Earthquake frequency dispersion spectrum extraction method and system, terminal and storage medium

Abstract

The invention relates to the technical field of seismic exploration imaging, and discloses a seismic frequency dispersion spectrum extraction method and system, a terminal and a storage medium, and the method comprises the steps: mapping a target seismic region into a target coordinate system, and carrying out the segmentation, thereby obtaining triangular subunits; calculating a frequency-Bessel transformation result of the triangular subunits, and calculating a global frequency dispersion spectrum of the target seismic region based on the frequency-Bessel transformation result; converting the time domain signal of the global frequency dispersion spectrum into a wavenumber domain signal for wavenumber conversion according to different modes, then converting the wavenumber domain signal into a time domain signal for phase velocity filtering processing to obtain high-order frequency dispersion curves, and performing superposition processing on all the high-order frequency dispersion curves to obtain a target frequency dispersion spectrum. According to the invention, the area division process is introduced into the frequency-Bessel framework, the azimuth dependence of the radiation pattern of the seismic source is offset from the theoretical level, and the problem of frequency dispersion measurement deviation under the coverage of a wide azimuth array is solved.

Description

Technical Field

[0001] This invention relates to the field of seismic exploration imaging technology, and in particular to a seismic dispersion spectrum extraction method, system, terminal, and computer-readable storage medium. Background Technology

[0002] Traditional dispersion curve extraction methods (such as the dual-stage method and the process function method) generally suffer from low resolution of higher-order modes. Higher-order dispersion information is easily masked by the energy of the fundamental mode or interfered with by noise, resulting in insufficient constraints and multiple solutions in the inversion of underground structures. The proposed frequency-Bessel (FJ) transform method greatly improves this situation. This method achieves efficient extraction of dispersion spectrum through cylindrical harmonic function expansion, significantly improving the identification efficiency and extraction accuracy of higher-order surface waves.

[0003] However, earthquake sources are complex and are anisotropic sources with differences in all directions. Therefore, this characteristic must be fully considered in the dispersion spectrum calculation process. Furthermore, the conditions for extracting dispersion spectrum from natural earthquake event records are quite stringent. It requires sources with sufficiently large magnitudes, and the propagation path from the source to the array should avoid passing through natural low-pass filters such as the ocean to ensure that as much high-order dispersion information as possible can be received.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] The main objective of this invention is to provide a method, system, terminal, and computer-readable storage medium for seismic dispersion spectrum extraction, aiming to solve the problem that the frequency-Bessel method in the prior art requires very high conditions when analyzing seismic sources, resulting in large deviations in the high-order dispersion information analyzed under ordinary seismic source environments.

[0006] To achieve the above objectives, the present invention provides a method for seismic dispersion spectrum extraction, the method comprising the following steps: The target seismic region is obtained, mapped to the target coordinate system, and then divided into multiple triangular sub-units in the target coordinate system. Using multiple constructed expansion coefficients, the frequency-Bessel transform result of each triangular sub-unit is calculated. Based on each frequency-Bessel transform result and the corresponding triangular sub-unit, the global dispersion spectrum of the target seismic region is calculated. For different modes, the time-domain signal of the global dispersion spectrum is converted into a wavenumber domain signal, and the wavenumber domain signal is converted into a wavenumber to obtain the three-component data for each mode. Each of the three-component data is converted into a time-domain signal and then subjected to phase velocity filtering to obtain the corresponding higher-order dispersion curve. All the higher-order dispersion curves are then superimposed to obtain the target dispersion spectrum of the target seismic region.

[0007] Optionally, the seismic dispersion spectrum extraction method, wherein obtaining the target seismic region, mapping the target seismic region to a target coordinate system, and segmenting the target seismic region in the target coordinate system to obtain multiple triangular sub-units, specifically includes: Obtain the target earthquake region and construct a target coordinate system using the epicenter of the target earthquake region as the origin; The target seismic region is mapped to the target coordinate system, and multiple arrays in the target seismic region are defined as nodes; Connect all the neighboring nodes of the aforementioned nodes to divide the target seismic region into multiple triangular sub-units.

[0008] Optionally, the seismic dispersion spectrum extraction method further includes, prior to utilizing the multiple pre-constructed expansion coefficients: The seismic displacement field of the target seismic region is expanded using the column harmonic function vector to obtain the first expansion coefficient of the target seismic region: ; Second expansion factor: ; Third expansion factor: ; Fourth expansion factor: ; Fifth expansion coefficient: ; Sixth expansion factor: ; Seventh expansion factor: ; Eighth expansion factor: ; in, Indicates the first expansion factor. Indicates the second expansion coefficient. Indicates the third expansion factor. This represents the fourth expansion coefficient. This represents the fifth expansion coefficient. This represents the sixth expansion coefficient. This represents the seventh expansion coefficient. This represents the eighth expansion coefficient. k Indicates wave number, z Indicates depth, Represents the radial three-component seismic record. r Indicates the distance from the epicenter. Indicates azimuth. This represents the first-order Hankel function of the first class. This represents the three-component seismic record in the vertical direction. This represents the 0th order Hankel function of the first kind. This represents the stiffness coefficient with respect to verticality. Represents the three-component seismic record along the tangential direction. This represents the second-order Hankel function of the first kind. This represents the stiffness coefficient with respect to the horizontal plane. This represents the third-order Hankel function of the first class.

