A physical model test device and method for photovoltaic-geothermal energy storage system

Abstract

A physical model test device and method for a photovoltaic-geothermal energy storage system, belonging to the technical field of laboratory simulation devices, includes a liquid storage tank, a high-pressure injection system, a fluid heating system, a core clamping system, a core constant temperature system, a confining pressure system, a liquid recovery system, an acoustic emission monitoring system, a temperature and pressure monitoring system, a permeability coefficient testing system, and a pipeline connection system. The present invention can carry out the process of circulating high-temperature and high-pressure fluid into rocks to induce rock fracture and seepage heat transfer to simulate the actual workflow of storing photovoltaic-heated fluid in geothermal energy storage formations. By conducting experiments on high-temperature and high-pressure fluid injection into rocks under different injection and production strategies, the dynamic evolution characteristics of the temperature field in the rock and the changing mechanism of thermal damage to the reservoir surrounding rock under different injection and production strategies can be clarified, providing corresponding technical theoretical support for maximizing the energy storage efficiency of the photovoltaic-geothermal energy storage system.

Description

Technical Field

[0001] The present invention belongs to the technical field of laboratory simulation devices, and in particular relates to a physical model test device and method for a photovoltaic-geothermal energy storage system. Background Art

[0002] Energy is a crucial foundation for economic development and social stability. With rising global prosperity and production, energy demand is expanding. Due to the limitations of traditional fossil fuels, such as limited reserves and severe pollution, and the dual challenges of growing energy demand and reducing carbon emissions, countries around the world are focusing on the development and utilization of clean, renewable energy. In this environment, my country urgently needs to rapidly advance its clean, low-carbon energy transition through energy restructuring and the construction of a new power system. The development and utilization of renewable energy sources such as solar, hydro, wind, and geothermal energy will continue to grow.

[0003] The combination of photovoltaic power generation and energy storage systems can be a cheaper alternative to coal-fired power generation and an option that is more compatible with the power grid. Geothermal energy storage has the advantages of large scale, low cost, wide application, and cross-seasonal use, providing a unique way to store photovoltaic power generation. The photovoltaic-geothermal energy storage system uses solar radiation to heat fluid, which is then injected into sedimentary formations for storage, forming a high-temperature geothermal reservoir for geothermal power generation, heating, and other cascade utilization. While solving the power supply imbalance problem caused by the intermittent nature of solar energy, this system compensates for geothermal gradients, enhances the potential for geothermal power generation, and accelerates the construction of photovoltaic-geothermal energy storage systems. This system can not only meet all-weather energy needs, but also maintain the stability and reliability of the power grid after integration into the grid.

[0004] When solar-heated fluid is injected into a geothermal reservoir, the surrounding rock in the injection channel will be damaged and fractured by the mass and heat transfer of the high-temperature fluid. Currently, research on photovoltaic-geothermal energy storage systems is in its initial stages of exploration, and many processes, such as well pattern layout and injection-production techniques, are still immature. Simulating the operation of photovoltaic-geothermal energy storage systems in the laboratory is of guiding significance for practical engineering, so indoor simulation of the cyclic injection and production of high-temperature fluids in geothermal reservoirs is essential. Current indoor physical model experiments investigating rock thermal damage and fracture often directly heat the rock, inject low-temperature fluids into the rock, and monitor the temperature changes at the fluid outlet. These experiments are unable to accurately simulate the rock damage and fracture process in a geothermal reservoir at a constant temperature due to the injection of high-temperature fluids. Furthermore, current indoor experimental methods and approaches cannot accurately monitor the evolution of surrounding rock damage and fracture in photovoltaic-geothermal energy storage systems, making it impossible to analyze the impact of rock thermal damage and fracture on photovoltaic-geothermal energy storage efficiency when solar thermal fluids are injected into geothermal energy storage systems. Summary of the Invention

[0005] The technical problem to be solved by this invention is to provide a physical model test apparatus and method for a photovoltaic-geothermal energy storage system to simulate the high-temperature, high-pressure fluid circulation injection and production process, as well as the high-temperature fluid seepage heat transfer process. This test apparatus and method provide guidance for analyzing the thermal damage behavior of surrounding rocks during the operation of photovoltaic-geothermal reservoir systems, analyze the impact of different injection and production factors on energy storage efficiency, and provide scientific and engineering guidance for the layout of various production conditions in actual photovoltaic-geothermal energy storage systems.

