A method, device and storage medium for identifying and suppressing single-frequency interference of seismic data

Abstract

This invention provides a method, device, and storage medium for identifying and suppressing single-frequency interference in seismic data, relating to the field of digital seismic data processing. The method includes: defining an observation system; acquiring seismic data; extracting seismic gathers and exporting their signal data; mirroring and normalizing the seismic gather signal data to obtain identification signal data for the seismic gathers; calculating the average cross-correlation coefficient of the seismic gathers based on the identification signal data to determine whether the seismic gathers contain single-frequency interference; when single-frequency interference is determined to be present, calculating the high-precision single-frequency interference frequency of each seismic trace in the seismic gather; and calculating the actual single-frequency interference of the seismic gather based on the high-precision single-frequency interference frequency of each seismic trace, thereby suppressing the single-frequency interference. The device and storage medium are used to implement the method. The beneficial effects of this invention are: it conforms to the characteristics of seismic data, better identifies single-frequency interference, and avoids the impact caused by near-offset energy anomalies in seismic data.

Description

Technical Field

[0001] This invention relates to the field of digital processing of seismic data, and in particular to a method, device, and storage medium for identifying and suppressing single-frequency interference in seismic data. Background Technology

[0002] In seismic data processing, strong-energy single-frequency interference noise is frequently encountered. Previous single-frequency interference identification methods typically operate in the frequency domain, searching for abnormal "convex" values ​​in the frequency domain of each single-frequency interference trace (Yuan et al., 2021). However, this is difficult to identify when the amplitude of the interference frequency domain is relatively weak compared to the overall seismic gather frequency. Chen Keyang et al. proposed calculating the cross-correlation normalization coefficient in the time domain to determine whether a seismic gather contains single-frequency interference (Chen Keyang et al., 2014). This method assumes the presence of single-frequency interference in the seismic gather, uses the least squares method to fit the amplitude, frequency, and phase of the single-frequency interference signal, and then performs cross-correlation between the fitted single-frequency interference signal and the seismic gather to obtain a normalization coefficient. This coefficient is then used to determine the presence of single-frequency interference. However, this algorithm is cumbersome and not suitable for the efficiency requirements of processing massive amounts of seismic data. Current literature on single-frequency interference (SFM) suppression does not discuss the effectiveness of near-path seismic data in suppressing SFM. Some papers propose using deep seismic data to estimate the SFM frequency and amplitude. However, since SFM is determined by three parameters—frequency, amplitude, and initial phase at the sampling point—the estimated SFM signal from deep data differs from the actual SFM signal's initial phase, thus failing to effectively suppress the interference. Other papers suggest applying automatic gain control (AGaS) to seismic data to equalize energy; however, after AGaS, the near-path SFM is no longer a complete harmonic interference, and therefore, it still cannot be suppressed. Summary of the Invention

[0003] The purpose of this invention is to address the difficulty of suppressing single-frequency interference in seismic near-channel data. This invention provides a method, device, and storage medium for identifying and suppressing single-frequency interference in seismic data. The method for identifying and suppressing single-frequency interference in seismic data mainly includes the following steps:

[0004] S1. Define the observation system, acquire seismic data, extract seismic gathers and export their signal data;

[0005] S2. Mirror and flip the seismic gather signal data and normalize it to obtain the seismic gather identification signal data.

[0006] S3. Calculate the average cross-correlation coefficient of the seismic gathers based on the seismic gather signal data used for identification, and determine whether the seismic gathers contain single-frequency interference;

[0007] S4. When it is determined that the seismic gather contains single-frequency interference, calculate the high-precision single-frequency interference frequency of each seismic trace in the seismic gather.

[0008] S5. Calculate the actual single-frequency interference of the seismic traces based on the high-precision single-frequency interference frequency of each seismic trace in the seismic trace set, and then suppress the single-frequency interference.

[0009] Furthermore, the seismic data is single-shot recorded data, received by multiple receivers.

