Geothermal energy system using open U-shaped wells to develop and utilize geothermal reservoirs

Abstract

The present application relates to the field of geothermal energy supply technology, and provides a geothermal energy supply system for developing and utilizing geothermal reservoirs using an open U-shaped well, including a geothermal component and an energy supply mechanism. The geothermal component has a connected screen and a heat exchanger to form a geothermal loop. The screen is set in the formation and filled with gravel on both sides of the screen. The screen has screen holes connecting the inside and outside. Heat conduction is formed between the screen, gravel and the formation. The geothermal fluid circulates in the geothermal loop and is heated by the screen, gravel and formation. The first energy supply unit in the energy supply mechanism is connected to the geothermal loop, and converts the kinetic energy and thermal energy of the geothermal fluid into electrical energy output. The second energy supply unit and the heat exchanger are correspondingly arranged, and convert the thermal energy of the geothermal fluid into electrical energy output. The third energy supply unit and the heat exchanger are correspondingly arranged, and the thermal energy of the geothermal fluid is transferred to the preset liquid in the third energy supply unit and output as thermal energy. Through such an arrangement, the charging efficiency and utilization rate of the geothermal fluid are improved.

Description

Technical Field

[0001] The present application relates to the field of geothermal energy supply technology, and in particular to a geothermal energy supply system that utilizes an open U-shaped well to develop and utilize a geothermal reservoir. Background Art

[0002] Hydrothermal geothermal resources are mainly developed by combining extraction and reinjection, that is, the extracted geothermal fluid is used for heat extraction and then reinjected into the heat reservoir.

[0003] In the related technology, the extraction and reinjection of geothermal fluids are completed through geothermal pipes. The reinjected geothermal fluids and the geothermal pipes in the formation form heat conduction to achieve the transfer of thermal energy, and continue to be extracted from the formation through geothermal pipes to complete the next geothermal energy supply cycle.

[0004] However, after reinjection, geothermal fluids are only charged with heat through the walls of geothermal pipes, resulting in a decrease in the energy extraction and utilization rate of geothermal fluids. Summary of the invention

[0005] The present application provides a geothermal energy supply system for developing and utilizing geothermal reservoirs using an open U-shaped well, which can improve the extraction and utilization rate of geothermal fluids.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions:

[0007] The present application provides a geothermal energy supply system for developing and utilizing geothermal reservoirs using an open U-shaped well, comprising:

[0008] A geothermal component includes a sieve pipe, a first heat exchanger and a second heat exchanger. The sieve pipe is arranged in a formation. Both the inner and outer sides of the sieve pipe are filled with gravel. The sieve pipe has sieve holes. The sieve holes connect the inner and outer sides of the sieve pipe. The sieve pipe, the first heat exchanger and the second heat exchanger are connected end to end in sequence to form a geothermal loop. The geothermal fluid circulates in the geothermal loop.

[0009] The energy supply mechanism includes a first energy supply unit, a second energy supply unit and a third energy supply unit, wherein the first energy supply unit is connected in series between the first end of the screen tube and the first heat exchanger, and the first energy supply unit includes a first generator, and the first generator is configured to generate electric energy driven by geothermal fluid;

[0010] The second energy supply unit and the first heat exchanger are correspondingly arranged, the liquid heat-conducting medium flows in the second energy supply unit, the liquid heat-conducting medium is heated by the geothermal fluid through the first heat exchanger and converted into a gaseous state, the second energy supply unit includes a second generator, and the second generator is configured to generate electric energy under the drive of the gaseous heat-conducting medium;

[0011] The third energy supply unit and the second heat exchanger are correspondingly arranged, a preset liquid flows in the third energy supply unit, the preset liquid is heated by the geothermal fluid through the second heat exchanger, and the third energy supply unit is configured to supply the heated preset liquid to the outside.

[0012] The sieve pipe of the geothermal energy supply system provided by the present application is located in the formation, and there is heat conduction between the sieve pipe itself and the formation. When the geothermal fluid flows in the sieve pipe, it will be heated by the sieve pipe. Gravel is filled on both sides of the sieve pipe, and the gravel is heated in the formation. The geothermal fluid contacts the gravel during the flow, and the gravel and the formation heat the geothermal fluid at the same time. The geothermal fluid on both sides of the sieve pipe can flow along the sieve pipe. The sieve holes on the sieve pipe can increase the contact area between the geothermal fluid and the formation, further improving the charging efficiency of the geothermal fluid and the utilization rate of the formation energy. The geothermal fluid acts on the first generator of the first energy supply unit, converting part of the kinetic energy and thermal energy of the geothermal fluid into electrical energy output. The geothermal fluid continues to flow and transfers part of the thermal energy to the heat-conducting medium in the second energy supply unit. The heat-conducting medium acts on the second generator of the second energy supply unit with this part of the thermal energy, realizing the re-conversion of the thermal energy of the geothermal fluid into electrical energy. Furthermore, the geothermal fluid heats the preset liquid in the third energy supply unit, and the heated preset liquid is supplied to the outside. The third energy supply unit uses the thermal energy of the geothermal fluid to achieve thermal energy output with the preset liquid. In this way, the energy of the geothermal fluid is fully utilized through the energy supply mechanism and converted into various forms of energy output, thereby improving the energy utilization rate of the geothermal fluid. In addition, the circulation of geothermal fluid in the geothermal loop can avoid the damage to the stratum structure caused by long-term and continuous exploitation of geothermal fluid, forming an environmentally friendly geothermal energy supply technology.

[0013] As a possible implementation manner, the screen tube extends along a first direction, and the first direction and a horizontal direction form an angle.

[0014] As a possible implementation, the diameter of the sieve hole is smaller than the particle size of the gravel;

[0015] The strata include sand and gravel, and the particle size of the gravel is 5-6 times the median particle size of the sand and gravel.

