A gas boosting system

Abstract

The utility model discloses a kind of gas promotes extraction system, it is related to coal seam gas extraction technical field, including the water injection gas injection borehole and gas extraction borehole being set in the inside of coal seam, the inside of water injection gas injection borehole and gas extraction borehole is equipped with cement slurry hole sealing material, the side of water injection gas injection borehole is provided with the displacement operation mechanism for carrying out water injection gas injection alternation operation, the side of gas extraction borehole is provided with the gas extraction mechanism for separating gas-liquid.The utility model effectively overcomes the limitation of single displacement mode by alternately injecting water and gas, can displace free gas in coal seam fissure by high-pressure water, then replace gas by using competitive adsorption effect of gas, simultaneously displace water in fissure, form new gas flow path, avoid to close flow path due to the plugging effect of water, cyclic alternation water injection gas injection can expand coal seam fissure network, improve gas extraction rate.

Description

Technical Field

[0001] This utility model relates to the field of coal seam gas extraction technology, specifically a gas extraction system. Background Technology

[0002] Coal seam gas is characterized by low saturation, low permeability, low reservoir pressure, and high adsorption. Gas drainage is a fundamental technical measure for gas disaster prevention and control. Currently, to improve gas drainage efficiency, displacement drainage technology has been proposed. Commonly used displacement technologies can be divided into two categories: one is water injection to displace gas, and the other is gas injection to displace gas.

[0003] Water injection for gas displacement involves injecting water into the coal seam to displace free gas within fractures, achieving efficient extraction. This is primarily achieved through alternating water injection and extraction holes. High-pressure water displaces the gas and desorbs it, increasing the gas volume fraction and flow rate of adjacent extraction holes. Initial water injection can achieve good results, but due to water blockage and water-locking effects, extraction efficiency significantly decreases after the initial displacement, failing to meet expectations. Gas injection for displacement utilizes the strong adsorption capacity of gas to compete with methane in the micropores of the coal matrix for adsorption. After a period, the adsorbed methane in the coal can be displaced. However, because gas injection affects the gas extraction concentration, a certain degree of mixing occurs, resulting in low displacement efficiency and hindering subsequent processing. In summary, both technologies have problems that affect the efficiency of coal seam gas extraction.

[0004] Based on this, a gas extraction system is now provided that can eliminate the drawbacks of existing technical solutions. Utility Model Content

[0005] The purpose of this invention is to provide a gas extraction system to solve the problem of low efficiency in coal seam gas extraction in the prior art.

[0006] To achieve the above objectives, this utility model provides the following technical solution:

[0007] A gas extraction system includes water injection and gas injection boreholes and gas extraction boreholes drilled inside the coal seam. The interior of the water injection and gas injection boreholes and the gas extraction boreholes are filled with cement slurry sealing material. A displacement operation mechanism for alternating water injection and gas injection is provided on one side of the water injection and gas injection borehole, and a gas extraction mechanism for separating gas and liquid is provided on one side of the gas extraction borehole.

[0008] The displacement operation mechanism includes a displacement operation pipeline. One end of the displacement operation pipeline passes through the cement slurry sealing material and extends into the water injection and air injection borehole. The other end of the displacement operation pipeline is fixedly connected to the outlet end of a three-way valve. The two inlet ends of the three-way valve are respectively connected to a gas pulse injection component and a pulse water injection component. A flow sensor is provided on the displacement operation pipeline.

[0009] Preferably, the gas extraction mechanism includes a gas extraction pipeline. One end of the gas extraction pipeline passes through the cement slurry sealing material and extends into the gas extraction borehole. The other end of the gas extraction pipeline is connected to a connecting pipe, and the other end of the connecting pipe is connected to a gas separator. A gas output pipeline is provided on one side of the gas separator. A water guide pipeline is connected to the connecting pipe. The other end of the water guide pipeline is connected to a water collection tank. A drain pipe is provided at the bottom of the water collection tank. The water collection tank and the gas separator are connected by a gas guide pipeline. A valve body is provided on the outside of the connecting pipe, the water guide pipeline, the drain pipe, and the gas guide pipeline.

[0010] Preferably, the gas pulse injection assembly includes an injection pipeline connected to one of the inlet ends of a three-way valve, a high-pressure injection pump is provided on the injection pipeline, a gas supply pipeline is fixedly connected to the input end of the high-pressure injection pump, the other end of the gas supply pipeline is connected to a gas storage tank, and a gas shut-off valve is provided on both the gas supply pipeline and the injection pipeline.

