A device for detecting seepage heat transfer data based on rock samples with multi-level fracture network

Abstract

This application relates to the field of rock sample testing technology, and discloses a device for detecting seepage heat transfer data based on multi-level fracture network rock samples. The heat exchanger injection device of the device is connected to both the first pressure regulating device and the heat exchanger cooling circulation device. The heat-fluid-solid coupling pressure chamber is connected to the first pressure regulating device, the second pressure regulating device, the heat exchanger cooling circulation device, the temperature control device, and the temperature detection device. The device proposed in this application can eliminate interference from other temperature factors, allowing only the heat exchanger to flow and transfer heat. Heat loss within the device is solely due to the heat exchanger, thus replicating the real-world scenario during mineral-thermal co-mining. The measured parameters are therefore accurate and reliable.

Description

Technical Field

[0001] This application relates to the field of rock sample testing technology, and in particular, to a device for detecting seepage heat transfer data of rock samples based on multi-level fracture networks. Background Technology

[0002] Geothermal co-mining, as a novel technology, presents more complex research conditions and implementation challenges. Due to the relatively good overall stability of deep ore and rock, efficient mining requires the use of mining techniques such as excavation, blasting, and caving to expand and connect rock fractures under the coupled effects of high temperature, high osmotic pressure, and high geostress, eventually forming a large-scale complex fracture network. This unique mining method inevitably results in a geological strata where large areas of gravel and a small number of interconnected diagenetic fractures coexist. In the central geothermal mining stage, the rock mass itself has a high permeability, leading to a geological strata morphology of (rock matrix porosity + numerous micro-fractures + a small number of main fractures). Therefore, this application aims to propose a seepage-heat transfer data detection device based on multi-level fracture network rock samples to effectively test and detect seepage-heat transfer in such unique multi-level fracture network rock samples. Summary of the Invention

[0003] This application provides a seepage and heat transfer data detection device based on multi-level fracture network rock samples. It can effectively test and detect seepage and heat transfer data of special multi-level fracture network rock samples, restore the real working conditions in the mineral-thermal co-mining process, and then measure various data of the rock sample in the mineral-thermal co-mining process.

[0004] Other features and advantages of this application will become apparent from the following detailed description, or may be learned in part from practice of this application.

[0005] According to one aspect of the embodiments of this application, a seepage heat transfer data detection device based on rock samples with multi-level fracture network is provided. The device includes: a heat exchange medium injection device, a first pressure regulating device, a second pressure regulating device, a heat exchange medium cooling circulation device, a heat-fluid-solid coupling pressure chamber, a temperature control device, and a temperature detection device.

[0006] The heat exchange medium injection device is connected to the first pressure regulating device and the heat exchange medium cooling circulation device respectively, and the heat-fluid-solid coupling pressure chamber is connected to the first pressure regulating device, the second pressure regulating device, the heat exchange medium cooling circulation device, the temperature control device and the temperature detection device respectively.

[0007] The heat exchange medium injection device is used to output the heat exchange medium. The heat exchange medium enters the heat-fluid-solid coupling pressure chamber after passing through the first pressure regulating device. After flowing heat exchange in the heat-fluid-solid coupling pressure chamber, it flows into the heat exchange medium cooling circulation device to cool the heat exchange medium after flowing heat exchange, and then transports the cooled heat exchange medium to the heat exchange medium injection device.

[0008] The second pressure regulating device is used to regulate the pressure of the heat-fluid-solid coupling pressure chamber, which includes an internal rock sample, a clamping device, a first sleeve device, a second sleeve device, and multiple temperature measuring lines. The rock sample has a through hole, and the first sleeve device is fitted into the through hole. The first sleeve device is filled with heat insulation material to prevent the heat exchange medium from flowing into the through hole, so that the heat exchange medium flowing into the rock sample only flows in the matrix pores and cracks of the rock sample.

[0009] The second sleeve device is fitted onto the outer surface of the rock sample. The first sleeve device and the second sleeve device are connected by multiple temperature measuring lines. The multiple temperature measuring lines are located in the rock sample, and each temperature measuring line is connected to the temperature detection device. The clamping device is used to clamp both ends of the rock sample. The clamping device is connected to the annular inner wall of the heat-fluid-solid coupling pressure chamber. The heat exchange medium enters from the annular inner wall of the heat-fluid-solid coupling pressure chamber, flows through the clamping device, and enters the rock sample. The temperature detection device detects the temperature of the heat exchange medium in the rock sample through each of the temperature measuring lines.

[0010] In one embodiment of this application, based on the aforementioned scheme, the heat-fluid-solid coupling pressure chamber further includes an internal mixing device, a fluid inlet, and a fluid outlet, the mixing device being located at both ends of the rock sample; the clamping device includes a front clamp and a rear clamp, the front clamp and the rear clamp being fixed by screws; both the front clamp and the rear clamp are provided with heat-insulated water injection channels, both heat-insulated water injection channels are connected to the mixing device, and graphite gaskets are provided in the gaps formed between the front clamp and the rear clamp and the second sleeve device respectively; the fluid inlet and the fluid outlet are respectively located in the two heat-insulated water injection channels, and both heat-insulated water injection channels are filled with heat-insulating material; the annular inner wall is a hollow chamber located inside the heat-fluid-solid coupling pressure chamber, and both the fluid inlet and the fluid outlet are connected to the annular inner wall;

[0011] The mixing device has multiple flow openings. After the heat exchange medium enters from the fluid inlet, it flows through the heat-insulating water injection channel of the pre-clamping device and is then dispersed and injected into the rock sample through the multiple flow openings of the mixing device.

[0012] In one embodiment of this application, based on the aforementioned scheme, the heat-fluid-solid coupling pressure chamber further includes an oil outlet, an oil injection port, an exhaust port, an annular heating band, and an on / off valve disposed within the annular inner wall, wherein the oil injection port and the exhaust port are connected to the on / off valve; the annular outer wall of the heat-fluid-solid coupling pressure chamber is filled with heat insulation material between it and the annular interior, and the annular heating band is wrapped around the outer surface of the annular inner wall.

[0013] In one embodiment of this application, based on the foregoing scheme, the heat-fluid-solid coupling pressure chamber further includes an internal oil bath chamber, a safety device, an axial pressure chamber, and a confining pressure device. The oil bath chamber is connected to the annular inner wall, and the rock sample is disposed within the oil bath chamber. The annular inner wall includes a front wall of the chamber, a first rear wall of the chamber, and a second rear wall of the chamber. The confining pressure device is connected to the front wall of the chamber. The inner surface of the first rear wall of the chamber is connected to the axial pressure chamber, and the first rear wall of the chamber is connected to the second rear wall of the chamber. The safety device is connected to the outer surface of the first rear wall of the chamber and the outer surface of the second rear wall of the chamber, respectively.

