Method and system for storing and releasing energy and obtaining geothermal energy through existing original stratum fractures of stratum

Abstract

The invention relates to a method for storing and releasing energy and obtaining geothermal energy through existing original stratum fractures of a stratum. The method comprises the steps that at least one energy storage geothermal layer which has rich geothermal resources, does not contain oil gas and has at least one existing original stratum fracture is recognized; screening at least one target artificial fracture from the at least one stratum fracture; normal-temperature high-pressure fluid is injected into the at least one target artificial fracture through injection equipment, so that the fracture width of the at least one target artificial fracture is increased, and the electric energy is converted into stratum rock elastic deformation energy to be stored; the high-pressure fluid exchanges heat with the surrounding energy storage geothermal layer in the crack injection and storage process, so that the temperature is increased; high-temperature and high-pressure fluid in the cracks is reversely discharged to the ground to drive geothermal power generation equipment and hydroelectric power generation equipment to generate power due to the closing process of at least one target artificial crack, so that geothermal energy in the stratum is obtained, and stored rock elastic deformation energy is converted into electric energy again. The energy storage method is low in investment and maintenance cost, can adapt to different earth terrains, and is wide in application range. In addition, geothermal resources in the stratum can be obtained while energy storage is carried out.

Description

Technical Field

[0001] The present invention relates to the field of underground energy storage, and in particular to a method and system for storing and releasing energy and obtaining geothermal energy through existing original formation cracks in the formation. Background Art

[0002] Renewable energy such as wind power and solar power often have significant intermittent, volatile and random characteristics. With the large-scale development of new energy and high proportion of grid connection, power balance, safe and stable control will face unprecedented challenges. Therefore, the energy storage industry is an inevitable requirement to balance the volatility of new energy power generation and meet the peak demand of electricity users.

[0003] Existing energy storage technologies mainly include mechanical energy storage and electrochemical energy storage. Among them, electrochemical energy storage includes lead-acid batteries, lithium-ion batteries and hydrogen fuel cell energy storage. Due to the high investment and maintenance costs, and the fact that there are still great problems in the environment and safety, it has not been used on a large scale; mechanical energy storage mainly includes pumped energy storage and air compression energy storage. Pumped energy storage is to pump water from a lower position to a higher position and convert electrical energy into the gravitational potential energy of water. Therefore, the pumped energy storage method often has high requirements for the terrain structure and cannot be applied to plains or hilly areas with relatively flat terrain. At the same time, it also has corresponding requirements for the climate and rainfall in the application area; 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.

[0004] Geothermal energy is also the main direction of new energy development. Traditional geothermal energy mining often targets faults with more developed natural fractures in the strata. However, it is difficult to meet today's geothermal mining needs by relying solely on natural fractures. At the same time, excessive development of faults will also lead to geological safety problems. Existing geothermal mining is mainly carried out in a multi-well manner through multi-stage hydraulic fracturing technology. However, this method has problems such as high investment and maintenance costs, easy flow short circuits, and low geothermal mining utilization.

[0005] In view of this, there is an urgent need for a new energy storage method that has low investment and maintenance costs, adapts to the storage requirements of various terrains, and can effectively exploit geothermal resources. Summary of the invention

[0006] The present invention provides a method and system for storing energy and obtaining geothermal energy through existing original formation cracks in the formation, which can alleviate the above-mentioned problems to a certain extent or partially.

[0007] In order to solve the above problems, the present invention adopts the following technical solutions:

[0008] The first aspect of the present invention is to provide a method for storing energy and obtaining geothermal energy through existing original formation fractures in the formation, which comprises the steps of:

[0009] Identifying at least one geothermal reservoir layer that is rich in geothermal resources and does not contain oil or gas and has at least one original formation fracture;

[0010] Screening at least one target formation fracture from the at least one original formation fracture;

[0011] Injecting a normal temperature and high pressure fluid into the at least one target formation fracture using an injection device, so that the fracture width of the target formation fracture increases to a target width, thereby converting electrical energy into elastic deformation energy of the formation rock for storage, and at the same time, the high pressure fluid in the target formation fracture exchanges heat with the energy storage geothermal layer to increase the fluid temperature;

[0012] The high-temperature and high-pressure fluid discharged during the closing process of the target formation fracture is used to drive the preset hydroelectric power generation equipment and geothermal power generation equipment to generate electricity, thereby converting the acquired geothermal energy and the elastic deformation energy of the formation rock into electrical energy for energy release;

[0013] The step of using the high-temperature and high-pressure fluid discharged during the closing process of the target formation fracture to drive the preset hydroelectric power generation equipment and geothermal power generation equipment to generate electricity specifically includes:

[0014] Monitor whether there is a demand for power generation, and when it is detected that there is a demand for power generation, open the control valve on the backflow pipeline connected to the wellbore corresponding to the target formation fracture, so that the high-temperature and high-pressure fluid in the target formation fracture is backflowed through the backflow pipeline and drives the hydroelectric power generation equipment to generate electricity; otherwise, continue to monitor whether there is a demand for power generation; judge whether the high-temperature and high-pressure fluid backflowed during the closing process of the target formation fracture drives the hydroelectric power generation equipment to generate electricity, and if so, open the geothermal power generation equipment, so that the high-temperature and high-pressure fluid backflowed during the closing process of the target formation fracture drives the geothermal power generation equipment to generate electricity; if the geothermal power generation condition is not met, judge whether the high-temperature and high-pressure fluid meets the heating demand, if it meets the heating demand, connect the high-temperature and high-pressure fluid to the heating system, and if it does not meet the heating demand, discharge the high-temperature and high-pressure fluid into a preset water reservoir.

[0015] In some embodiments of the present invention, before the high-temperature and high-pressure fluid discharged during the closure of the formation fractures is used to drive the preset geothermal power generation equipment to generate electricity, the wellbore, the discharge pipe and the hydroelectric power generation equipment are all insulated.

[0016] In some embodiments of the present invention, the step of identifying the energy storage geothermal layer specifically includes: constructing a fluid-solid thermal coupling numerical model of "wellbore-fracture-formation" according to the thermal conductivity of underground rocks, temperature gradient and groundwater circulation conditions; when the wellbore outlet temperature simulated based on the fluid-solid thermal coupling numerical model can reach above the power generation temperature, marking the energy storage geothermal layer as directly capable of supplying electricity and / or heating; when the wellbore outlet temperature simulated based on the fluid-solid thermal coupling numerical model does not reach above the power generation temperature but meets the heating demand, marking the energy storage geothermal layer as capable of heating.

[0017] In some embodiments of the present invention, when there are multiple wellbores, if there is a demand for power generation, it is determined whether the outlet temperature of each wellbore in the energy storage geothermal layer marked as being able to directly supply electricity and / or heat meets the requirements of the geothermal power generation equipment, and the wellbore with the outlet temperature meeting the requirements of the geothermal power generation equipment is selected to reverse the high-temperature and high-pressure fluid for power generation; wherein, the step of determining whether the wellbore outlet temperature meets the requirements of the geothermal power generation equipment specifically includes: simulating the relationship between the wellbore closed heat storage time and the wellbore outlet temperature based on a fluid-solid-heat coupling numerical model; calculating the required target closed heat storage time using a fluid-solid-heat coupling numerical model according to the wellbore outlet temperature required for power generation; timing the closed heat storage time of each wellbore after the reverse discharge pipeline is closed, and determining whether the closed heat storage time of each wellbore is greater than or equal to the corresponding target closed heat storage time, and if so, determining that the outlet temperature of the corresponding wellbore meets the requirements of the geothermal power generation equipment.

[0018] In some embodiments of the present invention, the original formation fractures include artificial fractures, the at least one target formation fractures include at least one target artificial fracture, and the step of screening out at least one target artificial fracture from the at least one original formation fracture specifically includes the steps of: obtaining first monitoring data of the artificial fractures in the energy storage formation by using a preset monitoring device; calculating the original length and original height of the artificial fractures in the energy storage formation by combining the first monitoring data and the first construction parameters of the artificial fractures acquired in advance with a numerical model of fracture extension; judging whether the original length and original height of the artificial fractures reach a preset target length threshold and a target height threshold, and if so, marking the artificial fractures as the target artificial fractures; and / or, the original formation fractures include natural fractures in a closed state, and accordingly, the at least one target formation fracture includes at least one target The method comprises the steps of: obtaining second monitoring data of the natural fractures in the energy storage geothermal layer by a preset monitoring device, and performing inversion according to the second monitoring data to obtain the distribution of the at least one natural fracture; the second monitoring data comprises: logging data and seismic data; obtaining the three-dimensional stress distribution of the energy storage geothermal layer by tectonic stress analysis; simulating the opening of the at least one natural fracture during the injection of normal temperature and high pressure fluid into the at least one natural fracture by a three-dimensional fracture-stress coupling model, and calculating the energy storage amount when the width of the at least one natural fracture expands to the target width under the action of the normal temperature and high pressure fluid; judging whether the energy storage amount reaches the preset target energy storage amount, and if so, marking the at least one natural fracture as a target natural fracture.

[0019] In some embodiments of the present invention, the method for storing energy and obtaining geothermal energy through existing original formation fractures in the formation further comprises the steps of:

[0020] Determine whether the number of the target artificial cracks reaches a preset number threshold; if not, perform secondary transformation on the artificial cracks whose original length and original height do not meet the preset target length threshold and target height threshold. Specifically, the step of performing secondary transformation on the artificial cracks includes:

[0021] According to a preset third construction parameter, injecting fluid into the artificial fracture through the wellbore, so that the fracture pressure in the artificial fracture is greater than the fracture expansion pressure, so that the artificial fracture expands along its original height and original length direction;

[0022] Acquiring third monitoring data during the expansion of the artificial fracture by means of the monitoring device;

[0023] According to the third construction parameter and the third monitoring data, in combination with the crack extension numerical model, the latest length and the latest height of the artificial crack after extending along the original height and the original length are calculated;

[0024] Determine whether the latest length and the latest height reach the target length threshold and the target height threshold, and if so, stop injecting the normal temperature high pressure fluid to obtain the target artificial fracture;

[0025] The target length threshold and the target height threshold are pre-deduced based on the required fluid kinetic energy and thermal energy carried by the fluid, as well as the target width of the existing formation fractures.

[0026] In some embodiments of the present invention, the method for storing energy and obtaining geothermal energy through existing original formation fractures in the formation further comprises the steps of:

[0027] When it is determined that the energy storage capacity does not reach the preset target energy storage capacity, injecting fluid into the natural fracture through the wellbore according to a preset fourth construction parameter, so that the fracture pressure in the natural fracture is greater than the fracture expansion pressure, thereby causing the natural fracture to expand along the original height and original length direction;

[0028] Acquiring fourth monitoring data during the extension of the natural fracture through the monitoring device; calculating the latest length and the latest height of the natural fracture after extension using a numerical model of fracture extension according to the fourth construction parameter and the fourth monitoring data;

[0029] Determine whether the latest delayed length and the latest height of the natural fracture reach a preset target length threshold and a target height threshold, and if so, stop injecting fluid to obtain the target natural fracture;

[0030] The target length threshold and the target height threshold are pre-deduced based on the required fluid kinetic energy and thermal energy carried by the fluid, as well as the target width of the existing formation fractures.

