Middle-deep geothermal well heat removal structure and method

Abstract

The invention discloses a middle-deep layer geothermal well heat extraction structure which is arranged in a drill hole of a middle-deep layer geothermal well and comprises a heat transfer bottom plate, a bottom pipe, a bottom pipe connecting pipe, an outer sleeve, a water inlet end and a water outlet pipe, the heat transfer bottom plate is assembled at the bottom end of the bottom pipe and arranged at the bottom end in the drill hole, the bottom pipe connecting pipe is fixedly installed at the upper end of the bottom pipe, and the outer sleeve is fixedly installed at the lower end of the bottom pipe. The multiple outer sleeves are sequentially assembled at the upper end of the bottom pipe connecting pipe, the water inlet end is arranged at the upper end of the outer sleeve on the uppermost side, the water outlet pipe is located in the outer sleeves, the bottom pipe connecting pipe and the bottom pipe, and the spiral water guide pipe is assembled in the bottom pipe. Connection of underground soil and the bottom pipe is achieved through the heat transfer inserting rods and the heat conduction blocks, the heat conduction efficiency is remarkably improved, in addition, the heat transfer bottom plate can be effectively wrapped and supported by well cementation cement through the structural design of the heat transfer bottom plate, and therefore supporting protection of the heat transfer bottom plate is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of geothermal wells, and in particular provides a heat extraction structure and method for a mid-deep geothermal well. Background Art

[0002] As a renewable and clean energy, geothermal energy is gradually gaining widespread attention in the context of global efforts to reduce carbon emissions. Geothermal energy is usually extracted from deep in the earth through pipe wells. There are two main ways to extract heat: one is to directly extract underground hot water and use it; the other is to use heat transfer technology to transfer heat from the formation to the ground using a heat transfer medium. Among them, the "heat extraction without water extraction" method is more in line with the principle of sustainable recycling and has become the focus of research.

[0003] In traditional heat exchange and heat extraction solutions, heat conduction is mainly relied on to achieve the heat exchange process. In the process of transferring heat from underground to the borehole casing, it must pass through cementing cement, but the thermal conductivity of cementing cement is not ideal, and its thermal conductivity coefficient is generally between 0.1 and 3.63W / (m·K). Although the thermal conductivity of cement can be improved by adjusting the raw material ratio of cement and adding different materials, there is still a situation of poor thermal conductivity efficiency, and sometimes it cannot even meet the heating demand.

[0004] Therefore, there is a need for a heat extraction structure and method for mid-deep geothermal wells that can effectively improve heat exchange efficiency. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a heat extraction structure and method for a mid-deep geothermal well.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a heat extraction structure for a medium-deep geothermal well, which is arranged in a borehole of a medium-deep geothermal well, and includes a heat transfer bottom plate, a bottom pipe, a bottom pipe connecting pipe, an outer sleeve, a water inlet end and a water outlet pipe. The heat transfer bottom plate is assembled at the bottom end of the bottom pipe, and the heat transfer bottom plate is arranged at the bottom end in the borehole. The bottom pipe connecting pipe is fixedly installed at the upper end of the bottom pipe. A plurality of outer sleeves are sequentially assembled at the upper end of the bottom pipe connecting pipe. The upper end of the uppermost outer sleeve is provided with a water inlet end. The water outlet pipe is located in the outer sleeve, the bottom pipe connecting pipe and the bottom pipe, and the lower end of the water outlet pipe is assembled at the lower side of the inner cavity of the bottom pipe. A spiral water guide pipe is assembled inside the bottom pipe, and the spiral water guide pipe is sleeved on the outer side of the water outlet pipe.

[0007] Furthermore, the heat transfer bottom plate includes a bottom plate and a cylindrical tube, and the cylindrical tube is fixedly installed on the upper surface of the bottom plate, a heat transfer plug is fixedly installed on the upper surface of the bottom plate, and the upper end of the heat transfer plug is fixedly installed on the lower end of the bottom tube, the lower end of the heat transfer plug passes through the bottom plate, and the lower end of the heat transfer plug is a tapered end, and a circular hole is opened on the upper surface of the bottom plate.

[0008] Furthermore, the straight section of the heat transfer plug is provided with threads, and threaded rings are screwed on both upper and lower sides of the straight section of the heat transfer plug, and the two threaded rings are respectively located on the upper and lower sides of the bottom plate.