[0006] A physical model test device for a photovoltaic-geothermal energy storage system, comprising a liquid storage tank, a high-pressure injection system, a fluid heating system, a core clamping system, a core constant temperature system, a confining pressure system, a liquid recovery system, an acoustic emission monitoring system, a temperature and pressure monitoring system, a permeability coefficient testing system, and a pipeline connection system;

[0007] The liquid storage tank is connected to a high-pressure injection system, which includes a pump I, a pump II, and a controller, and injects fluid into the rock sample according to a set injection flow rate or injection pressure;

[0008] The fluid heating system includes two groups of pressure stabilizing tanks, and a heating device is provided on the outside of each group of pressure stabilizing tanks. One end of the pressure stabilizing tank is connected to the high-pressure injection system, and the other end is connected to the core clamping system.

[0009] The core clamping system is arranged inside the core constant temperature system. The core clamping system is a cylindrical barrel structure with a high-temperature and high-pressure rubber sleeve arranged inside. The rock sample is arranged inside the high-temperature and high-pressure rubber sleeve. The inlet end of the core clamping system is connected to the pressure regulating tank, and the outlet end is connected to the back pressure valve I. The back pressure valve I is used to maintain pressure in the fluid experiment to prevent fluid liquefaction.

[0010] The acoustic emission monitoring system includes one or more acoustic emission probes, which are respectively arranged at both ends and around the rock sample;

[0011] The temperature and pressure monitoring system includes one or more temperature probes and pressure sensors. The temperature probes are respectively arranged at both ends and around the rock sample; the pressure sensors are arranged at both ends of the rock sample;

[0012] The permeability coefficient testing system includes two flow meters, which are respectively arranged at the inlet and outlet ends of the core clamping system;

[0013] The confining pressure system uses a confining pressure pump, one end of which is connected to a liquid storage tank, and the other end is connected to a core clamping system. The confining pressure pump injects liquid between the high-temperature and high-pressure rubber sleeve and the cylindrical barrel to wrap the rock sample and uniformly apply confining pressure to the rock sample;

[0014] The liquid recovery system is equipped with a refrigeration unit containing a coil, a temperature probe at the rear end of the coil, and a pressure sensor at the front end. A connecting valve at the rear of back-pressure valve II connects to the liquid storage tank, with the connection located at the top of the tank. The liquid recovery system provides a low-temperature environment to cool the high-temperature, high-pressure liquid flowing through back-pressure valve I.

[0015] It also includes a data acquisition system for collecting data from acoustic emission probes, temperature probes, pressure sensors and flow meters.

[0016] The reference heat storage temperature of the fluid heating system is 200°C.

[0017] A photovoltaic-geothermal energy storage system physical model test method, using the photovoltaic-geothermal energy storage system physical model test device, includes the following steps:

[0018] Step 1: Cut the sandstone used for the experiment and place it as a rock sample in a high-temperature and high-pressure rubber sleeve. Place the high-temperature and high-pressure rubber sleeve inside the cylindrical barrel of the core clamping system. Pass the temperature probe and acoustic emission probe through the reserved holes of the cylindrical barrel and the high-temperature and high-pressure rubber sleeve to contact the rock sample. Seal the reserved holes to close the test pipeline.

[0019] Step 2: Turn on the refrigeration switch of the liquid recovery system and set the refrigeration temperature; turn on the injection pump and valve I. When the refrigeration device is filled with distilled water, close valve I and the injection pump; open the valve of the confining pressure system, start the confining pressure pump, inject the distilled water in the liquid storage tank into the core clamping system, wrap the high-temperature and high-pressure rubber sleeve, and apply confining pressure to the rock sample; turn on the heating device of the core constant temperature system to increase the temperature;

