Rock complex dielectric constant testing device for high temperature and high pressure environment and testing method thereof

Abstract

The application discloses a device for testing complex dielectric constant of rock under high temperature and high pressure, which comprises a test table, a rock sample is placed on the test table, a confining pressure loading system is arranged on the test table and used for applying confining pressure to the rock sample, the confining pressure loading system is connected with a temperature heating system through a wire, and the temperature heating system is used for heating the rock sample, and the device further comprises a complex dielectric constant testing system used for testing dielectric properties of the rock sample. The device can realize the complex dielectric constant testing under the condition of temperature field and pressure field cooperation. The application further discloses a testing method for complex dielectric constant of rock under high temperature and high pressure based on a terminal short circuit method.

Description

Technical Field

[0001] This invention belongs to the technical field of rock complex permittivity testing in deep drilling engineering, and relates to a testing device for the complex permittivity of rocks under high temperature and high pressure. This invention also relates to a testing method for the complex permittivity of rocks under high temperature and high pressure. Background Technology

[0002] The complex permittivity of rocks is one of the core parameters characterizing their electromagnetic radiation properties, and its value is closely related to the rock's mineral composition, internal microstructure, and geological environment. In fields such as oil and gas exploration and development, geothermal resource assessment, and prediction of deep geological hazards, the complex permittivity of rocks is an important basis for rock and mineral identification and geological condition analysis. Rocks in deep, complex strata are typically subjected to high-temperature (above 300℃) and high-pressure (above 120MPa) geological conditions. This environment significantly alters the internal structure of the rocks, leading to changes in their complex permittivity. Therefore, the complex permittivity of rocks obtained only under normal temperature and pressure conditions deviates significantly from the parameters in actual deep-earth environments, failing to meet the technical requirements for accurate exploration and development.

[0003] Existing devices and methods for testing the complex permittivity of rocks have the following shortcomings: First, the testing devices are disconnected from actual geological conditions. Most testing devices can only perform tests under high temperature or high pressure, making it difficult to accurately simulate complex deep-earth environments. Second, the testing accuracy is low. Inappropriate design of the high-pressure sealing structure can easily lead to pressure leakage, and electromagnetic interference in high-temperature environments is not effectively shielded, all of which affect the accuracy of the test data.

[0004] To address the aforementioned issues, there is an urgent need to develop a high-temperature, high-pressure complex permittivity testing device for rocks that can accurately simulate complex deep-earth environments and achieve high testing precision, and to provide a set of methods for testing the complex permittivity of rocks under high-temperature and high-pressure conditions. Summary of the Invention

[0005] The purpose of this invention is to provide a testing device for the complex permittivity of rocks under high temperature and high pressure, which can realize the testing of complex permittivity under the combined conditions of temperature and pressure fields.

[0006] Another object of the present invention is to provide a method for testing the complex permittivity of rocks under high temperature and high pressure.

[0007] The technical solution adopted in this invention is a testing device for the complex dielectric constant of rocks under high temperature and high pressure, including a test bench on which a rock sample is placed. A confining pressure loading system is provided on the test bench to apply confining pressure to the rock sample. The confining pressure loading system is connected to a temperature heating system via wires. The temperature heating system is used to heat the rock sample. The device also includes a complex dielectric constant testing system for testing the dielectric properties of the rock sample.

[0008] Preferably, the test bench includes a metal support, on which a rectangular metal test box is fixedly mounted, and the confining pressure loading system is mounted on the metal test box.

[0009] Preferably, the confining pressure loading system includes a hydraulic press installed in the middle of the outer side of three adjacent and non-corresponding side walls of the metal experimental box. The pressure head of the hydraulic press extends into the metal experimental box through the corresponding side wall and is connected to a force transmission plate. A reaction plate is symmetrically arranged on the side wall of the metal experimental box corresponding to the force transmission plate. The hydraulic press is connected to a PC-end pressure control system via an electric wire.

[0010] Preferably, the inner wall of the metal experimental box is further provided with a heat insulation material layer, and the reaction plate is set on the corresponding heat insulation material layer of the inner wall.