[0014] In one embodiment of this application, based on the foregoing scheme, the first pressure regulating device includes a pressure stabilizing device, a mass flow meter, a preheating device, a first ball valve, a first oil filter, and a first filter connected in sequence; the pressure stabilizing device is connected to the heat exchange medium injection device, and the first filter is connected to the fluid inlet.

[0015] In one embodiment of this application, based on the aforementioned scheme, the heat exchange medium cooling circulation device includes a back pressure valve, a first temperature sensor, a first pressure sensor, a cooler, a first check valve, a second oil filter, a third pressure sensor, a second filter, a differential pressure sensor, and a first low-temperature coolant circulation pump connected in parallel to both ends of the cooler; the back pressure valve is connected to the heat exchange medium injection device, and the differential pressure sensor is connected to the annular inner wall.

[0016] In one embodiment of this application, based on the aforementioned scheme, a first passage and a second passage are provided between the first pressure regulating device and the heat exchange medium cooling circulation device. The first passage consists of a second check valve, a first regulating valve, and a second ball valve connected in sequence. The second check valve is connected to the cooler and the first check valve, respectively, and the second ball valve is connected to the pressure stabilizing device and the mass flow meter, respectively.

[0017] The second passage consists of a second regulating valve and a third ball valve connected in sequence. The second regulating valve is connected to the cooler and the first check valve, respectively, and the third ball valve is connected to the preheating device and the first ball valve, respectively.

[0018] In one embodiment of this application, based on the aforementioned scheme, the heat exchange medium injection device includes a gas storage cylinder, a fourth ball valve, a liquid storage tank, a fifth ball valve, a third filter, a plunger pump, a third pressure sensor, and a safety valve connected in sequence. The safety valve is also connected to the preheating device. The heat exchange medium injection device further includes a second cryogenic coolant circulation pump, which is connected to the liquid storage tank and the plunger pump, respectively. The liquid storage tank is also connected to the back pressure valve.

[0019] In one embodiment of this application, based on the aforementioned scheme, the second pressure regulating device includes a first pressure regulating pipeline and a second pressure regulating pipeline, both of which are connected to the axial pressure chamber; the first pressure regulating pipeline consists of a first electric pressurizing pump, a third regulating valve, and a fourth pressure sensor connected in sequence, and the second pressure regulating pipeline consists of a second electric pressurizing pump, a fourth regulating valve, and a fifth pressure sensor connected in sequence.

[0020] The beneficial effects of this application are as follows: The rock sample is placed within a heat-fluid-solid coupling pressure chamber, and a second sleeve device is fitted over the outer surface of the rock sample. Simultaneously, a clamping device holds the rock sample, ensuring that the heat exchange medium can only enter from both ends of the rock sample. The first sleeve device, filled with insulating material, ensures that the heat exchange medium flowing into the rock sample can only exchange heat within the matrix pores and fissures of the rock sample. Temperature measuring lines are installed in the fissures of the rock sample, connecting the first and second sleeve devices. A temperature detection device connected to the temperature measuring lines detects the actual temperature data of the rock sample under mining conditions, as well as the actual temperature data of the heat exchange medium flowing within the rock sample. This eliminates interference from other temperature factors and accurately reflects the actual mining conditions of the rock sample.

[0021] Furthermore, the external connections of the heat-fluid-solid coupling pressure chamber include a first pressure regulating device, a second pressure regulating device, and a heat exchange medium cooling and circulation device. The heat exchange medium is injected through the heat exchange medium injection device and flows through the first pressure regulating device, which adjusts various parameters such as pressure and temperature of the heat exchange medium to match the setpoints in actual mining conditions. Simultaneously, the second pressure regulating device adjusts the pressure within the heat-fluid-solid coupling pressure chamber to match the setpoints in actual mining conditions. This constitutes a fully simulated real mining operation. The heat exchange medium, after heat exchange, is recycled and cooled before being reintroduced into the heat exchange medium injection device. This eliminates the need for externally cooled heat exchange medium, achieving recycling of the heat exchange medium under simulated real mining conditions and improving resource utilization.

[0022] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings:

[0024] Figure 1 This is an overall block diagram of a seepage heat transfer data detection device based on a multi-level fracture network rock sample, according to an embodiment of this application.

[0025] Figure 2 This is a structural diagram illustrating a seepage heat transfer data detection device based on a multi-level fracture network rock sample, according to an embodiment of this application.

[0026] Figure 3 This is a schematic diagram illustrating the clamping of a rock sample within an axial compression chamber according to an embodiment of this application;

[0027] Figure 4 This is a schematic diagram of the mixing tank and the second sleeve device according to an embodiment of this application;

[0028] Figure 5 This is a diagram illustrating the internal structure of a thermo-fluid-structure interaction pressure chamber according to an embodiment of this application.

[0029] Figure 6This is a side cross-sectional view showing the clamping of a rock sample in an axial compression chamber according to an embodiment of this application.

[0030] Figure Labels

[0031] 1. Gas cylinder; 2. Liquid storage tank; 3. Plunger pump; 4. Second cryogenic coolant circulation pump; 5. Pressure stabilizing device; 6. Mass flow meter; 7. Preheating device; 8. Thermal-fluid-solid coupling pressure chamber; 9. Temperature control device; 10. First electric pressurizing pump; 11. Third ball valve; 12. Third regulating valve; 13. Fourth pressure sensor; 14. Second electric pressurizing pump; 15. Fourth regulating valve; 16. Fifth pressure sensor; 17. Fourth ball valve; 18. Fifth ball valve; 19. Third filter; 20. Safety valve; 21. First ball valve; 22. First oil filter; 23. First filter; 24. Back pressure valve; 25. First temperature sensor; 26. First pressure sensor; 27. Cooler; 28. First cryogenic coolant circulation pump; 29. ​​First check valve; 30. Second oil filter; 31. Third pressure sensor; 32. Second filter; 33. Differential pressure sensor; 34. Temperature detection device. Second check valve 35, first regulating valve 36, second ball valve 37, second regulating valve 38, fluid inlet 8-1, fluid outlet 8-2, thermocouple lead-out tube 8-3, front clamp 8-4, rear clamp 8-5, rear wall of first chamber 8-6, safety device 8-7, axial pressure chamber 8-8, rear wall of second chamber 8-9, confining pressure device 8-10, front wall of chamber 8-11, annular inner wall 8-12, outlet Oil hole 8-13, on / off valve 8-14, oil injection hole 8-15, vent hole 8-16, annular heating belt 8-17, first sleeve device 8-18, through hole 8-19, rock sample 8-20, heat insulation water injection channel 8-21, screw 8-22, second sleeve device 8-23, temperature measuring wire 8-24, oil bath chamber 8-25, heat insulation material 8-26, graphite gasket 8-27, mixing device 8-28. Detailed Implementation

[0032] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art.

