Device and method for displacing coalbed methane through carbon dioxide emulsion carbon sequestration

Abstract

The invention provides a device and method for displacing coalbed methane through carbon dioxide emulsion carbon sequestration, and belongs to the field of coalbed methane exploitation and carbon dioxide geological sequestration. The device comprises an underground system module, a signal detection module, a gas separation module and a carbon dioxide emulsion preparation module; the underground system module is connected with the gas separation module and the carbon dioxide emulsion preparation module, the signal detection module is arranged on the underground system module, and the gas separation module is connected with the carbon dioxide emulsion preparation module. The comprehensive utilization efficiency of resources is improved while the production cost is reduced, and various safety guarantee facilities are arranged; according to the method, geological storage of carbon dioxide is achieved, meanwhile, stratum stress is effectively compensated, the homogeneous stability of a backfill layer is enhanced, and the desorption capacity and the flowing capacity of coal bed gas can be effectively improved through a carbon dioxide emulsion method.

Description

Technical Field

[0001] This invention relates to the fields of coalbed methane extraction and carbon dioxide geological storage, and particularly to a carbon dioxide emulsion carbon sequestration device and method for displacing coalbed methane. Background Technology

[0002] Coal, as a large-scale fuel for global power generation, sees its consumption increasing year by year. During coalbed methane (CBM) extraction, gas explosions pose a significant potential safety hazard, severely impacting the safety and efficiency of mining operations. Coal seams have a much higher adsorption capacity for CO2 than CH4. Injected CO2 competes with CH4 in the coal seam for adsorption, displacing CH4 from its adsorbed state to a free state, thereby improving CBM recovery. Using carbon dioxide emulsions to replace CBM gas in CBMs ensures simultaneous geological carbon sequestration during extraction. Fractured and soft coal seams, due to their poor permeability, low mechanical strength, and difficulty in direct pressure treatment, contain large amounts of gas, but their desorption and flow capacity are weak. Using carbon dioxide emulsions to displace CO2-CH4 in fractured and soft coal seams reduces the water-locking effect, ensuring replacement efficiency and improving recovery while simultaneously achieving geological carbon dioxide sequestration. In addition, the lubricating and supporting effects of CO2 emulsion can significantly reduce the risk of coal seam collapse, providing a safer and more stable environment for mining operations. Summary of the Invention

[0003] The purpose of this invention is to provide a carbon dioxide emulsion carbon sequestration and displacement device and method for coalbed methane. This invention's device achieves the recycling of separated carbon dioxide, reducing production costs while improving the overall efficiency of resource utilization, and is equipped with multiple safety assurance facilities. This invention's method, while achieving geological carbon dioxide sequestration, effectively compensates for formation stress, enhances the homogeneity and stability of the backfill layer, and utilizes the carbon dioxide emulsion method to effectively improve the desorption and flow capacity of coalbed methane. Compared with traditional mining methods, it can significantly increase the recovery rate of coalbed methane, achieving efficient development and utilization of coalbed methane resources.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A carbon dioxide emulsion carbon sequestration and displacement device for coalbed methane is characterized by comprising an underground system module, a signal detection module, a gas separation module, and a carbon dioxide emulsion preparation module. The underground system module is connected to the gas separation module and the carbon dioxide emulsion preparation module. The underground system module is used for coalbed methane extraction operations and carbon dioxide geological sequestration. The signal detection module is installed on the underground system module. The gas separation module is connected to the carbon dioxide emulsion preparation module. The gas separation module is used to collect, separate, and simultaneously collect gas. The carbon dioxide emulsion module is used to prepare displacement agents and improve the recovery rate of coalbed methane.

[0006] Furthermore, the underground system module includes a first hollow sleeve, a second hollow sleeve, an injection pipe, a drainage pipe, a one-way valve, a filter screen, an injection port packer, and a production pipe packer. The first hollow sleeve is lowered along the injection well to the bottom of the well and its height is the same as the injection well. The second hollow sleeve is lowered along the drainage well to the bottom of the well and its height is the same as the drainage well. Cement is installed between the injection well and the first hollow sleeve, and between the drainage well and the second hollow sleeve, for well cementing. The injection pipe is lowered into the coal seam through the hollow part inside the first hollow sleeve. The drainage pipe is located in the hollow part inside the second hollow sleeve. One-way valves are installed on the injection pipe and the drainage pipe, respectively. Filter screens are installed above the one-way valve on the injection pipe and below the one-way valve on the drainage pipe, respectively. The injection port packer is located in the bottom gap between the injection pipe and the first hollow sleeve, and the production pipe packer is located in the bottom gap between the drainage pipe and the second hollow sleeve.

[0007] Furthermore, the signal detection module includes several supporting steel plates, stress sensors, through holes, and cables. The supporting steel plates are evenly distributed on the wall surface between the injection pipe and the first hollow sleeve, and between the discharge pipe and the second hollow sleeve. Stress sensors are arranged between adjacent supporting steel plates. The stress sensors are arranged on the inner wall surface of the first and second hollow sleeves. Through holes are arranged at the geometric center of the supporting steel plates. The cables are connected to the stress sensors through the through holes.

[0008] Furthermore, the gas separation module includes a gas separation device, which includes a device body, a vacuum pump, a methane storage tank, a first valve, a methane leakage monitoring device, a methane flow sensor, a carbon dioxide storage tank, a second valve, and a carbon dioxide flow sensor.

