Improved energy tradeoff surface wave suppression method

Abstract

The application provides an improved energy replacement surface wave suppression method, comprising the following steps: step 1, determining the range of the surface wave frequency band; step 2, dividing the seismic signal into the signal in the surface wave frequency width range and the signal out of the surface wave frequency width range; step 3, for the signal in the surface wave frequency width range, simultaneously restraining the surface wave from the frequency factor and the linear factor and extracting; step 4, for the signal out of the surface wave frequency width range, obtaining the time-varying reference signal by applying the time-varying amplitude energy adjustment; step 5, respectively obtaining the gain operator in each time window; step 6, suppressing the surface wave strong energy to the intensity with the same energy level as the reference signal; and step 7, combining the signal in the surface wave frequency width range after the surface wave is suppressed with the signal out of the surface wave frequency width range to obtain the final result. The improved energy replacement surface wave suppression method utilizes the linear component of the surface wave and the time-varying factor characteristics of the seismic wave energy, suppresses the surface wave interference to the maximum extent, and is more thorough and reliable than the previous surface wave suppression method.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas exploration seismic data processing technology, in particular to an improved energy replacement surface wave suppression method. BACKGROUND

[0002] With the deepening of oil and gas exploration and development, higher requirements are put forward for the signal-to-noise ratio and resolution of seismic data. Seismic surface wave, as a regular interference, is widely present in land seismic data. It has the characteristics of low frequency, strong energy and low speed. The surface wave energy is about ten times the effective signal energy, and the surface wave and the effective signal are intertwined and overlapped together on the shot gather. The surface wave is mainly distributed in the near-offset of the seismic record. The traditional geophone combination receiving mode is conducive to suppressing surface wave. With the popularization and application of single-point high-density seismic technology, surface wave seriously reduces the signal-to-noise ratio of seismic data, and the effective signal in the seismic data is submerged in noise, which seriously affects the quality of seismic data. Surface wave suppression is a crucial step in seismic data processing.

[0003] A large number of surface wave noise suppression methods have been proposed by domestic and foreign scholars in view of the characteristics of low frequency, strong energy and low apparent velocity of surface wave. At present, the surface wave suppression methods mainly include:

[0004] 1. Band-pass filtering method (high-pass filtering) based on frequency difference. According to the frequency distribution range of surface wave 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 band-pass filtering method is relatively simple, but the effective signal below the low cutoff frequency is filtered out, and the low-frequency effective signal is lost. The frequency-space domain coherent noise attenuation method is performed on the data in the surface wave frequency range. Based on the least square error criterion, the surface wave is estimated at each frequency. The surface wave occurrence area is limited by the velocity and frequency parameters, and the seismic signal outside the range has little effect.

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

[0006] There are two main shortcomings in the current surface wave suppression method. On the one hand, the surface wave recognition is not accurate, and the data without surface wave is also processed, which destroys the effective signal, or the data containing surface wave is not included 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 still has a certain degree of influence on subsequent data interpretation and reservoir inversion work.

[0007] With the deepening of oil and gas exploration, the importance of low-frequency information in seismic data processing is increasingly recognized. Low-frequency information has important significance in high-steep structure imaging, extended frequency band, and pre-stack inversion. It is increasingly important to protect low-frequency information in data processing.

[0008] Patent CN104345341A proposes a regional constraint-based frequency band energy seismic surface wave processing method (regional filtering), which uses wavelet transform to process seismic data in different frequency bands, calculates the average amplitude value in the time window in different time windows and different frequency bands, sets the amplitude threshold value by using the cumulative superposition statistical analysis method, replaces the original amplitude value with the new amplitude value calculated by the suppression factor formula, and realizes surface wave suppression.

[0009] Patent CN105093282B proposes an energy replacement method based on frequency constraint. This method removes surface waves, and the essence is to rely on the differences between surface waves and effective signals in frequency and energy. Frequency scanning and spectral analysis are performed on the data containing surface waves to determine the frequency band range of surface waves. Within the surface wave frequency band range, according to the differences between surface waves and effective signals in energy, the multi-time window root mean square amplitude gain analysis is performed on the data in and out of the separated surface wave frequency range along the time axis, and the gain operator in each time window is obtained. In a certain time window containing surface waves, by using the gain operator replacement method, the larger gain operator is used to calculate the anti-gain of the signal in the surface wave frequency range, and the surface wave energy is suppressed to the same energy level as the effective signal, realizing the suppression of surface waves.

