Middle-deep geothermal well heat extraction test system

Abstract

The utility model provides a medium-deep layer geothermal well heat extraction test system, which relates to the technical field of medium-deep layer geothermal well heat extraction test and comprises a coaxial sleeve heat exchanger and a cooling tower. The heat pump unit, the evaporation side inlet and the evaporation side outlet are connected through a geothermal well outlet pipeline and a geothermal well inlet pipeline respectively, and the geothermal well outlet pipeline and the geothermal well inlet pipeline are provided with a first testing unit and a second testing unit respectively. The condensation side inlet and the condensation side outlet are connected through a cooling tower water outlet pipeline and a cooling tower water inlet pipeline respectively; a third test unit and a fourth test unit are arranged on the cooling tower water outlet pipeline and the cooling tower water inlet pipeline respectively; two ends of the first bypass pipeline are respectively connected with the geothermal well outlet pipeline and the cooling tower water inlet pipeline, and two ends of the second bypass pipeline are respectively connected with the geothermal well inlet pipeline and the cooling tower water outlet pipeline; the device can be used for testing and researching heat extraction of a medium-deep layer coaxial heat exchanger geothermal well.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of heat extraction test of middle-deep geothermal well, more particularly, relate to a kind of heat extraction test system of middle-deep geothermal well. BACKGROUND

[0002] Geothermal resources are a kind of renewable clean energy, which has significant auxiliary effect on greenhouse gas emission reduction and is conducive to atmospheric haze control. China is rich in geothermal resources, and middle-deep geothermal energy is widely distributed in China, with great development potential. According to statistics, 336 cities above prefecture level have high-quality heat storage conditions, but the utilization rate of geothermal energy in China is not high.

[0003] Currently, there are two main technologies for the development and utilization of middle-deep geothermal energy: one is the same layer recharging technology without water consumption, and the other is the closed-circuit heat extraction technology in the well without exploiting geothermal fluid. The former is the main way of developing middle-deep geothermal energy in China, and the latter is an exploratory development method that has been studied in recent years. For low-yield geothermal wells and idle oil-water wells in some porous thermal storage areas where recharging is not ideal, well heat exchange technology can be considered to develop geothermal resources.

[0004] Middle-deep geothermal heating uses water as a medium to obtain underground heat through a geothermal well heat exchanger. In terms of application, depending on the temperature and flow rate of the heat-exchanged water, it can be used for direct heating or through a heat pump to increase the temperature and achieve regional heating. Currently, the application of middle-deep geothermal energy is becoming more widespread, but there is relatively little research on targeted heat extraction and heating test technology, and there is a lack of test methods for different heating methods. SUMMARY

[0005] The utility model aims at the deficiencies in the prior art, and provides a middle-deep geothermal well heat extraction test system to solve the problem of lack of heat extraction test research on middle-deep coaxial heat exchanger geothermal wells in the prior art.

[0006] To achieve the above-mentioned purpose, the utility model provides a middle-deep geothermal well heat extraction test system, comprising:

[0007] Coaxial casing heat exchanger and cooling tower;

[0008] Heat pump unit, the evaporation side inlet and evaporation side outlet of the heat pump unit are connected through geothermal well outlet pipeline and geothermal well inlet pipeline respectively, first test unit and second test unit are arranged on the geothermal well outlet pipeline and the geothermal well inlet pipeline respectively, the condensation side inlet and condensation side outlet of the heat pump unit are connected through cooling tower outlet pipeline and cooling tower inlet pipeline respectively, third test unit and fourth test unit are arranged on the cooling tower outlet pipeline and the cooling tower inlet pipeline respectively;

[0009] a first bypass pipeline and a second bypass pipeline, two ends of the first bypass pipeline are connected with the geothermal well outlet pipeline and the cooling tower inlet pipeline respectively, and two ends of the second bypass pipeline are connected with the geothermal well inlet pipeline and the cooling tower outlet pipeline respectively.

[0010] Optionally, the coaxial double-pipe heat exchanger comprises a central pipe and an annular pipe, the geothermal well outlet pipeline is connected with the central pipe, and the geothermal well inlet pipeline is connected with the annular pipe.

