Geothermal resource comprehensive exploitation system and method in Inner Mongolia region

Abstract

The present application relates to a comprehensive exploitation system for geothermal resources in Inner Mongolia, comprising a deep geothermal energy exploitation system, an upper coal seam heat energy exploitation system and an underground water supplement system, wherein the deep geothermal energy exploitation system comprises a cold water injection well and a water return well, and a heat energy extraction device A on the ground connecting the two; the upper coal seam heat energy exploitation system comprises a cold water injection pipe, the low-temperature cold water delivered by which is sent to a mining system for dust removal and cooling, and the cold water with relatively high temperature delivered by which enters a goaf heat energy collection system, the output end of the goaf heat energy collection system is sequentially connected with a water delivery pipe, a coal seam heat energy return pipe and a ground heat energy extraction device B, and the heat energy extraction device B is connected with the cold water injection pipe after recovering heat energy; the underground water supplement system supplies water in the aquifer of the coal seam roof and floor to the goaf heat energy collection system and the geothermal energy reservoir. The present application can improve the overall resource utilization rate and maximize the exploitation energy efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of geothermal resource exploitation, in particular to a geothermal resource comprehensive exploitation system and method, which is especially suitable for Inner Mongolia region. BACKGROUND

[0002] Geothermal energy is a renewable clean energy from the deep part of the earth, which is brought to the earth's surface in the form of hot water or steam through the flow of underground water or other working medium. In the current situation of rapid economic development and energy shortage, the rational development and utilization of geothermal resources has been more and more favored by people. Geothermal power generation is the main way, and direct utilization of geothermal water for building heating, development of greenhouse agriculture and hot spring tourism has also developed rapidly. The traditional geothermal energy exploitation method is to use water as a heat transfer fluid to realize circulation underground, enter the connected fracture zone caused by artificial fracturing, water is heated after contacting with rock mass, and then returns to the ground through the production well to form a closed loop; but the supplement of clean circulating water has always been a difficult problem.

[0003] There are a certain amount of geothermal energy resources in Inner Mongolia region, and a large amount of coal resources are also deposited. In recent years, with the continuous exploitation of coal resources to the deep part, the problem of high ground temperature is caused. In order to solve the problem caused by high ground temperature, coal-geothermal water coordinated exploitation has become a hot research topic, but it usually adopts filling mining process, which causes low production efficiency and high cost; and the coordinated exploitation of coal-coal bed geothermal energy-deep pure geothermal energy has not been studied. SUMMARY

[0004] In order to solve the problem of coordinated exploitation of coal-coal bed geothermal energy-deep pure geothermal energy in Inner Mongolia region, the present application provides a geothermal resource comprehensive exploitation system, which comprises a deep geothermal energy exploitation system, an upper coal seam heat energy exploitation system and an underground water supplement system. The deep geothermal energy exploitation system comprises a cold water injection well and a water return well, and a heat energy extraction device A on the ground connecting the two. The upper coal seam heat energy exploitation system comprises a cold water injection pipe, the low temperature cold water transported by which is sent to the mining system for dust removal and cooling, and the cold water with relatively high temperature is transported into the goaf heat energy collection system. The output end of the goaf heat energy collection system is connected with a water delivery pipe, a coal seam heat energy return pipe and a ground heat energy extraction device B in sequence, and the heat energy extraction device B is connected with the cold water injection pipe after recovering heat energy. The underground water supplement system supplies water in the coal seam roof and floor aquifer to the goaf heat energy collection system and the geothermal energy reservoir.

[0005] Preferably, the cold water injection well and the water return well are connected by artificial fracturing horizontal fractures in the geothermal energy reservoir.

[0006] Preferably, the cold water injection pipe is arranged in the main shaft or the auxiliary shaft, and the coal seam heat energy return pipe is arranged in the air return well.

[0007] Preferably, the water return well is connected with non-recyclable water and recyclable water on the ground, and the output end of the recyclable water is connected with the heat energy extraction device B.

[0008] Preferably, the heat energy extraction device B is connected with the cold water injection pipe after passing through the purification device B, and the cold water with relatively high temperature after extracting heat energy is directly injected into the goaf heat energy collection system; and the low-temperature cold water cooled by the multi-stage filtering cooling pool and the cooling tower is injected into the cold water sump through the cold water injection pipe.

[0009] Preferably, the potential energy recovery device A is arranged at the lower part of the cold water injection well, and the potential energy recovery device B is arranged at the lower part of the cold water injection pipe.

[0010] Preferably, the low-temperature cold water is transferred to the mining system through the power device A after entering the cold water sump, and the water in the coal seam roof and floor aquifer is extracted by using the power device B.

[0011] Preferably, the application further comprises a power storage and supply device, the potential energy recovery device A and the potential energy recovery device B convert the recovered potential energy into electric energy and store the electric energy in the power storage and supply device, and the power storage and supply device supplies the electric energy to the power device A and the power device B.