[0009] Furthermore, the outer diameter of the cylindrical tube is smaller than the diameter of the drilled hole, and the inner diameter of the cylindrical tube is larger than the outer diameter of the bottom plate. Heat-conducting blocks are evenly fixedly installed on the inner and outer surfaces of the cylindrical tube. The heat-conducting blocks on the inner and outer sides are respectively attached to the outer wall of the bottom tube and the inner wall of the drilled hole. Through holes are evenly opened on the outer surface of the cylindrical tube.

[0010] Furthermore, the heat conducting block is a hemispherical structure.

[0011] Furthermore, corresponding grooves are provided on the inner and outer surfaces of the bottom end of the bottom tube, the upper end of the heat transfer rod is assembled in the groove on the outer side of the bottom end of the bottom tube, and a heat transfer rod is assembled in the groove on the inner side of the bottom end of the bottom tube, and the upper end of the heat transfer rod faces the lower end of the water outlet pipe.

[0012] Furthermore, a fixing ring is fixedly installed on the lower end of the inner wall of the bottom pipe connecting pipe, and a limiting ring is fixedly installed on the inner surface of the fixing ring. The inner diameter of the limiting ring is the same as the outer diameter of the water outlet pipe, and the water outlet pipe passes through the limiting ring. The upper end of the limiting ring is an open structure facing outward, and a spiral water guide pipe connecting pipe is fixedly installed through the lower surface of the fixing ring, and the upper end of the spiral water guide pipe is inserted into the spiral water guide pipe connecting pipe.

[0013] Furthermore, a retaining ring is fixedly installed on the lower side of the inner surface of the bottom tube, and a spiral water pipe outlet pipe connected to the lower end of the spiral water pipe is fixedly installed through the upper surface of the retaining ring. The inner cavity of the bottom tube is located between the fixed ring and the retaining ring and is filled with heat exchange liquid.

[0014] A method for extracting heat from a medium-deep geothermal well, using the above-mentioned medium-deep geothermal well heat extraction structure, specifically comprises the following steps:

[0015] Step 1, performing drilling work to obtain a borehole;

[0016] Step 2, connecting the heat transfer bottom plate and the bottom tube;

[0017] Step 3: Install the outlet pipe in the bottom pipe, and inject heat exchange liquid between the bottom pipe and the outlet pipe above the retaining ring;

[0018] Step 4: Lower the bottom pipe, bottom pipe connecting pipe and outer casing into the borehole in sequence, and extend the outlet pipe at the same time;

[0019] Step 5, filling cementing cement;

[0020] Step six, lower the water outlet pipe to extract heat.

[0021] Furthermore, in step 2, the method of connecting the heat transfer bottom plate and the bottom tube is:

[0022] First, install the upper end of the heat transfer plug into the groove at the lower end of the bottom tube, then screw the threaded ring on the straight section of the heat transfer plug, then put the bottom plate on the heat transfer plug, and screw the threaded ring on the straight section of the heat transfer plug again, so that the two threaded rings on the same heat transfer plug clamp the bottom plate, and complete the installation of the heat transfer bottom plate and the bottom tube.

[0023] The beneficial effects of using the present invention are:

[0024] 1. The present invention configures a heat transfer bottom plate structure at the bottom end of the bottom pipe, and realizes the connection between the underground soil and the bottom pipe through the heat transfer plug rod and the heat conduction block, which significantly improves the heat conduction efficiency. In addition, the structural design of the heat transfer bottom plate enables the cementing cement to effectively wrap and support the heat transfer bottom plate, thereby realizing the support and protection of the heat transfer bottom plate.

[0025] 2. The present invention fills the bottom pipe with heat exchange liquid, which can effectively store geothermal resources. Then, heat is exchanged between the heat exchange liquid and the liquid in the spiral water pipe, thereby further improving the heat exchange efficiency.

[0026] 3. The present invention also designs a spiral water conduit, which prolongs the heat exchange time of the liquid through the spiral structure, ensures the adequacy of heat transfer, and thus effectively improves the heat exchange efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the present invention.

[0028] Figure 2 For the present invention Figure 1 A partial enlarged view of part a.

[0029] Figure 3 For the present invention Figure 1 A partial enlarged view of part b.

[0030] Figure 4 For the present invention Figure 1 Cross-sectional view of the midsole tube connecting tube in the AA direction.

