A low-carbon hydrogen storage method, device and system

Abstract

The present invention relates to the field of oil and gas engineering technology, and in particular to a low-carbon hydrogen storage method, device and system. The method comprises: moving a rock formation sealing piston to seal the side walls of rock formations other than a target rock formation that requires hydrogen injection in an oil and gas reservoir; moving the sealing piston in a well to the bottom surface of the target rock formation to isolate the wellbore below the target rock formation in the well; then injecting hydrogen into the target rock formation, and lowering a variable weight piston arranged at the wellhead to press the hydrogen in the wellbore into the target rock formation for storage; at the same time, the potential energy generated when the variable weight piston descends will also be converted into electrical energy for storage to provide power for the next operation of the variable weight piston, thereby achieving energy conservation and emission reduction while utilizing the oil and gas reservoir to store hydrogen.

Description

Technical Field

[0001] The present invention relates to the field of oil and gas engineering technology, and in particular to a low-carbon hydrogen storage method, device and system. Background Art

[0002] While fossil fuels provide energy and power for social development, the carbon emissions they generate put increasing pressure on the environment. Therefore, all countries are currently vigorously developing clean energy and related technologies to achieve the goal of emission reduction.

[0003] Hydrogen, a combustible gas, generates heat through combustion or electricity through combination with oxygen, becoming an energy gas. This process does not emit carbon, making it a clean energy gas. Currently, the hydrogen economy—economic activities that use hydrogen as a primary energy source—is being vigorously developed globally. Specifically, hydrogen is used as a power source in transportation, energy, and other fields.

[0004] In recent years, major economies around the world have developed hydrogen energy strategies for their national economies and proposed ambitious hydrogen production capacity plans. However, as the development of the hydrogen economy is still in its infancy, various infrastructures still need to be further developed. Consequently, the rapid increase in hydrogen production capacity will outstrip hydrogen consumption, necessitating the storage of excess hydrogen.

[0005] Hydrogen is a reactive gas. Long-term contact with steel can cause hydrogen embrittlement, reducing storage safety. Furthermore, the large amounts of hydrogen generated by excessive hydrogen production capacity require storage methods that are both long-term safe and economically viable.

[0006] Oil and gas reservoirs, known for their ability to store gas and their vast reserves of crude oil and natural gas over a long geological history, require detailed geological surveys and the construction of comprehensive water and gas injection facilities to support the exploration and extraction phases. Furthermore, these reservoirs are equipped with sophisticated pipeline networks to facilitate the transportation of oil and gas. In the later stages of extraction, these established supporting facilities are well-preserved, eliminating the need for additional construction. Therefore, depleted oil and gas reservoirs, particularly depleted natural gas reservoirs, are ideal locations for the long-term, economical storage of hydrogen.

[0007] However, because the physical and chemical properties of hydrogen at the surface differ significantly from those of underground gases such as methane and carbon dioxide, surface hydrogen must be injected into the ground using artificial pressure boosting, a process that consumes energy. This contradicts the principle of hydrogen as a clean energy source, which aims to reduce energy consumption and emissions. Therefore, a technology is needed that can utilize depleted natural gas reservoirs to store large volumes of hydrogen while also reducing energy consumption during storage compared to traditional gas injection methods. Summary of the Invention

[0008] The object of the present invention is to provide a low-carbon hydrogen storage method for storing hydrogen in abandoned oil and gas reservoirs in a manner that saves energy and reduces emissions.

[0009] Another object of the present invention is to provide a low-carbon hydrogen storage device for storing hydrogen in abandoned oil and gas reservoirs in a manner that saves energy and reduces emissions.

[0010] Another object of the present invention is to provide a low-carbon hydrogen storage system for storing hydrogen in abandoned oil and gas reservoirs in a manner that saves energy and reduces emissions.

[0011] In order to achieve the above objectives, the technical solutions adopted in the embodiments of the present invention are as follows:

[0012] In a first aspect, an embodiment of the present invention provides a low-carbon hydrogen storage method, which includes: moving a rock formation sealing piston to seal the side walls of other rock formations in the oil and gas reservoir except for the target rock formation that requires hydrogen injection; moving the sealing piston in the well to the bottom position of the target rock formation to isolate the wellbore below the target rock formation in the well; injecting hydrogen to connect with the target rock formation; lowering a variable weight piston arranged at the wellhead to press the hydrogen in the wellbore into the target rock formation; at the same time, converting the potential energy generated when the variable weight piston descends into electrical energy for storage to provide power for the movement of the variable weight piston.

[0013] In the second aspect, an embodiment of the present invention also provides a low-carbon hydrogen storage device, which includes: a first moving module, used to move the rock formation sealing piston to seal the side walls of other rock formations in the oil and gas reservoir except for the target rock formation that needs hydrogen injection; a second moving module, used to move the sealing piston in the well to the bottom position of the target rock formation, and isolate the wellbore below the target rock formation in the well; an injection module, used to inject hydrogen to connect with the target rock formation; an operating module, used to lower the variable weight piston arranged at the wellhead, and press the hydrogen in the wellbore into the target rock formation; at the same time, the potential energy generated when the variable weight piston descends is converted into electrical energy for storage to provide power for the movement of the variable weight piston.

