A method and system for earthquake source location based on consistent spectrum correlation imaging

Abstract

The present invention relates to a method and system for earthquake source positioning based on consistent spectrum correlation imaging. The method comprises: using a time window to intercept a time window intercepted earthquake record in original earthquake data; selecting a standard earthquake trace according to the time window intercepted earthquake record, and determining the first arrival wave signal in the standard earthquake trace as a standard first arrival wave field; obtaining a virtual source earthquake record according to the time window intercepted earthquake record and the standard first arrival wave field; obtaining a high signal-to-noise ratio earthquake record according to the virtual source earthquake record and the standard first arrival wave field; taking the position of each seismic station as the earthquake source point, and using an adaptive function solution method according to a grid model to obtain the first arrival wave travel time at each grid node corresponding to each earthquake source point; obtaining an imaging value at each grid node according to the first arrival wave travel time at each grid node corresponding to the high signal-to-noise ratio earthquake record and each earthquake source point, and determining the grid node corresponding to the imaging value with the largest absolute value as the earthquake source position. The present invention can improve the efficiency and accuracy of earthquake source positioning.

Description

Technical Field

[0001] The present invention relates to the technical field of natural earthquake positioning and microseismic monitoring on land or in the ocean, and in particular to a method and system for earthquake source positioning based on consistent spectrum correlation imaging. Background Art

[0002] The relative source location method based on waveform imaging can avoid the positioning error caused by the travel time information picking, and can eliminate the determination of the absolute time of source excitation, thereby greatly improving the efficiency and accuracy of source location, and can be widely used in the source location of natural earthquakes and microseismic monitoring. However, the relative source location method based on waveform imaging requires high signal-to-noise ratio first arrival wave records. In actual earthquake monitoring, due to the uncertainty of the source position, the absorption and attenuation of complex stratum media and the interference of noise, the actual recorded earthquake first arrival waves often exist in the form of weak signals in strong background noise, which seriously affects the quality of waveform imaging and reduces the accuracy of source location. Therefore, it is necessary to suppress the noise before waveform imaging to improve the signal-to-noise ratio of the first arrival wave field. However, the commonly used denoising methods have limited enhancement effects on low signal-to-noise ratio first arrival signals and cannot meet the needs of accurate source location based on low signal-to-noise ratio seismic records. At the same time, conventional ray tracing methods cannot achieve accurate calculation of the travel time of the first arrival wave under complex media conditions, further reducing the accuracy of source location. Therefore, on this basis, it is still necessary to continue to study and design a high-precision source locating method based on waveform imaging to address the deficiencies of the above-mentioned existing methods and technologies and improve the efficiency and accuracy of source locating. Summary of the invention

[0003] The purpose of the present invention is to provide a method and system for earthquake source positioning based on consistent spectrum correlation imaging, which can improve the efficiency and accuracy of earthquake source positioning.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A method for earthquake source location based on consistent spectrum correlation imaging, comprising:

[0006] Obtain the original seismic data of each seismic station in the seismic array;

[0007] For the original seismic data of any seismic station, a time window is used to intercept the time window intercepted seismic record corresponding to the seismic station in the original seismic data, and the time window intercepted seismic record includes all the first arrival wave signals in the original seismic data;

[0008] Selecting a seismic trace with a set signal-to-noise ratio from the time window intercepted seismic records corresponding to all the seismic stations as a standard seismic trace and determining the first arrival wave signal in the standard seismic trace as a standard first arrival wave field;

[0009] For any seismic station, a time window intercepted seismic record corresponding to the seismic station and the standard first arrival wave field are subjected to consistent spectrum correlation processing to obtain a virtual source seismic record corresponding to the seismic station;

[0010] Performing convolution interference processing on the virtual source seismic record corresponding to the seismic station and the standard first arrival wave field to obtain a high signal-to-noise ratio seismic record corresponding to the seismic station after phase recovery;

[0011] Meshing the velocity model of the seismic array monitoring area to obtain a grid model;

[0012] Taking the position of each seismic station as a source point, and using an adaptive time function solution method according to the grid model to obtain the travel time of the first arrival wave at each grid node corresponding to each source point;

[0013] The imaging value at each grid node is obtained based on the high signal-to-noise ratio seismic records after phase recovery corresponding to each of the seismic stations and the travel time of the first arrival wave at each grid node corresponding to each source point, and the grid node corresponding to the imaging value with the largest absolute value is determined as the source position.