[0031] Figure 5 For the present invention Figure 2 Cross-sectional view of the heat transfer bottom plate in the BB direction.

[0032] Figure 6 It is a three-dimensional schematic diagram of the spiral water conduit of the present invention.

[0033] Reference numerals include:

[0034] 1. Drilling hole, 11. Cementing cement, 2. Heat transfer base plate, 21. Base plate, 22. Heat transfer rod, 23. Cylindrical tube, 24. Heat transfer block, 25. Through hole, 26. Round hole, 3. Bottom pipe, 31. Heat transfer rod, 32. Retaining ring, 4. Bottom pipe connecting pipe, 41. Fixing ring, 42. Limiting ring, 43. Spiral water pipe connecting pipe, 5. Outer sleeve, 6. Spiral water pipe, 7. Water inlet, 8. Water outlet pipe. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0036] Embodiment 1

[0037] Reference Figures 1 to 6 A heat extraction structure for a medium-deep geothermal well is arranged in a borehole 1 of a medium-deep geothermal well, comprising a heat transfer bottom plate 2, a bottom pipe 3, a bottom pipe connecting pipe 4, an outer sleeve 5, a water inlet end 7 and a water outlet pipe 8. The heat transfer bottom plate 2 is assembled at the bottom end of the bottom pipe 3, and the heat transfer bottom plate 2 is arranged at the bottom end in the borehole 1. The bottom pipe connecting pipe 4 is fixedly installed at the upper end of the bottom pipe 3. Multiple outer sleeves 5 are sequentially assembled at the upper ends of the bottom pipe connecting pipes 4. The upper end of the uppermost outer sleeve 5 is provided with a water inlet end 7. The water outlet pipe 8 is located in the outer sleeve 5, the bottom pipe connecting pipe 4 and the bottom pipe 3, and the lower end of the water outlet pipe 8 is assembled at the lower side of the inner cavity of the bottom pipe 3. A spiral water guide pipe 6 is assembled inside the bottom pipe 3, and the spiral water guide pipe 6 is sleeved on the outer side of the water outlet pipe 8.

[0038] The heat transfer bottom plate 2 is used to improve the transfer efficiency between the ground heat and the bottom pipe 3 .

[0039] The bottom pipe 3, the bottom pipe connecting pipe 4 and the outer sleeve 5 are combined to form a pipeline system in the borehole. The water inlet channel is between the pipeline system and the water outlet pipe 8, and the water outlet pipe 8 is the water outlet channel. Water passes through the water inlet channel to reach the bottom pipe 3 for heat exchange, and then flows out from the water outlet pipe 8.

[0040] The design of the spiral water conduit 6 can extend the heat exchange time of the liquid through the spiral structure, ensure the adequacy of heat transfer, and thus effectively improve the heat exchange efficiency.

[0041] In this embodiment, two spiral water conduits 6 are provided to form a double spiral shape. In practical applications, multiple spiral water conduits 6 can be provided simultaneously according to actual conditions to increase the water flow rate per unit time.

[0042] The water outlet pipe 8 is formed by connecting multiple sections of pipes.

[0043] The medium-deep geothermal well mainly passes through the low-temperature rock mass, the hot reservoir rock mass and the hot reservoir rock mass heating zone. The bottom pipe 3 and the heat transfer bottom plate 2 are arranged at the hot reservoir rock mass heating zone, which can better complete the heat exchange work.

[0044] Specifically, if Figure 2 and Figure 5 As shown, the heat transfer bottom plate 2 includes a bottom plate 21 and a cylindrical tube 23, and the cylindrical tube 23 is fixedly installed on the upper surface of the bottom plate 21, a heat transfer plug 22 is fixedly installed on the upper surface of the bottom plate 21, and the upper end of the heat transfer plug 22 is fixedly installed on the lower end of the bottom tube 3, the lower end of the heat transfer plug 22 passes through the bottom plate 21, and the lower end of the heat transfer plug 22 is a tapered end, and a circular hole 26 is opened on the upper surface of the bottom plate 21.

[0045] The heat transfer bottom plate 2 is made of metal, such as copper, stainless steel, etc., and has good thermal conductivity.

[0046] The tapered end of the heat transfer rod 22 can be inserted into the soil, which can better achieve heat transfer and transfer the ground heat to the bottom pipe 3.