[0011] Preferably, the pulsating water injection assembly includes a water injection pipeline connected to the other inlet end of the three-way valve, a high-pressure water injection pump is installed on the water injection pipeline, a water supply pipeline is fixedly connected to the input end of the high-pressure water injection pump, the other end of the water supply pipeline is connected to a water storage tank, and a liquid shut-off valve is provided on both the water injection pipeline and the water supply pipeline.

[0012] Preferably, the gas inside the gas storage tank is nitrogen.

[0013] Preferably, the gas separator includes an adsorption tower, which adopts a dual-tower parallel structure. The adsorption tower is filled with molecular sieve material for adsorbing methane. The inlet end of the adsorption tower is connected to a connecting pipe and a gas guide pipe. A nitrogen outlet is provided on one side of the gas separator, and the nitrogen outlet is connected to a gas storage tank through a circulation pipe.

[0014] Preferably, the inside of the water collection tank is equipped with a filter screen for filtering coal dust and impurities, and the air guide pipe is located below the filter screen.

[0015] Preferably, both the air guide pipe and the connecting pipe are equipped with negative pressure pumps.

[0016] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0017] This invention effectively overcomes the limitations of a single displacement method by alternately injecting water and gas, utilizing the synergistic effect of the different physical properties of the two media. It can displace free gas in coal seam fractures with high-pressure water, and then replace adsorbed gas in coal seam micropores with the competitive adsorption effect of gas, while simultaneously displacing water in the fractures to form new gas flow paths. This avoids the blockage effect of water on the gas flow paths. The cyclical alternating water and gas injection can expand the coal seam fracture network and improve the gas extraction rate. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0019] Figure 2 This is a schematic diagram of the displacement mechanism of this utility model.

[0020] Figure 3 This is a schematic diagram of the gas extraction mechanism of this utility model.

[0021] Figure 4 This is a schematic diagram of the gas separation component of this utility model.

[0022] Figure label annotations: 1. Coal seam; 2. Water and gas injection borehole; 3. Gas drainage borehole; 4. Cement slurry sealing material; 5. Displacement operation pipeline; 6. Three-way valve; 7. Flow sensor; 8. Gas drainage pipeline; 9. Connecting pipe; 10. Gas separator; 10. Adsorption tower; 101. Molecular sieve material; 102. Nitrogen outlet; 103. Circulation pipeline; 104. Gas output pipeline; 11. Water guide pipeline; 12. Water collection tank; 13. Drainage pipe; 14. Gas guide pipeline; 15. Gas injection pipeline; 16. High-pressure gas injection pump; 17. Gas supply pipeline; 18. Gas storage tank; 19. Water injection pipeline; 20. High-pressure water injection pump; 21. Water supply pipeline; 22. Water storage tank; 23. Filter screen; 24. Negative pressure pump; 25. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments.

[0024] In this embodiment, as Figures 1-4As shown, a gas extraction system includes a water injection and gas injection borehole 2 and a gas extraction borehole 3, both located within a coal seam 1. The water injection and gas injection borehole 2 and the gas extraction borehole 3 are both located on the surface of the coal seam 1. The water injection and gas injection borehole 2 is used to inject gas into the coal seam 1. Multiple water injection and gas injection through-holes are provided at the bottom of the water injection and gas injection borehole 2 to allow the injected gas and water to diffuse evenly into the coal seam 1. The gas extraction borehole 3 is located on one side of the water injection and gas injection borehole 2 and is used to extract gas. The displaced gas has multiple extraction holes at its bottom to allow it to enter the gas extraction pipeline 8. Both the water injection / gas injection borehole 2 and the gas extraction borehole 3 are equipped with cement slurry sealing material 4 for sealing the boreholes. A displacement mechanism for alternating water and gas injection operations is located on one side of the water injection / gas injection borehole 2. During the pulsed water injection stage, high-pressure water impacts the coal seam fractures in the form of pulse waves, displacing free gas, and pulsed gas injection... During the initial stage, nitrogen gas seeps into the fractures under pressure fluctuations. The gas can displace the water in the fractures of coal seam 1, forming a new gas flow path. Through competitive adsorption, it replaces the adsorbed gas. After the water in the fractures is displaced, water injection is performed again to displace the gas, thus achieving a water-gas injection cycle displacement effect. The alternating pulsating pressure can avoid the water-locking effect, continuously expanding the fracture channel and forcing the original fractures in coal seam 1 to expand. On the basis of the original fractures, new fracture areas are formed, expanding the gas collection area and thus improving the gas extraction effect. By alternating water and gas injection combined with gas circulation, the gas desorption efficiency is significantly improved. A gas extraction mechanism for separating gas and liquid is set on one side of the gas extraction borehole 3. When the coal seam 1 is saturated with water, water will gush out in the gas extraction borehole 3. The water collection tank 13 is used to filter and separate the substances extracted from the coal seam 1, realizing the separation of gas, solid and liquid operations, which facilitates the subsequent gas extraction work.

