A circulating multi-layer geothermal well based on dry hot rock geothermal extraction

Abstract

This invention provides a circulating multi-layered geothermal well for exploiting hot dry rock geothermal energy, comprising: a main well extending downwards from the surface into the hot dry rock stratum; branch wells distributed around the main well and located within the hot dry rock stratum; and horizontal wells distributed below the main well. Each horizontal well has an annular channel within its pipe, with the inlet of the annular channel connected to the lower end of an inlet pipe and the outlet of the annular channel connected to the lower end of a return water pipe. The horizontal wells are located at the bottom of the main well, and the branch wells are located around the main well. Both the branch wells and the main well are located within the hot dry rock stratum, and the pipes of the branch wells and the horizontal wells are not coplanar. By setting up the branch wells and horizontal wells, the flow area of ​​the water can be increased, realizing the circulating flow of water in a three-dimensional space. During the circulation of water within the branch wells and horizontal wells, the geothermal energy of the hot dry rock stratum can be fully absorbed. Therefore, this invention has excellent heat extraction performance and provides a new concept and approach for the exploitation of hot dry rock geothermal energy.

Description

Technical Field

[0001] This invention belongs to the field of geothermal well technology, specifically relating to a circulating multi-layer geothermal well based on dry hot rock geothermal extraction. Background Technology

[0002] Geothermal energy is a widely distributed, abundant, stable, clean, and efficient renewable energy source, mainly divided into two types: hot water geothermal and hot dry rock geothermal. Hot water geothermal is a medium-to-low temperature geothermal resource and is currently the main geothermal resource being developed and utilized. Hot dry rock geothermal is a high-temperature geothermal resource, with temperatures generally between 150-650℃, exhibiting a dry and hot state, and located at depths of 3000-10000m.

[0003] Hot dry rock geothermal energy can be used for power generation and heating. Currently, the extraction method for hot dry rock geothermal energy involves injecting high-pressure water into the hot dry rock strata through injection wells. After absorbing heat from the strata, the high-temperature water and steam are extracted through production wells. After heat exchange and surface circulation, the cooled water is injected back underground, and this cycle continues to develop the heat. This extraction method requires both injection wells and production wells, both of which are vertical shafts, thus failing to fully utilize the heat from the hot dry rock strata.

[0004] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide a circulating multi-layered geothermal well based on hot dry rock geothermal extraction, in order to solve the shortcomings of current hot dry rock geothermal extraction and to make full use of the heat of hot rock formations.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A circulating multi-layered geothermal well based on hot dry rock geothermal extraction includes:

[0008] The main well extends downward from the surface into the dry hot rock strata. The main well includes a main well pipeline, which is divided into an inlet pipeline and a return pipeline by a vertical partition.

[0009] Branch wells are distributed around the main well and located in hot dry rock formations. At least one of the inlet pipe and the return pipe is connected to the branch well. The branch well includes a branch well pipe and has a C-shaped channel communicating with the inlet pipe or the return pipe.

[0010] A horizontal well is located below the main well. The horizontal well includes a horizontal well pipe. The axial direction of the horizontal well pipe is parallel to the width direction of the vertical partition. The horizontal well pipe has an annular channel. The inlet of the annular channel is connected to the lower port of the water inlet pipe, and the outlet of the annular channel is connected to the lower port of the water return pipe.

[0011] Preferably, the horizontal well pipe is provided with a horizontal baffle, and the vertical baffle extends into the horizontal well pipe and is fixedly connected to the horizontal baffle. The horizontal baffle and the vertical baffle are perpendicular to each other. Two fan-shaped flow-blocking plates are provided at both ends of the vertical baffle in the width direction of the horizontal well pipe. The two fan-shaped flow-blocking plates are distributed on both sides of the vertical baffle in the thickness direction. There is a certain distance between the two ends of the horizontal baffle and the two end caps of the horizontal well pipe.

[0012] The annular channel is defined by the vertical partition, the horizontal partition, the two fan-shaped flow-blocking plates, the inner wall of the horizontal well pipe, and the end caps.

[0013] Preferably, the inner and outer sides of the end caps of the horizontal well pipe are respectively equipped with water flow temperature sensors and rock layer temperature sensors.

[0014] Preferably, the central axis of the main well pipe is coplanar with the vertical baffle, the central axis of the horizontal well pipe is coplanar with the horizontal baffle, and the area of ​​the fan-shaped flow baffle is 1 / 4 of the cross-section of the inner pipe of the horizontal well pipe.