[0009] The main body of the gas separation device is connected to the top of the discharge pipe. A gas pump is installed on the top of the main body. The right side of the main body is connected to a methane storage tank through a first pipeline. A first valve, a methane leakage monitoring device, and a methane flow sensor are installed on the first pipeline from left to right. The left side of the main body is connected to a carbon dioxide storage tank through a second pipeline. A second valve and a carbon dioxide flow sensor are installed on the second pipeline from right to left.

[0010] Furthermore, the carbon dioxide emulsion preparation module includes a carbon dioxide emulsion preparation device, which includes a buffer tank, a pressure reducing valve, a pressure sensor, a high-pressure stirred reactor, a water pump, a chemical reagent adding device, a chemical reagent booster pump, a constant temperature water bath, a carbon dioxide emulsion storage tank, and a third valve.

[0011] The buffer tank is connected to the carbon dioxide storage tank via a third pipeline, on which a pressure reducing valve and a pressure sensor are installed sequentially from left to right. The buffer tank is connected to the top right end of the high-pressure stirred reactor via a fourth pipeline. The top left end of the high-pressure stirred reactor is connected to the top of the main body of the device via a fifth pipeline, on which a water pump is installed. The bottom center of the high-pressure stirred reactor is connected to a chemical reagent adding device via a sixth pipeline, on which a chemical reagent booster pump is installed. The right side of the constant temperature water bath is connected to the upper right side of the high-pressure stirred reactor, and the left side of the constant temperature water bath is connected to one end of the bottom of the high-pressure stirred reactor. The upper left side of the high-pressure stirred reactor is connected to the carbon dioxide emulsion storage tank via a seventh pipeline, on which a third valve is installed. The carbon dioxide emulsion storage tank is connected to the injection pipe.

[0012] Furthermore, the injection tube includes an emulsion booster pump and an injection tube valve, which are arranged sequentially from top to bottom on the injection tube.

[0013] Furthermore, the drainage pipe includes a drainage pipe booster pump, a methane concentration sensor, and a drainage valve. The drainage pipe booster pump is located at the top of the drainage pipe, and the methane concentration sensor and the drainage valve are arranged sequentially from top to bottom above the drainage pipe. The drainage pipe is connected to the bottom of the main body of the device through the drainage pipe booster pump.

[0014] Furthermore, the high-pressure stirred reactor includes a reactor water inlet, a reactor air inlet, a chemical reagent feed inlet, a mechanical stirring paddle, a reactor temperature sensor, and a reactor pressure sensor.

[0015] The high-pressure stirred reactor has a water inlet at the top left end, which is connected to the top of the main body of the device via a fifth pipe. An air inlet is located at the top right end of the reactor, which is connected to a buffer tank via a fourth pipe. A chemical reagent inlet is located at the bottom center of the reactor, which is connected to a chemical reagent adding device via a sixth pipe. One end of the mechanical stirring paddle is located at the top center of the reactor, and one end of the paddle blade extends into the reactor. A reactor temperature sensor and a reactor pressure sensor are located at opposite ends of the top of the reactor.

[0016] A method of using a carbon dioxide emulsion carbon sequestration and displacement device for coalbed methane, characterized by comprising the following steps:

[0017] S1. Arrangement of mining wells: First, the location, depth and fracture distribution of the coal seam are determined through geological exploration. Well drilling operations are carried out in the fractured and soft coal seam. Injection wells and drainage wells are arranged. Hollow casings are lowered and cement is injected to solidify the wells. The wells pass through the rock layer from the surface to reach the various locations of the coal seam. Drilling operations are stopped after completion.

[0018] S2. Pipeline Section Arrangement: The injection pipe is lowered along the hollow section of the inner interlayer of the first hollow sleeve. When the injection pipe reaches the bottom of the injection well, it is stopped. The pipe section is sealed using injection port packers and production port packers to seal the gaps between the first hollow sleeve and the injection pipe, and between the second hollow sleeve and the drainage pipe. High-pressure one-way valves are used for the injection pipe and the drainage pipe. One end of the drainage pipe is lowered from the drainage well, and the other end is higher than the drainage well and connected to the gas-liquid separation device. After installing the stress sensor, the supporting steel plate is welded. Then, the cable is lowered through the through hole and connected to the stress sensor to collect formation data.

[0019] S3. Initial Drainage: Following the above steps, the initial coalbed methane extraction is carried out. First, ensure all valves are initially closed. Turn on the booster pump connected to the drainage pipe, and turn on the main body of the gas-liquid separation device and the extraction pump. Gradually open the first and second valves to perform the initial coalbed methane gas separation. At this time, the coalbed methane in the collection area has undergone one extraction, and the separated methane and carbon dioxide gases are stored in the methane storage tank and carbon dioxide storage tank, respectively. Observe the methane flow rate in the drainage pipe. When the flow rate and concentration are less than 0.5%, close the drainage valve, the first valve, and the second valve to complete the initial coalbed methane collection.

