Natural gas extraction and injection complementary energy efficient utilization system

Abstract

The invention relates to the technical field of efficient energy conversion and utilization systems, in particular to an efficient utilization system for natural gas extraction and injection complementary energy. Specifically, the system comprises a gas injection module, a soil heat storage module and a residual pressure power generation module; according to the system, waste heat generated in the gas injection period can be stored in soil, natural gas is heated through the waste heat in the gas production period, redundant heat energy can be used for building heating, cross-season use of the waste heat is achieved, and a sustainable solution is provided for efficient utilization of energy.

Description

Technical Field

[0001] The present invention relates to the technical field of energy efficient conversion and utilization systems, and in particular to a natural gas production and injection surplus energy efficient utilization system. Background Art

[0002] Underground gas storage is the main way to solve the problem of natural gas supply and demand balance. It adopts a separate operation mode of injection and production. The injection period is concentrated in summer and autumn. Natural gas is compressed step by step and stored in underground reservoirs. At the same time, a large amount of waste heat is generated during the compression process. The production period is concentrated in winter and spring. Natural gas is transported out of the field after a series of treatment processes such as pressure reduction and heating.

[0003] At present, the conventional way to utilize the surplus energy of gas storage is to use the pressure energy of high-pressure natural gas during the gas extraction process and convert the pressure energy into electrical energy through an expansion generator. However, the waste heat generated between the stages of the natural gas compressor during the gas injection period is large in magnitude but low in quality and difficult to use for power generation. In addition, there is less demand for low-grade thermal energy in summer and autumn. Therefore, this part of the waste heat is often directly wasted by air cooling.

[0004] During the gas production stage, the temperature of natural gas drops rapidly during the process of reducing pressure, and heating equipment is needed to heat the natural gas to meet the demand. The common measure is to directly heat the natural gas by heating furnace or electric heating. This will consume a lot of energy and increase the energy consumption of natural gas storage stations.

[0005] Due to the above reasons, it is difficult to efficiently utilize the surplus energy of gas storage. At present, there are relatively few studies on the recovery of surplus energy in gas storage. The conventional technology of using surplus pressure to generate electricity only recovers pressure energy, but does not solve the problem of utilizing low-grade waste heat generated between stages of natural gas compressors during gas injection. At the same time, during the gas production stage, although the pressure energy has been recovered, the natural gas still needs to be heated by heating equipment to meet the process requirements, which increases the energy consumption of the system. Summary of the invention

[0006] The technical problem to be solved by the present invention is that the low-grade waste heat generated between stages of the natural gas compressor during gas injection is difficult to utilize, and at the same time, during the gas production stage, heating equipment is still required to heat the natural gas, resulting in a large amount of energy being consumed.

[0007] To this end, the present invention provides a system for efficiently utilizing surplus energy from natural gas extraction and injection, comprising: Gas injection module, soil heat storage module, residual pressure power generation module; During the gas injection period, the natural gas is compressed and cooled by the gas injection module before being stored. The gas injection module transfers the heat of the natural gas to the soil heat storage module, which then transfers it to the soil. During gas extraction, the natural gas released from the underground gas storage is depressurized and expanded by the residual pressure power generation module. In the residual pressure power generation module, the pressure energy of the natural gas is converted into mechanical energy and then into electrical energy. During gas injection, the heat stored in the soil is used to heat the natural gas that has expanded and cooled during gas production; The natural gas is expanded and heated at least once.

[0008] Further, the gas injection module includes: a natural gas compressor, a gas injection heat exchanger; Wherein, the natural gas compressor and the gas injection heat exchanger are connected through a pipeline; During gas injection, natural gas is compressed step by step by the natural gas compressor. As the pressure and temperature of natural gas increase, the gas injection heat exchanger is used to reduce the temperature of natural gas. In the gas injection heat exchanger, the natural gas exchanges heat with the heat exchange medium in the soil heat storage module, and then transfers the heat to the soil through the soil heat storage module.

[0009] Further, the soil heat storage module includes: a buried pipe heat exchanger; The gas injection module absorbs the heat of the natural gas and transfers it to the ground heat exchanger, which transfers the heat to the soil for storage.