[0010] Furthermore, a seismic gather is a collection of seismic traces extracted from common receiver points after suppressing anomalous amplitudes in seismic data. These traces are arranged in ascending order of offset. The data in the seismic gather is defined by amplitude data prior to the earthquake's first arrival time. The derived form of the seismic gather is as follows:

[0011]

[0012] In the formula, s(n) is a function of i and j, representing the signal data of the nth seismic gather; n is the seismic gather number; i is the number of sample points acquired below the first arrival time of the seismic gather; and j is the number of seismic traces in the nth seismic gather. ij The amplitude is the amplitude below the first arrival time of the earthquake in the seismic trace.

[0013] Furthermore, step S2 specifically includes:

[0014] S21. The signal data of the seismic gather is subjected to a matrix column vector element mirroring process, as shown in the following mathematical expression:

[0015]

[0016] In the formula, srev(n) is a function of i and j, representing the mirror flipping result of the nth seismic gather signal data;

[0017] S22. Normalize the mirror-flipped seismic gather signal data to obtain the seismic gather signal data. The mathematical expression is as follows:

[0018] srevnorm(n)=srevnorm(i,j)=srev(n) / max(srev)

[0019] In the formula, srevnorm(n) is a function of i and j, representing the identification signal data of the nth seismic gather.

[0020] Furthermore, the single-frequency interference is represented by a discrete mathematical model, and the cosine model is as follows:

[0021] y=Ccos(2πfiΔt+φ)=Acos(2πfiΔt)+Bsin(2πfiΔt)

[0022] In the formula, y represents the single-frequency interference; C represents the actual amplitude of the single-frequency interference; A represents the amplitude of the cosine function after decomposing the single-frequency interference; and B represents the amplitude of the sine function after decomposing the single-frequency interference. There is a corresponding relationship among the three. φ is the phase of the single-frequency interference; f is the frequency of the single-frequency interference; Δt is the sampling time interval.

[0023] Furthermore, whether a seismic gather contains single-frequency interference is determined by the average cross-correlation coefficient of the seismic gather. When the average cross-correlation coefficient of the seismic gather exceeds a critical value, then all seismic gathers contain single-frequency interference.

[0024] The average cross-correlation coefficient of the seismic gather is the weighted average of the cross-correlation coefficients of the seismic traces, and the calculation formula is as follows:

[0025]

[0026] In the formula, Rj represents the average cross-correlation coefficient of the nth seismic gather; R(j) represents the cross-correlation coefficient of the jth seismic gather, calculated using the following formula:

[0027]

[0028] In the formula, Rc(j) is the cosine cross-correlation coefficient of the j-th seismic trace in the seismic trace set, and Rs(j) is the sine cross-correlation coefficient of the j-th seismic trace in the seismic trace set. The calculation formula is as follows:

[0029]

[0030] The further steps for calculating the high-precision single-frequency interference frequency are as follows:

[0031] The initial frequency of each seismic trace is obtained by frequency spectrum analysis of the seismic trace collection. Based on the relationship between frequency and amplitude in single-frequency interference, the accuracy is gradually increased on the basis of the initial single-frequency interference frequency to obtain the high-precision single-frequency interference frequency of each seismic trace in the seismic trace collection.

[0032] The functional expression for the relationship between frequency and amplitude in single-frequency interference is as follows:

[0033]

[0034]

[0035] according to The frequency that makes the amplitude C(j) reach its maximum value in the preset frequency accuracy level is taken as the high-precision single-frequency interference frequency of the j-th seismic trace in the seismic trace set.

[0036] Furthermore, step S5 specifically includes:

[0037] S51. Calculate the corresponding amplitude based on the high-precision single-frequency interference frequency of each seismic trace in the seismic trace set, and reconstruct the single-frequency interference of the seismic trace.

[0038] S52. Obtain the discrete form of single-frequency interference of the seismic traces based on the reconstructed single-frequency interference of the seismic traces, and then perform matrix column vector element mirroring and flipping to obtain the actual single-frequency interference of the seismic traces.

[0039] S53. Subtract the actual single-frequency interference from the signal data of the seismic gather to suppress single-frequency interference.

[0040] A storage medium storing instructions and data for implementing a method for identifying and suppressing single-frequency interference in seismic data.

[0041] A computer device includes: a processor and a storage medium; the processor loads and executes instructions and data in the storage medium to implement a method for identifying and suppressing single-frequency interference in seismic data.

