Coal bed gas ground well gas production and heat exchange mutual promotion synergy device and method

Abstract

The invention discloses a coal bed gas ground well gas production and heat exchange mutual promotion synergistic device and method, and relates to the technical field of coal bed gas exploitation. The water inlet end of a vertical water pump is connected with a drainage vertical pipe, the drainage vertical pipe is installed in a drainage vertical well, and a filter is arranged at the bottom end of the drainage vertical pipe; a water outlet end of the vertical water pump is connected with an evaporator end water inlet of the heat pump unit, and an evaporator end water outlet of the heat pump unit is connected with a recharge connector arranged at the top of the vertical well section of the horizontal well; the water temperature sensor is arranged at the water outlet end of the vertical water suction pump; a gas inlet of the gas extraction pump is connected with an extraction connector in the top of the drainage vertical well, and the extraction monitoring sensor is arranged at the gas inlet of the gas extraction pump. Through the intermittent circulation heat exchange process method, the coal seam temperature field is changed, the coal seam permeability and the gas desorption capacity are improved, and the problem that the gas production rate is low in the middle and later periods of ground well drainage production is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of coalbed methane exploitation, and in particular to a device and method for enhancing the efficiency of heat exchange and gas extraction in a coalbed methane surface well. Background Art

[0002] Surface well mining technology is a common means of pre-extraction of coalbed methane and prevention of gas disasters. With the development and progress of drilling and completion, fracturing transformation, directional drilling and other technologies, my country has established a mature coalbed methane surface well development technology system, including surface vertical wells, cluster wells, U-shaped wells, L-shaped wells, etc., and is widely used in coal mining areas. Coalbed methane surface well drainage and production usually go through four stages: drainage and pressure reduction, stable production, production decline and exhaustion. The gas production capacity in the middle and late stages of drainage and production is key to the efficiency of surface well mining; however, there is a lack of technical means to improve the gas production capacity at this stage, which leads to the premature expiration of the service life of the surface well project, which not only wastes engineering resources, but also reduces the effect of coalbed methane extraction.

[0003] Existing studies have shown that coal permeability and gas desorption capacity are important factors affecting coalbed methane production, and temperature under high stress conditions has a significant impact on coal permeability and gas desorption capacity. Therefore, the output of surface wells can be improved by controlling the temperature of the coal seam. Heat pump technology has been maturely applied in the utilization of medium and deep geothermal energy in my country. It can extract underground heat and change the underground temperature field through coaxial casing, underground water recharge and other processes. Therefore, the gas production of surface wells can be increased by changing the geothermal field through heat exchange in surface wells. Application publication number CN 117905421 A proposes an integrated method for deep coal seam non-tunnel gas extraction and deep geothermal resource exploitation. Based on the U-shaped well constructed in the coal seam, through double-layer casing gas and heat separation mining, deep coal seam gas extraction and deep geothermal resource mining are realized, but it does not involve the improvement of the development effect of the two resources by gas and heat extraction process methods, and the problem of production reduction in the middle and late stages of U-shaped well drainage is still unsolved. Since the increase of coalbed methane output will reduce the gas content of coal seams, and the reduction of gas content will reduce the thermal resistance of coal rock mass, the thermal conductivity of coal seams will increase, that is, the increase of coalbed methane output can promote the heat exchange efficiency of coal seams. Therefore, it is necessary to coordinate the implementation of underground heat exchange and gas extraction technology to improve the gas production effect of surface wells. Summary of the invention

[0004] The purpose of the present invention is to provide a device and method for promoting the mutual promotion of heat exchange in coalbed methane surface wells in order to solve at least one of the above-mentioned technical problems.

