Method for predicting rock mechanics parameters of hydrate-bearing sediments based on broadband electrical parameters

Abstract

The application discloses a hydrate deposit rock mechanics parameter prediction method based on a wide-frequency electric parameter, and first determines an electric parameter measurement method and a combined measurement method of mechanics tests, obtains impedance of hydrate porous media by applying different frequency excitation signals to electrodes, and calculates corresponding complex resistivity according to the size and distance of the electric sensor and the impedance of the hydrate porous media, and simultaneously obtains mechanics parameters of the hydrate porous media through the mechanics tests. According to the obtained complex resistivity and mechanics parameters, a mechanics parameter prediction model is established by using linear fitting, polynomial fitting and neural network methods. The application combines various electric measurement methods with various mechanics tests, so as to establish an accurate mechanics parameter prediction model, and can be widely applied to the technical field of data processing.

Description

Technical Field

[0001] The present invention relates to the technical field of data processing, and in particular to a method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters. Background Art

[0002] Rock mechanical parameters are critical data in geological exploration and engineering development, particularly in hydrate-bearing reservoirs, where they directly impact reservoir stability and extraction safety. Natural gas hydrates, an unconventional energy resource with enormous potential, are primarily found in high-pressure, low-temperature marine and continental margins and permafrost regions. Because hydrate decomposition during extraction can lead to formation instability and increase extraction risks, accurate prediction of rock mechanical parameters is crucial for the development of hydrate resources.

[0003] In traditional rock mechanics research, in-situ measurement of rock mechanical parameters is difficult, and laboratory mechanical experiments, such as triaxial tests and unconfined compression tests, are often used to determine them. While accurate, these methods are often time-consuming and costly, especially in large-scale geological exploration or deep underground engineering projects, where the difficulty and cost of testing are even greater. Summary of the Invention

[0004] The present invention aims to address, at least to some extent, the limitations of related technologies. To this end, the present invention proposes a method for predicting rock mechanical parameters of hydrate-bearing sediments based on broadband electrical parameters, which can conveniently predict rock mechanical parameters of hydrate-bearing sediments based on broadband electrical parameters.

[0005] In one aspect, an embodiment of the present invention provides a method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters, comprising the following steps:

[0006] Acquire a sample set; the sample set includes samples of multiple hydrate-bearing sediment rocks with different saturations;

[0007] The shear strength of each sample in the sample set is measured in sequence under different axial stresses based on the first mechanical test, and the impedance corresponding to each sample in different states is obtained by synchronously and jointly measuring based on the first electrical measurement method, thereby obtaining first correlation data of the impedance and shear strength of each sample;

[0008] The compressive strength and the corresponding axial strain of each sample in the sample set are measured sequentially based on the second mechanical test, and the impedance corresponding to each sample is simultaneously measured based on the second electrical measurement method to obtain second correlation data between the impedance and the compressive strength of each sample; the compressive strength is determined based on the axial stress applied by the second mechanical test;

[0009] Based on the geometric parameters of the electrical sensor applied by the electrical measurement method and the impedance, the resistivity corresponding to the sample in different states is obtained; the electrical measurement method includes a first electrical measurement method and a second electrical measurement method;

[0010] Based on the resistivity corresponding to the sample in different states, the first correlation data is converted into third correlation data of the resistivity and shear strength of the sample, and the second correlation data is converted into fourth correlation data of the resistivity and compressive strength;

[0011] Based on the test results of the first mechanical test, a first correlation curve between shear strength and axial stress is constructed, and then, based on the Coulomb shear strength theory, the internal friction angle and cohesion corresponding to the shear strength of the sample under different axial stresses are obtained; and based on the third correlation data, fifth correlation data between the resistivity and internal friction angle of the sample and sixth correlation data between the resistivity and cohesion are obtained;

[0012] Based on the test results of the second mechanical test, a second correlation curve of axial strain and axial stress is constructed, and the compression modulus of the sample corresponding to the axial strain under different axial stresses is obtained according to the slope of the second correlation curve; and seventh correlation data of the resistivity and compression modulus of the sample are obtained according to the fourth correlation data;

[0013] Performing data fitting on the third correlation data, the fourth correlation data, the fifth correlation data, the sixth correlation data, and the seventh correlation data to obtain a mechanical parameter prediction model; the mechanical parameter prediction model includes a shear strength prediction model, a compressive strength prediction model, an internal friction angle prediction model, a cohesion prediction model, and a compression modulus prediction model;

[0014] The mechanical parameter prediction model is used to predict the mechanical parameters of the rock to be predicted based on the resistivity of the rock to be predicted.

[0015] On the other hand, an embodiment of the present invention provides an electronic device, comprising: a processor and a memory; the memory is used to store programs; the processor executes the program to implement the above-mentioned method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters.

[0016] On the other hand, an embodiment of the present invention provides a computer storage medium storing a program executable by a processor. When executed by the processor, the program executable by the processor is used to implement the above-mentioned method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters.

[0017] The embodiment of the present invention obtains a sample set; the sample set includes samples of hydrate-containing sediment rocks with multiple different saturations; based on a first mechanical test, the shear strength of each sample in the sample set under different axial stresses is measured in sequence, and based on a first electrical measurement method, the impedance corresponding to each sample in different states is synchronously and jointly measured to obtain first correlation data of the impedance and shear strength of each sample; based on a second mechanical test, the compressive strength and the corresponding axial strain of each sample in the sample set are measured in sequence, and based on the second electrical measurement method, the impedance corresponding to each sample is synchronously and jointly measured to obtain second correlation data of the impedance and compressive strength of each sample; the compressive strength is determined based on the axial stress applied by the second mechanical test; based on the geometric parameters of the electrical sensor applied by the electrical measurement method and the impedance, the resistivity corresponding to the sample in different states is obtained; the electrical measurement method includes a first electrical measurement method and a second electrical measurement method; based on the resistivity corresponding to the sample in different states, the first correlation data is converted into third correlation data of the resistivity and shear strength of the sample, and the second correlation data is converted into third correlation data of the resistivity and compressive strength Four related data; based on the test results of the first mechanical test, a first related curve of shear strength and axial stress is constructed, and then according to the Coulomb shear strength theory, the internal friction angle and cohesion corresponding to the shear strength of the sample under different axial stresses are obtained; then according to the third related data, fifth related data of the resistivity and internal friction angle of the sample and sixth related data of the resistivity and cohesion are obtained; based on the test results of the second mechanical test, a second related curve of axial strain and axial stress is constructed, and according to the slope of the second related curve, the compression modulus corresponding to the axial strain of the sample under different axial stresses is obtained; then according to the fourth related data, seventh related data of the resistivity and compression modulus of the sample are obtained; data fitting is performed on the third related data, the fourth related data, the fifth related data, the sixth related data and the seventh related data to obtain a mechanical parameter prediction model; the mechanical parameter prediction model includes a shear strength prediction model, a compressive strength prediction model, an internal friction angle prediction model, a cohesion prediction model and a compression modulus prediction model; wherein, the mechanical parameter prediction model is used to predict the mechanical parameters of the rock to be predicted based on the resistivity of the rock to be predicted. This method combines electrical parameter measurement with mechanical testing to measure various mechanical parameters of hydrate-containing porous media. The impedance of the hydrate-containing porous media is then simultaneously determined using electrical measurement. The corresponding resistivity is then calculated based on the size and distance of the electrical sensor and the impedance of the hydrate-containing porous media, yielding electrical-mechanical correlation data. Finally, a mechanical parameter prediction model is established using data fitting based on the experimentally obtained resistivity and mechanical parameters.The present invention constructs a prediction model by associating the data of fitted electrical parameters and mechanical parameters, and then in the subsequent rock mechanical parameter prediction based on the mechanical parameter prediction model, it can conveniently realize the mechanical parameter prediction based on the wide-band electrical parameters of the rock and realize recycling, avoiding the tediousness of the traditional method of relying purely on mechanical measurements and having to re-perform mechanical tests every time. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the technical solution of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the technical solution of the present invention and do not constitute a limitation to the technical solution of the present invention.