[0042] The beneficial effects of the technical solution provided by this invention are as follows: This invention obtains the signal data for identifying seismic gathers by mirroring and normalizing the seismic gather signal data, and then calculates the average cross-correlation coefficient of the seismic gathers to determine whether the seismic gathers contain single-frequency interference. This conforms to the characteristics of seismic data, where the energy is strong at near offsets, weak at far offsets, strong in shallow areas, and weak in deep areas, and can effectively identify single-frequency interference. By mirroring and flipping the seismic data to estimate the amplitude of single-frequency interference, and then mirroring it back to successfully obtain the single-frequency interference of the original seismic record, the inaccuracy of single-frequency interference estimation caused by abnormal energy at near offsets can be avoided. Attached Figure Description

[0043] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0044] Figure 1 This is a flowchart of a method for identifying and suppressing single-frequency interference in seismic data according to an embodiment of the present invention;

[0045] Figure 2 This is a schematic diagram comparing the effects of the present invention and conventional methods in an embodiment of the present invention;

[0046] Figure 3 This is a schematic diagram of the hardware device working in an embodiment of the present invention. Detailed Implementation

[0047] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0048] Embodiments of the present invention provide a method, device, and storage medium for identifying and suppressing single-frequency interference in seismic data.

[0049] Please refer to Figure 1 , Figure 1 This is a flowchart of a method for identifying and suppressing single-frequency interference in seismic data according to an embodiment of the present invention, which specifically includes the following steps:

[0050] The first step is to define the observation system, acquire seismic data, extract seismic gathers, and export their signal data.

[0051] Seismic data consists of single-shot records received from multiple receivers.

[0052] The seismic gather is a collection of seismic traces extracted from common receiver points after suppressing anomalous amplitudes in seismic data. It is arranged in ascending order of offset. The data in the seismic gather is defined from amplitude data below the earthquake's first arrival time. The derived form of the seismic gather is as follows:

[0053]

[0054] In the formula, s(n) is a function of i and j, representing the signal data of the nth seismic gather; n is the seismic gather number; i is the number of sample points acquired below the first arrival time of the seismic gather; and j is the number of seismic traces in the nth seismic gather. ij The amplitude is the amplitude below the first arrival time of the earthquake in the seismic trace.

[0055] The second step involves mirroring and normalizing the seismic gather signal data to obtain the signal data for seismic gather identification. The specific steps are as follows:

[0056] Step 1: Mirror and flip the column vector elements of the seismic gather signal data. The mathematical expression is as follows:

[0057]

[0058] In the formula, srev(n) is a function of i and j, representing the mirror flipping result of the nth seismic gather signal data.

[0059] Step two involves normalizing the mirrored seismic gather signal data to obtain the seismic gather signal data, the mathematical expression of which is as follows:

[0060] srevnorm(n)=srevnorm(i,j)=srev(n) / max(srev)

[0061] In the formula, srevnorm(n) is a function of i and j, representing the identification signal data of the nth seismic gather.

[0062] In earthquakes, the shallow energy of a single shot near the track is strong. Normally, cross-correlation or least squares methods cannot accurately fit the single-shot interference. To solve this problem, this invention mirrors and flips the column vector elements of the derived matrix of each seismic gather at the common receiver point. The estimated single-frequency interference is a mirror image of the single-frequency interference in the actual seismic record. This method avoids the influence of strong shallow energy and better satisfies the rationality of identification and suppression algorithms.

[0063] The third step is to calculate the average cross-correlation coefficient of the seismic gathers based on the identified seismic gather signal data, and determine whether the seismic gathers contain single-frequency interference.

[0064] Single-frequency interference is represented by a discrete mathematical model, and its cosine model is as follows:

[0065] y=Ccos(2πfiΔt+φ)=Acos(2πfiΔt)+Bsin(2πfiΔt)

[0066] In the formula, y represents the single-frequency interference; C represents the actual amplitude of the single-frequency interference; A represents the amplitude of the cosine function after decomposing the single-frequency interference; and B represents the amplitude of the sine function after decomposing the single-frequency interference. There is a corresponding relationship among the three. φ is the phase of the single-frequency interference; f is the frequency of the single-frequency interference; Δt is the sampling time interval.

