A compressed air energy storage system and method based on depleted oil and gas reservoirs

Abstract

This invention discloses a compressed air energy storage system and method based on depleted oil and gas reservoirs. The system includes: a compression subsystem, a depleted oil and gas reservoir gas storage subsystem, and an expansion and power generation system. The compression subsystem and the depleted oil and gas reservoir gas storage subsystem are connected by pipelines, and the depleted oil and gas reservoir gas storage subsystem and the expansion and power generation system are also connected by pipelines. The compression subsystem is used to compress air; the depleted oil and gas reservoir gas storage subsystem is used to store the compressed air and to detect the natural gas concentration in the compressed air based on natural gas concentration measuring instruments included in the depleted oil and gas reservoir gas storage subsystem; the expansion and power generation system is used to heat and expand the air stored in the depleted oil and gas reservoir gas storage subsystem to perform work. This system flexibly selects the air heating method based on the measurement results, improving the operational stability of the compressed air energy storage system, avoiding environmental problems caused by residual natural gas in oil and gas wells, and has advantages such as high efficiency and environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of new energy technology, and in particular to a compressed air energy storage system and method based on depleted oil and gas reservoirs. Background Technology

[0002] Compressed air energy storage systems (CASS) are a technology suitable for power systems, enabling long-term, large-capacity energy storage with advantages such as safe and reliable operation, high efficiency, low carbon emissions, and environmental friendliness. Therefore, CASS has a very broad application prospect. Currently, commonly used CASS systems can be divided into non-adiabatic and adiabatic CASS systems based on their operating principles. Non-adiabatic CASS consumes combustible gases through combustion, but this method results in significant heat waste and low efficiency; therefore, non-adiabatic CASS is no longer the main research direction in CASS. In contrast, adiabatic CASS can recover compression heat and has the advantage of high efficiency, gradually becoming a research hotspot. Summary of the Invention

[0003] To improve the operational stability of compressed air energy storage systems and avoid environmental pollution caused by residual natural gas in oil and gas wells, this invention provides a compressed air energy storage system and method based on depleted oil and gas reservoirs.

[0004] In a first aspect, embodiments of the present invention provide a compressed air energy storage system based on a depleted oil and gas reservoir, which may include: a compression subsystem, a depleted oil and gas reservoir gas storage subsystem, and an expansion power generation system; the compression subsystem and the depleted oil and gas reservoir gas storage subsystem are connected by pipelines, and the depleted oil and gas reservoir gas storage subsystem and the expansion power generation system are connected by pipelines.

[0005] The compression subsystem is used to compress air; the depleted oil and gas reservoir storage subsystem is used to store compressed air and to detect the natural gas concentration in the compressed air based on the natural gas concentration measuring instrument included in the depleted oil and gas reservoir storage subsystem; the expansion and expansion subsystem is used to heat and expand the air stored in the depleted oil and gas reservoir storage subsystem to perform work.

[0006] In one embodiment, the compression subsystem may include: a plurality of compression stages connected in series, a cold storage tank, and a first pump;

[0007] In a series of multiple compression stages, each stage includes a compressor and a post-stage heat exchanger. The outlet of the compressor in each stage is connected to the air inlet of the post-stage heat exchanger via a pipeline. The inlet of the compressor in the next stage is connected to the air outlet of the post-stage heat exchanger in the previous stage via a pipeline. The inlet of the compressor in the first stage is open to the environment, and the air outlet of the post-stage heat exchanger in the last stage is connected to the first abandoned oil and gas well, which serves as the inlet in the depleted oil and gas reservoir, in the depleted oil and gas reservoir storage subsystem via a pipeline.

[0008] The outlet of the cold storage tank is connected to the inlet of the first pump via a pipe. The outlet of the first pump is connected to the water-side inlet of each stage of the post-heat exchanger via a pipe. The water-side outlet of each stage of the post-heat exchanger is connected to the inlet of the heat storage tank included in the expansion generator system via a pipe.

[0009] In one embodiment, the compression subsystem may include: a first-stage compressor, a first-stage post-stage heat exchanger, a second-stage compressor, a second-stage post-stage heat exchanger, a final-stage compressor, a final-stage post-stage heat exchanger, a cold storage tank, and a first pump.

[0010] The inlet of the first-stage compressor is open to the environment, and the outlet of the first-stage compressor is connected to the air inlet of the first-stage post-heat exchanger via a pipeline; the air outlet of the first-stage post-heat exchanger is connected to the inlet of the second-stage compressor via a pipeline, and the outlet of the second-stage compressor is connected to the air inlet of the second-stage post-heat exchanger via a pipeline; the air outlet of the second-stage post-heat exchanger is connected to the inlet of the last-stage compressor via a pipeline, and the outlet of the last-stage compressor is connected to the air inlet of the last-stage post-heat exchanger via a pipeline; the air outlet of the last-stage post-heat exchanger is connected to the first abandoned oil and gas well, which serves as the inlet in the depleted oil and gas reservoir included in the depleted oil and gas reservoir storage subsystem, via a pipeline.

[0011] The inlet of the cold storage tank is connected to the water-side outlet of the heat exchanger included in the expansion generator system via a pipeline, and the outlet of the cold storage tank is connected to the inlet of the first pump via a pipeline; the outlet of the first pump is connected to the water-side inlet of the first-stage heat exchanger, the water-side inlet of the second-stage heat exchanger, and the water-side inlet of the last-stage heat exchanger via pipelines.

[0012] In one embodiment, the depleted oil and gas reservoir gas storage subsystem may include: a depleted oil and gas reservoir, a first abandoned oil and gas well as an inlet, a second abandoned oil and gas well as an outlet, a natural gas concentration measuring instrument, and a throttle valve;

[0013] The depleted oil and gas reservoir serves as a gas storage chamber, and is connected to the first abandoned oil and gas well and the second abandoned oil and gas well, respectively. The natural gas concentration measuring instrument is placed inside the depleted oil and gas reservoir to detect the natural gas concentration in the air of the depleted oil and gas reservoir in real time. The inlet of the throttle valve is connected to the second abandoned oil and gas well through a pipeline, and the outlet of the throttle valve is connected to the pre-stage heat exchanger included in the expansion generator system through a pipeline.