[0016] As a possible implementation, the geothermal component includes a gas-liquid separator, the gas-liquid separator and the first energy supply unit are connected in series to the first end of the sieve tube, and the gas-liquid separator is connected to the first heat exchanger;

[0017] The first energy supply unit also includes a first steam turbine, which is arranged between the gas-liquid separator and the first generator, and is connected to the geothermal circuit. The first steam turbine includes a first impeller, and the geothermal fluid acts on the first impeller and drives the first generator to generate electricity.

[0018] As a possible implementation, the second energy supply unit includes a condensate pump, a third heat exchanger and a second steam turbine, the second steam turbine, the third heat exchanger and the condensate pump are connected end to end in sequence, and the first heat exchanger is arranged between the condensate pump and the second steam turbine, and the second steam turbine and the second generator are arranged correspondingly;

[0019] The second steam turbine includes a second impeller. The gaseous heat transfer medium acts on the second impeller and drives the second generator to generate electrical energy.

[0020] As a possible implementation manner, the second energy supply unit further includes an electric heater, which is disposed between the condensation pump and the first heat exchanger, and is configured to heat the liquid heat transfer medium.

[0021] As a possible implementation, the geothermal component further includes at least one flow valve, and the at least one flow valve is disposed between the second heat exchanger and the second end of the sieve tube.

[0022] As a possible implementation, the geothermal assembly further includes a sedimentation tank and a filter, the sedimentation tank and the filter are connected in series and disposed between the second heat exchanger and the second end of the sieve tube;

[0023] There are two flow valves, one of which is arranged between the second heat exchanger and the sedimentation tank, and the other flow valve is arranged between the filter and the second end of the screen tube.

[0024] As a possible implementation, the filter includes at least a first filter and a second filter, the first filter and the second filter are connected in series and arranged between the sedimentation tank and the second end of the screen tube;

[0025] The filtering accuracy of the first filter is 50-80 μm, and the filtering accuracy of the second filter is 2-5 μm.

[0026] As a possible implementation, the geothermal component also includes a pressure relief valve, which is arranged between the second heat exchanger and the second end of the screen tube, and the pressure relief valve is configured to open and discharge the air in the geothermal loop when the pressure in the geothermal loop is greater than a preset pressure value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 A schematic diagram of the structure of the geothermal energy supply system provided in an embodiment of the present application.

[0029] Description of reference numerals:

[0030] 100-Geothermal energy system;

[0031] 1-geothermal component; 11-screen tube; 12-first heat exchanger; 13-second heat exchanger; 14-gravel;

[0032] 2- Energy supply mechanism;

[0033] 21-first energy supply unit; 211-first generator; 212-first steam turbine;

[0034] 22-second energy supply unit; 221-second generator; 222-condensate pump; 223-third heat exchanger; 224-second steam turbine; 225-electric heater;

[0035] 23- the third energy supply unit;

[0036] 3-gas-liquid separator; 4-sterilization device; 6-cyclone desander; 7-flow valve; 8-sedimentation tank;

[0037] 9-filter; 9a-first filter; 9b-second filter; 10-pressure relief valve;

[0038] 200- casing;

[0039] 300-Cement. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0041] Hydrothermal geothermal resources are mainly developed by combining extraction and reinjection, that is, the extracted geothermal fluid is used for heat extraction and then reinjected into the heat reservoir.

[0042] In the related technology, the extraction and reinjection of geothermal fluids are completed through geothermal pipes. The reinjected geothermal fluids and the geothermal pipes in the formation form heat conduction to achieve the transfer of thermal energy, and continue to be extracted from the formation through geothermal pipes to complete the next geothermal energy supply cycle.

[0043] However, after reinjection, geothermal fluids are only charged with heat through the walls of geothermal pipes, resulting in a decrease in the energy extraction and utilization rate of geothermal fluids.

[0044] In order to overcome the defects in the prior art, the present application provides a geothermal energy supply system for developing and utilizing geothermal reservoirs using an open U-shaped well, including a geothermal component and an energy supply mechanism. The geothermal component has a sieve pipe and a heat exchanger that are interconnected to form a geothermal loop. The sieve pipe is arranged in the formation, and gravel is filled on both the inner and outer sides of the sieve pipe. The sieve pipe has sieve holes. Heat conduction is formed between the sieve pipe, gravel, formation and geothermal fluid. The heat in the formation heats the sieve pipe, gravel and geothermal fluid. The geothermal fluid circulates in the geothermal loop and can also be heated by the sieve pipe gravel and formation. The energy supply mechanism includes multiple energy supply units. The first energy supply unit is connected to the geothermal circuit. The first kinetic energy unit can convert the kinetic energy and thermal energy of the geothermal fluid into electrical energy output. The second energy supply unit and the heat exchanger are correspondingly arranged. The second energy supply unit converts the thermal energy of the geothermal fluid into electrical energy output through the heat exchanger. The third energy supply unit and the heat exchanger are correspondingly arranged. The third energy supply unit transfers the thermal energy of the geothermal fluid to the preset liquid flowing in the third energy supply unit through the heat exchanger, and the preset liquid outputs this part of the thermal energy. Through such a setting, the heat source of the geothermal fluid in the formation is increased, the charging efficiency of the geothermal fluid is improved, the energy supply unit converts the thermal energy of the geothermal fluid into various forms of energy for output, and the energy utilization rate of the geothermal fluid is improved.

[0045] The content of the present invention will be described in detail below in conjunction with the accompanying drawings so that those skilled in the art can understand the content of the present invention more clearly and in detail.

[0046] Figure 1 A schematic diagram of the structure of the geothermal energy supply system provided in an embodiment of the present application.

[0047] like Figure 1 As shown, this embodiment provides a geothermal energy supply system 100 for developing and utilizing geothermal reservoirs using an open U-shaped well, including a geothermal component 1 and an energy supply mechanism 2. The geothermal component 1 is partially located in the formation, and extracts the geothermal fluid from the formation. The geothermal fluid completes the energy charging process in the formation, and then outputs this part of energy in different forms through the energy supply mechanism 2.