[0020] Step 3: Inject distilled water into the pressure-surge tank, heat the distilled water, and maintain a constant pressure during the heating process so that the distilled water remains in a liquid phase; set the pressure of back-pressure valve I; open the injection pump and valve II of the liquid recovery system, and set the pressure of back-pressure valve II to a value lower than the pressure of back-pressure valve I; input the distilled water into the coil of the liquid return system, and when the pressure sensor in the refrigeration unit indicates a value slightly lower than the pressure of back-pressure valve II, close the injection pump and valve II;

[0021] Step 4: Inject distilled water heated to the set temperature into the rock sample. Stop the injection after the pressure sensor reading near the outlet stabilizes. Allow the high-temperature distilled water to remain in the rock sample for a period of time. During this process, the temperature probe, pressure sensor, and acoustic emission probe in the core clamping system transmit data to the data acquisition system in real time.

[0022] Step 5: After the interval reaches the set value, simultaneously lower the set pressures of back-pressure valves I and II until the pressure set on back-pressure valve I is lower than the reading on the outlet pressure sensor. The high-temperature, high-pressure fluid in the core holder will flow through back-pressure valve I into the liquid recovery system. When the temperature probe reading falls below 100°C, open the valve connecting the liquid recovery system to the liquid storage tank to cool and reduce the pressure of the high-temperature, high-pressure fluid flowing through the liquid recovery system, facilitating water recycling. After the distilled water in the entire experimental setup has been drained, remove the rock sample and conduct dynamic behavior characterization tests under the next experimental conditions.

[0023] Step 6. During the experiment, the fracture process of the rock sample during the injection of high-temperature fluid is observed through acoustic emission data, and the evolution of the temperature field in the rock sample is monitored through temperature data. The rock fracture, temperature field evolution, and heat storage efficiency under different injection schemes are obtained, as well as the rock fracture mechanism and temperature field evolution law during the injection of high-temperature fluid.

[0024] Through the above-mentioned design scheme, the present invention can bring the following beneficial effects: a physical model test device and method of a photovoltaic-geothermal energy storage system of the present invention can carry out the process of circulating high-temperature and high-pressure fluid into rocks to induce rock fracture and seepage heat transfer to simulate the actual workflow of storing photovoltaic-heated fluid in geothermal energy storage formations. By carrying out experiments on injecting high-temperature and high-pressure fluid into rocks under different injection and production strategies, the dynamic evolution characteristics of the temperature field in the rock and the change mechanism of thermal damage to the reservoir surrounding rock under different injection and production strategies can be clarified, thereby providing corresponding technical theoretical support for maximizing the energy storage efficiency of the photovoltaic-geothermal energy storage system.

[0025] The acoustic emission monitoring system in this test device can monitor the initiation and expansion of cracks in rocks in real time during the injection of high-temperature fluid.

[0026] The temperature monitoring system in this experimental device can monitor the fluid temperature at the rock inlet and outlet as well as the temperature at different locations around the rock in real time to characterize the evolution law of the rock and fluid temperature field.

[0027] The pressure monitoring system in this test device can monitor the changes in fluid pressure at the rock inlet and outlet in real time to determine changes in rock permeability characteristics.

[0028] The liquid recovery device in this experimental device can quickly cool the high-temperature and high-pressure fluid to ensure the recycling of the liquid and the safe and efficient conduct of the experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0030] Figure 1This is a structural schematic diagram of a physical model test device for a photovoltaic-geothermal energy storage system according to the present invention.

[0031] Figure 2 This is a structural schematic diagram of the core clamping system of a physical model test device for a photovoltaic-geothermal energy storage system of the present invention.

[0032] Figure 3 This is a structural schematic diagram of the liquid recovery system of a physical model test device for a photovoltaic-geothermal energy storage system of the present invention.

