Improved energy replacement surface wave suppression method

Abstract

The invention provides an improved energy replacement surface wave suppression method. The method comprises the following steps: step 1, determining the range of a surface wave frequency band; step 2, dividing the seismic signals into signals within a surface wave bandwidth range and signals outside the surface wave bandwidth range; step 3, simultaneously constraining and extracting surface waves from two aspects of a frequency factor and a linear factor for signals in a surface wave bandwidth range; step 4, performing time-varying amplitude energy adjustment on the signals outside the surface wave bandwidth range to obtain time-varying reference signals; 5, gain operators in all the time windows are obtained respectively; step 6, suppressing the surface wave strong energy to the intensity having the same energy level as the reference signal; and step 7, combining the surface wave bandwidth inner signal and the surface wave bandwidth outer signal after surface wave suppression to obtain a final result. According to the improved energy replacement surface wave suppression method, surface wave interference is suppressed to the greatest extent by utilizing linear components of surface waves and seismic wave energy time-varying factor characteristics, and compared with a conventional method, the surface wave suppression is more thorough, and the result is more reliable.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas exploration seismic data processing, and in particular to an improved energy replacement surface wave suppression method. Background Art

[0002] With the continuous deepening of oil and gas exploration and development, higher requirements are placed on the signal-to-noise ratio and resolution of seismic data. As a regular interference, seismic surface waves are commonly found in onshore seismic data. They are characterized by low frequency, strong energy, and low speed. The surface wave energy is about ten times the energy of the effective signal. It is distributed approximately linearly on the shot set, and the surface waves and effective signals are intertwined and overlapped. Surface waves are mainly distributed near the shot offset of seismic records. The traditional detector combination receiving method is conducive to suppressing surface waves. However, with the promotion and application of single-point high-density seismic technology, surface waves have seriously reduced the signal-to-noise ratio of seismic data. The effective signals in the seismic data are submerged in the noise, which seriously affects the quality of the seismic data. Surface wave suppression is a crucial step in the processing of seismic data.

[0003] In view of the low frequency, strong energy and low apparent velocity of surface waves, domestic and foreign scholars have proposed a large number of surface wave noise suppression methods. The current surface wave suppression methods mainly include:

[0004] 1. Bandpass filtering method (high-pass filtering) based on frequency difference: According to the frequency distribution range of surface waves in seismic data, a high-pass filter is designed, the low cutoff frequency of the filter is set, and the seismic data is filtered to filter out the components below the low cutoff frequency, thereby realizing surface wave processing. The bandpass filtering method is relatively simple, but it filters out all effective signals below the low cutoff frequency, resulting in the loss of low-frequency effective signals. The frequency-space domain coherent noise attenuation method is performed on data in the surface wave frequency range, and the surface waves are estimated at each frequency based on the minimum square error criterion. The area where the surface waves appear is restricted by the two parameters of velocity and frequency, which has little impact on seismic signals outside the range.

[0005] 2. The frequency-wavenumber domain method of suppressing surface waves based on apparent velocity difference (frequency beam domain filtering) is to perform two-dimensional Fourier transform on seismic data to obtain frequency-wavenumber spectrum. Since there is a difference in apparent velocity between surface waves and effective signals, the low frequency of surface waves and effective signals are separated in the frequency-wavenumber spectrum. The surface wave area is cut off, and then a two-dimensional Fourier inverse transform is performed to obtain seismic data without surface waves.

[0006] At present, the surface wave suppression method has two main shortcomings. On the one hand, the surface wave identification is inaccurate, and the data without surface waves are also processed, thereby destroying the effective signal, or failing to include all the data containing surface waves in the surface wave suppression process; on the other hand, the surface wave suppression loses the low-frequency effective signal. Although the existing surface wave suppression technology has been improved, it will still have a certain degree of impact on the subsequent data interpretation and reservoir inversion work.

[0007] With the continuous deepening of oil and gas exploration, the importance of low-frequency seismic information in seismic data processing has become more and more deeply understood. Low-frequency information is of great significance in high-steep structure imaging, frequency band expansion, and pre-stack inversion. How to protect low-frequency information to the greatest extent during data processing is becoming increasingly important.

