Ghost wave parameter optimization method for suppressing ghost wave of streamer based on frequency slowness domain continuation

Abstract

The application discloses a method for suppressing ghost waves of a streamer based on frequency-slowness domain continuation and ghost wave parameter optimization. Considering that ghost wave parameters vary with time and space and affect the ghost wave removal effect, first, the marine seismic data is divided by using a sliding time window to reduce the influence of the time variation of the ghost wave parameters; the delay time and amplitude difference coefficient of the ghost wave and the primary wave are enumerated alternately; the data in the time window is continued by using a frequency-slowness domain wave field continuation operator, and then the original marine seismic data is added and subtracted by the continued record; the sum of the absolute values of the products of the new records obtained by operation is taken as the target, the optimal ghost wave delay time and amplitude difference coefficient are iteratively searched, and then the ghost wave is suppressed; after the data in each window is suppressed, all the window data are integrated into a complete record. The method can effectively suppress the ghost wave, widen the frequency band and improve the resolution of the seismic data.

Description

Technical Field

[0001] This invention relates to the field of ghost wave suppression technology, and in particular to a ghost wave suppression method for towed cables based on frequency slowness domain extension and ghost wave parameter optimization. Background Technology

[0002] In marine exploration, towlines are typically laid below the sea surface. Due to the strong reflection from the sea surface, reflected waves from the strata in marine seismic data are accompanied by ghost waves with out-of-phase phase. The trapping effect of these ghost waves narrows the effective frequency band of the seismic record, and suppressing ghost waves is an important way to broaden the frequency band of seismic data.

[0003] In the frequency slow-domain ghost wave suppression method, under the condition of a horizontal sea surface, when the detector's wavefield is at the same slowness, the delay time between the ghost wave and the primary wave is a function of the detector depth. Due to the significant difference in wave impedance between seawater and air, the sea surface reflection coefficient is often assumed to be -1. A relationship between the ghost wave and the primary wave is established based on the relationship at the same slowness, and the upflow wave field is obtained by solving the relationship using the least squares method. However, this method has significant limitations in terms of the delay time and amplitude difference coefficient between the ghost wave and the primary wave in actual data acquisition; in real-world data, the delay time and amplitude difference coefficient fluctuate.

[0004] Therefore, accurately obtaining the delay time and amplitude difference coefficient between the ghost wave and the primary wave is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a ghost wave suppression method based on frequency slow-domain extension for optimizing ghost wave parameters. By extending the ghost wave to obtain an extended record, the characteristics of the two new records obtained by adding and subtracting the extended record from the original record are compared to correct the ghost wave parameters, thereby improving the accuracy of the ghost wave parameters and enhancing the ghost wave suppression effect.

[0006] To achieve the above objectives, this invention provides a ghost wave suppression method for towed cables based on frequency slow-domain extension and ghost wave parameter optimization, comprising the following steps:

[0007] S1: Determine the size of the sliding time window and divide the marine seismic data;

[0008] S2: Set the delay time and amplitude difference coefficient of ghost wave and primary wave in the marine seismic data within the window as ghost wave parameters, determine the range of variation of delay time and amplitude difference coefficient, and divide the delay time and amplitude difference coefficient into equal intervals;

[0009] S3: Select the delay time and amplitude difference coefficient, extend the marine seismic data within the window using the frequency slow domain wavefield extension operator, then add and subtract the extended record from the original marine seismic data respectively, and use the sum of the absolute values ​​of the products of the new records obtained by the calculation as the objective function, and calculate the objective function value.

[0010] S4: Keep the amplitude difference coefficient unchanged, repeat step S3 for all the divided delay times, take the delay time corresponding to the minimum value of the objective function as the current optimal delay time, and then update the delay time;

[0011] S5: Keep the delay time unchanged, repeat step S3 for all the amplitude difference coefficients of the division, take the amplitude difference coefficient corresponding to the minimum value of the objective function as the current optimal amplitude difference coefficient, and then update the amplitude difference coefficient.

[0012] S6: Repeat steps S4 to S5, update the optimal delay time and the optimal amplitude difference coefficient until the maximum number of iterations is reached, and remove the ghost wave with the final optimal delay time and the optimal amplitude difference coefficient;

[0013] S7: Repeat steps S3 to S6 for the marine seismic data in each window, and finally integrate the data in all windows into a complete record, which is the marine seismic data after ghost wave suppression.

[0014] Furthermore, step S1 specifically includes: determining the size of the sliding time window, with each rectangle containing a portion of the seismic data, discretizing the entire marine seismic data along the time axis, and trying to place ghost waves and upgoing waves in the same time window, with partial overlap between the sliding windows to ensure full coverage of the marine seismic data.