[0033] In the figure, 1-liquid storage tank, 2-pump I, 3-pump II, 4-pressure stabilizing tank, 5-heating device, 6-core clamping system, 6-A-inlet end, 6-B-outlet end, 6-C-high temperature and high pressure rubber sleeve, 6-D-rock sample, 7-core constant temperature system, 8-confining pressure system, A-back pressure valve I, 9-liquid recovery system, 9-1-coil, 9-2-refrigeration device, 9-3-temperature probe, 9-4-pressure sensor, 9-5-connecting valve, B-back pressure valve II, 9-6-injection pump, 9-7-valve I, 9-8-valve II. DETAILED DESCRIPTION

[0034] A physical model test device for a photovoltaic-geothermal energy storage system comprises a liquid storage tank 1, a high-pressure injection system, a fluid heating system, a core clamping system 6, a core constant temperature system 7, a confining pressure system 8, a back pressure valve IA, a liquid recovery system 9, an acoustic emission monitoring system, a temperature and pressure monitoring system, a permeability coefficient testing system, a data acquisition system, and a pipeline connection system.

[0035] The high-pressure injection system consists of two groups of pumps, namely pump I2 and pump II3, and a controller. It has a constant speed working mode and a constant pressure working mode to choose from. Fluid can be injected into the rock sample according to the set injection flow rate or injection pressure. The two pumps can alternately provide fluid to avoid interruption of fluid injection during the test.

[0036] The fluid heating system, used to generate high-temperature fluid, consists of two sets of high-temperature and high-pressure resistant surge tanks 4 and a heating device 5. One end of the heating device 5 and surge tank 4 is connected to the high-pressure injection system, and the other end is connected to the core clamping system 6. Normal-temperature fluid is injected into the surge tanks 4 via the high-pressure injection system. After being heated to the set temperature by the fluid heating system, it is injected into the rock sample 6-D. The design of the two sets of surge tanks 4 ensures that the fluid maintains a stable, high temperature when injected into the rock sample 6-D.

[0037] Furthermore, the heating system can heat the fluid in the liquid storage tank 1 to 200°C, and the photovoltaic power generation device can heat the water to 400°C or even higher. However, in order to minimize potential operational problems and reduce costs, 200°C is selected as the benchmark heat storage temperature in the geothermal energy storage system.

[0038] Furthermore, the liquid storage tank 1 is provided with a high-precision pressure and temperature probe to monitor the pressure and temperature of the fluid in the liquid storage tank 1 .

[0039] The core clamping system 6 consists of a cylindrical barrel and a high-temperature and high-pressure resistant rubber sleeve 6-C. The rock sample 6-D is placed in the rubber sleeve, and cylindrical pads are placed on both sides and placed together in the cylindrical barrel. The rock sample 6-D is fixed on both sides of the cylindrical barrel using fixing devices. The inlet end 6-A of the core clamping system 6 is connected to the pressure-regulating tank 4, and the outlet end 6-B is connected to the back-pressure valve IA.

[0040] The back pressure valve IA is set to ensure that the fluid is always maintained above a certain pressure during the test. Since the fluid involves a high temperature during the test, in order to ensure that the liquid is not vaporized, the fluid pressure needs to be maintained above a certain value.

[0041] In order to restore the photovoltaic-geothermal energy storage system to the greatest extent, the temperature of the surrounding rock around the reservoir is adjusted, which mainly relies on the core constant temperature system 7: the core clamping system 7 is placed in a constant temperature box, and the constant temperature box can maintain the ambient temperature at the value required by the project through a heating device.

[0042] The acoustic emission monitoring system consists of nine acoustic emission probes, two of which are arranged at the inlet end 6-A and the outlet end 6-B of the core clamping system 6, and five acoustic emission probes are arranged around the rock sample to monitor the crack initiation and propagation process induced by the high-temperature fluid flowing through the rock sample.

[0043] The temperature and pressure monitoring system consists of temperature probes and pressure sensors. Five temperature probes are arranged around the rock sample 6-D to measure the temperature of the rock sample 6-D at different positions. One temperature probe and one pressure sensor are arranged at the inlet end 6-A and the outlet end 6-B respectively to measure the temperature and pressure of the fluid at the inlet and outlet.

[0044] The permeability coefficient testing system is made up of two flow meters, which are respectively arranged at the inlet end 6-A and the outlet end 6-B of the core clamping system 6 to measure the flow rate at the inlet and outlet of the fluid.

