System and method for intensifying corrosion of minerals by hot flue gas through coal seam zoning electroosmosis targeted water displacement

Abstract

The invention discloses a system and a method for strengthening corrosion of minerals by hot flue gas through coal seam zoning electroosmosis targeted water flooding, firstly, the hot flue gas is injected into a coal reservoir, CO2 of the hot flue gas displaces adsorbed gas in pores of the coal reservoir through a competitive adsorption effect, meanwhile, part of the CO2 is dissolved in water vapor of the hot flue gas and raw water in a coal body to form acidic water, and the acidic water is dissolved in water vapor of the hot flue gas; the acid water can corrode minerals in micropores of the coal reservoir to increase permeability of the coal body; when a water locking effect occurs in micropores of the coal reservoir, a high-voltage electric field is formed between every two adjacent drill holes, and the acidic water generates a targeted electroosmosis water driving effect under the action of the high-voltage electric field, so that the acidic water continuously moves in fractures of the coal reservoir in the direction of the electric field, and the water locking effect is broken; meanwhile, the acid water can promote multistage ionization of an acid medium in the solution to generate a large number of hydrogen ions under the action of electrified positive and negative electrodes, the mineral dissolution rate is increased, finally, the range and effect of hot flue gas on dissolution minerals in the coal reservoir are enlarged, and finally, the overall gas extraction efficiency of the coal reservoir is effectively improved.

Description

Technical Field

[0001] The present invention belongs to the field of efficient development of resources and carbon emission reduction in coal mining areas, and relates to a system and method for enhancing the permeability of low-permeability coal seams based on the hot flue gas dissolution effect of targeted electroosmotic water flooding, specifically a system and method for coal seam zoned electroosmotic targeted water flooding to enhance hot flue gas dissolution of minerals. Background Art

[0002] Coalbed methane is a hydrocarbon gas found in coal seams and coal-bearing strata, and its main component is methane. Coalbed methane is not only the main threat to coal mine safety production, but also an efficient unconventional natural gas. In addition, methane is also a gas with a strong temperature effect, and the greenhouse effect produced by its discharge into the atmosphere is about 22-28 times that of CO2. Most of my country's gas resources are stored in deep reservoirs, and deep reserves account for about 80%. Because deep coal reservoirs have strong adsorption and low permeability characteristics under the high ground stress environment, the efficiency of gas resource development in deep reservoirs is limited. Therefore, how to achieve efficient development of deep coal mine gas is of great significance to coal mine safety production, efficient development and utilization of resources, carbon sequestration and emission reduction.

[0003] The main components of hot flue gas produced and discharged by gas power plants are CO2, N2, and water vapor. When hot flue gas is injected into coal seams under pressure, it can effectively displace the adsorbed gas in the micropores of deep coal seams through competitive adsorption, and can seal the CO2 in the hot flue gas. However, when the permeability of the coal body is low, hot flue gas cannot be effectively injected into the coal seam. Although the water vapor in the hot flue gas and the native water in the coal body can form an acidic environment with the CO2 in the hot flue gas to dissolve the minerals in the cracks and increase the permeability of the coal body, the injectability of hot flue gas is improved. However, due to the significant water sensitivity of the coal body, when the coal seam is rich in water vapor, it is very easy to produce "water lock phenomenon" in its internal pores and cracks; this phenomenon makes it difficult to continuously inject hot flue gas and will cause water blocking and gas blocking, which ultimately limits the effective range of hot flue gas dissolution of minerals and the effect of hot flue gas in displacing coal seam gas. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides a system and method for coal seam zoned electro-osmotic targeted water flooding to enhance hot flue gas dissolution of minerals. The targeted electro-osmotic water flooding effect can overcome the water lock effect, enable targeted migration of acidic water, and ultimately effectively improve the effective range of hot flue gas dissolution of minerals and the effect of hot flue gas displacing coal seam gas.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a system for strengthening the hot flue gas dissolution of minerals by electroosmotic targeted water flooding in coal seams, including a hot flue gas injection gas production subsystem, an electroosmotic targeted water flooding subsystem, and a reservoir gas-liquid fluid state monitoring subsystem: The hot flue gas injection gas production subsystem includes a gas power plant on the ground, a hot flue gas storage tank, a high-temperature and high-pressure gas booster pump group and a gas-liquid fluid extraction pump station, as well as a transportation pipeline group and multiple targeted electroosmosis and gas-liquid transport coupling boreholes; one end of each targeted electroosmosis and gas-liquid transport coupling borehole extends into the coal reservoir, and the other end is on the ground; the transportation pipeline group includes a gas-liquid fluid transport main pipe and multiple gas-liquid fluid transport branch pipes, one end of each gas-liquid fluid transport branch pipe corresponds to extending into a targeted electroosmosis and gas-liquid transport coupling borehole, and the other end is connected to the gas-liquid fluid transport main pipe, and each gas-liquid fluid transport branch pipe is connected to the targeted electroosmosis and gas-liquid transport coupling borehole where it is located. A sealing mechanism is provided in between to prevent the gas and liquid in the borehole from flowing out from between the gas-liquid fluid transport branch pipe and the gas-liquid transport coupling borehole; the gas power plant is connected to the inlet of the high-temperature and high-pressure gas booster pump group through the hot flue gas storage tank, and the outlet of the high-pressure gas booster pump group is connected to the gas-liquid fluid transport main pipe, which is used to inject the hot flue gas produced and discharged by the gas power plant and stored in the hot flue gas storage tank into each targeted electroosmosis and gas-liquid transport coupling borehole through the gas-liquid fluid transport main pipe and the gas-liquid fluid transport branch pipe; the gas-liquid fluid extraction pump station is connected to the gas-liquid fluid transport main pipe, which is used to extract gas-liquid fluid from each targeted electroosmosis and gas-liquid transport coupling borehole through the gas-liquid fluid transport main pipe and the gas-liquid fluid transport branch pipe.

