Method and device for suppressing free surface multiples of seabed node data

Abstract

The invention relates to the technical field of seismic exploration, and provides a seabed node data free surface multiple suppression method and device. The method comprises the following steps: interpolating uplink wave and downlink wave seabed node data; separating the multiples according to periodic characteristics of wave field incident angle changes; establishing a target function by adopting a sparse inversion method; and based on the objective function, solving an upgoing wave field which does not contain the free surface related multiples through a fast iteration shrinkage threshold so as to remove the free surface multiples. According to the method, the free surface multiples in the uplink wave field of the seabed node data in the ultra-shallow water area can be effectively removed, and the primary wave imaging quality of seismic data is obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of seismic exploration, and particularly to a method for suppressing free surface multiples in seafloor node data, a device for suppressing free surface multiples in seafloor node data, and a computer device. Background Art

[0002] Compared with traditional narrow azimuth (NAZ) streamer acquisition, ocean bottom node (OBN) exploration has the advantages of flexible acquisition construction, ultra-long offset receiving, all-round, high coverage, repeatability, wide frequency, and multi-component. It plays an important role in the exploration of complex offshore oil and gas fields and the development of oil and gas reservoirs, and gradually replaces streamer acquisition.

[0003] In ocean bottom node (OBN) acquisition, hydrophones and land-based three-component geophones are buried on the ocean floor to record pressure and velocity data. The hydrophone P-component geophone is a pressure geophone without directivity; the land-based three-component geophone is a velocity geophone with directivity, including three components of X, Y, and Z, where the Z-component is perpendicular to the seafloor to receive longitudinal wave signals. Wavefield separation can be divided into up-going waves and down-going waves through the hydrophone P-component and the land-based Z-component. However, there are still a large number of multiples related to the free surface (sea surface) in the up-going wavefield, including source ghosts, water layer multiples, and free surface multiples related to reflection layers, etc. These multiples seriously affect the quality of exploration data, resulting in structural illusions and increasing exploration risks. Therefore, they must be removed in data processing.

[0004] The prior art uses up-down wavefield deconvolution technology, which can better remove the free surface multiples in the up-going wavefield in waters where the sea water is relatively deep (more than 20 meters) and the seafloor is relatively flat. However, in the processing of OBN data collected in ultra-shallow waters (1 - 20 meters), the number of direct wave (down-going wave) channels is very scarce and is masked by strong energy noise. At the same time, the wavefield propagation distance is comparable to the size of the gun array, and the wavefield recorded by the seafloor nodes is extremely complex. The imaging accuracy of the up-going wave of OBN data in ultra-shallow waters will be severely affected by multiples, and the existing up-down wavefield deconvolution technology often fails to achieve ideal results. Summary of the Invention

[0005] To solve the defects of the prior art, the present invention provides a method for suppressing free surface multiples in seafloor node data, which effectively removes the free surface multiples in the up-going wavefield of seafloor node data in ultra-shallow waters.

[0006] On the one hand, the present invention provides a method for suppressing free surface multiples in seafloor node data, including:

[0007] Interpolating the up-going wave and down-going wave seafloor node data;

[0008] Separate the multiple waves according to the periodic characteristics of the incident angle variation of the wave field;

[0009] Establish an objective function using the sparse inversion method;

[0010] Based on the objective function, solve the up-going wave field without free-surface-related multiple waves through fast iterative shrinkage thresholding to remove free-surface multiple waves.

[0011] In the embodiment of the present invention, the interpolation of the up-going wave and down-going wave seafloor node data includes: performing high-density interpolation on the up-going wave and down-going wave seafloor node data in the frequency-wavenumber domain using Fourier transform.

[0012] In the embodiment of the present invention, the wave field with sparse spatial sampling is forward-transformed from the sparse spatio-temporal domain to the FKK domain; relevant threshold values are set, and the effective information of the wave field is extracted through an iterative method for high-density interpolation; the up-going wave and down-going wave are inverse-transformed back to the spatio-temporal domain with high-density spatial sampling.

