CN108775275B - Single-well closed circulation underground thermoelectric power generation system and method - Google Patents
Single-well closed circulation underground thermoelectric power generation system and method Download PDFInfo
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- CN108775275B CN108775275B CN201810525808.XA CN201810525808A CN108775275B CN 108775275 B CN108775275 B CN 108775275B CN 201810525808 A CN201810525808 A CN 201810525808A CN 108775275 B CN108775275 B CN 108775275B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
- F03G—SPRING, WEIGHT, INERTIA OR LIKE MOTORS; MECHANICAL-POWER PRODUCING DEVICES OR MECHANISMS, NOT OTHERWISE PROVIDED FOR OR USING ENERGY SOURCES NOT OTHERWISE PROVIDED FOR
- F03G7/00—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for
- F03G7/04—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using pressure differences or thermal differences occurring in nature
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/10—Geothermal energy
Abstract
The invention relates to a single-well closed circulation underground thermoelectric power generation system and a method. The system comprises: the system comprises a well bore, a fluid circulation module and an electric energy output module. The wellbore includes a casing, tubing, and a thermoelectric generation module. The top of the oil pipe is flush with the top of the casing pipe, and the bottom of the oil pipe is positioned above the bottom of the shaft and has a gap with the bottom of the shaft. The thermoelectric power generation module is connected with the electric energy output module through a connecting cable. And an oil sleeve annular flow channel is formed in a space between the inner wall of the sleeve and the outer wall of the thermoelectric power generation module. The interior space of the oil pipe forms an oil pipe flow passage. The fluid circulation module comprises a cold fluid injection pipeline, a cold fluid injection pump, a cold fluid outflow pipeline, a cold fluid storage container, a cold fluid inflow pipeline, a closed circulation outflow hot fluid utilization module and a closed circulation outflow fluid flow pipeline. The invention can realize the heat extraction power generation without extracting water, provides stable electric energy supply and does not influence the subsequent utilization of the heat exchange fluid.
Description
Technical Field
The invention belongs to the technical field of geothermal power generation, and particularly relates to a single-well closed-cycle underground thermoelectric power generation system and method.
Background
Geothermal energy is a clean green energy source, and has the advantages of large resource quantity, no influence of climate conditions on production, small pollution, sustainability and the like.
The geothermal power generation technology mainly comprises a dry steam power generation technology, an underground hot water power generation technology, a combined cycle power generation technology, a dry hot rock geothermal power generation technology and the like. In the current geothermal power generation technology, 27% adopts dry steam geothermal power generation, 41% adopts a single-working-medium flash evaporation mode, 20% adopts a double-working-medium flash evaporation mode, 1% adopts a back pressure steam turbine, and 11% adopts an ORC/combined cycle/mixing mode.
With the progress of semiconductor material manufacturing techniques and processes in recent years, thermoelectric power generation techniques have been gradually developed. When different temperatures are applied to both sides of the semiconductor, respectively, an electromotive force is generated between the high temperature side and the low temperature side due to the seebeck effect. By utilizing this phenomenon, thermal energy can be directly converted into electric energy using the thermoelectric power generation element. Some studies have shown that sufficient electrical energy can be generated even with a temperature difference of only 10 degrees celsius between the high temperature side and the low temperature side.
Disclosure of Invention
Aiming at the production characteristics of medium and low temperature heat storage, the invention provides a single-well closed cycle underground thermoelectric power generation system and method by combining a thermoelectric power generation technology.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention relates to a single-well closed circulation underground thermoelectric power generation system, which comprises: the system comprises a shaft drilled through the formation of the geothermal well, a fluid circulation module and an electric energy output module.
Specifically, the shaft comprises a casing, an oil pipe embedded in the casing and a thermoelectric power generation module arranged on the outer wall of the oil pipe; the top of the oil pipe is flush with the top of the casing pipe, the bottom of the oil pipe is positioned above the bottom of the shaft, and a gap is reserved between the bottom of the oil pipe and the bottom of the shaft; the thermoelectric power generation module is connected with the electric energy output module through a connecting cable; an oil sleeve annulus flow channel is formed in a space between the inner wall of the sleeve and the outer wall of the thermoelectric power generation module; the inner space of the oil pipe forms an oil pipe flow passage.