[0011] Preferably, the temperature heating system includes a metal plate embedded in the middle of the side of the reaction plate near the inside of the metal test box, and an electromagnetic heating coil is embedded in the side of the metal plate near the inside of the metal test box. The electromagnetic heating coil passes through the metal test box with a wire and is connected to a PC-based temperature control system.

[0012] Preferably, it also includes a pressure monitoring system, which includes a high-temperature strain gauge. The high-temperature strain gauge is attached to the side of the force transmission plate near the inside of the metal test box. The high-temperature strain gauge is connected to the PC-side pressure detection display via a wire passing through the metal test box.

[0013] It also includes a temperature monitoring system, which consists of a thermal resistor attached to the side of the reaction plate near the inside of the metal experimental box. The thermal resistor is connected to a temperature display on a PC via wires that pass through the metal experimental box.

[0014] Preferably, a displacement sensor and a pressure sensor are also provided on the side of the force transmission plate near the inside of the metal experimental box, and a temperature sensor is also provided on the side of the reaction plate near the inside of the metal experimental box.

[0015] Preferably, the complex permittivity testing system includes a vector network analyzer, which is connected to a coaxial adapter via a coaxial cable. The other end of the coaxial adapter is connected to a rectangular waveguide port, and the other end of the rectangular waveguide port is attached to the outer wall of the metal experimental box, and is attached to the outer wall of the metal experimental box where a force transmission plate is correspondingly provided. The force transmission plate on the side corresponding to the rectangular waveguide port is made of a wave-transparent material with high compressive strength.

[0016] The second technical solution adopted in this invention is a test method for the complex permittivity of rocks under high temperature and high pressure based on the terminal short-circuit method. After the rock sample is processed into the corresponding shape and size, it is placed in a metal test box. The force transmission plate is adjusted by a hydraulic press so that the rock sample is in contact with the force transmission plate and the reaction plate. The heating rate of the electromagnetic heating coil is adjusted by a PC-based temperature control system. After the rock sample temperature reaches the target temperature, the pressure is transmitted to the rock sample by the hydraulic press. After the temperature and pressure parameters of the rock sample stabilize, the vector network analyzer is started to measure the reflection coefficient of the rock sample, and the complex permittivity is calculated based on the reflection coefficient.

[0017] Preferably, during heating and pressurization, the target confining pressure and temperature are set in the PC-side pressure control system and the PC-side temperature control system. The rock sample is heated at a uniform rate by the electromagnetic heating coil. During the heating process, the temperature of the rock sample is monitored in real time by the thermal resistor. After the target temperature is reached, the heating is stopped and the electromagnetic heating coil is kept at the target temperature. After the temperature of the rock sample stabilizes, the pressure control system is activated to maintain a uniform pressurization rate. The pressure is transmitted to the force transmission plate through the hydraulic press. During the pressurization process, the pressure change is monitored synchronously by high-temperature strain gauges. Once the target pressure is reached, the pressurization is stopped and the target pressure is maintained. The complex permittivity of the rock sample under test was measured and calculated using a vector network analyzer. The specific steps are as follows: Step 1: Ensure the cross-sectional dimensions of the rock sample and the corresponding side of the rectangular waveguide are identical. Let the thickness of the rock sample be denoted as . d The rock sample and the antenna port of the rectangular waveguide were placed close together. Frequency sweep tests were performed through the rectangular waveguide within the target frequency range. The test was performed for 1-3 seconds at each frequency point, and the transmission coefficient was obtained by repeating the test 3 times and taking the average value. ; Step 2: Through transmission coefficients The complex permittivity of the rock sample to be tested was calculated as follows: The attenuation constant is obtained by using the conditional equation for the transmission coefficient, i.e., formula (2). and phase constant The complex permittivity of the rock sample to be tested can be obtained by formulas (3) and (4). and loss tangent : (2) (3) (4) In the formula: The cutoff wave number is calculated using formula (5); The free space wavenumber is calculated using formula (6); (5) (6) In the formula: The cutoff wavelength, , a To test the wide side dimension of the waveguide; For the wavelength in free space, , c For the speed of light in free space, To test the resonant frequency of the waveguide.