[0019] Figure 1 A schematic flow chart of a method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters provided by an embodiment of the present invention;

[0020] Figure 2 A schematic diagram of a combined measurement of a contact-type two-electrode method and a direct shear test provided in an embodiment of the present invention;

[0021] Figure 3a A side view schematic diagram of a combined measurement of a contact-type two-electrode method and a ring shear test provided in an embodiment of the present invention;

[0022] Figure 3b A schematic top view of a combined measurement of a contact-type two-electrode method and a ring shear test provided in an embodiment of the present invention;

[0023] Figure 4 Schematic diagram of the non-contact two-electrode method and direct shear test combined measurement provided by an embodiment of the present invention;

[0024] Figure 5a A side view schematic diagram of a non-contact two-electrode method and a ring shear test combined measurement according to an embodiment of the present invention;

[0025] Figure 5b A schematic top view of a non-contact two-electrode method and a ring shear test combined measurement according to an embodiment of the present invention;

[0026] Figure 6a A side view schematic diagram of a non-contact Van der Pauw method and ring shear test combined measurement provided by an embodiment of the present invention;

[0027] Figure 6b A schematic top view of a non-contact Van der Pauw method and ring shear test combined measurement according to an embodiment of the present invention;

[0028] Figure 7 A schematic diagram of a combined measurement of a contact-type two-electrode method and a triaxial test provided in an embodiment of the present invention;

[0029] Figure 8 A schematic diagram of a non-contact two-electrode method and a triaxial test combined measurement according to an embodiment of the present invention;

[0030] Figure 9a A side view schematic diagram of a combined measurement of a contact-type three-electrode method and an unconfined compression test provided in an embodiment of the present invention;

[0031] Figure 9b A schematic top view of a combined measurement of a contact-type three-electrode method and an unconfined compression test according to an embodiment of the present invention;

[0032] Figure 10a A schematic side view of a combined measurement of the contact-type Van der Pauw method and the unconfined compression test provided in an embodiment of the present invention;

[0033] Figure 10b A schematic top view of a combined measurement of the contact-type Van der Pauw method and the unconfined compression test provided in an embodiment of the present invention;

[0034] Figure 11 A schematic diagram of a combined measurement of a contact-type four-probe method and a triaxial test provided in an embodiment of the present invention;

[0035] Figure 12 A schematic diagram of a process for establishing a mechanical parameter prediction model according to an embodiment of the present invention;

[0036] Figure 13 A schematic diagram of the relationship between the real part of complex resistivity and shear strength under different axial pressures provided by an embodiment of the present invention;

[0037] Figure 14 A schematic diagram of the relationship between the imaginary part of complex resistivity and shear strength under different axial pressures provided by an embodiment of the present invention;

[0038] Figure 15 A schematic diagram of the relationship between the real part of complex resistivity and the internal friction angle provided in an embodiment of the present invention;

[0039] Figure 16 A schematic diagram of the relationship between the imaginary part of complex resistivity and the internal friction angle provided by an embodiment of the present invention;

[0040] Figure 17 A schematic diagram of the relationship between the real part of complex resistivity and cohesion provided by an embodiment of the present invention;

[0041] Figure 18 A schematic diagram of the relationship between the imaginary part of complex resistivity and cohesion provided by an embodiment of the present invention;

[0042] Figure 19 A schematic diagram of the relationship between the real part of complex resistivity and compressive strength provided by an embodiment of the present invention;

[0043] Figure 20 A schematic diagram of the relationship between the imaginary part of complex resistivity and compressive strength provided by an embodiment of the present invention;

[0044] Figure 21 A schematic diagram of the relationship between the real part of complex resistivity and the compression modulus provided in an embodiment of the present invention;

[0045] Figure 22 A schematic diagram of the relationship between the imaginary part of complex resistivity and the compression modulus provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0047] It should be noted that although the system diagrams illustrate functional module divisions and the flowcharts illustrate a logical sequence, in certain circumstances, the steps shown or described may be performed in a sequence that differs from the module divisions in the system or the sequence in the flowcharts. The terms "first / S100," "second / S200," and the like in the specification, claims, and drawings are used to distinguish similar objects and are not necessarily intended to describe a specific sequence or precedence.

[0048] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute a separate or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0049] To facilitate understanding of the technical solutions of the present invention, the meanings of the parameters that may be cited in the embodiments of the present invention and their technical principles are first explained:

[0050] Electrical parameter measurement methods and mechanical tests:

[0051] 1) Electrical measurement method:

[0052] As shown in Table 1, the electrical measurement methods involved in the present invention are divided into two categories: contact and non-contact. The contact electrical measurement methods include the two-electrode method, the three-electrode method, the Van der Pauw method and the four-probe method. The non-contact electrical measurement methods include the two-electrode method and the Van der Pauw method.

[0053] Table 1

[0054]

[0055] 2) Mechanical test:

[0056] As shown in Table 2, the mechanical tests involved in the present invention include direct shear test, ring shear test, triaxial test and unconfined compression test.

[0057] Table 2

[0058]

[0059] Reference Figure 1 , Figure 1 The flowchart of the method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters applied to a server provided in an embodiment of the present invention is provided. The execution subject of the method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters can be any of the aforementioned computer devices (including servers or terminals). Figure 1 , the method comprises the following steps:

[0060] S100, obtaining a sample set; the sample set includes a plurality of samples of hydrate-containing sediment rocks with different saturations;

[0061] S200, sequentially measuring the shear strength of each sample in the sample set under different axial stresses based on the first mechanical test, and synchronously and jointly measuring the impedance of each sample under different states based on the first electrical measurement method, to obtain first correlation data between the impedance and the shear strength of each sample;

[0062] It should be noted that, in some embodiments, step S200 may include the following steps: measuring the shear strength of each sample in the sample set under different axial stresses in sequence through a direct shear test, and obtaining the impedance corresponding to each sample in different states through a synchronous joint measurement based on a contact two-electrode method through an impedance analyzer, and obtaining the first correlation data of the impedance and shear strength of each sample; wherein, a single direct shear test applies a fixed axial stress to the sample, and continuously shears the sample at a preset shear rate until the shear stress reaches a first preset condition during the shear treatment, determines the shear strength according to the shear stress, and performs synchronous joint measurement based on the contact two-electrode method through an impedance analyzer.

[0063] For example, in some embodiments, the contacting two-electrode method is combined with the direct shear test to measure the resistivity of the sample in relation to the shear strength, cohesion and internal friction angle. Figure 2 As shown ( Figure 2 The corresponding meanings of the reference numerals are: 1—upper electrode plate; 2—insulating sleeve; 3—piston; 4—platform; 5—sample; 6—lower electrode plate). The application principle of the combined measurement of the contact two-electrode method and the direct shear test is as follows:

[0064] By applying current to the upper and lower electrode plates and measuring the voltage drop, the resistance R of the sample can be measured according to Ohm's law:

[0065]

[0066] Where: U is the voltage and I is the current through the sample.

[0067] The resistivity of the sample can be calculated according to the following formula:

[0068]

[0069] Where: A1 is the equivalent contact area of ​​the electrodes, and L is the distance between the electrodes (equivalent to the sample thickness).

[0070] At the same time, a vertical load is applied to the sample, and a lateral stress is applied to the upper part of the sample through the piston, while the platform fixes the lower part of the sample, forcing the sample to shear failure on a specific plane, thereby measuring the shear strength of the sample. According to Coulomb shear strength theory, the shear strength τ of the sample can be expressed as:

[0071]

[0072] Where: τ is the shear strength of the sample, c is the cohesion of the sample, and σ is the normal stress; is the internal friction angle of the sample, representing the effect of friction between soil particles.

[0073] The specific experimental steps can be implemented as follows:

[0074] ① The lower electrode plate, insulating sleeve and platform are integrated. Hydrate sediments are added to the insulating sleeve while being compacted. After the sample fills the insulating sleeve, the upper electrode plate is placed on the sample and pressed repeatedly to ensure full contact between the electrode and the sample.

[0075] ② Use an impedance analyzer to apply AC excitation signals of different frequencies to the two electrodes and simultaneously measure the output signals of the two electrodes to obtain the sample impedance. Apply an axial stress of 50kPa to the sample and keep it constant. Allow the piston to shear at a rate of 1mm / min. When the shear stress reading reaches a stable level or shows a significant retreat, it indicates that the sample has been sheared. Shearing should be continued until the shear deformation reaches 4mm. When the shear stress reading continues to increase, the shear deformation should reach 6mm. The shear stress at this point is the shear strength, and the sample impedance at this point is measured simultaneously.

[0076] ③ Change the axial stress applied to the sample to 100kPa, 150kPa, and 200kPa, repeat experimental steps ① and ② in sequence, and record the measured impedance and shear strength.

[0077] ④ Change the saturation of the sample, repeat steps ①, ②, and ③, and record the measured sample impedance and shear strength.

[0078] It should be noted that, in some embodiments, step S200 may further include the following steps: measuring the shear strength of each sample in the sample set under different axial stresses in sequence through a ring shear test, and obtaining the impedance corresponding to each sample in different states through a synchronous joint measurement based on a contact two-electrode method through an impedance analyzer, and obtaining first correlation data of the impedance and shear strength of each sample; wherein, a single ring shear test applies a fixed axial stress to the sample, and continuously shears the sample at a preset shear rate until the shear stress reaches a second preset condition during the shear treatment, determines the shear strength according to the shear stress, and performs synchronous joint measurement based on the contact two-electrode method through an impedance analyzer.