[0014] In a third aspect, an embodiment of the present invention further provides a low-carbon hydrogen storage system, which includes a plurality of hydrogen storage rock formations, a wellbore, a variable weight piston, a hydrogen injection channel, an energy storage mechanism, and a power mechanism; the wellbore is connected to the plurality of hydrogen storage rock formations in the oil and gas reservoir; the variable weight piston is arranged at the wellhead of the wellbore, and is respectively connected to the energy storage mechanism and the power mechanism; the energy storage mechanism is used to convert the potential energy generated by the falling of the variable weight piston into electrical energy for storage, and provide power for the power mechanism, and the power mechanism is used to drive the variable weight piston to rise; the hydrogen injection channel is used to input hydrogen into the wellbore, and the hydrogen is pressed into the corresponding hydrogen storage rock formation through the variable weight piston.

[0015] An embodiment of the present invention provides a low-carbon hydrogen storage method, device and system, which includes: moving a rock formation sealing piston to seal the side walls of other rock formations in the oil and gas reservoir except for the target rock formation that needs to be injected with hydrogen; moving the sealing piston in the well to the bottom position of the target rock formation to isolate the wellbore below the target rock formation in the well; then injecting hydrogen into the target rock formation, and lowering a variable weight piston arranged at the wellhead to press the hydrogen in the wellbore into the target rock formation for storage; at the same time, the potential energy generated when the variable weight piston descends will also be converted into electrical energy for storage to provide power for the next operation of the variable weight piston, so as to achieve energy conservation and emission reduction while storing hydrogen in the oil and gas reservoir.

[0016] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A schematic structural diagram of a low-carbon hydrogen storage system provided by an embodiment of the present invention is shown.

[0019] Figure 2 A schematic flow chart of a low-carbon hydrogen storage method provided in an embodiment of the present invention is shown.

[0020] Figure 3 A schematic flow chart of another low-carbon hydrogen storage method provided in an embodiment of the present invention is shown.

[0021] Figure 4 A schematic flow chart of another low-carbon hydrogen storage method provided in an embodiment of the present invention is shown.

[0022] Figure 5 A functional module diagram of a low-carbon hydrogen storage device used in an embodiment of the present invention is shown.

[0023] Diagram:

[0024] 100-low-carbon hydrogen storage system; 101-wellbore; 102-energy storage mechanism; 103-rotor; 104-lifting cable; 105-variable weight piston; 106-power mechanism; 107-hydrogen injection channel; 108-hydrogen storage rock formation; 109-well sealing piston; 110-rock formation sealing piston; 200-low-carbon hydrogen storage device; 210-first mobile module; 220-second mobile module; 230-injection module; 240-operation module. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0026] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. At the same time, in the description of the present invention, the terms "first", "second", etc. are used only to distinguish the description and should not be understood as indicating or implying relative importance.

[0027] Example 1

[0028] See Figure 1 , is a structural schematic diagram of a low-carbon hydrogen storage system 100 provided in an embodiment of the present invention, wherein the low-carbon hydrogen storage system 100 includes a plurality of hydrogen storage rock layers 108 and a wellbore 101. The wellbore 101 is a well drilled in a crude oil and gas reservoir, including exploration wells, development wells, etc., which are drilled to a certain depth and contain different strata or vertical or artificial holes with a certain inclination within the same stratum. The hydrogen storage rock layer 108 is the specific rock layer where the wellbore 101 is located, mainly a rock layer with a certain porosity and long-term stability. The hydrogen storage rock layer 108 is composed of multiple layers of natural rock layers R1, R2, ..., Rn. In order to ensure the stability of the wellbore 101, a high-strength artificial well wall can be laid in the wellbore for a certain rock layer Rn or all rock layers to provide protection for the wellbore 101.

[0029] At the entrance of the wellbore 101, there are also provided an energy storage mechanism 102, a rotor 103, a lifting cable 104, a variable weight piston 105, and a power mechanism 106. Specifically, the energy storage mechanism 102 is a potential energy-electrical energy conversion and storage machine, which can convert the potential energy generated by the descent of the variable weight piston 105 into electrical energy and store the converted electrical energy. Furthermore, the energy storage mechanism 102 is connected to the rotor 103, one end of the rotor 103 is connected to the lifting cable 104, and the bottom end of the lifting cable 104 is connected to the variable weight piston 105. When the variable weight piston 105 needs to descend along the wellbore 101, the lifting cable 104 can drive the rotor 103 to rotate, thereby transmitting the potential energy to the energy storage mechanism 102, so that the energy storage mechanism 102 can convert the potential energy into electrical energy for storage.

