Open type middle-deep geothermal heat exchange system

Abstract

This invention relates to the field of medium-deep geothermal resource development technology, specifically disclosing an open medium-deep geothermal heat exchange system, including an open medium-deep geothermal well device. The open medium-deep geothermal well device includes a well casing, a central pipe installed inside the well casing, and a flow guiding device installed on the well casing. A heat exchange channel is formed between the well casing and the central pipe. The well casing is located within the heat exchange well and extends through the aquifer into a crater-type geothermal reservoir. A first gap is formed between the outer wall of the well casing within the crater-type geothermal reservoir and the inner wall of the crater-type geothermal reservoir. The flow guiding device includes an upper filter pipe and a lower filter pipe. The upper filter pipe is located in the middle of the well casing, and the lower filter pipe is located at or near the bottom of the well casing. This geothermal heat exchange system meets the water temperature and quality requirements for hot spring bathing, while also minimizing the risk of the central pipe detaching, facilitating troubleshooting and repair of subsequent hot and cold water crosstalk faults within the well, and reducing heat loss.

Description

Technical Field

[0001] This invention relates to the field of medium-deep geothermal resource development technology, and in particular to an open medium-deep geothermal heat exchange system for the development and utilization of shale-type geothermal resources. Background Technology

[0002] Geothermal resources are one of the new clean energy sources encouraged by the state. Currently, the main development methods for medium-deep geothermal resources are the "balanced extraction and irrigation" method and the "heat extraction without water extraction" method of medium-deep downhole heat exchange.

[0003] Existing medium-deep downhole heat exchange systems primarily involve drilling closed medium-deep geothermal wells. These systems utilize a fluid medium flowing through sealed well casings to absorb heat from the geothermal reservoir and bring it to the surface for utilization. The fluid medium exchanges heat with the reservoir via the well casing. However, due to the obstruction of the well casing, the fluid medium cannot directly contact the reservoir rock. This reduces the heat exchange area, leading to lower heat exchange efficiency and lower outlet water temperature. Furthermore, the lack of contact with the rock prevents the dissolution of beneficial minerals, resulting in poor hot spring bathing effects. Additionally, the central tube of the medium-deep geothermal well is suspended from the wellhead device via rings and screws. However, these screws can loosen over time, causing leaks and allowing hot and cold water to flow between the two, or even leading to the central tube detaching.

[0004] Therefore, when developing shale-type geothermal resources, it is necessary to design a medium-deep downhole heat exchange system to improve the above-mentioned problems. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an open-type medium-deep geothermal heat exchange system.

[0006] This invention provides an open medium-deep geothermal heat exchange system, including an open medium-deep geothermal well device. The open medium-deep geothermal well device includes a well wall tube, a central tube installed inside the well wall tube, and a flow guiding device installed on the well wall tube. A heat exchange channel is formed between the well wall tube and the central tube.

[0007] The wellbore tube is located inside the heat exchange well and extends through the water-bearing strata into the crater-type thermal reservoir. A first gap is formed between the outer wall of the wellbore tube located in the crater-type thermal reservoir and the inner wall of the crater-type thermal reservoir.

[0008] The flow guiding device includes an upper water filter pipe and a lower water filter pipe. The upper water filter pipe is located in the middle of the well wall pipe, and the lower water filter pipe is located at the bottom or near the bottom of the well wall pipe. It is used to connect the heat exchange channel and the first gap to realize direct contact heat exchange between the heat exchange medium and the crater-type thermal reservoir.

[0009] The wellhead device is located at the top of the open medium-deep geothermal well device. The wellhead device is equipped with an inlet and an outlet for connecting the well wall pipe and the central pipe to the surface pipeline through the inlet and outlet.

[0010] The ground circulation control device includes a ground circulation pipeline and a control system. The ground circulation pipeline is connected to the inlet of the wellhead device, the outlet of the wellhead device, a low-temperature water source interface, and a hot water supply interface, respectively, to enable the heat exchange medium to form a circulation flow channel in the heat exchange well. The control system adjusts the circulation time of the low-temperature water in the heat exchange well according to the water temperature at the outlet of the wellhead device, thereby controlling the water temperature at the outlet of the wellhead device.