[0008] Patent CN104345341A proposes a frequency-band energy seismic surface wave processing method (regional filtering) based on regional constraints. It uses wavelet transform to perform frequency-band processing on seismic data, calculates the average amplitude value in different time windows and different frequency bands, and uses the cumulative superposition statistical analysis method to set the amplitude threshold value. The new amplitude value calculated by the suppression factor formula replaces the original amplitude value, thereby achieving surface wave suppression.

[0009] Patent CN105093282B proposes an energy replacement method based on frequency constraints. The essence of this method for removing surface waves is to use the difference between surface waves and effective signals in terms of frequency and energy. Frequency scanning and spectrum analysis are performed on the data containing surface waves to determine the frequency band range of the surface waves. Within the frequency band of the surface waves, according to the difference in energy between the surface waves and the effective signals, multi-time window root mean square amplitude gain analysis is performed on the separated data inside and outside the frequency bandwidth along the time axis to obtain the gain operator in each time window. In a certain time window containing surface waves, a larger gain operator is used to perform inverse gain calculation on the signal within the frequency bandwidth of the surface waves through gain operator replacement, and the strong energy of the surface waves is suppressed to the intensity with the same energy level as the effective signal, thereby achieving suppression of the surface waves.

[0010] Patent CN112379427A proposes a surface wave noise suppression method and device, wherein the method includes: setting a surface wave time window, determining the dispersion spectrum of the data to be processed; using the dispersion spectrum to obtain a frequency velocity curve; using the frequency velocity curve and the offset distance of each adjacent channel to perform phase shift processing on each adjacent channel of the specified number of adjacent channels in the data to be processed, and superimposing each channel after the phase shift processing to obtain the surface wave prediction result of each channel; performing phase matching on the surface wave prediction result of each adjacent channel with the corresponding channel in the preprocessed seismic data to obtain the best matching time shift amount, and using the best matching time shift amount to perform time shift processing on the corresponding channel in the surface wave prediction result to obtain the best prediction result of the surface wave of the channel; using the preprocessed seismic data of each channel to subtract the best prediction result of the surface wave of the channel, to obtain the seismic data with suppressed surface wave noise. The invention can solve the problem of false frequency energy in surface wave noise suppression.

[0011] Patent CN115480304A proposes a method for automatic identification and suppression of seismic surface waves, including: step 1, using modified S transform to perform time-frequency analysis on seismic single-shot records of different offsets based on the original seismic single-shot records; step 2, synchronously and automatically identifying the surface wave distribution time, distribution frequency, distribution range, and distribution energy in the time-frequency-offset domain spectrum; step 3, extracting single-band seismic single-shot records in the modified S transform time-frequency spectrum; step 4, performing radial trace transformation on single-band seismic single-shot records; step 5, performing variable frequency dynamic filtering on different single-band seismic single-shot records in the radial trace transformation domain; step 6, performing radial trace inverse transformation on the surface wave noise extracted from all single-band seismic single-shot records. The method for automatic identification and suppression of seismic surface waves fully considers the characteristics of frequency, apparent velocity, dispersion characteristics, and energy change, so as to better extract surface wave noise.

[0012] The above existing technologies are greatly different from the present invention and fail to solve the technical problem we want to solve. For this reason, we have invented a new and improved energy replacement surface wave suppression method. Summary of the invention

[0013] The purpose of the present invention is to provide an improved energy replacement surface roll suppression method which fully considers the two characteristics of surface roll linear component and reference signal time-varying factor and protects the low-frequency information of effective signal to the maximum extent.

[0014] The object of the present invention can be achieved by the following technical measures: an improved energy displacement surface wave suppression method, the improved energy displacement surface wave suppression method comprising:

[0015] Step 1, determine the range of the surface wave frequency band;

[0016] Step 2, dividing the seismic signal into signals within the surface roll bandwidth and signals outside the surface roll bandwidth;

[0017] Step 3, for signals within the frequency range of the surface wave, the surface wave is constrained and extracted from both the frequency factor and the linear factor;

[0018] Step 4, applying time-varying amplitude energy adjustment to the signal outside the surface roll bandwidth to obtain a time-varying reference signal;

[0019] Step 5, respectively obtain the gain operator in each time window;

[0020] Step 6, suppressing the surface wave strong energy to an intensity having the same energy level as the reference signal;

[0021] Step 7, combining the signal within the surface roll bandwidth after suppressing the surface roll with the signal outside the surface roll bandwidth to obtain the final result.