[0031] In some embodiments of the present invention, the step of injecting a normal temperature and high pressure fluid into the at least one target formation fracture using an injection device specifically includes:

[0032] injecting a normal temperature and high pressure fluid into the target formation fracture according to a preset second construction parameter, so that the fracture pressure in the target formation fracture gradually increases; the target formation fracture includes at least one of the artificial fractures and / or at least one of the target natural fractures;

[0033] real-time monitoring of the fracture pressure in the target formation fracture, and determining whether the fracture pressure is greater than the closing pressure, so that the closed state of the target formation fracture becomes an open state;

[0034] If the fracture pressure is greater than the closing pressure, adjusting the second construction parameter so that the pressure of the fluid injected into the target formation fracture is greater than the closing pressure and less than the expansion pressure of the target formation fracture, so that the fracture width of the target formation fracture gradually increases;

[0035] Determine whether the width of at least one of the target formation fractures is equal to or greater than a preset target width. If so, stop supplying electrical energy to the injection device so that the injection device stops injecting the normal temperature and high pressure fluid into the at least one target formation fracture.

[0036] A second aspect of the present invention is to provide a system for storing energy and obtaining geothermal energy through existing original formation fractures in the formation, comprising:

[0037] A formation identification device, used for identifying at least one energy storage geothermal layer having rich geothermal resources and no oil or gas and having at least one original formation fracture; the at least one original formation fracture comprises a natural fracture in a closed state and / or an artificial fracture in a closed state;

[0038] A formation fracture screening device, used for screening out at least one target formation fracture from at least one original formation fracture identified by the formation identification device, wherein the at least one target formation fracture includes at least one target artificial fracture and / or at least one target natural fracture;

[0039] An injection device is used to inject a normal temperature and high pressure fluid into the at least one target formation fracture, so that the fracture width of the at least one target formation fracture increases to a target width, thereby converting electrical energy into elastic deformation energy of the formation rock for storage, and at the same time, after the normal temperature and high pressure fluid is injected into the target formation fracture, heat is exchanged with the formation to increase the temperature;

[0040] A hydroelectric power generation device, used for converting elastic deformation energy of the formation rock into electrical energy driven by the high-temperature and high-pressure fluid when the high-temperature and high-pressure fluid in the target formation fracture is reversed under the rock squeezing action during the closing process of the target formation fracture;

[0041] Geothermal power generation equipment, used for converting the obtained geothermal energy into electrical energy under the drive of the high-temperature and high-pressure fluid in the target formation fractures after the high-temperature and high-pressure fluid in the target formation fractures is reversed under the rock compression during the closing process of the target formation fractures and drives the hydroelectric power generation device to generate electricity;

[0042] A backflow pipeline is connected to the hydroelectric power generation equipment and the geothermal power generation equipment and is externally connected to a heating system. When the high-temperature and high-pressure fluid in the target formation fracture is backflowed through the backflow pipeline, the hydroelectric power generation equipment and the geothermal power generation equipment are driven to generate electricity and / or the heating system is used to provide heating;

[0043] The plugging device is used to close the backflow pipeline so that the fluid in the target formation fracture continues to exchange heat with the energy storage geothermal layer so that the fluid temperature continues to rise.

[0044] In some embodiments of the present invention, the system for storing energy and obtaining geothermal energy through existing original formation fractures in the formation further includes:

[0045] A water reservoir for storing the normal temperature and high pressure fluid, wherein the water reservoir is connected to the wellbore corresponding to the target formation fracture through the backflow pipeline, and a control valve is provided in the backflow pipeline;

[0046] A monitoring device is connected to the control valve and is used to monitor whether there is a demand for power generation. When a demand for power generation is detected, a first control instruction indicating opening the control valve is generated and sent to the control valve, so that the wellbore is connected to the water reservoir through the backflow pipeline; otherwise, the monitoring device continues to monitor whether there is a demand for power generation.

[0047] A judgment device is connected to the control valve, and is used to judge whether the high-temperature and high-pressure fluid discharged during the closing process of the target formation fracture drives the hydroelectric power generation equipment to generate electricity, and whether the geothermal power generation conditions are met. When the geothermal power generation conditions are met, a second control instruction indicating the start of the geothermal power generation equipment is generated and sent to the geothermal power generation equipment, so that the geothermal power generation equipment generates electricity under the drive of the high-temperature and high-pressure fluid; otherwise, it continues to judge whether the heating demand is met, and when it is judged that the heating demand is met, the high-temperature and high-pressure fluid that is discharged is allowed to flow into the heating system for heating.

[0048] Beneficial effects: The present invention identifies at least one energy storage geothermal layer that is rich in geothermal resources, does not contain oil and gas, and has at least one original formation fracture; screens out at least one target formation fracture from the at least one formation fracture; and then uses injection equipment to inject room temperature and high-pressure fluid into the target formation fracture, so that the fracture width of the formation fracture increases, thereby converting electrical energy into elastic deformation energy of formation rock for storage, thereby achieving energy storage with low investment and low maintenance costs; at the same time, the fluid in the fracture exchanges heat with the energy storage geothermal layer to increase the temperature, thereby obtaining geothermal energy.

[0049] Furthermore, in the process of gradual closing of the formation fractures, due to the squeezing effect of the formation rocks, the high-temperature and high-pressure fluid in the fractures is discharged back to the ground to drive the preset hydroelectric power generation equipment and geothermal power generation equipment to generate electricity, that is, the elastic deformation energy of the formation fractures and the obtained geothermal energy are converted into electrical energy, thereby achieving stable power supply in the case of insufficient solar energy or wind energy.

[0050] Compared with the prior art, the desired formation cracks are obtained by directly performing hydraulic fracturing construction in the formation, that is, energy storage and energy release are performed through controllable formation cracks. In the present invention, the existing formation cracks in the formation are used to enter and exit energy storage or release. Since the formation cracks for energy storage and energy release are already in the formation, that is, many parameters such as the number and geometric dimensions of the formation cracks are fixed and uncontrollable, therefore, the core of the present invention is to screen out target formation cracks (for example, at least one target artificial crack, and / or, at least one target natural crack) in the existing uncontrollable formation cracks. Compared with the method of directly performing hydraulic fracturing construction, the method of the present invention reduces the construction difficulty because there is no need to perform hydraulic fracturing construction, and the investment and maintenance costs are lower.

[0051] The method and system of the present invention can convert the electric energy generated by sunlight or wind into elastic deformation energy of rock for storage when there is sufficient sunlight or wind, and obtain geothermal energy through heat exchange between injected fluid and formation, and then convert the stored and obtained energy into electric energy and release it 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] 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.

[0053] Figure 1A In an exemplary embodiment of the present invention, the original formation fractures are formed through the formation. A schematic flow diagram of a method for storing and releasing energy and obtaining geothermal energy;

[0054] Figure 1B It is a schematic flow chart of a method for storing and releasing energy and obtaining geothermal energy through original formation fractures in a formation in another exemplary embodiment of the present invention;

[0055] Figure 2In the present invention, at least one target artificial Schematic diagram of the crack process;

[0056] Figure 3 It is a schematic diagram of the process of secondary transformation of artificial fractures in the present invention;

[0057] Figure 4 A functional module diagram of a system for storing and releasing energy and obtaining geothermal energy through existing original formation fractures in the formation according to an exemplary embodiment of the present invention;

[0058] Figure 5A is a schematic diagram of an electric injection device injecting fluid from a water reservoir into a formation fracture in a shale formation in an exemplary embodiment of the present invention;

[0059] Figure 5B It is a schematic diagram of discharging high-temperature and high-pressure fluid in a formation fracture back into a water reservoir and driving a power generation device to generate electricity in an exemplary embodiment of the present invention;

[0060] Fig. 6A is a schematic diagram of an electric injection device injecting fluid from a water reservoir into a formation fracture in a shale formation in another exemplary embodiment of the present invention;

[0061] Figure 6B It is a schematic diagram of another exemplary embodiment of the present invention, in which high-temperature and high-pressure fluid in a formation fracture is discharged back into a water reservoir and a power generation device is driven to generate electricity;

[0062] Figure 7 It is a schematic diagram of a system for utilizing multiple vertical wells and multiple horizontal wells for hydraulic fracturing to achieve continuous energy storage and release and obtain geothermal energy.

[0063] Reference numerals:

[0064] Figure 5A and Figure 5B Among them, 500 injection equipment, 510 water storage tank, 520 injection pipeline, 530 wellbore, 540 shale formation, 550 hydroelectric power generation equipment, 560 geothermal power generation equipment, 570 backflow pipeline, 580 heating system, 590 formation fractures;

[0065] Fig. 6A and Figure 6B Among them, 610 integrated power generation and water injection machine, 620 geothermal power generation equipment, 630 reservoir, 640 pipeline, 650 wellbore, 660 shale formation, 670 formation fracture, 680 heating system;

[0066] Figure 7 Among them, there are 710 vertical wells, 720 vertical wells, 730 vertical wells, 740 horizontal wells, 750 horizontal wells, and 760 horizontal wells. DETAILED DESCRIPTION

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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, an indirect connection through an intermediate medium, or a connection between the 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. "And / or" in this document includes any and all combinations of one or more listed related items. "Multiple" in this document means two or more, that is, it includes two, three, four, five, etc.

[0071] In this specification, some embodiments may be disclosed in a format of being in a certain range. It should be understood that such description of "being in a certain range" is only for convenience and brevity, and should not be interpreted as a rigid limitation on the disclosed range. Therefore, the description of the range should be considered to have specifically disclosed all possible sub-ranges and independent numerical values ​​within this range.

[0072] "Fluid" herein may be, but is not limited to, gas, liquid, emulsion, slurry, and solid particle flow having flow characteristics similar to liquid flow. For example, the fluid may include a water-based liquid with chemical additives. In addition, the chemical additives may include, but are not limited to, acid, gel, potassium chloride, surfactants, etc.

[0073] The "original formation fractures" in this article refer to the open cracks in the rock that have been transformed by hydraulic fracturing, or the naturally existing fractures in the energy storage formation that contain geothermal resources but no oil and gas, and these original formation fractures are in a closed state.

[0074] The "transformation" or "secondary transformation" in this article refers to the extension and expansion of existing original formation fractures in the energy storage formation along their original height and length under the action of external forces (such as high-pressure fluid at normal temperature), but their width, fracture spacing and number remain unchanged.