[0018] The beneficial effects of this invention are: This invention combines a confining pressure application system and a temperature heating system to achieve the testing of the complex dielectric constant of rocks under different confining pressures or at different temperatures. It can also achieve the testing of the complex dielectric constant of rocks under the synergistic effect of high temperature and high pressure, making the test environment closer to the actual deep-earth environment. It can realize the synchronous acquisition and recording of temperature, pressure and complex dielectric constant data, and solve the problem of testing the complex dielectric constant of rocks under high temperature and high pressure conditions. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the device for testing the complex permittivity of rocks under high temperature and high pressure according to the present invention; Figure 2 This is a front cross-sectional view of the testing device for the complex permittivity of rocks under high temperature and high pressure according to the present invention; Figure 3 This is a top cross-sectional view of the testing device for the complex permittivity of rocks under high temperature and high pressure according to the present invention; Figure 4 This is a perspective view of the device for testing the complex permittivity of rocks under high temperature and high pressure according to the present invention; Figure 5 This is a schematic diagram of the arrangement of the electromagnetic heating coil, metal plate and temperature sensor in the testing device for the complex dielectric constant of rocks under high temperature and high pressure according to the present invention. Figure 6 This is a diagram showing the arrangement of pressure and displacement sensors in the testing device for the complex permittivity of rocks under high temperature and pressure according to the present invention.

[0020] In the diagram: 1. Confining pressure loading system, 2. Temperature heating system, 3. Complex permittivity testing system, 4. PC-side pressure control system, 5. Pressure monitoring system, 6. PC-side temperature control system, 7. Temperature monitoring system, 8. Test bench, 8-1. Metal support, 8-2. Metal test box, 9. Rock sample, 10. Wire, 11. Hydraulic press, 12. Force transmission plate, 13. Reaction plate, 14. Electromagnetic heating coil, 15. Metal plate, 16. Thermal insulation layer, 17. High-temperature strain gauge, 18. Resistance temperature detector (RTD), 19. Vector network analyzer, 20. Coaxial cable, 21. Coaxial adapter, 22. Rectangular waveguide port, 23. Displacement sensor, 24. Pressure sensor, 25. Temperature sensor. Detailed Implementation

[0021] The following detailed description is provided in conjunction with specific implementation methods.

[0022] Example 1 This invention relates to a testing device for the complex permittivity of rocks under high temperature and pressure, the structure of which is as follows: Figure 1 As shown, the test bench includes a test bench 8 on which a rock sample 9 is placed. The test bench 8 is equipped with a confining pressure loading system 1 for applying confining pressure to the rock sample 9. The confining pressure loading system 1 is connected to a temperature heating system 2 via wires for heating the rock sample 9. The test bench also includes a complex dielectric constant testing system 3 for testing the dielectric properties of the rock sample 9.

[0023] like Figure 2 As shown, the test bench 8 includes a metal support 8-1, on which a rectangular metal test box 8-2 is fixedly mounted, and the confining pressure loading system 1 is mounted on the metal test box 8-2.

[0024] Example 2 This invention relates to a testing device for the complex permittivity of rocks under high temperature and pressure, the structure of which is as follows: Figure 1 As shown, the test bench includes a test bench 8 on which a rock sample 9 is placed. The test bench 8 is equipped with a confining pressure loading system 1 for applying confining pressure to the rock sample 9. The confining pressure loading system 1 is connected to a temperature heating system 2 via wires for heating the rock sample 9. The test bench also includes a complex dielectric constant testing system 3 for testing the dielectric properties of the rock sample 9.

[0025] like Figure 2 As shown, the test bench 8 includes a metal support 8-1, on which a rectangular metal test box 8-2 is fixedly mounted, and the confining pressure loading system 1 is mounted on the metal test box 8-2.

[0026] like Figures 2-4As shown, the confining pressure loading system 1 includes a hydraulic press 11 installed in the middle of the outer side of three adjacent and non-corresponding side walls of the metal test box 8-2. The pressure head of the hydraulic press 11 extends into the metal test box 8-2 through the corresponding side wall and is connected to a force transmission plate 12. A reaction plate 13 is symmetrically arranged on the side wall of the metal test box 8-2 corresponding to the force transmission plate 12. The hydraulic press 11 is connected to a PC-end pressure control system 4 through a wire 10.