[0020] S4. Carbon Dioxide Emulsion Synthesis and Circulation: After completing the initial coalbed methane extraction work, first open the third valve and the high-pressure stirred reactor. Inject the separated and purified carbon dioxide and pumped water into the high-pressure stirred reactor through the fourth and fifth pipelines, respectively. The collected and separated carbon dioxide gas enters the buffer tank from the carbon dioxide storage tank through the third pipeline, and then enters the high-pressure stirred reactor through the fourth pipeline. Open the pressure reducing valve to adjust the pressure of the carbon dioxide gas to the set value of 14 MPa. At the same time, start the constant temperature water bath to adjust the temperature in the high-pressure stirred reactor to the set value of 50-95℃. In the high-pressure stirred reactor, the mechanical stirring paddle is used to stir at a speed of 500-1000 rpm to achieve high-pressure shearing. Emulsifier is added to the high-pressure stirred reactor through the chemical reagent adding device. The emulsifier is TW80 nonionic surfactant, with a concentration of 0.5-8% (mass fraction). Under the set temperature, pressure and stirring conditions, stir continuously for 10-40 minutes to generate a carbon dioxide emulsion with carbon dioxide as the continuous phase and water as the dispersed phase. The volume fraction of carbon dioxide in the generated emulsion is generally 80-95%, and its viscosity is much higher than that of pure carbon dioxide. Finally, the generated carbon dioxide emulsion is transported to a carbon dioxide emulsion storage tank through a seventh pipeline for storage, and injected into the target formation through an injection pipe as needed for subsequent coalbed methane extraction or other applications.

[0021] S5. Displacement and Carbon Dioxide Sequestration: Open the valves of the carbon dioxide emulsion storage tank and injection pipe, and start the emulsion booster pump. The carbon dioxide emulsion enters the bottom of the collection area from the carbon dioxide emulsion storage tank via the emulsion booster pump and injection pipe to carry out the displacement work of carbon dioxide-methane adsorption and desorption. According to the estimated flow rate and displacement time based on the pore volume, after injecting a certain amount of carbon dioxide emulsion, maintain the displacement reaction for a long time, close the carbon dioxide emulsion storage tank, injection pipe valve, and emulsion booster pump to promote coalbed methane displacement. After the displacement is completed, open the drainage valve, the first valve, and the second valve, and repeat the cycle of coalbed methane collection, carbon dioxide emulsion synthesis, and carbon dioxide emulsion injection according to the drainage process in step S3.

[0022] S6. After completing the above work, determine the number of cycles based on the previous displacement efficiency; perform well sealing, use a sealing device to plug the wellhead, and install a methane leakage monitoring device.

[0023] Advantages of this invention:

[0024] 1. Utilizing CO2 emulsions to displace coalbed methane (CBM) can effectively improve the desorption and flow capacity of CBM. Compared with traditional extraction methods, it can significantly increase the recovery rate of CBM, achieving efficient development and utilization of CBM resources. On the one hand, after the CO2 emulsion is injected into the coal seam, some CO2 can be effectively sealed within the coal seam, reducing greenhouse gas emissions and providing good environmental benefits. On the other hand, the separated CO2 gas can be returned to the high-pressure stirred reactor for the regeneration of CO2 emulsion through a gas-liquid separation device, realizing the recycling of CO2, reducing production costs, and improving the comprehensive utilization efficiency of resources.

[0025] 2. This device is suitable for coalbed methane extraction in fractured and soft coal seams. It has been optimized for such special geological conditions, including the layout of directional horizontal wells and the corresponding pipe section sealing and support structures. It can effectively solve the technical problems in the mining process of fractured and soft coal seams, has strong geological adaptability, and can provide an effective technical solution for coalbed methane extraction under similar geological conditions. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the device of the present invention;

[0027] Figure 2 This is a schematic diagram of the gas separation device in the apparatus of the present invention;

[0028] Figure 3 This is a schematic diagram of the carbon dioxide emulsion preparation device in the apparatus of the present invention;

[0029] Figure 4 This is a schematic diagram of the high-pressure stirred reactor in the device of the present invention;

[0030] In the diagram: 1. First hollow sleeve; 2. Second hollow sleeve; 3. Injection pipe; 3-1. Emulsion booster pump; 3-2. Injection pipe valve; 4. Drainage pipe; 4-1. Drainage pipe booster pump; 4-2. Methane concentration sensor; 4-3. Drainage valve; 5. Check valve; 6. Filter screen; 7. Injection port packer; 8. Drainage pipe packer; 9. Support steel plate; 10. Stress sensor; 11. Through hole; 12. Gas separation device; 12-1. Device body; 12-2. Pump; 12-3. Methane storage tank; 12-4. First valve; 12-5. Methane leakage monitoring device; 12-6. Methane flow sensor; 12-7. Carbon dioxide storage tank; 12-8. Two valves; 12-9 Carbon dioxide flow sensor; 13. Carbon dioxide emulsion preparation device; 13-1. Buffer tank; 13-2. Pressure reducing valve; 13-3. Pressure sensor; 13-4. High-pressure stirred reactor; 13-4-1. Reactor inlet; 13-4-2. Reactor air inlet; 13-4-3. Chemical reagent inlet; 13-4-4. Mechanical stirrer; 13-4-5. Reactor temperature sensor; 13-4-6. Reactor pressure sensor; 13-5. Water pump; 13-6. Chemical reagent adding device; 13-7. Chemical reagent booster pump; 13-8. Constant temperature water bath; 13-9. Carbon dioxide emulsion storage tank; 13-10. Third valve. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0032] like Figure 1 As shown, a carbon dioxide emulsion carbon sequestration and displacement device for coalbed methane includes an underground system module, a signal detection module, a gas separation module, and a carbon dioxide emulsion preparation module. The underground system module is connected to the gas separation module and the carbon dioxide emulsion preparation module. The underground system module is used for coalbed methane extraction operations and carbon dioxide geological sequestration. The signal detection module is installed on the underground system module. The gas separation module is connected to the carbon dioxide emulsion preparation module. The gas separation module is used to collect gas, separate gas, and simultaneously collect gas. The carbon dioxide emulsion module is used to prepare displacement agents and improve the recovery rate of coalbed methane.

