CN114016988A

CN114016988A - Method and system for storing and releasing energy through formation

Info

Publication number: CN114016988A
Application number: CN202111292888.7A
Authority: CN
Inventors: 王瀚艺
Original assignee: Individual
Current assignee: Shaoxing Far West Energy Technology Co ltd
Priority date: 2021-11-03
Filing date: 2021-11-03
Publication date: 2022-02-08

Abstract

The invention relates to a method for storing and releasing energy through a formation, comprising the steps of: identifying at least one hydrocarbon-free energy storage formation; performing hydraulic fracturing construction on the energy storage stratum to enable the energy storage stratum to generate at least one stratum fracture; the method comprises the steps that high-pressure fluid is injected into at least one stratum fracture by utilizing electric energy to drive injection equipment, so that the width of the at least one stratum fracture is increased, and electric energy is converted into elastic deformation energy of stratum rock to be stored; high-pressure fluid in the cracks is reversely discharged to the ground to drive an impeller of power generation equipment to rotate for power generation in the closing process of at least one stratum crack, so that elastic deformation energy of rocks stored in the stratum is converted into electric energy again. The energy storage method has lower investment and maintenance cost, can adapt to different surface terrains, and has wider application range.

Description

Method and system for storing and releasing energy through formation

Technical Field

The invention relates to the field of underground energy storage, in particular to a method and a system for storing and releasing energy through stratum.

Background

Many renewable energy sources such as solar energy and wind energy have daily and seasonal intermittency, the power output is unstable, and the renewable energy sources are not suitable for providing a basic load power supply, so that the renewable energy sources are difficult to directly enter a power grid, and the key point for successfully expanding the production scale of the renewable energy sources is to solve the problem of energy storage. Therefore, how to store surplus clean power on a large scale and stably transmit power when both sunlight and wind power are insufficient remains a technical problem in various countries.

Currently, large-scale power storage methods include the use of lead-acid batteries, lithium ion batteries, hydrogen fuel cells, compressed air energy storage, and pumped water energy storage. The lead-acid battery, the lithium ion battery and the hydrogen fuel battery store energy, and are not used in large scale due to higher investment and maintenance cost; the water pumping and energy storage is to pump water from a lower position to a higher position of the terrain and convert electric energy into gravitational potential energy of the water, so that the water pumping and energy storage method has certain requirements on the terrain structure and cannot be applied to plains or hilly areas with relatively flat terrain; compressed air energy storage is a mature energy storage technology, but a waste mine or an underground cave is required to be used as an air storage medium, so that the compressed air energy storage can be used only in certain specific areas.

In view of the foregoing, there is a need for a new clean electrical power storage and energy release method that is relatively low in investment and maintenance costs and adaptable to a variety of terrain.

Disclosure of Invention

The invention aims to provide a method and a system for storing and releasing energy through stratum, which partially solve or relieve the defects in the prior art, and have the advantages of low investment and maintenance cost and wide application range.

In order to solve the above mentioned technical problems, the present invention specifically adopts the following technical solutions:

in order to partially solve the technical problem, a first aspect of the present invention provides a method for storing and releasing energy through a formation, comprising the steps of:

identifying at least one hydrocarbon-free energy storage formation;

performing hydraulic fracturing construction on the energy storage stratum, so that at least one stratum fracture is generated in the energy storage stratum;

injecting high-pressure fluid into the at least one stratum fracture by using electric energy to drive injection equipment, so that the width of the stratum fracture is increased, and the electric energy is converted into elastic deformation energy of stratum rock to be stored;

and driving preset power generation equipment to generate power by using the high-pressure fluid reversely discharged in the closing process of the formation fracture, so that the elastic deformation energy of the formation rock is converted into electric energy to release energy.

In some embodiments of the invention, a fluid loss additive is included in the fracturing fluid in the hydraulic fracturing construction.

In some embodiments of the invention, the fluid loss additive comprises: at least one high molecular polymer, and/or at least one resin, and/or at least one quartz sand, and/or at least one gel, and/or at least one silicate, and/or at least one sulphate, and/or at least one phosphate, and/or at least one oxalate, and/or at least one particle having the effect of plugging the pores of the rock matrix of the formation.

In some embodiments of the invention, prior to the step of injecting the high pressure fluid into the at least one formation fracture, the method further comprises the steps of:

calculating to obtain a three-dimensional body of the stratum fracture according to a hydraulic fracturing model, rock mechanical properties and first construction parameters, and obtaining an expansion radius of the stratum fracture according to the three-dimensional body;

and judging whether the expansion radius is equal to or larger than the target radius or not, and stopping hydraulic fracturing construction when the expansion radius of the stratum fracture is equal to or larger than the target radius.

In some embodiments of the invention, the pressure of the fluid injected into the at least one formation fracture is greater than the minimum principal stress of the formation and less than the propagation pressure of the formation fracture, such that the width of the formation fracture progressively increases.

In some embodiments of the present invention, before the high-pressure fluid reversely discharged during the closing process of the formation fracture is used for driving a preset power generation device to generate power, the method further comprises the following steps:

and judging whether the width of at least one stratum fracture is equal to or larger than a preset target width, if so, stopping providing electric energy to the injection equipment so as to enable the injection equipment to stop injecting the high-pressure fluid into the at least one stratum fracture.

In some embodiments of the invention, prior to injecting the high pressure fluid into the at least one formation fracture, the method further comprises the steps of: at least one reservoir is provided underground or at the surface for storing the fluid.

In some embodiments of the present invention, the step of driving a preset power generation device to generate power by using the high-pressure fluid reversely discharged in the formation fracture closure process specifically includes the steps of:

monitoring whether a power generation requirement exists or not, and when the power generation requirement is monitored, opening a control valve on a reverse drainage pipeline which is communicated with the ground through a shaft corresponding to the formation fracture, so that the high-pressure fluid in the formation fracture is reversely drained to the ground through the reverse drainage pipeline, and driving the power generation equipment to generate power; otherwise, whether the power generation is required or not is continuously monitored.

