Method and system for storing and releasing energy in fractures at different positions of stratum

Abstract

The invention relates to the technical field of energy storage, in particular to a method and system for storing and releasing energy in fractures at different positions of a stratum, and the method comprises an integrated energy storing and releasing method or a split energy storing and releasing method which can operate independently. The integrated energy storage and release method comprises the steps that at least two formation fractures at different depth positions are selected as target energy storage fractures, and the target energy storage fractures are connected through a shaft; high-pressure fluid is injected into the shaft, so that the high-pressure fluid can enter all target energy storage cracks connected with the shaft; blocking a shaft opening, and keeping elastic deformation of stratum rocks so as to store energy; and during energy release, the shaft plugging pressure is reduced, so that the target energy storage crack is closed, and the high-pressure fluid reversely discharged in the closing process is utilized for power generation. The method is suitable for energy storage and release of formation fractures at multiple different depth positions.

Description

[0001] Divisional application This application is a divisional application of the Chinese invention patent application [Application Number: 202411342565.8] [Name: A method and system for storing and releasing energy at different positions in the formation] filed on September 25, 2024. Technical Field

[0002] The present invention belongs to the field of underground energy storage, and in particular relates to a method and system for storing and releasing energy in cracks at different positions in a stratum. Background Art

[0003] Many renewable energy sources such as solar energy and wind energy have daily and seasonal intermittent characteristics, unstable power output, and are not suitable for providing basic load power. Therefore, it is difficult to directly enter the power grid. Solving the energy storage problem is the key to successfully expanding the scale of renewable energy production. Therefore, how to store excess clean electricity on a large scale and transmit electricity stably when the supply of sunlight and wind is insufficient is still a technical problem that all countries are working on.

[0004] At present, large-scale electricity storage methods include the use of lead-acid batteries, lithium-ion batteries, hydrogen fuel cells, compressed air energy storage, and pumped storage. Among them, lead-acid batteries, lithium-ion batteries, and hydrogen fuel cell energy storage have not been used on a large scale due to their high investment and maintenance costs; pumped storage is to pump water from a lower position to a higher position to convert electrical energy into the gravitational potential energy of water. Therefore, the pumped storage method has certain requirements for the terrain structure and cannot be applied to relatively flat plains or hilly areas; compressed air energy storage is a mature energy storage technology, but it requires abandoned mines or underground caves as gas storage media, so it can only be used in certain specific areas.

[0005] In view of this, there is an urgent need for a new clean electricity storage method with low investment and maintenance costs and adaptable to various terrains. For example, the Chinese patent application with publication number CN114016988A is a method and system for storing and releasing energy through formations, which performs hydraulic fracturing construction in energy storage formations that do not contain oil and gas, thereby generating at least one formation fracture, and then injecting high-pressure fluid into the obtained formation fracture to cause elastic deformation of the formation fracture to store energy, and then releases energy by reversely discharging the high-pressure fluid in the fracture to push the preset power generation equipment. However, this method is only applicable to formation fractures at the same height. When multiple formation fractures are at different positions and have different closing pressures, this method is no longer applicable, because the different closing pressures of the formation fractures make it uncontrollable for high-pressure fluids to enter the fractures at different positions and to be reversed from the fractures at different positions. Summary of the invention

[0006] The object of the present invention is to provide a method and system for storing and releasing energy at different positions of a formation, which can partially solve or alleviate the above-mentioned deficiencies in the prior art and can be applicable to the storage and release of energy in formation fractures at multiple different depth positions.

[0007] In order to solve the above-mentioned technical problems, the present invention specifically adopts the following technical solutions: A method for storing and releasing energy at different positions in a formation, including an integrated energy storage and release method or a split energy storage and release method that can operate independently; The integrated energy storage and release method comprises: Selecting at least two formation fractures at different depths as target energy storage fractures, wherein the target energy storage fractures at at least two different depths are connected by a wellbore; Injecting high-pressure fluid into the wellbore so that the high-pressure fluid can enter all target energy storage fractures connected to the wellbore, thereby driving the target energy storage fractures to increase in width and allowing formation rocks to accumulate elastic potential energy; the pressure generated by the high-pressure fluid at each target energy storage fracture is greater than the minimum closing pressure of the corresponding target energy storage fracture, and less than the maximum energy storage pressure of the corresponding target energy storage fracture; The wellbore opening is sealed to maintain elastic deformation of the formation rock so as to store energy; When releasing energy, the wellbore plugging pressure is reduced, so that the target energy storage fracture is closed, and during the closing process, the elastic potential energy accumulated in the formation rock is converted into kinetic energy during the back discharge of high-pressure fluid; The split type energy storage and release method comprises: Select at least two or two groups of formation fractures connected by wellbore as target energy storage fractures; Injecting high-pressure fluid into the wellbore, wherein the high-pressure fluid can only enter one of the target energy storage fractures at the same time, thereby driving the width of the target energy storage fracture to increase and allowing the formation rock to accumulate elastic potential energy; or, grouping the target energy storage fractures, wherein the high-pressure fluid can only enter one group of target energy storage fractures at the same time, thereby driving the width of all target energy storage fractures in the group to increase and allowing the formation rock to accumulate elastic potential energy; the pressure generated by the high-pressure fluid at each of the target energy storage fractures in the group is greater than the minimum closing pressure of the corresponding target energy storage fracture, and less than the maximum energy storage pressure of the corresponding target energy storage fracture; The wellbore opening is sealed to maintain elastic deformation of the formation rock so as to store energy; When releasing energy, the wellbore plugging pressure is reduced, so that the target energy storage fracture is closed, and during the closing process, the elastic potential energy accumulated in the formation rock is converted into kinetic energy during the back discharge of high-pressure fluid.

[0008] As an improvement, in the integrated energy storage and release method, the density range of the high-pressure fluid is calculated using the maximum energy storage pressure of the first target energy storage fracture at the depth H1, the minimum closing pressure of the second target energy storage fracture at the depth H2, and the depths of the first target energy storage fracture and the second target energy storage fracture from the wellhead, H1<H2; specifically, the formula is used: < < ; Calculate the density range of the high pressure fluid; wherein, is the maximum energy storage pressure of the first target energy storage fracture, is the density of the high pressure fluid, is the gravity acceleration, H1 is the depth of the first target energy storage fracture from the wellhead, H2 is the depth of the second target energy storage fracture from the wellhead, is the minimum closing pressure of the second target energy storage fracture, and P0 is the injection pressure of the high-pressure fluid.

