A deep in-situ petrophysical experiment device based on fiber grating

Abstract

The application relates to the field of deep rock physical in-situ test experiments, and discloses a deep in-situ rock physical experiment device based on a fiber grating. The deep in-situ rock physical experiment device based on the fiber grating comprises a pressure container provided with a hollow cavity for placing a rock sample, and the two axial ends of the hollow cavity are respectively provided with an axially movable ballast end plug and a measuring end plug; an axial compression loading module, which comprises an axial driving part for applying an axial force to the ballast end plug from the outside and a pressure sensor axially connected to the outside of the measuring end plug, and a vibration generating unit is arranged between the axial driving part and the ballast end plug or between the measuring end plug and the pressure sensor; and a detection module, which comprises a first axial fiber grating sensing element used for being attached to the peripheral wall of the rock sample along the axial direction, and the first axial fiber grating sensing element is used for acquiring axial deformation data of the rock sample. The application can improve the accuracy and reliability of the dynamic and static elastic parameter measurement experiment of the rock sample.

Description

Technical Field

[0001] This application belongs to the field of in-situ testing experiments in deep rock physics, specifically, it relates to an in-situ deep rock physics experimental device based on fiber Bragg gratings. Background Technology

[0002] In actual seismic exploration and development, the elastic and mechanical properties of rocks beneath the in-situ strata are quite important. Static elastic parameters of rocks are crucial for oil and gas extraction, well and mine evaluation, and hydraulic fracturing; dynamic elastic parameters can provide very important information for reservoir quality and fluid detection.

[0003] In existing experimental setups, acoustic vibration sources are typically used to vibrate rock samples, and multiple metal or semiconductor strain gauges are attached to measure the dynamic elastic parameters of the rock samples. This process is not only cumbersome but also costly. Furthermore, existing acoustic vibration sources are generally located inside the working chamber, and are susceptible to unpredictable changes in the working chamber environment, such as high temperature, high pressure, and humidity and erosion caused by fluid displacement. This results in inaccurate test data. Summary of the Invention

[0004] The purpose of this application is to provide a deep in-situ rock physics experimental device based on fiber optic gratings to improve the reliability and accuracy of rock sample dynamic and static elastic parameter measurement experiments.

[0005] To achieve the above objectives, this application provides a deep in-situ rock physics experimental device based on fiber Bragg gratings. The deep in-situ rock physics experimental device based on fiber Bragg gratings includes: The pressure vessel is provided with a hollow cavity for placing rock samples. The hollow cavity has axially movable ballast end plugs and measuring end plugs at its two axial ends, respectively. The axial compression loading module includes an axial drive for applying axial force to the ballast end plug from the outside and a pressure sensor axially connected to the outside of the measuring end plug. A vibration generating unit is provided between the axial drive and the ballast end plug, or between the measuring end plug and the pressure sensor. The detection module includes a first axial fiber optic grating sensing element for attaching along the axial direction to the periphery of the rock sample. The first axial fiber optic grating sensing element is used to acquire axial deformation data of the rock sample.

[0006] In some implementations, the axial compression loading module includes a hydraulic cylinder and a hydraulic pump, with the piston rod of the hydraulic cylinder connected axially to the outside of the ballast end plug, and the hydraulic pump used to supply oil to the hydraulic cylinder.

[0007] In some embodiments, the vibration generating unit includes a piezoelectric ceramic disposed between the piston rod and the ballast end plug, and the deep in-situ rock physics experimental device based on fiber optic gratings further includes: A function generator is used to generate sinusoidal electrical signals of different frequencies. A power amplifier is used to amplify sinusoidal electrical signals and guide the amplified sinusoidal electrical signals to piezoelectric ceramics.

[0008] In some implementations, the detection module further includes: A laser generator, used to produce laser light with periodically varying wavelengths; The photoelectric converter is connected to the first axial fiber optic grating sensing element via optical fiber. The photoelectric converter is used to convert the light signal reflected by the first axial fiber optic grating sensing element into an electrical signal. The demodulator, electrically connected to the photoelectric converter, is used to demodulate the electrical signal to obtain the deformation data of the first axial fiber optic grating sensing element.