[0011] Furthermore, a first water-stopping element is provided between the water-bearing stratum and the magmatic reservoir, and the first water-stopping element is located above the upper water filter pipe; a second water-stopping element is provided in the heat exchange channel, and the second water-stopping element is located below the upper water filter pipe; a third water-stopping element is provided in the heat exchange channel, and the third water-stopping element is located above the lower water filter pipe.

[0012] Furthermore, a sealing and water-stopping component is provided between the outer wall of the well casing and the inner wall of the heat exchange well, and the sealing and water-stopping component is located in the water-bearing stratum.

[0013] Furthermore, the wellhead device includes a wellhead cover plate, which is installed at the water outlet of the wellhead device. A central pipe connector is nested through the wellhead cover plate. The top end of the central pipe is connected to the central pipe connector, and the bottom end of the central pipe is connected to the first gap.

[0014] Furthermore, the wellhead cover plate includes an upper annular plate and a lower annular plate arranged sequentially. The central pipe joint is nested in the middle of the upper and lower annular plates. The central pipe joint has a cross-shaped structure and an annular protrusion. The central pipe joint is suspended on the lower annular plate through the annular protrusion. A sealing gasket is provided below the annular protrusion. The lower annular plate and the central pipe joint are sealed and connected by the sealing gasket. Both the upper and lower annular plates are provided with screw holes. The upper and lower annular plates are connected to the central pipe joint by screws.

[0015] Furthermore, an exhaust pipe is connected to one side of the wellhead device to regulate the emission of gas.

[0016] Furthermore, the ground circulation control device also includes a temperature sensor and a third gate;

[0017] The third gate is installed on the circulating flow pipe to control whether the low temperature water forms a circulating flow in the well wall pipe; the temperature sensor is installed on the pipe at the outlet of the well wall pipe to collect the temperature at the outlet of the well wall pipe in real time.

[0018] The control system connects the temperature sensor and the third gate, and controls the opening and closing of the third gate according to the temperature of the water outlet of the well wall pipe, thereby adjusting the circulation time of the low-temperature water in the well wall pipe.

[0019] Furthermore, the ground circulation pipeline includes a first pipeline, a second pipeline, and a third pipeline;

[0020] The first pipe is used to connect the well wall pipe inlet and the low-temperature water source;

[0021] The second pipe is used to connect the outlet of the well wall pipe and the hot water supply end;

[0022] The temperature sensor is installed on the second pipe;

[0023] The third pipe is used to connect the first pipe and the second pipe;

[0024] The third gate is installed on the third pipe to allow the low-temperature water after heat exchange to re-enter the well wall pipe from the inlet for heat exchange, forming a circulating flow.

[0025] Furthermore, the ground circulation control device also includes a first gate and a second gate;

[0026] The first gate is installed on the first pipe and is located between the junction of the first and third pipes and the low-temperature water source; the second gate is installed on the second pipe and is located between the junction of the second and third pipes and the hot water supply end; the control system is connected to the first gate and the second gate respectively.

[0027] Furthermore, the temperature sensor is located between the junction of the first and third pipes and the outlet of the wellhead device.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] This invention relates to an open-type medium-deep geothermal heat exchange system. By installing an open-type medium-deep geothermal well device, the heat exchange medium can undergo a water-rock reaction with the reservoir rocks, increasing the water's mineral content and creating hot mineral water that meets the needs of hot spring bathing. Furthermore, the water medium can directly absorb heat from the rock-thermal reservoir, improving the heat exchange efficiency of the well casing and achieving the required water temperature for hot spring bathing. A wellhead device is installed at the top of the deep well casing device, equipped with an inlet and an outlet for connecting the well casing and central pipe to surface pipelines. The design minimizes the risk of the central pipe detaching, facilitating troubleshooting and repair of hot and cold water crosstalk within the well and reducing heat loss. A ground circulation control device is installed, comprising a ground circulation pipeline and a control system. The ground circulation pipeline connects to the inlet of the wellhead device, the outlet of the wellhead device, a low-temperature water source interface, and a hot water supply interface, enabling the heat exchange medium to form a circulating flow channel within the heat exchange well. The control system adjusts the circulation time of the low-temperature water in the heat exchange well based on the water temperature at the outlet of the wellhead device, thereby controlling the water temperature at the outlet of the wellhead device to reach the temperature required for bathing. Attached Figure Description

