Multi-layer geothermal development and energy storage system

Abstract

The application provides a multi-layer geothermal development and energy storage system, which comprises a geothermal reservoir, a common layer, a tail water reservoir, a geothermal well, an energy utilization facility, a tail water reinjection well and a tail water recharge device, the bottom of the geothermal well is located in the geothermal reservoir, the bottom of the tail water reinjection well is located in the tail water reservoir, the depth of the geothermal reservoir is greater than that of the tail water reservoir, and the porosity and permeability of the geothermal reservoir and the tail water reservoir are higher than those of the common layer; the geothermal energy is stored in the geothermal reservoir, the heat fluid is extracted from the geothermal reservoir through the geothermal well, the energy utilization facility works by using the geothermal energy carried in the heat fluid, and the tail water generated in the geothermal energy utilization process is reinjected into the tail water reservoir through the tail water reinjection well; the tail water recharge device uses a supplementary energy to recharge the tail water stored in the tail water reservoir to the geothermal reservoir. The tail water of the geothermal reservoir is stored in the tail water reservoir, and the ground construction of the geothermal tail water storage facility is not needed, so that the economic feasibility of the geothermal system is improved, and the limitation of the energy storage capacity of the geothermal system is reduced.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of geothermal development and energy storage technology, specifically to a multi-stratum geothermal development and energy storage system. Background Technology

[0002] Geothermal energy is a clean and renewable energy source, but its utilization generates geothermal tailwater. Failure to reinject this tailwater pollutes the environment, while reinjection consumes energy and incurs costs, reducing the profitability of geothermal projects and potentially leading to losses. This is especially true for deep, high-temperature geothermal resources below 3000m. Due to the great depth, the overlying rock pressure is high, the formation is highly compacted, and the porosity and permeability are low, resulting in significant resistance to water flow and even higher energy consumption and costs for tailwater reinjection. For deep, high-temperature geothermal resources, whether hydrothermal or hot dry rock, establishing a water injection-production cycle for large-scale development requires sufficient energy to overcome formation seepage resistance. The development and utilization of geothermal energy has long been constrained by the cost of tailwater reinjection. Therefore, solving the energy consumption problems of tailwater reinjection and formation injection-production cycles is one of the key issues in expanding the scale of geothermal resource development and utilization.

[0003] To address the energy consumption issues associated with geothermal tailwater reinjection and formation injection-production cycles, researchers in this field have proposed introducing other renewable energy sources to balance the energy consumption of geothermal systems. This method utilizes other renewable energy sources for pressurized water injection, resolving the energy consumption problem of the formation injection-production cycle. However, the power output of these introduced renewable energy sources is temporally unstable, requiring intermittent pressurized water injection. To ensure water is available for energy storage when needed, geothermal tailwater needs to be stored on the surface. Storing geothermal tailwater requires the construction of surface-based storage facilities. Whether using reservoirs or tanks, this incurs land acquisition costs, facility construction costs, and facility maintenance costs, which not only weakens the economic viability of the geothermal system but also limits the energy storage capacity of the geothermal system due to the limited capacity of the storage facilities. Summary of the Invention

[0004] This invention provides a multi-stratum geothermal development and energy storage system to solve the problems of low economic feasibility and limited energy storage capacity caused by the need to construct geothermal tailwater storage facilities on the ground in existing systems.

[0005] This invention provides a multi-stratum geothermal development and energy storage system, comprising:

[0006] Geothermal reservoir, ordinary formation, tailwater reservoir, geothermal well, energy-consuming facilities, tailwater reinjection well and tailwater reinjection device. The bottom of the geothermal well is located in the geothermal reservoir, the bottom of the tailwater reinjection well is located in the tailwater reservoir, the depth of the geothermal reservoir is greater than that of the tailwater reservoir, and the porosity and permeability of the geothermal reservoir and the tailwater reservoir are higher than those of the ordinary formation.

[0007] Geothermal reservoirs store geothermal energy. Geothermal fluids are extracted from geothermal reservoirs through geothermal wells. Energy-using facilities utilize the geothermal energy carried in the thermal fluids to operate. Tailwater generated during the geothermal energy utilization process is reinjected into the tailwater reservoir through tailwater reinjection wells.

[0008] The tailwater reinjection device uses supplemental energy to reinject the tailwater stored in the tailwater reservoir back into the geothermal reservoir.

[0009] In one embodiment, the supplementary energy includes: wind energy during periods of wind curtailment, solar energy during periods of solar curtailment, and grid power during periods of low electricity prices.

[0010] In one embodiment, the tailwater reinjection device includes: a water replenishment pumping well, a water replenishment pumping station and control facilities, and a water replenishment injection well. The bottom of the water replenishment pumping well is located in the tailwater reservoir, and the bottom of the water replenishment injection well is located in the geothermal reservoir.

[0011] The water replenishment pumping station and control facilities use supplementary energy to extract tailwater from the tailwater reservoir through the water replenishment pumping well, pressurize it, and then inject it into the geothermal reservoir through the water replenishment injection well.

[0012] In one embodiment, the tailwater reinjection device includes: a booster pump control facility and a water injection well, wherein the bottom of the water injection well is located in the geothermal reservoir;

[0013] A submersible booster pump is installed in the water injection well at a position in the tailwater reservoir and near the bottom of the tailwater reservoir. The booster pump control facility controls the submersible booster pump to use supplementary energy to draw tailwater from above and discharge it downwards after pressurization.