[0013] In the embodiment of the present invention, the separation of the multiple waves according to the periodic characteristics of the incident angle variation of the wave field includes: performing three-dimensional Taup transformation on the P component and Z component of the multiple waves respectively to separate the multiple waves according to the periodic characteristics of the incident angle variation of the wave field.

[0014] In the embodiment of the present invention, the formula for the three-dimensional Taup transformation is:

[0015]

[0016] In the formula,

[0017] τ = t - px;

[0018]

[0019] where V * represents the apparent velocity, θ represents the incident angle of the seismic wave ray, V represents the wave velocity in the medium, t is the time-domain sample point, P x is the P-value sampling in the x direction, P y is the P-value sampling in the y direction, and the P value represents the incident angle of the wave field.

[0020] In the embodiment of the present invention, the objective function established using the sparse inversion method is:

[0021]

[0022] where,

[0023] U = D * r;

[0024] r i+1 = T τ [ri +D H (U - Dr i )];

[0025] U represents the up - going wavefield, D represents the down - going wavefield, r is the sequence of subsurface reflection coefficients, λ is the regularization parameter, T τ is the transform - domain threshold operator, and i refers to the i - th iteration.

[0026] In an embodiment of the present invention, the method for suppressing free - surface multiples of seafloor node data further includes: inverse - transforming the up - going wavefield after multiple - wave suppression back to the time domain to obtain the up - going wavefield with free - surface - related multiples attenuated in the time domain.

[0027] In an embodiment of the present invention, the up - going wavefield after multiple - wave suppression is inverse - transformed back to the time domain through three - dimensional Taup inverse transformation to obtain the Vz noise model in the time domain;

[0028] The formula for the three - dimensional Taup inverse transformation is:

[0029]

[0030] where t is the time - domain sample point, P x is the P - value sampling in the x - direction, P y is the P - value sampling in the y - direction, and the P - value represents the incident angle of the wavefield.

[0031] On the other hand, the present invention provides a device for suppressing free - surface multiples of seafloor node data, including:

[0032] An interpolation module for interpolating the up - going and down - going seafloor node data;

[0033] A multiple - wave separation module for separating multiples according to the periodic characteristics of the change in the incident angle of the wavefield;

[0034] A multiple - wave suppression module for establishing an objective function using the sparse inversion method and solving for the up - going wavefield without free - surface - related multiples based on the objective function through fast iterative shrinkage thresholding to remove free - surface multiples.

[0035] The present invention also provides a computer device, including: a memory, a processor, and a computer program, where the computer program is stored in the memory and is configured to be executed by the processor to implement the above - mentioned method for suppressing free - surface multiples of seafloor node data.

[0036] Based on the model that the downward wavefield convolution of OBN data with the subsurface reflection coefficient sequence is equivalent to the upward wavefield, after high-density interpolation of OBN data, the upward and downward wavefield information is comprehensively utilized in the high-precision three-dimensional TauP domain. A relevant objective function is established through the sparse inversion method, and the upward wavefield without free-surface-related multiple waves is solved by the fast iterative shrinkage threshold method. This avoids the instability caused by signal division in traditional deconvolution algorithms, can effectively remove the free-surface multiple waves in the upward wavefield of OBN data in ultra-shallow waters, provides a true and reliable data basis for geological research, and reduces exploration risks.

[0037] Other features and advantages of the technical solution of the present invention will be described in detail in the following specific implementation part. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0039] Figure 1 is a flowchart of the method for suppressing free-surface multiple waves of seafloor node data provided by an embodiment of the present invention;

[0040] Figure 2 is a schematic diagram of multiple waves in the spatio-temporal domain (left) and multiple waves in the Taup domain (right);

[0041] Figure 3 is a schematic diagram of the trace gather before multiple wave attenuation (left) and the trace gather after multiple wave attenuation (right);

[0042] Figure 4 is a schematic diagram of the stacked section before multiple wave attenuation;

[0043] Figure 5 is a schematic diagram of the stacked section after multiple wave attenuation;

[0044] Figure 6 is a comparison diagram of the section after multiple wave attenuation by the traditional wave suppression method of actual data and the section after multiple wave attenuation of the present invention;

[0045] Figure 7 is a comparison diagram of the application effects of the multiple wave suppression method of the present invention in actual production projects. DETAILED DESCRIPTION OF THE INVENTION

[0046] In order to make the technical solutions and advantages in the embodiments of the present invention clearer and more understandable, the following further details the exemplary embodiments of the present invention with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than an exhaustive list of all embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0047] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings. These are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically and clearly defined.