[0010] Patent CN112379427A proposes a surface wave noise suppression method and device, wherein the method comprises: setting a surface wave time window, determining the frequency dispersion spectrum of the data to be processed; obtaining the frequency-velocity curve using the frequency dispersion spectrum; for each specified number of adjacent channels in the data to be processed, using the frequency-velocity curve and the offset distance of each channel of the adjacent channels to perform phase shift processing on each channel of the adjacent channels, respectively, and superimposing each channel after phase shift processing to obtain the surface wave prediction result of each channel; phase matching the surface wave prediction result of each channel of the adjacent channels with the corresponding channel of the preprocessed seismic data to obtain the best time shift amount, and using the best time shift amount to perform time shift processing on the corresponding channel of the surface wave prediction result to obtain the best prediction result of the surface wave of the channel; subtracting the best prediction result of the surface wave of the channel from the preprocessed seismic data of each channel to obtain seismic data with surface wave noise suppressed. 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, comprising: step 1, using modified S transform to perform time-frequency analysis on seismic single shot records at different offsets according to original seismic single shot records; step 2, simultaneously and automatically identifying the distribution time, distribution frequency, distribution range and distribution energy of surface waves in the time-frequency-offset domain spectrum; step 3, extracting single-frequency seismic single shot records in the modified S transform time-frequency spectrum; step 4, performing radial trace transformation on the single-frequency seismic single shot records; step 5, performing variable frequency dynamic filtering on different single-frequency 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-frequency seismic single shot records. The method fully considers the characteristics of frequency, apparent velocity, dispersion characteristics and energy change, so as to better extract surface wave noise.

[0012] The above prior art is quite different from the present application and cannot solve the technical problems we want to solve, so we have invented a new improved energy replacement surface wave suppression method. SUMMARY

[0013] The purpose of the present application is to provide an improved energy replacement surface wave suppression method of improved energy replacement surface wave suppression technology which fully considers the characteristics of surface wave linear component and reference signal time-varying factor, and maximally protects the low-frequency information of effective signals.

[0014] The purpose of the present application can be achieved by the following technical measures: the improved energy replacement surface wave suppression method comprises:

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

[0016] Step 2, the seismic signal is divided into signals in the surface wave frequency bandwidth range and signals out of the surface wave frequency bandwidth range;

[0017] Step 3, for the signals in the surface wave frequency bandwidth range, the surface wave is simultaneously constrained from the frequency factor and the linear factor and extracted;

[0018] Step 4, for the signals out of the surface wave frequency bandwidth range, a time-varying reference signal is obtained by applying time-varying amplitude energy adjustment;

[0019] Step 5, gain operators in each time window are respectively obtained;

[0020] Step 6, the surface wave strong energy is suppressed to the intensity with the same energy level as the reference signal;

[0021] Step 7, the signals in the surface wave frequency bandwidth range after the surface wave is suppressed and the signals out of the surface wave frequency bandwidth range are combined to obtain the final result.

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

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

[0024] In step 2, the signals in the surface wave frequency bandwidth range are separated from the original single-shot data containing surface waves by a low-pass filtering method to obtain single-shot signal data in the surface wave frequency bandwidth range, the original single-shot seismic data is subtracted from the separated single-shot signal data in the surface wave frequency bandwidth range to obtain single-shot signal data out of the surface wave frequency bandwidth range, so that the single-shot data in and out of the surface wave frequency bandwidth range is separated.

[0025] In step 3, for the signals in the surface wave frequency bandwidth range, the linear component in the specified speed range is removed by using RADON transformation according to the linear characteristics of the surface wave, the surface wave is simultaneously constrained from the frequency factor and the linear factor and extracted, so that the surface wave is better separated.

[0026] In step 3, for the signals in the surface wave frequency bandwidth range, i.e. the low-frequency end signals containing surface waves, the linear component in the specified speed range is removed by using RADON transformation according to the linear characteristics of the surface wave, so that the seismic single-shot containing the low-frequency end signals containing the surface waves is obtained after the linear component in the specified speed range is removed by using RADON transformation.

[0027] In step 4, for the signals out of the surface wave frequency bandwidth range, i.e. the signals not containing surface wave signals, the signals in a certain frequency range are taken as reference signals, a time-varying reference signal is obtained by applying time-varying amplitude energy adjustment, and the surface wave band energy suppression strength is adjusted; in the same time window, the weaker the time-varying reference signal energy is, the stronger the surface wave suppression strength is, and the stronger the time-varying reference signal is, the weaker the surface wave suppression strength is.