[0033] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a thorough understanding of embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0034] The block diagrams shown in the accompanying drawings are merely functional entities and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller node devices.

[0035] The flowcharts shown in the accompanying drawings are merely illustrative and do not necessarily include all content and operations / steps, nor do they necessarily have to be performed in the described order. For example, some operations / steps can be broken down, while others can be combined or partially combined; therefore, the actual execution order may change depending on the specific circumstances.

[0036] It should be noted that "multiple" in this article refers to two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0037] The technical background of the embodiments of this application is described in detail below:

[0038] Mineral-thermal co-mining is a novel concept first proposed in my country, with no international precedent. Although the basic theories and technologies for the development and utilization of high-temperature geothermal resources in strata are relatively mature both domestically and internationally, mineral-thermal co-mining, as a completely new technology, presents more complex research conditions and implementation challenges. Because deep ore and rock generally have good overall stability, efficient mining requires the use of mining techniques such as excavation, blasting, and caving to expand and connect rock fractures under the coupled effects of high temperature, high osmotic pressure, and high ground stress, eventually forming a large-scale complex fracture network. This special mining method inevitably results in a geological stratum with large areas of gravel and a small number of interconnected diagenetic fractures. If the rock mass itself has a high permeability during geothermal mining in the central region, a geological stratum morphology of (rock matrix porosity + numerous micro-fractures + a small number of main fractures) (a multi-level fracture network) will be formed. A key task is to conduct seepage-heat transfer tests on rock samples 8-20 within this special multi-level fracture network. In the embodiments of this application, rock samples 8-20 of a multi-level fracture network can be loaded into a clamping component, relevant parameters can be measured, and then the seepage-thermal migration characteristics of the rock samples 8-20 of the multi-level fracture network can be obtained through calculation and pattern summarization.

[0039] In practical work, it has been found that existing numerical simulations mostly focus on simulating long-term geothermal extraction under complex geological conditions, specifically the non-constant heat source loading of the multi-level fracture network rock sample 8-20, which is difficult to achieve in experiments. The multi-level fracture network rock sample 8-20 refers to a special rock sample 8-20 composed of matrix pores, numerous micro-fractures, and a small number of diagenetic fractures. Non-constant heat source heating refers to the oil in the oil bath chamber 8-25 being heated to a certain temperature and then heating is stopped. The oil temperature changes due to heat exchange between the heat exchange medium and the rock sample 8-20, and heat loss within the system is solely due to the heat exchange medium. However, in existing seepage-heat transfer test devices, the oil in the oil bath chamber 8-25 is directly pressurized by an external pressure pump, which not only poses a risk of high-temperature oil leakage but also causes continuous heat exchange with the outside environment, resulting in fluctuations in the oil bath heat source. Furthermore, existing devices require external equipment to apply axial pressure, making movement and testing extremely inconvenient. Furthermore, because the entire thermo-fluid-solid coupled triaxial pressure chamber continuously exchanges heat with the outside world during the application of the confining pressure and axial pressure, it is difficult to achieve a non-constant heat source loading situation, that is, the heat loss in the system is only completed by the heat exchange medium.

[0040] The implementation details of the technical solutions in the embodiments of this application are described in detail below:

[0041] According to one aspect of this application, a device for detecting seepage heat transfer data based on rock samples with multi-level fracture networks is provided. Figure 1 This is an overall block diagram of a seepage heat transfer data detection device based on a multi-level fracture network rock sample, according to an embodiment of this application. Figure 2 The following is a detailed structural diagram of a seepage heat transfer data detection device based on a multi-level fracture network rock sample, according to an embodiment of this application:

[0042] The seepage heat transfer data detection device based on multi-level fracture network rock samples proposed in this application includes: a heat exchange medium injection device, a first pressure regulating device, a second pressure regulating device, a heat exchange medium cooling circulation device, a heat-fluid-solid coupling pressure chamber 8, a temperature control device 9, and a temperature detection device 34.

[0043] The heat exchange medium injection device is connected to the first pressure regulating device and the heat exchange medium cooling circulation device respectively, and the heat-fluid-solid coupling pressure chamber 8 is connected to the first pressure regulating device, the second pressure regulating device, the heat exchange medium cooling circulation device, the temperature control device 9 and the temperature detection device 34 respectively.

[0044] The heat exchange medium injection device is used to output the heat exchange medium. The heat exchange medium enters the heat-fluid-solid coupling pressure chamber 8 after passing through the first pressure regulating device. After undergoing flow heat exchange in the heat-fluid-solid coupling pressure chamber 8, it flows into the heat exchange medium cooling circulation device to cool the heat exchange medium after flow heat exchange, and then transports the cooled heat exchange medium to the heat exchange medium injection device.

[0045] The second pressure regulating device is used to regulate the pressure of the heat-fluid-solid coupling pressure chamber 8. The heat-fluid-solid coupling pressure chamber 8 includes a rock sample 8-20, a clamping device, a first sleeve device 8-18, a second sleeve device 8-23, and multiple temperature measuring lines 8-24. The rock sample 8-20 has a through hole 8-19. The first sleeve device 8-18 is fitted into the through hole 8-19 and is filled with heat insulation material to prevent the heat exchange medium from flowing into the through hole 8-19, so that the heat exchange medium flowing into the rock sample 8-20 only flows in the matrix pores and cracks of the rock sample 8-20.

[0046] The second sleeve device 8-23 is sleeved on the outer surface of the rock sample 8-20. The first sleeve device 8-18 and the second sleeve device 8-23 are connected by multiple temperature measuring lines 8-24. The multiple temperature measuring lines 8-24 are disposed in the rock sample 8-20, and each temperature measuring line 8-24 is connected to the temperature detection device 34. The clamping device is used to clamp both ends of the rock sample 8-20. The clamping device is connected to the annular inner wall 8-12 of the heat-fluid-solid coupling pressure chamber 8. The heat exchange medium enters from the annular inner wall 8-12 of the heat-fluid-solid coupling pressure chamber 8, flows through the clamping device and enters the rock sample 8-20. The temperature detection device 34 detects the temperature of the heat exchange medium in the rock sample 8-20 through each of the temperature measuring lines 8-24.