[0006] The electroosmotic targeted water flooding subsystem includes an integrated control terminal and a high-power power supply on the ground, as well as multiple positive electrode groups and multiple negative electrode groups. A positive electrode group and a negative electrode group are placed in each targeted electroosmotic and gas-liquid transport coupled borehole at the coal reservoir location. The integrated control terminal is connected to each positive electrode group and negative electrode group through an electrical signal transmission line, and is used to control the opening and closing of the positive electrode group and the negative electrode group respectively. When the integrated control terminal controls the positive electrode group of a targeted electroosmotic and gas-liquid transport coupled borehole and the negative electrode group of an adjacent targeted electroosmotic and gas-liquid transport coupled borehole to be turned on at the same time, a high-voltage electric field can be formed between the two boreholes, which is used for targeted electroosmotic driving of gas-liquid fluids; the high-power power supply supplies power for the entire electroosmotic targeted water flooding subsystem.

[0007] The reservoir gas-liquid fluid state monitoring subsystem includes multiple gas-liquid fluid state monitoring devices, which are respectively connected to each gas-liquid fluid transport branch pipe through pipelines, and are used to collect gas-liquid fluid data in each borehole and feed it back to the integrated control end.

[0008] Furthermore, a stop valve is installed on each gas-liquid fluid transport branch pipe and on the gas-liquid fluid transport main pipe between two adjacent gas-liquid fluid transport branch pipes to control the connection and disconnection between each gas-liquid fluid transport branch pipe and the high-temperature and high-pressure gas booster pump group or the gas-liquid fluid extraction pump station.

[0009] Furthermore, the sealing mechanism includes two sealing baffles, which are installed parallel to each other between the gas-liquid fluid transport branch pipe and the targeted electroosmosis and gas-liquid transport coupling borehole to form a gas-liquid sealed sealing section between the two sealing baffles.

[0010] Furthermore, high-power electrical conductors are provided on the positive electrode group and the negative electrode group to enhance the intensity of the generated electric field.

[0011] Furthermore, multiple targeted electroosmosis and gas-liquid transport coupling boreholes are arranged at equal intervals, and the distance between two adjacent boreholes is 10 to 50 m.

[0012] The working method of the above-mentioned coal seam zoned electroosmosis targeted water flooding to enhance the hot flue gas dissolution mineral system has the following specific steps: Step 1: construct multiple targeted electro-osmosis and gas-liquid transport coupling boreholes from the ground to the coal reservoir, and arrange and connect other parts of the coal seam zone electro-osmosis targeted water flooding and enhanced hot flue gas dissolution mineral system to complete the system arrangement work; and in the initial state, all stop valves are closed.