[0014] Optionally, before the original seismic data of any seismic station is intercepted by using a time window to obtain a time window interception seismic record corresponding to the seismic station in the original seismic data, the method further includes:

[0015] The format of the original seismic data is converted to obtain seismic data after the format conversion.

[0016] Optionally, obtaining the imaging value at each grid node according to the high signal-to-noise ratio seismic record after phase recovery corresponding to each seismic station and the travel time of the first arrival wave at each grid node corresponding to each earthquake source point specifically includes:

[0017] Calculate the standard travel time, where the standard travel time is the travel time of the first arrival wave at each grid node corresponding to the earthquake source where the standard track is located, calculated according to the position of the earthquake source where the standard track is located and the grid model;

[0018] For any grid node, the difference between the first arrival wave travel time at the grid node corresponding to each of the earthquake source points and the standard travel time is calculated to obtain the difference at the grid node corresponding to each seismic station;

[0019] For any seismic station, using the difference at the grid node corresponding to the seismic station, time-shift correction is performed on the high signal-to-noise ratio seismic record after phase recovery corresponding to the seismic station to obtain the seismic record after time-shift correction corresponding to the seismic station;

[0020] Performing horizontal product processing on the time-shift-corrected seismic records corresponding to all the seismic stations to obtain amplitude-multiplied seismic records;

[0021] The maximum or minimum amplitude value in the seismic record after the amplitude multiplication is selected as the imaging value at the grid node.

[0022] Optionally, before selecting a seismic trace with a set signal-to-noise ratio from the seismic records corresponding to the time windows of all the seismic stations as a standard seismic trace, the method further includes:

[0023] The time window intercepted seismic records corresponding to each of the seismic stations are preprocessed to obtain the preprocessed time window intercepted seismic records corresponding to each of the seismic stations.

[0024] Optionally, preprocessing the time window intercepted seismic records corresponding to each of the seismic stations to obtain the preprocessed time window intercepted seismic records corresponding to each of the seismic stations specifically includes:

[0025] Deleting the data of the set amplitude in the time window intercepted seismic record to obtain the seismic record after abnormal amplitude processing;

[0026] The seismic records after abnormal amplitude processing are sequentially processed by removing the mean, removing the trend and removing the instrument response to obtain the pre-processed time window intercepted seismic records.

[0027] A seismic source location system based on consistent spectrum correlation imaging, comprising:

[0028] An acquisition module is used to acquire the original seismic data of each seismic station in the seismic array;

[0029] An interception module is used for intercepting the original seismic data of any seismic station by using a time window to obtain a time window intercepted seismic record corresponding to the seismic station in the original seismic data, wherein the time window intercepted seismic record includes all first arrival wave signals in the original seismic data;

[0030] A standard first arrival wave field determination module is used to select a seismic trace with a set signal-to-noise ratio from the time window intercepted seismic records corresponding to all the seismic stations as a standard seismic trace and determine the first arrival wave signal in the standard seismic trace as a standard first arrival wave field;

[0031] A virtual source seismic record determination module is used for, for any seismic station, performing consistency spectrum correlation processing on the time window intercepted seismic record corresponding to the seismic station and the standard first arrival wave field to obtain the virtual source seismic record corresponding to the seismic station;

[0032] A convolution interference processing module, used for performing convolution interference processing on the virtual source seismic record corresponding to the seismic station and the standard first arrival wave field to obtain a high signal-to-noise ratio seismic record corresponding to the seismic station after phase recovery;

[0033] A grid model determination module, used for gridding the velocity model of the seismic array monitoring area to obtain a grid model;

[0034] A first arrival wave travel time calculation module is used to use the position of each seismic station as a source point and obtain the first arrival wave travel time at each grid node corresponding to each source point by using an adaptive equation function solution method according to the grid model;

[0035] The module for determining the earthquake source position is used to obtain the imaging value at each grid node based on the high signal-to-noise ratio earthquake records after phase recovery corresponding to each seismic station and the travel time of the first arrival wave at each grid node corresponding to each earthquake source point, and determine the grid node corresponding to the imaging value with the largest absolute value as the earthquake source position.

[0036] Optionally, the earthquake source location system based on consistency spectrum correlation imaging further includes:

[0037] The format conversion module is used to perform format conversion on the original seismic data to obtain seismic data after format conversion.