[0047] Specifically, rock sample 8-20 is placed in the heat-fluid-solid coupling pressure chamber 8, and a second sleeve device 8-23 is fitted onto the outer surface of rock sample 8-20. Simultaneously, a clamping device clamps rock sample 8-20, allowing the heat exchange medium to enter only from both ends of rock sample 8-20. A first sleeve device 8-18 filled with insulating material ensures that the heat exchange medium flowing into rock sample 8-20 can only exchange heat within rock sample 8-20. Temperature measuring wires 8-24, which are thermocouples, are installed in the cracks of rock sample 8-20. Temperature measuring wires 8-24 connect the first sleeve device 8-18 and the second sleeve device 8-23. A temperature detection device 34 connected to temperature measuring wires 8-24 detects the actual temperature data of rock sample 8-20 under mining conditions, thereby eliminating interference from other temperature factors and accurately reproducing the actual mining conditions of rock sample 8-20.

[0048] Furthermore, the external connections of the heat-fluid-solid coupling pressure chamber 8 include a first pressure regulating device, a second pressure regulating device, and a heat exchange medium cooling and circulation device. The heat exchange medium is injected through the heat exchange medium injection device and flows through the first pressure regulating device, which adjusts the pressure and temperature of the heat exchange medium to match the setpoints in actual mining conditions. Simultaneously, the second pressure regulating device adjusts the pressure within the heat-fluid-solid coupling pressure chamber 8 to match the setpoints in actual mining conditions. This constitutes a fully simulated real mining condition. The heat exchange medium, after heat exchange flow, is recycled and cooled before being reintroduced into the heat exchange medium injection device. This eliminates the need for externally cooled heat exchange medium, achieving recycling of the heat exchange medium under simulated real mining conditions and improving resource utilization.

[0049] This application enables data measurement of the seepage-heat transfer process of multi-level fracture network rock sample 8-20 under the action of a non-constant heat source, simulating the mining conditions in the process of geothermal extraction under complex geological conditions, which corresponds to the real situation of non-constant heat source loading of multi-level fracture network rock sample 8-20, which is difficult to achieve in experiments.

[0050] Furthermore, the heat-fluid-solid coupling pressure chamber 8 also includes an internal mixing device 8-28, a fluid inlet 8-1, and a fluid outlet 8-2. The mixing device 8-28 is located at both ends of the rock sample 8-20. The clamping device includes a front clamp 8-4 and a rear clamp 8-5, which are fixed by screws 8-22. Both the front clamp 8-4 and the rear clamp 8-5 are provided with heat-insulated water injection channels 8-21, and both heat-insulated water injection channels 8-21 are connected to the mixing device 8-28. The two sleeve devices 8-23 are connected, and graphite gaskets 8-27 are provided in the gaps formed between the front clamp 8-4 and the rear clamp 8-5 and the second sleeve device 8-23, respectively; the fluid inlet 8-1 and the fluid outlet 8-2 are respectively located in the two heat-insulated water injection channels 8-21, and the two heat-insulated water injection channels 8-21 are filled with heat-insulating material; the annular inner wall 8-12 is a hollow cavity and is located inside the heat-fluid-solid coupling pressure chamber 8, and the fluid inlet 8-1 and the fluid outlet 8-2 are both connected to the annular inner wall 8-12;

[0051] The mixing device 8-28 has multiple flow openings. After the heat exchange medium enters from the fluid inlet 8-1, it flows through the heat-insulating water injection channel 8-21 of the pre-clamp 8-4 and then through the multiple flow openings of the mixing device 8-28 and is dispersed and injected into the rock sample 8-20.

[0052] like Figure 3 and Figure 4 As shown, the first sleeve device 8-18 can be specifically a steel sleeve, and the second sleeve device 8-23 can be specifically a copper sleeve. First, the specially manufactured multi-level fracture network rock sample 8-20 is inserted into the steel sleeve through the through hole 8-19, and then the copper sleeve 8-23 is inserted from the outer side. Multiple 0.8mm holes are drilled at the same position on both the steel and copper sleeves for the temperature measuring wire 8-24 to pass through, allowing the temperature measuring wire 8-24 to connect the first sleeve device 8-18 and the second sleeve device 8-23. The wire extends from the thermocouple lead-out tube 8-3 located in the through hole 8-19 and is connected to the temperature detection device 34. Thus, the temperature detection device 34 can accurately measure the temperature at different measuring points within the rock sample 8-20 through the temperature measuring wire 8-24. It should be noted that... Figure 3 The rock sample 8-20 shown is only half the size of the actual rock sample in the real scene. Figure 3 Rock sample 8-20 was cut in half to get a clearer view of the interior of the entire apparatus, as well as the location of each component.

[0053] External pressure on the rock causes the copper sleeve to deform, ensuring no gap between the rock and the two sleeves, allowing the high-pressure fluid to flow only through the matrix pores and cracks of rock sample 8-20. Insulating material is filled inside the steel sleeve to prevent the heat exchange medium from passing through, ensuring it can only flow within the cracks. Rock sample 8-20 is then placed into the clamping device, and a graphite gasket 8-27 is fitted onto part of the clamping device. Finally, the copper sleeve is fitted onto the outer surfaces of rock sample 8-20 and the clamping device. The pressure difference between the oil bath and the fluid inside the rock sample causes the copper sleeve to deform, ensuring no gap between rock sample 8-20 and the first sleeve device 8-18, allowing the high-pressure fluid to flow only inside the rock sample. The graphite gasket 8-27 deforms and expands under the combined action of oil pressure and mechanical force, tightly fitting against the copper sleeve, thus preventing leakage between the heat exchange medium and the oil bath. The fluid inlet 8-1 and fluid outlet 8-2 in the heat-insulating water injection channel 8-21 inside the clamping device are used for the flow of the heat exchange medium, so that the heat exchange medium enters the interior of the rock sample 8-20.

[0054] The complex arrangement of the clamping device, copper sleeve, rock sample 8-20, and graphite gasket 8-27 is designed to prevent fluid (heat exchange medium) from flowing within the gap between the rock and the copper sleeve. The pressure difference between the fluid in the oil bath and the rock sample causes the copper sleeve to deform, ensuring a gap-free connection between the rock and the sleeve, with the high-pressure fluid flowing only through the matrix pores and cracks. The graphite gasket 8-27 deforms and expands under the combined action of oil pressure and mechanical force, fitting tightly against the copper sleeve, thus preventing leakage between the fluid and the oil bath. Channels within the front clamp 8-4 and the rear clamp 8-5 are used for fluid flow and thermocouple extraction.