[0033] In a preferred embodiment of the present invention, the underground system module includes a first hollow sleeve 1, a second hollow sleeve 2, an injection pipe 3, a drainage pipe 4, a one-way valve 5, a filter screen 6, an injection port packer 7, and a production pipe packer 8. The first hollow sleeve 1 is lowered along the injection well to the bottom of the well and its height is the same as that of the injection well. The second hollow sleeve 2 is lowered along the drainage well to the bottom of the well and its height is the same as that of the drainage well. Cement is installed between the injection well and the first hollow sleeve 1, and between the drainage well and the second hollow sleeve 2, to solidify the well and support the well wall and maintain its stability. The injection pipe 3 is lowered into the coal seam through the hollow part inside the first hollow sleeve 1, serving as a channel for injecting carbon dioxide emulsion into the coal seam. The discharge pipe 4 is located inside the hollow part inside the second hollow sleeve 2, used to discharge methane gas, carbon dioxide gas, and accumulated water from the coal seam. One-way valves 5 are respectively installed on the injection pipe 3 and the discharge pipe 4 to prevent fluid backflow, avoiding pressure fluctuations and blockages caused by backflow, and ensuring unidirectional fluid flow. Filter screens 6 are respectively installed above the one-way valve 5 of the injection pipe 3 and below the one-way valve 5 of the discharge pipe 4 to filter large particles and prevent particles from clogging the pipes and one-way valves 5. The injection port packer 7 is located in the bottom gap between the injection pipe 3 and the first hollow sleeve 1, and the discharge pipe packer 8 is located in the bottom gap between the discharge pipe 4 and the second hollow sleeve 2. The injection port packer 7 and the discharge pipe packer 8 serve to seal the operation and prevent gas leakage.

[0034] In a preferred embodiment of the present invention, the signal detection module includes several supporting steel plates 9, stress sensors 10, through holes 11, and cables. The supporting steel plates 9 are evenly distributed on the wall surfaces between the injection pipe 3 and the first hollow sleeve 1, and between the drainage pipe 4 and the second hollow sleeve 2, to ensure stable support between the injection pipe 3 and the first hollow sleeve 1, and between the drainage pipe 4 and the second hollow sleeve 2. Stress sensors 10 are arranged between adjacent supporting steel plates 9, and are located on the inner wall surfaces of the first hollow sleeve 1 and the second hollow sleeve 2. The stress sensors 10 are used to monitor formation strain data and to understand the stress conditions of the underlying layers in real time. Through holes 11 are provided at the geometric center of each of the supporting steel plates 9, and the cables are connected to the stress sensors 10 through the through holes 11 to transmit the monitored formation data to the ground.

[0035] As a preferred embodiment of the present invention, such as Figure 1 and Figure 2As shown, the gas separation module includes a gas separation device 12, which includes a device body 12-1, a vacuum pump 12-2, a methane storage tank 12-3, a first valve 12-4, a methane leakage monitoring device 12-5, a methane flow sensor 12-6, a carbon dioxide storage tank 12-7, a second valve 12-8, and a carbon dioxide flow sensor 12-9.

[0036] The main body 12-1 of the gas separation device 12 is connected to the top of the discharge pipe 4 for separating the extracted gas. A suction pump 12-2 is installed on the top of the main body 12-1 to improve the desorption and flow capacity of the coalbed methane, promoting gas discharge. The right side of the main body 12-1 is connected to a methane storage tank 12-3 via a first pipeline, which stores the separated methane gas. From left to right, the first pipeline is equipped with a first valve 12-4, a methane leak monitoring device 12-5, and a methane flow sensor 12-6. Device 12-5 is used to detect gas leaks and issue an alarm to prevent methane gas leak accidents. The left side of the main body 12-1 of the device is connected to a carbon dioxide storage tank 12-7 via a second pipeline. The carbon dioxide storage tank 12-7 is used to store the separated carbon dioxide gas. A second valve 12-8 and a carbon dioxide flow sensor 12-9 are arranged sequentially from right to left on the second pipeline. The second valve 12-8 is used to control the reception and storage of carbon dioxide gas. The methane flow sensor 12-6 and the carbon dioxide flow sensor 12-9 are used to monitor the gas flow rate to ensure the safety and stability of the gas storage and transportation process.

[0037] As a preferred embodiment of the present invention, such as Figure 1 and Figure 3 As shown, the carbon dioxide emulsion preparation module includes a carbon dioxide emulsion preparation device 13, which includes a buffer tank 13-1, a pressure reducing valve 13-2, a pressure sensor 13-3, a high-pressure stirred reactor 13-4, a water pump 13-5, a chemical reagent adding device 13-6, a chemical reagent booster pump 13-7, a constant temperature water bath 13-8, a carbon dioxide emulsion storage tank 13-9, and a third valve 13-10.