[0015] Preferably, the branch well pipes are distributed vertically or inclined relative to the main well pipes.

[0016] Preferably, the branch well pipe is a straight pipe, one end of which is connected to the inlet pipe or the return pipe, and the other end of which is a closed end; the branch well pipe is provided with a branch well baffle to divide the branch well pipe into upper and lower parts, one end of which is fixedly connected to the vertical baffle to divide the inlet pipe or the return pipe into upper and lower sections, and the other end of which has a certain distance from the closed end of the branch well pipe to form the C-shaped channel.

[0017] Preferably, the branch well pipes are distributed perpendicularly to each other, the branch well partition is perpendicular to the vertical partition, and the central axis of the branch well pipes is coplanar with the branch well partition.

[0018] Preferably, a water flow temperature sensor and a rock layer temperature sensor are respectively installed on the inner and outer sides of the closed end of the branch well pipeline.

[0019] Preferably, both the inlet pipe and the return pipe are connected to the branch wells, and the heights of the branch wells are different.

[0020] Preferably, the system further includes a signal receiving center for receiving and processing temperature signals emitted by the water flow temperature sensor and the rock layer temperature sensor.

[0021] Beneficial Effects: This invention includes a main well, branch wells, and horizontal wells. The horizontal wells are located at the bottom of the main well, and the branch wells are located on the outer periphery of the main well. Both the branch wells and the main well are located in hot dry rock formations, and the branch well pipes are not coplanar with the horizontal well pipes. By setting up branch wells and horizontal wells, the flow area of ​​the water can be increased, realizing the circulation of water in three-dimensional space. During the circulation of water in the branch wells and horizontal wells, the geothermal energy of the hot dry rock formations can be fully absorbed. Therefore, this invention has a good heat extraction effect and provides a new concept and approach for the exploitation of hot dry rock geothermal energy. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein:

[0023] Figure 1 This is a schematic diagram of the structure of the circulating multi-layer geothermal well in this invention;

[0024] Figure 2 This is a front view of the circulating multi-layer geothermal well in this invention;

[0025] Figure 3 This is a view of the circulating multi-layer geothermal well in this invention;

[0026] Figure 4 This is a top view of the circulating multi-layer geothermal well in this invention;

[0027] Figure 5 This is a schematic diagram of the overall heat extraction process of the present invention;

[0028] Figure 6 This is a schematic diagram of the horizontal well heat extraction process in this invention;

[0029] Figure 7 This is a diagram showing the usage status of the circulating multi-layer geothermal well in this invention.

[0030] The names corresponding to the various labels in the diagram are as follows: 1-Main well pipe; 2-Vertical baffle; 3-Inlet pipe; 4-Return pipe; 5-Branch well pipe; 6-Branch well baffle; 7-Horizontal well pipe; 8-Horizontal baffle; 9-Water flow temperature sensor; 10-Rock layer temperature sensor; 11-Fan-shaped flow deflector; 12-Insulation material; 13-Shallow formation; 14-Hot dry rock formation; 15-End cap. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0032] In the description of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. The terms "connected" and "linked" used in this invention should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through intermediate components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0033] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0034] like Figure 1-7 As shown, a circulating multi-layered geothermal well based on hot dry rock geothermal extraction includes a main well, branch wells, and horizontal wells. The main well extends vertically from the surface down into the hot dry rock layer. The branch wells and horizontal wells are both located in the hot dry rock layer 14.

[0035] The main shaft includes a main shaft pipe 1, within which a vertical partition 2 is fixed, dividing the main shaft pipe 1 into an inlet pipe 3 and a return pipe 4. The main shaft pipe 1 has an upper port and a lower port at its upper and lower ends, respectively. The upper port of the inlet pipe 3 is the first inlet, and the lower port is the first outlet. The lower port of the return pipe 4 is the second inlet, and the upper port is the second outlet. A pumping device is connected to the upper port of the return pipe 4 to extract water from it.