[0025] The displacement operation mechanism includes a displacement operation pipeline 5. One end of the displacement operation pipeline 5 passes through the cement slurry sealing material 4 and extends into the water injection and air injection borehole 2. The other end of the displacement operation pipeline 5 is fixedly connected to the outlet end of the three-way valve 6. The two inlet ends of the three-way valve 6 are respectively connected to the gas pulse injection component and the pulse water injection component to facilitate alternating water injection and air injection operations. The displacement operation pipeline 5 is equipped with a flow sensor 7. During the transportation process, it is necessary to monitor and measure the gas and liquid to calculate the flow rate of the medium so as to adjust the operating parameters in a timely manner.

[0026] Among them, such as Figure 1 and Figure 3As shown, the gas extraction mechanism includes a gas extraction pipeline 8. One end of the gas extraction pipeline 8 passes through the cement grout sealing material 4 and extends into the gas extraction borehole 3. The other end of the gas extraction pipeline 8 is connected to a connecting pipe 9, and the other end of the connecting pipe 9 is connected to a gas separator 10 to facilitate the separation of gas and injection gas in the gas mixture, thereby improving the gas extraction efficiency. A gas output pipeline 11 is provided on one side of the gas separator 10 to facilitate the transportation of the separated gas to other equipment for subsequent operations. A water guide pipeline 12 is connected to the connecting pipe 9, and the other end of the water guide pipeline 12 is connected to a water collection tank 13. A level gauge is installed inside the water collection tank 13. When the level gauge detects that the water level in the water collection tank 13 is low, a water level indicator is installed. When the pressure is high, the valves at the water pipe 12 and the gas pipe 15 can be closed to discharge the water in time, and the extracted gas can enter the gas separator 10 through the connecting pipe 9 to avoid affecting the negative pressure effect and thus affecting the extraction operation. The bottom of the water collection tank 13 is equipped with a drain pipe 14 to facilitate the discharge of water. The water collection tank 13 and the gas separator 10 are connected by the gas pipe 15. The water collection tank 13 retains the coal dust and liquid extracted from the gas extraction pipeline 8 inside it. The separated gas is transported to the gas separator 10 through the gas pipe 15. The connecting pipe 9, the water pipe 12, the drain pipe 14 and the gas pipe 15 are all equipped with valves on the outside to facilitate the control of flow rate and opening / closing status.

[0027] Among them, such as Figure 1 and Figure 2 As shown, the gas pulse injection assembly includes an injection pipeline 16 connected to one of the inlet ends of the three-way valve 6. A high-pressure injection pump 17 is installed on the injection pipeline 16. The high-pressure injection pump 17 is existing technology, which facilitates the delivery of gas into the injection pipeline 16. The injection pressure can be adjusted according to the actual scenario. The input end of the high-pressure injection pump 17 is fixedly connected to a gas supply pipeline 18. The other end of the gas supply pipeline 18 is connected to a gas storage tank 19. Both the gas supply pipeline 18 and the injection pipeline 16 are equipped with gas shut-off valves to control the flow rate and open / closed state.

[0028] Among them, such as Figure 1 and Figure 2 As shown, the pulsating water injection assembly includes a water injection pipeline 20 connected to the other inlet end of the three-way valve 6. A high-pressure water injection pump 21 is installed on the water injection pipeline 20. The high-pressure water injection pump 21 is existing technology. The water injection pressure can be adjusted according to the actual scenario to facilitate the delivery of water to the inside of the water injection pipeline 20. The water enters the coal seam 1 under high pressure, displacing the free gas in the fractures, so that the gas can be pushed to the gas extraction borehole 3 and extracted through the gas extraction pipeline 8. The input end of the high-pressure water injection pump 21 is fixedly connected to a water supply pipeline 22. The other end of the water supply pipeline 22 is connected to a water storage tank 23. Both the water injection pipeline 20 and the water supply pipeline 22 are equipped with liquid shut-off valves to control the flow rate and opening / closing status.