[0005] In the first aspect, an embodiment of the present invention provides a coalbed methane surface well gas production heat exchange mutual promotion and efficiency enhancement device, which is applied to a coalbed methane production U-shaped well, wherein the coalbed methane production U-shaped well includes a vertical well for drainage and production, a vertical well section of a horizontal well and a horizontal well section; the device includes: a vertical water pump, a drainage riser, a heat pump unit, a water temperature sensor, a gas extraction pump and an extraction monitoring sensor; wherein the water inlet end of the vertical water pump is connected to the drainage riser, the drainage riser is installed in the vertical well for drainage and production, and a filter is arranged at the bottom end of the drainage riser; the water outlet end of the vertical water pump is connected to the heat pump The water inlet of the evaporator end of the unit is connected, and the water outlet of the evaporator end of the heat pump unit is connected to the reinjection interface arranged at the top of the vertical shaft section of the horizontal well; the water temperature sensor is arranged at the water outlet end of the vertical water pump; the air inlet of the gas extraction pump is connected to the extraction interface at the top of the vertical well, and the extraction monitoring sensor is arranged at the air inlet position of the gas extraction pump; the water temperature sensor is used to monitor the water temperature at the water outlet end of the vertical water pump; the extraction monitoring sensor is used to monitor the methane gas concentration and flow at the air inlet position of the gas extraction pump.

[0006] Furthermore, the heat pump unit includes a screw heat pump unit.

[0007] Furthermore, a heat pump water inlet valve is provided at the water inlet of the evaporator end of the heat pump unit; and a drain valve is provided at the water outlet end of the vertical water pump.

[0008] In the second aspect, an embodiment of the present invention further provides a coalbed methane surface well gas production heat exchange mutual promotion and efficiency enhancement device, which is applied to coalbed methane surface vertical wells; the device includes: a vertical water pump, a drainage riser, a heat pump unit, a water temperature sensor, a gas extraction pump and an extraction monitoring sensor; wherein the water inlet end of the vertical water pump is connected to the drainage riser, the drainage riser is installed in the drainage vertical well, and a filter is arranged at the bottom end of the drainage riser; the water outlet end of the vertical water pump is connected to the water inlet end of the evaporator end of the heat pump unit, The water outlet at the evaporator end of the heat pump unit is connected to the reinjection interface arranged at the top of the vertical drainage well; the water temperature sensor is arranged at the water outlet end of the vertical water pump; the air inlet of the gas extraction pump is connected to the extraction interface at the top of the vertical drainage well, and the extraction monitoring sensor is arranged at the air inlet position of the gas extraction pump; the water temperature sensor is used to monitor the water temperature at the water outlet end of the vertical water pump; the extraction monitoring sensor is used to monitor the methane gas concentration and flow at the air inlet position of the gas extraction pump.

[0009] In the third aspect, an embodiment of the present invention further provides a method for mutual promotion and efficiency enhancement of gas production and heat exchange in coalbed methane surface wells, which is applied to the device for mutual promotion and efficiency enhancement of gas production and heat exchange in coalbed methane surface wells provided in an embodiment of the present invention; the method includes: when the gas production monitored by the extraction monitoring sensor is lower than a preset production threshold, starting the heat pump unit and increasing the pumping rate of the vertical water pump, so that the underground hot water in the drainage and production vertical well is transported to the heat pump unit by the vertical water pump for heat exchange; when the water temperature monitored by the water temperature sensor is lower than the preset temperature threshold, shutting down the heat pump unit and lowering the pumping rate of the vertical water pump to stop the heat exchange operation; when the water temperature monitored by the water temperature sensor and the highest water temperature at the last heat exchange start-up meet the preset conditions, starting the heat pump unit again and increasing the pumping rate of the vertical water pump.

[0010] Furthermore, when the gas production monitored by the extraction monitoring sensor is lower than a preset production threshold, the heat pump unit is started and the pumping capacity of the vertical water pump is increased, including: when the average daily gas production value monitored by the extraction monitoring sensor for multiple consecutive days is lower than a preset production threshold, the heat pump unit is started and the pumping capacity of the vertical water pump is increased; the preset production threshold includes 40% of the historical maximum daily gas production value.

[0011] Furthermore, after the underground hot water in the vertical well is transported to the heat pump unit by the vertical water pump for heat exchange, the cooling water after heat exchange flows back to the vertical well or the vertical well section of the horizontal well through the recharging interface.

[0012] Furthermore, the preset temperature threshold is no greater than 15°C.

[0013] Furthermore, the preset conditions include: n -T0≥0.7*(T n-1 -T0)≥10℃; where T n is the water temperature monitored before starting the heat exchange for the nth time, T n-1 is the highest water temperature when the heat exchange is started for the n-1th time, and T0 is the preset temperature threshold.