[0079] For example, in some embodiments, the contacting two-electrode method is combined with the ring shear test to measure the resistivity of the sample in relation to the shear strength, cohesion and internal friction angle. Figure 3a (side view) and Figure 3b (Top view) Figure 3a and Figure 3b The corresponding meanings of the reference numerals are: 1—upper electrode plate; 2—sample box; 3—sample; 4—lower electrode plate). The application principle of the contact two-electrode method and the ring shear test combined measurement is as follows:

[0080] The upper and lower sample boxes are fixed to the upper and lower electrodes respectively. By applying current to the upper and lower electrodes and measuring the voltage drop, the resistivity of the ring sample can be obtained according to formula (1) and formula (2).

[0081] A vertical load is applied to the sample, and the sample box is rotated to apply hoop stress to the sample, causing shear deformation of the sample, thereby measuring the shear strength of the sample. Similar to the direct shear test, the ring shear test results are explained by formula (3).

[0082] The specific experimental steps can be implemented as follows:

[0083] ① The upper and lower electrode plates are integrated with the upper and lower sample boxes respectively. The sample is made into a ring sample according to the size of the sample box and placed in the lower sample box. The upper sample box is covered and pressed repeatedly to ensure full contact between the electrode and the sample.

[0084] ② Use an impedance analyzer to apply AC excitation signals of different frequencies to the two electrodes and simultaneously measure the output signals of the two electrodes to obtain the sample's impedance. Apply a constant axial stress of 50kPa to the sample and shear the lower sample box at a rate of 1° / min. When the shear stress reading decreases, it indicates that the sample has been sheared. The shear stress at this point is the shear strength, and the sample impedance at this point is also measured and calculated.

[0085] ③ Change the axial stress applied to the sample to 100kPa, 150kPa, and 200kPa, repeat experimental steps ① and ② in sequence, and record the measured sample impedance and shear strength.

[0086] ④ Change the saturation of the sample, repeat steps ①, ②, and ③, and record the measured sample impedance and shear strength.

[0087] It should be noted that, in some embodiments, step S200 may further include the following steps: measuring the shear strength of each sample in the sample set under different axial stresses in sequence through a direct shear test, and obtaining the impedance corresponding to each sample in different states through a synchronous joint measurement using an impedance analyzer based on a non-contact two-electrode method, and obtaining first correlation data of the impedance and shear strength of each sample; wherein, a single direct shear test applies a fixed axial stress to the sample, and continuously shears the sample at a preset shear rate until the shear stress reaches a third preset condition during the shear treatment, determines the shear strength according to the shear stress, and performs synchronous joint measurement based on the non-contact two-electrode method using an impedance analyzer.

[0088] For example, in some embodiments, the non-contact two-electrode method is combined with the direct shear test to measure the resistivity of the sample in relation to the shear strength, cohesion and internal friction angle. Figure 4 As shown ( Figure 4 The corresponding meanings of the reference numerals are: 1—insulating sleeve; 2—platform; 3—piston; 4—sample; 5—electrode). The application principle of the non-contact two-electrode method combined with the direct shear test is as follows:

[0089] The two electrodes are the excitation electrode and the detection electrode. When the sensor is working, an AC excitation signal u is applied to the excitation electrode. i At this time, the excitation electrode, the sample container wall and the sample to be tested will form a coupling capacitor C1; similarly, the detection electrode, the sample container wall and the sample to be tested will form a coupling capacitor C2. The two coupling capacitors C1 and C2 and the equivalent conductance R x An AC measurement path will be formed, and the output current i O It can be expressed as:

[0090]

[0091] Where f is the AC excitation signal u i The excitation frequency. Figure 4 As shown, connecting an inductor in series in the circuit can eliminate the influence of the coupling capacitor. The impedance of the sample can be obtained by an impedance analyzer, and then the resistivity of the sample can be calculated.

[0092] Transverse stress is applied to the sample through the piston. Similarly, the shear strength is measured when the sample is destroyed, and the cohesion and internal friction angle of the sample are calculated according to formula (3).

[0093] The specific experimental steps can be implemented as follows:

[0094] ① Add the sample to the insulating sleeve and compact it while adding. The two electrodes are made of conductive silver paint, which is applied to the outside of the insulating sleeve. They do not come into contact with the sample and will change with the shape of the insulating sleeve.

[0095] ② Impedance analysis involves applying AC excitation signals of varying frequencies to the upper electrode and measuring the sample impedance by detecting the output signal from the lower electrode. An axial stress of 50 kPa is applied to the sample and maintained constant. The piston is sheared at a rate of 1 mm / min. When the shear stress reading stabilizes or significantly retreats, the sample has been sheared. Shearing should be continued until the shear deformation reaches 4 mm. If the shear stress reading continues to increase, the shear deformation should reach 6 mm. This shear stress is the shear strength, and the sample impedance is measured at this point.

[0096] ③ Change the axial stress applied to the sample to 100kPa, 150kPa, and 200kPa, repeat experimental steps ① and ② in sequence, and record the measured sample impedance and shear strength.

[0097] ④ Change the saturation of the sample, repeat steps ①, ②, and ③, and record the measured sample impedance and shear strength.

[0098] It should be noted that, in some embodiments, step S200 may further include the following steps: measuring the shear strength of each sample in the sample set under different axial stresses in sequence through a ring shear test, and obtaining the impedance corresponding to each sample in different states through a synchronous joint measurement using an impedance analyzer based on a non-contact two-electrode method, to obtain first correlation data of the impedance and shear strength of each sample; wherein, a single ring shear test applies a fixed axial stress to the sample, and continuously shears the sample at a preset shear rate until the shear stress reaches a fourth preset condition during the shear treatment, determines the shear strength according to the shear stress, and performs synchronous joint measurement based on the non-contact two-electrode method using an impedance analyzer.

[0099] For example, in some embodiments, the non-contact two-electrode method is combined with the ring shear test to measure the resistivity of the sample in relation to the shear strength, cohesion and internal friction angle. Figure 5a and Figure 5b As shown ( Figure 5a and Figure 5b The corresponding meanings of the reference numerals are: 1—load plate; 2—sample box; 3—electrode; 4—sample). The application principle of the non-contact two-electrode method combined with the ring shear test is as follows:

[0100] As 5a and Figure 5b As shown, the upper electrode serves as an excitation electrode to apply an excitation signal, the lower electrode serves as an output electrode, and the series inductor eliminates the influence of the coupling capacitor. Similarly, the impedance of the sample is finally obtained by the impedance analyzer, and then the resistivity of the sample is calculated.

[0101] The hoop stress is applied to the sample through the loading plate. Similarly, the shear strength is measured when the sample is destroyed. The cohesion and internal friction angle of the sample are calculated according to formula (3).

[0102] The specific experimental steps can be implemented as follows:

[0103] ① Add the sample to the insulating sleeve and compact it while adding.

[0104] ② Using an impedance analyzer, apply AC excitation signals of varying frequencies to the upper electrode. Measure the sample impedance by detecting the output signal from the lower electrode, and then calculate the sample impedance. Apply a constant axial stress of 50 kPa to the sample, and shear the load plate at a rate of 1° / min. When the shear stress reading decreases, the sample has sheared. The shear stress at this point is the shear strength, and the sample impedance is measured simultaneously.

[0105] ③ Change the axial stress applied to the sample to 100kPa, 150kPa, and 200kPa, repeat experimental steps ① and ② in sequence, and record the measured sample impedance and shear strength.

[0106] ④ Change the saturation of the sample, repeat steps ①, ②, and ③, and record the measured sample impedance and shear strength.

[0107] It should be noted that, in some embodiments, step S200 may further include the following steps: measuring the shear strength of each sample in the sample set under different axial stresses in sequence through a ring shear test, and obtaining the impedance corresponding to each sample in different states through a synchronous joint measurement based on the non-contact Van der Pauw method through an impedance analyzer, and obtaining the first correlation data of the impedance and shear strength of each sample; wherein, a single ring shear test applies a fixed axial stress to the sample, and continuously shears the sample at a preset shear rate until the shear stress reaches a fifth preset condition during the shear treatment, determines the shear strength according to the shear stress, and performs synchronous joint measurement based on the non-contact Van der Pauw method through an impedance analyzer.

[0108] For example, in some embodiments, the non-contact Van der Pauw method is combined with the ring shear test to measure the resistivity of the sample in relation to shear strength, cohesion and internal friction angle. Figure 6a and Figure 6b As shown ( Figure 6a and Figure 6b The corresponding meanings of the reference numerals are: 1—load plate; 2—sample; 3—sample box; 4—electrode sheet). The application principle of the non-contact two-electrode method combined with the ring shear test is as follows:

[0109] Such as 6a and Figure 6b As shown, four metal electrodes, designated 1, 2, 3, and 4, are placed outside the insulating sample box. Adjacent metal electrodes 1 and 2 serve as excitation electrodes, connected to an excitation source. Metal electrodes 3 and 4 serve as detection electrodes, connected to a signal processing and acquisition module. Applying an AC voltage to the two excitation electrodes generates an AC voltage output signal at the two detection electrodes. The signal amplitude varies with resistivity. Finally, an impedance analyzer is used to determine the sample impedance, from which the resistivity is calculated.