[0015] Further, step S2 specifically includes: setting the delay time and amplitude difference coefficient of the ghost wave and the primary wave in the marine seismic data within the window as the ghost wave parameter, determining the delay time interval as α, and the range of delay time variation as Δτ. min -Δτ max The amplitude difference coefficient interval is β, and the amplitude difference coefficient varies within the range of R. min -R max The time delay and amplitude difference coefficient within the range of variation are divided into equal intervals at a given interval.

[0016] Furthermore, step S3 specifically includes:

[0017] S31: Perform a one-dimensional Fourier transform on the marine seismic data d(x,t) within the window to D(x,ω), and then perform a forward Radon transform in the frequency domain to...

[0018] S32: Obtain the frequency slow-domain wavefield extension operator based on the frequency slow-domain ghost wave suppression method, specifically including:

[0019] In the frequency-slow-domain ghost wave suppression method, for each frequency ω, there is

[0020] D(x,ω)=G(x,p,ω)U(p,ω)

[0021] In the formula, x is the detector offset distance, p is the horizontal slowness parameter, D(x,ω) is the frequency spatial domain record of the total wave field d(x,t), which is a column vector with N elements; U(p,ω) is the frequency slowness domain record of the first wave u(x,t), which is a column vector with M elements; G(x,p,ω) is the representation of the ghost wave filter operator in the frequency slowness domain, which is an N×M matrix with the following elements:

[0022]

[0023] In the formula, G U Multiplying (x,p,ω) by U(p,ω) yields a first-order wave, U(p,ω) and -G. G Multiplying (x, p, ω) yields the ghost wave. θ j It is the j-th level of slowness p j The corresponding exit angle of the plane wave is j = 1, 2, ..., M, where M is the number of slowness degrees; Δτ is the time delay between the ghost wave and the first wave; x i z i , i = 1, 2, ..., N, where N is the number of channels recorded; R is the assumed ghost wave amplitude difference coefficient between the ghost wave and the primary wave; V w It is the propagation speed of the seawater wave field;

[0024] From the expression of D(x,ω), we get

[0025] D(x,ω)=(G U (x,p,ω)-G G (x,p,ω))U(p,ω)

[0026] Let D(x,ω) be abbreviated to D, U(p,ω) to U, and G... G (x,p,ω) is abbreviated as G G G U (x,p,ω) is abbreviated as G U Multiply both sides by G U -1 ,have to

[0027] G U -1D = (IG) U -1 G G )U

[0028] In the above formula, The earthquake record is about to be converted from the frequency spatial domain to the frequency slowness domain. This is equivalent to marine seismic data obtained by performing a Radon forward transform on D(x,ω) in the frequency domain; let G U (x,p,ω) -1 G G (x,p,ω)=T, where T is the frequency-slow-domain wavefield extension operator; Abbreviated as So

[0029]

[0030] right After one extension, compared with the original record Adding them together gives

[0031]

[0032] By extension, we have

[0033]

[0034] Where k = 1, 2, ..., K, K corresponds to the number of wave field extensions;

[0035] S33: Using the current delay time and amplitude difference coefficient, the seismic record is extended in the frequency slowness domain using the frequency slowness domain wavefield extension operator:

[0036] set up but

[0037] T + =G U (x,p,ω) -1 G G+ (x,p,ω)

[0038] T - =G U (x,p,ω) -1 G G- (x,p,ω)

[0039] Let T + Operator pairs After one extension, compared with the original record Adding them together gives Then there is

[0040]

[0041] With T - Operator pairs After one extension, use the original record. Subtracting the result Then there is

[0042]

[0043] Will With Q - Transform to the frequency space domain, i.e.

[0044]

[0045]

[0046] Then, regarding Q + The time-space domain record q is obtained by performing an inverse Fourier transform. + (x,t), for Q - The time-space domain record q is obtained by performing an inverse Fourier transform. - (x,t);

[0047] S34: Establish the following objective function, and calculate the corresponding objective function value for each delay time, i.e.

[0048]

[0049] In the formula, q + (x,t) is equivalent to the original record plus the extended record, q - (x,t) is equivalent to the original record minus the extended record, and S(x) is the objective function value of the trace record at the shot-receiver distance x with respect to the coefficient of difference in amplitude for different delay times; that is, through two newly constructed records q + (x,t) and q - The waveform characteristics of (x,t) are used to determine the recording results of different delay times and different amplitude difference coefficients. The delay time and amplitude difference coefficient corresponding to the optimal processing result are found. The delay time and amplitude difference coefficient corresponding to the minimum value of each objective function are the desired results.