[0029] Among them, such as Figure 1 and Figure 2 As shown, the gas inside the gas storage tank 19 is nitrogen. Nitrogen is an inert gas with relatively wide availability and is relatively safe. It can be used to compete with methane on the surface of the micropores of the coal matrix to displace the methane and enhance the competitive adsorption and displacement effect.

[0030] Among them, such as Figure 4 As shown, the gas separator 10 includes an adsorption tower 101, which adopts a dual-tower parallel structure. A heater and a switching controller are installed on the outside of the adsorption tower 101, both existing technologies, which can automatically control the adsorption and desorption processes, operating according to a preset time and program to achieve continuous separation. The temperature of the adsorption tower can be increased by electric heating or steam heating, for example, by using an electric heating element wound around the outer wall of the adsorption tower, automatically adjusting the heating power according to the set temperature. To ensure safety, a gas leak monitoring alarm, pressure relief valve, and temperature protection device can be installed. Regular maintenance and safety inspections of the equipment are performed to reduce the probability of danger caused by gas leaks and equipment damage. The two towers alternately perform adsorption and desorption operations through the switching controller. The adsorption pressure is 0.3~0.5MPa, and the desorption temperature is 100~120℃, so that when one adsorption tower 101 is adsorbing, the other adsorption tower 101 is in a desorption state. 01 is set as tower A and tower B. Switching the controller to open and close the corresponding valve body allows the gas in the mixed gas to be adsorbed by the molecular sieve material 102, and the nitrogen is discharged through the nitrogen outlet 103. The adsorption time can be set to 10-15 minutes. Switching the controller to open and close the corresponding valve body and heater of tower B allows the gas in the molecular sieve material 102 to be desorbed and discharged through the gas output pipeline 11. The desorption time can be set to 5-8 minutes to achieve continuous separation. The interior of the adsorption tower 101 is filled with molecular sieve material 102 for adsorbing gas. The molecular sieve material 102 can be zeolite molecular sieve, such as 5A molecular sieve or 13X molecular sieve, depending on the actual scenario. It preferentially adsorbs gas and allows nitrogen to pass through. The inlet end of the adsorption tower 101 is connected to the connecting pipe 9 and the gas guide pipe 15. A nitrogen outlet 103 is set on one side of the gas separator 10. The nitrogen outlet 103 is connected to the gas storage tank 19 through the circulation pipeline 104 to form a closed loop and reduce the cost of inert gas replenishment.

[0031] Among them, such as Figure 3 As shown, the inside of the water collection tank 13 is equipped with a filter screen 24 for filtering coal dust and impurities. The top of the outer side of the water collection tank 13 is provided with a door corresponding to the filter screen 24, which facilitates the cleaning of the filter screen 24 and avoids contamination of the adsorption material. The gas guide pipe 15 is located below the filter screen 24, which facilitates the separation of solids from gases and liquids. The liquid is stored inside the water collection tank 13, which enables the separation of liquids and gases for subsequent processing.

[0032] Among them, such as Figure 3 As shown, both the gas guide pipe 15 and the connecting pipe 9 are equipped with negative pressure pumps 25. The negative pressure pumps 25 generate negative pressure in the gas extraction pipe 8. The extraction negative pressure can be adjusted according to the actual environment, for example, it can be controlled at about 13~20 kPa, so that the gas in the coal seam 1 flows to the gas extraction borehole 3 under the action of pressure difference. The extracted gas mixture is transported to the inside of the connecting pipe 9 through the gas extraction pipe 8.