[0048] Among them, the geothermal component 1 includes a sieve pipe 11, a first heat exchanger 12 and a second heat exchanger 13. The sieve pipe 11 is arranged in the formation. The inner and outer sides of the sieve pipe 11 are filled with gravel 14. The sieve pipe 11 has sieve holes, and the sieve holes connect the inner and outer sides of the sieve pipe 11. The sieve pipe 11, the first heat exchanger 12 and the second heat exchanger 13 are connected end to end in sequence to form a geothermal loop, and the geothermal fluid circulates in the geothermal loop.

[0049] The energy supply mechanism 2 includes a first energy supply unit 21, a second energy supply unit 22 and a third energy supply unit 23. The first energy supply unit 21 is connected in series between the first end of the screen pipe 11 and the first heat exchanger 12. The first energy supply unit 21 includes a first generator 211. The first generator 211 is configured to generate electrical energy driven by geothermal fluid.

[0050] The second energy supply unit 22 and the first heat exchanger 12 are arranged correspondingly. The liquid heat-conducting medium flows in the second energy supply unit 22. The liquid heat-conducting medium is heated by the geothermal fluid through the first heat exchanger 12 and converted into a gas. The second energy supply unit 22 includes a second generator 221. The second generator 221 is configured to generate electrical energy under the drive of the gaseous heat-conducting medium.

[0051] The third energy supply unit 23 and the second heat exchanger 13 are correspondingly arranged, a preset liquid flows in the third energy supply unit 23, the preset liquid is heated by the geothermal fluid through the second heat exchanger 13, and the third energy supply unit 23 is configured to supply the heated preset liquid to the outside.

[0052] In this embodiment, the sieve 11 is located in the formation, and there is heat conduction between the sieve 11 itself and the formation. When the geothermal fluid flows in the sieve 11, it will be heated by the sieve 11. The sieve 11 has sieve holes, and the geothermal fluid can contact the formation through the sieve holes and conduct heat with the formation. The inner and outer sides of the sieve 11 are filled with gravel 14, and the gravel 14 is heated in the formation. The geothermal fluid contacts the gravel 14 during the flow, and the gravel 14 and the sieve 11 heat the geothermal fluid at the same time, thereby improving the charging efficiency of the geothermal fluid and the utilization rate of the formation energy. The geothermal fluid acts on the first generator 211 of the first energy supply unit 21, converting part of the kinetic energy and thermal energy of the geothermal fluid into electrical energy output. The geothermal fluid continues to flow and transfers part of the thermal energy to the heat-conducting medium in the second energy supply unit 22. The heat-conducting medium acts on the second generator 221 of the second energy supply unit 22 with this part of the thermal energy, realizing the re-conversion of the thermal energy of the geothermal fluid into electrical energy. Furthermore, the geothermal fluid heats the preset liquid in the third energy supply unit 23, and the heated preset liquid is supplied to the outside. The third energy supply unit 23 uses the thermal energy of the geothermal fluid to achieve thermal energy output with the preset liquid. In this way, the energy of the geothermal fluid is fully utilized through the energy supply mechanism 2 and converted into various forms of energy output, thereby improving the energy utilization rate of the geothermal fluid. In addition, the circulation of the geothermal fluid in the geothermal loop can avoid the damage to the stratum structure caused by the long-term and continuous exploitation of the geothermal fluid, forming an environmentally friendly geothermal energy supply technology.

[0053] It should be noted that the geothermal fluid in this embodiment is groundwater, and other forms of groundwater in different temperature environments, such as gas and liquid.

[0054] In the specific implementation process, it is necessary to explore the geology of the geothermal mining location, obtain geological information of the mining location, and determine the location where the screen 11 is placed in the formation. The geothermal loop has two wellheads, one wellhead as the outlet of the geothermal fluid, and the other wellhead as the return port of the geothermal fluid. The two wellheads are arranged in the vertical direction. The specific drilling process is as follows:

[0055] The first well opening adopts the conventional drilling method, and the casing 200 is lowered and cement 300 is injected to perform the first well cementing operation; the second well opening is to drill to the preset position of the screen 11, the casing 200 is lowered again, and cement 300 is injected and returned to the ground to fix the casing 200.

[0056] The screen pipe 11 is lowered through the wellhead that serves as the return port. Specifically, a diverter is used for side drilling and window opening operations, a power drilling tool is used for directional inclination, and the wellbore trajectory is tracked and controlled by the rotary drill's stabilizer drilling tool combination to ensure that the horizontal section of the wellbore is in the middle of the formation. The screen pipe 11 is suspended on the upper casing 200 and lowered into the formation. In order for the two wellheads to be connected in the formation through the screen pipe 11 to form a flow loop of the geothermal fluid, it is necessary to lower a rotating magnetic guide instrument into the wellhead that serves as the outlet of the geothermal fluid, and lower a strong magnetic joint into the screen pipe 11. The receiving device on the ground receives the pulse signal, which is then converted into an electrical signal to generate an electromagnetic sensor image to determine the position of the screen pipe 11 and the wellhead, thereby achieving precise docking. In this way, the geothermal loop presents a U-shaped loop, in which the screen pipe 11 is in the formation. The heat in the formation heats the flowing geothermal fluid through the screen pipe 11, realizing the heat charging of the circulating geothermal fluid.

[0057] The screen tube 11 in this embodiment is filled with gravel 14 on both sides inside and outside. The heat in the formation will also heat the gravel 14. When the geothermal fluid flows in the screen tube 11, the geothermal fluid contacts the gravel 14 in the screen tube 11, further heating and charging the geothermal fluid. In this way, through the cooperation of the gravel 14 and the screen tube 11, the energy source of the geothermal fluid is expanded and the energy acquisition efficiency of the geothermal fluid is improved. When the geothermal fluid acquires energy in the formation, it flows to the outside of the formation along the geothermal loop, and then the energy carried by the geothermal fluid is converted and output in various forms through the energy supply mechanism 2.