In some embodiments of the invention, the high pressure fluid comprises: a bactericide, and/or a detergent, and/or a mineral salt, and/or a fluid loss additive.

In a second aspect, the present invention also provides a system for storing and releasing energy through a formation, comprising:

the stratum identification device is used for identifying at least one oil-gas-free energy storage stratum;

the hydraulic fracturing construction device is used for carrying out hydraulic fracturing construction on the energy storage stratum so that at least one stratum fracture is generated in the energy storage stratum;

the injection device is used for injecting high-pressure fluid into the at least one formation fracture to enable the width of the at least one formation fracture to be increased, so that electric energy is converted into formation rock elastic deformation energy to be stored;

and the power generation device is used for converting the elastic deformation energy of the formation rock into electric energy under the driving of the high-pressure fluid when the high-pressure fluid in the formation fracture is reversely discharged under the rock extrusion effect in the closing process of the formation fracture.

In some embodiments of the invention, the system further comprises:

the reservoir is used for storing the high-pressure fluid, the reservoir is connected with a shaft corresponding to the formation fracture through a reverse drainage pipeline, and a control valve is arranged in the shaft or the reverse drainage pipeline;

the monitoring device is connected with the control valve and used for monitoring whether power generation is required currently or not, and when the power generation is required, a first control instruction for opening the control valve is generated and sent to the control valve, so that the shaft is communicated with the reservoir through the inverted pipeline; otherwise, whether the power generation is required or not is continuously monitored.

Advantageous effects

The method comprises the steps of identifying at least one oil-gas-free energy storage stratum, and then performing hydraulic fracturing construction on the identified energy storage stratum to generate at least one stratum fracture in the energy storage stratum; and then, the high-pressure fluid is injected into the formation cracks by utilizing the electric energy to drive the injection equipment, so that the width of the formation cracks is increased, the electric energy is converted into the elastic deformation energy of the formation rock to be stored, and the energy storage with low investment and low maintenance cost is realized. Wherein, the electric energy in the steps is derived from renewable energy sources such as wind power generation, solar power generation and the like.

Further, in the process of gradually closing the stratum fracture, due to the squeezing effect of stratum rocks, high-pressure fluid in the fracture is reversely discharged to the ground to drive preset power generation equipment to generate power, namely, elastic deformation energy of the stratum fracture is converted into electric energy, and therefore stable power supply is achieved under the condition that solar energy or wind energy is insufficient.

The method and the system can convert the electric energy generated by sunshine or wind power into rock elastic deformation energy for storage when the sunshine or the wind power is sufficient, and release the electric energy to a power grid when needed, thereby having great significance for grid-connected peak regulation of wind power generation or solar power generation.

The invention can be applied to underground porous and permeable rock stratums, such as shale stratums, carbonate stratums, sandstone stratums and the like, wherein the shale has wide distribution range and multiple types and deposits in continental facies and marine facies basins, so that the shale stratums are used as energy storage stratums and have wide applicable regions and are not restricted by surface topography conditions; on the other hand, because the permeability of the shale formation is extremely low, when high-pressure fluid is stored in the formation fracture, only a very small amount of high-pressure fluid can be filtered and lost into the formation rock pore, namely, the shale formation can store the high-pressure fluid in the formation fracture for a long time, namely, the shale formation has higher energy storage efficiency; in addition, the method can be used for shale strata which is buried deep and does not contain oil gas, the construction difficulty is small, and the investment and maintenance cost is low.

The method disclosed by the invention also relates to a hydraulic fracturing method, which is used on a large scale as a mature technology in the field of petroleum and natural gas, so that related construction supporting equipment is easy to obtain and the cost is controllable.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. Throughout the drawings, like elements or portions are generally identified by like reference numerals. In the drawings, elements or portions are not necessarily drawn to scale. It is obvious that the drawings in the following description are some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive exercise.

FIG. 1 is a schematic flow diagram of a method for storing and releasing energy through a formation in an exemplary embodiment of the invention;

FIG. 2 is a schematic diagram of a system for hydraulic fracturing of vertical and horizontal wells;

FIG. 3A is a schematic illustration of an electrically powered injection apparatus injecting fluid from a reservoir into a formation fracture in a shale formation in accordance with an exemplary embodiment of the present invention;

FIG. 3B is a schematic illustration of the reverse discharge of high pressure fluid within a formation fracture to a reservoir and driving a power plant to generate power in an exemplary embodiment of the invention;

FIG. 4A is a schematic illustration of an electrically powered injection apparatus injecting fluid from a reservoir into a formation fracture in a shale formation in another exemplary embodiment of the invention;

FIG. 4B is a schematic illustration of the reverse discharge of high pressure fluid from a formation fracture to a reservoir and driving a power plant to generate power in another exemplary embodiment of the invention;

FIG. 5 is a schematic illustration of an apparatus for a system for storing and releasing energy through a formation in an exemplary embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Herein, suffixes such as "module", "part", or "unit" used to denote elements are used only for facilitating the description of the present invention, and have no specific meaning in itself. Thus, "module", "component" or "unit" may be used mixedly.

A "fluid" herein may be, but is not limited to, a gas, a liquid, an emulsion, a slurry, and a stream of solid particles having flow characteristics similar to the flow of a liquid. For example, the fluid may comprise a water-based liquid with chemical additives. In addition, chemical additives may include, but are not limited to, acids, gels, potassium chloride, surfactants, and the like.

A "formation" or "reservoir" herein is a subterranean porous and permeable rock formation (e.g., shale formation, sandstone formation, carbonate formation, etc.) that can serve as a storage space for fluids. Typically these fluids may be water, hydrocarbons or gases. Such porous and permeable rock formations that can store high pressure fluids are collectively referred to herein as "energy storage formations". The shale formation is used as a preferred embodiment to describe the energy storage and release method and system of the present application, because the shale formation can store fluid in its internal fractures for a long time.