[0027] Example 3 This invention relates to a testing device for the complex permittivity of rocks under high temperature and pressure, the structure of which is as follows: Figure 1 As shown, the test bench includes a test bench 8 on which a rock sample 9 is placed. The test bench 8 is equipped with a confining pressure loading system 1 for applying confining pressure to the rock sample 9. The confining pressure loading system 1 is connected to a temperature heating system 2 via wires for heating the rock sample 9. The test bench also includes a complex dielectric constant testing system 3 for testing the dielectric properties of the rock sample 9.

[0028] like Figure 2 As shown, the test bench 8 includes a metal support 8-1, on which a rectangular metal test box 8-2 is fixedly mounted, and the confining pressure loading system 1 is mounted on the metal test box 8-2.

[0029] like Figures 2-4 As shown, the confining pressure loading system 1 includes a hydraulic press 11 installed in the middle of the outer side of three adjacent and non-corresponding side walls of the metal test box 8-2. The pressure head of the hydraulic press 11 extends into the metal test box 8-2 through the corresponding side wall and is connected to a force transmission plate 12. A reaction plate 13 is symmetrically arranged on the side wall of the metal test box 8-2 corresponding to the force transmission plate 12. The hydraulic press 11 is connected to a PC-end pressure control system 4 through a wire 10.

[0030] The temperature heating system 2 includes a metal plate 15 embedded in the middle of the side of the reaction plate 13 near the inside of the metal experimental box 8-2. An electromagnetic heating coil 14 is embedded in the side of the metal plate 15 near the inside of the metal experimental box 8-2. The electromagnetic heating coil 14 passes through the metal experimental box 8-2 through a wire and is connected to the PC-end temperature control system 6.

[0031] Example 4 This invention relates to a testing device for the complex permittivity of rocks under high temperature and pressure, the structure of which is as follows: Figure 1As shown, the test bench includes a test bench 8 on which a rock sample 9 is placed. The test bench 8 is equipped with a confining pressure loading system 1 for applying confining pressure to the rock sample 9. The confining pressure loading system 1 is connected to a temperature heating system 2 via wires for heating the rock sample 9. The test bench also includes a complex dielectric constant testing system 3 for testing the dielectric properties of the rock sample 9.

[0032] like Figure 2 As shown, the test bench 8 includes a metal support 8-1, on which a rectangular metal test box 8-2 is fixedly mounted, and the confining pressure loading system 1 is mounted on the metal test box 8-2.

[0033] like Figures 2-4 As shown, the confining pressure loading system 1 includes a hydraulic press 11 installed in the middle of the outer side of three adjacent and non-corresponding side walls of the metal test box 8-2. The pressure head of the hydraulic press 11 extends into the metal test box 8-2 through the corresponding side wall and is connected to a force transmission plate 12. A reaction plate 13 is symmetrically arranged on the side wall of the metal test box 8-2 corresponding to the force transmission plate 12. The hydraulic press 11 is connected to a PC-end pressure control system 4 through a wire 10.

[0034] The temperature heating system 2 includes a metal plate 15 embedded in the middle of the side of the reaction plate 13 near the inside of the metal experimental box 8-2. An electromagnetic heating coil 14 is embedded in the side of the metal plate 15 near the inside of the metal experimental box 8-2. The electromagnetic heating coil 14 passes through the metal experimental box 8-2 through a wire and is connected to the PC-end temperature control system 6.

[0035] It also includes a pressure monitoring system 5, which includes a high-temperature strain gauge 17. The high-temperature strain gauge 17 is attached to the side of the force transmission plate 12 near the inside of the metal test box 8-2. The high-temperature strain gauge 17 is connected to the PC-side pressure detection display through a wire passing through the metal test box 8-2. It also includes a temperature monitoring system 6, which includes a thermal resistor 18 attached to the side of the reaction plate 13 near the inside of the metal experimental box 8-2. The thermal resistor 18 is connected to a PC-based temperature display via wires that pass through the metal experimental box 8-2.