[0028] In step 4, because the seismic wave energy signal decreases with time, a more stable signal in the 18-45hz range is needed as a reference signal outside the surface wave frequency bandwidth range, and time-varying amplitude energy adjustment is applied to obtain a time-varying reference signal, so that the strength of the surface wave suppression is changed according to the energy change in the subsequent operation.

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

[0030] In step 5, according to the difference between the residual surface wave and the effective signal in terms of energy, the multi-time window root mean square amplitude gain analysis is performed on the separated surface wave frequency bandwidth range signal and the reference signal along the time axis, respectively, and the gain operator formula of each seismic trace in each time window is calculated, that is, the time-varying energy adjusted reference signal is obtained.

[0031] In step 5, the gain operator A i is defined by the following formula:

[0032]

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

[0034] In step 6, in the corresponding time window, the gain operators of the surface wave frequency bandwidth range signal and the reference signal are compared, and the larger gain operator is used to calculate the anti-gain of the surface wave frequency bandwidth range signal, so that the strong energy of the surface wave is suppressed to the same energy level as the reference signal.

[0035] In step 7, the surface wave frequency bandwidth range signal after suppressing the surface wave is added to the surface wave frequency bandwidth range signal, and finally the single shot seismic data after suppressing the surface wave is obtained. The single shot seismic data before and after suppressing the surface wave are subtracted to obtain the residual after removing the surface wave.

[0036] The improved energy replacement surface wave suppression method in the application is an energy replacement surface wave suppression method that considers the low frequency, strong energy and linear characteristics of the surface wave, has the ability to adjust the denoising strength, and almost does not lose the low frequency information of the effective signal. Based on the conventional energy replacement surface wave suppression method, the linear component in the specified velocity range within the surface wave frequency bandwidth range is removed by using RADON transformation according to the linear characteristics of the surface wave; and based on the conventional energy replacement surface wave suppression method, time-varying amplitude energy adjustment is applied to the signal outside the surface wave frequency bandwidth range to obtain a time-varying reference signal, so that the time-varying adjustment of the surface wave suppression strength is realized.

[0037] The application is based on the existing surface wave suppression technology, fully considers the linear component of the surface wave and the time-varying factor of the reference signal, and maximally protects the low-frequency information of the effective signal by using the improved energy replacement surface wave suppression technology. The improved energy replacement surface wave suppression method has two advantages: the first advantage is that, on the basis of the conventional energy replacement surface wave suppression method, the low-frequency end signal containing the surface wave frequency range, i.e., the low-frequency end signal containing the surface wave, is removed from the linear component in the specified speed range by using the RADON transform according to the linear characteristics of the surface wave, so as to maximally protect the effective information of the low-frequency end of the single-shot seismic data. The second advantage is that, on the basis of the conventional energy replacement surface wave suppression method, the signal outside the surface wave frequency range is adjusted by using the time-varying amplitude energy to obtain the time-varying reference signal, so as to adjust the energy suppression strength of the surface wave frequency band, the amplitude energy of the single-shot seismic data is weakened with the increase of time, the reference signal obtained by using the time-varying amplitude energy adjustment can more accurately suppress the low-energy surface wave noise information, and the effective low-frequency signal is maximally reserved. In the same time window, the surface wave suppression strength 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 trace in each time window is calculated. In the corresponding time window, the gain operator of the signal in the surface wave frequency range is compared with that of the reference signal, the larger gain operator is used to calculate the anti-gain of the signal in the surface wave frequency range, and the strong energy of the surface wave is suppressed to the same energy level as the reference signal. Finally, the signal in the surface wave frequency range after the surface wave suppression is added to the signal outside the surface wave frequency range, to obtain the single-shot seismic data after the surface wave suppression. The method uses the linear component of the surface wave and the time-varying factor of the reference signal, maximally suppresses the surface wave interference, and is more thorough than the previous method, and the result is more reliable. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The flow chart of the specific embodiment of the improved energy replacement surface wave suppression method of the application;

[0039] Figure 2 The schematic diagram of the seismic single-shot record before processing in the specific embodiment of the application;

[0040] Figure 3 The schematic diagram of the seismic single-shot in the low-frequency surface wave frequency band after low-pass filtering in the specific embodiment of the application;