[0014] In one embodiment, the expansion generator system may include: a plurality of expansion stages connected in series, a first three-way valve, a second three-way valve, a combustion chamber, a heat storage tank, and a second pump;

[0015] Each of the multiple expansion stages connected in series includes a pre-stage heat exchanger and a turbine. The air outlet of the pre-stage heat exchanger in each expansion stage is connected to the turbine inlet via a pipe. The air inlet of the pre-stage heat exchanger in the next expansion stage is connected to the turbine outlet in the previous expansion stage via a pipe. The air inlet of the pre-stage heat exchanger in the first expansion stage is connected to the outlet of the throttle valve via a pipe. The turbine outlet in the first expansion stage is connected to the inlet of the first three-way valve via a pipe. The outlet of the first three-way valve is connected to the air inlet of the pre-stage heat exchanger in the second expansion stage and the air inlet of the combustion chamber via pipes. The air outlet of the pre-stage heat exchanger in the second expansion stage is connected to the air inlet of the second three-way valve via a pipe. The flue gas outlet of the combustion chamber is connected to the flue gas inlet of the second three-way valve via a pipe. The outlet of the second three-way valve is connected to the turbine inlet in the second expansion stage via a pipe. The turbine outlet in the final expansion stage is open to the environment.

[0016] The outlet of the heat storage tank is connected to the inlet of the second pump via a pipeline. The outlet of the second pump is connected to the water-side inlet of each expansion stage intermediate preheater via a pipeline. The water-side outlet of each expansion stage intermediate preheater is connected to the inlet of the cold storage tank via a pipeline.

[0017] In one embodiment, the expansion generator system may include: a first-stage pre-stage heat exchanger, a first-stage turbine, a first three-way valve, a combustion chamber, a second-stage pre-stage heat exchanger, a second three-way valve, a second-stage turbine, a final-stage pre-stage heat exchanger, a final-stage turbine, a heat storage tank, and a second pump.

[0018] The air inlet of the first-stage pre-stage heat exchanger is connected to the outlet of the throttle valve via a pipe; the inlet of the first-stage turbine is connected to the air outlet of the first-stage pre-stage heat exchanger via a pipe; the outlet of the first-stage turbine is connected to the inlet of the first three-way valve via a pipe; the first outlet of the first three-way valve is connected to the air inlet of the combustion chamber via a pipe; the second outlet of the first three-way valve is connected to the air inlet of the second-stage pre-stage heat exchanger via a pipe; the flue gas outlet of the combustion chamber is connected to the flue gas inlet of the second three-way valve via a pipe; the air outlet of the second-stage pre-stage heat exchanger is connected to the air inlet of the second three-way valve via a pipe; the outlet of the second three-way valve is connected to the inlet of the second-stage turbine via a pipe; the outlet of the second-stage turbine is connected to the air inlet of the last-stage pre-stage heat exchanger via a pipe; the air outlet of the last-stage pre-stage heat exchanger is connected to the inlet of the last-stage turbine; and the outlet of the last-stage turbine is open to the environment.

[0019] The outlet of the heat storage tank is connected to the inlet of the second pump via a pipeline, and the outlet of the second pump is connected to the water-side inlet of the first-stage pre-stage heat exchanger, the water-side inlet of the second-stage pre-stage heat exchanger, and the water-side inlet of the last-stage pre-stage heat exchanger via pipelines.

[0020] Secondly, embodiments of the present invention provide a compressed air energy storage method based on depleted oil and gas reservoirs, wherein the compressed air energy storage method is implemented according to the compressed air energy storage system based on depleted oil and gas reservoirs described in the first aspect.

[0021] In one embodiment, the compressed air energy storage method may include:

[0022] During the energy storage phase, the power grid's off-peak load drives the compression subsystem to operate; air is compressed by the compression subsystem to reach the rated pressure and then sent to the depleted oil and gas reservoir's gas storage subsystem for storage.

[0023] During the energy release phase, the natural gas concentration in the compressed air of the depleted oil and gas reservoir storage subsystem is detected. If the natural gas concentration is lower than a preset concentration threshold, the compressed air stored in the depleted oil and gas reservoir storage subsystem is expanded and works through the expansion generator system. If the natural gas concentration is higher than the preset concentration threshold, the compressed air stored in the depleted oil and gas reservoir storage subsystem is burned and expanded through the expansion generator system.

[0024] In one embodiment, the compressed air energy storage method may specifically include:

[0025] During the energy storage phase, the off-peak load electricity from the power grid drives the compression subsystem to operate; air is compressed by multiple series-connected compression stages in the compression subsystem to reach the rated pressure and then sent to the depleted oil and gas reservoir in the depleted oil and gas reservoir storage subsystem for storage; cold water stored in the cold storage tank in the compression subsystem is drawn in by the first pump in the compression subsystem and delivered to the heat exchangers of each compression stage in the compression subsystem to absorb the heat of compression, and then delivered to the heat storage tank in the expansion power generation system for storage;

[0026] During the energy release phase, the natural gas concentration measuring instrument in the depleted oil and gas reservoir storage subsystem detects the natural gas concentration in the compressed air of the depleted oil and gas reservoir. If the natural gas concentration is lower than a preset concentration threshold, the second outlet of the first three-way valve and the air inlet of the second three-way valve in the expansion generator system are opened, and the first outlet of the first three-way valve and the flue gas inlet of the second three-way valve are closed. This allows the compressed air to pass sequentially through the pre-stage heat exchanger and turbine of each expansion stage in the expansion generator system. In the pre-stage heat exchanger, the compressed air absorbs the gas drawn in by the second pump in the expansion generator system. The heat energy of the hot water in the hot tank flows through each expansion stage to drive the turbine to expand and do work. If the natural gas concentration is higher than a preset concentration threshold, the first outlet of the second three-way valve and the flue gas inlet of the second three-way valve are opened, and the second outlet of the first three-way valve and the air inlet of the second three-way valve are closed. This allows the compressed air to mix and burn with the fuel in the combustion chamber of the expansion generator system before entering the subsequent expansion stages. The compressed air in the pre-stage heat exchanger absorbs the heat energy from the hot water in the heat storage tank and flows through each expansion stage to drive the turbine to expand and do work. The cold water that has undergone heat exchange in the pre-stage heat exchanger is sent to the cold storage tank for storage.

[0027] In one detailed embodiment, the compressed air energy storage method may specifically include:

[0028] During the energy storage phase, off-peak electricity from the power grid drives the compression subsystem. Air is compressed by the first-stage compressor in the compression subsystem and then sent to the first-stage post-compression heat exchanger for cooling. Then, it is compressed by the second-stage compressor and sent to the second-stage post-compression heat exchanger for further cooling. Finally, it is compressed by the last-stage compressor and sent to the last-stage post-compression heat exchanger for cooling. The cooled compressed air is then sent to a depleted oil and gas reservoir for storage. Cold water stored in the cold storage tank included in the compression subsystem is drawn in by the first pump included in the compression subsystem and transported to the first-stage, second-stage, and last-stage post-compression heat exchangers to absorb the heat of compression, and then input into the heat storage tank for storage.