[0110] The hoop stress is applied to the sample through the loading plate. Similarly, the shear strength is measured when the sample is destroyed. The cohesion and internal friction angle of the sample are calculated according to formula (3).

[0111] The specific experimental steps can be implemented as follows:

[0112] ① Add the sample to the sample box and compact it while adding.

[0113] ② Use an impedance analyzer to apply AC excitation signals of different frequencies to two adjacent electrodes. The sample impedance is measured by detecting the output signals of the other two electrodes, and then the sample impedance is calculated. An axial stress of 50 kPa is applied to the sample and maintained constant. The load plate is sheared at a rate of 1° / min. When the shear stress reading decreases, it indicates that the sample has been sheared. The shear stress at this time is the shear strength, and the sample impedance is measured at this time.

[0114] ③ Change the axial stress applied to the sample to 100kPa, 150kPa, and 200kPa, repeat experimental steps ① and ② in sequence, and record the measured sample impedance and shear strength.

[0115] ④ Change the saturation of the sample, repeat steps ①, ②, and ③, and record the measured sample impedance and shear strength.

[0116] S300, sequentially measuring the compressive strength and the corresponding axial strain of each sample in the sample set based on the second mechanical test, and synchronously and jointly measuring the impedance corresponding to each sample based on the second electrical measurement method, to obtain second correlation data of the impedance and compressive strength of each sample;

[0117] Wherein, the compressive strength is determined based on the axial stress applied in the second mechanical test;

[0118] It should be noted that, in some embodiments, step S300 may include the following steps: measuring the compressive strength and the corresponding axial strain of each sample in the sample set in sequence through a triaxial test, and obtaining the impedance corresponding to each sample through a two-electrode method through an impedance analyzer, and obtaining second related data of the impedance and compressive strength of each sample; wherein, the triaxial test applies axial stress to the sample at a preset downward speed, and monitors the axial strain of the sample in real time until the sample is destroyed, obtains the axial stress and axial strain at the corresponding moment, and uses the axial stress at the corresponding moment as the compressive strength; based on the two-electrode method, the impedance of the sample at the corresponding moment is synchronously and jointly measured through an impedance analyzer.

[0119] It should also be noted that the two-electrode method includes a contact two-electrode method and a non-contact two-electrode method.

[0120] For example, in some embodiments, the contact two-electrode method is combined with the triaxial test to measure the resistivity of the sample in relation to the compressive strength and compression modulus. Figure 7 As shown, ( Figure 7 The corresponding meanings of the reference numerals are: 1-piston; 2-exhaust hole; 3-electrode plate; 4-pressure chamber; 5-sample; 6-insulating sleeve; 7-air inlet). The application principle of the contact two-electrode method and the triaxial test combined measurement is as follows:

[0121] like Figure 7 As shown, current is applied to the upper and lower electrodes and the voltage drop is measured. Similarly, the resistivity of the ring sample can be obtained according to equations (1) and (2).

[0122] The axial stress applied to the sample can be adjusted by controlling the piston, and the confining pressure applied to the sample can be adjusted by controlling the exhaust and air inlet holes of the pressure chamber. Compressive strength refers to the maximum stress a sample can withstand before failure, and this parameter can be obtained using a dynamometer. The compression modulus is the elastic modulus of a material, representing the ratio of stress to strain. The compression modulus E is calculated from the linear portion of the axial stress and axial strain in the triaxial test:

[0123]

[0124] Where: Δσ is the change in axial stress, and Δε is the change in axial strain.

[0125] The specific experimental steps can be implemented as follows:

[0126] ① The electrode plate and the insulating sleeve form a sample box. Add the sample to the sample box and compact it while adding. After the sample fills the insulating sleeve, place the upper electrode plate on the sample and press repeatedly to ensure full contact between the electrode and the sample.

[0127] ② Using an impedance analyzer, apply AC excitation signals of varying frequencies to the two electrodes and simultaneously measure the output signals from both electrodes to determine the sample's impedance. A piston applies axial stress to the sample at a downward pressure rate of 1 mm / min. Adjust the air inlet and outlet ports to maintain a constant confining pressure. Monitor the sample's axial strain, confining pressure, and applied axial stress in real time until failure. The measured axial stress is the sample's compressive strength, and the sample's impedance is also measured and calculated.

[0128] ③ Change the saturation of the sample, repeat the above steps, and record the measured sample impedance, compressive strength, axial stress and axial strain.

[0129] For example, in some embodiments, the non-contact two-electrode method is combined with the triaxial test to measure the resistivity of the sample in relation to the compressive strength and compression modulus. Figure 8 As shown, ( Figure 8 The corresponding meanings of the reference numerals are: 1-piston; 2-exhaust hole; 3-pressure chamber; 4-electrode; 5-sample; 6-insulating sleeve; 7-air inlet). The application principle of the non-contact two-electrode method and triaxial test combined measurement is as follows:

[0130] The upper electrode is used as an excitation electrode to apply an excitation signal to it, the lower electrode is used as an output electrode, and the series inductor eliminates the influence of the coupling capacitor. Similarly, the sample impedance is finally obtained by the impedance analyzer, and then the sample impedance is calculated.

[0131] Axial pressure is applied to the sample through the piston, and confining pressure is applied to the sample through the pressure chamber. Similarly, the compressive strength of the sample is obtained according to the dynamometer, and the compression modulus of the sample is obtained according to formula (5).

[0132] The specific experimental steps can be implemented as follows:

[0133] ① Add the sample to the insulating sleeve and compact it while adding.

[0134] ② Using an impedance analyzer, apply AC excitation signals of varying frequencies to the upper electrode. The sample impedance is measured by detecting the output signal from the lower electrode, and the sample impedance is then calculated. A piston applies axial stress to the sample at a downward speed of 1 mm / min. The air inlet and outlet ports are adjusted to maintain a constant confining pressure. The axial strain, confining pressure, and applied axial stress of the sample are monitored in real time until the sample fails. The measured axial stress at this point is the sample's compressive strength, and the sample impedance is also measured at this point.

[0135] ③ Change the saturation of the sample, repeat the above steps, and record the measured sample impedance, compressive strength, axial stress and axial strain.

[0136] It should be noted that, in some embodiments, step S300 may further include the following steps: measuring the compressive strength and the corresponding axial strain of each sample in the sample set in sequence through an unconfined compression test, and obtaining the impedance corresponding to each sample through a synchronous joint measurement based on a contact three-electrode method through an impedance analyzer, and obtaining second related data of the impedance and compressive strength of each sample; wherein, the unconfined compression test applies axial stress to the sample at a preset upper pressure speed, and monitors the axial strain of the sample in real time until the sample is destroyed, obtains the axial stress and axial strain at the corresponding moment, and uses the axial stress at the corresponding moment as the compressive strength; based on the contact three-electrode method, the impedance of the sample at the corresponding moment is synchronously and jointly measured through an impedance analyzer.

[0137] For example, in some embodiments, the contact three-electrode method is combined with the unconfined compression test to measure the resistivity of the sample and correlate it with the compressive strength. Figure 9a and Figure 9b As shown, ( Figure 9a and Figure 9b The corresponding meanings of the reference numerals are: 1—low-voltage electrode; 2—shielding electrode; 3—sample; 4—insulating sleeve; 5—high-voltage electrode; 6—piston). The application principle of the contact three-electrode method combined with the unconfined compression test is as follows:

[0138] The three electrodes include high-voltage and low-voltage electrodes and a shielding electrode. The shielding electrode serves as the third electrode to introduce the surface current of the sample directly into the ground to eliminate its influence on the body current measurement. The high-voltage and low-voltage electrodes apply voltage to both ends of the sample and measure the current flowing through the sample. The volume resistance of the sample is calculated by formula (1), and the equivalent area of ​​the sample is calculated according to the following formula:

[0139]

[0140] Where: D E is the diameter of the low-voltage electrode; g is the distance between the low-voltage electrode and the shielding electrode.

[0141] Finally, the resistivity ρ is solved according to the following formula:

[0142]

[0143] Where: R is the resistance, A2 is the equivalent contact area of ​​the electrode, and h is the sample thickness.

[0144] The piston can apply axial stress to the sample, and the compressive strength of the sample can be measured by the dynamometer, that is, the maximum stress the sample can withstand before failure.

[0145] The specific experimental steps can be implemented as follows:

[0146] ① Three electrodes and an insulating sleeve form a sample box. Add the sample to the sample box and compact it while adding. The low-voltage electrode and the shielding electrode are connected through the insulating sleeve. After the sample fills the insulating sleeve, press the three electrodes repeatedly to ensure that the electrodes are in full contact with the sample.

[0147] ② Using an impedance analyzer, apply AC excitation signals of varying frequencies to the high-voltage and low-voltage electrodes and simultaneously measure the output signals from both electrodes to determine the sample's impedance. A piston applies axial stress to the sample at an upward pressure rate of 1 mm / min until the sample fails. The measured axial stress is the sample's compressive strength, and the sample's impedance is also measured at this point.