As used herein, "hydraulic fracturing" or "fracturing" refers to the creation and propagation of a fracture in the formation rock under the influence of an external force (e.g., a high pressure fluid).

As used herein, a "hydraulic fracture" or "formation fracture" or "fracture" is an open rock gap created in a formation after a hydraulic fracture construction, and the terms "hydraulic fracture" or "formation fracture" or "fracture" are used interchangeably.

As used herein, "bottom-hole pressure" refers to the pressure at or near the depth of initiation of a hydraulic fracture (formation fracture) in a wellbore. When the frictional losses are negligible, the bottom hole pressure is equal to the fracture pressure of the hydraulic fracture.

By "wellbore" herein is meant a hole formed by drilling or inserting a conduit into the earth formation. Typically, the wellbore is cylindrical, and thus the wellbore may be circular in cross-section. Additionally, the wellbore may have any other cross-section. The wellbore may be open-hole, i.e., open-hole, or cased-hole, i.e., cemented to the wellbore inner wall.

As used herein, "width of a formation fracture" or "fracture width" refers to the relative displacement distance of two walls in a direction perpendicular to the plane of the formation fracture. When a formation fracture is assumed to be circular (or in engineering practice it may be considered circular or nearly circular), the "propagation radius" of the formation fracture refers to the radius of the circle (see the double-headed arrow R in fig. 3A), and the terms "width of the formation fracture" or "fracture width" may be used interchangeably.

"constant" or "unchanged" herein does not mean that the absolute variation of the specified item is zero, but that the variation for the specified item is very small, which can be considered constant in engineering practice. For example, the term "bottom hole pressure is unchanged" herein also means "approximately constant bottom hole pressure", or "radius of propagation" herein actually means "radius of propagation" of the formation fracture "is substantially unchanged" or "approximately constant" under the action of the high pressure fluid, or "width of the formation fracture" herein actually means "width of the formation fracture" is substantially unchanged "or" approximately constant "under the action of the high pressure fluid. It should also be appreciated that the term "equal" as used in this disclosure does not mean that the specified items are exactly the same, but rather is used to specify two items with negligible difference in engineering practice. For example, the term "equal/equal" in this disclosure may also have the meaning of "approximately equal/equal".

Example one

Shale is widely distributed and has extremely low permeability, and in the field of petroleum and natural gas, shale formations are generally regarded as overlying sealing layers of conventional oil and gas reservoirs and can prevent oil and gas from moving upwards and volatilizing to the ground. Meanwhile, the shale formation can also be used as a storage medium of fluid, and due to the extremely low permeability of the shale formation, high-pressure fluid in the internal formation fracture can be stored for a long time, and only a very small amount of fluid can be filtered into the formation rock pores, for example, the Oak Ridge National Laboratory in the united states injects fluid waste with radioactivity into the artificial formation fracture of the shale formation for decades, so that the purpose of permanent storage is achieved. Therefore, the present invention preferably achieves long-term energy storage by storing high-pressure fluid in artificial fractures (i.e., fractures of formations formed by hydraulic fracturing operations) of porous and permeable shale formations, i.e., shale formations as energy storage formations. Of course, the invention may also be applied to other porous and permeable rock formations.

Referring to fig. 1, the present invention provides a method for storing and releasing energy through a formation.

In step S100, at least one hydrocarbon-free energy storage formation (i.e., reservoir) is identified.

In some embodiments, the hydrocarbon-free energy storage formation comprises: depleted crude oil and gas reservoirs have been produced.

In some embodiments, visual methods may be used to identify information (e.g., the depth of the formation and the thickness of the formation) associated with an energy storage formation (preferably a shale formation), for example, by obtaining a core through a borehole. In other embodiments, indirect methods may also be used to identify information about the formation, such as interpreting log/log data and seismic data inversion.

In step S102, the energy storage formation is subjected to hydraulic fracturing construction so that the energy storage formation generates at least one formation fracture.

During a hydraulic fracturing construction, injected fracturing fluid is pumped into the wellbore through surface facilities, such as first surface facility 240, second surface facility 250 in fig. 2 into vertical well 210 and horizontal well 220, respectively. Once the bottom hole pressure of the vertical well 210 and the horizontal well 220 reaches the fracture pressure of the subterranean formation 230 (i.e., the bottom hole pressure is greater than or equal to the fracture pressure), the first hydraulic fracture 260, the second hydraulic fracture 262 in the vertical well 210 will initiate from around the vertical well 210 and propagate into the subterranean formation 230 until pumping stops (i.e., hydraulic fracturing construction stops), and correspondingly, the third hydraulic fracture 264, the fourth hydraulic fracture 266, the fifth hydraulic fracture 268, the sixth hydraulic fracture 270 in the horizontal well 220 will initiate from around the horizontal well 220 and propagate into the subterranean formation 230 until pumping stops. As shown in fig. 2, the hydraulic fractures (e.g., first, third, and fourth

hydraulic fractures

260, 264, 266 in fig. 2) may form a planar geometry and propagate in a direction perpendicular to the minimum principal stress F of the shale formation. However, under certain geological conditions, some hydraulic fractures (e.g., the second hydraulic fracture 262, the fifth hydraulic fracture 268, the sixth hydraulic fracture 270 in fig. 2) may interact with pre-existing natural fractures to form complex fracture geometries.

In practical application, the expansion degree of the formation fracture can be determined according to different energy storage requirements and mechanical characteristics of the energy storage formation, for example, if more energy needs to be stored, a longer formation fracture needs to be designed, and if relatively less energy needs to be stored, a shorter formation fracture needs to be designed, so that design parameters of the formation fracture, such as an expansion radius (or an expansion length), can be set in advance according to the actual requirements, and when the expansion radius of the formation fracture is judged to meet the design requirements, pumping of fracturing fluid is stopped (i.e., hydraulic fracturing construction is stopped), so that the formation fracture gradually stops expanding.