[0038] Optionally, the earthquake source location determination module specifically includes:

[0039] A standard travel time calculation unit, used for calculating the standard travel time, wherein the standard travel time is the travel time of the first arrival wave at each grid node corresponding to the earthquake source where the standard track is located, calculated according to the position of the earthquake source where the standard track is located and the grid model;

[0040] A difference determination unit, for calculating, for any grid node, the difference between the first arrival wave travel time at the grid node corresponding to each of the earthquake source points and the standard travel time, to obtain the difference at the grid node corresponding to each seismic station;

[0041] A time shift correction processing unit is used to perform time shift correction on the high signal-to-noise ratio seismic record after phase recovery corresponding to any seismic station by using the difference at the grid node corresponding to the seismic station to obtain the seismic record after time shift correction corresponding to the seismic station;

[0042] A horizontal product processing unit, used for performing horizontal product processing on the time-shift-corrected seismic records corresponding to all the seismic stations to obtain amplitude-multiplied seismic records;

[0043] An imaging value calculation unit is used to select the maximum or minimum amplitude value in the seismic record after the amplitude multiplication as the imaging value at the grid node.

[0044] Optionally, the earthquake source location system based on consistency spectrum correlation imaging further includes:

[0045] The preprocessing module is used to preprocess the time window intercepted seismic records corresponding to each of the seismic stations to obtain the preprocessed time window intercepted seismic records corresponding to each of the seismic stations.

[0046] Optionally, the preprocessing module specifically includes:

[0047] A deleting unit, used for deleting the data of the set amplitude in the time window intercepted seismic record to obtain the seismic record after abnormal amplitude processing;

[0048] The preprocessing unit is used to sequentially remove the mean, trend and instrument response of the seismic record after the abnormal amplitude processing to obtain the preprocessed time window intercepted seismic record.

[0049] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: the present invention uses a time window to intercept the time window intercepted seismic record corresponding to the seismic station in the original seismic data; selects the seismic trace with a set signal-to-noise ratio as the standard seismic trace in the time window intercepted seismic records corresponding to all seismic stations and determines the first arrival wave signal in the standard seismic trace as the standard first arrival wave field; performs consistency spectrum correlation processing on the time window intercepted seismic record corresponding to the seismic station and the standard first arrival wave field to obtain the virtual source seismic record corresponding to the seismic station; performs convolution interference processing on the virtual source seismic record corresponding to the seismic station and the standard first arrival wave field to obtain The high signal-to-noise ratio seismic records after phase recovery corresponding to the seismic stations; the velocity model of the monitoring area of ​​the seismic array is gridded to obtain a grid model; the position of each seismic station is used as the source point, and the adaptive equation function solution method is used according to the grid model to obtain the first arrival wave travel time at each grid node corresponding to each source point; the imaging value at each grid node is obtained according to the high signal-to-noise ratio seismic records after phase recovery corresponding to each seismic station and the first arrival wave travel time at each grid node corresponding to each source point, and the grid node corresponding to the imaging value with the largest absolute value is determined as the source position, which can improve the efficiency and accuracy of source positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0051] Figure 1 A flow chart of a method for earthquake source location based on consistent spectrum correlation imaging provided by an embodiment of the present invention;

[0052] Figure 2 A schematic diagram of the layout of seismic stations for earthquake source location provided by an embodiment of the present invention;

[0053] Figure 3 A seismic record diagram containing a first-arrival wave field after preprocessing provided by an embodiment of the present invention;

[0054] Figure 4 A virtual source seismic record map obtained based on consistent spectrum correlation in step 7 provided in an embodiment of the present invention;

[0055] Figure 5 A high signal-to-noise ratio seismic record image based on convolution phase recovery obtained in step eight of the embodiment of the present invention;

[0056] Figure 6 A waveform imaging result diagram for determining the earthquake source location provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0057] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0058] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0059] The purpose of the present invention is to provide a data-driven relative source positioning method based on consistent spectral correlation imaging to improve the accuracy of source positioning and realize accurate source positioning based on weak seismic events in natural earthquake and microseismic monitoring, in view of the fact that existing source positioning technology cannot achieve high-precision source positioning results based on complex medium conditions and complex seismic records.

[0060] like Figure 1 As shown, an embodiment of the present invention provides a method for earthquake source location based on consistent spectrum correlation imaging, including:

[0061] Step 101: Obtain original seismic data from each seismic station in the seismic array.

[0062] Step 102: For the original seismic data of any seismic station, a time window is used to intercept the seismic record corresponding to the seismic station in the original seismic data. The time window intercepted seismic record includes all the first arrival wave signals in the original seismic data.

[0063] Step 103: Selecting a seismic trace with a set signal-to-noise ratio from the time-window intercepted seismic records corresponding to all the seismic stations as a standard seismic trace and determining the first arrival wave signal in the standard seismic trace as a standard first arrival wave field.

