CN208059337U - Heat Exchange System for Harvesting Geothermal Energy - Google Patents

Abstract

The utility model provides a heat transfer system (100) for exploiting geothermal energy, heat transfer system includes vertical well section (1) that extends to in the heat-extraction reservoir from ground, heat transfer system still includes heat exchanger (4) in the pit, and heat exchanger (4) in the pit are arranged in the heat-extraction reservoir. According to the utility model discloses a heat transfer system for exploiting geothermal energy has avoided tail water recharge problem, realizes real "getting heat and does not get water" to it is efficient to get the heat.

Description

Heat Exchange System for Harvesting Geothermal Energy

technical field

The utility model relates to the technical field of geothermal energy development and utilization, in particular to a heat exchange system for exploiting geothermal energy.

Background technique

Heat exchange technology has been applied in geothermal energy development and utilization industries, including geothermal energy heating, cooling, power generation, and the combination of geothermal energy and planting and breeding.

At present, there are two main ways to realize the utilization of geothermal energy by "getting heat without water": economic recharge technology and downhole heat exchange technology. However, there are many problems in them. For example, there are outlet wells and return wells dug to circulate groundwater, so at least two geothermal vertical wells are required, which are expensive and occupy a large area; in addition, the liquid between the well pipe and the thermal reservoir is at rest as the heat conducting material of the two. state, the thermal resistance is large, and the heat transfer efficiency is low.

Utility model content

The purpose of the utility model is to at least partly overcome the defects of the prior art, and provide a heat exchange system for exploiting geothermal energy with high heat extraction efficiency.

The purpose of the utility model is also to provide a heat exchange system for exploiting geothermal energy, so as to avoid the problem of tail water recharge.

The purpose of the utility model is also to provide a heat exchange system for exploiting geothermal energy, which has a small footprint, high space utilization and low drilling cost.

For achieving above-mentioned purpose or one of purpose, the technical solution of the present utility model is as follows:

A heat exchange system for exploiting geothermal energy, the heat exchange system includes a vertical well section extending from the ground into a heat extraction reservoir, the heat exchange system also includes a downhole heat exchanger, and the downhole heat exchanger Heaters are arranged in the heat extraction reservoir.

According to a preferred embodiment of the present utility model, the heat exchange system further includes a first additional well section and a second additional well section, one end of the first additional well section is at the first position of the vertical well section and the vertical The vertical well section is connected, the first additional well section is not parallel to the vertical well section, one end of the second additional well section communicates with the other end of the first additional well section, and the other end of the second additional well section communicating with the vertical well section at a second location in the vertical well section, either directly or indirectly through an additional well section, and

Wherein there is a height difference between the first position and the second position, and the downhole heat exchanger is located between the first position and the second position in height.

According to a preferred embodiment of the present invention, the downhole heat exchanger is arranged in the vertical well section between the first position and the second position.

According to a preferred embodiment of the present utility model, the downhole heat exchanger is arranged in the first additional well section or the second additional well section.

According to a preferred embodiment of the present invention, the second position is higher than the first position.

According to a preferred embodiment of the present utility model, the other end of the second additional well section directly communicates with the vertical well section, so that the vertical well section, the first additional well section and the second additional well section form a loop .

According to a preferred embodiment of the present utility model, the first additional well section is configured as a horizontal well section, and the second additional well section is configured as an inclined well section inclined relative to both the horizontal direction and the vertical direction.

According to a preferred embodiment of the present utility model, the first additional well section extends from the vertical well section, and/or the second additional well section extends from the vertical well section, and

The first additional well section and the second additional well section are interconnected by connecting means.

According to a preferred embodiment of the present utility model, the heat exchange system further includes a water inlet pipe, an outlet pipe and an uphole heat exchanger, one end of the water inlet pipe communicates with the downhole heat exchanger, and the other end of the water inlet pipe communicates with the uphole heat exchanger. The heat exchanger is connected, one end of the outlet pipe is connected with the downhole heat exchanger, and the other end of the outlet pipe is connected with the uphole heat exchanger; the water inlet pipe, the outlet pipe, the downhole heat exchanger and the uphole heat exchanger form a closed cycle circuit to transfer the heat from the downhole heat exchanger to the user side heat supply circuit through the uphole heat exchanger.