[0041] Figure 4 The schematic diagram of the seismic single-shot outside the surface wave frequency band after low-pass filtering in the specific embodiment of the application;

[0042] Figure 5 The seismic single-shot schematic diagram after removing the linear component in the specified speed range by using the RADON transform on the low-frequency end signal containing the surface wave in the specific embodiment of the application;

[0043] Figure 6 Figure 1 is a schematic diagram of the linear component in a specified velocity range obtained by subtracting the low-frequency surface wave frequency band seismic single shot after low-pass filtering from the seismic single shot after Radon transform of the low-frequency end signal containing surface waves in a specific embodiment of the present application;

[0044] Figure 7 Figure 2 is a schematic diagram of a reference signal (18-45 Hz) in a specific embodiment of the present application;

[0045] Figure 8 Figure 3 is a schematic diagram of a time-varying reference signal obtained by applying time-varying amplitude energy adjustment to the signal outside the surface wave frequency width in a specific embodiment of the present application;

[0046] Figure 9 Figure 4 is a schematic diagram of a single shot in which the surface wave energy is suppressed to the same energy level as the time-varying reference signal by using a larger gain operator to calculate the inverse gain of the signal within the surface wave frequency width in a corresponding time window in a specific embodiment of the present application;

[0047] Figure 10 Figure 5 is a schematic diagram of a seismic single shot obtained by merging the surface wave frequency width signal after suppressing the surface wave with the signal outside the surface wave frequency width in a specific embodiment of the present application;

[0048] Figure 11 Figure 6 is a schematic diagram of the residual obtained by using the method to remove the surface wave in a specific embodiment of the present application. DETAILED DESCRIPTION

[0049] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0050] It should be noted that the terms used herein are only intended to describe specific embodiments and are not intended to limit exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of the features, steps, operations and / or combinations thereof.

[0051] The application is a new surface wave suppression method based on the frequency-constrained energy replacement surface wave suppression method. The method first performs frequency scanning and spectrum analysis on single-shot data containing surface waves to determine the range of surface wave frequency band. The seismic signals are divided into signals within the surface wave frequency range and signals outside the surface wave frequency range. For the signals within the surface wave frequency range, the linear components within the specified speed range are removed by using RADON transform according to the linear characteristics of surface waves, and the surface waves are extracted from the frequency factor and the linear factor, so that the surface waves are better separated. Because the seismic wave energy signal decreases with time, the signals within the 18-45hz range which are more stable are taken as reference signals outside the surface wave frequency range, and time-varying reference signals are obtained by using time-varying amplitude energy adjustment, so that the strength of the suppressed surface waves is changed according to the energy change in the subsequent operation. Then, the separated signals within the surface wave frequency range and the time-varying reference signals after time-varying amplitude energy adjustment are analyzed along the time axis by using multi-time window root mean square amplitude gain analysis, and the gain operators in each time window are calculated. In the corresponding time window, the gain operators of the signals within the surface wave frequency range and the time-varying reference signals are compared, and the larger gain operator is used to calculate the anti-gain of the signals within the surface wave frequency range, so that the strong energy of the surface waves is suppressed to the same energy level as the reference signal. The signals within the surface wave frequency range after suppressing the surface waves are combined with the signals outside the surface wave frequency range to obtain the final result. The method of the application uses the linear components of surface waves and the time-varying factor characteristics of seismic wave energy, and suppresses the surface wave interference to the greatest extent, which is more thorough than the previous method, and the result is more reliable.

[0052] The following are several specific embodiments of the application

[0053] Embodiment 1

[0054] In a specific embodiment 1 of the application, in view of the various problems existing in the processing process of the existing surface wave suppression technology, an improved energy replacement surface wave suppression method is provided based on the existing surface wave suppression technology, which fully considers the linear components of surface waves and the time-varying factor characteristics of reference signals. The processing flow Figure 1 ) mainly includes the following steps:

[0055] Firstly, the single-shot data containing typical surface waves (such as Figure 2 a) Frequency scanning and spectrum analysis are performed on the surface wave region to determine the frequency band range of the surface wave (2-10hz).

[0056] Secondly, the signals within the surface wave frequency range are separated from the original single-shot data containing surface waves by using low-pass filtering method to obtain the single-shot signal data within the surface wave frequency range (2-10hz) (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 in the surface wave frequency band, to obtain the single shot signal data outside the surface wave frequency band (such as Figure 4 a), so as to realize the separation of the single shot data in and outside the surface wave frequency band.