[0030] Furthermore, the power mechanism 106 is an electric energy-to-potential energy converter connected to the energy storage mechanism 102. When electricity is needed, the energy storage mechanism 102 can input the stored electric energy into the power mechanism 106, allowing the power mechanism 106 to drive the variable weight piston 105 upward without an additional power source, thus saving energy. It will be readily understood that the power mechanism 106 can also be connected to a separate external power source to supplement the required additional energy.

[0031] A hydrogen injection channel 107 is also provided on one side of the wellbore 101. When hydrogen needs to be injected into the hydrogen storage rock layer 108, hydrogen is injected through the hydrogen injection channel 107. The specific implementation process includes the hydrogen injection process and the hydrogen production process, which are as follows:

[0032] Hydrogen injection process:

[0033] First, the rock formation sealing piston is moved to seal the side walls of the rock formations other than the target rock formation that needs to be injected with hydrogen.

[0034] Specifically, the rock formation sealing piston 110 is used to seal the rock formation sidewalls, preventing hydrogen from flowing into non-target rock formations during hydrogen injection. The rock formations in an oil and gas reservoir primarily possess a certain porosity and are stable over the long term, which can be used to store hydrogen. Furthermore, when hydrogen injection is required, the target rock formation to be injected must be identified, and the rock formation sealing piston is moved to seal the sidewalls of all rock formations in the reservoir except the target rock formation.

[0035] Secondly, the sealing piston in the well is moved to the bottom surface position of the target rock formation to isolate the wellbore below the target rock formation in the well.

[0036] Specifically, the rock formation sealing piston 110 is mainly used to seal the side walls of other rock formations. However, the wellbore 101 has a certain depth, and the target rock formation to be injected with hydrogen is overlapped with other multiple rock formations. Therefore, the wellbore sealing piston 109 needs to be moved to the bottom position of the target rock formation to isolate the wellbore below the target rock formation in the well to prevent hydrogen from reaching unnecessary places, so that hydrogen can be injected into the target rock formation faster.

[0037] Then, hydrogen is injected to communicate with the target rock formation.

[0038] Finally, the variable weight piston at the wellhead is lowered to pressurize the hydrogen in the wellbore into the target rock formation; at the same time, the potential energy generated when the variable weight piston descends is converted into electrical energy for storage to provide power for the movement of the variable weight piston.

[0039] Specifically, the variable weight piston 105 is released and moves downward, thereby pressing the hydrogen in the wellbore 101 into the target rock formation. Simultaneously, the energy storage mechanism 102 converts the potential energy generated by the variable weight piston 105 during its descent into electrical energy for storage. The next time the power mechanism 106 needs to use power to raise the variable weight piston, it can directly consume the stored electrical energy, thus reducing energy loss.

[0040] When a single hydrogen injection is completed, the power mechanism 106 will lift the variable weight piston 105 to stay above the edge of the hydrogen injection channel 107 close to the wellhead and keep it stationary in preparation for the next hydrogen injection.

[0041] It should be further explained that in order for the variable weight piston 105 to pressurize hydrogen into the target rock formation, it needs a certain weight to overcome the pressure in the rock formation. Therefore, the weight of the variable weight piston 105 must be adjusted before hydrogen injection begins. The adjustment method is as follows:

[0042] The inner diameter of the rock formation sealing piston 110 is determined by subtracting the wall thickness of the rock formation sealing piston 110 at the minimum diameter of the wellbore 101 from the wall thickness of the rock formation sealing piston 110, and this diameter is used as the diameter of the variable weight piston 105. Generally, the cross-sectional area of ​​the variable weight piston 105 is circular, so the cross-sectional area S of the variable weight piston 105 can be determined based on the determined diameter of the variable weight piston 105. Production data from depleted oil and gas reservoirs used for hydrogen storage can be used to determine the formation pressure Pn of each natural rock layer Rn in the underground hydrogen storage rock layer 108 in the wellbore 101 used for hydrogen storage in this oil and gas reservoir. The pressure calculation formula P = mg / S is then used to calculate the minimum mass mg of the variable weight piston 105 required to successfully compress hydrogen into the natural rock layer Rn. Therefore, the weight of the variable weight piston 105 can be adjusted to be greater than the minimum weight so that the variable weight piston 105 can overcome the pressure and compress the hydrogen in the wellbore 101 into the target rock layer.

[0043] Hydrogen production process:

[0044] First, the maximum weight of the variable weight piston is determined according to the pressure of the target rock formation and the cross-sectional area of ​​the variable weight piston.

[0045] Specifically, the natural rock formation Rn from which hydrogen is to be extracted from the underground hydrogen storage rock formation 108 is determined. The pressure Pn of this formation is determined based on the various parameters collected during the aforementioned hydrogen injection step. The maximum weight of the variable weight piston 105 is then calculated based on the pressure of the target rock formation and the cross-sectional area of ​​the variable weight piston 105.

