CN115542392B - Automatic detection method and device for underground faults based on distributed optical fiber acoustic wave sensing - Google Patents

Abstract

The present disclosure provides an automatic detection method and device for underground faults based on distributed optical fiber acoustic wave sensing, which can be applied to the technical fields of underground fault detection and earthquake analysis. The method includes: obtaining seismic data recorded by an optical fiber seismograph, wherein the optical fiber of the optical fiber seismograph is distributed in the area of the underground fault to be identified; performing frequency wavenumber filtering on the seismic data to obtain scattered wave data from which direct wave signal data and noise signal data are filtered out; determining the scattering intensity of all scattered waves in the waveform diagram of the scattered wave data using a traceability pane; integrating the scattering intensity in the time domain to obtain an integrated result; and determining the location of the underground fault according to the integrated result and the optical fiber distribution of the optical fiber seismograph.

Description

Automatic detection method and device for underground faults based on distributed optical fiber acoustic wave sensing

Technical Field

The present disclosure relates to the technical field of underground fault detection and earthquake analysis, and more specifically, to an automatic underground fault detection method, device, electronic device and storage medium based on distributed optical fiber acoustic wave sensing.

Background technique

Underground faults are the source of earthquakes. When an earthquake occurs, underground faults suddenly shift rapidly, causing strong ground movement and surface rupture and deformation, which causes serious damage or collapse of most houses along the faults, posing a huge threat to human life and property. When constructing a city, identifying the distribution of underground faults in advance and constructing buildings outside their safe avoidance distance can significantly reduce the disaster risk caused by underground fault activity.

In the process of realizing the concept of the present disclosure, the inventors found that there are at least the following problems in the related art: In the related art, the method of detecting the location of underground faults requires complex data processing, which is time-consuming and cannot be popularized.

Summary of the invention

In view of this, the present disclosure provides a method, device, electronic device and storage medium for automatic detection of underground faults based on distributed optical fiber acoustic wave sensing.

One aspect of the present disclosure provides a method for automatic detection of underground faults based on distributed optical fiber acoustic wave sensing, comprising:

Acquiring seismic data recorded by a fiber optic seismograph, wherein the optical fiber of the fiber optic seismograph is distributed in the area where the underground fault is to be identified;

Perform frequency wavenumber filtering on the seismic data to obtain scattered wave data after filtering out direct wave signal data and noise signal data;

Use the traceability pane to determine the scattering intensity of all scattered waves in the waveform graph of the scattered wave data;

Integrate the scattering intensity in the time domain to obtain an integrated result; and

The location of the underground fault is determined based on the integration results and the optical fiber distribution of the fiber optic seismograph.

According to an embodiment of the present disclosure, before performing frequency wavenumber filtering on the seismic data to obtain scattered wave data from which direct wave signal data and noise signal data are filtered out, the method further includes:

Determining shock wave noise data in the seismic data, wherein the shock wave noise data is noise data caused by non-seismic waves;

The shock wave noise data in the seismic data is modified to eliminate the influence of the shock wave noise data.

According to an embodiment of the present disclosure, determining shock wave noise data in seismic data includes:

Selecting a predetermined number of reference data according to the positions of each sampling point of the seismic data;

When the ratio of the strain rate amplitude of the seismic data at the sampling point to the strain rate amplitude of the reference data is greater than a preset threshold, the seismic data at the sampling point is determined to be shock wave noise data.

According to an embodiment of the present disclosure, the shock wave noise data in the seismic data is modified to eliminate the influence of the shock wave noise data, including:

Based on the seismic data acquired from the sampling points adjacent to the shock wave noise data, the shock wave noise data in the seismic data is modified to eliminate the influence of the shock wave noise data.

According to an embodiment of the present disclosure, determining the scattering intensity of all scattered waves in a waveform diagram of scattered wave data using a source tracing pane includes:

Use the Source Trace pane to identify all scattering sources in the waveform graph of the scattered wave data;

For each scatter source:

The other scattering sources on both sides of the scattering source are superimposed at a preset apparent velocity to obtain two column vectors representing the unidirectional propagation of the scattering wave field;

Based on the dot product result of the two column vectors, the scattering intensity of the scattered wave is determined.

According to an embodiment of the present disclosure, frequency wavenumber filtering is performed on seismic data to obtain scattered wave data from which direct wave signal data and noise signal data are filtered out, including:

The seismic data in the distance-time domain are converted into the frequency-wavenumber domain by Fourier transformation;

The direct wave signal and the noise signal in the seismic data are filtered out using preset parameters to obtain the scattered wave data in the frequency wave number domain;

The scattered wave data in the frequency-wavenumber domain are inversely transformed to obtain the scattered wave data in the distance-time domain.

According to an embodiment of the present disclosure, before converting the seismic data in the range-time domain into the frequency-wavenumber domain by Fourier transform, the method further includes:

Normalizing the seismic data to obtain normalized seismic data;

The edge waveforms of the waveform diagram of the normalized seismic data are subjected to waveform pinching to reduce false signals caused by the edge waveforms.

