A bidirectional differential detection method

Abstract

This invention discloses a bidirectional differential detection method, comprising: S1: a vibration source excites a vibration wave, a signal acquisition device acquires vibration signal records from sensors, and extracts vibration signal records from three sensors. The sensor group includes at least three sensors arranged at intervals along a first direction, and the vibration source and sensor group are arranged at intervals along the first direction; S2: according to the time-domain differential detection method, a first vibration signal record after suppressing direct transverse waves and Rayleigh surface waves between the main sensor and the front sensor is calculated, and a second vibration signal record after suppressing direct transverse waves and Rayleigh surface waves between the main sensor and the rear sensor is calculated, wherein the sensor in the middle is the main sensor, and the sensors on both sides are the front sensor and the rear sensor, respectively, with the main sensor as a reference; S3: the first vibration signal record and the second vibration signal record are horizontally superimposed to obtain a third vibration signal record that suppresses direct transverse waves and Rayleigh surface waves and whose reflected wave phase and amplitude return to normal.

Description

Technical Field

[0001] This invention relates to the fields of wave detection, such as seismic exploration, ultrasonic testing, and ground-penetrating radar testing, and particularly to a two-way differential wave detection method. Background Technology

[0002] In artificial source seismic exploration or acoustic nondestructive testing, for near-shot records, direct shear waves and Rayleigh surface waves account for the vast majority of energy, while reflected waves from subsurface anisotropic wave velocities or wave impedance interfaces within a certain depth are submerged, thus limiting the resolution of seismic exploration. Suppressing direct shear waves and Rayleigh surface waves is a major challenge in seismic exploration, especially in shallow seismic exploration. Although there are many numerical analysis algorithms in geophysics, such as frequency domain filtering, frequency-wavenumber domain filtering, and Radon transform, these numerically based post-delay algorithms have limited effectiveness and lack universal applicability. In practice, it is sometimes necessary to discard potentially useful information by cutting off the energy envelope signals of Rayleigh surface waves and direct shear waves, resulting in the loss of shallow reflected wave signals.

[0003] The Chinese invention patent with application number CN202011131485.X, entitled "A Detection Method", proposes to use two adjacent sensors with a small channel spacing to perform time-domain differential, which effectively eliminates the interference of direct shear waves and Rayleigh surface waves. However, this method has a drawback: while eliminating direct shear waves and Rayleigh surface waves, it also changes the phase and shape of the reflected waves from the underground interface to a certain extent, which brings some trouble to the subsequent seismic wave processing and interpretation. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a bidirectional differential detection method capable of restoring the phase and shape of reflected waves.

[0005] A bidirectional differential detection method according to a first aspect of the present invention includes: S1: The vibration of the seismic source excites a vibration wave, and the signal acquisition device collects the vibration signal records of the sensor. The vibration signal records of three sensors are extracted. The seismic source and the sensor group are arranged at intervals along the first direction. The sensor group includes at least three sensors arranged at intervals along the first direction. S2: Based on the time-domain differential detection method, the first vibration signal record after suppressing the direct transverse wave and Rayleigh surface wave between the main sensor and the front sensor is calculated, and the second vibration signal record after suppressing the direct transverse wave and Rayleigh surface wave between the main sensor and the rear sensor is calculated. The sensor in the middle is the main sensor, and the sensors on both sides are the front sensor and the rear sensor, respectively, with the main sensor as the reference. S3: The first vibration signal record and the second vibration signal record are horizontally superimposed to obtain a third vibration signal record that suppresses the direct transverse wave and Rayleigh surface wave and whose reflected wave phase and amplitude are regressed.

[0006] The bidirectional differential detection method according to embodiments of the present invention has at least the following beneficial effects: 1. When three sensors are selected, if the current sensor is closer to the vibration source, the rear sensor will receive the vibration signal before the main sensor, and the front sensor will receive the vibration signal after the main sensor. When the calculation is performed based on the main sensor and the time-domain differential detection method, the time difference between the main sensor and the front sensor is exactly opposite to the time difference between the main sensor and the rear sensor. This makes the direction of the reflected wave changed by the first vibration signal record and the direction of the reflected wave changed by the second vibration signal record exactly opposite. After horizontal superposition, the changed direction of the reflected wave in the first vibration signal record and the changed direction of the reflected wave in the second vibration signal record cancel each other out, realizing the regression of the reflected wave phase and amplitude. 2. At the same time, both the first and second seismic signal records suppressed the direct shear waves and Rayleigh surface waves using time-domain differential detection. After horizontal superposition, the first and second seismic signal records still suppressed the direct shear waves and Rayleigh surface waves, making the third seismic signal record more accurate. Subsequent seismic wave data processing is more convenient, easier to implement and promote in software, and improves the resolution of seismic exploration.