[0046] Secondly, the weight of the variable weight piston is adjusted to be less than the maximum weight.

[0047] In order to ensure that the variable weight piston 105 does not suppress the hydrogen and prevent the hydrogen from being released, the weight of the variable weight piston 105 is adjusted to be less than the maximum weight so that the hydrogen can be released gradually.

[0048] Finally, the variable weight piston is lowered to above the target rock formation so that the hydrogen can push the variable weight piston upward and be gradually discharged.

[0049] Even if, before the release of hydrogen begins, the variable weight piston 105 is lowered to the upper edge of the target rock formation, the potential energy generated by the descent of the variable weight piston 105 during this process can be converted into electrical energy by the energy storage mechanism 102 and stored, and then provide power for the power mechanism 106. At this time, the well sealing piston 109 is adjusted to below the target rock formation, and the rock formation sealing piston 110 set on the side wall of the target rock formation is removed to gradually release the hydrogen in the target rock formation, and push the variable weight piston 105 toward the wellhead to gradually and slowly release the hydrogen, that is, to complete a single hydrogen extraction process. Furthermore, during the hydrogen release process, the well sealing piston 109 can be moved to the upper edge of the target rock formation to avoid continuous release of hydrogen, resulting in hydrogen waste or safety hazards.

[0050] Example 2

[0051] Please refer to Figure 2 , is a schematic flow chart of a low-carbon hydrogen storage method provided by an embodiment of the present invention, the low-carbon hydrogen storage method comprising:

[0052] S110, moving the rock formation sealing piston to seal the side walls of the rock formations other than the target rock formation requiring hydrogen injection in the oil and gas reservoir.

[0053] Specifically, the rock formation sealing piston 110 is used to seal the rock formation sidewalls, preventing hydrogen from flowing into non-target rock formations during hydrogen injection. The rock formations in an oil and gas reservoir primarily possess a certain porosity and are stable over the long term, which can be used to store hydrogen. Furthermore, when hydrogen injection is required, the target rock formation to be injected must be identified, and the rock formation sealing piston is moved to seal the sidewalls of all rock formations in the reservoir except the target rock formation.

[0054] S120, moving the sealing piston in the well to the bottom surface of the target rock formation to isolate the wellbore below the target rock formation in the well.

[0055] Specifically, the rock formation sealing piston 110 is mainly used to seal the side walls of other rock formations. However, the wellbore 101 has a certain depth, and the target rock formation to be injected with hydrogen is overlapped with other multiple rock formations. Therefore, the wellbore sealing piston 109 needs to be moved to the bottom position of the target rock formation to isolate the wellbore below the target rock formation in the well to prevent hydrogen from reaching unnecessary places, so that hydrogen can be injected into the target rock formation faster.

[0056] S130, injecting hydrogen to communicate with the target rock formation.

[0057] Specifically, after the basic work preparations are completed, hydrogen can be injected into the wellbore 101 through the hydrogen injection channel 107 .

[0058] S140, lowering the variable weight piston set at the wellhead to press the hydrogen in the wellbore into the target rock formation; at the same time, the potential energy generated when the variable weight piston descends is converted into electrical energy for storage to provide power for the movement of the variable weight piston.

[0059] Specifically, since the density of hydrogen is less than that of air, hydrogen will not reach the target rock formation on its own and requires the intervention of external forces. Furthermore, an energy storage mechanism 102, a rotor 103, a lifting cable 104, a variable weight piston 105, and a power mechanism 106 are also provided at the wellhead of the wellbore 101. Specifically, the energy storage mechanism 102 is a potential energy-electric energy conversion and storage machine, which can convert the potential energy generated by the descent of the variable weight piston 105 into electrical energy and store the converted electrical energy. Furthermore, the energy storage mechanism 102 is connected to the rotor 103, one end of the rotor 103 is connected to the lifting cable 104, and the bottom end of the lifting cable 104 is connected to the variable weight piston 105. Then, when the variable weight piston 105 needs to descend along the wellbore 101, the lifting cable 104 can drive the rotor 103 to rotate, thereby transmitting the potential energy to the energy storage mechanism 102, so that the energy storage mechanism 102 can convert the potential energy into electrical energy for storage.

[0060] Furthermore, the power mechanism 106 is an electric energy-to-potential energy converter connected to the energy storage mechanism 102. When electricity is needed, the energy storage mechanism 102 can input the stored electric energy into the power mechanism 106, allowing the power mechanism 106 to drive the variable weight piston 105 upward without an additional power source, thus saving energy. It will be readily understood that the power mechanism 106 can also be connected to a separate external power source to supplement the required additional energy.

[0061] When hydrogen is injected into the hydrogen injection channel 107, the power mechanism 106 is first started to control the lifting rope 104 to lift the variable weight piston 105 to the wellhead position until the lower edge of the variable weight piston 105 is higher than the upper edge of the hydrogen injection channel 107 and is fixed. At this time, the power of the power mechanism 106 is supplied by the energy storage mechanism 102, reducing energy consumption.