Another aspect of the present disclosure provides an automatic detection device for underground faults based on distributed optical fiber acoustic wave sensing, comprising:

An acquisition module, used for acquiring seismic data recorded by a fiber optic seismograph, wherein the optical fiber of the fiber optic seismograph is distributed in an area of the underground fault to be identified;

The first obtaining module is used to perform frequency wavenumber filtering on the seismic data to obtain scattered wave data after filtering out direct wave signal data and noise signal data;

A first determination module is used to determine the scattering intensity of all scattered waves in the waveform diagram of the scattered wave data by using the traceability pane;

The second obtaining module is used to integrate the scattering intensity in the time domain to obtain an integral result;

The second determination module is used to determine the location of the underground fault according to the integration result and the optical fiber distribution of the optical fiber seismograph.

Another aspect of the present disclosure provides an electronic device, comprising: one or more processors; and a memory for storing one or more programs, wherein when the one or more programs are executed by the one or more processors, the one or more processors implement the above-mentioned automatic detection method of underground faults based on distributed optical fiber acoustic wave sensing.

Another aspect of the present disclosure provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, causes the processor to execute the above-mentioned method for automatic detection of underground faults based on distributed optical fiber acoustic wave sensing.

According to the embodiments of the present disclosure, a method is adopted to obtain seismic data recorded by a fiber optic seismograph, wherein the optical fiber of the fiber optic seismograph is distributed in the area of the underground fault to be identified; the seismic data is subjected to frequency wavenumber filtering to obtain scattered wave data after filtering out direct wave signal data and noise signal data; the scattering intensity of all scattered waves is determined in the waveform diagram of the scattered wave data using a tracing pane; the scattering intensity is integrated in the time domain to obtain an integrated result; and a technical means for determining the position of the underground fault according to the integrated result and the optical fiber distribution of the fiber optic seismograph is used. The scattering intensity of all scattered waves can be determined based on the scattered wave data after filtering out the direct wave signal data and the noise signal data using the tracing pane, without the need for complex data processing, and then the position of the underground fault within the optical fiber distribution range of the fiber optic seismograph is determined based on the scattering intensity of the scattered wave. This method is simple and fast, and the position of the underground fault can be accurately located. Therefore, the method at least partially overcomes the technical problems in the related art that the method for detecting the position of the underground fault requires complex data processing, is time-consuming, and cannot be popularized. The method has the same detection capability for smaller underground faults and blind faults, is low-cost and easy to promote.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

FIG1 schematically shows a flow chart of an automatic underground fault detection method based on distributed optical fiber acoustic wave sensing according to an embodiment of the present disclosure;

FIG2 schematically shows a schematic diagram of a waveform diagram of seismic data recorded by a fiber optic seismograph;

FIG3 schematically shows a schematic diagram of the form of a source tracing pane in a waveform diagram of seismic data;

FIG4 schematically shows a schematic diagram of the scattering intensity and integration result of the scattered waves in the seismic data of a single seismic event;

FIG5 schematically shows a schematic diagram of the scattering intensity and integration results of scattered waves in seismic data of multiple seismic events;

FIG6 schematically shows a schematic diagram of converting seismic data from the range-time domain to the frequency-wavenumber domain for filtering;

FIG7 schematically shows a block diagram of an automatic underground fault detection device based on distributed optical fiber acoustic wave sensing according to an embodiment of the present disclosure; and

FIG8 schematically shows a block diagram of an electronic device suitable for implementing the above-described method for automatic detection of underground faults based on distributed optical fiber acoustic wave sensing according to an embodiment of the present disclosure.

Detailed ways

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "include", "comprising", etc. used herein indicate the existence of the features, steps, operations and/or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

In the case of using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and/or A, B, C, etc.). In the case of using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted in accordance with the meaning of the expression generally understood by those skilled in the art (for example, "a system having at least one of A, B, or C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and/or A, B, C, etc.).

Earthquakes are caused by the rapid release of energy from the medium inside the earth's crust. Part of the energy released is propagated and diffused in the form of elastic waves, i.e., seismic waves. Seismic waves can be divided into two types: body waves and surface waves (L waves). Body waves include transverse waves (S waves) and longitudinal waves (P waves).

An underground fault is a structure where the earth's crust breaks under stress, and the rocks on both sides of the fault surface undergo significant relative displacement, which changes the physical properties of the medium inside, such as the seismic wave velocity and rheological properties. When seismic waves pass through an underground fault, due to the local heterogeneity, the underground fault will behave as a scatterer, causing the body waves to scatter toward the surface waves, causing severe damage to buildings, etc. Therefore, it is necessary to determine the location of the underground fault so as to reduce the damage caused by an earthquake.

In the related art, one method of identifying underground faults is the geological survey method, which generally involves sending a geological survey team to conduct on-site surface observations. This method has high labor costs and is difficult to detect small faults and blind faults. Other methods for imaging blind faults also have their own defects. For example, the tomography method has a low resolution and cannot image small faults; the active source 3D seismic mapping method is too expensive and is not suitable for large-scale surveys.

Due to the high frequency and fast attenuation of the scattered waves of underground faults, it is difficult for traditional seismic instruments to capture the signal. As an emerging technology, distributed fiber optic seismometers set ordinary optical fibers into dense arrays to detect the axial strain rate of the surface. The high spatial frequency enables it to observe fault scattering signals. In addition, the amplitude amplification effect of the fault zone medium on the strain rate is much greater than the amplification of the velocity field detected by traditional seismographs, which also provides advantages for distributed optical fiber sampling of fault scattering signals, allowing the development of underground fault detection methods. The recording of distributed optical fiber data usually uses background noise interferometry and back-projection methods, which can detect and accurately locate underground faults, but such methods still require researchers to perform complex data processing, which is time-consuming and not easy to popularize. Therefore, there is a need for a simple and fast underground fault detection method that has the same detection capability for small faults and blind faults, is low-cost and easy to promote.

