Closed underground compressed gas energy storage system and method

Abstract

The invention discloses a closed underground compressed gas energy storage system and method.The closed underground compressed gas energy storage system comprises a compression subsystem, a heat exchange and storage subsystem, a gas storage subsystem and an expansion power generation subsystem; an inlet and an outlet of the compression subsystem are respectively connected with the gas storage subsystem through pipelines; an inlet and an outlet of the expansion power generation subsystem are respectively connected with the gas storage subsystem through pipelines; the heat exchange and storage subsystem is connected with the compression subsystem and the expansion power generation subsystem through pipelines. The gas storage subsystem comprises a plurality of oil and gas reservoir stratums connected in parallel. On one hand, absorption of new energy power generation is achieved, the purpose of peak clipping and valley filling is achieved, meanwhile, carbon dioxide or nitrogen closed circulation is adopted to prevent the carbon dioxide or nitrogen from forming an explosive mixture with combustible media such as oil gas, and carbon dioxide is utilized and stored while carbon dioxide or nitrogen oil displacement is achieved.

Description

Technical Field

[0001] This invention belongs to the field of energy storage technology, and specifically relates to a closed underground compressed gas energy storage system and method. Background Technology

[0002] While renewable energy sources such as wind and solar power are developing rapidly, the demand for energy storage is growing in tandem due to their instability, presenting a vast market opportunity. Among various energy storage technologies, compressed air energy storage systems are considered one of the most promising large-scale energy storage technologies due to their advantages such as large scale, strong applicability, high efficiency, low cost, and environmental friendliness. However, compressed air energy storage technology is still in the demonstration stage both domestically and internationally. Demonstration projects such as the 500kW compressed air energy storage project in Wuhu, Anhui, and the 60MW salt cavern compressed air energy storage project in Jintan, China Salt Industry Corporation, have been successfully completed, vigorously promoting the development of compressed air energy storage technology.

[0003] In order to overcome a series of technical challenges, improve oil recovery rates, and effectively solve the problem of oil resource shortage, many oilfields have applied carbon dioxide flooding tertiary oil recovery technology.

[0004] Existing compressed air energy storage systems require specific storage tanks, which pose significant storage risks and require large quantities. Furthermore, they cannot achieve the recycling of the gas storage medium, and the use of air as the storage medium is unsuitable for oilfield gas injection and oil recovery operations. Summary of the Invention

[0005] To address the above problems, this invention discloses a closed underground compressed gas energy storage system, comprising: a compression subsystem, a heat exchange and storage subsystem, a gas storage subsystem, and an expansion and power generation system;

[0006] The inlet and outlet of the compression subsystem are connected to the gas storage subsystem via pipelines.

[0007] The inlet and outlet of the expansion generator system are connected to the gas storage subsystem via pipelines.

[0008] The heat exchange and heat storage subsystem is connected to the compression subsystem and the expansion and power generation subsystem via pipelines.

[0009] The gas storage subsystem comprises several parallel oil and gas reservoirs.

[0010] Furthermore, the gas storage subsystem also includes: an injection switching valve and a gas sampling switching valve;

[0011] Each of the oil and gas reservoir outlets is equipped with a parallel gas injection switching valve and a gas production switching valve;

[0012] The oil and gas reservoir is connected to the outlet of the compression subsystem and the outlet of the expansion generator subsystem via gas injection switching valves, respectively.

[0013] The oil and gas reservoir is connected to the inlet of the compression subsystem and the inlet of the expansion generator subsystem via gas production switching valves.

[0014] Furthermore, the compression subsystem includes several sets of compression units connected in series;

[0015] The compression unit includes a gas compressor and an electric motor;

[0016] The electric motor is connected to the gas compressor;

[0017] Multiple gas compressors are connected in series via pipelines, with the first gas compressor connected to the oil and gas reservoir via a pipeline, and the Nth gas compressor connected to the oil and gas reservoir via a pipeline.

[0018] Furthermore, the expansion electron system includes several sets of expansion units connected in series;

[0019] The expansion unit includes an expander and a generator;

[0020] The expander is connected to the generator via a drive shaft;

[0021] Multiple expanders are connected in series via pipelines, and the Nth expander is connected to the oil and gas reservoir via a pipeline.

[0022] Furthermore, the expansion generator system also includes: a pressure regulating valve;

[0023] One end of the pressure regulating valve is connected to the oil and gas reservoir via a pipeline.