[0064] Step 104: For any seismic station, a consistency spectrum correlation process is performed on the time window intercepted seismic record corresponding to the seismic station and the standard first arrival wave field to obtain the virtual source seismic record corresponding to the seismic station.

[0065] Step 105: Perform convolution interference processing on the virtual source seismic record corresponding to the seismic station and the standard first arrival wave field to obtain a high signal-to-noise ratio seismic record corresponding to the seismic station after phase recovery.

[0066] Step 106: gridding the velocity model of the seismic array monitoring area to obtain a grid model.

[0067] Step 107: taking the position of each of the seismic stations as a source point, and using an adaptive time function solution method according to the grid model to obtain the travel time of the first arrival wave at each grid node corresponding to each source point.

[0068] Step 108: Obtain imaging values ​​at each grid node based on the high signal-to-noise ratio seismic records after phase recovery corresponding to each of the seismic stations and the travel time of the first arrival wave at each grid node corresponding to each earthquake source point, and determine the grid node corresponding to the imaging value with the largest absolute value as the earthquake source position.

[0069] In practical applications, for the original seismic data of any seismic station, before using the time window to intercept the seismic record corresponding to the seismic station in the original seismic data, the method further includes:

[0070] The format of the original seismic data is converted to obtain seismic data after the format conversion.

[0071] In practical applications, the imaging value at each grid node is obtained according to the high signal-to-noise ratio seismic records after phase recovery corresponding to each seismic station and the travel time of the first arrival wave at each grid node corresponding to each source point, specifically including:

[0072] The standard travel time is calculated, where the standard travel time is the travel time of the first arrival wave at each grid node corresponding to the earthquake source where the standard track is located, calculated according to the position of the earthquake source where the standard track is located and the grid model.

[0073] For any grid node, the difference between the first arrival wave travel time and the standard travel time at the grid node corresponding to each seismic source point is calculated to obtain the difference at the grid node corresponding to each seismic station.

[0074] For any seismic station, the difference at the grid node corresponding to the seismic station is used to perform time-shift correction on the high signal-to-noise ratio seismic record after phase recovery corresponding to the seismic station to obtain the seismic record after time-shift correction corresponding to the seismic station.

[0075] The time-shift-corrected seismic records corresponding to all the seismic stations are subjected to horizontal product processing to obtain amplitude-multiplied seismic records.

[0076] The maximum or minimum amplitude value in the seismic record after the amplitude multiplication is selected as the imaging value at the grid node.

[0077] In practical applications, before selecting a seismic trace with a set signal-to-noise ratio from the seismic records corresponding to the time windows of all the seismic stations as a standard seismic trace, the method further includes:

[0078] The time window intercepted seismic records corresponding to each of the seismic stations are preprocessed to obtain the preprocessed time window intercepted seismic records corresponding to each of the seismic stations.

[0079] In practical applications, the preprocessing of the time window intercepted seismic records corresponding to each of the seismic stations to obtain the preprocessed time window intercepted seismic records corresponding to each of the seismic stations specifically includes:

[0080] The data of the set amplitude in the time window intercepted seismic record is deleted to obtain the seismic record after abnormal amplitude processing.

[0081] The seismic records after abnormal amplitude processing are sequentially processed by removing the mean, removing the trend and removing the instrument response to obtain the preprocessed time window intercepted seismic records.

[0082] The embodiment of the present invention further provides a source location system based on consistent spectrum correlation imaging corresponding to the above method, comprising:

[0083] The acquisition module is used to obtain the original seismic data of each seismic station in the seismic array.

[0084] The interception module is used to intercept the original seismic data of any seismic station using a time window to obtain the time window intercepted seismic record corresponding to the seismic station in the original seismic data, and the time window intercepted seismic record includes all the first arrival wave signals in the original seismic data.

[0085] The standard first arrival wave field determination module is used to select a seismic trace with a set signal-to-noise ratio from the time window intercepted seismic records corresponding to all the seismic stations as a standard seismic trace and determine the first arrival wave signal in the standard seismic trace as a standard first arrival wave field.

[0086] The virtual source seismic record determination module is used to perform consistent spectrum correlation processing on the time window intercepted seismic record corresponding to any seismic station and the standard first arrival wave field to obtain the virtual source seismic record corresponding to the seismic station.

[0087] The convolution interference processing module is used to perform convolution interference processing on the virtual source seismic record corresponding to the seismic station and the standard first arrival wave field to obtain the high signal-to-noise ratio seismic record corresponding to the seismic station after phase recovery.