[0067] Whether a seismic gather contains single-frequency interference is determined by the average cross-correlation coefficient of the seismic gather. When the average cross-correlation coefficient of the seismic gather exceeds a critical value, then all seismic gathers contain single-frequency interference.

[0068] The average cross-correlation coefficient of the seismic gather is the weighted average of the cross-correlation coefficients of the seismic traces, and the calculation formula is as follows:

[0069]

[0070] In the formula, Rj represents the average cross-correlation coefficient of the nth seismic gather; R(j) represents the cross-correlation coefficient of the jth seismic gather, calculated using the following formula:

[0071]

[0072] In the formula, Rc(j) is the cosine cross-correlation coefficient of the j-th seismic trace in the seismic trace set, and Rs(j) is the sine cross-correlation coefficient of the j-th seismic trace in the seismic trace set. The calculation formula is as follows:

[0073]

[0074] The fourth step is to determine the high-precision single-frequency interference frequency of each seismic trace in the seismic gather when it contains single-frequency interference.

[0075] The steps for high-precision single-frequency interference frequency calculation are as follows:

[0076] The initial frequency of each seismic trace is obtained by frequency spectrum analysis of the seismic trace collection. Based on the relationship between frequency and amplitude in single-frequency interference, the accuracy is gradually increased on the basis of the initial single-frequency interference frequency to obtain the high-precision single-frequency interference frequency of each seismic trace in the seismic trace collection.

[0077] The functional expression for the relationship between frequency and amplitude in single-frequency interference is as follows:

[0078]

[0079] according to The frequency that makes the amplitude C(j) reach its maximum value in the preset frequency accuracy level is taken as the high-precision single-frequency interference frequency of the j-th seismic trace in the seismic trace set.

[0080] The detailed derivation process is as follows:

[0081] First, a hierarchical search is performed near the initial frequency. The first-level search sample points are as follows:

[0082] f k =f0+0.1k, -10≤k≤10

[0083] The sample point f is calculated based on the functional relationship between the frequency and amplitude of the single-frequency interference. k The corresponding amplitude value, when the amplitude C(n) reaches its maximum value, yields the frequency f1. f1 is then set as the initial frequency for the second-level search, resulting in the following second-level search samples:

[0084] f k = f1 + 0.01k, -10 ≤ k ≤ 10

[0085] Following the same procedure, calculate the sample point f based on the functional relationship between the frequency and amplitude of the single-frequency interference. k The corresponding amplitude value, according to the correspondence relationship Calculate the amplitude C(j). When the amplitude C(j) reaches its maximum value, obtain the frequency f2 as the initial frequency for the third-level search, and start the third-level search:

[0086] f k = f2 + 0.001k, -10 ≤ k ≤ 10

[0087] Similarly, the precision is gradually increased based on the initial frequency, and the frequency that makes the amplitude C(j) reach its maximum value in the preset precision level is taken as the high-precision single-frequency interference frequency of the j-th seismic trace in the seismic trace set.

[0088] The fifth step involves calculating the actual single-frequency interference of the seismic traces based on the high-precision single-frequency interference frequencies of each seismic trace in the seismic trace set, and then suppressing the single-frequency interference. The specific steps are as follows:

[0089] Step 1: Calculate the corresponding amplitude based on the high-precision single-frequency interference frequency of each seismic trace in the seismic trace set, and reconstruct the single-frequency interference of the seismic trace. The mathematical representation is as follows:

[0090] y * (j)=Acos(2πf * iΔt)+Bsin(2πf * iΔt)

[0091] In the formula, y * (j) represents the reconstructed single-frequency interference of the j-th seismic trace in the seismic trace set, f * This is the high-precision single-frequency interference frequency for this seismic trace.

[0092] Step two: Based on the reconstructed seismic trace single-frequency interference, obtain the discrete form of the single-frequency interference of the seismic gather, and then perform matrix column vector element mirroring to obtain the actual single-frequency interference of the seismic gather.