[0014] In the portion of the water injection well located within the geothermal reservoir, one or more radial wellbores are constructed to connect the water injection well with the water flow channel of the geothermal reservoir.

[0015] In one embodiment, the tailwater reinjection device includes: a booster pump control facility and a water injection well, wherein the bottom of the water injection well is located in the geothermal reservoir;

[0016] Hydraulic fracturing is performed in the water injection well to construct one or more hydraulic fracturing fractures that connect the tailwater reservoir and the geothermal reservoir, so that the tailwater in the tailwater reservoir can flow into the geothermal reservoir through the hydraulic fracturing fractures.

[0017] A submersible booster pump is installed at a predetermined location in the water injection well. The booster pump control system controls the submersible booster pump to use supplementary energy to draw tailwater from above and discharge it downwards after pressurization.

[0018] In one embodiment, when the geothermal reservoir is a hot dry rock formation, the geothermal reservoir is formed by hydraulic fracturing in the hot dry rock formation to create artificial fractures;

[0019] The tailwater reinjection device includes a booster pump control facility and a water injection well. The water injection well is a horizontal well, and the horizontal section is located in a dry hot rock formation.

[0020] The geothermal well is a horizontal well, and the depth of the horizontal section of the geothermal well is lower than the depth of the horizontal section of the water injection well;

[0021] A submersible booster pump is installed at a predetermined location in the water injection well. The booster pump control system controls the submersible booster pump to use supplementary energy to draw tailwater from above and discharge it downwards after pressurization.

[0022] In one embodiment, a tailwater storage tank is provided between the energy-consuming facility and the tailwater reinjection well to store the geothermal tailwater generated by the energy-consuming facility within a preset time period.

[0023] The tailwater storage tank is equipped with a reinjection pump, which uses supplemental energy to reinject the tailwater stored in the tailwater storage tank back into the tailwater reservoir through the tailwater reinjection well.

[0024] The multi-stratum geothermal development and energy storage system provided in this invention includes: a geothermal reservoir, a common stratum, a tailwater reservoir, a geothermal well, energy-consuming facilities, a tailwater reinjection well, and a tailwater reinjection device. The bottom of the geothermal well is located in the geothermal reservoir, and the bottom of the tailwater reinjection well is located in the tailwater reservoir. The depth of the geothermal reservoir is greater than that of the tailwater reservoir, and the porosity and permeability of the geothermal reservoir and the tailwater reservoir are higher than those of the common stratum. Geothermal energy is stored in the geothermal reservoir. Thermal fluid is extracted from the geothermal reservoir through the geothermal well. The energy-consuming facilities utilize the geothermal energy carried in the thermal fluid to operate. The tailwater generated during the geothermal energy utilization process is reinjected into the tailwater reservoir through the tailwater reinjection well. The tailwater reinjection device uses supplementary energy to reinject the tailwater stored in the tailwater reservoir back into the geothermal reservoir. Using tailwater reservoirs to store geothermal tailwater eliminates the need for surface-level storage facilities, improving the economic feasibility of geothermal systems and reducing limitations on energy storage capacity. It can be used for deep, high-temperature geothermal energy, enabling large-scale development. It offers large storage capacity at low cost, adapting to grid-level energy storage applications. Energy storage and extraction cycles are flexible. It can be combined with wind and solar energy technologies to improve renewable energy utilization. It has wide adaptability, allowing use in areas with low geothermal gradients. It is environmentally friendly and can be rapidly applied in oilfields with existing exploration and development data, enabling the utilization of geological assets in older oilfields. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0026] Figure 1 This is a schematic diagram of the structure of a multi-stratum geothermal development and energy storage system provided in an embodiment of the present invention;

[0027] Figure 2 A schematic diagram of the structure of a multi-stratum geothermal development and energy storage system provided in another embodiment of the present invention;

[0028] Figure 3 A schematic diagram of the structure of a multi-stratum geothermal development and energy storage system provided in another embodiment of the present invention;

[0029] Figure 4 A schematic diagram of the structure of a multi-stratum geothermal development and energy storage system provided in another embodiment of the present invention;

[0030] Figure 5 A schematic diagram of the structure of a multi-stratum geothermal development and energy storage system provided in another embodiment of the present invention;

[0031] Figure 6 This is a schematic diagram of the structure of a multi-stratum geothermal development and energy storage system provided in another embodiment of the present invention.

[0032] The accompanying drawings have illustrated specific embodiments of the invention, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of this application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to this application are not shown or described in the specification. This is to avoid obscuring the core parts of this application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0034] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0035] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. Unless otherwise specified, the terms "connection" and "linkage" used in this application include both direct and indirect connections (linkages).

[0036] Example 1

[0037] Figure 1 This is a schematic diagram of a multi-stratum geothermal development and energy storage system provided in an embodiment of the present invention. Figure 1 As shown, the multi-stratum geothermal development and energy storage system provided in this embodiment may include: a geothermal reservoir 1, a common stratum 2, a tailwater reservoir 3, a geothermal well 4, an energy consumption facility 5, a tailwater reinjection well 6, and a tailwater reinjection device 7. The bottom of the geothermal well 4 is located in the geothermal reservoir 1, and the bottom of the tailwater reinjection well 6 is located in the tailwater reservoir 3. The depth of the geothermal reservoir 1 is greater than that of the tailwater reservoir 3, and the porosity and permeability of the geothermal reservoir 1 and the tailwater reservoir 3 are higher than those of the common stratum 2. Geothermal energy is stored in the geothermal reservoir 1. Thermal fluid is extracted from the geothermal reservoir 1 through the geothermal well 4. The energy consumption facility 5 utilizes the geothermal energy carried in the thermal fluid for operation. The tailwater generated during the geothermal energy utilization process is reinjected into the tailwater reservoir 3 through the tailwater reinjection well 6. The tailwater reinjection device 7 uses supplementary energy to reinject the tailwater stored in the tailwater reservoir 3 back into the geothermal reservoir 1.