In view of this, an embodiment of the present disclosure provides an automatic detection method for underground faults based on distributed optical fiber acoustic wave sensing. The method includes acquiring seismic data recorded by an optical fiber seismograph, wherein the optical fiber of the optical fiber seismograph is distributed in the area of the underground fault to be identified; performing frequency wavenumber filtering on the seismic data to obtain scattered wave data from which direct wave signal data and noise signal data are filtered out; determining the scattering intensity of all scattered waves in the waveform diagram of the scattered wave data using a traceability pane; integrating the scattering intensity in the time domain to obtain an integrated result; and determining the location of the underground fault based on the integrated result and the optical fiber distribution of the optical fiber seismograph.

FIG1 schematically shows a flow chart of a method for automatic detection of underground faults based on distributed optical fiber acoustic wave sensing according to an embodiment of the present disclosure.

As shown in FIG. 1 , the method includes operations S101 to S105 .

In operation S101 , seismic data recorded by a fiber optic seismograph is acquired, wherein the optical fiber of the fiber optic seismograph is distributed in a region where an underground fault is to be identified.

According to an embodiment of the present disclosure, the fiber optic seismograph may be a distributed fiber optic seismograph. The total length of a distributed fiber optic seismograph is generally ten to several dozen kilometers, and is often distributed in a linear manner. In areas where earthquake disasters occur frequently, the optical fiber of the distributed fiber optic seismograph may intersect with multiple known or unknown faults. When an earthquake occurs, the seismic waves passing through the area are detected by the fiber optic seismograph, thereby generating seismic data.

According to the embodiments of the present disclosure, each earthquake that occurs can be recorded as a seismic event, and the seismic data can be data obtained by detecting one seismic event or data obtained by detecting multiple seismic events. In the case of selecting multiple seismic events, in order to reduce the interference of human activity noise signals (such as traffic noise), seismic events that occur at night can be screened out, for example, seismic events from 23:00 to 7:00 the next day. In addition, manually screening events with high signal-to-noise ratios can also help produce optimal detection results, but is not limited to this.

According to an embodiment of the present disclosure, the optical fiber of the fiber optic seismograph can be used as a sampling point at a certain distance, and the time and position of the seismic wave passing through the optical fiber sampling point can be recorded in the seismic data. The optical fiber of a sampling point can have multiple channels for sampling.

According to the embodiments of the present disclosure, there are strong low-velocity anomalies in the medium of the underground fault. This velocity anomaly causes the body waves of the earthquake to be scattered as surface waves in the form of secondary sources when passing through. The measurement of surface strain rate by distributed optical fiber is on the order of meters and belongs to a dense array. The high spatial sampling rate characteristic of the fiber optic seismometer significantly improves its detection capability of high-frequency signals on the surface compared to traditional seismometers, and can record high-quality fault scattered waves. The fault scattered wave field in the linear optical fiber recording shows a "human" shaped feature.

FIG. 2 schematically shows a schematic diagram of a waveform diagram of seismic data recorded by a fiber optic seismograph.

As shown in Figure 2, the earthquake event is the seismic data recorded by a 10km long distributed optical fiber deployed in a certain place. As can be seen from Figure 2, the first obvious seismic phase to arrive is the P wave (about 7-8s), and the second obvious seismic phase to arrive is the S wave (about 8.5-10s). The three square boxes in Figure 2 are three obvious scattered wave fields excited by the P-wave coda and the S-wave coda, which are in the shape of a "human" on the waveform. This type of scattered signal is inferred to be emitted by underground faults.

In operation S102, frequency wavenumber filtering is performed on the seismic data to obtain scattered wave data from which direct wave signal data and noise signal data are filtered out.

According to the embodiments of the present disclosure, the wave field of seismic waves in seismic data can be analyzed and separated through frequency wave-number filtering (Frequency Wave-number, referred to as FK filtering), and the wave field of seismic waves can be filtered from three dimensions of frequency, wave number and apparent velocity to weaken the direct wave signal and noise signal, and obtain the scattered wave data emitted by the underground fault.

In operation S103, the scattering intensities of all scattered waves are determined in a waveform graph of the scattered wave data using the source tracing pane.

According to the embodiments of the present disclosure, the prestack migration technology in seismic exploration can return the reflected waves in the common shot point gather records to the reflection interface, and make the diffraction waves converge to the diffraction point that produces it. With the help of the idea of the migration method, strictly based on the physical essence, we proposed a variable slope tilt tracing pane that comprehensively measures the duration, symmetry and phase consistency to trace the scattered waves emitted by the underground fault. The waveform of the scattered wave data is recorded according to the time and position of the optical fiber, so the tracing pane can be scaled by the time and position of the waveform.

According to an embodiment of the present disclosure, the scattering intensity of the scattered wave can be obtained based on the scattered wave in the tracing window pane.

In operation S104, the scattered intensity is integrated in the time domain to obtain an integration result.

According to an embodiment of the present disclosure, the scattering intensity of the scattered wave can be integrated in the time domain to obtain an integrated result. According to the propagation characteristics of seismic waves in underground faults, the integrated result can represent the scattered wave intensity distribution of the underground fault in the area where the underground fault is to be identified.

In operation S105, the location of the underground fault is determined according to the integration result and the fiber distribution of the fiber optic seismograph.