[0088] The grid model determination module is used to grid the velocity model of the seismic array monitoring area to obtain a grid model.

[0089] The first arrival wave travel time calculation module is used to take the position of each seismic station as the source point, and use the adaptive process function solution method according to the grid model to obtain the first arrival wave travel time at each grid node corresponding to each source point.

[0090] The module for determining the earthquake source position is used to obtain the imaging value at each grid node based on the high signal-to-noise ratio earthquake records after phase recovery corresponding to each seismic station and the travel time of the first arrival wave at each grid node corresponding to each earthquake source point, and determine the grid node corresponding to the imaging value with the largest absolute value as the earthquake source position.

[0091] As an optional implementation, the earthquake source location system based on consistent spectrum correlation imaging further includes:

[0092] The format conversion module is used to perform format conversion on the original seismic data to obtain seismic data after format conversion.

[0093] As an optional implementation, the earthquake source location determination module specifically includes:

[0094] The standard travel time calculation unit is used to calculate the standard travel time, wherein the standard travel time is the travel time of the first arrival wave at each grid node corresponding to the earthquake source where the standard track is located, calculated according to the position of the earthquake source where the standard track is located and the grid model.

[0095] The difference determination unit is used to calculate the difference between the first arrival wave travel time and the standard travel time at the grid node corresponding to each seismic source point for any grid node to obtain the difference at the grid node corresponding to each seismic station.

[0096] The time-shift correction processing unit is used to perform time-shift correction on the high signal-to-noise ratio seismic record after phase recovery corresponding to any seismic station using the difference at the grid node corresponding to the seismic station to obtain the seismic record after time-shift correction corresponding to the seismic station.

[0097] The horizontal product processing unit is used to perform horizontal product processing on the time-shift-corrected seismic records corresponding to all the seismic stations to obtain amplitude-multiplied seismic records.

[0098] An imaging value calculation unit is used to select the maximum or minimum amplitude value in the seismic record after the amplitude multiplication as the imaging value at the grid node.

[0099] As an optional implementation, the earthquake source location system based on consistent spectrum correlation imaging further includes:

[0100] The preprocessing module is used to preprocess the time window intercepted seismic records corresponding to each of the seismic stations to obtain the preprocessed time window intercepted seismic records corresponding to each of the seismic stations.

[0101] As an optional implementation, the preprocessing module specifically includes:

[0102] The deleting unit is used to delete the data of the set amplitude in the time window intercepted seismic record to obtain the seismic record after abnormal amplitude processing.

[0103] The preprocessing unit is used to sequentially remove the mean, trend and instrument response of the seismic record after the abnormal amplitude processing to obtain the preprocessed time window intercepted seismic record.

[0104] The embodiment of the present invention also provides a specific process of using the above method to perform the following processing:

[0105] Step 1: For the area of ​​earthquake source monitoring, reasonable seismic arrays are arranged at equal intervals to collect earthquake source signals at different incident angles.

[0106] Figure 2 This is the layout of the seismic array used for earthquake source location, where the triangle represents the seismic station and the five-pointed star represents the actual earthquake source location. It can be seen that the dense seismic array is symmetrically and evenly arranged along both ends of the monitored area. Therefore, the seismic array can collect seismic waves of different incident angles from any source inside the monitoring area, and the full-incident-angle earthquake source monitoring system can provide sufficient data support for high-precision earthquake source location imaging.

[0107] Step 2: After the earthquake or microseismic event is over, the original seismic data is exported from each seismic station, and the format of the original seismic data is further converted to generate seismic data after the format conversion.

[0108] Step 3: Based on the seismic data after format conversion, using a time window whose length can cover all first-arrival wave signals in a seismic record, intercept the seismic record containing the first-arrival wave signal, and generate a time window intercepted seismic record corresponding to each seismic data after format conversion.

[0109] Step 4: For the time window intercepted earthquake record, the records of abnormal amplitudes such as null value records and maximum amplitude records are processed and the abnormal amplitudes are deleted to generate earthquake records after abnormal amplitude processing. The time window intercepted earthquake record is a whole block of earthquake records, such as Figure 3 As shown, the abnormal data in the entire block of seismic data is deleted.

[0110] Step 5: For the seismic records after abnormal amplitude processing, preprocessing of removing mean, trend and instrument response is carried out in sequence to obtain preprocessed seismic data.

[0111] like Figure 3 As shown in the figure, due to the interference of strong energy noise, the earthquake first arrival wave signal is submerged in the strong environmental noise in the form of a weak signal, thereby reducing the accuracy and resolution of source positioning.