[0036] At least one branch well is distributed around the periphery of the main well. At least one of the inlet pipe 3 and the return pipe 4 is connected to a branch well. The branch well includes a branch well pipe 5, which has a C-shaped channel communicating with the inlet pipe 3 or the return pipe 4 to increase the flow area of ​​the water and make full use of the geothermal energy in the three-dimensional space. Specifically, when a branch well is connected to the inlet pipe 3, cold water enters the inlet pipe 3 through the first inlet. The cold water flows through the C-shaped channel in the corresponding branch well and then re-enters the inlet pipe 3, thereby increasing the flow area of ​​the cold water and improving the heat extraction effect. When a branch well is connected to the return pipe 4, return water enters the return pipe 4 through the second inlet. The return water flows through the C-shaped channel in the corresponding branch well and then re-enters the return pipe 4, thereby increasing the flow area of ​​the return water and further improving the heat extraction effect.

[0037] The horizontal well includes a horizontal well pipe 7 and branch well pipes 5, which are not coplanar with the horizontal well pipe 7. The horizontal well pipe 7 is located below the main well pipe 1, and its axial direction is parallel to the width direction of the vertical partition 2. The horizontal well pipe 7 has an annular channel. The inlet of the annular channel is connected to the lower port of the inlet water pipe 3, and the outlet of the annular channel is connected to the lower port of the return water pipe 4. That is, cold water flows out through the first outlet of the inlet water pipe 3, flows through the annular channel, and flows into the second inlet of the return water pipe 4. By setting up the annular channel, the flow area of ​​the water can be further increased, thereby further improving the heat extraction effect. The connection position between the main well pipe 1 and the horizontal well pipe 7 can be located in the middle of the upper part of the horizontal well pipe 7, or it can be set at other positions on the upper part of the horizontal well pipe 7.

[0038] In this invention, since both the branch wells and the horizontal wells are arranged in the space of the dry hot rock stratum 14, the water will fully absorb geothermal heat and undergo multiple rounds of "heating" during the circulation of the branch wells and the horizontal wells, thus continuously raising the temperature and achieving a good heat extraction effect.

[0039] In an optional embodiment of the present invention, a horizontal baffle 8 is provided inside the horizontal well pipe 7 to divide the horizontal well pipe 7 into upper and lower parts. A vertical baffle 2 inside the main well pipe 1 extends into the horizontal well pipe 7 and is fixedly connected to the horizontal baffle 8. The horizontal baffle 8 and the vertical baffle 2 are perpendicular to each other. Two fan-shaped flow-blocking plates 11 are provided at both ends of the vertical baffle 2 in the width direction inside the horizontal well pipe 7. The two fan-shaped flow-blocking plates 11 are located on two different cross sections of the horizontal well pipe 7, and are distributed on both sides in the thickness direction of the vertical baffle 2. There is a certain distance between the two ends of the horizontal baffle 8 and the two end caps 15 of the horizontal well pipe 7. The annular channel is defined by the vertical baffle 2, the horizontal baffle 8, the two fan-shaped flow-blocking plates 11, the inner wall of the horizontal well pipe 7, and the two end caps 15. By setting up a fan-shaped baffle, the water in the inlet pipe 3 enters the upper part of the horizontal well pipe 7 through the inlet of the annular channel and can only flow towards one end of the horizontal baffle 8. Then, it flows into the lower part of the horizontal well pipe 7 through the gap between the horizontal baffle 8 and the end cap 15 of the horizontal well pipe 7. The water flows towards the other end of the inlet pipe 3 in the lower part of the horizontal well pipe 7 and enters the upper part of the horizontal well pipe 7. After that, it enters the return pipe 4 through the outlet of the annular channel.

[0040] In a preferred embodiment of the present invention, a water flow temperature sensor 9 and a rock layer temperature sensor 10 are respectively provided on the inner and outer sides of the end caps 15 of the horizontal well pipe 7. The water flow temperature sensor 9 is used to monitor the water temperature inside the horizontal well pipe 7; the rock layer temperature sensor 10 is used to monitor the rock layer temperature outside the horizontal well pipe 7.

[0041] In a preferred embodiment of the present invention, the central axis of the main well pipe 1 is coplanar with the vertical baffle 2, the central axis of the horizontal well pipe 7 is coplanar with the horizontal baffle 8, and the area of ​​the fan-shaped flow baffle 11 is 1 / 4 of the cross-section of the inner pipe of the horizontal well pipe 7. In other optional embodiments of the present invention, there may be a certain distance between the central axis of the main well pipe 1 and the vertical baffle 2, and there may be a certain distance between the central axis of the horizontal well pipe 7 and the horizontal baffle 8.