[0011] Optionally, a first external pipe is arranged on the geothermal well outlet pipeline upstream of the first bypass pipeline connection position, and a first valve is arranged on the first external pipe; and a second external pipe is arranged on the cooling tower outlet pipeline downstream of the fourth test unit, and a second valve is arranged on the second external pipe.

[0012] Optionally, the first test unit comprises a first flow sensor, a first pressure sensor and a first temperature sensor arranged in sequence along the water flow direction in the geothermal well outlet pipeline, the first temperature sensor is arranged upstream of the first external pipe; and the second test unit comprises a second temperature sensor, a second pressure sensor and a second flow sensor arranged in sequence along the water flow direction in the geothermal well inlet pipeline.

[0013] Optionally, the third test unit comprises a third flow sensor, a third pressure sensor and a third temperature sensor arranged in sequence along the water flow direction in the cooling tower inlet pipeline; and the fourth test unit comprises a fourth temperature sensor and a fourth pressure sensor arranged in sequence along the water flow direction in the cooling tower outlet pipeline, the fourth pressure sensor is arranged upstream of the second external pipe.

[0014] Optionally, a third valve is arranged on the geothermal well outlet pipeline downstream of the first bypass pipeline connection position, a fourth valve is arranged on the geothermal well inlet pipeline upstream of the second bypass pipeline connection position, a fifth valve is arranged on the cooling tower outlet pipeline upstream of the first bypass pipeline connection position, and a sixth valve is arranged on the cooling tower inlet pipeline downstream of the second bypass pipeline connection position.

[0015] Optionally, a seventh valve and an eighth valve are arranged on the first bypass pipeline and the second bypass pipeline respectively.

[0016] Optionally, a third bypass pipeline is further included, two ends of the third bypass pipeline are connected with the geothermal well outlet pipeline and the geothermal well inlet pipeline respectively, the position where the third bypass pipeline is connected with the geothermal well outlet pipeline is upstream of the first test unit, the position where the third bypass pipeline is connected with the geothermal well inlet pipeline is upstream of the second test unit, and a ninth valve is arranged on the third bypass pipeline.

[0017] Optionally, a first water pump is arranged on the cooling tower outlet pipeline between the connection position of the second bypass pipeline and the fourth test unit, and a second water pump is arranged on the geothermal well inlet pipeline between the connection position of the third bypass pipeline and the connection position of the second bypass pipeline.

[0018] Optionally, a data analysis unit is further included, which is connected with the first test unit, the second test unit, the third test unit and the fourth test unit.

[0019] The middle-deep geothermal well heat extraction test system has the coaxial casing heat exchanger and the cooling tower, the heat pump unit is connected between the two, and the first bypass pipeline and the second bypass pipeline are arranged, the on-off of the related pipelines connected with the heat pump unit and the first bypass pipeline and the second bypass pipeline can test the middle-deep geothermal well heat extraction capacity under two working conditions of direct heating of the geothermal well and heating of the geothermal well through the heat pump unit, and the arrangement of the first test unit, the second test unit, the third test unit and the fourth test unit can quantitatively study the middle-deep geothermal well heat extraction capacity under the two working conditions, facilitate deep analysis of the test data, and provide a basis for operation, maintenance and decision-making.

[0020] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0021] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which like reference characters refer to like parts throughout the several views.

[0022] Figure 1 A structure schematic view of a middle-deep geothermal well heat extraction test system according to one embodiment of the present application is shown.