[0014] The present invention provides a device and method for mutual promotion and efficiency enhancement of gas production and heat exchange in coalbed methane surface wells. Through an intermittent cycle heat exchange process method, the temperature field of the coal seam is changed, the permeability and gas desorption capacity of the coal seam are improved, and the difficult problem of low gas production in the middle and late stages of surface well production is improved. The existing gas-heat co-production method is difficult to achieve mutual promotion of gas and heat production effects, which limits the later utilization of surface well projects and increases the technical problem of coalbed methane production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 A schematic diagram of a coalbed methane surface well gas production heat exchange mutual promotion and efficiency enhancement device provided by an embodiment of the present invention;

[0017] Figure 2 A schematic diagram of another coalbed methane surface well gas production heat exchange mutual promotion and efficiency enhancement device provided by an embodiment of the present invention;

[0018] Figure 3 A flow chart of a method for promoting mutual promotion and efficiency enhancement of gas production and heat exchange in coalbed methane surface wells provided in an embodiment of the present invention.

[0019] In the figure: 1. vertical water pump, 2. drainage riser, 3. heat pump unit, 4. water temperature sensor, 5. reinjection interface, 6. gas extraction pump, 7. extraction interface, 8. extraction monitoring sensor, 9. filter, 10. horizontal well vertical section, 11. drainage vertical well, 12. rock layer, 13. coal seam, 14. heat pump water inlet valve, 15. drainage valve, 16. horizontal well section, 17. branch well section. DETAILED DESCRIPTION

[0020] 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.

[0021] Embodiment 1

[0022] Figure 1 Schematic diagram of a coalbed methane surface well gas production heat exchange mutual promotion and efficiency enhancement device provided according to an embodiment of the present invention. Figure 1 As shown, the device is applied to a U-shaped well for coalbed methane extraction. The U-shaped well for coalbed methane extraction includes a vertical well 11, a horizontal well section 10 and a horizontal well section 16. The vertical well 11 passes through a rock layer 12 and a coal layer 13, the horizontal well section 10 passes through the rock layer 12 and enters the coal layer 13, and the horizontal well section 16 is arranged in the coal layer 13 and connects the vertical well 11 and the horizontal well section 10. Specifically, the device includes: a vertical water pump 1, a drainage riser 2, a heat pump unit 3, a water temperature sensor 4, a gas extraction pump 6 and an extraction monitoring sensor 8.

[0023] like Figure 1 As shown, the water inlet of the vertical water pump 1 is connected to the drainage riser 2, the drainage riser 2 is installed in the drainage vertical well 11, and a filter 9 is arranged at the bottom end of the drainage riser 2; the water outlet of the vertical water pump 1 is connected to the water inlet of the evaporator end of the heat pump unit 3, and the water outlet of the evaporator end of the heat pump unit 3 is connected to the recharge interface 5 arranged at the top of the horizontal well vertical well section 10; the water temperature sensor 4 is arranged at the water outlet of the vertical water pump 1; the air inlet of the gas extraction pump 6 is connected to the extraction interface 7 at the top of the drainage vertical well 11, and the extraction monitoring sensor 8 is arranged at the air inlet position of the gas extraction pump 6;

[0024] The water temperature sensor 4 is used to monitor the water temperature at the outlet of the vertical water pump 1;

[0025] The extraction monitoring sensor 8 is used to monitor the methane gas concentration and flow rate at the air inlet position of the gas extraction pump 6.

[0026] Optionally, the flow rate of the vertical water pump 1 is 5 to 800 m 3 / h, head is 500~15000m.

[0027] Optionally, the thermal conductivity of the drainage riser 2 pipe is ≤0.2 W / (m·K).

[0028] Optionally, the heat pump unit 3 comprises a screw heat pump unit. The water outlet temperature of the condenser end of the screw heat pump unit is 45-70°C.

[0029] Optionally, the temperature range monitored by the water temperature sensor 4 is 0 to 120° C., and the collection frequency is 1 to 60 min / time.

[0030] Optionally, the extraction monitoring sensor 8 can monitor the concentration and flow rate of methane gas at the same time, with a collection frequency of 1 to 60 minutes per time.