[0036] Example 5 This invention relates to a testing device for the complex permittivity of rocks under high temperature and pressure, the structure of which is as follows: Figure 1 As shown, the test bench includes a test bench 8 on which a rock sample 9 is placed. The test bench 8 is equipped with a confining pressure loading system 1 for applying confining pressure to the rock sample 9. The confining pressure loading system 1 is connected to a temperature heating system 2 via wires for heating the rock sample 9. The test bench also includes a complex dielectric constant testing system 3 for testing the dielectric properties of the rock sample 9.

[0037] like Figure 2 As shown, the test bench 8 includes a metal support 8-1, on which a rectangular metal test box 8-2 is fixedly mounted, and the confining pressure loading system 1 is mounted on the metal test box 8-2.

[0038] like Figures 2-4 As shown, the confining pressure loading system 1 includes a hydraulic press 11 installed in the middle of the outer side of three adjacent and non-corresponding side walls of the metal test box 8-2. The pressure head of the hydraulic press 11 extends into the metal test box 8-2 through the corresponding side wall and is connected to a force transmission plate 12. A reaction plate 13 is symmetrically arranged on the side wall of the metal test box 8-2 corresponding to the force transmission plate 12. The hydraulic press 11 is connected to a PC-end pressure control system 4 through a wire 10.

[0039] The temperature heating system 2 includes a metal plate 15 embedded in the middle of the side of the reaction plate 13 near the inside of the metal test box 8-2. The metal plate 15 is in direct contact with the rock sample 9. An electromagnetic heating coil 14 is embedded in the side of the metal plate 15 near the inside of the metal test box 8-2. The electromagnetic heating coil 14 is connected to the PC-end temperature control system 6 through a wire passing out of the metal test box 8-2.

[0040] It also includes a pressure monitoring system 5, which includes a high-temperature strain gauge 17. The high-temperature strain gauge 17 is attached to the side of the force transmission plate 12 near the inside of the metal test box 8-2, which can realize high-precision monitoring of stress during the application of confining pressure to the rock sample 9. The high-temperature strain gauge 17 is connected to the PC pressure detection display through a wire passing through the metal test box 8-2. It also includes a temperature monitoring system 6, which includes a thermal resistor 18 attached to the side of the reaction plate 13 near the inside of the metal test box 8-2, which can achieve high-precision monitoring of the temperature of the rock sample 9. The thermal resistor 18 is connected to a PC-side temperature display through wires passing through the metal test box 8-2.

[0041] The inner wall of the metal experimental box 8-2 is also provided with a heat insulation material layer 16, and the reaction plate 13 is set on the corresponding heat insulation material layer 16 of the inner wall.

[0042] like Figure 5 and Figure 6As shown, a displacement sensor 23 and a pressure sensor 24 are also installed on the side of the force transmission plate 12 near the inside of the metal experimental box 8-2, and a temperature sensor 25 is also installed on the side of the reaction plate 13 near the inside of the metal experimental box 8-2. The displacement sensor 23 can monitor the displacement of the hydraulic head of the hydraulic press in real time, which can effectively reduce the risk of equipment damage; the pressure sensor 24 can monitor the magnitude of the confining pressure on the rock sample 9 in real time. The temperature sensor 25 is installed in the reaction plate 13 to monitor the temperature of the rock sample 9 in real time. The displacement sensor 23 and the pressure sensor 24 are all connected to the PC display through wires.

[0043] The complex permittivity testing system 3 includes a vector network analyzer 19. The vector network analyzer 19 is connected to a coaxial adapter 21 via a coaxial cable 20. The other end of the coaxial adapter 21 is connected to a rectangular waveguide port 22. The other end of the rectangular waveguide port 22 is attached to the outer wall of the metal experimental box 8-2 and to the outer wall of the metal experimental box 8-2 where a force transmission plate 12 is correspondingly provided. The force transmission plate 12 on the side corresponding to the rectangular waveguide port 22 is made of a material that is transparent to waves and has high compressive strength.

[0044] In this embodiment, the hydraulic press 11 is arranged on the top, front and left sides of the metal experimental box 8-2, and the force transmission plate 12 is arranged. At the same time, the reaction plate 13 is arranged symmetrically with the force transmission plate 12 on the bottom, rear and right sides of the metal experimental box 8-2 to achieve uniform pressure loading. The confining pressure in the deep complex stratum environment is simulated by applying pressure to the rock sample 9 in three directions.