[0009] As an improvement, in the split energy storage and release method, the difference between the minimum closure pressures of the same group of target energy storage fractures is less than a threshold value.

[0010] As an improvement, in the split energy storage and release method, only one target energy storage crack or a group of target energy storage cracks are closed at the same time to convert the elastic potential energy into the kinetic energy of the high-pressure fluid when it is discharged.

[0011] As an improvement, in the split energy storage and release method, each or each group of the target energy storage fractures is respectively sealed in an independent cavity; the cavity has a channel connected to the wellbore, and the channel can be opened and closed.

[0012] As an improvement, the target energy storage fracture is a hydraulic fracturing fracture or a natural fracture or a fault gap.

[0013] As an improvement, when injecting the high-pressure fluid, electrical energy is used to drive the injection equipment; when releasing energy, the kinetic energy of the high-pressure fluid during backflow is converted into electrical energy through a preset generator.

[0014] As an improvement, in the split energy storage and release method, any one of the target energy storage cracks or any one group of target energy storage cracks with corresponding energy storage is selected for closure according to the power demand of the generator.

[0015] The present invention also provides a system for storing and releasing energy at different positions of a formation, which is equipped with the above-mentioned integrated energy storage and release method, and comprises: An injection device is used to inject high-pressure fluid into the target energy storage fracture through the wellbore, thereby driving the width of the target energy storage fracture to increase and allowing the formation rock to accumulate elastic potential energy; the pressure generated by the high-pressure fluid at each target energy storage fracture is greater than the minimum closing pressure of the target energy storage fracture and less than the maximum energy storage pressure of the target energy storage fracture; A plugging device is used to plug the wellbore opening and maintain elastic deformation of the formation rock to store energy; The power generation device is used to convert the kinetic energy of the high-pressure fluid converted from the elastic potential energy accumulated in the formation rock during the closing process of the target energy storage fracture into electrical energy.

[0016] The present invention also provides a system for storing and releasing energy at different positions of a formation, which is equipped with the above-mentioned split type energy storage and release method, and comprises: An isolation device is used to isolate each target energy storage fracture or each group of target energy storage fractures connected to the wellbore in an independent cavity; A channel opening and closing device, used to open or close the channel connecting the cavity and the wellbore; An injection device is used to inject a high-pressure fluid into a target energy storage fracture through a wellbore. With the cooperation of a channel opening and closing device, the high-pressure fluid can only enter one of the target energy storage fractures connected to the wellbore at the same time, thereby driving the width of the target energy storage fracture to increase and allowing the formation rock to accumulate elastic potential energy; or, the high-pressure fluid can only enter one group of target energy storage fractures at the same time, thereby driving the width of all target energy storage fractures in the group to increase and allowing the formation rock to accumulate elastic potential energy; the pressure generated by the high-pressure fluid at each of the target energy storage fractures in the group is greater than the minimum closing pressure of the corresponding target energy storage fracture, and less than the maximum energy storage pressure of the corresponding target energy storage fracture; A plugging device is used to plug the wellbore opening and maintain elastic deformation of the formation rock to store energy; The power generation device is used to convert the kinetic energy of the high-pressure fluid converted from the elastic potential energy accumulated in the formation rock during the closing process of the target energy storage fracture into electrical energy.

[0017] The invention is beneficial in that it uses electric energy to inject high-pressure fluid into cracks at different positions of the formation, so that the width of the cracks in the formation is increased, thereby converting electric energy into elastic deformation energy of the formation rock for storage, thereby achieving energy storage with low investment and low maintenance costs. The electric energy in the above steps can come from renewable energy such as wind power generation or solar power generation.

[0018] Furthermore, during the gradual closing process of the formation cracks, due to the squeezing effect of the formation rocks, the high-pressure fluid in the cracks is discharged back to the ground to drive the preset power generation equipment to generate electricity, that is, the elastic deformation energy of the formation cracks is converted into electrical energy, thereby achieving stable power supply in the case of insufficient solar energy or wind energy.

[0019] The method and system of the present invention can convert the electric energy generated by sunlight or wind into rock elastic deformation energy for storage when there is sufficient sunlight or wind, and release the electric energy to the power grid when needed, which is of great significance for the peak regulation of wind power generation or solar power generation connected to the grid.

[0020] The method disclosed in the present invention also relates to hydraulic fracturing. As a mature technology in the field of oil and gas, hydraulic fracturing has been used on a large scale. Therefore, related construction supporting equipment is easy to obtain and the cost is controllable.

[0021] In addition, in some embodiments, multiple formation fractures perform integrated energy storage and release, which is low-cost and simple to control.

[0022] In other embodiments, multiple formation fractures are controlled separately to store and release energy, which is more flexible to control and more convenient to use than the integrated type. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, each element or part is not necessarily drawn according to the actual scale. Obviously, the drawings described below are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without paying creative labor.

[0024] Figure 1 This is a flow chart of Embodiment 1; Figure 2 It is a structural schematic diagram of embodiment 1; Figure 3 This is a flow chart of Embodiment 2; Figure 4 It is a structural schematic diagram of Embodiment 2; Figure 5 This is a schematic diagram of the structure of the third embodiment.

[0025] Markings in the figure: 110 formation, 120 wellbore, 130 first target energy storage fracture, 140 second target energy storage fracture.

[0026] 200 injection device I, 215 third target energy storage crack, 220 fourth target energy storage crack, 225 fifth target energy storage crack, 240 inner tube I, 245 isolation device I, 250 isolation device II, 255 isolation device III, 260 water distributor X, 265 water distributor I, 270 water distributor II, 275 channel opening and closing device X, 280 channel opening and closing device I, 285 channel opening and closing device II.

[0027] 300 injection device II, 305 sixth target energy storage crack group, 310 seventh target energy storage crack group, 315 eighth target energy storage crack group, 320 ninth target energy storage crack group, 325 inner tube II, 330 isolation device IV, 335 isolation device V, 340 isolation device VI, 345 isolation device VII, 350 isolation device VIII, 355 water distributor III, 360 water distributor IV, 365 water distributor V, 370 water distributor VI, 375 channel opening and closing device III, 380 channel opening and closing device IV, 385 channel opening and closing device V, 390 channel opening and closing device VI. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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 part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0029] Herein, suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of the present invention, and have no specific meanings by themselves. Therefore, "module", "component" or "unit" can be used mixedly.

[0030] In this document, the terms "upper", "lower", "inner", "outer", "front", "back", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0031] In this document, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] Herein "and / or" includes any and all combinations of one or more of the associated listed items.