[0075] The "formation" or "reservoir" herein refers to an underground porous and permeable rock formation (e.g., shale formation, sandstone formation, carbonate formation, etc.) that can serve as a storage space for fluids. These fluids can usually be water, hydrocarbons, or gases. In this article, such porous and permeable rock formations that can store high-pressure fluids are collectively referred to as "energy storage formations." Among them, shale formations are able to store fluids in their internal cracks for a long time. Therefore, shale formations are used as a preferred embodiment herein to illustrate the energy storage and release methods and systems of the present application.

[0076] The term "hydraulic fracturing" or "fracture" or "fracture" in this article refers to the Cracks are generated and expanded under the action of external forces (such as high-pressure fluid).

[0077] "Hydraulic fracturing fractures" or "formation fractures" or "fractures" herein are open rock gaps created in the formation after hydraulic fracturing construction, and the terms "hydraulic fracturing fractures" or "formation fractures" or "fractures" are interchangeable.

[0078] The "bottom-hole pressure" herein refers to the pressure at or near the starting depth of the hydraulic fracture (formation fracture) in the wellbore. When the friction loss can be ignored, the bottom-hole pressure is equal to the fracture pressure of the hydraulic fracture.

[0079] The term "wellbore" as used herein refers to a hole formed by drilling or inserting a conduit into the earth. Generally, a wellbore is cylindrical, so the cross-section of the wellbore may be circular. Alternatively, 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.

[0080] The "closed state" in this article refers to the state where the fracture pressure of the formation fracture is less than the "fracture closure pressure" or "closure pressure". For example, when exploiting artificial fractures / natural fractures in depleted crude oil and gas reservoirs, since there is no fluid or crude oil in the fractures, the artificial fractures / natural fractures are in a state of not continuing to close, not expanding, and not extending. Another example is the state where the formation fractures gradually close as the fluid is discharged during the backflow process.

[0081] The term "open" or "open state" used herein refers to a state in which a formation fracture originally in a "closed state" has a fracture pressure greater than the "fracture closure pressure" or "closure pressure" under the action of an external force (e.g., a high-pressure fluid). For example, a formation fracture originally in a closed state has a fracture pressure gradually increasing under the action of an external force (e.g., a high-pressure fluid), and a state in which the fracture pressure is greater than the expansion pressure, causing the fracture to expand along the original length and / or height direction.

[0082] The "width of a formation fracture" in this article refers to the relative displacement distance between the two walls in the direction perpendicular to the fracture surface. When the formation fracture is assumed to be circular (or in engineering practice, the formation fracture can be considered to be circular or approximately circular), the "expansion radius" of the formation fracture refers to the radius of the circle (see Figure 5A (indicated by the double-headed arrows).

[0083] "Constant" or "unchanged" in this article does not mean that the absolute change of the specified item is zero, but that the change of the specified item is very small, and the item can be considered to remain constant in engineering practice. For example, the term "unchanged bottom hole pressure" in this article also means "approximately constant bottom hole pressure", or, "unchanged expansion radius" in this article actually means that the "expansion radius" of the formation fracture is "basically unchanged" or "approximately constant" under the action of high-pressure fluid, or, "unchanged width of the formation fracture" in this article actually means that the "width of the formation fracture" is "basically unchanged" or "approximately constant" under the action of high-pressure fluid. It should also be recognized that the term "equal / equal to" used in this disclosure does not mean that the specified items are exactly the same, but is used to specify two items with negligible differences in engineering practice. For example, the term "equal / equal to" in this disclosure can also have the meaning of "approximately equal / equal to".

[0084] Prior art CN116545125A discloses a method and system for storing and releasing energy through existing formation fractures in the formation, which comprises the following steps: identifying at least one energy storage formation that does not contain oil and gas and has at least one original formation fracture; screening out at least one target formation fracture from the at least one formation fracture, wherein the at least one target formation fracture includes at least one target artificial fracture; using electric energy to drive an injection device to inject a high-pressure fluid into the at least one target formation fracture, so that the fracture width of the formation fracture increases to a target width, thereby converting the electric energy into elastic deformation energy of the formation rock for storage; and using the high-pressure fluid that is reversed during the closing process of the target formation fracture to drive a preset power generation device to generate electricity, thereby converting the elastic deformation energy of the formation rock into electric energy for energy release.

[0085] However, the above scheme does not involve the exploitation and utilization of geothermal energy. As mentioned earlier, traditional geothermal energy is often exploited by looking for faults with more developed natural fractures in the strata as targets, or by using multiple wells through multi-stage hydraulic fracturing technology. However, it is difficult to meet today's geothermal exploitation needs by relying solely on natural fractures, and excessive development of faults will also lead to geological safety problems; while the collection of geothermal energy through multi-stage hydraulic fracturing faces problems such as high investment and maintenance costs, easy flow short circuits, and low geothermal exploitation utilization. Embodiment 1: Shale is widely distributed and has extremely low permeability. In the field of oil and gas, shale formations are usually regarded as the overlying sealing layer of conventional oil and gas reservoirs, which can prevent oil and gas from migrating upward and volatilizing to the ground. At the same time, the shale formation itself can also be used as a storage medium for fluids, and due to the extremely low permeability of the shale formation, the high-pressure fluid in the internal formation cracks can be stored for a long time, and only a very small amount of fluid will be lost to the pores of the formation rock. For example, the Oak Ridge National Laboratory in the United States has injected radioactive fluid waste into the artificial formation cracks of the shale formation for decades to achieve the purpose of permanent preservation. Therefore, preferably, the present invention achieves the purpose of long-term energy storage by storing high-pressure fluid in the artificial cracks of porous and permeable shale formations (that is, the formation cracks formed by hydraulic fracturing construction), that is, the shale formation is used as an energy storage formation. Of course, the present invention can also be applied to other porous and permeable rock formations.

[0086] See also Figure 1A , is a flow chart of a method for storing and releasing energy and obtaining geothermal energy through existing original formation fractures in a formation according to an exemplary embodiment of the present invention. Specifically, the method comprises the steps of:

[0087] In step S100, at least one energy storage geothermal layer (ie, reservoir) having rich geothermal resources, no oil or gas, and having at least one original formation fracture is identified.

[0088] In some embodiments, the energy storage formation without oil and gas includes: depleted oil and gas formations that have been hydraulically fractured and exhausted. That is, the energy storage formation has at least one artificial fracture (e.g., a formation fracture formed by hydraulic fracturing), and the artificial fracture is currently in a closed state due to exhaustion.

[0089] Of course, in other embodiments, the energy storage stratum without oil and gas may also include: an energy storage stratum with at least one natural fracture. Of course, the energy storage stratum without oil and gas may have both at least one artificial fracture and at least one natural fracture.

[0090] In some embodiments, an intuitive method may be used to identify relevant information of the energy storage formation (preferably a shale formation) (e.g., burial depth and thickness of the formation), for example, by obtaining a core through drilling to identify the burial depth and thickness of the formation. In other embodiments, an indirect method may also be used to identify relevant information of the formation, for example, by interpreting logging / mud logging data and seismic data inversion.

[0091] In addition, by analyzing factors such as the thermal conductivity, temperature gradient and groundwater circulation of underground rocks, a "wellbore-fracture-formation" fluid-solid thermal coupling numerical model is established to simulate the dynamic changes of the wellbore outlet temperature and formation temperature during long-term operation. If the simulation shows that the wellbore outlet temperature can be maintained above the power generation temperature for a long time (the power generation temperature depends on the geothermal power generation technology used, such as dry steam power generation and flash evaporation power generation require the wellbore outlet temperature to be above 150 degrees Celsius, and binary cycle power generation requires the wellbore outlet temperature to be above 50 degrees Celsius), then the geothermal energy storage formation can directly provide electricity or heating and be marked. If the wellbore outlet temperature cannot be maintained above the power generation temperature for a long time, but can be maintained above the heating temperature (usually above 35 degrees Celsius), then the geothermal energy storage formation can only be used for heating and marked. That is, the geothermal energy storage formation is classified and marked by simulation through the above-mentioned fluid-solid thermal coupling numerical model.

[0092] In some embodiments, well logging methods and seismic information can be used to identify and predict natural and artificial fractures in the formation. For example, electromagnetic direction finders, CT scanners, micro-Lambda logging, annular acoustic logging, imaging logging (FMI), full-bore formation microresistivity imaging (FMI), DSI dipole shear wave imagers, microseismic monitoring and downhole television (BHTV), etc. These methods and equipment can measure the inclination, strike, width, apparent porosity, filling and opening degree of reservoir fractures, and even identify micro fractures and sub-micro fractures.

[0093] Of course, nonlinear theoretical methods can also detect and identify natural and artificial fractures in formations, such as fractal theory, neural networks and other technical methods. These methods can describe the distribution law and fractal dimension characteristics of fractures, as well as the connectivity of fracture networks.

[0094] Based on the analysis of tectonic stress, natural and artificial fractures in the formation can also be predicted, such as using the main curvature of the structural surface to study the fracture problems in oil and gas reservoirs, using a buckled thin plate to simulate the mechanical model of longitudinal bending folds, establishing an analytical calculation method for the ancient stress field of faults, and using numerical simulation methods to study the influence of tectonic stress fields on fracture development.

[0095] In step S102, at least one target artificial fracture is screened out from the at least one original formation fracture in step S100.

[0096] In some embodiments, various parameters of the formation fractures for energy storage are planned in advance according to energy storage requirements, such as the amount of energy storage (including fluid kinetic energy and thermal energy) and economic costs, such as target width, target length threshold, target height threshold and target number of fractures. Among them, the target length threshold and target height threshold can also be inferred from the required fluid kinetic energy and thermal energy carried by the fluid, and the target width of the existing formation fractures. Therefore, when the corresponding parameters of the identified artificial fractures reach the above-mentioned target values, it means that it meets the energy storage requirements. Therefore, high-pressure fluid can be directly injected into it to change its width (even if it is deformed) to store energy, otherwise, it does not meet the energy storage requirements.

[0097] Specifically, see Figure 2 , step S102 includes the steps of: acquiring first monitoring data of the artificial fractures identified in step S100 from the monitoring equipment; calculating the number of artificial fractures in the closed state in the energy storage formation, as well as the original length and original height of each artificial fracture, by combining the first monitoring data and the first construction parameters (for example, injection rate, wellhead and bottom hole pressure, etc.) acquired in advance through the fracture extension numerical model, and judging whether the original length and original height of each artificial fracture meet the preset target length threshold and target height threshold, and if so, marking it as the target artificial fracture, otherwise continue screening until all the target artificial fractures are screened out.

[0098] In some embodiments, as mentioned above, the first monitoring data is obtained by using various monitoring equipment: electromagnetic direction finder, CT scanner, micro-Lambda logging, annular acoustic logging, imaging logging (FMI), full-bore formation microresistivity imaging (FMI), DSI dipole shear wave imager, microseismic monitoring and downhole television (BHTV), etc. Specifically, it includes: the dip angle, strike, width, apparent porosity of artificial fractures in the formation, and the filling and opening degree of the fractures, etc.