[0038] Ordinary formations are those excluding geothermal reservoirs and tailwater reservoirs, and supplementary energy can be other renewable energy sources besides geothermal energy. Geothermal well 4 is a geothermal water extraction well or steam extraction well.

[0039] The rocks that make up geological strata have a certain porosity, allowing them to hold a certain amount of fluid. The fluid pressure within these pores can vary within a certain range, and the pores may not completely fill, exhibiting an unsaturated state. Therefore, geological strata can hold a certain amount of fluid, serving as storage space. Changes in fluid volume manifest as variations in fluid saturation and formation pore pressure. Utilizing this characteristic, multiple strata with good sealing conditions can be selected at the same location and designated as geothermal reservoirs and tailwater reservoirs, respectively. Geothermal and tailwater reservoirs have higher porosity and permeability than surrounding ordinary strata, enabling them to hold a certain volume of water or steam. Shallower strata are designated as tailwater reservoirs, and deeper strata as geothermal reservoirs. Water injected into the tailwater reservoir flows into the geothermal reservoir under gravity and artificial pressurization, replenishing the fluid within and gradually heating it to become new extractable hot water or steam. Since the pore pressure and fluid saturation of the tailwater reservoir and the geothermal reservoir can vary independently, they can each accommodate different amounts of fluid, thus forming two relatively independent fluid storage spaces, equivalent to a high-level reservoir and a low-level reservoir.

[0040] Water injected into a geothermal reservoir using supplemental energy is heated within the reservoir. As the total injected volume increases, the pore pressure within the reservoir also increases. The internal energy of the injected water increases with both temperature and pressure. This increase in internal energy comes partly from heat absorbed from the geothermal strata, manifested as a rise in water temperature, and partly from the energy consumed during the pressurized injection process, manifested as a rise in pressure. The increased bottom-hole pressure of the geothermal well (geothermal water well or steam well) reduces the energy consumption required to extract the hot fluid. When the bottom-hole pressure is high enough to pressurize the wellhead, no energy is needed to extract the hot fluid; the fluid pressure at the wellhead can still drive the energy-consuming facilities. Regardless of whether the wellhead fluid is pressurized, the energy consumption for fluid extraction by the geothermal energy-consuming facilities decreases while the energy output increases. In this process, the supplementary energy consumed by pressurizing and injecting water into the geothermal reservoir is stored as the fluid pressure in the geothermal reservoir increases. A portion of this energy is consumed during the fluid flow in the geothermal reservoir, and the remainder is manifested as the internal energy of the geothermal fluid due to the increased pressure. Ultimately, this energy is extracted back to the surface and released for utilization when the geothermal fluid is extracted.

[0041] Although the installed capacity of renewable energy power generation such as wind and solar power has developed rapidly in recent years, it suffers from inherent power fluctuation problems. The mismatch between power generation and electricity demand at different times leads to significant curtailment of wind and solar power. Wind and solar power generation have low annual utilization hours, resulting in low effective utilization rates. To improve the utilization rate of renewable energy sources such as wind and solar power and avoid the large-scale waste of unstable renewable energy generation, this embodiment can use wind energy during curtailment periods and solar energy during curtailment periods as supplementary energy. During periods of low electricity prices, inexpensive grid electricity can be used as supplementary energy. In summary, the supplementary energy in this embodiment can include: wind energy during curtailment periods, solar energy during curtailment periods, and grid electricity during periods of low electricity prices.

[0042] By introducing supplementary energy to overcome the seepage resistance of deep strata, the injection-production cycle of deep strata can be realized, thereby effectively developing deep high-temperature geothermal resources. The effective utilization of deep high-temperature geothermal resources is key to improving the efficiency and scale of geothermal utilization. The energy utilization methods of geothermal systems can be divided into two main categories: direct thermal energy utilization and power generation utilization. When used for power generation, the higher the fluid temperature, the higher the power generation efficiency. Shallow geothermal resources, due to their lower fluid temperature, have low power generation efficiency and can only be utilized for direct thermal energy utilization. Direct thermal energy utilization is limited by the distance of hot fluid transportation, and can only be used for local residential heating, greenhouse aquaculture, fishponds, and other industries, making it difficult to expand the scale of geothermal resource development and obtain better economic benefits. Power generation utilization, on the other hand, can utilize power transmission and distribution networks to supply more users in more distant industries. The effective development of deep high-temperature geothermal energy is crucial for the large-scale development of geothermal resources. The multi-stratum geothermal development and energy storage system provided in this embodiment can be used for deep high-temperature geothermal energy, enabling large-scale geothermal energy development.