According to the heat exchange system for exploiting geothermal energy of the present invention, by adopting the downhole heat exchanger, it is possible to realize the utilization of geothermal energy by "getting heat without taking water", and there is no need for tail water recharge, thus avoiding the problem of tail water recharge Further, except the vertical well section, the heat exchange system also includes a first additional well section (such as a horizontal well section) and a second additional well section (such as an inclined well section), so that the vertical well section, the horizontal well section and the The inclined well section forms a circuit, and the downhole heat exchanger is set in the circuit. Due to the temperature difference between the heat exchanger and the place away from the heat exchanger in the circuit, the temperature of the vertical well section drops at the heat exchanger, and the water The density increases, and the temperature of the vertical well section away from the heat exchanger is relatively high, and the density of water is relatively small, so a natural circulation flow of the water medium in the circuit can be formed. With the help of the natural circulation flow of the medium, it can The geothermal energy in the heat extraction reservoir can be exploited more efficiently, so the heat exchange system for exploiting geothermal energy of the utility model has high heat extraction efficiency.

In addition, the heat exchange system for exploiting geothermal energy of the present invention only needs one vertical geothermal well, which occupies a small area, has a high space utilization rate, and lowers the drilling cost.

Description of drawings

1 is a schematic diagram of a heat exchange system for exploiting geothermal energy according to an embodiment of the present invention; and

Fig. 2 is a schematic diagram of an exemplary downhole heat exchanger according to an embodiment of the present invention.

Detailed ways

Exemplary embodiments of the present utility model will be described in detail below with reference to the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements. In addition, in the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a comprehensive understanding of the embodiments of the present disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown in diagrammatic form to simplify the drawings.

The utility model aims to propose a new downhole heat exchange technology with high heat output power, good economic efficiency and good environmental protection effect, completely solve the problem of difficult tail water recharge, and improve the economic feasibility of geothermal energy utilization.

According to the general concept of the present utility model, a heat exchange system for exploiting geothermal energy is provided, the heat exchange system includes a vertical well section extending from the ground to the heat extraction reservoir, and the heat exchange system also includes A downhole heat exchanger, and the downhole heat exchanger is arranged in the heat extraction reservoir. Further, the heat exchange system also includes a first additional well section and a second additional well section, one end of the first additional well section communicates with the vertical well section at the first position of the vertical well section, and the first The additional well section is not parallel to the vertical well section, one end of the second additional well section communicates with the other end of the first additional well section, and the other end of the second additional well section directly or through an additional well The section indirectly communicates with the vertical well section at a second location of the vertical well section, and wherein there is a height difference between the first location and the second location, and the downhole heat exchanger is located at the first position and the second position.

According to the heat exchange system for exploiting geothermal energy of the present invention, by adopting the downhole heat exchanger, it is possible to realize the utilization of geothermal energy by "getting heat without taking water", and there is no need for tail water recharge, thus avoiding the problem of tail water recharge Further, except the vertical well section, the heat exchange system also includes a first additional well section (such as a horizontal well section) and a second additional well section (such as an inclined well section), so that the vertical well section, the horizontal well section and the The inclined well section forms a circuit, and the downhole heat exchanger is set in the circuit. Due to the temperature difference between the heat exchanger and the place away from the heat exchanger in the circuit, the temperature of the vertical well section drops at the heat exchanger, and the water The density increases, and the temperature of the vertical well section away from the heat exchanger is relatively high, and the density of water is relatively small, so a natural circulation flow of the water medium in the circuit can be formed. With the help of the natural circulation flow of the medium, it can The geothermal energy in the heat extraction reservoir can be exploited more efficiently, so the heat exchange system for exploiting geothermal energy of the utility model has high heat extraction efficiency.