[0033] Herein, "plurality" means two or more than two, ie, it includes two, three, four, five, etc.

[0034] Definition: "Fluid" herein may be, but is not limited to, gas, liquid, emulsion, slurry, and solid particle flow with flow characteristics similar to liquid flow. For example, the fluid may include a water-based liquid or supercritical carbon dioxide with chemical additives. In addition, the chemical additives may include, but are not limited to, acid, gel, potassium chloride, surfactant, etc.

[0035] The "formation" herein is a porous and permeable rock formation (e.g., shale formation, sandstone formation, carbonate formation, etc.) underground that can act as a storage space for fluids. Typically, these fluids can be water, hydrocarbons, or gases. Fluid loss from the fractures to the formation can be reduced or hindered by adding a fluid loss control agent to the fluid injected into the fractures in the formation.

[0036] "Hydraulic fracturing" or "fracture" or "fracture" in this article refers to the generation and expansion of cracks in formation rocks under the action of external forces (such as high-pressure fluid).

[0037] "Formation fractures" or "fractures" in this article are rock openings created in the formation after hydraulic fracturing or natural fractures or faults that originally exist in the formation. The terms "formation fractures" or "fractures" are interchangeable. "Fractures" can refer to a single fracture or multiple fractures or fracture swarms adjacent to the same location.

[0038] The term "wellbore" as used herein refers to a hole formed by drilling or inserting a conduit into the formation. Generally, a wellbore is cylindrical, so the cross-section of the wellbore may be circular. In addition, the wellbore may have any other cross-section. The wellbore may be an open-hole wellbore, or a cased wellbore may be formed by cementing a casing to the inner wall of the wellbore. The wellbore connecting the fractures may be a vertical well, a horizontal well, or an inclined well.

[0039] The "fracture closure stress" or "closing pressure" in this article refers to the stress acting vertically on the fracture wall. For horizontal fractures, the fracture closure pressure is equal to the vertical stress (vertical stress) applied to the fracture wall; for vertical fractures, the fracture closure pressure is equal to the minimum horizontal principal stress (minimum horizontal stress) applied to the fracture wall. The fracture closure pressure can be obtained through a small fracturing (Diagnostic Fracturing Injection Test) or a reflux-assisted small fracturing (Rapid Injection-Flowback Test) test. The fracture closure pressure can also be calculated by combining logging data and a geostress model. The terms "fracture closure pressure" or "closing pressure" are interchangeable. The fractures in this article can be vertical fractures or horizontal fractures.

[0040] The “fracture width” in this article refers to the relative displacement distance between the two walls in the direction perpendicular to the fracture surface of the formation.

[0041] In this article, "target energy storage fracture" and "target fracture" are fractures selected for energy storage. The terms "target energy storage fracture" or "target fracture" are interchangeable.

[0042] Embodiment 1 Fractures at different locations in the formation usually have different closure pressures due to different formation depths or different mechanical properties of the formation rock (such as different Young's modulus or Poisson's ratio). Fractures at greater depths usually have greater closure pressures than fractures at lesser depths. Fractures at different locations in the formation can be created by multi-stage fracturing or temporary plugging fracturing. Fractures of different geometric sizes can be created according to the pre-set energy storage size at different locations.

[0043] In order to use the formation fractures at different heights as energy storage bodies, such as Figure 1 As shown, the present invention provides a method for storing and releasing energy at different positions of a formation, specifically an integrated energy storage and release method, and the specific steps thereof include: S101 selects at least two formation fractures at different depths as target energy storage fractures, and the target energy storage fractures are connected by a wellbore.

[0044] In this embodiment, the selected formation fractures may be fractures formed by hydraulic fracturing, or may be natural fractures or fault gaps, as long as they can undergo elastic deformation and accumulate elastic potential energy under the action of high-pressure fluid.

[0045] In addition, in order to facilitate the injection of high-pressure fluid and generate electricity using the reversed high-pressure fluid, multiple target energy storage fractures are connected using the same wellbore (especially a vertical well). Figure 2 As shown, in order to simplify the description in this embodiment, a simple model is used to illustrate the principle of the present invention. In this embodiment, the target energy storage fractures connected by the wellbore 120 in the formation 110 include a first target energy storage fracture located at a depth H1 and a second target energy storage fracture located at a depth H2. It is foreseeable that the number of target energy storage fractures may exceed 2. For example, in addition to the first target energy storage fracture and the second target energy storage fracture, there are one or more target energy storage fractures located between the first target energy storage fracture and the second target energy storage fracture.

[0046] S102 injects high-pressure fluid into the wellbore so that the high-pressure fluid can enter all target energy storage fractures connected to the wellbore, thereby driving the width of the target energy storage fractures to increase and allowing the formation rock to accumulate elastic potential energy; the pressure generated by the high-pressure fluid at each target energy storage fracture is greater than the minimum closing pressure of the target energy storage fracture, and less than the maximum energy storage pressure of the target energy storage fracture.

[0047] During the energy storage process, high-pressure fluid needs to be injected into the target energy storage fracture through the wellbore. The pressure of the high-pressure fluid increases the width of the target energy storage fracture, allowing the formation rock to accumulate elastic potential energy.

[0048] In this embodiment, it is assumed that the maximum energy storage pressure of the first target energy storage fracture at the depth H1 is , the maximum energy storage pressure of the second target energy storage fracture at depth H2 is , the minimum closing pressure of the first target energy storage fracture at depth H1 is , the minimum closure pressure of the second target energy storage fracture at depth H2 is Preferably, H1<H2. Generally speaking, < , < .

[0049] The injection pressure when injecting high-pressure fluid into the wellbore 120 is P0, and the fracture pressure of the first target energy storage fracture 130 is , the fracture pressure of the second target energy storage fracture 140 is If the friction in the wellbore is ignored, the fracture pressure of the first target energy storage fracture 130 is , the fracture pressure of the second target energy storage fracture 140 ,in is the density of the high pressure fluid injected into the wellbore 120, is the acceleration due to gravity (approximately 9.8 m / ), and H2 are the vertical distances of the first target energy storage fracture and the second target energy storage fracture from the wellhead, respectively.

