CN115828539A - Method for improving energy recovery efficiency of salt water layer compressed air energy storage underground - Google Patents
Method for improving energy recovery efficiency of salt water layer compressed air energy storage underground Download PDFInfo
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention provides a method for improving the efficiency of energy recovery underground by brine layer compressed air energy storage, which comprises the steps of finding out the deep geological condition and the property of a target site, and determining the position, the structure and the property of a target gas storage brine layer, a cover layer and an underlying stratum; determining a design scheme of a U-shaped working well by utilizing numerical simulation calculation, and selecting the design scheme of the U-shaped working well with high recovery efficiency, wherein the U-shaped working well comprises a U-shaped outer well and a U-shaped inner well, the U-shaped outer well is provided with a perforation, the U-shaped inner well is arranged in the U-shaped outer well, and the U-shaped inner well and the U-shaped outer well both extend to an underlying stratum; according to the selected design scheme of the U-shaped working well, performing site drilling and well completion construction; arranging devices of the earth surface energy storage system to form a whole set of energy storage system; the invention realizes that redundant underground heat supplement is obtained to increase the outlet temperature of the air at the wellhead under the condition of ensuring that the circulating pressure is not changed, thereby increasing the underground energy recovery efficiency.
Description
Technical Field
The invention belongs to the technical field of underground deep pore space utilization and new energy storage, and particularly relates to a method for improving underground energy recovery efficiency of salt water layer compressed air energy storage.
Background
An important technical approach to the achievement of the dual carbon goal is energy structure transformation, which changes from traditional fossil energy to a system based on clean and renewable energy. The wind and light installed machine power generation realizes large-span growth in nearly two years, and different regions and departments reasonably utilize wind and light resources which can be adapted in the regions. However, the important pain point of the wind and light grid-connected power generation is that the resource itself has the characteristics of intermittence and randomness, and the requirement of power supply safety and stability is difficult to meet.
The large-scale energy storage technology is the first choice method for solving the problem of stable power supply of wind and light at present, and the whole set of system aiming at wind, light and energy storage starts to be developed in a large range domestically and internationally. The traditional pumped storage has mature technology, the efficiency is more than 70 percent, and the pumped storage accounts for most of large-scale energy storage projects in the world, but the pumped storage has certain requirements on the terrain and water resources, and has certain influence on the environment. At present, another large-scale physical energy storage technology compressed air energy storage is developed at a very fast speed, and particularly, a system for storing air by utilizing underground deep space has small occupied area and long energy storage time. Compared with the salt cavern space, the deep underground saline water layer has been proved to be capable of storing gas, and the energy storage space and potential are huge due to wide distribution of the saline water layer, so that the deep underground saline water layer becomes a major research focus of large-scale energy storage in the world.
A key issue in using a saline aquifer for energy storage is the efficiency of underground energy recovery. At present, the efficiency of underground energy recovery is generally about 80-90%, and how to further improve the efficiency so as to improve the applicability of the whole energy storage technology is a problem to be researched. From the prior art and research, the geothermal energy in the deep underground part has the potential to provide certain heat compensation for the energy storage process, and research proposes that one geothermal exploitation system is additionally arranged to heat the exploitation air at a well mouth, but the method needs to additionally increase the cost of the geothermal exploitation system and is a loose two-set system, or research proposes that the heat compensation of the periphery to the air is improved by putting the compressed air into a deeper reservoir, but the method has the defect that the pressure of air circulation is increased at the same time, and the overall efficiency of the compression equipment and the expander is influenced. It has not been seen how to develop a more compact and less costly method that can improve underground energy recovery efficiency without changing the cycle pressure.
Disclosure of Invention
According to the defects of the prior art, the invention aims to provide a method for improving the underground energy recovery efficiency of salt water layer compressed air energy storage, which realizes that redundant underground heat supplement is obtained to increase the outlet temperature of air at a wellhead under the condition of ensuring that the circulation pressure of the air is not changed by optimizing an energy storage working well per se, thereby increasing the underground energy recovery efficiency without additionally increasing a geothermal mining system.