[0009] Optionally, in the seismic dispersion spectrum extraction method, the frequency-Bessel transform results include: Love wave dispersion spectrum, Rayleigh wave dispersion spectrum, and leaked guided wave dispersion spectrum; The calculation of the frequency-Bessel transform result for each triangular subunit using the constructed multiple extension coefficients specifically includes: For each of the triangular sub-units, the Love wave dispersion spectrum is constructed using the third expansion coefficient and the sixth expansion coefficient, wherein the Love wave dispersion spectrum is used to characterize the dispersion information of the target seismic region in the tangential displacement component; The Rayleigh wave dispersion spectrum is constructed using the first expansion coefficient, the second expansion coefficient, the fourth expansion coefficient, the fifth expansion coefficient, the seventh expansion coefficient, and the eighth expansion coefficient, wherein the Rayleigh wave dispersion spectrum is used to characterize the radial and vertical displacement components of the target seismic area; The leakage guided wave dispersion spectrum is constructed using the first expansion coefficient, the second expansion coefficient, the fourth expansion coefficient, the fifth expansion coefficient, the seventh expansion coefficient, and the eighth expansion coefficient, wherein the leakage guided wave dispersion spectrum is used to characterize the P-wave velocity structure of the target seismic region.

[0010] Optionally, the seismic dispersion spectrum extraction method, wherein calculating the global dispersion spectrum of the target seismic region based on each frequency-Bessel transform result and the corresponding triangular sub-unit specifically includes: Calculate the triangle area of ​​each of the triangular sub-units, and multiply the Rayleigh wave dispersion spectrum of each of the triangular sub-units by the corresponding triangle area to obtain the unit contribution value of each of the triangular sub-units; The contribution values ​​of each unit are summed to obtain the global dispersion spectrum of the target seismic region.

[0011] Optionally, the seismic dispersion spectrum extraction method, wherein the step of converting the time-domain signal of the global dispersion spectrum into a wavenumber-domain signal for different modes, and performing wavenumber conversion on the wavenumber-domain signal to obtain three-component data for each mode, specifically includes: The frequency-phase velocity relationship of each fundamental order dispersion energy is determined based on the global dispersion spectrum. For different modes, multiple non-target fundamental dispersion energies in the current mode are removed to obtain the current type of target fundamental dispersion energy, and the time domain signal of the global dispersion spectrum is converted into a wavenumber domain signal. Based on the frequency-phase velocity relationship corresponding to the current type, the target fundamental dispersion energy in the wavenumber domain signal is subjected to wavenumber transformation to obtain three-component data, and finally, three-component data for each mode are obtained: ; in, u Represents three-component data. f Indicates frequency, Indicates the first j One pattern, Indicates azimuth. z Indicates depth, e The base of the natural logarithm. i Represents the imaginary unit. c It represents the speed of light.

[0012] Optionally, the seismic dispersion spectrum extraction method, wherein converting each of the three-component data into a time-domain signal and performing phase velocity filtering to obtain the corresponding higher-order dispersion curve, and then superimposing all the higher-order dispersion curves to obtain the target dispersion spectrum of the target seismic region, specifically includes: The target fundamental dispersion energy of each of the three components of data is converted into a time domain signal to obtain the Green's function that corrects each mode to time 0. In each Green's function, the waveform of the target fundamental dispersion energy in each mode is captured using a time window to obtain the higher-order dispersion curve; The higher-order dispersion curves under each of the aforementioned modes are subjected to dispersion spectrum superposition processing to obtain the target dispersion spectrum of the target seismic region. The target dispersion spectrum includes the dispersion spectrum of the target seismic region under all said modes.

[0013] Furthermore, to achieve the above objectives, the present invention also provides a seismic dispersion spectrum extraction system, wherein the seismic dispersion spectrum extraction system comprises: A segmentation model is used to obtain a target seismic region, map the target seismic region onto a target coordinate system, and segment the target seismic region in the target coordinate system to obtain multiple triangular sub-units; The area integral model is used to calculate the frequency-Bessel transform result of each of the triangular sub-units using multiple pre-constructed expansion coefficients, and to calculate the global dispersion spectrum of the target seismic region based on each frequency-Bessel transform result and the corresponding triangular sub-unit. The mode separation model is used to convert the time-domain signal of the global dispersion spectrum into a wavenumber domain signal for different modes, and to perform wavenumber conversion on the wavenumber domain signal to obtain three-component data for each mode. The dispersion spectrum optimization model is used to convert each of the three-component data into a time-domain signal and then perform phase velocity filtering to obtain the corresponding higher-order dispersion curves. All the higher-order dispersion curves are then superimposed to obtain the target dispersion spectrum of the target seismic region.

[0014] Furthermore, to achieve the above objectives, the present invention also provides a terminal, wherein the terminal includes: a memory, a processor, and a seismic dispersion spectrum extraction program stored in the memory and executable on the processor, wherein when the seismic dispersion spectrum extraction program is executed by the processor, it implements the steps of the seismic dispersion spectrum extraction method as described above.

[0015] Furthermore, to achieve the above objectives, the present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a seismic dispersion spectrum extraction program, which, when executed by a processor, implements the steps of the seismic dispersion spectrum extraction method as described above.