[0009] In some embodiments, the detection module further includes a second axial fiber Bragg grating sensing element for axially attaching to the peripheral wall of the ballast end plug. The laser source, the second axial fiber Bragg grating sensing element, the photoelectric converter, and the demodulator are connected. The deep in-situ rock physics experimental apparatus based on the fiber Bragg grating also includes a computer configured as follows: Axial deformation data of the ballast end plug is obtained from the second axial fiber optic grating sensing element, and axial deformation data of the rock sample is obtained from the first axial fiber optic grating sensing element. The dynamic Young's modulus of the rock sample is calculated based on the axial deformation data of the ballast end plug, the axial deformation data of the rock sample, the preset Young's modulus of the ballast end plug, and the first preset formula. The first preset formula is: , in, The dynamic Young's modulus of the rock sample. This refers to the axial deformation data of the ballast end plug. The preset Young's modulus for the ballast end plug. This represents the axial deformation data of the rock sample.

[0010] In some embodiments, the detection module further includes a circumferential fiber Bragg grating sensing element for circumferentially attaching to the periphery of the rock sample. The laser source, the circumferential fiber Bragg grating sensing element, the photoelectric converter, and the demodulator are connected together, and the computer is further configured as follows: Radial deformation data of rock samples are acquired from circumferential fiber grating sensing elements; The Poisson's ratio of the rock sample is calculated based on the axial deformation data, the radial deformation data, and the second preset formula. The second preset formula is: , in, The Poisson's ratio of the rock sample. This represents the radial deformation data of the rock sample; The radial deformation data of the rock sample is obtained from the detection module, the axial stress of the rock sample is obtained from the pressure sensor, and the static Young's modulus of the rock sample is calculated according to the third preset formula. The third preset formula is: , in, The static Young's modulus of the rock sample. This represents the axial stress of the rock sample.

[0011] In some embodiments, the periphery of the rock sample is wrapped with a rubber sleeve, and the deep in-situ rock physics experimental device based on fiber optic gratings also includes a confining pressure loading module, which includes a confining pressure loading pump for injecting confining pressure fluid into the rubber sleeve.

[0012] In some embodiments, the ballast end plug and the measuring end plug are respectively provided with seepage simulation working channels for connecting to the two axial ends of the rock sample. The deep in-situ rock physics experimental device based on fiber optic grating also includes a fluid displacement unit, which is used to provide high-pressure fluid to the seepage simulation working channel of one of the ballast end plug and the measuring end plug.

[0013] In some embodiments, the ballast end plug and the measuring end plug are respectively provided with seepage simulation working channels for connecting to the two axial ends of the rock sample, and the vacuum unit is used to evacuate the seepage simulation working channel of one of the ballast end plug and the measuring end plug.

[0014] In some embodiments, the deep in-situ rock physics experimental apparatus based on fiber optic gratings also includes a temperature control unit for adjusting the temperature of the rock sample. The temperature control unit includes a heating jacket that surrounds the pressure vessel and a resistance wire for adjusting the temperature of the heating jacket.

[0015] Through the above technical solutions, the deep in-situ rock physics experimental device based on fiber Bragg gratings provided in this application has the following beneficial effects: In the technical solution of this application, the vibration generating unit can be located between the axial drive component and the ballast end plug, or between the measuring end plug and the pressure sensor. This allows the vibration unit to indirectly drive the rock sample vibration through the ballast end plug or the measuring end plug. The placement of the vibration generating unit away from the high-temperature, high-pressure, or humid environment of the rock sample ensures its performance. Furthermore, the pressure sensor can acquire the axial load applied to the rock by the axial drive component through the ballast end plug. Moreover, since metal strain gauges or semiconductor strain gauges are inherently fragile and require a large number, leading to high rock sample production costs, this application uses fiber optic grating-based sensors to acquire the axial deformation data of the rock sample. A single fiber optic grating sensor can include multiple sensing elements to acquire strain at different locations on the rock sample, thereby reducing the number of strain gauges required for the rock sample, reducing the workload and difficulty of wiring, and improving the reliability of the detection module in harsh environments. Compared to the prior art where the acoustic source is placed inside the working cavity, the vibration generating unit and detection module of this application offer better stability and accuracy. Based on a more stable low-frequency vibration environment and more accurate measurement results from the pressure sensor and the first axial fiber optic grating sensing element, this application can improve the accuracy and reliability of rock sample dynamic and static elastic parameter measurement experiments.