[0010] Furthermore, the residual pressure power generation module is a multi-stage expansion power generation; During gas production, the natural gas released from the underground gas storage reservoir undergoes at least one expansion to generate electricity and heat.

[0011] Furthermore, the residual pressure power generation module includes: an expansion power generation unit, a gas collection heat exchanger; The natural gas released from the underground gas storage enters the expansion generator set, where the pressure energy of the natural gas is converted into mechanical energy and then into electrical energy; The buried pipe heat exchanger transfers the heat in the soil to the heat exchange medium of the buried pipe heat exchanger, and then the gas production heat exchanger transfers the heat of the heat exchange medium inside the buried pipe heat exchanger to the natural gas that has been depressurized and cooled by the expansion generator set.

[0012] Further, The natural gas discharged from the underground reservoir enters at least one expansion generator set, and the pressure energy of the natural gas is converted into mechanical energy and then into electrical energy in the expansion generator set; After the natural gas is reduced in pressure and cooled by each expansion generator set, it needs to pass through the gas collection heat exchanger again. The heat in the soil is transferred to the gas collection heat exchanger through the buried pipe heat exchanger, and then the gas collection heat exchanger transfers the heat to the natural gas for heating.

[0013] Furthermore, the system for efficiently utilizing surplus energy from natural gas extraction and injection includes: a first fluid pump; The first fluid pump is arranged on the pipeline connecting the buried pipe heat exchanger and the gas injection heat exchanger. The first fluid pump is used to drive the circulation flow of the heat exchange medium in the buried pipe heat exchanger so that the heat exchange medium exchanges heat with the soil, the gas extraction heat exchanger or the gas injection heat exchanger.

[0014] Furthermore, the system for efficiently utilizing surplus energy from natural gas extraction and injection includes: a first valve, a second valve, and an air cooler; The first valve is arranged on the pipeline connecting the underground heat exchanger and the gas extraction heat exchanger, and the second valve is arranged on the pipeline connecting the underground heat exchanger and the gas injection heat exchanger; During gas injection, the second valve is opened to transfer the waste heat generated between the stages of the natural gas compressor to the soil through the air cooler and the buried pipe heat exchanger; During gas production, the first valve is opened, and the pressure energy of the natural gas is converted into mechanical energy and then into electrical energy. The heat energy stored in the soil is extracted through the buried pipe heat exchanger and the gas production heat exchanger to heat the reduced-pressure natural gas.

[0015] The beneficial effects of this application are: The present invention provides a system for efficiently utilizing surplus energy during natural gas production and injection, comprising: a gas injection module, a soil heat storage module, and a surplus pressure power generation module; during gas injection, the natural gas is compressed and cooled by the gas injection module and then stored, the gas injection module absorbs the heat of the natural gas and transfers it to the soil heat storage module, and then is transmitted to the soil via the soil heat storage module; during gas production, the natural gas released from the underground gas storage reservoir expands via the surplus pressure power generation module, and in the surplus pressure power generation module, the pressure energy of the natural gas is converted into mechanical energy and then into electrical energy; the heat stored in the soil is used to heat the natural gas that has expanded and cooled during gas production.

[0016] The system mentioned in the present invention can store the waste heat generated during gas injection in the soil, and use it to heat natural gas during gas extraction. The excess heat energy can be used for building heating, and the pressure energy is recovered by the residual pressure power generation module to achieve efficient utilization of the waste energy. At the same time, in order to further improve the waste heat utilization rate and the residual pressure power generation, the pressure energy is recovered by multi-stage expansion power generation. After the natural gas is reduced in pressure and temperature by the expansion generator set, the heat energy stored in the soil is used for heat supplement, and the next level of expansion power generation can be carried out. This process not only improves the waste heat utilization rate, but also increases the energy of the natural gas and the power generation due to the heat supplement. The natural gas can also be expanded and generated by the expansion generator set only once. Specifically, during the gas injection period, the temperature and pressure of the natural gas increase after being compressed by the natural gas compressor. The gas injection heat exchanger and the buried pipe heat exchanger are used to store the excess heat energy in the soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on the specifics of the present invention and in conjunction with the accompanying drawings.

[0018] Figure 1 This is a structural schematic diagram of a natural gas production and injection surplus energy efficient utilization system mentioned in the present invention.