[0007] According to some embodiments of the present invention, it further includes: S11: Extract vibration signal records from multiple groups of the three sensors, wherein the sensor group includes at least four sensors that are sequentially spaced along the first direction; S21: Based on the vibration signal records of each group of sensors, repeat S2 to obtain multiple sets of the first vibration signal records after suppressing direct transverse waves and Rayleigh surface waves, and multiple sets of the second vibration signal records after suppressing direct transverse waves and Rayleigh surface waves. S31: Horizontally superimpose all the first vibration signal records and all the second vibration signal records to obtain the third vibration signal record that suppresses the direct transverse wave and Rayleigh surface wave and whose reflected wave phase and amplitude revert.

[0008] According to some embodiments of the present invention, in S11, the three sensors in each group are arranged adjacent to each other along the first direction.

[0009] According to some embodiments of the present invention, the method further includes: S4: moving the sensor group along the first direction to the next preset measurement position, repeating S1 to S3, and obtaining the third vibration signal record at the preset measurement position.

[0010] According to some embodiments of the present invention, in S1, the sensors are distributed at equal intervals along the first direction.

[0011] According to some embodiments of the present invention, the sensor is one or a combination of piezoelectric, magnetoelectric, capacitive, inductive, and fiber optic vibration sensors.

[0012] According to some embodiments of the present invention, the step of obtaining the first vibration signal record by the front sensor and the main sensor according to the time-domain differential detection method includes: S201: The seismic source excites vibration waves, and the signal acquisition device simultaneously acquires two vibration signal records captured by the main sensor and the front sensor, and obtains the time difference between the arrival of the direct transverse wave and the Rayleigh surface wave of the two vibration signal records through correlation analysis. S202: Static correction, using the main sensor as a reference, statically correct the arrival time difference of the direct transverse wave and Rayleigh surface wave recorded by the front sensor, so that it is the same as the initial arrival time of the direct transverse wave and Rayleigh surface wave recorded by the main sensor. S203: Amplitude compensation: Using the main sensor as a reference, amplitude compensation is performed on the amplitudes of the direct transverse wave and Rayleigh surface wave recorded by the front sensor, so that the amplitudes of the direct transverse wave and Rayleigh surface wave recorded by the main sensor and the front sensor are consistent. S204: Invert the recorded values ​​processed by the front sensor and superimpose them with the recorded values ​​of the main sensor to obtain the first vibration signal record after Rayleigh surface wave and direct transverse wave elimination at the coordinate point of the main sensor.

[0013] According to some embodiments of the present invention, the step of obtaining the second vibration signal record by the rear sensor and the main sensor according to the time-domain differential detection method includes: S205: The source of vibration excites vibration waves, and the signal acquisition device simultaneously acquires two vibration signal records captured by the main sensor and the rear sensor, and obtains the time difference between the arrival of the direct transverse wave and the Rayleigh surface wave through correlation analysis. S206: Static correction, using the main sensor as a reference, statically correct the arrival time difference of the direct transverse wave and Rayleigh surface wave recorded by the rear sensor, so that it is the same as the initial arrival time of the direct transverse wave and Rayleigh surface wave recorded by the main sensor. S207: Amplitude compensation, with the main sensor as a reference, amplitude compensation is performed on the amplitudes of the direct transverse wave and Rayleigh surface wave recorded by the rear sensor, so that the amplitudes of the direct transverse wave and Rayleigh surface wave recorded by the main sensor and the rear sensor are consistent. S208: Invert the recorded values ​​processed by the post-sensor and superimpose them with the recorded values ​​of the main sensor to obtain the second vibration signal record after Rayleigh surface wave and direct transverse wave elimination at the coordinate point of the main sensor.