[0050] For a given formation rock mechanical properties (Young's modulus, Poisson's ratio and fracture toughness) and fracture size, in order to prevent the fracture from expanding in the length or height direction during the energy storage process, the fracture pressure and the volume of fluid injected into the fracture have maximum values ​​(i.e., maximum energy storage pressure and maximum energy storage volume). When the fracture pressure and the volume of fluid injected into the fracture reach their maximum values, the fracture reaches the maximum energy storage state. When the fracture pressure or the volume of fluid injected into the fracture is greater than the maximum value, the fracture will expand in the length or height direction.

[0051] Therefore, when injecting high-pressure fluid, both the closing pressure and the maximum energy storage pressure must be considered. In other words, the pressure generated by the high-pressure fluid at each target energy storage fracture is greater than the minimum closing pressure of the target energy storage fracture, and less than the maximum energy storage pressure of the target energy storage fracture. For the upper and lower target energy storage fractures in this embodiment, the high-pressure fluid density needs to meet the following conditions: .

[0052] Since the depth of each target energy storage fracture is different, the pressure generated by the high-pressure fluid is also different. In this embodiment, the density range of the high-pressure fluid is calculated using the maximum energy storage pressure of the first target energy storage fracture at the depth H1, the minimum closing pressure of the second target energy storage fracture at the depth H2, and the depths of the first target energy storage fracture and the second target energy storage fracture from the wellhead, H1<H2; specifically, the formula is used: < < ; Calculate the density range of the high-pressure fluid; where, is the maximum energy storage pressure of the first target energy storage fracture, is the density of the high pressure fluid, is the gravity acceleration, H1 is the vertical depth of the first target energy storage fracture from the wellhead, is the vertical depth of the second target energy storage fracture from the wellhead, is the minimum closing pressure of the second target energy storage fracture, and P0 is the injection pressure of the high-pressure fluid.

[0053] It should be noted that the density of high pressure fluid It is necessary to be within the above range to ensure that each target energy storage crack can be opened and will not expand. It can be understood that for the embodiment of more than two target energy storage cracks, as long as the target energy storage crack with the shallowest depth and the target energy storage crack with the deepest depth can be opened and will not expand, the target energy storage cracks located in the middle position can be satisfied. That is, by controlling the density of the high-pressure fluid, the cracks of different depths can be controlled to be opened and will not expand to a certain extent, that is, the controllability of the cracks at different positions can be achieved to a certain extent.

[0054] In some other embodiments, in addition to calculating the density using a simplified model as in the first embodiment, In addition, the density can also be calculated by numerical simulation and other methods. .

[0055] In this embodiment, the minimum closure pressure and the maximum energy storage pressure of the target energy storage fracture can be calculated using the size of the target energy storage fracture and the mechanical properties of the formation rock.

[0056] S103 seals the wellbore opening and maintains elastic deformation of the formation rock to store energy.

[0057] When all target energy storage fractures are deformed by the injection of high-pressure fluid, the wellbore opening can be closed to maintain the pressure inside the wellbore, thereby maintaining the elastic deformation of the formation rock and achieving the purpose of energy storage.

[0058] When S104 releases energy, the wellbore plugging pressure is reduced, so that the target energy storage fracture is closed, and during the closing process, the elastic potential energy accumulated in the formation rock is converted into kinetic energy during the backflow of high-pressure fluid.

[0059] When energy needs to be released, it is only necessary to reduce the wellbore plugging pressure. The target energy storage fracture will gradually close due to pressure relief. During the closing process, the elastic potential energy accumulated in the formation rock is converted into kinetic energy when the high-pressure fluid is reversed. In this embodiment, a generator is preset at the wellbore outlet to convert the kinetic energy of the high-pressure fluid back into electrical energy.

[0060] Based on the above method, this embodiment provides a system for storing and releasing energy at different positions of a formation, which is deployed with the integrated energy storage and release method disclosed in the first embodiment, including: The injection device is used to inject high-pressure fluid into the target energy storage fracture through the wellbore, thereby driving the width of the target energy storage fracture to increase and allowing the formation rock to accumulate elastic potential energy; the pressure generated by the high-pressure fluid at each target energy storage fracture is greater than the minimum closing pressure of the target energy storage fracture, and less than the maximum energy storage pressure of the target energy storage fracture. The injection device can be driven by electrical energy.

[0061] A plugging device is used to plug the wellbore opening and maintain elastic deformation of the formation rock to store energy; The power generation device is used to convert the kinetic energy of the high-pressure fluid converted from the elastic potential energy accumulated in the formation rock during the closing process of the target energy storage fracture into electrical energy.

[0062] Embodiment 2 Due to the randomness of the location and characteristics of formation fractures, after the injection of high-pressure fluid, it is not necessarily possible to meet the requirement that the pressure generated at each target energy storage fracture is greater than the minimum closure pressure of the target energy storage fracture and less than the maximum energy storage pressure of the target energy storage fracture. As a result, there are certain limitations on the energy storage of multiple formation fractures. In order to improve its universality, such as Figure 3 As shown, this embodiment provides a method for storing and releasing energy at different positions of a formation, specifically a split type energy storage and release method, the steps of which include: S201 selects at least two formation fractures at different depths as target energy storage fractures, and the target energy storage fractures are connected by a wellbore.

[0063] In this embodiment, the selected formation fractures may be fractures formed by hydraulic fracturing, or may be natural fractures or fault gaps, as long as they can undergo elastic deformation and accumulate elastic potential energy under the action of high-pressure fluid.

[0064] In addition, in order to facilitate the injection of high-pressure fluid and generate electricity using the reversed high-pressure fluid, multiple target energy storage fractures are connected using the same wellbore (especially a vertical well). In this embodiment, a simplified model is provided for ease of description. Figure 4 As shown, the wellbore is connected to a third target energy storage fracture 215 at a depth H3, a fourth target energy storage fracture 220 at a depth H4, and a fifth target energy storage fracture 225 at a depth H5. It is foreseeable that the number of target energy storage fractures may exceed two.

[0065] S202 injects high-pressure fluid into the wellbore. At the same time, the high-pressure fluid can only enter the target energy storage fracture connected to one of the wellbores, thereby driving the width of the target energy storage fracture to increase and allowing the formation rock to accumulate elastic potential energy.

[0066] like Figure 4 As shown, during the energy storage process, if the injection device is driven by electric energy to inject high-pressure fluid into the wellbore, it is assumed that the pressure generated by the high-pressure fluid can only open the third target energy storage crack 215 of the target energy storage. However, the fourth target energy storage crack 220 and the fifth target energy storage crack 225 of the target energy storage have higher closing pressures and cannot receive high-pressure fluids below their closing pressures, so energy storage cannot be achieved. If the pressure of the high-pressure fluid is further increased to exceed the minimum closing pressure of the fourth target energy storage crack 220 and the fifth target energy storage crack 225, the pressure may exceed the maximum energy storage pressure of the third target energy storage crack 215, causing the third target crack to expand.