[0019] Description of Reference Numerals 1. Natural gas compressor; 2. Gas injection heat exchanger; 3. Expansion generator set; 4. Gas extraction heat exchanger; 5. First valve; 6. Heat user; 7. Heat storage material module; 8. Fourth fluid pump; 9. Condenser; 10. Expansion valve; 11. Second fluid pump; 12. Compressor; 13. Evaporator; 14. Fourth valve; 15. Third fluid pump; 16. Third valve; 17. First fluid pump; 18. Second valve; 19. Ground pipe heat exchanger; 20. Soil; 21. Gas injection module; 22. Residual pressure power generation module; 23. Soil heat storage module. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings so that those skilled in the art can better understand the present invention and implement it, but the examples are not intended to limit the present invention.

[0021] For this purpose, refer to Figure 1 The present invention relates to a system for efficiently utilizing surplus energy from natural gas extraction and injection, comprising: Gas injection module 21, soil heat storage module 23, residual pressure power generation module 22; The gas injection module 21 is responsible for compressing and cooling the natural gas during the gas injection period. During the compression and cooling process, the natural gas exchanges heat with the soil heat storage module 23 through the gas injection module 21, and the heat is then transferred to the soil 20 through the soil heat storage module 23 for storage.

[0022] During gas extraction, the natural gas released from the underground gas storage expands through the residual pressure power generation module 22. The residual pressure power generation module 22 converts the pressure energy of the natural gas into mechanical energy, and then further converts it into electrical energy. The natural gas undergoes multi-stage expansion and heating.

[0023] This system focuses on improving the utilization rate of waste energy and reducing the comprehensive energy consumption of gas storage stations. In order to solve the problems of low waste heat quality and separation of production and injection periods, the cross-seasonal soil heat storage method is used to directly recover low-temperature waste heat in the form of thermal energy, which is used to heat natural gas during the gas production period. It not only recovers waste heat, but also solves the problem of natural gas heating during the gas production period, reducing energy consumption. At the same time, the waste pressure power generation module 22 is used to recover pressure energy. In order to further improve the utilization rate of waste heat and further increase the power generation, a multi-stage waste pressure heat expansion power generation method is adopted in the waste pressure expansion power generation stage. After the natural gas is reduced in pressure by the waste pressure power generation module 22, it uses the heat energy stored in the soil 20 for heat supplementation, and then performs the next stage of expansion power generation. This process improves the utilization rate of waste heat while also increasing the waste pressure power generation.

[0024] The following is the workflow of this system: During gas injection: Natural gas is compressed and cooled in the gas injection module 21, and heat is released during the compression process. The gas injection module 21 exchanges heat with the soil heat storage module 23, transferring the heat to the heat exchange medium in the soil heat storage module 23, and then the soil heat storage module 23 transfers the heat to the soil 20 for storage.

[0025] Heat storage stage: Natural gas transfers heat to the soil 20 through the gas injection module 21 and the soil heat storage module 23 for storage.

[0026] Gas production stage: During the gas production period, the compressed and cooled natural gas is released from the underground reservoir and expands through the residual pressure power generation module 22. During the expansion process, the pressure energy is converted into mechanical energy and further converted into electrical energy.

[0027] Heating stage: During the gas extraction process, the heat stored in the soil heat storage module 23 is used to heat the expanded natural gas, thereby improving the efficiency of waste heat utilization and increasing power generation.

[0028] This application can improve the overall energy utilization efficiency by effectively storing the heat generated during the gas injection process and using it in the gas production stage. At the same time, the pressure energy of high-pressure natural gas is converted into electrical energy during the expansion process to achieve effective recovery and utilization of pressure energy. By optimizing the natural gas production and injection process, energy waste can be reduced and environmental impact can be reduced. This system achieves efficient utilization and recovery of energy by cleverly utilizing and storing the heat and energy during the natural gas production and injection process, which helps to improve the overall utilization efficiency of natural gas resources.

[0029] In this technical solution, the gas injection module 21 includes: a natural gas compressor 1, a gas injection heat exchanger 2; The natural gas compressor 1 and the gas injection heat exchanger 2 are connected by a pipeline. During the gas injection period, the natural gas is compressed step by step by the natural gas compressor 1. As the pressure and temperature of the natural gas increase, the gas injection heat exchanger 2 is used to reduce the temperature of the natural gas.