[0045] The confining pressure system 8 consists of a confining pressure pump and a liquid storage tank 1. One end of the confining pressure pump is connected to the liquid storage tank 1, and the other end is connected to the core clamping system. The confining pressure pump uniformly applies confining pressure to the rock sample by injecting liquid between the rubber sleeve and the cylindrical barrel to wrap the rock sample. The applied confining pressure is reduced by pumping the liquid back into the liquid storage tank 1. The automatic servo system can automatically adjust the confining pressure to maintain a constant value during the test.

[0046] The liquid recovery system 9 consists of a coil 9-1, a refrigeration unit 9-2, a temperature probe 9-3, a pressure sensor 9-4, a back-pressure valve IIB, a connecting valve 9-5, an injection pump 9-6, valve I 9-7, and valve II 9-8. Coil 9-1 consists of a certain length of pipeline and is placed within refrigeration unit 9-2. The injection pump 9-6 in the liquid recovery system 9 is connected to the liquid storage tank 1. Refrigeration unit 9-2 is used to provide a low-temperature liquid (between 0°C and 5°C) to quickly cool the high-temperature, high-pressure liquid flowing through back-pressure valve IA. A temperature probe 9-3 is installed at the end of coil 9-1. Back-pressure valve IIB is used to control the temperature of the liquid flowing into the liquid storage tank. When the temperature drops below 100°C, connecting valve 9-5 is opened to ensure the safe recovery of the liquid into liquid storage tank 1.

[0047] The data acquisition system is composed of a data line and a computer, and can automatically collect data from the acoustic emission probe, temperature probe, pressure sensor and water flow rate, and transmit it to the computer at intervals as needed for recording.

[0048] A physical model test method for a photovoltaic-geothermal energy storage system is as follows:

[0049] The sandstone obtained from the on-site system is cut into samples that meet the test size requirements and placed in the high-temperature and high-pressure rubber sleeve 6-C. The high-temperature and high-pressure rubber sleeve 6-C is placed in the core clamping system 6. The temperature probe and the acoustic emission probe are passed through the small circular holes reserved on the core clamping system 6 and the high-temperature and high-pressure rubber sleeve 6-C to contact the rock sample 6-D. The circular holes on the core clamping system 6 are sealed with screw buckles and rubber rings to check the tightness of the entire test pipeline.

[0050] Turn on the refrigeration switch in the liquid recovery system 9 and set the refrigeration temperature to 3°C.

[0051] Open the valve of the confining pressure system 8, set the target confining pressure (higher than the boiling point corresponding to the water temperature), start the confining pressure pump, inject the distilled water in the liquid storage tank 1 into the core clamping system 6, wrap the high-temperature and high-pressure rubber sleeve 6-C to apply confining pressure to the rock sample 6-D, set the target temperature of the constant temperature box to 60°C, turn on the heating device of the core constant temperature system 7 to start heating, and during the heating process of the constant temperature box, adjust the liquid volume in the core clamp and the rubber sleeve through the confining pressure system 8 to maintain a constant confining pressure.

[0052] According to the experimental plan, distilled water was injected into two surge tanks 4 at a predetermined flow rate via pumps I2 and II3. The target temperature in surge tanks 4 was set to 200°C (the corresponding boiling point of distilled water is 6.25 MPa). Heating device 5 was turned on to heat the distilled water in surge tanks 4. The pressure in surge tanks 4 was maintained above 12 MPa to ensure that the distilled water remained in the liquid phase during the heating process.

[0053] After the fluid in pressure-surge tank 4 reaches the target temperature, the pressure of back-pressure valve IA is aligned with the pressure set by the confining pressure system to ensure that the distilled water remains liquid throughout the test. Simultaneously, the pressure of back-pressure valve IIB is set slightly lower than that of back-pressure valve IA but higher than atmospheric pressure. Injection pump 9-6 and valve I 9-7 in liquid recovery system 9 are opened to inject distilled water into refrigeration unit 9-2. Once the refrigeration unit is filled with distilled water, valve II 9-8 is opened, valve I 9-7 is closed, and distilled water is injected into coil 9-1. When the reading of pressure sensor 9-4 in the refrigeration unit is slightly lower than that of back-pressure valve IA, injection pump 9-6 and valve II 9-8 are closed.