[0048] As introduced in the background art, the prior art uses the up-down wavefield deconvolution technique, which can better remove the free surface multiples of the up-going wavefield in waters where the sea water is relatively deep (more than 20 meters) and the seabed is relatively flat. However, in the processing of OBN data collected in ultra-shallow waters (1 - 20 meters), the number of direct wave (down-going wave) channels is very scarce and is masked by strong energy noise. At the same time, the wavefield propagation distance is comparable to the size of the gun array, and the wavefield recorded by the seafloor nodes is extremely complex. The imaging accuracy of the up-going wavefield of OBN data in ultra-shallow waters will be severely affected by multiples, and the existing up-down wavefield deconvolution techniques often fail to achieve ideal results.

[0049] The embodiments of the present invention provide a method for suppressing free surface multiples of seafloor node data. Based on the model that the convolution of the down-going wavefield of OBN data with the underground reflection coefficient sequence is equivalent to the up-going wavefield, after high-density interpolation of the OBN data, the up-going wavefield and down-going wavefield information are comprehensively utilized in the high-precision three-dimensional TauP domain. A relevant objective function is established through the sparse inversion method, and the up-going wavefield without free surface-related multiples is solved by the fast iterative shrinkage threshold method, avoiding the instability caused by signal division in traditional deconvolution algorithms. It can effectively remove the free surface multiples in the up-going wavefield of OBN data in ultra-shallow waters, provide a true and reliable data basis for geological research, and reduce exploration risks.

[0050] Figure 1 is the flowchart of the free surface multiple suppression method for seafloor node data provided by the embodiments of the present invention. As Figure 1 shown, the free surface multiple suppression method for seafloor node data provided by this embodiment includes the following steps:

[0051] S110, interpolate the seafloor node data of the up-going wave and the down-going wave;

[0052] S120, separate the multiples according to the periodic characteristics of the wavefield incident angle change;

[0053] S130, establish an objective function using the sparse inversion method, and based on the objective function, solve the up-going wavefield without free surface-related multiples through fast iterative shrinkage thresholding to remove the free surface multiples;

[0054] S140, inverse-transform the up-going wavefield after multiple suppression back to the time domain.

[0055] In the above step S110, use the Fourier transform to perform high-density interpolation on the seafloor node data of the up-going wave and the down-going wave in the frequency-wavenumber domain (FK domain), and interpolate both the up-going wavefield and the down-going wavefield into high-density spatial sampling (the sampling interval is less than or equal to 6.25 meters).

[0056] Specifically, forward-transform the wavefield with sparse spatial sampling from the sparse spatio-temporal domain to the FKK domain, set relevant threshold values, extract the effective information of the wavefield through an iterative method, and then inverse-transform it back to the spatio-temporal domain with high-density spatial sampling to complete the high-density interpolation process. That is, perform forward transformation, high-density interpolation, and inverse transformation on the up-going wave and the down-going wave respectively. The formula for the forward transformation is as follows:

[0057]

[0058] The formula for the inverse transformation is as follows:

[0059]

[0060] Among them, in the forward transformation, x represents the sampling point in the time domain or the spatial domain, and in the inverse transformation, k represents the sampling point in the frequency domain or the beam domain.

