Fracture internal convection heat transfer experimental rock plate clamping device and method

Abstract

The application relates to the technical field of core clamps, and discloses a kind of fracture internal convection heat transfer experimental rock plate clamping device and method, it includes device ontology, first integrated block and second integrated block are oppositely arranged on the two sides of device ontology, device ontology further includes first gland and second gland of movable connection, first gland and second gland are equipped with containing groove for placing rock plate, first gland and second gland are connected and form simulated fracture between two rock plates, first gland and second gland are all provided with filtrate outlet, two filtrate outlets are all communicated with containing groove, it can be used for fluid fracture internal convection heat transfer experiment, comprehensively and accurately evaluates the convection heat transfer law of fluid in fracture, and comprehensively considers the influence of fluid loss on the convection heat transfer effect of fluid in fracture, to obtain more accurate convection heat transfer data.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of core clamps, in particular to a fracture internal convection heat transfer experimental rock plate clamping device and method. BACKGROUND

[0002] The heat transfer problem of fluid flow in fractures is involved in the fields of reservoir reconstruction, oil and gas development, and high-temperature geothermal resource utilization. When fluid flows through the surface of the fracture, heat exchange occurs with the solid matrix, and this flow and heat transfer process is continuous, which causes changes in fluid temperature, with a temperature rise of tens of degrees Celsius. Changes in temperature affect the effective evaluation of the effect of reservoir reconstruction and the effect of geothermal resource utilization.

[0003] The simulation experiment of fluid flow and heat transfer in fractures is an effective means to study the law of convection heat transfer. The core clamp, as the core component of the flow and heat transfer simulation experiment system, its structure is of great significance to the simulation experiment effect. Due to the pressure difference between the fluid in the fracture and the surrounding rock fluid, fluid loss to the formation is inevitable during the flow process in the fracture. Fluid loss will directly affect the flow and heat transfer effect. Therefore, the influence of fluid loss must be considered in the simulation experiment. However, the existing core clamping device for fluid flow and heat transfer in fractures mainly fills cylindrical cores and does not consider the influence of fluid loss on fluid flow and heat transfer in fractures.

[0004] The Chinese invention patent with patent number CN202310019516.X proposes an experimental device and interpretation method for simulating core seepage flow heat and mass transfer under high temperature and high pressure. The experimental system includes a sample injection assembly, a clamp assembly, a temperature and pressure control assembly, a sampling assembly, and a host computer. The sample injection assembly, clamp assembly, and sampling assembly are connected in sequence. The temperature and pressure control assembly is connected with the sample injection assembly and the clamp assembly. The host computer is connected with the clamp assembly, the temperature and pressure control assembly, the sampling assembly, and the sample injection assembly. The beneficial effects of the present application are: through the experimental device and method, the fracture aperture, permeability, and thermal conductivity of the core can be obtained, and the seepage flow and heat transfer process of the core can be characterized. Through multiple experiments, the influence of core fracture aperture, permeability, and thermal conductivity on core seepage flow and heat transfer can be explored.

[0005] The above technical solution solves the problem of studying the influence of physical factors on core seepage flow and heat transfer, but does not consider the influence of fluid loss on heat transfer. Moreover, the technical solution and interpretation method are complex and have certain drawbacks. SUMMARY

[0006] The purpose of the present application is to provide a crack internal convection heat transfer experiment rock plate clamping device, which can be used for fluid crack internal convection heat transfer experiment, comprehensively and accurately evaluate the fluid crack internal convection heat transfer law, and comprehensively consider the influence of fluid loss on fluid crack internal convection heat transfer effect, and obtain more accurate convection heat transfer data.

[0007] Another purpose of the present application is to provide a use method of the crack internal convection heat transfer experiment rock plate clamping device.

[0008] To solve the above technical problems, the technical scheme adopted by the present application is:

[0009] In a first aspect, the present application provides a crack internal convection heat transfer experiment rock plate clamping device, which comprises a device body, first and second integrated blocks are arranged opposite to the two sides of the device body, the device body further comprises first and second movable covers, the first and second covers are provided with accommodating grooves for placing rock plates, the first and second covers are connected and form a simulated crack between the two rock plates, the simulated crack is communicated with the accommodating grooves, the first integrated block is provided with a liquid inlet, and the second integrated block is provided with a liquid outlet, the liquid inlet and the liquid outlet are communicated with the simulated crack, the first and second covers are provided with filtrate outlets, and the two filtrate outlets are communicated with the accommodating grooves.