[0047] Specifically, the straight section of the heat transfer plug 22 is provided with threads, and threaded rings are screwed on both upper and lower sides of the straight section of the heat transfer plug 22 , and the two threaded rings are respectively located on the upper and lower sides of the bottom plate 21 .

[0048] Specifically, if Figure 2 As shown, the outer diameter of the cylindrical tube 23 is smaller than the diameter of the borehole 1, and the inner diameter of the cylindrical tube 23 is larger than the outer diameter of the bottom plate 3. Heat conductive blocks 24 are evenly fixedly installed on the inner and outer surfaces of the cylindrical tube 23. The heat conductive blocks 24 on both sides are respectively attached to the outer wall of the bottom tube 3 and the inner wall of the borehole 1. Through holes 25 are evenly opened on the outer surface of the cylindrical tube 23.

[0049] The cylindrical tube 23 is sleeved on the outside of the bottom tube 3 . When the bottom tube 3 and the heat transfer bottom plate 2 are lowered into the borehole 1 , the heat transfer bottom plate 2 can be ensured to move vertically downward under the restriction of the cylindrical tube 23 .

[0050] Since the heat conducting block 24 contacts the outer wall of the bottom tube 3 and the inner wall of the borehole 1 respectively, heat transfer can be effectively achieved and the heat exchange efficiency is improved.

[0051] Specifically, if Figure 2 As shown, the heat conducting block 24 is a hemispherical structure.

[0052] The shape of the heat conducting block 24 is designed so that it will not hinder the lowering of the water outlet pipe 8.

[0053] Specifically, if Figure 2As shown, corresponding grooves are provided on the inner and outer surfaces of the bottom end of the bottom tube 3, the upper end of the heat transfer rod 22 is assembled in the groove on the outer side of the bottom end of the bottom tube 3, and a heat transfer rod 31 is assembled in the groove on the inner side of the bottom end of the bottom tube 3, and the upper end of the heat transfer rod 31 faces the lower end of the water outlet pipe.

[0054] The heat transfer rod 22 and the groove may be connected by welding or by screwing.

[0055] The design of the groove position ensures the sealing of the bottom tube 3 while bringing the heat transfer rod 31 and the heat transfer plug 22 closer to each other, thereby achieving better heat transfer.

[0056] The upper end of the heat transfer rod 31 is close to the inlet of the lower end of the water outlet pipe 8, so that when water flows into the water outlet pipe 8, it can fully contact the heat transfer rod 31 to complete the heat transfer.

[0057] Specifically, if Figure 3 and Figure 4 As shown, a fixing ring 41 is fixedly installed on the lower end of the inner wall of the bottom pipe connecting pipe 4, and a limiting ring 42 is fixedly installed on the inner surface of the fixing ring 41. The inner diameter of the limiting ring 42 is the same as the outer diameter of the water outlet pipe 8, and the water outlet pipe 8 passes through the limiting ring 42. The upper end of the limiting ring 42 is an open structure facing outward, and a spiral water guide pipe connecting pipe 43 is fixedly installed through the lower surface of the fixing ring 41, and the upper end of the spiral water guide pipe 6 is inserted into the spiral water guide pipe connecting pipe 43.

[0058] The opening structure at the upper end of the limiting ring 42 allows the water outlet pipe 8 to pass smoothly.

[0059] Specifically, a retaining ring 32 is fixedly installed on the lower side of the inner surface of the bottom tube 3, and a spiral water pipe outlet pipe connected to the lower end of the spiral water pipe 6 is fixedly installed through the upper surface of the retaining ring 32. The inner cavity of the bottom tube 3 is located between the fixing ring 41 and the retaining ring 32 and is filled with heat exchange liquid.

[0060] The lower end of the spiral water conduit 6 is connected to the spiral water conduit outlet pipe, and the upper end is inserted into the spiral water conduit connecting pipe 43 .

[0061] The heat exchange liquid plays a role in assisting the storage of geothermal resources, thereby achieving more effective heat exchange for the liquid in the spiral water pipe 6 .

[0062] The space between the fixing ring 41 and the blocking ring 32 does not need to be filled with the heat exchange liquid.

[0063] When the water flowing in from the water inlet end 7 reaches the fixed ring 41, it will flow into the spiral water pipe 6 through the spiral water pipe connecting pipe 43, and exchange heat with the heat exchange liquid. Then, it will flow to the bottom end of the bottom pipe 3 through the spiral water pipe outlet pipe, and then flow into the water outlet pipe 8 after passing through the heat transfer rod 31. Among them, effective heat exchange can be carried out in the spiral water pipe 6 and the bottom end of the bottom pipe 3 to complete the heat extraction work.