[0024] Furthermore, the expansion generator system also includes: an oil-gas separation device;

[0025] The gas inlet of the oil-gas separator is connected to the pressure regulating valve via a pipeline, the gas outlet is connected to the expansion unit via a pipeline, and the liquid phase outlet is connected to the station oil treatment system.

[0026] Furthermore, the heat exchange and heat storage subsystem includes several compressor-stage heat exchangers, a high-temperature heat storage tank, and a low-temperature heat storage tank;

[0027] The gas outlet of the gas compressor is connected to the gas inlet of the compressor interstage heat exchanger via a pipeline;

[0028] The heat storage medium outlet of the compressor interstage heat exchanger is connected to the high-temperature heat storage tank via a pipeline, and the heat storage medium inlet is connected to the low-temperature heat storage tank via a pipeline.

[0029] Furthermore, the heat exchange and heat storage subsystem also includes: a preheating heat exchanger and an expander interstage heat exchanger;

[0030] The gas inlet of the preheating heat exchanger is connected to the oil-gas separator via a pipeline, and the gas outlet is connected to the gas inlet of the expander via a pipeline.

[0031] The heat storage medium inlet of the preheating heat exchanger is connected to the high-temperature heat storage tank via a pipeline, and the heat storage medium outlet is connected to the low-temperature heat storage tank via a pipeline.

[0032] The gas outlet of the expander is connected to the gas inlet of the interstage heat exchanger of the expander.

[0033] The heat storage medium inlet of the expander interstage heat exchanger is connected to the high-temperature heat storage tank, and the heat storage medium outlet is connected to the low-temperature heat storage tank.

[0034] Furthermore, the pressure range of the gas discharged through the pressure regulating valve is 5-40 MPa.

[0035] This invention also discloses a closed-loop underground compressed gas energy storage method based on the above-mentioned closed-loop underground compressed gas energy storage system, comprising:

[0036] Step 1: When electricity demand is low, the excess electricity generated by wind and solar power drives a gas compressor to compress carbon dioxide or nitrogen. The pressurized carbon dioxide or nitrogen is injected into the first oil and gas reservoir through the gas injection switching valve. During this process, the waste heat from the gas compressor outlet is recovered through the interstage heat exchanger of the compressor. The heated heat storage medium is then injected into a high-temperature heat storage tank.

[0037] Step 2: During peak electricity demand, carbon dioxide or nitrogen from the first oil and gas reservoir is extracted through the gas production switching valve, pressure is regulated by the pressure regulating valve, and after separation by the oil and gas separation device, it is heated by the preheating heat exchanger and sent to the expander drive shaft to drive the generator to generate electricity. Then, the expanded gas is sent to the injection switching valve to inject into the second oil and gas reservoir until the pressure of all oil and gas reservoirs is equal. During this period, the gas is heated by the heat storage medium in the high-temperature heat storage tank through the interstage heat exchanger of the expander. The heated heat storage medium is then sent to the low-temperature heat storage tank.

[0038] Step 3: When electricity consumption is low, carbon dioxide or nitrogen in the second oil and gas reservoir is extracted through the gas extraction switching valve. The excess electricity drives the gas compressor to compress the gas. The pressurized carbon dioxide or nitrogen is injected into the first oil and gas reservoir through the gas injection switching valve. During this process, the waste heat at the outlet of the gas compressor is recovered through the compressor stage heat exchanger. The heated heat storage medium is then injected into the high-temperature heat storage tank.

[0039] Step 4: Repeat steps 2 and 3 in a loop.

[0040] Compared with the prior art, the embodiments of the present invention have at least the following advantages: On the one hand, the present invention realizes the absorption of new energy power generation and achieves the purpose of peak shaving and valley filling. On the other hand, it adopts a closed-loop circulation of carbon dioxide or nitrogen to avoid the formation of explosive mixtures with flammable media such as oil and gas, so as to realize the utilization and storage of carbon dioxide while driving oil with carbon dioxide or nitrogen.

[0041] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention can be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 A schematic diagram of a closed underground compressed gas energy storage system according to an embodiment of the present invention is shown.