[0148] ③ Change the saturation of the sample, repeat the above steps, and record the measured sample impedance and compressive strength.

[0149] It should be noted that, in some embodiments, step S300 may further include the following steps: measuring the compressive strength and the corresponding axial strain of each sample in the sample set in sequence through an unconfined compression test, and obtaining the impedance corresponding to each sample through a synchronous joint measurement based on the contact-type Van der Pauw method through an impedance analyzer, and obtaining second correlated data of the impedance and compressive strength of each sample; wherein, the unconfined compression test applies axial stress to the sample at a preset upward pressure speed, and monitors the axial strain of the sample in real time until the sample is destroyed, obtains the axial stress and axial strain at the corresponding moment, and uses the axial stress at the corresponding moment as the compressive strength; based on the contact-type Van der Pauw method, the impedance of the sample at the corresponding moment is synchronously and jointly measured through an impedance analyzer.

[0150] For example, in some embodiments, the contact Van der Pauw method is combined with the unconfined compression test to measure the resistivity of the sample and the compressive strength. Figure 10a and Figure 10b As shown, ( Figure 10a and Figure 10b The corresponding meanings of the reference numerals are: 1-piston; 2-sample; 3-sample box; 4-electrode sheet). The application principle of the combined measurement of the contact Van der Pauw method and the unconfined compression test is as follows:

[0151] The Vanderbilt method test principle involves measuring two voltage values ​​and two current values. Four electrodes are placed on the surface of a sample of equal thickness. The four electrodes are named 1, 2, 3, and 4. The current value between 1 and 2 and the voltage value between 3 and 4 are measured respectively, and the resistance value R is obtained. 12,34 , similarly, we get the resistance value R 14,23 The relationship between the voltage and current can be expressed by the Vanderbilt formula:

[0152]

[0153] Where: d is the sample thickness, ρ is the sample resistivity.

[0154] When the sample is symmetrical and the electrodes are arranged symmetrically on the sample surface, R 12,34 =R 14,23 , the above formula can be simplified to:

[0155]

[0156] The piston applies axial stress to the sample. When the sample is damaged, the compressive strength of the sample is obtained by the dynamometer.

[0157] The specific experimental steps can be implemented as follows:

[0158] ① Four equally spaced electrodes and an insulating tube form a sample box. Add the sample into the sample box and compact it while adding.

[0159] ② Number the electrodes 1, 2, 3, and 4. Use an impedance analyzer to apply AC excitation signals of varying frequencies to adjacent electrodes 1 and 2, measuring the output signals from electrodes 3 and 4. Next, apply AC excitation signals of varying frequencies to adjacent pistons of electrodes 1 and 4, measuring the output signals from electrodes 2 and 3 to determine the sample's impedance. Apply axial stress to the sample at a downward pressure rate of 1 mm / min until failure. The measured axial stress is the sample's compressive strength, and the sample's impedance is also calculated.

[0160] ③ Change the saturation of the sample, repeat the above steps, and record the measured sample impedance and compressive strength.

[0161] It should be noted that, in some embodiments, step S300 may further include the following steps: measuring the compressive strength and the corresponding axial strain of each sample in the sample set in sequence through a triaxial test, and obtaining the impedance corresponding to each sample through a synchronous joint measurement based on a contact four-probe method through an impedance analyzer, and obtaining second correlation data of the impedance and compressive strength of each sample; wherein, the triaxial test applies axial stress to the sample at a preset downward speed, and monitors the axial strain of the sample in real time until the sample is destroyed, obtains the axial stress and axial strain at the corresponding moment, and uses the axial stress at the corresponding moment as the compressive strength; based on the contact four-probe method, the impedance of the sample at the corresponding moment is synchronously and jointly measured through an impedance analyzer.

[0162] For example, in some embodiments, the contact four-probe method is combined with the triaxial test to measure the resistivity of the sample in relation to the compressive strength and compression modulus. Figure 11 As shown, ( Figure 11The corresponding meanings of the reference numerals are: 1-piston; 2-exhaust hole; 3-pressure chamber; 4-insulating sleeve; 5-sample; 6-detection probe; 7-air inlet). The application principle of the contact two-electrode method and the triaxial test combined measurement is as follows:

[0163] In the four-probe method, four probes are arranged in a straight line and evenly spaced on the sample surface, usually at equal distances. The two outer probes are used to apply a known current I, and the two inner probes are used to measure the voltage drop U generated when the current passes through the sample. Since the voltage is measured by the two inner probes, this configuration can avoid the influence of electrode contact resistance and wire resistance on the measurement results, ensuring more accurate measurement. The resistivity calculation formula is:

[0164]

[0165] Where: ρ is the resistivity of the sample, s is the spacing between adjacent probes, U is the voltage drop measured by the inner probe, and I is the current applied by the outer probe.

[0166] Compressive strength refers to the maximum stress a sample can withstand before failure. This parameter can be obtained using a dynamometer. The compression modulus is the elastic modulus of the material and can be solved according to formula (5).

[0167] The specific experimental steps can be implemented as follows:

[0168] ① Add the sample to the insulating sleeve and compact it while adding. After the sample fills the insulating sleeve, insert four probes into the sample at equal intervals.

[0169] ② Using an impedance analyzer, apply AC excitation signals of varying frequencies to the two outer probes and measure the output signals from the two inner probes to determine the sample's impedance. A piston applies axial stress to the sample at a downward pressure rate of 1 mm / min. Adjust the air inlet and outlet ports to maintain a constant confining pressure. Monitor the sample's axial strain, confining pressure, and applied axial stress in real time until failure. The measured axial stress represents the sample's compressive strength, and the sample's impedance is also measured at this point.

[0170] ③ Change the saturation of the sample, repeat the above steps, and record the measured sample impedance, compressive strength, axial stress and axial strain.

[0171] S400, obtaining the resistivity of the sample under different states based on the geometric parameters of the electrical sensor applied by the electrical measurement method in combination with the impedance; the electrical measurement method includes a first electrical measurement method and a second electrical measurement method;

[0172] It should be noted that, in the embodiment of the present invention, the impedance is characterized by a resistor R.

[0173] For example, in some specific embodiments, referring to formulas (2), (7), (9) and (10) in the aforementioned specific embodiments, the geometric parameters of the electrical sensor include the electrode equivalent contact area and the spacing between adjacent probes. In some specific application scenarios, the resistivity is further calculated in combination with the sample thickness, wherein the impedance in formula (10) corresponds to U / I.

[0174] S500, based on the resistivity corresponding to the sample in different states, convert the first associated data into third associated data of the resistivity and shear strength of the sample, and convert the second associated data into fourth associated data of the resistivity and compressive strength;

[0175] S600: Construct a first correlation curve between shear strength and axial stress based on the test results of the first mechanical test, and then obtain the internal friction angle and cohesion corresponding to the shear strength of the sample under different axial stresses according to Coulomb shear strength theory; and then obtain fifth correlation data between the resistivity and internal friction angle of the sample and sixth correlation data between the resistivity and cohesion based on the third correlation data.

[0176] For example, in some specific embodiments, according to Coulomb shear strength theory, the shear strength τ of the sample can be expressed as:

[0177]

[0178] Where: τ is the shear strength of the sample, c is the cohesion of the sample, and σ is the normal stress; is the internal friction angle of the sample.

[0179] S700: construct a second correlation curve of axial strain and axial stress based on the test results of the second mechanical test, and obtain the compression modulus of the sample corresponding to the axial strain under different axial stresses according to the slope of the second correlation curve; and then obtain seventh correlation data of the resistivity and compression modulus of the sample according to the fourth correlation data;

[0180] For example, in some embodiments, the compression modulus is the elastic modulus of a material, which represents the ratio of stress to strain of the material. The compression modulus E is calculated by the linear portion of the axial stress and axial strain in a triaxial test:

[0181] Where: Δσ is the change in axial stress, and Δε is the change in axial strain.

[0182] S800 , performing data fitting on the third correlation data, the fourth correlation data, the fifth correlation data, the sixth correlation data, and the seventh correlation data to obtain a mechanical parameter prediction model.

[0183] The mechanical parameter prediction model comprises a shear strength prediction model, a compressive strength prediction model, an internal friction angle prediction model, a cohesion prediction model, and a compression modulus prediction model.

[0184] The mechanical parameter prediction model is used to predict the mechanical parameters of the rock to be predicted based on the electrical resistivity of the rock to be predicted.

[0185] For example, in some embodiments, the mechanical parameter prediction model can be established by using linear fitting, polynomial fitting, neural network, etc., according to the complex resistivity and mechanical parameters obtained through experiments.

[0186] To explain the principle of the technical scheme of the present application, the overall process of the present application will be described below in conjunction with some specific embodiments. It should be understood that the following is an explanation of the technical principle of the present application and cannot be regarded as a limitation of the present application.