[0050] Further, step S4 specifically includes: keeping the amplitude difference coefficient unchanged, repeating step S3 for all the divided delay times, and then finding the minimum objective function value and its corresponding delay time, i.e.

[0051]

[0052] In the formula, Δτ r Let A be the time of the r-th partition, and let A be the set of all possible delay times, Δτ. est This represents the optimal solution for the delay time.

[0053] Further, step S5 specifically includes: keeping the delay time constant, repeating step S3 for all the divided amplitude difference coefficients, and finding the minimum objective function value and its corresponding amplitude difference coefficient, i.e.

[0054]

[0055] In the formula, R v Let R be the amplitude difference coefficient of the v-th partition, B be the set of all possible amplitude difference coefficients, and R be the amplitude difference coefficient of the v-th partition. est The optimal solution represents the amplitude difference coefficient.

[0056] Further, step S6 specifically includes: repeating steps S4 to S5, updating the optimal delay time and the optimal amplitude difference coefficient; stopping the iteration when the maximum number of iterations is reached; determining the optimal delay time and the optimal amplitude difference coefficient; obtaining the corrected ghost wave filter factor G; and then processing the ghost wave using the frequency slow domain ghost wave suppression method, i.e.

[0057] U = (G T G+μI) -1 G T D

[0058] In the formula, μ is the damping coefficient, and I is the identity matrix.

[0059] In addition, to achieve the above objectives, the present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps of the described ghost wave suppression method based on frequency slow domain extension ghost wave parameter optimization for towed cable.

[0060] In addition, to achieve the above objectives, the present invention also provides a storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the described ghost wave suppression method based on frequency slow domain extension for optimizing ghost wave parameters in a tow cable.

[0061] The technical solution provided by this invention has the following beneficial effects:

[0062] This invention considers that the ghost wave parameters vary with time and space, affecting the ghost wave removal effect. Therefore, it first divides the marine seismic data using a sliding time window to reduce the impact of time-varying ghost wave parameters; it then alternately enumerates the delay time and amplitude difference coefficient between the ghost wave and the primary wave; it extends the data within the time window using a frequency slowness domain wavefield extension operator, and then adds and subtracts the extended primary wave record from the original marine seismic data; aiming to minimize the sum of the absolute values ​​of the products of the newly obtained records, iteratively searches for the optimal ghost wave delay time and amplitude difference coefficient, thereby suppressing the ghost wave; after suppressing the ghost wave in the data within each window, all window data are integrated into a complete record. This method can effectively suppress ghost waves, broaden the frequency band, and improve the resolution of seismic data. Attached Figure Description

[0063] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0064] Figure 1 This is a flowchart of the ghost wave suppression method for towed cables based on frequency slow domain extension for ghost wave parameter optimization according to the present invention.

[0065] Figure 2 The diagram shows the variation of complex salt dome model and inclined cable depth with offset distance in an embodiment of the present invention; (a) schematic diagram of salt dome model; (b) schematic diagram of inclined cable depth;

[0066] Figure 3 The following are composite records before and after ghosting removal in an embodiment of the present invention: (a) original record; (b) time-space domain ghosting removal record; (c) time-slowness domain original record; (d) time-slowness domain ghosting removal record.

[0067] Figure 4 These are partial views of the synthesized record before and after ghost wave removal in an embodiment of the present invention; (a) partial view of the original record; (b) partial view of the ghost wave removed record.

[0068] Figure 5 The following are the synthesized recorded amplitude spectra before and after ghost wave removal in an embodiment of the present invention: (a) Original recorded amplitude spectrum; (b) Recorded amplitude spectrum after ghost wave removal;

[0069] Figure 6 This is a schematic diagram of the physical structure of an electronic device according to the present invention. Detailed Implementation

[0070] 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.

[0071] refer to Figure 1 , Figure 1 This is a flowchart of the ghost wave suppression method for towed cables based on frequency slow domain extension for ghost wave parameter optimization according to the present invention. The method includes the following steps:

[0072] S1: Determine the size of the sliding time window and divide the marine seismic data;

[0073] The specific implementation of S1 is as follows: Determine the size of the sliding time window, each rectangle contains a portion of the seismic data, the window discretizes the entire marine seismic data along the time axis, and tries to place ghost waves and upgoing waves in the same time window. The sliding windows overlap partially to ensure full coverage of the marine seismic data.