In order to solve the technical problems, the invention adopts the technical scheme that:
a method for improving the underground energy recovery efficiency of salt water layer compressed air energy storage comprises the following steps:
s1, finding out deep geological conditions and properties of a target site, and determining the positions, structures and properties of a target gas storage, salt and water layer, a cover layer and an underburden;
s2, determining the design of the U-shaped working well by utilizing numerical simulation calculation, wherein the design comprises the steps of providing a plurality of U-shaped working well design schemes after the deep stratum condition is detected, carrying out site geological modeling by utilizing geological modeling software, carrying out numerical simulation on the plurality of U-shaped working well design schemes by utilizing a gas-water-heat well reservoir coupling simulator, analyzing pressure-temperature change in the cyclic process, calculating efficiency by utilizing an underground recovery energy formula, and selecting the U-shaped working well design scheme with high recovery efficiency, wherein the U-shaped working well comprises a U-shaped outer well and a U-shaped inner well, the U-shaped outer well is provided with a perforation, the U-shaped inner well is arranged in the U-shaped outer well and is spaced from the U-shaped outer well by a certain distance, and both the U-shaped inner well and the U-shaped outer well extend to the underlying stratum;
s3, according to the selected design scheme of the U-shaped working well, performing site drilling and well completion construction;
s4, arranging devices of the earth surface energy storage system to form a whole set of energy storage system, wherein the whole set of energy storage system comprises a heat storage device, a compressor system and an expander system;
s5, in the air injection process, air enters through the U-shaped well inner well, flows to the bottom of the U-shaped well inner well, enters between the U-shaped well outer well and the U-shaped well inner well, moves upwards, and finally enters into a target gas storage and salt water layer through a perforation on the U-shaped well outer well; in the process of air extraction, air enters between the U-shaped well outer well and the U-shaped well inner well from the target air storage saline water layer, moves downwards to the bottom of the well, then enters the U-shaped well inner well, and finally enters the well head upwards along the U-shaped well inner well, and the air is extracted.
Further, in the step S1, the deep geological condition detection range is 0 to 3000 meters, and the deep geological condition and the property of the target field are ascertained through well logging, vertical seismic profile testing, two-dimensional or three-dimensional seismic exploration, well drilling and pre-exploration, coring, interference testing, formation water chemical analysis and core displacement testing.
Further, in step S1, the principle of selecting a target gas storage saline water layer includes: the energy storage scale is reasonably matched with the reservoir closed structure, and the anticline or fault closed structure is adopted; the reservoir permeability needs to be more than 100md, the reservoir thickness needs to be more than 10m, and the porosity needs to be more than 0.1; the cover layer has good closure and integrity within a certain range, and the stability of the regional geological condition is good; the underburden has a greater temperature.
Further, in step S2, the design principle of the U-shaped working well is as follows: the U-shaped well is only completely jetted out within the depth range of the target gas storage saline water layer, and air and the U-shaped working well are allowed to enter and exit the reservoir layer in the process of energy storage and energy release; the drilling depth of the U-shaped working well is optimized according to various schemes of actual stratum drilling completion cost and recovery efficiency, but the temperature of the depth of the bottom of the U-shaped working well is at least more than 80 ℃.
Further, in step S2, the numerical simulation process is: the pressure and temperature simulation of gas produced at the wellhead in the actual field geological modeling and the operation process needs to be carried out, the two-dimensional radial model or three-dimensional modeling is selected according to the actual field geological modeling, the pressure and temperature of the outlet of the air after the circulation of the whole underground process are simulated, and a numerical simulation program T2WELL/EOS3 suitable for coupling of a gas-water-heat WELL barrel and a reservoir is adopted.
Further, in step S2, when calculating the underground energy recovery efficiency of each cycle process, neglecting the earth surface process, only considering the total energy ratio of the air when the WELL head is extracted and the air enters the WELL head, the specific enthalpy values at different times can be calculated by T2WELL/EOS3, and the underground energy recovery efficiency of a single cycle is calculated by using the following formula;
E efficiency ＝E pro /E inj (2)
wherein, E inj/pro For counting a single-cycle injection orTotal energy of extracted air, Q air Is the current injection or production flow, h (t) is the specific enthalpy for the corresponding time; e efficiency For single cycle underground energy recovery efficiency.
Further, in step S2, in the design process of the U-shaped working well, the diameter and the extension depth of the U-shaped outer well and the diameter and the extension depth of the U-shaped inner well need to be considered.
Further, in step S3, drilling needs to consider: the air tightness is ensured to be good under the high-temperature and high-pressure state; when cementing, the damage to the surrounding stratum is reduced; the sand control between the gas storage target layer and the outer layer wellbore is considered and the corrosion influence of the gas-water mixture in the aquifer on the well pipe is noticed.
Further, in the step S3, a section of space needs to be reserved at the bottom of the U-shaped well and the U-shaped well, so as to ensure that friction is reduced when the flow rate of the inner U-shaped well and the U-shaped well is exchanged; and an insulating layer is arranged at the periphery of the U-shaped well outside the well in a depth range with lower background temperature.
Further, in step S4, the compressor system includes a multistage compressor, a heat exchanger is disposed behind each stage of compressor, air behind each stage of compressor is cooled, and the heat of compression is stored by the heat storage device, and the expander system includes a multistage expander, and the heat of compression stored in the heat storage device is extracted by the heat exchanger in front of each stage of expander to heat the air.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) According to the invention, the U-shaped working well is adopted to design, so that the air can be supplemented through heat exchange between the deep well and the stratum under the condition of ensuring that the circulating pressure is not changed, the underground energy recovery efficiency is improved, and the benefit of the whole project can be increased and the large-scale popularization can be realized.