[0038] The buffer tank 13-1 is connected to the carbon dioxide storage tank 12-7 via a third pipeline. A pressure reducing valve 13-2 and a pressure sensor 13-3 are installed sequentially from left to right on the third pipeline. Carbon dioxide gas enters the buffer tank 13-1 through the pressure reducing valve 13-2 and then enters the high-pressure stirred reactor 13-4. The pressure of the gas entering the high-pressure stirred reactor 13-4 can be adjusted by controlling the pressure reducing valve 13-2 to synthesize a carbon dioxide emulsion that meets the requirements for coal seam injection. The buffer tank 13-1 is connected to the top right end of the high-pressure stirred reactor 13-4 via a fourth pipeline. The top left end of the high-pressure stirred reactor 13-4 is connected to the top of the main body 12-1 via a fifth pipeline. A water pump 13-5 is installed on the fifth pipeline. The water pump 13-5 is used to extract water from the drainage pipe 4, which, after treatment, enters the high-pressure stirred reactor 13-4 through the fifth pipeline for carbon dioxide extraction. Emulsion synthesis: The bottom center of the high-pressure stirred reactor 13-4 is connected to the chemical reagent adding device 13-6 via a sixth pipeline. A chemical reagent booster pump 13-7 is installed on the sixth pipeline. The right side of the constant temperature water bath 13-8 is connected to the upper right side of the high-pressure stirred reactor 13-4, and the left side of the constant temperature water bath 13-8 is connected to one end of the bottom of the high-pressure stirred reactor 13-4, forming a water bath circulation to ensure that the carbon dioxide emulsion preparation process is within a suitable temperature range. The upper left side of the high-pressure stirred reactor 13-4 is connected to the carbon dioxide emulsion storage tank 13-9 via a seventh pipeline. The carbon dioxide emulsion storage tank 13-9 is used to receive and store the carbon dioxide emulsion synthesized by the high-pressure reactor, providing an emulsion source for subsequent injection. A third valve 13-10 is installed on the seventh pipeline, and the carbon dioxide emulsion storage tank 13-9 is connected to the injection pipe 3.

[0039] In a preferred embodiment of the present invention, the injection tube 3 includes an emulsion booster pump 3-1 and an injection tube valve 3-2, which are arranged sequentially from top to bottom on the injection tube 3.

[0040] In a preferred embodiment of the present invention, the drainage pipe 4 includes a drainage pipe booster pump 4-1, a methane concentration sensor 4-2, and a drainage valve 4-3. The drainage pipe booster pump 4-1 is located at the top of the drainage pipe 4 and is used to pressurize the fluid in the drainage pipe 4 to ensure that the fluid can be discharged smoothly. The methane concentration sensor 4-2 and the drainage valve 4-3 are arranged sequentially from top to bottom above the drainage pipe 4. The drainage valve 4-3 is used to control the drainage operation and adjust the fluid flow rate in the drainage pipe. The drainage pipe 4 is connected to the bottom of the device body 12-1 through the drainage pipe booster pump 4-1.

[0041] As a preferred embodiment of the present invention, such as Figure 1 and Figure 4 As shown, the high-pressure stirred reactor 13-4 includes a reactor water inlet 13-4-1, a reactor air inlet 13-4-2, a chemical reagent feed inlet 13-4-3, a mechanical stirrer 13-4-4, a reactor temperature sensor 13-4-5, and a reactor pressure sensor 13-4-6.

[0042] The high-pressure stirred reactor 13-4 has a reactor water inlet 13-4-1 at its top left end, which is connected to the top of the main body 12-1 via a fifth pipe. The high-pressure stirred reactor 13-4 has a reactor air inlet 13-4-2 at its top right end, which is connected to a buffer tank 13-1 via a fourth pipe. The high-pressure stirred reactor 13-4 has a chemical reagent inlet 13-4-3 at its bottom center, which is connected to a chemical reagent adding device 13-6 via a sixth pipe. The chemical reagent inlet is used to add emulsifier, water, and carbon dioxide to the high-pressure stirred reactor 13-4. Carbon is used to form a carbon dioxide emulsion with good wetting and lubrication properties. One end of the impeller rod of the mechanical agitator 13-4-4 is located at the top center of the high-pressure stirred reactor 13-4, and one end of the blade of the mechanical agitator 13-4-4 extends into the interior of the high-pressure stirred reactor 13-4. The reactor temperature sensor 13-4-5 and the reactor pressure sensor 13-4-6 are respectively located at the top two ends of the high-pressure stirred reactor 13-4. The reactor temperature sensor 13-4-5 and the reactor pressure sensor 13-4-6 are used to monitor the temperature and pressure of the fluid inside the high-pressure stirred reactor 13-4 in real time, providing data support for the safe and stable operation of the entire device, so as to adjust the operating parameters in a timely manner.

[0043] A method of using a carbon dioxide emulsion carbon sequestration and displacement device for coalbed methane includes the following steps:

[0044] S1. Arrangement of mining wells: First, the location, depth and fracture distribution of the coal seam are determined through geological exploration. Well drilling operations are carried out in the fractured and soft coal seam. Injection wells and drainage wells are arranged. Hollow casings are lowered and cement is injected to solidify the wells. The wells pass through the rock layer from the surface to reach the various locations of the coal seam. Drilling operations are stopped after completion.

[0045] S2. Pipeline section layout: The injection pipe 3 is lowered along the hollow section of the inner interlayer of the first hollow sleeve 1. When the injection pipe 3 reaches the bottom of the injection well, it is stopped. The pipe section is sealed using the injection port packer 7 and the production port packer 8 to seal the gaps between the first hollow sleeve 1 and the injection pipe 3, and between the second hollow sleeve and the drainage pipe 4. The injection pipe 3 and the drainage pipe 4 are connected by a high-pressure one-way valve 5. One end of the drainage pipe 4 is lowered from the drainage well, and the other end is higher than the drainage well and connected to the gas-liquid separation device 12. After installing the stress sensor 10, the supporting steel plate 9 is welded. Then, the cable is lowered through the through hole 11 and connected to the stress sensor 10 to collect formation data.