[0058] The screen pipe 11 is set in the formation. There is geothermal fluid in the formation. Screen holes are set on the screen pipe 11 to connect the inside and outside of the screen pipe 11. The geothermal fluid in the formation can be heated in the formation through the gravel outside the screen pipe 11, and then enter the screen pipe 11 through the screen holes, and merge with the geothermal fluid in the geothermal loop. These two parts of geothermal fluid circulate together in the geothermal loop. In this way, the geothermal fluid that has released heat energy in the previous flow cycle returns to the screen pipe 11, and can obtain heat energy through the pipe wall of the screen pipe 11, and can also obtain heat energy through the gravel 14 on the inside and outside of the screen pipe 11. Moreover, the geothermal fluid can also flow into the formation through the screen holes and be heated by the formation. Such a screen pipe 11 can increase the energy enhancement pathways of the geothermal fluid, thereby improving the energy charging efficiency of the geothermal fluid, and then improving the energy utilization rate of the geothermal fluid.

[0059] In addition, after the geothermal fluid completes a cycle, it returns to the screen pipe 11. Due to the setting of the screen holes on the screen pipe 11, the geothermal fluid will also flow into the formation through the screen holes, so that the formation pressure can be kept stable and the impact of geothermal fluid extraction on the geological structure can be avoided.

[0060] It should be noted that this embodiment does not limit the number of sieve holes, and the distribution of the sieve holes on the sieve pipe 11 is not specifically limited. The number and distribution of the sieve holes can be determined according to the geological structure and parameters in the actual production process.

[0061] The energy supply mechanism 2 includes a first energy supply unit 21, and the first energy supply unit 21 is connected to the geothermal circuit. Specifically, the first energy supply unit 21 is connected to the first end of the screen tube 11, and the geothermal fluid can flow in the first energy supply unit 21. The first energy supply unit 21 includes a first generator 211. When the geothermal fluid flows in the first energy supply unit 21, the geothermal fluid has kinetic energy and thermal energy, and the geothermal fluid can drive the first generator 211 to do work. The first generator 211 uses the kinetic energy and thermal energy of the geothermal fluid to output electrical energy. The geothermal fluid continues to flow after completing the first energy conversion in the first energy supply unit 21, and completes the second energy conversion at the first heat exchanger 12 and the second energy supply unit 22.

[0062] Exemplarily, a first heat exchanger 12 is provided on the geothermal loop, and the second energy supply unit 22 is provided corresponding to the first heat exchanger 12, and a liquid heat-conducting medium flows in the second energy supply unit 22. The liquid heat-conducting medium and the geothermal fluid complete heat exchange at the first heat exchanger 12 and are converted into a gaseous state. It can be understood that the geothermal fluid releases heat through the first heat exchanger 12 to heat the heat-conducting medium. The heat-conducting medium has thermal energy, and the heat-conducting medium has kinetic energy when flowing in the second energy supply unit 22. The thermal energy and kinetic energy of the heat-conducting medium act on the second generator 221 of the second energy supply unit 22, and the second generator 221 generates electrical energy and outputs it to the outside. In this way, the second energy supply unit 22 realizes the re-conversion of the thermal energy of the geothermal fluid, and outputs it in the form of electrical energy, thereby improving the energy utilization rate of the geothermal fluid. After the second energy conversion is completed in the second energy supply unit 22, the geothermal fluid continues to flow, and completes the third energy transfer with the third energy supply unit 23 at the second heat exchanger 13.

[0063] Specifically, the third energy supply unit 23 and the second heat exchanger 13 are correspondingly arranged, and a preset liquid flows in the third energy supply unit 23, and the preset liquid and the geothermal fluid have a temperature gradient, so that the geothermal fluid forms heat conduction with the preset liquid at the second heat exchanger 13 to heat the preset liquid in the third energy supply unit 23, and the heated preset liquid can be transported to the outside and can be used as daily hot water or as heating hot water. In this way, on the basis of the above-mentioned embodiment, through the cooperation of the energy supply mechanism 2 and the geothermal component 1, the multiple utilization and conversion of the energy carried by the geothermal fluid is realized, and the diversity of the energy conversion of the geothermal fluid and the energy utilization rate of the geothermal fluid are improved.

[0064] The arrangement of the screen pipe 11 in the formation also affects the charging efficiency of the geothermal fluid. As a possible implementation, the screen pipe 11 extends along a first direction, and the first direction and the horizontal direction have an angle.

[0065] The screen tube 11 extends along the first direction, and there is an angle between the first direction and the horizontal direction. When the angle is 0°, the screen tube 11 extends along the horizontal direction. Of course, in the actual production process, the screen tube 11 will inevitably have a certain angle with the horizontal direction, but it can still ensure that the screen tube 11 extends along the horizontal direction as a whole, so this embodiment does not limit the size of the angle.

[0066] Furthermore, the distance that the sieve 11 extends along the first direction affects the charging efficiency of the geothermal fluid in the sieve 11. It can be understood that the longer the distance that the sieve 11 extends along the first direction, the longer the time that the geothermal fluid flows in the formation, so that the geothermal fluid can obtain more energy. Furthermore, ensuring that there is a large temperature difference between the temperature of the geothermal fluid at the first end of the sieve 11 and the second end of the sieve 11 can prevent the geothermal fluid from forming a thermal breakthrough in the formation, resulting in a reduction in the energy utilization rate of the geothermal fluid by the energy supply mechanism 2.

[0067] The size of the sieve holes on the sieve tube 11 affects the structural strength of the sieve tube 11 and the impurity content in the geothermal circuit. The particle size of the gravel 14 filled in the sieve tube 11 also affects the charging efficiency of the geothermal fluid to a certain extent. Therefore, in this embodiment, the diameter of the sieve holes is smaller than the particle size of the gravel 14; the formation includes sand and gravel, and the particle size of the gravel 14 is 5-6 times the median of the sand and gravel particle size.