In addition, the heat exchange system for exploiting geothermal energy of the present invention only needs one vertical geothermal well, which occupies a small area, has a high space utilization rate, and lowers the drilling cost.

Fig. 1 is a schematic diagram of a heat exchange system for exploiting geothermal energy according to an embodiment of the present invention. The general concept of the present invention will be described in detail below taking Fig. 1 as an example. As shown in Figure 1, a heat exchange system 100 for exploiting geothermal energy includes a vertical well section 1 extending from the ground into a heat extraction reservoir, wherein the heat extraction reservoir is a rock formation that stores geothermal energy, and the rock formation contains water Medium, geothermal energy can be utilized by extracting heat from the aqueous medium in the rock formation. The vertical well section 1 is, for example, configured as a metal casing extending into the ground, and has perforations on the peripheral wall of the metal casing so that the aqueous medium in the rock formation can enter the interior of the metal casing. The non-heat extraction section of the vertical well section should be cemented, such as pouring cement around the outer periphery of the vertical well section to fix it with the formation; The gap between the heat extraction reservoir and the heat extraction reservoir is filled with stones to prevent the gravel in the rock formation from entering the metal casing through perforations, and only allow the water-based medium to enter the metal casing, thus playing the role of filtration. Preferably, an insulating layer 9 is arranged on the part of the vertical well section 1 between the heat-taking reservoir and the ground, and the insulating layer 9 can be configured as an insulating casing, such as a cement casing, and the insulating layer 9 plays a role in insulating Function, to avoid heat dissipation in the non-heat extraction section, so as to improve the heat exchange efficiency of the heat exchange system. Appropriate sealing is made at the surface or near liquid level in the vertical well section 1 to isolate from the outside world.

The heat exchange system is designed to include a downhole heat exchanger 4, and the downhole heat exchanger 4 is arranged in the heat extraction reservoir. As shown in FIG. 1, the downhole heat exchanger 4 is located in the vertical well section 1 Located in the part of the heat extraction reservoir. The heat exchange system also includes a water inlet pipe 5, an outlet pipe 6 and an uphole heat exchanger 7, one end of the water inlet pipe 5 communicates with the downhole heat exchanger 4, and the other end of the water inlet pipe 5 communicates with the uphole heat exchanger 7. One end of the outlet pipe 6 communicates with the downhole heat exchanger 4, and the other end of the outlet pipe 6 communicates with the uphole heat exchanger 7; the water inlet pipe 5, the outlet pipe 6, the downhole heat exchanger 4 and the uphole heat exchanger The heat exchanger 7 constitutes a closed circulation loop to transfer the heat from the downhole heat exchanger 4 to the heat supply circuit on the user side through the uphole heat exchanger 7 . The heat exchange system also includes a pump 8, such as a centrifugal pump, for pumping fluid to the downhole heat exchanger 4. The pump 8 is preferably arranged on the water inlet pipe 5, alternatively, it can also be arranged on the water outlet pipe 6 superior.

The following first introduces the working process of the heat exchange system. In the course of work, the pump 8 is turned on, and the medium (such as water) in the closed circulation loop formed by the water inlet pipe 5, the water outlet pipe 6, the downhole heat exchanger 4 and the uphole heat exchanger 7 can flow in the closed circulation loop, that is, Flow through the water inlet pipe 5 to the downhole heat exchanger 4; the water-based medium contained in the heat-absorbing reservoir contains geothermal energy and has a relatively high temperature, and the water-based medium enters the vertical well section 1 through the perforations on the gravel and the metal casing In the process, heat exchange occurs with the medium flowing in the downhole heat exchanger 4, that is, the heat is transferred to the medium flowing in the downhole heat exchanger 4, so the temperature of the medium rises; the medium in the closed circulation loop with temperature rise flows through the outlet pipe 6 The heat exchanger 7 on the well, the heat exchanger 7 on the well is also connected to the heat supply circuit on the user side, so the medium in the closed circulation loop transfers heat to the heat supply circuit on the user side, and at the same time the temperature of the medium in the closed circulation loop drops; The medium whose temperature has dropped is supplied to the downhole heat exchanger 4 again through the pump 8 and the water inlet pipe 5; the heat exchange system works in such a reciprocating cycle to continuously exploit geothermal energy.