[0029] During the energy release phase, the natural gas concentration measuring instrument detects the natural gas concentration in the compressed air of the depleted oil and gas reservoir. If the natural gas concentration is lower than a preset concentration threshold, the second outlet of the first three-way valve and the air inlet of the second three-way valve are opened, and the first outlet of the first three-way valve and the flue gas inlet of the second three-way valve are closed. The compressed air passes through the throttle valve in the gas storage subsystem of the depleted oil and gas reservoir and then sequentially through the first-stage pre-stage heat exchanger, first-stage turbine, first three-way valve, second-stage pre-stage heat exchanger, second three-way valve, second-stage turbine, last-stage pre-stage heat exchanger, and last-stage turbine in the expansion generator system. The first-stage pre-stage heat exchanger, second-stage pre-stage heat exchanger, and last-stage pre-stage heat exchanger absorb heat energy from the heat storage tank and heat the compressed air. The first-stage turbine, second-stage turbine, and last-stage turbine perform work through the expansion of the compressed air. If the natural gas concentration is higher than the preset concentration threshold, the instrument opens... The first outlet and flue gas inlet of the second three-way valve are opened, while the second outlet and air inlet of the first three-way valve are closed. Compressed air enters the combustion chamber after passing through the first-stage pre-stage heat exchanger, the first-stage turbine, and the first three-way valve. After mixing and burning with fuel, it enters the second-stage turbine through the second three-way valve and then exits after passing through the last-stage pre-stage heat exchanger and the last-stage turbine. The compressed air in the first-stage and last-stage pre-stage heat exchangers absorbs heat energy from the hot water in the heat storage tank, and the combustion in the combustion chamber heats the compressed air. The first-stage, second-stage, and last-stage turbines perform work through the expansion of the compressed air. The first-stage, second-stage, and last-stage pre-stage heat exchangers absorb heat energy from the hot water in the heat storage tank and send the cooled water after heat exchange to the cold storage tank for storage.

[0030] The beneficial effects of the above-mentioned technical solutions provided in the embodiments of the present invention include at least the following:

[0031] This invention provides a compressed air energy storage system and method based on depleted oil and gas reservoirs. The compressed air energy storage system detects the concentration of natural gas using a natural gas concentration measuring instrument and flexibly selects the air heating method based on the measurement results. This improves the stability of the compressed air energy storage system's operation and avoids environmental problems caused by residual natural gas in oil and gas wells. It has advantages such as high efficiency and environmental friendliness.

[0032] 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 may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0033] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0034] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0035] Figure 1 This is a schematic diagram of the structure of a compressed air energy storage system based on a depleted oil and gas reservoir provided in an embodiment of the present invention;

[0036] Among them, 1-compression subsystem; 2-gas storage subsystem of depleted oil and gas reservoir; 3-expansion and power generation system;

[0037] 101 - First stage compressor; 102 - First stage post-stage heat exchanger; 103 - Second stage compressor; 104 - Second stage post-stage heat exchanger; 105 - Last stage compressor; 106 - Last stage post-stage heat exchanger; 107 - Cold storage tank; 108 - First pump;

[0038] 201 - Depleted oil and gas reservoir; 202 - First abandoned oil and gas well; 203 - Second abandoned oil and gas well; 204 - Natural gas concentration measuring instrument; 205 - Throttling valve;

[0039] 301 - First stage pre-stage heat exchanger; 302 - First stage turbine; 303 - First three-way valve; 304 - Combustion chamber; 305 - Second stage pre-stage heat exchanger; 306 - Second three-way valve; 307 - Second stage turbine; 308 - Last stage pre-stage heat exchanger; 309 - Last stage turbine; 310 - Heat storage tank; 311 - Second pump. Detailed Implementation

[0040] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0041] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "far," "near," "front," and "rear," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0042] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0043] The inventors discovered in practical work that adiabatic compressed air energy storage cannot solve the problem of residual natural gas emissions. Therefore, when using abandoned oil and gas wells as storage chambers for adiabatic compressed air energy storage power plants, it is necessary to eliminate residual combustible gases in the wells; however, current adiabatic compressed air energy storage methods cannot solve this problem. In view of the above problems, this invention is proposed to provide a compressed air energy storage system and method based on depleted oil and gas reservoirs that overcomes or at least partially solves the above problems. The purpose of this invention is to utilize abandoned oil and gas wells left after the depletion of oil and gas production as storage chambers for compressed air energy storage systems, thereby reducing construction costs and achieving the rational utilization of abandoned oil and gas wells.

[0044] This invention provides a compressed air energy storage system based on depleted oil and gas reservoirs, referring to... Figure 1 As shown, the compressed air energy storage system may include: a compression subsystem 1, a depleted oil and gas reservoir storage subsystem 2, and an expansion and power generation system 3; the compression subsystem 1 and the depleted oil and gas reservoir storage subsystem 2 are connected by pipelines, and the depleted oil and gas reservoir storage subsystem 2 and the expansion and power generation system 3 are connected by pipelines; the compression subsystem 1 is used to compress air; the depleted oil and gas reservoir storage subsystem 2 is used to store compressed air and to detect the natural gas concentration in the compressed air based on the natural gas concentration measuring instrument 204 included in the depleted oil and gas reservoir storage subsystem 2; the expansion and power generation system 3 is used to heat and expand the air stored in the depleted oil and gas reservoir storage subsystem 2 to perform work.

[0045] The compressed air energy storage system provided in this embodiment of the invention detects the concentration of natural gas using a natural gas concentration measuring instrument 204 and flexibly selects the air heating method based on the measurement results. This improves the stability of the operation of the compressed air energy storage system, avoids environmental problems caused by residual natural gas in oil and gas wells, and has the advantages of high efficiency and environmental friendliness.

[0046] In one embodiment, refer to Figure 1 As shown, the compression subsystem 1 may include: multiple series-connected compression stages, a cold storage tank 107, and a first pump 108; each compression stage in the multiple series-connected compression stages includes a compressor and a post-stage heat exchanger; the outlet of the compressor in each compression stage is connected to the air inlet of the post-stage heat exchanger via a pipeline, and the inlet of the compressor in the next compression stage is connected to the air outlet of the post-stage heat exchanger in the previous compression stage via a pipeline; the inlet of the compressor in the first compression stage is in communication with the environment, and the air outlet of the post-stage heat exchanger in the last compression stage is connected to the first abandoned oil and gas well 202, which serves as the inlet of the depleted oil and gas reservoir 201 included in the depleted oil and gas reservoir storage subsystem 2, via a pipeline; the outlet of the cold storage tank 107 is connected to the inlet of the first pump 108 via a pipeline, the outlet of the first pump 108 is connected to the water-side inlet of each post-stage heat exchanger via a pipeline, and the water-side outlet of each post-stage heat exchanger is connected to the inlet of the heat storage tank 310 included in the expansion generator system 3 via a pipeline.