In some embodiments, before the step of injecting the high pressure fluid into the at least one formation fracture (i.e., before performing step S104), the method further comprises the steps of:

and judging whether the expansion radius of the formation fracture reaches a preset target radius or not, and stopping hydraulic fracturing construction when the expansion radius of the formation fracture reaches the target radius, so that the formation fracture gradually stops expanding.

Specifically, in some embodiments, the step of determining whether the propagation radius of the formation fracture reaches the preset target radius specifically includes the steps of: calculating to obtain a three-dimensional body of the formation fracture according to a pre-constructed hydraulic fracturing model, rock mechanical characteristics and first construction parameters, and obtaining an expansion radius of the formation fracture according to the three-dimensional body; then, it is determined whether the propagation radius of the formation fracture is equal to or greater than the target radius.

In some embodiments, the hydraulic fracturing model may employ a two-dimensional PKN model, a KGD model, a RADIAL model, and a pseudo three-dimensional model and a full three-dimensional model, and the first construction parameter is a construction parameter of a surface facility (i.e., an injection device in a hydraulic fracturing construction apparatus), including: injection rate of fracturing fluid, total injection volume, fracturing fluid viscosity.

Of course, in other embodiments, when to stop the hydraulic fracturing construction may be determined by a worker in combination with relevant work experience, for example, the worker may determine or calculate the time to stop the hydraulic fracturing construction based on the work experience in combination with the injection rate of the fracturing fluid, the total injection volume, and the viscosity of the fracturing fluid.

Preferably, in some embodiments, the preset target radius is set by a professional according to mechanical characteristics of the energy storage stratum, so that the energy storage stratum is prevented from being damaged by an excessively large expansion radius of the stratum fracture while the stratum fracture is ensured to have a certain storage capacity.

In some embodiments, a plurality of formation fractures are produced in the hydraulic fracturing construction process, and in order to avoid damage to the energy storage formation due to an excessively large propagation radius of the formation fractures, the hydraulic fracturing construction is preferably stopped when it is detected that one formation fracture has a propagation radius equal to or greater than a preset target radius. Of course, in other embodiments, the hydraulic fracturing construction may be stopped when the average propagation radius of all the formation fractures is determined to be equal to or equal to the preset target radius.

It will be appreciated that upon cessation of the hydraulic fracturing operation, the formation fracture will not immediately cease to propagate, and therefore, to avoid having a too large propagation radius of the formation fracture, it is preferred in some embodiments to cease the hydraulic fracturing operation when the propagation radius of the formation fracture is approximately equal to (or close to) the target radius (e.g., when the propagation radius is 0.90-0.95 times the target radius).

Preferably, in order to reduce the rate of fluid loss from the fracturing fluid in the formation fracture to the surrounding rock, so that the formation fracture in the energy storage formation has the capability of storing the fracturing fluid or high-pressure fluid for a long time, in some embodiments, a fluid loss additive is added to the fracturing fluid in the hydraulic fracturing construction in step S102.

Preferably, in some embodiments, the fluid loss additive may comprise: the fluid loss additive can also be particles with the effect of blocking pores of a rock matrix of the energy storage stratum, such as micro-nano materials, and the particles are filled into the pores of the rock matrix around the formation cracks in the fluid loss process, so that the permeability of the energy storage stratum is reduced, and the fluid loss prevention effect is achieved.

In some embodiments, fluid loss additives may include: at least one silicate, and/or at least one sulfate, and/or at least one phosphate, and/or at least one oxalate, which may react with formation mineral cations to form precipitates that plug the pores of the formation rock matrix.

In step S104, the injection device is driven by electric energy to inject high-pressure fluid into at least one formation fracture, so that the width of the at least one formation fracture is increased, and the electric energy is converted into formation rock elastic deformation energy for storage.

Further, in some embodiments, in step S104, the pressure of the fluid injected into the at least one formation fracture is greater than the minimum principal stress of the energy storage formation and less than the propagation pressure of the formation fracture, so that the width of the formation fracture gradually increases and the propagation radius remains constant or constant (since the fluid pressure is less than the propagation pressure of the formation fracture, the formation fracture will not propagate, i.e., the propagation radius of the fracture remains constant or constant).

Of course, in other embodiments, the radius of propagation of the formation fracture remaining constant or held constant may be understood to remain constant or held constant over a period of time. For example, when the width of a formation fracture changes due to the action of high-pressure fluid, the expansion radius of the formation fracture also gradually changes (i.e., continues to expand), but within a certain time (e.g., one hour), the change of the expansion radius can be ignored in engineering practice; alternatively, when a fracture in the formation is propagated by the action of the high-pressure fluid, the fracture which continues to be propagated is filled or partially filled with particulate matter or the like added to the high-pressure fluid over a certain period of time.

Preferably, in some embodiments, the minimum principal stress of the energy storage formation may be obtained by a small Fracturing (Diagnostic Fracturing Injection Test) or a Flowback-assisted small Fracturing (Rapid Injection-Flowback Test) Test. The propagation Pressure of the formation fracture can be obtained by analyzing the Instantaneous Shut-In Pressure (instant Shut-In Pressure) of the Pressure drop curve after the hydraulic fracturing construction stops pumping.

In some embodiments, in step S104, the method specifically includes the steps of: monitoring the pressure of the injected fluid in real time, and judging whether the pressure of the injected fluid is greater than the minimum principal stress of the stratum and less than the expansion pressure of the stratum fracture;

if so, maintaining a second construction parameter of high-pressure fluid injected into the formation fracture at present; otherwise, adjusting a second construction parameter (i.e., the construction parameter of the injection equipment) for injecting high pressure fluid into the formation fracture so that the current fluid pressure is always maintained between the extension pressure and the minimum principal stress of the energy storage formation.