[0014] According to some embodiments of the present invention, in S202 or S206, the static correction method is as follows: The time intervals of the Rayleigh surface wave and the direct transverse wave distributions on the two records are extracted to form vector signals X and Y. The simple correlation coefficient r is calculated according to the correlation coefficient calculation formula. r is used to measure the linear relationship between the two vectors, and the formula is defined as follows:

[0015] Where Cov(X,Y) is the covariance of X and Y, Var[X] is the variance of X, and Var[Y] is the variance of Y. The correlation coefficient between the two is calculated. Then, relative to the reference record, another record is shifted successively at one-hour time intervals, and the correlation is calculated successively. When the correlation coefficient is about 1, it means that the shift time is just right, and this time is the static correction time. Or, the correlation coefficient is the largest at a certain shift time, which also means that the correlation between the two vector signals is the best at that shift time point, and this time is the static correction time.

[0016] According to some embodiments of the present invention, the bidirectional differential detection method is used for seismic surveys, ultrasonic testing, or ground-penetrating radar testing.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein: Figure 1 This is a flowchart illustrating the steps of the bidirectional differential detection method according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the common-source adjacent three-sensor shot collection recording acquisition mode according to an embodiment of the present invention; Figure 3 The embodiments of the present invention include shot collection records of both direct waves and reflected waves; Figure 4 Direct waves were eliminated by using a "master-precedence" pair of records for time-domain differential detection; Figure 5 Direct waves were eliminated by using a "master-rear" pair of records for time-domain differential detection; Figure 6 This is a record formed by horizontally superimposing two records obtained by the main sensor after bidirectional differential. Figure 7 For extraction Figure 3 , Figure 4 , Figure 5 and Figure 6 Zoom in on details of the 40th record obtained from each process. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0020] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, etc., are based on the orientation or positional relationship shown in the drawings and are only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0021] In the description of this invention, "several" refers to one or more, and "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0022] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0023] Reference Figure 1 As shown, this invention proposes a bidirectional differential detection method, comprising: S1: The vibration of the seismic source excites a vibration wave, and the signal acquisition device collects the vibration signal records of the sensor. The vibration signal records of three sensors are extracted. The seismic source and the sensor group are arranged at intervals along the first direction. The sensor group includes at least three sensors arranged at intervals along the first direction. S2: Based on the time-domain differential detection method, the first vibration signal record after suppressing the direct transverse wave and Rayleigh surface wave between the main sensor and the front sensor is calculated, and the second vibration signal record after suppressing the direct transverse wave and Rayleigh surface wave between the main sensor and the rear sensor is calculated. The sensor in the middle is the main sensor, and the sensors on both sides are the front sensor and the rear sensor, respectively, with the main sensor as the reference. S3: The first vibration signal record and the second vibration signal record are horizontally superimposed to obtain a third vibration signal record that suppresses the direct transverse wave and Rayleigh surface wave and whose reflected wave phase and amplitude are regressed.

[0024] The time-domain differential detection method is described in Chinese invention patent application number CN202011131485.X, entitled "A Detection Method." Its principle is as follows: The arrival time difference of the direct transverse wave and Rayleigh surface wave on two records is obtained through correlation analysis; using the record obtained by the main sensor as a reference, the auxiliary sensor record undergoes static correction according to the arrival time difference of the direct transverse wave and Rayleigh surface wave to make it the same as the initial arrival time of the direct transverse wave or Rayleigh surface wave recorded by the main sensor; simultaneously, the amplitude of the direct transverse wave or Rayleigh surface wave on the two records is compared, and using the main sensor record as the standard, the auxiliary sensor record undergoes amplitude compensation for the direct transverse wave and Rayleigh surface wave to make it consistent with the main sensor record; the auxiliary sensor record after static correction and amplitude compensation is inverted to obtain the corresponding data. The auxiliary sensor can be a front sensor or a rear sensor.

[0025] Taking seismic survey as an example, seismic sources and sensor groups are arranged horizontally and at intervals on the ground surface. All sensors in the sensor group are also arranged horizontally, and the seismic source and all sensors are on the same straight line. After the arrangement is completed, the seismic source is activated, and the vibration signal records of the sensors in the sensor group are collected by a signal collector. The vibration signal records of three sensors are extracted, and based on the positions of the three sensors, the sensor located in the middle horizontally is determined to be the main sensor. The sensors on both sides of the main sensor are the front sensor and the rear sensor, respectively. When the rear sensor is closer to the seismic source, the rear sensor will receive the vibration signal before the main sensor, and the front sensor will receive the vibration signal after the main sensor. When the calculation is performed based on the main sensor and according to the time-domain differential detection method, the time difference between the main sensor and the front sensor is exactly opposite to the time difference between the main sensor and the rear sensor. This makes the direction of the reflected wave changed by the first vibration signal record obtained by the time-domain differential detection method exactly opposite to the direction of the reflected wave changed by the second vibration signal record. After horizontal superposition, the changed direction of the reflected wave in the first vibration signal record and the changed direction of the reflected wave in the second vibration signal record cancel each other out, realizing the regression of the reflected wave phase and amplitude.