[0055] A mixing device 8-28 is also provided between the clamping device and the rock sample 8-20. The mixing device 8-28 is a device with multiple flow openings. The heat exchange medium enters the mixing device 8-28 from the fluid inlet 8-1 of the insulated water injection channel 8-21. Due to the multiple flow openings, the heat exchange medium is dispersed into the interior of the rock sample 8-20 from each flow opening. This is to reduce the temperature difference between the liquid at the fluid inlet 8-1 of the clamping device and the liquid at the inlet of the rock sample 8-20. When the injected heat exchange medium is injected into the surface of the rock sample 8-20, it only comes into contact with the steel axial pressure part (part of the clamping device, which can be used for axial pressure and heating) at the port of the clamping device, and a temperature change occurs after being heated by the clamping device.

[0056] Mixing devices 8-28 are installed at the contact points between the rock sample 8-20 and the clamping device, specifically at both ends of the fluid inlet 8-1 and fluid outlet 8-2, to disperse the injected liquid. The mixing devices 8-28 are porous components made of high-strength insulating material, allowing free flow of fluid. Multiple pyramid-shaped protrusions are present on the surfaces of both ends of the mixing devices 8-28. The mixing devices 8-28 ensure uniform mixing of the fluid (heat exchange medium) at the inlet and outlet of the rock sample 8-20. Simultaneously, they prevent direct contact between the fluid inlet 8-1 and the surface of the rock sample 8-20, thus avoiding uneven pressure distribution on the surface. This transforms the point loading of the mixing devices 8-28 onto the liquid inlet of the rock sample 8-20 into surface loading, preventing excessively high and uneven local pressures caused by point loading.

[0057] Furthermore, a temperature measuring point, namely a thermocouple lead-out tube 8-3, can be arranged inside the mixing device 8-28. By comparing the temperature of the mixing device 8-28 with the temperature before entering the clamping device, their functional relationship can be obtained, thereby controlling the temperature of the fluid entering the clamping device, further improving the accuracy of the temperature entering the rock sample 8-20, and ensuring that the temperature of the heat exchange medium before entering the rock sample 8-20 reaches the required set value, further improving the accuracy and authenticity of the experiment.

[0058] The following are the steps for preparing the specially made rock sample 8-20:

[0059] In the formal preparation of special rock sample 8-20, ten cylindrical porous matrix rock samples, each 100 mm in diameter and 200 mm in height, were taken from a complete rock. Their porosity was obtained using nuclear magnetic resonance (NMR) technology, and their permeability was obtained using a pulse attenuation permeameter. A circular hole with a diameter of 21 ± 0.5 mm (i.e., the through hole 8-19 described in this application embodiment) was drilled at the center of the sample (rock sample 8-20). The diameter of the circular hole was slightly larger than the 20 mm diameter of the detection steel sleeve used for the sensor cable. The rock samples were placed in a high-temperature furnace and heated to several different high temperatures. They were then quickly placed in water at 20°C, resulting in ten different rock samples 8-20 containing numerous microcracks and porous matrix. At this point, the permeability of the rock was determined by the permeability of the microcracks (…). k f 1- k f 10 ) and the permeability of the matrix pores ( k m 1- k m 10The rock was constructed using CT scanning technology to acquire images of its interior, which were then binarized to distinguish between the pore and fracture components of the rock matrix. Finally, 3D reconstruction and voxel calculations were used to determine the volume fraction of pores and fractures. Two peaks were clearly visible in the graph showing pore size and pore volume fraction; the larger pore size corresponds to the fracture rate, while the smaller peak represents the porosity. The total permeability at room temperature was obtained using a pulse attenuation permeameter. k 1- k 10 Since the empirical relationship between porosity and matrix pore permeability has been obtained, the permeability of microfractures can be obtained from the difference between total permeability and matrix pore permeability. The functional relationship between the fracture rate and permeability of microfractures can be obtained using data processing software such as MATLAB. The treated rock sample 8-20 was cut into multi-fracture specimens with a specific roughness characteristic using a wire cutter, and main fractures of different widths were taken. Finally, multiple holes 8-19 were drilled from the inner surface of the multi-fracture specimens using a 0.8mm drill bit to arrange temperature measuring lines 8-24, etc., as needed. The aforementioned special rock sample 8-20 was then prepared. Its basic parameters, such as matrix porosity and permeability, microfracture fracture rate and permeability, main fracture aperture, and fracture network distribution morphology, have been obtained and can be used for numerical simulation and theoretical verification.

[0060] Furthermore, it can be like Figure 5 and Figure 6 As shown, Figure 5 This is a schematic diagram of the interior of the thermo-fluid-structure interaction pressure chamber 8. Figure 6 This is a schematic diagram of the axial pressure chamber 8-8. The heat-fluid-solid coupling pressure chamber 8 also includes an oil outlet 8-13, an oil injection hole 8-15, an exhaust hole 8-16, an annular heating band 8-17, and an on / off valve 8-14 disposed inside the annular inner wall 8-12. The oil injection hole 8-15 and the exhaust hole 8-16 are connected to the on / off valve 8-14. The annular outer wall and the annular inner wall of the heat-fluid-solid coupling pressure chamber 8 are filled with heat insulation material 8-26. The annular heating band 8-17 is disposed on the top of the annular inner wall 8-12.

[0061] The heat-fluid-solid coupling pressure chamber 8 further includes an internal oil bath chamber 8-25, a safety device 8-7, an axial pressure chamber 8-8, and a confining pressure device 8-10. The oil bath chamber 8-25 is connected to the annular inner wall 8-12, and the rock sample 8-20 is disposed within the oil bath chamber 8-25. The annular inner wall 8-12 includes a front wall 8-11, a first rear wall 8-6, and a second rear wall 8-9. The confining pressure device 8-10 is connected to the front wall 8-11, the inner surface of the first rear wall 8-6 ​​is connected to the axial pressure chamber 8-8, and the first rear wall 8-6 ​​is connected to the second rear wall 8-9. The safety device 8-7 is connected to the outer surface of the first rear wall 8-6 ​​and the outer surface of the second rear wall 8-9, respectively.

[0062] Specifically, the heat-fluid-solid coupling pressure chamber 8 is equipped with a confining pressure device 8-10, an annular heating belt 8-17, an annular inner wall 8-12, an axial pressure pressurizing device (composed of the front wall 8-11 of the annular inner wall 8-12 and a front clamp 8-4), and a safety device 8-7. All six devices are detachable. The oil bath chamber 8-25 is used to store heated and pressurized oil. The confining pressure device 8-10 is connected to the annular inner wall 8-12 for pressurizing the oil in the oil bath chamber 8-25, and the annular heating belt 8-17 is tightly connected to the annular inner wall 8-12 for heating the oil in the oil bath chamber 8-25.