[0099] In some embodiments, the first construction parameter includes injection rate and wellhead and bottom hole pressure. Generally, the first construction parameters of each artificial fracture in the formation can be acquired in advance.

[0100] In other embodiments, if the number of target artificial cracks finally screened out is less than a preset target artificial crack number threshold (usually, the target number of artificial cracks required to store the corresponding energy storage is pre-calculated based on the current energy storage demand, such as the energy storage capacity and economic cost, to obtain the target artificial crack number threshold, that is, the preset number threshold), artificial cracks that do not meet the preset target values ​​(for example, artificial cracks whose original length and / or original height do not meet the corresponding target length threshold and / or target height threshold), that is, the remaining artificial cracks that are not marked as target artificial cracks, can also be re-modified.

[0101] Specifically, the number of artificial fractures for secondary transformation may be the difference between the current target number of artificial fractures and a target threshold number of artificial fractures, or may be set according to the current target energy storage capacity.

[0102] Specifically, see Figure 3 The steps of performing secondary transformation on the artificial fracture specifically include: according to a preset third construction parameter, injecting a high-pressure fluid into the artificial fracture through a wellbore, so that the fracture pressure in the artificial fracture is greater than the fracture expansion pressure, so that the artificial fracture expands along its original height and original length; according to the preset third construction parameter and the third monitoring data obtained by real-time monitoring, combining the fracture expansion numerical model to calculate the latest length and the latest height of the artificial fracture after extending along the original height and original length; then judging whether the latest length and the latest height reach the preset target length threshold and the target height threshold, if so, stopping injecting the high-pressure fluid to obtain the target artificial fracture, otherwise continuing to inject the high-pressure fluid to extend it along the original height and original length, so that the artificial fracture is transformed into the target artificial fracture after secondary transformation, until the height and length of the target artificial fracture reach the preset target threshold.

[0103] In step S104, electric energy is used to drive the injection device to inject normal temperature and high pressure fluid into at least one target artificial fracture, so that the fracture width of at least one target artificial fracture increases to the target width, thereby converting the electric energy into elastic deformation energy of the formation rock for storage, and obtaining geothermal energy at the same time.

[0104] In some embodiments, the injection equipment uses an integrated power generation and water injection machine. When energy storage is needed, the integrated power generation and water injection machine can pressurize normal temperature fluid and input it into the wellbore to increase the width of the target formation fracture. When power generation is needed, the integrated power generation and water injection machine can convert the kinetic energy of the reversed fluid into electrical energy.

[0105] In some embodiments, step S104 specifically includes: injecting high-pressure fluid into the target artificial fracture according to a preset second construction parameter so that the fracture pressure gradually increases; real-time monitoring of the fracture pressure in the target artificial fracture, and determining whether the fracture pressure is greater than the closure stress (that is, the minimum principal stress or closure pressure of the formation); if so, adjusting the second construction parameter so that the fluid pressure injected into the target artificial fracture is greater than the closure pressure and less than the expansion pressure of the formation fracture; otherwise, continuing monitoring.

[0106] In some embodiments, since the target artificial fracture is originally in a closed state, the pressure of the fluid initially injected into the closed target artificial fracture is less than the closing stress. However, with the continuous injection of the fluid, the fracture pressure in the target artificial fracture will gradually increase and eventually exceed the closing pressure, so that the closed target artificial fracture becomes an open state, that is, the artificial fracture is opened.

[0107] In some embodiments, the second construction parameter includes: the injection rate and the total injection volume of the fluid. Specifically, the fluid pressure can be adjusted by adjusting the injection rate of the injection device or the amount of fluid injected, and the fluid pressure can be monitored by a pre-installed pressure monitoring device.

[0108] In some embodiments, fracture pressure may be monitored by a pre-installed pressure monitoring device, such as a pressure sensor.

[0109] In some embodiments, by adjusting the second construction parameter (for example, the injection rate and volume of the fluid, etc.), the pressure of the injected fluid is greater than the closing pressure of the formation and less than the expansion pressure of the target artificial fracture, so that the crack width of the target artificial fracture gradually increases, and the expansion radius remains unchanged or constant (since the fluid pressure is less than the expansion pressure of the formation fracture, the target artificial fracture will not expand, that is, the crack radius remains unchanged or constant, and its length and height will not change), thereby converting electrical energy into elastic deformation energy of the formation rock for storage.

[0110] Of course, in other embodiments, the expansion radius of the formation fracture / target artificial fracture remains unchanged or constant, which can be understood as remaining unchanged or constant for a period of time. For example, when the width of the target formation fracture changes due to the action of high-pressure fluid, its expansion radius will also gradually change (that is, continue to expand), but within a certain period of time (for example, one hour), the change in the expansion radius can be ignored in engineering practice; or, when the formation fracture expands due to the action of high-pressure fluid, after a certain period of time, the particles added to the high-pressure fluid will fill or partially fill the fracture that continues to expand.

[0111] Preferably, in some embodiments, the minimum principal stress of the energy storage formation can be obtained by a small-scale fracturing (Diagnostic Fracturing Injection Test) or a rapid injection-flowback test. The expansion pressure of the formation fracture can be obtained by analyzing the instantaneous shut-in pressure (Instantaneous Shut-In Pressure) of the pressure drop curve after the pump is stopped during hydraulic fracturing construction.

[0112] Specifically, in some embodiments, before injecting the normal temperature high pressure fluid into at least one target artificial fracture (i.e. before executing step S104), the method further includes the step of: setting at least one reservoir for storing the fluid underground or on the ground, wherein the reservoir is connected to the wellbore through a pipeline (e.g., a ground pipeline).

[0113] Preferably, in some embodiments, one or more additives may be added to the fluid in the reservoir in advance (that is, one or more additives may be added to the fluid injected into the formation fractures), for example, bactericides, descaling agents, mineral salts (such as KCl, NaCl, CaCl2, NaSiO4, etc.) and filtration control agents, wherein the mineral salts are used to balance the electrolytes in the energy storage formation.

[0114] When the water reservoir is disposed on the ground, preferably, in order to reduce the loss of the fluid, in some embodiments, the water reservoir is provided with a shielding structure for preventing the evaporation of the fluid, for example, a plastic or metal film is covered above the water reservoir.

[0115] S106, determining whether the width of at least one target artificial crack is equal to or greater than a preset target width, if so, executing step S108; otherwise, executing step S110;

[0116] S108, stop injecting normal temperature high pressure fluid into at least one target formation fracture, i.e. at least one target artificial fracture, so as to keep the bottom hole pressure unchanged or the change is negligible, so that the width of the target formation fracture remains unchanged or the change is negligible.

[0117] S110, continue to inject normal temperature and high pressure fluid into at least one target artificial fracture, and execute step S106.

[0118] In some embodiments, the width of the target artificial fracture is calculated based on the height of the target artificial fracture, the expansion radius of the target artificial fracture and the bottom hole pressure. It can be understood that the widths at different positions in the target artificial fracture are not equal. Preferably, in some embodiments, the "width of the target artificial fracture" in step S106 refers to the average width of all target artificial fractures; of course, in other embodiments, the "width of the target artificial fracture" in step S106 may also refer to the width of any target artificial fracture.

[0119] For example, in some embodiments, for the same wellbore, during the process of injecting normal temperature and high pressure fluid into each target artificial fracture, the width data of all target artificial fractures are obtained, and the widths of all target artificial fractures are averaged to obtain the average width of all target artificial fractures. When the average width is equal to or greater than the preset target width, power is stopped to the injection device so that the injection device stops injecting normal temperature and high pressure fluid into each target artificial fracture.

[0120] In some embodiments, the target width of the target artificial fracture is set in advance by professionals according to the mechanical properties of the energy storage formation and different energy storage requirements, so as to ensure that the target artificial fracture has a certain storage capacity while avoiding the damage to the energy storage formation caused by the excessive width of the target artificial fracture. It is understandable that, since there are multiple target artificial fractures, in order to avoid the damage to the energy storage formation caused by the excessive width of the target artificial fracture, preferably, when it is monitored (or determined) that there is a target artificial fracture with a width equal to or greater than the preset target width, the injection of normal temperature high pressure fluid into at least one target artificial fracture is stopped, so as to keep the bottom hole pressure unchanged or the change is small enough to be ignored, so that the fracture width remains unchanged or the change is small enough to be ignored.

[0121] Preferably, in some embodiments, one or more additives may be added to the fluid in the reservoir in advance (that is, one or more additives may be added to the fluid injected into the formation fractures), for example, bactericides, descaling agents, mineral salts (such as KCl, NaCl, CaCl2, NaSiO4, etc.) and filtration control agents, wherein the mineral salts are used to balance the electrolytes in the energy storage formation.

[0122] As a specific example Figure 5A As shown, the grid-powered injection device 500 injects the fluid in the reservoir 510 into the hydraulic fracture 590 (i.e., the target artificial fracture) in the shale formation 540 through the injection pipe 5200 to the wellbore 530, so that the width of the formation fracture expands, the rock around the fracture undergoes elastic deformation to store energy, and the surrounding rock heats the fluid in the fracture to obtain geothermal energy. Assume that the expansion radius of the circular fracture is 500m (the expansion radius is as follows Figure 5AThe average Young's modulus of the rock is 20 GPa, the fluid pressure in the fracture is 3 MPa higher than the minimum principal stress of the shale formation, and the formation temperature is 50 °C. According to fracture mechanics, the energy stored in the elastic deformation of the shale formation around the fracture is 2.8 × 10 11 J, that is, 78530 kw h. According to heat transfer theory, the available geothermal energy is 7.2×10 12 J, that is, 2019343kw·h.

[0123] S114, utilizing the high-temperature and high-pressure fluid discharged during the closing process of at least one target artificial fracture to drive a preset hydroelectric power generation device to generate electricity, thereby converting the elastic deformation energy of the formation rock into electrical energy for energy release.

[0124] In some embodiments, before executing step S114, step S112 is also included, monitoring whether there is a demand for power generation, and when it is monitored that there is a demand for power generation, step S114 is executed; otherwise, continue to monitor whether there is a demand for power generation.

[0125] Of course, in other embodiments, when it is monitored that the power supplied to the injection device 500 is insufficient (for example, weather changes cause insufficient supply of solar or wind power generation, specifically, when all or most of the solar and wind power generation is consumed by the end users of the power supply, and there is no excess power to supply the injection device), step S108 is executed to stop supplying power to the injection device 500, so that the injection device 500 stops injecting normal temperature high pressure fluid into at least one target artificial fracture, thereby maintaining the bottom hole pressure unchanged and the fracture width unchanged. Further, the power generation device is connected to the power grid, so that the power consumption equipment can be stably supplied.