According to an embodiment of the present disclosure, the position where the scattered wave is stronger in the integration result may be caused by an underground fault. According to the fiber distribution of the fiber optic seismograph, the fiber position corresponding to the position of the scattered wave is determined and determined as the position of the underground fault.

According to the embodiments of the present disclosure, a method is adopted to obtain seismic data recorded by a fiber optic seismograph, wherein the optical fiber of the fiber optic seismograph is distributed in the area of the underground fault to be identified; the seismic data is subjected to frequency wavenumber filtering to obtain scattered wave data after filtering out direct wave signal data and noise signal data; the scattering intensity of all scattered waves is determined in the waveform diagram of the scattered wave data using a tracing pane; the scattering intensity is integrated in the time domain to obtain an integrated result; and a technical means for determining the position of the underground fault according to the integrated result and the optical fiber distribution of the fiber optic seismograph is used. The scattering intensity of all scattered waves can be determined based on the scattered wave data after filtering out the direct wave signal data and the noise signal data using the tracing pane, without the need for complex data processing, and then the position of the underground fault within the optical fiber distribution range of the fiber optic seismograph is determined based on the scattering intensity of the scattered wave. This method is simple and fast, and the position of the underground fault can be accurately located. Therefore, the method at least partially overcomes the technical problems in the related art that the method for detecting the position of the underground fault requires complex data processing, is time-consuming, and cannot be popularized. The method has the same detection capability for smaller underground faults and blind faults, is low-cost and easy to promote.

According to an embodiment of the present disclosure, before performing frequency wavenumber filtering on the seismic data to obtain scattered wave data from which direct wave signal data and noise signal data are filtered out, the method further includes:

Determining shock wave noise data in the seismic data, wherein the shock wave noise data is noise data caused by non-seismic waves;

The shock wave noise data in the seismic data is modified to eliminate the influence of the shock wave noise data.

According to the embodiments of the present disclosure, in the waveform of seismic data, there may be sudden abnormal waveforms, which may be caused by animals such as mice and insects suddenly passing near the optical fiber, or may be caused by the fiber optic seismometer itself. We define these noise data that are not caused by seismic waves as shock wave noise data.

According to the embodiment of the present disclosure, the data of all channels of a certain sampling point in the seismic data are considered uniformly, and the regional deviation of each point is defined. d ₁ and d ₂ are the absolute values of the difference between the seismic data of the sampling point and the adjacent sampling points on the left and right. The 3σ principle is often used in statistics, and the three standard deviations above and below the statistical mean are used as thresholds to measure outliers. Referring to its idea, we introduce a robust measurement that is more adaptable to outliers in the data set than the standard deviation, namely the Median Absolute Deviation (MAD). Data points with regional deviation d greater than 5 times the regional deviation median MAD are marked as outliers, and according to the characteristics of shock wave noise data appearing in a single channel and without continuity, the outliers in the seismic data are automatically adjusted and screened to determine the shock wave noise data, and then the shock wave noise data is modified to a value that will not affect the underground fault, thereby eliminating the impact of the shock wave noise data.

According to an embodiment of the present disclosure, determining shock wave noise data in seismic data includes:

Selecting a predetermined number of reference data according to the positions of each sampling point of the seismic data;

When the ratio of the strain rate amplitude of the seismic data at the sampling point to the strain rate amplitude of the reference data is greater than a preset threshold, the seismic data at the sampling point is determined to be shock wave noise data.

According to an embodiment of the present disclosure, the predetermined number may be 5 channels. For example, with respect to the position of a sampling point, the same sampling point in the 5 channels to the left and right of the sampling point may be selected to form a set of reference data.

According to an embodiment of the present disclosure, the seismic data of the sampling point can be divided by the strain rate amplitude of the maximum value in the reference data to obtain a ratio, and the predetermined threshold can be set to 2. When the ratio is greater than 2, the seismic data of the sampling point is determined to be shock wave noise data, that is, the strain rate amplitude of the sampling point is greater than 2 times the maximum value in the reference data group.

According to an embodiment of the present disclosure, when a predetermined number of sampling points cannot be selected, the data of the sampling point can be discarded. This is because optical fibers are generally distributed widely and the intervals between sampling points are generally a few meters, which usually does not cause any impact.

According to an embodiment of the present disclosure, the shock wave noise data in the seismic data is modified to eliminate the influence of the shock wave noise data, including:

Based on the seismic data acquired from the sampling points adjacent to the shock wave noise data, the shock wave noise data in the seismic data is modified to eliminate the influence of the shock wave noise data.

According to an embodiment of the present disclosure, when the shock wave noise data is determined, data of sampling points adjacent to the sampling points of the shock wave noise data may be acquired, and interpolation may be performed to replace the measured value of the shock wave noise data.

According to an embodiment of the present disclosure, determining the scattering intensity of all scattered waves in a waveform diagram of scattered wave data using a source tracing pane includes:

Use the Source Trace pane to identify all scattering sources in the waveform graph of the scattered wave data;

For each scatter source:

The other scattering sources on both sides of the scattering source are superimposed at a preset apparent velocity to obtain two column vectors representing the unidirectional propagation of the scattering wave field;

Based on the dot product result of the two column vectors, the scattering intensity of the scattered wave is determined.

FIG3 schematically shows a schematic diagram of the appearance of a source tracing pane in a waveform diagram of seismic data.