(2) Compared with salt caverns, the underground salt water layer space is used for storing gas, the distribution and application range is wider, compared with rock caverns and surface gas storage tanks, the gas storage scale and economy are better, the grid-connected safety of wind and light large-scale power generation can be greatly promoted, and the realization of 'carbon peak reaching and carbon neutralization' is facilitated.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the embodiments will be briefly described below, and obviously, the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a flow chart of an implementation of the present invention.
Fig. 2 is a general schematic diagram of a target air storage salt water layer compressed air energy storage system according to the present invention.
Fig. 3 is a schematic diagram of fluid movement in a conventional work well.
FIG. 4 is a schematic view of the fluid movement in a U-shaped working well after the improvement of the present invention.
FIG. 5 is a schematic view of fluid movement in another modified U-shaped well of the present invention.
Fig. 6 is a comparison of wellhead pressures for a conventional work well and a U-shaped work well of the present invention.
Fig. 7 is a comparison of wellhead temperatures for a conventional work well and a U-shaped work well of the present invention.
Fig. 8 is a graph comparing the underground energy recovery efficiency of a conventional work well and a U-shaped work well according to the present invention.
In the figure: 1-a photovoltaic power generation device; 2-a wind power generation device; 3-an electric motor; 4-a low pressure compressor; 5-a high-pressure compressor; 6-a first heat exchanger; 7-a second heat exchanger; 8-high temperature heating tank; 9-low temperature cooling tank; 10-a third heat exchanger; 11-a high pressure turbine; 12-a low pressure turbine; 13-a coaxial generator; 14-a fourth heat exchanger; 15-a first throttle valve; 16-a second throttle valve; 17-a working well; 18-an overburden; 19-a cap layer; 20-target gas and salt water storage layer; 21-an underburden; 22-initial balloon space; 23-U-shaped working well; a 24-U-shaped out-of-well; a 25-U shaped well.
Detailed Description
The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless otherwise specified.
The invention provides a method for improving the efficiency of energy recovery underground by using brine layer compressed air energy storage, which comprises the following steps as shown in figure 1:
s1, finding out deep geological conditions and properties of a target site, and determining the positions, structures and properties of a target gas storage and salt water layer 20, a cover layer 19 and an underburden 21;
s2, determining the design of the U-shaped working well 23 by utilizing numerical simulation calculation, wherein the design scheme of a plurality of U-shaped working wells 23 is given after the deep stratum condition is detected, site geological modeling is carried out by utilizing geological modeling software, a gas-water-heat well casing reservoir coupling simulator is used for carrying out numerical simulation on the design scheme of the plurality of U-shaped working wells 23, the pressure-temperature change in the circulation process is analyzed, the efficiency is calculated by utilizing an underground recovery energy formula, and the design scheme of the U-shaped working well 23 with high recovery efficiency is selected, wherein the U-shaped working well 23 comprises a U-shaped outer well 24 and a U-shaped inner well 25, the U-shaped outer well 24 is provided with a perforation, the U-shaped inner well 25 is arranged in the U-shaped outer well 24 and is spaced from the U-shaped outer well 24 by a certain distance, and both the U-shaped inner well 25 and the U-shaped outer well 24 extend to the underburden 21;
s3, according to the selected design scheme of the U-shaped working well 23, performing site drilling and well completion construction;
s4, arranging devices of the earth surface energy storage system to form a whole set of energy storage system, wherein the whole set of energy storage system comprises a heat storage device, a compressor system and an expander system;
s5, in the process of injecting air, air enters through the U-shaped well inner well 25, flows to the bottom of the U-shaped well inner well 25, enters between the U-shaped well outer well 24 and the U-shaped well inner well 25, moves upwards, and finally enters the target gas storage and saline water layer 20 through the perforation on the U-shaped well outer well 24; in the process of air extraction, air enters between the U-shaped well outer well 24 and the U-shaped well inner well 25 from the target air storage saline-water layer 20, moves downwards to the bottom of the well, enters the U-shaped well inner well 25, and finally enters the wellhead upwards along the U-shaped well inner well 25, and the air is extracted.
In the related art, the energy storage working well 17 directly goes deep into the target gas storage and salt water layer 20 for air injection and air extraction, generally about 80-90% from the viewpoint of efficiency of underground energy recovery, and cannot be further improved, and in the existing research, a set of geothermal exploitation system is additionally arranged to heat the air extracted from the wellhead, but the method needs to additionally increase the cost of the geothermal exploitation system and is a loose two-set system, or research also provides that the heat supplement of the periphery to the air is improved by putting compressed air into a deeper reservoir, but the method has the defect that the pressure of air circulation is increased at the same time, and the overall efficiency of the compression equipment and the expander is influenced.
The traditional working well 17 is shown in fig. 3, and is not divided into an inner shaft and an outer shaft, and the air injection process enters from the wellhead and moves downwards along the well to a target reservoir stratum; during air production, air flows from the reservoir into the wellbore, along the wellbore and into the wellhead.