The downhole heat exchange technology proposed by the utility model mainly includes heat extraction reservoir, 1 geothermal well, 1 downhole heat exchanger, 1 downhole heat exchanger water inlet pipe and 1 downhole heat exchanger outlet water pipe. The heat extraction storage layer to which the utility model belongs is located in the middle-deep layer, that is, 1 km below the ground. Depending on the specific target application area, and according to the local reservoir temperature, its depth or thickness varies.

Further, the heat exchange system also includes a first additional well section and a second additional well section, one end of the first additional well section communicates with the vertical well section 1 at the first position of the vertical well section 1, The first additional well section is not parallel to the vertical well section 1, one end of the second additional well section communicates with the other end of the first additional well section, and the other end of the second additional well section directly or through The additional well section indirectly communicates with the vertical well section 1 at a second location of the vertical well section 1, and wherein there is a height difference between the first location and the second location, and the downhole heat exchanger 4 The height is between the first position and the second position.

Preferably, the downhole heat exchanger 4 is arranged in the vertical well section 1 between the first position and the second position. However, the present invention is not limited thereto, and the downhole heat exchanger 4 may be arranged in the first additional well section or the second additional well section.

Taking the embodiment shown in Figure 1 as an example, the heat exchange system 100 also includes a horizontal well section 2 and an inclined well section 3, one end of the horizontal well section 2 is connected to the vertical well section at the bottom end of the vertical well section 1. The well section 1 is connected, the horizontal well section 2 is perpendicular to the vertical well section 1, one end of the inclined well section 3 communicates with the other end of the horizontal well section 2, and the other end of the inclined well section 3 is directly on the vertical well section. The middle part of the vertical well section 1 communicates with the vertical well section 1 , and the downhole heat exchanger 4 is between the bottom end and the middle part of the vertical well section 1 .

It can be seen that the geothermal wells of the present utility model include a common mid-deep geothermal exploitation vertical shaft (vertical well section), and a group of horizontal wells (horizontal well section) and inclined wells (inclined well section) expanded and excavated. The vertical shaft is connected with the horizontal well and the inclined shaft to form a closed loop, providing a place for natural circulation. The outside of the downhole heat exchanger is the hot water from the geothermal well. During the operation of the heat exchanger, due to the temperature difference between the heat exchanger and the place far away from the heat exchanger in the closed circuit, the vertical well section at the heat exchanger As the temperature drops, the density of water increases, while the temperature of the vertical well section away from the heat exchanger is relatively high, and the density of water is relatively small, which drives the thermal fluid in the inclined well to move upward and establishes a natural circulation (as shown in Figure 1 indicated by the thick arrow). Under the effect of natural circulation flow, the heat transfer coefficient between the hot water in the vertical well section and the downhole heat exchanger, and between the hot water in the vertical well section and the heat extraction reservoir is much greater than that of the hot water in the vertical well section at rest. The thermal conductivity under the state, thus effectively improving the heat extraction efficiency. In addition, the natural circulation path constructed by horizontal wells, inclined wells and shafts also increases the heat exchange area between the heat exchange system and the heat extraction reservoir, and can further expand the heat exchange area by increasing the number of loops to achieve long-lasting heat stability supply.

As shown in Figure 1, the second position is higher than the first position. In fact, the first position is higher than the second position, which can also form a natural circulation loop. Therefore, the utility model does not exclude the technical solution that the first position is higher than the second position, as long as the downhole heat exchanger 4 is set at the first position and the second position.