[0010] In the present application, in order to consider the influence of fluid loss on fluid crack internal convection heat transfer effect, the structure of simulated crack and two filtrate outlets is creatively added, when the fluid flows in the simulated crack, heat exchange with the rock plate occurs, which causes the temperature of the low-temperature fluid to rise and flow out of the liquid outlet, and the fluid loss occurs to the rock plate through the crack during the flow process, the filtrate flows out of the two filtrate outlets of the first and second covers, the effect of rock plate fluid loss is simulated, and the temperature of the experimental fluid flowing into and out of the simulated crack is recorded continuously during the experiment, and the experiment is ended after the fluid temperature is stable, at this time, the heat transfer data of the fluid after filtration can be obtained, and more accurate and comprehensive convection heat transfer data can be calculated.

[0011] In some embodiments of the present application, the device body further comprises two electric heating plates, the two electric heating plates are respectively located in the two accommodating grooves and abut against the inner walls of the first and second covers, in order to simulate the effect of fluid crack internal convection heat transfer, an external electric heating plate is needed to heat the rock plate to obtain the required experimental data, since two rock plates are arranged in the device, two groups of electric heating plates are needed to heat the two rock plates respectively, the output end of the electric heating plate abuts against the rock plate, and the cold end abuts against the inner wall of the cover, which can effectively transmit heat to the rock plate, and heat is applied from the end of the rock plate far away from the simulated crack, so that the overall temperature of the rock plate can be ensured to be constant after the temperature is stable, if the heating is performed from the end close to the simulated crack, the rock plate may be unevenly heated, which affects the subsequent experimental results.

[0012] In some embodiments of the present application, the device body further comprises a plurality of rubber sleeves, which are respectively located in the two accommodating grooves and abut against the inner walls of the first and second gland. The rubber sleeves serve the purpose of sealing, and can increase the tightness of the rock plate and the gland, preventing fluid leakage between the two.

[0013] In some embodiments of the present application, the device body further comprises a plurality of surrounding pressure pipelines, which are respectively embedded in the first and second gland, and one end of each of the surrounding pressure pipelines is in communication with the rubber sleeve, and the other end respectively penetrates the outer side wall of the first and second integrated block and forms a plurality of surrounding pressure interfaces. The surrounding pressure pipelines are used to inject gas or water into the rubber sleeve, so as to apply surrounding pressure to the rock plate. After the surrounding pressure is applied, the rubber sleeve will be tightly attached to the rock plate, ensuring that the rock plate is uniformly subjected to surrounding pressure, preventing fluid leakage from the edge of the rock plate when flowing in the crack.

[0014] In some embodiments of the present application, the device body further comprises two temperature sensors, which are respectively located at the two ends of the simulated crack. Since multiple groups of fluid temperature are recorded when flowing in and out during the experiment, temperature sensors are respectively arranged at the two ends of the simulated crack, which can read the temperature before and after the fluid heat exchange.

[0015] In some embodiments of the present application, the opening part of the liquid inlet and the liquid outlet is provided with a temperature sensor interface, and the temperature sensor is electrically connected with the temperature sensor interface. In order to more conveniently read the temperature of the temperature sensor, the temperature sensor interface is further provided at the position of the liquid inlet and the liquid outlet. The two temperature sensors are respectively electrically connected with the temperature sensor interface through the liquid inlet and the liquid outlet. The temperature sensor interface is electrically connected to the data acquisition instrument or the computer, so as to read the temperature.

[0016] In some embodiments of the present application, the outer wall of the first and second integrated block is sleeved with a gasket. The first and second integrated blocks are detachably connected with the first and second gland. Since the device itself requires high sealing performance, interference fit is required during connection to ensure the sealing effect of the connection. Since the integrated block and the gland are both made of metal material, long-term use will cause wear and even deformation, affecting the sealing performance of the device. Therefore, the outer wall of the first and second integrated block is sleeved with a gasket. The gasket can buffer the connection between the integrated block and the gland, prevent direct contact between the two, and the gasket has softness, which can more easily achieve interference fit during connection of the two, further increase the sealing performance, improve the service life of the device, and reduce maintenance.