In some embodiments, the second construction parameter comprises: the injection rate and the total injection volume of the fluid, in particular, the fluid pressure can be adjusted by adjusting the rate at which the injection device injects high-pressure fluid or the amount of fluid injected, and the fluid pressure can be monitored by a pressure monitoring device installed in advance.

Specifically, in some embodiments, before injecting the high pressure fluid into the at least one formation fracture (i.e., before performing step S104), the method further comprises the steps of: at least one reservoir for storing a fluid is provided underground or at the surface. Wherein the reservoir is in communication with a wellbore in a hydraulic fracturing construction via a conduit (e.g., a surface conduit).

Preferably, in some embodiments, one or more additives may be pre-added to the fluid in the reservoir (i.e., one or more additives may be added to the fluid injected into the formation fracture), for example, biocides, detergents, mineral salts (e.g., KCl, NaCl, CaCl)₂,NaSiO₄Etc.) and fluid loss additives, wherein mineral salts are used to balance the electrolytes of the energy storage formation.

When the reservoir is located on the ground, preferably to reduce loss of fluid, in some embodiments the reservoir is provided with a barrier structure for preventing evaporation of the fluid, for example, covered with a plastic or metal film over the reservoir.

In step S106, determining whether the width of the at least one formation fracture is equal to or greater than a preset target width, if so, performing step S108, that is, stopping supplying electric energy to the injection device to stop the injection device from injecting the high-pressure fluid into the at least one formation fracture, so as to keep the bottom hole pressure unchanged and the width of the formation fracture unchanged (at this time, since the pipelines between the wellbore, the reservoir, and the injection device are all in a closed state, the bottom hole pressure remains unchanged after the injection of the high-pressure fluid is stopped); otherwise, step S110 is performed to continue injecting high pressure fluid into at least one formation fracture.

Wherein the width of the formation fracture is calculated according to the height of the formation fracture, the propagation radius of the formation fracture and the bottom pressure, it can be understood that the widths of different positions in the formation fracture are not equal, and preferably, in some embodiments, the "width of the formation fracture" in step S106 refers to the average width of all formation fractures; of course, in other embodiments, the "width of the formation fracture" in step S106 may also refer to the width of any formation fracture.

For example, in some embodiments, during the process of injecting high pressure fluid into the formation fracture, the width data of all the formation fractures is acquired, the widths of all the formation fractures are averaged to obtain the average width of all the formation fractures, and when the average width is equal to or greater than a preset target width, power supply to the injection device is stopped, so that the injection device stops injecting high pressure fluid into the formation fracture.

In some embodiments, the target width of the formation fracture is set by a professional according to the mechanical characteristics of the energy storage formation and different energy storage requirements in advance, so that the formation fracture is ensured to have certain storage capacity, and the damage to the energy storage formation caused by the overlarge width of the formation fracture is avoided. It is understood that, because a plurality of formation fractures exist, in order to avoid damage to the energy storage formation due to the excessive width of the formation fractures, preferably, when it is detected (or determined) that one formation fracture exists, the width of which is equal to or greater than the preset target width, step S108 is executed to stop supplying electric energy to the injection device, so that the injection device stops injecting high-pressure fluid into at least one formation fracture, thereby keeping the bottom hole pressure constant and keeping the fracture width constant.

Of course, in other embodiments, when it is detected that the power supplied to the injection device is insufficient (e.g., when the weather changes cause the solar or wind power generation to be insufficient, specifically, when all or most of the too-energy and wind power generation is consumed by the end user supplying power and no excess power is supplied to the injection device), step S108 is performed to stop supplying power to the injection device, so that the injection device stops injecting the high-pressure fluid into at least one formation fracture, thereby keeping the bottom hole pressure constant and keeping the fracture width constant.

For example, in some embodiments, referring to fig. 3A and 3B, when the electrical energy is stopped to the injection apparatus, so that the injection apparatus stops injecting the high-pressure fluid into at least one formation fracture, the control valve corresponding to the first surface conduit 330 (i.e., the injection conduit for injecting the high-pressure fluid) is closed (at this time, since the second surface conduit 370, i.e., the control valve corresponding to the inverted conduit for inverting the high-pressure fluid, is in a normally closed state), so that the formation fracture and the high-pressure fluid in the wellbore cannot be inverted to the reservoir/surface through the first and second surface conduits, at this time, the total volume of the formation fracture and the high-pressure fluid in the wellbore is kept unchanged (the filtration loss of the high-pressure fluid can be ignored in engineering practice), so that the bottom hole pressure is kept unchanged, and the width of the formation fracture is kept unchanged.

In step S112, monitoring whether there is a power generation demand, and when it is monitored that there is a power generation demand, performing step S114, driving a preset power generation device to generate power by using high-pressure fluid reversely discharged due to closure of at least one formation fracture, so as to convert elastic deformation energy of formation rock into electric energy; otherwise, whether the power generation is required or not is continuously monitored.

Further, in some embodiments, the reservoir is connected to the wellbore corresponding to the formation fracture through a pipeline (for example, an injection pipeline and a reverse drainage pipeline), and after the injection of the high-pressure fluid into the formation fracture is stopped, both the reverse drainage pipeline and the injection pipeline are in a closed state (specifically, the reverse drainage pipeline and a control valve in the injection pipeline are in a closed state), so that when a power generation demand is monitored, the control valve corresponding to the reverse drainage pipeline is opened to circulate the reverse drainage pipeline, so that the high-pressure fluid in the formation fracture can be reversely drained into the reservoir through the reverse drainage pipeline under the action of rock compression, and the power generation equipment is driven to generate power.