[0022] The purpose of the present invention can also be achieved by the following technical measures:

[0023] In step 1, frequency scanning and spectrum analysis are performed on the single-shot data containing typical surface waves in the surface wave region to determine the frequency band range of the surface waves.

[0024] In step 2, the signal within the surface wave bandwidth is separated from the original single-shot data containing the surface wave by a low-pass filtering method to obtain the single-shot signal data within the surface wave bandwidth. The original single-shot seismic data is subtracted from the separated single-shot signal data within the surface wave bandwidth to obtain the single-shot signal data outside the surface wave bandwidth, thereby realizing the separation of the single-shot data within and outside the surface wave bandwidth.

[0025] In step 3, for the signal within the frequency bandwidth of the surface wave, the linear components within the specified speed range are removed by using RADON transformation according to the linear characteristics of the surface wave, and the surface wave is constrained and extracted from both the frequency factor and the linear factor, so as to better separate the surface wave.

[0026] In step 3, for the signal within the frequency bandwidth of the surface wave, i.e., the low-frequency end signal including the surface wave, the linear component within the specified velocity, i.e., the linear component angle range is removed by using RADON transformation according to the linear characteristics of the surface wave, so as to obtain a seismic single shot after removing the linear component within the specified velocity range by using RADON transformation on the low-frequency end signal including the surface wave.

[0027] In step 4, the signal outside the surface roll bandwidth range, that is, the signal not containing the surface roll signal, is taken as a relatively stable signal within a certain frequency range as a reference signal, and the time-varying amplitude energy adjustment is applied to obtain a time-varying reference signal, so as to adjust the intensity of surface roll frequency band energy suppression; within the same time window, the weaker the energy of the time-varying reference signal, the stronger the surface roll suppression intensity, and the stronger the time-varying reference signal, the weaker the surface roll suppression intensity.

[0028] In step 4, because the seismic wave energy signal weakens with time, it is necessary to take the relatively stable signal within the range of 18-45 Hz as the reference signal outside the surface wave bandwidth, and then apply the time-varying amplitude energy adjustment to obtain the time-varying reference signal, so as to change the intensity of the suppressed surface wave according to the energy change in subsequent operations.

[0029] In step 5, a multi-time window root mean square amplitude gain analysis is performed on each channel along the time axis for the separated surface wave bandwidth signal and the time-varying reference signal after the time-varying amplitude energy is adjusted, and the gain operator in each time window is obtained respectively.

[0030] In step 5, according to the energy difference between the residual surface roll and the effective signal, a multi-time window root mean square amplitude gain analysis is performed on the separated signals within the surface roll bandwidth and the reference signal along the time axis, and the gain operator formula of each seismic channel in each time window is calculated to obtain the reference signal after time-varying energy adjustment.

[0031] In step 5, the gain operator A in the i-th time window i Defined by:

[0032]

[0033] Where B is the root mean square amplitude value expected to be output by the user; N is the number of samples in time window i; X j is the amplitude value of the jth sample point in time window i.

[0034] In step 6, in the corresponding time window, the gain operators of the signal within the surface roll bandwidth and the reference signal are compared, and a larger gain operator is used to perform inverse gain calculation on the signal within the surface roll bandwidth to suppress the strong energy of the surface roll to an intensity with the same energy level as the reference signal.

[0035] In step 7, the signal within the surface wave bandwidth after surface wave suppression is added to the signal outside the surface wave bandwidth, and finally the single-shot seismic data after surface wave suppression is obtained. The single-shot seismic data before and after surface wave suppression are subtracted to obtain the residual after surface wave removal.

[0036] The improved energy replacement surface wave suppression method in the present invention is an energy replacement surface wave suppression method that takes into account the low frequency, strong energy and linear characteristics of the surface wave and has the ability to adjust the denoising intensity in a time-varying manner without losing the low frequency information of the effective signal. On the basis of the conventional energy replacement surface wave suppression method, the present invention uses RADON transformation to remove the linear components of the specified speed range within the surface wave bandwidth according to the linear characteristics of the surface wave; on the basis of the conventional energy replacement surface wave suppression method, the signal outside the surface wave bandwidth is adjusted by time-varying amplitude energy to obtain a time-varying reference signal, thereby realizing the time-varying adjustment of the surface wave suppression intensity.