[0017] In some embodiments of the present application, the device body further comprises a plurality of wires embedded in the first gland and the second gland, one end of the plurality of wires is respectively electrically connected with the two electric heating plates, and the other end of the plurality of wires respectively passes through the outer side wall of the first integrated block and the second integrated block and forms a plurality of electrical interfaces for supplying power to the electric heating plates. Since the device needs to be filled with rock plates, the device is set as a split structure as a whole, but in order to flow in and out of the liquid, and not to damage the simulated cracks and the liquid inlet and outlet, the first integrated block and the second integrated block are provided, and the liquid inlet and outlet, the temperature sensor interface and the electrical interface are integrated on the integrated block. Therefore, the separate split can avoid the separation of the integrated interfaces, and the detachable structure is convenient for maintenance personnel to maintain, thereby increasing the service life of the device.

[0018] In some embodiments of the present application, the first gland and the second gland are connected by two long bolts and two nuts, the first long bolt passes through the first gland, the first integrated block and the second gland in sequence and is connected with the first nut, and the second long bolt passes through the first gland, the second integrated block and the second gland in sequence and is connected with the second nut, so as to achieve the connection effect of the device as a whole.

[0019] In some embodiments of the present application, the plurality of long bolts and the plurality of nuts can also be connected, and the connection mode is the same as described above.

[0020] In some embodiments of the present application, the size of the rock block is 25*50*100mm.

[0021] In some embodiments of the present application, the size of the electric heating plate is 50*100mm.

[0022] In the second aspect, the embodiments of the present application provide a use method of the crack internal convection heat transfer experimental rock plate clamping device, which comprises the following steps: S1, opening the first gland and the second gland, and filling two rock blocks with the same size into the first gland and the second gland respectively; S2, forming a simulated crack by the two rock blocks, and adjusting the positions of the two rock blocks to adjust the height of the simulated crack; S3, closing the first gland and the second gland, and filling water into the plurality of rubber sleeves through the plurality of confining pressure interfaces and applying confining pressure to make the plurality of rubber sleeves have an interference fit with the two rock blocks; S4, turning on the two electric heating plates and adjusting to a set temperature, pumping a constant flow of fluid from the liquid inlet after the temperature is stable, and recording the temperature when the fluid flows in and the temperature when the fluid flows out; and S5, calculating the convective heat transfer coefficient of the fluid flowing in the simulated crack according to the recorded data.

[0023] In some embodiments of the present application, in the step S2, the height of the simulated crack is adjusted in the range of 0-5mm, and the length and width of the simulated crack are 50*100mm respectively.

[0024] In some embodiments of the present application, the calculation formula in step S5 is shown in formula (1):

[0025]

[0026] wherein h is the convective heat transfer coefficient, W / (m 2 ·K);c p is the specific heat capacity of the fluid, J / (kg·K);Q is the fluid flow rate, m 3 / s;ρ is the fluid density, kg / m 3 ; T in and T out are the fluid inlet and outlet temperatures, K respectively;D is the height of the rock plate, m;L is the length of the rock plate, m;T c is the temperature of the outer surface of the rock plate, i.e. the temperature of the electric heating plate, K.

[0027] Compared with the prior art, the embodiments of the present application have at least the following advantages or beneficial effects:

[0028] 1. The simulated fracture and filtrate outlet can realize the influence of fluid filtration on the convective heat transfer effect in the fluid fracture in the experiment, and the obtained heat transfer coefficient is more comprehensive and accurate.

[0029] 2. The first integrated block and the second integrated block integrate the inlet and outlet ports, temperature sensor interfaces and electrical interfaces, which is convenient for use and maintenance of the user, and increases the service life of the device.

[0030] 3. The rubber sleeve can form an interference fit between the rock block and the gland, has high sealing performance, prevents fluid leakage, and increases the accuracy of experimental data. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0032] Figure 1 The structure of a fracture convective heat transfer experimental rock plate clamping device provided by the present application is shown in the figure.

[0033] Figure legend: 100-first gland;200-second gland;300-first integrated block;400-second integrated block;410-gasket;420-confining pressure line;421-confining pressure interface;500-rock block;510-electric heating plate;520-rubber sleeve;600-filtrate outlet;700-simulated fracture;710-inlet;720-outlet. DETAILED DESCRIPTION

[0034] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will be combined with the accompanying drawings for the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present application.

[0036] The features and performances of the present application are further described in detail in combination with the embodiments.