[0093] The discrete form of the single-frequency interference of the seismic gather is obtained based on the reconstructed seismic trace single-frequency interference, and its mathematical representation is as follows:

[0094]

[0095] In the formula, y * (n) represents the discrete form of single-frequency interference of the nth seismic gather.

[0096] For y * (n) Perform a mirroring and flipping process on the matrix column vector elements to obtain the actual single-frequency interference y of the seismic gather. * rev(n), mathematically represented as follows:

[0097]

[0098] Step 3: Subtract the actual single-frequency interference from the signal data of the seismic gather to suppress single-frequency interference. The mathematical representation is as follows:

[0099] x(n) = s(n) - y * rev(n)

[0100] In the formula, x(n) is the result of suppressing single-frequency interference in the nth seismic gather.

[0101] Please see Figure 2 , Figure 2 This is a schematic diagram comparing the effects of the present invention and conventional methods in an embodiment of the present invention. Figure 2(a) is the original single shot. To more clearly demonstrate the superiority of this invention, a near-shot seismic trace containing single-frequency interference is selected here. Previous references have not discussed the effect of suppressing single-frequency interference in the near-shot trace. The conventional method used is the cross-correlation normalization coefficient proposed by Chen Keyang et al., which calculates the cross-correlation normalization coefficient in the time domain to determine whether the seismic trace concentration contains single-frequency interference. When the near-shot trace contains single-frequency interference, due to the abnormally strong shallow energy in the near-shot trace, regardless of whether the least squares method or the cross-correlation method is used, the single-shot interference with a large amplitude will be estimated. Figure 2 (b) is a conventional method for suppressing single-frequency interference from a single shot. Due to the high energy at close range, a strong amplitude single-frequency interference is reconstructed, which will produce strong single-frequency interference after suppression in the time domain. Figure 2 (c) shows the single-frequency interference suppressed by this method, demonstrating that this method effectively identifies and suppresses single-frequency interference on the short track.

[0102] Please see Figure 3 , Figure 3 This is a schematic diagram of the hardware device operation according to an embodiment of the present invention. The hardware device specifically includes: a computer device 401, a processor 402, and a storage medium 403.

[0103] A computer device 401: The computer device 401 implements the method for identifying and suppressing single-frequency interference in seismic data.

[0104] Processor 402: The processor 402 loads and executes the instructions and data in the storage medium 403 to implement the method for identifying and suppressing single-frequency interference in seismic data.

[0105] Storage medium 403: The storage medium 403 stores instructions and data; the storage medium 403 is used to implement the method for identifying and suppressing single-frequency interference in seismic data.

[0106] The beneficial effects of this invention are as follows: This invention obtains the signal data for identifying seismic gathers by mirroring and normalizing the seismic gather signal data, and then calculates the average cross-correlation coefficient of the seismic gathers to determine whether the seismic gathers contain single-frequency interference. This conforms to the characteristics of seismic data, where the energy is strong at near offsets, weak at far offsets, strong in shallow areas, and weak in deep areas. It can effectively identify single-frequency interference, estimate the amplitude of single-frequency interference by mirroring and flipping the seismic data, and then successfully obtain the single-frequency interference of the original seismic record by mirroring and flipping back. This can avoid the inaccuracy of single-frequency interference estimation caused by abnormal energy at near offsets of the seismic data.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for identifying and suppressing single-frequency interference in seismic data, characterized in that, The specific steps include: S1. Define the observation system, acquire seismic data, extract seismic gathers, and derive their signal data; the seismic gathers are collections of seismic traces from common receiver points extracted after suppressing anomalous amplitudes in the seismic data, arranged in ascending order of offset. The data in the seismic gathers are defined by amplitude data after the initial arrival time of the earthquake. The derived form of the seismic gathers is as follows: In the formula, Let be a function of i and j, representing the signal data of the nth seismic gather; n is the seismic gather number; i is the number of sample points collected after the first arrival time of the seismic gather; and j is the number of seismic traces in the nth seismic gather. The amplitude after the initial arrival time of the earthquake in the seismic trace; S2. Mirror and normalize the seismic gather signal data to obtain the signal data for seismic gather identification, specifically: S21. The signal data of the seismic gather is subjected to a matrix column vector element mirroring process, as shown in the following mathematical expression: In the formula, Let be a function of i and j, representing the mirror flipping result of the nth seismic gather signal data; S22. Normalize the mirror-flipped seismic gather signal data to obtain the seismic gather identification signal data. The mathematical expression is as follows: In the formula, Let be a function of i and j, representing the identification signal data of the nth seismic gather; S3. Calculate the average cross-correlation coefficient of the seismic gathers based on the signal data used for seismic gather identification, and determine whether the seismic gathers contain single-frequency interference. S4. When it is determined that the seismic gather contains single-frequency interference, calculate the high-precision single-frequency interference frequency of each seismic trace in the seismic gather. S5. Based on the high-precision single-frequency interference frequency of each seismic trace in the seismic trace set, calculate the actual single-frequency interference of the seismic trace set, and then suppress the single-frequency interference; specifically: S51. Calculate the corresponding amplitude based on the high-precision single-frequency interference frequency of each seismic trace in the seismic trace set, and reconstruct the single-frequency interference of the seismic trace. S52. Obtain the discrete form of single-frequency interference of the seismic traces based on the reconstructed single-frequency interference of the seismic traces, and then perform matrix column vector element mirroring and flipping to obtain the actual single-frequency interference of the seismic traces. S53. Subtract the actual single-frequency interference from the signal data of the seismic gather to suppress single-frequency interference.