[0037] The present invention is based on the existing surface wave suppression technology, fully considers the two characteristics of surface wave linear components and reference signal time-varying factors, and maximally protects the low-frequency information of the effective signal to an improved energy replacement method surface wave suppression technology. The improved energy replacement surface wave suppression method in the present invention has two advantages: the first advantage is that for the low-frequency end signal within the frequency range of the surface wave, that is, the low-frequency end signal containing the surface wave, the linear component of the specified velocity range within the surface wave bandwidth is removed by RADON transformation based on the linear characteristics of the surface wave on the basis of the conventional energy replacement surface wave suppression method, thereby maximally protecting the effective information of the low-frequency end of the single-shot seismic data. The second advantage is that for the signal that does not contain the surface wave, on the basis of the conventional energy replacement surface wave suppression method, the signal outside the surface wave bandwidth range is applied with time-varying amplitude energy adjustment to obtain a time-varying reference signal, thereby adjusting the intensity of the surface wave frequency band energy suppression, the amplitude energy of the single-shot seismic data decreases with time, and the reference signal obtained by applying the time-varying amplitude energy adjustment can more accurately suppress the low-energy surface wave noise information, while retaining the effective low-frequency signal to the maximum extent. In the same time window, the surface wave suppression force is proportional to the energy of the reference signal. According to the difference in energy between the residual surface wave and the effective signal, the gain operator of each seismic channel in each time window is calculated respectively. In the corresponding time window, the gain operators of the signal within the surface wave bandwidth and the reference signal are compared, and a larger gain operator is used to perform an inverse gain calculation on the signal within the surface wave bandwidth to suppress the strong energy of the surface wave to an intensity with the same energy level as the reference signal. Finally, the signal within the surface wave bandwidth after the surface wave is suppressed is added to the signal outside the surface wave bandwidth to obtain the single-shot seismic data after the surface wave is suppressed. The method of the present invention utilizes the linear components of the surface wave and the time-varying factor characteristics of the reference signal to suppress the surface wave interference to the greatest extent. Compared with previous methods, the surface wave suppression is more thorough and the results are more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A flowchart of a specific embodiment of the improved energy replacement surface wave suppression method of the present invention;

[0039] Figure 2 It is a schematic diagram of processing a single shot record of a pre-seismic event in a specific embodiment of the present invention;

[0040] Figure 3 It is a schematic diagram of a single seismic shot in the low-frequency surface wave band after low-pass filtering in a specific embodiment of the present invention;

[0041] Figure 4 It is a schematic diagram of a seismic single shot outside the wave frequency band after low-pass filtering in a specific embodiment of the present invention;

[0042] Figure 5 It is a schematic diagram of a seismic single shot after the low-frequency end signal containing the surface wave is transformed by RADON and the linear component within the specified velocity range is removed in a specific embodiment of the present invention;

[0043] Figure 6 It is a schematic diagram of obtaining a linear component within a specified velocity range by subtracting a low-frequency surface wave band seismic shot after low-pass filtering from a low-frequency end signal containing surface waves after RADON transformation in a specific embodiment of the present invention;

[0044] Figure 7 It is a schematic diagram of a reference signal (18-45 Hz) in a specific embodiment of the present invention;

[0045] Figure 8 A schematic diagram of a time-varying reference signal obtained by applying time-varying amplitude energy adjustment to a signal outside the surface roll bandwidth in a specific embodiment of the present invention;

[0046] Fig. 9 It is a schematic diagram of a single shot in which a relatively large gain operator is used to perform inverse gain calculation on a signal within the surface wave bandwidth in a corresponding time window in a specific embodiment of the present invention, so as to suppress the strong energy of the surface wave to an intensity having the same energy level as that of a time-varying reference signal;

[0047] Fig.10 It is a schematic diagram of a seismic single shot after combining the signal within the surface wave bandwidth after suppressing the surface wave with the signal outside the surface wave bandwidth in a specific embodiment of the present invention;

[0048] Fig.11 It is a schematic diagram of using the method to remove the residual of surface roll in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0049] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0050] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations and / or combinations thereof.