[0046] S3. Initial Drainage: Following the above steps, the initial coalbed methane extraction is performed. First, ensure all valves are initially closed. Then, turn on the drainage pipe booster pump 4-1 connected to the drainage pipe 4, and turn on the main body 12-1 and extraction pump 12-2 of the gas-liquid separator 12. Gradually open the first valve 12-4 and the second valve 12-8 to perform the initial coalbed methane gas separation. At this point, the coalbed methane in the collection area has undergone one extraction, and the separated methane and carbon dioxide gases are stored in the methane storage tank 12-3 and the carbon dioxide storage tank 12-7. Observe the methane flow rate in the drainage pipe 4. When the flow rate and concentration are less than 0.5%, close the drainage valve 4-3, the first valve 12-4, and the second valve 12-8 to complete the initial coalbed methane collection.

[0047] S4. Carbon Dioxide Emulsion Synthesis and Circulation: After completing the initial coalbed methane extraction, first open the third valve 13-10 and the high-pressure stirred reactor 13-4. Inject the separated and purified carbon dioxide and pumped water into the high-pressure stirred reactor 13-4 through the fourth and fifth pipelines, respectively. The collected and separated carbon dioxide gas enters the buffer tank 13-1 from the carbon dioxide storage tank 12-7 through the third pipeline, and then enters the high-pressure stirred reactor 13-4 through the fourth pipeline. Open the pressure reducing valve 13-2 to adjust the carbon dioxide gas pressure to the set value of 14 MPa. Simultaneously, start the constant temperature water bath 13-8. The temperature inside the high-pressure stirred reactor 13-4 is adjusted to a set value of 50-95℃. Inside the reactor 13-4, a mechanical stirring paddle 13-4-4 is used to stir the mixture at a speed of 500-1000 rpm to achieve high-pressure shearing. An emulsifier, TW80 nonionic surfactant, is added to the reactor 13-4 via a chemical reagent adding device 13-6. The emulsifier is typically a TW80 nonionic surfactant with a concentration of 0.5-8% by mass. Under the set temperature, pressure, and stirring conditions, stirring is continued for 10-40 minutes to generate a carbon dioxide emulsion with carbon dioxide as the continuous phase and water as the dispersed phase. The volume fraction of carbon dioxide in the generated emulsion is typically 80-95%, and its viscosity is much higher than that of pure carbon dioxide. Finally, the generated carbon dioxide emulsion is transported to a carbon dioxide emulsion storage tank 13-9 via a seventh pipeline for storage. As needed, it can be injected into the target formation via injection pipe 3 for subsequent coalbed methane extraction or other applications.

[0048] S5. Displacement and Carbon Dioxide Sequestration: Open the carbon dioxide emulsion storage tank 13-9 and injection pipe valve 3-2, and start the emulsion booster pump 3-1. The carbon dioxide emulsion enters the bottom of the collection area from the carbon dioxide emulsion storage tank 13-9 via the emulsion booster pump and injection pipe 3 to carry out the displacement work of carbon dioxide-methane adsorption and desorption. According to the estimated flow rate and displacement time based on the pore volume, after injecting a certain amount of carbon dioxide emulsion, maintain the displacement reaction for a long time, and close the carbon dioxide emulsion storage tank 13-9, injection pipe valve 3-2 and emulsion booster pump 3-1 to promote coalbed methane displacement. After the displacement is completed, open the drainage valve 4-3, the first valve 12-4 and the second valve 12-8, and carry out the cycle of coalbed methane collection, carbon dioxide emulsion synthesis and carbon dioxide emulsion injection according to the drainage process in step S3.

[0049] S6. After completing the above work, determine the number of cycles based on the previous displacement efficiency; perform well sealing, use a sealing device to plug the wellhead, and install a methane leakage monitoring device 12-5.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can still adjust the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Therefore, 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 also intends to include these modifications and variations.

Claims

1. A carbon dioxide emulsion carbon sequestration and displacement device for coalbed methane, characterized in that: The system includes an underground system module, a signal detection module, a gas separation module, and a carbon dioxide emulsion preparation module. The underground system module is connected to the gas separation module and the carbon dioxide emulsion preparation module. The underground system module is used for coalbed methane extraction operations and carbon dioxide geological storage. The signal detection module is installed on the underground system module. The gas separation module is connected to the carbon dioxide emulsion preparation module. The gas separation module is used to collect, separate, and simultaneously gather gas. The carbon dioxide emulsion module is used to prepare displacement agents to improve the recovery rate of coalbed methane.

2. The carbon dioxide emulsion carbon sequestration and displacement device for coalbed methane according to claim 1, characterized in that: The underground system module includes a first hollow sleeve (1), a second hollow sleeve (2), an injection pipe (3), a drainage pipe (4), a one-way valve (5), a filter screen (6), an injection port packer (7), and a production pipe packer (8). The first hollow sleeve (1) is lowered along the injection well to the bottom of the well and its height is the same as the injection well. The second hollow sleeve (2) is lowered along the drainage well to the bottom of the well and its height is the same as the drainage well. Cement is installed between the injection well and the first hollow sleeve (1), and between the drainage well and the second hollow sleeve (2) for well cementing. The injection pipe (3) is lowered along the first hollow sleeve (1) and the second hollow sleeve (2). The hollow part of the hollow sleeve (1) is lowered into the coal seam. The drainage pipe (4) is set in the hollow part of the second hollow sleeve (2). One-way valves (5) are respectively set on the injection pipe (3) and the drainage pipe (4). Filter screens (6) are respectively set above the one-way valve (5) of the injection pipe (3) and below the one-way valve (5) of the drainage pipe (4). The injection port packer (7) is set in the bottom gap between the injection pipe (3) and the first hollow sleeve (1). The extraction pipe packer (8) is set in the bottom gap between the drainage pipe (4) and the second hollow sleeve (2).