As shown in figures 4 and 5, the invention optimizes the self energy storage working well by designing a new U-shaped working well 23, wherein the U-shaped working well 23 comprises a U-shaped outer well 24 and a U-shaped inner well 25, the U-shaped outer well 24 is provided with an open part, the U-shaped inner well 25 is arranged in the U-shaped outer well 24 and is spaced from the U-shaped outer well 24 by a certain distance, the U-shaped inner well 25 and the U-shaped outer well 24 both extend to the underburden 21, the U-shaped inner well 25 and the U-shaped outer well 24 form a heat supplementing section at the part of the underburden 21, the heat exchange between air and an external high-temperature stratum is prolonged in a deep heat stratum, the temperature is improved, the purpose that the redundant underground heat supplementing is obtained under the condition that the circulating pressure of the air is not changed, the outlet temperature of the air at a well head is increased, the underground energy recovery efficiency is increased, and an additional exploitation system is not needed.
The invention adopts the design of the U-shaped working well 23, under the condition of ensuring that the circulating pressure is not changed, the air can be supplemented with heat through the heat exchange between the deep well and the stratum, the underground energy recovery efficiency is improved, and the benefit of the whole project can be increased and the large-scale popularization can be realized.
Compared with a rock cave and an earth surface gas storage tank, the underground salt water layer space is used for storing gas, the distribution and application range is wider, the scale and economy of the gas storage are better, the problem of limitation of further efficiency improvement in underground energy storage is solved, the applicability of large-scale energy storage of the type is improved, the grid-connected safety of wind and light large-scale power generation can be greatly promoted, and the realization of 'carbon peak reaching and carbon neutralization' is facilitated.
In the invention, in step S1, the deep geological condition detection range is 0-3000 m, and the deep geological condition and the property of a target field are found out through well logging, vertical seismic profile testing, two-dimensional or three-dimensional seismic exploration, well drilling and pre-exploration, coring, interference test, formation water chemical analysis and core displacement experiment.
In the invention, in step S1, the positions of the target gas storage and salt-water layer 20 and the U-shaped out-of-well 24 outside diameter jet-opened are determined, and the selection principle of the target gas storage and salt-water layer 20 includes: the energy storage scale is reasonably matched with the reservoir closed structure, and the anticline or fault closed structure is adopted; the permeability of the reservoir is required to be more than 100md, the thickness of the reservoir is required to be more than 10m, and the porosity is required to be more than 0.1; the cover layer 19 has good closure and integrity within a certain range, and the stability of the regional geological condition is good.
As shown in fig. 1, in one embodiment of the invention, during the selection of the target gas, salt and water reservoir 20, the anticline structure, the high porosity, high permeability formation separated by faults, and the large volume of high permeability sandstone lens in the low permeability formation. Reservoir permeability and porosity were good: the permeability of the target gas storage and salt water layer 20 at least reaches more than 100mD, and the thickness of the reservoir is required to be more than 10m, so that the injectability and large-scale gas production can be met; the porosity is required to be more than 10%. The buried depth at the top of the reservoir is more than 600m. And (3) regional geological stability: earthquake activity in the area is weak, geological disaster activity is not frequent, and no large mining area exists. The lithology of the cover layer 19 is mainly mudstone, the thickness is larger than 10m, the permeability is smaller than 0.01Md, the breakthrough pressure of the cover layer 19 is 1.5-2.0 times of the hydrostatic pressure of the target gas storage and saline water layer 20, the thickness of the cover layer 19 is continuous within 2 times of the horizontal distance of a closed structure area, cracks and faults of the cover layer 19 do not develop, and no potential leakage channels such as abandoned wells and the like exist in the area.
In the present invention, in step S1, the underburden 21 has a greater temperature, thereby ensuring the efficiency of the heat exchange section and reducing the overall depth of the U-shaped working well 23.
In one embodiment of the invention, the depth of the heat exchange portion of U-shaped working well 23 of underburden 21 below target gas storage-brine layer 20 is within 3000m, the temperature at 3000 depth should generally be greater than 100 ℃, and no other petroleum and coal resources are available in the layer.
In step S2, the design principle of the U-shaped working well 23 is as follows: the U-shaped well 24 is completely opened only within the depth range of the target gas storage and salt water layer 20, and air and the U-shaped working well 23 are allowed to enter and exit the reservoir during the energy storage and release process; the drilling depth of the U-shaped working well 23 is optimized according to various schemes of actual stratum drilling completion cost and recovery efficiency, but the temperature of the bottom of the U-shaped working well 23 is at least more than 80 ℃.
In the step S2, the pressure fluctuation of the injected and extracted air is ensured to be the same as that of the traditional working well 17, so that the overall efficiency is prevented from being reduced due to overhigh pressure; the temperature of the air at the extraction end is improved by enhancing the underground heat supply, so that the underground energy recovery efficiency is improved.