As shown in Figure 3, the source tracing pane takes a certain point on the waveform as an assumed scattering source. When the body wave coda reaches the optical fiber, the duration of the scattering source continuously scattering the surface wave outward is set to t, the number of sampling points is n _t = d _t * f _s , where d _t is the interval of the sampling points, and f _s is the sampling frequency. The propagation distance of the scattered surface wave from the optical fiber axis to both sides before the attenuation front is set to x, and the number of channels on each side where the scattered surface wave is detected is n _x = x/d _x , where d _x is the channel interval of the same sampling point. The apparent velocity of the scattered surface wave is constrained to be within a certain range (generally 100 to 1000 m/s), and n _t sampling points are selected after the scattering source starts scattering. The wave field data recorded by the n _x channels on the left and right of the scattering source are tilted and superimposed according to a certain assumed apparent velocity to obtain two column vectors representing the unidirectional propagation of the scattered wave field. The point product of the two column vectors representing the unidirectional propagation of the scattered wave field is used as the scattering intensity of the scattered wave at the assumed apparent velocity. The apparent velocities of the scattered waves within the constraint range are traversed, and the tracing result with the highest scattering intensity is searched as the scattering intensity of the point.

According to an embodiment of the present disclosure, after expanding seismic data points of the same width as the source tracing pane on both sides of the waveform graph of seismic data, the source tracing pane is used to scan the scattered wave data after frequency wave number filtering to obtain the scattering intensity of a single seismic event, as shown in FIG4 .

FIG. 4 schematically shows a schematic diagram of the scattering intensity and integration result of the scattered waves in the seismic data of a single seismic event.

As shown in Fig. 4, scattering intensity graph 401 shows the scattering intensity of the scattered waves in the seismic data of a single earthquake event, and integral result graph 402 shows the integral result in the time domain according to scattering intensity graph 401. In integral result graph 402, three significant peaks are shown, which are inferred to be three underground faults intersecting with the optical fiber in the region. According to the time information from the body wave to the optical fiber sampling point in the seismic data, the seismic waveforms within the range of the P-wave coda and the S-wave coda can be scanned respectively to obtain the scattering intensity distribution of the two types of body wave coda waves with stronger analyzability.

FIG5 schematically shows a schematic diagram of the scattering intensity and integration results of scattered waves in seismic data of multiple seismic events.

As shown in Fig. 5, scattering intensity graph 501 shows the scattering intensity of scattered waves in the seismic data of 154 seismic events with the same sampling points as the seismic data of a single seismic event in Fig. 4, and integration result graph 502 shows the integration result in the time domain according to scattering intensity graph 501. In integration result graph 502, three significant peaks are also shown, which are inferred to be three underground faults intersecting with the optical fiber in the region, and the positions of the three underground faults are basically corresponding to the results of the Quaternary fault and fold database of a certain geological survey bureau, which is consistent with the seismological research on the same region.

Combining the results of Figures 4 and 5, it can be seen that the underground fault location obtained by the underground fault detection method provided in the embodiment of the present disclosure is true and accurate, consistent with the actual situation, and also has a certain accuracy and reliability for determining the location of the underground fault based on the seismic data of a single earthquake event with good data quality; using multiple earthquake events in the data set for detection can obtain more accurate and smooth results; the small standard deviation of the detection results shows that this method has good robustness and stability.

According to an embodiment of the present disclosure, frequency wavenumber filtering is performed on seismic data to obtain scattered wave data from which direct wave signal data and noise signal data are filtered out, including:

The seismic data in the distance-time domain are converted into the frequency-wavenumber domain by Fourier transformation;

The direct wave signal and the noise signal in the seismic data are filtered out using preset parameters to obtain the scattered wave data in the frequency wave number domain;

The scattered wave data in the frequency-wavenumber domain are inversely transformed to obtain the scattered wave data in the distance-time domain.

According to the embodiments of the present disclosure, the elastic wave field has two expressions: the distance-time (x-t) domain and the frequency-wavenumber (f-k) domain, which are equivalent and can be converted into each other. For seismic data measured by distributed optical fiber with equal spacing, its waveform is the wave field in the discrete x-t domain.

FIG6 schematically shows a schematic diagram of converting seismic data from the range-time domain to the frequency-wavenumber domain for filtering.

As shown in FIG6 , a two-dimensional fast Fourier transform can be used to transform the initial distance time domain waveform 601 from the x-t domain to the initial frequency wave number domain spectrum 602. In the spectrum of the f-k domain of the initial frequency wave number domain spectrum 602, the horizontal axis corresponds to the frequency of the seismic wave, and the vertical axis corresponds to the wave number of the seismic wave. Since the wave number k = 2π/λ, the wave velocity v = λ·f = 2πf/λ, and the slope of the f-k spectrum corresponds to the apparent velocity of the seismic wave in the optical fiber axis. The signal to be filtered can be set to zero by custom parameters or default parameters, that is, the direct wave signal and the noise signal in the seismic data are filtered out by using preset parameters to obtain the target frequency wave number domain spectrum 603, and then the target frequency wave number domain spectrum 603 in the frequency wave number domain is inversely transformed back to the x-t domain to obtain the target distance time domain waveform 604 in which the direct wave and the noise signal are filtered out and the scattered wave is retained.

According to the embodiments of the present disclosure, the direct wave signal and the noise signal in the seismic data are filtered out, which can effectively eliminate the influence of the direct wave signal and the noise signal on the determination of the underground fault location, and can accurately determine the location of the underground fault.