[0031] like Figure 1 As shown, in an optional implementation provided by an embodiment of the present invention, a heat pump water inlet valve 14 is provided at the water inlet of the evaporator end of the heat pump unit 3; and a drain valve 15 is provided at the water outlet end of the vertical water pump 1.

[0032] Embodiment 2

[0033] Figure 2 Schematic diagram of another coalbed methane ground well gas production heat exchange mutual promotion and efficiency enhancement device provided according to an embodiment of the present invention, the device is applied to coalbed methane ground vertical wells. Figure 2 As shown, the coalbed methane extraction surface vertical well includes a drainage vertical well 11 and a branch well section 17 connecting the middle and lower part of the drainage vertical well 11 with the coal seam 13. Specifically, the device includes: a vertical pump 1, a drainage riser 2, a heat pump unit 3, a water temperature sensor 4, a gas extraction pump 6 and an extraction monitoring sensor 8.

[0034] like Figure 2 As shown, the water inlet of the vertical water pump 1 is connected to the drainage riser 2, the drainage riser 2 is installed in the drainage vertical well 11, and a filter 9 is arranged at the bottom end of the drainage riser 2; the water outlet of the vertical water pump 1 is connected to the water inlet of the evaporator end of the heat pump unit 3, and the water outlet of the evaporator end of the heat pump unit 3 is connected to the recharge interface 5 arranged at the top of the drainage vertical well 11; the water temperature sensor 4 is arranged at the water outlet of the vertical water pump 1; the air inlet of the gas extraction pump 6 is connected to the extraction interface 7 at the top of the drainage vertical well 11, and the extraction monitoring sensor 8 is arranged at the air inlet position of the gas extraction pump 6;

[0035] The water temperature sensor 4 is used to monitor the water temperature at the outlet of the vertical water pump 1;

[0036] The extraction monitoring sensor 8 is used to monitor the methane gas concentration and flow rate at the air inlet position of the gas extraction pump 6.

[0037] like Figure 2 As shown, in an optional implementation provided by an embodiment of the present invention, a heat pump water inlet valve 14 is provided at the water inlet of the evaporator end of the heat pump unit 3; and a drain valve 15 is provided at the water outlet end of the vertical water pump 1.

[0038] Embodiment 3

[0039] Figure 3 The flowchart of a method for promoting the mutual promotion of heat exchange in coalbed methane surface well gas production is provided according to an embodiment of the present invention. The method is applied to the device for promoting the mutual promotion of heat exchange in coalbed methane surface well gas production provided according to an embodiment of the present invention. Figure 3 As shown, the method specifically comprises the following steps:

[0040] Step S302, when the gas production monitored by the extraction monitoring sensor is lower than the preset production threshold, the heat pump unit is started and the pumping capacity of the vertical water pump is increased so that the underground hot water in the drainage well is transported to the heat pump unit by the vertical water pump for heat exchange.

[0041] In an optional implementation provided by an embodiment of the present invention, when the average daily gas production value monitored by the extraction monitoring sensor for multiple consecutive days is lower than a preset production threshold, the heat pump unit is started and the water pumping capacity of the vertical water pump is increased. For example, the preset production threshold includes 40% of the historical maximum daily gas production value.

[0042] In an embodiment of the present invention, after the underground hot water in the vertical well is transported to the heat pump unit by a vertical water pump for heat exchange, the cooling water after heat exchange flows back to the vertical well or the vertical well section of the horizontal well through the recharging interface.

[0043] Specifically, in the coalbed methane surface well gas production heat exchange mutual promotion and efficiency enhancement device provided in the above-mentioned embodiment 1, the cooling water after heat exchange flows back to the vertical section of the horizontal well through the re-injection interface, and then continues to exchange heat with the coal rock through the horizontal well section, and then returns to the drainage vertical well, and the cycle is repeated.

[0044] Specifically, in the coalbed methane surface well gas production heat exchange mutual promotion and efficiency enhancement device provided in the above-mentioned embodiment 2, the cooling water after heat exchange flows back to the double-layer casing in the drainage and production vertical well through the re-injection interface, and part of it enters the rock layer and coal seam through the branch well section to continue heat exchange, and this cycle is repeated.