During the drilling process, a certain range of holes need to be opened on the U-shaped well 24 by means of perforation technology, so that the fluid in the U-shaped well 24 can be communicated with the target gas storage and salt-water layer 20. The complete jetting means that the U-shaped well 24 at the section of the target gas storage and salt water layer 20 is opened within the depth range of the target gas storage and salt water layer 20 through a perforation technology, so that compressed air can be communicated with the reservoir at the section and freely enter and exit. The un-jetted U-shaped well 24 can not exchange the air with the target gas storage and salt-water layer 20, but can exchange heat.
In step S2, the U-shaped well 25 is arranged in the underburden 21 below the depth of the target gas/saline water layer 20 to be a straight well or a spiral for heat exchange, as shown in fig. 4, which is a schematic fluid movement diagram in the U-shaped well after the improvement of the present invention, the U-shaped well 25 is arranged in the underburden 21 below the depth of the target gas/saline water layer 20 to be a straight well for heat exchange, as shown in fig. 5, which is a schematic fluid movement diagram in the U-shaped well after the improvement of the present invention, the U-shaped well 25 is arranged in the underburden 21 below the depth of the target gas/saline water layer 20 to be a spiral for heat exchange, specifically, the U-shaped well 25 is arranged in the overburden 18 and the target gas/saline water layer 20 to be a straight well, the U-shaped well 25 is arranged in the underburden 21 to be a spiral shape, which can increase the heat exchange area and the fluid flow time, which is beneficial for air heat supplement, and the U-shaped well 25 is arranged in the overburden 18 and the target gas/saline water layer 20 to be a straight well with small construction difficulty and short fluid flow time compared to be a short spiral.
In step S2, the numerical simulation process is: the pressure and temperature simulation of gas produced at the wellhead in the actual field geological modeling and the operation process needs to be carried out, the two-dimensional radial model or three-dimensional modeling is selected according to the actual field geological modeling, the pressure and temperature of the outlet of the air after the circulation of the whole underground process are simulated, and a numerical simulation program T2WELL/EOS3 suitable for coupling of a gas-water-heat WELL barrel and a reservoir is adopted.
Specifically, a modeling tool of a two-dimensional radial model or three-dimensional modeling adopts GOCAD or MVIEW.
In the invention, in the step S2, when calculating the underground energy recovery efficiency of each cycle process, the earth surface process is ignored, only the total energy ratio of air in the extraction WELL mouth and air in the WELL mouth is considered, the specific enthalpy values at different times can be calculated by T2WELL/EOS3, and the single-cycle underground energy recovery efficiency is calculated by adopting the following formula;
E efficiency ＝E pro /E inj (2)
wherein E is inj/pro For calculating the total energy, Q, of air injected or extracted in a single cycle air Is the current injection or production flow, h (t) is the specific enthalpy for the corresponding time; e efficiency For single cycle underground energy recovery efficiency.
In the invention, in step S2, in the design process of the U-shaped working well 23, the diameter and the extension depth of the U-shaped outer well 24 and the diameter and the extension depth of the U-shaped inner well 25 need to be considered, the efficiency is calculated according to the underground recovery energy formula, the design scheme of the U-shaped working well 23 with high recovery efficiency is selected, and further the diameter and the extension depth of the U-shaped outer well 24 and the diameter and the extension depth of the U-shaped inner well 25 are selected appropriately.
In the present invention, in step S3, the drilling needs to consider: the air tightness is ensured to be good under the high-temperature and high-pressure state; when cementing, the damage to the surrounding stratum is reduced; the sand control between the target gas storage and salt water layer 20 and the U-shaped well 24 is considered, and the influence of the gas-water mixture in the aquifer on the corrosion of the U-shaped well 24 is noticed.
In the invention, in the step S3, a section of space needs to be reserved at the bottom of the U-shaped well outer well 24 and the U-shaped well inner well 25 to ensure that the friction is reduced when the flow rate of the inner U-shaped well outer well 24 and the flow rate of the U-shaped well inner well 25 are exchanged; an insulating layer is arranged in the depth range with lower background temperature at the periphery of the U-shaped outer well 24, so that heat dissipation of high-temperature air in the upward flowing process is reduced.
In the present invention, as shown in fig. 2, in step S4, the compressor system includes a multistage compressor, a heat exchanger is disposed behind each stage of compressor, air behind each stage of compressor is cooled, and compressed heat is stored by the heat storage device, and the expander system includes a multistage expander, and compressed heat stored in the heat storage device is extracted by the heat exchanger in front of each stage of expander, so as to heat the air.
The multistage compressor of the present invention is a low-pressure compressor 4 and a high-pressure compressor 5, respectively, and the multistage expander is a high-pressure turbine 11 and a low-pressure turbine 12, respectively.
In the present invention, in step S4, before the multi-stage expander system entering the ground surface regenerates power, it is necessary to heat air by using heat of compression and store cold energy in the heat storage device.