[0067] In order to avoid the above situation, in this embodiment, when injecting high-pressure fluid to drive the target energy storage crack to produce elastic deformation, only one target energy storage crack is injected at the same time. At this time, the other target energy storage cracks are isolated from the target energy storage crack, so the pressure of the high-pressure fluid only needs to consider the target energy storage crack.

[0068] During the energy storage process, high-pressure fluid is only allowed to be injected into a crack at one position at any time, so this method is not affected by the crack closure pressure and the energy storage sequence of cracks at different positions. In order to achieve this goal, in this embodiment, each target energy storage crack is isolated in an independent cavity; the cavity has a channel connected to the wellbore, and the channel can be opened and closed.

[0069] S203 seals the wellbore opening and maintains elastic deformation of the formation rock to store energy.

[0070] Similar to the first embodiment, after all target energy storage fractures are deformed by injection of high-pressure fluid, the wellbore opening can be closed to maintain the pressure inside the wellbore, thereby maintaining the elastic deformation of the formation rock and achieving the purpose of energy storage.

[0071] During energy release at S204, the wellbore plugging pressure is reduced so that the target energy storage fracture is closed, and during the closing process, the elastic potential energy accumulated in the formation rock is converted into kinetic energy during the back discharge of the high-pressure fluid.

[0072] When energy needs to be released, it is only necessary to reduce the wellbore plugging pressure. The target energy storage fracture will gradually close due to pressure relief. During the closing process, the elastic potential energy accumulated in the formation rock is converted into kinetic energy when the high-pressure fluid is reversed. In this embodiment, a generator is preset at the wellbore outlet to convert the kinetic energy of the high-pressure fluid back into electrical energy.

[0073] It is worth noting that when the closing pressure difference between the third target energy storage fracture 215, the fourth target energy storage fracture 220, and the fifth target energy storage fracture 225 is large, the reverse discharge may be uncontrollable when they are closed at the same time. For example, the high-pressure fluid reversely discharged from the fifth target energy storage fracture 225 at the depth H5 will enter the third target energy storage fracture 215 at the depth H3 and the fourth target energy storage fracture 220 at the depth H4, instead of being directly reversely discharged from the wellhead.

[0074] In order to avoid mutual interference caused by different closing pressures of cracks at different locations during the backflow process, during the energy release process, only one target energy storage crack is allowed to close at the same time, and the high-pressure fluid in the crack at this location is backflowed to the ground and drives the preset power generation equipment to generate electricity. During the energy release process, only one crack is allowed to close at any time, and the high-pressure fluid in the crack at this location is backflowed to the ground and drives the preset power generation equipment to generate electricity. Therefore, this method is not affected by the crack closure pressure and the energy release sequence of cracks at different locations. That is, the energy storage and energy release of each crack can be controlled separately, so as to meet different power generation needs.

[0075] Furthermore, a target energy storage crack closure with corresponding energy storage is selected according to the power demand of the generator. Specifically, it can be one or more (those with smaller closing pressure difference).

[0076] like Figure 4 As shown, this embodiment provides a system for storing and releasing energy at different positions of a formation, which is deployed with the split type energy storage and release method disclosed in the second embodiment, including: An isolation device is used to isolate the target energy storage fractures connected to the wellbore in independent cavities; A channel opening and closing device, used to open or close the channel connecting the cavity and the wellbore; The injection device is used to inject high-pressure fluid into the target energy storage fracture through the wellbore. With the cooperation of the channel opening and closing device, the high-pressure fluid can only enter the target energy storage fracture connected to one of the wellbores at the same time, thereby driving the width of the target energy storage fracture to increase and allowing the formation rock to accumulate elastic potential energy; A plugging device is used to plug the wellbore opening and maintain elastic deformation of the formation rock to store energy; The power generation device is used to convert the kinetic energy of the high-pressure fluid converted from the elastic potential energy accumulated in the formation rock during the closing process of the target energy storage fracture into electrical energy.

[0077] Specifically, in the second embodiment, the wellbore connects the third target energy storage fracture 215 at the depth H3, the fourth target energy storage fracture 220 at the depth H4, and the fifth target energy storage fracture 225 at the depth H5. It is foreseeable that the number of target energy storage fractures may exceed 3.

[0078] An inner pipe is arranged in the wellbore, and isolation devices I245, II250 and III255 are arranged along the axial direction of the wellbore, so as to isolate three target energy storage fractures in three independent cavities.

[0079] The injection device I200 is provided with three water distributors, namely water distributor X260, water distributor I265 and water distributor II270, which correspond to three target energy storage cracks respectively. Each water distributor is equipped with a channel opening and closing device, through which the cavity can be connected to the inner tube, so that high-pressure fluid can enter the target energy storage cracks in the cavity.

[0080] For example, to store energy in the third target energy storage crack 215 at depth H3, it is necessary to open the channel opening and closing device X275, close the channel opening and closing device I280, and close the channel opening and closing device II285. In this way, the high-pressure fluid injected from the inner tube I240 can only enter the third target energy storage crack 215 at depth H3 through the only outlet (i.e., the channel opening and closing device X275). Similarly, to store energy in the fourth target energy storage crack 220 at depth H4, it is necessary to open the channel opening and closing device I280, close the channel opening and closing device X275, and close the channel opening and closing device II285. In this way, the high-pressure fluid injected from the inner tube I240 can only enter the fourth target energy storage crack 220 at depth H4 through the only outlet (i.e., the channel opening and closing device I280). Similarly, to store energy in the fifth target energy storage crack 225 at depth H5, it is necessary to open the channel opening and closing device II285, close the channel opening and closing device X275, and close the channel opening and closing device I280. In this way, the high-pressure fluid injected from the inner tube I240 can only enter the fifth target energy storage fracture 225 at the depth H5 through the only outlet (ie, the channel opening and closing device II285).

[0081] If the channel opening and closing device X275 is opened when storing energy in the fifth target energy storage crack 225 at the depth H5, the high-pressure fluid subsequently injected into the inner tube 1240 will enter the third target energy storage crack 215 at the position H3, because the third target energy storage crack 215 has a smaller closing pressure. At the same time, the high-pressure fluid entering the fifth target energy storage crack 225 will also be backflowed into the inner tube 1240, and may even enter the third target energy storage crack 215 at the depth H3 through the channel opening and closing device X275. This will cause serious interference to the energy storage of the fifth target energy storage crack 225.