3. The carbon dioxide emulsion carbon sequestration and displacement device for coalbed methane according to claim 2, characterized in that: The signal detection module includes several supporting steel plates (9), stress sensors (10), through holes (11), and cables. Several supporting steel plates (9) are evenly distributed on the wall between the injection pipe (3) and the first hollow sleeve (1), and between the discharge pipe (4) and the second hollow sleeve (2). Stress sensors (10) are arranged between adjacent supporting steel plates (9). The stress sensors (10) are arranged on the inner wall of the first hollow sleeve (1) and the second hollow sleeve (2). Through holes (11) are arranged at the geometric center of the several supporting steel plates (9). The cables are connected to the stress sensors (10) through the through holes (11).

4. The carbon dioxide emulsion carbon sequestration and displacement device for coalbed methane according to claim 3, characterized in that: The gas separation module includes a gas separation device (12), which includes a device body (12-1), a vacuum pump (12-2), a methane storage tank (12-3), a first valve (12-4), a methane leakage monitoring device (12-5), a methane flow sensor (12-6), a carbon dioxide storage tank (12-7), a second valve (12-8), and a carbon dioxide flow sensor (12-9). The main body (12-1) of the gas separation device (12) is connected to the top of the discharge pipe (4). A gas pump (12-2) is installed on the top of the main body (12-1). The right side of the main body (12-1) is connected to the methane storage tank (12-3) through a first pipeline. A first valve (12-4), a methane leakage monitoring device (12-5), and a methane flow sensor (12-6) are installed on the first pipeline from left to right. The left side of the main body (12-1) is connected to the carbon dioxide storage tank (12-7) through a second pipeline. A second valve (12-8) and a carbon dioxide flow sensor (12-9) are installed on the second pipeline from right to left.

5. The carbon dioxide emulsion carbon sequestration and displacement device for coalbed methane according to claim 4, characterized in that: The carbon dioxide emulsion preparation module includes a carbon dioxide emulsion preparation device (13), which includes a buffer tank (13-1), a pressure reducing valve (13-2), a pressure sensor (13-3), a high-pressure stirred reactor (13-4), a water pump (13-5), a chemical reagent adding device (13-6), a chemical reagent booster pump (13-7), a constant temperature water bath (13-8), a carbon dioxide emulsion storage tank (13-9), and a third valve (13-10). The buffer tank (13-1) is connected to the carbon dioxide storage tank (12-7) via a third pipeline. A pressure reducing valve (13-2) and a pressure sensor (13-3) are installed sequentially from left to right on the third pipeline. The buffer tank (13-1) is connected to the top right end of the high-pressure stirred reactor (13-4) via a fourth pipeline. The top left end of the high-pressure stirred reactor (13-4) is connected to the top of the main body (12-1) via a fifth pipeline. A water pump (13-5) is installed on the fifth pipeline. The bottom center of the high-pressure stirred reactor (13-4) is connected to the chemical... A reagent adding device (13-6) is connected, and a chemical reagent booster pump (13-7) is installed on the sixth pipeline. The right side of the constant temperature water bath (13-8) is connected to the upper right side of the high pressure stirred reactor (13-4), and the left side of the constant temperature water bath (13-8) is connected to one end of the bottom of the high pressure stirred reactor (13-4). The upper left side of the high pressure stirred reactor (13-4) is connected to the carbon dioxide emulsion storage tank (13-9) through the seventh pipeline. A third valve (13-10) is installed on the seventh pipeline, and the carbon dioxide emulsion storage tank (13-9) is connected to the injection pipe (3).

6. The carbon dioxide emulsion carbon sequestration and displacement device for coalbed methane according to claim 5, characterized in that: The injection tube (3) includes an emulsion booster pump (3-1) and an injection tube valve (3-2), which are arranged sequentially from top to bottom on the injection tube (3).

7. The carbon dioxide emulsion carbon sequestration and displacement device for coalbed methane according to claim 6, characterized in that: The drainage pipe (4) includes a drainage pipe booster pump (4-1), a methane concentration sensor (4-2), and a drainage valve (4-3). The drainage pipe booster pump (4-1) is located at the top of the drainage pipe (4). The methane concentration sensor (4-2) and the drainage valve (4-3) are arranged sequentially from top to bottom above the drainage pipe (4). The drainage pipe (4) is connected to the bottom of the device body (12-1) through the drainage pipe booster pump (4-1).

8. The carbon dioxide emulsion carbon sequestration and displacement device for coalbed methane according to claim 7, characterized in that: The high-pressure stirred reactor (13-4) includes a reactor water inlet (13-4-1), a reactor air inlet (13-4-2), a chemical reagent feed inlet (13-4-3), a mechanical stirrer (13-4-4), a reactor temperature sensor (13-4-5), and a reactor pressure sensor (13-4-6); The high-pressure stirred reactor (13-4) has a reactor water inlet (13-4-1) at its top left end, which is connected to the top of the main body (12-1) via a fifth pipe. The high-pressure stirred reactor (13-4) has a reactor air inlet (13-4-2) at its top right end, which is connected to a buffer tank (13-1) via a fourth pipe. The high-pressure stirred reactor (13-4) has a chemical reagent inlet (13-4) at its bottom center. -3), the chemical reagent inlet (13-4-3) is connected to the chemical reagent adding device (13-6) through the sixth pipeline, one end of the paddle rod of the mechanical stirring paddle (13-4-4) is set at the top center of the high-pressure stirred reactor (13-4), one end of the blade of the mechanical stirring paddle (13-4-4) extends into the interior of the high-pressure stirred reactor (13-4), and the reactor temperature sensor (13-4-5) and reactor pressure sensor (13-4-6) are respectively set at the top two ends of the high-pressure stirred reactor (13-4).