[0013] Step 2: Open the corresponding stop valve to connect the targeted electroosmosis and gas-liquid transport coupling borehole closest to the high-temperature and high-pressure gas booster pump group to the high-temperature and high-pressure gas booster pump group through the gas-liquid fluid transport branch pipe and the gas-liquid fluid transport main pipe. At the same time, the targeted electroosmosis and gas-liquid transport coupling borehole adjacent to the borehole is connected to the gas-liquid fluid extraction pump station through the gas-liquid fluid transport branch pipe and the gas-liquid fluid transport main pipe.

[0014] Step 3: Start the high-temperature and high-pressure gas booster pump group and the gas-liquid fluid extraction pump station, and transport the hot flue gas produced by the gas power plant and stored in the hot flue gas storage tank through the gas-liquid fluid transportation branch pipe and the gas-liquid fluid transportation main pipe to the targeted electroosmosis and gas-liquid transportation coupling borehole connected to the high-temperature and high-pressure gas booster pump group. At the same time, the gas-liquid fluid extraction pump station continuously performs negative pressure extraction on the targeted electroosmosis and gas-liquid transportation coupling borehole connected to it to form a negative pressure environment, thereby performing high-pressure injection into the coal reservoir between the above two boreholes. Gas permeability enhancement; in this process, the CO2 in the hot flue gas can effectively displace the adsorbed gas in the micropores of the coal reservoir through competitive adsorption, and seal the CO2 in the hot flue gas. At the same time, part of the CO2 in the hot flue gas dissolves in the water vapor of the hot flue gas and the native water in the coal body to form acidic water. The acidic water can dissolve the minerals in the micropores of the coal reservoir and increase the permeability of the coal body; when the injection pressure of the borehole continues to increase and the flow rate remains basically unchanged, it indicates that a water lock effect occurs in the micropores of the coal reservoir, and the hot flue gas can no longer be injected into the coal reservoir.

[0015] Step 4: The integrated control terminal simultaneously activates the positive electrode group in the borehole connected to the high-temperature and high-pressure gas booster pump group and the negative electrode group in the borehole connected to the gas-liquid fluid extraction pumping station in Step 3 through the electrical signal transmission line, thereby forming a high-voltage electric field between the two boreholes. The acidic water in the borehole generates a targeted electroosmotic water drive effect under the action of the high-voltage electric field, causing the acidic water to continuously migrate along the electric field direction within the coal reservoir fractures, breaking the water lock effect, and finally reaching the borehole connected to the gas-liquid fluid extraction pumping station. At the same time, under the action of the energized positive and negative electrodes, the acidic water can promote the multi-stage ionization of acidic media in the solution to generate a large number of hydrogen ions, increase the mineral dissolution rate, and ultimately increase the range and effect of the hot flue gas on the dissolved minerals in the coal reservoir.

[0016] Step 5: During the targeted electroosmotic water drive process in Step 4, the gas-liquid fluid state monitoring device corresponding to the borehole connected to the gas-liquid fluid extraction pumping station continuously collects the gas-liquid fluid extracted under negative pressure from this borehole and analyzes the physical and chemical parameters of the collected gas-liquid fluid. When the physical and chemical parameters of the continuously collected gas-liquid fluid meet the set standards, the electrode groups, high-temperature and high-pressure gas booster pump group, and gas-liquid fluid extraction pumping station in the two boreholes are shut down, and each stop valve is closed, thereby completing the permeability enhancement and gas displacement of the coal reservoir between the above two boreholes.

[0017] Step 6: Open the corresponding stop valve to switch the borehole connected to the gas-liquid fluid extraction pumping station in Step 2 to be connected to the high-temperature and high-pressure gas booster pump group, connect its adjacent borehole to the gas-liquid fluid extraction pumping station, and then repeat Steps 3 to 5 for the two boreholes in this step, thereby completing the permeability enhancement and gas displacement of the coal reservoir between the current two boreholes. Repeat this process until the permeability enhancement and gas displacement of the coal reservoir between all adjacent boreholes are completed, ultimately improving the overall gas extraction efficiency of the coal reservoir.

[0018] Furthermore, the physical and chemical parameters of the gas-liquid fluid in Step 5 include fluid temperature, fluid pH value, and water saturation. The set standards are that the fluid temperature is 50 - 100 °C, the fluid pH value is 3.0 < pH < 5.0, and the water saturation is 0.5 - 1.0.