[0044] Reference numerals in the attached figures: 1. Oil and gas reservoir; 2. Gas injection switching valve; 3. Gas production switching valve; 4. Gas compressor; 5. Compressor interstage heat exchanger; 6. Electric motor; 7. Pressure regulating valve; 8. Oil and gas separation device; 9. Preheating heat exchanger; 10. Expander; 11. Expander interstage heat exchanger; 12. Generator; 13. High-temperature heat storage tank; 14. Low-temperature heat storage tank. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] Figure 1 A schematic diagram of a closed underground compressed gas energy storage system according to an embodiment of the present invention is shown. Figure 1 As shown, the present invention proposes a closed underground compressed gas energy storage system, comprising: a compression subsystem, a heat exchange and storage subsystem, a gas storage subsystem, and an expansion and power generation system;

[0047] The inlet and outlet of the compression subsystem are connected to the gas storage subsystem via pipelines.

[0048] The inlet and outlet of the expansion generator system are connected to the gas storage subsystem via pipelines.

[0049] The heat exchange and heat storage subsystem is connected to the compression subsystem and the expansion and power generation subsystem via pipelines.

[0050] The gas storage subsystem comprises several parallel oil and gas reservoirs 1. The pressure of the oil and gas reservoir 1 is 5-40 MPa, and the temperature is 50-150℃.

[0051] For example, two oil and gas reservoirs 1 are set up in parallel.

[0052] Oil and gas reservoir 1 is used to store compressed gas or low-pressure gas after expansion.

[0053] Existing technologies use specific high-pressure storage tanks to store gas media, which poses problems such as high risks and large usage. This invention uses parallel oil and gas reservoirs 1 to store gas, which has a large storage capacity, high safety, and can realize the recycling of gas storage media.

[0054] A closed-loop underground compressed gas energy storage system uses carbon dioxide and nitrogen as compressed energy storage media. The closed-loop circulation avoids explosive mixtures, realizing carbon dioxide oil displacement while utilizing and storing carbon dioxide. Nitrogen can prevent corrosion caused by carbon dioxide.

[0055] Furthermore, the gas storage subsystem also includes: an injection switching valve 2 and a gas sampling switching valve 3;

[0056] Each of the oil and gas reservoirs 1 is equipped with a parallel gas injection switching valve 2 and a gas production switching valve 3 at its outlet;

[0057] The oil and gas reservoir 1 is connected to the gas outlet of the compressor interstage heat exchanger 5 at the outlet of the compression subsystem and the gas outlet of the Nth expander 10 (far right) at the outlet of the expansion generator system via the gas injection switching valve 2.

[0058] The oil and gas reservoir 1 is connected to the gas inlet of the first gas compressor 4 at the inlet of the compression subsystem and the constant pressure valve 7 at the inlet of the expansion generator system via the gas production switching valve 3.

[0059] The gas sampling switching valve 3 is connected to the first gas compressor 4, thereby forming a closed-loop system to achieve closed-loop energy storage.

[0060] Gas injection switching valve 2 and gas production switching valve 3 are used to switch the functional positioning of different oil and gas reservoirs 1. Figure 1 For example, when reservoir 1 on the left is used as the gas production layer, reservoir 1 on the right is used as the gas injection layer. The reverse is also true.

[0061] Furthermore, the compression subsystem includes several sets of compression units connected in series;

[0062] The compression unit includes a gas compressor 4 and an electric motor 6;

[0063] The electric motor 6 is connected to the gas compressor 4;

[0064] Multiple gas compressors 4 (e.g.) Figure 1 As shown, from left to right, the first gas compressor 4, the second gas compressor 4, ..., the Nth gas compressor 4 (where N is a positive integer) are connected in series through pipelines. The gas inlet of the first gas compressor 4 is connected to the gas production switching valve 3 of the oil and gas reservoir 1 through a pipeline, and the gas outlet of the Nth gas compressor 4 is connected to the gas injection switching valve 2 of the oil and gas reservoir 1 through the compressor stage heat exchanger 5.

[0065] The compression subsystem is equipped with a multi-stage gas compressor 4, which can compress low-pressure gas into high-pressure gas as needed, and can convert more electrical energy.

[0066] Furthermore, the expansion electron system includes several sets of expansion units connected in series;

[0067] The expansion unit includes an expander 10 and a generator 12;

[0068] The expander 10 is connected to the generator 12 via a transmission shaft. Gas drives the expander 10 to rotate, thereby driving the generator 12 to output electrical energy.

[0069] Multiple expanders 10 (e.g.) Figure 1 As shown, from left to right, the first expander 10, the second expander 10, ..., the Nth expander 10 are connected in series through pipelines, and the gas outlet of the Nth expander 10 is connected to the gas injection switching valve 2 of the oil and gas reservoir 1 through a pipeline.