[0064] The inner surfaces of the limiting ring 42 and the retaining ring 32 are both provided with sealing rings to ensure the sealing between the water outlet pipe 8 .

[0065] Embodiment 2

[0066] A method for extracting heat from a medium-deep geothermal well, using a medium-deep geothermal well heat extraction structure as in Example 1, specifically comprises the following steps:

[0067] Step 1, performing drilling work to obtain a borehole 1;

[0068] Step 2, connecting the heat transfer bottom plate 2 and the bottom tube 3;

[0069] First, install the upper end of the heat transfer plug 22 in the groove at the lower end of the bottom tube 3, and then screw the threaded ring on the straight section of the heat transfer plug 22. Then, put the bottom plate 21 on the heat transfer plug 22, and screw the threaded ring on the straight section of the heat transfer plug 22. The two threaded rings on the same heat transfer plug 22 clamp the bottom plate 21, and the installation of the heat transfer bottom plate 2 and the bottom tube 3 is completed.

[0070] Step three: install the water outlet pipe 8 in the bottom pipe 3, and inject heat exchange liquid between the bottom pipe 3 and the water outlet pipe 8 above the retaining ring 32.

[0071] First, pass the water outlet pipe 8 through the retaining ring 32, so that the lower end of the water outlet pipe 8 is close to the heat transfer rod 31, and then inject heat exchange liquid into the space formed by the bottom pipe 3, the water outlet pipe 8 and the retaining ring 32;

[0072] Step 4: lower the bottom pipe 3, the bottom pipe connecting pipe 4 and the outer sleeve 5 into the borehole 1 in sequence, and extend the water outlet pipe 8 at the same time;

[0073] First, put the bottom pipe 3 with the heat transfer bottom plate 2 installed into the borehole 1, then put the bottom pipe connecting pipe 4 in and connect it with the bottom pipe 3, let the fixing ring 41 and the limiting ring 42 block the space where the heat exchange liquid is located, and then connect the outer sleeve 5 in sequence and lower it;

[0074] At the same time, the outlet pipe 8 is extended and lowered.

[0075] Step 5, filling cementing cement 11;

[0076] Inject cement 11 into the gap between the outer casing 5 and the borehole 1 to fix the heat transfer bottom plate 2, the bottom pipe 3, the bottom pipe connecting pipe 4 and the outer casing 5;

[0077] Step 6, installing the water inlet 7 to extract heat;

[0078] Install the water inlet end 7 on the uppermost outer casing 5;

[0079] The process of heat extraction is:

[0080] Water is injected into the outer sleeve 5 through the water inlet end 7. The water flows to the fixing ring 41 and then flows into the spiral water pipe 6, and exchanges heat with the heat exchange liquid. Then, it flows out from the water outlet pipe of the spiral water pipe, contacts the heat transfer rod 31 at the bottom end of the bottom pipe 3, and exchanges heat again. Finally, it flows into the water outlet pipe 8 and flows out for collection, thus completing the heat extraction work of "extracting heat without extracting water".

[0081] The above contents are only preferred embodiments of the present invention. For ordinary technicians in this field, many changes can be made in the specific implementation methods and application scopes based on the ideas of the present invention. As long as these changes do not deviate from the concept of the present invention, they all belong to the protection scope of the present invention.

Claims

1. A medium-deep geothermal well heat extraction structure, arranged in a borehole of a medium-deep geothermal well, characterized in that: It includes a heat transfer bottom plate, a bottom pipe, a bottom pipe connecting pipe, an outer sleeve, a water inlet end and a water outlet pipe. The heat transfer bottom plate is assembled at the bottom end of the bottom pipe, and the heat transfer bottom plate is arranged at the bottom end in the drilled hole. The bottom pipe connecting pipe is fixedly installed at the upper end of the bottom pipe. A plurality of outer sleeves are sequentially assembled at the upper end of the bottom pipe connecting pipe. The upper end of the uppermost outer sleeve is provided with a water inlet end. The water outlet pipe is located in the outer sleeve, the bottom pipe connecting pipe and the bottom pipe, and the lower end of the water outlet pipe is assembled at the lower side of the inner cavity of the bottom pipe. A spiral water guide pipe is assembled inside the bottom pipe, and the spiral water guide pipe is sleeved on the outer side of the water outlet pipe.