According to an embodiment of the present disclosure, before converting the seismic data in the range-time domain into the frequency-wavenumber domain by Fourier transform, the method further includes:

Normalizing the seismic data to obtain normalized seismic data;

The edge waveforms of the waveform diagram of the normalized seismic data are subjected to waveform pinching to reduce false signals caused by the edge waveforms.

According to an embodiment of the present disclosure, in order to reduce the amount of calculation, the seismic data in the distance-time domain can be normalized before being converted into the frequency-wavenumber domain through Fourier transform to obtain normalized seismic data. For example, the z-score method can be used to normalize the data to obtain normalized seismic data.

According to an embodiment of the present disclosure, since the edge value of the waveform graph of normalized seismic data may be large, thereby causing a false signal to appear, the edge waveform of the waveform graph of normalized seismic data may be subjected to waveform pinching-out. For example, a 1/2 cosine function may be used to perform waveform pinching-out on the upper and lower edges (time domain) and the left and right edges (spatial domain) of the waveform graph, respectively.

FIG7 schematically shows a block diagram of an automatic underground fault detection device based on distributed optical fiber acoustic wave sensing according to an embodiment of the present disclosure.

As shown in FIG. 7 , the automatic detection device 700 for underground faults based on distributed optical fiber acoustic wave sensing includes an acquisition module 710 , a first obtaining module 720 , a first determining module 730 , a second obtaining module 740 and a second determining module 750 .

An acquisition module 710 is used to acquire seismic data recorded by a fiber optic seismograph, wherein the optical fiber of the fiber optic seismograph is distributed in an area of the underground fault to be identified;

The first obtaining module 720 is used to perform frequency wavenumber filtering on the seismic data to obtain scattered wave data after filtering out direct wave signal data and noise signal data;

A first determination module 730 is used to determine the scattering intensity of all scattered waves in the waveform diagram of the scattered wave data by using the traceability pane;

A second obtaining module 740 is used to integrate the scattering intensity in the time domain to obtain an integration result;

The second determination module 750 is used to determine the location of the underground fault according to the integration result and the fiber distribution of the fiber optic seismograph.

According to an embodiment of the present disclosure, the above device further includes:

A third determination module is used to determine shock wave noise data in the seismic data before performing frequency wave number filtering on the seismic data to obtain scattered wave data from which direct wave signal data and noise signal data are filtered out, wherein the shock wave noise data is noise data caused by non-seismic waves;

The modification module is used to modify the shock wave noise data in the seismic data to eliminate the influence of the shock wave noise data.

According to an embodiment of the present disclosure, the third determination module for determining shock noise data in seismic data includes:

A first determining unit is used to select a predetermined number of reference data according to the positions of each sampling point of the seismic data;

The second determination unit is configured to determine the seismic data at the sampling point as shock wave noise data when the ratio of the strain rate amplitude of the seismic data at the sampling point to the strain rate amplitude of the reference data is greater than a preset threshold.

According to an embodiment of the present disclosure, a modification module for modifying shock wave noise data in seismic data to eliminate the influence of the shock wave noise data includes:

The modification unit is used to modify the shock wave noise data in the seismic data based on the seismic data acquired from the sampling points adjacent to the shock wave noise data, so as to eliminate the influence of the shock wave noise data.

According to an embodiment of the present disclosure, the first determination module for determining the scattering intensity of all scattered waves in the waveform diagram of scattered wave data by using the source tracing pane includes:

A third determining unit is used to determine all scattering sources in the waveform diagram of the scattered wave data by using the source tracing pane;

For each scatter source:

The other scattering sources on both sides of the scattering source are superimposed at a preset apparent velocity to obtain two column vectors representing the unidirectional propagation of the scattering wave field;

Based on the dot product result of the two column vectors, the scattering intensity of the scattered wave is determined.

According to an embodiment of the present disclosure, the first obtaining module for performing frequency wavenumber filtering on seismic data to obtain scattered wave data from which direct wave signal data and noise signal data are filtered out includes:

A first obtaining unit is used to convert the seismic data in the distance time domain into the frequency wave number domain through Fourier transformation;

The second obtaining unit is used to filter the direct wave signal and the noise signal in the seismic data by using preset parameters to obtain the scattered wave data in the frequency wave number domain;

The third obtaining unit is used to inversely transform the scattered wave data in the frequency wave number domain to obtain the scattered wave data in the distance time domain.

According to an embodiment of the present disclosure, the above device further includes:

A normalization module is used to normalize the seismic data in the distance time domain before converting the seismic data in the frequency wave number domain through Fourier transform to obtain normalized seismic data;

The waveform pinch-out module is used to pinch out the edge waveforms of the waveform diagram of normalized seismic data to reduce false signals caused by edge waveforms.

According to the embodiments of the present invention, any one or more of the modules, submodules, units, and subunits, or at least part of the functions of any one of them can be implemented in one module. According to the embodiments of the present invention, any one or more of the modules, submodules, units, and subunits can be split into multiple modules for implementation. According to the embodiments of the present invention, any one or more of the modules, submodules, units, and subunits can be at least partially implemented as hardware circuits, such as field programmable gate arrays (FPGAs), programmable logic arrays (PLAs), systems on chips, systems on substrates, systems on packages, application specific integrated circuits (ASICs), or can be implemented by hardware or firmware in any other reasonable way of integrating or packaging the circuit, or implemented in any one of the three implementation methods of software, hardware, and firmware, or in any appropriate combination of any of them. Alternatively, according to the embodiments of the present invention, one or more of the modules, submodules, units, and subunits can be at least partially implemented as computer program modules, and when the computer program modules are run, the corresponding functions can be performed.