The fluid circulation module comprises a cold fluid injection pipeline, a cold fluid injection pump, a cold fluid outflow pipeline, a cold fluid storage container, a cold fluid inflow pipeline, a closed type circulation outflow hot fluid utilization module and a closed type circulation outflow fluid flow pipeline; the outlet of the cold fluid injection pump is connected with the oil sleeve annular flow channel or the oil pipe flow channel through a cold fluid injection pipeline; the inlet of the cold fluid injection pump is connected with the outlet of the cold fluid storage container through a cold fluid outflow pipeline; an inlet of the cold fluid storage container is connected with an outlet of the closed type circulating outflow hot fluid utilization module through a cold fluid inflow pipeline; when the outlet of the cold fluid injection pump is connected with the oil sleeve annular flow channel through a cold fluid injection pipeline, the inlet of the closed circulating hot fluid outflow utilization module is connected with the oil pipe flow channel through a closed circulating outflow fluid flow pipeline; when the outlet of the cold fluid injection pump is connected with the oil pipe flow channel through the cold fluid injection pipeline, the inlet of the closed circulation outflow heat fluid utilization module is connected with the oil sleeve annulus flow channel through the closed circulation outflow fluid flow pipeline.
Furthermore, the shaft is of a hole structure drilled through the formation of the geothermal well and is realized by adopting a mode of casing pipe descending to shaft bottom cement injection and well cementation; the casing is tightly cemented with the geothermal well stratum; and the well bottom is sealed by cement.
Further, the thermoelectric power generation module comprises a plurality of groups of thermoelectric power generators which are connected in series; the thermoelectric generator comprises a plurality of groups of thermoelectric generating units; the thermoelectric power generation units comprise an N-type semiconductor and a P-type semiconductor, and the N-type semiconductor and the P-type semiconductor are alternately arranged between the adjacent thermoelectric power generation units.
Furthermore, the cross sections of the sleeve and the oil pipe are both circular; the sleeve and the oil pipe are coaxially arranged; the cross section of the thermoelectric power generation module is circular.
Further, the cold fluid injection pump and the cold fluid storage vessel are located on the ground.
The invention also relates to a thermoelectric power generation method adopting the single-well closed circulation underground thermoelectric power generation system, which comprises the following steps:
s1, when the outlet of the cold fluid injection pump is connected with the oil casing annular flow channel through the cold fluid injection pipeline, the method comprises the following steps:
and S11, allowing the cold fluid stored in the cold fluid storage container to enter a cold fluid injection pump through a cold fluid outflow pipeline, pressurizing the cold fluid, and allowing the cold fluid to enter an oil sleeve annulus flow channel through a cold fluid injection pipeline.
S12, in the process that the cold fluid flows downwards along the oil sleeve annulus flow channel, heat is continuously absorbed from the surrounding stratum, the temperature is gradually increased, and the temperature reaches the highest at the bottom of the well and becomes high-temperature fluid.
And S13, because the bottom of the well is sealed by cement, high-temperature fluid enters the oil pipe flow channel from a gap between the bottom of the well and the bottom of the oil pipe, flows upwards to the ground along the oil pipe flow channel, enters a closed circulation flow fluid flow pipeline, then enters a closed circulation flow hot fluid utilization module, and returns to the cold fluid storage container through the cold fluid flow pipeline after heat exchange and utilization.
And S14, generating electric energy by the thermoelectric power generation module under the action of the temperature difference between the high-temperature fluid in the oil pipe flow channel and the low-temperature fluid in the oil sleeve annulus flow channel, and inputting the electric energy into the electric energy output module through the connecting cable.
S2, when the outlet of the cold fluid injection pump is connected with the oil casing annular flow channel through the cold fluid injection pipeline, the method comprises the following steps:
and S21, after entering a cold fluid injection pump for pressurization through a cold fluid outflow pipeline, the cold fluid stored in the cold fluid storage container enters an oil pipe flow channel through a cold fluid injection pipeline.
And S22, absorbing partial heat from the hot fluid in the oil sleeve annulus flow channel in the process that the cold fluid flows downwards along the oil pipe flow channel, and keeping the temperature at a low level.