[0047] It should be noted that the first pump 108 in this embodiment is a cold water pump, which introduces cold water from the cold storage tank 107 into the water circuits of each stage of the heat exchanger to absorb and store the heat of compression. In this embodiment of the invention, the cold storage tank 107 and the first pump 108 absorb the heat of compression in the water circuits of each stage of the heat exchanger, and then store it through the heat storage tank 310 in the expansion generator system 3. Compared with the prior art of simply compressing and storing air, this avoids simply converting electrical energy into the internal energy (mainly pressure energy and thermal energy) of compressed air during off-peak periods, and avoids the problem of compressed air being too hot to store. On the other hand, by using the cold storage tank 107, the cold water pump, and the multi-stage heat exchangers, the heat of compression generated by the high-temperature compressed air is stored in a timely manner, avoiding heat loss.

[0048] In one specific embodiment, refer to Figure 1As shown, the compression subsystem 1 may include: a first-stage compressor 101, a first-stage post-stage heat exchanger 102, a second-stage compressor 103, a second-stage post-stage heat exchanger 104, a final-stage compressor 105, a final-stage post-stage heat exchanger 106, a cold storage tank 107, and a first pump 108; the inlet of the first-stage compressor 101 is in communication with the environment, and the outlet of the first-stage compressor 101 is connected to the air inlet of the first-stage post-stage heat exchanger 102 via a pipe; the air outlet of the first-stage post-stage heat exchanger 102 is connected to the inlet of the second-stage compressor 103 via a pipe, and the outlet of the second-stage compressor 103 is connected to the air inlet of the second-stage post-stage heat exchanger 104 via a pipe; the air outlet of the second-stage post-stage heat exchanger 104 is connected to the final-stage compressor 105. The inlet of 5 is connected by a pipe, the outlet of the final stage compressor 105 is connected by a pipe to the air inlet of the final stage heat exchanger 106, and the air outlet of the final stage heat exchanger 106 is connected by a pipe to the first abandoned oil and gas well 202, which is the inlet of the depleted oil and gas reservoir 201 included in the depleted oil and gas reservoir gas storage subsystem 2; the inlet of the cold storage tank 107 is connected by a pipe to the water-side outlet of the heat exchanger included in the expansion generator system 3, and the outlet of the cold storage tank 107 is connected by a pipe to the inlet of the first pump 108; the outlet of the first pump 108 is connected by pipes to the water-side inlet of the first stage heat exchanger 102, the water-side inlet of the second stage heat exchanger 104, and the water-side inlet of the final stage heat exchanger 106.

[0049] In this embodiment of the invention, the compression subsystem 1 consists of a three-stage compression stage. By compressing and cooling the air in stages, high-pressure compressed air is obtained, and electrical energy is stored as pressure energy. At the same time, the compression heat in the water circuit of the heat exchanger after each stage is absorbed by the cold storage tank 107 and the first pump 108 after the three-stage compression stage, and part of the electrical energy is stored as heat energy. Compared with the prior art, which simply stores pressure energy, heat energy loss is avoided.

[0050] In another embodiment, refer to Figure 1 As shown, the depleted oil and gas reservoir gas storage subsystem 2 may include: a depleted oil and gas reservoir 201, a first abandoned oil and gas well 202 as the inlet, a second abandoned oil and gas well 203 as the outlet, a natural gas concentration measuring instrument 204, and a throttle valve 205; the depleted oil and gas reservoir 201 serves as a gas storage chamber, and is connected to the first abandoned oil and gas well 202 and the second abandoned oil and gas well 203 respectively; the natural gas concentration measuring instrument 204 is placed inside the depleted oil and gas reservoir 201 and is used to detect the natural gas concentration of the air in the depleted oil and gas reservoir 201 in real time; the inlet of the throttle valve 205 is connected to the second abandoned oil and gas well 203 through a pipeline, and the outlet of the throttle valve 205 is connected to the pre-stage heat exchanger included in the expansion generator system 3 through a pipeline.

[0051] It should be noted that a depleted oil and gas reservoir 201 can be connected to multiple abandoned oil and gas wells. Some of these abandoned wells serve as the inlet of the gas storage subsystem 2 of the depleted oil and gas reservoir in the compressed air energy storage system, namely the first abandoned well 202; others serve as the outlet of the gas storage subsystem 2 of the depleted oil and gas reservoir in the compressed air energy storage system, namely the second abandoned well 203. The first abandoned well 202 and the second abandoned well 203 can be arranged according to the specific site construction conditions, and this embodiment of the invention does not impose specific limitations on this.

[0052] The depleted oil and gas reservoir gas storage subsystem 2 provided in this embodiment of the invention is constructed based on the depleted oil and gas reservoir 201 and abandoned oil and gas wells left after the completion of oil and gas extraction. The depleted oil and gas reservoir 201 is used as the gas storage chamber of the compressed air energy storage system, which can reduce construction costs and realize the rational utilization of abandoned oil and gas wells.

[0053] In another embodiment, refer to Figure 1 As shown, the expansion generator system 3 may include: multiple expansion stages connected in series, a first three-way valve 303, a second three-way valve 306, a combustion chamber 304, a heat storage tank 310, and a second pump 311; each expansion stage in the series connection includes a pre-stage heat exchanger and a turbine; the air outlet of the pre-stage heat exchanger in each expansion stage is connected to the turbine inlet via a pipe, and the air inlet of the pre-stage heat exchanger in the next expansion stage is connected to the turbine outlet in the previous expansion stage via a pipe; the air inlet of the pre-stage heat exchanger in the first expansion stage is connected to the outlet of the throttle valve 205 via a pipe, the turbine outlet in the first expansion stage is connected to the inlet of the first three-way valve 303 via a pipe, and the outlet of the first three-way valve 303 is connected to the second expansion stage... The air inlet of the intermediate preheater of the expansion stage and the air inlet of the combustion chamber 304 are connected by pipes; the air outlet of the intermediate preheater of the second expansion stage is connected by pipes to the air inlet of the second three-way valve 306, the flue gas outlet of the combustion chamber 304 is connected by pipes to the flue gas inlet of the second three-way valve 306, and the outlet of the second three-way valve 306 is connected by pipes to the inlet of the turbine in the second expansion stage; the outlet of the turbine in the final expansion stage is in communication with the environment; the outlet of the heat storage tank 310 is connected by pipes to the inlet of the second pump 311, the outlet of the second pump 311 is connected by pipes to the water-side inlet of each intermediate preheater of the expansion stage, and the water-side outlet of each intermediate preheater of the expansion stage is connected by pipes to the inlet of the cold storage tank 107.