[0019] Compared with the prior art, the present invention adopts a combination of a hot flue gas pressure injection gas production subsystem, an electroosmosis targeted water flooding subsystem and a reservoir gas-liquid fluid state monitoring subsystem. The hot flue gas pressure injection gas production subsystem is used to inject hot flue gas into the coal reservoir. The CO2 in the hot flue gas can effectively displace the adsorbed gas in the micropores of the coal reservoir through competitive adsorption, and seal the CO2 in the hot flue gas. At the same time, part of the CO2 in the hot flue gas dissolves in the water vapor of the hot flue gas and the native water in the coal body to form acidic water. The acidic water can dissolve the minerals in the micropores of the coal reservoir and increase the permeability of the coal body. When the water lock effect occurs in the micropores of the coal reservoir, the hot flue gas can no longer be injected into the coal reservoir. At this time, the electroosmosis targeted water flooding is started. The water subsystem forms a high-voltage electric field between two adjacent boreholes. The acidic water is affected by the high-voltage electric field to produce a targeted electroosmotic water flooding effect, so that the acidic water continues to migrate along the direction of the electric field in the coal reservoir fractures, breaking the water lock effect; at the same time, the acidic water can promote the multi-stage ionization of the acidic medium in the solution to generate a large number of hydrogen ions under the action of the energized positive and negative electrodes, thereby increasing the mineral dissolution rate and ultimately increasing the scope and effect of hot flue gas on the dissolved minerals in the coal reservoir; the reservoir gas-liquid fluid state monitoring subsystem is used to monitor the targeted electroosmotic water flooding effect in real time. When the set standard is reached, the permeability enhancement and gas displacement of the coal reservoir are completed, ultimately effectively improving the overall gas extraction efficiency of the coal reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall layout of the system in the present invention; Figure 2 It is a diagram of the internal structure of the targeted electroosmosis and gas-liquid transport coupling borehole in the present invention.

[0021] In the figure: 1-gas power plant, 2-hot flue gas storage tank, 3-high temperature and high pressure gas booster pump group, 4-first targeted electroosmosis and gas-liquid transport coupling borehole, 5-second targeted electroosmosis and gas-liquid transport coupling borehole, 6-third targeted electroosmosis and gas-liquid transport coupling borehole, 7-fourth targeted electroosmosis and gas-liquid transport coupling borehole, 8-fifth targeted electroosmosis and gas-liquid transport coupling borehole, 9-sixth targeted electroosmosis and gas-liquid transport coupling borehole, 10-coal reservoir, 11-stop valve, 12-electric signal transmission line, 13-transport pipeline group, 14-gas-liquid fluid state monitoring equipment, 15-integrated control end, 16-high power power supply, 17-gas-liquid fluid extraction pump station, 18-sealing partition, 19-gas-liquid sealing section, 20-high power conductor, 21-positive electrode group, 22-negative electrode group. DETAILED DESCRIPTION

[0022] The present invention will be further described below.