For example, referring to fig. 3A and 3B, a first surface conduit 330 (i.e., an injection conduit) and a second surface conduit 370 (i.e., a reverse drainage conduit) of the reservoir connected to the wellbore are provided with control valves for controlling the circulation and closure of the surface conduits, and after the injection of high-pressure fluid into the formation fracture is stopped and before the power generation is detected, the control valves corresponding to the first surface conduits are in a closed state, and when the power generation is detected (for example, the corresponding control system, or the first power generation device, or the corresponding operator receives a power supply request sent from an external device, such as a power grid or other control system), the control system connected to the control valves, or the first power generation device 360 opens the control valves corresponding to the second surface conduit 370 between the wellbore and the reservoir (of course, the control valves can also be manually opened by the operator), so as to communicate between the wellbore and the reservoir, under the action of rock extrusion, high-pressure fluid in the formation fracture is reversely discharged into the reservoir and drives an impeller of the first power generation equipment 360 to rotate so as to generate power; of course, if no power request is received, the second surface conduit 370 between the well bore and the reservoir will remain closed all the time, i.e. the control valve in the second conduit is normally closed, and at this time, it is sufficient to continue to monitor whether there is a power demand.

Furthermore, the power generation equipment is connected to a power grid, so that the power supply to the electric equipment can be stably realized.

Specifically, in some embodiments, at least one power generation device is previously disposed in the reservoir or a pipe connecting the reservoir to the wellbore, and the power generation device is connected to the power grid. After the high-pressure fluid is stopped being injected into the stratum crack, and a pipeline between the reservoir and the shaft is in an opening state (or a circulation state), the fluid pressure (larger than the minimum principal stress of the stratum and smaller than the expansion pressure of the stratum crack) in the stratum crack is far higher than the water pressure in the reservoir due to the extrusion of the rock, so that the high-pressure fluid in the stratum crack is reversely discharged into the reservoir under the extrusion effect of the rock, an impeller of the power generation equipment is pushed to rotate for power generation, the elastic deformation energy of the rock around the stratum crack can be converted into electric energy, and the stable power supply of a power grid connected with the power generation equipment is realized. During the process of gradually closing the stratum fracture, the fluid pressure in the stratum fracture is gradually reduced, when the stratum fracture is completely closed, the fluid pressure in the stratum fracture is reduced to the minimum principal stress of the stratum, the elastic deformation energy of rocks around the stratum fracture is completely released, namely the elastic deformation energy of the rocks is completely converted into electric energy (the friction loss of high-pressure fluid in the ground pipeline and the well bore in the migration process is ignored).

In some embodiments, when a power supply demand is detected, the fluid in the formation fracture is reversely discharged under the action of rock squeezing by opening a control valve arranged on a pipeline between the well bore and the water reservoir, and the power generation equipment is driven to generate power. For example, referring to fig. 4A and 4B, after stopping injecting the high-pressure fluid into at least one formation fracture, the valve in the third surface pipe 430 between the wellbore and the reservoir is also in a closed state (in this case, the injection pipe and the inverted pipe are the same pipe, i.e., the third surface pipe 430), when power generation is detected, the control valve corresponding to the third surface pipe 430 between the wellbore and the reservoir is opened, and at this time, under rock squeezing, the high-pressure fluid in the formation fracture is inverted into the reservoir through the third surface pipe 430 and drives the impeller of the second power generation device 410 (i.e., the second injection device) to rotate to generate power; if no power demand is monitored, the surface conduit 430 between the wellbore and the reservoir remains closed at all times (specifically, closing the control valve associated with the third surface conduit).

The cyclic storage and release of the electric energy can be realized through the reciprocating cycles of the steps S104, S106, S108, S112 and S114, for example, the surplus solar electric power is stored by the elastic deformation energy of the rock around the fracture of the energy storage stratum in the daytime, and when the solar power generation cannot be performed at night, the elastic deformation energy of the energy storage stratum is converted into the electric energy again and released to the power grid for supplying power, and the electric energy can also be generated by wind power generation or other renewable resources.

Example two

For example, in one embodiment of the present disclosure, as shown in fig. 3A, the first injection device 310 (i.e., a power injection device) driven by the power grid injects fluid from the first reservoir 320 through the first surface conduit 330 and the first wellbore 340 into the seventh hydraulic fracture 380 in the first shale formation 350, such that the width of the formation fracture expands and the rock surrounding the fracture elastically deforms to store energy.

Wherein, assuming that the formation fracture is circular (or the formation fracture can be considered to be circular or approximately circular in engineering practice), the expansion radius of the circular fracture is 500m (the expansion radius is shown as a bidirectional arrow R in FIG. 3A), the distance from the ground is 500m, the average Young modulus of the rock is 20GPa, the fluid pressure in the fracture is 3MPa higher than the minimum principal stress of the shale formation, and the energy stored by the elastic deformation of the shale formation around the fracture is 2.8 x 10 according to fracture mechanics¹¹J, i.e., 78530kw · h. After the injection of fluid into the fracture is stopped and a power generation demand is monitored, as shown in fig. 3B, a seventh hydraulic fracture 380 within the shale formation 350 is gradually closed and squeezes the fluid within the fracture such that the fluid (i.e., high pressure fluid) is expelled back into the first reservoir 320 through the first wellbore 340 and the second surface conduit 370, thereby driving the first power generation apparatus 360 to rotate and incorporate power into the grid.

EXAMPLE III

Preferably, to simplify the construction apparatus, in some embodiments, the power generation device and the injection device are the same device, the injection device is disposed in the surface pipeline, when the power grid is connected, the injection device (i.e. the power generation device) starts to operate, at this time, the surface pipeline between the well bore and the reservoir and the injection device is in an open state/circulation state (specifically, a control valve disposed in the well bore or the surface pipeline is opened), the impeller of the injection device drives the fluid in the reservoir to flow through the surface pipeline into the well bore, so that at least one formation fracture produced by the hydraulic fracturing construction is widened, that is, electric energy is converted into elastic deformation energy of the formation fracture, when the width of at least one formation fracture is detected/determined to be greater than or equal to the target width, the injection device stops injecting the fluid into the well bore, and causes the well bore, the reservoir, the injection device, the control valve and the control valve to open state, The ground pipeline between the injection devices is in a closed state/non-circulation state (specifically, a control valve arranged in the ground pipeline or a shaft is closed), so that the bottom hole pressure is kept unchanged, the width of a stratum crack is kept unchanged, when the power generation requirement is monitored, the control valve corresponding to the ground pipeline is opened, high-pressure fluid in the stratum crack is gradually reversely discharged into a reservoir through the shaft and the bottom pipeline under the extrusion action of rocks, in the process, the reversely discharged fluid pushes an impeller of the injection devices to rotate for power generation, and the crack is gradually closed.