[0016] In this invention, a target seismic region is acquired and mapped onto a target coordinate system. The target seismic region is then segmented within this coordinate system to obtain multiple triangular sub-units. Using pre-constructed expansion coefficients, the frequency-Bessel transform result of each triangular sub-unit is calculated. Based on each frequency-Bessel transform result and the corresponding triangular sub-unit, the global dispersion spectrum of the target seismic region is calculated. For different modes, the time-domain signal of the global dispersion spectrum is converted to a wavenumber domain signal. Wavenumber conversion is then performed on the wavenumber domain signal to obtain three-component data for each mode. Each of the three-component data is converted back to a time-domain signal and then subjected to phase velocity filtering to obtain the corresponding higher-order dispersion curves. All the higher-order dispersion curves are then superimposed to obtain the target dispersion spectrum of the target seismic region. This invention introduces a surface integration process into the frequency-Bessel framework, theoretically offsetting the azimuth dependence of the seismic source radiation pattern and solving the dispersion measurement bias problem under wide-azimuth array coverage. Attached Figure Description

[0017] Figure 1 This is a flowchart of a preferred embodiment of the seismic dispersion spectrum extraction method of the present invention; Figure 2 This is a schematic diagram of the area integral of a preferred embodiment of the seismic dispersion spectrum extraction method of the present invention; Figure 3 This is a schematic diagram of the dispersion spectrum of a preferred embodiment of the seismic dispersion spectrum extraction method of the present invention; Figure 4 This is a schematic flowchart of mode separation in a preferred embodiment of the seismic dispersion spectrum extraction method of the present invention; Figure 5 This is a structural diagram of a preferred embodiment of the seismic dispersion spectrum extraction system of the present invention; Figure 6 This is a structural diagram of a preferred embodiment of the terminal of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0019] The seismic dispersion spectrum extraction method described in the preferred embodiment of the present invention, such as... Figure 1 As shown, the seismic dispersion spectrum extraction method includes the following steps: Step S10: Obtain the target seismic region, map the target seismic region to the target coordinate system, and divide the target seismic region in the target coordinate system to obtain multiple triangular sub-units.

[0020] Among them, the existing FJ technology (i.e., frequency-Bessel) has not solved the problem of dispersion measurement deviation under wide azimuth array coverage, and only alleviates it by limiting the azimuth range of the array; therefore, this invention discloses the introduction of the concept of area integral in the frequency-Bessel framework to theoretically offset the azimuth dependence of earthquake source radiation patterns.

[0021] Specifically, the target earthquake region is obtained, and a target coordinate system is constructed with the epicenter of the target earthquake region as the origin. The horizontal axis of the target coordinate system is due east, and the vertical axis is due north. The target seismic region is mapped to the target coordinate system, and multiple arrays in the target seismic region are defined as nodes; Connect all the neighboring nodes of the aforementioned nodes to divide the target seismic region into multiple triangular sub-units.

[0022] In the embodiments disclosed in this invention, a semi-analytical expression for the full-mode dispersion spectrum is constructed by introducing the concept of area integral within the frequency-Bessel framework, and a discretized integration scheme is adopted to adapt to the actual array deployment. In practical applications, area integral needs to be implemented using a discrete method, but in most cases, arrays are irregularly distributed. For irregular array distributions, Delaunay triangulation is used to divide the seismic array into several triangular sub-units, and the area integral is achieved by superimposing the contributions of the sub-units.

[0023] Among them, such as Figure 2 As shown in (a), this invention uses a synthetic example of the seismic array area integral corresponding to a magnitude 5.7 earthquake record occurring in a certain region to verify the practical application effect of the area integral in this method. The asterisk represents the location of the seismic source, and the target coordinate system is constructed with this as the origin of the coordinate system. Then, the east direction is used as the horizontal axis and the north direction is used as the vertical axis; as shown in (a), the method uses the seismic source location as the origin of the coordinate system to construct the target coordinate system. Figure 2 As shown in (b), this is the parameter configuration for the one-dimensional structural model corresponding to the target seismic area. The vertical axis represents depth, and the horizontal axis represents the values ​​of different parameters. Represents density, Represents the speed of transverse wave propagation in the structure. This represents the speed at which longitudinal waves propagate within the structure.

[0024] During the mapping process, the coordinates of each array are transformed into cylindrical coordinates with the seismic source as the center. This allows the corresponding radial and azimuth angles to be determined. Then, based on the array positions, Delaunay triangulation is performed to generate triangular sub-units. The area of ​​each triangular sub-unit is then calculated for the next step of area integration.

[0025] It should be noted that the Delaunay triangulation disclosed in this invention is not the only method. Other graph partitioning methods, such as rectangular mesh partitioning or adaptive mesh partitioning, can also be used. Its main purpose is to decompose the target seismic region into sub-elements, and then perform local integration and global accumulation to achieve the fusion of the FJ frame and the area integral, thereby reducing the azimuth dependence of the seismic source radiation pattern. Furthermore, the dimension of the area integral is not fixed to a two-dimensional area integral, but can be extended to a three-dimensional integral, thereby adapting to three-dimensional non-homogeneous medium models.

[0026] Furthermore, if the array density difference in the target seismic area is too large, station density interpolation (such as Kriging interpolation) can be added before subdivision to make the irregular array approximately regular, and then the area integration process can be applied to offset the azimuth dependence. For low-frequency areas, area integration can be used to offset the azimuth deviation, while for high-frequency areas, FK transform (frequency-wavenumber transform) can be used to improve efficiency.

[0027] Step S20: Using the constructed multiple expansion coefficients, calculate the frequency-Bessel transform result of each of the triangular sub-units, and calculate the global dispersion spectrum of the target seismic region based on each frequency-Bessel transform result and the corresponding triangular sub-unit.

[0028] In the embodiments disclosed in this invention, based on the semi-analytical solution of the three-dimensional multilayer medium wave equation, the seismic displacement field is expanded using the cylindrical harmonic function vector basis, and eight expansion coefficients are derived to construct multiple full-mode dispersion spectra. Based on the area of ​​each triangular sub-unit, the contribution value of each triangular sub-unit is calculated to calculate the dispersion spectrum of the entire target seismic region. Furthermore, Delaunay triangulation is used to achieve discretized area integration under irregular array distribution, which is compatible with the non-uniform deployment characteristics of actual seismic arrays and can effectively solve the problem of poor adaptability caused by the reliance on regular arrays in existing technologies.