[0030] The following figures are for illustrative purposes only and are not intended to limit the scope of the invention, wherein:

[0031] Figure 1 : A schematic diagram of the structure of the open-type medium-deep geothermal heat exchange system of the present invention;

[0032] In the diagram: 1-Open medium-deep geothermal well device; 2-Wellhead device; 3-Surface circulation control device; 4-Well wall pipe; 5-Filter pipe; 6-Second water stop; 7-Central pipe; 8-Cement; 9-Low temperature water source interface; 10-Hot water supply interface; 11-Exhaust pipe; 12-Water-bearing formation; 13-Large thermal reservoir; 14-First gap. Detailed Implementation

[0033] To make the objectives, technical solutions, design methods, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0034] like Figure 1 As shown, the present invention provides an open-type medium-deep geothermal heat exchange system, including...

[0035] An open-type medium-deep geothermal well device 1 includes a well wall pipe 4, a central pipe 7 installed inside the well wall pipe 4, and a flow guiding device installed on the well wall pipe 4, wherein a heat exchange channel is formed between the well wall pipe 4 and the central pipe 7.

[0036] The wellbore tube 4 is located inside the heat exchange well and extends through the water-bearing stratum 12 into the crater-type thermal reservoir 13. A first gap 14 is formed between the outer wall of the wellbore tube 4 located in the crater-type thermal reservoir 13 and the inner wall of the crater-type thermal reservoir 13.

[0037] The flow guiding device includes an upper water filter pipe and a lower water filter pipe. The upper water filter pipe is located in the middle of the well wall pipe 4, and the lower water filter pipe is located at the bottom or near the bottom of the well wall pipe 4. It is used to connect the heat exchange channel and the first gap 14 to realize direct contact heat exchange between the heat exchange medium and the rock thermal reservoir 13.

[0038] Wellhead device 2 is located at the top of the open medium-deep geothermal well device 1. The wellhead device 2 is equipped with an inlet and an outlet for connecting the well wall pipe 4 and the central pipe 7 to the ground pipeline through the inlet and outlet.

[0039] The ground circulation control device 3, located on one side of the wellhead device 2, includes a ground circulation pipeline and a control system. The ground circulation pipeline is connected to the inlet, outlet, low-temperature water source interface 9, and hot water supply interface 10 of the wellhead device 2, respectively, to enable the heat exchange medium to form a circulation flow channel. The control system adjusts the circulation time of the low-temperature water in the heat exchange well according to the temperature of the outlet of the wellhead device 2, thereby controlling the water temperature at the outlet of the wellhead device.

[0040] Furthermore, a first water-stopping element is provided between the water-bearing stratum 12 and the craton-type thermal reservoir 13, and the first water-stopping element is located above the upper water filter pipe; a second water-stopping element 6 is provided in the heat exchange channel, and the second water-stopping element 6 is located below the upper water filter pipe; a third water-stopping element is provided in the heat exchange channel, and the third water-stopping element is located above the lower water filter pipe.

[0041] A sealing and water-stopping component is provided between the outer wall of the well wall pipe 4 and the inner wall of the heat exchange well, and the sealing and water-stopping component is located in the water-bearing stratum 12.

[0042] It should be noted that the first water-stopping component, the second water-stopping component 6, and the third water-stopping component are all water-stopping devices; the sealing water-stopping component is cement 8;

[0043] Furthermore, the central pipe 7 is an insulated pipe, which is a polypropylene pipe. A second gap is provided between the bottom of the central pipe 7 and the bottom of the rock thermal reservoir 13, so that the heat exchange medium can pass through the lower filter pipe and flow into the central pipe 7 for insulated transport.