[0054] 200°C distilled water is injected into rock sample 6-D at a set injection rate. During the injection process, the temperature probe, pressure sensor, and acoustic emission probe transmit data to the computer in real time. Once the pressure sensor reading near outlet 6-B stabilizes, injection is stopped. The high-temperature distilled water is allowed to remain in the rock sample for a period of time. After the interval reaches the set value, the settings of back-pressure valves IA and IIB are slowly and gradually lowered until they are below the pressure sensor reading at outlet 6-B. When the reading of temperature probe 9-3 falls below 100°C, valve 9-5 in the liquid recovery system 9, connected to liquid storage tank 1, is opened to collect the distilled water into the storage tank.

[0055] Replace the new rock sample, inject 200℃ distilled water into the rock sample again according to the test target injection flow rate, and carry out the next set of tests.

[0056] According to the above steps, design injection plans with different injection times, different injection flow rates, different injection temperatures, and different interval time conditions, implement high-temperature fluid injection, and record the monitoring data of the acoustic emission probe, temperature probe, pressure probe, and flow meter.

[0057] The fracture process of rock samples during high-temperature fluid injection is observed through acoustic emission data, and the evolution of the temperature field in the rock samples is monitored through temperature data. The differences in rock fracture, temperature field evolution and heat storage efficiency under different injection schemes are compared, and the rock fracture mechanism and temperature field evolution law during high-temperature fluid injection are explained. The influence of injection times, injection temperature, injection flow rate, interval time, etc. on heat storage efficiency is revealed, and the photovoltaic-geothermal energy storage efficiency injection scheme is optimized.

Claims

1. A physical model test device for a photovoltaic-geothermal energy storage system, characterized by: It includes a liquid storage tank (1), a high-pressure injection system, a fluid heating system, a core clamping system (6), a core constant temperature system (7), a confining pressure system (8), a liquid recovery system (9), an acoustic emission monitoring system, a temperature and pressure monitoring system, a permeability coefficient testing system, and a pipeline connection system; The liquid storage tank (1) is connected to a high-pressure injection system, which includes a pump I (2), a pump II (3) and a controller, and injects fluid into the rock sample according to a set injection flow rate or injection pressure; The fluid heating system comprises two groups of pressure stabilizing tanks (4), and a heating device (5) is provided on the outside of each group of pressure stabilizing tanks (4). One end of the pressure stabilizing tank (4) is connected to the high-pressure injection system, and the other end is connected to the core clamping system (6). The core clamping system (6) is arranged inside the core constant temperature system (7). The core clamping system (6) is a cylindrical barrel structure, and a high-temperature and high-pressure rubber sleeve (6-C) is arranged inside. The rock sample (6-D) is arranged inside the high-temperature and high-pressure rubber sleeve (6-C). The inlet end (6-A) of the core clamping system (6) is connected to the pressure regulating tank (4), and the outlet end (6-B) is connected to the back pressure valve (9). The back pressure valve (9) is used to maintain pressure in fluid experiments to prevent fluid liquefaction. The acoustic emission monitoring system includes one or more acoustic emission probes, which are respectively arranged at both ends and around the rock sample (6-D); The temperature and pressure monitoring system includes one or more temperature probes and pressure sensors, wherein the temperature probes are respectively arranged at both ends and around the rock sample (6-D); the pressure sensors are arranged at both ends of the rock sample (6-D); The permeability coefficient testing system includes two flow meters, which are respectively arranged at the inlet end (6-A) and the outlet end (6-B) of the core clamping system (6); The confining pressure system (8) uses a confining pressure pump, one end of which is connected to the liquid storage tank (1), and the other end is connected to the core clamping system (6). The confining pressure pump injects liquid between the high-temperature and high-pressure rubber sleeve (6-C) and the cylindrical barrel to wrap the rock sample (6-D) and uniformly apply confining pressure to the rock sample; The liquid recovery system (9) is provided with a refrigeration device, a coil (9-1) is provided inside the refrigeration device, and a temperature probe (9-3) is provided at the tail end of the coil (9-1); a pressure sensor (9-4) is provided at the head end; a valve (9-5) is connected to the tail end of the back pressure valve II (B) and is connected to the liquid storage tank (1), and the interface is located at the upper end of the liquid storage tank (1); the liquid recovery system (9) is used to provide a low-temperature environment to cool the high-temperature and high-pressure liquid flowing through the back pressure valve I (A).