[0061] In the above step S120, use the Taup transformation to separate the multiples according to the periodic characteristics caused by the change of the wavefield incident angle. Specifically, it includes: perform three-dimensional Taup transformation on the P component and the Z component of the multiples respectively. Taking the two-dimensional Taup transformation as an example, its formula is:

[0062]

[0063] In formula (3),

[0064] τ = t - px; (4)

[0065]

[0066] Among them, V * represents the apparent velocity, θ represents the incident angle of the seismic wave ray, and V represents the wave velocity in the medium;

[0067] It is extended to three-dimensional Taup transformation, and its formula is:

[0068]

[0069] In formula (6),

[0070] τ = t - px;

[0071]

[0072] Among them, V * represents the apparent velocity, θ represents the incident angle of the seismic wave ray, V represents the wave velocity in the medium, t is the sample point in the time domain, and P x is the P value sampling in the x direction, P y is the P value sampling in the y direction, and the P value represents the incident angle of the wave field.

[0073] In the above step S130, in the three-dimensional Taup domain, the sparse inversion method is adopted to establish the relevant objective function, and the up-going wave field without free surface-related multiples is solved by fast iterative shrinkage threshold, effectively avoiding the instability caused by signal division in the traditional up-down wave field deconvolution algorithm. The objective function established by the sparse inversion method is:

[0074] U = D * r; (7)

[0075]

[0076] r i+1 = T τ [r i + D H (U - Dr i )]; (9)

[0077] Formula (7) is obtained based on the model that the down-going wave field convolution of OBN data with the subsurface reflection coefficient sequence is equivalent to the up-going wave field, where U represents the up-going wave field, D represents the down-going wave field, and r is the subsurface reflection coefficient sequence; it can be deduced from formula (7):

[0078] Formula (8) is the objective function, and λ is the regularization parameter;

[0079] In formula (9), T τ is the transform domain threshold operator, and i refers to the i-th iteration.

[0080] In the above step S140, the up-going wavefield after multiple suppression is inversely transformed back to the time domain through three-dimensional Taup inverse transformation to obtain the Vz noise model in the time domain, thereby obtaining the up-going wavefield after free-surface-related multiple attenuation in the time domain. The formula for three-dimensional Taup inverse transformation is as follows:

[0081]

[0082] In Equation (10), t is the sample point in the time domain, P x is the P-value sampling in the x direction, P y is the P-value sampling in the y direction, and the P value represents the incident angle of the wavefield.

[0083] In a specific application scenario, the multiples are separated according to the incident angle of the wavefield using Taup transformation. As shown in Figure 2 , the left part is the multiple in the space-time domain, and the right part is the multiple in the Taup domain. The test results based on theoretical data are shown in Figure 3 . The left part is the gather before multiple attenuation, and the right part is the gather after multiple attenuation. The stacked section before multiple attenuation is shown in Figure 4 . The stacked section after multiple attenuation is shown in Figure 5 . It can be seen from the comparison between Figure 4 and Figure 5 that the imaging effect after multiple attenuation is better. Based on actual data, the test results of using the traditional multiple suppression method and the multiple suppression method of the present invention are compared as shown in Figure 6 . The left part in the figure is the section after multiple attenuation by the traditional wave suppression method, and the right part in the figure is the section after multiple attenuation by the present invention. In an actual production project, the application effect of using the multiple suppression method of the present invention is compared as shown in Figure 7 . The upper part in the figure is the section before multiple attenuation, and the lower part in the figure is the section after multiple attenuation. It can be seen from Figure 7 that the imaging effect after multiple attenuation is better.

[0084] After suppressing multiples using the method provided in the above embodiment, all the relevant multiple noises brought by the strong-reflecting sea surface are effectively attenuated, significantly improving the imaging quality of the primary waves in seismic data, obtaining a processing result that can accurately reflect the underground geological conditions, providing a high-fidelity data basis for well location determination in interpretation, effectively improving the drilling success rate, and reducing the exploration risk.

[0085] An embodiment of the present invention also provides a device for suppressing free-surface multiple waves in subsea node data, including: an interpolation module, a multiple-wave separation module, and a multiple-wave suppression module. The interpolation module is used to interpolate the up-going wave and down-going wave subsea node data. The multiple-wave separation module is used to separate the multiple waves according to the periodic characteristics of the change in the incident angle of the wave field. The multiple-wave suppression module is used to establish an objective function by using the sparse inversion method, and based on the objective function, solve the up-going wave field without free-surface related multiple waves through fast iterative shrinkage thresholding to remove the free-surface multiple waves.