[0044] Furthermore, the wellhead device includes a wellhead cover plate, which is installed at the water outlet of the wellhead device. A central pipe joint is nested through the wellhead cover plate. The top end of the central pipe 7 is connected to the central pipe joint, and the bottom end of the central pipe is connected to the first gap 14 through a lower filter pipe.

[0045] Furthermore, the wellhead cover plate includes an upper annular plate and a lower annular plate arranged sequentially. The central pipe joint is nested in the middle of the upper and lower annular plates. The central pipe joint has a cross-shaped structure and an annular protrusion. The central pipe joint is suspended on the lower annular plate through the annular protrusion. A sealing gasket is provided below the annular protrusion. The lower annular plate and the central pipe joint are sealed and connected by the sealing gasket. Both the upper and lower annular plates are provided with screw holes. The upper and lower annular plates are connected to the central pipe joint by screws.

[0046] It should be noted that the outer diameter of the annular protrusion on the central pipe joint is 40-60mm larger than that of the central pipe, and a sealing gasket is provided on the lower side of the annular protrusion; the central pipe joint is shaped like a cross, with an annular protrusion in the middle, and the lower annular plate is connected to the central pipe joint via a sealing gasket. The central pipe joint is suspended and supported on the lower annular plate, which facilitates the installation of the central pipe 7 and the well wall pipe 4, making it less likely to fall off and reducing the failure rate of the medium-deep heat exchange well system. The central pipe 7 is a polypropylene pipe or a double-layer vacuum insulation pipe, which has a heat preservation effect. After the heat exchange medium absorbs heat, it flows out of the well wall pipe 4 from the inside of the central pipe 7, reducing heat loss;

[0047] Furthermore, an exhaust pipe 11 is connected to one side of the top of the well wall pipe 4 to regulate the gas discharge. The exhaust pipe 11 is used to remove air or other non-condensable gases from the system to prevent them from having an adverse effect on the system, such as reducing thermal efficiency or aggravating corrosion.

[0048] Furthermore, the ground circulation control device 3 also includes a temperature sensor and a third gate;

[0049] The third gate is installed on the circulating flow pipe to control whether the low temperature water forms a circulating flow in the well wall pipe; the temperature sensor is installed on the pipe at the outlet of the well wall pipe to collect the temperature at the outlet of the well wall pipe in real time.

[0050] The control system connects the temperature sensor and the third gate, and controls the opening and closing of the third gate according to the temperature of the water outlet of the well wall pipe, thereby adjusting the time of low-temperature water circulation in the well wall pipe.

[0051] Furthermore, the ground circulation pipeline includes a first pipeline, a second pipeline, and a third pipeline;

[0052] The first pipe is used to connect the well wall pipe inlet and the low-temperature water source;

[0053] The second pipe is used to connect the outlet of the well wall pipe and the hot water supply end;

[0054] The temperature sensor is installed on the second pipe;

[0055] The third pipe is used to connect the first pipe and the second pipe;

[0056] The third gate is installed on the third pipe to allow the low-temperature water after heat exchange to re-enter the well wall pipe from the inlet for heat exchange, forming a circulating flow.

[0057] Furthermore, the ground circulation control device 3 also includes a first gate and a second gate;

[0058] The first gate is installed on the first pipe and is located between the junction of the first and third pipes and the low-temperature water source; the second gate is installed on the second pipe and is located between the junction of the second and third pipes and the hot water supply end; the control system is connected to the first gate, the second gate, and the third gate respectively.

[0059] The control system is connected to the first gate, the second gate, and the third gate, all of which are electrically controlled valves. The opening and closing of each automatic control gate is controlled according to the temperature at the outlet of the heat exchange well. When the temperature at the outlet of the heat exchange well is lower than the set value, the control system controls the second gate to open, allowing the water from the outlet to re-enter the medium-deep heat exchange well for secondary heating. When the temperature at the outlet of the heat exchange well reaches or exceeds the set value, the control system controls the second gate to close, allowing low-temperature water to enter the heat exchange well while simultaneously directing hot water to the hot water supply interface for user use.

[0060] It should be noted that the first pipe, the second pipe, and the third pipe are respectively ductile iron pipe, polyethylene pipe, copper pipe, or stainless steel pipe; and the first pipe and the second pipe are equipped with telescopic pipes to adjust the deformation of the first pipe and the second pipe caused by thermal expansion and contraction.