[0074] S2: Set the delay time and amplitude difference coefficient of ghost wave and primary wave in the marine seismic data within the window as ghost wave parameters, determine the range of variation of delay time and amplitude difference coefficient, and divide the delay time and amplitude difference coefficient into equal intervals;

[0075] The specific implementation of S2 is as follows: The delay time and amplitude difference coefficient of the ghost wave and primary wave in the marine seismic data within the window are set as the ghost wave parameter; the delay time interval is determined as α; and the range of delay time variation is Δτ. min -Δτ max The amplitude difference coefficient interval is β, and the amplitude difference coefficient varies within the range of R. min -R max The time delay and amplitude difference coefficient within the range of variation are divided into equal intervals at a given interval.

[0076] S3: Select the delay time and amplitude difference coefficient, extend the marine seismic data within the window using the frequency slow domain wavefield extension operator, then add and subtract the extended record from the original marine seismic data respectively, and use the sum of the absolute values ​​of the products of the new records obtained by the calculation as the objective function, and calculate the objective function value.

[0077] The specific implementation method of S3 is as follows:

[0078] S31: Perform a one-dimensional Fourier transform on the marine seismic data d(x,t) within the window to D(x,ω), and then perform a forward Radon transform in the frequency domain to...

[0079] S32: Obtain the frequency slow-domain wavefield extension operator based on the frequency slow-domain ghost wave suppression method, specifically including:

[0080] In the frequency-slow-domain ghost wave suppression method, for each frequency ω, there is

[0081] D(x,ω)=G(x,p,ω)U(p,ω)

[0082] In the formula, x is the detector offset distance, p is the horizontal slowness parameter, D(x,ω) is the frequency spatial domain record of the total wave field d(x,t), which is a column vector with N elements; U(p,ω) is the frequency slowness domain record of the first wave u(x,t), which is a column vector with M elements; G(x,p,ω) is the representation of the ghost wave filter operator in the frequency slowness domain, which is an N×M matrix with the following elements:

[0083]

[0084] In the formula, G U Multiplying (x,p,ω) by U(p,ω) yields a first-order wave, U(p,ω) and -G. G Multiplying (x, p, ω) yields the ghost wave. θ j It is the j-th level of slowness p j The corresponding exit angle of the plane wave is j = 1, 2, ..., M, where M is the number of slowness degrees; Δτ is the time delay between the ghost wave and the first wave; x i z i , i = 1, 2, ..., N, where N is the number of channels recorded; R is the assumed ghost wave amplitude difference coefficient between the ghost wave and the primary wave; V w It is the propagation speed of the seawater wave field;

[0085] From the expression of D(x,ω), we get

[0086] D(x,ω)=(G U (x,p,ω)-G G (x,p,ω))U(p,ω)

[0087] Let D(x,ω) be abbreviated to D, U(p,ω) to U, and G... G (x,p,ω) is abbreviated as G G G U (x,p,ω) is abbreviated as G U Multiply both sides by G U -1 ,have to

[0088] G U -1 D = (IG) U -1 G G )U

[0089] In the above formula, The earthquake record is about to be converted from the frequency spatial domain to the frequency slowness domain. This is equivalent to marine seismic data obtained by performing a Radon forward transform on D(x,ω) in the frequency domain; let GU (x,p,ω) -1 G G (x,p,ω)=T, where T is the frequency-slow-domain wavefield extension operator; Abbreviated as So

[0090]

[0091] right After one extension, compared with the original record Adding them together gives

[0092]

[0093] By extension, we have

[0094]

[0095] Where k = 1, 2, ..., K, K corresponds to the number of wave field extensions;

[0096] S33: Using the current delay time and amplitude difference coefficient, the seismic record is extended in the frequency slowness domain using the frequency slowness domain wavefield extension operator:

[0097] set up but

[0098] T + =G U (x,p,ω) -1 G G+ (x,p,ω)

[0099] T - =G U (x,p,ω) -1 G G- (x,p,ω)

[0100] Let T + Operator pairs After one extension, compared with the original record Adding them together gives Then there is

[0101]

[0102] With T - Operator pairs After one extension, use the original record. Subtracting the result Then there is

[0103]

[0104] Will With Q- Transform to the frequency space domain, i.e.

[0105]

[0106]

[0107] Then, regarding Q + The time-space domain record q is obtained by performing an inverse Fourier transform. + (x,t), for Q - The time-space domain record q is obtained by performing an inverse Fourier transform. - (x,t);

[0108] S34: Establish the following objective function, and calculate the corresponding objective function value for each delay time, i.e.