[0023] EXPLANATION OF REFERENCE CHARACTERS:

[0024] 1. coaxial double-pipe heat exchanger 2. first flow sensor; 3. first pressure sensor; 4. first temperature sensor; 5. first valve; 6. third valve; 7. heat pump unit; 8. seventh valve; 9. third flow sensor; 10. third pressure sensor; 11. third temperature sensor; 12. fifth valve; 13. cooling tower; 14. sixth valve; 15. first water pump; 16. fourth temperature sensor; 17. fourth pressure sensor; 18. second valve; 19. eighth valve; 20. fourth valve; 21. second water pump; 22. second temperature sensor; 23. second pressure sensor; 24. geothermal well inlet pipeline; 25. geothermal well outlet pipeline; 26. first bypass pipeline; 27. cooling tower water inlet pipeline; 28. cooling tower water outlet pipeline; 29. second bypass pipeline; 30. ninth valve; 31. second flow sensor; 32. third bypass pipe; 101. central pipe; 102. annular pipe. DETAILED DESCRIPTION

[0025] The preferred embodiments of the present application will be described in more detail below. Although the preferred embodiments of the present application are described below, it is understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present application can be more thoroughly and completely conveyed to those skilled in the art.

[0026] As shown in Figure 1 , the present application provides a middle-deep geothermal well heat extraction test system, comprising:

[0027] a coaxial double-pipe heat exchanger 1 and a cooling tower 13;

[0028] a heat pump unit 7, the evaporation side inlet and the evaporation side outlet of the heat pump unit 7 are connected through the geothermal well outlet pipeline 25 and the geothermal well inlet pipeline 24 respectively, the first test unit and the second test unit are respectively arranged on the geothermal well outlet pipeline 25 and the geothermal well inlet pipeline 24, the condensation side inlet and the condensation side outlet of the heat pump unit 7 are connected through the cooling tower water outlet pipeline 28 and the cooling tower water inlet pipeline 27 respectively, the third test unit and the fourth test unit are respectively arranged on the cooling tower water outlet pipeline 28 and the cooling tower water inlet pipeline 27;

[0029] a first bypass pipeline 26 and a second bypass pipeline 29, the two ends of the first bypass pipeline 26 are connected with the geothermal well outlet pipeline 25 and the cooling tower water inlet pipeline 27 respectively, the two ends of the second bypass pipeline 29 are connected with the geothermal well inlet pipeline 24 and the cooling tower water outlet pipeline 28 respectively.

[0030] Specifically, to solve the problem of lack of heat extraction test research for the middle-deep coaxial heat exchanger geothermal well in the prior art, the middle-deep geothermal well heat extraction test system has a coaxial casing heat exchanger 1 and a cooling tower 13, is connected with a heat pump unit 7 between two and is provided with a first bypass pipeline 26 and a second bypass pipeline 29, the heat extraction capacity of the middle-deep geothermal well in two working conditions of direct heating of the geothermal well and heating of the geothermal well through the heat pump unit 7 can be tested by switching on and off the related pipelines connected with the heat pump unit 7 and the first bypass pipeline 26 and the second bypass pipeline 29, and the first test unit, the second test unit, the third test unit and the fourth test unit are arranged, so that the middle-deep geothermal well heat extraction test system can quantitatively study the heat extraction capacity of the middle-deep geothermal well in the two working conditions, facilitating in-depth analysis of the test data and providing a basis for operation, maintenance and decision-making.

[0031] In the embodiment, the middle-deep geothermal well heat extraction test system can realize two test modes, the first test mode is that the circulating water is directly connected with the cooling tower 13 through the bypass pipeline after passing through the coaxial casing heat exchanger 1, the test mode can verify the reliability of the system pipeline, the cooling tower 13, the water pump and the test unit, and the change rule of the geothermal well inlet and outlet temperature and the heat extraction amount in the direct heating mode of the geothermal well can be obtained by analyzing and processing the test data in a set time period; the second test mode is that the circulating water is connected with the cooling tower 13 after being heated by the heat pump unit 7 after passing through the coaxial casing heat exchanger 1, the bypass can be constructed to mix the water outlet of the evaporation side of the heat pump unit 7 with the geothermal well outlet water, reduce the inlet temperature of the evaporation side of the heat pump unit 7, change the water inlet temperature of the heat pump unit 7, ensure the normal operation of the heat pump unit 7 and realize variable temperature regulation, and the heat absorbed by the geothermal well from the soil, the effective power of the water pump and the heat supply amount of the heat pump unit 7 in two working conditions of direct heating and heating through the heat pump unit 7 can be obtained by calculation.