[0068] If the sieve holes on the screen 11 are too large, the geothermal fluid will bring in a lot of impurities in the formation, such as sand and gravel in the formation, during its flow in the formation. Furthermore, if the sieve holes are too large, in order to ensure the structural strength of the screen 11, the structure or wall thickness of the screen 11 will be increased, which will lead to a decrease in the filling rate of the gravel 14, and a decrease in the effective contact rate between the geothermal fluid and the gravel 14 in the screen 11, resulting in a poor charging effect of the geothermal fluid. Therefore, the diameter of the sieve holes is related to the size of the sand and gravel in the formation and the gravel 14 filled in the screen 11. In this way, the diameter of the sieve holes on the screen 11 in this embodiment should be smaller than the diameter of the gravel 14, which can effectively prevent the gravel 14 from escaping from the sieve holes on the screen 11 during the flow of the geothermal fluid, and can also prevent the gravel outside the screen 11 from entering the screen 11, thereby ensuring the charging effect of the geothermal fluid during the flow.

[0069] It can be understood that the size of the gravel 14 is relatively small, the filling density of the gravel 14 on both sides of the screen 11 is relatively large, and the gaps between the gravel 14 are relatively small. In this way, the filled gravel 14 forms an obstacle to the flow of sand and gravel in the formation, effectively reducing the sand and gravel penetration in the geothermal loop. However, due to the large filling density of the gravel 14 and the relatively small gaps between the gravel 14, the gravel 14 also forms an obstacle to the flow of the geothermal fluid, resulting in a decrease in the fluidity of the geothermal fluid. In order to ensure the smooth operation of the geothermal energy supply system 100, the geothermal loop needs more energy consumption to improve the fluidity of the geothermal fluid, which leads to an increase in the energy consumption of the geothermal loop. On the contrary, when the size of the gravel 14 is large, the sand and gravel penetration in the geothermal loop increases, and the flow rate of the geothermal fluid increases, which will lead to insufficient contact between the geothermal fluid and the gravel 14, a short heat conduction time, and a small effective area of ​​heat conduction, which then reduces the energy obtained by the geothermal fluid in the formation. Therefore, through research, it is found that the particle size of the gravel 14 is 5-6 times the median particle size of the sand and gravel. In this way, the fluidity of the geothermal fluid in the formation and the screen 11 can be guaranteed, while the energy charging effect of the geothermal fluid flowing in the screen 11 is improved, and the energy carried by the geothermal fluid flowing out of the formation is increased. After the gravel 14 is filled, the gap formed between the gravels 14 is 1 / 2-2 / 3 of the minimum particle size of the gravel 14.

[0070] In addition, during the specific implementation process, the diameter of the screen tube 11 needs to ensure the filling density of the gravel 14, the diameter of the screen tube 11 needs to ensure the flow of geothermal fluid, and it is also necessary to ensure that the filling thickness of the gravel 14 is greater than 30 mm. Therefore, in the actual production process, it is sufficient to ensure that the diameter of the screen tube 11 meets the above structural requirements.

[0071] The temperature of the formation is relatively high. After the geothermal fluid flowing in the formation is heated in the formation, the geothermal fluid discharged through the wellhead is essentially a gas-liquid mixture. Such geothermal fluid can also directly act on the first generator 211 to make the first generator 211 work and generate electricity. In this way, the energy utilization rate of the geothermal fluid will decrease. As a possible implementation, the geothermal component 1 includes a gas-liquid separator 3, the gas-liquid separator 3 and the first energy supply unit 21 are connected in series to the first end of the sieve pipe 11, and the gas-liquid separator 3 is connected to the first heat exchanger 12; the first energy supply unit 21 also includes a first steam turbine 212, the first steam turbine 212 is arranged between the gas-liquid separator 3 and the first generator 211, and the first steam turbine 212 is connected to the geothermal circuit, the first steam turbine 212 includes a first impeller, and the geothermal fluid acts on the first impeller and drives the first generator 211 to generate electricity. In this way, the gas-liquid mixture in the geothermal fluid is separated by the gas-liquid separator 3, and the energy carried by the gaseous geothermal fluid is first converted into electrical energy and output.

[0072] In the specific implementation process, after the geothermal fluid flows out of the formation, it needs to be sterilized to reduce the chemical reaction between the microorganisms in the formation and the pipeline, and reduce the maintenance cost of the geothermal energy supply system 100. Therefore, a sterilization device 4 can be set in the geothermal loop, and the geothermal fluid is directly passed into the sterilization device 4 after it comes out of the formation to sterilize the microorganisms carried by the geothermal fluid. The sterilization device 4 contains chlorine dioxide, and the geothermal fluid can be quickly sterilized by the action of chlorine dioxide. At this time, the geothermal fluid contains sand and gravel in the formation, and the geothermal fluid needs to be separated from the sand and gravel to prevent the first generator 211 from being damaged by the sand and gravel when the first fluid acts on the first generator 211. A cyclone desander 6 can be added to the geothermal loop, and the geothermal fluid is passed into the cyclone desander 6 after sterilization. Under the centrifugal action of the cyclone desander 6, the geothermal fluid can separate the sand and gravel and discharge the geothermal fluid at the same time.

[0073] The outlet of the gas-liquid separator 3 and the cyclone desander 6 in this embodiment are connected, and the two output ends of the gas-liquid separator 3 are respectively connected to the first heat exchanger 12 and the first steam turbine 212. The geothermal fluid flows into the gas-liquid separator 3, and the geothermal fluid will be separated into gas and liquid. The gas flows to the first steam turbine 212 through the output end of the gas-liquid separator 3, and acts on the first impeller of the first steam turbine 212. The gaseous geothermal fluid drives the first steam turbine to rotate and drives the first generator 211 to generate electrical energy. In this way, the initial energy conversion of the geothermal fluid can be achieved. It should be noted that there is a certain pressure in the geothermal energy supply system 100, and the gaseous geothermal fluid itself has a certain gas pressure and temperature. At the same time, the gaseous geothermal fluid has gas kinetic energy during the flow process. The kinetic energy and thermal energy of the gaseous geothermal fluid act on the first impeller. Through the mutual cooperation of the first steam turbine 212 and the first generator 211, this part of energy is converted into electrical energy. In this process, the gaseous geothermal fluid is transformed into liquid geothermal fluid after heat transfer, the first steam turbine is connected to the geothermal loop, and this part of the geothermal fluid will return to the geothermal loop again.