[0054] It should be noted that the second pump 311 in this embodiment is a hot water pump, which introduces hot water from the heat storage tank 310 into the water circuit of each stage of the preheating heat exchanger to release heat to heat the compressed air, and stores the cold water in the cold storage tank 107. The expansion power generation system 3 described above in this embodiment generates heat through the combustion of residual natural gas in the combustion chamber 304, converting this heat into electrical energy, thus avoiding resource waste and environmental pollution; on the other hand, it heats the compressed air by collecting the heat of compression, further improving the conversion efficiency when the compressed air expands and does work, and enhancing the energy storage capacity of the compressed air energy storage system.

[0055] In one specific embodiment, refer to Figure 1 As shown, the expansion generator system 3 may include: a first-stage pre-stage heat exchanger 301, a first-stage turbine 302, a first three-way valve 303, a combustion chamber 304, a second-stage pre-stage heat exchanger 305, a second three-way valve 306, a second-stage turbine 307, a final-stage pre-stage heat exchanger 308, a final-stage turbine 309, a heat storage tank 310, and a second pump 311; the air inlet of the first-stage pre-stage heat exchanger 301 is connected to the outlet of the throttle valve 205 via a pipe, and the inlet of the first-stage turbine 302 is connected to the air outlet of the first-stage pre-stage heat exchanger 301 via a pipe; the outlet of the first-stage turbine 302 is connected to the inlet of the first three-way valve 303 via a pipe; the first outlet of the first three-way valve 303 is connected to the air inlet of the combustion chamber 304 via a pipe, and the second outlet of the first three-way valve 303 is connected to the air inlet of the second-stage pre-stage heat exchanger via a pipe. Connections: The flue gas outlet of combustion chamber 304 is connected to the flue gas inlet of second three-way valve 306 via a pipe; the air outlet of the second-stage preheater is connected to the air inlet of second three-way valve 306 via a pipe; the outlet of second three-way valve 306 is connected to the inlet of second-stage turbine 307 via a pipe; the outlet of second-stage turbine 307 is connected to the air inlet of final-stage preheater 308 via a pipe; the air outlet of final-stage preheater 308 is connected to the inlet of final-stage turbine 309; the outlet of final-stage turbine 309 is open to the environment; the outlet of heat storage tank 310 is connected to the inlet of second pump 311 via a pipe; the outlet of second pump 311 is connected to the water-side inlet of first-stage preheater 301, water-side inlet of second-stage preheater 305, and water-side inlet of final-stage preheater 308 via pipes.

[0056] In this embodiment, the turbine expands and performs work in three stages of expansion, which facilitates the conversion of the compressed heat stored in the heat storage tank 310 into electrical energy step by step. On the other hand, the pressure energy of the compressed air is released step by step, which improves the conversion efficiency. Furthermore, the residual natural gas in the depleted oil and gas reservoir 201 is fully utilized to convert the energy of fossil fuels into electrical energy through thermal energy, which not only avoids energy waste and environmental pollution, but also improves the energy storage capacity of the compressed air energy storage system.

[0057] Based on the same inventive concept, this embodiment of the invention also provides a compressed air energy storage method based on depleted oil and gas reservoirs, which is implemented according to the above-mentioned compressed air energy storage system based on depleted oil and gas reservoirs.

[0058] In an optional embodiment, combined with Figure 1 As shown, the above-mentioned compressed air energy storage method based on depleted oil and gas reservoirs may include:

[0059] During the energy storage phase, the power grid's off-peak load drives the compression subsystem 1 to work; the air is compressed by the compression subsystem 1 and sent to the depleted oil and gas reservoir storage subsystem 2 for storage after reaching the rated pressure.

[0060] During the energy release phase, the natural gas concentration of the compressed air in the depleted oil and gas reservoir storage subsystem 2 is detected. If the natural gas concentration is lower than the preset concentration threshold, the compressed air stored in the depleted oil and gas reservoir storage subsystem 2 is expanded and works through the expansion generator system 3. If the natural gas concentration is higher than the preset concentration threshold, the compressed air stored in the depleted oil and gas reservoir storage subsystem 2 is burned and expanded and works through the expansion generator system 3.

[0061] In one specific embodiment, combined with Figure 1 As shown, the above-mentioned compressed air energy storage method based on depleted oil and gas reservoirs may include:

[0062] During the energy storage phase, the off-peak load power of the power grid drives the operation of the compression subsystem 1; the air is compressed by multiple series-connected compression stages in the compression subsystem 1 and sent to the depleted oil and gas reservoir 201 in the depleted oil and gas reservoir storage subsystem 2 for storage after reaching the rated pressure; the cold water stored in the cold storage tank 107 in the compression subsystem 1 is drawn in by the first pump 108 in the compression subsystem 1 and delivered to the heat exchangers of each compression stage in the compression subsystem 1 to absorb the heat of compression, and then delivered to the heat storage tank 310 in the expansion power generation system 3 for storage;

[0063] During the energy release phase, the natural gas concentration measuring instrument 204 in the depleted oil and gas reservoir storage subsystem 2 detects the natural gas concentration of the compressed air in the depleted oil and gas reservoir 201. If the natural gas concentration is lower than a preset concentration threshold, the second outlet of the first three-way valve 303 in the expansion generator system 3 and the air inlet of the second three-way valve 306 in the expansion generator system 3 are opened, while the first outlet of the first three-way valve 303 and the flue gas inlet of the second three-way valve 306 are closed. This allows the compressed air to pass sequentially through the pre-stage heat exchangers and turbines of each expansion stage in the expansion generator system 3. In the pre-stage heat exchangers, the compressed air absorbs the gas drawn in by the second pump 311 in the expansion generator system 3. The heat energy of the hot water in the hot tank 310 flows through each expansion stage to drive the turbine to expand and do work. If the natural gas concentration is higher than the preset concentration threshold, the first outlet of the second three-way valve 306 and the flue gas inlet of the second three-way valve 306 are opened, and the second outlet of the first three-way valve 303 and the air inlet of the second three-way valve 306 are closed. The compressed air is mixed and burned with the fuel in the combustion chamber 304 of the expansion generator system 3, and then enters the subsequent expansion stages. The compressed air in the pre-stage heat exchanger absorbs the heat energy from the hot water in the hot tank 310 and flows through each expansion stage to drive the turbine to expand and do work. The cold water in the pre-stage heat exchanger after heat exchange is sent to the cold storage tank 107 for storage.