[0012] Preferably, the goaf potential energy collection system comprises a cold water inlet main pipe as an input end, a plurality of cold water inlet branch pipes connected with the cold water inlet pipe and arranged in the return air roadway floor, a hot water extraction pipe connected with the cold water inlet branch pipe and arranged in the working face floor, a hot water return branch pipe connected with the other end of the hot water extraction pipe and arranged in the transportation roadway floor, a plurality of hot water return branch pipes connected with the hot water return main pipe, and the hot water return main pipe as an output end is communicated with the water return pipe through the water delivery pipe.

[0013] Preferably, the cold water branch pipe and the hot water return branch pipe are respectively arranged in the middle direction cuttings of the return air roadway and the transportation roadway, the hot water extraction pipe is arranged in the drilling hole of the working face floor, and the hot water extraction pipe is ahead of the periodic pressure roof breaking position.

[0014] Beneficial effects: 1. The deep geothermal energy mining and the coal-heat co-mining of the deep coal seam are cooperatively mined for the first time. The lower geothermal energy mining system independently produces, guarantees the high cleanliness of the circulating water, and avoids the blockage of the horizontal fissure. The upper coal seam heat energy mining system directly inputs part of the water after extracting heat energy into the goaf heat energy collection system to form a cycle, reduces the energy loss; and the other part of the water is used for dust removal and cooling of the mining system after multi-stage filtering and cooling, which solves the problem of high mining temperature of the deep coal seam and realizes the mining of the heat energy of the deep coal seam.

[0015] 2. Constructed the geothermal resource composite system, the lower geothermal energy exploitation system extracts part of hot water directly for the recyclable water, then connects with the heat energy extraction device B of the coal seam heat energy exploitation system with relatively low cleanliness requirement, further extracts heat energy and then serves as the goaf heat energy extraction system circulating water; and creatively proposes to use the water in the coal seam roof and floor aquifer as the supplement water of the two circulating water systems, can develop deep coal-heat resources and deep groundwater resources at the same time, and reduces the use of shallow surface water.

[0016] 3. For the goaf heat energy treatment system, creatively proposes to bury the heat extraction water pipe in the goaf floor, and gives the scheme of avoiding periodic mine pressure; the goaf heat energy treatment system does not need to be filled and mined, greatly improves the mining efficiency and reduces the mining cost, and the cold water branch pipe and the heat recovery water branch pipe are buried in the heading cut of the two roadways of the working face, which can solve the floor heave problem of deep coal seams and realize the burial of the geothermal pipe. BRIEF DESCRIPTION OF DRAWINGS

[0017] Fig. 1 is the geothermal resource comprehensive exploitation system of the present application;

[0018] Fig. 2 is the goaf heat energy collection system of the present application;

[0019] In the figure: geothermal reservoir cold water injection well 1, coal seam heat energy cold water injection pipe 2, coal seam heat energy water recovery pipe 3, geothermal reservoir water recovery well 4, water pipe 5, geothermal reservoir 6, horizontal fracture 61, power transmission line 7, cold water inlet main pipe 81, heat recovery water main pipe 82, cold water inlet branch pipe 83, heat recovery water branch pipe 84, heat extraction water pipe 85, periodic pressure roof breakage position 86. DETAILED DESCRIPTION

[0020] As shown in Figs. 1-2 , a geothermal resource comprehensive exploitation system, especially suitable for Inner Mongolia region, comprises a deep geothermal energy exploitation system, the deep geothermal energy exploitation system comprises a cold water injection well 1 and a water recovery well 4 constructed from the ground to the geothermal energy reservoir 6, and an artificial fracturing horizontal fracture 61 located in the geothermal energy reservoir 6 and connected with the cold water injection well 1 and the water recovery well 4, and a potential recovery device A arranged at the lower part of the cold water injection well 1; the water recovery well 4 is connected with the heat energy extraction device A on the ground, the other end of the heat energy extraction device A is connected with the cold water injection well 1, and the water recovery well 4 is also connected with non-recyclable water (such as daily life direct water, factory production direct water) and recyclable water (such as domestic water heating water) on the ground for direct use;

[0021] The upper coal seam thermal energy mining system comprises a cold water injection pipe 2 located in the main shaft or the auxiliary shaft, and a potential energy recovery device B connected with the cold water injection pipe 2 at the lower part of the main shaft or the auxiliary shaft. The low-temperature cold water recovered by the potential energy recovery device B enters a cold water pool, and then the low-temperature cold water in the cold water pool is transported to the mining system by the power device A for dust removal and cooling. The cold water with relatively high temperature recovered by the potential energy recovery device B enters the goaf thermal energy collection system. The mine water purified by the purification device A also communicates with the input end of the goaf thermal energy collection system. The output end of the goaf thermal energy collection system communicates with the coal seam thermal energy return pipe 3 located in the return air shaft through the water delivery pipe 5. The coal seam thermal energy return pipe 3 is connected with the thermal energy extraction device B on the ground. The thermal energy extraction device B is connected with the cold water injection pipe 2 after being purified by the purification device B. The cold water with relatively high temperature after extracting thermal energy is directly injected into the goaf thermal energy collection system. The low-temperature cold water cooled by the multi-stage filtering cooling pool and the cooling tower is injected into the cold water pool through the cold water injection pipe 2.