[0063] The axial pressure applying device consists of the annular inner wall 8-12, the front wall 8-11 of the chamber, and the front clamp 8-4, used to apply axial pressure to the rock sample 8-20. The safety device 8-7 consists of two semicircles, which, after assembly, can be inserted into the front clamp 8-4 or the rear clamp 8-5 to prevent the front clamp 8-4 or the rear clamp 8-5 from detaching from the oil bath chamber 8-25 during the application of axial pressure, thus preventing potential danger. The assembled axial pressure chamber 8-8 is then connected to the rock sample 8-20 and the clamping device, completing the assembly of the axial pressure chamber 8-8. Next, the axial pressure chamber 8-8 is fitted into a copper sleeve (i.e., the first sleeve device 8-18) and connected to the external devices and microcomputer detection equipment. This completes the assembly of the entire thermo-fluid-structure interaction triaxial pressure chamber, fulfilling the preparation steps for the experiment.

[0064] The following are the specific steps in the experimental process:

[0065] After purging the air from the confining pressure device 8-10 and the axial pressure pressurizing device, open the oil inlet and outlet at the top of the axial pressure chamber 8-8, and add bath oil until the entire oil bath chamber 8-25 is filled. Close the opening and tighten the screws. Add pressurized oil into the cavity of the confining pressure device 8-10 to apply axial pressure σ1 and confining pressure σ3. Close the on / off valve 8-14. Use the annular heating belt 8-17 to heat the liquid oil in the oil bath chamber 8-25 to the target temperature T0. After the temperature stabilizes, under the action of heat transfer, the outer surface temperature of the sample, the liquid oil temperature in the oil bath chamber 8-25, the surface temperature of the clamping device, and the temperature of the axial pressure chamber 8-8 are all consistent with the surface temperature of the annular heating belt 8-17, all being T0. At this time, due to the change in the liquid oil temperature in the axial pressure chamber 8-8, the axial pressure and confining pressure have changed. It is necessary to open the on / off valve 8-14 again to adjust the axial pressure and confining pressure to σ1 and σ3 respectively, and then close the on / off valve 8-14. For seepage-heat transfer tests on multi-stage fractured network rock sample 8-20 using a constant heat source (continuous heating to maintain a constant oil bath temperature), the microcomputer detects and controls the heating of the annular heating belt 8-17 after the test begins, maintaining the liquid oil in the pressure chamber at the target temperature T0. For seepage-heat transfer tests on multi-stage fractured network rock sample 8-20 using a non-constant heat source (the oil bath is heated to a certain temperature and then heating stops, with heat exchanged only by the heat exchange medium), the annular heating belt 8-17 is closed to stop heating. For long-term heat exchange tests, due to significant changes in the liquid oil temperature inside the axial pressure chamber 8-8, the confining pressure and axial pressure change. The microcomputer needs to detect the pressure change and set a confining pressure change threshold, such as 5%. Whenever the confining pressure change exceeds this threshold, the on / off valve 8-14 is reopened to pressurize the axial pressure and confining pressure to σ1 and σ3 respectively, and then the on / off valve 8-14 is closed again. Since the oil pressure inside the confining pressure device 8-10 is much lower than the liquid oil pressure inside the axial pressure chamber 8-8, the added oil will not affect the overall heat. An insulating sleeve (i.e., the first sleeve device 8-18) is installed outside the axial pressure chamber 8-8, and the pressurized pipeline is wrapped with insulating material 8-26. The on / off valve 8-14 prevents pressure oil exchange. Therefore, it can be considered that the total heat loss of the entire heat-fluid-solid coupling pressure chamber 8 is caused by the heat exchange medium.

[0066] The front wall 8-11 of the chamber is equipped with a confining pressure device 8-10 and the front wall 8-11 itself. The oil pressure in the oil bath chamber 8-25 is indirectly controlled by the confining pressure device 8-10, while the temperature control device 9 controls the temperature of the oil in the oil bath chamber 8-25. This avoids the risk of high-temperature oil leakage and prevents the high-temperature oil from constantly exchanging heat with the outside environment, which would cause fluctuations in the oil bath heat source. In the seepage-heat transfer test study of the multi-level fracture network rock sample 8-20 with a non-constant heat source, because the hydraulic oil capacity in the confining pressure device 8-10 is much smaller than the oil capacity in the oil bath chamber 8-25, and the pressurization pipe is wrapped with heat insulation material 8-26, the entire heat-fluid-solid coupling pressure chamber 8 is enclosed by the heat insulation material 8-26. When the confining pressure is controlled by an external electric pressurization pump, the heat loss is negligible. If traditional equipment is used to directly pressurize the bath oil in the oil bath chamber 8-25, there will be a large amount of heat exchange.

[0067] Furthermore, the second pressure regulating device includes a first pressure regulating pipeline and a second pressure regulating pipeline, both of which are connected to the axial pressure chamber 8-8; the first pressure regulating pipeline consists of a first electric pressurizing pump 10, a third regulating valve 12, and a fourth pressure sensor 13 connected in sequence, and the second pressure regulating pipeline consists of a second electric pressurizing pump 14, a fourth regulating valve 15, and a fifth pressure sensor 16 connected in sequence.

[0068] Specifically, the second pressure regulating device, also known as the axial pressure and confining pressure loading device, includes a first pressure regulating pipeline and a second pressure regulating pipeline. The first pressure regulating pipeline consists of a first electric pressurizing pump 10, a third regulating valve 12, and a fourth pressure sensor 13 connected in sequence. The second pressure regulating pipeline consists of a second electric pressurizing pump 14, a fourth regulating valve 15, and a fifth pressure sensor 16 connected in sequence. A microcomputer monitors and controls the temperature control device 9 to ensure the temperature applied to the rock sample 8-20 throughout the experiment. By monitoring the fourth pressure sensor 13 and the fifth pressure sensor 16, the microcomputer controls the first electric pressurizing pump 10 and the second electric pressurizing pump 14 to apply axial pressure and confining pressure, respectively, thus achieving stable application of axial pressure and confining pressure to the rock sample 8-20.

[0069] Specifically, during the seepage-heat transfer test of rock sample 8-20 with a non-constant heat source and a multi-level fracture network, the confining pressure and axial pressure changed due to the large temperature change of the liquid oil inside the pressure chamber. It was necessary to use a microcomputer to detect the pressure change and set a confining pressure change threshold, such as 5%. Whenever the pressure change exceeded this threshold, the on / off valve 8-14 was reopened to pressurize the axial pressure and confining pressure to maintain pressure stability, and then the on / off valve 8-14 was closed again.