[0064] In a detailed embodiment, combined with Figure 1 As shown, the above-mentioned compressed air energy storage method based on depleted oil and gas reservoirs may include:

[0065] During the energy storage phase, off-peak electricity from the power grid drives the operation of the compression subsystem 1. Air is compressed by the first-stage compressor 101 in the compression subsystem 1 and then sent to the first-stage post-heat exchanger 102 for cooling. Next, it is compressed by the second-stage compressor 103 in the compression subsystem 1 and then sent to the second-stage post-heat exchanger 104 for further cooling. Finally, it is compressed by the final-stage compressor 105 in the compression subsystem 1 and then sent to the compressor... The compressed air is cooled in the last stage heat exchanger 106 of the compression subsystem 1; the compressed air cooled by the last stage heat exchanger 106 is sent to the depleted oil and gas reservoir 201 for storage; the cold water stored in the cold storage tank 107 included in the compression subsystem 1 is drawn in by the first pump 108 included in the compression subsystem 1 and sent to the first stage heat exchanger 102, the second stage heat exchanger 104 and the last stage heat exchanger 106 to absorb the heat of compression, and then input into the heat storage tank 310 for storage;

[0066] During the energy release phase, the natural gas concentration measuring instrument 204 detects the natural gas concentration of the compressed air in the depleted oil and gas reservoir 201. If the natural gas concentration is lower than the preset concentration threshold, the second outlet of the first three-way valve 303 and the air inlet of the second three-way valve 306 are opened, and the first outlet of the first three-way valve 303 and the flue gas inlet of the second three-way valve 306 are closed. The compressed air passes through the throttle valve 205 in the depleted oil and gas reservoir storage subsystem 2 and then sequentially passes through the first-stage preheater 301 in the expansion generator system 3. The system consists of a first-stage turbine 302, a first three-way valve 303, a second-stage pre-stage heat exchanger 305, a second three-way valve 306, a second-stage turbine 307, a final-stage pre-stage heat exchanger 308, and a final-stage turbine 309. The first-stage pre-stage heat exchanger 301, the second-stage pre-stage heat exchanger 305, and the final-stage pre-stage heat exchanger 308 absorb heat energy from the heat storage tank 310 and heat the compressed air. The first-stage turbine 302, the second-stage turbine 307, and the final-stage turbine 309 perform work through the expansion of the compressed air. If the natural gas concentration is higher than the preset value... If the concentration threshold is reached, the first outlet of the second three-way valve 306 and the flue gas inlet of the second three-way valve 306 are opened, while the second outlet of the first three-way valve 303 and the air inlet of the second three-way valve 306 are closed. Compressed air passes through the first-stage pre-stage heat exchanger 301, the first-stage turbine 302, and the first three-way valve 303 before entering the combustion chamber 304 to mix and burn with the fuel. After combustion, it passes through the second three-way valve 306 into the second-stage turbine 307, and then passes through the last-stage pre-stage heat exchanger 308 and the last-stage turbine 309 before being discharged. The compressed air in the pre-stage heat exchanger 301 and the final-stage pre-stage heat exchanger 308 absorbs the heat energy from the hot water in the heat storage tank 310, and the combustion in the combustion chamber 304 heats the compressed air; the first-stage turbine 302, the second-stage turbine 307 and the final-stage turbine 309 do work by expanding the compressed air; the first-stage pre-stage heat exchanger 301, the second-stage pre-stage heat exchanger 305 and the final-stage pre-stage heat exchanger 308 absorb the heat energy from the hot water in the heat storage tank 310, and the cooled water after heat exchange is sent to the cold storage tank 107 for storage.

[0067] In a specific example, refer to Figure 1As shown, the above-mentioned compressed air energy storage method based on depleted oil and gas reservoirs may include: during the low-load phase of the power grid, the compression subsystem 1 starts working, using off-peak electricity to drive the compressor. Atmospheric air is drawn into the first-stage compressor 101 and compressed to 470 kPa and 485 K; then it is sent to the first-stage post-heat exchanger 102 to be cooled to 317 K; the cooled air flows into the second-stage compressor 103 and is further pressurized to 2180 kPa and 515 K; then the air at the outlet of the second-stage compressor 103 flows into the second-stage post-heat exchanger 104 to be cooled to 320 K; after passing through the second-stage post-heat exchanger... After being cooled, the air flows into the final stage compressor 105. The outlet air pressure of the final stage compressor 105 is 10000 kPa and 520 K. The outlet air of the final stage compressor 105 flows into the final stage heat exchanger 106, where the temperature is reduced to around 320 K before being sent to the depleted oil and gas reservoir 201 via the first abandoned oil and gas well 202. The water used for cooling the air in the first stage heat exchanger 102, the second stage heat exchanger 104, and the final stage heat exchanger 106 is cold water at 293 K pumped from the cold storage tank 107 by the cold water pump (first pump 108). The water temperature after heat exchange is about 485 K and is stored in the heat storage tank 310.

[0068] During periods of high power load, the expansion generator system 3 begins operation; the natural gas concentration is measured in the depleted oil and gas reservoir 201 using the natural gas concentration measuring instrument 204; if the natural gas concentration exceeds 0.5%, the outlet of the cold air three-way valve (first three-way valve 303) and the inlet of the hot air three-way valve (second three-way valve 306) are closed, while the outlet of the cold air three-way valve and the inlet of the hot air three-way valve are opened; conversely, if the natural gas concentration is below 0.5%, the outlet of the cold air three-way valve and the inlet of the hot air three-way valve are closed, while the outlet of the cold air three-way valve and the inlet of the hot air three-way valve are opened. The three-way valve inlet is opened; the throttle valve 205 is opened, and the compressed air stored in the depleted oil and gas reservoir 201 at a pressure of 9900 kPa is discharged through the second abandoned oil and gas well 203. The temperature of the compressed air at the outlet of the throttle valve 205 is 319 K and the pressure is 9800 kPa. The compressed air flows into the first-stage pre-stage heat exchanger 301, and at the same time, the hot water in the heat storage tank 310 flows into the first-stage pre-stage heat exchanger 301 to heat the temperature of the compressed air to 470 K. The air at the outlet of the first-stage heat exchanger flows into the first-stage turbine 302 to expand and do work. The air at the outlet of the first-stage turbine 302... The gas temperature and pressure are 340K and 2200kPa, respectively. Air from the outlet of the first-stage turbine 302 flows into a cold air three-way valve. If the natural gas concentration in the abandoned oil and gas well is higher than 0.5%, the compressed air flows into the combustion chamber 304 to mix and burn with the natural gas fuel, heating the air to 510K. If the natural gas concentration is lower than 0.5%, the compressed air flows into the second-stage pre-stage heat exchanger 305, where it is heated to 470K using hot water from the heat storage tank 310. The heated compressed air then flows into the inlet of the second-stage turbine 307 to continue expanding and performing work. The outlet air temperature of turbine 307 is approximately 350K, and the pressure is approximately 490kPa. Subsequently, the compressed air flows into the final stage pre-stage heat exchanger 308 and is heated for the last time by the hot water in the heat storage tank 310, raising the temperature to 470K. The outlet air of the final stage pre-stage heat exchanger 308 flows into the final stage turbine 309, expands and does work, reducing the pressure to 110kPa before being discharged into the atmosphere. The hot water that has undergone heat exchange in the first stage pre-stage heat exchanger 301, the second stage pre-stage heat exchanger 305, and the final stage pre-stage heat exchanger 308 is cooled and then transported to the cold storage tank 107 for storage.