In the invention, in step S4, the compressor system comprises a motor 3, a power generation system, a low-pressure compressor 4, a high-pressure compressor 5, a first heat exchanger 6 and a second heat exchanger 7, wherein filtered clean air at normal temperature and normal pressure enters the inlet part of the low-pressure compressor 4, the air is cooled by the first heat exchanger 6 after being compressed by the low-pressure compressor 4, and then enters the high-pressure compressor 5, the air is cooled by the second heat exchanger 7 after being compressed by the high-pressure compressor 5, and the cooled high-pressure air is controlled to be injected into the working well 17 through a pipeline and a first throttle valve 15.
The power generation system comprises a wind power generation device 2 and a photovoltaic power generation device 1, and electric energy generated by the wind power generation device 2 and the photovoltaic power generation device 1 drives a motor 3 to operate for supplying power.
In the present invention, in step S4, the expander system includes a multi-stage expander, the expander system includes a third heat exchanger 10, a fourth heat exchanger 14, a high-pressure turbine 11, a low-pressure turbine 12 and a coaxial generator 13, after the flow rate and pressure of the air after mining are controlled by a second throttle 16, the air firstly enters the third heat exchanger 10 to further heat the high-pressure air to form high-temperature high-pressure air, the high-temperature high-pressure air enters the high-pressure turbine 11 to generate electricity by the coaxial generator 13, the low-pressure air is formed and then is heated by the fourth heat exchanger 14, the low-pressure air enters the low-pressure turbine 12 to generate electricity by the coaxial generator 13 again, and then the air is discharged to the atmosphere.
In the invention, in step S4, the heat storage device includes a high-temperature hot tank 8 and a low-temperature cold tank 9, the high-temperature hot tank 8 is used for collecting the compression heat in the process of compressing the air by the low-pressure compressor 4 and the high-pressure compressor 5 in the compressor system, and the low-temperature cold tank 9 is used for collecting the cold energy after heat exchange before the exploited air enters the high-pressure turbine 11 and is respectively connected with the heat exchanger.
In an embodiment of the present invention, as shown in fig. 2, which is a general schematic diagram of a compressed air energy storage system of a target air storage saline water layer 20 in the present invention, valley electricity in a photovoltaic power generation apparatus 1 and a wind power generation apparatus 2 drives a motor 3 to drive a low-pressure compressor 4 and a high-pressure compressor 5 to work, pure air (20-25 ℃ and 0.1 Mpa) at normal temperature and normal pressure first passes through the low-pressure compressor 4 and is compressed to 0.1-4.0Mpa, the compressed air enters a first heat exchanger 6, is cooled by using cold energy provided by a low-temperature cold tank 9, and stores the compressed heat in a high-temperature hot tank 8, the cooled compressed air enters the high-pressure compressor 5 and is compressed to 8-15Mpa, the compressed high-temperature high-pressure air enters a second heat exchanger 7 for heat exchange, the low-temperature cold tank 9 provides cold energy, the compressed heat is stored in the high-temperature hot tank 8, the high-pressure air (25-40 ℃) coming from the second heat exchanger 7 is injected into the target saline water layer 20 through a working well 17, and the injection flow rate of the first throttle valve 15 is controlled; during gas production and power generation, the flow and pressure of gas production are controlled through the second throttle valve 16, produced high-pressure air enters the third heat exchanger 10 to be heated, heat energy is provided by the high-temperature hot tank 8, cold energy after heat exchange is stored in the low-temperature cold tank 9, high-temperature high-pressure air at the outlet of the third heat exchanger 10 enters the high-pressure turbine 11 to generate power through the coaxial power generator 13, low-pressure air (0.1-4 Mpa) at the outlet of the high-pressure turbine 11 passes through the fourth heat exchanger 14, heat energy is provided by the high-temperature hot tank 8, cold energy is recovered by the low-temperature cold tank 9, the high-temperature high-pressure air enters the low-pressure turbine 12 to generate power for the second time through the power generator 13, and waste gas discharged by the low-pressure turbine 12 can be directly discharged into the environment or subjected to waste heat recovery.
To better illustrate the present invention, and to take advantage of its potential efficiency, the embodiment of the present invention selects the existing conventional work well system as shown in FIG. 3 and the U-shaped work well 23 of the present invention to illustrate the comparison of wellhead pressure, temperature and subsurface recovery energy efficiency.
Through geological survey, the geological conditions in this embodiment are: the cover layer 19 on the target gas storage and saline water layer 20 has very low permeability of 5.0 × 10 -19 m 2 (ii) a The structure of the target gas and salt water layer 20 is a straight aquifer, and the closed structure is a very low permeability boundary which is 40m away from the working well 17; the depth range of the reservoir is 650m to 800m, and the permeability in the gas storage space of the saline water layer is 5.0 multiplied by 10 -13 m 2 (500 md), porosity of 0.2, formation thermal conductivity of 2.51W/(m.K); the geothermal gradient of the ground background is 31.25 ℃/km, and the initial surface temperature is 15 ℃.