[0026] Simultaneously, both the first and second seismic signal records suppressed direct shear waves and Rayleigh surface waves using time-domain differential detection. Even after horizontal superposition, the first and second seismic signal records still suppress these waves, resulting in a more accurate third seismic signal record. This facilitates subsequent seismic wave data processing, is easier to implement and promote in software, and improves the resolution of seismic exploration. This method can also be widely applied in seismic exploration, ultrasonic testing, and even ground-penetrating radar detection, demonstrating broad application prospects.

[0027] Reference Figure 1 As shown, in some specific embodiments of the present invention, it further includes: S11: Extract vibration signal records from multiple groups of the three sensors, wherein the sensor group includes at least four sensors that are sequentially spaced along the first direction; S21: Based on the vibration signal records of each group of sensors, repeat S2 to obtain multiple sets of the first vibration signal records after suppressing direct transverse waves and Rayleigh surface waves, and multiple sets of the second vibration signal records after suppressing direct transverse waves and Rayleigh surface waves. S31: Horizontally superimpose all the first vibration signal records and all the second vibration signal records to obtain the third vibration signal record that suppresses the direct transverse wave and Rayleigh surface wave and whose reflected wave phase and amplitude revert.

[0028] The selected set of three sensors can be any three sensors from all available sensors.

[0029] It is worth understanding that by recording vibration signals from multiple sets of three sensors, multiple first vibration signal records and multiple second vibration signal records are obtained. By accumulating multiple sets of data, the error is reduced, making the third vibration signal record obtained by horizontally superimposing all the first vibration signal records and all the second vibration signal records more accurate and closer to reality.

[0030] For ease of understanding, the following explanation uses a sensor group consisting of 5 sensors as an example. The following explanation does not constitute a specific limitation on this method.

[0031] The seismic source, sensor 1, sensor 2, sensor 3, sensor 4, and sensor 5 are arranged horizontally at intervals. In the following labels, sensor 1 is used to represent sensor 1, and so on. When selecting three sensors, the following combinations are possible: (1, 2, 3); (1, 2, 4); (1, 2, 5); (1, 3, 4); (1, 3, 5); (1, 4, 5); (2, 3, 4); (2, 3, 5); (2, 4, 5); (3, 4, 5). The first and second vibration signal records corresponding to each combination are calculated separately. This makes the third vibration signal record, obtained by horizontally superimposing all the first and second vibration signal records, more accurate and closer to reality.

[0032] Of course, another approach is to determine sensor number 3 as the primary sensor and then arrange the other sensors accordingly. Specific combinations include: (1, 3, 4); (1, 3, 5); (2, 3, 4); (2, 3, 5). This avoids the accumulation of duplicate data and increases accuracy and reliability while ensuring data accuracy.

[0033] Reference Figure 1 As shown, in some specific embodiments of the present invention, in S11, the three sensors in each group are arranged adjacent to each other along the first direction.

[0034] It is understandable that the accuracy of the first and second vibration signals obtained by sampling three adjacent sensors using the time-domain differential detection method is better. This avoids the situation where the distance between the front or rear sensor and the main sensor is too large, which would cause dispersion distortion of the direct transverse wave or Rayleigh surface wave, affecting the accuracy of the first and second vibration signals.

[0035] Specifically, taking a sensor group consisting of 5 sensors as an example, the three extracted sensors can be combined as follows: (1, 2, 3); (2, 3, 4); (3, 4, 5). Extending this to a more general approach, after excluding the first and last sensors along the horizontal direction in the sensor group, the remaining sensors can be used as the main sensors, with their adjacent sensors being the front and rear sensors, respectively.