[0016] Other features and advantages of the embodiments of this application will be described in detail in the following detailed description section. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the following detailed description to explain the embodiments of this application, but do not constitute a limitation on the embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without any inventive effort. In the drawings: Figure 1 This is a schematic diagram of a deep in-situ rock physics experimental device based on a fiber optic grating according to a specific embodiment of this application. Figure 2 for Figure 1 A schematic diagram of the rock sample structure; Figure 3 Figure 1 shows the experimental measurement results of the static and dynamic trans-frequency band Young's modulus of dry shale under different confining and axial pressures, provided for a specific embodiment of this application. Figure 4 The experimental measurement results of the static and dynamic trans-frequency band Poisson's ratio of dry shale under different confining pressures and axial pressures are shown in the figure for specific embodiments of this application. Figure 5 This is a flowchart illustrating the steps of a rock sample physical parameter measurement experiment according to a specific embodiment of this application.

[0018] Explanation of reference numerals in the attached figures Detailed Implementation

[0019] The specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0020] The following description, with reference to the accompanying drawings, describes a deep in-situ rock physics experimental apparatus based on a fiber optic grating according to this application.

[0021] This application discloses a novel deep in-situ rock physics experimental device based on fiber Bragg gratings, such as... Figure 1 and Figure 2 As shown, a specific embodiment of a deep in-situ rock physics experimental apparatus based on a fiber optic grating includes: Pressure vessel 100 is provided with a hollow cavity for placing rock sample R. The hollow cavity is provided with an axially movable ballast end plug U and a measuring end plug D at its two axial ends. The axial compression loading module includes an axial drive for applying axial force to the ballast end plug U from the outside and a pressure sensor 400 axially connected to the outside of the measuring end plug D. A vibration generating unit 500 is provided between the axial drive and the ballast end plug U, or between the measuring end plug D and the pressure sensor 400. The detection module 600 includes a first axial fiber optic grating sensing element F1 for axially attaching to the peripheral wall of the rock sample R. The first axial fiber optic grating sensing element F1 is used to acquire axial deformation data of the rock sample R.

[0022] In the technical solution of this application, the vibration generating unit 500 can be disposed between the axial drive member and the ballast end plug U, or between the measuring end plug D and the pressure sensor 400, so that after the rock sample is axially compressed, the vibration unit can indirectly drive the rock sample R to vibrate through the ballast end plug U or the measuring end plug D. Since the vibration generating unit 500 is located outside the hollow cavity, away from the high temperature, high pressure, or humid environment of the rock sample R, the working performance of the vibration generating unit 500 is guaranteed. Furthermore, the pressure sensor 400 can acquire the axial load applied to the rock by the axial drive member through the ballast end plug U. Furthermore, since metal strain gauges or semiconductor strain gauges are inherently fragile and require a large number, resulting in high manufacturing costs for rock sample R, this application uses fiber optic grating-based sensors to acquire the axial deformation data of rock sample R. A single fiber optic grating sensor can include multiple sensing elements to acquire strain at different locations on rock sample R, thereby reducing the number of strain gauges required for rock sample R, reducing the workload and difficulty of wiring, and improving the reliability of the detection module 600 in harsh environments. Compared to the prior art where the acoustic wave source is placed inside the working cavity, the vibration generation unit 500 and detection module 600 of this application have better stability and accuracy. Based on the more stable low-frequency vibration environment and the more accurate measurement results of the pressure sensor 400 and the first axial fiber optic grating sensing element F1, this application can improve the accuracy and reliability of the dynamic and static elastic parameter measurement experiments of rock sample R.