[0030] In the gas injection heat exchanger 2 , the natural gas exchanges heat with the heat exchange medium in the soil heat storage module 23 , and then transfers the heat to the soil 20 through the soil heat storage module 23 .

[0031] During the compression process, since the outside world does work on the natural gas, according to the law of conservation of energy, the internal energy of the natural gas increases, which is manifested as an increase in temperature and pressure.

[0032] The high-temperature natural gas compressed by the natural gas compressor 1 enters the gas injection heat exchanger 2. The main function of the gas injection heat exchanger 2 is to reduce the temperature of the natural gas. The gas injection heat exchanger 2 adopts the form of a heat exchanger, and uses a heat exchange medium to exchange heat with the high-temperature natural gas. When the high-temperature natural gas flows in the pipeline of the gas injection heat exchanger 2, the heat exchange medium flows outside the pipeline or through a specific channel. Heat is transferred from the high-temperature natural gas to the heat exchange medium, which reduces the temperature of the natural gas. The heat is transferred from the high-temperature natural gas to the heat exchange medium through the gas injection heat exchanger 2. During the flow process, the heat exchange medium absorbs the heat of the natural gas by convection heat transfer.

[0033] In the gas injection heat exchanger 2 , the natural gas exchanges heat with the heat exchange medium in the soil heat storage module 23 , and then transfers the heat to the soil 20 through the soil heat storage module 23 .

[0034] The waste heat generated during the gas injection can be stored in the soil 20 via the gas injection module 21 and the soil heat storage module 23 according to the heat demand. In summer, the heat exchange effect of the soil 20 is more advantageous than air cooling. Specifically, it can be achieved through a specific heat exchange circuit to transfer heat to the soil 20.

[0035] Through the coordinated work of the natural gas compressor 1 and the gas injection heat exchanger 2, the natural gas can be compressed and cooled, the safety and efficiency of the gas injection process can be ensured, and the heat generated during the compression process can be effectively utilized.

[0036] In the present technical solution, the soil heat storage module 23 includes: a ground-mounted heat exchanger 19; illustratively, the top of the ground-mounted heat exchanger 19 is often about 2 meters underground, and the occupation of land does not affect the use of the land surface.

[0037] The ground pipe heat exchanger 19 is connected to the gas injection module 21 through a pipeline. The natural gas in the pipeline passes through the gas injection module 21 and exchanges heat with the heat exchange medium in the ground pipe heat exchanger 19 , and the ground pipe heat exchanger 19 transfers the heat to the soil 20 .

[0038] The buried pipe heat exchanger 19 is composed of a pipeline system buried underground. The gas injection heat exchanger 2 in the gas injection module 21 transfers the heat generated by the compressed natural gas to the heat exchange medium in the buried pipe heat exchanger 19. Among them, the first fluid pump 17 is arranged on the pipeline connecting the buried pipe heat exchanger 19 and the gas injection heat exchanger 2. The first fluid pump 17 is used to drive the circulation flow of the heat exchange medium in the buried pipe heat exchanger 19, and the heat exchange medium inside the buried pipe heat exchanger 19 exchanges heat with the soil 20. Exemplarily, the heat exchange medium can be a circulating fluid, and the heat is transferred from the circulating fluid with a higher temperature to the soil 20 with a relatively lower temperature. With the continuous transfer of heat, the temperature of the soil 20 gradually increases, and heat storage is achieved. In addition, during the gas injection period, since the temperature of the soil 20 is lower and the fluctuation is small, it has a better cooling effect on the natural gas.

[0039] The system mentioned in the present application realizes the absorption, transmission and storage of low-temperature waste energy generated during the gas injection stage, stores the waste heat underground in summer and autumn, and extracts the stored heat energy in winter, thus realizing the cross-seasonal use of waste heat and providing a sustainable solution for the efficient use of energy.

[0040] In the present technical solution, there are multiple residual pressure power generation modules 22; during gas production, the natural gas released from the underground gas storage passes through multiple residual pressure power generation modules 22, expands multiple times to generate electricity and is heated.

[0041] In a feasible implementation, the residual pressure power generation module 22 includes: an expansion power generation unit 3 and a gas extraction heat exchanger 4 .