[0036] The following example illustrates a specific implementation during seismic exploration. For instance, in seismic exploration, 60 shot gather records are obtained along a seismic line, meaning that 60 sensors sharing the same seismic source point simultaneously collect and record data. Figure 3 As shown. Records from track 2 to track 59 are taken sequentially as the main sensor records, and each is paired with the records obtained by its preceding and following adjacent sensors. Time-domain differential filtering is performed on each pair. After filtering, the first and second vibration signal records are horizontally superimposed. This processed record is then used as the third vibration signal record after eliminating direct shear waves and Rayleigh surface waves from tracks 2 to track 59. The filtered shot gather records are shown below. Figure 6 As shown.

[0037] Alternatively, when processing data from well-drilled seismic exploration or negative apparent velocity seismic exploration, it is necessary to suppress downlink direct waves, referring to... Figure 3The record is shown. Assuming that the first 30 common-source shot gather records are obtained, similar to the two embodiments mentioned above, the direct wave is taken as the interference wave to be filtered out. Records from the 2nd to the 29th are taken as the main sensor records, and they are paired with the records obtained by the sensors before and after them. Each of them is subjected to time-domain differential filtering. After filtering, the first vibration signal record and the second vibration signal record are horizontally superimposed. The processed record is used as the third vibration signal record after eliminating the direct shear wave and Rayleigh surface wave in channels 2 to 29.

[0038] Reference Figure 1 As shown, in some specific embodiments of the present invention, it further includes: S4: moving the sensor group along the first direction to the next preset measurement position, repeating S1 to S3, to obtain the third vibration signal record at the preset measurement position.

[0039] It is understandable that, in order to save on the equipment cost of purchasing sensors, only three sensors can be arranged to form a sensor group. Multiple recording points are set up sequentially along the first direction. The main sensor of the three sensors is placed on one recording point, and the other two sensors are set on both sides of the main sensor along the first direction to measure this recording point. After the measurement, the three sensors are moved so that the main sensor is located on the new recording point, and the measurement is repeated until all recording points have been detected.

[0040] The following example illustrates a specific implementation method used in seismic exploration. For instance, in seismic exploration, the source point and the sensor maintain a constant relative distance while performing isotropic mapping. (Refer to...) Figure 2 Using three identical sensors with a 6m offset and a 0.5m spacing between each pair, after each common-source three-sensor data acquisition, the middle sensor was identified as the master sensor. It, along with its preceding and following sensors, formed a recording pair with the master sensor as a reference. Time-domain differential filtering was performed on each pair. After filtering, the first and second seismic signal records were horizontally superimposed. This processed record served as the third seismic signal record after eliminating direct shear waves and Rayleigh surface waves, with the recording point falling on the master sensor's location. The isotropic mapping method was then used, with the seismic source and sensors moving synchronously along the survey line to the next work point. This acquisition process was repeated until all survey lines were completed. This yielded an isotropic seismic record profile along the entire survey line, which is a seismic record profile after eliminating direct shear waves and Rayleigh surface waves.

[0041] Reference Figure 1 As shown, in some specific embodiments of the present invention, in step S1, the sensors are distributed at equal intervals along the first direction. This more uniform sensor distribution reduces the influence of distance factors during measurement and improves measurement accuracy. In this embodiment, the distance between two adjacent sensors is 0.5 mm.

[0042] Reference Figure 1 As shown, in some specific embodiments of the present invention, the sensor is one or a combination of piezoelectric, magnetoelectric, capacitive, inductive, and fiber optic vibration sensors.

[0043] Reference Figure 1 As shown, in some specific embodiments of the present invention, the step of the front sensor and the main sensor obtaining the first vibration signal record according to the time-domain differential detection method includes: S201: The seismic source excites vibration waves, and the signal acquisition device simultaneously acquires two vibration signal records captured by the main sensor and the front sensor, and obtains the time difference between the arrival of the direct transverse wave and the Rayleigh surface wave of the two vibration signal records through correlation analysis. S202: Static correction, using the main sensor as a reference, statically correct the arrival time difference of the direct transverse wave and Rayleigh surface wave recorded by the front sensor, so that it is the same as the initial arrival time of the direct transverse wave and Rayleigh surface wave recorded by the main sensor. S203: Amplitude compensation: Using the main sensor as a reference, amplitude compensation is performed on the amplitudes of the direct transverse wave and Rayleigh surface wave recorded by the front sensor, so that the amplitudes of the direct transverse wave and Rayleigh surface wave recorded by the main sensor and the front sensor are consistent. S204: Invert the recorded values ​​processed by the front sensor and superimpose them with the recorded values ​​of the main sensor to obtain the first vibration signal record after Rayleigh surface wave and direct transverse wave elimination at the coordinate point of the main sensor.