[0023] In this embodiment, such as Figure 1 As shown, the axial load loading module includes a hydraulic cylinder 200 and a hydraulic pump 300. The piston rod 210 of the hydraulic cylinder 200 is axially connected to the outer side of the ballast end plug U, and the hydraulic pump 300 supplies oil to the hydraulic cylinder 200. Specifically, the rock sample R requires a large axial load, and the hydraulic cylinder 200 has high power density and good impact resistance, thereby achieving precise control of the axial load on the rock sample R. However, those skilled in the art will understand that the axial load loading module can also be a drive component such as an electric cylinder, a pneumatic cylinder, or even a gear and rack mechanism, and these structural forms should also fall within the protection scope of this application.

[0024] In this embodiment, such as Figure 2 As shown, the vibration generating unit 500 includes a piezoelectric ceramic disposed between the piston rod 210 and the ballast end plug U. The deep in-situ rock physics experimental device based on fiber optic grating also includes: A function generator is used to generate sinusoidal electrical signals of different frequencies. A power amplifier is used to amplify sinusoidal electrical signals and guide the amplified sinusoidal electrical signals to piezoelectric ceramics.

[0025] A piezoelectric ceramic is positioned between the piston rod 210 and the ballast end plug U. The piezoelectric properties of the ceramic allow it to indirectly drive the rock sample R to vibrate via the ballast end plug U. Specifically, the function generator of the vibration generation unit 500 can generate a sinusoidal electrical signal with a frequency between 0 Hz and 10^6 Hz. After being amplified by a power amplifier and guided to the piezoelectric ceramic, the piezoelectric ceramic vibration source can convert the electrical signal into sinusoidal mechanical vibration of the corresponding frequency, thereby indirectly driving the rock sample R to vibrate accordingly.

[0026] In this embodiment, the detection module 600 further includes: A laser generator, used to produce laser light with periodically varying wavelengths; The photoelectric converter is connected to the first axial fiber optic grating sensing element F1 via an optical fiber. The photoelectric converter is used to convert the light signal reflected by the first axial fiber optic grating sensing element F1 into an electrical signal. The demodulator is electrically connected to the photoelectric converter. The demodulator is used to demodulate the electrical signal to obtain the deformation data of the first axial fiber optic grating sensing element F1.

[0027] By controlling the change in the driving current of the laser source, the output light wavelength can be periodically and continuously changed, scanning the spectral region of the sensing fiber grating. After the optical signal enters the fiber grating array, due to the wavelength selectivity of the fiber grating, the optical signal that meets the conditions is reflected by the grating to the photoelectric converter, generating an electrical signal corresponding to the reflected optical signal. The demodulator then demodulates the electrical signal and acquires the deformation data of the fiber grating sensing element. Those skilled in the art will understand that operators can set additional fiber grating sensing elements to compensate for temperature, thereby eliminating the influence of high-temperature environments on strain measurements.

[0028] Since the force on the ballast end plug U is the same as that on the rock sample R, in this embodiment, as... Figure 1 and Figure 2 As shown, the detection module 600 also includes a second axial fiber grating sensing element for axially attaching to the peripheral wall of the ballast end plug U. The laser source, the second axial fiber grating sensing element, the photoelectric converter, and the demodulator are connected. The deep in-situ rock physics experimental device based on the fiber grating also includes a computer, configured as follows: Axial deformation data of the ballast end plug U is obtained from the second axial fiber optic grating sensing element, and axial deformation data of the rock sample R is obtained from the first axial fiber optic grating sensing element F1. The dynamic Young's modulus of rock sample R is calculated based on the axial deformation data of ballast end plug U, the axial deformation data of rock sample R, the preset Young's modulus of ballast end plug U, and the first preset formula. The first preset formula is: , in, Let R be the dynamic Young's modulus of the rock sample. This refers to the axial deformation data of the ballast end plug U. The preset Young's modulus of the ballast end plug U. The data represents the axial deformation of rock sample R. Specifically, there can be four of each of the first axial fiber grating sensing element F1 and the second axial fiber grating sensing element, which are arranged sequentially and evenly at intervals on the four sides of the periphery of rock sample R and ballast end plug U, in order to improve the accuracy of axial deformation data detection of rock sample and ballast end plug U.