[0029] Specifically, the seismic displacement field of the target seismic region is expanded using the column harmonic function vector to obtain the first expansion coefficient of the target seismic region: ; Second expansion factor: ; Third expansion factor: ; Fourth expansion factor: ; Fifth expansion coefficient: ; Sixth expansion factor: ; Seventh expansion factor: ; Eighth expansion factor: ; in, Indicates the first expansion factor. Indicates the second expansion coefficient. Indicates the third expansion factor. This represents the fourth expansion coefficient. This represents the fifth expansion coefficient. This represents the sixth expansion coefficient. This represents the seventh expansion coefficient. This represents the eighth expansion coefficient. k Indicates wave number, z Indicates depth, Represents the radial three-component seismic record. r Indicates the distance from the epicenter. Indicates azimuth. This represents the first-order Hankel function of the first class. This represents the three-component seismic record in the vertical direction. This represents the 0th order Hankel function of the first kind. This represents the stiffness coefficient with respect to verticality. Represents the three-component seismic record along the tangential direction. This represents the second-order Hankel function of the first kind. This represents the stiffness coefficient with respect to the horizontal plane. This represents the third-order Hankel function of the first class.

[0030] Among them, such as Figure 3 As shown in (a), this represents the extraction result of the dispersion spectrum that can be extracted from the third expansion coefficient; as... Figure 3 As shown in (b), this represents the extraction result of the dispersion spectrum that can be extracted from the sixth expansion coefficient; as... Figure 3 As shown in (c), this represents the extraction result of the dispersion spectrum that can be extracted from the first expansion coefficient; as... Figure 3 As shown in (d), this represents the extraction result of the dispersion spectrum that can be extracted from the fourth expansion coefficient; as... Figure 3 As shown in (e), this represents the extraction result of the dispersion spectrum that can be extracted from the seventh expansion coefficient; as... Figure 3 As shown in (f), this represents the extraction result of the dispersion spectrum that can be extracted from the second expansion coefficient; as... Figure 3 As shown in (g), this represents the extraction result of the dispersion spectrum that can be extracted from the fifth expansion coefficient; as... Figure 3 As shown in (h), this represents the extraction result of the dispersion spectrum that can be extracted from the eighth expansion coefficient.

[0031] In specific application scenarios (such as using data with a high signal-to-noise ratio), the calculation of the spread coefficient can be omitted, and the integration logic before the surface integral can be retained. The integral function can be replaced by the modified Bessel function or other orthogonal functions to suppress different types of wave field aliasing (such as body wave and surface wave aliasing).

[0032] Furthermore, the frequency-Bessel transform results include: Love wave dispersion spectrum (Love wave dispersion spectrum, which inverts the transverse wave velocity model by analyzing the change of wave velocity with frequency), Rayleigh wave dispersion spectrum (Rayleigh wave dispersion spectrum, which is an interference wave of the vertical components of longitudinal and transverse waves, with high energy and low frequency, suitable for shallow detection) and leakage guide wave dispersion spectrum.

[0033] Among them, the semi-analytical expressions of these 8 expansion coefficients can realize the simultaneous extraction of Love wave dispersion spectrum, Rayleigh wave dispersion spectrum and leakage guided wave dispersion spectrum, which can overcome the limitation of the existing FJ method that can only extract a single wave type (such as Rayleigh wave) or a single component (such as vertical component).

[0034] Furthermore, after constructing the dispersion spectrum, higher-order modes can be separated from noise through wavelet transform denoising, matched pursuit filtering, or adaptive threshold filtering.

[0035] For each of the triangular sub-units, the Love wave dispersion spectrum is constructed using the third expansion coefficient and the sixth expansion coefficient, wherein the Love wave dispersion spectrum is used to characterize the dispersion information of the target seismic region in the tangential displacement component; The Rayleigh wave dispersion spectrum is constructed using the first expansion coefficient, the second expansion coefficient, the fourth expansion coefficient, the fifth expansion coefficient, the seventh expansion coefficient, and the eighth expansion coefficient, wherein the Rayleigh wave dispersion spectrum is used to characterize the radial and vertical displacement components of the target seismic area; The leakage guided wave dispersion spectrum is constructed using the first expansion coefficient, the second expansion coefficient, the fourth expansion coefficient, the fifth expansion coefficient, the seventh expansion coefficient, and the eighth expansion coefficient, wherein the leakage guided wave dispersion spectrum is used to characterize the P-wave velocity structure of the target seismic region.

[0036] Further, the area of ​​the triangle in each of the triangular sub-units is calculated, and the Rayleigh wave dispersion spectrum of each of the triangular sub-units is multiplied by the corresponding area of ​​the triangle to obtain the unit contribution value of each of the triangular sub-units; The contribution values ​​of each unit are summed to obtain the global dispersion spectrum of the target seismic region.

[0037] For each triangular sub-unit, the data of each array (where each triangular sub-unit consists of three arrays) are used to calculate the dispersion results within each unit according to the above formula (i.e., the Love wave dispersion spectrum, Rayleigh wave dispersion spectrum, and leakage guided wave dispersion spectrum). Then, the sub-unit contribution is obtained by multiplying the Rayleigh wave dispersion spectrum by the unit area. Finally, the contributions of all sub-units are accumulated to obtain the global dispersion spectrum, thus completing the discretized area integral calculation.

[0038] Furthermore, for the differences in dispersion spectrum in different directions, in the embodiments disclosed in this invention, it is possible to extract high-quality dispersion spectrum at small angles in non-ultra-low frequency bands. This feature can be used to characterize the differences in the orientation of regional structures.