[0187] First of all, it should be pointed out that in traditional rock mechanics research, it is difficult to measure the in-situ rock mechanics parameters, and laboratory mechanical tests such as triaxial test and unconfined compression test are often used to determine the parameters. Although these methods are accurate, they are usually time-consuming and costly, especially in large-scale geological exploration or deep underground engineering, the testing difficulty and cost are more significant. Electrical parameter measurement of rock is a non-invasive detection method that can quickly and economically obtain the electrical properties of rock. The electrical parameters of rock are influenced by many factors such as mineral composition, porosity, and water content, which are also indirectly related to the mechanical properties of rock. Therefore, the electrical parameter measurement can be used to predict the mechanical parameters of rock to reduce the cost and time of traditional experimental methods.

[0188] Currently, in the research of combined electrical and mechanical measurement, there is a lack of wideband measurement means, which limits the comprehensive understanding of the electrical properties of rock. Wideband measurement can provide more frequency information, thus better reflecting the electrical response of rock at different frequencies. However, existing research generally does not incorporate this technology into the analysis framework. In addition, the application of non-contact measurement methods is also relatively scarce, which makes the process of obtaining rock electrical parameters more tedious and time-consuming. Non-contact measurement has the advantages of speed and non-invasiveness, which can improve the efficiency and accuracy of data acquisition. Due to the lack of application of these advanced measurement techniques, the existing research results are limited in practical application under complex geological conditions, and it is difficult to meet the needs of modern geological exploration and engineering development.

[0189] The present application proposes a rock mechanical parameter prediction method based on wideband electrical parameter measurement to solve the problem of lack of wideband measurement and non-contact measurement in current combined electrical and mechanical measurement. By combining various electrical measurement methods with various mechanical tests, an accurate mechanical parameter prediction model is established.

[0190] The present invention proposes a rock mechanical parameter prediction method based on electrical parameter measurement, which comprises the following steps:

[0191] First, a combined electrical parameter measurement method and mechanical testing method was determined. The impedance of the hydrate-containing porous medium was obtained by applying excitation signals of different frequencies to the electrodes. The corresponding complex resistivity was calculated based on the size and distance of the electrical sensor and the impedance of the hydrate-containing porous medium. Simultaneously, the mechanical parameters of the hydrate-containing porous medium were measured through mechanical testing.

[0192] According to the complex resistivity and mechanical parameters obtained from the experiment, a mechanical parameter prediction model was established using linear fitting, polynomial fitting and neural network methods.

[0193] In some specific application scenarios, establishing a mechanical parameter prediction model can be achieved as follows:

[0194] The impedance analyzer can obtain the impedance values ​​at a series of frequency points in each state, within a certain frequency range, and calculate the corresponding complex resistivity based on the geometric size and distance of the electrical sensor and the impedance of the sample.

[0195] The shear strength and compressive strength of the sample can be directly obtained through mechanical testing, but the internal friction angle, cohesion and compression modulus cannot be directly obtained through mechanical testing.

[0196] Based on the shear strength and axial stress obtained from the ring shear test and direct shear test, a shear strength-axial stress curve is drawn. According to the Coulomb shear strength theory, the internal friction angle and cohesion can be obtained.

[0197]

[0198] Where: τ is the shear strength of the sample, c is the cohesion of the sample, σ is the normal stress, is the internal friction angle of the sample.

[0199] Based on the axial stress change and axial strain measured by the triaxial test, a stress-strain curve is drawn, and the compression modulus can be obtained according to its slope.

[0200] The complex resistivity obtained above and the mechanical parameters obtained are used to establish a mechanical parameter prediction model through linear fitting, polynomial fitting and neural network methods. The mechanical parameter prediction model specifically includes five models: internal friction angle prediction model, shear strength prediction model, cohesion prediction model, compression modulus prediction model and compressive strength prediction model. The process of establishing the mechanical parameter prediction model is as follows: Figure 12 shown.

[0201] The following uses the application scenarios of the two-electrode method (contact type) and the direct shear test combined measurement method, and the four-probe method and the compression test (triaxial test) combined measurement method as examples to specifically illustrate the logical flow of the technical solution of the present invention: 1. Specific embodiment 1:

[0203] The shear strength prediction model, internal friction angle prediction model, and cohesion prediction model were established using the two-electrode method (contact type) and direct shear test combined measurement method. The specific method is as follows:

[0204] Experimental setup:

[0205] like Figure 2 As shown, the two-electrode method (contact type) and direct shear test combined measurement system of the present invention mainly includes an impedance analyzer, upper and lower electrode plates, an insulating sleeve, a platform and a piston.

[0206] The impedance analyzer connects the upper and lower electrodes, which can apply excitation signals of different frequencies to the electrodes, and also receive the output signals of the two electrodes to obtain the impedance of the sample being measured.

[0207] The insulating sleeve is made of an insulating and elastically deformable rubber material, and together with the upper and lower electrode sheets, forms a cylindrical sample container.

[0208] The piston part is connected to the dynamometer and displacement meter, and its length should be greater than or equal to the exposed part of the sample on the platform to ensure that the exposed sample is evenly stressed and obtain accurate data.

[0209] The platform is made of a material with high hardness, insulation and smooth surface, and is mainly used to fix the sample.

[0210] The experimental operation process is:

[0211] Remove the upper electrode sheet and add hydrate-containing sediment with a saturation of 10% into the insulating sleeve while compacting it. After the sample fills the insulating sleeve, cover it with the upper electrode sheet and press it repeatedly to ensure full contact between the sample and the electrode sheet.

[0212] The impedance analyzer was used to apply 1Hz-10 5 Hz excitation signal, and simultaneously detect the output signals of the two electrodes to obtain the impedance of the sample.

[0213] Place weights on the upper electrode plate and apply axial stress to the sample. The initial axial stress is 50kPa. Let the piston shear at a rate of 1mm / min. When the shear stress reading reaches a stable state or retreats significantly, it means that the sample has been sheared. It is advisable to shear until the shear deformation reaches 4mm. When the shear stress reading continues to increase, the shear deformation should reach 6mm. The shear stress at this time is the shear strength. At the same time, the sample impedance at this time is recorded by the impedance analyzer.

[0214] The saturation of the sample was kept constant, the weight of the weight was changed so that the axial stress applied by it was 100 kPa, 150 kPa and 200 kPa respectively, the above steps were repeated, and the shear strength and the corresponding impedance were recorded.

[0215] The saturation of the sample was changed, the above steps were repeated, and the measured shear strength and impedance were recorded.

[0216] Data processing and model establishment:

[0217] The complex resistivity of the sample was calculated according to the impedance obtained by the impedance analyzer, the size and distance of the two-electrode electrode sheet, and the test frequency was 1 Hz-10 Hz. 5 Hz.

[0218]

[0219] In the formula: |p| is the amplitude of the complex resistivity, |Z| is the amplitude of the impedance, A1 is the effective contact area, and L is the distance between the two electrodes. According to the amplitude and phase angle of the complex resistivity, the real part and imaginary part of the complex resistivity can be obtained:

[0220] p' = |p| cos θ

[0221] p" = |p| sin θ

[0222] In the formula: p' is the real part of the complex resistivity, p" is the imaginary part of the complex resistivity, and θ is the phase angle of the complex resistivity.

[0223] The real part and imaginary part of the complex resistivity were fitted with the shear strength by linear fitting, polynomial fitting and neural network, and the best fitting equation was obtained, as shown in Figure 13 , Figure 14 From Figure 13 and Figure 14 , it can be seen that the compressive strength increases with the increase of the axial stress, and the shear strength decreases with the increase of the complex resistivity under the same axial stress.

[0224] According to the measured shear strength and the corresponding axial pressure, the shear strength-axial pressure curve can be drawn, and the internal friction angle and cohesion can be obtained by the Coulomb shear strength theory.

[0225]

[0226] The real part and imaginary part of the complex resistivity were fitted with the internal friction angle and cohesion by linear fitting, polynomial fitting and neural network, and the best fitting equation was obtained, as shown in Figure 15 , Figure 16 , Figure 17 and Figure 18 shown. 2. Specific embodiment 2:

[0228] The compression modulus prediction model and compressive strength prediction model are established using the four-probe method and compression test combined measurement method. The specific method is as follows.

[0229] Experimental setup:

[0230] like Figure 11 As shown, the four-probe method and compression test combined measurement system of the present invention mainly includes an impedance analyzer, four detection probes, an insulating sleeve, a pressure chamber and a piston.

[0231] The signal output end of the impedance analyzer is connected to the upper and lower outer probes, and excitation signals of different frequencies can be applied to the probes. Its signal receiving end is connected to the two inner test probes.

[0232] The insulating sleeve is made of insulating and elastically deformable rubber material, is cylindrical in shape, and has an opening at the bottom that is inverted on the fixing platform.

[0233] Four detection probes are fixed on the lower platform at equal intervals.

[0234] The piston part is connected to the dynamometer and displacement meter, and its area should be greater than or equal to the cross-sectional area of ​​the insulating sleeve to ensure that the sample is evenly stressed and obtain accurate data.