[0033] In operation, water is first injected into the water-injection and gas-injection borehole 2. The high-pressure water pump 21 is then started to transport the water from the storage tank 23 to the water injection pipeline 20. The water is then diffused into the borehole 2 via the three-way valve 6. This water injection displaces the free gas in the coal seam 1, improving extraction efficiency. When the water injection in the coal seam 1 reaches saturation (i.e., water gushes out from the gas extraction borehole 3 on one side of the water-injection and gas-injection borehole 2), the water blocks the gas flow path, and the efficiency of water displacement of the gas rapidly increases. The flow rate drops rapidly, the liquid shut-off valve is closed, the gas shut-off valve is opened, and the gas injection operation begins. The gas can displace the water in the fissures of coal seam 1, forming a new gas flow path. When the water in the fissures of coal seam 1 is completely displaced (i.e., there is no water inflow inside the gas extraction borehole 3 on one side of the water injection and gas injection borehole 2), the gas shut-off valve is closed, the liquid shut-off valve is opened, and water is injected to displace the gas, thereby achieving the water injection-gas injection cycle displacement effect, expanding the gas collection area, and then achieving high-efficiency gas extraction through the gas extraction pipeline 8.

[0034] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A gas extraction system, comprising a water injection and gas injection borehole (2) and a gas extraction borehole (3) opened inside a coal seam (1), wherein the interior of the water injection and gas injection borehole (2) and the gas extraction borehole (3) is provided with cement slurry sealing material (4), a displacement operation mechanism for alternating water injection and gas injection is provided on one side of the water injection and gas injection borehole (2), and a gas extraction mechanism for separating gas and liquid is provided on one side of the gas extraction borehole (3). Its features are, The displacement operation mechanism includes a displacement operation pipeline (5), one end of which passes through the cement slurry sealing material (4) and extends into the water injection and air injection borehole (2). The other end of the displacement operation pipeline (5) is fixedly connected to the outlet end of a three-way valve (6). The two inlet ends of the three-way valve (6) are respectively connected to a gas pulse injection component and a pulse water injection component. A flow sensor (7) is provided on the displacement operation pipeline (5).

2. The gas extraction system according to claim 1, characterized in that, The gas extraction mechanism includes a gas extraction pipeline (8), one end of which passes through the cement grout sealing material (4) and extends into the gas extraction borehole (3). The other end of the gas extraction pipeline (8) is connected to a connecting pipe (9), and the other end of the connecting pipe (9) is connected to a gas separator (10). A gas output pipeline (11) is provided on one side of the gas separator (10). A water guide pipeline (12) is connected to the connecting pipe (9). The other end of the water guide pipeline (12) is connected to a water collection tank (13). A drain pipe (14) is provided at the bottom of the water collection tank (13). The water collection tank (13) and the gas separator (10) are connected by a gas guide pipeline (15). A valve body is provided on the outside of the connecting pipe (9), the water guide pipeline (12), the drain pipe (14), and the gas guide pipeline (15).

3. The gas extraction system according to claim 2, characterized in that, The gas pulse injection assembly includes an injection pipeline (16) connected to one of the inlet ends of a three-way valve (6). A high-pressure injection pump (17) is installed on the injection pipeline (16). A gas supply pipeline (18) is fixedly connected to the input end of the high-pressure injection pump (17). The other end of the gas supply pipeline (18) is connected to a gas storage tank (19). Both the gas supply pipeline (18) and the injection pipeline (16) are equipped with gas shut-off valves.

4. The gas extraction system according to claim 1, characterized in that, The pulsating water injection assembly includes a water injection pipeline (20) connected to the other inlet end of a three-way valve (6). A high-pressure water injection pump (21) is installed on the water injection pipeline (20). A water supply pipeline (22) is fixedly connected to the input end of the high-pressure water injection pump (21). The other end of the water supply pipeline (22) is connected to a water storage tank (23). Both the water injection pipeline (20) and the water supply pipeline (22) are equipped with liquid shut-off valves.

5. The gas extraction system according to claim 3, characterized in that, The gas inside the gas storage tank (19) is nitrogen.

6. The gas extraction system according to claim 5, characterized in that, The gas separator (10) includes an adsorption tower (101), which adopts a double-tower parallel structure. The adsorption tower (101) is filled with molecular sieve material (102) for adsorbing gas. The inlet end of the adsorption tower (101) is connected to the connecting pipe (9) and the gas guide pipe (15). A nitrogen outlet (103) is provided on one side of the gas separator (10), and the nitrogen outlet (103) is connected to the gas storage tank (19) through the circulation pipe (104).

7. The gas extraction system according to claim 2, characterized in that, The water collection tank (13) is equipped with a filter screen (24) for filtering coal dust and impurities, and the air guide pipe (15) is located below the filter screen (24).

8. The gas extraction system according to claim 2, characterized in that, Negative pressure pumps (25) are installed on both the air guide pipe (15) and the connecting pipe (9).

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