The design parameters of the U-shaped working well 23 are as follows: the bottom hole depth is 3000m, according to the geothermal gradient, the background formation temperature of the bottom hole is 108.75 ℃, the perforation range of the U-shaped well outside well 24 is 650-800m of a target reservoir range, the diameter of the U-shaped well inside well 25 is 0.5m, the diameter of the U-shaped well outside well 24 is 1.5m, and the roughness coefficient in the well is 45 multiplied by 10-6m; compared with the conventional working well 17, the bottom depth is 800m, and the hole diameter is 0.5m.
The underground injection-production circulating working system comprises: daily circulation, injecting at the initial 12 hours each day at the speed of 54kg/s, stopping injection at 4.5 hours, extracting at the speed of 216kg/s for 3 hours, and stopping injection at the last 4.5 hours. The injected air temperature was 40 ℃.
The modeling software adopts MVIEW to establish a two-dimensional radial symmetric model, the calculation simulation program adopts T2WELL/EOS3, and the total simulation time is 200 cycles, namely 200 days.
FIG. 6 is a comparison graph of wellhead pressures of a traditional working well 17 and a U-shaped working well 23, and the result shows that the pressure changes of the wellheads in the circulation process are basically consistent, the pressure of the traditional well in the injection and extraction stages is slightly larger than that of the U-shaped working well 23, but the maximum difference is not more than 0.25MPa; fig. 7 is a comparison diagram of wellhead temperatures of a conventional working well 17 and a U-shaped working well 23 in the invention, and it can be obviously found that the air pressure in the extraction stage of the U-shaped working well 23 is obviously improved compared with that of an original system, and the outlet pressure in the U-shaped extraction stage can reach 46 ℃ and even exceed 40 ℃ of injected air, which indicates that the U-shaped working well 23 provided by the invention can improve the outlet temperature to a greater extent through the heat exchange between the underlying stratum 21 and the U-shaped working well 23; fig. 8 is a comparison graph of the underground energy recovery efficiency of the conventional working well 17 and the U-shaped working well 23, and the U-shaped working well 23 provided by the present invention can enhance the efficiency to a greater extent, and can improve the efficiency by up to 6% compared with the conventional method under the conditions of the present embodiment, and can well utilize a part of the formation heat in the energy storage process.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (10)
1. A method for improving the underground energy recovery efficiency of salt water layer compressed air energy storage is characterized by comprising the following steps:
s1, finding out deep geological conditions and properties of a target site, and determining the positions, structures and properties of a target gas storage, salt water layer, cover layer and underburden;
s2, determining the design of the U-shaped working well by utilizing numerical simulation calculation, wherein the design comprises the steps of providing a plurality of U-shaped working well design schemes after the deep stratum condition is detected, carrying out site geological modeling by utilizing geological modeling software, carrying out numerical simulation on the plurality of U-shaped working well design schemes by utilizing a gas-water-heat well reservoir coupling simulator, analyzing pressure-temperature change in the cyclic process, calculating efficiency by utilizing an underground recovery energy formula, and selecting the U-shaped working well design scheme with high recovery efficiency, wherein the U-shaped working well comprises a U-shaped outer well and a U-shaped inner well, the U-shaped outer well is provided with a perforation, the U-shaped inner well is arranged in the U-shaped outer well and is spaced from the U-shaped outer well by a certain distance, and both the U-shaped inner well and the U-shaped outer well extend to the underlying stratum;
s3, according to the selected design scheme of the U-shaped working well, performing site drilling and well completion construction;
s4, arranging devices of the ground surface energy storage system to form a whole set of energy storage system, wherein the whole set of energy storage system comprises a heat storage device, a compressor system and an expander system;
s5, in the process of injecting air, air enters through the U-shaped well inner well, flows to the bottom of the U-shaped well inner well, enters between the U-shaped well outer well and the U-shaped well inner well, moves upwards, and finally enters into a target gas storage and salt water layer through a perforation on the U-shaped well outer well; in the process of air extraction, air enters between the U-shaped well outer well and the U-shaped well inner well from the target air storage saline water layer, moves downwards to the bottom of the well, then enters the U-shaped well inner well, and finally enters the well head upwards along the U-shaped well inner well, and the air is extracted.
2. The method for improving the underground energy recovery efficiency of the salt water layer compressed air energy storage according to claim 1, wherein the method comprises the following steps:
in the step S1, the deep geological condition detection range is 0-3000 m, and the deep geological condition and the properties of the target field are found out through well logging, vertical seismic profile testing, two-dimensional or three-dimensional seismic exploration, well drilling and pre-exploration, coring, interference test, formation water chemical analysis and core displacement experiment.