[0042] When the natural gas from the gas storage enters the expansion generator set 3, the high-pressure natural gas expands in the expansion generator set 3. During the expansion process, the pressure energy of the natural gas is finally converted into electrical energy.

[0043] At the same time, the natural gas from the expansion generator set 3 exchanges heat with the soil 20 through the gas extraction heat exchanger 4 and the ground pipe heat exchanger 19. In this process, the heat in the soil 20 is extracted to heat the natural gas, thereby increasing the temperature of the natural gas.

[0044] The present application makes full use of the pressure energy of high-pressure natural gas through the residual pressure power generation module 22, converts it into electrical energy, and improves the energy utilization efficiency. Then, by exchanging heat with the soil 20, not only can heat be obtained from the soil 20 when needed, but also excess heat can be stored in the soil 20 at other times, thereby improving the energy utilization rate of the system.

[0045] The present application recovers a large amount of low-grade waste heat generated during the gas injection period through the cross-season soil heat storage module 23, and uses the stored heat energy for natural gas heating in the gas production stage, replacing the original fuel heating, and reusing the waste heat that was originally directly discarded, saving energy and reducing emissions.

[0046] In this technical solution, the natural gas extraction and injection surplus energy efficient utilization system can be added with: off-site heating components, which include: heat storage material module 7, heat user 6; The ground source heat pump unit uses the underground soil 20 as a low temperature heat source. In winter, it absorbs heat from the low temperature heat source, raises the heat to a higher temperature through the heat pump cycle, and then transmits this part of the heat to the heat user 6 for heating.

[0047] Specifically, when heating outside the station is carried out, the fourth valve 14 and the third valve 16 are set to control the opening and closing of the heating components outside the station. The refrigerant in the heating components outside the station absorbs the heat of the underground heat source in the evaporator 13 and evaporates. Then, the steam is compressed into high-temperature and high-pressure gas by the compressor 12 and enters the condenser 9. In the condenser 9, the high-temperature and high-pressure refrigerant gas releases heat to the circulating water of the heat user 6, thereby increasing the temperature of the circulating water for heating. After the refrigerant is cooled by the condenser 9, it is depressurized by the expansion valve 10 and converted into a low-temperature and low-pressure state.

[0048] The ground source heat pump unit can work in conjunction with the buried pipe heat exchanger 19 in the soil heat storage module 23.

[0049] The heat storage material module 7 is mainly used to store excess heat energy, and at the same time, the energy can be transported across distances by transporting the heat storage material module 7. Exemplarily, the heat storage material module 7 can use low-temperature phase change materials or water. It can be provided to users by vehicle transportation or thermal pipeline transportation. Specifically, when there is excess heat energy in the system, this part of the heat can be extracted and stored in the heat storage material module 7 for use during peak heat energy demand. The heat storage material module 7 has a high heat capacity and good stability, and can store heat for a long time without significant energy loss.

[0050] In the heat storage stage, the high-temperature fluid (such as hot water) in the system flows through the heat storage material module 7, transfers heat to the heat storage material module 7, and increases the temperature of the heat storage material module 7. In the heat release stage, when heat supply is required, the low-temperature fluid flows through the heat storage material module 7, and the heat storage material module 7 transfers the stored heat to the fluid, increases the temperature of the fluid, and then delivers it to the heat user 6 for heat supply.

[0051] The hot water provided by the ground source heat pump unit or the heat storage material module 7 enters the heat user 6, releases the heat into the room, and then the low-temperature return water returns to the ground source heat pump unit or the heat storage material module 7 and is heated again, forming a cycle.

[0052] In a feasible implementation, the second fluid pump 11 is used to drive the heat exchange medium in the pipeline between the condenser 9 and the heat storage material module 7. The fluid medium absorbs heat and heats up on the condenser 9 side, and releases heat and cools down on the heat storage material module 7. The third fluid pump 15 is used to drive the heat exchange medium in the ground pipe heat exchanger 19. The fourth fluid pump 8 is connected to the heat storage material module 7 and the heat user 6 through a pipeline. The fourth fluid pump 8 drives the heat exchange medium in the pipeline. The fluid medium absorbs heat and heats up on the heat storage material module 7 side, and releases heat and cools down on the heat user 6.