[0057] Thirdly, according to the linear characteristics of the surface wave, the RADON transform is used to remove the linear components in the specified speed range (linear component angle) from the signal in the surface wave frequency band, i.e. the low frequency end signal containing the surface wave (such as Figure 6 a), to obtain the seismic single shot after the low frequency end signal containing the surface wave is removed from the linear components in the specified speed range by the RADON transform (such as Figure 5 a).

[0058] Fourthly, the signal outside the surface wave frequency band, i.e. the signal not containing the surface wave, is taken as the reference signal in the relatively stable 18-45 Hz range (such as Figure 7 a), and the time-varying reference signal is obtained by applying the time-varying amplitude energy adjustment (such as Figure 8 a), so as to adjust the energy suppression strength of the surface wave. In the same time window, the weaker the energy of the time-varying reference signal, the stronger the surface wave suppression strength, and the stronger the time-varying reference signal, the weaker the surface wave suppression strength.

[0059] Fifthly, according to the energy difference between the residual surface wave and the effective signal, the multi-time window root mean square amplitude gain analysis is performed on the separated signal in the surface wave frequency band and the reference signal along the time axis, respectively, to calculate the gain operator formula (1) of each seismic trace in each time window, so as to obtain the time-varying energy adjusted reference signal.

[0060] The gain operator A in the i-th time window is defined by the following formula: i

[0061]

[0062] In the formula, B is the root mean square amplitude value expected to be output by the user; N is the number of sample points in the time window i; X j is the amplitude value of the j-th sample point in the time window i.

[0063] Sixthly, in the corresponding time window, the gain operators of the signal in the surface wave frequency band and the reference signal are compared, the larger gain operator is used to calculate the anti-gain of the signal in the surface wave frequency band, and the strong energy of the surface wave is suppressed to the same energy level as the reference signal (such as Figure 9 a).

[0064] Seventhly, the signal in the surface wave frequency band after the surface wave is suppressed is added to the signal outside the surface wave frequency band, to obtain the single shot seismic data after the surface wave is suppressed (such as Figure 10 ​a) Subtract the single shot seismic data after the surface wave is suppressed, and get the residual after the surface wave is removed (such as Figure 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 after removing part of it, and improved energy replacement surface wave suppression is achieved.

[0065] Embodiment 2

[0066] In a specific embodiment 2 of the application, in view of various problems existing in the processing process of the existing surface wave suppression technology, an improved energy replacement surface wave suppression method is provided based on the existing surface wave suppression technology, fully considering the linear component of the surface wave and the time-varying factor of the reference signal. The processing flowchart Figure 1 ) mainly includes the following steps:

[0067] Firstly, the single shot data containing typical surface waves (such as Figure 2 b) The frequency scanning and spectrum analysis are performed on the surface wave area to determine the frequency band range (3-10hz) of the surface wave.

[0068] Secondly, the signal in the surface wave frequency range is separated from the original single shot data containing surface waves by a low-pass filtering method, and the single shot signal data in the surface wave frequency range (3-10hz) is obtained (such as Figure 3 b), Figure 3 b) The original single shot seismic data and the single shot signal data in the surface wave frequency range are subtracted, and the single shot signal data outside the surface wave frequency range is obtained (such as Figure 4 b), so as to realize the separation of the single shot data inside and outside the surface wave frequency range.

[0069] Thirdly, according to the linear characteristic of the surface wave, the RADON transform is used to remove the linear component in the specified speed range (such as Figure 6 b) The single shot seismic data after the low-frequency end signal containing the surface wave is removed by the RADON transform is obtained (such as Figure 5 b).

[0070] Fourthly, the signal outside the surface wave frequency range, that is, the signal not containing the surface wave, is taken as the reference signal in the relatively stable 18-45hz range (such as Figure 7 b), and the time-varying reference signal is obtained by applying the time-varying amplitude energy adjustment (such as Figure 8 b), so as to adjust the surface wave band energy suppression strength. In the same time window, the weaker the energy of the time-varying reference signal, the stronger the surface wave suppression strength, and the stronger the time-varying reference signal, the weaker the surface wave suppression strength.