For example, in one embodiment of the present disclosure, as shown in fig. 4A, the second injection device (i.e., a second power generation device, i.e., an electrically powered injection device) 410 is driven by the power grid to inject the fluid in the reservoir 420 into the eighth hydraulic fracture 460 in the second shale formation 450 through the third surface conduit 430 and the second wellbore 440, such that the fracture width expands and the rock around the fracture elastically deforms to store energy. As shown in fig. 4B, when the eighth hydraulic fracture 460 in the second shale formation 450 closes, fluid within the fracture is squeezed. Causing the fluid (i.e., high pressure fluid) to drain back from the eighth hydraulic fracture 460 through the second wellbore 440 and the third surface conduit 430 into the second reservoir 420, driving the second injection apparatus 410 to rotate to generate electricity, and to merge the electricity into the power grid.

Preferably, in some embodiments, to prevent initiation and propagation of hydraulic fractures (i.e., formation fractures) in other non-shale formations, the method further comprises the steps of: and arranging a casing at the position of the shaft, which is positioned at the upper end of the energy storage stratum. In particular, it is often desirable to cement the casing in an open hole wellbore up to an upper portion of the identified reservoir depth of the energy storage formation.

Preferably, in order to make the hydraulic fracture initiation from the identified energy storage stratum easier, in some embodiments, the step of performing hydraulic fracture construction on the energy storage stratum further comprises the steps of: and carrying out perforation operation on the inner part of a shaft in the energy storage stratum in the shaft in the hydraulic fracturing construction. In particular, perforating operations may be performed within the thickness of the identified energy storage formation (i.e., within the upper and lower boundaries of the energy storage formation's burial depth).

Preferably, in some embodiments, the fluid loss additive in the fluid or fracturing fluid comprises: at least one high molecular polymer, and/or at least one resin, and/or at least one quartz sand, and/or at least one gel, and/or at least one silicate, and/or at least one sulphate, and/or at least one phosphate, and/or at least one oxalate, and/or at least one particle having the effect of plugging the pores of the rock matrix of the energy storage formation.

Example four

The invention also provides a system for storing energy in a formation, see fig. 5, the apparatus comprising:

a formation recognition device 02 for recognizing at least one hydrocarbon-free energy storage formation;

the hydraulic fracturing construction device 04 is used for performing hydraulic fracturing construction on the energy storage stratum so that at least one stratum fracture is generated in the energy storage stratum;

and the injection device 06 is used for injecting high-pressure fluid into at least one formation fracture to increase the width of the at least one formation fracture, so that the electric energy is converted into formation rock elastic deformation energy to be stored.

Preferably, in some embodiments, the hydraulic fracturing construction device 04 and the injection device 06 are the same device.

In some embodiments, the system further comprises: and the first control device 08 is connected with the hydraulic fracturing construction device 04 and used for judging whether the expansion radius of at least one stratum fracture reaches a preset target radius or not, and when the expansion radius reaches the target radius, the first control device sends a second control instruction indicating that the injection of the fracturing fluid is stopped to the hydraulic pressure construction device so that the hydraulic fracturing construction device stops hydraulic fracturing construction.

In some embodiments, the first control device 08 specifically comprises:

a first calculation module 082, configured to calculate a three-dimensional shape of the formation fracture according to a hydraulic fracturing model that is constructed in advance, a rock mechanical property, and a first construction parameter, and obtain an expansion radius of the formation fracture according to the three-dimensional shape;

and the first judging module 084 is used for judging whether the expansion radius of the formation fracture is equal to or larger than the target radius, generating a second control instruction for indicating stopping injecting the fracturing fluid when judging that the expansion radius of the formation fracture is equal to or larger than the target radius, and sending the second control instruction to the hydraulic pressure construction device so that the hydraulic fracturing construction device stops hydraulic fracturing construction.

In some embodiments, the system further comprises: and the second control device 10 is connected with the injection device 06 and is used for judging whether the width of the at least one formation fracture is equal to or larger than a preset target width, if so, generating a third control instruction indicating that the injection of the high-pressure fluid is stopped, and sending the third control instruction to the injection device 06 so that the injection device 06 stops injecting the high-pressure fluid into the at least one formation fracture and the width of the formation fracture is kept unchanged.

In some embodiments, the second control device 10 is also configured to monitor whether the power supply of the injection device 06 is sufficient, and if not, generate a third control command indicating that the injection of the high-pressure fluid is stopped, and send the third control command to the injection device 06, so that the injection device 06 stops injecting the high-pressure fluid into at least one formation fracture, so that the width of the formation fracture is kept constant.

Specifically, in some embodiments, the injection device 06 is installed in an injection conduit (i.e., a conduit communicating the reservoir and the wellbore and providing for fluid injection), and when the injection device 06 ceases to inject high pressure fluid into at least one formation fracture, the injection device 06 places the injection conduit in a closed/non-flow state, specifically, the injection device 06 closes a valve in the injection conduit.

In some embodiments, the system further comprises: and the power generation device 12 is used for converting the elastic deformation energy of the formation rock into electric energy under the action of the high-pressure fluid when the high-pressure fluid in at least one formation fracture is reversely discharged under the action of rock extrusion.

In some embodiments, the system further comprises: a reservoir 14 connected to the injection device 06 for storing the fluid.