[0039] Step S30: For different modes, convert the time domain signal of the global dispersion spectrum into a wavenumber domain signal, perform wavenumber conversion on the wavenumber domain signal, and obtain the three-component data for each mode.

[0040] In the application of measured data, to extract the weaker higher-order dispersion and P-guided wave (formed by the superposition of shallow reflected and refracted waves, whose dispersion characteristics can reflect the physical properties of the underground medium), this invention introduces signal enhancement techniques, such as... Figure 4 As shown in (a), the dispersion compensation method is used to enhance the mode separation effect: first, the fundamental energy distribution of the original dispersion spectrum is picked up, which is the relationship between the frequency and phase velocity of the fundamental dispersion energy. Based on this relationship, the contribution of the fundamental dispersion energy in the dispersion spectrum is removed, and what remains is the contribution of other modes in the dispersion spectrum.

[0041] Specifically, the frequency-phase velocity relationship of each fundamental order dispersion energy is determined based on the global dispersion spectrum; For different modes, multiple non-target fundamental dispersion energies in the current mode are removed to obtain the current type of target fundamental dispersion energy, and the time domain signal of the global dispersion spectrum is converted into a wavenumber domain signal. Based on the frequency-phase velocity relationship corresponding to the current type, the target fundamental dispersion energy in the wavenumber domain signal is subjected to wavenumber transformation to obtain three-component data, and finally, three-component data for each mode are obtained: ; in, u Represents three-component data. f Indicates frequency, Indicates the first j One pattern, Indicates azimuth. z Indicates depth, eThe base of the natural logarithm. i Represents the imaginary unit. c It represents the speed of light.

[0042] In the embodiments disclosed in this invention, the time-domain data is processed through positive and negative wavenumber transformation. First, the patterns to be removed are picked from the original dispersion spectrum to obtain the frequency-phase velocity relationship. The seismic data in the frequency domain is then subjected to wavenumber transformation based on this relationship to obtain the corresponding three-component data (where f and c are the relationship between the picked patterns). Based on the joint scheme of pattern separation, this invention can also combine dispersion compensation with machine learning classification to replace the traditional phase velocity domain windowing and improve the accuracy of high-order pattern recognition.

[0043] Furthermore, the three-component seismic record is extended to a single component (such as only the radial component) or a combination of multiple components (radial + tangential), and dispersion extraction is achieved by adjusting the weight distribution of the extension coefficient.

[0044] Step S40: Convert each of the three-component data into a time-domain signal and perform phase velocity filtering to obtain the corresponding higher-order dispersion curve. Then, superimpose all the higher-order dispersion curves to obtain the target dispersion spectrum of the target seismic region.

[0045] Specifically, the target fundamental dispersion energy of each of the three-component data is converted into a time-domain signal to obtain the Green's function at time 0 for each of the modes; In each Green's function, the waveform of the target fundamental dispersion energy in each mode is captured using a time window to obtain the higher-order dispersion curve; The higher-order dispersion curves under each of the aforementioned modes are subjected to dispersion spectrum superposition processing to obtain the target dispersion spectrum of the target seismic region. The target dispersion spectrum includes the dispersion spectrum of the target seismic region under all said modes.

[0046] In step S30, the target fundamental dispersion energy of the three-component data is converted into a time domain signal. Each mode obtained at this time should be the Green's function that corrects the mode to time 0. At this time, the waveform of the mode is truncated using a time window, and the remaining waveform is retained, which completes the phase velocity domain filtering. The remaining part is the energy of the higher-order dispersion curve, which can significantly improve the visibility of the higher-order dispersion curve.

[0047] Finally, as Figure 4 As shown in (b), by combining the dispersion spectra of each completed mode and superimposing the dispersion spectra, a clear dispersion spectrum of each mode is obtained immediately. This invention combines dispersion compensation and multi-expansion coefficient fusion strategy to enhance the recognizability of high-order dispersion curves and leakage guided waves, and solves the problem of difficult separation of weak energy modes.

[0048] This invention introduces an area integral process into the frequency-Bessel framework, which theoretically counteracts the azimuth dependence of earthquake source radiation patterns and solves the problem of dispersion measurement bias under wide azimuth array coverage.

[0049] Furthermore, such as Figure 5 As shown, based on the above-described seismic dispersion spectrum extraction method, the present invention also provides a seismic dispersion spectrum extraction system, wherein the seismic dispersion spectrum extraction system includes: Segmentation model 51 is used to obtain the target seismic region, map the target seismic region to the target coordinate system, and segment the target seismic region in the target coordinate system to obtain multiple triangular sub-units; The area integral model 52 is used to calculate the frequency-Bessel transform result of each of the triangular sub-units using multiple constructed expansion coefficients, and to calculate the global dispersion spectrum of the target seismic region based on each of the frequency-Bessel transform results and the corresponding triangular sub-units. The mode separation model 53 is used to convert the time domain signal of the global dispersion spectrum into a wavenumber domain signal for different modes, and to perform wavenumber conversion on the wavenumber domain signal to obtain three-component data for each mode. The dispersion spectrum optimization model 54 is used to convert each of the three component data into a time domain signal and then perform phase velocity filtering to obtain the corresponding higher-order dispersion curves. All the higher-order dispersion curves are then superimposed to obtain the target dispersion spectrum of the target seismic area.

[0050] Furthermore, such as Figure 6 As shown, based on the above-mentioned seismic dispersion spectrum extraction method and system, the present invention also provides a terminal, which includes a processor 10, a memory 20 and a display 30. Figure 6 Only some of the terminal components are shown; however, it should be understood that it is not required to implement all of the components shown, and more or fewer components may be implemented instead.