[0126] S118, utilizing the high-temperature and high-pressure fluid that is reversed due to the closure of at least one target artificial fracture to drive a preset geothermal power generation device to generate electricity.

[0127] In some embodiments, before executing step S118, step S116 is also included to determine whether the high temperature and high pressure fluid meets the geothermal power generation requirements. If the geothermal power generation requirements are met, step S118 is executed; otherwise, continue to monitor whether there is a demand for power generation.

[0128] When the high-temperature and high-pressure fluid discharged during the closing of the target formation fractures drives the hydroelectric power generation equipment to generate electricity and still meets the geothermal power generation requirements (for example, the wellbore outlet temperature is greater than or equal to the power generation temperature required by the geothermal power generation equipment), the reverse discharge pipeline is opened to connect to the control valve on the geothermal power generation equipment, so that the high-temperature and high-pressure fluid discharged during the closing of the target formation fractures drives the geothermal power generation equipment to generate electricity.

[0129] In some other embodiments, when it is determined in step S116 that the high temperature and high pressure fluid does not meet the geothermal power generation requirements, the following steps are further included:

[0130] S120, determine whether the high temperature and high pressure fluid meets the heating requirements, if so, execute step S122, otherwise, discharge the high temperature and high pressure fluid into the water reservoir.

[0131] S122, connecting the high temperature and high pressure fluid to an external heating system for heating.

[0132] The water reservoir is connected to the wellbore corresponding to the formation fracture through a pipeline and a reverse discharge pipeline, and when the injection of normal temperature and high pressure fluid into the formation fracture stops, the reverse discharge pipeline and the injection pipeline are both in a closed state. Specifically, the control valves in the reverse discharge pipeline and the injection pipeline are in a closed state. Therefore, when it is detected that there is a demand for power generation, the control valve corresponding to the reverse discharge pipeline is opened to allow the reverse discharge pipeline to flow, so that the high temperature and high pressure fluid in the formation fracture can be reversed to the water reservoir through the reverse discharge pipeline under the action of rock compression, and the hydroelectric power generation equipment is driven during the reverse discharge process to convert the kinetic energy of the fluid into electrical energy. Specifically, see Figure 5A and Figure 5B The injection pipe 520 and the backflow pipe 570 connecting the water reservoir 510 and the wellbore 530 are both provided with control valves for controlling the circulation and closure of the ground pipes. When it is detected that power generation is required (for example, the corresponding control system, or the first power generation equipment, or the corresponding staff will receive a power supply request from the outside, such as the power grid or other control systems), the control system connected to the control valve, or the hydroelectric power generation equipment 550 and the geothermal power generation equipment 560 open the control valve corresponding to the backflow pipe 570 between the wellbore and the water reservoir (of course, it can also be opened manually by the staff), so that the wellbore 530 and the water reservoir are connected. The pools 510 are connected, and then under the effect of rock squeezing, the high-temperature and high-pressure fluid in the formation fractures 590 in the shale formation 540 is discharged back into the water storage tank 510. In this process, the high-temperature and high-pressure fluid first drives the impeller of the hydroelectric power generation equipment 550 to rotate to generate electricity. When passing through the geothermal power generation equipment 560, it is determined whether the high-temperature and high-pressure fluid meets the geothermal power generation requirements. If so, the geothermal power generation equipment 560 is turned on to generate electricity. If not, the geothermal power generation equipment 560 is not turned on, but the fluid is introduced into the heating system 580 for heating (for example, when it is detected that there is a heating demand and the fluid temperature reaches the heating demand).

[0133] Through the reciprocating cycle of steps S104-S118, the cyclic storage and release of electric energy can be realized and geothermal energy can be obtained for power generation. For example, during the day, excess solar power is stored as the elastic deformation energy of rocks around at least one target artificial fracture, and geothermal energy is obtained at the same time. When solar power generation is impossible at night, the elastic deformation energy of the energy storage stratum and the obtained geothermal energy are converted into electric energy and released to the power grid for power supply. Of course, the electric energy can also come from wind power generation or other power generation methods.

[0134] Of course, in other embodiments, if the high-temperature and high-pressure fluid discharged during the closing process of the target formation fracture drives the hydroelectric power generation equipment to generate electricity but does not meet the geothermal power generation requirements, but meets the heating requirements, if the heating requirements are monitored, it is determined whether the fluid temperature meets the heating requirements. Only when the fluid temperature meets the heating requirements, the fluid is heated to the heating system through the discharge pipe. Of course, it is understandable that the heated fluid can also be eventually discharged into the reservoir to achieve the recycling of the fluid.

[0135] Example 2: See Figure 1B , is a flow chart of a method for storing energy and obtaining thermal energy through existing original formation cracks in a formation according to another exemplary embodiment of the present invention. Specifically, the method includes the steps in the above-mentioned embodiment 1, except that, in step S102 of the method in this embodiment, at least one target natural crack is screened out from the energy storage formation, and correspondingly, in step S104, a normal temperature and high pressure fluid is injected into the target natural crack, so that the crack width of at least one target natural crack is increased, thereby converting electrical energy into elastic deformation energy of formation rock for storage, and obtaining geothermal energy at the same time; in step S106, it is judged whether the width of the target natural crack reaches a preset target width. If so, in step S108, injection of normal temperature and high pressure fluid into the natural crack is stopped, so as to keep the bottom hole pressure unchanged or change so small that it can be ignored, so that the width of the target formation crack is unchanged or changes so small that it can be ignored; in steps S114 and S118, the high temperature and high pressure fluid discharged during the closing process of the natural crack is used to drive the preset hydroelectric power generation equipment and geothermal power generation equipment to generate electricity, thereby converting the elastic deformation energy of the formation rock and the obtained geothermal energy into electrical energy for energy release.

[0136] In other embodiments, when it is determined that the high-temperature and high-pressure fluid discharged back does not meet the geothermal power generation requirements after driving the preset hydroelectric power generation equipment, it is determined whether it meets the heating requirements. If so, the high-temperature and high-pressure fluid is connected to the heating system for heating; otherwise, the high-temperature and high-pressure fluid is discharged into the water reservoir.

[0137] In some embodiments, the step of screening out at least one target natural fracture from at least one in-situ formation fracture in the energy storage formation specifically comprises:

[0138] Obtaining the distribution of the at least one natural fracture by inversion of well logging and seismic data;

[0139] Through structural stress analysis, the three-dimensional stress distribution of the energy storage formation is obtained;

[0140] Using a three-dimensional fracture-stress coupling model, simulating the opening of the at least one natural fracture during the process of injecting fluid into the at least one natural fracture, and calculating the energy storage capacity of the at least one natural fracture;

[0141] It is determined whether the energy storage capacity reaches the target energy storage capacity. If so, the corresponding natural fracture is marked as a target natural fracture.

[0142] Furthermore, when it is determined that the energy storage capacity of the at least one natural fracture does not reach the target energy storage capacity, the natural fracture may be transformed. Specifically, the step of transforming the natural fracture includes:

[0143] According to a preset fourth construction parameter, a normal temperature high pressure fluid is injected into the natural fracture through the wellbore, so that the fracture pressure in the natural fracture is greater than the fracture expansion pressure, thereby causing the natural fracture to expand along the original height and original length direction;

[0144] According to the fourth construction parameter and the real-time monitoring data, the latest length and the latest height of the natural fracture after extension are calculated using the numerical model of fracture extension; and it is determined whether the latest length and the latest height of the natural fracture after extension reach the preset target length threshold and the target height threshold. If so, stop injecting the normal temperature and high pressure fluid, otherwise continue injecting the normal temperature and high pressure fluid.

[0145] In practical applications, the degree of expansion of the natural fracture can be determined according to different energy storage requirements and the mechanical properties of the energy storage formation. For example, if more energy needs to be stored, a longer formation fracture needs to be designed. If relatively less energy needs to be stored, a shorter formation fracture needs to be designed. Therefore, the parameters of the target formation fracture, such as the target width, target length threshold, target height threshold and target fracture number threshold, can be set in advance according to actual needs. When it is determined that the identified natural fracture reaches the desired target threshold: the target length threshold and the target height threshold, normal temperature and high pressure fluid is directly injected into it to increase its width to the target width, thereby storing energy. Of course, if the identified natural fracture does not reach the desired target threshold, normal temperature and high pressure fluid can be injected into it for transformation, that is, it expands in height or length until it meets the corresponding target threshold (including the target length threshold, the target height threshold and the target fracture number threshold).

[0146] In some embodiments, the step of injecting a normal temperature and high pressure fluid into at least one target natural fracture using an injection device driven by electric energy specifically includes:

[0147] Injecting a normal temperature and high pressure fluid into the target natural fracture according to a preset second construction parameter, so that the fracture pressure in the target natural fracture gradually increases;

[0148] Real-time monitoring of the fracture pressure in the target natural fracture, and determining whether the fracture pressure is greater than the closing pressure, so that the closed target natural fracture becomes open;

[0149] If the fracture pressure is greater than the closing pressure, the second construction parameter is adjusted so that the fluid pressure injected into the target natural fracture is greater than the closing pressure and less than the expansion pressure of the target natural fracture, thereby gradually increasing the fracture width of the target natural fracture to the target width.

[0150] Of course, if the target natural fracture is obtained through transformation, since the natural fracture is currently in an open state, accordingly, when injecting normal temperature and high pressure fluid into the target natural fracture through the injection device, it is only necessary to make the pressure of the injected normal temperature and high pressure fluid greater than the closing pressure and less than the expansion pressure of the target natural fracture, so that the fracture width of the target natural fracture gradually increases to the target width.

[0151] Usually, during the process of injecting normal temperature high pressure fluid, during the energy storage process, and even during the reverse discharge process, due to the fluid loss, the electric energy obtained by the final reverse discharge may only have a loss of the target energy storage, for example, only 70%-80% of the target energy storage. Therefore, in order to reduce the low electric energy obtained by the final reverse discharge due to the loss as much as possible, the target length and / or target width and / or number of the target natural fracture / target artificial fracture can be increased. For example, while simulating and calculating the energy storage of the natural fracture, the fluid loss of the natural fracture can also be calculated, so as to calculate the number of the target natural fractures, the target length threshold and the target height threshold based on the fluid loss, energy storage, and the target energy storage.

[0152] Of course, in other embodiments, in order to reduce the rate at which high-pressure fluid in the formation fractures is lost to the surrounding rocks so that the formation fractures in the energy storage formation have the ability to store high-pressure fluid for a long time, a fluid loss preventer is added to the high-pressure fluid injected into the fractures.

[0153] Preferably, in some embodiments, the fluid loss agent may include: at least one high molecular polymer, and / or at least one resin, and / or at least one gel and other additives. After the fluid loss agent is injected into the formation fracture, it covers the surface of the formation fracture to form a cap layer with extremely low leakage rate. In addition, the fluid loss agent can also be particles with the effect of plugging the pores of the rock matrix of the energy storage formation, such as micro-nano materials. During the filtration process, the particles are filled into the pores of the rock matrix around the formation fracture, reducing the permeability of the energy storage formation and achieving a fluid loss prevention effect.