And S23, after the fluid reaches the well bottom, because the well bottom is sealed by cement, the fluid flowing out of the oil pipe flow channel enters the oil sleeve annulus flow channel from a gap between the well bottom and the bottom of the oil pipe, flows upwards to the ground along the oil sleeve annulus flow channel, enters a closed circulation outflow fluid flow pipeline, then enters a closed circulation outflow hot fluid utilization module, and returns to the cold fluid storage container through the cold fluid inflow pipeline after heat exchange and utilization.
S24, continuously performing heat exchange with surrounding strata in the upward flowing process of the oil sleeve annulus flow channel, enabling the temperature of the fluid in the oil sleeve annulus flow channel to be higher than that of the fluid in the oil pipe flow channel at the same depth, enabling the thermoelectric power generation module to generate electric energy under the action of the temperature difference between the high-temperature fluid in the oil sleeve annulus flow channel and the low-temperature fluid in the oil pipe flow channel, and inputting the electric energy into the electric energy output module through the connecting cable.
Further, the cold fluid is any one of water, liquid carbon dioxide and liquid nitrogen.
Compared with the prior art, the invention has the beneficial effects that:
(1) the invention adopts a fluid closed circulation mode to realize that water is not required for underground heat extraction and power generation, and avoids the potential problems of stratum sedimentation, shaft scaling and the like in the traditional geothermal production process.
(2) The invention realizes underground power generation by utilizing the thermoelectric module arranged underground.
(3) In the invention, the fluid circulated after underground power generation can be used for ground heating, cultivation, bathing and the like after ground heat exchange.
In conclusion, the invention can not only realize the heat extraction and power generation without extracting water and provide stable electric energy supply, but also can not influence the subsequent utilization of the heat exchange fluid.
Drawings
FIG. 1 is a schematic structural diagram of a single well closed cycle downhole thermoelectric power generation system according to an embodiment;
FIG. 2 is a schematic view of the cross-sectional structure I-I' of FIG. 1;
fig. 3 is a schematic structural diagram of a single-well closed-cycle downhole hot spot power generation system in the second embodiment.
Wherein:
101. the system comprises a geothermal well formation, 102, a casing, 103, a thermoelectric power generation module, 104, an oil pipe, 105, a well bottom, 106, a well bore, 200, a fluid circulation module, 201, a cold fluid injection pipeline, 202, a cold fluid injection pump, 203, a cold fluid outflow pipeline, 204, a cold fluid storage container, 205, a cold fluid inflow pipeline, 206, a closed circulation outflow hot fluid utilization module, 207, a closed circulation outflow fluid flow pipeline, 301, a connecting cable, 302, an electric energy output module, 401, an oil casing annulus flow channel, 402 and an oil pipe flow channel.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
example one
A single well closed cycle downhole thermoelectric power generation system as shown in fig. 1, comprising: a wellbore 106 drilled through the formation of a geothermal well, a fluid circulation module 200, and an electrical energy export module 302.
Specifically, the geothermal well formation 101 extends several kilometers deep, and the formation temperature gradually decreases from bottom to top. The wellbore 106 is a borehole drilled through the geothermal well formation 101 and is cemented to the bottom of the well 105 by casing 102. The casing 102 is cemented in close proximity to the geothermal well formation 101 and isolated from formation fluids. The bottom hole 105 is sealed with cement to prevent formation fluids from entering the wellbore 106. Tubing 104 is run directly above the bottom of the well 105 and the outer wall of tubing 104 and the portion of casing 102 form an oil-casing annulus flow passage 401. The interior space of the tubing 104 forms a tubing flow passage 402. The thermoelectric generation module 103 is tightly fixed on the outer wall of the oil pipe 104 and is lowered into the casing 102 along with the oil pipe 104.