[0061] Furthermore, the temperature sensor is located between the junction of the first and third pipes and the outlet of the wellhead device;

[0062] It is worth noting that the present invention sets up an open-type medium-deep geothermal well device 1 for the development and utilization of crater geothermal resources; a flow guiding device on the well wall pipe 4 forms a heat exchange channel between the well wall pipe 4 and the central pipe 7; the upper filter pipe of the flow guiding device 5 is located in the middle of the well wall pipe 4, and the lower filter pipe is located at the bottom or near the bottom of the well wall pipe 4, which is used to connect the heat exchange channel and the first gap 14, so as to realize direct contact heat exchange between the heat exchange medium and the crater geothermal reservoir 13; a first water-stopping element is set between the water-bearing stratum 12 and the crater geothermal reservoir 13, the first water-stopping element is located above the upper filter pipe, and a second water-stopping element 3 is located below the upper filter pipe. The third water-stopping component is located above the lower filter pipe. The first, second, and third water-stopping components are all water-stoppers. By reasonably installing the upper and lower filter pipes and water-stoppers, the heat exchange medium can directly contact the lithothermic reservoir. On the one hand, the water medium can undergo a water-rock reaction with the reservoir rocks, increasing the water with some beneficial mineral components, thus becoming hot mineral water that meets the needs of hot spring bathing water. On the other hand, the water medium can directly absorb the heat from the lithothermic reservoir, reducing the thermal resistance of the first gap 14, while increasing the heat exchange area between the water medium and the reservoir, improving the heat exchange efficiency of the heat exchange well, and meeting the water temperature requirements for hot spring bathing water.

[0063] The top of the medium-deep heat exchange well device 1 is equipped with a wellhead device 2, which is used to connect the central pipe 7 and the well wall pipe 4 to the ground circulation pipeline. This facilitates the installation and fixation of the central pipe 7, prevents water leakage during the installation of the central pipe that could cause hot and cold water to flow together, and also reduces the risk of the central pipe falling off. This makes it easier to troubleshoot and repair any subsequent hot and cold water flow faults in the well. Hot water is directly connected to the second pipeline through the central pipe 7 and the central pipe joint, without direct contact with the iron fittings in the wellhead device, thus reducing heat loss.

[0064] A ground circulation control device is installed at the top of the well wall pipe 4 in the medium-deep heat exchange well device 1. The ground circulation control device includes a ground circulation pipe and a control system. The ground circulation pipe is connected to the heat exchange well inlet, heat exchange well outlet, low-temperature water source interface 9, and hot water supply interface 10, respectively, to form a circulating flow of low-temperature water in the heat exchange well. A third gate is installed on the circulating flow pipe to control whether the low-temperature water forms a circulating flow in the heat exchange well. A temperature sensor is installed on the pipe at the outlet of the well wall pipe to collect the temperature at the outlet of the well wall pipe in real time. The control system is connected to the temperature sensor and the third gate installed on the ground circulation pipe, and controls the opening and closing of the gate according to the temperature at the outlet of the well wall pipe to control the water temperature at the outlet of the well wall pipe to reach the temperature required for bathing.