[0086] In one embodiment, the interpolation module performs high-density interpolation on the up-going wave and down-going wave subsea node data in the frequency-wavenumber domain (FK domain) by using Fourier transform, and interpolates both the up-going wave field and the down-going wave field into high-density spatial sampling (the sampling interval is less than or equal to 6.25 meters).

[0087] Specifically, the wave field of sparse spatial sampling is directly transformed from the sparse spatio-temporal domain to the FKK domain, relevant threshold values are set, the effective information of the wave field is extracted through an iterative method, and then it is inversely transformed back to the spatio-temporal domain of high-density spatial sampling to complete the high-density interpolation process. That is, the forward transformation, high-density interpolation, and inverse transformation are respectively performed on the up-going wave and the down-going wave. The formula for the forward transformation is as follows:

[0088]

[0089] The formula for the inverse transformation is as follows:

[0090]

[0091] Among them, in the forward transformation, x represents the sampling point in the time domain or the spatial domain, and in the inverse transformation, k represents the sample point in the frequency domain or the beam domain.

[0092] In one embodiment, the multiple-wave separation module uses the Taup transformation to separate the multiple waves according to the periodic characteristics caused by the change in the incident angle of the wave field. Specifically, it includes: performing three-dimensional Taup transformation on the P component and Z component of the multiple waves respectively, and its formula is:

[0093]

[0094] In formula (6),

[0095] τ = t - px;

[0096]

[0097] where V * represents the apparent velocity, θ represents the incident angle of the seismic wave ray, V represents the wave velocity in the medium, t is the sample point in the time domain, P x is the P value sampling in the x direction, P yP-value sampling in the y direction, where the P-value represents the incident angle of the wavefield.

[0098] In one embodiment, the multiple suppression module adopts a sparse inversion method in the 3D Taup domain, establishes a relevant objective function, and solves the up-going wavefield without free-surface-related multiples through fast iterative shrinkage thresholding, effectively avoiding the instability caused by signal division in the traditional up- and down-going wavefield deconvolution algorithm. The objective function established by the sparse inversion method is:

[0099] U = D * r; (7)

[0100]

[0101] r i+1 = T τ [r i + D H (U - Dr i )]; (9)

[0102] Equation (7) is obtained based on the model that the convolution of the down-going wavefield with the subsurface reflection coefficient sequence in OBN data is equivalent to the up-going wavefield, where U represents the up-going wavefield, D represents the down-going wavefield, and r is the subsurface reflection coefficient sequence; it can be deduced from Equation (7) that:

[0103] Equation (8) is the objective function, and λ is the regularization parameter;

[0104] In Equation (9), T τ is the transform-domain threshold operator, and i refers to the i-th iteration.

[0105] The up-going wavefield after multiple suppression is inverse-transformed back to the time domain through 3D Taup inverse transform to obtain the Vz noise model in the time domain, thereby obtaining the up-going wavefield after attenuation of free-surface-related multiples in the time domain. The formula for 3D Taup inverse transform is:

[0106]

[0107] In Equation (10), t is the time-domain sample point, P x is the P-value sampling in the x direction, P y is the P-value sampling in the y direction, and the P-value represents the incident angle of the wavefield.

[0108] The embodiment of the present invention also provides a computer device, including: a memory, a processor, and a computer program, where the computer program is stored in the memory and is configured to be executed by the processor to implement the above-mentioned method for suppressing free-surface multiples of seafloor node data.

[0109] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The solutions in the embodiments of the present invention can be implemented in various computer languages. For example, object-oriented programming languages such as Java and interpreted scripting languages such as JavaScript, etc.