[0235] The gas in the pressure chamber is controlled through the inlet and exhaust holes, thereby controlling the confining pressure applied to the sample.

[0236] The experimental operation process is:

[0237] Add hydrate-containing sediments with a saturation of 10% into the insulating sleeve and compact it while adding. After the sample fills the insulating sleeve, place it on a platform with detection probes, while ensuring that the sample contacts each probe.

[0238] The impedance analyzer was used to apply 1Hz-10 5 Hz excitation signal, and simultaneously detect the output signals of the two inner detection electrodes to obtain the impedance of the sample.

[0239] The air inlet and outlet holes are adjusted to ensure constant confining pressure. The piston applies axial stress to the sample at a downward speed of 1 mm / min. The axial strain and applied axial stress of the sample are monitored in real time by the displacement meter and dynamometer until the sample is destroyed. The axial stress measured at this time is the compressive strength of the sample, and the sample impedance at this time is also recorded.

[0240] Change the saturation of the sample, repeat the above steps, and record the changes in compressive strength, impedance, axial strain and axial stress at each saturation.

[0241] Data processing and model building:

[0242] The complex resistivity of the sample is calculated based on the impedance obtained by the impedance analyzer, the size of the two electrode sheets and the distance between them. 5 The value is between Hz.

[0243] |ρ|=2πs×|Z|

[0244] Where: |ρ| is the magnitude of complex resistivity, |Z| is the magnitude of impedance, and s is the distance between adjacent probes.

[0245] The real and imaginary parts of the complex resistivity can be obtained according to the amplitude and phase angle of the complex resistivity:

[0246] ρ'=|ρ|cosθ

[0247] ρ'=|ρ|sinθ

[0248] Where: ρ' is the real part of the complex resistivity, ρ" is the imaginary part of the complex resistivity, and θ is the phase angle of the complex resistivity.

[0249] The real and imaginary parts of the complex resistivity are fitted with the compressive strength by various methods such as linear fitting, polynomial fitting and neural network, and the best fitting equation is obtained. The results are as follows: Figure 19 、 Figure 20 As shown. Figure 19 and Figure 20 It can be seen that the compressive strength increases with the increase of axial stress, and the shear strength decreases with the increase of complex resistivity under the same axial stress.

[0250] The strain-stress curve is drawn according to the measured axial strain and axial stress, and the compression modulus can be obtained by calculating the slope of the curve.

[0251] The real and imaginary parts of the complex resistivity are fitted with the compression modulus by various methods such as linear fitting, polynomial fitting and neural network, and the best fitting equation is obtained. The results are as follows: Figure 21 、 Figure 22 shown.

[0252] In another aspect, an embodiment of the present invention further provides an electronic device comprising a memory and a processor. The memory stores a computer program, and the processor, when executing the computer program, implements the aforementioned method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters. The electronic device can be any smart terminal, including a tablet computer and an in-vehicle computer.

[0253] It can be understood that the contents of the above method embodiments are applicable to the present device embodiments, the functions specifically implemented by the present device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0254] The contents of the method embodiments of the present invention are all applicable to the electronic device embodiments. The functions specifically implemented by the electronic device embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0255] Another aspect of an embodiment of the present invention further provides a computer-readable storage medium, wherein the storage medium stores a program, and the program is executed by a processor to implement the above method.

[0256] It should be noted that the computer-readable medium shown in the embodiments of the present invention may be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or component, or any combination thereof. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a flash memory, an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present invention, a computer-readable storage medium may be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, device, or component. In the present invention, a computer-readable signal medium may include a data signal propagated in baseband or as part of a carrier wave, which carries computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium may also be any computer-readable medium other than a computer-readable storage medium that can transmit, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device. Program code embodied on a computer-readable medium may be transmitted using any suitable medium, including but not limited to wireless, wired, or any suitable combination thereof.

[0257] The contents of the method embodiments of the present invention are all applicable to the computer-readable storage medium embodiments. The functions specifically implemented by the computer-readable storage medium embodiments are the same as those of the above method embodiments, and the beneficial effects achieved are also the same as those achieved by the above method embodiments.

[0258] The present invention also discloses a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device can read the computer instructions from the computer-readable storage medium and execute the computer instructions, causing the computer device to perform the above method.

[0259] The flowcharts and block diagrams in the accompanying drawings illustrate the possible implementation architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, program segment, or a part of code, and the above-mentioned module, program segment, or a part of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram or flowchart, and the combination of boxes in the block diagram or flowchart, can be implemented with a dedicated hardware-based system that performs the specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0260] It should be noted that although several modules of the device for action execution are mentioned in the above detailed description, this division is not mandatory. In fact, according to an embodiment of the present invention, the features and functions of two or more modules or units described above can be concretized in one module or unit. Conversely, the features and functions of one module or unit described above can be further divided into multiple modules or units to be concretized.

[0261] Through the description of the above embodiments, it is easy for those skilled in the art to understand that the example embodiments described herein can be implemented by software or by combining software with necessary hardware. Therefore, the technical solution according to the embodiments of the present invention can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD to ROM, a USB flash drive, a mobile hard disk, etc.) or on a network, and includes a number of instructions to enable a computing device (which can be a personal computer, a server, a touch terminal, or a network device, etc.) to execute the method according to the embodiments of the present invention.

[0262] In some optional embodiments, the function / operation mentioned in the block diagram may not occur in the order mentioned in the operation diagram. For example, depending on the function / operation involved, the two boxes shown in succession can actually be executed substantially simultaneously or the boxes can sometimes be executed in reverse order. In addition, the embodiment presented and described in the flow chart of the present invention is provided in an exemplary manner for the purpose of providing a more comprehensive understanding of the technology. The disclosed method is not limited to the operation and logic flow presented herein. Optional embodiments are contemplated in which the order of the various operations is changed and the sub-operations described as a part of a larger operation are performed independently.

[0263] In addition, although the present invention is described in the context of functional modules, it should be understood that, unless otherwise stated, one or more of the functions and / or features may be integrated into a single physical device and / or software module, or one or more functions and / or features may be implemented in separate physical devices or software modules. It will also be understood that a detailed discussion of the actual implementation of each module is not necessary for understanding the present invention. More specifically, given the properties, functions, and internal relationships of the various functional modules in the devices disclosed herein, the actual implementation of the module will be understood within the ordinary skill of an engineer. Therefore, a person skilled in the art will be able to implement the present invention as set forth in the claims using ordinary skill without undue experimentation. It will also be understood that the specific concepts disclosed are merely illustrative and are not intended to limit the scope of the present invention, which is determined by the full scope of the appended claims and their equivalents.

[0264] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, and other media that can store program code.

[0265] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution apparatus, device, or apparatus (e.g., a computer-based apparatus, a device including a processor, or other apparatus that can fetch instructions from and execute instructions on an instruction execution apparatus, device, or apparatus). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution apparatus, device, or apparatus.

[0266] More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering, or processing in another suitable manner as necessary, and then stored in a computer memory.

[0267] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution device. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0268] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations 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 any one or more embodiments or examples.

[0269] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

[0270] The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of the present invention.

Claims

1. A method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters, characterized in that: The following steps are involved: Acquire a sample set; the sample set includes a plurality of samples of hydrate-containing sediment rocks with different saturations; sequentially measuring the shear strength of each sample in the sample set under different axial stresses based on the first mechanical test, and synchronously and jointly measuring the impedance of each sample under different states based on the first electrical measurement method, to obtain first correlation data between the impedance and the shear strength of each sample; sequentially measuring the compressive strength and the corresponding axial strain of each sample in the sample set based on a second mechanical test, and synchronously and jointly measuring the impedance corresponding to each sample based on a second electrical measurement method, to obtain second correlation data between the impedance and the compressive strength of each sample; the compressive strength is determined based on the axial stress applied by the second mechanical test; Based on the geometric parameters of the electrical sensor applied by the electrical measurement method and the impedance, the resistivity corresponding to the sample in different states is obtained; the electrical measurement method includes the first electrical measurement method and the second electrical measurement method; Based on the resistivity of the sample under different states, converting the first correlation data into third correlation data of the resistivity and the shear strength of the sample, and converting the second correlation data into fourth correlation data of the resistivity and the compressive strength; Based on the test results of the first mechanical test, a first correlation curve between the shear strength and the axial stress is constructed, and then, based on Coulomb shear strength theory, the internal friction angle and cohesion corresponding to the shear strength of the sample under different axial stresses are obtained; and based on the third correlation data, fifth correlation data between the resistivity and the internal friction angle of the sample and sixth correlation data between the resistivity and the cohesion are obtained; constructing a second correlation curve between the axial strain and the axial stress based on the test results of the second mechanical test, and obtaining the compression modulus of the sample corresponding to the axial strain under different axial stresses according to the slope of the second correlation curve; and obtaining seventh correlation data between the resistivity and the compression modulus of the sample according to the fourth correlation data; performing data fitting on the third associated data, the fourth associated data, the fifth associated data, the sixth associated data, and the seventh associated data to obtain a mechanical parameter prediction model; the mechanical parameter prediction model includes a shear strength prediction model, a compressive strength prediction model, an internal friction angle prediction model, a cohesion prediction model, and a compression modulus prediction model; The mechanical parameter prediction model is used to predict the mechanical parameters of the rock to be predicted based on the resistivity of the rock to be predicted.