[0082] This shows the importance of adjusting the flow distribution device during the energy storage process to allow only one target energy storage fracture to be injected with high-pressure fluid at any time and not allow the high-pressure fluid to flow to fractures at other locations.

[0083] Through the cooperation of the injection device 1200 and the channel opening and closing device on the water distributor, only one target energy storage crack is allowed to be injected with high-pressure fluid at any time during the energy storage process, so this method is not affected by the crack closure pressure and the energy storage order of cracks at different positions. For example, in some embodiments, the third target energy storage crack 215 can be firstly stored, then the fourth target energy storage crack 220 can be stored, and finally the fifth target energy storage crack 225 can be stored. In other embodiments, the fifth target energy storage crack 225 can be firstly stored, then the fourth target energy storage crack 220 can be stored, and finally the third target energy storage crack 215 can be stored. Switching from storing energy in the fifth target energy storage crack 225 to storing energy in the fourth target energy storage crack 220 can be done at any time during the energy storage, and it is not necessary to wait until the fifth target energy storage crack 225 reaches the maximum energy storage value before switching to storing energy in the fourth target energy storage crack 220.

[0084] After the energy storage is completed, if energy release is not required, the channel opening and closing device X275, the channel opening and closing device I280, and the channel opening and closing device II285 can all be closed, so that no high-pressure fluid will flow into and out of the target energy storage crack, and the energy storage size of the target energy storage crack remains unchanged.

[0085] During the energy release process, the wellhead pressure is reduced, causing the fractures to gradually close, driving high-pressure fluids to flow back from the fractures to the ground and drive the preset power generation equipment to generate electricity.

[0086] In some energy release embodiments, the channel opening and closing device X275, the channel opening and closing device I280, and the channel opening and closing device II285 can be opened at the same time. The third target energy storage crack 215 located at the depth H3 is closed, driving the internal high-pressure fluid from the channel opening and closing device X275 to flow into the inner tube I240. The fourth target energy storage crack 220 located at the depth H4 is closed, driving the internal high-pressure fluid from the channel opening and closing device X280 to flow into the inner tube I240. The fifth target energy storage crack 225 located at the depth H5 is closed, driving the internal high-pressure fluid from the channel opening and closing device II285 to flow into the inner tube I240. Finally, the high-pressure fluid gathered in the inner tube I240 is discharged back to the ground and drives the preset power generation equipment to generate electricity.

[0087] When the closing pressure difference of the three target energy storage fractures is large, opening the three channel opening and closing devices at the same time may cause uncontrollable reverse discharge. For example, after the high-pressure fluid reversely discharged from the fifth target energy storage fracture 225 at the depth H5 enters the inner tube I240 from the channel opening and closing device II285, it can enter the third target energy storage fracture 215 at the depth H3 and the fourth target energy storage fracture 220 at the depth H4 through the channel opening and closing device X275 and the channel opening and closing device I280 respectively, instead of being directly reversely discharged from the wellhead.

[0088] In order to avoid mutual interference caused by different closing pressures of cracks at different positions during the discharge process, only one target energy storage crack is allowed to close at any time during the energy release process, and the high-pressure fluid in the crack at this position is discharged to the ground and drives the preset power generation equipment to generate electricity.

[0089] For example, to release energy to the third target energy storage crack 215 at a depth of H3, it is necessary to open the channel opening and closing device X275, close the channel opening and closing device I280, and the channel opening and closing device II285. In this way, the high-pressure fluid discharged from the third target energy storage crack 215 through the channel opening and closing device X275 to the inner tube I240 can only be discharged to the ground through the only outlet (i.e., the wellhead) to drive the preset power generation equipment to generate electricity. Similarly, to release energy to the fourth target energy storage crack 220 at a depth of H4, it is necessary to open the channel opening and closing device I280, close the channel opening and closing device X275, and the channel opening and closing device II285. In this way, the high-pressure fluid discharged from the fourth target energy storage crack 220 through the channel opening and closing device I280 to the inner tube I240 can only be discharged to the ground through the only outlet (i.e., the wellhead) to drive the preset power generation equipment to generate electricity. Similarly, to release energy to the fifth target energy storage fracture 225 at depth H5, it is necessary to open the channel opening and closing device II285, close the channel opening and closing device X275, and the channel opening and closing device I280. In this way, the high-pressure fluid discharged from the fifth target energy storage fracture 225 through the channel opening and closing device II285 to the inner tube I240 can only be discharged to the ground through the only outlet (i.e., the wellhead) to drive the preset power generation equipment to generate electricity.

[0090] Since only one crack at a position is allowed to close at any time during the energy release process, the high-pressure fluid in the crack at that position is discharged to the ground and the preset power generation equipment is driven to generate electricity, so this method is not affected by the crack closure pressure and the order of energy release of cracks at different positions. For example, in some embodiments, the target third target energy storage crack 215 can be released first, then the target fourth target energy storage crack 220 can be released, and finally the target fifth target energy storage crack 225 can be released. In other embodiments, the target fifth target energy storage crack 225 can be released first, then the target fourth target energy storage crack 220 can be released, and finally the target third target energy storage crack 215 can be released. Switching from releasing energy to the target fifth target energy storage crack 225 to releasing energy to the target fourth target energy storage crack 220 can be done at any time during the energy release process, and it is not necessary to wait until the energy storage of the target fifth target energy storage crack 225 is reduced to zero before switching to releasing energy to the target fourth target energy storage crack 220.

[0091] In some embodiments, the target fracture to be released can be selected according to the current power generation demand. For example, when the power generation demand is small, the target third target energy storage fracture 215 located at the depth H3 can be selected for energy release, because the closing pressure of the target third target energy storage fracture 215 is low, and the fluid pressure discharged to the wellhead is also low, so the output power of the driving power generation equipment is also low. When the power generation demand is large, the target fifth target energy storage fracture 225 located at the depth H5 can be selected for energy release, because the closing pressure of the target fifth target energy storage fracture 225 is high, and the fluid pressure discharged to the wellhead is also high, so the output power of the driving power generation equipment is also high.

[0092] Embodiment 3 In the second embodiment, since the depth difference between each target energy storage crack is large, the difference between the minimum closure pressure and the maximum energy storage pressure between the target energy storage cracks is also large, so each target energy storage crack needs to be controlled as a separate energy storage and release unit. In this embodiment, a number of target energy storage cracks with similar minimum closure pressures are grouped as a group and controlled as a separate energy storage and release unit, thereby reducing equipment costs.