[0029] The first preset formula is applicable to experiments where rock sample R is in a low-frequency vibration environment, i.e., it is necessary to measure the dynamic Young's modulus of rock sample R. To better understand the elastic properties of rock sample R, it is also necessary to obtain its Poisson's ratio and static Young's modulus. In this embodiment, as... Figure 2 As shown, the detection module 600 also includes a circumferential fiber grating sensing element F2 for circumferentially affixed to the circumferential wall of the rock sample R. The laser source, the circumferential fiber grating sensing element F2, the photoelectric converter, and the demodulator are connected together. The computer is also configured as follows: Radial deformation data of rock sample R are acquired from the circumferential fiber grating sensing element F2; Based on the axial deformation data and radial deformation data of rock sample R, and the second preset formula, calculate the Poisson's ratio of rock sample R; The second preset formula is: , in, The Poisson's ratio of rock sample R. This represents the radial deformation data of rock sample R; The radial deformation data of rock sample R is obtained from the detection module, the axial stress of rock sample R is obtained from the pressure sensor 400, and the static Young's modulus of rock sample R is calculated according to the third preset formula. The third preset formula is: , in, Let R be the static Young's modulus of rock sample R. This represents the axial stress of rock sample R. To ensure the accuracy of the axial deformation data and radial deformation data of rock sample R acquired by the detection module 600, as follows... Figure 2 As shown, multiple pairs of axial strain gauges S1 and circumferential strain gauges S2 can also be arranged on the rock sample R as references for the fiber optic grating sensing element, thereby improving the accuracy of the detection module 600.

[0030] Under different confining pressure environments, the dynamic and static elastic parameters of rock sample R will change accordingly. In this embodiment, such as... Figure 1As shown, the rock sample R is encased in a rubber sleeve 700. The deep in-situ rock physics experimental apparatus based on fiber optic gratings also includes a confining pressure loading module, which includes a confining pressure loading pump for injecting confining pressure fluid into the rubber sleeve 700. Specifically, the operator can inject confining pressure fluid (e.g., pure water) between the rubber sleeve 700 and the periphery of the rock sample R using a servo pump, and obtain the confining pressure on the rock sample R through a pressure sensor connected to the servo pump, thereby understanding how the dynamic and static elastic parameters of the rock sample R change accordingly under different confining pressure environments. Figure 3 As shown, a deep in-situ rock physics experimental setup based on fiber Bragg gratings was used to measure the dynamic Young's modulus of rock samples under different confining pressures (15 MPa, 10 MPa, 5 MPa) and frequencies (0 Hz ~ 10^6 Hz) multiple times using strain gauges and Bragg gratings (i.e., fiber Bragg grating sensing elements). The measurement results are shown in [Figure number missing]. Figure 3 (Where, at a frequency of 0Hz, the dynamic Young's modulus is the same as the static Young's modulus.) Figure 4 As shown, a deep in-situ rock physics experimental setup based on fiber Bragg gratings was used to measure the Poisson's ratio of rock samples under different confining pressures (15 MPa, 10 MPa, 5 MPa) and frequencies (0 Hz ~ 10^6 Hz) multiple times using strain gauges and Bragg gratings (i.e., fiber Bragg grating sensing elements). The measurement results are shown in [Figure number missing]. Figure 4 .

[0031] In real-world environments, rocks beneath in-situ strata possess varying degrees of liquid saturation. Rock samples R with different saturations exhibit different dynamic and static elastic parameters. In this embodiment, as... Figure 1 As shown, the ballast end plug U and the measuring end plug D are respectively provided with seepage simulation working channels for connecting to the two axial ends of the rock sample R. The deep in-situ rock physics experimental device based on fiber optic gratings also includes a fluid displacement unit, which is used to provide high-pressure fluid to the seepage simulation working channel of one of the ballast end plug U and the measuring end plug D. Specifically, liquid can be injected into the core of the rock sample R through the seepage simulation working channel of the ballast end plug U by an injection pump to adjust the liquid saturation of the rock sample R. When the liquid flows out from the seepage simulation working channel of the measuring end plug D, it can be determined that the rock sample R is completely saturated, and the injection of liquid can be stopped. Those skilled in the art will understand that, in order to obtain the dynamic and static elastic parameters of the rock sample R under different pore pressures, the operator can replace the liquid with gas.