[0154] In some embodiments, the fluid loss control agent may include: at least one silicate, and / or at least one sulfate, and / or at least one phosphate, and / or at least one oxalate. Silicates, sulfates, phosphates, and oxalates may react with formation mineral cations to generate precipitates to plug the pores of the formation rock matrix.

[0155] Of course, in other embodiments, at least one target artificial fracture and at least one target natural fracture may be simultaneously selected from the existing original formation fractures in the formation for energy storage (and the order of identifying the target artificial fractures and the target natural fractures may be adjusted according to actual needs), and the number of target artificial fractures and target natural fractures, and the corresponding target threshold (for example, target width) are set according to the current energy storage demand; of course, if the data of the corresponding target artificial fractures and / or target natural fractures do not reach the respective preset target number thresholds, the existing artificial fractures may be reconstructed, and / or the natural fractures may be transformed, and the specific transformation method is the same as the corresponding transformation method in the above-mentioned embodiments one and two, which will not be repeated here.

[0156] Embodiment 3: Different from Embodiment 1, there are multiple wellbores in this embodiment, each of which is connected to the energy storage geothermal layer and the target formation fractures; it also includes a number of injection pipes and return pipes respectively matched with each wellbore, the injection pipes are connected to injection equipment, and the return pipes are connected to hydroelectric power generation equipment, geothermal power generation equipment and heating system.

[0157] At the same time, some of the multiple wellbores are performing the process of injecting fluid for secondary transformation, some are performing the process of storing energy, and some are performing the process of releasing energy.

[0158] Of course, the injection pipeline and the backflow pipeline in the process of injecting the normal temperature high pressure fluid can also be the same pipeline. The principle is the same and will not be repeated here.

[0159] In the case of multiple wells, if there is a demand for power generation, it is also possible to determine whether the well outlet temperature meets the requirements of the geothermal power generation equipment; and select at least one well whose outlet temperature meets the requirements of the geothermal power generation equipment to discharge fluid for power generation. The purpose of this step is to determine whether the fluid has accumulated enough geothermal heat to be used for geothermal generators to generate electricity.

[0160] Of course, in the case of only one wellbore, since power generation has the highest priority, this step can be ignored.

[0161] Specifically, the method for determining whether the wellbore outlet temperature meets the requirements of the geothermal power generation equipment includes:

[0162] The relationship between the wellbore closed heat storage time and the wellbore outlet temperature is simulated based on the fluid-solid-heat coupling numerical model.

[0163] According to the wellbore outlet temperature required for power generation (including hydropower generation and geothermal power generation) and / or heating demand, the required target closed heat storage time is calculated using the fluid-solid thermal coupling numerical model;

[0164] If the actual closed heat storage time of any wellbore reaches the corresponding target closed heat storage time, it is judged that the outlet temperature of the corresponding wellbore meets the requirements of the geothermal power generation equipment.

[0165] In addition, this step can also be applied to the coordinated work of multiple wellbores. When the power generation demand is higher than the power that a single wellbores can provide, this step can be used to select multiple wellbores that can work together to meet the power generation demand. Specifically, the required number of wellbores is calculated based on the required power generation demand.

[0166] See also Figure 7 This embodiment provides a system for realizing continuous energy storage and release and obtaining geothermal energy by utilizing existing formation fractures in an energy storage formation. Specifically, the energy storage formation includes depleted oil and gas wells that have completed production, for example, vertical wells 710, 720, 730, and horizontal wells 740, 750, and 760 (three horizontal wells or vertical wells are taken as an example in this case, but the number of multiple vertical wells and horizontal wells described in the present invention includes all cases where the number is greater than 1), and each vertical well and horizontal well has at least one formation fracture in a closed state. During the period of utilizing the formation for energy storage and release, vertical wells 710, vertical well 720, and vertical well 730 and horizontal wells 740, horizontal well 750, and horizontal well 760 cooperate with each other to realize continuous energy storage and release and obtain geothermal energy. For example, when vertical well 710 and horizontal well 740 are performing the injection process and converting electrical energy into formation elastic deformation energy, vertical well 720 and horizontal well 750 have completed the injection, so the electrical energy can be converted into formation elastic deformation energy for storage, and geothermal energy can be obtained at the same time. Vertical well 730 and horizontal well 760 are performing the reverse discharge process due to power generation needs, converting the stored formation elastic deformation energy and the obtained geothermal energy into electrical energy and putting them into the power grid for use. Then, the vertical well 730 and horizontal well 760 that have completed the energy release perform the injection process. After the injection is completed, the vertical well 720 and horizontal well 750 that are in the storage process perform the reverse discharge process to release energy. After the injection is completed, the vertical well 710 and horizontal well 740 are in the energy storage process and obtain geothermal energy. Taking this as an example, the vertical wells 710, 720, and 730 and the horizontal wells 740, 750, and 760 are cyclically coordinated to ensure that they can provide electrical energy to the power grid at any time to meet the electricity demand.

[0167] Embodiment 4: The present invention also provides a system for storing and releasing energy and obtaining geothermal energy through existing original formation fractures in the formation, see Figure 4 The system specifically includes:

[0168] The formation identification device 02 is used to identify at least one energy storage geothermal layer that has rich geothermal resources and does not contain oil and gas and has at least one original formation fracture; wherein the original formation fracture includes a natural fracture and / or an artificial fracture in a closed state;

[0169] The formation fracture screening device 04 is used to screen out at least one target formation fracture from at least one original formation fracture identified by the formation identification device 02; wherein the at least one target formation fracture includes at least one target artificial fracture and / or at least one target natural fracture;

[0170] Injection device 06, used to inject normal temperature and high pressure fluid into at least one target formation fracture, so that the fracture width of at least one target formation fracture increases to a target width, thereby converting electrical energy into elastic deformation energy of formation rock for storage and obtaining geothermal energy;

[0171] The power generation device 12 includes a hydroelectric power generation device and a geothermal power generation device, which is used to convert the elastic deformation energy of the formation rock and the acquired geothermal energy into electrical energy under the drive of the high-temperature and high-pressure fluid when the high-temperature and high-pressure fluid in the target formation fracture is reversed under the rock squeezing action during the closing process of the target formation fracture;

[0172] A backflow pipe is connected to the above-mentioned hydroelectric power generation equipment and geothermal power generation equipment. The fluid in the formation fracture is backflowed through the backflow pipe and drives the hydroelectric power generation equipment and / or geothermal power generation equipment to generate electricity. Preferably, the hydroelectric power generation equipment is driven to generate electricity first. After driving the hydroelectric power generation equipment to generate electricity, if the geothermal power generation demand is still met (for example, the temperature of the high-temperature and high-pressure fluid is detected by a temperature detection device, or whether the wellbore outlet temperature meets the heating temperature required by the geothermal generating equipment), the geothermal power generation equipment is driven to generate electricity. If the geothermal power generation demand is not met, it is determined whether it meets the heating demand. If it is met, the high-temperature and high-pressure fluid is connected to the heating system for heating. If it does not meet the heating demand, it is directly backflowed into the water storage tank.

[0173] The plugging device is used to close the backflow pipe so that the fluid in the formation fracture continues to exchange heat with the energy storage geothermal layer so that the fluid temperature continues to rise. Preferably, the plugging device is a control valve arranged on the backflow pipe. Of course, in order to prevent the fluid from flowing back from the injection pipe, the plugging device may also include a control valve arranged on the injection pipe.

[0174] In some embodiments, the system further includes: a water reservoir 14 connected to the injection device 06 for storing fluid.

[0175] Furthermore, in some embodiments, the water reservoir is connected to the wellbore corresponding to the original formation fracture through a reverse flow pipe, and a control valve for controlling the opening (i.e., flow) or closing (i.e., no flow) of the wellbore or the reverse flow pipe is provided in the wellbore or the reverse flow pipe. Accordingly, the system also includes: a (power generation demand) monitoring device, connected to the control valve, for monitoring whether there is a power generation demand. When a power generation demand is detected, a first control instruction indicating opening the control valve of the reverse flow pipe is generated and sent to the control valve to control the control valve to open, that is, to connect the water reservoir and the wellbore. Otherwise, the monitoring of whether there is a power generation demand continues.

[0176] Specifically, in some embodiments, the reverse discharge pipeline between the water reservoir and the wellbore is normally in a closed state / no flow state (specifically, the valve in the reverse discharge pipeline is normally in a closed state). When the power generation device 12 receives a first control instruction sent by the monitoring device indicating to open the control valve corresponding to the reverse discharge pipeline (for example, a control instruction from a power grid or other control system connected to the power generation device 12, or a control instruction issued by a staff member), the power generation device 12 will open the reverse discharge pipeline between the wellbore and the water reservoir (specifically, open the control valve corresponding to the reverse discharge pipeline), so that under the action of rock squeezing, the high-temperature and high-pressure fluid in the formation fracture is reversed into the water reservoir through the reverse discharge pipeline, and drives the hydraulic generator in the power generation device 12. The impeller of the electric device rotates to generate electricity, and then the judgment device judges whether the high-temperature and high-pressure fluid driven by the reverse discharge hydroelectric power generation equipment meets the geothermal power generation demand. If the geothermal power generation demand is met, a second control instruction indicating the opening of the geothermal power generation equipment is generated and sent to the geothermal power generation equipment, so that the geothermal power generation equipment in the power generation device 12 is driven to generate electricity. If the power generation device 12 does not receive the first control instruction indicating the opening of the control valve of the reverse discharge pipeline, the power generation device 12 always keeps the reverse discharge pipeline closed. At this time, the monitoring device continues to monitor whether there is a power supply demand. Of course, in other embodiments, the staff can judge whether there is a power supply demand and control the opening and closing of the valve in the injection / reverse discharge pipeline by the staff. In other embodiments, if it is judged that the geothermal power generation conditions are not met, the geothermal power generation equipment is closed, and further judgment is continued to determine whether the heating demand is met. When it is judged that the heating demand is met, the reverse high-temperature and high-pressure fluid is allowed to flow into the heating system for heating.