[0045] like Figure 2 and 3 As shown, if the rectangular waveguide port 22 is set on the left side of the metal experimental box 8-2, then the thickness d of the rock sample 9 is consistent with the height of the interface of the rectangular waveguide port 22.

[0046] The material selected for the force transmission plate 12 on the irradiation side of the rectangular waveguide port 22 of the confining pressure loading system 1 should be a material that is transparent to waves and has high compressive strength, such as quartz glass; the force transmission plates 12 on the other two sides should be a material with good thermal conductivity and high compressive strength, such as aluminum alloy or copper alloy.

[0047] The connection between the hydraulic press head 11 and the metal test box 8-2 is a sealed connection, and the connection between the wires and the metal test box 8-2 is a sealed connection.

[0048] Each hydraulic press 11 uses an independent servo system, which can achieve both synchronous and asynchronous loading.

[0049] Example 6 This invention relates to a method for testing the complex permittivity of rocks under high temperature and pressure. The method employs the testing apparatus described in Example 5. After processing the rock sample into the corresponding shape and size, it is placed in a metal experimental box 8-2. The force transmission plate 12 is adjusted using a hydraulic press 11 to ensure the rock sample 9 is in contact with the force transmission plate 12 and the reaction plate 13. The heating rate of the electromagnetic heating coil 14 is adjusted using a PC-based temperature control system 6. Once the rock sample 9 reaches the target temperature, pressure is transmitted to the rock sample 9 via the hydraulic press 11. After the temperature and pressure parameters of the rock sample 9 stabilize, the vector network analyzer 19 is activated to measure the transmission coefficient of the rock sample 9. The complex permittivity is then calculated based on the transmission coefficient.

[0050] Preferably, during heating and pressurization, the target confining pressure and temperature are set in the PC-side pressure control system 4 and the PC-side temperature control system 6, and the rock sample 9 is heated at a uniform rate by the electromagnetic heating coil 14. During the heating process, the temperature of the rock sample 9 is monitored in real time by the thermal resistor 18 to avoid local overheating. After the target temperature is reached, the heating is stopped so that the electromagnetic heating coil 14 maintains the target temperature. After the temperature of the rock sample stabilizes, the pressure control system 4 is activated to maintain a uniform pressurization rate. The pressure is transmitted to the force transmission plate 12 through the hydraulic press 11. During the pressurization process, the pressure change is monitored synchronously by the high-temperature strain gauge 17 to prevent the rock sample from breaking due to a sudden increase in pressure. After the target pressure is reached, the pressurization is stopped and the target pressure is maintained. After starting the vector network analyzer 19, a frequency sweep test is performed within the target frequency range through the rectangular waveguide port 22. The test is performed for 1-3 seconds at each frequency point, and the average value is taken to obtain the transmission coefficient. Through transmission coefficient The complex permittivity of the rock sample to be tested was calculated.

[0051] The specific steps are as follows: Step 1: Ensure that the cross-sectional dimensions of the corresponding side of the rock sample 9 and the rectangular waveguide aperture 22 are the same, and denote the thickness of the rock sample as... d The antenna ports of rock sample 9 and rectangular waveguide port 22 are close together. Frequency sweep test is performed through rectangular waveguide port 22 within the target frequency range. The test is performed for 1-3 seconds at each frequency point. The test is repeated 3 times and the average value is taken to obtain the transmission coefficient. ; Vector Network Analyzer 19 tests transmission coefficients The principle is as follows: Based on the terminal short-circuit method, the transmission coefficient of the rock sample 9 to be tested is calculated by formula (1). : (1) In the formula: d The thickness of rock sample 9 to be tested; The standing wave ratio of the rock sample 9 to be tested; , k This represents the phase constant when the sample is not placed inside. This is the distance from the point of minimum standing wave to the input end of the rock sample 9 to be tested.