[0032] In real-world environments, the core of rock sample R may also be under negative pressure. In this embodiment, such as... Figure 1As shown, the ballast end plug U and the measuring end plug D are respectively provided with seepage simulation working channels for connecting to the two axial ends of the rock sample R. The vacuum unit is used to evacuate the seepage simulation working channel of one of the ballast end plug U and the measuring end plug D. In this way, the deep in-situ rock physics experimental device based on fiber optic grating of this application can realize the measurement of the dynamic and static elastic parameters of the rock sample R under negative pressure pore pressure.

[0033] In real-world environments, the dynamic and static elastic parameters of rock sample R are affected not only by factors such as pore pressure, confining pressure, and fluid saturation, but also by the temperature of rock sample R. In this embodiment, as... Figure 1 As shown, the deep in-situ rock physics experimental device based on fiber optic grating also includes a temperature control unit 800 for adjusting the temperature of rock sample R. The temperature control unit 800 includes a heating jacket that wraps around the pressure vessel 100 and a resistance wire for adjusting the temperature of the heating jacket.

[0034] In summary, the operation steps of the deep in-situ rock physics experimental device based on fiber optic gratings in this application can be as follows: Figure 5 As shown: S100: Cleaning, cutting, and grinding reservoir rocks to prepare rock sample R; S200: Attach fiber optic grating sensing elements to rock sample R; S300: Adjusts the vibration frequency and axial pressure of rock sample R; S400: Adjusts the temperature, pore pressure, confining pressure, and fluid saturation of rock sample R; S500: Measures the elastic parameters of rock samples using a detection module.

[0035] Steps S300 and S400 can be performed interchangeably. It should be noted that the confining pressure of the rock sample R generated by the servo pump should not exceed the injection pressure of the injection pump to avoid preventing liquid from being injected into the core.

[0036] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0037] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0038] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A deep in-situ rock physics experimental apparatus based on fiber Bragg gratings, characterized in that, The deep in-situ rock physics experimental device based on fiber Bragg grating includes: The pressure vessel (100) is provided with a hollow cavity for placing a rock sample (R), and the hollow cavity is provided with an axially movable ballast end plug (U) and a measuring end plug (D) at its two axial ends respectively. The axial compression loading module includes an axial drive for applying an axial force to the ballast end plug (U) from the outside and a pressure sensor (400) axially connected to the outside of the measuring end plug (D). A vibration generating unit (500) is provided between the axial drive and the ballast end plug (U) or between the measuring end plug (D) and the pressure sensor (400). The detection module (600) includes a first axial fiber grating sensing element (F1) for axially attaching to the peripheral wall of the rock sample (R). The first axial fiber grating sensing element (F1) is used to acquire the axial deformation data of the rock sample (R). Multiple pairs of axial strain gauges (S1) and circumferential strain gauges (S2) are also arranged on the peripheral wall of the rock sample (R) as references for the fiber grating sensing element. The detection module (600) further includes: A laser generator, used to produce laser light with periodically varying wavelengths; A photoelectric converter is connected to the first axial fiber optic grating sensing element (F1) via an optical fiber. The photoelectric converter is used to convert the optical signal reflected by the first axial fiber optic grating sensing element (F1) into an electrical signal. A demodulator is electrically connected to the photoelectric converter. The demodulator is used to demodulate the electrical signal to obtain the deformation data of the first axial fiber optic grating sensing element (F1). The detection module (600) further includes a second axial fiber grating sensing element for axially attaching to the peripheral wall of the ballast end plug (U). The laser source, the second axial fiber grating sensing element, the photoelectric converter, and the demodulator are connected. The deep in-situ rock physics experimental apparatus based on fiber Bragg gratings also includes a computer, configured as follows: The axial deformation data of the ballast end plug (U) is obtained from the second axial fiber grating sensing element, and the axial deformation data of the rock sample (R) is obtained from the first axial fiber grating sensing element (F1). The dynamic Young's modulus of the rock sample (R) is calculated based on the axial deformation data of the ballast end plug (U), the axial deformation data of the rock sample (R), the preset Young's modulus of the ballast end plug (U), and the first preset formula. The first preset formula is: , in, The dynamic Young's modulus of the rock sample (R) is given. The axial deformation data are for the ballast end plug (U). The preset Young's modulus of the ballast end plug (U) is given. The axial deformation data of the rock sample (R); The detection module (600) further includes a circumferential fiber grating sensing element (F2) for circumferentially attaching to the peripheral wall of the rock sample (R). The laser source, the circumferential fiber grating sensing element (F2), the photoelectric converter, and the demodulator are connected. The computer is further configured to: Radial deformation data of the rock sample (R) are acquired from the circumferential fiber grating sensing element (F2); Based on the axial deformation data and radial deformation data of the rock sample (R) and the second preset formula, calculate the Poisson's ratio of the rock sample (R); The second preset formula is: , in, The Poisson's ratio of the rock sample (R) is given. The radial deformation data of the rock sample (R); The radial deformation data of the rock sample (R) is obtained from the detection module, the axial stress of the rock sample is obtained from the pressure sensor (400), and the static Young's modulus of the rock sample (R) is calculated according to the third preset formula. The third preset formula is: , in, The static Young's modulus of the rock sample (R) is given. denoted as axial stress in the rock sample (R).