[0070] The expansion generator system is equipped with a multi-stage expander 10, which can expand the high-pressure gas step by step to do work according to the needs, thereby driving the generator 12 to generate more electricity.

[0071] Furthermore, the expansion generator system also includes: a pressure regulating valve 7;

[0072] One end of the pressure regulating valve 7 is connected to the gas production switching valve 3 of the oil and gas reservoir 1 via a pipeline. After gas is produced, it enters the oil and gas separation device 8 through the pressure regulating valve 7.

[0073] Pressure regulating valve 7 is used to stabilize the pressure and adjust it to a set pressure. Pressure regulating valve 7 can adjust the produced gas pressure to adapt to the operation of the gas extraction system expander 10. It switches to constant sliding pressure regulation operation.

[0074] Furthermore, the gas pressure discharged through the pressure regulating valve 7 is in the range of 5-40 MPa.

[0075] Furthermore, the expansion generator system also includes: an oil-gas separator 8;

[0076] The gas inlet of the oil-gas separator 8 is connected to the pressure regulating valve 7 via a pipeline, the gas outlet is connected to the expander 10 of the expansion unit via a preheating heat exchanger 9, and the liquid phase outlet is connected to the station oil treatment system.

[0077] After the produced gas is separated by the oil-gas separator 8, the gas enters the preheating heat exchanger 9, and the liquid phase enters the oil treatment system.

[0078] The oil-gas separation unit 8 separates oil and gas. The oil is processed downstream as a byproduct of the associated extraction, while the gas is recycled.

[0079] Furthermore, the heat exchange and heat storage subsystem includes several compressor-stage heat exchangers 5, a high-temperature heat storage tank 13, and a low-temperature heat storage tank 14;

[0080] The gas outlet of the gas compressor 4 is connected to the gas inlet of the compressor interstage heat exchanger 5 via a pipeline. The compressed gas from the gas compressor 4 passes through the compressor interstage heat exchanger 5 and enters the next gas compressor 4. The gas outlet of the compressor interstage heat exchanger 5 is connected to the gas inlet of the gas compressor 4 or the gas injection switching valve 2 of the oil and gas reservoir 1. That is, several compressor interstage heat exchangers 5 are arranged in parallel between the gas compressors 4 connected in series or between the gas compressor 4 and the gas injection switching valve 2.

[0081] The heat storage medium outlet of the compressor interstage heat exchanger 5 is connected to the high-temperature heat storage tank 13 via a pipeline, and the heat storage medium inlet is connected to the low-temperature heat storage tank 14 via a pipeline.

[0082] The compressor interstage heat exchanger 5 is used for heat exchange.

[0083] The compression section generates heat, which is removed by the compressor interstage heat exchanger 5 and stored in the high-temperature heat storage tank 13. The medium in the expander interstage heat exchanger 11 heats the medium coming out of the expander 10 and then flows to the low-temperature heat storage tank 14. The medium in the low-temperature heat storage tank 14 then exchanges heat with the compression section.

[0084] Furthermore, the heat exchange and heat storage subsystem also includes: a preheating heat exchanger 9 and an expander interstage heat exchanger 11;

[0085] The gas inlet of the preheating heat exchanger 9 is connected to the oil-gas separator 8 via a pipeline, and the gas outlet is connected to the gas inlet of the first expander 10 via a pipeline. The depressurized gas discharged after expansion by the expander 10 is heated by the interstage heat exchanger 11 and then enters the next expander 10.

[0086] The heat storage medium inlet of the preheating heat exchanger 9 is connected to the high-temperature heat storage tank 13 through a pipeline, and the heat storage medium outlet is connected to the low-temperature heat storage tank 14 through a pipeline.

[0087] The gas outlet of the expander 10 is connected to the gas inlet of the expander interstage heat exchanger 11, and the gas outlet of the expander interstage heat exchanger 11 is connected to the gas inlet of the next expander 10.

[0088] The heat storage medium inlet of the expander interstage heat exchanger 11 is connected to the high-temperature heat storage tank 13, and the heat storage medium outlet is connected to the low-temperature heat storage tank 14.

[0089] The preheating heat exchanger 9 is used to heat the medium entering the expander 10 to prevent the medium temperature from being too low and affecting efficiency.

[0090] The expander interstage heat exchanger 11 is used to increase the medium inlet temperature of the expander 10.

