase curve, Indicates the peak flow rate of the calculated breakthrough point of the production increase curve; S8. Determine the optimal gas injection pressure and optimal CO2 concentration corresponding to the maximum gas production increase efficiency by combining the response surface analysis method, and adjust the preset concentration and the preset gas injection pressure to the optimal gas injection pressure and optimal CO2 concentration respectively; S9, repeating steps S2-S8 until the gas production increase efficiency is lower than the preset threshold for three consecutive times, and the calculated production increase curve and the actual production increase curve are optimized in a closed-loop manner.

2. The closed-loop optimization method for coal seam gas injection displacement gas based on production increase characteristic points according to claim 1, characterized in that: In step S4, the preset concentration of CO2 in the displacement gas storage tank during the initial production increase is 50%, and the preset gas injection pressure satisfies: ； in, Indicates the preset gas injection pressure. Indicates the initial gas pressure.

3. The closed-loop optimization method for coal seam gas injection displacement gas based on production increase characteristic points according to claim 1, characterized in that: In the steps S6 and S7, the starting point is the starting point of the production increase curve, the breakthrough point is the point where the pure flow of the production increase curve begins to decrease, and the failure point is the point where the pure flow of the production increase curve decreases to the initial gas pure flow.

4. The closed-loop optimization method for coal seam gas injection displacement gas based on production increase characteristic points according to claim 1, characterized in that: In step S7, the calculation basis for matching the characteristic points of the production increase curve with the actual production increase curve is as follows: ； in, is the absolute error limit, is the relative error limit.

5. The closed-loop optimization method for coal seam gas injection displacement gas based on production increase characteristic points according to claim 1, characterized in that: In step S8, the gas production increase efficiency expression is: ； in, Indicates the gas production efficiency, Indicates the preset gas injection pressure. Indicates CO2 concentration, Indicates the expiration time, It indicates the gas production increase per unit volume of coal. and is the adsorption constant, represents the coal porosity, Indicates the initial gas pressure, represents the density of coal, Indicates a unit conversion factor.

6. The closed-loop optimization method for coal seam gas injection displacement gas based on production increase characteristic points according to claim 1, characterized in that: In step S9, the preset threshold range of the gas production increase efficiency is 1-5%.

7. The device applied to the closed-loop optimization method of coal seam gas injection displacement gas based on production increase characteristic points as claimed in claim 1, characterized in that: It includes construction drilling module, displacement gas premixing module and gas injection enhanced extraction module; The construction drilling module is used to construct a first gas extraction borehole (2), a gas injection borehole (3) and a second gas extraction borehole (4) toward the coal reservoir (1) through a floor gas management tunnel; the gas injection borehole (3) is located between the first gas extraction borehole (2) and the second gas extraction borehole (4); The displacement gas premixing module is used to prepare and store binary mixed gas, and comprises a nitrogen injection pipeline (5), a booster pump (6), a first stop valve (7), a data acquisition device (8), a displacement gas storage tank (9), an integrated terminal (10), a first pressure reducing valve (11), a CO2 gas tank group (12) and a vent valve (15); The nitrogen injection pipeline (5) is connected to one end of the booster pump (6); the other end of the booster pump (6) is connected to one end of the first stop valve (7); the other end of the first stop valve (7) is respectively connected to one end of the second pressure reducing valve (13) and one end of the displacement gas storage tank (9); one end of the vent valve (15) is connected to one end of the displacement gas storage tank (9), and the other end is connected to the atmosphere; one end of the data acquisition device (8) is connected to one end of the integrated terminal (10), and the other end is connected to one end of the displacement gas storage tank (9); the other end of the integrated terminal (10) is connected to one end of the displacement gas storage tank (9); one end of the first pressure reducing valve (11) is connected to one end of the displacement gas storage tank (9), and the other end is connected to one end of the CO2 gas tank group (12); The gas injection enhanced extraction module is used to inject binary mixed gas into the coal seam, and comprises a second pressure reducing valve (13), a one-way valve (14), a second stop valve (16), a third stop valve (17), a fourth stop valve (18), an extraction pump (19), and a gas extraction pipeline (20); One end of the second pressure reducing valve (13) is respectively connected to one end of the first stop valve (7) and one end of the displacement gas storage tank (9), and the other end is connected to one end of the one-way valve (14); the other end of the one-way valve (14) is connected to one end of the second stop valve (16), and the other end of the second stop valve (16) is respectively connected to the gas injection borehole (3) and one end of the third stop valve (17); the other end of the third stop valve (17), the first gas extraction borehole (2), and the second gas extraction borehole (4) are respectively connected to one end of the fourth stop valve (18); the other end of the fourth stop valve (18) is connected to one end of the extraction pump (19); and the other end of the extraction pump (19) is connected to the gas extraction pipeline (20).

8. The device for the closed-loop optimization method of coal seam gas injection displacement gas based on production increase characteristic points according to claim 7, characterized in that: In the construction drilling module, the borehole spacing between the gas injection borehole (3) and the first gas extraction borehole (2) and the second gas extraction borehole (4) is equal, ranging from 5 to 10 m, and the borehole diameters of the gas injection borehole (3), the first gas extraction borehole (2) and the second gas extraction borehole (4) are in the range of 0.1 to 1.6 m.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method according to any one of claims 1 to 6 is performed.

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