[0043] Once drilling reaches a sufficient depth, the formation temperature can meet the requirements for geothermal utilization. Therefore, by simply finding a shallow tailwater reservoir with high porosity, without requiring a high geothermal gradient, the multi-stratum geothermal development and storage system provided in this embodiment can be used to introduce supplementary energy, overcome the difficulties of tailwater reinjection caused by excessively deep geothermal reservoirs, and overcome the system energy consumption caused by formation seepage resistance, thus enabling the effective development of local geothermal resources. The multi-stratum geothermal development and storage system provided in this embodiment has wide adaptability and can be used in areas with low geothermal gradients. Moreover, by using a tailwater reservoir to store geothermal tailwater, there is no need to construct geothermal tailwater storage facilities on the surface, improving the economic feasibility of the geothermal system and reducing the limitations on the energy storage capacity of the geothermal system.

[0044] The fluid volume of geothermal reservoirs can easily reach 10 6 m 3 If calculated based on a temperature difference of 90℃, every 10 6 m 3The energy released as the water temperature decreases is approximately 3.77 × 10⁻⁶. 11 kJ is equivalent to approximately 100 million kilowatt-hours of electricity. Even with a power generation efficiency of only 15%, 15 million kilowatt-hours of electricity can be obtained. The current optimistic cost estimate for battery energy storage systems is 1.0 yuan / (W·h), or 1000 yuan / (kW·h). Construction costs account for 83%, while operation and maintenance costs and financial costs account for 17%. Therefore, a lithium battery energy storage system capable of storing 15 million kilowatt-hours of electricity would require approximately 12.5 billion yuan in construction costs. If large-scale construction of lithium battery energy storage systems is undertaken, the prices of resources such as lithium and nickel will rise significantly, becoming an insurmountable resource bottleneck. The multi-stratum geothermal development and energy storage system provided in this embodiment has a construction cost far lower than that of battery energy storage systems, reaching a fraction of the cost of a lithium battery energy storage system of the same scale. It is a realistic and feasible grid-scale energy storage technology. The multi-stratum geothermal development and energy storage system provided in this embodiment offers large-scale energy storage at low cost and is suitable for grid-scale energy storage applications.

[0045] The multi-stratum geothermal development and energy storage system provided in this embodiment can utilize low-priced grid electricity during off-peak nighttime hours for cross-day energy storage; it can also utilize wind power, which is difficult to connect to the grid during winter's low energy demand period, for cross-seasonal energy storage; and it can also utilize solar power, which is difficult to connect to the grid during periods of curtailment, for cross-seasonal energy storage. Furthermore, geothermal energy extraction can be performed at any time as needed, provided that there is still recoverable thermal fluid in the geothermal reservoir. Therefore, the energy storage and extraction cycle of the multi-stratum geothermal development and energy storage system provided in this embodiment is flexible.

[0046] The multi-stratum geothermal development and energy storage system provided in this embodiment utilizes wind energy during periods of wind curtailment and solar energy during periods of solar curtailment as supplementary energy sources. Combined with wind and solar energy technologies, this improves the utilization rate of renewable energy. It effectively utilizes waste wind and solar energy, enabling the storage and re-extraction of these energy sources, reducing waste from wind and solar curtailment, and increasing their utilization rate. Furthermore, as the utilization rate of the renewable energy system improves, its economic feasibility also increases, allowing for the further expansion of wind and solar energy development and increasing the proportion of renewable energy in primary energy consumption.

[0047] Compared to battery energy storage technology, the multi-stratum geothermal development and energy storage system provided in this embodiment does not face the bottleneck problem of non-ferrous metal resources, will not compete with other sectors of the national economy for scarce resources, does not consume rare metals such as lithium, cobalt, and nickel, and does not discharge geothermal wastewater, making it quite environmentally friendly. Moreover, it can be rapidly applied in oilfield areas with existing exploration and development data, enabling the geological assets of old oilfields to be utilized effectively.

[0048] The multi-stratum geothermal development and energy storage system provided in this embodiment includes: a geothermal reservoir, a common stratum, a tailwater reservoir, a geothermal well, energy-consuming facilities, a tailwater reinjection well, and a tailwater reinjection device. The bottom of the geothermal well is located in the geothermal reservoir, and the bottom of the tailwater reinjection well is located in the tailwater reservoir. The depth of the geothermal reservoir is greater than that of the tailwater reservoir, and the porosity and permeability of the geothermal reservoir and the tailwater reservoir are higher than those of the common stratum. Geothermal energy is stored in the geothermal reservoir. Thermal fluid is extracted from the geothermal reservoir through the geothermal well. The energy-consuming facilities utilize the geothermal energy carried in the thermal fluid to operate. The tailwater generated during the geothermal energy utilization process is reinjected into the tailwater reservoir through the tailwater reinjection well. The tailwater reinjection device uses supplementary energy to reinject the tailwater stored in the tailwater reservoir back into the geothermal reservoir. Using tailwater reservoirs to store geothermal tailwater eliminates the need for surface-level storage facilities, improving the economic feasibility of geothermal systems and reducing limitations on energy storage capacity. It can be used for deep, high-temperature geothermal energy, enabling large-scale development. It offers large storage capacity at low cost, adapting to grid-level energy storage applications. Energy storage and extraction cycles are flexible. It can be combined with wind and solar energy technologies to improve renewable energy utilization. It has wide adaptability, allowing use in areas with low geothermal gradients. It is environmentally friendly and can be rapidly applied in oilfields with existing exploration and development data, enabling the utilization of geological assets in older oilfields.