[0023] like Figure 1 As shown, the system of this embodiment includes a hot flue gas pressure injection gas production subsystem, an electroosmotic targeted water flooding subsystem, and a reservoir gas-liquid fluid state monitoring subsystem: The hot flue gas injection gas production subsystem includes a gas power plant 1 on the ground, a hot flue gas storage tank 2, a high-temperature and high-pressure gas booster pump group 3 and a gas-liquid fluid extraction pump station 17, as well as a transportation pipeline group 13 and six targeted electroosmosis and gas-liquid transport coupling boreholes; one end of each targeted electroosmosis and gas-liquid transport coupling borehole extends into the coal reservoir 10, and the other end is on the ground; the six targeted electroosmosis and gas-liquid transport coupling boreholes are respectively the first targeted electroosmosis and gas-liquid transport coupling borehole 4, the second targeted electroosmosis and gas-liquid transport coupling borehole 5, the third targeted electroosmosis and gas-liquid transport coupling borehole 6, the fourth targeted electroosmosis and gas-liquid transport coupling borehole 7, the fifth targeted electroosmosis and gas-liquid transport coupling borehole 8 and the sixth targeted electroosmosis and gas-liquid transport coupling borehole 9; multiple targeted electroosmosis and gas-liquid transport coupling boreholes are arranged at equal intervals, and the interval between two adjacent boreholes is 10 to 50 meters. The transport pipeline group 13 includes a gas-liquid fluid transport main pipe and multiple gas-liquid fluid transport branch pipes, one end of each gas-liquid fluid transport branch pipe extends into a targeted electroosmosis and gas-liquid transport coupling borehole, and the other end is connected to the gas-liquid fluid transport main pipe, and a sealing mechanism is provided between each gas-liquid fluid transport branch pipe and the targeted electroosmosis and gas-liquid transport coupling borehole in which it is located, for preventing the gas and liquid in the borehole from flowing out from between the gas-liquid fluid transport branch pipe and the targeted electroosmosis and gas-liquid transport coupling borehole; the sealing mechanism includes two sealing baffles 18, and the two sealing baffles 18 are installed in parallel with each other between the gas-liquid fluid transport branch pipe and the targeted electroosmosis and gas-liquid transport coupling borehole, so that a gas-liquid sealing section 19 is formed between the two sealing baffles 18 by grouting and solidification. The gas power plant 1 is connected to the inlet of the high-temperature and high-pressure gas booster pump group 3 through the hot flue gas storage tank 2, and the outlet of the high-pressure gas booster pump group 3 is connected to the gas-liquid fluid transport main pipe, which is used to inject the hot flue gas produced and discharged by the gas power plant 1 and stored in the hot flue gas storage tank 2 into each targeted electroosmosis and gas-liquid transport coupling borehole through the gas-liquid fluid transport main pipe and the gas-liquid fluid transport branch pipe; the gas-liquid fluid extraction pump station 17 is connected to the gas-liquid fluid transport main pipe, which is used to extract gas-liquid fluid from each targeted electroosmosis and gas-liquid transport coupling borehole through the gas-liquid fluid transport main pipe and the gas-liquid fluid transport branch pipe; a stop valve 11 is installed on each gas-liquid fluid transport branch pipe and on the gas-liquid fluid transport main pipe between two adjacent gas-liquid fluid transport branches, which is used to control the connection and disconnection of each gas-liquid fluid transport branch pipe and the high-temperature and high-pressure gas booster pump group 3 or the gas-liquid fluid extraction pump station 17.

[0024] The electroosmotic targeted water flooding subsystem includes an integrated control terminal 15 and a high-power power supply 16 on the ground, as well as a plurality of positive electrode groups 21 and a plurality of negative electrode groups 22. A positive electrode group 21 and a negative electrode group 22 are placed in each targeted electroosmotic and gas-liquid transport coupling borehole at the coal reservoir 10. The integrated control terminal 15 is connected to each positive electrode group 21 and negative electrode group 22 through an electrical signal transmission line 12, and is used to control the opening and closing of the positive electrode group 21 and the negative electrode group 22 respectively. When the integrated control terminal 15 controls the positive electrode group 21 of a targeted electroosmotic and gas-liquid transport coupling borehole and the negative electrode group 22 of an adjacent targeted electroosmotic and gas-liquid transport coupling borehole to be opened at the same time, a high-voltage electric field can be formed between the two boreholes for targeted electroosmotic driving of gas-liquid fluids; the high-power power supply 16 supplies power to the entire electroosmotic targeted water flooding subsystem. The positive electrode group 21 and the negative electrode group 22 are both provided with a high-power electrical conductor 20 to enhance the intensity of the generated electric field.

[0025] The reservoir gas-liquid fluid state monitoring subsystem includes multiple gas-liquid fluid state monitoring devices 14, which are respectively connected to each gas-liquid fluid transport branch pipe through pipelines, and are used to collect gas-liquid fluid data in each borehole and feed it back to the integrated control end.