[0062] Then, hydrogen is injected into the wellbore 101 through the hydrogen injection channel 107. Since other rock formations are sealed, the hydrogen will flow into the target rock formation.

[0063] Furthermore, when the injected hydrogen reaches the single injection volume, the variable weight piston 105 is released and moves downward to pressurize the hydrogen in the wellbore 101 into the target rock formation. Simultaneously, the energy storage mechanism 102 converts the potential energy generated by the variable weight piston 105 during its descent into electrical energy for storage. The next time the power mechanism 106 needs to use power to raise the variable weight piston, it can directly consume the stored electrical energy, reducing energy loss.

[0064] When a single hydrogen injection is completed, the power mechanism 106 will lift the variable weight piston 105 to stay above the edge of the hydrogen injection channel 107 close to the wellhead and keep it stationary in preparation for the next hydrogen injection.

[0065] It should be noted that the total volume of hydrogen that can be stored in the target rock formation can be calculated based on parameters such as the natural rock formation thickness, area, and porosity. Furthermore, the single hydrogen injection volume can be determined based on the diameter of the variable weight piston 105 and the burial depth of the target rock formation capable of storing hydrogen. Furthermore, the number of hydrogen injections can be calculated based on the total amount of hydrogen that can be injected into the rock formation and the single hydrogen injection volume, thereby achieving multiple batch hydrogen injections.

[0066] Example 3

[0067] In order for the variable weight piston 105 to pressurize hydrogen into the target rock formation, it needs a certain weight to overcome the pressure in the rock formation. Therefore, a method is required to determine the weight of the variable weight piston.

[0068] Please refer to Figure 3 , is a schematic flow chart of another low-carbon hydrogen storage method provided by an embodiment of the present invention, the method comprising:

[0069] S210: Subtract the thickness of the corresponding rock formation sealing piston from the minimum diameter in the wellbore to obtain the diameter of the variable weight piston.

[0070] Specifically, during early oil and gas production, wellbore 101 is casingd. The integrity of the existing casing needs to be investigated, and casing is installed in the natural rock formations Rn where additional casing is required. When the diameter of wellbore 101 varies, the shape of the rock formation sealing piston 110 is modified to maintain a consistent vertical centerline.

[0071] The inner diameter of the rock formation sealing piston 110 is determined by subtracting the wall thickness of the rock formation sealing piston 110 from the minimum diameter of the wellbore 101 , and this inner diameter is used as the diameter of the variable weight piston 105 .

[0072] S220: Determine the cross-sectional area of ​​the variable weight piston according to the determined diameter of the variable weight piston.

[0073] Specifically, generally, the cross-sectional area of ​​the variable weight piston 105 is circular, so the cross-sectional area S of the variable weight piston 105 can be determined according to the determined diameter of the variable weight piston 105 .

[0074] S230: Determine the minimum weight of the variable weight piston according to the pressure of the target rock formation and the cross-sectional area of ​​the variable weight piston.

[0075] The production data of the depleted oil and gas reservoir used for hydrogen storage can be used to determine the formation pressure Pn of each natural rock layer Rn in the underground hydrogen storage rock layer 108 in the wellbore 101 used for hydrogen storage in this oil and gas reservoir.

[0076] Then, using the pressure calculation formula P=mg / S, the minimum mass mg of the variable weight piston 105 required to successfully press hydrogen into the natural rock formation Rn is calculated.

[0077] S240: Select a variable weight piston whose weight value is greater than the minimum weight as a target variable weight piston.

[0078] Therefore, the weight of the variable weight piston 105 can be adjusted to be greater than the minimum weight, so that the variable weight piston 105 can overcome the pressure and press the hydrogen in the wellbore 101 into the target rock formation.

[0079] Example 4

[0080] After hydrogen is injected into various rock formations, it is necessary to release the hydrogen when it is needed. Please refer to Figure 4 , is a schematic flow chart of another low-carbon hydrogen storage method provided by an embodiment of the present invention, the method comprising:

[0081] S310, adjusting the sealing piston in the well to move below the target rock formation.

[0082] The sealing piston 109 in the well is moved to below the target rock formation to prevent hydrogen from leaking out of the target rock formation and entering the wellbore 101 below the target rock formation.

[0083] S320: Remove the rock formation sealing piston corresponding to the target rock formation to release the stored hydrogen.

[0084] The rock formation sealing piston 110 provided on the side wall of the target rock formation is removed, so that the hydrogen in the target rock formation is gradually released.

[0085] S330: Determine the maximum weight of the variable weight piston according to the pressure of the target rock formation and the cross-sectional area of ​​the variable weight piston.