[0037] Embodiment 1

[0038] Please refer to Figure 1 , Figure 1 The structural schematic diagram of the embodiments of the present application is shown.

[0039] The present application provides a crack internal convection heat transfer experimental rock plate clamping device, which comprises a device body, first and second integrated blocks 300 and 400 are arranged opposite to the two sides of the device body, the device body further comprises first and second movable covers 100 and 200, the first and second movable covers 100 and 200 are both provided with containing grooves for placing rock plates, the first and second movable covers 100 and 200 are connected and form a simulated crack 700 between the two rock plates, the simulated crack 700 is communicated with the containing grooves, the first integrated block 300 is provided with a liquid inlet 710, and the second integrated block 400 is provided with a liquid outlet 720, the liquid inlet 710 and the liquid outlet 720 are both communicated with the simulated crack 700, the first and second movable covers 100 and 200 are both provided with filtrate outlets 600, and the two filtrate outlets 600 are both communicated with the containing grooves.

[0040] In order to simulate the heat convection effect in the fluid fracture, the device body further comprises two electric heating plates 510, which are respectively located in the two accommodating grooves and respectively abut against the inner wall of the first gland 100 and the inner wall of the second gland 200. The electric heating plates 510 are arranged to heat the rock plates to obtain the required experimental data. Since two rock plates are arranged in the device, two groups of electric heating plates 510 are required to heat the two rock plates. The output end of the electric heating plate 510 abuts against the rock plate, and the cold end abuts against the inner wall of the gland, which can effectively transmit heat to the rock plate. The rock plate is heated from the end away from the simulated fracture 700, and the overall temperature of the rock plate can be kept constant after the temperature is stable. If the rock plate is heated from the end close to the simulated fracture 700, the heating of the rock plate may be uneven, which affects the subsequent experimental results.

[0041] In order to prevent fluid from leaking between the rock block 500 and the gland, the device body further comprises a plurality of rubber sleeves 520, which are respectively located in the two accommodating grooves and respectively abut against the inner wall of the first gland 100 and the inner wall of the second gland 200. The rubber sleeves 520 are arranged to seal the rock plates, and the rubber sleeves 520 can increase the tightness of the rock plates and the glands to prevent fluid from leaking between them.

[0042] In order to make the rubber sleeve 520 better fit the rock block 500, the device body further comprises a plurality of confining line 420, which are respectively embedded in the first gland 100 and the second gland 200, and one end of the confining line 420 is respectively communicated with the rubber sleeve 520, and the other end is respectively penetrated out of the outer side wall of the first integrated block 300 and the second integrated block 400 and forms a plurality of confining interfaces 421. The confining line 420 is arranged to inject gas or water into the rubber sleeve 520 to apply confining pressure to the rock plate. After the confining pressure is applied, the rubber sleeve 520 will tightly adhere to the rock plate, ensuring that the confining pressure on the rock plate is uniform, and preventing fluid from leaking from the edge of the rock plate when flowing in the fracture.

[0043] In order to obtain the temperature before and after the fluid heat transfer, the device body further comprises two temperature sensors, which are respectively located at both ends of the simulated fracture 700. Since multiple groups of fluid inflow and outflow temperatures need to be recorded in the experiment, temperature sensors are arranged at both ends of the simulated fracture 700 to read the temperature before and after the fluid heat exchange.

[0044] In order to read the temperature of the temperature sensor, the opening part of the liquid inlet 710 and the liquid outlet 720 is provided with a temperature sensor interface, and the temperature sensor is electrically connected with the temperature sensor interface. In order to read the temperature of the temperature sensor more conveniently, the temperature sensor interface is also provided at the position of the liquid inlet 710 and the liquid outlet 720, and the two temperature sensors are respectively electrically connected with the temperature sensor interface through the liquid inlet 710 and the liquid outlet 720. The temperature sensor interface is electrically connected to the data acquisition instrument or the computer, and the temperature is read.