[0051] In some embodiments, the memory 20 may be an internal storage unit of the terminal, such as a hard disk or memory. In other embodiments, the memory 20 may be an external storage device of the terminal, such as a plug-in hard disk, smart media card (SMC), secure digital card (SD), flash card, etc. Further, the memory 20 may include both internal and external storage devices. The memory 20 is used to store application software and various types of data installed on the terminal, such as the program code installed on the terminal. The memory 20 can also be used to temporarily store data that has been output or will be output. In one embodiment, the memory 20 stores a seismic dispersion spectrum extraction program 40, which can be executed by the processor 10 to implement the seismic dispersion spectrum extraction method of this application.

[0052] In some embodiments, the processor 10 may be a central processing unit (CPU), a microprocessor, or other data processing chip, used to run program code stored in the memory 20 or process data, such as executing the seismic dispersion spectrum extraction method.

[0053] In some embodiments, the display 30 may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, or an OLED (Organic Light-Emitting Diode) touchscreen. The display 30 is used to display information on the terminal and to display a visual user interface. The components of the terminal communicate with each other via a system bus.

[0054] In one embodiment, when the processor 10 executes the seismic dispersion spectrum extraction program 40 in the memory 20, the following steps are performed: The target seismic region is obtained, mapped to the target coordinate system, and then divided into multiple triangular sub-units in the target coordinate system. Using multiple constructed expansion coefficients, the frequency-Bessel transform result of each triangular sub-unit is calculated. Based on each frequency-Bessel transform result and the corresponding triangular sub-unit, the global dispersion spectrum of the target seismic region is calculated. For different modes, the time-domain signal of the global dispersion spectrum is converted into a wavenumber domain signal, and the wavenumber domain signal is converted into a wavenumber to obtain the three-component data for each mode. Each of the three-component data is converted into a time-domain signal and then subjected to phase velocity filtering to obtain the corresponding higher-order dispersion curve. All the higher-order dispersion curves are then superimposed to obtain the target dispersion spectrum of the target seismic region.

[0055] Specifically, the step of acquiring the target seismic region, mapping the target seismic region to a target coordinate system, and segmenting the target seismic region in the target coordinate system to obtain multiple triangular sub-units includes: Obtain the target earthquake region and construct a target coordinate system using the epicenter of the target earthquake region as the origin; The target seismic region is mapped to the target coordinate system, and multiple arrays in the target seismic region are defined as nodes; Connect all the neighboring nodes of the aforementioned nodes to divide the target seismic region into multiple triangular sub-units.

[0056] The use of multiple pre-constructed expansion coefficients, as previously mentioned, also includes: The seismic displacement field of the target seismic region is expanded using the column harmonic function vector to obtain the first expansion coefficient of the target seismic region: ; Second expansion factor: ; Third expansion factor: ; Fourth expansion factor: ; Fifth expansion coefficient: ; Sixth expansion factor: ; Seventh expansion factor: ; Eighth expansion factor: ; in, Indicates the first expansion factor. Indicates the second expansion coefficient. Indicates the third expansion factor. This represents the fourth expansion coefficient. This represents the fifth expansion coefficient. This represents the sixth expansion coefficient. This represents the seventh expansion coefficient. This represents the eighth expansion coefficient. k Indicates wave number,z Indicates depth, Represents the radial three-component seismic record. r Indicates the distance from the epicenter. Indicates azimuth. This represents the first-order Hankel function of the first class. This represents the three-component seismic record in the vertical direction. This represents the 0th order Hankel function of the first kind. This represents the stiffness coefficient with respect to verticality. Represents the three-component seismic record along the tangential direction. This represents the second-order Hankel function of the first kind. This represents the stiffness coefficient with respect to the horizontal plane. This represents the third-order Hankel function of the first class.

[0057] The frequency-Bessel transform results include: Love wave dispersion spectrum, Rayleigh wave dispersion spectrum and leaked guided wave dispersion spectrum; The calculation of the frequency-Bessel transform result for each triangular subunit using the constructed multiple extension coefficients specifically includes: For each of the triangular sub-units, the Love wave dispersion spectrum is constructed using the third expansion coefficient and the sixth expansion coefficient, wherein the Love wave dispersion spectrum is used to characterize the dispersion information of the target seismic region in the tangential displacement component; The Rayleigh wave dispersion spectrum is constructed using the first expansion coefficient, the second expansion coefficient, the fourth expansion coefficient, the fifth expansion coefficient, the seventh expansion coefficient, and the eighth expansion coefficient, wherein the Rayleigh wave dispersion spectrum is used to characterize the radial and vertical displacement components of the target seismic area; The leakage guided wave dispersion spectrum is constructed using the first expansion coefficient, the second expansion coefficient, the fourth expansion coefficient, the fifth expansion coefficient, the seventh expansion coefficient, and the eighth expansion coefficient, wherein the leakage guided wave dispersion spectrum is used to characterize the P-wave velocity structure of the target seismic region.

[0058] Specifically, calculating the global dispersion spectrum of the target seismic region based on each frequency-Bessel transform result and the corresponding triangular sub-unit includes: Calculate the triangle area of ​​each of the triangular sub-units, and multiply the Rayleigh wave dispersion spectrum of each of the triangular sub-units by the corresponding triangle area to obtain the unit contribution value of each of the triangular sub-units; The contribution values ​​of each unit are summed to obtain the global dispersion spectrum of the target seismic region.