[0109]

[0110] In the formula, q + (x,t) is equivalent to the original record plus the extended record, q - (x,t) is equivalent to the original record minus the extended record, and S(x) is the objective function value of the trace record at the shot-receiver distance x with respect to the coefficient of difference in amplitude for different delay times; that is, through two newly constructed records q + (x,t) and q - The waveform characteristics of (x,t) are used to determine the recording results of different delay times and different amplitude difference coefficients. The delay time and amplitude difference coefficient corresponding to the optimal processing result are found. The delay time and amplitude difference coefficient corresponding to the minimum value of each objective function are the desired results.

[0111] S4: Keep the amplitude difference coefficient unchanged, repeat step S3 for all the divided delay times, take the delay time corresponding to the minimum value of the objective function as the current optimal delay time, and then update the delay time;

[0112] The specific implementation of S4 is as follows: Keeping the amplitude difference coefficient unchanged, repeat step S3 for all the divided delay times, and then find the minimum objective function value and its corresponding delay time, i.e.

[0113]

[0114] In the formula, Δτ r Let A be the time of the r-th partition, and let A be the set of all possible delay times, Δτ. est This represents the optimal solution for the delay time.

[0115] S5: Keep the delay time unchanged, repeat step S3 for all the amplitude difference coefficients of the division, take the amplitude difference coefficient corresponding to the minimum value of the objective function as the current optimal amplitude difference coefficient, and then update the amplitude difference coefficient.

[0116] The specific implementation of S5 is as follows: Keeping the delay time constant, repeat step S3 for all the amplitude difference coefficients, and find the minimum objective function value and its corresponding amplitude difference coefficient, i.e.

[0117]

[0118] In the formula, R v Let R be the amplitude difference coefficient of the v-th partition, B be the set of all possible amplitude difference coefficients, and R be the amplitude difference coefficient of the v-th partition. est The optimal solution represents the amplitude difference coefficient.

[0119] S6: Repeat steps S4 to S5, update the optimal delay time and the optimal amplitude difference coefficient until the maximum number of iterations is reached, and remove the ghost wave with the final optimal delay time and the optimal amplitude difference coefficient;

[0120] Step S6 is implemented as follows: Repeat steps S4 to S5, update the optimal delay time and the optimal amplitude difference coefficient. When the maximum number of iterations is reached, stop the iteration, determine the optimal delay time and the optimal amplitude difference coefficient, obtain the corrected ghost wave filter factor G, and then process the ghost wave using the frequency slow domain ghost wave suppression method, i.e.

[0121] U = (G T G+μI) -1 G T D

[0122] In the formula, μ is the damping coefficient, and I is the identity matrix.

[0123] S7: Repeat steps S3 to S6 for the marine seismic data in each window, and finally integrate the data in all windows into a complete record, which is the marine seismic data after ghost wave suppression.

[0124] To verify the ghost wave suppression effect of the method of the present invention, a specific embodiment is described below:

[0125] In this embodiment, the following is adopted: Figure 2 (a) shows the forward model of the complex salt dome model, with the inclined cable using... Figure 2 (b) shows a parabolic inclined cable with the shot point located at 800m. The geophone is submerged at depths ranging from a minimum of 6m to a maximum of 50m, recording a total of 250 channels with a channel spacing of 10m and a time sampling interval of 0.002s. The wavelet used is a 35Hz Ricker wavelet, and the channel recording length is 2.9s. The initial delay time Δτ0 is calculated from the current depth of the tow cable. Here, the delay time Δτ r ∈[0.8Δτ0, 1.2Δτ0], with intervals of 0.01Δτ0; amplitude difference coefficient R v∈[-1, -0.6], with a 0.01 interval.

[0126] It should be noted that in other embodiments, the specific values ​​mentioned above may be adjusted or changed according to the actual situation, and all such adjustments are within the scope of protection of this invention.