[0086] More preferably, the natural rock formation Rn from which hydrogen is to be extracted from the underground hydrogen reservoir 108 is determined. The pressure Pn of this formation is determined based on the various parameters collected during the aforementioned hydrogen injection step. The maximum weight of the variable weight piston 105 is then calculated based on the pressure of the target rock formation and the cross-sectional area of ​​the variable weight piston 105.

[0087] S340: Adjust the weight of the variable weight piston to be less than the maximum weight.

[0088] In order to ensure that the variable weight piston 105 does not suppress the hydrogen and prevent the hydrogen from being released, the weight of the variable weight piston 105 is adjusted to be less than the maximum weight so that the hydrogen can be released gradually.

[0089] S350, lowering the variable weight piston to above the target rock formation so that the hydrogen can push the variable weight piston upward and be discharged gradually.

[0090] Even if, before the release of hydrogen begins, the variable weight piston 105 is lowered to the upper edge of the target rock formation, the potential energy generated by the descent of the variable weight piston 105 during this process can be converted into electrical energy by the energy storage mechanism 102 and stored, and then provide power for the power mechanism 106. At this time, the well sealing piston 109 is adjusted to below the target rock formation, and the rock formation sealing piston 110 set on the side wall of the target rock formation is removed to gradually release the hydrogen in the target rock formation, and push the variable weight piston 105 toward the wellhead to gradually and slowly release the hydrogen, that is, to complete a single hydrogen extraction process. Furthermore, during the hydrogen release process, the well sealing piston 109 can be moved to the upper edge of the target rock formation to avoid continuous release of hydrogen, resulting in hydrogen waste or safety hazards.

[0091] Example 5

[0092] Please refer to Figure 5, is a functional module diagram of a low-carbon hydrogen storage device 200 provided by an embodiment of the present invention, the device includes a first moving module 210, a second moving module 220, an injection module 230 and an operation module 240. Specifically:

[0093] The first moving module 210 is used to move the rock formation sealing piston to seal the side walls of other rock formations in the oil and gas reservoir except the target rock formation that needs to be injected with hydrogen.

[0094] Specifically, the rock formation sealing piston 110 is used to seal the rock formation sidewalls, preventing hydrogen from flowing into non-target rock formations during hydrogen injection. The rock formations in an oil and gas reservoir primarily possess a certain porosity and are stable over the long term, which can be used to store hydrogen. Furthermore, when hydrogen injection is required, the target rock formation to be injected must be identified, and the rock formation sealing piston is moved to seal the sidewalls of all rock formations in the reservoir except the target rock formation.

[0095] The second moving module 220 moves the sealing piston in the well to the bottom surface of the target rock formation to isolate the wellbore below the target rock formation in the well.

[0096] Specifically, the rock formation sealing piston 110 is mainly used to seal the side walls of other rock formations. However, the wellbore 101 has a certain depth, and the target rock formation to be injected with hydrogen is overlapped with other multiple rock formations. Therefore, the wellbore sealing piston 109 needs to be moved to the bottom position of the target rock formation to isolate the wellbore below the target rock formation in the well to prevent hydrogen from reaching unnecessary places, so that hydrogen can be injected into the target rock formation faster.

[0097] The injection module 230 injects hydrogen to communicate with the target rock formation.

[0098] Specifically, after the basic work preparations are completed, hydrogen can be injected into the wellbore 101 through the hydrogen injection channel 107 .

[0099] The operating module 240 lowers the variable weight piston provided at the wellhead to pressurize the hydrogen in the wellbore into the target rock formation; at the same time, the potential energy generated when the variable weight piston descends is converted into electrical energy for storage to provide power for the movement of the variable weight piston.

[0100] Specifically, since the density of hydrogen is less than that of air, hydrogen will not reach the target rock formation on its own and requires the intervention of external forces. Furthermore, an energy storage mechanism 102, a rotor 103, a lifting cable 104, a variable weight piston 105, and a power mechanism 106 are also provided at the wellhead of the wellbore 101. Specifically, the energy storage mechanism 102 is a potential energy-electric energy conversion and storage machine, which can convert the potential energy generated by the descent of the variable weight piston 105 into electrical energy and store the converted electrical energy. Furthermore, the energy storage mechanism 102 is connected to the rotor 103, one end of the rotor 103 is connected to the lifting cable 104, and the bottom end of the lifting cable 104 is connected to the variable weight piston 105. Then, when the variable weight piston 105 needs to descend along the wellbore 101, the lifting cable 104 can drive the rotor 103 to rotate, thereby transmitting the potential energy to the energy storage mechanism 102, so that the energy storage mechanism 102 can convert the potential energy into electrical energy for storage.

[0101] Furthermore, the power mechanism 106 is an electric energy-to-potential energy converter connected to the energy storage mechanism 102. When electricity is needed, the energy storage mechanism 102 can input the stored electric energy into the power mechanism 106, allowing the power mechanism 106 to drive the variable weight piston 105 upward without an additional power source, thus saving energy. It will be readily understood that the power mechanism 106 can also be connected to a separate external power source to supplement the required additional energy.