[0070] Furthermore, the first pressure regulating device includes a pressure stabilizing device 5, a mass flow meter 6, a preheating device 7, a first ball valve 21, a first oil filter 22, and a first filter 23 connected in sequence; the pressure stabilizing device 5 is connected to the heat exchange medium injection device, and the first filter 23 is connected to the fluid inlet 8-1.

[0071] The heat exchange medium cooling circulation device includes a back pressure valve 24, a first temperature sensor 25, a first pressure sensor 26, a cooler 27, a first check valve 29, a second oil filter 30, a third pressure sensor 31, a second filter 32, a differential pressure sensor 33, and a first low-temperature coolant circulation pump 28 connected in parallel to both ends of the cooler 27; the back pressure valve 24 is connected to the heat exchange medium injection device, and the differential pressure sensor 33 is connected to the annular inner wall 8-12.

[0072] A first passage and a second passage are provided between the first pressure regulating device and the heat exchange medium cooling circulation device. The first passage consists of a second check valve 35, a first regulating valve 36 and a second ball valve 37 connected in sequence. The second check valve 35 is connected to the cooler 27 and the first check valve 29 respectively. The second ball valve 37 is connected to the pressure stabilizing device 5 and the mass flow meter 6 respectively.

[0073] The second passage consists of a second regulating valve 38 and a third ball valve 11 connected in sequence. The second regulating valve 38 is connected to the cooler 27 and the first check valve 29 respectively, and the third ball valve 11 is connected to the preheating device 7 and the first ball valve 21 respectively.

[0074] The heat exchange medium injection device includes a gas storage cylinder 1, a fourth ball valve 17, a liquid storage tank 2, a fifth ball valve 18, a third filter 19, a plunger pump 3, a third pressure sensor 31, and a safety valve 20 connected in sequence. The safety valve 20 is also connected to the preheating device 7. The heat exchange medium injection device also includes a second cryogenic coolant circulation pump 4, which is connected to the liquid storage tank 2 and the plunger pump 3, respectively. The liquid storage tank 2 is also connected to the back pressure valve 24.

[0075] The second pressure regulating device includes a first pressure regulating pipeline and a second pressure regulating pipeline, both of which are connected to the axial pressure chamber 8-8. The first pressure regulating pipeline consists of a first electric pressurizing pump 10, a third regulating valve 12, and a fourth pressure sensor 13 connected in sequence. The second pressure regulating pipeline consists of a second electric pressurizing pump 14, a fourth regulating valve 15, and a fifth pressure sensor 16 connected in sequence.

[0076] Specifically, after the triaxial pressure chamber of the thermo-fluid-solid coupling is debugged, the fourth ball valve 17 between the gas storage cylinder 1 and the liquid storage tank 2 is opened. Gaseous CO2 (carbon dioxide) in the gas storage cylinder 1 enters the test system, that is, into the liquid storage tank 2, where it is cooled to a liquid state. After filtration, the liquid CO2 enters the plunger pump 3. The pressure difference before and after the back pressure valve 24 is controlled by adjusting its opening, i.e., the pressure difference between the test section and the liquid storage tank 2. Therefore, CO2 can be pressurized to the supercritical pressure state required for the test within the plunger pump 3. By adjusting the plunger pump 3, the mass flow rate of liquid CO2 in the system reaches the set value. The liquid CO2 enters the pressure stabilizing device 5 to eliminate pressure fluctuations, and the mass flow rate of liquid CO2 is measured using a mass flow meter 6. By adjusting the parallel pipelines (i.e., the first and second passages) set before the mass flow meter 6, the flow rate fluctuations of liquid CO2 caused by the pump piston compression at lower flow rates are minimized. After passing through the preheating device 7, the liquid CO2 has a bypass (second passage) and a main path. The main path is the liquid passage along the first ball valve 21, the first oil filter 22, and the first filter 23. By controlling the ball valves of the main path and the bypass, the liquid CO2 can flow instantaneously through the heated rock sample. The liquid CO2 enters the rock fissures for flow heat exchange, and is then cooled to the required temperature by the cooler 27. It then returns to the storage tank 2 through the back pressure valve 24, forming a closed flow loop. In summary, this application uses the mass flow meter 6, various pressure sensors, differential pressure sensor 33, and various temperature sensors (i.e., temperature detection device 34) to obtain information such as fluid temperature, pressure, and flow rate at the inlet and outlet of the rock sample 8-20, and uses thermocouples (temperature measuring wires 8-24) arranged inside the rock sample 8-20 to obtain internal temperature information.

[0077] In summary, this application utilizes a specially designed wiring method to measure temperature changes at any location. A mixing device 8-28 is designed at the interface between the clamping device and rock sample 8-20, avoiding uneven fluid temperature near the contact point between the clamping device and rock sample 8-20, accurately controlling the fluid temperature in the core test section, and further ensuring the accuracy of the experiment.

[0078] Design a special rock sample 8-20 to simulate the special geological conditions in the mining-thermal co-mining project where the thermal extraction process (rock matrix pores + a large number of micro fractures + a small number of main fractures) coexists. Provide basic experimental parameters for obtaining the sample, such as the porosity and permeability of the pore matrix, the fracture rate and permeability of the micro fractures, the fracture aperture of the diagenetic fractures, and the fracture network distribution.

[0079] Therefore, this application can realize data measurement of multi-level fracture network rock sample 8-20 under the action of a non-constant heat source during the seepage-heat transfer process, corresponding to the non-constant heat source loading situation of multi-level fracture network rock sample 8-20, which is difficult to achieve in experiments. By embedding a confining pressure device 8-10 in the front wall of the heat-fluid-solid coupling pressure chamber 8, the heating and pressurization are separated. The axial pressure pressurization device is composed of the rear clamp 8-5, the rear wall of the first chamber 8-6, and the rear wall of the second chamber 8-9, so that the entire device can be wrapped in the heat insulation material 8-26. While applying confining pressure and axial pressure simultaneously, heating is stopped after the oil bath is heated to a certain temperature, realizing the test scenario where heat is exchanged only by the heat exchange medium.