2. A photovoltaic-geothermal energy storage system physical model test device according to claim 1, characterized in that: It also includes a data acquisition system for collecting and storing data from acoustic emission probes, temperature probes, pressure sensors, flow meters and temperature sensors.

3. A photovoltaic-geothermal energy storage system physical model test device according to claim 1, characterized in that: The reference heat storage temperature of the fluid heating system is 200°C.

4. A physical model test method for a photovoltaic-geothermal energy storage system, characterized by: The photovoltaic-geothermal energy storage system physical model test device according to claim 1 includes the following steps: Step 1: Cut the sandstone used for the experiment as a rock sample (6-D) and place it in a high-temperature and high-pressure rubber sleeve (6-C). Place the high-temperature and high-pressure rubber sleeve (6-C) inside the cylindrical barrel of the core clamping system (6). Pass the temperature probe and the acoustic emission probe through the reserved holes of the cylindrical barrel and the high-temperature and high-pressure rubber sleeve (6-C) to contact the rock sample (6-D). Seal the reserved holes to close the test pipeline. Step 2: Turn on the refrigeration switch of the liquid recovery system (9) and set the refrigeration temperature; turn on the injection pump (9-6) and valve I (9-7), and when the interior of the refrigeration device is filled with distilled water, close the valve (9-7) and the injection pump (9-6); open the valve of the confining pressure system (8), start the confining pressure pump, inject the distilled water in the liquid storage tank (1) into the core clamping system (6), wrap the high-temperature and high-pressure rubber sleeve (6-C), and apply confining pressure to the rock sample; turn on the heating device of the core constant temperature system (7) to increase the temperature; Step 3: inject distilled water into the pressure stabilizing tank (4), heat the distilled water, and maintain a constant pressure during the heating process so that the distilled water maintains a liquid phase; set the pressure of the back pressure valve I (A); open the injection pump (9-6) and valve II (9-8) of the liquid recovery system (9), set the pressure of the back pressure valve II (B), and set the pressure value to be lower than the pressure of the back pressure valve I (A); input the distilled water into the coil (9-1) of the liquid return system (9), and when the pressure sensor (9-4) in the refrigeration device (9-2) indicates a value slightly lower than the pressure of the back pressure valve II (B), close the injection pump (9-6) and valve II (9-8); Step 4: inject distilled water heated to a set temperature into the rock sample (6-D). After the pressure sensor reading near the outlet end (6-B) stabilizes, stop injecting and allow the high-temperature distilled water to be stored in the rock sample for a period of time. During the storage process, the temperature probe, pressure sensor, and acoustic emission probe in the core clamping system (6) transmit data to the data acquisition system in real time. Step 5: After the interval time reaches the set value, the set pressures of the back pressure valve I (A) and the back pressure valve II B () are reduced synchronously, so that the pressure set by the back pressure valve I (A) is lower than the reading of the pressure sensor at the outlet end (6-B); the high-temperature and high-pressure fluid in the core clamping system will flow into the liquid recovery system through the back pressure valve I (A); when the reading of the temperature probe (9-3) is lower than 100°C, the connecting valve (9-5) between the liquid recovery system (9) and the liquid storage tank (1) is opened to reduce the temperature and pressure of the high-temperature and high-pressure liquid flowing through the liquid recovery system (9) and recycle water resources; after the distilled water in the entire experimental device is discharged, the rock sample (6-D) is taken out, and the dynamic behavior characteristic test of the rock sample under the next test conditions is carried out; Step 6. During the test, the fracture process of the rock sample (6-D) during the injection of high-temperature fluid is observed through acoustic emission data, and the evolution of the temperature field in the rock sample is monitored through temperature data. The rock fracture, temperature field evolution, and heat storage efficiency under different injection schemes are obtained, as well as the rock fracture mechanism and temperature field evolution law during the injection of high-temperature fluid.

Images