[0065] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. An open-type medium-deep geothermal heat exchange system, characterized in that, The invention includes an open-type medium-deep geothermal well device, which includes a well casing, a central pipe installed inside the well casing, and a flow guiding device installed on the well casing, wherein a heat exchange channel is formed between the well casing and the central pipe. The wellbore tube is located inside the heat exchange well and extends through the water-bearing strata into the crater-type thermal reservoir. A first gap is formed between the outer wall of the wellbore tube located in the crater-type thermal reservoir and the inner wall of the crater-type thermal reservoir. The flow guiding device includes an upper water filter pipe and a lower water filter pipe. The upper water filter pipe is located in the middle of the well wall pipe, and the lower water filter pipe is located at the bottom or near the bottom of the well wall pipe. It is used to connect the heat exchange channel and the first gap to realize direct contact heat exchange between the heat exchange medium and the crater-type thermal reservoir. The wellhead device is located at the top of the open medium-deep geothermal well device. The wellhead device is equipped with an inlet and an outlet for connecting the well wall pipe and the central pipe to the surface pipeline through the inlet and outlet. The ground circulation control device includes a ground circulation pipeline and a control system. The ground circulation pipeline is connected to the inlet of the wellhead device, the outlet of the wellhead device, a low-temperature water source interface, and a hot water supply interface, respectively, to enable the heat exchange medium to form a circulation flow channel in the heat exchange well. The control system adjusts the circulation time of the low-temperature water in the heat exchange well according to the water temperature at the outlet of the wellhead device, thereby controlling the water temperature at the outlet of the wellhead device. The ground circulation control device also includes a temperature sensor and a third gate; The third gate is installed on the circulating flow pipe to control whether the low temperature water forms a circulating flow in the well wall pipe; the temperature sensor is installed on the pipe at the outlet of the well wall pipe to collect the temperature at the outlet of the well wall pipe in real time. The control system connects the temperature sensor and the third gate, and controls the opening and closing of the third gate according to the temperature of the water outlet of the well wall pipe, thereby adjusting the time of low-temperature water circulation in the well wall pipe. The ground circulation pipeline includes a first pipeline, a second pipeline, and a third pipeline; The first pipe is used to connect the well wall pipe inlet and the low-temperature water source; The second pipe is used to connect the outlet of the well wall pipe and the hot water supply end; The temperature sensor is installed on the second pipe; The third pipe is used to connect the first pipe and the second pipe; The third gate is installed on the third pipe to allow the low-temperature water after heat exchange to re-enter the well wall pipe from the inlet for heat exchange, forming a circulating flow.

2. The open-type medium-deep geothermal heat exchange system according to claim 1, characterized in that, A first water-stopping element is provided between the water-bearing stratum and the magnetothermal reservoir, and the first water-stopping element is located above the upper water filter pipe; a second water-stopping element is provided in the heat exchange channel, and the second water-stopping element is located below the upper water filter pipe; a third water-stopping element is provided in the heat exchange channel, and the third water-stopping element is located above the lower water filter pipe.

3. The open-type medium-deep geothermal heat exchange system according to claim 2, characterized in that, A sealing and water-stopping component is provided between the outer wall of the well casing and the inner wall of the heat exchange well, and the sealing and water-stopping component is located in the water-bearing stratum.

4. An open-type medium-deep geothermal heat exchange system according to claim 3, characterized in that, The wellhead device includes a wellhead cover plate, which is installed at the water outlet of the wellhead device. A central pipe connector is nested through the wellhead cover plate. The top end of the central pipe is connected to the central pipe connector, and the bottom end of the central pipe is connected to the first gap.

5. An open-type medium-deep geothermal heat exchange system according to claim 4, characterized in that, The wellhead cover plate includes an upper annular plate and a lower annular plate arranged sequentially. The central pipe joint is nested in the middle of the upper and lower annular plates. The central pipe joint has a cross-shaped structure and an annular protrusion. The central pipe joint is suspended on the lower annular plate through the annular protrusion. A sealing gasket is provided below the annular protrusion. The lower annular plate and the central pipe joint are sealed and connected by the sealing gasket. Both the upper and lower annular plates are provided with screw holes. The upper and lower annular plates are connected to the central pipe joint by screws.

6. An open-type medium-deep geothermal heat exchange system according to claim 5, characterized in that, An exhaust pipe is connected to one side of the wellhead device to regulate the emission of gas.

7. An open-type medium-deep geothermal heat exchange system according to claim 1, characterized in that, The ground circulation control device also includes a first gate and a second gate; The first gate is installed on the first pipe and is located between the junction of the first and third pipes and the low-temperature water source; the second gate is installed on the second pipe and is located between the junction of the second and third pipes and the hot water supply end; the control system is connected to the first gate and the second gate respectively.

8. An open-type medium-deep geothermal heat exchange system according to claim 7, characterized in that, The temperature sensor is located between the junction of the first and third pipes and the outlet of the wellhead device.

Images