[0053] In a feasible implementation, the natural gas production and injection surplus energy efficient utilization system includes: a first valve 5 and a second valve 18. The first valve 5 is arranged on the pipeline connecting the ground pipe heat exchanger 19 and the gas production heat exchanger 4, and the second valve 18 is arranged on the pipeline connecting the ground pipe heat exchanger 19 and the gas injection heat exchanger 2.

[0054] During the gas injection period, the second valve 18 is opened, and the other valves are closed, and the waste heat generated between the stages of the natural gas compressor 1 is transferred to the soil 20 through the air cooler and the underground pipe heat exchanger 19.

[0055] During gas production, the first valve 5 is opened and the other valves are closed. The pressure energy of the natural gas is converted into mechanical energy and then into electrical energy. The heat energy stored in the soil 20 is extracted through the buried pipe heat exchanger 19 and the gas production heat exchanger 4 and used to heat the reduced-pressure natural gas.

[0056] The present invention proposes a system for efficiently utilizing the surplus energy of natural gas production and injection. The system can store the surplus heat generated during the gas injection period in the soil 20, which is used to heat the natural gas during the gas production period. The surplus heat energy can be used for building heating, and the pressure energy is recovered by the pressure difference generator to achieve efficient utilization of the surplus energy. During the gas injection period, the temperature and pressure of the natural gas increase after being compressed by the natural gas compressor 1. The interstage gas production heat exchanger 4 is used, and water is used as the heat exchange medium to store the surplus heat energy in the soil 20.

[0057] The technical solution of the present application will be further described below in the form of embodiments combined with drawings.

[0058] Example 1: Gas injection waste heat storage system.

[0059] like Figure 1 As shown, during the gas injection period of the gas storage, the natural gas is compressed step by step by the natural gas compressor 1. As the natural gas pressure increases, the temperature rises rapidly, and the natural gas temperature needs to be lowered by the gas injection heat exchanger 2. The gas injection heat exchanger 2 exchanges heat with the ground pipe heat exchanger 19, and the ground pipe heat exchanger 19 is connected to the soil 20 for heat exchange, and the residual heat is stored in the soil 20 through the gas injection heat exchanger 2 and the ground pipe heat exchanger 19.

[0060] Embodiment 2: Gas extraction excess pressure expansion power generation system.

[0061] like Figure 1 As shown, during the gas production period of the gas storage, the natural gas first enters the expansion generator set 3 in the pressure reduction process to convert its pressure energy into electrical energy. The temperature of the natural gas decreases rapidly while the pressure is reduced, and the temperature of the expanded natural gas is relatively low. The heat energy stored in the soil 20 is extracted by the heat pump to heat the natural gas. Specifically, the natural gas can be heat-exchanged with the soil 20 through the gas production heat exchanger 4 and the buried pipe heat exchanger 19, and then enter the next-level expansion generator set 3 to expand and generate electricity until the required pressure is reached.

[0062] Example 3: Ground source heat pump heating system.

[0063] like Figure 1 As shown, the heat energy stored in the soil 20 is first used to heat the natural gas in the station, and the remaining heat energy can first be used to improve the quality of waste heat through the soil 20 source heat pump unit, and then stored in the heat storage material module 7, and finally transported to the heat user 6 via vehicles or thermal pipelines for domestic heating.

[0064] Obviously, the above is only an example for clear explanation and is not a limitation of the implementation method. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the invention.

[0065] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0066] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0067] In the present invention, unless otherwise clearly specified and limited, when a first feature is “on” or “below” a second feature, it may be that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, when a first feature is “above”, “above” or “above” a second feature, it may be that the first feature is directly above or obliquely above the second feature, or it may simply mean that the first feature is higher in level than the second feature. When a first feature is “below”, “below” or “below” a second feature, it may be that the first feature is directly below or obliquely below the second feature, or it may simply mean that the first feature is lower in level than the second feature.

[0068] In the description of this specification, the description of the terms "one", "some", "", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the or example are included in at least one or examples of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same or examples. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different or examples and the features of the different or examples described in this specification without contradiction.

[0069] Although the present invention has been shown and described above, it is to be understood that the above is exemplary and is not to be construed as limiting the present invention. A person skilled in the art may make changes, modifications, substitutions and variations to the above within the scope of the present invention.