[0112] Step 6: Using the pre-processed seismic data, select seismic traces with high signal-to-noise ratio as standard traces, and intercept the first arrival wave signal from the standard trace as the standard first arrival wave field.

[0113] Step 7: Using the pre-processed seismic data obtained in step 5 and the standard first arrival wave field obtained in step 6, the consistency spectrum correlation processing is carried out to obtain the virtual source seismic record, and the formula for obtaining it is:

[0114]

[0115] Among them, || represents the amplitude spectrum, * represents the complex conjugate, ω represents the angular frequency, w represents the white noise coefficient, S(ω) represents the standard first arrival wave field obtained in step 6, U(i,ω) represents the preprocessed seismic data of the i-th seismic station generated in step 5, and VS(i,ω) represents the virtual source seismic record of the i-th seismic station generated in step 7.

[0116] like Figure 4 As shown in the figure, it can be seen that after the processing based on the consistency spectrum correlation, although the earthquake first arrival wave event axis is still the same as the first arrival wave event axis in the seismic record after preprocessing, the travel time is moved up to the negative time axis, indicating that the location of the seismic station where the selected standard first arrival wave field is located is the farthest from the earthquake source. At the same time, the first arrival wave event axis is compressed to a certain extent, and the resolution is further improved.

[0117] Step 8: Using the virtual source seismic record generated in step 7 and the standard first arrival wave field obtained in step 6, convolution interference processing is performed to obtain a high signal-to-noise ratio seismic record after phase recovery. The formula for obtaining the high signal-to-noise ratio seismic record is:

[0118] HU(i,ω)=VS(i,ω)S(ω)

[0119] Among them, HU(i,ω) represents the high signal-to-noise ratio seismic record of the i-th seismic station after phase recovery.

[0120] Will Figure 5 and Figure 3 By comparison, we can see that after phase recovery, the data quality of the original seismic record is greatly improved, the low signal-to-noise ratio first-arrival wave signal is greatly improved, and the signal-to-noise ratio is significantly enhanced.

[0121] Step 9: Use the seismic wave velocity survey data to establish a velocity model for the source monitoring area, and divide the velocity model into grids to obtain a grid model, in which each grid has a constant velocity parameter inside and the grid intersection is the grid node where the first arrival wave to be found is located during its travel. The specific grid model is:

[0122] G(j)=D(V(x))

[0123] Among them, x represents the spatial coordinate, V(x) represents the velocity model established based on the seismic wave velocity survey, D represents the grid operator, and G(j) represents the constant velocity parameter inside the jth grid.

[0124] Step 10: Using the grid model generated in step 9, taking the position of each seismic station in step 1 as the source point, and using the adaptive eikonal equation solving method, calculate the travel time of the first arrival wave at each node generated by the excitation of each source point. The formula for calculating the travel time is:

[0125] T(i,k)=AF(L(i);G(j))

[0126] Where L(i) represents the spatial position of the i-th seismic station, the AF symbol represents the adaptive eikonal equation solver, and T(i,k) represents the travel time of the first arrival wave recorded by the i-th seismic station stimulating the k-th grid node.

[0127] Step 11: Calculate the imaging value at each grid node using the high signal-to-noise ratio seismic record after phase recovery obtained in step 8 and the first arrival wave travel time calculated in step 10. For each grid node, the calculation steps are as follows:

[0128] (1) Select the first arrival wave travel time calculated at the source location of the standard trace generated in step 6 as the standard travel time.

[0129] (2) Calculate the difference between the first arrival wave travel time and the standard travel time from each earthquake source point to the grid node. The formula for this is:

[0130] DT(i,k)=T(i,k)-ST

[0131] Where ST represents the standard travel time, and DT(i,k) represents the difference between the travel time of the first arrival wave recorded by the i-th seismic station stimulating the k-th grid node and the standard travel time.

[0132] (3) Using the difference calculated in the above steps, time-shift correction is performed on the high signal-to-noise ratio seismic record after phase recovery generated in step eight to generate a seismic record after time-shift correction.

[0133] (4) Using the time-shift corrected seismic records, horizontal product processing is performed to generate seismic records after amplitude multiplication. The formula for obtaining the seismic records is:

[0134]

[0135] Among them, N represents the total number of seismic stations, Π represents the multiplication symbol, THU(i,t) represents the seismic record of each seismic station after time shift correction, and MHU(t) represents the seismic record after amplitude multiplication.