[0052] Step 2: Through transmission coefficients The complex permittivity of the rock sample to be tested was calculated as follows: The attenuation constant is obtained by using the conditional equation for the transmission coefficient, i.e., formula (2). and phase constant The complex permittivity of the rock sample 9 to be tested can be obtained by formulas (3) and (4). and loss tangent ; (2) (3) (4) In the formula: The cutoff wave number is calculated using formula (5); The free space wavenumber is calculated using formula (6); (5) (6) In the formula: The cutoff wavelength, , a To test the wide side dimension of the waveguide; For the wavelength in free space, , c For the speed of light in free space, To test the resonant frequency of the waveguide.

[0053] Example 7 Based on Example 6, after one test is completed, the temperature and pressure parameters are adjusted, and steps 2-4 are repeated to complete the complex dielectric constant test under different high temperature and high pressure conditions. The real part, imaginary part and loss tangent of the dielectric constant under different temperature and confining pressure conditions are recorded simultaneously. After all tests are completed, the pressure is first controlled by the PC-side pressure control system 4 to release the pressure slowly at a uniform rate to avoid sudden pressure drop that could damage the rock sample structure. After the pressure drops to normal pressure, heating is stopped, and the sample is allowed to cool naturally to room temperature. The force transmission plate 12 and the reaction plate 13 are then opened, the rock sample 9 is removed, and the testing system is cleaned and maintained.

Claims

1. A testing device for the complex permittivity of rocks under high temperature and high pressure, characterized in that, The test bench (8) is provided with a rock sample (9) placed on it. A confining pressure loading system (1) is provided on the test bench (8) to apply confining pressure to the rock sample (9). The confining pressure loading system (1) is connected to a temperature heating system (2) via wires. The temperature heating system (2) is used to heat the rock sample (9). The test bench (8) also includes a complex dielectric constant testing system (3) for testing the dielectric properties of the rock sample (9).

2. The testing device for the complex permittivity of rocks under high temperature and high pressure according to claim 1, characterized in that, The test bench (8) includes a metal support (8-1), on which a rectangular metal test box (8-2) is fixedly mounted, and the confining pressure loading system (1) is mounted on the metal test box (8-2).

3. The testing device for the complex permittivity of rocks under high temperature and high pressure according to claim 2, characterized in that, The confining pressure loading system (1) includes a hydraulic press (11) set in the middle of the outer side of three adjacent and non-corresponding side walls of the metal test box (8-2). The pressure head of the hydraulic press (11) extends into the metal test box (8-2) through the side wall of the corresponding side and is connected to a force transmission plate (12). A reaction plate (13) is symmetrically arranged on the side wall of the metal test box (8-2) corresponding to the force transmission plate (12). The hydraulic press (11) is connected to a PC-end pressure control system (4) through a wire (10).

4. The testing device for the complex permittivity of rocks under high temperature and high pressure according to claim 3, characterized in that, The inner wall of the metal experimental box (8-2) is also provided with a heat insulation material layer (16), and the reaction plate (13) is provided on the heat insulation material layer (16) of the corresponding inner wall.

5. The testing device for the complex permittivity of rocks under high temperature and high pressure according to claim 3, characterized in that, The temperature heating system (2) includes a metal plate (15) embedded in the middle of the side of the reaction plate (13) near the inside of the metal experimental box (8-2). An electromagnetic heating coil (14) is embedded in the side of the metal plate (15) near the inside of the metal experimental box (8-2). The electromagnetic heating coil (14) passes through the metal experimental box (8-2) and is connected to a PC-end temperature control system (6).

6. The testing apparatus for the complex permittivity of rocks under high temperature and high pressure according to claim 5, characterized in that, It also includes a pressure monitoring system (5), which includes a high-temperature strain gauge (17). The high-temperature strain gauge (17) is attached to the side of the force transmission plate (12) near the inside of the metal test box (8-2). The high-temperature strain gauge (17) is connected to the PC-side pressure detection display through a wire passing through the metal test box (8-2). It also includes a temperature monitoring system (6), which includes a thermal resistor (18) attached to the side of the reaction plate (13) near the inside of the metal experimental box (8-2). The thermal resistor (18) is connected to a PC-side temperature display via a wire passing through the metal experimental box (8-2).