[0026] The working method of the above system includes the following specific steps: Step 1: construct six targeted electroosmosis and gas-liquid transport coupling boreholes from the ground to the coal reservoir, and arrange and connect other parts of the coal seam zone electroosmosis targeted water flooding enhanced hot flue gas dissolution mineral system to complete the system arrangement work; and in the initial state, all stop valves 11 are closed; Step 2, open the corresponding stop valve 11, so that the first targeted electroosmosis and gas-liquid transport coupling borehole 4 is connected to the high-temperature and high-pressure gas booster pump group 3 through the gas-liquid fluid transport branch pipe and the gas-liquid fluid transport main pipe, and at the same time, the second targeted electroosmosis and gas-liquid transport coupling borehole 5 adjacent to the borehole is connected to the gas-liquid fluid extraction pump station 17 through the gas-liquid fluid transport branch pipe and the gas-liquid fluid transport main pipe; Step 3: Start the high-temperature and high-pressure gas booster pump set 3 and the gas-liquid fluid extraction pump station 17. The hot flue gas produced and stored in the hot flue gas storage tank 2 of the gas power plant 1 is transported through the gas-liquid fluid transport branch pipe and the gas-liquid fluid transport main pipe to the first target electroosmosis and gas-liquid transport coupling borehole 4. At the same time, the gas-liquid fluid extraction pump station 17 continuously conducts negative pressure extraction on the second target electroosmosis and gas-liquid transport coupling borehole 5 to form a negative pressure environment, so as to enhance the permeability of the coal reservoir between the above two boreholes by high-pressure gas injection; during this process, CO2 in the hot flue gas can effectively displace the adsorbed gas in the micropores of the coal reservoir 10 through competitive adsorption, and seal the CO2 in the hot flue gas. At the same time, part of the CO2 in the hot flue gas dissolves in the water vapor of the hot flue gas and the original water in the coal body to form acidic water, and the acidic water can dissolve and increase the permeability of the minerals in the micropores of the coal reservoir 10; when the injection pressure of the first target electroosmosis and gas-liquid transport coupling borehole 4 continues to increase and the flow rate is basically unchanged, it indicates that a water lock effect occurs in the micropores of the coal reservoir 10, and the hot flue gas cannot continue to be injected into the coal reservoir; Step 4: The integrated control terminal 15 simultaneously activates the positive electrode group in the first target electroosmosis and gas-liquid transport coupling borehole 4 and the negative electrode group in the second target electroosmosis and gas-liquid transport coupling borehole 5 through the electrical signal transmission line 12, so as to form a high-voltage electric field between the two boreholes. The acidic water in the first target electroosmosis and gas-liquid transport coupling borehole 4 produces a target electroosmotic water displacement effect under the action of the high-voltage electric field, so that the acidic water continuously migrates along the electric field direction in the coal reservoir fissures, breaks the water lock effect, and finally reaches the second target electroosmosis and gas-liquid transport coupling borehole 5; at the same time, the acidic water can promote the multi-stage ionization of acidic media in the solution to generate a large number of hydrogen ions under the action of the energized positive and negative electrodes, improve the mineral dissolution rate, and finally increase the range and effect of the hot flue gas on dissolving minerals in the coal reservoir; Step 5: During the process of target electroosmotic water displacement in Step 4, the gas-liquid fluid state monitoring device 14 corresponding to the second target electroosmosis and gas-liquid transport coupling borehole 5 continuously collects the gas-liquid fluid extracted by negative pressure from this borehole, and analyzes the physical and chemical parameters of the collected gas-liquid fluid. The physical and chemical parameters of the gas-liquid fluid include fluid temperature, fluid pH value, and water saturation; when the physical and chemical parameters of the continuously collected gas-liquid fluid meet the set standards, turn off the electrode groups, the high-temperature and high-pressure gas booster pump set 3, and the gas-liquid fluid extraction pump station 17 in the two boreholes, and close each stop valve 11, so as to complete the permeability enhancement and gas displacement of the coal reservoir between the above two boreholes; the set standards are that the fluid temperature is 50 - 100 °C, the fluid pH value is 3.0 < pH < 5.0, and the water saturation is 0.5 - 1.0.

[0027] Step six, open the corresponding stop valve to connect the second targeted electro-osmosis and gas-liquid transport coupled borehole 5 with the high-temperature and high-pressure gas booster pump group, and connect the adjacent third targeted electro-osmosis and gas-liquid transport coupled borehole 6 with the gas-liquid fluid extraction pump station 17, and then repeat steps three to five for the two boreholes in this step, thereby completing the permeability enhancement and gas displacement of the coal reservoir between the current two boreholes; repeat this process until the permeability enhancement and gas displacement of the coal reservoir 10 between all adjacent boreholes are completed, thereby ultimately improving the overall gas extraction efficiency of the coal reservoir 10.