[0022] The geothermal resource composite system comprises the following: the output end of the recycled water (such as domestic water for heating) is connected with the thermal energy extraction device B; the underground water supplementing system is arranged, and the water in the coal seam roof and floor aquifer is extracted by the power device B to supplement the goaf thermal energy collection system, and the water is supplemented to the geothermal energy reservoir 6 through the cold water injection well 1 by the potential energy recovery device A. In addition, the power storage and supply equipment is further arranged. The potential energy recovery device A and the potential energy recovery device B convert the recovered potential energy into electric energy and store the electric energy in the power storage and supply equipment. The power storage and supply equipment supplies electric energy to the power device A and the power device B.

[0023] The goaf potential energy collection system comprises the cold water inlet main pipe 81 as the input end, a plurality of cold water inlet branch pipes 83 connected with the cold water inlet main pipe 81 and located in the return air roadway floor, the hot water collection pipe 85 connected with the cold water inlet branch pipe 83 and located in the working face floor, the hot water return branch pipe 84 connected with the other end of the hot water collection pipe 85 and located in the transportation roadway floor, and a plurality of hot water return branch pipes 84 connected with the hot water return main pipe 82. The hot water return main pipe 82 as the output end communicates with the water return pipe 3 through the water delivery pipe 5. The cold water branch pipe 83 and the hot water return branch pipe 84 are respectively embedded in the middle heading cut of the return air roadway and the transportation roadway. Since the heading cut is performed in the middle of the roadway, the problem of roadway floor heave can be relieved. The hot water collection pipe 85 is embedded in the borehole in the working face floor, and the hot water collection pipe 85 is ahead of the periodic pressure roof breaking position 86 by about 3-5 m.

[0024] The use method of the geothermal resource comprehensive exploitation system comprises the following steps: S1, constructing a deep geothermal energy exploitation system, constructing a cold water injection well 1 and a water return well 4 from the ground to the geothermal energy reservoir 6, artificially cracking a horizontal crack 61 in the geothermal energy reservoir 6 to connect the cold water injection well 1 and the water return well 4, and constructing a well chamber containing the potential energy recovery device A downward from the main well or the auxiliary well, and connecting the potential energy recovery device A with the lower part of the cold water injection well 1;

[0025] The water return well 4 is connected with the ground and the heat energy extraction device A, the other end of the heat energy extraction device A is connected with the cold water injection well 1, and the water return well 4 is also connected with non-recyclable water (such as direct water for daily life and direct water for factory production) and recyclable water (such as water for household floor heating) on the ground for direct use;

[0026] S2, constructing an upper coal seam heat energy exploitation system, laying a cold water injection pipe 2 in the main well or the auxiliary well of the coal seam, constructing a chamber at the bottom of the main well or the auxiliary well, installing a potential energy recovery device B connected with the cold water injection pipe 2 in the chamber, inputting low-temperature cold water after the potential energy recovery by the potential energy recovery device B into a cold water pool through a water delivery pipe, and then inputting the low-temperature cold water in the cold water pool into the mining system through the power device A for dust removal and cooling;

[0027] The cold water with relatively high temperature after the potential energy recovery by the potential energy recovery device B is input into the goaf heat energy collection system, and the mine water after purification by the purification device A is also communicated with the input end of the goaf heat energy collection system, the goaf heat energy collection system heats the input water, and the output end of the goaf heat energy collection system is communicated with the coal seam heat energy return pipe 3 in the air return well through the water delivery pipe 5;

[0028] The coal seam heat energy return pipe 3 is connected with the ground and the heat energy extraction device B, the heat energy extraction device B is connected with the cold water injection pipe 2 after purification by the purification device B, and the cold water with relatively high temperature after the heat energy extraction is directly injected into the goaf heat energy collection system; the water after the heat energy extraction by the heat energy extraction device B is partially cooled through the multi-stage filtering cooling pool and the cooling tower, and then becomes low-temperature cold water and is injected into the cold water pool through the cold water injection pipe 2;

[0029] S3, constructing a geothermal resource composite system, connecting the recyclable water output end with the heat energy extraction device B, and further extracting heat energy and then communicating with the multi-stage filtering cooling pool and the purification device B;

[0030] An underground water supplementing system is constructed, the water in the aquifer of the roof and floor of the coal seam is extracted by the power device B to supplement the goaf heat energy collection system, and the extracted water is also supplemented to the geothermal energy reservoir 6 through the cold water injection well 1.