9. The method of using a carbon dioxide emulsion carbon sequestration and displacement coalbed methane device according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Arrangement of mining wells: First, the location, depth and fracture distribution of the coal seam are determined through geological exploration. Well drilling operations are carried out in the fractured and soft coal seam. Injection wells and drainage wells are arranged. Hollow casings are lowered and cement is injected to cement the wells. The wells pass through the rock layer from the surface to reach the various locations of the coal seam. Drilling operations are stopped after completion. S2. Pipeline section arrangement: The injection pipe (3) is lowered along the hollow part of the inner interlayer of the first hollow sleeve (1). When the injection pipe (3) reaches the bottom of the injection well, it is stopped. The pipe section is sealed with the injection port packer (7) and the production port packer (8) to seal the gap between the first hollow sleeve (1) and the injection pipe (3), and between the second hollow sleeve and the drainage pipe (4). The injection pipe (3) and the drainage pipe (4) are equipped with high-pressure one-way valves (5). One end of the drainage pipe (4) is lowered from the drainage well, and the other end is higher than the drainage well and connected to the gas-liquid separation device (12). After installing the stress sensor (10), the support steel plate (9) is welded. Then, the cable is lowered through the through hole (11) and connected to the stress sensor (10) to collect formation data. S3. Initial Drainage: Through the above work, the initial coalbed methane extraction is carried out. First, ensure that all valves are in the closed state in the initial state; turn on the drainage pipe booster pump (4-1) connected to the drainage pipe (4), turn on the main body (12-1) and the gas pump (12-2) of the gas-liquid separation device (12), and gradually open the first valve (12-4) and the second valve (12-8) to carry out the first gas separation of coalbed methane. At this time, the coalbed methane in the collection area has been harvested once, and the separated methane gas and carbon dioxide gas are stored in the methane storage tank (12-3) and the carbon dioxide storage tank (12-7). Observe the methane flow rate in the drainage pipe (4). When the flow rate and concentration are less than 0.5%, close the drainage valve (4-3), the first valve (12-4), and the second valve (12-8) to complete the initial collection of coalbed methane. S4. Carbon Dioxide Emulsion Synthesis and Circulation: After completing the initial coalbed methane extraction, first open the third valve (13-10) and the high-pressure stirred reactor (13-4), and inject the separated and purified carbon dioxide and pumped water into the high-pressure stirred reactor (13-4) through the fourth and fifth pipelines, respectively; the collected and separated carbon dioxide gas enters the buffer tank (13-1) from the carbon dioxide storage tank (12-7) through the third pipeline, and then enters the high-pressure stirred reactor (13-4) through the fourth pipeline. Open the pressure reducing valve (13-2) to adjust the pressure of the carbon dioxide gas to the set value of 14MPa. At the same time, start the constant temperature water bath (13-8). The temperature inside the high-pressure stirred reactor (13-4) is adjusted to a set value of 50-95℃. Inside the high-pressure stirred reactor (13-4), the reactor is stirred at a speed of 500-1000 rpm by a mechanical stirring paddle (13-4-4) to achieve high-pressure shearing. The emulsifier is added to the high-pressure stirred reactor (13-4) through a chemical reagent adding device (13-6). The emulsifier is a TW80 nonionic surfactant with a concentration of 0.5-8% (mass fraction). Under the set temperature, pressure and stirring conditions, the reactor is stirred continuously for 10-40 minutes to generate a carbon dioxide emulsion with carbon dioxide as the continuous phase and water as the dispersed phase. The volume fraction of carbon dioxide in the generated emulsion is generally 80-95%, and its viscosity is much higher than that of pure carbon dioxide. Finally, the generated carbon dioxide emulsion is transported to the carbon dioxide emulsion storage tank (13-9) through the seventh pipeline for storage. As needed, it is injected into the target formation through the injection pipe (3) for subsequent coalbed methane mining or other applications. S5. Displacement and Carbon Dioxide Sequestration: Open the carbon dioxide emulsion storage tank (13-9) and injection pipe valve (3-2), and start the emulsion booster pump (3-1). The carbon dioxide emulsion enters the bottom of the collection area from the carbon dioxide emulsion storage tank (13-9) through the emulsion booster pump and injection pipe (3) to carry out the displacement work of adsorption and desorption of carbon dioxide and methane. According to the expected flow rate and displacement time based on the pore volume, after injecting a certain amount of carbon dioxide emulsion, maintain the displacement reaction for a long time, close the carbon dioxide emulsion storage tank (13-9), injection pipe valve (3-2) and emulsion booster pump (3-1) to promote coalbed methane displacement. After the displacement is completed, open the discharge valve (4-3), the first valve (12-4), and the second valve (12-8). The coalbed methane collection, carbon dioxide emulsion synthesis and carbon dioxide emulsion injection work are carried out in a cycle according to the discharge process of step S3. S6. After completing the above work, determine the number of cycles based on the previous displacement efficiency; perform well sealing, use a sealing device to plug the wellhead, and install a methane leakage monitoring device (12-5).

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