[0032] Optionally, the coaxial casing heat exchanger 1 comprises a center pipe 101 and an annular pipe 102, the geothermal well outlet pipeline 25 is connected with the center pipe 101, and the geothermal well inlet pipeline 24 is connected with the annular pipe 102.

[0033] Specifically, the coaxial casing heat exchanger 1 is a middle-deep geothermal well coaxial casing heat exchanger 1 arranged in the geothermal well, the center pipe 101 is coaxially arranged in the annular pipe 102, and the geothermal well outlet pipeline 25 and the geothermal well inlet pipeline 24 are connected with the center pipe 101 and the annular pipe 102 respectively to realize heat extraction of the geothermal well.

[0034] Optionally, a first external pipe is arranged on the geothermal well outlet pipeline 25 upstream of the first bypass pipeline 26 connection position, and a first valve 5 is arranged on the first external pipe; a second external pipe is arranged on the cooling tower outlet water pipeline 28 downstream of the fourth test unit, and a second valve 18 is arranged on the second external pipe.

[0035] Specifically, the first external pipe and the second external pipe are used to connect tap water, and the on-off state of the two is controlled by the first valve 5 and the second valve 18 respectively.

[0036] Optionally, the first test unit comprises a first flow sensor 2, a first pressure sensor 3 and a first temperature sensor 4 arranged in sequence along the water flow direction in the geothermal well outlet pipeline 25, and the first temperature sensor 4 is arranged upstream of the first external pipe; the second test unit comprises a second temperature sensor 22, a second pressure sensor 23 and a second flow sensor 31 arranged in sequence along the water flow direction in the geothermal well inlet pipeline 24.

[0037] Optionally, the third test unit comprises a third flow sensor 9, a third pressure sensor 10 and a third temperature sensor 11 arranged in sequence along the water flow direction in the cooling tower inlet water pipeline 27; the third test unit comprises a fourth temperature sensor 16 and a fourth pressure sensor 17 arranged in sequence along the water flow direction in the cooling tower outlet water pipeline 28, and the fourth pressure sensor 17 is arranged upstream of the second external pipe.

[0038] Specifically, each flow sensor and temperature sensor is used to monitor the water temperature and flow in each pipeline, and the heat extraction capacity of the geothermal well and the heat supply capacity of the heat pump unit 7 can be calculated according to the inlet and outlet temperature difference and flow; the pressure sensor is used to monitor the pressure of each pipeline, and according to the pressure value, it can be judged whether the pipeline is in normal operation state, and the effective power of the water pump can be calculated.

[0039] In the embodiment, since the flow sensor, pressure sensor and temperature sensor are arranged on the geothermal well outlet pipeline 25 and the cooling tower inlet water pipeline 27 to collect the flow, pressure and temperature information of the circulating water, and then through calculation, the change rule and stable value of the heat extraction and heat supply capacity and the effective power of the pump can be obtained, which provides dynamic data guidance for project operation.

[0040] Optionally, a third valve 6 is arranged on the geothermal well outlet pipeline 25 downstream of the first bypass pipeline 26 connection position; a fourth valve 20 is arranged on the geothermal well inlet pipeline 24 upstream of the second bypass pipeline 29 connection position; a fifth valve 12 is arranged on the cooling tower outlet water pipeline 28 upstream of the first bypass pipeline 26 connection position; and a sixth valve 14 is arranged on the cooling tower inlet water pipeline 27 downstream of the second bypass pipeline 29 connection position.

[0041] Optionally, the first bypass pipeline 26 and the second bypass pipeline 29 are respectively provided with a seventh valve 8 and an eighth valve 19.

[0042] Specifically, the seventh valve 8 and the eighth valve 19 are respectively used for controlling the on-off state of the first bypass pipeline 26 and the second bypass pipeline 29, thereby being capable of changing the heating mode.