[0045] Step S304: when the water temperature monitored by the water temperature sensor is lower than the preset temperature threshold, the heat pump unit is turned off and the water pumping capacity of the vertical water pump is reduced to stop the heat exchange operation.

[0046] In an optional real-time method provided in an embodiment of the present invention, the preset temperature threshold is no greater than 15°C.

[0047] Step S306, when the water temperature monitored by the water temperature sensor meets the preset condition with the highest water temperature at the last heat exchange start-up, the heat pump unit is started again and the water pumping capacity of the vertical water pump is increased.

[0048] In an optional implementation manner provided by an embodiment of the present invention, the preset conditions include:

[0049] T n -T0≥0.7*(T n-1 -T0)≥10℃

[0050] Where, T n is the water temperature monitored before starting the heat exchange for the nth time, T n-1 is the highest water temperature when the heat exchange is started for the n-1th time, and T0 is the preset temperature threshold.

[0051] Embodiment 4

[0052] The embodiment of the present invention also provides another method for promoting the mutual promotion of heat exchange in coalbed methane surface well gas production, which is applied to the device for promoting the mutual promotion of heat exchange in coalbed methane surface well gas production provided by the embodiment of the present invention. Specifically, the method comprises the following steps:

[0053] Step 1: After the surface well is constructed, the coalbed methane surface well gas production heat exchange mutual promotion and efficiency enhancement device provided by the embodiment of the present invention is connected, the heat pump water inlet valve is closed, the drainage valve is opened, the vertical water pump and the gas extraction pump are started and operated according to the surface well extraction working conditions, and the vertical water pump pumping volume is adjusted to maintain the bottom hole flow pressure between 1 and 5 MPa, and the surface well casing is used to extract gas; the bottom hole flow pressure can be maintained at a high value during the drainage and pressure reduction stage, and the bottom hole flow pressure can be reduced when entering the drainage and stable production stage;

[0054] Step 2: When the average daily gas production value for 7 consecutive days monitored by the extraction monitoring sensor is lower than the historical maximum daily gas production value by 40%, open the heat pump water inlet valve and close the drain valve, start the screw heat pump unit and increase the vertical water pumping capacity, the underground hot water in the vertical well is transported to the screw heat pump unit by the vertical water pump, after heat exchange at the evaporator end, the cooling water flows back to the vertical well or the vertical well section of the horizontal well through the recharging interface, continues to exchange heat with the coal rock, and then the vertical water pump installed in the vertical well transports the underground hot water to the screw heat pump unit again, and the cycle repeats;

[0055] Step 3: When the water temperature monitored by the water temperature sensor reaches T0, the screw heat pump unit is turned off and the vertical water pumping volume is reduced, the heat pump water inlet valve is closed and the drain valve is opened to stop the underground heat exchange operation; T0 is set according to the actual ground temperature of the coal seam where the ground well is located. In the embodiment of the present invention, T0≤20°C;

[0056] Step 4: The temperature around the ground well rises under the influence of the earth's heat flow. When the water temperature T n The highest water temperature T at the last heat exchange start n-1 , satisfying T n -T0≥0.7*(T n-1 -T0)≥10℃, repeat steps 3 and 4 until the life cycle of the surface well gas production operation project ends.

[0057] From the above description, it can be seen that the present invention provides a device and method for mutual promotion and efficiency enhancement of gas production and heat exchange in coalbed methane surface wells. Through the intermittent cycle heat exchange process method, the temperature field of the coal seam is changed, the permeability of the coal seam and the gas desorption capacity are improved, and the problem of low gas production in the middle and late stages of surface well production is improved. The existing gas-heat co-production method is difficult to achieve mutual promotion of gas and heat production effects, which limits the later utilization of surface well projects and increases the technical problem of coalbed methane production costs.