[0110] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each flow and / or block in the flowchart and / or block diagram, and the combination of flows and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for realizing the specified functions in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0111] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including instruction means, and the instruction means realizes the specified functions in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks. These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for realizing the specified functions in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0112] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made to these embodiments by those skilled in the art once they learn the basic inventive concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art can make various changes and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and its equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A method for suppressing free surface multiple waves of submarine node data, characterized in that, Comprising: Interpolating the up-going wave and down-going wave seafloor node data; Separating the multiple waves according to the periodic characteristics of the incident angle variation of the wave field; Establishing an objective function by using the sparse inversion method; Based on the objective function, solving the up-going wave field without the free surface-related multiple waves through fast iterative shrinkage thresholding to remove the free surface multiple waves.

2. The method for suppressing the free surface multiple waves of the subsea node data according to claim 1, wherein The interpolating the up-going wave and down-going wave seafloor node data comprises: Performing high-density interpolation on the up-going wave and down-going wave seafloor node data in the frequency-wavenumber domain by using Fourier transform.

3. The method for suppressing the free surface multiple of the subsea node data according to claim 2, characterized in that The performing high-density interpolation on the up-going wave and down-going wave seafloor node data in the frequency-wavenumber domain by using Fourier transform comprises: Forward-transforming the sparsely spatially sampled wave field from the sparse spatio-temporal domain to the FKK domain; Setting relevant threshold values, extracting the effective information of the wave field through an iterative manner, and performing high-density interpolation; Inverse-transforming the up-going wave and down-going wave back to the high-density spatially sampled spatio-temporal domain.

4. The method for suppressing the free surface multiple waves of the subsea node data according to claim 1, characterized in that The separating the multiple waves according to the periodic characteristics of the incident angle variation of the wave field comprises: Performing three-dimensional Taup transformation on the P component and Z component of the multiple waves respectively to separate the multiple waves according to the periodic characteristics of the incident angle variation of the wave field.

5. The method for suppressing free surface multiples of seafloor node data according to claim 4, wherein The formula of the three-dimensional Taup transformation is: Wherein, τ = t - px; Among them, V * represents the apparent velocity, θ represents the incident angle of the seismic wave ray, V represents the wave velocity in the medium, t is the sample point in the time domain, and P x is the P-value sampling in the x direction, and P y is the P-value sampling in the y direction. The P value represents the incident angle of the wave field.

6. The method for suppressing the free surface multiple waves of the subsea node data according to claim 1, wherein The objective function established by using the sparse inversion method is: Wherein, U = D * r; r i+1 = T τ [r i + D H (U - Dr i )]; U represents the up-going wavefield, D represents the down-going wavefield, r is the sequence of subsurface reflection coefficients, λ is the regularization parameter, and T τ is the transform-domain threshold operator, and i refers to the i-th iteration.

7. The method for suppressing the free surface multiple waves of the subsea node data according to claim 1, wherein The method further comprises: Inverse-transforming the up-going wave field after suppressing the multiple waves back to the time domain to obtain the up-going wave field with the free surface-related multiple waves attenuated in the time domain.

8. The method for suppressing free surface multiple waves of submarine node data according to claim 7, characterized in that The inverse-transforming the up-going wave field after suppressing the multiple waves back to the time domain comprises: Inverse-transforming the up-going wave field after suppressing the multiple waves back to the time domain through three-dimensional Taup inverse transformation to obtain the Vz noise model in the time domain; The formula of the three-dimensional Taup inverse transformation is: where t is the sample point in the time domain, and P x is the P-value sampling in the x direction, and P y is the P-value sampling in the y direction. The P value represents the incident angle of the wave field.

9. An undersea node data free surface multiple suppression device, characterized in that Comprising: An interpolation module for interpolating the up-going wave and down-going wave seafloor node data; A multiple wave separation module for separating the multiple waves according to the periodic characteristics of the incident angle variation of the wave field; A multiple wave suppression module for establishing an objective function by using the sparse inversion method and solving the up-going wave field without the free surface-related multiple waves based on the objective function through fast iterative shrinkage thresholding to remove the free surface multiple waves.

10. A computer device, characterized in that, Comprising: A memory; A processor; And A computer program; Wherein, the computer program is stored in the memory and is configured to be executed by the processor to implement the method for suppressing the free surface multiple waves of the seafloor node data according to any one of claims 1 - 8.

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