An Automatic Selection Method for Virtual Source Records Applicable to Environmental Noise Seismic Exploration

Abstract

This invention belongs to the field of environmental noise seismic exploration, specifically relating to an automatic selection method for virtual source records suitable for environmental noise seismic exploration. The method includes: Step 1, preprocessing the original environmental noise seismic data to obtain preprocessed environmental noise seismic data; Step 2, reconstructing virtual source seismic records for different time periods at each receiving point using the preprocessed environmental noise seismic data; Step 3, performing linear scan stacking calculations on the positive and negative time semi-axis of each virtual source seismic record to obtain scan stacking amplitude curves based on different linear velocities; comparing and analyzing the maximum amplitude values ​​of the scan stacking amplitude curves of the virtual source seismic records based on the positive and negative time semi-axis to automatically select virtual source seismic records; Step 4, repeating Step 3 to achieve automatic selection of virtual source seismic records for different time periods at each receiving point. This invention can achieve automatic screening of high-quality virtual source seismic records rich in surface wave information.

Description

Technical Field

[0001] This invention belongs to the field of environmental noise seismic exploration, and specifically relates to an automatic selection method for virtual source records applicable to environmental noise seismic exploration. Background Technology

[0002] In traditional seismological research, environmental noise seismic data is often regarded as noise interference and needs to be suppressed or deleted. However, in reality, environmental noise seismic signals, after multiple scattering, transmission, reflection, and refraction through the subsurface elastic medium, contain a wealth of useful information about the subsurface medium. This information is highly beneficial for studying the velocity structure from the shallow to the deep layers of the Earth.

[0003] In recent years, with the popularization and widespread use of intelligent seismic nodal instruments, environmental noise seismic exploration methods have developed rapidly and been widely applied. Using cross-correlation seismic interferometry, virtual source seismic records excited by surface virtual sources and received by multiple receivers can be reconstructed from environmental noise seismic data. These records contain response information such as refracted waves, surface waves, reflected waves, and diffracted waves, which can be used to invert and image the structure and physical properties of the formation medium. However, the quality of the virtual source seismic records reconstructed based on environmental noise seismic interferometry is closely related to the distribution of the environmental noise sources. Theoretically, environmental noise sources should satisfy the assumption of uniform distribution in three-dimensional space to achieve symmetrical reconstruction of effective seismic signals across the entire wavefield. However, in actual seismic exploration, the distribution of environmental noise sources is often spatiotemporally non-uniform, resulting in lower quality and asymmetrical distribution characteristics in the reconstructed virtual source seismic records. Therefore, how to select high-quality seismic records from numerous virtual source records has become a key aspect of quality control and data processing in environmental noise seismic exploration. Summary of the Invention

[0004] The purpose of this invention is to provide an automatic selection method for virtual source records applicable to environmental noise seismic exploration. This method can automatically screen high-quality virtual source seismic records rich in surface wave information by comparing and analyzing the energy of linearly tilted superimposed seismic wave fields. This effectively solves the problem of inconsistent quality of calculated virtual source seismic records caused by the non-uniform distribution of noise sources in environmental noise seismic exploration.

[0005] Technical solution to achieve the purpose of this invention:

[0006] An automatic selection method for virtual source records applicable to seismic exploration of environmental noise, the method comprising:

[0007] Step 1: Preprocess the raw environmental noise seismic data to obtain preprocessed environmental noise seismic data;

[0008] Step 2: Using the preprocessed environmental noise seismic data, reconstruct the virtual source seismic records for different time periods at each receiving point location;

[0009] Step 3: For the virtual source seismic records of the positive and negative time half-axis, perform linear scan stacking calculations to obtain scan stacking curves based on different linear velocities; compare and analyze the maximum amplitude values ​​of the scan stacking amplitude curves based on the virtual source seismic records of the positive and negative time half-axis, and automatically select the virtual source seismic record.

[0010] Step 4: Repeat step 3 to achieve automatic selection of virtual source seismic records for different time periods at each receiving point location.

[0011] The preprocessing in step 1 includes: instrument response removal, mean removal, trend removal, data segmentation, outlier suppression, and spectral whitening.

[0012] The different time periods of the virtual source earthquake record include the positive time half-axis and the negative time half-axis.

[0013] Step 3 includes:

[0014] Step 3.1, set the linear speed range;

[0015] Step 3.2: Calculate the time field under different offset distances and different linear velocities;

[0016] Step 3.3: Calculate the superimposed sweep amplitude under different linear velocities;

[0017] Step 3.4: Calculate the maximum superimposed amplitude value in the linear scan superimposed amplitude curve;

[0018] Step 3.5: Compare and analyze the maximum superposition amplitude value obtained from the linear scanning superposition amplitude curve of the virtual source seismic records based on the positive and negative time half-axis, so as to realize the automatic selection of virtual source seismic records rich in surface wave information.

[0019] The formulas for calculating the time field under different offset distances and different linear velocities in step 3.2 are as follows:

[0020] t i,j =x i / v j

[0021] Where, x i This represents the offset of the i-th trace in the virtual source seismic record; v j t represents the j-th linear velocity; i,j Representing the offset at the i-th track, using the j-th linear velocity v j The time field of the calculation.