[0074] It can be understood that the liquid geothermal fluid flows out through the output end of the gas-liquid separator 3 and continues to flow in the geothermal loop to the first heat exchanger 12, completes heat exchange with the second energy supply unit 22 at the first heat exchanger 12, and completes energy conversion through the second energy supply unit 22.

[0075] Exemplarily, the second heating unit in this embodiment includes a condensate pump 222, a third heat exchanger 223 and a second steam turbine 224. The second steam turbine 224, the third heat exchanger 223 and the condensate pump 222 are connected end to end in sequence, and the first heat exchanger 12 is arranged between the condensate pump 222 and the second steam turbine 224. The second steam turbine 224 and the second generator 221 are arranged correspondingly. The second steam turbine 224 includes a second impeller, and the gaseous heat-conducting medium acts on the second impeller and drives the second generator 221 to generate electricity. In this way, the geothermal fluid and the heat-conducting medium complete heat exchange at the first heat exchanger 12, and the heated gaseous heat-conducting medium acts on the second steam turbine 224 to drive the second generator 221 to do work and generate electricity, thereby improving the energy utilization rate of the geothermal fluid.

[0076] The heat-conducting medium flows in the second heat supply unit, flows to the second heat exchanger 13 and forms heat exchange with the geothermal fluid, the liquid heat-conducting medium absorbs the heat of the geothermal fluid and turns into a gaseous state, and the gaseous heat-conducting medium flows to the second steam turbine 224, driving the second impeller of the second steam turbine 224 to rotate, thereby driving the second generator 221 to do work and generate electricity. The gaseous heat-conducting medium acts on the second impeller and releases heat through the third heat exchanger 223, and turns into a liquid heat-conducting medium. The liquid heat-conducting medium continues to flow in the second energy supply unit 22 driven by the condensation pump 222 to complete the next cycle. In this process, the second utilization of the energy of the geothermal fluid is achieved through the setting of the second energy supply unit 22. On the basis of the above-mentioned embodiment, the energy of the geothermal fluid is converted twice to improve the energy utilization rate of the geothermal fluid.

[0077] Furthermore, the second energy supply unit 22 also includes an electric heater 225, which is disposed between the condensate pump 222 and the first heat exchanger 12, and is configured to heat the liquid heat-conducting medium. In this way, the heat-conducting medium in the second energy supply unit 22 is heated by the electric heater 225 and the geothermal fluid, thereby improving the efficiency of the heat-conducting medium being converted from liquid to gas in the second energy supply unit 22, so that the gaseous heat-conducting medium acts more on the second impeller of the second steam turbine 224, thereby improving the efficiency of the second generator 221 in generating electrical energy.

[0078] It should be noted that the heat-conducting medium in this embodiment is butyl chloride, n-butane, isobutane, isopentane and Freon.

[0079] The geothermal fluid that completes heat exchange at the first heat exchanger 12 continues to flow along the geothermal loop, and forms heat conduction again with the preset liquid flowing at the second heat exchanger 13 and in the third energy supply unit 23 to heat the preset liquid. The heated preset liquid can be used for external heating, domestic hot water supply, hot spring bathing supply, etc.

[0080] The geothermal fluid in the geothermal energy supply system 100 circulates in the geothermal loop. To ensure the smooth operation of the geothermal energy supply system 100, the geothermal fluid has a certain flow pressure. When the geothermal fluid flows back to the screen pipe 11 to be recharged, the flow pressure of the geothermal fluid is too large, which will have a certain impact on the formation. Long-term continuous flow is likely to cause formation migration and destroy the formation structure. Therefore, a flow valve 7 can be set on the geothermal component 1 to control the flow rate and flow pressure of the geothermal fluid circulating into the screen pipe 11. As a possible implementation method, the geothermal component 1 in this embodiment also includes at least one flow valve 7, and at least one flow valve 7 is set between the second heat exchanger 13 and the second end of the screen pipe 11.

[0081] Exemplarily, the flow valve 7 in this embodiment can be one, which is arranged between the second heat exchanger 13 and the second end of the sieve tube 11, so that the flow rate of the geothermal fluid returning to the sieve tube 11 can be controlled by the opening and closing degree of the flow valve 7 to prevent the flow rate and flow velocity of the geothermal fluid from being too large and causing impact on the formation.

[0082] Of course, there may be multiple flow valves 7 in this embodiment, which are connected in series and arranged between the second heat exchanger 13 and the second end of the sieve tube 11. The multiple flow valves 7 can be controlled individually, so that the flow rate and flow velocity of the geothermal fluid can be gradually reduced, thereby improving the working stability of the geothermal energy supply system 100 and avoiding the damage of the geothermal fluid to the formation.

[0083] The geothermal energy supply system 100 needs to be connected by pipelines to form a flow path for the geothermal fluid. During the long-term circulation of the geothermal fluid, some impurities will be formed in the pipeline, or the geothermal fluid and the pipeline will undergo a certain degree of chemical reaction, and these impurities and chemicals will return to the formation, which may pollute the formation. Therefore, some mechanisms can be set in the geothermal loop to purify the geothermal fluid, and then the geothermal fluid is passed into the formation, so that the impurities and chemicals in the geothermal energy supply system 100 can be prevented from polluting the formation.

[0084] Thus, the geothermal component 1 in this embodiment also includes a sedimentation tank 8 and a filter 9, which are connected in series and arranged between the second heat exchanger 13 and the second end of the sieve tube 11; there are two flow valves 7, one of the two flow valves 7 is arranged between the second heat exchanger 13 and the sedimentation tank 8, and the other flow valve 7 is arranged between the filter 9 and the second end of the sieve tube 11.