2. The deep in-situ rock physics experimental apparatus based on fiber optic gratings according to claim 1, characterized in that, The axial pressure loading module includes a hydraulic cylinder (200) and a hydraulic pump (300). The piston rod (210) of the hydraulic cylinder (200) is connected to the outer side of the ballast end plug (U). The hydraulic pump (300) is used to supply oil to the hydraulic cylinder (200).

3. The deep in-situ rock physics experimental apparatus based on fiber optic gratings according to claim 2, characterized in that, The vibration generating unit (500) includes a piezoelectric ceramic disposed between the piston rod (210) and the ballast end plug (U), and the deep in-situ rock physics experimental device based on fiber optic grating further includes: A function generator is used to generate sinusoidal electrical signals of different frequencies. A power amplifier is used to amplify the sinusoidal electrical signal and guide the amplified sinusoidal electrical signal to the piezoelectric ceramic.

4. The deep in-situ rock physics experimental apparatus based on fiber optic gratings according to claim 1, characterized in that, The rock sample (R) is surrounded by a rubber sleeve (700). The deep in-situ rock physics experimental device based on fiber optic grating also includes a confining pressure loading module, which includes a confining pressure loading pump for injecting confining pressure fluid into the rubber sleeve (700).

5. The deep in-situ rock physics experimental apparatus based on fiber optic gratings according to any one of claims 1 to 4, characterized in that, The ballast end plug (U) and the measuring end plug (D) are respectively provided with seepage simulation working channels for connecting to the two axial ends of the rock sample (R). The deep in-situ rock physics experimental device based on fiber optic grating also includes a fluid displacement unit, which is used to provide high-pressure fluid to the seepage simulation working channel of one of the ballast end plug (U) and the measuring end plug (D).

6. The deep in-situ rock physics experimental apparatus based on fiber optic gratings according to any one of claims 1 to 4, characterized in that, The ballast end plug (U) and the measuring end plug (D) are respectively provided with seepage simulation working channels for connecting to the two axial ends of the rock sample (R), and the vacuum unit is used to evacuate the seepage simulation working channel of one of the ballast end plug (U) and the measuring end plug (D).

7. The deep in-situ rock physics experimental apparatus based on fiber optic gratings according to any one of claims 1 to 4, characterized in that, The deep in-situ rock physics experimental apparatus based on fiber optic grating also includes a temperature control unit (800) for adjusting the temperature of the rock sample (R), the temperature control unit (800) including a heating jacket surrounding the pressure vessel (100) and a resistance wire for adjusting the temperature of the heating jacket.

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