[0136] (5) Using the seismic records after amplitude multiplication, the maximum or minimum amplitude value is selected as the imaging value at the desired grid node. The formula for obtaining the value is:

[0137]

[0138] Among them, the max and min symbols represent the maximum and minimum values ​​respectively, the abs symbol represents the absolute value operator, and I(k) represents the imaging value of the kth grid node.

[0139] like Figure 6 As shown, it can be seen that the signal-to-noise ratio of the entire imaging result is extremely high, and the location of the local obvious negative anomaly amplitude is the location of the earthquake source.

[0140] Step 12: Calculate the maximum absolute value of the imaging value using the imaging result calculated in step 11. The grid node position where the maximum absolute amplitude is located is the earthquake source position.

[0141] The beneficial technical effects of the present invention are: utilizing a reasonable seismic station monitoring system, based on the first-arrival wave records of earthquakes, combining the correlation of seismic events between different stations, utilizing consistency spectrum-based correlation technology to achieve enhancement of the first-arrival wave signal; at the same time, utilizing an adaptive eikonal equation solving method to achieve accurate calculation of the first-arrival wave travel time under complex medium conditions; finally, utilizing relative imaging positioning method to achieve accurate source positioning based on weak seismic events under complex medium conditions, which can improve the efficiency and accuracy of source positioning.

[0142] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the system disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0143] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for earthquake source location based on consistent spectrum correlation imaging, characterized in that: include: Obtain the original seismic data of each seismic station in the seismic array; For the original seismic data of any seismic station, a time window is used to intercept the time window intercepted seismic record corresponding to the seismic station in the original seismic data, and the time window intercepted seismic record includes all the first arrival wave signals in the original seismic data; Selecting a seismic trace with a set signal-to-noise ratio from the time window intercepted seismic records corresponding to all the seismic stations as a standard seismic trace and determining the first arrival wave signal in the standard seismic trace as a standard first arrival wave field; For any seismic station, a time window intercepted seismic record corresponding to the seismic station and the standard first arrival wave field are subjected to consistent spectrum correlation processing to obtain a virtual source seismic record corresponding to the seismic station; Performing convolution interference processing on the virtual source seismic record corresponding to the seismic station and the standard first arrival wave field to obtain a high signal-to-noise ratio seismic record corresponding to the seismic station after phase recovery; Meshing the velocity model of the seismic array monitoring area to obtain a grid model; Taking the position of each seismic station as a source point, and using an adaptive time function solution method according to the grid model to obtain the travel time of the first arrival wave at each grid node corresponding to each source point; The imaging value at each grid node is obtained based on the high signal-to-noise ratio seismic records after phase recovery corresponding to each of the seismic stations and the travel time of the first arrival wave at each grid node corresponding to each source point, and the grid node corresponding to the imaging value with the largest absolute value is determined as the source position.

2. The earthquake source location method based on consistency spectrum correlation imaging according to claim 1, characterized in that: Before the original seismic data of any seismic station is intercepted by using a time window to obtain a time window interception seismic record corresponding to the seismic station in the original seismic data, the method further includes: The format of the original seismic data is converted to obtain seismic data after the format conversion.

3. The earthquake source location method based on consistency spectrum correlation imaging according to claim 1, characterized in that: The imaging value at each grid node is obtained according to the high signal-to-noise ratio seismic records after phase recovery corresponding to each seismic station and the travel time of the first arrival wave at each grid node corresponding to each earthquake source point, specifically including: Calculate the standard travel time, where the standard travel time is the travel time of the first arrival wave at each grid node corresponding to the earthquake source where the standard track is located, calculated according to the position of the earthquake source where the standard track is located and the grid model; For any grid node, the difference between the first arrival wave travel time at the grid node corresponding to each of the earthquake source points and the standard travel time is calculated to obtain the difference at the grid node corresponding to each seismic station; For any seismic station, using the difference at the grid node corresponding to the seismic station, time-shift correction is performed on the high signal-to-noise ratio seismic record after phase recovery corresponding to the seismic station to obtain the seismic record after time-shift correction corresponding to the seismic station; Performing horizontal product processing on the time-shift-corrected seismic records corresponding to all the seismic stations to obtain amplitude-multiplied seismic records; The maximum or minimum amplitude value in the seismic record after the amplitude multiplication is selected as the imaging value at the grid node.

4. The earthquake source location method based on consistency spectrum correlation imaging according to claim 1, characterized in that: Before selecting the seismic trace with the set signal-to-noise ratio as the standard seismic trace from the time window intercepted seismic records corresponding to all the seismic stations, the method further includes: The time window intercepted seismic records corresponding to each of the seismic stations are preprocessed to obtain the preprocessed time window intercepted seismic records corresponding to each of the seismic stations.