Further, the fluid circulation module 200 includes a cold fluid injection line 201, a cold fluid injection pump 202, a cold fluid outflow line 203, a cold fluid storage container 204, a cold fluid inflow line 205, a closed circulation outflow hot fluid utilization module 206, and a closed circulation outflow fluid flow line 207. The cold fluid injection pump 202 and cold fluid storage vessel 204 are located at the surface. The inlet of the cold fluid injection pump 202 is connected to the outlet of the cold fluid storage vessel 204 via a cold fluid outflow line 203. The outlet of the cold fluid injection pump 202 is connected to the oil jacket annulus flow passage 401 by cold fluid injection line 201. The inlet of the cold fluid storage container is connected with the outlet of the closed-type circulating outflow hot fluid utilization module through a cold fluid inflow pipeline. The inlet of the closed-cycle effluent hot fluid utilization module 206 is connected to the tubing flow path 402 by a closed-cycle effluent fluid flow line 207.
Further, the thermoelectric power generation module 103 is connected to the electric energy output module 302 through a docking cable 301, and provides electric energy to the user through the electric energy output module 302.
Further, as shown in FIG. 2, the cross-section of the tubing 104 and casing 102 are circular. The casing 102 and tubing 104 are coaxially disposed. The thermoelectric power generation module 103 has a circular cross section.
Further, the thermoelectric power generation module 103 is formed by connecting a plurality of groups of thermoelectric power generators in series; the plurality of groups of thermoelectric generators can be 1 group, 10 groups and 100 groups, and can also be any plurality of groups; the thermoelectric generator is formed by assembling a plurality of N-type semiconductors and a plurality of P-type semiconductors in an alternating and paired arrangement mode; an N-type semiconductor and a P-type semiconductor form a thermoelectric power generation unit; the number of the N-type semiconductors and the number of the P-type semiconductors can be 1, 10, 100 or any number; the number of the N-type semiconductors is equal to that of the P-type semiconductors.
Further, the cold fluid is water, liquid carbon dioxide and liquid nitrogen.
The working principle of the system is as follows:
the cold fluid injection pump 202 pressurizes cold fluid from the cold fluid storage vessel 204 and injects the pressurized cold fluid through the cold fluid injection line 201 into the oil jacket annular flow passage 401. The pressurized cooling fluid flows down the annular flow passage 401 to the bottom of the well 105. As the cold fluid flows down the oil jacket annulus flow passage 401, it continuously absorbs heat from the surrounding formation and the cold fluid gradually increases in temperature to become a hot fluid, i.e., a hot fluid. Since the bottom hole 105 is cemented, the hot fluid that has absorbed heat from the surrounding formation can only enter the tubing flow path 402 from the space between the bottom of the tubing 104 and the bottom hole 105 and then flow up the tubing flow path 402 out of the wellbore. Since the fluid flowing upward in the tubing flow channel 402 is heated by absorbing heat from the surrounding formation, and the fluid flowing downward in the oil jacket annulus flow channel 401 is heated by continuously absorbing heat from the surrounding formation during the flowing process, the temperature of the fluid in the tubing flow channel 402 is higher than that of the fluid in the oil jacket annulus flow channel 401 at the same depth. The fluid in the oil pipe flow channel 402 provides a heat source for the thermoelectric generation module 103 and becomes the high-temperature hot end of the thermoelectric generation module 103; the fluid in the oil jacket annulus flow channel 401 provides a cold source for the thermoelectric generation module 103 and becomes the low temperature cold end of the thermoelectric generation module 103. The thermoelectric generation modules 103 generate electrical energy as a function of the temperature difference between the fluid temperature in the oil jacket annulus flow passage 401 and the fluid temperature in the oil pipe flow passage 402. The hot fluid flowing out of the oil pipe flow passage 402 enters the closed-cycle outflow hot fluid utilization module 206 through the closed-cycle outflow fluid flow line 207, and after being sufficiently heat-exchanged and utilized in the closed-cycle outflow hot fluid utilization module 206 to become a cold fluid, the cold fluid flows into the cold fluid storage container 204 through the cold fluid inflow line 205. The cold fluid storage container 204, the cold fluid outflow pipeline 203, the cold fluid injection pump 202, the cold fluid injection pipeline 201, the oil jacket annular flow channel 401, the oil pipe flow channel 402, the closed circulation outflow fluid flow pipeline 207, the closed circulation outflow hot fluid utilization module 206 and the cold fluid inflow pipeline 205 form a closed fluid circulation system, so that continuous cold energy and heat energy are provided for the thermoelectric power generation module 9, and downhole power generation is realized.