[0085] It can be understood that before the geothermal fluid returns to the formation, it is settled in the sedimentation tank 8. Physical sedimentation can be used to settle impurities such as mud and sand. Furthermore, chemical sedimentation can be used. For example, a descaling agent is added to the sedimentation tank 8. The coagulation and dispersion effect of the descaling agent can make the impurities in the geothermal fluid quickly form floccules and settle, so as to improve the purification efficiency of the geothermal fluid, and then increase the circulation rate of the geothermal fluid in the geothermal energy supply system 100, thereby improving the energy utilization efficiency of the geothermal energy supply system 100.

[0086] A large amount of geothermal fluid is passed into the sedimentation tank 8, which causes the sedimentation pressure of the sedimentation tank 8 to increase. A flow valve 7 can be set between the second heat exchanger 13 and the sedimentation tank 8 to control the flow of the geothermal fluid into the sedimentation tank 8 through the flow valve 7. In this way, the flow valve 7 can be reasonably controlled according to the actual sedimentation conditions of the sedimentation tank 8 to keep the geothermal energy supply system 100 in a stable working state.

[0087] The precipitated geothermal fluid is further purified by the filtering action of the filter 9, so as to prevent the geothermal fluid from circulating into the stratum and causing irreversible pollution.

[0088] In this embodiment, a flow valve 7 is also provided between the filter 9 and the second end of the screen tube 11. The opening and closing of the flow valve 7 here can control the flow rate and flow rate of the geothermal fluid after being filtered by the filter 9, thereby preventing the fluid pressure of the geothermal fluid from causing irreparable geological damage to the formation.

[0089] Exemplarily, the filter 9 in this embodiment includes at least a first filter 9a and a second filter 9b, which are connected in series and arranged between the sedimentation tank 8 and the second end of the sieve tube 11; the filtering accuracy of the first filter 9a is 50-80 μm, and the filtering accuracy of the second filter 9b is 2-5 μm. By connecting a plurality of filters 9 with different filtering accuracies in series, the purity of the geothermal fluid before entering the formation is improved, thereby preventing the geothermal fluid from polluting the formation.

[0090] For example, the filtering accuracy of the first filter 9a can be selected as 50μm, and the filtering accuracy of the second filter 9b can be selected as 2μm or 5μm and any one of the filtering accuracy between 2-5μm. Of course, the filtering accuracy of the first filter 9a can also be selected as 80μm, and the filtering accuracy of the second filter 9b can be selected as 2μm or 5μm and any one of the filtering accuracy between 2-5μm. In the specific practice process, the filtering accuracy of the first filter 9a and the filtering accuracy of the second filter 9b need to be reasonably selected in combination with the actual geological environment parameters and the impurities carried by the geothermal fluid in the geothermal loop. This embodiment does not specifically limit the combination of the filtering accuracy of the first filter 9a and the second filter 9b. It should be noted that the geothermal fluid filtered by the second filter 9b needs to meet the emission standards for returning to the formation.

[0091] As an embodiment, the geothermal component 1 also includes a pressure relief valve 10, which is arranged between the second heat exchanger 13 and the second end of the screen tube 11. The pressure relief valve 10 is configured to open to discharge the air in the geothermal loop when the pressure in the geothermal loop is greater than a preset pressure value.

[0092] It can be understood that when the geothermal fluid flows in the formation, it completes charging in the formation. During the charging process, the temperature of the geothermal fluid rises. Since the formation temperature is relatively high, part of the geothermal fluid is heated and transformed from liquid to gas. The increase in the gaseous geothermal fluid will cause the pressure of the geothermal energy supply system 100 to increase, and will also cause the fluidity of the geothermal fluid to decrease, further leading to an increase in the operating energy consumption of the geothermal energy supply system 100. In this embodiment, a pressure relief valve 10 is set on the geothermal loop. When the pressure in the geothermal loop is greater than the preset pressure value, the pressure relief valve 10 opens to discharge the air in the geothermal loop. In this way, the system pressure in the geothermal loop can be kept stable, reducing the overall energy consumption of the geothermal energy supply system 100.

[0093] It should be noted that the preset pressure value in this embodiment needs to be determined based on parameters such as the geological environment in actual production and the structure of the geothermal loop in the formation. Therefore, this section does not make specific restrictions on the preset pressure value.

[0094] The geothermal energy supply system provided in this embodiment includes a geothermal component and an energy supply mechanism. The geothermal component includes a sieve pipe, a first heat exchanger and a second heat exchanger. The sieve pipe is arranged in the formation. The inner and outer sides of the sieve pipe are filled with gravel. The sieve pipe has sieve holes. The sieve holes connect the inner and outer sides of the sieve pipe. The sieve pipe, the first heat exchanger and the second heat exchanger are connected end to end in sequence to form a geothermal loop. The geothermal fluid circulates in the geothermal loop. The energy supply mechanism includes a first energy supply unit, a second energy supply unit and a third energy supply unit. The first energy supply unit is connected in series between the first end of the sieve pipe and the first heat exchanger. The first energy supply unit includes a first generator. The first generator is configured to generate electricity under the drive of the geothermal fluid. The second energy supply unit and the first heat exchanger are correspondingly arranged. The liquid heat-conducting medium flows in the second energy supply unit. The liquid heat-conducting medium is heated by the geothermal fluid through the first heat exchanger and converted into a gaseous state. The second energy supply unit includes a second generator. The second generator is configured to generate electricity under the drive of the gaseous heat-conducting medium. The third energy supply unit is correspondingly arranged with the second heat exchanger, the preset liquid flows in the third energy supply unit, the preset liquid is heated by the geothermal fluid through the second heat exchanger, and the third energy supply unit is configured to supply the heated preset liquid to the outside. Through such an arrangement, the exploitation and utilization rate of the geothermal fluid is improved.