[0069] For a detailed description of the compressed air energy storage method for depleted oil and gas reservoirs provided in the embodiments of the present invention and its beneficial effects, please refer to the relevant introduction of the compressed air energy storage system described above. The embodiments of the present invention will not be repeated here.

[0070] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. This disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims. Thus, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. A compressed air energy storage system based on depleted oil and gas reservoirs, characterized in that, include: The system comprises a compression subsystem, a depleted oil and gas reservoir gas storage subsystem, and an expansion and power generation system; the compression subsystem and the depleted oil and gas reservoir gas storage subsystem are connected by pipelines, and the depleted oil and gas reservoir gas storage subsystem and the expansion and power generation system are also connected by pipelines. The compression subsystem is used to compress air; the depleted oil and gas reservoir storage subsystem is used to store compressed air and to detect the natural gas concentration in the compressed air based on the natural gas concentration measuring instrument included in the depleted oil and gas reservoir storage subsystem; the expansion and expansion subsystem is used to heat and expand the air stored in the depleted oil and gas reservoir storage subsystem to perform work.

2. The compressed air energy storage system according to claim 1, characterized in that, The compression subsystem includes: multiple compression stages connected in series, a cold storage tank, and a first pump; In a series of multiple compression stages, each stage includes a compressor and a post-stage heat exchanger. The outlet of the compressor in each stage is connected to the air inlet of the post-stage heat exchanger via a pipeline. The inlet of the compressor in the next stage is connected to the air outlet of the post-stage heat exchanger in the previous stage via a pipeline. The inlet of the compressor in the first stage is open to the environment, and the air outlet of the post-stage heat exchanger in the last stage is connected to the first abandoned oil and gas well, which serves as the inlet in the depleted oil and gas reservoir, in the depleted oil and gas reservoir storage subsystem via a pipeline. The outlet of the cold storage tank is connected to the inlet of the first pump via a pipe. The outlet of the first pump is connected to the water-side inlet of each stage of the post-heat exchanger via a pipe. The water-side outlet of each stage of the post-heat exchanger is connected to the inlet of the heat storage tank included in the expansion generator system via a pipe.

3. The compressed air energy storage system according to claim 2, characterized in that, The compression subsystem includes: a first-stage compressor, a first-stage post-stage heat exchanger, a second-stage compressor, a second-stage post-stage heat exchanger, a final-stage compressor, a final-stage post-stage heat exchanger, a cold storage tank, and a first pump; The inlet of the first-stage compressor is open to the environment, and the outlet of the first-stage compressor is connected to the air inlet of the first-stage post-heat exchanger via a pipeline; the air outlet of the first-stage post-heat exchanger is connected to the inlet of the second-stage compressor via a pipeline, and the outlet of the second-stage compressor is connected to the air inlet of the second-stage post-heat exchanger via a pipeline; the air outlet of the second-stage post-heat exchanger is connected to the inlet of the last-stage compressor via a pipeline, and the outlet of the last-stage compressor is connected to the air inlet of the last-stage post-heat exchanger via a pipeline; the air outlet of the last-stage post-heat exchanger is connected to the first abandoned oil and gas well, which serves as the inlet in the depleted oil and gas reservoir included in the depleted oil and gas reservoir storage subsystem, via a pipeline. The inlet of the cold storage tank is connected to the water-side outlet of the heat exchanger included in the expansion generator system via a pipeline, and the outlet of the cold storage tank is connected to the inlet of the first pump via a pipeline; the outlet of the first pump is connected to the water-side inlet of the first-stage heat exchanger, the water-side inlet of the second-stage heat exchanger, and the water-side inlet of the last-stage heat exchanger via pipelines.

4. The compressed air energy storage system according to claim 3, characterized in that, The depleted oil and gas reservoir gas storage subsystem includes: a depleted oil and gas reservoir, a first abandoned oil and gas well as an inlet, a second abandoned oil and gas well as an outlet, natural gas concentration measuring instruments, and a throttle valve; The depleted oil and gas reservoir serves as a gas storage chamber, and is connected to the first abandoned oil and gas well and the second abandoned oil and gas well, respectively. The natural gas concentration measuring instrument is placed inside the depleted oil and gas reservoir to detect the natural gas concentration in the air of the depleted oil and gas reservoir in real time. The inlet of the throttle valve is connected to the second abandoned oil and gas well through a pipeline, and the outlet of the throttle valve is connected to the pre-stage heat exchanger included in the expansion generator system through a pipeline.

5. The compressed air energy storage system according to claim 4, characterized in that, The expansion generator system includes: multiple expansion stages connected in series, a first three-way valve, a second three-way valve, a combustion chamber, a heat storage tank, and a second pump; Each of the multiple expansion stages connected in series includes a pre-stage heat exchanger and a turbine. The air outlet of the pre-stage heat exchanger in each expansion stage is connected to the turbine inlet via a pipe. The air inlet of the pre-stage heat exchanger in the next expansion stage is connected to the turbine outlet in the previous expansion stage via a pipe. The air inlet of the pre-stage heat exchanger in the first expansion stage is connected to the outlet of the throttle valve via a pipe. The turbine outlet in the first expansion stage is connected to the inlet of the first three-way valve via a pipe. The outlet of the first three-way valve is connected to the air inlet of the pre-stage heat exchanger in the second expansion stage and the air inlet of the combustion chamber via pipes. The air outlet of the pre-stage heat exchanger in the second expansion stage is connected to the air inlet of the second three-way valve via a pipe. The flue gas outlet of the combustion chamber is connected to the flue gas inlet of the second three-way valve via a pipe. The outlet of the second three-way valve is connected to the turbine inlet in the second expansion stage via a pipe. The turbine outlet in the final expansion stage is open to the environment. The outlet of the heat storage tank is connected to the inlet of the second pump via a pipeline. The outlet of the second pump is connected to the water-side inlet of each expansion stage intermediate preheater via a pipeline. The water-side outlet of each expansion stage intermediate preheater is connected to the inlet of the cold storage tank via a pipeline.