Claims

1. A system for efficiently utilizing surplus energy from natural gas production and injection, characterized in that: include: Gas injection module, soil heat storage module, residual pressure power generation module; During the gas injection period, the natural gas is compressed and cooled by the gas injection module before being stored. The gas injection module transfers the heat of the natural gas to the soil heat storage module, which then transfers the heat to the soil. During gas extraction, the natural gas released from the underground gas storage is depressurized and expanded by the residual pressure power generation module. In the residual pressure power generation module, the pressure energy of the natural gas is converted into mechanical energy and then into electrical energy. During gas injection, the heat stored in the soil is used to heat the natural gas that has expanded and cooled during gas production; The natural gas is expanded and heated at least once.

2. A natural gas extraction and injection surplus energy efficient utilization system according to claim 1, characterized in that: The gas injection module includes: a natural gas compressor and a gas injection heat exchanger; Wherein, the natural gas compressor and the gas injection heat exchanger are connected through a pipeline; During the gas injection period, the natural gas is compressed step by step by the natural gas compressor, and as the pressure and temperature of the natural gas increase, the gas injection heat exchanger is used to reduce the temperature of the natural gas; In the gas injection heat exchanger, the natural gas exchanges heat with the heat exchange medium in the soil heat storage module, and then transfers the heat to the soil through the soil heat storage module.

3. A natural gas extraction and injection surplus energy efficient utilization system according to claim 2, characterized in that: The soil heat storage module comprises: a buried pipe heat exchanger; The gas injection module absorbs the heat of the natural gas and transfers it to the ground pipe heat exchanger, and the ground pipe heat exchanger transfers the heat to the soil for storage.

4. A natural gas extraction and injection surplus energy efficient utilization system according to claim 3, characterized in that: The residual pressure power generation module is a multi-stage expansion power generation module; During gas production, the natural gas released from the underground gas storage reservoir undergoes at least one expansion to generate electricity and heat.

5. A natural gas extraction and injection surplus energy efficient utilization system according to claim 4, characterized in that: The residual pressure power generation module includes: an expansion power generation unit and a gas collection heat exchanger; The natural gas released from the underground gas storage enters the expansion generator set, where the pressure energy of the natural gas is converted into mechanical energy and then into electrical energy; The buried pipe heat exchanger transfers the heat in the soil to the heat exchange medium in the buried pipe heat exchanger, and then the gas production heat exchanger transfers the heat of the heat exchange medium inside the buried pipe heat exchanger to the natural gas that has been depressurized and cooled by the expansion generator set.

6. A natural gas extraction and injection surplus energy efficient utilization system according to claim 5, characterized in that: The natural gas discharged from the underground reservoir enters at least one expansion generator set, and the pressure energy of the natural gas is converted into mechanical energy and then into electrical energy in the expansion generator set; After being reduced in pressure and cooled by each expansion generator set, the natural gas needs to pass through the gas collection heat exchanger again. The heat in the soil is transferred to the gas collection heat exchanger via the buried pipe heat exchanger, and then the gas collection heat exchanger transfers the heat to the natural gas for heating the natural gas.

7. A natural gas production and injection surplus energy efficient utilization system according to claim 5, characterized in that: include: a first fluid pump; The first fluid pump is arranged on the pipeline connecting the buried pipe heat exchanger and the gas injection heat exchanger. The first fluid pump is used to drive the circulation flow of the heat exchange medium in the buried pipe heat exchanger so that the heat exchange medium exchanges heat with the soil, the gas extraction heat exchanger or the gas injection heat exchanger.

8. A natural gas production and injection surplus energy efficient utilization system according to claim 5, characterized in that: include: First valve, second valve, air cooler; The first valve is arranged on the pipeline connecting the underground heat exchanger and the gas extraction heat exchanger, and the second valve is arranged on the pipeline connecting the underground heat exchanger and the gas injection heat exchanger; During gas injection, the second valve is opened to transfer the waste heat generated between the stages of the natural gas compressor to the soil through the air cooler and the buried pipe heat exchanger; During gas production, the first valve is opened, and the pressure energy of the natural gas is converted into mechanical energy and then into electrical energy. The heat energy stored in the soil is extracted through the buried pipe heat exchanger and the gas production heat exchanger to heat the reduced-pressure natural gas.

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