[0177] Specifically, see Figure 5A and Figure 5BThe injection pipe 520 and the backflow pipe 570 connecting the water reservoir 510 and the wellbore 530 are both provided with control valves for controlling the circulation and closure of the ground pipes. When it is detected that power generation is required (for example, the corresponding control system, or the first power generation equipment, or the corresponding staff will receive a power supply request from the outside, such as the power grid or other control systems), the control system connected to the control valve, or the hydroelectric power generation equipment 550 and the geothermal power generation equipment 560 open the control valve corresponding to the backflow pipe 570 between the wellbore and the water reservoir (of course, it can also be opened manually by the staff), so that the wellbore 530 and the water reservoir are connected. The pools 510 are connected, and then under the effect of rock squeezing, the high-temperature and high-pressure fluid in the formation fractures 590 in the shale formation 540 is discharged back into the water storage tank 510. In this process, the high-temperature and high-pressure fluid first drives the impeller of the hydroelectric power generation equipment 550 to rotate to generate electricity. When passing through the geothermal power generation equipment 560, it is determined whether the high-temperature and high-pressure fluid meets the geothermal power generation requirements. If so, the geothermal power generation equipment 560 is turned on to generate electricity. If not, the geothermal power generation equipment 560 is not turned on, but the fluid is introduced into the heating system 580 for heating (for example, when it is detected that there is a heating demand and the fluid temperature reaches the heating demand).

[0178] Of course, if no power supply request is received, the backflow pipe 570 between the wellbore and the reservoir will always remain closed, that is, the control valve on the backflow pipe 570 is in a normally closed state. At this time, continue to monitor whether there is a power supply demand.

[0179] It is understandable that even if there is a demand for power supply and / or heating, it is still necessary to determine whether the fluid in the formation fractures can meet the requirements for power generation and / or heating.

[0180] In some embodiments, the formation fracture screening device 04 specifically includes:

[0181] A monitoring device, used for monitoring the energy storage formation to obtain monitoring data of at least one original formation fracture existing in the energy storage formation; specifically, the monitoring data includes first monitoring data of the artificial fracture and / or second monitoring data of the natural fracture;

[0182] A data storage module, used for storing the first construction parameters of the artificial fractures existing in the energy storage formation acquired in advance;

[0183] A first calculation module is connected to the monitoring device and the data storage module, and is used to calculate the original length and original height of the artificial crack based on the crack extension numerical model combined with the first monitoring data and the first construction parameter;

[0184] The first control module is connected to the first calculation module and the injection device 06, and is used to determine whether the original length and original height of the artificial fracture meet the preset target length threshold and target height threshold. If so, the corresponding artificial fracture is marked as a target artificial fracture, and the injection device is triggered to inject high-pressure fluid into the target artificial fracture; or, when it is determined that the original length and original height of the artificial fracture reach the preset target length threshold and target height threshold, the injection device is triggered to inject high-pressure fluid into the target artificial fracture to perform secondary transformation on the artificial fracture. Of course, when the target artificial fracture is obtained by transformation, the first control module is also used to trigger the injection device to inject high-pressure fluid into the target artificial fracture for energy storage;

[0185] In some embodiments, the formation fracture screening device further comprises:

[0186] A second calculation module, configured to perform inversion on the well logging data and the seismic data to obtain the distribution of the at least one natural fracture;

[0187] A third calculation module is used to obtain the three-dimensional stress distribution of the energy storage formation through structural stress analysis;

[0188] A fourth calculation module is used to simulate the opening of the natural fracture during the process of injecting fluid into the natural fracture using a three-dimensional fracture-stress coupling model, and calculate the energy storage capacity of the natural fracture;

[0189] The second control module is used to determine whether the energy storage has reached the preset target energy storage. If so, the corresponding natural fracture is marked as a target natural fracture, and the injection device is triggered to inject high-pressure fluid into the target natural fracture; or, when it is determined that the energy storage has not reached the preset target energy storage, the injection device is triggered to transform the natural fracture. Of course, when the target natural fracture is obtained by transformation, the second control module is also used to trigger the injection device to inject normal temperature high-pressure fluid into the target natural fracture to store energy and obtain geothermal energy;

[0190] In some embodiments, the formation fracture screening device also includes: a second control device 10, connected to the injection device 06, for determining whether the width of at least one target formation fracture is equal to or greater than a preset target width. If so, a third control instruction indicating to stop injecting normal temperature and high pressure fluid is generated and sent to the injection device 06, so that the injection device 06 stops injecting normal temperature and high pressure fluid into at least one target formation fracture, so that the width of the target formation fracture remains unchanged.

[0191] In some embodiments, the second control device 10 is also used to monitor whether the power supply of the injection device 06 is sufficient. If not, a third control instruction indicating to stop injecting normal temperature and high pressure fluid is generated and sent to the injection device 06, so that the injection device 06 stops injecting normal temperature and high pressure fluid into at least one target formation fracture, so that the width of the target formation fracture remains unchanged.

[0192] Specifically, in some embodiments, the injection device 06 is installed in an injection pipeline (i.e., a pipeline connecting the water reservoir and the wellbore and for fluid injection). When the injection device 06 stops injecting normal temperature and high pressure fluid into at least one formation fracture, the injection device 06 puts the injection pipeline into a closed state / non-circulating state. Specifically, the injection device 06 closes the valve in the injection pipeline.

[0193] In some embodiments, the injection device 06 comprises:

[0194] A fluid injection module 062, used to inject a normal temperature and high pressure fluid into at least one formation fracture;

[0195] A pressure monitoring module 064, used for real-time monitoring of the pressure of the injected fluid;

[0196] The pressure judgment module 066 is connected to the fluid injection module 062 and the pressure monitoring module 064, and is used to judge whether the pressure of the injected fluid is greater than the closing pressure of the energy storage formation and less than the expansion pressure of the formation fracture. If so, the pressure judgment module 066 has no operation; otherwise, the pressure judgment module 066 generates a fourth control instruction indicating adjustment of the second construction parameter (i.e., the working parameter of the fluid injection module 062), and sends it to the fluid injection module 062 to control the fluid injection module 062 to adjust the second construction parameter so that the current fluid pressure is always maintained between the fracture expansion pressure and the closing pressure of the energy storage formation.

[0197] In some embodiments, the pressure judgment module 066 is also used to determine whether the internal crack pressure of the natural crack / artificial crack is greater than the crack expansion pressure during the transformation of the natural crack / artificial crack. If so, the pressure judgment module 066 does not operate; otherwise, the pressure judgment module 066 generates a fifth control instruction indicating the adjustment of the third construction parameter / fourth construction parameter (i.e., the working parameter of the fluid injection module 062), and sends it to the fluid injection module 062 to control the fluid injection module 062 to adjust the third construction parameter / fourth construction parameter so that the internal crack pressure of the natural crack / artificial crack is greater than the crack expansion pressure, thereby achieving the expansion of the natural crack / artificial crack along the original height and original length direction.

[0198] In some embodiments, the second control device 10 is also used to monitor the injection device according to the fourth construction parameter and the fourth monitoring data monitored in real time by the monitoring equipment, and use the numerical model of crack extension to calculate the latest length and the latest height of the natural crack after extension, or use the numerical model of crack extension to calculate the latest length and the latest height of the artificial crack after extension according to the third construction parameter and the third monitoring data monitored in real time by the monitoring equipment; and to determine whether the latest length and the latest height of the natural crack / artificial crack have reached the preset target length threshold and the target height threshold, and when it is determined that the latest length and the latest height have reached the preset target length threshold and the target height threshold, control the injection module to stop injecting fluid.

[0199] In other embodiments, in order to simplify the equipment, the difference is that the injection pipeline and the backflow pipeline in this embodiment are the same pipeline; the hydraulic generator and the injection equipment are an integrated power generation and water injection machine. When energy storage is needed, the integrated power generation and water injection machine can pressurize the normal temperature fluid and input it into the wellbore to increase the width of the formation fracture. When power generation is needed, the integrated power generation and water injection machine can convert the kinetic energy of the backflow fluid into electrical energy.

[0200] The so-called integrated power generation and water injection machine is a device with water pumping and power generation functions. It can pump water or convert the kinetic energy of water into electrical energy by forward and reverse rotation. Specifically, it can be an electric generator, a motor with both the functions of a generator and an electric motor. It can be used as a generator driven by a water turbine to generate electricity, and it can also be converted into an electric motor to drive a water pump to pump water.

[0201] See Fig. 6A and Figure 6B After the integrated power generation and water injection machine 610 stops injecting normal temperature and high pressure fluid into at least one formation fracture, the valve in the pipeline 640 between the wellbore 650 and the water reservoir 630 is also in a closed state. When it is monitored that power generation is required, the control valve corresponding to the pipeline 640 between the wellbore 650 and the water reservoir 630 is opened. At this time, under the action of rock squeezing, the high temperature and high pressure fluid heated by the formation in the formation fracture 670 in the shale formation 660 is discharged back into the water reservoir 630 through the pipeline 640. In this process, the impeller of the integrated power generation and water injection machine 610 is first driven to rotate to generate electricity, and then passes through the geothermal power generation equipment 620. At this time, if it is determined that the high temperature and high pressure fluid meets the geothermal power generation conditions, the geothermal power generation equipment 620 is driven to generate electricity, otherwise the geothermal power generation equipment 620 remains in a closed state, and it is determined whether there is a heating demand. If there is a heating demand, the fluid is introduced into the heating system 680, otherwise it flows back to the water reservoir. If no power demand is detected, the pipeline 640 between the wellbore 650 and the water reservoir 630 remains closed at all times.

[0202] The present invention also provides a non-temporary computer program product, in which a computer program is stored. When the computer program is executed by a processor, the device where the computer program product is located is controlled to execute the steps of the method described in Example 1.

[0203] 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.

[0204] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, a magnetic disk, or an optical disk), and includes a number of instructions for a computer terminal (which can be a mobile phone, a computer, a server, or a network device, etc.) to execute the methods described in each embodiment of the present invention.

[0205] 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 energy and obtaining geothermal energy through existing original formation cracks in the formation, characterized in that: Includes steps: Identifying at least one geothermal reservoir layer that is rich in geothermal resources and does not contain oil or gas and has at least one original formation fracture; Screening at least one target formation fracture from the at least one original formation fracture; Injecting a normal temperature and high pressure fluid into the at least one target formation fracture using an injection device, so that the fracture width of the target formation fracture increases to a target width, thereby converting electrical energy into elastic deformation energy of the formation rock for storage, and at the same time, the high pressure fluid in the target formation fracture exchanges heat with the energy storage geothermal layer to increase the fluid temperature; The high-temperature and high-pressure fluid discharged during the closing process of the target formation fracture is used to drive the preset hydroelectric power generation equipment and geothermal power generation equipment to generate electricity, thereby converting the acquired geothermal energy and the elastic deformation energy of the formation rock into electrical energy for energy release; The step of using the high-temperature and high-pressure fluid discharged during the closing process of the target formation fracture to drive the preset hydroelectric power generation equipment and geothermal power generation equipment to generate electricity specifically includes: monitoring whether there is a demand for power generation, and when it is detected that there is a demand for power generation, opening a control valve on a backflow pipeline connected to a wellbore corresponding to the target formation fracture, so that the high-temperature and high-pressure fluid in the target formation fracture is backflowed through the backflow pipeline and drives the hydroelectric power generation equipment to generate electricity; otherwise, continuing to monitor whether there is a demand for power generation; Determine whether the high-temperature and high-pressure fluid discharged during the closing process of the target formation fracture drives the hydroelectric power generation equipment to generate electricity after meeting the geothermal power generation conditions. If so, start the geothermal power generation equipment so that the high-temperature and high-pressure fluid discharged during the closing process of the target formation fracture drives the geothermal power generation equipment to generate electricity. If the geothermal power generation conditions are not met, determine whether the high-temperature and high-pressure fluid meets the heating demand. If so, connect the high-temperature and high-pressure fluid to the heating system. If not, discharge the high-temperature and high-pressure fluid into a preset water reservoir.