[0031] S4, constructing a power supply auxiliary system, converting the potential energy recovered by the potential energy recovery device A and the potential energy recovery device B into electric energy and storing the electric energy in a power storage and supply device, and supplying the electric energy to the power device A and the power device B by the power storage and supply device.

[0032] The goaf potential energy collection system comprises an inlet cold water main pipe 81 as an input end, a plurality of inlet cold water branch pipes 83 connected with the inlet cold water main pipe 81 and arranged in the floor of the air return roadway, a hot water collection pipe 85 connected with the inlet cold water branch pipes 83 and arranged in the floor of the working face, a hot water return branch pipe 84 connected with the other end of the hot water collection pipe 85 and arranged in the floor of the transportation roadway, a plurality of hot water return branch pipes 84 connected with a hot water return main pipe 82, and the hot water return main pipe 82 as an output end is communicated with the water return pipe 3 through the water delivery pipe 5. Cold water branch pipes 83 and hot water return branch pipes 84 are respectively embedded in the air return roadway and the transportation roadway by cutting grooves in the middle of the air return roadway and the transportation roadway during the mining of the working face. The hot water collection pipe 85 is embedded in the floor of the working face by drilling holes in the floor of the working face in front of the working face, and the hot water collection pipe 85 is embedded in the floor of the working face in front of 3-5 m of the position 86 where the periodic pressure roof breaks.

Claims

1. A comprehensive exploitation system for geothermal resources in Inner Mongolia, characterized in that, The deep geothermal energy exploitation system comprises a cold water injection well and a water return well constructed from the ground to a geothermal energy reservoir, and an artificial fractured horizontal crack in the geothermal energy reservoir connecting the cold water injection well and the water return well, and a potential energy recovery device A arranged at the lower part of the cold water injection well; the water return well is connected with a geothermal energy extraction device A at the ground, and the geothermal energy extraction device A is connected with the cold water injection well at the other end, and the water return well is also connected with non-recyclable water and recyclable water at the ground; The upper coal seam geothermal energy exploitation system comprises a cold water injection pipe arranged in a main shaft or a subsidiary shaft, and a potential energy recovery device B connected with the cold water injection pipe at the lower part of the main shaft or the subsidiary shaft, and low-temperature cold water with recovered potential energy by the potential energy recovery device B enters a cold water pool, and then the low-temperature cold water in the cold water pool is transported to a mining system by a power device A; cold water with relatively high temperature and recovered potential energy by the potential energy recovery device B enters a goaf heat energy collection system; mine water purified by a purification device A also communicates with an input end of the goaf heat energy collection system, and an output end of the goaf heat energy collection system communicates with a coal seam heat energy return pipe arranged in an air return shaft through a water delivery pipe; the coal seam heat energy return pipe is connected with a geothermal energy extraction device B at the ground, and the geothermal energy extraction device B is connected with the cold water injection pipe after being purified by a purification device B, and cold water with relatively high temperature and extracted heat energy is directly injected into the goaf heat energy collection system; low-temperature cold water cooled by the geothermal energy extraction device B through a multi-stage filtering cooling pool and a cooling tower is injected into the cold water pool through the cold water injection pipe; The geothermal resource composite system comprises the following: the output end of the recyclable water is connected with the geothermal energy extraction device B; a downhole water supplementing system is arranged, and a power device B is used to extract water in a coal seam roof and floor aquifer to supplement the goaf heat energy collection system, and the potential energy recovery device A is used to supplement the geothermal energy reservoir through the cold water injection well; a power storage and supply device is further arranged, and the potential energy recovery device A and the potential energy recovery device B convert the recovered potential energy into electric energy and store the electric energy in the power storage and supply device, and the power storage and supply device supplies the electric energy to the power device A and the power device B; The goaf heat energy collection system comprises an input end, a plurality of cold water inlet branch pipes arranged in the floor of the air return roadway and connected with the cold water inlet pipe, a heat water extraction pipe arranged in the floor of the working face and connected with the cold water inlet branch pipe, a heat water return branch pipe arranged in the floor of the transportation roadway and connected with the heat water extraction pipe, and a plurality of heat water return branch pipes connected with a heat water return main pipe, and the heat water return main pipe is connected with the water return pipe through a water delivery pipe as an output end; the cold water branch pipe and the heat water return branch pipe are respectively arranged in the middle of the air return roadway and the transportation roadway; the heat water extraction pipe is arranged in a borehole in the floor of the working face, and the heat water extraction pipe is ahead of the broken position of the periodic pressure roof by 3-5 m.

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