[0042] In one optional embodiment of the present invention, the branch well pipe 5 is perpendicular to the main well pipe 1. The branch well pipe 5 is a straight pipe, one end of which is connected to the inlet pipe 3 or the return pipe 4, and the other end of which is a closed end. A branch well baffle 6 is provided inside the branch well pipe 5 to divide the branch well pipe 5 into upper and lower parts. One end of the branch well baffle 6 extends into the interior of the inlet pipe 3 or the return pipe 4 and is fixedly connected to the vertical baffle 2, thus dividing the inlet pipe 3 or the return pipe 4 into upper and lower sections. There is a certain distance between the other end of the branch well baffle 6 and the closed end of the branch well pipe 5 to form a C-shaped channel. In a preferred embodiment of the present invention, the branch well baffle 6 is perpendicular to the vertical baffle 2, and the central axis of the branch well pipe 5 is coplanar with the branch well baffle 6. In other optional embodiments of the present invention, the branch well pipe 5 is inclined relative to the main well pipe 1, the branch well baffle 6 is inclined to the vertical baffle 2, and the branch well baffle 6 intersects the vertical baffle 2.

[0043] Preferably, the closed end of the branch well pipe 5 is provided with an end cap 15, and a water flow temperature sensor 9 and a rock layer temperature sensor 10 are respectively provided on the inner and outer sides of the end cap 15 of the branch well pipe 5, for monitoring the water temperature on the inner side of the closed end of the branch well pipe 5 and the rock layer temperature on the outer side.

[0044] In a preferred embodiment of the present invention, the circulating multi-layer geothermal well based on dry hot rock geothermal extraction also includes a signal receiving center for receiving and processing temperature signals emitted by the water flow temperature sensor 9 and the rock layer temperature sensor 10, so that ground personnel can collect and analyze temperature information in each pipe and in the rock layer in a timely manner.

[0045] In a preferred embodiment of the present invention, both the inlet pipe 3 and the return pipe 4 are connected to branch wells, and the heights of each branch well are different. Compared with setting branch wells only on one side of the inlet pipe 3 or the return pipe 4, this embodiment can further increase the water flow area, thereby further improving the heat extraction effect. Specifically, the number of branch wells connected to the inlet pipe 3 and the return pipe 4 is one; or, the number of branch wells connected to the inlet pipe 3 and the return pipe 4 is two or more (e.g., two, three, four, five or six), in which case the branch wells are distributed in a tree-like pattern around the outer periphery of the main pipe 1.

[0046] In a preferred embodiment of the present invention, the gap between the main well pipe 1 section located in the shallow formation 13 and the main well shaft is filled with thermal insulation material 12 to ensure that the heat loss is minimized during the extraction of hot water. The fan-shaped baffle 11, the horizontal baffle 8, the vertical baffle 2 and the branch well baffle 6 are all made of thermal insulation material to avoid heat loss.

[0047] In other optional embodiments of the present invention, the branch well pipe 5 may also be a C-shaped pipe, which is connected to the inlet pipe 3 or the return pipe 4; correspondingly, the inlet pipe 3 or the return pipe 4 is provided with a diaphragm to separate the inlet pipe 3 or the return pipe 4 along the water flow direction; one opening of the C-shaped pipe is located above the diaphragm, and the other opening of the C-shaped pipe is located below the diaphragm.

[0048] The working principle of a preferred embodiment of the present invention is as follows: Cold water enters the inlet pipe 3 from the upper port of the inlet pipe 3, flows downward to the branch well pipe 5, and under the action of the branch well baffle 6 in the branch well pipe 5, the water flows around the branch well baffle 6 and completes a cycle inside the branch well pipe 5; then the cold water flows back into the inlet pipe 3 and flows downward into the horizontal well pipe 7. Under the action of the vertical baffle 2, the horizontal baffle 8 and the two fan-shaped flow baffles 11, the water flows along the horizontal baffle 8 to one end of the horizontal well pipe 7, and continues to flow downward to the other end of the horizontal well pipe 7, and then enters the return water pipe 4 (is pumped into the return water pipe 4), completing the cycle in the horizontal well pipe 7; then the water flows into the branch well pipe 5 connected to the return water pipe 4, and after completing the corresponding cycle flow, the hot water flows back into the return water pipe 4 and flows upward, and finally flows out through the upper port of the return water pipe 4, so as to be used on the ground.