[0043] Optionally, the system further comprises a third bypass pipeline 32, two ends of the third bypass pipeline 32 being respectively connected with the geothermal well outlet pipeline 25 and the geothermal well inlet pipeline 24, the third bypass pipeline 32 being connected with the geothermal well outlet pipeline 25 at a position upstream of the first test unit, the third bypass pipeline 32 being connected with the geothermal well inlet pipeline 24 at a position upstream of the second test unit, and the third bypass pipeline 32 being provided with a ninth valve 30.

[0044] Specifically, the opening degree of the ninth valve 30 can be controlled to adjust the mixed water amount of the evaporating side outlet water of the heat pump unit 7 and the outlet water of the geothermal well, to reduce the inlet temperature of the evaporating side of the heat pump unit 7, to change the inlet water temperature of the heat pump unit 7, and to realize variable temperature regulation.

[0045] In the embodiment, each valve except the first valve 5 and the second valve 18 can change the circulating water flow path and flow rate by controlling the opening and closing state thereof.

[0046] Optionally, the cooling tower outlet pipeline 28 is provided with a first water pump 15 between the connection position of the second bypass pipeline 29 and the fourth test unit, and the geothermal well inlet pipeline 24 is provided with a second water pump 21 between the connection position of the third bypass pipeline 32 and the connection position of the second bypass pipeline 29.

[0047] Specifically, the first water pump 15 and the second water pump 21 are circulating pumps.

[0048] In the embodiment, the first water pump 15 and the second water pump 21 are variable frequency water pumps, which are capable of testing the heat exchange capacity under different flow rates and different loads, and providing support for predicting the heating capacity in the later period.

[0049] Optionally, the system further comprises a data analysis unit, the data analysis unit being connected with the first test unit, the second test unit, the third test unit and the fourth test unit.

[0050] Specifically, the data collected by each sensor is uploaded to the data analysis unit, and the data analysis unit can complete the analysis of the test data by relying on each sensor, to research the heat exchange capacity of the geothermal well, the heat pump heating capacity, the effective power of the water pump and the recovery capacity of the water temperature under special working conditions under different working conditions.

[0051] In conclusion, the heat extraction test system for the middle-deep geothermal well can test two test modes, i.e., direct heating after the circulating water is heated by the geothermal well and heating after the circulating water is heated by the geothermal well and then heated by the heat pump unit 7.

[0052] The first test mode:

[0053] Before the test, the first valve 5, the seventh valve 8 and the eighth valve 19 are opened, the third valve 6, the fifth valve 12, the sixth valve 14, the fourth valve 20 and the ninth valve 30 are closed, tap water is connected from the first valve 5, the second water pump 21 is opened, the whole circulating water circuit is filled with tap water, then the first valve 5 is closed, the second water pump 21 is a variable frequency water pump, and the flow is adjusted by adjusting the second water pump 21.

[0054] The parameters of the first flow sensor 2, the first pressure sensor 3, the first temperature sensor 4, the second temperature sensor 22, the second flow sensor 31 and the second pressure sensor 23 are tested under the conditions that the inlet water of the geothermal well is 15 m 3 / h, 20 m 3 / h and 25 m 3 / h, and the heat exchange capacity of the geothermal well and the effective power of the second water pump 21 under various working conditions are obtained by calculation, and the test time lasts until the outlet temperature of the geothermal well reaches stability.

[0055] Then, the whole system is stopped for one day, and after being restarted, the inlet and outlet temperatures of the geothermal well are monitored, the temperature field recovery speed in the deep stratum is judged according to the water temperature recovery, and the water temperature recovery under special working conditions such as well shutdown and power failure is simulated.

[0056] The second test mode:

[0057] Before the test, the first valve 5, the third valve 6, the fifth valve 12, the sixth valve 14, the second valve 18 and the fourth valve 20 are opened, the seventh valve 8, the ninth valve 30 and the eighth valve 19 are closed, tap water is connected from the first valve 5 and the second valve 18, the first water pump 15 and the second water pump 21 are opened, and the two circuits on the side of the geothermal well and the side of the cooling tower 13 are filled with tap water, then the first valve 5 and the second valve 18 are closed.