[0059] Specifically, for different modes, the time-domain signal of the global dispersion spectrum is converted into a wavenumber-domain signal, and wavenumber conversion is performed on the wavenumber-domain signal to obtain three-component data for each mode, including: The frequency-phase velocity relationship of each fundamental order dispersion energy is determined based on the global dispersion spectrum. For different modes, multiple non-target fundamental dispersion energies in the current mode are removed to obtain the current type of target fundamental dispersion energy, and the time domain signal of the global dispersion spectrum is converted into a wavenumber domain signal. Based on the frequency-phase velocity relationship corresponding to the current type, the target fundamental dispersion energy in the wavenumber domain signal is subjected to wavenumber transformation to obtain three-component data, and finally, three-component data for each mode are obtained: ; in, u Represents three-component data. f Indicates frequency, Indicates the first j One pattern, Indicates azimuth. z Indicates depth, e The base of the natural logarithm. i Represents the imaginary unit. c It represents the speed of light.

[0060] Specifically, the process of converting each of the three-component data into a time-domain signal and then performing phase velocity filtering to obtain the corresponding higher-order dispersion curve, followed by superimposing all the higher-order dispersion curves to obtain the target dispersion spectrum of the target seismic region, includes: The target fundamental dispersion energy of each of the three components of data is converted into a time domain signal to obtain the Green's function that corrects each mode to time 0. In each Green's function, the waveform of the target fundamental dispersion energy in each mode is captured using a time window to obtain the higher-order dispersion curve; The higher-order dispersion curves under each of the aforementioned modes are subjected to dispersion spectrum superposition processing to obtain the target dispersion spectrum of the target seismic region. The target dispersion spectrum includes the dispersion spectrum of the target seismic region under all said modes.

[0061] The present invention also provides a computer-readable storage medium, wherein the computer-readable storage medium stores a seismic dispersion spectrum extraction program, which, when executed by a processor, implements the steps of the seismic dispersion spectrum extraction method as described above.

[0062] In summary, this invention provides a method and related equipment for seismic dispersion spectrum extraction. The method includes: acquiring a target seismic region; mapping the target seismic region to a target coordinate system; segmenting the target seismic region in the target coordinate system to obtain multiple triangular sub-units; calculating the frequency-Bessel transform result of each triangular sub-unit using multiple pre-constructed expansion coefficients; calculating the global dispersion spectrum of the target seismic region based on each frequency-Bessel transform result and the corresponding triangular sub-unit; converting the time-domain signal of the global dispersion spectrum into a wavenumber domain signal for different modes; performing wavenumber conversion on the wavenumber domain signal to obtain three-component data for each mode; converting each of the three-component data into a time-domain signal and performing phase velocity filtering to obtain the corresponding higher-order dispersion curves; and superimposing all the higher-order dispersion curves to obtain the target dispersion spectrum of the target seismic region. This invention introduces an area integral process into the frequency-Bessel framework, theoretically offsetting the azimuth dependence of the seismic source radiation pattern and solving the problem of dispersion measurement bias under wide-azimuth array coverage.

[0063] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal that includes that element.

[0064] Of course, those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware (such as a processor, controller, etc.). The program can be stored in a computer-readable storage medium, and when executed, it can include the processes described in the above method embodiments. The computer-readable storage medium can be a memory, magnetic disk, optical disk, etc.

[0065] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for extracting seismic dispersion spectra, characterized in that, The seismic dispersion spectrum extraction method includes: The target seismic region is obtained, mapped to the target coordinate system, and then divided into multiple triangular sub-units in the target coordinate system. Using multiple constructed expansion coefficients, the frequency-Bessel transform result of each triangular sub-unit is calculated. Based on each frequency-Bessel transform result and the corresponding triangular sub-unit, the global dispersion spectrum of the target seismic region is calculated. For different modes, the time-domain signal of the global dispersion spectrum is converted into a wavenumber domain signal, and the wavenumber domain signal is converted into a wavenumber to obtain the three-component data for each mode. Each of the three-component data is converted into a time-domain signal and then subjected to phase velocity filtering to obtain the corresponding higher-order dispersion curve. All the higher-order dispersion curves are then superimposed to obtain the target dispersion spectrum of the target seismic region.

2. The seismic dispersion spectrum extraction method according to claim 1, characterized in that, The process of acquiring the target seismic region, mapping the target seismic region to a target coordinate system, and segmenting the target seismic region in the target coordinate system to obtain multiple triangular sub-units specifically includes: Obtain the target earthquake region and construct a target coordinate system using the epicenter of the target earthquake region as the origin; The target seismic region is mapped to the target coordinate system, and multiple arrays in the target seismic region are defined as nodes; Connect all the neighboring nodes of the aforementioned nodes to divide the target seismic region into multiple triangular sub-units.

3. The seismic dispersion spectrum extraction method according to claim 1, characterized in that, The use of multiple pre-constructed expansion coefficients also previously included: The seismic displacement field of the target seismic region is expanded using the column harmonic function vector to obtain the first expansion coefficient of the target seismic region: ； Second expansion factor: ； Third expansion factor: ； Fourth expansion factor: ； Fifth expansion coefficient: ； Sixth expansion factor: ； Seventh expansion factor: ； Eighth expansion factor: ； in, Indicates the first expansion factor. Indicates the second expansion coefficient. Indicates the third expansion factor. This represents the fourth expansion coefficient. This represents the fifth expansion coefficient. This represents the sixth expansion coefficient. This represents the seventh expansion coefficient. This represents the eighth expansion coefficient. k Indicates wave number, z Indicates depth, Represents the radial three-component seismic record. r Indicates the distance from the epicenter. Indicates azimuth. This represents the first-order Hankel function of the first class. This represents the three-component seismic record in the vertical direction. This represents the 0th order Hankel function of the first kind. This represents the stiffness coefficient with respect to verticality. Represents the three-component seismic record along the tangential direction. This represents the second-order Hankel function of the first kind. This represents the stiffness coefficient with respect to the horizontal plane. This represents the third-order Hankel function of the first class.