In the present invention, the other end of the second additional well section may directly communicate with the vertical well section 1, so that the vertical well section 1, the first additional well section and the second additional well section form a loop. Alternatively, the heat exchange system of the present invention may also include a third additional well section, the other end of the second additional well section communicates with the third additional well section, and then the third additional well section is in the vertical well section The second position of 1 communicates with vertical well section 1. By analogy, the fourth additional well section, the fifth additional well section, ... may also be included, as long as the vertical well section 1 and the additional well section can form a circuit.

In the embodiment shown in Figure 1, the first additional well section is configured as a horizontal well section 2, and the second additional well section is configured as an inclined well section that is inclined relative to both the horizontal direction and the vertical direction 3. Alternatively, the first additional well section is configured as an inclined well section that is inclined relative to both the horizontal direction and the vertical direction, and the second additional well section is configured as a horizontal well section. Or alternatively, the first additional well section is configured as an inclined well section inclined relative to both the horizontal direction and the vertical direction, and the second additional well section is configured to be inclined relative to the horizontal direction and the vertical direction inclined well section.

Preferably, the first additional well section, the second additional well section and the part of the vertical well section 1 between the first position and the second position form an isosceles triangle. However, the present invention is not limited thereto, and the first additional well section, the second additional well section and the part of the vertical well section 1 between the first position and the second position may be formed in other shapes.

According to a preferred embodiment of the present invention, the first additional well section extends from the vertical well section 1, and/or the second additional well section extends from the vertical well section 1, and the The first additional well section and said second additional well section are interconnected by connecting means. Alternatively, the first additional well section is connected to the vertical well section 1 through a connecting device, and/or the second additional well section is connected to the vertical well section 1 through a connecting device.

Advantageously, the angle between the second additional well section and the vertical well section 1 is less than 20 degrees, and the angle between the first additional well section and the vertical well section 1 is greater than the angle between the second additional well section and the vertical well section 1 The angle is especially slightly larger than the angle between the second additional well section and the vertical well section 1, optionally greater than 5 degrees, which is conducive to the formation of the first additional well section and the second additional well section. In a preferred technical solution, both the first additional well section and the second additional well section extend directly from the vertical well section 1, which can be realized by using the existing branch well technology, and the second additional well section is connected to the vertical well section. Keeping the angle of the well section 1 small is beneficial to the implementation of branch well technology, and the angle between the first additional well section and the vertical well section 1 is larger than the angle between the second additional well section and the vertical well section 1, which can make the second An additional well section and the second additional well section are naturally intersected. Through calculation, the first additional well section and the second additional well section can be intersected as long as the first additional well section and the second additional well section reach the expected length respectively, and then The first and second additional well sections are interconnected by connecting means such as bolts.

The natural circulation in Fig. 1 includes the arrangement of one vertical well, one horizontal well and one inclined well. In practice, one vertical well, multiple horizontal wells and inclined wells are used in the positive or inverted umbrella shape The arrangement also belongs to the category of the present invention, and has better heat output efficiency. In this case, there are multiple first additional well sections and multiple second additional well sections, and the number of the first additional well sections is the same as that of the second additional well sections, so that each of the first additional well sections An additional interval corresponds to a second additional interval. And advantageously, the multiple first additional well sections are evenly distributed along the circumferential direction of the vertical well section 1 , and the multiple second additional well sections are evenly distributed along the circumferential direction of the vertical well section 1 .

Considering the implementation of branch well technology, multiple first additional well sections are located on one side of the vertical well section 1, and multiple second additional well sections are located on one side of the vertical well section 1, that is, a half "umbrella" is formed. "shape. The angle between each second additional well section and the vertical well section 1 is less than 20 degrees, and the angle between each first additional well section and the vertical well section 1 is greater than that between each second additional well section and the vertical well section The included angle of section 1 is especially slightly larger than the included angle between each second additional well section and vertical well section 1, optionally greater than 5 degrees, and the resulting arrangement is similar to a retracted half "umbrella" shape. It should be noted that the smaller the angle between the second additional well section and the vertical well section 1, the tighter the umbrella is retracted.