[0058] The opening degree of the ninth valve 30 can be adjusted to adjust the mixed water amount of the evaporating side outlet water of the heat pump unit 7 and the well outlet water of the geothermal well, the inlet temperature of the evaporating side of the heat pump unit 7 is reduced, the inlet water temperature of the heat pump unit 7 can be changed, and variable temperature adjustment is realized.

[0059] The parameters of the first flow sensor 2, the first pressure sensor 3, the first temperature sensor 4, the second temperature sensor 22, the second flow sensor 31 and the second pressure sensor 23 are tested under the conditions that the inlet water of the geothermal well is 15 m 3 / h, 20 m 3 / h and 25 m 3The parameters of the first flow sensor 2, the first pressure sensor 3, the first temperature sensor 4, the second temperature sensor 22, the second pressure sensor 23, the second flow sensor 31, the third flow sensor 9, the third pressure sensor 10, the third temperature sensor 11, the fourth temperature sensor 16 and the fourth pressure sensor 17 are obtained at the flow rate of 10 ℃, 15 ℃ and 18 ℃, and the heat exchange capacity of the geothermal well, the heat pump heating capacity and the effective power of the water pump under the working condition are obtained by calculation, and the test time lasts until the outlet temperature of the geothermal well reaches a stable state.

[0060] After that, the whole system is stopped for one day, and after being restarted, the inlet and outlet temperatures of the geothermal well are monitored, and the temperature field recovery speed in the deep formation is judged according to the water temperature recovery, and the water temperature recovery under special working conditions such as well shutdown and power failure is simulated.

[0061] In the above two test methods, due to the different circulating modes of water, the test targets and test contents are also different. In the first test method, the circulating water does not pass through the heat pump, but completes the circulation through the geothermal well outlet pipeline 25, the first bypass pipeline 26, the cooling tower inlet pipeline 27, the second bypass pipeline 29 and the geothermal well inlet pipeline 24, and the purpose is to test the stability of the system while simulating the direct heating working condition of the geothermal well. In the second test method, there are two circulating water paths, one is that the circulating water passes through the central pipe 101, the geothermal outlet pipeline, the heat pump unit 7, the geothermal inlet pipeline and the annular pipe 102, and the other is that the circulating water passes through the heat pump unit 7, the cooling tower inlet pipeline 27, the cooling tower 13 and the cooling tower outlet pipeline 28, and the purpose is to simulate the heating working condition of the geothermal well through the heat pump.

[0062] In this embodiment, the heat exchange capacity of the geothermal well and the heat pump heating capacity are calculated:

[0063] P = c p × Q v × ρ × (t1-t2) / 3600

[0064] In the formula, P is the heat extraction or heating capacity, kW;

[0065] c p is the specific heat capacity of water, which is 4.187 kJ·kg -1 ·℃ -1 ;

[0066] Q v is the volume flow rate, m 3 / h;

[0067] ρ is the density of water, which is 998 kg / m 3 ;

[0068] t1 is the inlet temperature of the geothermal well or the outlet temperature of the heat pump, ℃;

[0069] t2 is the geothermal well outlet collection temperature or heat pump inlet collection temperature, ℃;

[0070] Actual outlet temperature calculation of well when heat pump mixes water:

[0071] t 2，real = Q v (t2-t1) / Q v2 +t1

[0072] In the formula: Q v2 is the downhole volumetric flow rate, m 3 / h;

[0073] Effective power calculation of pump:

[0074] P b = Q v (p in -P out ) / 3600

[0075] In the formula: P b is the effective power of the pump, kW;

[0076] P in is the geothermal well inlet collection pressure, kPa;

[0077] P out is the geothermal well outlet collection pressure, kPa.