For example, any of the acquisition module 710, the first acquisition module 720, the first determination module 730, the second acquisition module 740 and the second determination module 750 can be combined in one module/unit/subunit for implementation, or any of the modules/units/subunits can be split into multiple modules/units/subunits. Alternatively, at least part of the functions of one or more modules/units/subunits in these modules/units/subunits can be combined with at least part of the functions of other modules/units/subunits and implemented in one module/unit/subunit. According to an embodiment of the present disclosure, at least one of the acquisition module 710, the first acquisition module 720, the first determination module 730, the second acquisition module 740 and the second determination module 750 can be at least partially implemented as a hardware circuit, such as a field programmable gate array (FPGA), a programmable logic array (PLA), a system on a chip, a system on a substrate, a system on a package, an application specific integrated circuit (ASIC), or can be implemented by hardware or firmware such as any other reasonable way of integrating or packaging the circuit, or by any one of the three implementation methods of software, hardware and firmware or by a suitable combination of any of them. Alternatively, at least one of the acquisition module 710, the first obtaining module 720, the first determining module 730, the second obtaining module 740 and the second determining module 750 may be at least partially implemented as a computer program module, which may perform a corresponding function when executed.

It should be noted that the part of the automatic detection device for underground faults based on distributed optical fiber acoustic wave sensing in the embodiments of the present disclosure corresponds to the part of the automatic detection method for underground faults based on distributed optical fiber acoustic wave sensing in the embodiments of the present disclosure. The description of the part of the automatic detection device for underground faults based on distributed optical fiber acoustic wave sensing specifically refers to the part of the automatic detection method for underground faults based on distributed optical fiber acoustic wave sensing, which will not be repeated here.

Figure 8 schematically shows a block diagram of an electronic device suitable for implementing the above-described method for automatic detection of underground faults based on distributed optical fiber acoustic wave sensing according to an embodiment of the present disclosure. The electronic device shown in Figure 8 is only an example and should not bring any limitation to the functions and scope of use of the embodiment of the present disclosure.

As shown in Figure 8, the electronic device 800 according to the embodiment of the present disclosure includes a processor 801, which can perform various appropriate actions and processes according to the program stored in the read-only memory (ROM) 802 or the program loaded from the storage part 808 to the random access memory (RAM) 803. The processor 801 may include, for example, a general-purpose microprocessor (such as a CPU), an instruction set processor and/or a related chipset and/or a special-purpose microprocessor (for example, an application-specific integrated circuit (ASIC)), etc. The processor 801 may also include an onboard memory for caching purposes. The processor 801 may include a single processing unit or multiple processing units for performing different actions of the method flow according to the embodiment of the present disclosure.

In RAM 803, various programs and data required for the operation of electronic device 800 are stored. Processor 801, ROM 802 and RAM 803 are connected to each other via bus 804. Processor 801 performs various operations of the method flow according to the embodiment of the present disclosure by executing the program in ROM 802 and/or RAM 803. It should be noted that the program can also be stored in one or more memories other than ROM 802 and RAM 803. Processor 801 can also perform various operations of the method flow according to the embodiment of the present disclosure by executing the program stored in the one or more memories.

According to an embodiment of the present disclosure, the electronic device 800 may further include an input/output (I/O) interface 805, which is also connected to the bus 804. The system 800 may further include one or more of the following components connected to the I/O interface 805: an input section 806 including a keyboard, a mouse, etc.; an output section 807 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 808 including a hard disk, etc.; and a communication section 809 including a network interface card such as a LAN card, a modem, etc. The communication section 809 performs communication processing via a network such as the Internet. A drive 810 is also connected to the I/O interface 805 as needed. A removable medium 811, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 810 as needed, so that a computer program read therefrom is installed into the storage section 808 as needed.

According to an embodiment of the present disclosure, the method flow according to an embodiment of the present disclosure can be implemented as a computer software program. For example, an embodiment of the present disclosure includes a computer program product, which includes a computer program carried on a computer-readable storage medium, and the computer program contains a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from the network through the communication part 809, and/or installed from the removable medium 811. When the computer program is executed by the processor 801, the above-mentioned functions defined in the system of the embodiment of the present disclosure are executed. According to an embodiment of the present disclosure, the system, equipment, device, module, unit, etc. described above can be implemented by a computer program module.

The present disclosure also provides a computer-readable storage medium, which may be included in the device/apparatus/system described in the above embodiments; or may exist independently without being assembled into the device/apparatus/system. The above computer-readable storage medium carries one or more programs, and when the above one or more programs are executed, the method according to the embodiment of the present disclosure is implemented.

According to an embodiment of the present disclosure, the computer-readable storage medium may be a non-volatile computer-readable storage medium. For example, it may include, but is not limited to: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination thereof. In the present disclosure, a computer-readable storage medium may be any tangible medium containing or storing a program that may be used by or in combination with an instruction execution system, apparatus, or device.

For example, according to an embodiment of the present disclosure, the computer-readable storage medium may include the ROM 802 and/or the RAM 803 described above and/or one or more memories other than the ROM 802 and the RAM 803 .