[0071] Step 5, according to the difference between the residual surface wave and the effective signal in terms of energy, the separated signal in the surface wave frequency range and the reference signal along the time axis are respectively analyzed by multi-time window root mean square amplitude gain analysis, and the gain operator formula (1) of each seismic trace in each time window is calculated, that is, the time-varying energy adjusted reference signal is obtained;

[0072] Gain operator A in the i-th time window i defined by the following formula:

[0073]

[0074] In the formula, B is the root mean square amplitude value expected to be output by the user; N is the number of samples in the time window i; X j is the amplitude value of the j-th sample in the time window i.

[0075] Step 6, in the corresponding time window, the gain operators of the signal in the surface wave frequency range and the reference signal are compared, the larger gain operator is used to calculate the anti-gain of the signal in the surface wave frequency range, and the strong energy of the surface wave is suppressed to the same energy level as the reference signal (such as Figure 9 b).

[0076] Step 7, finally, the signal in the surface wave frequency range after suppressing the surface wave is added to the signal outside the surface wave frequency range, and finally the single-shot seismic data after suppressing the surface wave is obtained (such as Figure 10 b). The single-shot seismic data before and after suppressing the surface wave are subtracted, and the residual after removing the surface wave is obtained (such as Figure 11 b). It can be seen that the surface wave of the single-shot seismic data is well suppressed, and part of the effective signal is removed without obvious effective signal, realizing the improved energy replacement surface wave suppression.

[0077] Example 3

[0078] In a specific embodiment 3 of the application, in view of various problems existing in the processing process of the existing surface wave suppression technology, an improved energy replacement surface wave suppression method is provided based on the existing surface wave suppression technology, fully considering the two aspects of the characteristics of the surface wave linear component and the time-varying factor of the reference signal. The processing flow Figure 1 ) mainly includes the following steps:

[0079] Step 1, single-shot data containing typical surface waves (such as Figure 2 c) is subjected to frequency scanning and spectrum analysis in the surface wave region to determine the frequency band range (2-11hz) of the surface wave.

[0080] Step 2, the signal in the surface wave frequency range is separated from the original single-shot data containing surface waves by a low-pass filtering method, and the single-shot signal data in the surface wave frequency range (2-11hz) is obtained (such as Figure 3 c), Figure 3c) and the original single shot seismic data to obtain the single shot signal data outside the surface wave frequency range (such as Figure 4 c) so as to realize the separation of the single shot data within and outside the surface wave frequency range.

[0081] The third step is to remove the linear component within the specified velocity range from the low frequency end signal containing the surface wave by using the RADON transform according to the linear characteristics of the surface wave (such as Figure 6 c) to obtain the seismic single shot after removing the linear component within the specified velocity range from the low frequency end signal containing the surface wave by using the RADON transform (such as Figure 5 c).

[0082] The fourth step is to take the relatively stable signal within the range of 18-45 Hz as the reference signal (such as Figure 7 c) and apply the time-varying amplitude energy adjustment to obtain the time-varying reference signal (such as Figure 8 c) to adjust the energy suppression strength of the surface wave band. In the same time window, the weaker the energy of the time-varying reference signal, the stronger the surface wave suppression strength, and the stronger the time-varying reference signal, the weaker the surface wave suppression strength.

[0083] The fifth step is to perform multi-time window root mean square amplitude gain analysis on the separated signal within the surface wave frequency range and the reference signal along the time axis respectively according to the energy difference between the residual surface wave and the effective signal, and calculate the gain operator formula (1) of each seismic trace in each time window to obtain the time-varying energy adjusted reference signal.

[0084] The gain operator A in the i-th time window i which is defined by the following formula:

[0085]

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

[0087] The sixth step is to compare the gain operators of the signal within the surface wave frequency range and the reference signal in the corresponding time window, and perform anti-gain calculation on the signal within the surface wave frequency range by using the larger gain operator to suppress the strong energy of the surface wave to the same energy level as the reference signal (such as Figure 9 c).

[0088] The seventh step is to add the signal within the surface wave frequency range after suppressing the surface wave to the signal outside the surface wave frequency range to finally obtain the single shot seismic data after suppressing the surface wave (such as Figure 10c). Subtract the single shot seismic data after suppressing the surface wave from the single shot seismic data before suppressing the surface wave to obtain the residual after removing the surface wave (such as Figure 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 after removing part of it, and improved energy replacement surface wave suppression is achieved.

[0089] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some of the technical features. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

[0090] In addition to the technical features described in the specification, they are known to those skilled in the art.