6. The compressed air energy storage system according to claim 4 or 5, characterized in that, The expansion generator system includes: a first-stage pre-stage heat exchanger, a first-stage turbine, a first three-way valve, a combustion chamber, a second-stage pre-stage heat exchanger, a second three-way valve, a second-stage turbine, a final-stage pre-stage heat exchanger, a final-stage turbine, a heat storage tank, and a second pump. The air inlet of the first-stage pre-stage heat exchanger is connected to the outlet of the throttle valve via a pipe; the inlet of the first-stage turbine is connected to the air outlet of the first-stage pre-stage heat exchanger via a pipe; the outlet of the first-stage turbine is connected to the inlet of the first three-way valve via a pipe; the first outlet of the first three-way valve is connected to the air inlet of the combustion chamber via a pipe; the second outlet of the first three-way valve is connected to the air inlet of the second-stage pre-stage heat exchanger via a pipe; the flue gas outlet of the combustion chamber is connected to the flue gas inlet of the second three-way valve via a pipe; the air outlet of the second-stage pre-stage heat exchanger is connected to the air inlet of the second three-way valve via a pipe; the outlet of the second three-way valve is connected to the inlet of the second-stage turbine via a pipe; the outlet of the second-stage turbine is connected to the air inlet of the last-stage pre-stage heat exchanger via a pipe; the air outlet of the last-stage pre-stage heat exchanger is connected to the inlet of the last-stage turbine; and the outlet of the last-stage turbine is open to the environment. The outlet of the heat storage tank is connected to the inlet of the second pump via a pipeline, and the outlet of the second pump is connected to the water-side inlet of the first-stage pre-stage heat exchanger, the water-side inlet of the second-stage pre-stage heat exchanger, and the water-side inlet of the last-stage pre-stage heat exchanger via pipelines.

7. A compressed air energy storage method based on depleted oil and gas reservoirs, characterized in that, The compressed air energy storage method is implemented according to any one of claims 1 to 6 based on a compressed air energy storage system of a depleted oil and gas reservoir.

8. The compressed air energy storage method according to claim 7, characterized in that, The method includes: During the energy storage phase, the power grid's off-peak load drives the compression subsystem to operate; air is compressed by the compression subsystem to reach the rated pressure and then sent to the depleted oil and gas reservoir's gas storage subsystem for storage. During the energy release phase, the natural gas concentration in the compressed air of the depleted oil and gas reservoir storage subsystem is detected. If the natural gas concentration is lower than a preset concentration threshold, the compressed air stored in the depleted oil and gas reservoir storage subsystem is expanded and works through the expansion generator system. If the natural gas concentration is higher than the preset concentration threshold, the compressed air stored in the depleted oil and gas reservoir storage subsystem is burned and expanded through the expansion generator system.

9. The compressed air energy storage method according to claim 8, characterized in that, The method includes: During the energy storage phase, the off-peak load electricity from the power grid drives the compression subsystem to operate; air is compressed by multiple series-connected compression stages in the compression subsystem to reach the rated pressure and then sent to the depleted oil and gas reservoir in the depleted oil and gas reservoir storage subsystem for storage; cold water stored in the cold storage tank in the compression subsystem is drawn in by the first pump in the compression subsystem and delivered to the heat exchangers of each compression stage in the compression subsystem to absorb the heat of compression, and then delivered to the heat storage tank in the expansion power generation system for storage; During the energy release phase, the natural gas concentration measuring instrument in the depleted oil and gas reservoir storage subsystem detects the natural gas concentration in the compressed air of the depleted oil and gas reservoir. If the natural gas concentration is lower than a preset concentration threshold, the second outlet of the first three-way valve and the air inlet of the second three-way valve in the expansion generator system are opened, and the first outlet of the first three-way valve and the flue gas inlet of the second three-way valve are closed. This allows the compressed air to pass sequentially through the pre-stage heat exchanger and turbine of each expansion stage in the expansion generator system. In the pre-stage heat exchanger, the compressed air absorbs the gas drawn in by the second pump in the expansion generator system. The heat energy of the hot water in the hot tank flows through each expansion stage to drive the turbine to expand and do work. If the natural gas concentration is higher than a preset concentration threshold, the first outlet of the second three-way valve and the flue gas inlet of the second three-way valve are opened, and the second outlet of the first three-way valve and the air inlet of the second three-way valve are closed. This allows the compressed air to mix and burn with the fuel in the combustion chamber of the expansion generator system before entering the subsequent expansion stages. The compressed air in the pre-stage heat exchanger absorbs the heat energy from the hot water in the heat storage tank and flows through each expansion stage to drive the turbine to expand and do work. The cold water that has undergone heat exchange in the pre-stage heat exchanger is sent to the cold storage tank for storage.

10. The compressed air energy storage method according to claim 9, characterized in that, The method specifically includes: During the energy storage phase, off-peak electricity from the power grid drives the compression subsystem. Air is compressed by the first-stage compressor in the compression subsystem and then sent to the first-stage post-compression heat exchanger for cooling. Then, it is compressed by the second-stage compressor and sent to the second-stage post-compression heat exchanger for further cooling. Finally, it is compressed by the last-stage compressor and sent to the last-stage post-compression heat exchanger for cooling. The cooled compressed air is then sent to a depleted oil and gas reservoir for storage. Cold water stored in the cold storage tank included in the compression subsystem is drawn in by the first pump included in the compression subsystem and transported to the first-stage, second-stage, and last-stage post-compression heat exchangers to absorb the heat of compression, and then input into the heat storage tank for storage. During the energy release phase, the natural gas concentration measuring instrument detects the natural gas concentration of the compressed air in the depleted oil and gas reservoir. If the natural gas concentration is lower than a preset concentration threshold, the second outlet of the first three-way valve and the air inlet of the second three-way valve are opened, and the first outlet of the first three-way valve and the flue gas inlet of the second three-way valve are closed. The compressed air passes through the throttle valve in the gas storage subsystem of the depleted oil and gas reservoir and then sequentially through the first-stage preheater, first-stage turbine, first three-way valve, second-stage preheater, second three-way valve, second-stage turbine, last-stage preheater, and last-stage turbine in the expansion generator system. The first-stage preheater, second-stage preheater, and last-stage preheater absorb heat energy from the heat storage tank and heat the compressed air. The final stage turbine performs work through the expansion of compressed air. If the natural gas concentration is higher than a preset concentration threshold, the first outlet and flue gas inlet of the second three-way valve are opened, and the second outlet and air inlet of the first three-way valve are closed. The compressed air enters the combustion chamber after passing through the first-stage pre-stage heat exchanger, the first-stage turbine, and the first three-way valve. After mixing and burning with fuel, the compressed air enters the second-stage turbine through the second three-way valve and is discharged after passing through the final-stage pre-stage heat exchanger and the final-stage turbine in sequence. The compressed air in the first-stage and final-stage pre-stage heat exchangers absorbs heat energy from the hot water in the heat storage tank, and the combustion in the combustion chamber heats the compressed air. The first-stage turbine, the second-stage turbine, and the final-stage turbine perform work through the expansion of compressed air. The first-stage preheater, the second-stage preheater, and the last-stage preheater absorb heat energy from the hot water in the heat storage tank and send the cooled water after heat exchange to the cold storage tank for storage.

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