[0051] The present invention invents a new surface wave suppression method based on the frequency-constrained energy replacement surface wave suppression method. The method first performs frequency division scanning and spectrum analysis on single-shot data containing surface waves to determine the range of the surface wave frequency band. The seismic signal is divided into a signal within the surface wave frequency bandwidth and a signal outside the surface wave frequency bandwidth. For the signal within the surface wave frequency bandwidth, the linear component within the specified velocity range is removed by RADON transformation according to the linear characteristics of the surface wave, and the surface wave is constrained and extracted from both the frequency factor and the linear factor, so as to better separate the surface wave. Because the seismic wave energy signal weakens with time, it is necessary to take a relatively stable signal within the range of 18-45 Hz as a reference signal for the signal outside the surface wave frequency bandwidth, and then apply time-varying amplitude energy adjustment to obtain a time-varying reference signal, so as to change the intensity of the suppressed surface wave according to the energy change in subsequent operations. Subsequently, the separated signal within the surface wave frequency bandwidth and the time-varying reference signal after the time-varying amplitude energy adjustment are respectively subjected to multi-time window root mean square amplitude gain analysis along the time axis, and the gain operator in each time window is obtained respectively. In the corresponding time window, the gain operators of the signal within the surface wave bandwidth and the time-varying reference signal are compared, and a larger gain operator is used to perform inverse gain calculation on the signal within the surface wave bandwidth, so as to suppress the strong energy of the surface wave to an intensity with the same energy level as the reference signal. The signal within the surface wave bandwidth after the surface wave is suppressed is combined with the signal outside the surface wave bandwidth to obtain the final result. The method of the present invention utilizes the linear component of the surface wave and the time-varying factor characteristics of the seismic wave energy to suppress the surface wave interference to the greatest extent, and the surface wave suppression is more thorough than the previous method, and the result is more reliable.

[0052] The following are several specific embodiments of the present invention.

[0053] Example 1

[0054] In a specific embodiment 1 of the present invention, in view of the various problems existing in the processing of the existing surface roll suppression technology, an improved energy replacement surface roll suppression method is provided based on the existing surface roll suppression technology, which fully considers the characteristics of the surface roll linear component and the time-varying factor of the reference signal. Processing flow ( Figure 1 ) mainly includes the following steps:

[0055] The first step is to analyze the single shot data containing typical surface waves (such as Figure 2 a) Perform frequency scanning and spectrum analysis on the surface wave area to determine the frequency band range of the surface wave (2-10 Hz).

[0056] In the second step, the signal within the surface wave bandwidth is separated from the original single shot data containing the surface wave by low-pass filtering method, and the single shot signal data within the surface wave bandwidth (2-10 Hz) is obtained (such as Figure 3 a), Figure 3a surface wave frequency band 2-10 Hz, subtract the original single shot seismic data from the separated single shot signal data within the surface wave frequency bandwidth to obtain the single shot signal data outside the surface wave frequency bandwidth (such as Figure 4 a), thereby achieving the separation of single shot data within and outside the surface wave bandwidth.

[0057] The third step is to use RADON transformation to remove the linear components within the specified velocity (linear component angle) range according to the linear characteristics of the surface wave, i.e., the low-frequency end signals of the surface wave. Figure 6 a), the low-frequency signal containing the surface wave is transformed by RADON, and the linear component within the specified velocity range is removed to obtain the seismic single shot (such as Figure 5 a).

[0058] The fourth step is to use the signal outside the surface wave bandwidth, that is, the signal not including the surface wave, and take the relatively stable signal within the range of 18-45 Hz as the reference signal (such as Figure 7 a), applying time-varying amplitude energy adjustment to obtain a time-varying reference signal (such as Figure 8 a), so as to adjust the surface roll frequency band energy suppression strength. In the same time window, the weaker the time-varying reference signal energy, the stronger the surface roll suppression strength, and the stronger the time-varying reference signal, the weaker the surface roll suppression strength.

[0059] The fifth step is to perform multi-time window root mean square amplitude gain analysis on the separated signals within the frequency bandwidth of the surface roll and the reference signal along the time axis according to the energy difference between the residual surface roll and the effective signal, and calculate the gain operator formula (1) of each seismic channel in each time window, so as to obtain the reference signal after time-varying energy adjustment;

[0060] The gain operator A in the i-th time window i Defined by:

[0061]

[0062] Where B is the root mean square amplitude value expected to be output by the user; N is the number of samples in time window i; X j is the amplitude value of the jth sample point in time window i.