2. A heat extraction structure for a medium-deep geothermal well according to claim 1, characterized in that: The heat transfer bottom plate includes a bottom plate and a cylindrical tube, and the cylindrical tube is fixedly installed on the upper surface of the bottom plate. A heat transfer plug is fixedly installed on the upper surface of the bottom plate, and the upper end of the heat transfer plug is fixedly installed on the lower end of the bottom tube. The lower end of the heat transfer plug passes through the bottom plate, and the lower end of the heat transfer plug is a tapered end. A circular hole is opened on the upper surface of the bottom plate.

3. A heat extraction structure for a medium-deep geothermal well according to claim 2, characterized in that: The straight section of the heat transfer plug rod is provided with threads, and threaded rings are screwed on both upper and lower sides of the straight section of the heat transfer plug rod, and the two threaded rings are respectively located on the upper and lower sides of the bottom plate.

4. A heat extraction structure for a medium-deep geothermal well according to claim 2, characterized in that: The outer diameter of the cylindrical tube is smaller than the diameter of the drilled hole, and the inner diameter of the cylindrical tube is larger than the outer diameter of the bottom plate. Heat-conducting blocks are evenly fixedly installed on the inner and outer surfaces of the cylindrical tube. The heat-conducting blocks on the inner and outer sides are respectively attached to the outer wall of the bottom tube and the inner wall of the drilled hole. Through holes are evenly opened on the outer surface of the cylindrical tube.

5. A heat extraction structure for a mid-deep geothermal well according to claim 4, characterized in that: The heat conducting block is a hemispherical structure.

6. A heat extraction structure for a mid-deep geothermal well according to claim 2, characterized in that: The inner and outer surfaces of the bottom end of the bottom tube are provided with corresponding grooves, the upper end of the heat transfer plug is assembled in the groove outside the bottom end of the bottom tube, and the heat transfer rod is assembled in the groove inside the bottom end of the bottom tube, and the upper end of the heat transfer rod faces the lower end of the water outlet pipe.

7. A heat extraction structure for a mid-deep geothermal well according to claim 1, characterized in that: A fixing ring is fixedly installed on the lower end of the inner wall of the bottom pipe connecting pipe, and a limiting ring is fixedly installed on the inner surface of the fixing ring. The inner diameter of the limiting ring is the same as the outer diameter of the water outlet pipe, and the water outlet pipe passes through the limiting ring. The upper end of the limiting ring is an open structure facing outward, and a spiral water guide pipe connecting pipe is fixedly installed through the lower surface of the fixing ring, and the upper end of the spiral water guide pipe is inserted into the spiral water guide pipe connecting pipe.

8. A heat extraction structure for a mid-deep geothermal well according to claim 7, characterized in that: A retaining ring is fixedly installed on the lower side of the inner surface of the bottom tube, and a spiral water pipe outlet pipe connected to the lower end of the spiral water pipe is fixedly installed through the upper surface of the retaining ring. The inner cavity of the bottom tube is located between the fixed ring and the retaining ring and is filled with heat exchange liquid.

9. A method for extracting heat from a medium-deep geothermal well, using a medium-deep geothermal well heat extraction structure as claimed in any one of claims 1 to 8, specifically comprising the following steps: Step 1, performing drilling work to obtain a borehole; Step 2, connecting the heat transfer bottom plate and the bottom tube; Step 3: Install the outlet pipe in the bottom pipe, and inject heat exchange liquid between the bottom pipe and the outlet pipe above the retaining ring; Step 4: Lower the bottom pipe, bottom pipe connecting pipe and outer casing into the borehole in sequence, and extend the outlet pipe at the same time; Step 5, filling cementing cement; Step six, lower the water outlet pipe to extract heat.

10. A method for extracting heat from a medium-deep geothermal well according to claim 9, characterized in that: In step 2, the method of connecting the heat transfer bottom plate and the bottom tube is: First, install the upper end of the heat transfer plug into the groove at the lower end of the bottom tube, then screw the threaded ring on the straight section of the heat transfer plug, then put the bottom plate on the heat transfer plug, and screw the threaded ring on the straight section of the heat transfer plug again, so that the two threaded rings on the same heat transfer plug clamp the bottom plate, and complete the installation of the heat transfer bottom plate and the bottom tube.

Images