[0045] In order to increase the sealing property of the connection between the integrated block and the gland, the outer wall of the first integrated block 300 and the second integrated block 400 is sleeved with a gasket 410. The first integrated block 300 and the second integrated block 400 are detachably connected with the first gland 100 and the second gland 200. The device itself needs high sealing property, so that the interference fit needs to be achieved when connected to ensure the sealing effect of the connection. Since the integrated block and the gland are both metal materials, long-term use will cause wear and even deformation, affecting the sealing property of the device. Therefore, the gasket 410 is sleeved on the outer wall of the first integrated block 300 and the second integrated block 400. The gasket 410 can play a buffering effect when the integrated block and the gland are connected, preventing direct contact between the two. At the same time, the gasket 410 has softness, which makes it easier to achieve interference fit when the two are connected, further increases the sealing property, improves the service life of the device, and reduces maintenance.

[0046] In order to supply power to the electric heating plate 510, the device body further includes a plurality of wires, which are respectively embedded in the first gland 100 and the second gland 200. One end of the plurality of wires is respectively electrically connected with the two electric heating plates 510, and the other end respectively passes through the outer side wall of the first integrated block 300 and the second integrated block 400 and forms a plurality of electrical interfaces to supply power to the electric heating plate 510.

[0047] In order to realize the connection of the first gland 100 and the second gland 200, the first gland 100 and the second gland 200 are connected through two long bolts and two nuts. The first long bolt passes through the first gland 100, the first integrated block 300 and the second gland 200 in sequence and is connected with the first nut. The second long bolt passes through the first gland 100, the second integrated block 400 and the second gland 200 in sequence and is connected with the second nut, so as to achieve the connection effect of the whole device.

[0048] In use, the first grommet 100 and the second grommet 200 are opened, two rock blocks 500 with a size of 25x50x100mm are respectively filled into the first grommet 100 and the second grommet 200, and a simulated fracture 700 is formed by the two rock blocks 500, the positions of the two rock blocks 500 are adjusted to adjust the height of the simulated fracture 700, after adjustment, the first grommet 100 and the second grommet 200 are locked and closed by long bolts and nuts, and the first integrated block 300 and the second integrated block 400 are fixed, the water pump is connected with the confining pressure interface 421, then water is filled into the plurality of rubber sleeves 520 from the plurality of confining pressure interfaces 421 by the water pump to apply confining pressure, the plurality of rubber sleeves 520 are in interference fit with the two rock blocks 500, the two electric heating plates 510 are turned on and adjusted to a set temperature, after the temperature is constant, a constant flow of fluid is pumped from the liquid inlet 710, a plurality of groups of temperature when the fluid flows in and temperature when the fluid flows out are recorded, after the temperatures before and after the fluid flows out are constant, the convective heat transfer coefficient of the fluid flowing and heat transfer in the simulated fracture 700 is calculated according to the recorded data.

[0049] Embodiment 2

[0050] The embodiment 2 provides a method of a rock plate clamping device based on convective heat transfer experiment in a fracture, comprising the following steps:

[0051] S1, the first grommet and the second grommet are opened, and two rock blocks with a size of 25x50x100mm are respectively filled into the first grommet and the second grommet;

[0052] S2, the simulated fracture is formed by the two rock blocks, and the positions of the two rock blocks are adjusted so that the height of the simulated fracture is 2mm;

[0053] S3, the first grommet and the second grommet are closed, water is filled into the plurality of rubber sleeves from the plurality of confining pressure interfaces by the water pump to apply confining pressure, and the plurality of rubber sleeves are in interference fit with the two rock blocks;

[0054] S4, the two electric heating plates are turned on and adjusted to 380K, after the temperature is stable, a fluid with a pressure of 2MPa and a flow rate of 12mL / min is pumped from the liquid inlet, the temperature when the fluid flows in is 310K, and the temperature when the fluid flows out is recorded in real time by the temperature sensor;

[0055] S5, the convective heat transfer coefficient of the fluid flowing and heat transfer in the simulated fracture is calculated according to the calculation formula formula (1).

[0056] The calculation formula is shown in formula (1):

[0057]

[0058] In the formula, h is the convective heat transfer coefficient, W / (m 2 ·K); c pCp is the specific heat capacity of the fluid, J / (kgK); Q is the fluid flow rate, m / s; p is the fluid density, kg / m 3 3 ; T in and T out are the fluid inlet and outlet temperatures, respectively, K; D is the height of the rock plate, m; L is the length of the rock plate, m; T c is the temperature of the outer surface of the rock plate, i.e., the temperature of the electric heating plate, K.