Claims

1. An improved method of energy replacement surface wave suppression, characterized by, The improved energy replacement surface wave suppression method comprises: Step 1, determining the range of the surface wave frequency band; Step 2, dividing the seismic signal into signals within the surface wave frequency range and signals outside the surface wave frequency range; Step 3, for the signals within the surface wave frequency range, simultaneously constraining and extracting the surface wave from the frequency factor and the linear factor; Step 4, for the signals outside the surface wave frequency range, obtaining the time-varying reference signal by applying time-varying amplitude energy adjustment; Step 5, respectively calculating the gain operator in each time window; Step 6, suppressing the strong energy of the surface wave to the same energy level as the reference signal; Step 7, combining the signals within the surface wave frequency range after suppressing the surface wave with the signals outside the surface wave frequency range to obtain the final result.

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

3. The improved energy replacement surface wave suppression method of claim 1, wherein, In step 2, the signals within the surface wave frequency range are separated from the original single-shot data containing surface waves by low-pass filtering method to obtain single-shot signal data within the surface wave frequency range, and the original single-shot seismic data is subtracted from the separated single-shot signal data within the surface wave frequency range to obtain single-shot signal data outside the surface wave frequency range, thereby realizing the separation of single-shot data within and outside the surface wave frequency range.

4. The improved method of energy replacement surface wave suppression of claim 1, wherein, In step 3, for the signals within the surface wave frequency range, the linear component within the specified velocity range is removed by RADON transform according to the linear characteristics of the surface wave, and the surface wave is simultaneously constrained and extracted from the frequency factor and the linear factor, thereby better separating the surface wave.

5. The improved energy replacement surface wave suppression method of claim 4, wherein, In step 3, for the signals within the surface wave frequency range, i.e. the low-frequency end signals containing surface waves, the linear component within the specified velocity range is removed by RADON transform according to the linear characteristics of the surface wave, thereby obtaining the seismic single-shot after removing the linear component within the specified velocity range.

6. The improved energy replacement surface wave suppression method of claim 1, wherein, In step 4, for the signals outside the surface wave frequency range, i.e. the signals not containing surface wave signals, a certain frequency range with relatively stable signals is taken as a reference signal, and a time-varying reference signal is obtained by applying time-varying amplitude energy adjustment, so as to adjust the surface wave band energy suppression strength; in the same time window, the weaker the energy of the time-varying reference signal, the stronger the surface wave suppression strength, and the stronger the time-varying reference signal, the weaker the surface wave suppression strength.

7. The improved energy replacement surface wave suppression method of claim 6, wherein, In step 4, because the seismic wave energy signal decreases with time, a certain frequency range with relatively stable signals is taken as a reference signal, and a time-varying reference signal is obtained by applying time-varying amplitude energy adjustment, so as to change the strength of suppressing the surface wave according to the energy change in the subsequent operation.

8. The improved energy replacement surface wave suppression method of claim 1, wherein, In step 5, the multi-time window root mean square amplitude gain analysis is performed on the separated signals within the surface wave frequency range and the time-varying reference signal after time-varying amplitude energy adjustment along the time axis, and the gain operator in each time window is calculated.

9. The improved energy replacement surface wave suppression method of claim 8, wherein, In step 5, according to the difference between the residual surface wave and the effective signal in energy, the multi-time window root mean square amplitude gain analysis is performed on the separated signals within the surface wave frequency range and the reference signal along the time axis, and the gain operator formula of each seismic trace in each time window is calculated, i.e. the time-varying energy adjusted reference signal.

10. The improved energy replacement surface wave suppression method of claim 9, wherein, At step 5, the gain operator A in the i-th time window i is defined by: where B is the user-specified root-mean-square amplitude value expected to be output; N is the number of samples in the time window i; X j is the amplitude value of the jth sample in the time window i.

11. The improved method of energy replacement surface wave suppression of claim 1, wherein, In step 6, in the corresponding time window, the gain operator of the signal in the surface wave frequency bandwidth range and the reference signal is compared, the signal in the surface wave frequency bandwidth range is calculated by using the larger gain operator, and the surface wave strong energy is suppressed to the same energy level as the reference signal.

12. The improved energy replacement surface wave suppression method according to claim 1, wherein, In step 7, the signal in the surface wave frequency bandwidth after the surface wave is suppressed is added to the signal outside the surface wave frequency bandwidth, and finally the single-shot seismic data after the surface wave is suppressed is obtained. The single-shot seismic data before and after the surface wave is suppressed are subtracted to obtain the residual after the surface wave is removed.

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