[0063] The sixth step is to compare the gain operators of the signal within the surface wave bandwidth with the reference signal within the corresponding time window, and use a larger gain operator to perform inverse gain calculation on the signal within the surface wave bandwidth to suppress the surface wave strong energy to the same energy level as the reference signal (such as Fig. 9 a).

[0064] In the seventh step, the signal within the surface wave bandwidth after surface wave suppression is added to the signal outside the surface wave bandwidth, and finally the single shot seismic data after surface wave suppression is obtained (such as Fig.10a). Subtract the single shot seismic data before and after suppressing the surface wave to obtain the residual after removing the surface wave (such as Fig.11 a). It can be seen that the surface wave of the single-shot seismic data is well suppressed, and there is no obvious effective signal in the removed part, achieving improved energy replacement surface wave suppression.

[0065] Example 2

[0066] In a specific embodiment 2 of the present invention, in view of the various problems existing in the processing of the existing surface roll suppression technology, an improved energy replacement surface roll suppression method is provided based on the existing surface roll suppression technology, which fully considers the characteristics of the surface roll linear component and the time-varying factor of the reference signal. Processing flow ( Figure 1 ) mainly includes the following steps:

[0067] The first step is to analyze the single shot data containing typical surface waves (such as Figure 2 b) Perform frequency scanning and spectrum analysis on the surface wave area to determine the frequency band range of the surface wave (3-10 Hz).

[0068] In the second step, the signal within the surface wave bandwidth is separated from the original single shot data containing the surface wave by low-pass filtering method, and the single shot signal data within the surface wave bandwidth (3-10 Hz) is obtained (such as Figure 3 b), Figure 3 b Surface wave frequency band 3-10 Hz, subtract the original single shot seismic data from the separated single shot signal data within the surface wave frequency bandwidth to obtain the single shot signal data outside the surface wave frequency bandwidth (such as Figure 4 b), thereby achieving the separation of single shot data inside and outside the surface wave bandwidth.

[0069] The third step is to use RADON transformation to remove the linear components within the specified velocity (linear component angle) range according to the linear characteristics of the surface wave, i.e., the low-frequency end signals of the surface wave. Figure 6 b), the low-frequency signal containing the surface wave is transformed by RADON, and the linear component within the specified velocity range is removed to obtain the seismic single shot (such as Figure 5 b).

[0070] The fourth step is to use the signal outside the surface wave bandwidth, that is, the signal not including the surface wave, and take the relatively stable signal within the range of 18-45 Hz as the reference signal (such as Figure 7 b), applying time-varying amplitude energy adjustment to obtain a time-varying reference signal (such as Figure 8 b) to adjust the surface roll frequency band energy suppression strength. In the same time window, the weaker the time-varying reference signal energy, the stronger the surface roll suppression strength, and the stronger the time-varying reference signal, the weaker the surface roll suppression strength.

[0071] The fifth step is to perform multi-time window root mean square amplitude gain analysis on the separated signals within the frequency bandwidth of the surface roll and the reference signal along the time axis according to the energy difference between the residual surface roll and the effective signal, and calculate the gain operator formula (1) of each seismic channel in each time window, so as to obtain the reference signal after time-varying energy adjustment;

[0072] Gain operator A in the i-th time window i Defined by:

[0073]

[0074] Where B is the root mean square amplitude value expected to be output by the user; N is the number of samples in time window i; X j is the amplitude value of the jth sample point in time window i.

[0075] The sixth step is to compare the gain operators of the signal within the surface wave bandwidth with the reference signal within the corresponding time window, and use a larger gain operator to perform inverse gain calculation on the signal within the surface wave bandwidth to suppress the surface wave strong energy to the same energy level as the reference signal (such as Fig. 9 b).

[0076] In the seventh step, the signal within the surface wave bandwidth after surface wave suppression is added to the signal outside the surface wave bandwidth, and finally the single shot seismic data after surface wave suppression is obtained (such as Fig.10 b) Subtract the single shot seismic data before and after suppressing the surface wave to obtain the residual after removing the surface wave (such as Fig.11 b). It can be seen that the surface wave of the single-shot seismic data is well suppressed, and there is no obvious effective signal in the removed part, achieving improved energy replacement surface wave suppression.