2. The method for identifying and suppressing single-frequency interference in seismic data as described in claim 1, characterized in that, The seismic data refers to single-shot record data received from multiple receivers.

3. The method for identifying and suppressing single-frequency interference in seismic data as described in claim 1, characterized in that, The single-frequency interference is represented by a discrete mathematical model, and its cosine model is as follows: In the formula, This is single-frequency interference; This represents the actual amplitude of a single-frequency interference. This represents the amplitude of the cosine function after decomposing the single-frequency interference. This represents the amplitude of the sine function after decomposing the single-frequency interference; there is a corresponding relationship among the three. ; The phase of a single-frequency interference; The frequency of single-frequency interference; This represents the sampling time interval.

4. The method for identifying and suppressing single-frequency interference in seismic data as described in claim 3, characterized in that, Whether a seismic gather contains single-frequency interference is determined by the average cross-correlation coefficient of the seismic gather. When the average cross-correlation coefficient of the seismic gather exceeds a critical value, then all seismic gathers contain single-frequency interference. The average cross-correlation coefficient of the seismic gather is the weighted average of the cross-correlation coefficients of the seismic traces, and the calculation formula is as follows: In the formula, The average cross-correlation number of the nth seismic gather; Let represent the cross-correlation coefficient of the j-th seismic trace in the seismic trace set. The calculation formula is as follows: In the formula, Let cosine cross-correlation coefficient be the cosine cross-correlation coefficient of the j-th seismic trace in the seismic trace set. Let be the sinusoidal cross-correlation coefficient of the j-th seismic trace in the seismic trace set, calculated using the following formula: 。 5. The method for identifying and suppressing single-frequency interference in seismic data as described in claim 4, characterized in that, The high-precision single-frequency interference frequency calculation steps are as follows: The initial frequency of each seismic trace is obtained by frequency spectrum analysis of the seismic trace collection. Based on the relationship between frequency and amplitude in single-frequency interference, the accuracy is gradually increased on the basis of the initial single-frequency interference frequency to obtain the high-precision single-frequency interference frequency of each seismic trace in the seismic trace collection. The functional expression for the relationship between frequency and amplitude in single-frequency interference is as follows: according to The preset frequency accuracy level is adjusted to make the amplitude... The frequency at which the maximum value is reached is used as the high-precision single-frequency interference frequency of the j-th seismic trace in the seismic trace set.

6. A storage medium, characterized in that: The storage medium stores instructions and data to implement the single-frequency interference identification and suppression method for seismic data as described in any one of claims 1 to 5.

7. A computer device, characterized in that: include: A processor and a storage medium; the processor loads and executes instructions and data in the storage medium to implement the single-frequency interference identification and suppression method for seismic data as described in any one of claims 1 to 5.

Images