5. The earthquake source location method based on consistency spectrum correlation imaging according to claim 4, characterized in that: The preprocessing of the time window intercepted seismic records corresponding to each of the seismic stations to obtain the preprocessed time window intercepted seismic records corresponding to each of the seismic stations specifically includes: Deleting the data of the set amplitude in the time window intercepted seismic record to obtain the seismic record after abnormal amplitude processing; The seismic records after abnormal amplitude processing are sequentially processed by removing the mean, removing the trend and removing the instrument response to obtain the pre-processed time window intercepted seismic records.

6. A source location system based on consistent spectrum correlation imaging, characterized in that: include: An acquisition module is used to acquire the original seismic data of each seismic station in the seismic array; An interception module is used for intercepting the original seismic data of any seismic station by using a time window to obtain a time window intercepted seismic record corresponding to the seismic station in the original seismic data, wherein the time window intercepted seismic record includes all first arrival wave signals in the original seismic data; A standard first arrival wave field determination module is used to select a seismic trace with a set signal-to-noise ratio from the time window intercepted seismic records corresponding to all the seismic stations as a standard seismic trace and determine the first arrival wave signal in the standard seismic trace as a standard first arrival wave field; A virtual source seismic record determination module is used for, for any seismic station, performing consistency spectrum correlation processing on the time window intercepted seismic record corresponding to the seismic station and the standard first arrival wave field to obtain the virtual source seismic record corresponding to the seismic station; A convolution interference processing module, used for performing convolution interference processing on the virtual source seismic record corresponding to the seismic station and the standard first arrival wave field to obtain a high signal-to-noise ratio seismic record corresponding to the seismic station after phase recovery; A grid model determination module, used for gridding the velocity model of the seismic array monitoring area to obtain a grid model; A first arrival wave travel time calculation module is used to use the position of each seismic station as a source point and obtain the first arrival wave travel time at each grid node corresponding to each source point by using an adaptive process function solution method according to the grid model; The module for determining the earthquake source position is used to obtain the imaging value at each grid node based on the high signal-to-noise ratio earthquake records after phase recovery corresponding to each seismic station and the travel time of the first arrival wave at each grid node corresponding to each earthquake source point, and determine the grid node corresponding to the imaging value with the largest absolute value as the earthquake source position.

7. The earthquake source location system based on consistency spectrum correlation imaging according to claim 6, characterized in that: Also includes: The format conversion module is used to perform format conversion on the original seismic data to obtain seismic data after format conversion.

8. The earthquake source location system based on consistency spectrum correlation imaging according to claim 6, characterized in that: The earthquake source location determination module specifically includes: A standard travel time calculation unit, used for calculating the standard travel time, wherein the standard travel time is the travel time of the first arrival wave at each grid node corresponding to the earthquake source where the standard track is located, calculated according to the position of the earthquake source where the standard track is located and the grid model; A difference determination unit, for calculating, for any grid node, the difference between the first arrival wave travel time at the grid node corresponding to each of the earthquake source points and the standard travel time, to obtain the difference at the grid node corresponding to each seismic station; A time shift correction processing unit is used to perform time shift correction on the high signal-to-noise ratio seismic record after phase recovery corresponding to any seismic station by using the difference at the grid node corresponding to the seismic station to obtain the seismic record after time shift correction corresponding to the seismic station; A horizontal product processing unit, used for performing horizontal product processing on the time-shift-corrected seismic records corresponding to all the seismic stations to obtain amplitude-multiplied seismic records; An imaging value calculation unit is used to select the maximum or minimum amplitude value in the seismic record after the amplitude multiplication as the imaging value at the grid node.

9. The earthquake source location system based on consistency spectrum correlation imaging according to claim 6, characterized in that: Also includes: The preprocessing module is used to preprocess the time window intercepted seismic records corresponding to each of the seismic stations to obtain the preprocessed time window intercepted seismic records corresponding to each of the seismic stations.

10. The earthquake source location system based on consistency spectrum correlation imaging according to claim 9, characterized in that: The preprocessing module specifically includes: A deleting unit, used for deleting the data of the set amplitude in the time window intercepted seismic record to obtain the seismic record after abnormal amplitude processing; The preprocessing unit is used to sequentially remove the mean, trend and instrument response of the seismic record after the abnormal amplitude processing to obtain the preprocessed time window intercepted seismic record.

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