[0080] Furthermore, the above figures are merely illustrative of the processes included in the method according to exemplary embodiments of this application, and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0081] It should be understood that this application is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A device for detecting seepage heat transfer data based on rock samples with multi-level fracture networks, characterized in that, The device includes: a heat exchange medium injection device, a first pressure regulating device, a second pressure regulating device, a heat exchange medium cooling circulation device, a heat-fluid-solid coupling pressure chamber, a temperature control device, and a temperature detection device. The heat exchange medium injection device is connected to the first pressure regulating device and the heat exchange medium cooling circulation device respectively, and the heat-fluid-solid coupling pressure chamber is connected to the first pressure regulating device, the second pressure regulating device, the heat exchange medium cooling circulation device, the temperature control device and the temperature detection device respectively. The heat exchange medium injection device is used to output the heat exchange medium. The heat exchange medium enters the heat-fluid-solid coupling pressure chamber after passing through the first pressure regulating device. After flowing heat exchange in the heat-fluid-solid coupling pressure chamber, it flows into the heat exchange medium cooling circulation device to cool the heat exchange medium after flowing heat exchange, and then transports the cooled heat exchange medium to the heat exchange medium injection device. The second pressure regulating device is used to regulate the pressure of the heat-fluid-solid coupling pressure chamber, which includes an internal rock sample, a clamping device, a first sleeve device, a second sleeve device, and multiple temperature measuring lines. The rock sample has a through hole, and the first sleeve device is fitted into the through hole. The first sleeve device is filled with heat insulation material to prevent the heat exchange medium from flowing into the through hole, so that the heat exchange medium flowing into the rock sample only flows in the matrix pores and cracks of the rock sample. The second sleeve device is fitted onto the outer surface of the rock sample. The first sleeve device and the second sleeve device are connected by multiple temperature measuring lines. The multiple temperature measuring lines are located in the cracks of the rock sample, and each temperature measuring line is connected to the temperature detection device. The clamping device is used to clamp both ends of the rock sample. The clamping device is connected to the annular inner wall of the heat-fluid-solid coupling pressure chamber. The heat exchange medium enters from the annular inner wall of the heat-fluid-solid coupling pressure chamber, flows through the clamping device, and enters the rock sample. The temperature detection device detects the temperature of the heat exchange medium in the rock sample through each of the temperature measuring lines. The heat-fluid-solid coupling pressure chamber further includes an internal mixing device, a fluid inlet, and a fluid outlet. The mixing device is located at both ends of the rock sample. The clamping device includes a front clamp and a rear clamp, which are fixed by screws. Both the front clamp and the rear clamp have insulated water injection channels, which are connected to the mixing device. Graphite gaskets are installed in the gaps formed between the front clamp and the rear clamp and the second sleeve device. The fluid inlet and the fluid outlet are located within the two insulated water injection channels, and both channels are filled with insulating material. The annular inner wall is a hollow chamber located inside the heat-fluid-solid coupling pressure chamber, and both the fluid inlet and the fluid outlet are connected to the annular inner wall. The mixing device has multiple flow openings. After the heat exchange medium enters from the fluid inlet, it flows through the heat-insulating water injection channel of the pre-clamping device and is then dispersed and injected into the rock sample through the multiple flow openings of the mixing device.

2. The device for detecting seepage heat transfer data based on multi-level fracture network rock samples according to claim 1, characterized in that, The heat-fluid-solid coupling pressure chamber further includes an oil outlet, an oil injection port, an exhaust port, an annular heating band, and an on / off valve disposed within the annular inner wall. The oil injection port and the exhaust port are connected to the on / off valve. The annular outer wall of the heat-fluid-solid coupling pressure chamber is filled with heat insulation material between itself and the annular interior. The annular heating band is wrapped around the outer surface of the annular inner wall.

3. The device for detecting seepage heat transfer data based on multi-level fracture network rock samples according to claim 2, characterized in that, The thermo-fluid-solid coupling pressure chamber further includes an internal oil bath chamber, a safety device, an axial pressure chamber, and a confining pressure device. The oil bath chamber is connected to the annular inner wall, and the rock sample is placed inside the oil bath chamber. The annular inner wall includes a front wall, a first rear wall, and a second rear wall. The confining pressure device is connected to the front wall, the inner surface of the first rear wall is connected to the axial pressure chamber, and the first rear wall is connected to the second rear wall. The safety device is connected to the outer surface of the first rear wall and the outer surface of the second rear wall, respectively.

4. The device for detecting seepage heat transfer data based on multi-level fracture network rock samples according to claim 3, characterized in that, The first pressure regulating device includes a pressure stabilizing device, a mass flow meter, a preheating device, a first ball valve, a first oil filter, and a first filter connected in sequence; the pressure stabilizing device is connected to the heat exchange medium injection device, and the first filter is connected to the fluid inlet.

5. The device for detecting seepage heat transfer data based on multi-level fracture network rock samples according to claim 4, characterized in that, The heat exchange medium cooling circulation device includes a back pressure valve, a first temperature sensor, a first pressure sensor, a cooler, a first check valve, a second oil filter, a third pressure sensor, a second filter, a differential pressure sensor, and a first low-temperature coolant circulation pump connected in parallel to both ends of the cooler, connected in sequence; the back pressure valve is connected to the heat exchange medium injection device, and the differential pressure sensor is connected to the annular inner wall.

6. The device for detecting seepage heat transfer data based on multi-level fracture network rock samples according to claim 5, characterized in that, A first passage and a second passage are provided between the first pressure regulating device and the heat exchange medium cooling circulation device. The first passage consists of a second check valve, a first regulating valve and a second ball valve connected in sequence. The second check valve is connected to the cooler and the first check valve respectively. The second ball valve is connected to the pressure stabilizing device and the mass flow meter respectively. The second passage consists of a second regulating valve and a third ball valve connected in sequence. The second regulating valve is connected to the cooler and the first check valve, respectively, and the third ball valve is connected to the preheating device and the first ball valve, respectively.

7. The device for detecting seepage heat transfer data based on multi-level fracture network rock samples according to claim 6, characterized in that, The heat exchange medium injection device includes a gas storage cylinder, a fourth ball valve, a liquid storage tank, a fifth ball valve, a third filter, a plunger pump, a third pressure sensor, and a safety valve connected in sequence. The safety valve is also connected to the preheating device. The heat exchange medium injection device also includes a second cryogenic coolant circulation pump, which is connected to the liquid storage tank and the plunger pump, respectively. The liquid storage tank is also connected to the back pressure valve.

8. The device for detecting seepage heat transfer data based on multi-level fracture network rock samples according to claim 7, characterized in that, The second pressure regulating device includes a first pressure regulating pipeline and a second pressure regulating pipeline, both of which are connected to the axial pressure chamber. The first pressure regulating pipeline consists of a first electric pressurizing pump, a third regulating valve, and a fourth pressure sensor connected in sequence, while the second pressure regulating pipeline consists of a second electric pressurizing pump, a fourth regulating valve, and a fifth pressure sensor connected in sequence.

Images