[0127] In the original artillery collection ( Figure 3 (a) Due to the strong reflection from the sea surface, a ghost wave of opposite phase follows the primary wave. The delay time between the ghost wave and the primary wave first increases and then decreases as the offset distance increases. Figure 3 (b) shows the shot gather after the ghost wave suppression by the towed cable. It can be clearly seen that after processing by the method of this invention, the anti-phase axis after the first wave basically disappears, and the phase of the entire record becomes relatively uniform. When optimizing parameters, it is necessary to convert the data to the frequency slowness domain for extension, and then convert it to the time-space domain for processing result judgment. When converting the original shot gather to the time slowness domain, such as... Figure 3 As shown in (c), it can be found that... Figure 3 (a) Similar characteristics: the in-phase axes corresponding to the ghost wave and the primary wave gradually separate and then move closer together. Their phases are opposite, and each in-phase axis corresponds to the in-phase axis in the time-space domain. Figure 3 (d) is the time-slow domain record of the ghost wave deghosting, in which the in-phase axis corresponding to the ghost wave is effectively suppressed, and the ghost wave is removed relatively cleanly. From Figure 4 (a) shows the near-offset local recording, revealing the gradual separation of the ghost wave and the primary wave as the offset increases. After ghost wave suppression (e.g.) Figure 4 (b) The energy of the ghost wave in phase axis is greatly attenuated. It can be seen that the method of the present invention has a good removal effect on ghost waves.

[0128] The ghost wave interferes with the primary wave, causing notches in the spectrum. At these notches, the spectral energy is significantly weakened (e.g., ...). Figure 5 (a)). Amplitude spectrum in the frequency spatial domain of the original gun collection ( Figure 5 As shown in (a), the notch frequency varies with the detector depth, revealing the diversity of the notch characteristics of the inclined cable. After removing the ghost wave ( Figure 5 (b) The energy at the notch point is effectively recovered, the spectrum becomes continuous, and the effective bandwidth of the recording is increased, verifying that the method described in this paper can suppress ghost waves and compensate for the energy loss at the notch point caused by ghost waves. The ghost wave suppression embodiment verifies the effectiveness of the present invention.

[0129] To better implement the aforementioned ghost wave suppression method based on frequency slow domain extension and ghost wave parameter optimization for cable towing, this invention also provides an electronic device and a storage medium. (Reference) Figure 6 , Figure 6The example illustrates the physical structure of an electronic device, which may include: a processor 610, a communication interface 620, a memory 630, and a communication bus 640, wherein the processor 610, the communication interface 620, and the memory 630 communicate with each other through the communication bus 640. The processor 610 can call the logic instructions in the memory 630 to execute the steps of the above-mentioned ghost wave suppression method based on frequency slow domain extension for ghost wave parameter optimization. For example, the method specifically includes: S1: Determining the size of the sliding time window and dividing the marine seismic data; S2: Setting the delay time and amplitude difference coefficient of the ghost wave and primary wave in the marine seismic data within the window as ghost wave parameters, determining the range of variation of the delay time and amplitude difference coefficient, and dividing the delay time and amplitude difference coefficient at equal intervals; S3: Selecting the delay time and amplitude difference coefficient, extending the marine seismic data within the window using the frequency slow domain wavefield extension operator, then adding and subtracting the extended primary record from the original marine seismic data respectively, using the sum of the absolute values ​​of the products of the newly obtained records as the objective function, and calculating the objective function. S4: Keeping the amplitude difference coefficient unchanged, repeat step S3 for all the divided delay times, take the delay time corresponding to the minimum value of the objective function as the current optimal delay time, and then update the delay time; S5: Keeping the delay time unchanged, repeat step S3 for all the divided amplitude difference coefficients, take the amplitude difference coefficient corresponding to the minimum value of the objective function as the current optimal amplitude difference coefficient, and then update the amplitude difference coefficient; S6: Repeat steps S4 to S5, update the optimal delay time and the optimal amplitude difference coefficient, until the maximum number of iterations is reached, and remove the ghost wave with the final optimal delay time and the optimal amplitude difference coefficient; S7: Repeat steps S3 to S6 for the marine seismic data in each window, and finally integrate the data in all windows into a complete record, that is, obtain the marine seismic data after ghost wave suppression.

[0130] Furthermore, the logical instructions in the aforementioned memory 630 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0131] Furthermore, the present invention also provides a storage medium storing a computer program that, when executed by a processor, implements the steps of the aforementioned method for suppressing ghost waves in towed cables based on frequency slow-domain extension for optimizing ghost wave parameters. For example, the method specifically includes: S1: determining the size of the sliding time window and dividing the marine seismic data; S2: setting the delay time and amplitude difference coefficient of the ghost wave and primary wave in the marine seismic data within the window as ghost wave parameters, determining the range of variation of the delay time and amplitude difference coefficient, and dividing the delay time and amplitude difference coefficient at equal intervals; S3: selecting the delay time and amplitude difference coefficient, extending the marine seismic data within the window using a frequency slow-domain wavefield extension operator, and then adding and subtracting the extended primary record from the original marine seismic data, using the sum of the absolute values ​​of the products of the newly obtained records as the objective function. S4: Keeping the amplitude difference coefficient unchanged, repeat step S3 for all the divided delay times, take the delay time corresponding to the minimum value of the objective function as the current optimal delay time, and then update the delay time; S5: Keeping the delay time unchanged, repeat step S3 for all the divided amplitude difference coefficients, take the amplitude difference coefficient corresponding to the minimum value of the objective function as the current optimal amplitude difference coefficient, and then update the amplitude difference coefficient; S6: Repeat steps S4 to S5, update the optimal delay time and the optimal amplitude difference coefficient, until the maximum number of iterations is reached, and remove the ghost wave with the final optimal delay time and the optimal amplitude difference coefficient; S7: Repeat steps S3 to S6 for the marine seismic data in each window, and finally integrate the data in all windows into a complete record, that is, obtain the marine seismic data after ghost wave suppression.