[0102] When hydrogen is injected into the hydrogen injection channel 107, the power mechanism 106 is first started to control the lifting rope 104 to lift the variable weight piston 105 to the wellhead position until the lower edge of the variable weight piston 105 is higher than the upper edge of the hydrogen injection channel 107 and is fixed. At this time, the power of the power mechanism 106 is supplied by the energy storage mechanism 102, reducing energy consumption.

[0103] Then, hydrogen is injected into the wellbore 101 through the hydrogen injection channel 107. Since other rock formations are sealed, the hydrogen will flow into the target rock formation.

[0104] Furthermore, when the injected hydrogen reaches the single injection volume, the variable weight piston 105 is released and moves downward to pressurize the hydrogen in the wellbore 101 into the target rock formation. Simultaneously, the energy storage mechanism 102 converts the potential energy generated by the variable weight piston 105 during its descent into electrical energy for storage. The next time the power mechanism 106 needs to use power to raise the variable weight piston, it can directly consume the stored electrical energy, reducing energy loss.

[0105] When a single hydrogen injection is completed, the power mechanism 106 will lift the variable weight piston 105 to stay above the edge of the hydrogen injection channel 107 close to the wellhead and keep it stationary in preparation for the next hydrogen injection.

[0106] It should be noted that the total volume of hydrogen that can be stored in the target rock formation can be calculated based on parameters such as the natural rock formation thickness, area, and porosity. Furthermore, the single hydrogen injection volume can be determined based on the diameter of the variable weight piston 105 and the burial depth of the target rock formation capable of storing hydrogen. Furthermore, the number of hydrogen injections can be calculated based on the total amount of hydrogen that can be injected into the rock formation and the single hydrogen injection volume, thereby achieving multiple batch hydrogen injections.

[0107] Furthermore, in order for the variable weight piston 105 to pressurize hydrogen into the target rock formation, it needs a certain weight to overcome the pressure in the rock formation. Therefore, when the hydrogen injection starts, the weight of the variable weight piston 105 needs to be adjusted. This specifically includes:

[0108] The inner diameter of the rock formation sealing piston 110 is determined by subtracting the wall thickness of the rock formation sealing piston 110 at the minimum diameter of the wellbore 101 from the wall thickness of the rock formation sealing piston 110, and this diameter is used as the diameter of the variable weight piston 105. Generally, the cross-sectional area of ​​the variable weight piston 105 is circular, so the cross-sectional area S of the variable weight piston 105 can be determined based on the determined diameter of the variable weight piston 105. Production data from depleted oil and gas reservoirs used for hydrogen storage can be used to determine the formation pressure Pn of each natural rock layer Rn in the underground hydrogen storage rock layer 108 in the wellbore 101 used for hydrogen storage in this oil and gas reservoir. The pressure calculation formula P = mg / S is then used to calculate the minimum mass mg of the variable weight piston 105 required to successfully compress hydrogen into the natural rock layer Rn. Therefore, the weight of the variable weight piston 105 can be adjusted to be greater than the minimum weight so that the variable weight piston 105 can overcome the pressure and compress the hydrogen in the wellbore 101 into the target rock layer.

[0109] Therefore, the low-carbon hydrogen storage method proposed in the present invention makes full use of the infrastructure of existing depleted oil and gas reservoirs, reduces the construction investment required for hydrogen storage, and has reasonable economic efficiency. During the hydrogen storage process, the actual well diameter is reduced by using a rock formation sealing piston, which can quickly increase the pressure of the running piston, thereby reducing the energy required to compress the hydrogen. At the same time, in the process of using the running piston to press hydrogen into the formation, the potential energy of the piston is allowed to be converted into electrical energy, reducing the energy consumption required for the hydrogen storage process. On the other hand, in the hydrogen production process, the pressure of the hydrogen injected in the early stage is used to push the running piston to move in the well, thereby obtaining electrical energy. On the one hand, this technology can tap the surplus value of depleted oil and gas reservoirs. On the other hand, it realizes the conversion of potential energy into electrical energy in both the hydrogen injection and production processes. It can not only reduce the energy consumption in the hydrogen injection and production process, but also provide electricity to society with the electricity obtained in the hydrogen injection and production process, thereby partially offsetting the carbon emissions of oil companies and helping oil companies achieve carbon neutrality.

[0110] In summary, an embodiment of the present invention provides a low-carbon hydrogen storage method, device and system, which includes: moving the rock formation sealing piston to seal the side walls of other rock formations in the oil and gas reservoir except for the target rock formation that needs to be injected with hydrogen; moving the sealing piston in the well to the bottom position of the target rock formation to isolate the wellbore below the target rock formation in the well; then injecting hydrogen into the target rock formation, and lowering the variable weight piston arranged at the wellhead to press the hydrogen in the wellbore into the target rock formation for storage; at the same time, the potential energy generated when the variable weight piston descends will also be converted into electrical energy for storage to provide power for the next operation of the variable weight piston, so as to achieve energy conservation and emission reduction while storing hydrogen in the oil and gas reservoir.