[0077] Example 3

[0078] In a specific embodiment 3 of the present invention, in view of the various problems existing in the processing of the existing surface roll suppression technology, an improved energy replacement surface roll suppression method is provided based on the existing surface roll suppression technology, which fully considers the characteristics of the surface roll linear component and the time-varying factor of the reference signal. Processing flow ( Figure 1 ) mainly includes the following steps:

[0079] The first step is to analyze the single shot data containing typical surface waves (such as Figure 2 c) Perform frequency scanning and spectrum analysis on the surface wave area to determine the frequency band range of the surface wave (2-11 Hz).

[0080] In the second step, the signal within the surface wave bandwidth is separated from the original single shot data containing the surface wave by low-pass filtering method, and the single shot signal data within the surface wave bandwidth (2-11 Hz) is obtained (such as Figure 3 c), Figure 3c surface wave frequency band 2-11 Hz, subtract the original single shot seismic data from the separated single shot signal data within the surface wave frequency bandwidth to obtain the single shot signal data outside the surface wave frequency bandwidth (such as Figure 4 c) to achieve the separation of single shot data inside and outside the surface wave bandwidth.

[0081] The third step is to use RADON transformation to remove the linear components within the specified velocity (linear component angle) range according to the linear characteristics of the surface wave, i.e., the low-frequency end signals of the surface wave. Figure 6 c) to obtain the seismic single shot after removing the linear components within the specified velocity range by using RADON transformation on the low-frequency end signal containing the surface wave (such as Figure 5 c).

[0082] The fourth step is to use the signal outside the surface wave bandwidth, that is, the signal not including the surface wave, and take the relatively stable signal within the range of 18-45 Hz as the reference signal (such as Figure 7 c), applying time-varying amplitude energy adjustment to obtain a time-varying reference signal (such as Figure 8 c) to adjust the surface roll frequency band energy suppression strength. In the same time window, the weaker the time-varying reference signal energy, the stronger the surface roll suppression strength, and the stronger the time-varying reference signal, the weaker the surface roll suppression strength.

[0083] The fifth step is to perform multi-time window root mean square amplitude gain analysis on the separated signals within the frequency bandwidth of the surface roll and the reference signal along the time axis according to the energy difference between the residual surface roll and the effective signal, and calculate the gain operator formula (1) of each seismic channel in each time window, so as to obtain the reference signal after time-varying energy adjustment;

[0084] The gain operator A in the i-th time window i Defined by:

[0085]

[0086] Where B is the root mean square amplitude value expected to be output by the user; N is the number of samples in time window i; X j is the amplitude value of the jth sample point in time window i.

[0087] The sixth step is to compare the gain operators of the signal within the surface wave bandwidth with the reference signal within the corresponding time window, and use a larger gain operator to perform inverse gain calculation on the signal within the surface wave bandwidth to suppress the surface wave strong energy to the same energy level as the reference signal (such as Fig. 9 c).

[0088] In the seventh step, the signal within the surface wave bandwidth after surface wave suppression is added to the signal outside the surface wave bandwidth, and finally the single shot seismic data after surface wave suppression is obtained (such as Fig.10c) Subtract the single shot seismic data before and after suppressing the surface wave to obtain the residual after removing the surface wave (such as Fig.11 c). It can be seen that the surface wave of the single-shot seismic data is well suppressed, and there is no obvious effective signal in the removed part, achieving improved energy replacement surface wave suppression.

[0089] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0090] Except for the technical features described in the specification, all other technical features are known technologies to those skilled in the art.

Claims

1. An improved energy displacement surface wave suppression method, characterized in that: The improved energy displacement surface wave suppression method comprises: Step 1, determine the range of the surface wave frequency band; Step 2, dividing the seismic signal into signals within the surface roll bandwidth and signals outside the surface roll bandwidth; Step 3, for signals within the frequency range of the surface wave, the surface wave is constrained and extracted from both the frequency factor and the linear factor; Step 4, applying time-varying amplitude energy adjustment to the signal outside the surface roll bandwidth to obtain a time-varying reference signal; Step 5, respectively obtain the gain operator in each time window; Step 6, suppressing the surface wave strong energy to an intensity having the same energy level as the reference signal; Step 7, combining the signal within the surface roll bandwidth after suppressing the surface roll with the signal outside the surface roll bandwidth to obtain the final result.