The downhole heat exchanger described in the utility model can be in the form of a U-shaped tube or a concentric casing. The downhole heat exchanger 4 shown in Figure 1 is in the form of a U-shaped tube. The downhole heat exchanger 4 forms a U-shape with the corresponding water inlet pipe 5 and water outlet pipe 6. They are in common with the uphole pump 8 and the plate type uphole heat exchanger 7 A geothermal energy utilization loop is formed, which is a closed loop.

Fig. 2 shows a schematic diagram of a concentric casing type downhole heat exchanger according to an embodiment of the present invention. As shown in Figure 2, the downhole heat exchanger includes a central inner tube 41 and an outer tube 42, the central inner tube 41 is arranged at the center of the outer tube 42, and the outer peripheral wall of the upper end of the outer tube 42 is provided with a water inlet 44, and the outer tube 42 The lower end is closed, the lower end of the central inner tube 41 is provided with an inlet, and the upper end of the central inner tube 41 is provided with a water outlet 43 . The water inlet 44 is connected with the water inlet pipe 5 , and the water outlet 43 is connected with the water outlet pipe 6 . The downhole heat exchanger in this embodiment has a simple structure and high heat exchange efficiency.

As mentioned above, there are perforations on the vertical well section 1 to facilitate the water-based medium in the heat-absorbing reservoir to enter the circulation loop. In order to enhance the aforementioned natural circulation, the perforations on the vertical well section 1 are located in the downhole heat exchange At the place of the downhole heat exchanger 4, there are also perforations at a position away from the downhole heat exchanger 4 on the first additional well section or the second additional well section. Through such arrangement, it is beneficial to increase the temperature difference between the downhole heat exchanger 4 and the place away from the downhole heat exchanger 4, thereby increasing the density difference of the circulating medium and enhancing the natural circulation.

Further advantageously, grooves are formed on the inner wall surface of the first additional well section and the inner wall surface of the second additional well section, so as to increase the heat exchange area of the inner and outer media of the first additional well section and the second additional well section, Enhance heat transfer and fully improve heat transfer efficiency.

According to another aspect of the present technology, a heat exchange method is provided, the heat exchange method adopts the heat exchange system 100 for exploiting geothermal energy described in the foregoing embodiments.

In the heat exchange method, several branches can be added to the additional well sections as required, and the lengths and head and tail heights of different additional well sections are designed according to the principle of resistance distribution and can be changed.

The downhole heat exchange technology of the utility model has the following characteristics:

1) The downhole passive natural heat exchange circulation path is constructed in the production well, which improves the heat extraction efficiency without adding additional energy-consuming components.

2) The single well structure is adopted, the space utilization rate is high, and the drilling cost is reduced.

3) The downhole heat exchanger adopts single-side circulation with compact structure, and the uphole heat exchange system is simplified and occupies a small area.

4) Groundwater is not exploited, and the downhole heat exchange system is completely isolated from the uphole heat exchange system to avoid environmental pollution.

5) The downhole heat exchange system does not need to use heat conducting agent to increase heat exchange efficiency.

The utility model combines the passive technology with the downhole heat exchange technology, and develops a new type of high-efficiency passive downhole heat exchange technology for mid-deep geothermal energy. The basic principle of the passive downhole heat exchange technology driven by natural circulation is to build a passive natural heat exchange circulation path in the downhole of the production well, and transfer the thermal energy of the geothermal water to the downhole heat exchanger through natural circulation, and then through the ground heat exchange system passed to the heat user.

The utility model proposes the technology of using downhole heat exchangers to obtain heat and using passive technology to improve downhole heat exchange efficiency. Its advantages are: (1) the passive downhole heat exchange technology only extracts underground heat resources and does not extract groundwater. Therefore, no heat exchange tail water is generated, and the problem of tail water recharge is fundamentally avoided, and absolutely clean geothermal utilization is realized, which has very important social significance and economic value; (2) Adopt passive downhole heat exchange technology, Without relying on the amount of underground water resources, it can extract mid-deep geothermal energy with little water or even no water, which greatly expands the available mid-deep geothermal resources; (3) Passive technology can improve the efficiency of downhole heat exchange, Without adding other equipment, cost and space are saved, thereby improving the economics of geothermal exploitation.