[0044] Reference Figure 1 As shown, in some specific embodiments of the present invention, the step of the rear sensor and the main sensor obtaining the second vibration signal record according to the time-domain differential detection method includes: S205: The source of vibration excites vibration waves, and the signal acquisition device simultaneously acquires two vibration signal records captured by the main sensor and the rear sensor, and obtains the time difference between the arrival of the direct transverse wave and the Rayleigh surface wave through correlation analysis. S206: Static correction, using the main sensor as a reference, statically correct the arrival time difference of the direct transverse wave and Rayleigh surface wave recorded by the rear sensor, so that it is the same as the initial arrival time of the direct transverse wave and Rayleigh surface wave recorded by the main sensor. S207: Amplitude compensation, with the main sensor as a reference, amplitude compensation is performed on the amplitudes of the direct transverse wave and Rayleigh surface wave recorded by the rear sensor, so that the amplitudes of the direct transverse wave and Rayleigh surface wave recorded by the main sensor and the rear sensor are consistent. S208: Invert the recorded values ​​processed by the post-sensor and superimpose them with the recorded values ​​of the main sensor to obtain the second vibration signal record after Rayleigh surface wave and direct transverse wave elimination at the coordinate point of the main sensor.

[0045] According to some embodiments of the present invention, in S202 or S206, the static correction method is as follows: The time intervals of the Rayleigh surface wave and the direct transverse wave distributions on the two records are extracted to form vector signals X and Y. The simple correlation coefficient r is calculated according to the correlation coefficient calculation formula. r is used to measure the linear relationship between the two vectors, and the formula is defined as follows:

[0046] Where Cov(X,Y) is the covariance of X and Y, Var[X] is the variance of X, and Var[Y] is the variance of Y. The correlation coefficient between the two is calculated. Then, relative to the reference record, another record is shifted successively at one-hour time intervals, and the correlation is calculated successively. When the correlation coefficient is about 1, it means that the shift time is just right, and this time is the static correction time. Or, the correlation coefficient is the largest at a certain shift time, which also means that the correlation between the two vector signals is the best at that shift time point, and this time is the static correction time.

[0047] The above content is all the content described in the Chinese invention patent with application number CN202011131485.X, entitled "A Detection Method", and will not be repeated here.

[0048] Reference Figure 1 As shown, in some specific embodiments of the present invention, the bidirectional differential detection method is also used for seismic surveying, ultrasonic testing, or ground-penetrating radar testing. It is worth understanding that bidirectional differential detectors have a wide range of applications and broad application prospects.

[0049] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method of bidirectional differential detection, the method comprising: include: S1: The vibration of the seismic source excites a vibration wave, and the signal acquisition device collects the vibration signal records of the sensor. The vibration signal records of three sensors are extracted. The seismic source and the sensor group are arranged at intervals along the first direction. The sensor group includes at least three sensors arranged at intervals along the first direction. S2: Based on the time-domain differential detection method, the first vibration signal record after suppressing the direct transverse wave and Rayleigh surface wave between the main sensor and the front sensor is calculated, and the second vibration signal record after suppressing the direct transverse wave and Rayleigh surface wave between the main sensor and the rear sensor is calculated. The sensor in the middle is the main sensor, and the sensors on both sides are the front sensor and the rear sensor, respectively, with the main sensor as the reference. S3: The first vibration signal record and the second vibration signal record are horizontally superimposed to obtain a third vibration signal record that suppresses the direct transverse wave and Rayleigh surface wave and whose reflected wave phase and amplitude are regressed.

2. The bidirectional differential detection method of claim 1, wherein, Also includes: S11: Extract vibration signal records from multiple groups of the three sensors, wherein the sensor group includes at least four sensors that are sequentially spaced along the first direction; S21: Based on the vibration signal records of each group of sensors, repeat S2 to obtain multiple sets of the first vibration signal records after suppressing direct transverse waves and Rayleigh surface waves, and multiple sets of the second vibration signal records after suppressing direct transverse waves and Rayleigh surface waves. S31: Horizontally superimpose all the first vibration signal records and all the second vibration signal records to obtain the third vibration signal record that suppresses the direct transverse wave and Rayleigh surface wave and whose reflected wave phase and amplitude revert.