[0028] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A system for targeted water flooding by electroosmosis in coal seams to enhance hot flue gas dissolution of minerals, characterized in that: Including hot flue gas injection gas production subsystem, electroosmotic targeted water flooding subsystem, reservoir gas-liquid fluid state monitoring subsystem: The hot flue gas injection gas production subsystem includes a gas power plant on the ground, a hot flue gas storage tank, a high-temperature and high-pressure gas booster pump group and a gas-liquid fluid extraction pump station, as well as a transportation pipeline group and a plurality of targeted electroosmosis and gas-liquid transport coupling boreholes; one end of each targeted electroosmosis and gas-liquid transport coupling borehole extends into the coal reservoir, and the other end is on the ground; the transportation pipeline group includes a gas-liquid fluid transport main pipe and a plurality of gas-liquid fluid transport branch pipes, one end of each gas-liquid fluid transport branch pipe extends into a corresponding targeted electroosmosis and gas-liquid transport coupling borehole, and the other end is connected to the gas-liquid fluid transport main pipe, and each gas-liquid fluid transport branch pipe is provided with a gas-liquid fluid transport branch pipe and a gas-liquid fluid transport branch pipe. There is a sealing mechanism for preventing the gas and liquid in the borehole from flowing out from the gas-liquid fluid transport branch pipe and the targeted electroosmosis and gas-liquid transport coupling borehole; the gas power plant is connected to the inlet of the high-temperature and high-pressure gas booster pump group through the hot flue gas storage tank, and the outlet of the high-pressure gas booster pump group is connected to the gas-liquid fluid transport main pipe, which is used to inject the hot flue gas produced and discharged by the gas power plant and stored in the hot flue gas storage tank into each targeted electroosmosis and gas-liquid transport coupling borehole through the gas-liquid fluid transport main pipe and the gas-liquid fluid transport branch pipe; the gas-liquid fluid extraction pump station is connected to the gas-liquid fluid transport main pipe, which is used to extract gas and liquid fluid from each targeted electroosmosis and gas-liquid transport coupling borehole through the gas-liquid fluid transport main pipe and the gas-liquid fluid transport branch pipe; The electroosmotic targeted water flooding subsystem includes an integrated control end and a high-power power supply on the ground, as well as a plurality of positive electrode groups and a plurality of negative electrode groups. A positive electrode group and a negative electrode group are placed in each targeted electroosmotic and gas-liquid transport coupling borehole at the coal reservoir position. The integrated control end is connected to each positive electrode group and negative electrode group through an electrical signal transmission line to control the opening and closing of the positive electrode group and the negative electrode group respectively. When the integrated control end controls the positive electrode group of a targeted electroosmotic and gas-liquid transport coupling borehole and the negative electrode group of an adjacent targeted electroosmotic and gas-liquid transport coupling borehole to be opened at the same time, a high-voltage electric field can be formed between the two boreholes for targeted electroosmotic driving of gas-liquid fluids; The high-power power supply supplies power to the entire electroosmotic targeted water drive subsystem; The reservoir gas-liquid fluid state monitoring subsystem includes multiple gas-liquid fluid state monitoring devices, which are respectively connected to each gas-liquid fluid transport branch pipe through pipelines, and are used to collect gas-liquid fluid data in each borehole and feed it back to the integrated control end.

2. The system for coal seam zoned electroosmosis targeted water flooding to enhance hot flue gas dissolution of minerals according to claim 1 is characterized in that: A stop valve is installed on each gas-liquid fluid transport branch pipe and on the gas-liquid fluid transport main pipe between two adjacent gas-liquid fluid transport branch pipes to control the connection and disconnection between each gas-liquid fluid transport branch pipe and the high-temperature and high-pressure gas booster pump group or the gas-liquid fluid extraction pump station.

3. The system for coal seam zoned electroosmosis targeted water flooding to enhance hot flue gas dissolution of minerals according to claim 1 is characterized in that: The sealing mechanism comprises two blocking baffles which are installed parallel to each other between the gas-liquid fluid transport branch pipe and the targeted electroosmosis and gas-liquid transport coupling borehole, so that a gas-liquid sealed blocking section is formed between the two blocking baffles.

4. The system for coal seam zoned electroosmosis targeted water flooding to enhance hot flue gas dissolution of minerals according to claim 1 is characterized in that: The positive electrode group and the negative electrode group are both provided with high-power electrical conductors for enhancing the intensity of the generated electric field.

5. The system for coal seam zoned electroosmosis targeted water flooding to enhance hot flue gas dissolution of minerals according to claim 1 is characterized in that: Multiple targeted electroosmosis and gas-liquid transport coupling boreholes are arranged at equal intervals, and the distance between two adjacent boreholes is 10 to 50 meters.