[0078] The above has described various embodiments of the present application, the above description is exemplary, is not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A system for testing heat extraction from a medium-deep geothermal well, characterized by, The application relates to a heat pump system. The heat pump system comprises a coaxial double-pipe heat exchanger and a cooling tower; a heat pump unit, an evaporating side inlet and an evaporating side outlet of the heat pump unit being connected through a geothermal well outlet pipeline and a geothermal well inlet pipeline respectively, a first test unit and a second test unit being arranged on the geothermal well outlet pipeline and the geothermal well inlet pipeline respectively, a condensing side inlet and a condensing side outlet of the heat pump unit being connected through a cooling tower outlet water pipeline and a cooling tower inlet water pipeline respectively, a third test unit and a fourth test unit being arranged on the cooling tower outlet water pipeline and the cooling tower inlet water pipeline respectively; a first bypass pipeline and a second bypass pipeline, two ends of the first bypass pipeline being connected with the geothermal well outlet pipeline and the cooling tower inlet water pipeline respectively, and two ends of the second bypass pipeline being connected with the geothermal well inlet pipeline and the cooling tower outlet water pipeline respectively. The coaxial double-pipe heat exchanger comprises a central pipe and a ring pipe, the geothermal well outlet pipeline is connected with the central pipe, and the geothermal well inlet pipeline is connected with the ring pipe.

2. The system for testing heat extraction of a medium-depth geothermal well according to claim 1, wherein, A first external connecting pipe is arranged on the geothermal well outlet pipeline upstream of the first bypass pipeline connection position, a first valve is arranged on the first external connecting pipe, a second external connecting pipe is arranged on the cooling tower outlet water pipeline downstream of the fourth test unit, and a second valve is arranged on the second external connecting pipe.

3. The system of claim 1, wherein, The first test unit comprises a first flow sensor, a first pressure sensor and a first temperature sensor arranged in sequence along the water flow direction in the geothermal well outlet pipeline, the first temperature sensor is arranged upstream of the first external connecting pipe, the second test unit comprises a second temperature sensor, a second pressure sensor and a second flow sensor arranged in sequence along the water flow direction in the geothermal well inlet pipeline.

4. The system for testing heat extraction of a medium-depth geothermal well according to claim 3, wherein, The third test unit comprises a third flow sensor, a third pressure sensor and a third temperature sensor arranged in sequence along the water flow direction in the cooling tower inlet water pipeline, the third test unit comprises a fourth temperature sensor and a fourth pressure sensor arranged in sequence along the water flow direction in the cooling tower outlet water pipeline, and the fourth pressure sensor is arranged upstream of the second external connecting pipe.

5. The system for testing heat extraction of a medium-depth geothermal well according to claim 4, wherein, A third valve is arranged on the geothermal well outlet pipeline downstream of the first bypass pipeline connection position, a fourth valve is arranged on the geothermal well inlet pipeline upstream of the second bypass pipeline connection position, a fifth valve is arranged on the cooling tower outlet water pipeline upstream of the first bypass pipeline connection position, and a sixth valve is arranged on the cooling tower inlet water pipeline downstream of the second bypass pipeline connection position.

6. The system for testing heat extraction of a medium-depth geothermal well according to claim 1, wherein, Seventh and eighth valves are arranged on the first bypass pipeline and the second bypass pipeline respectively.

7. The system of claim 1, wherein, The application further relates to a third bypass pipeline, two ends of the third bypass pipeline being connected with the geothermal well outlet pipeline and the geothermal well inlet pipeline respectively, a position, at which the third bypass pipeline is connected with the geothermal well outlet pipeline, being upstream of the first test unit, a position, at which the third bypass pipeline is connected with the geothermal well inlet pipeline, being upstream of the second test unit, and a ninth valve being arranged on the third bypass pipeline.

8. The mesoporous geothermal well heat extraction test system of claim 1, wherein, ​ 9. The system for testing heat extraction of a medium-depth geothermal well according to claim 8, wherein, A first water pump is arranged on the cooling tower outlet pipeline between the connection position of the second bypass pipeline and the fourth test unit, and a second water pump is arranged on the geothermal well inlet pipeline between the connection position of the third bypass pipeline and the connection position of the second bypass pipeline.

10. The mesoporous geothermal well heat extraction test system of claim 1, wherein, A data analysis unit is further included and connected with the first test unit, the second test unit, the third test unit and the fourth test unit.

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