Further, in some embodiments, the reservoir is connected to the wellbore corresponding to the formation fracture through a reverse drainage pipe, and a control valve for controlling opening (i.e. circulation) or closing (i.e. non-circulation) of the wellbore or the reverse drainage pipe is disposed in the wellbore or the reverse drainage pipe, and accordingly, the system further includes: and the monitoring device is connected with the control valve and used for monitoring whether a power generation demand exists, when the power generation demand is monitored, a first control instruction for opening the control valve of the inverted pipeline is generated and sent to the control valve to control the control valve to be opened, namely, the reservoir is communicated with the shaft, otherwise, the monitoring device continues to monitor whether the power generation demand exists.

Specifically, in some embodiments, the drainback pipe between the reservoir and the wellbore is normally closed/not open (specifically, the valve in the drainback pipe is normally closed), when the power generation device 12 receives a first control command (e.g., a control command from a power grid or other control system connected to the power generation device 12, or a control command issued by a worker) sent by a monitoring device indicating that the control valve corresponding to the drainback pipe is open, the power generation device 12 will open the drainback pipe between the wellbore and the reservoir (specifically, open the control valve corresponding to the drainback pipe) so that high-pressure fluid in the formation fracture is drained back into the reservoir through the drainback pipe under rock squeezing and drive the impeller of the power generation device 12 to generate power, if the power generation device 12 does not receive the control command indicating that the control valve corresponding to the drainback pipe is open, the generator 12 keeps the reverse drain pipe closed all the time, and at this time, the monitoring module continues to monitor whether there is a power supply requirement, and in other embodiments, the staff may determine whether there is a power supply requirement, and the staff may control the opening and closing of the valve in the injection/reverse drain pipe.

In some embodiments, the injection device 06 comprises:

a fluid injection module 062 for injecting high pressure fluid into at least one formation fracture;

a pressure monitoring module 064 for monitoring the pressure of the injected fluid in real time;

and the pressure judging module 066 is connected with the fluid injection module 062 and the pressure monitoring module 064 and is used for judging whether the pressure of the injected fluid is greater than the minimum principal stress of the energy storage stratum and less than the expansion pressure of the stratum fracture, if so, the pressure judging module 066 is not operated, otherwise, the pressure judging module 066 generates a fourth control instruction for adjusting the second construction parameter (namely the working parameter of the fluid injection module 062) and sends the fourth control instruction to the fluid injection module 062 so as to control the fluid injection module 062 to adjust the second construction parameter, and the current fluid pressure is always kept between the expansion pressure and the minimum principal stress of the energy storage stratum.

Preferably, to simplify the system, in some embodiments, the power generation device 12 and the fluid injection module 062 of the injection device 06 are the same device, i.e., the injection tubing and the inverted tubing are the same tubing, e.g., in some embodiments, the system does not require additional power generation device 12, wherein the fluid injection module 062 is disposed in a tubing of the reservoir 14 connected to the wellbore, when power is supplied to the injection device 06 and the fluid injection module 062 is turned on, the fluid injection module 062 drives fluid in the reservoir 14 into a formation fracture, at which time the fluid injection module 062 (i.e., the power generation device 12) maintains the tubing between the reservoir and the wellbore in a closed state, when power generation demand is detected, the fluid injection module 062 (i.e., the power generation device 12) receives an externally transmitted control command indicating power supply demand, and then the fluid injection module 062 opens the tubing connecting the reservoir and the wellbore, so that the high-pressure fluid in the formation fracture is reversely discharged into the reservoir 14 through the pipeline under the action of rock extrusion and pushes the impeller of the fluid injection module 062 arranged in the pipeline to rotate to generate power.

EXAMPLE five

A third aspect of the invention provides a non-transitory computer program product having a computer program stored thereon, which, when being executed by a processor, controls an apparatus of the computer program product to carry out the steps of the method as defined in the first embodiment.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

Reference to "one embodiment" or "an embodiment" of the present invention means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Furthermore, the terms "a" and "an" herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. In addition, various features are described which some embodiments may exhibit which other embodiments may not. Similarly, various requirements are described which may be requirements for some embodiments but not other embodiments.

While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method of storing and releasing energy through a formation comprising the steps of:

identifying at least one hydrocarbon-free energy storage formation;

2. The method of claim 1, wherein a fluid loss additive is included in the fracturing fluid in the hydraulic fracturing construction, the fluid loss additive comprising: at least one high molecular polymer, and/or at least one resin, and/or at least one quartz sand, and/or at least one gel, and/or at least one silicate, and/or at least one sulphate, and/or at least one phosphate, and/or at least one oxalate, and/or at least one particle having the effect of plugging the pores of the rock matrix of the formation.

3. The method of claim 1, wherein the step of injecting high pressure fluid into the at least one formation fracture is preceded by the step of:

4. The method of claim 1 wherein the pressure of the fluid injected into the at least one formation fracture is greater than the minimum principal stress of the formation and less than the propagation pressure of the formation fracture such that the width of the formation fracture progressively increases.

5. The method of claim 1, wherein before using the high pressure fluid that is displaced during the closing of the formation fracture to drive a predetermined power generation device to generate power, further comprising the steps of:

6. The method of claim 1, further comprising, prior to injecting the high pressure fluid into the at least one formation fracture: at least one reservoir is provided underground or at the surface for storing the fluid.

7. The method according to claim 1, wherein the step of driving a preset power generation device to generate power by using the high-pressure fluid reversely discharged during the closing process of the formation fracture comprises the following steps:

8. The method of claim 1, wherein the high pressure fluid comprises: a bactericide, and/or a detergent, and/or a mineral salt, and/or a fluid loss additive.

9. A system for storing and releasing energy through a formation, comprising:

the injection device is used for injecting high-pressure fluid into the at least one formation fracture to enable the width of the at least one formation fracture to be increased, so that electric energy is converted into formation rock elastic deformation energy to be stored; and the power generation device is used for converting the elastic deformation energy of the formation rock into electric energy under the driving of the high-pressure fluid when the high-pressure fluid in the formation fracture is reversely discharged under the rock extrusion effect in the closing process of the formation fracture.

10. The system of claim 9, further comprising: