Deep in-situ environment rock parameter acoustic electromagnetic fidelity test system and method

Abstract

The invention relates to the technical field of deep rock mechanics, and provides a deep in-situ environment rock parameter acoustic electromagnetic fidelity test system and method.The deep in-situ environment rock parameter acoustic electromagnetic fidelity test system comprises a cabin, a test space is formed in the cabin, and a rock core sample enters the test space from one end of the cabin through a displacement unit; the temperature and pressure control unit is communicated with the cabin body and is used for adjusting the temperature and the pressure in the cabin body to reach target values and keeping the target values stable; the acoustic electromagnetic testing module is arranged in the cabin body and used for calculating the wave velocity, the resistivity and the apparent resistivity of the rock core sample, and the acoustic electromagnetic testing module is connected with an external acoustic electromagnetic data acquisition system; and the remote control system is electrically connected with the acoustic electromagnetic test module and the temperature and pressure control unit. According to the method, the original occurrence state of the rock can be restored in a fidelity manner, the physical and mechanical parameters of the rock in a deep in-situ real environment are tested and analyzed, the evolution law of the physical and mechanical parameters along with the deep environment is analyzed, and reliable data support is provided for revealing the constitutive relation, the failure mechanism and the disaster breeding mechanism of the deep rock mass.

Description

Technical Field

[0001] This invention relates to the field of deep rock mechanics technology, and in particular to a system and method for high-fidelity acoustic-electromagnetic testing of rock parameters in deep in-situ environments. Background Technology

[0002] The importance of deep resource exploration is becoming increasingly prominent, and revealing the physical and mechanical properties of rocks at different depths has become a key scientific issue in engineering practice.

[0003] The reliability of any engineering design, disaster early warning, and numerical simulation depends on a precise understanding of the physical and mechanical properties of rocks, such as their elastic modulus, porosity, and oil and gas resource content. Therefore, obtaining rock physical and mechanical parameters that accurately reflect the deep in-situ environment is an indispensable scientific prerequisite for the safe development of deep resources.

[0004] However, current methods for testing the physical and mechanical parameters of deep rocks have significant shortcomings. Conventional techniques rely on coring deep rock strata and transporting the cores to surface laboratories for testing. This process leads to the unloading of high in-situ stress, cooling of the high-temperature environment, and dissipation of pore pressure. This "environmental instability" causes irreversible damage and changes in the physical properties of the cores. Parameters such as "elastic modulus," "porosity," and "oil and gas content" measured under conventional conditions are actually distorted data and cannot represent the true mechanical behavior of the rock in its in-situ state, making it difficult to accurately predict and prevent deep engineering disasters. To overcome this core challenge, revolutionary testing technologies and methods must be developed.

[0005] Therefore, there is an urgent need for a deep in-situ environment rock parameter acoustic-electromagnetic fidelity testing system and method to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a system and method for high-fidelity acoustic-electromagnetic testing of rock parameters in deep in-situ environments, in order to solve the problems existing in the prior art.

[0007] To achieve the above objectives, the present invention provides the following solution: The present invention provides a deep in-situ environment rock parameter acoustic-electromagnetic fidelity testing system, comprising:

[0008] The chamber forms a testing space inside, and the core sample enters the testing space from one end of the chamber through a displacement unit;

[0009] A temperature and pressure control unit is connected to the chamber. By activating the temperature and pressure control unit, the temperature and pressure inside the chamber are adjusted to reach the preset target value of the deep in-situ environment and kept stable.

[0010] An acoustic electromagnetic testing module is installed inside the chamber. The module collects ultrasonic signals, electrical signals, and transient electromagnetic signals from the core sample. Based on the collected ultrasonic signals, electrical signals, and transient electromagnetic signals, the module calculates the wave velocity, resistivity, and apparent resistivity of the core sample. The acoustic electromagnetic testing module is connected to an external acoustic electromagnetic data acquisition system.

[0011] The remote control system is electrically connected to the acoustic-electromagnetic testing module and the temperature-pressure control unit.

[0012] According to the present invention, a deep in-situ environment rock parameter acoustic, electromagnetic and magnetic fidelity testing system is provided. The chamber includes a conversion flange, an acoustic measurement ring chamber, an electrical measurement ring chamber, a magnetic measurement ring chamber, and a base plate arranged sequentially. The conversion flange, the acoustic measurement ring chamber, the electrical measurement ring chamber, the magnetic measurement ring chamber, and the base plate are spliced ​​into an integral structure by a plurality of screws, threads and nuts.

[0013] According to the present invention, a deep in-situ environment rock parameter acoustic-electromagnetic fidelity testing system is provided. The acoustic-electromagnetic testing module includes an ultrasonic detection module, an electrical method testing module, and a transient electromagnetic detection module. The ultrasonic detection module includes several ultrasonic sensors, which are fixedly connected to the acoustic measurement ring chamber at equal intervals along the circumference. The electrical method testing module includes several DC sensors, which are fixedly connected to the electrical method testing ring chamber at equal intervals along the circumference. The transient electromagnetic detection module includes several transient electromagnetic sensors, which are fixedly connected to the magnetic measurement ring chamber at equal intervals along the circumference.

[0014] According to the present invention, a deep in-situ environment rock parameter acoustic-electromagnetic fidelity testing system is provided, wherein the temperature and pressure control unit includes a high-pressure pipeline, the magnetic ring chamber is provided with a water inlet, the acoustic ring chamber is provided with a water outlet, the two ends of the high-pressure pipeline are respectively connected to the water outlet and the water inlet, and a high-pressure plunger pump and a mold temperature controller are provided on the high-pressure pipeline.

[0015] According to the present invention, a deep in-situ environment rock parameter acoustic-electromagnetic fidelity testing system further includes an air-mounted socket structure. The air-mounted socket structure includes several air-mounted posts, which are respectively disposed in the acoustic measurement ring chamber, the electrical measurement ring chamber, and the magnetic measurement ring chamber. The ultrasonic sensor, the DC sensor, and the transient electromagnetic sensor are respectively connected to one end of the air-mounted posts, and the other end of the air-mounted posts are connected to the external acoustic-electromagnetic data acquisition system.

[0016] According to the present invention, a deep in-situ environment rock parameter acoustic-electromagnetic fidelity testing system is provided, wherein the displacement unit includes a track displacement system, a gate valve is fixedly connected to the top, and a clamping mechanism is provided on both sides of the gate valve. The two clamping mechanisms are respectively docked with the core sampler and the chamber. The core sampler is used to transport the rock core sample to the testing space.

[0017] According to the present invention, a deep in-situ environment rock parameter acoustic-electromagnetic fidelity testing system is provided, wherein guide rings and sealing gaskets are provided between the acoustic measurement ring chamber and the electrical measurement ring chamber, and between the electrical measurement ring chamber and the magnetic measurement ring chamber.

[0018] A method for acoustic-electromagnetic fidelity testing of rock parameters in deep in-situ environments includes the following steps:

[0019] The displacement unit containing the rock core sample is sealed and docked with the chamber.

[0020] The temperature and pressure control unit is activated to adjust the temperature and pressure inside the chamber to reach the preset target value of the deep in-situ environment and keep it stable. After the temperature and pressure environment is stable, the core sample is pushed into the chamber.

[0021] The ultrasonic, electrical, and transient electromagnetic signals of the core sample are acquired by the acoustic-electromagnetic testing module. Based on the acquired ultrasonic, electrical, and transient electromagnetic signals, the wave velocity, resistivity, and apparent resistivity of the core sample are calculated.

[0022] The elastic modulus, porosity, and hydrocarbon content parameters of the core sample were obtained by inversion using wave velocity, resistivity, and apparent resistivity.

[0023] The method for acoustic, electromagnetic and magnetic fidelity testing of rock parameters in deep in-situ environments provided by the present invention further includes a step of analyzing the influence of temperature and pressure, by changing the temperature and pressure parameters in the chamber and conducting multiple sets of comparative tests.

[0024] According to the method for acoustic-electromagnetic fidelity testing of rock parameters in deep in-situ environments provided by the present invention, when the ultrasonic signal, electrical signal and transient electromagnetic signal of the rock core sample are collected by the acoustic-electromagnetic testing module, the test of each set of parameters is repeated at least three times, and the average value is taken as the final test result.

[0025] Compared with the prior art, the present invention has the following advantages and technical effects:

[0026] This invention provides a system and method for high-fidelity acoustic-electromagnetic (AE) testing of rock parameters in deep in-situ environments. This invention reconstructs the temperature and pressure environment of deep in-situ environments within a testing chamber, enabling high-fidelity acoustic-electromagnetic testing and analysis of rock core samples obtained from deep in-situ environments. This accurately obtains in-situ rock sample parameters, overcoming the problem of large measurement deviations in rock sample parameters due to differences between traditional testing environments and deep in-situ environments. Based on the accurate results obtained from AE testing, this invention deeply analyzes rock physical properties and further inverts the in-situ physical and mechanical parameters of deep rocks, providing accurate and reliable data support for subsequent research on the mechanical behavior of deep rocks. Furthermore, this invention systematically analyzes the influence of deep in-situ environments on the in-situ physical and mechanical behavior of rocks, constructing a correlation system between the in-situ mechanical behavior laws of rocks in deep environments, providing scientific and effective guidance for engineering practices in deep-earth resource development and space utilization. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the cabin structure of the present invention;

[0029] Figure 2 This is a schematic diagram of the internal structure of the cabin of the present invention;

[0030] Figure 3 This is a schematic diagram of the ultrasonic detection module structure of the present invention;

[0031] Figure 4 This is a schematic diagram of the electrical resistivity testing module of the present invention;

[0032] Figure 5 This is a schematic diagram of the transient electromagnetic detection module structure of the present invention;

[0033] Figure 6 This is a schematic diagram of the high-pressure pipeline connection status of the present invention;

[0034] Figure 7 This is a schematic diagram of the shifting unit structure of the present invention;

[0035] The components include: 1. Conversion flange; 2. Acoustic ring chamber; 3. Electrical ring chamber; 4. Magnetic ring chamber; 5. Base plate; 6. Outlet; 7. Inlet; 8. Insertion column; 9. Screw; 10. Nut; 11. Gate valve; 12. Core sampler; 13. Clamping mechanism; 14. Track shifting system; 15. Ultrasonic detection module; 16. Electrical resistivity testing module; 17. Transient electromagnetic detection module; 18. Guide ring; 19. High-pressure pipeline; 20. High-pressure plunger pump; 21. Mold temperature controller; 22. Acoustic-electromagnetic data acquisition system; 23. Remote control system; 24. Core sample; 25. Ultrasonic sensor; 26. DC sensor; 27. Transient electromagnetic sensor. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Reference Figure 1-7 This invention provides a deep in-situ rock parameter acoustic-electromagnetic fidelity testing system, comprising:

[0039] The chamber forms a test space inside, and the core sample 24 enters the test space from one end of the chamber through the shifting unit;

[0040] The temperature and pressure control unit is connected to the cabin. By activating the temperature and pressure control unit, the temperature and pressure inside the cabin are adjusted to reach the preset target value of the deep in-situ environment and remain stable.

[0041] An acoustic electromagnetic testing module is installed inside the chamber. It collects ultrasonic signals, electrical signals and transient electromagnetic signals from the rock core sample 24. Based on the collected ultrasonic signals, electrical signals and transient electromagnetic signals, it calculates the wave velocity, resistivity and apparent resistivity of the rock core sample 24. The acoustic electromagnetic testing module is connected to the external acoustic electromagnetic data acquisition system 22.

[0042] The remote control system 23 is electrically connected to the acoustic-electromagnetic test module and the temperature and pressure control unit.

[0043] In one embodiment of the present invention, the remote control system 23 is a remote control and monitoring system based on industrial Ethernet communication, realizing unmanned and intelligent operation of the entire testing process. Through the host computer software interface, the entire process of chamber docking, temperature and pressure loading and adjustment, core pushing, acoustic and electromagnetic signal testing initiation, data acquisition and analysis can be completed remotely. The system can monitor the internal temperature, pressure, and working status of each sensor in real time, and dynamically display the test data in graphical form. To ensure operational safety, the control system has abnormal warning and automatic shutdown protection functions. When the temperature or pressure exceeds the set threshold, the system will immediately issue an audible and visual alarm and automatically cut off the heating and pressurization circuits to ensure the safety of testing personnel. Remote operation not only effectively avoids personnel risks under high temperature and high pressure environments, but also improves experimental efficiency and data consistency.

[0044] As an optional implementation, the cabin includes a conversion flange 1, an acoustic ring cabin 2, an electrical ring cabin 3, a magnetic ring cabin 4, and a base plate 5 arranged in sequence. The conversion flange 1, the acoustic ring cabin 2, the electrical ring cabin 3, the magnetic ring cabin 4, and the base plate 5 are spliced ​​into an integral structure by a number of screws 9 and a number of threads and nuts 10.

[0045] In one embodiment of the present invention, the inner wall of the chamber is made of corrosion-resistant stainless steel alloy, and its inner surface is mirror-polished to reduce the interference of high-pressure fluid turbulence on signal acquisition. The entire chamber is a modular and detachable design, forming a high-temperature and high-pressure sealed test space that can withstand 150°C and 140MPa, which can realistically simulate the temperature and pressure environment deep underground.

[0046] As an optional implementation, the acoustic-electromagnetic testing module includes an ultrasonic detection module 15, an electrical method testing module 16, and a transient electromagnetic detection module 17. The ultrasonic detection module 15 includes several ultrasonic sensors 25, which are fixedly connected at equal intervals along the circumference inside the acoustic measurement ring chamber 2. The electrical method testing module 16 includes several DC sensors 26, which are fixedly connected at equal intervals along the circumference inside the electrical measurement ring chamber 3. The transient electromagnetic detection module 17 includes several transient electromagnetic sensors 27, which are fixedly connected at equal intervals along the circumference inside the magnetic measurement ring chamber 4.

[0047] In one embodiment of the present invention, the ultrasonic detection module 15, the electrical resistivity testing module 16, and the transient electromagnetic detection module 17 are used to collect ultrasonic signals, electrical resistivity signals, and transient electromagnetic signals from the core sample 24, respectively. The collected signals are then transmitted to an external computer for calculation to determine the wave velocity, resistivity, and apparent resistivity of the core sample 24. Eight ultrasonic sensors 25 are uniformly arranged on the inner wall of the acoustic ring chamber 2. An excitation voltage is applied to the eight ring-arranged ultrasonic sensors 25 via an external host, employing a "one-transmitter-multiple-receiver" mode, where one probe emits a sound wave signal while seven probes simultaneously receive it, thus exciting the ultrasonic waves. The full-field response effect of the core to the ultrasonic waves is collected. The arrival times of the P-wave and S-wave are collected using an ultrasonic array. The cyclic transmission of the array allows for the complete recording of 7×7 channels of ultrasonic signal data. When calculating the non-contact wave velocity, a symmetrically arranged set of sensors is used. The calculation principle is as follows:

[0048] Determine the sound wave propagation path: The ultrasonic wave starts from the transmitting probe, travels through deionized water to the surface of the rock core, then passes through the rock core, and finally travels through deionized water to the receiving probe.

[0049] Core wave velocity calculation formula:

[0050] ;

[0051] ;

[0052] in, The core wave velocity is (m / s). The wave velocity in deionized water is (m / s). The diameter of the rock core sample is in meters (m). The distance (m) is from the probe to the rock core. The time difference (s) between the excitation wave and the arrival wave. The time (s) for sound waves to travel through deionized water.

[0053] The working principle of the electrical measurement ring of the deep in-situ fidelity testing system of this invention is as follows: 32 electrodes with a diameter of Φ0.5mm are evenly arranged on the support on the inner wall of the electrical measurement ring chamber 3. During the experiment, the rock core is placed in a deionized water environment. Signal acquisition is performed after setting the square wave type, transmission voltage, constant current time, sampling frequency, and signal gain. An electric field is excited by an external host. Similarly, the sensor probe adopts a "one-transmit, multiple-receive" working mode, and each electrode can be used as both an excitation electrode and a receiving electrode.

[0054] The two-electrode method is used to calculate the resistivity of rocks. It is assumed that a DC power supply is transmitted through two electrodes (A and B), establishing a stable electric field within the rock mass. The distribution of this electric field is influenced by the occurrence state of rocks with different resistivities. The effects of electrodes A and B on the voltage signals received by electrodes M and N are then calculated based on the distribution of the electric field intensity from the point power supply.

[0055] rock resistivity The calculation formula is:

[0056] ;

[0057] in, rock resistivity U is the voltage (V) between receiving electrodes M and N, and I is the current (A) between transmitting electrodes A and B. Let M be the distance (m) between electrode A and measuring point M. Let N be the distance (m) between electrode A and measuring point N. Let M be the distance (m) between electrode B and measuring point M. Let N be the distance (m) between electrode B and measuring point N. The distance (m) between measuring points M and N.

[0058] Establish a point source electric field model: Consider the emitting electrodes A and B as point sources, generating an electric field in the homogeneous rock core. According to electrostatic theory, the electric potential generated by a point source at a certain point in space... ( (The distance from the point to the power source).

[0059] Formula for calculating the potential at the measuring point:

[0060] ;

[0061] The potentials at points M and N can be measured. The potential difference can be calculated, and the resistivity derived. Substituting the values ​​into the potential expression and rearranging, we obtain the formula for calculating rock resistivity.

[0062] Magnetic test module

[0063] The working principle of the magnetic measurement ring of the deep in-situ high-fidelity testing system of this invention is as follows: multiple magnetic field coils are uniformly arranged on the inner wall of the electromagnetic measurement ring chamber 4. A pulsed magnetic field is emitted in a "two-transmitter, six-receiver" mode; during the interval of the pulsed magnetic field, the secondary induced eddy current field signal generated by the rock core in the test chamber is collected, and the decay law of the induced electromotive force over time is recorded.

[0064] For the emission current that conforms to the step function:

[0065] ;

[0066] The analytical expression for the induced electromotive force in a uniform half-space is:

[0067] ;

[0068] In the formula, Transmitting current as a function of time (A). Initial emission current (A). The effective area of ​​the receiving coil , : Send return line side length , Resistivity Magnetic permeability (H / m) Probability integral function The derivative of the probability integral function.

[0069] ;

[0070] Apparent resistivity ( )expression:

[0071] .

[0072] As an optional implementation, the temperature and pressure control unit includes a high-pressure pipeline 19, an inlet 7 on the magnetic ring chamber 4, an outlet 6 on the acoustic ring chamber 2, and the two ends of the high-pressure pipeline 19 are connected to the outlet 6 and the inlet 7 respectively. A high-pressure plunger pump 20 and a mold temperature controller 21 are installed on the high-pressure pipeline 19.

[0073] In one embodiment of the present invention, the temperature and pressure control unit comprises a high-pressure plunger pump 20, a mold temperature controller 21, an air-cooled unit, a high-precision pressure sensor, and a PID control system, forming a closed-loop control system. Before testing, deionized water is injected into the chamber via the high-pressure plunger pump 20, establishing a closed circulation loop. The mold temperature controller 21 heats the water medium, while the air-cooled unit cools it as needed. The heating and cooling power are adjusted in real time using a PID intelligent algorithm to ensure that the internal temperature and pressure of the chamber simultaneously reach the target deep in-situ conditions. The system temperature can be stably controlled within the range of room temperature to 150°C, and the pressure is adjustable within the range of 0–140 MPa. To prevent medium leakage under high pressure, the system is equipped with multi-stage safety valves, pressure relief pipelines, and data interlock protection devices. In extreme cases, automatic pressure relief and shutdown protection can be achieved, enabling the maintenance of a stable high-temperature and high-pressure environment for extended periods.

[0074] As an optional implementation, the aviation socket structure includes several aviation plugs 8, which are respectively installed in the acoustic measurement ring chamber 2, the electrical measurement ring chamber 3 and the magnetic measurement ring chamber 4. The ultrasonic sensor 25, the DC sensor 26 and the transient electromagnetic sensor 27 are respectively connected to one end of the aviation plug 8, and the other end of the aviation plug 8 is connected to the external acoustic and electromagnetic data acquisition system 22.

[0075] In one embodiment of the present invention, the aviation socket structure mainly consists of an aviation connector 8, a high-temperature and high-pressure resistant aviation socket, and a multi-layer sealing ring. The aviation connector 8 serves as a signal transmission relay element, reliably transmitting the weak signals collected by sensors inside the cabin to the external acoustic-electromagnetic data acquisition system 22. The aviation socket uses a nickel-based alloy shell and a ceramic insulating core, maintaining excellent signal stability under high temperature, high pressure, and strong electromagnetic interference environments. The sealing ring is composed of a composite structure of fluororubber and a metal gasket, effectively preventing leakage of high-temperature media. The external connection end achieves safe separation of data and power through a quick-plug aviation connector, facilitating maintenance and replacement. This structure ensures signal integrity and system safety under complex experimental environments.

[0076] As an optional implementation, the shifting unit includes a track shifting system 14, with a gate valve 11 fixedly connected to the top. Both sides of the gate valve 11 are provided with clamping mechanisms 13, which are respectively connected to the core extractor 12 and the cabin. The core extractor 12 is used to transport the core sample 24 to the test space.

[0077] In one embodiment of the present invention, the core sample 24 is transported to the test space by the docking core extractor 12.

[0078] As an optional implementation, guide rings 18 and sealing gaskets are provided between the acoustic ring chamber 2 and the electrical ring chamber 3, as well as between the electrical ring chamber 3 and the magnetic ring chamber 4.

[0079] In one embodiment of the present invention, the guide ring 18 ensures high coaxiality of each section of the chamber during assembly, so that the rock core can pass smoothly during the pushing process.

[0080] A method for acoustic-electromagnetic fidelity testing of rock parameters in deep in-situ environments includes the following steps:

[0081] The displacement unit containing core sample 24 was sealed and docked with the cabin.

[0082] The temperature and pressure control unit is activated to adjust the temperature and pressure inside the chamber to reach the preset target value for the deep in-situ environment and maintain it stable.

[0083] After the temperature and pressure environment stabilizes, the core sample 24 is pushed into the chamber, and the ultrasonic signal, electrical signal and transient electromagnetic signal of the core sample 24 are collected by the acousto-electromagnetic test module.

[0084] Based on the collected ultrasonic signals, electrical signals and transient electromagnetic signals, the wave velocity, resistivity and apparent resistivity of core sample 24 were calculated, and the elastic modulus, porosity and hydrocarbon content parameters of core sample 24 were obtained by inversion using wave velocity, resistivity and apparent resistivity.

[0085] In one embodiment of the present invention, during use:

[0086] Initial state calibration before relocation: pre-calibrate the coaxiality of the cabin and relocation unit. Perform zero-point / full-scale calibration on each of the pressure, temperature, level, displacement, and limit switch. Conduct no-load tests on the PID control, over-limit alarm, emergency stop, and pressure relief valve interlock to confirm that the interlock trigger time is ≤200ms. Test the continuity and insulation resistance of the aviation socket, aviation plug 8, and acoustic-electromagnetic data acquisition system (≥100MΩ@500VDC). Record the sensor no-load noise baseline to provide a reference for subsequent noise subtraction and drift determination.

[0087] The test chamber docking and sealing connection uses a servo slide / linear module to move gate valve 11 to the preset coordinates, avoiding scratching the sealing surface; monitoring the axial thrust curve to find a balance plateau indicates that the flange end face fit is complete. Pre-tightening is performed in two stages (30%→70% of design torque) in a "diagonal-cloverleaf" sequence, and coaxiality is re-measured; finally, tightening is performed to 100% of the design torque, and the torque of each bolt is recorded; if necessary, a 24-hour creep test is performed followed by a re-inspection. Cold-state leakage checks are conducted using low-pressure deionized water at 0.2MPa–0.5MPa, including visual dry inspection and paper tape leak testing; pressure is maintained for 10–15 minutes; only if there is no visible leakage and the pressure drop is ≤0.02MPa can the next step be performed.

[0088] The test chamber's temperature and pressure environment is established by starting the high-pressure plunger pump 20 and injecting deionized water (conductivity ≤1μS / cm, filtration ≤5μm) into the test chamber via the high-pressure pipeline 19. A circulation pump establishes a loop flow rate (typically 2–6L / min) to eliminate dead zones and temperature gradients. Data is collected in real-time by a high-precision pressure sensor inside the chamber; a step increase indicates full filling. The target temperature and pressure (upper limit 150℃, 140MPa) are input into the temperature and pressure control interface. The mold temperature controller 21 is started for rapid heating; simultaneously, the air-cooled unit is activated for overshoot suppression and steady-state maintenance. After entering the constant temperature and pressure phase, data is recorded for 10–15 minutes. At this time, the following conditions should be met: temperature fluctuation peak—peak value ≤ ±0.5℃ (preferably ±0.3℃); pressure fluctuation peak—peak value ≤ ±0.3MPa (preferably ±0.2MPa). A temperature and pressure steady-state determination record (curve + statistics) is generated as an admission criterion.

[0089] Double-check that the steady-state conditions of T and P meet the criteria from the previous step; verify the temperature / pressure difference between the coring unit 12 and the chamber: |ΔT|≤1℃, |ΔP|≤0.3MPa (if not met, make minor adjustments at the coring unit 12 end first). Remotely open the gate valves in stages from the central control room to suppress transient shocks; monitor transient fluctuations in the temperature and pressure curves, allowing for short-term fluctuations. Continue monitoring until the fluctuations naturally decay and a new steady state is reached; the steady state must be maintained for ≥5 minutes before core pushing can begin.

[0090] The remotely activated displacement unit is pushed at a uniform speed of v = 2–10 mm / s; the allowable positioning error is ≤ ±0.5 mm; after reaching the desired position, it is allowed to stand still for 2–3 minutes to allow temperature and pressure disturbances to stabilize again (same as the above steady-state criterion). The ultrasonic transmitting probe is triggered, and the receiving end collects reflected / transmitted signals; each set of parameters is repeated 3 times, anomalies are eliminated, and the mean and standard deviation are taken; the acoustic waveform, arrival time, and other parameters are output. A stable DC / low-frequency square wave is applied, different electrode combinations are scanned, and the potential and current responses are measured; the apparent resistivity is calculated, and the dielectric conductivity and polarization drift are recorded simultaneously to subtract background effects; each operating condition is repeated 3 times, and the mean ± confidence interval is output. A single pulse excitation is performed on the ungrounded loop, and the secondary eddy current decay curve is measured during the pulse interval; the time domain response is logarithmically divided and sampled / superimposed to improve the signal-to-noise ratio; the apparent resistivity value is obtained through inversion.

[0091] All tests are triggered synchronously in the central control room and recorded on the same timescale and temperature / pressure recording channel. Quality thresholds are set; if not met, the connectors / shielding / grounding and temperature / pressure stability are checked before retesting. A chain record of original waveform / response—processing—inversion—report is automatically generated, and the corresponding T and P steady-state windows and statistical confidence intervals are marked.

[0092] The elastic modulus is inverted from wave velocity. Based on wave velocity, resistivity, and apparent resistivity obtained from acoustic, electrical, and magnetic tests, and combined with theoretical formulas, the in-situ physical and mechanical parameters of rocks are inverted. The core derivation is as follows:

[0093] The wave velocity in the rock core obtained from the acoustic ring, combined with Hooke's Law, can be obtained as follows:

[0094] ;

[0095] From the impulse theorem, we can obtain:

[0096] ;

[0097] When rock is subjected to longitudinal stress, it will undergo lateral shrinkage, and a lateral shrinkage coefficient (i.e., Poisson's ratio) needs to be introduced. Considering the effect of lateral contraction, a lateral contraction coefficient is introduced:

[0098] ;

[0099] The core elastic modulus can be obtained as follows:

[0100] ;

[0101] in, Stress (Pa) Apparent elastic modulus (Pa). Strain (dimensionless) Force (N) Area of ​​force application (m²) Duration of action (s) Mass (kg) Change in velocity (m / s) Lateral contraction coefficient (dimensionless). Poisson's ratio (dimensionless). True elastic modulus (Pa). Longitudinal wave velocity (m / s).

[0102] Porosity and hydrocarbon content can be derived from resistivity. Rock resistivity is a key parameter characterizing the electrical properties of rocks. Its value is controlled by a variety of internal and external factors, among which the porosity of the rock and the hydrocarbon content (saturation) in the pore fluid are the decisive factors.

[0103] Using the above system, the resistivity of pore fluids that can enter the rock without a core sample is first tested. Then, the resistivity of the obtained core sample is tested, and the porosity of the rock can be estimated using Archie's formula.

[0104] ;

[0105] In the formula Porosity of the core sample (dimensionless). The lithology coefficient (dimensionless) is related to the curvature and cementation of rock particles, and is usually between 0.6 and 1.0. The cementation index (dimensionless) is related to the degree of cementation and the complexity of the pore structure of the rock, and is usually between 1.8 and 2.2. Resistivity of pore fluid ; To preserve the resistivity of the rock core .

[0106] Further, the water saturation of the core sample can be obtained:

[0107] ;

[0108] In the formula, Water saturation (dimensionless). True resistivity of rock core

[0109] If the rock core contains only oil and water:

[0110] ;

[0111] Oil saturation is usually expressed as The value is expressed as dimensionless, which gives the oil volume fraction of the core sample.

[0112] If the core contains only gas and water:

[0113] ;

[0114] Gas content is usually expressed as The dimensionless value indicates that the gas content integral of the core sample can be obtained.

[0115] Verified by apparent resistivity test

[0116] The apparent resistivity of the rock core sample calculated based on the transient electromagnetic test results can be used to further verify the resistivity results obtained by the DC resistivity method, and together the results of in-situ physical and mechanical parameters of the rock can be obtained.

[0117] By controlling the temperature and pressure parameters inside the test chamber and comparing the changes in physical and mechanical parameters under different conditions, the influence of the deep in-situ environment on the mechanical behavior of rocks is revealed:

[0118] Set the pressure inside the test chamber to a fixed value (e.g., 100 MPa), and use a PID algorithm to set the temperature gradient (20℃→150℃, with a temperature gradient of 10℃). After each temperature setting stabilizes for 6 hours (with fluctuation range ≤±1℃), maintain this temperature condition for subsequent tests.

[0119] Based on the physical property parameters of the core obtained from the test, the core's elastic modulus, porosity, hydrocarbon content, and other physical and mechanical parameters are inverted and solved to analyze the changes in the core's physical and mechanical parameters after the temperature increases.

[0120] With the test chamber temperature fixed, a pressure gradient was set (0MPa→140MPa, gradient of 10MPa). After each pressure level stabilized for 3 hours (fluctuation range...), ), and maintain this pressure condition for subsequent testing.

[0121] Similarly, the acoustic and electromagnetic signals of the core sample are tested, the values ​​of the physical properties of the core sample are calculated, and the physical and mechanical parameters of the core are further obtained by inversion. The change law of the physical and mechanical parameters of the core after the pressure increases is analyzed.

[0122] As an optional implementation, it also includes a step of analyzing the influence of temperature and pressure, which involves conducting multiple sets of comparative tests by changing the temperature and pressure parameters in the chamber.

[0123] In one embodiment of the present invention, the combined values ​​of temperature and pressure under different burial depths are determined based on the variation law of temperature and pressure with burial depth in the in-situ environment of deep rock. Multiple sets of temperature-pressure coupling conditions are set through the system's temperature and pressure control unit. The relationship between temperature-pressure coupling changes and burial depth can be approximately referenced in Table 1. A bidirectional temperature and pressure feedback control mode is used. After the temperature and pressure under each set of conditions have stabilized for more than 3 hours, with temperature fluctuations ≤ ±1℃ and pressure fluctuations ≤ ±0.5MPa, subsequent tests are conducted.

[0124] Table 1. Approximate Correspondence between Rock Temperature and Pressure and Burial Depth in Deep In-situ Environments

[0125] Serial Number Burial depth (m) Temperature estimate (°C) Pressure estimate (MPa) 1 0 15.0 0.0 2 500 28.8 12.5 3 1000 42.5 25.0 4 1500 56.3 37.5 5 2000 70.0 50.0 6 2500 83.8 62.5 7 3000 97.5 75.0 8 3500 111.3 87.5 9 4000 125.0 100.0 10 4500 138.8 112.5 11 5000 152.5 125.0 12 5500 166.3 137.5 13 6000 180.0 150.0

[0126] As an optional implementation, when collecting ultrasonic signals, electrical signals and transient electromagnetic signals of core sample 24 through the acoustic electromagnetic testing module, each set of parameters is tested at least three times, and the average value is taken as the final test result.

[0127] In one embodiment of the present invention, the test is repeated three times under each temperature condition. If there is no significant difference, the average value is selected as the measured value at that temperature. When the test values ​​of different groups differ greatly, the number of test groups is increased, and the average value of the three groups with little difference is selected.

[0128] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0129] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A deep in-situ environmental rock parameter acoustic electromagnetic fidelity testing system, characterized in that, The application relates to a deep in-situ environment test device for rock core samples. The device comprises a cabin body, a temperature and pressure control unit, and an acoustic electromagnetic test module. The cabin body is internally formed with a test space, and a rock core sample (24) enters the test space from one end of the cabin body through a displacement unit. The temperature and pressure control unit is in communication with the cabin body, and the temperature and pressure in the cabin body are adjusted to reach preset deep in-situ environment target values and remain stable by starting the temperature and pressure control unit. The acoustic electromagnetic test module is arranged in the cabin body, and ultrasonic signals, electric signals and transient electromagnetic signals of the rock core sample (24) are collected through the acoustic electromagnetic test module.

2. The system of claim 1, wherein: The acoustic electromagnetic test module is connected with an external acoustic electromagnetic data collection system (22).

3. The system of claim 2, wherein: The temperature and pressure control unit is electrically connected with the acoustic electromagnetic test module and the remote control system (23).

4. The system of claim 2, wherein: The cabin body comprises a conversion flange (1), an acoustic measurement ring cabin body (2), an electric measurement ring cabin body (3), a magnetic measurement ring cabin body (4) and a bottom plate (5) arranged in sequence.

5. The system of claim 3, wherein: The conversion flange (1), the acoustic measurement ring cabin body (2), the electric measurement ring cabin body (3), the magnetic measurement ring cabin body (4) and the bottom plate (5) are spliced into an integral structure through a plurality of screw rods (9) and a plurality of threads and nuts (10). The acoustic electromagnetic test module comprises an ultrasonic detection module (15), an electric method test module (16) and a transient electromagnetic detection module (17). The ultrasonic detection module (15) comprises a plurality of ultrasonic sensors (25) fixedly connected in the acoustic measurement ring cabin body (2) at equal intervals in the circumferential direction. The electric method test module (16) comprises a plurality of direct current sensors (26) fixedly connected in the electric measurement ring cabin body (3) at equal intervals in the circumferential direction. The transient electromagnetic detection module (17) comprises a plurality of transient electromagnetic sensors (27) fixedly connected in the magnetic measurement ring cabin body (4) at equal intervals in the circumferential direction. The temperature and pressure control unit comprises a high-pressure pipeline (19). The magnetic measurement ring cabin body (4) is provided with a water inlet (7), and the acoustic measurement ring cabin body (2) is provided with a water outlet (6). The high-pressure pipeline (19) is provided with a high-pressure plunger pump (20) and a mold temperature machine (21). The device further comprises a plurality of navigation plug columns (8) arranged in the acoustic measurement ring cabin body (2), the electric measurement ring cabin body (3) and the magnetic measurement ring cabin body (4) respectively. The ultrasonic sensors (25), the direct current sensors (26) and the transient electromagnetic sensors (27) are connected with one end of the navigation plug columns (8) respectively. The other end of the navigation plug columns (8) is connected with the external acoustic electromagnetic data collection system (22).

6. The system of claim 1, wherein: The displacement unit comprises a track displacement system (14), a gate valve (11) fixedly connected to the top end, gripping mechanisms (13) arranged on both sides of the gate valve (11), and core extractors (12) and the cabin body respectively connected to the two gripping mechanisms (13), wherein the core extractors (12) are used to deliver the core sample (24) into the test space.

7. The system of claim 2, wherein: A guide ring (18) and a sealing gasket are arranged between the acoustic logging ring cabin body (2) and the electrical logging ring cabin body (3) and between the electrical logging ring cabin body (3) and the magnetic logging ring cabin body (4).

8. A method for deep in-situ environmental rock parameter acoustic electromagnetic fidelity testing, applicable to the deep in-situ environmental rock parameter acoustic electromagnetic fidelity testing system of any one of claims 1-7, characterized in that, The method comprises the following steps: The displacement unit loaded with the core sample (24) is sealed and docked with the cabin body. The temperature and pressure control unit is started to adjust the temperature and pressure in the cabin body to reach the preset deep in-situ environment target value and keep stable, and after the temperature and pressure environment is stable, the core sample (24) is pushed into the cabin body. The ultrasonic signal, the electrical signal and the transient electromagnetic signal of the core sample (24) are collected by the acoustic-electromagnetic test module, and the wave velocity, the resistivity and the apparent resistivity of the core sample (24) are calculated based on the collected ultrasonic signal, the electrical signal and the transient electromagnetic signal. The elastic modulus, the porosity and the oil and gas content parameters of the core sample (24) are obtained by wave velocity, resistivity and apparent resistivity inversion.

9. The method of claim 8, wherein: The temperature and pressure influence law analysis step is further included, and a plurality of groups of comparative tests are performed by changing the temperature and pressure parameters in the cabin body.

10. The method of claim 8, wherein: When the acoustic-electromagnetic test module collects the ultrasonic signal, the electrical signal and the transient electromagnetic signal of the core sample (24), each group of parameter test is repeated at least three times, and the average value is taken as the final test result.

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