4. The seismic dispersion spectrum extraction method according to claim 3, characterized in that, The frequency-Bessel transform results include: Love wave dispersion spectrum, Rayleigh wave dispersion spectrum, and leaked guided wave dispersion spectrum; The calculation of the frequency-Bessel transform result for each triangular subunit using the constructed multiple extension coefficients specifically includes: For each of the triangular sub-units, the Love wave dispersion spectrum is constructed using the third expansion coefficient and the sixth expansion coefficient, wherein the Love wave dispersion spectrum is used to characterize the dispersion information of the target seismic region in the tangential displacement component; The Rayleigh wave dispersion spectrum is constructed using the first expansion coefficient, the second expansion coefficient, the fourth expansion coefficient, the fifth expansion coefficient, the seventh expansion coefficient, and the eighth expansion coefficient, wherein the Rayleigh wave dispersion spectrum is used to characterize the radial and vertical displacement components of the target seismic area; The leakage guided wave dispersion spectrum is constructed using the first expansion coefficient, the second expansion coefficient, the fourth expansion coefficient, the fifth expansion coefficient, the seventh expansion coefficient, and the eighth expansion coefficient, wherein the leakage guided wave dispersion spectrum is used to characterize the P-wave velocity structure of the target seismic region.

5. The seismic dispersion spectrum extraction method according to claim 4, characterized in that, The step of calculating the global dispersion spectrum of the target seismic region based on each frequency-Bessel transform result and the corresponding triangular sub-unit specifically includes: Calculate the triangle area of ​​each of the triangular sub-units, and multiply the Rayleigh wave dispersion spectrum of each of the triangular sub-units by the corresponding triangle area to obtain the unit contribution value of each of the triangular sub-units; The contribution values ​​of each unit are summed to obtain the global dispersion spectrum of the target seismic region.

6. The seismic dispersion spectrum extraction method according to claim 1, characterized in that, For different modes, the time-domain signal of the global dispersion spectrum is converted into a wavenumber-domain signal, and wavenumber conversion is performed on the wavenumber-domain signal to obtain three-component data for each mode, specifically including: The frequency-phase velocity relationship of each fundamental order dispersion energy is determined based on the global dispersion spectrum. For different modes, multiple non-target fundamental dispersion energies in the current mode are removed to obtain the current type of target fundamental dispersion energy, and the time domain signal of the global dispersion spectrum is converted into a wavenumber domain signal. Based on the frequency-phase velocity relationship corresponding to the current type, the target fundamental dispersion energy in the wavenumber domain signal is subjected to wavenumber transformation to obtain three-component data, and finally, three-component data for each mode are obtained: ； in, u Represents three-component data. f Indicates frequency, Indicates the first j One pattern, Indicates azimuth. z Indicates depth, e The base of the natural logarithm. i Represents the imaginary unit. c It represents the speed of light.

7. The seismic dispersion spectrum extraction method according to claim 6, characterized in that, The process of converting each of the three-component data into a time-domain signal and then performing phase velocity filtering to obtain the corresponding higher-order dispersion curve, and then superimposing all the higher-order dispersion curves to obtain the target dispersion spectrum of the target seismic region, specifically includes: The target fundamental dispersion energy of each of the three components of data is converted into a time domain signal to obtain the Green's function that corrects each mode to time 0. In each Green's function, the waveform of the target fundamental dispersion energy in each mode is captured using a time window to obtain the higher-order dispersion curve; The higher-order dispersion curves under each of the aforementioned modes are subjected to dispersion spectrum superposition processing to obtain the target dispersion spectrum of the target seismic region. The target dispersion spectrum includes the dispersion spectrum of the target seismic region under all said modes.

8. A seismic dispersion spectrum extraction system, characterized in that, The seismic dispersion spectrum extraction system is used to implement the seismic dispersion spectrum extraction method as described in any one of claims 1-7, and the seismic dispersion spectrum extraction system comprises: A segmentation model is used to obtain a target seismic region, map the target seismic region onto a target coordinate system, and segment the target seismic region in the target coordinate system to obtain multiple triangular sub-units; The area integral model is used to calculate the frequency-Bessel transform result of each of the triangular sub-units using multiple pre-constructed expansion coefficients, and to calculate the global dispersion spectrum of the target seismic region based on each frequency-Bessel transform result and the corresponding triangular sub-unit. The mode separation model is used to convert the time-domain signal of the global dispersion spectrum into a wavenumber domain signal for different modes, and to perform wavenumber conversion on the wavenumber domain signal to obtain three-component data for each mode. The dispersion spectrum optimization model is used to convert each of the three-component data into a time-domain signal and then perform phase velocity filtering to obtain the corresponding higher-order dispersion curves. All the higher-order dispersion curves are then superimposed to obtain the target dispersion spectrum of the target seismic region.

9. A terminal, characterized in that, The terminal includes: a memory, a processor, and a seismic dispersion spectrum extraction program stored in the memory and executable on the processor. When the seismic dispersion spectrum extraction program is executed by the processor, it implements the steps of the seismic dispersion spectrum extraction method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a seismic dispersion spectrum extraction program, which, when executed by a processor, implements the steps of the seismic dispersion spectrum extraction method as described in any one of claims 1-7.

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