[0093] For formation fractures of different depths connected by vertical wells or inclined wells, the minimum closure pressure is generally different. However, for formation fractures that are very close to each other, it can also be considered that they have similar minimum closure pressures and can be controlled separately as a group in this embodiment. In fact, when defining formation fractures, the present invention also considers multiple fractures or fracture groups adjacent to the same position as the same formation fracture.

[0094] For formation fractures at different locations connected by horizontal wells, although they are at the same depth, due to the heterogeneity of the formation, the formation fractures at different locations will also have different closing pressures. Therefore, when applying the split energy storage and release method, multiple fractures or fracture groups adjacent to the same location are controlled as a group separately, so it is necessary to use an isolation device to isolate the target energy storage fractures at adjacent locations connected to the wellbore and with the same or similar closing pressures in independent cavities.

[0095] Based on the above grouping of formation fractures, the split energy storage and release method provided in this embodiment includes: S301 selects at least two formation fractures connected by the wellbore as target energy storage fractures.

[0096] like Figure 5 As shown, the wellbore includes a vertical section and a horizontal section, and a plurality of formation fractures are connected to both the vertical section and the horizontal section. Of course, at least two groups of formation fractures connected by the wellbore can also be selected as target energy storage fractures.

[0097] S302 injects high-pressure fluid into the wellbore, and at the same time the high-pressure fluid can only enter one group of target energy storage fractures, thereby driving the width of all target energy storage fractures in the group to increase and allowing the formation rock to accumulate elastic potential energy; the pressure generated by the high-pressure fluid at each target energy storage fracture in the group is greater than the minimum closing pressure of the corresponding target energy storage fracture, and less than the maximum energy storage pressure of the corresponding target energy storage fracture.

[0098] Continuing with the above example, multiple formation fractures connected to the vertical section of the wellbore are located at adjacent depths and have similar minimum closure pressures, so they are grouped together in this embodiment as the sixth target energy storage fracture group 305 and are controlled separately. It is understandable that if there are fractures or fracture groups at other depths in the vertical section, they can also be divided into one or more target energy storage fracture groups according to the similarity of their minimum closure pressures.

[0099] Due to the heterogeneity of the formation, the minimum closure pressures of the multiple formation fractures connected in the horizontal section of the wellbore are different. Therefore, the fractures with similar minimum closure pressures are divided into a target energy storage fracture group, thereby forming the seventh target energy storage fracture group 310, the eighth target energy storage fracture group 315, and the ninth target energy storage fracture group 320.

[0100] The purpose of selecting fractures with similar minimum closure pressures as a group is to meet the condition that "the pressure generated by the high-pressure fluid at each target energy storage fracture in the group is greater than the minimum closure pressure of the corresponding target energy storage fracture, and less than the maximum energy storage pressure of the corresponding target energy storage fracture". The so-called similar minimum closure pressures, in this embodiment, means that the difference between the minimum closure pressures of the target energy storage fractures in the same group is less than a threshold, for example, less than 3Mp.

[0101] S303 seals the wellbore opening to maintain elastic deformation of the formation rock to store energy; During energy release at S304, the wellbore plugging pressure is reduced to close the target energy storage fracture, and during the closing process, the elastic potential energy accumulated in the formation rock is converted into kinetic energy during the back discharge of the high-pressure fluid.

[0102] In order to avoid mutual interference caused by cracks with different closing pressures during the backflow process, only one group of target energy storage cracks is allowed to close at the same time during the energy release process, and the high-pressure fluid in the cracks at this position is backflowed to the ground and drives the preset power generation equipment to generate electricity. During the energy release process, only one group of target energy storage cracks is allowed to close at any time, and the high-pressure fluid in the cracks at this position is backflowed to the ground and drives the preset power generation equipment to generate electricity. Therefore, this method is not affected by the crack closure pressure and the energy release order of cracks at different positions.

[0103] It can be understood that the system for storing and releasing energy at different positions of the formation by deploying the above-mentioned split energy storage and release method is slightly different from that in the second embodiment, which specifically includes: The isolation device is used to isolate each group of target energy-storage fractures connected to the wellbore in an independent cavity; specifically, it includes isolation device IV330 and isolation device V335, which are used to seal the sixth target energy-storage fracture group 305 in an independent cavity. In addition, it also includes isolation device VI340, isolation device VII345, and isolation device VIII350, which are used to isolate the seventh target energy-storage fracture group 310, the eighth target energy-storage fracture group 315, and the ninth target energy-storage fracture group 320.

[0104] The channel opening and closing device is used to open or close the channel connecting the cavity and the wellbore. Specifically, the channel opening and closing device in this embodiment includes a channel opening and closing device 375, a channel opening and closing device 380, a channel opening and closing device 385 and a channel opening and closing device 390, and the above-mentioned channel opening and closing devices correspond to the sixth target energy storage fracture group 305, the seventh target energy storage fracture group 310, the eighth target energy storage fracture group 315 and the ninth target energy storage fracture group 320 one by one.

[0105] The injection device II300 is used to inject high-pressure fluid into the target energy storage fractures through the wellbore. The high-pressure fluid can only enter one group of target energy storage fractures at the same time, thereby driving the width of all target energy storage fractures in the group to increase and allowing the formation rock to accumulate elastic potential energy; the pressure generated by the high-pressure fluid at each target energy storage fracture in the group is greater than the minimum closing pressure of the corresponding target energy storage fracture, and less than the maximum energy storage pressure of the corresponding target energy storage fracture.

[0106] The specific injection device in this embodiment includes a water distributor III355, a water distributor IV360, a water distributor V365 and a water distributor VI370 arranged on the inner tube II325, which correspond to the sixth target energy storage crack group 305, the seventh target energy storage crack group 310, the eighth target energy storage crack group 315 and the ninth target energy storage crack group 320 respectively.

[0107] A plugging device is used to plug the wellbore opening and maintain elastic deformation of the formation rock to store energy; The power generation device is used to convert the kinetic energy of the high-pressure fluid converted from the elastic potential energy accumulated in the formation rock during the closing process of the target energy storage fracture into electrical energy.

[0108] The working principle of the above device is shown in Example 2, which will not be described in detail in this example.

[0109] It should be noted that the various devices in this embodiment are only one of many forms. For example, in other embodiments, the channel opening and closing device can be a valve or a nozzle, which will not be listed one by one in this embodiment.