The technical key point of the utility model is to build a natural circulation path in the well, realize the natural circulation of geothermal water in the well, improve the heat exchange efficiency with the well wall and heat exchanger, and increase the heat exchange area with the reservoir . Through the special shaft structure, a closed natural circulation passage is constructed, which is combined with the heat exchanger to achieve the effects of improving thermal efficiency, diffusing heat exchange area, and increasing heat supply capacity.

While embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention. The scope of application of the present invention is defined by the appended claims and their equivalents.

List of reference signs:

100 heat exchange system

1 vertical well section

2 horizontal well section

3 Inclined well section

4 downhole heat exchanger

5 water inlet pipe

6 outlet pipe

7 Well heat exchanger

8 pumps

9 insulation layer

41 center inner tube

42 outer tube

43 outlet

44 water inlet

Claims (8)

1. A heat exchange system (100) for exploiting geothermal energy, said heat exchange system comprising a vertical well section (1) extending from the ground into a heat extraction reservoir, characterized in that said heat exchange system It also includes a downhole heat exchanger (4), and the downhole heat exchanger (4) is arranged in the heat extraction reservoir, Wherein the heat exchange system further includes a first additional well section and a second additional well section, one end of the first additional well section is connected to the vertical well section (1) at the first position of the vertical well section (1) connected, the first additional well section is not parallel to the vertical well section (1), one end of the second additional well section communicates with the other end of the first additional well section, and the other end of the second additional well section communicating with the vertical well section (1) at a second location of the vertical well section (1), either directly or indirectly through an additional well section, and Wherein there is a height difference between the first position and the second position, and the downhole heat exchanger (4) is located between the first position and the second position in height. 2. The heat exchange system (100) for exploiting geothermal energy according to claim 1, characterized in that, the downhole heat exchanger (4) is arranged in a vertical position between the first position and the second position Well section (1). 3. The heat exchange system (100) for exploiting geothermal energy according to claim 1, characterized in that, the downhole heat exchanger (4) is arranged in the first additional well section or the second additional well section . 4. The heat exchange system (100) for exploiting geothermal energy according to any one of claims 1-3, characterized in that, the second position is higher than the first position. 5. The heat exchange system (100) for exploiting geothermal energy according to claim 1, characterized in that, the other end of the second additional well section directly communicates with the vertical well section (1), The vertical well section (1), the first additional well section and the second additional well section form a loop. 6. The heat exchange system (100) for exploiting geothermal energy according to claim 1, characterized in that, the first additional well section is configured as a horizontal well section (2), and the second additional well section The section is configured as an inclined well section (3) inclined relative to both the horizontal direction and the vertical direction. 7. The heat exchange system (100) for exploiting geothermal energy according to claim 1, characterized in that, the first additional well section extends from the vertical well section (1), and/or the a second additional well section extends from the vertical well section (1), and The first additional well section and the second additional well section are interconnected by connecting means. 8. The heat exchange system (100) for exploiting geothermal energy according to claim 1, characterized in that, the heat exchange system further comprises a water inlet pipe (5), a water outlet pipe (6) and an uphole heat exchanger ( 7), one end of the water inlet pipe (5) is in communication with the downhole heat exchanger (4), the other end of the water inlet pipe (5) is in communication with the uphole heat exchanger (7), and the outlet pipe (6) One end is communicated with the downhole heat exchanger (4), and the other end of the outlet pipe (6) is communicated with the uphole heat exchanger (7); the water inlet pipe (5), the outlet pipe (6), the downhole heat exchanger (4) It forms a closed circulation loop with the uphole heat exchanger (7), so as to transfer the heat from the downhole heat exchanger (4) to the heat supply circuit on the user side through the uphole heat exchanger (7).