[0091] Based on the aforementioned closed-loop underground compressed gas energy storage system, this embodiment proposes a closed-loop underground compressed gas energy storage method, including:

[0092] Step 1: When electricity consumption is low, the excess electricity generated by wind and solar power drives the gas compressor 4 to compress carbon dioxide or nitrogen. The pressurized carbon dioxide or nitrogen is injected into the first oil and gas reservoir 1 through the gas injection switching valve 2. During this process, the waste heat at the outlet of the gas compressor 4 is recovered through the compressor stage heat exchanger 5. The heated heat storage medium is then injected into the high-temperature heat storage tank 13.

[0093] Step 2: During peak electricity demand, carbon dioxide or nitrogen from the first oil and gas reservoir 1 is extracted through the gas production switching valve 3, and the pressure is regulated by the pressure regulating valve 7. After separation by the oil and gas separation device 8, the gas is heated by the preheating heat exchanger 9 and sent to the expander 10 to drive the drive shaft, which in turn drives the generator 12 to generate electricity. Subsequently, the expanded gas is sent to the injection switching valve 2 and injected into the second oil and gas reservoir 1 until the pressure of all oil and gas reservoirs 1 is equal. During this period, the gas is heated by the heat storage medium in the high-temperature heat storage tank 13 through the interstage heat exchanger 11 of the expander. The heated heat storage medium is then sent to the low-temperature heat storage tank 14.

[0094] Step 3: When electricity consumption is low, carbon dioxide or nitrogen in the second oil and gas reservoir 1 is extracted through the gas extraction switching valve 3. The excess electricity drives the gas compressor 4 to compress the gas. The pressurized carbon dioxide or nitrogen is injected into the first oil and gas reservoir 1 through the gas injection switching valve 2. During this process, the waste heat at the outlet of the gas compressor 4 is recovered through the compressor stage heat exchanger 5. The heated heat storage medium is then injected into the high-temperature heat storage tank 13.

[0095] Step 4: Repeat steps 2 and 3 in a loop.

[0096] This invention discloses a closed-loop underground compressed gas energy storage system and method. On the one hand, it enables the utilization of new energy power generation. On the other hand, oil and gas reservoirs contain flammable media such as oil and gas. If air is used as the medium, it is easy to form an explosive mixture. The closed-loop circulation of carbon dioxide, nitrogen, and deoxygenated air avoids the explosive mixture. It realizes the utilization and storage of carbon dioxide while driving oil with carbon dioxide or nitrogen. It develops a new energy utilization method to promote the development of new energy industry and help build low-carbon production in oil fields.

[0097] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A closed-loop underground compressed gas energy storage system, characterized in that, include: Compression subsystem, heat exchange and storage subsystem, gas storage subsystem, and expansion and power generation subsystem; The inlet and outlet of the compression subsystem are connected to the gas storage subsystem via pipelines. The inlet and outlet of the expansion generator system are connected to the gas storage subsystem via pipelines. The heat exchange and heat storage subsystem is connected to the compression subsystem and the expansion and power generation subsystem via pipelines. The gas storage subsystem includes several parallel oil and gas reservoirs (1).

2. The closed-loop underground compressed gas energy storage system according to claim 1, characterized in that, The gas storage subsystem also includes: a gas injection switching valve (2) and a gas sampling switching valve (3); Each of the oil and gas reservoirs (1) is equipped with a parallel gas injection switching valve (2) and a gas production switching valve (3) at its outlet; The oil and gas reservoir (1) is connected to the outlet of the compression subsystem and the outlet of the expansion generator system respectively through the gas injection switching valve (2); The oil and gas reservoir (1) is connected to the inlet of the compression subsystem and the inlet of the expansion generator system through the gas production switching valve (3).

3. The closed-loop underground compressed gas energy storage system according to claim 1, characterized in that, The compression subsystem includes several sets of compression units connected in series; The compression unit includes a gas compressor (4) and an electric motor (6); The electric motor (6) is connected to the gas compressor (4); Multiple gas compressors (4) are connected in series via pipelines, and the first gas compressor (4) is connected to the oil and gas reservoir (1) via a pipeline, and the Nth gas compressor (4) is connected to the oil and gas reservoir (1) via a pipeline.

4. The closed-loop underground compressed gas energy storage system according to claim 3, characterized in that, The expansion electron-generating system includes several sets of expansion units connected in series; The expansion unit includes an expander (10) and a generator (12); The expander (10) and the generator (12) are connected by a drive shaft; Multiple expanders (10) are connected in series via pipelines, and the Nth expander (10) is connected to the oil and gas reservoir (1) via a pipeline.