3. The method of claim 2, wherein: In S11, the three sensors in each group are arranged adjacent to each other along the first direction.

4. The bidirectional differential detection method of claim 1, wherein, Also includes: S4: Move the sensor group along the first direction to the next preset measurement position, and repeat S1 to S3 to obtain the third vibration signal record at the preset measurement position.

5. The method of claim 1, wherein: In S1, the sensors are distributed at equal intervals along the first direction.

6. The bidirectional differential detection method of claim 1, wherein: The sensor is one of piezoelectric, magnetoelectric, capacitive, inductive, or fiber optic vibration sensors, or a combination thereof.

7. The bidirectional differential detection method of claim 1, wherein: The steps for the front sensor and the main sensor to obtain the first vibration signal record according to the time-domain differential detection method include: S201: The seismic source excites vibration waves, and the signal acquisition device simultaneously acquires two vibration signal records captured by the main sensor and the front sensor, and obtains the time difference between the arrival of the direct transverse wave and the Rayleigh surface wave of the two vibration signal records through correlation analysis. S202: Static correction, using the main sensor as a reference, statically correct the arrival time difference of the direct transverse wave and Rayleigh surface wave recorded by the front sensor, so that the arrival times of the direct transverse wave and Rayleigh surface wave recorded by the front sensor and the main sensor are the same. S203: Amplitude compensation: Using the main sensor as a reference, amplitude compensation is performed on the amplitudes of the direct transverse wave and Rayleigh surface wave recorded by the front sensor, so that the amplitudes of the direct transverse wave and Rayleigh surface wave recorded by the main sensor and the front sensor are consistent. S204: Invert the recorded values ​​processed by the front sensor and superimpose them with the recorded values ​​of the main sensor to obtain the first vibration signal record after Rayleigh surface wave and direct transverse wave elimination at the coordinate point of the main sensor.

8. The bidirectional differential detection method of claim 1, wherein: The steps for the rear sensor and the main sensor to obtain the second vibration signal record according to the time-domain differential detection method include: S205: The source of vibration excites vibration waves, and the signal acquisition device simultaneously acquires two vibration signal records captured by the main sensor and the rear sensor, and obtains the time difference between the arrival of the direct transverse wave and the Rayleigh surface wave through correlation analysis. S206: Static correction, using the main sensor as a reference, statically correct the arrival time difference of the direct transverse wave and Rayleigh surface wave recorded by the rear sensor, so that the arrival times of the direct transverse wave and Rayleigh surface wave recorded by the rear sensor are the same as those of the main sensor. S207: Amplitude compensation, with the main sensor as a reference, amplitude compensation is performed on the amplitudes of the direct transverse wave and Rayleigh surface wave recorded by the rear sensor, so that the amplitudes of the direct transverse wave and Rayleigh surface wave recorded by the main sensor and the rear sensor are consistent. S208: Invert the recorded values ​​processed by the post-sensor and superimpose them with the recorded values ​​of the main sensor to obtain the second vibration signal record after Rayleigh surface wave and direct transverse wave elimination at the coordinate point of the main sensor.

9. The bidirectional differential detection method according to claim 7 or 8, characterized in that: In S202 or S206, the static correction method is as follows: The time intervals between the Rayleigh surface wave and the direct transverse wave distributions on the two records are extracted to form vector signals X and Y. The simple correlation coefficient r is calculated according to the correlation coefficient calculation formula. r is used to measure the linear relationship between the two vectors, and the formula is defined as follows: Where Cov(X,Y) is the covariance of X and Y, Var[X] is the variance of X, and Var[Y] is the variance of Y. The correlation coefficient between the two is calculated. Then, relative to the reference record, another record is shifted sequentially at one-hour time intervals, and the correlation is calculated sequentially. When the correlation coefficient is about 1, it means that the shift time is just right, and this time is the static correction time. Or, the correlation coefficient is the largest at a certain shift time, which also means that the correlation between the two vector signals is the best at that shift time point, and this time is the static correction time.

10. The bidirectional differential detection method of claim 1, wherein: The bidirectional differential detection method is used for seismic surveys, ultrasonic testing, or ground-penetrating radar testing.

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