[0059] Calculation process: In this embodiment, the fluid medium is pure water, and the thermophysical parameters are constant: density p = 1000 kg / m 3 ; specific heat capacity c p = 4208 J / (kgK). The fluid pressure is 2 MPa, the filtrate outlet pressure is atmospheric pressure 0.1 MPa, and the filtration pressure difference is 1.9 MPa. The flow rate Q = 0.2 x 10 -6 m 3 / s, the fluid inlet temperature T in = 310 K, the temperature of the outer surface of the rock plate T c = 380 K, the length of the rock plate L = 0.1 m, and the height of the rock plate D = 0.05 m. The fluid outlet temperature T out measured by the temperature sensor is 332 K

[0060] The convective heat transfer coefficient can be calculated according to formula (1) as follows:

[0061]

[0062] Through this embodiment, the convective heat transfer coefficient considering the filtration of the fluid in the fracture can be calculated, and the calculation result is 62.76 W / (m 2 ·K).

[0063] The above merely describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.​

Claims

1. A rock slab clamping device for experimental convection heat transfer within a crack, characterized in that, The device body is provided with a first integrated block and a second integrated block on opposite sides, and further comprises a first movable cover and a second movable cover, each of which is provided with a containing groove for placing a rock plate, and the first movable cover and the second movable cover are connected and form a simulated fracture between the two rock plates, which is in communication with the containing groove. The first integrated block is provided with a liquid inlet, and the second integrated block is provided with a liquid outlet, both of which are in communication with the simulated fracture. The first movable cover and the second movable cover are each provided with a filtrate outlet, both of which are in communication with the containing groove. The device body further comprises two electric heating plates, which are respectively located in the two containing grooves, and the output end of the electric heating plate abuts against the rock plate, and the cold end of the electric heating plate abuts against the inner wall of the first movable cover and the second movable cover. The device body further comprises a plurality of rubber sleeves, which are respectively located in the two containing grooves and abut against the inner wall of the first movable cover and the second movable cover. The device body further comprises a plurality of confining line, which are respectively embedded in the first movable cover and the second movable cover, and one end of the plurality of confining line is in communication with the plurality of rubber sleeves, and the other end respectively passes through the outer side wall of the first integrated block and the second integrated block and forms a plurality of confining interfaces. The device body further comprises two temperature sensors, which are respectively located at both ends of the simulated fracture.

2. The rock slab clamping device for the experiment of heat transfer by convection in fracture according to claim 1, characterized in that, The opening part of the liquid inlet and the liquid outlet is provided with a temperature sensor interface, and the temperature sensor is electrically connected with the temperature sensor interface.

3. The rock slab clamping device for the experiment of heat transfer by convection in fracture according to claim 1, characterized in that, The outer wall of the first integrated block and the second integrated block is provided with a gasket.

4. The rock slab clamping device for the experiment of heat transfer by convection in fracture according to claim 1, characterized in that, The steps include:

5. The method of using a rock slab holder for in-fracture convection heat transfer experiment according to any one of claims 1-4, characterized in that, S1, open the first movable cover and the second movable cover, and fill two rock plates of the same size into the first movable cover and the second movable cover respectively; S2, the simulated fracture is formed by the two rock plates, and the position of the two rock plates is adjusted to adjust the height of the simulated fracture; S3, close the first movable cover and the second movable cover, and fill water or gas into the plurality of rubber sleeves through the plurality of confining interfaces to apply confining pressure, so that the plurality of rubber sleeves are in interference fit with the two rock plates; S4, turn on the two electric heating plates and adjust to the set temperature, then pump a constant flow of fluid from the liquid inlet after the temperature is stable, and record the temperature when the fluid flows in and the temperature when the fluid flows out; S5, calculate the convective heat transfer coefficient of the fluid flowing and heat transfer in the simulated fracture according to the recorded data; The height adjustment range of the simulated fracture is 0-5mm, and the length and width of the simulated fracture are 50x100mm respectively. The calculation formula in step S5 is shown in formula (1).

6. The method of claim 5, wherein the method further comprises: ​ Formula (1); wherein, is the convective heat transfer coefficient, W / (m 2 ⋅K); is the specific heat of the fluid, J / (kg⋅K); is the fluid flow rate, m 3 / s; is the fluid density, kg / m 3 ; and are the fluid inlet and outlet temperatures, K, respectively; D is the height of the rock plate, m; L is the length of the rock plate, m; is the temperature of the outer surface of the rock plate, i.e., the temperature of the electric heating plate, K.

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