The flowcharts and block diagrams in the accompanying drawings illustrate the possible architecture, functions and operations of the systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram may represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of the 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 may 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. It can be understood by those skilled in the art that the features recorded in the various embodiments and/or claims of the present disclosure can be combined and/or combined in a variety of ways, even if such a combination or combination is not explicitly recorded in the present disclosure. In particular, without departing from the spirit and teaching of the present disclosure, the features described in the various embodiments and/or claims of the present disclosure may be combined and/or combined in a variety of ways. All of these combinations and/or combinations fall within the scope of the present disclosure.

The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. The scope of the present disclosure is defined by the attached claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims (9)

1. A method for automatic detection of underground faults based on distributed optical fiber acoustic wave sensing, comprising: Acquiring seismic data recorded by a fiber optic seismograph, wherein the optical fiber of the fiber optic seismograph is distributed in an area where the underground fault is to be identified; Performing frequency wavenumber filtering on the seismic data to obtain scattered wave data after filtering out direct wave signal data and noise signal data; Determine the scattering intensity of all scattered waves in the waveform diagram of the scattered wave data by using a tracing pane, wherein the waveform diagram is recorded according to time and the position of the optical fiber, and the tracing pane uses the time and position in the waveform diagram as a scale to trace the scattered waves emitted by the underground fault; Integrating the scattering intensity in the time domain to obtain an integration result; and Determine the location of the underground fault according to the integration result and the optical fiber distribution of the optical fiber seismograph; The method of determining the scattering intensity of all scattered waves in the waveform diagram of the scattered wave data by using the source tracing pane includes: Determine all scattering sources in the waveform diagram of the scattered wave data using the source tracing pane; For each of the scatter sources: The other scattering sources on both sides of the scattering source are superimposed at a preset apparent velocity to obtain two column vectors representing the unidirectional propagation of the scattering wave field; The scattering intensity of the scattered wave is determined based on the dot product result of the two column vectors. 2. The method according to claim 1, before performing frequency wavenumber filtering on the seismic data to obtain scattered wave data from which direct wave signal data and noise signal data are filtered out, further comprises: Determining shock wave noise data in the seismic data, wherein the shock wave noise data is noise data caused by non-seismic waves; The shock wave noise data in the seismic data is modified to eliminate the influence of the shock wave noise data. 3. The method of claim 2, wherein determining shock noise data in the seismic data comprises: Selecting a predetermined number of reference data according to the positions of the respective sampling points of the seismic data; When the ratio of the strain rate amplitude of the seismic data at the sampling point to the strain rate amplitude of the reference data is greater than a preset threshold, the seismic data at the sampling point is determined to be shock wave noise data. 4. The method according to claim 3, wherein the step of modifying the shock wave noise data in the seismic data to eliminate the influence of the shock wave noise data comprises: Based on seismic data acquired from sampling points adjacent to the shock wave noise data, the shock wave noise data in the seismic data is modified to eliminate the influence of the shock wave noise data. 5. The method according to claim 1, wherein the step of performing frequency wavenumber filtering on the seismic data to obtain scattered wave data from which direct wave signal data and noise signal data are filtered out comprises: Converting the seismic data in the range-time domain into the frequency-wavenumber domain by Fourier transform; Using preset parameters to filter out direct wave signals and noise signals in the seismic data to obtain scattered wave data in the frequency wavenumber domain; The scattered wave data in the frequency wave number domain is inversely transformed to obtain the scattered wave data in the distance time domain. 6. The method according to claim 5, before converting the seismic data in the range-time domain into the frequency-wavenumber domain by Fourier transform, further comprising: Normalizing the seismic data to obtain normalized seismic data; The edge waveforms of the waveform diagram of the normalized seismic data are subjected to waveform pinching to reduce false signals caused by the edge waveforms. 7. An automatic detection device for underground faults based on distributed optical fiber acoustic wave sensing, comprising: An acquisition module, used for acquiring seismic data recorded by a fiber optic seismograph, wherein the optical fiber of the fiber optic seismograph is distributed in an area where the underground fault is to be identified; A first obtaining module is used to perform frequency wavenumber filtering on the seismic data to obtain scattered wave data after filtering out direct wave signal data and noise signal data; A first determination module, configured to determine the scattering intensity of all scattered waves in the waveform diagram of the scattered wave data by using a tracing pane, wherein the waveform diagram is recorded according to time and the position of the optical fiber, and the tracing pane uses the time and position in the waveform diagram as a scale to trace the scattered waves emitted by the underground fault; The second obtaining module is used to integrate the scattering intensity in the time domain to obtain an integration result; A second determination module is used to determine the location of the underground fault according to the integration result and the optical fiber distribution of the optical fiber seismograph; Wherein, the first determining module includes: A third determining unit, configured to determine all scattering sources in the waveform graph of the scattered wave data by using the source tracing pane; For each of the scatter sources: The other scattering sources on both sides of the scattering source are superimposed at a preset apparent velocity to obtain two column vectors representing the unidirectional propagation of the scattering wave field; The scattering intensity of the scattered wave is determined based on the dot product result of the two column vectors. 8. An electronic device comprising: one or more processors; a memory for storing one or more programs, When the one or more programs are executed by the one or more processors, the one or more processors implement the method according to any one of claims 1 to 6. 9. A computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enables the processor to implement the method according to any one of claims 1 to 6.