5. The closed-loop underground compressed gas energy storage system according to claim 4, characterized in that, The expansion generator system also includes: a pressure regulating valve (7); One end of the pressure regulating valve (7) is connected to the oil and gas reservoir (1) via a pipeline.

6. The closed-loop underground compressed gas energy storage system according to claim 5, characterized in that, The expansion generator system also includes: an oil-gas separator (8); The gas inlet of the oil-gas separator (8) is connected to the pressure regulating valve (7) through a pipeline, the gas outlet is connected to the expansion unit through a pipeline, and the liquid outlet is connected to the station oil treatment system.

7. The closed-loop underground compressed gas energy storage system according to claim 6, characterized in that, The heat exchange and heat storage subsystem includes several compressor interstage heat exchangers (5), a high-temperature heat storage tank (13), and a low-temperature heat storage tank (14); The gas outlet of the gas compressor (4) is connected to the gas inlet of the compressor interstage heat exchanger (5) via a pipeline; The heat storage medium outlet of the compressor interstage heat exchanger (5) is connected to the high-temperature heat storage tank (13) through a pipeline, and the heat storage medium inlet is connected to the low-temperature heat storage tank (14) through a pipeline.

8. The closed-loop underground compressed gas energy storage system according to claim 7, characterized in that, The heat exchange and heat storage subsystem also includes: a preheating heat exchanger (9) and an expander interstage heat exchanger (11); The gas inlet of the preheating heat exchanger (9) is connected to the oil-gas separator (8) via a pipeline, and the gas outlet is connected to the gas inlet of the expander (10) via a pipeline. The heat storage medium inlet of the preheating heat exchanger (9) is connected to the high-temperature heat storage tank (13) through a pipeline, and the heat storage medium outlet is connected to the low-temperature heat storage tank (14) through a pipeline. The gas outlet of the expander (10) is connected to the gas inlet of the interstage heat exchanger (11) of the expander; The heat storage medium inlet of the expansion interstage heat exchanger (11) is connected to the high-temperature heat storage tank (13), and the heat storage medium outlet is connected to the low-temperature heat storage tank (14).

9. The closed-loop underground compressed gas energy storage system according to claim 5, characterized in that, The pressure range of the gas discharged through the pressure regulating valve (7) is 5-40 MPa.

10. A closed-loop underground compressed gas energy storage method based on the closed-loop underground compressed gas energy storage system according to any one of claims 1-9, characterized in that, include: Step 1: When the electricity consumption is low, the excess electricity generated by wind and solar power drives the gas compressor (4) to compress carbon dioxide or nitrogen. The pressurized carbon dioxide or nitrogen is injected into the first oil and gas reservoir (1) through the gas injection switching valve (2). During this period, the waste heat at the outlet of the gas compressor (4) is recovered through the compressor stage heat exchanger (5). The heated heat storage medium is injected into the high temperature heat storage tank (13). Step 2: During peak electricity demand, carbon dioxide or nitrogen from the first oil and gas reservoir (1) is extracted through the gas extraction switching valve (3), and the pressure is regulated by the pressure regulating valve (7). After separation by the oil and gas separation device (8), the gas is heated by the preheating heat exchanger (9) and sent to the expander (10) to drive the drive shaft, which in turn drives the generator (12) to generate electricity. Subsequently, the expanded gas is sent to the gas injection switching valve (2) and injected into the second oil and gas reservoir (1) until the pressure of all oil and gas reservoirs (1) is equal. During this period, the gas is heated by the heat storage medium in the high-temperature heat storage tank (13) through the interstage heat exchanger (11) of the expander. The heated heat storage medium is then sent to the low-temperature heat storage tank (14). Step 3: When electricity consumption is low, carbon dioxide or nitrogen in the second oil and gas reservoir (1) is extracted through the gas extraction switching valve (3). The excess electricity drives the gas compressor (4) to compress the gas. The pressurized carbon dioxide or nitrogen is injected into the first oil and gas reservoir (1) through the gas injection switching valve (2). During this process, the waste heat at the outlet of the gas compressor (4) is recovered through the compressor stage heat exchanger (5). The heated heat storage medium is injected into the high temperature heat storage tank (13). Step 4: Repeat steps 2 and 3 in a loop.

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