[0111] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a portion of code, and the module, program segment or a portion of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or can be implemented using a combination of dedicated hardware and computer instructions.

[0112] In addition, the functional modules in the various embodiments of the present invention may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0113] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. It should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, the elements defined by the phrase "comprising a..." do not exclude the presence of other identical elements in the process, method, article or device comprising the elements.

[0114] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Various modifications and variations are readily apparent to those skilled in the art. Any modifications, equivalent substitutions, improvements, and the like made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention. It should be noted that similar reference numerals and letters denote similar items in the following figures. Therefore, once an item is defined in one figure, it need not be further defined or explained in subsequent figures.

[0115] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A low-carbon hydrogen storage method, characterized in that: The method comprises: Move the rock formation sealing piston to seal the sidewalls of other rock formations in the oil and gas reservoir except the target rock formation where hydrogen injection is required; Moving the sealing piston in the well to the bottom surface of the target rock formation to isolate the wellbore below the target rock formation in the well; injecting hydrogen to communicate with the target rock formation; Lowering a variable weight piston disposed at the wellhead to compress the hydrogen in the wellbore into the target rock formation; simultaneously, converting the potential energy generated by the descending variable weight piston into electrical energy for storage to provide power for the movement of the variable weight piston; Determining the minimum weight of the variable weight piston based on the pressure of the target rock formation and the cross-sectional area of ​​the variable weight piston; selecting a variable weight piston with a weight greater than the minimum weight as a target variable weight piston; The total volume of hydrogen that can be stored in the target rock formation is determined based on the various parameters of the target rock formation; the single hydrogen injection volume is determined based on the diameter of the variable weight piston and the distance between the variable weight piston and the target rock formation at the wellhead; and the number of hydrogen injections is determined based on the total hydrogen volume and the single hydrogen injection volume.

2. The method according to claim 1, wherein The method for determining the cross-sectional area of ​​the variable weight piston includes: The minimum diameter in the wellbore minus the thickness of the corresponding rock formation sealing piston is used as the diameter of the variable weight piston; The cross-sectional area of ​​the variable weight piston is determined according to the determined diameter of the variable weight piston.

3. The method according to claim 1, wherein The method further comprises: Adjusting the sealing piston in the well to move below the target rock formation; The rock formation sealing piston corresponding to the target rock formation is removed to release the stored hydrogen.

4. The method according to claim 3, wherein The method further comprises: The variable weight piston is lowered to above the target rock formation so that the hydrogen can push the variable weight piston upward and be discharged gradually.

5. The method according to claim 4, wherein The method further comprises: determining a maximum weight of the variable weight piston based on the pressure of the target rock formation and the cross-sectional area of ​​the variable weight piston; The weight of the variable weight piston is adjusted to be less than the maximum weight.

6. A low-carbon hydrogen storage device using the low-carbon hydrogen storage method according to any one of claims 1 to 5, characterized in that: The device comprises: The first moving module is used to move the rock formation sealing piston to seal the side walls of other rock formations in the oil and gas reservoir except the target rock formation that needs hydrogen injection; A second moving module is used to move the sealing piston in the well to the bottom surface of the target rock formation to isolate the wellbore below the target rock formation in the well; an injection module, used for injecting hydrogen to communicate with the target rock formation; The operating module is used to lower the variable weight piston set at the wellhead to compress the hydrogen in the wellbore into the target rock formation; at the same time, the potential energy generated when the variable weight piston descends is converted into electrical energy for storage to provide power for the movement of the variable weight piston.

7. A low-carbon hydrogen storage system using the low-carbon hydrogen storage method according to any one of claims 1 to 5, characterized in that: The system includes a plurality of hydrogen storage rock formations, a wellbore, a variable weight piston, a hydrogen injection channel, an energy storage mechanism, and a power mechanism; The wellbore is connected to the multiple hydrogen storage rock layers in the oil and gas reservoir; The variable weight piston is arranged at the wellhead of the wellbore and is respectively connected to the energy storage mechanism and the power mechanism; The energy storage mechanism is used to convert the potential energy generated by the falling of the variable weight piston into electrical energy for storage, and provide power for the power mechanism, which is used to drive the variable weight piston to rise; The hydrogen injection channel is used to input hydrogen into the wellbore, and the hydrogen is pressed into the corresponding hydrogen storage rock layer through the variable weight piston.

8. The system according to claim 7, wherein: The system also includes a formation sealing piston and a well sealing piston, The rock formation sealing piston is used to seal the side wall of the hydrogen storage rock formation that does not require hydrogen injection; The well sealing piston is arranged below the current hydrogen injection rock formation.

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