2. The method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters according to claim 1, characterized in that: The method comprises the following steps: sequentially measuring the shear strength of each sample in the sample set under different axial stresses based on the first mechanical test, and synchronously and jointly measuring the impedance of each sample under different states based on the first electrical measurement method to obtain first correlation data between the impedance and the shear strength of each sample. The shear strength of each sample in the sample set under different axial stresses is measured in sequence by a direct shear test, and the impedance corresponding to each sample in different states is obtained by synchronously and jointly measuring using an impedance analyzer based on a contact two-electrode method, thereby obtaining first correlation data between the impedance and the shear strength of each sample; In which, a single direct shear test applies a fixed axial stress to the sample, and continuously shears the sample at a preset shear rate until the shear stress reaches a first preset condition during the shear treatment. The shear strength is determined based on the shear stress, and is synchronously measured using an impedance analyzer based on a contact two-electrode method.

3. The method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters according to claim 1, characterized in that: The method comprises the following steps: sequentially measuring the shear strength of each sample in the sample set under different axial stresses based on the first mechanical test, and synchronously and jointly measuring the impedance of each sample under different states based on the first electrical measurement method to obtain first correlation data between the impedance and the shear strength of each sample. The shear strength of each sample in the sample set under different axial stresses is measured in sequence by a ring shear test, and the impedance corresponding to each sample in different states is obtained by synchronously and jointly measuring using an impedance analyzer based on a contact two-electrode method, thereby obtaining first correlation data between the impedance and the shear strength of each sample; Among them, a single ring shear test applies a fixed axial stress to the sample, and continuously shears the sample at a preset shear rate until the shear stress reaches a second preset condition during the shear treatment. The shear strength is determined based on the shear stress, and is synchronously measured by an impedance analyzer based on a contact two-electrode method.

4. The method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters according to claim 1, characterized in that: The method comprises the following steps: sequentially measuring the shear strength of each sample in the sample set under different axial stresses based on the first mechanical test, and synchronously and jointly measuring the impedance of each sample under different states based on the first electrical measurement method to obtain first correlation data between the impedance and the shear strength of each sample. The shear strength of each sample in the sample set under different axial stresses is measured in sequence by a direct shear test, and the impedance corresponding to each sample in different states is obtained by synchronously and jointly measuring using an impedance analyzer based on a non-contact two-electrode method, thereby obtaining first correlation data between the impedance and the shear strength of each sample; In which, a single direct shear test applies a fixed axial stress to the sample, and continuously shears the sample at a preset shear rate until the shear stress reaches a third preset condition during the shear treatment. The shear strength is determined based on the shear stress, and is synchronously measured using an impedance analyzer based on a non-contact two-electrode method.

5. The method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters according to claim 1, characterized in that: The method comprises the following steps: sequentially measuring the shear strength of each sample in the sample set under different axial stresses based on the first mechanical test, and synchronously and jointly measuring the impedance of each sample under different states based on the first electrical measurement method to obtain first correlation data between the impedance and the shear strength of each sample. The shear strength of each sample in the sample set under different axial stresses is measured in sequence by a ring shear test, and the impedance corresponding to each sample in different states is obtained by synchronously and jointly measuring using an impedance analyzer based on a non-contact two-electrode method, thereby obtaining first correlation data between the impedance and the shear strength of each sample; Among them, a single ring shear test applies a fixed axial stress to the sample, and continuously shears the sample at a preset shear rate until the shear stress reaches a fourth preset condition during the shear treatment. The shear strength is determined based on the shear stress, and is synchronously measured by an impedance analyzer based on a non-contact two-electrode method.

6. The method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters according to claim 1, characterized in that: The method comprises the following steps: sequentially measuring the shear strength of each sample in the sample set under different axial stresses based on the first mechanical test, and synchronously and jointly measuring the impedance of each sample under different states based on the first electrical measurement method to obtain first correlation data between the impedance and the shear strength of each sample. The shear strength of each sample in the sample set under different axial stresses is measured in sequence by a ring shear test, and the impedance corresponding to each sample in different states is obtained by synchronously and jointly measuring using an impedance analyzer based on a non-contact Van der Pauw method, thereby obtaining first correlation data between the impedance and the shear strength of each sample; Among them, a single ring shear test applies a fixed axial stress to the sample, and continuously shears the sample at a preset shear rate until the shear stress reaches a fifth preset condition during the shear treatment. The shear strength is determined based on the shear stress, and is synchronously measured by an impedance analyzer based on the non-contact Van der Pauw method.

7. The method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters according to claim 1, characterized in that: The method of sequentially measuring the compressive strength and the corresponding axial strain of each sample in the sample set based on the second mechanical test, and synchronously and jointly measuring the impedance corresponding to each sample based on the second electrical measurement method to obtain second correlation data of the impedance and compressive strength of each sample includes the following steps: sequentially measuring the compressive strength and the corresponding axial strain of each sample in the sample set through a triaxial test, and synchronously and jointly measuring the impedance corresponding to each sample through an impedance analyzer based on a two-electrode method to obtain second correlation data of the impedance and the compressive strength of each sample; Among them, the triaxial test applies axial stress to the sample at a preset downward speed, and monitors the axial strain of the sample in real time until the sample is destroyed, obtains the axial stress and the axial strain at the corresponding moment, and uses the axial stress at the corresponding moment as the compressive strength; based on the two-electrode method, the impedance of the sample at the corresponding moment is synchronously and jointly measured by an impedance analyzer.

8. The method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters according to claim 1, characterized in that: The method of sequentially measuring the compressive strength and the corresponding axial strain of each sample in the sample set based on the second mechanical test, and synchronously and jointly measuring the impedance corresponding to each sample based on the second electrical measurement method to obtain second correlation data of the impedance and compressive strength of each sample includes the following steps: sequentially measuring the compressive strength and the corresponding axial strain of each sample in the sample set through an unconfined compression test, and synchronously and jointly measuring the impedance corresponding to each sample through an impedance analyzer based on a contact three-electrode method to obtain second correlation data of the impedance and the compressive strength of each sample; Among them, the unconfined compression test applies axial stress to the sample at a preset upper pressure speed, and monitors the axial strain of the sample in real time until the sample is destroyed, obtains the axial stress and the axial strain at the corresponding moment, and uses the axial stress at the corresponding moment as the compressive strength; based on the contact three-electrode method, the impedance of the sample at the corresponding moment is synchronously and jointly measured by an impedance analyzer.

9. The method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters according to claim 1, characterized in that: The method of sequentially measuring the compressive strength and the corresponding axial strain of each sample in the sample set based on the second mechanical test, and synchronously and jointly measuring the impedance corresponding to each sample based on the second electrical measurement method to obtain second correlation data of the impedance and compressive strength of each sample includes the following steps: sequentially measuring the compressive strength and the corresponding axial strain of each sample in the sample set through an unconfined compression test, and synchronously and jointly measuring the impedance corresponding to each sample through an impedance analyzer based on a contact-type Van der Pauw method, thereby obtaining second correlation data of the impedance and the compressive strength of each sample; Among them, the unconfined compression test applies axial stress to the sample at a preset upward pressure speed, and monitors the axial strain of the sample in real time until the sample is destroyed, obtains the axial stress and the axial strain at the corresponding moment, and uses the axial stress at the corresponding moment as the compressive strength; based on the contact Van der Pauw method, the impedance of the sample at the corresponding moment is synchronously and jointly measured by an impedance analyzer.

10. The method for predicting rock mechanical parameters of hydrate-containing sediments based on broadband electrical parameters according to claim 1, characterized in that: The method of sequentially measuring the compressive strength and the corresponding axial strain of each sample in the sample set based on the second mechanical test, and synchronously and jointly measuring the impedance corresponding to each sample based on the second electrical measurement method to obtain second correlation data of the impedance and compressive strength of each sample includes the following steps: sequentially measuring the compressive strength and the corresponding axial strain of each sample in the sample set through a triaxial test, and synchronously and jointly measuring the impedance corresponding to each sample through an impedance analyzer based on a contact four-probe method, thereby obtaining second correlation data of the impedance and the compressive strength of each sample; Among them, the triaxial test applies axial stress to the sample at a preset downward speed, and monitors the axial strain of the sample in real time until the sample is destroyed, obtains the axial stress and the axial strain at the corresponding moment, and uses the axial stress at the corresponding moment as the compressive strength; based on the contact four-probe method, the impedance of the sample at the corresponding moment is synchronously and jointly measured by an impedance analyzer.

Images