[0049] In summary, this invention, through the design of a water circulation system, utilizes branch wells at different levels and in different directions combined with horizontal wells to achieve multiple water circulations in a three-dimensional space, maximizing the utilization of heat from the dry hot rock strata 14 while also avoiding environmental pollution, providing a new concept and approach for the exploitation of dry hot rock geothermal resources.

[0050] It is understood that the above description is merely exemplary and the embodiments of this application do not limit the scope of the application.

[0051] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention shall be within the scope of protection of the pending claims of the present invention.

Claims

1. A circulating multi-layered geothermal well based on dry hot rock geothermal extraction, characterized in that, include: The main well extends downward from the surface into the dry hot rock strata. The main well includes a main well pipeline, which is divided into an inlet pipeline and a return pipeline by a vertical partition. Branch wells are distributed around the main well and located in hot dry rock formations. At least one of the inlet pipe and the return pipe is connected to the branch well. The branch well includes a branch well pipe and has a C-shaped channel communicating with the inlet pipe or the return pipe. A horizontal well is located below the main well. The horizontal well includes a horizontal well pipe. The axial direction of the horizontal well pipe is parallel to the width direction of the vertical partition. The horizontal well pipe has an annular channel. The inlet of the annular channel is connected to the lower port of the water inlet pipe, and the outlet of the annular channel is connected to the lower port of the water return pipe. The horizontal well pipe is provided with a horizontal baffle, and the vertical baffle extends into the horizontal well pipe and is fixedly connected to the horizontal baffle. The horizontal baffle and the vertical baffle are perpendicular to each other. Two fan-shaped flow-blocking plates are provided at both ends of the vertical baffle in the width direction of the horizontal well pipe. The two fan-shaped flow-blocking plates are distributed on both sides of the vertical baffle in the thickness direction. There is a certain distance between the two ends of the horizontal baffle and the two end caps of the horizontal well pipe. The annular channel is defined by the vertical partition, the horizontal partition, the two fan-shaped flow-blocking plates, the inner wall of the horizontal well pipe, and the end caps.

2. The circulating multi-layered geothermal well based on dry hot rock geothermal extraction according to claim 1, characterized in that, The inner and outer sides of the end caps of the horizontal well pipe are respectively equipped with water flow temperature sensors and rock layer temperature sensors.

3. The circulating multi-layered geothermal well based on dry hot rock geothermal extraction according to claim 1, characterized in that, The central axis of the main well pipe is coplanar with the vertical baffle, the central axis of the horizontal well pipe is coplanar with the horizontal baffle, and the area of ​​the fan-shaped flow baffle is 1 / 4 of the cross-section of the inner pipe of the horizontal well pipe.

4. The circulating multi-layered geothermal well based on dry hot rock geothermal extraction according to claim 1, characterized in that, The branch well pipes are distributed vertically or at an angle relative to the main well pipes.

5. The circulating multi-layered geothermal well based on dry hot rock geothermal extraction according to claim 4, characterized in that, The branch well pipe is a straight pipe. One end of the branch well pipe is connected to the inlet pipe or the return pipe, and the other end of the branch well pipe is a closed end. A branch well baffle is provided inside the branch well pipe to divide the branch well pipe into upper and lower parts. One end of the branch well baffle is fixedly connected to the vertical baffle to divide the inlet pipe or the return pipe into upper and lower sections. There is a certain distance between the other end of the branch well baffle and the closed end of the branch well pipe to form the C-shaped channel.

6. The circulating multi-layered geothermal well based on dry hot rock geothermal extraction according to claim 5, characterized in that, The branch well pipes are distributed perpendicularly to the main well pipes, the branch well partitions are perpendicular to the vertical partitions, and the central axis of the branch well pipes is coplanar with the branch well partitions.

7. The circulating multi-layered geothermal well based on dry hot rock geothermal extraction according to claim 5, characterized in that, The inner and outer sides of the closed end of the branch well pipeline are respectively equipped with a water flow temperature sensor and a rock layer temperature sensor.

8. The circulating multi-layered geothermal well based on dry hot rock geothermal extraction according to claim 1, characterized in that, Both the inlet pipe and the return pipe are connected to the branch wells, and the heights of the branch wells are different.

9. The circulating multi-layered geothermal well based on dry hot rock geothermal extraction according to claim 2 or 7, characterized in that, It also includes a signal receiving center for receiving and processing temperature signals emitted by the water flow temperature sensor and the rock layer temperature sensor.

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