[0049] Based on Example 1, the following will use several specific examples to further describe in detail the tailwater reinjection device in a multi-stratum geothermal development and energy storage system.

[0050] Example 2

[0051] Figure 2 This is a schematic diagram of a multi-stratum geothermal development and energy storage system provided in another embodiment of the present invention. Figure 2 As shown, the multi-stratum geothermal development and energy storage system provided in this embodiment may include: a geothermal reservoir 1, a common stratum 2, a tailwater reservoir 3, a geothermal well 4, an energy consumption facility 5, a tailwater reinjection well 6, and a tailwater reinjection device 7. The bottom of the geothermal well 4 is located in the geothermal reservoir 1, and the bottom of the tailwater reinjection well 6 is located in the tailwater reservoir 3. The depth of the geothermal reservoir 1 is greater than that of the tailwater reservoir 3, and the porosity and permeability of the geothermal reservoir 1 and the tailwater reservoir 3 are higher than those of the common stratum 2. Geothermal energy is stored in the geothermal reservoir 1. The geothermal fluid is extracted from the geothermal reservoir 1 through the geothermal well 4. The energy consumption facility 5 uses the geothermal energy carried in the geothermal fluid to operate. The tailwater generated during the geothermal energy utilization process is reinjected into the tailwater reservoir 3 through the tailwater reinjection well 6. The tailwater reinjection device 7 uses supplementary energy to reinject the tailwater stored in the tailwater reservoir 3 back into the geothermal reservoir 1.

[0052] The tailwater reinjection device 7 includes: a water replenishment pumping well 711, a water replenishment pumping station and control facilities 712, and a water replenishment injection well 713. The bottom of the water replenishment pumping well 711 is located in the tailwater reservoir 3, and the bottom of the water replenishment injection well 713 is located in the geothermal reservoir 1. The water replenishment pumping station and control facilities 712 uses supplementary energy to extract tailwater from the tailwater reservoir 3 through the water replenishment pumping well 711, pressurizes it, and injects it into the geothermal reservoir 1 through the water replenishment injection well 713.

[0053] When geothermal energy is needed, hot water or steam is extracted from geothermal reservoir 1 by geothermal well 4, utilized in energy-consuming facility 5, and then the tailwater is reinjected into tailwater reservoir 3 via tailwater reinjection well 6. During the off-peak season of winter electricity demand, wind power that is difficult to connect to the grid, i.e. wind energy during the curtailment period, can be used as supplementary energy; or grid electricity during the nighttime low electricity price period can be used as supplementary energy. Using supplementary energy, tailwater is extracted from tailwater reservoir 3 via water replenishment pumping well 711, pressurized, and injected into geothermal reservoir 1 via water replenishment injection well 713 to replenish the geothermal reservoir fluid and increase the saturation and pressure of the geothermal reservoir fluid.

[0054] Water injected into the geothermal reservoir using supplemental energy is heated within the reservoir. As the total injected volume increases, the pore pressure within the geothermal reservoir also increases. The internal energy of the injected water increases with both temperature and pressure. This increase in internal energy comes partly from heat absorbed from the geothermal formation, manifested as a rise in water temperature; and partly from energy consumed during the pressurized injection process, manifested as a rise in pressure. The latter portion of energy is highest at the bottom of the supplemental injection well 713 and is partially consumed as water flows from 713 to geothermal well 4. This consumed energy offsets the formation seepage resistance. The remaining energy is manifested as the bottomhole fluid pressure of geothermal well 4. This bottomhole fluid pressure causes the wellbore fluid level of geothermal well 4 to rise (i.e., the rise of the "dynamic fluid level" in oilfield development). When this bottomhole fluid pressure exceeds the static fluid column pressure of the well, the wellhead fluid becomes pressurized. Although this system consumes some supplemental energy to overcome formation seepage resistance, it can effectively develop some geothermal resources that are difficult to exploit due to high water injection energy consumption. Furthermore, because the fluids in the geothermal reservoir are replenished and pressurized, it allows for the extraction of hot water or steam at higher flow rates, thus enabling larger-scale development of geothermal energy.

[0055] This embodiment provides a multi-stratum geothermal development and energy storage system that utilizes multiple strata at different depths to store water or steam, with deeper strata serving as geothermal reservoirs and shallower strata as tailwater reservoirs. Hot water or steam is extracted from the geothermal reservoirs to extract geothermal energy. When inexpensive supplementary energy is available, geothermal tailwater is pressurized and reinjected into the geothermal reservoirs. During periods without inexpensive supplementary energy, the geothermal tailwater is injected into the tailwater reservoir. This invention can increase the economic scale of geothermal development. Simultaneously, the increased fluid pressure in the geothermal reservoirs allows a portion of the supplementary energy to be stored and retrieved again during geothermal fluid extraction. Pressurized reinjection of geothermal tailwater increases the fluid saturation and pressure in the geothermal reservoirs, storing a portion of the consumed supplementary energy. During geothermal fluid extraction, the increased fluid pressure increases the energy output of the geothermal system, thereby releasing the stored energy. Furthermore, by overcoming the seepage resistance of the geothermal reservoirs with supplementary energy, the scale of geothermal development can be increased, improving the economic viability of developing deep, high-temperature geothermal resources.