[0110] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including 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. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0111] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A method for storing and releasing energy in cracks at different positions in a formation, characterized by: Including an integrated energy storage and release method or a split energy storage and release method that can operate independently; The integrated energy storage and release method comprises: Selecting at least two formation fractures at different depths as target energy storage fractures, wherein the target energy storage fractures at at least two different depths are connected by a wellbore; Injecting high-pressure fluid into the wellbore so that the high-pressure fluid can enter all the target energy storage fractures connected to the wellbore, thereby driving the width of the target energy storage fractures to increase, and then allowing the formation rock to accumulate elastic potential energy; the pressure generated by the high-pressure fluid at each target energy storage fracture is greater than the minimum closing pressure of the corresponding target energy storage fracture, and less than the maximum energy storage pressure of the corresponding target energy storage fracture; Blocking the wellbore opening and maintaining elastic deformation of the formation rock to store energy; When releasing energy, the wellbore plugging pressure is reduced to close the target energy storage fracture, and the reversed high-pressure fluid is used to generate electricity during the closing process; The split type energy storage and release method comprises: Select at least two or two groups of formation fractures connected by wellbore as target energy storage fractures; A high-pressure fluid is injected into the wellbore, and the high-pressure fluid can only enter one of the target energy storage fractures at the same time, thereby driving the width of the target energy storage fracture to increase and allowing the formation rock to accumulate elastic potential energy; or, the high-pressure fluid can only enter one group of target energy storage fractures at the same time, thereby driving the width of all target energy storage fractures in the same group to increase and allowing the formation rock to accumulate elastic potential energy; the pressure generated by the high-pressure fluid at each of the target energy storage fractures in the same group is greater than the minimum closing pressure of the corresponding target energy storage fracture, and less than the maximum energy storage pressure of the corresponding target energy storage fracture; The wellbore opening is sealed to maintain elastic deformation of the formation rock so as to store energy; When releasing energy, the wellbore plugging pressure is reduced to close the target energy storage fracture, and the reversed high-pressure fluid is used to generate electricity during the closing process; The target energy storage cracks in the integrated energy storage and release method or the split energy storage and release method are hydraulic fracturing cracks or natural cracks or fault gaps.

2. A method for storing and releasing energy in cracks at different positions in a formation according to claim 1, characterized in that: In the integrated energy storage and release method, the density range of the high-pressure fluid is calculated using the maximum energy storage pressure of the first target energy storage fracture at the depth H1, the minimum closing pressure of the second target energy storage fracture at the depth H2, and the depths of the first target energy storage fracture and the second target energy storage fracture from the wellhead, H1<H2; specifically, the formula is used: ； Calculate the density range of the high pressure fluid; wherein, is the maximum energy storage pressure of the first target energy storage fracture, is the density of the high pressure fluid, is the gravity acceleration, H1 is the depth of the first target energy storage fracture from the wellhead, H2 is the depth of the second target energy storage fracture from the wellhead, is the minimum closing pressure of the second target energy storage fracture, and P0 is the injection pressure of the high-pressure fluid.

3. A method for storing and releasing energy in fractures at different positions of a formation according to claim 1, characterized in that: In the split energy storage and release method, the difference between the minimum closure pressures of the same group of target energy storage fractures is less than the threshold value.

4. A method for storing and releasing energy in fractures at different positions of a formation according to claim 1, characterized in that: In the split energy storage and release method, only one target energy storage fracture or a group of target energy storage fractures are closed at the same time, and the high-pressure fluid in the target energy storage fracture is discharged to the ground and drives the preset power generation equipment to generate electricity.

5. A method for storing and releasing energy in cracks at different positions in a formation according to claim 1, characterized in that: In the split energy storage and release method, each or each group of the target energy storage fractures are respectively sealed in an independent cavity; the cavity has a channel connected to the wellbore, and the channel can be opened and closed.

6. A method for storing and releasing energy in fractures at different positions in a formation according to claim 1, characterized in that: When the high-pressure fluid is injected, the injection device is driven by electrical energy; when the energy is released, the kinetic energy of the high-pressure fluid during reverse discharge is converted into electrical energy through a preset generator.

7. A method for storing and releasing energy in fractures at different positions of a formation according to claim 6, characterized in that: In the split energy storage and release method, any one of the target energy storage cracks or any one group of target energy storage cracks with corresponding energy storage is selected for closure according to the power demand of the generator.

8. A system for storing and releasing energy in cracks at different positions of a formation, which is equipped with the integrated energy storage and release method according to claim 1, characterized in that include: An injection device is used to inject a high-pressure fluid into a target energy storage fracture connected to the wellbore through a wellbore, thereby driving the width of the target energy storage fracture to increase and allowing the formation rock to accumulate elastic potential energy; the pressure generated by the high-pressure fluid at each target energy storage fracture is greater than the minimum closing pressure of the target energy storage fracture and less than the maximum energy storage pressure of the target energy storage fracture; A plugging device, used to plug the wellbore opening and maintain elastic deformation of the formation rock to store energy; A power generation device is used to generate electricity using high-pressure fluid discharged from the target energy storage fracture during the closing process.

9. A system for storing and releasing energy in fractures at different positions of a formation, which is equipped with the split type energy storage and release method according to claim 1, characterized in that include: An isolation device is used to isolate each target energy storage fracture or each group of target energy storage fractures connected to the wellbore in an independent cavity; the target energy storage fracture is a hydraulic fracture or a natural fracture or a fault gap; A channel opening and closing device, used to open or close the channel connecting the cavity and the wellbore; An injection device is used to inject high-pressure fluid into the target energy storage fracture through the wellbore. With the cooperation of the channel opening and closing device, the high-pressure fluid can only enter the target energy storage fracture connected to one of the wellbores at the same time, thereby driving the width of the target energy storage fracture to increase and allowing the formation rock to accumulate elastic potential energy; Alternatively, the high-pressure fluid can only enter one group of target energy storage fractures at the same time, thereby driving the width of all target energy storage fractures in the group to increase and allowing the formation rock to accumulate elastic potential energy; the pressure generated by the high-pressure fluid at each target energy storage fracture in the group is greater than the minimum closing pressure of the corresponding target energy storage fracture, and less than the maximum energy storage pressure of the corresponding target energy storage fracture; A plugging device, used to plug the wellbore opening and maintain elastic deformation of the formation rock to store energy; A power generation device is used to generate electricity using high-pressure fluid discharged from the target energy storage fracture during the closing process.

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