2. A method for storing energy and obtaining geothermal energy through existing original formation cracks in the formation according to claim 1, characterized in that: Before utilizing the high-temperature and high-pressure fluid discharged during the closure of the formation fractures to drive the preset geothermal power generation equipment to generate electricity, the wellbore, the discharge pipe and the hydroelectric power generation equipment are all subjected to heat insulation treatment.

3. The method for storing energy and obtaining geothermal energy through original formation fractures in the formation according to claim 1, characterized in that: The step of identifying the energy storage geothermal layer specifically includes: According to the thermal conductivity, temperature gradient and groundwater circulation of underground rocks, a fluid-solid-thermal coupling numerical model of "wellbore-fracture-formation" is constructed; When the wellbore outlet temperature can reach above the power generation temperature based on the simulation of the fluid-solid thermal coupling numerical model, the energy storage geothermal layer is marked as being capable of directly supplying electricity and / or heating; When the wellbore outlet temperature simulated based on the fluid-solid thermal coupling numerical model does not reach the power generation temperature but meets the heating demand, the energy storage geothermal layer is marked as available for heating.

4. A method for storing energy and obtaining geothermal energy through original formation fractures in the formation according to claim 3, characterized in that: When there are multiple wells, if there is a demand for power generation, determine whether the outlet temperature of each well in the energy storage geothermal layer marked as being able to directly supply electricity and / or heat meets the requirements of the geothermal power generation equipment, and select the well whose outlet temperature meets the requirements of the geothermal power generation equipment to reversely discharge the high-temperature and high-pressure fluid for power generation; The step of judging whether the wellbore outlet temperature meets the requirement of the geothermal power generation equipment specifically includes: The relationship between the wellbore closed heat storage time and the wellbore outlet temperature is simulated based on the fluid-solid-heat coupling numerical model. According to the wellbore outlet temperature required for power generation, the required target closed heat storage time is calculated using the fluid-solid-heat coupling numerical model; The closed heat storage time of each wellbore after the reverse discharge pipeline is closed is timed, and it is determined whether the closed heat storage time of each wellbore is greater than or equal to the corresponding target closed heat storage time. If so, it is determined that the outlet temperature of the corresponding wellbore meets the requirements of the geothermal power generation equipment.

5. The method for storing energy and obtaining geothermal energy through original stratum fractures according to claim 1, characterized in that: The original formation fractures include artificial fractures, the at least one target formation fracture includes at least one target artificial fracture, and the step of screening out at least one target artificial fracture from the at least one original formation fracture specifically includes the steps of: Acquiring first monitoring data of artificial fractures in the energy storage formation using a preset monitoring device; Calculate the original length and original height of the artificial fracture in the energy storage formation by combining the first monitoring data and the first construction parameter of the artificial fracture acquired in advance through the fracture extension numerical model; Determine whether the original length and the original height of the artificial crack reach a preset target length threshold and a target height threshold, and if so, mark the artificial crack as the target artificial crack; and / or, The original formation fracture includes a natural fracture in a closed state. Accordingly, the at least one target formation fracture includes at least one target natural fracture. The step of screening out at least one target natural fracture from the at least one original formation fracture specifically includes the steps of: Acquire second monitoring data of the natural fractures in the energy storage geothermal layer through a preset monitoring device, and perform inversion based on the second monitoring data to obtain the distribution of the at least one natural fracture; The second monitoring data includes: well logging data and seismic data; By analyzing the structural stress, the three-dimensional stress distribution of the energy storage geothermal layer is obtained; Using a three-dimensional fracture-stress coupling model, simulating the opening of the at least one natural fracture during the process of injecting a normal temperature and high pressure fluid into the at least one natural fracture, and calculating the energy storage amount when the width of the at least one natural fracture expands to a target width under the action of the normal temperature and high pressure fluid; It is determined whether the energy storage capacity reaches a preset target energy storage capacity, and if so, the at least one natural fracture is marked as a target natural fracture.

6. A method for storing energy and obtaining geothermal energy through original stratum fractures according to claim 5, characterized in that: Also includes the steps: Determine whether the number of the target artificial cracks reaches a preset number threshold; if not, perform secondary transformation on the artificial cracks whose original length and original height do not meet the preset target length threshold and target height threshold. Specifically, the step of performing secondary transformation on the artificial cracks includes: According to a preset third construction parameter, injecting fluid into the artificial fracture through the wellbore, so that the fracture pressure in the artificial fracture is greater than the fracture expansion pressure, so that the artificial fracture expands along its original height and original length direction; Acquiring third monitoring data during the expansion of the artificial fracture by means of the monitoring device; According to the third construction parameter and the third monitoring data, in combination with the crack extension numerical model, the latest length and the latest height of the artificial crack after extending along the original height and the original length are calculated; Determine whether the latest length and the latest height reach the target length threshold and the target height threshold, and if so, stop injecting the normal temperature and high pressure fluid to obtain the target artificial fracture; The target length threshold and the target height threshold are pre-deduced based on the required fluid kinetic energy and thermal energy carried by the fluid, as well as the target width of the existing formation fractures.

7. The method for storing energy and obtaining geothermal energy through original formation fractures in the formation according to claim 5, characterized in that: Also includes the steps: When it is determined that the energy storage capacity does not reach the preset target energy storage capacity, injecting fluid into the natural fracture through the wellbore according to a preset fourth construction parameter, so that the fracture pressure in the natural fracture is greater than the fracture expansion pressure, thereby causing the natural fracture to expand along the original height and original length direction; Acquire fourth monitoring data during the extension of the natural fracture through the monitoring device; calculate the latest length and the latest height of the natural fracture after extension using a numerical model of fracture extension according to the fourth construction parameter and the fourth monitoring data; Determine whether the latest delayed length and the latest height of the natural fracture reach a preset target length threshold and a target height threshold, and if so, stop injecting fluid to obtain the target natural fracture; The target length threshold and the target height threshold are pre-deduced based on the required fluid kinetic energy and thermal energy carried by the fluid, as well as the target width of the existing formation fractures.

8. A method for storing energy and obtaining geothermal energy through existing original formation fractures in the formation according to any one of claims 5 to 7, characterized in that: The step of injecting a normal temperature and high pressure fluid into the at least one target formation fracture using an injection device specifically comprises: injecting a normal temperature and high pressure fluid into the target formation fracture according to a preset second construction parameter, so that the fracture pressure in the target formation fracture gradually increases; the target formation fracture includes at least one of the artificial fractures and / or at least one of the target natural fractures; real-time monitoring of the fracture pressure in the target formation fracture, and determining whether the fracture pressure is greater than the closing pressure, so that the closed state of the target formation fracture becomes an open state; If the fracture pressure is greater than the closing pressure, adjusting the second construction parameter so that the pressure of the fluid injected into the target formation fracture is greater than the closing pressure and less than the expansion pressure of the target formation fracture, so that the fracture width of the target formation fracture gradually increases; Determine whether the width of at least one of the target formation fractures is equal to or greater than a preset target width. If so, stop supplying electrical energy to the injection device so that the injection device stops injecting the normal temperature and high pressure fluid into the at least one target formation fracture.

9. A system for storing energy and obtaining geothermal energy through existing original formation cracks in the formation, characterized in that: include: A formation identification device, used to identify at least one energy storage geothermal layer having rich geothermal resources and no oil or gas and having at least one original formation fracture; The at least one original formation fracture comprises a natural fracture in a closed state, and / or an artificial fracture in a closed state; A formation fracture screening device, used for screening out at least one target formation fracture from at least one original formation fracture identified by the formation identification device, wherein the at least one target formation fracture includes at least one target artificial fracture and / or at least one target natural fracture; An injection device is used to inject a normal temperature and high pressure fluid into the at least one target formation fracture, so that the fracture width of the at least one target formation fracture increases to a target width, thereby converting electrical energy into elastic deformation energy of the formation rock for storage, and at the same time, after the normal temperature and high pressure fluid is injected into the target formation fracture, heat is exchanged with the formation to increase the temperature; A hydroelectric power generation device, used for converting elastic deformation energy of the formation rock into electrical energy driven by the high-temperature and high-pressure fluid when the high-temperature and high-pressure fluid in the target formation fracture is reversed under the rock squeezing action during the closing process of the target formation fracture; Geothermal power generation equipment, used for converting the obtained geothermal energy into electrical energy under the drive of the high-temperature and high-pressure fluid in the target formation fractures after the high-temperature and high-pressure fluid in the target formation fractures is reversed under the rock compression during the closing process of the target formation fractures and drives the hydroelectric power generation device to generate electricity; A backflow pipeline is connected to the hydroelectric power generation equipment and the geothermal power generation equipment and is externally connected to a heating system. When the high-temperature and high-pressure fluid in the target formation fracture is backflowed through the backflow pipeline, the hydroelectric power generation equipment and the geothermal power generation equipment are driven to generate electricity and / or the heating system is used to provide heating; The plugging device is used to close the backflow pipeline so that the fluid in the target formation fracture continues to exchange heat with the energy storage geothermal layer so that the fluid temperature continues to rise.

10. A system for storing energy and obtaining geothermal energy through original stratum fractures according to claim 9, characterized in that: Also includes: A water reservoir for storing the normal temperature and high pressure fluid, wherein the water reservoir is connected to the wellbore corresponding to the target formation fracture through the reverse flow pipeline, and a control valve is provided in the reverse flow pipeline; A monitoring device is connected to the control valve and is used to monitor whether there is a demand for power generation. When a demand for power generation is detected, a first control instruction indicating opening the control valve is generated and sent to the control valve, so that the wellbore is connected to the water reservoir through the backflow pipeline; otherwise, the monitoring device continues to monitor whether there is a demand for power generation. A judgment device is connected to the control valve, and is used to judge whether the high-temperature and high-pressure fluid discharged during the closing process of the target formation fracture drives the hydroelectric power generation equipment to generate electricity, and whether the geothermal power generation conditions are met. When the geothermal power generation conditions are met, a second control instruction indicating the start of the geothermal power generation equipment is generated and sent to the geothermal power generation equipment, so that the geothermal power generation equipment generates electricity under the drive of the high-temperature and high-pressure fluid; otherwise, it continues to judge whether the heating demand is met, and when it is judged that the heating demand is met, the high-temperature and high-pressure fluid that is discharged is allowed to flow into the heating system for heating.

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