The implementation method of the single-well closed-cycle underground thermoelectric power generation system in the embodiment comprises the following steps:
(1) selecting a high-temperature geothermal well or a discarded oil well due to high water content, and plugging the bottom of the well by using cement; the oil pipe 104, to the outer wall of which the thermoelectric generation module 103 is bonded, is lowered above the well bottom 105 according to the depth of the well bottom 105.
(2) The cold fluid storage container 204, the cold fluid outflow pipeline 203, the cold fluid injection pump 202 and the cold fluid injection pipeline 201 are sequentially connected, and the cold fluid injection pipeline 201 is connected with the oil sleeve annulus flow channel 401; connecting the tubing flow path 402 to the closed-cycle effluent hot fluid utilization module 206 via the closed-cycle effluent fluid flow line 207; the closed-cycle outflow hot fluid utilization module 206 is connected to the cold fluid storage container 204 through the cold fluid inflow line 205, thereby forming a closed fluid circulation system.
(3) The thermoelectric power generation module 103 is connected to the electric power output module 302 via a patch cable 301 to form a circuit system.
(4) The cold fluid stored in the cold fluid storage vessel 204 enters the cold fluid injection pump 202 through the cold fluid outflow line 203, is pressurized, and then enters the oil jacket annulus flow passage 401 through the cold fluid injection line 201.
(5) As the cold fluid flows down the oil jacket annulus flow passage 401, it continuously absorbs heat from the surrounding formation, increasing in temperature, reaching a maximum temperature at the bottom of the well 105, becoming a hot fluid.
(6) As the bottom hole 105 is cemented, the high temperature fluid enters the tubing flow channel 402 from the space between the bottom hole 105 and the bottom of the tubing 104 and flows up the tubing flow channel 402 to the surface, enters the closed-cycle effluent fluid flow line 207, then enters the closed-cycle effluent hot fluid utilization module 206, exchanges heat and is utilized and then returns to the cold fluid storage vessel 204 through the cold fluid inflow line 205.
(7) The thermoelectric generation module 103 generates electric power by a temperature difference between the high temperature fluid in the oil pipe flow passage 402 and the low temperature fluid in the oil jacket annulus flow passage 401, and inputs the electric power to the electric power output module 302 through the patch cable 301.
Example two
As shown in fig. 3, in the single-well closed-cycle downhole thermoelectric power generation system in this embodiment, an outlet of the cold fluid injection pump is connected to the oil pipe flow channel through a cold fluid injection line, and an inlet of the closed-cycle hot fluid outflow module is connected to the oil jacket annulus flow channel through a closed-cycle hot fluid outflow line.
The implementation method of the single-well closed-cycle underground thermoelectric power generation system in the embodiment comprises the following steps:
(1) selecting a high-temperature geothermal well or a discarded oil well due to high water content, and plugging the bottom of the well by using cement; the oil pipe 104, to the outer wall of which the thermoelectric generation module 103 is bonded, is lowered above the well bottom 105 according to the depth of the well bottom 105.
(2) The cold fluid storage container 204, the cold fluid outflow line 203, the cold fluid injection pump 202 and the cold fluid injection line 201 are connected in sequence, and the cold fluid injection line 201 is connected with the oil pipe flow channel 402; connecting the oil jacket annulus flow channel 401 with a closed cycle effluent hot fluid utilization module 206 via a closed cycle effluent fluid flow line 207; the closed-cycle outflow hot fluid utilization module 206 is connected to the cold fluid storage container 204 via the cold fluid inflow line 205, thereby forming a closed fluid circulation system.
(3) The thermoelectric power generation module 103 is connected to the electric power output module 302 via a patch cable 301 to form a circuit system.
(4) The cold fluid stored in the cold fluid storage container 204 enters the cold fluid injection pump 202 through the cold fluid outflow line 203, is pressurized, and then enters the tubing flow channel 402 through the cold fluid injection line 201.
(5) During the downward flow of the cold fluid along the tubing flow path 402, a portion of the heat is absorbed from the hot fluid in the oil jacket annulus flow path 401, and the temperature is maintained at a low level.