7. The testing apparatus for the complex permittivity of rocks under high temperature and high pressure according to claim 6, characterized in that, The force transmission plate (12) is equipped with a displacement sensor (23) and a pressure sensor (24) on the side near the inside of the metal experimental box (8-2), and the reaction plate (13) is equipped with a temperature sensor (25) on the side near the inside of the metal experimental box (8-2).

8. The testing apparatus for the complex permittivity of rocks under high temperature and high pressure according to claim 7, characterized in that, The complex permittivity testing system (3) includes a vector network analyzer (19), which is connected to a coaxial adapter (21) via a coaxial cable (20). The other end of the coaxial adapter (21) is connected to a rectangular waveguide port (22). The other end of the rectangular waveguide port (22) is attached to the outer wall of the metal experimental box (8-2) and to the outer wall of the metal experimental box (8-2) where a force transmission plate (12) is correspondingly provided. The force transmission plate (12) on the side corresponding to the rectangular waveguide port (22) is made of a material that is transparent to waves and has high compressive strength.

9. A method for testing the complex permittivity of rocks under high temperature and high pressure based on the terminal short-circuit method, characterized in that, After the rock sample (9) is processed into the corresponding shape and size, it is placed in the metal test box (8-2). The force transmission plate (12) is adjusted by the hydraulic press (11) so that the rock sample (9) is in contact with the force transmission plate (12) and the reaction plate (13). The heating rate of the electromagnetic heating coil (14) is adjusted by the PC-end temperature control system (6). After the temperature of the rock sample (9) reaches the target temperature, the pressure is transmitted to the rock sample (9) by the hydraulic press (11). After the temperature and pressure parameters of the rock sample (9) are stable, the vector network analyzer (19) is started to measure the reflection coefficient of the rock sample (9). The complex dielectric constant is calculated based on the reflection coefficient.

10. The method for testing the complex permittivity of rock under high temperature and high pressure based on the terminal short-circuit method according to claim 9, characterized in that, During heating and pressurization, the target confining pressure and temperature are set in the PC end pressure control system (4) and the PC end temperature control system (6). The rock sample (9) is heated at a uniform rate through the electromagnetic heating coil (14). During the heating process, the temperature of the rock sample (9) is monitored in real time through the thermal resistor (18). After the target temperature is reached, the heating is stopped so that the electromagnetic heating coil (14) can maintain the target temperature. After the temperature of the rock sample stabilizes, the pressure control system (4) is started to maintain a uniform pressurization rate. The pressure is transmitted to the force transmission plate (12) through the hydraulic press (11). During the pressurization process, the pressure change is monitored synchronously through the high-temperature strain gauge (17). After the target pressure is reached, the pressurization is stopped and the target pressure is maintained. After starting the vector network analyzer (19), a frequency sweep test is performed through the rectangular waveguide port (22) within the target frequency range. The test is performed for 1-3 seconds at each frequency point. The test is repeated 3 times and the average value is taken to obtain the transmission coefficient. Through transmission coefficient The complex permittivity of the rock sample to be tested was calculated as follows: Step 1: Make the corresponding cross-sectional dimensions of the rock sample (9) and the rectangular waveguide port (22) the same, and denote the thickness of the rock sample (9) as d. Place the antenna ports of the rock sample (9) and the rectangular waveguide port (22) close together, and perform a frequency sweep test through the rectangular waveguide port (22) within the target frequency range. Test for 1-3 seconds at each frequency point, repeat the test 3 times, and take the average value to obtain the transmission coefficient. ; Step 2: Through transmission coefficients The complex permittivity of the rock sample to be tested was calculated as follows: The attenuation constant is obtained by using the conditional equation for the transmission coefficient, i.e., formula (2). and phase constant The complex permittivity of the rock sample 9 to be tested can be obtained by formulas (3) and (4). and loss tangent ; (2) (3) (4) In the formula: The cutoff wave number is calculated using formula (5); The free space wavenumber is calculated using formula (6); (5) (6) In the formula: The cutoff wavelength, , a To test the wide side dimension of the waveguide; For the wavelength in free space, , c For the speed of light in free space, To test the resonant frequency of the waveguide.

Images