[0095] It should be noted that the phrases "one embodiment", "an embodiment", "an exemplary embodiment", "some embodiments", etc. mentioned in the specification indicate that the described embodiments may include certain features, structures or characteristics, but not every embodiment may include the certain features, structures or characteristics. In addition, such phrases do not necessarily refer to the same embodiment. In addition, when describing certain features, structures or characteristics in conjunction with an embodiment, it is within the knowledge of those skilled in the art to implement such features, structures or characteristics in conjunction with other embodiments, whether explicitly or not explicitly described.

[0096] In general, terms should be understood, at least in part, by the context in which they are used. For example, the term "one or more" as used herein may be used to describe any feature, structure, or characteristic in a singular sense, or may be used to describe a combination of features, structures, or characteristics in a plural sense, depending, at least in part, on the context. Similarly, terms such as "a," "an," or "the" may also be understood to convey singular usage or to convey plural usage, depending, at least in part, on the context.

[0097] It should be easily understood that the terms “on,” “above,” and “over” in this application should be interpreted in the broadest manner, so that “on” means not only “directly on something,” but also includes the meaning of “on something” with intervening features or layers therebetween, and “above” or “over” includes not only the meaning of “above something” or “over,” but also may include the meaning of “above something” or “over” with no intervening features or layers therebetween (i.e., directly on something).

[0098] In addition, spatially relative terms, such as "below," "below," "beneath," "above," "above," etc., may be used herein for ease of description to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the figures. The device may have other orientations (rotated 90° or at other orientations), and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A geothermal energy supply system for developing and utilizing geothermal reservoirs using an open U-shaped well, characterized in that: include: A geothermal component, comprising a sieve pipe, a first heat exchanger and a second heat exchanger, wherein the sieve pipe is arranged in a formation, the inner and outer sides of the sieve pipe are filled with gravel, the sieve pipe has sieve holes, the sieve holes communicate with the inner and outer sides of the sieve pipe, the sieve pipe, the first heat exchanger and the second heat exchanger are connected end to end in sequence to form a geothermal loop, and a geothermal fluid circulates in the geothermal loop; The diameter of the sieve hole is smaller than the particle size of the gravel; the stratum includes sand and gravel, and the particle size of the gravel is 5-6 times the median value of the particle size of the sand and gravel; The geothermal loop has two wellheads and a horizontal section, the two wellheads are connected through the horizontal section, one wellhead serves as an outlet for geothermal fluid, and the other wellhead serves as a return port for geothermal fluid, and the two wellheads are arranged in a vertical direction; An energy supply mechanism, comprising a first energy supply unit, a second energy supply unit and a third energy supply unit, wherein the first energy supply unit is connected in series between the first end of the screen pipe and the first heat exchanger, and the first energy supply unit comprises a first generator, and the first generator is configured to generate electric energy driven by the geothermal fluid; The second energy supply unit and the first heat exchanger are arranged correspondingly, a liquid heat-conducting medium flows in the second energy supply unit, the liquid heat-conducting medium is heated by the geothermal fluid through the first heat exchanger and converted into a gaseous state, the second energy supply unit comprises a second generator, and the second generator is configured to generate electric energy under the drive of the gaseous heat-conducting medium; The third energy supply unit and the second heat exchanger are correspondingly arranged, a preset liquid flows in the third energy supply unit, the preset liquid is heated by the geothermal fluid through the second heat exchanger, and the third energy supply unit is configured to supply the heated preset liquid to the outside; The second energy supply unit further includes an electric heater, which is disposed between the condensation pump of the second energy supply unit and the first heat exchanger, and is configured to heat the liquid heat-conducting medium; The geothermal assembly further comprises at least one flow valve, wherein at least one flow valve is disposed between the second heat exchanger and the second end of the screen tube; The geothermal assembly further comprises a sedimentation tank and a filter, wherein the sedimentation tank and the filter are connected in series and are arranged between the second heat exchanger and the second end of the sieve tube; There are two flow valves, one of which is arranged between the second heat exchanger and the sedimentation tank, and the other flow valve is arranged between the filter and the second end of the sieve tube; The geothermal component also includes a pressure relief valve, which is arranged between the second heat exchanger and the second end of the screen tube. The pressure relief valve is configured to open and discharge air in the geothermal loop when the pressure in the geothermal loop is greater than a preset pressure value.

2. The geothermal energy supply system for developing and utilizing geothermal reservoirs using an open U-shaped well according to claim 1, characterized in that: The screen pipe extends along a first direction, and the first direction and a horizontal direction form an included angle.

3. The geothermal energy supply system for developing and utilizing geothermal reservoirs using an open U-shaped well according to claim 1 or 2, characterized in that: The geothermal component comprises a gas-liquid separator, the gas-liquid separator and the first energy supply unit are connected in series to the first end of the sieve tube, and the gas-liquid separator is in communication with the first heat exchanger; The first energy supply unit also includes a first steam turbine, which is arranged between the gas-liquid separator and the first generator, and the first steam turbine is connected to the geothermal circuit. The first steam turbine includes a first impeller, and the geothermal fluid acts on the first impeller and drives the first generator to generate electricity.

4. The geothermal energy supply system for developing and utilizing geothermal reservoirs using an open U-shaped well according to claim 1 or 2, characterized in that: The second energy supply unit comprises a condensate pump, a third heat exchanger and a second steam turbine, the second steam turbine, the third heat exchanger and the condensate pump are connected end to end in sequence, and the first heat exchanger is arranged between the condensate pump and the second steam turbine, and the second steam turbine and the second generator are arranged correspondingly; The second steam turbine includes a second impeller, and the gaseous heat transfer medium acts on the second impeller and drives the second generator to generate electrical energy.

5. The geothermal energy supply system for developing and utilizing geothermal reservoirs using an open U-shaped well according to claim 1, characterized in that: The filter comprises at least a first filter and a second filter, wherein the first filter and the second filter are connected in series and are arranged between the sedimentation tank and the second end of the screen tube; The filtering accuracy of the first filter is 50-80 μm, and the filtering accuracy of the second filter is 2-5 μm.

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