(6) After the fluid reaches the bottom hole 105, because the bottom hole 105 is sealed by cement, the fluid flowing out of the tubing flow channel 402 enters the oil casing annulus flow channel 401 from the space between the bottom hole 105 and the bottom of the tubing 104, flows upwards to the ground along the oil casing annulus flow channel 401, enters the closed circulation fluid flow line 207, then enters the closed circulation fluid utilization module 206, and returns to the cold fluid storage container 204 through the cold fluid flow line 205 after heat exchange and utilization.
(7) During the upward flow of the fluid in the oil sleeve annulus flow channel 401, the fluid continuously exchanges heat with the surrounding stratum, the temperature of the fluid in the oil sleeve annulus flow channel 401 is higher than that of the fluid in the oil pipe flow channel 402 at the same depth, the thermoelectric generation module 103 generates electric energy under the action of the temperature difference between the high-temperature fluid in the oil sleeve annulus flow channel 401 and the low-temperature fluid in the oil pipe flow channel 402, and the electric energy is input into the electric energy output module 302 through the connecting cable 301.
The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.
Claims (6)
1. The power generation method of the single-well closed-cycle underground thermoelectric power generation system is characterized in that the thermoelectric power generation system comprises the following steps: the system comprises a shaft drilled through the formation of the geothermal well, a fluid circulation module and an electric energy output module;
the shaft comprises a casing, an oil pipe embedded in the casing and a thermoelectric power generation module arranged on the outer wall of the oil pipe; the casing is tightly cemented with the geothermal well stratum; the top of the oil pipe is flush with the top of the casing pipe, the bottom of the oil pipe is positioned above the bottom of the shaft and a gap is reserved between the bottom of the shaft and the bottom of the shaft; the thermoelectric power generation module is connected with the electric energy output module through a connecting cable; an oil sleeve annulus flow channel is formed in a space between the inner wall of the sleeve and the outer wall of the thermoelectric power generation module; the inner space of the oil pipe forms an oil pipe flow channel;
the fluid circulation module comprises a cold fluid injection pipeline, a cold fluid injection pump, a cold fluid outflow pipeline, a cold fluid storage container, a cold fluid inflow pipeline, a closed type circulation outflow hot fluid utilization module and a closed type circulation outflow fluid flow pipeline; the outlet of the cold fluid injection pump is connected with the oil sleeve annular flow channel or the oil pipe flow channel through a cold fluid injection pipeline; the inlet of the cold fluid injection pump is connected with the outlet of the cold fluid storage container through a cold fluid outflow pipeline; an inlet of the cold fluid storage container is connected with an outlet of the closed type circulating outflow hot fluid utilization module through a cold fluid inflow pipeline; when the outlet of the cold fluid injection pump is connected with the oil sleeve annular flow channel through a cold fluid injection pipeline, the inlet of the closed circulating outflow hot fluid utilization module is connected with the oil pipe flow channel through a closed circulating outflow fluid flow pipeline; when the outlet of the cold fluid injection pump is connected with the oil pipe flow channel through a cold fluid injection pipeline, the inlet of the closed circulating hot fluid outflow utilization module is connected with the oil sleeve annulus flow channel through a closed circulating outflow fluid flow pipeline;
when the outlet of the cold fluid injection pump is connected with the oil sleeve annular flow channel through the cold fluid injection pipeline, the power generation method of the thermoelectric power generation system comprises the following steps:
s11, after entering a cold fluid injection pump through a cold fluid outflow pipeline and being pressurized, the cold fluid stored in the cold fluid storage container enters an oil sleeve annular flow channel through a cold fluid injection pipeline;
s12, continuously absorbing heat from the surrounding stratum in the process that cold fluid flows downwards along the oil sleeve annulus flow channel, gradually increasing the temperature, and changing the temperature to high-temperature fluid when the temperature reaches the highest at the bottom of the well;
s13, because the bottom of the well is sealed by cement, high-temperature fluid enters an oil pipe flow channel from a gap between the bottom of the well and the bottom of the oil pipe, flows upwards to the ground along the oil pipe flow channel, enters a closed circulation outflow fluid flow pipeline, then enters a closed circulation outflow hot fluid utilization module, and returns to a cold fluid storage container through a cold fluid inflow pipeline after heat exchange and utilization;