6. A method for working a coal seam zoned electroosmosis targeted water flooding enhanced hot flue gas dissolution mineral system according to any one of claims 1 to 5, characterized in that: The specific steps are: Step 1: construct multiple targeted electroosmosis and gas-liquid transport coupling boreholes from the ground to the coal reservoir, and arrange and connect other parts of the coal seam zone electroosmosis targeted water flooding enhanced hot flue gas dissolution mineral system to complete the system arrangement work; and in the initial state, all stop valves are closed; Step 2: Open the corresponding stop valve to connect the targeted electroosmosis and gas-liquid transport coupling borehole closest to the high-temperature and high-pressure gas booster pump group to the high-temperature and high-pressure gas booster pump group through the gas-liquid fluid transport branch pipe and the gas-liquid fluid transport main pipe, and at the same time, connect the targeted electroosmosis and gas-liquid transport coupling borehole adjacent to the borehole to the gas-liquid fluid extraction pump station through the gas-liquid fluid transport branch pipe and the gas-liquid fluid transport main pipe; Step 3: Start the high-temperature and high-pressure gas booster pump group and the gas-liquid fluid extraction pump station, and transport the hot flue gas produced by the gas power plant and stored in the hot flue gas storage tank through the gas-liquid fluid transportation branch pipe and the gas-liquid fluid transportation main pipe to the targeted electroosmosis and gas-liquid transportation coupling borehole connected to the high-temperature and high-pressure gas booster pump group. At the same time, the gas-liquid fluid extraction pump station continuously performs negative pressure extraction on the targeted electroosmosis and gas-liquid transportation coupling borehole connected to it to form a negative pressure environment, thereby performing high-pressure injection into the coal reservoir between the above two boreholes. Gas permeability enhancement; in this process, the CO2 in the hot flue gas can effectively displace the adsorbed gas in the micropores of the coal reservoir through competitive adsorption, and seal the CO2 in the hot flue gas. At the same time, part of the CO2 in the hot flue gas dissolves in the water vapor of the hot flue gas and the native water in the coal body to form acidic water. The acidic water can dissolve the minerals in the micropores of the coal reservoir and increase the permeability of the coal body; when the injection pressure of the borehole continues to increase and the flow rate remains basically unchanged, it means that a water lock effect occurs in the micropores of the coal reservoir, and the hot flue gas can no longer be injected into the coal reservoir; Step 4: The integrated control end simultaneously activates the positive electrode group in the borehole connected to the high-temperature and high-pressure gas booster pump group and the negative electrode group in the borehole connected to the gas-liquid fluid extraction pump station in step 3 through the electrical signal transmission line, thereby forming a high-voltage electric field between the two boreholes. The acidic water in the borehole is subjected to the action of the high-voltage electric field to produce a targeted electroosmotic water drive effect, so that the acidic water continues to migrate along the direction of the electric field in the coal reservoir fractures, breaking the water lock effect, and finally reaches the borehole connected to the gas-liquid fluid extraction pump station; at the same time, the acidic water can promote the multi-stage ionization of the acidic medium in the solution to generate a large number of hydrogen ions under the action of the energized positive and negative electrodes, thereby increasing the mineral dissolution rate, and finally increasing the scope and effect of the hot flue gas on the dissolution of minerals in the coal reservoir; Step Five: During the targeted electroosmotic water drive process in Step Four, the gas-liquid fluid state monitoring device corresponding to the borehole connected to the gas-liquid fluid extraction pumping station collects the gas-liquid fluid extracted under negative pressure from this borehole in real time and analyzes the physical and chemical parameters of the collected gas-liquid fluid; when the physical and chemical parameters of the gas-liquid fluid collected in real time meet the set standards, turn off the electrode groups, high-temperature and high-pressure gas booster pump groups, and gas-liquid fluid extraction pumping station in the two boreholes, and close each stop valve, thereby completing the permeability enhancement and gas displacement of the coal reservoir between the above two boreholes; Step Six: Open the corresponding stop valve to switch the borehole connected to the gas-liquid fluid extraction pumping station in Step Two to be connected to the high-temperature and high-pressure gas booster pump group, connect its adjacent borehole to the gas-liquid fluid extraction pumping station, and then repeat Steps Three to Five for the two boreholes in this step, thereby completing the permeability enhancement and gas displacement of the coal reservoir between the current two boreholes; repeat this process until the permeability enhancement and gas displacement of the coal reservoir between all adjacent boreholes are completed, ultimately improving the overall gas extraction efficiency of the coal reservoir.

7. The working method according to claim 6, characterized in that: The physical and chemical parameters of the gas-liquid fluid in Step Five include fluid temperature, fluid pH value, and water saturation. The set standards are that the fluid temperature is 50 - 100 °C, the fluid pH value is 3.0 < pH < 5.0, and the water saturation is 0.5 - 1.0.

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