[0056] Example 3

[0057] Figure 3 This is a schematic diagram of a multi-stratum geothermal development and energy storage system provided in another embodiment of the present invention. Figure 3 As shown, the multi-stratum geothermal development and energy storage system provided in this embodiment may include: a geothermal reservoir 1, a common stratum 2, a tailwater reservoir 3, a geothermal well 4, an energy consumption facility 5, a tailwater reinjection well 6, and a tailwater reinjection device 7. The bottom of the geothermal well 4 is located in the geothermal reservoir 1, and the bottom of the tailwater reinjection well 6 is located in the tailwater reservoir 3. The depth of the geothermal reservoir 1 is greater than that of the tailwater reservoir 3, and the porosity and permeability of the geothermal reservoir 1 and the tailwater reservoir 3 are higher than those of the common stratum 2. Geothermal energy is stored in the geothermal reservoir 1. The geothermal fluid is extracted from the geothermal reservoir 1 through the geothermal well 4. The energy consumption facility 5 uses the geothermal energy carried in the geothermal fluid to operate. The tailwater generated during the geothermal energy utilization process is reinjected into the tailwater reservoir 3 through the tailwater reinjection well 6. The tailwater reinjection device 7 uses supplementary energy to reinject the tailwater stored in the tailwater reservoir 3 back into the geothermal reservoir 1.

[0058] The tailwater reinjection device 7 includes: a pressurization pump control facility 721 and a water injection well 722, with the bottom of the water injection well 722 located in the geothermal reservoir 1; a submersible pressurization pump 723 is installed in the water injection well 722 at a position in the tailwater reservoir 3 and near the bottom of the tailwater reservoir 3; the pressurization pump control facility 721 controls the submersible pressurization pump 723 to use supplementary energy to draw tailwater from above and discharge it downwards after pressurization; in the part of the water injection well 722 located in the geothermal reservoir 1, one or more radial drilling wellbores 724 are constructed to connect the water injection well 722 with the water flow channel of the geothermal reservoir 1.

[0059] Submersible booster pumps should not be installed too high. In this embodiment, the submersible booster pump is installed near the bottom of the tailrace reservoir, so that even when the water volume in the tailrace reservoir is not sufficient, the submersible booster pump can still successfully pump the tailrace.

[0060] The multi-stratum geothermal development and energy storage system provided in this embodiment involves installing a submersible booster pump 723 at an appropriate depth in the water injection well 722. Radial drilling is then performed on the portion of the water injection well 722 located within the geothermal reservoir 1, constructing one or more radial wellbores 724. The submersible booster pump 723 can extract water from above, pressurize it, and discharge it downwards. The radial wellbores 724 serve as water flow channels connecting the water injection well 722 and the geothermal reservoir 1, facilitating the flow of water from the water injection well 722 into the geothermal reservoir 1. During peak daytime energy consumption periods, hot water or steam is extracted from the geothermal reservoir 1 by the geothermal well 4, utilized in the energy consumption facility 5, and then the tailwater is reinjected into the tailwater reservoir 3 via the tailwater reinjection well 6. During the nighttime low electricity price period, the grid power is used as a supplementary energy source. The submersible pressurization pump 723 is started to pressurize and inject water into the geothermal reservoir 1 to replenish the geothermal reservoir fluid and increase the fluid saturation and fluid pressure of the geothermal reservoir.

[0061] Example 4

[0062] Figure 4 This is a schematic diagram of a multi-stratum geothermal development and energy storage system provided in another embodiment of the present invention. Figure 4 As shown, the multi-stratum geothermal development and energy storage system provided in this embodiment may include: a geothermal reservoir 1, a common stratum 2, a tailwater reservoir 3, a geothermal well 4, an energy consumption facility 5, a tailwater reinjection well 6, and a tailwater reinjection device 7. The bottom of the geothermal well 4 is located in the geothermal reservoir 1, and the bottom of the tailwater reinjection well 6 is located in the tailwater reservoir 3. The depth of the geothermal reservoir 1 is greater than that of the tailwater reservoir 3, and the porosity and permeability of the geothermal reservoir 1 and the tailwater reservoir 3 are higher than those of the common stratum 2. Geothermal energy is stored in the geothermal reservoir 1. The geothermal fluid is extracted from the geothermal reservoir 1 through the geothermal well 4. The energy consumption facility 5 uses the geothermal energy carried in the geothermal fluid to operate. The tailwater generated during the geothermal energy utilization process is reinjected into the tailwater reservoir 3 through the tailwater reinjection well 6. The tailwater reinjection device 7 uses supplementary energy to reinject the tailwater stored in the tailwater reservoir 3 back into the geothermal reservoir 1.

[0063] The tailwater reinjection device 7 includes a booster pump control facility 731 and a water injection well 732, with the bottom of the water injection well 732 located in the geothermal reservoir 1. Hydraulic fracturing is performed in the water injection well 732 to construct one or more hydraulic fracturing fractures 733 connecting the tailwater reservoir 3 and the geothermal reservoir 1, so that the tailwater in the tailwater reservoir 3 flows into the geothermal reservoir 1 through the hydraulic fracturing fractures 733. A submersible booster pump 734 is installed at a preset position in the water injection well 732, and the booster pump control facility 731 controls the submersible booster pump 734 to use supplementary energy to draw tailwater from above and discharge it downwards after pressurization.