[0132] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0133] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. In the unit claims listing several devices, several of these devices may be embodied by the same hardware item. The use of the terms first, second, and third, etc., does not indicate any order and can be interpreted as identifiers.

[0134] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A ghost wave suppression method for towed cables based on frequency slow-domain extension and parameter optimization, characterized in that, Includes the following steps: S1: Determine the size of the sliding time window and divide the marine seismic data; S2: Set the delay time and amplitude difference coefficient of ghost wave and primary wave in the marine seismic data within the window as ghost wave parameters, determine the range of variation of delay time and amplitude difference coefficient, and divide the delay time and amplitude difference coefficient into equal intervals; S3: Select the delay time and amplitude difference coefficient, extend the marine seismic data within the window using the frequency slow domain wavefield extension operator, then add and subtract the extended record from the original marine seismic data respectively, and use the sum of the absolute values ​​of the products of the new records obtained by the calculation as the objective function, and calculate the objective function value. S4: Keep the amplitude difference coefficient unchanged, repeat step S3 for all the divided delay times, take the delay time corresponding to the minimum value of the objective function as the current optimal delay time, and then update the delay time; S5: Keep the delay time unchanged, repeat step S3 for all the amplitude difference coefficients of the division, take the amplitude difference coefficient corresponding to the minimum value of the objective function as the current optimal amplitude difference coefficient, and then update the amplitude difference coefficient. S6: Repeat steps S4 to S5, update the optimal delay time and the optimal amplitude difference coefficient until the maximum number of iterations is reached, and remove the ghost wave with the final optimal delay time and the optimal amplitude difference coefficient; S7: Repeat steps S3 to S6 for the marine seismic data in each window, and finally integrate the data in all windows into a complete record, which is the marine seismic data after ghost wave suppression.

2. The ghost wave suppression method for towed cables based on frequency slow-domain extension and parameter optimization according to claim 1, characterized in that, Step S1 specifically includes: determining the size of the sliding time window, with each rectangle containing a portion of the seismic data, discretizing the entire marine seismic data along the time axis, and trying to place ghost waves and upgoing waves in the same time window as much as possible, with partial overlap between the sliding windows to ensure full coverage of the marine seismic data.

3. The ghost wave suppression method for towed cables based on frequency slow-domain extension and parameter optimization according to claim 1, characterized in that, Step S2 specifically includes: setting the delay time and amplitude difference coefficient of the ghost wave and the primary wave in the marine seismic data within the window as the ghost wave parameter, determining the delay time interval as α, and the range of delay time variation as Δτ. min -Δτ max The amplitude difference coefficient interval is β, and the amplitude difference coefficient varies within the range of R. min -R max The time delay and amplitude difference coefficient within the range of variation are divided into equal intervals at a given interval.