3. The method for improving the underground energy recovery efficiency of the salt water layer compressed air energy storage according to claim 1, wherein the method comprises the following steps:
in the step S1, the principle of selecting a target gas storage saline water layer includes: the energy storage scale is reasonably matched with the reservoir closed structure, and the structure is a anticline or fault closed structure; the reservoir permeability needs to be more than 100md, the reservoir thickness needs to be more than 10m, and the porosity needs to be more than 0.1; the cover layer has good closure and integrity within a certain range, and the stability of the regional geological condition is good; the underburden has a greater temperature.
4. The method for improving the underground energy recovery efficiency of the salt water layer compressed air energy storage according to claim 1, wherein the method comprises the following steps:
in step S2, the design principle of the U-shaped working well is: the U-shaped well is only completely penetrated within the depth range of a target gas storage saline water layer, and air and the U-shaped working well are allowed to enter and exit the reservoir layer in the process of energy storage and energy release; the drilling depth of the U-shaped working well is optimized according to the actual drilling completion cost and recovery efficiency of the stratum, but the temperature of the bottom of the U-shaped working well at the depth is at least more than 80 ℃.
5. The method for improving the underground energy recovery efficiency of the salt water layer compressed air energy storage according to claim 1, wherein the method comprises the following steps:
in step S2, the numerical simulation process is: the pressure and temperature simulation of gas produced at the wellhead in the actual field geological modeling and the operation process needs to be carried out, the two-dimensional radial model or three-dimensional modeling is selected according to the actual field geological modeling, the pressure and temperature of the outlet of the air after the circulation of the whole underground process are simulated, and a numerical simulation program T2WELL/EOS3 suitable for coupling of a gas-water-heat WELL barrel and a reservoir is adopted.
6. The method for improving the underground energy recovery efficiency of the salt water layer compressed air energy storage according to claim 5, wherein the method comprises the following steps:
in the step S2, when calculating the underground energy recovery efficiency of each cycle process, neglecting the earth surface process, only considering the total energy ratio of air when the WELL mouth is extracted and air enters the WELL mouth, the specific enthalpy values at different times can be calculated by T2WELL/EOS3, and the underground energy recovery efficiency of a single cycle is calculated by adopting the following formula;
E efficiency ＝E pro /E inj (2)
wherein E is inj/pro For calculating the total energy, Q, of air injected or extracted in a single cycle air Is the current injection or production flow, h (t) is the specific enthalpy for the corresponding time; e efficiency For single cycle underground energy recovery efficiency.
7. The method for improving the underground energy recovery efficiency of the salt water layer compressed air energy storage according to claim 1, wherein the method comprises the following steps:
in step S2, in the design process of the U-shaped working well, the diameter and the extension depth of the U-shaped outer well and the diameter and the extension depth of the U-shaped inner well need to be considered.
8. The method for improving the underground energy recovery efficiency of the salt water layer compressed air energy storage according to claim 1, wherein the method comprises the following steps:
in step S3, drilling needs to consider: the air tightness is ensured to be good under the high-temperature and high-pressure state; when cementing, the damage to the surrounding stratum is reduced; the sand control between the target gas storage layer and the outer layer of the well bore is considered, and the influence of the gas-water mixture in the aquifer on the corrosion of the well pipe is noticed.
9. The method for improving the underground energy recovery efficiency of the salt water layer compressed air energy storage according to claim 1, wherein the method comprises the following steps:
in the step S3, a section of space needs to be reserved at the bottom of the U-shaped well outer well and the U-shaped well inner well, so that friction is reduced when the flow rate of the inner U-shaped well outer well and the U-shaped well inner well is exchanged; and an insulating layer is arranged at the periphery of the U-shaped well outside the well in a depth range with lower background temperature.
10. The method for improving the underground energy recovery efficiency of the salt water layer compressed air energy storage according to claim 1, wherein the method comprises the following steps:
in step S4, the compressor system includes a multistage compressor, a heat exchanger is disposed behind each stage of compressor, air behind each stage of compressor is cooled, and the heat of compression is stored by the heat storage device, and the expander system includes a multistage expander, and the heat of compression stored in the heat storage device is extracted by the heat exchanger in front of each stage of expander, so as to heat the air.
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| CN117722262A (en) * | 2024-02-18 | 2024-03-19 | 成都英沃信科技有限公司 | Method for using natural gas abandoned reservoir as gas circulation energy storage warehouse |
| CN117722262B (en) * | 2024-02-18 | 2024-04-30 | 成都英沃信科技有限公司 | Method for using natural gas abandoned reservoir as gas circulation energy storage warehouse |
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| CN117722262A (en) * | 2024-02-18 | 2024-03-19 | 成都英沃信科技有限公司 | Method for using natural gas abandoned reservoir as gas circulation energy storage warehouse |
| CN117722262B (en) * | 2024-02-18 | 2024-04-30 | 成都英沃信科技有限公司 | Method for using natural gas abandoned reservoir as gas circulation energy storage warehouse |
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