[0064] The multi-stratum geothermal development and storage system provided in this embodiment involves hydraulic fracturing in the water injection well 732 to construct one or more hydraulic fracturing fractures 733 that connect the tailwater reservoir 3 and the geothermal reservoir 1. The hydraulic fracturing fractures 733 allow water from the tailwater reservoir 3 to flow into the geothermal reservoir 1. A submersible pressurization pump 734 is installed at an appropriate depth in the water injection well 732. The submersible pressurizes the water, drawing water from above and discharging it downwards. When geothermal energy is needed, hot water or steam is extracted from the geothermal reservoir 1 by the geothermal well 4, utilized in the energy consumption facility 5, and then the tailwater is reinjected into the tailwater reservoir 3 via the tailwater reinjection well 6. Water from the tailwater reservoir 3 continuously flows downwards into the geothermal reservoir 1 through the hydraulic fracturing fractures 733. During periods when cheap supplemental energy is available, the submersible pressurization pump 734 is activated using supplemental energy to pressurize and inject water into the geothermal reservoir 1, replenishing the geothermal reservoir fluid and increasing the fluid saturation and pressure of the geothermal reservoir.

[0065] Example 5

[0066] Figure 5 This is a schematic diagram of a multi-stratum geothermal development and energy storage system provided in another embodiment of the present invention. Figure 5 As shown, the multi-stratum geothermal development and energy storage system provided in this embodiment may include: a geothermal reservoir 1, a common stratum 2, a tailwater reservoir 3, a geothermal well 4, an energy consumption facility 5, a tailwater reinjection well 6, and a tailwater reinjection device 7. The bottom of the geothermal well 4 is located in the geothermal reservoir 1, and the bottom of the tailwater reinjection well 6 is located in the tailwater reservoir 3. The depth of the geothermal reservoir 1 is greater than that of the tailwater reservoir 3, and the porosity and permeability of the geothermal reservoir 1 and the tailwater reservoir 3 are higher than those of the common stratum 2. Geothermal energy is stored in the geothermal reservoir 1. The geothermal fluid is extracted from the geothermal reservoir 1 through the geothermal well 4. The energy consumption facility 5 uses the geothermal energy carried in the geothermal fluid to operate. The tailwater generated during the geothermal energy utilization process is reinjected into the tailwater reservoir 3 through the tailwater reinjection well 6. The tailwater reinjection device 7 uses supplementary energy to reinject the tailwater stored in the tailwater reservoir 3 back into the geothermal reservoir 1.

[0067] Given the geological conditions of having both hot dry rock formations and tailwater reservoirs, hot dry rock formations can be used as geothermal reservoirs. For example... Figure 5 As shown, the geothermal reservoir 1 in this embodiment is a hot dry rock formation, formed by hydraulic fracturing to create artificial fractures. The tailwater reinjection device 7 includes a booster pump control facility 741 and a water injection well 742. The water injection well 742 is a horizontal well, with its horizontal section located within the hot dry rock formation. The geothermal well 4 in this embodiment is also a horizontal well, but the depth of its horizontal section is lower than that of the water injection well. A submersible booster pump 743 is installed at a predetermined location on the water injection well 742. The booster pump control facility 741 controls the submersible booster pump 743 to draw tailwater from above using supplemental energy, pressurize it, and then discharge it downwards.

[0068] The multi-stratum geothermal development and energy storage system provided in this embodiment, in areas with dry hot rock strata and tailwater reservoir geological conditions, first drills a horizontal well as a water injection well 742, with its horizontal section located in the dry hot rock strata. Then, hydraulic fracturing is performed in the dry hot rock strata to construct a set of artificial fractures 744. Influenced by the artificial fractures 744, the fluid seepage capacity is enhanced in a certain area, forming an artificial geothermal reservoir capable of accommodating a certain amount of fluid. Next, another horizontal well is drilled as a geothermal well (geothermal water well or steam well) 4. The horizontal section of geothermal well 4 is lower than that of the water injection well 742 and passes through the artificial geothermal reservoir.

[0069] During peak energy consumption periods, hot water or steam is extracted from the artificial geothermal reservoir by geothermal well 4 and utilized in energy consumption facility 5. The tailwater is then reinjected into tailwater reservoir 3 via tailwater reinjection well 6. During periods when inexpensive supplemental energy is available, submersible booster pump 743 is activated to pressurize and inject water into the artificial geothermal reservoir, rapidly replenishing the reservoir fluid and increasing its fluid saturation and pressure. The water injected into the artificial geothermal reservoir is heated by the dry hot rock strata 1, becoming an extractable geothermal fluid, and its increased pressure stores a portion of the supplemental energy. When the geothermal fluid is extracted and utilized again, this stored supplemental energy is released back into the energy consumption facility.

[0070] Example 6

[0071] Please refer to Figure 6 To further improve energy efficiency, in the multi-stratum geothermal development and storage system provided in this embodiment, based on any of the above embodiments, a tailwater storage tank 8 is also installed between the energy-consuming facility 5 and the tailwater reinjection well 6 to store the geothermal tailwater generated by the energy-consuming facility 5 within a preset time period. A reinjection pump 9 is installed in the tailwater storage tank, and the reinjection pump 9 uses supplementary energy to reinject the tailwater stored in the tailwater storage tank back to the tailwater reservoir 3 via the tailwater reinjection well 6. It should be noted that the tailwater reinjection device 7 in this embodiment can be the tailwater reinjection device provided in any of the above embodiments.