s14, the thermoelectric power generation module generates electric energy under the action of temperature difference between high-temperature fluid in the oil pipe flow channel and low-temperature fluid in the oil sleeve annulus flow channel, and the electric energy is input into the electric energy output module through the connecting cable;
s2, when the outlet of the cold fluid injection pump is connected with the oil casing annular flow channel through the cold fluid injection pipeline, the power generation method of the thermoelectric power generation system comprises the following steps:
s21, after entering a cold fluid injection pump for pressurization through a cold fluid outflow pipeline, the cold fluid stored in the cold fluid storage container enters an oil pipe flow channel through a cold fluid injection pipeline;
s22, absorbing partial heat from the hot fluid in the oil sleeve annulus flow channel in the process that the cold fluid flows downwards along the oil pipe flow channel, and keeping the temperature at a lower level;
s23, after the fluid reaches the bottom of the well, because the bottom of the well is sealed by cement, the fluid flowing out of the oil pipe flow channel enters the oil sleeve annulus flow channel from a gap between the bottom of the well and the bottom of the oil pipe, flows upwards to the ground along the oil sleeve annulus flow channel, enters a closed circulation outflow fluid flow pipeline, then enters a closed circulation outflow hot fluid utilization module, and returns to a cold fluid storage container through a cold fluid inflow pipeline after heat exchange and utilization;
s24, continuously performing heat exchange with surrounding strata in the upward flowing process of the oil sleeve annulus flow channel, enabling the temperature of the fluid in the oil sleeve annulus flow channel to be higher than that of the fluid in the oil pipe flow channel at the same depth, enabling the thermoelectric power generation module to generate electric energy under the action of the temperature difference between the high-temperature fluid in the oil sleeve annulus flow channel and the low-temperature fluid in the oil pipe flow channel, and inputting the electric energy into the electric energy output module through the connecting cable.
2. The method of generating power for a single well closed cycle downhole thermoelectric power generation system of claim 1, wherein the wellbore is a perforated structure drilled through a formation of a geothermal well by cementing the wellbore casing to the bottom of the well; the casing is tightly cemented to the geothermal well formation.
3. The method of generating power for a single well closed cycle downhole thermoelectric power generation system of claim 1, wherein the thermoelectric power generation module comprises a plurality of sets of thermoelectric power generators connected in series with one another; the thermoelectric generator comprises a plurality of groups of thermoelectric generating units; the thermoelectric power generation units comprise an N-type semiconductor and a P-type semiconductor, and the N-type semiconductor and the P-type semiconductor are alternately arranged between the adjacent thermoelectric power generation units.
4. The method of power generation for a single well closed cycle downhole thermoelectric power generation system of claim 1, wherein: the cross sections of the sleeve and the oil pipe are both circular; the sleeve and the oil pipe are coaxially arranged; the cross section of the thermoelectric power generation module is circular.
5. The method of power generation for a single well closed cycle downhole thermoelectric power generation system of claim 1, wherein the cold fluid injection pump and cold fluid storage vessel are both located on the surface.
6. The method of power generation for a single well closed cycle downhole thermoelectric power generation system of claim 1, wherein: the cold fluid is any one of water, liquid carbon dioxide and liquid nitrogen.
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| CN113374659B (en) * | 2021-06-18 | 2023-05-09 | 中国石油化工股份有限公司 | Dry-hot rock power generation system based on carbon dioxide closed circulation |
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| CN105958870B (en) * | 2016-06-29 | 2017-11-21 | 中国石油大学(华东) | Compound low-temperature receiver hot dry rock thermoelectric heat generation system and method |
| CN207063968U (en) * | 2017-03-06 | 2018-03-02 | 中国石油集团钻井工程技术研究院 | A kind of two wells connection circulates enhanced underground heat completion system |
| CN107939621B (en) * | 2017-12-01 | 2024-04-02 | 西安交通大学 | S-CO based on geothermal energy of heating dry rock of fin sleeve 2 Power generation system and method |
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