[0022] The formula for calculating the superimposed scanning amplitude at different linear velocities in step 3.3 is as follows:

[0023]

[0024] Where u(t) i,j ) represents time t i,j The virtual source seismic record wavefield below; s j Represents speed v j The scanning superimposed amplitude.

[0025] The formula for calculating the maximum superimposed amplitude value in step 3.4 is as follows:

[0026] s m =max(s j )

[0027] Where max represents the maximum value operator; s m The superimposed amplitudes s in the representative curve j The maximum amplitude value is obtained by finding the following.

[0028] In step 3.5, the automatic selection calculation formula for virtual source seismic records is as follows:

[0029]

[0030] Among them, s m+ and s m- These represent the values ​​of s obtained from the calculation of the positive and negative time semi-axis, respectively. m value, u + and u - represents the virtual source seismic records of the positive and negative time halves, respectively, and p represents the automatically selected virtual source seismic record rich in surface wave information.

[0031] The beneficial technical effects of this invention are as follows:

[0032] 1. The present invention provides an automatic selection method for virtual source records applicable to environmental noise seismic exploration. By comparing and analyzing the energy of linearly tilted superimposed seismic wave fields, it is possible to automatically screen high-quality virtual source seismic records rich in surface wave information.

[0033] 2. The present invention provides an automatic selection method for virtual source records applicable to environmental noise seismic exploration. By superimposing linear scanning amplitudes based on different velocities, the method can achieve automatic in-phase superposition of the energy of seismic surface waves in virtual source seismic records and efficiently obtain linear scanning superposition curves.

[0034] 3. The present invention provides an automatic selection method for virtual source records applicable to environmental noise seismic exploration. By comparing and analyzing the linear scanning superimposed amplitude curves calculated separately for positive and negative time axes, the method can automatically screen ideal environmental noise virtual source seismic records, thereby improving the quality of environmental noise seismic exploration. Attached Figure Description

[0035] Figure 1This is a virtual source seismic record diagram showing the cross-correlation of environmental noise in an embodiment of the present invention;

[0036] Figure 2 This is a linear scan superimposed amplitude curve diagram in an embodiment of the present invention;

[0037] Figure 3 This is a virtual source seismic record map automatically selected using linear scan overlay in an embodiment of the present invention. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0039] This invention provides an automatic selection method for virtual source records applicable to seismic exploration of environmental noise, specifically including the following steps:

[0040] Step 1: Preprocess the raw environmental noise seismic data to obtain preprocessed environmental noise seismic data.

[0041] The raw environmental noise seismic data were preprocessed sequentially, including instrument response removal, mean removal, trend removal, data segmentation, outlier suppression, and spectral whitening, to obtain the preprocessed environmental noise seismic data.

[0042] Step 2: Using the preprocessed environmental noise seismic data, reconstruct the virtual source seismic records for different time periods at each receiver location.

[0043] By using the preprocessed environmental noise seismic data, cross-correlation processing was performed to reconstruct virtual source seismic records for different time periods at each receiver location.

[0044] In one specific implementation, the different time periods of the virtual source seismic record include a positive time half-axis and a negative time half-axis.

[0045] Figure 1 This is a virtual source seismic record reconstructed from preprocessed environmental noise seismic data. Figure 1 It is clearly visible that no effective seismic information is developed on the positive time half-axis, while strong seismic surface waves with symmetrical distribution are developed on the negative time half-axis.

[0046] Step 3: For the virtual source seismic records along the positive and negative time axes, perform linear scan stacking calculations to obtain scan stacking curves based on different linear velocities; compare and analyze the maximum amplitude values ​​of the scan stacking amplitude curves based on the virtual source seismic records along the positive and negative time axes, and automatically select the virtual source seismic record.

[0047] Step 3.1, set the linear velocity range v j ;

[0048] Step 3.2: Calculate the time field under different offsets and linear velocities. The calculation formula is as follows:

[0049] t i,j =x i / v j

[0050] Where, x i This represents the offset of the i-th trace in the virtual source seismic record; v j t represents the j-th linear velocity; i,j Representing the offset at the i-th track, using the j-th linear velocity v j The calculated time field;

[0051] Step 3.3: Calculate the superimposed scanning amplitude under different linear velocities. The calculation formula is as follows:

[0052]

[0053] Where u(t) i,j ) represents time t i,j The virtual source seismic record wavefield below; s j Represents speed v j The scanning superimposed amplitude.

[0054] Figure 2 To utilize Figure 1 The positive and negative time semi-axis virtual source seismic records and the superimposed amplitudes at different linear velocities calculated in step 3.3 are shown, yielding the linear scan superimposed amplitude curves. (From...) Figure 2 It can be seen that the positive and negative time axes exhibit different superimposed amplitude characteristics.