[0072] By setting up a tailwater storage tank 8 for storing geothermal tailwater generated by energy-consuming facility 5 within a preset time period (e.g., 1 day), the injection of water into tailwater reservoir 3 and the extraction of water from geothermal reservoir 1 do not need to be carried out simultaneously. This allows water to be injected into tailwater reservoir 3 during periods when inexpensive supplemental energy is available, while hot water or steam can be extracted from geothermal reservoir 1 as needed for energy consumption.

[0073] Specifically, during peak daytime energy consumption periods, hot water or steam can be extracted from geothermal reservoir 1 by geothermal well 4 and utilized in energy-consuming facility 5, with the tailwater temporarily stored in tailwater storage tank 8. During low-cost nighttime periods, the reinjection pump 8 is activated using low-cost grid electricity, and the tailwater from tailwater storage tank 8 is reinjected into tailwater reservoir 3 via tailwater reinjection well 6. Water in tailwater reservoir 3 is then reinjected into geothermal reservoir 1 through tailwater reinjection device 7. This further improves the efficiency of energy storage and geothermal energy utilization across day and night and across seasons.

[0074] The various embodiments in this disclosure are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0075] The scope of protection of this disclosure is not limited to the embodiments described above. Obviously, those skilled in the art can make various modifications and variations to this disclosure without departing from its scope and spirit. If such modifications and variations fall within the scope of the claims of this disclosure and their equivalents, then the intent of this disclosure also includes such modifications and variations.

Claims

1. A multi-stratum geothermal development and energy storage system, characterized in that, include: The geothermal reservoir, ordinary formation, tailwater reservoir, geothermal well, energy-consuming facilities, tailwater reinjection well and tailwater reinjection device, wherein the bottom of the geothermal well is located in the geothermal reservoir, the bottom of the tailwater reinjection well is located in the tailwater reservoir, the depth of the geothermal reservoir is greater than that of the tailwater reservoir, and the porosity and permeability of the geothermal reservoir and the tailwater reservoir are higher than those of the ordinary formation; The geothermal reservoir stores geothermal energy. The geothermal well extracts hot fluid from the geothermal reservoir. The energy-consuming facility uses the geothermal energy carried in the hot fluid to operate. The tailwater generated during the geothermal energy utilization process is reinjected into the tailwater reservoir through the tailwater reinjection well. The tailwater reinjection device uses supplemental energy to reinject the tailwater stored in the tailwater reservoir back into the geothermal reservoir.

2. The system according to claim 1, characterized in that, The supplementary energy sources include: wind energy during periods of wind curtailment, solar energy during periods of solar curtailment, and grid power during periods of low electricity prices.

3. The system according to claim 1, characterized in that, The tailwater reinjection device includes: a water replenishment pumping well, a water replenishment pumping station and control facilities, and a water replenishment injection well. The bottom of the water replenishment pumping well is located in the tailwater reservoir, and the bottom of the water replenishment injection well is located in the geothermal reservoir. The replenishment pumping station and control facilities utilize the replenishment energy to extract tailwater from the tailwater reservoir via the replenishment pumping well, pressurize it, and then inject it into the geothermal reservoir via the replenishment injection well.

4. The system according to claim 1, characterized in that, The tailwater reinjection device includes: a pressurization pump control facility and a water injection well, wherein the bottom of the water injection well is located in the geothermal reservoir; A submersible booster pump is installed at the location of the water injection well in the tailwater reservoir and near the bottom of the tailwater reservoir. The booster pump control facility controls the submersible booster pump to use the supplementary energy to draw tailwater from above and discharge it downwards after pressurization. In the portion of the water injection well located within the geothermal reservoir, one or more radial wellbores are constructed to connect the water injection well with the water flow channel of the geothermal reservoir.

5. The system according to claim 1, characterized in that, The tailwater reinjection device includes: a pressurization pump control facility and a water injection well, wherein the bottom of the water injection well is located in the geothermal reservoir; Hydraulic fracturing is performed in the water injection well to construct one or more hydraulic fracturing fractures connecting the tailwater reservoir and the geothermal reservoir, so that tailwater in the tailwater reservoir can flow into the geothermal reservoir through the hydraulic fracturing fractures. A submersible booster pump is installed at a predetermined location in the water injection well. The booster pump control facility controls the submersible booster pump to use the supplementary energy to draw tailwater from above and discharge it downwards after pressurization.

6. The system according to claim 1, characterized in that, When the geothermal reservoir is a dry hot rock formation, the geothermal reservoir is formed by hydraulic fracturing of the dry hot rock formation to create artificial fractures; The tailwater reinjection device includes a booster pump control facility and a water injection well. The water injection well is a horizontal well, and the horizontal section is located in the dry hot rock stratum. The geothermal well is a horizontal well, and the depth of the horizontal section of the geothermal well is lower than the depth of the horizontal section of the water injection well; A submersible booster pump is installed at a predetermined location in the water injection well. The booster pump control facility controls the submersible booster pump to use the supplementary energy to draw tailwater from above and discharge it downwards after pressurization.

7. The system according to any one of claims 1-6, characterized in that, A tailwater storage tank is installed between the energy-consuming facility and the tailwater reinjection well to store the geothermal tailwater generated by the energy-consuming facility within a preset time period. The tailwater storage tank is equipped with a reinjection pump, which uses the supplementary energy to reinject the tailwater stored in the tailwater storage tank back into the tailwater reservoir via the tailwater reinjection well.

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