[0058] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0059] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A coalbed methane surface well gas production heat exchange mutual promotion and efficiency enhancement device, characterized in that: Applicable to a U-shaped well for coalbed methane extraction, the U-shaped well for coalbed methane extraction includes a vertical well for drainage, a vertical well section and a horizontal well section; the device includes: a vertical water pump, a drainage riser, a heat pump unit, a water temperature sensor, a gas extraction pump and an extraction monitoring sensor; wherein, The water inlet of the vertical water pump is connected to the drainage riser, the drainage riser is installed in the drainage vertical well, and a filter is arranged at the bottom of the drainage riser; the water outlet of the vertical water pump is connected to the water inlet of the evaporator end of the heat pump unit, and the water outlet of the evaporator end of the heat pump unit is connected to the reinjection interface arranged at the top of the vertical well section of the horizontal well; the water temperature sensor is arranged at the water outlet of the vertical water pump; the air inlet of the gas extraction pump is connected to the extraction interface at the top of the drainage vertical well, and the extraction monitoring sensor is arranged at the air inlet position of the gas extraction pump; The water temperature sensor is used to monitor the water temperature at the outlet of the vertical water pump; The extraction monitoring sensor is used to monitor the methane gas concentration and flow rate at the air inlet position of the gas extraction pump.

2. The device according to claim 1, characterized in that: The heat pump unit comprises a screw heat pump unit.

3. The device according to claim 1, characterized in that: A heat pump water inlet valve is arranged at the water inlet of the evaporator end of the heat pump unit; and a drain valve is arranged at the water outlet end of the vertical water pump.

4. A coalbed methane surface well gas production heat exchange mutual promotion and efficiency enhancement device, characterized in that: Applicable to vertical wells on the ground for coalbed methane mining; the device includes: a vertical water pump, a drainage riser, a heat pump unit, a water temperature sensor, a gas extraction pump and an extraction monitoring sensor; wherein, The water inlet of the vertical water pump is connected to the drainage riser, the drainage riser is installed in the drainage vertical well, and a filter is arranged at the bottom of the drainage riser; the water outlet of the vertical water pump is connected to the water inlet of the evaporator end of the heat pump unit, and the water outlet of the evaporator end of the heat pump unit is connected to the reinjection interface arranged at the top of the drainage vertical well; the water temperature sensor is arranged at the water outlet of the vertical water pump; the air inlet of the gas extraction pump is connected to the extraction interface at the top of the drainage vertical well, and the extraction monitoring sensor is arranged at the air inlet position of the gas extraction pump; The water temperature sensor is used to monitor the water temperature at the outlet of the vertical water pump; The extraction monitoring sensor is used to monitor the methane gas concentration and flow rate at the air inlet position of the gas extraction pump.

5. A method for promoting the mutual promotion of heat exchange in coalbed methane surface wells, characterized in that: The device for promoting the heat exchange of coalbed methane surface well gas production according to any one of claims 1 to 4 is applied; the method comprises: When the gas production monitored by the extraction monitoring sensor is lower than the preset production threshold, the heat pump unit is started and the water pumping capacity of the vertical water pump is increased, so that the underground hot water in the drainage well is transported by the vertical water pump to the heat pump unit for heat exchange; When the water temperature monitored by the water temperature sensor is lower than the preset temperature threshold, the heat pump unit is turned off and the water pumping capacity of the vertical water pump is reduced to stop the heat exchange operation; When the water temperature monitored by the water temperature sensor meets a preset condition with the highest water temperature at the last heat exchange start-up, the heat pump unit is started again and the water pumping capacity of the vertical water pump is increased.

6. The method according to claim 5, characterized in that: When the gas production monitored by the extraction monitoring sensor is lower than a preset production threshold, the heat pump unit is started and the water pumping capacity of the vertical water pump is increased, including: When the average daily gas production value monitored by the extraction monitoring sensor for multiple consecutive days is lower than a preset production threshold, the heat pump unit is started and the pumping capacity of the vertical water pump is increased; the preset production threshold includes 40% of the historical maximum daily gas production value.

7. The method according to claim 5, characterized in that: After the underground hot water in the vertical well is transported to the heat pump unit by the vertical water pump for heat exchange, the cooling water after heat exchange flows back to the vertical well or the vertical well section of the horizontal well through the recharging interface.

8. The method according to claim 5, characterized in that: The preset temperature threshold is no greater than 15°C.

9. The method according to claim 5, characterized in that: The preset conditions include: T n -T0≥0.7*(T n-1 -T0)≥10℃ Where, T n is the water temperature monitored before starting the heat exchange for the nth time, T n-1 is the highest water temperature when the heat exchange is started for the n-1th time, and T0 is the preset temperature threshold.

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