4. The ghost wave suppression method for towed cables based on frequency slow-domain extension and parameter optimization according to claim 1, characterized in that, Step S3 specifically includes: S31: Perform a one-dimensional Fourier transform on the marine seismic data d(x,t) within the window to D(x,ω), and then perform a forward Radon transform in the frequency domain to... S32: Obtain the frequency slow-domain wavefield extension operator based on the frequency slow-domain ghost wave suppression method, specifically including: In the frequency-slow-domain ghost wave suppression method, for each frequency ω, there is D(x,ω)=G(x,p,ω)U(p,ω) In the formula, x is the detector offset distance, p is the horizontal slowness parameter, D(x,ω) is the frequency spatial domain record of the total wave field d(x,t), which is a column vector with N elements; U(p,ω) is the frequency slowness domain record of the first wave u(x,t), which is a column vector with M elements; G(x,p,ω) is the representation of the ghost wave filter operator in the frequency slowness domain, which is an N×M matrix with the following elements: In the formula, G U Multiplying (x,p,ω) by U(p,ω) yields a first-order wave, U(p,ω) and -G. G Multiplying (x, p, ω) yields the ghost wave. θ j It is the j-th level of slowness p j The corresponding exit angle of the plane wave is j = 1, 2, ..., M, where M is the number of slowness degrees; Δτ is the time delay between the ghost wave and the first wave; x i z i , i = 1, 2, ..., N, where N is the number of channels recorded; R is the assumed ghost wave amplitude difference coefficient between the ghost wave and the primary wave; V w It is the propagation speed of the seawater wave field; From the expression of D(x,ω), we get D(x,ω)=(G U (x,p,ω)-G G (x,p,ω))U(p,ω) Let D(x,ω) be abbreviated to D, U(p,ω) to U, and G... G (x,p,ω) is abbreviated as G G G U (x,p,ω) is abbreviated as G U Multiply both sides by G U -1 ,have to G U -1 D=(I-G U -1 G G )U In the above formula, The earthquake record is about to be converted from the frequency spatial domain to the frequency slowness domain. This is equivalent to marine seismic data obtained by performing a Radon forward transform on D(x,ω) in the frequency domain; let G U (x,p,ω) -1 G G (x,p,ω)=T, where T is the frequency-slow-domain wavefield extension operator; Abbreviated as So right After one extension, compared with the original record Adding them together gives By extension, we have Where k = 1, 2, ..., K, K corresponds to the number of wave field extensions; S33: Using the current delay time and amplitude difference coefficient, the seismic record is extended in the frequency slowness domain using the frequency slowness domain wavefield extension operator: set up but T + =G U (x,p,ω) -1 G G+ (x,p,ω) T - =G U (x,p,ω) -1 G G- (x,p,ω) Let T + Operator pairs After one extension, compared with the original record Adding them together gives Then there is With T - Operator pairs After one extension, use the original record. Subtracting the result Then there is Will With Q - Transform to the frequency space domain, i.e. Then, regarding Q + The time-space domain record q is obtained by performing an inverse Fourier transform. + (x,t), for Q - The time-space domain record q is obtained by performing an inverse Fourier transform. - (x,t); S34: Establish the following objective function, and calculate the corresponding objective function value for each delay time, i.e. In the formula, q + (x,t) is equivalent to the original record plus the extended record, q - (x,t) is equivalent to the original record minus the extended record, and S(x) is the objective function value of the trace record at the shot-receiver distance x with respect to the coefficient of difference in amplitude for different delay times; that is, through two newly constructed records q + (x,t) and q - The waveform characteristics of (x,t) are used to determine the recording results of different delay times and different amplitude difference coefficients. The delay time and amplitude difference coefficient corresponding to the optimal processing result are found. The delay time and amplitude difference coefficient corresponding to the minimum value of each objective function are the desired results.

5. The ghost wave suppression method for towed cables based on frequency slow-domain extension and ghost wave parameter optimization according to claim 1, characterized in that, Step S4 specifically includes: keeping the amplitude difference coefficient unchanged, repeating step S3 for all the divided delay times, and then finding the minimum objective function value and its corresponding delay time, i.e. In the formula, Δτ r Let A be the time of the r-th partition, and let A be the set of all possible delay times, Δτ. est This represents the optimal solution for the delay time.

6. The ghost wave suppression method for towed cables based on frequency slow-domain extension and ghost wave parameter optimization according to claim 4, characterized in that, Step S5 specifically includes: keeping the delay time constant, repeating step S3 for all the amplitude difference coefficients to find the minimum objective function value and its corresponding amplitude difference coefficient, i.e. In the formula, R v Let R be the amplitude difference coefficient of the v-th partition, B be the set of all possible amplitude difference coefficients, and R be the amplitude difference coefficient of the v-th partition. est The optimal solution represents the amplitude difference coefficient.

7. The ghost wave suppression method for towed cables based on frequency slow-domain extension and parameter optimization according to claim 1, characterized in that, Step S6 specifically includes: repeating steps S4 to S5, updating the optimal delay time and the optimal amplitude difference coefficient; stopping the iteration when the maximum number of iterations is reached; determining the optimal delay time and the optimal amplitude difference coefficient; obtaining the corrected ghost wave filter factor G; and then processing the ghost wave using the frequency slow domain ghost wave suppression method. In the formula, μ is the damping coefficient, and I is the identity matrix.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the ghost wave suppression method for towed cable based on frequency slow domain extension as described in any one of claims 1-7.

9. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the ghost wave suppression method for towed cable based on frequency slow domain extension as described in any one of claims 1-7.

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