[0055] Step 3.4: Calculate the maximum superimposed amplitude value in the linear scan superimposed amplitude curve. The calculation formula is as follows:

[0056] s m =max(s j )

[0057] Where max represents the maximum value operator; s m The superimposed amplitudes s in the representative curve j The maximum amplitude value is obtained by finding the following.

[0058] Step 3.5: Compare and analyze the maximum stacking amplitude values ​​obtained from the linear scan stacking amplitude curves of virtual source seismic records based on positive and negative time half-axis, thereby achieving automatic selection of virtual source seismic records rich in surface wave information.

[0059] In one specific implementation, the s values ​​obtained from the calculation of the positive and negative time semi-axis are compared and analyzed. m The value enables automatic selection of virtual source seismic records rich in surface wave information. The specific calculation formula is as follows:

[0060]

[0061] Among them, s m+ and s m- These represent the values ​​of s obtained from the calculation of the positive and negative time semi-axis, respectively. m value, u + and u - represents the virtual source seismic records of the positive and negative time halves, respectively, and p represents the automatically selected virtual source seismic record rich in surface wave information.

[0062] Step 4: Repeat step 3 to achieve automatic selection of virtual source seismic records for different time periods at each receiving point location.

[0063] based on Figure 2 As shown in the linear scan stacked amplitude curve, the maximum stacked amplitude value of the negative time half-axis is greater than that of the positive time half-axis. Therefore, based on step 3.5, the virtual source seismic record of the negative time half-axis is automatically selected as the final preferred virtual source seismic record. Figure 3 It is evident that linear seismic surface waves are well-developed in the automatically selected virtual source seismic records, providing a reliable data foundation for the extraction of dispersion curves and surface wave inversion.

[0064] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. All contents not described in detail in the present invention can be derived from existing technologies.

Claims

1. A method for automatic selection of virtual source records suitable for seismic exploration of environmental noise, characterized in that, The method includes: Step 1: Preprocess the raw environmental noise seismic data to obtain preprocessed environmental noise seismic data; Step 2: Using the preprocessed environmental noise seismic data, reconstruct the virtual source seismic records for different time periods at each receiving point location; Step 3: For the virtual source seismic records of the positive and negative time half-axis, perform linear scan stacking calculations to obtain scan stacking curves based on different linear velocities; compare and analyze the maximum amplitude values ​​of the scan stacking amplitude curves based on the virtual source seismic records of the positive and negative time half-axis, and automatically select the virtual source seismic record. Step 4: Repeat step 3 to achieve automatic selection of virtual source seismic records for different time periods at each receiving point location; Step 3 includes: Step 3.1, set the linear speed range; Step 3.2: Calculate the time field under different offset distances and different linear velocities; Step 3.3: Calculate the superimposed sweep amplitude under different linear velocities; Step 3.4: Calculate the maximum superimposed amplitude value in the linear scan superimposed amplitude curve; Step 3.5: Compare and analyze the maximum superposition amplitude value obtained from the linear scanning superposition amplitude curve of the virtual source seismic records based on the positive and negative time half-axis, so as to realize the automatic selection of virtual source seismic records rich in surface wave information.

2. The method for automatic selection of virtual source records applicable to environmental noise seismic exploration according to claim 1, characterized in that, The preprocessing in step 1 includes: instrument response removal, mean removal, trend removal, data segmentation, outlier suppression, and spectral whitening.

3. The method for automatic selection of virtual source records applicable to environmental noise seismic exploration according to claim 1, characterized in that, The different time periods of the virtual source earthquake record include the positive time half-axis and the negative time half-axis.

4. The method for automatic selection of virtual source records applicable to environmental noise seismic exploration according to claim 1, characterized in that, The formulas for calculating the time field under different offset distances and different linear velocities in step 3.2 are as follows: t i,j =x i / v j Where, x i This represents the offset of the i-th trace in the virtual source seismic record; v j t represents the j-th linear velocity; i,j Representing the offset at the i-th track, using the j-th linear velocity v j The time field of the calculation.

5. The method for automatic selection of virtual source records applicable to environmental noise seismic exploration according to claim 4, characterized in that, The formula for calculating the superimposed scanning amplitude at different linear velocities in step 3.3 is as follows: Where u(t) i,j ) represents time t i,j The virtual source seismic record wavefield below; s j Represents speed v j The scanning superimposed amplitude.

6. The method for automatic selection of virtual source records applicable to environmental noise seismic exploration according to claim 5, characterized in that, The formula for calculating the maximum superimposed amplitude value in step 3.4 is as follows: s m =max(s j ) Where max represents the maximum value operator; s m The superimposed amplitudes s in the representative curve j The maximum amplitude value is obtained by finding the following.

7. The method for automatic selection of virtual source records applicable to environmental noise seismic exploration according to claim 6, characterized in that, In step 3.5, the automatic selection calculation formula for virtual source seismic records is as follows: Among them, s m+ and s m- These represent the values ​​of s obtained from the calculation of the positive and negative time semi-axis, respectively. m value, u + and u - represents the virtual source seismic records of the positive and negative time halves, respectively, and p represents the automatically selected virtual source seismic record rich in surface wave information.

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