2. The improved energy displacement surface wave suppression method according to claim 1, characterized in that: In step 1, frequency scanning and spectrum analysis are performed on the single-shot data containing typical surface waves in the surface wave region to determine the frequency band range of the surface waves.

3. The improved energy displacement surface wave suppression method according to claim 1, characterized in that: In step 2, the signal within the surface wave bandwidth is separated from the original single-shot data containing the surface wave by a low-pass filtering method to obtain the single-shot signal data within the surface wave bandwidth. The original single-shot seismic data is subtracted from the separated single-shot signal data within the surface wave bandwidth to obtain the single-shot signal data outside the surface wave bandwidth, thereby realizing the separation of the single-shot data within and outside the surface wave bandwidth.

4. The improved energy displacement surface wave suppression method according to claim 1, characterized in that: In step 3, for the signal within the frequency bandwidth of the surface wave, the linear components within the specified speed range are removed by using RADON transformation according to the linear characteristics of the surface wave, and the surface wave is constrained and extracted from both the frequency factor and the linear factor, so as to better separate the surface wave.

5. The improved energy displacement surface wave suppression method according to claim 4, characterized in that: In step 3, for the signal within the frequency bandwidth of the surface wave, i.e., the low-frequency end signal including the surface wave, the linear component within the specified velocity, i.e., the linear component angle range is removed by using RADON transformation according to the linear characteristics of the surface wave, so as to obtain a seismic single shot after removing the linear component within the specified velocity range by using RADON transformation on the low-frequency end signal including the surface wave.

6. The improved energy displacement surface wave suppression method according to claim 1, characterized in that: In step 4, the signal outside the surface roll bandwidth range, that is, the signal not containing the surface roll signal, is taken as a relatively stable signal within a certain frequency range as a reference signal, and the time-varying amplitude energy adjustment is applied to obtain a time-varying reference signal, so as to adjust the intensity of surface roll frequency band energy suppression; within the same time window, the weaker the energy of the time-varying reference signal, the stronger the surface roll suppression intensity, and the stronger the time-varying reference signal, the weaker the surface roll suppression intensity.

7. The improved energy displacement surface wave suppression method according to claim 6, characterized in that: In step 4, because the seismic wave energy signal weakens with time, it is necessary to take the relatively stable signal within the range of 18-45 Hz as the reference signal outside the surface wave bandwidth, and then apply the time-varying amplitude energy adjustment to obtain the time-varying reference signal, so as to change the intensity of the suppressed surface wave according to the energy change in subsequent operations.

8. The improved energy displacement surface wave suppression method according to claim 1, characterized in that: In step 5, a multi-time window root mean square amplitude gain analysis is performed on each channel along the time axis for the separated surface wave bandwidth signal and the time-varying reference signal after the time-varying amplitude energy is adjusted, and the gain operator in each time window is obtained respectively.

9. The improved energy displacement surface wave suppression method according to claim 8, characterized in that: In step 5, according to the energy difference between the residual surface roll and the effective signal, a multi-time window root mean square amplitude gain analysis is performed on the separated signals within the surface roll bandwidth and the reference signal along the time axis, and the gain operator formula of each seismic channel in each time window is calculated to obtain the reference signal after time-varying energy adjustment.

10. The improved energy displacement surface wave suppression method according to claim 9, characterized in that: In step 5, the gain operator A in the i-th time window i Defined by: Where B is the root mean square amplitude value expected to be output by the user; N is the number of samples in time window i; X j is the amplitude value of the jth sample point in time window i.

11. The improved energy displacement surface wave suppression method according to claim 1, characterized in that: In step 6, in the corresponding time window, the gain operators of the signal within the surface roll bandwidth and the reference signal are compared, and a larger gain operator is used to perform inverse gain calculation on the signal within the surface roll bandwidth to suppress the strong energy of the surface roll to an intensity with the same energy level as the reference signal.

12. The improved energy displacement surface wave suppression method according to claim 1, characterized in that: In step 7, the signal within the surface wave bandwidth after surface wave suppression is added to the signal outside the surface wave bandwidth, and finally the single-shot seismic data after surface wave suppression is obtained. The single-shot seismic data before and after surface wave suppression are subtracted to obtain the residual after surface wave removal.

Images