Reverse time offset method and electronic equipment

Abstract

This application relates to the field of geological exploration technology and discloses a reverse-time migration method and electronic equipment. The reverse-time migration method includes: acquiring seismic exploration data in a viscoelastic medium; calculating a compensated backpropagation wavefield based on the inverse dispersion acoustic wave equation transformed to the frequency domain and the seismic exploration data; and obtaining a compensated reverse-time migration image based on the compensated forward propagation wavefield and the compensated backpropagation wavefield. By acquiring seismic exploration data in a viscoelastic medium, calculating a compensated backpropagation wavefield based on the inverse dispersion acoustic wave equation transformed to the frequency domain and the seismic exploration data, and obtaining a compensated reverse-time migration image based on the compensated forward propagation wavefield and the compensated backpropagation wavefield, this application can compensate for energy loss caused by absorption attenuation during the reverse-time migration process while suppressing high-frequency noise, ensuring the stability of the reverse-time migration results.

Description

Technical Field

[0001] The embodiments of this application relate to the field of geological exploration technology, and in particular to a reverse time migration method and electronic equipment. Background Technology

[0002] Reverse time migration (RTM) is a seismic wave migration imaging method that, theoretically, can achieve energy relocation for any type of wave group without limitations on the imaging angle. With the rapid development of computer technology, RTM, due to its unique imaging advantages in complex geological regions, has become an indispensable technique in the field of migration imaging in recent years.

[0003] However, in actual seismic exploration, because the underground medium is closer to a viscoelastic medium than a perfectly elastic medium, seismic waves will be accompanied by significant amplitude attenuation and phase changes during propagation, which will lead to a decrease in the resolution of the reverse time migration results.

[0004] Existing techniques typically employ an approximate method of establishing a fractional-order Laplace operator wave equation based on a constant Q model to compensate for the absorption attenuation effect, thereby improving the resolution of the reverse-time migration results. However, this method cannot guarantee the stability of the reverse-time migration results and makes it difficult to suppress high-frequency noise while compensating for the effective high-frequency signal. Summary of the Invention

[0005] This application provides a reverse time migration method and electronic device to compensate for energy loss caused by absorption attenuation during the reverse time migration process while suppressing high-frequency noise, thereby ensuring the stability of the reverse time migration result.

[0006] The embodiments of this application provide the following technical solutions:

[0007] In a first aspect, embodiments of this application provide a reverse-time offset method, including:

[0008] Acquire seismic exploration data in viscoelastic media;

[0009] Based on the inverse dispersion acoustic wave equation transformed to the frequency domain and seismic exploration data, the compensated reverse propagation wave field is calculated.

[0010] Based on the compensated forward propagation wavefield and the compensated reverse propagation wavefield, the compensated reverse time migration image is obtained.

[0011] In some embodiments, before calculating the compensated back propagation wavefield based on the inverse dispersion acoustic wave equation transformed to the frequency domain and seismic exploration data, the method further includes:

[0012] Establish the equation for the inverse dispersion sound wave;

[0013] The equations for inverse-frequency dispersion acoustic waves are transformed to the frequency domain to extrapolate the wavefield of seismic waves.

[0014] The equations for inverse dispersion acoustic waves transformed into the frequency domain include:

[0015]

[0016] Where σ is a mathematical value used to quantify the degree of stability and instability, ω is the angular frequency, v is the velocity, x is the spatial abscissa, z is the spatial ordinate, U is the displacement, and f is the source function. In some embodiments, the compensated back propagation wavefield is calculated based on the inverse dispersion acoustic wave equation transformed to the frequency domain and seismic exploration data, including:

[0017] During the wavefield extrapolation process, the seismic wave is subjected to absorption attenuation compensation and discretization processing based on the inverse dispersion acoustic wave equation transformed to the frequency domain, and the compensated wavefield is obtained.

[0018] If the source function in the compensated wavefield is the complex conjugate of the frequency domain seismic record, then the seismic exploration data is substituted into the compensated wavefield to calculate the compensated back propagation wavefield.

[0019] In some embodiments, during wavefield extrapolation, the seismic wave is subjected to absorption attenuation compensation and discretization processing based on the inverse dispersion acoustic wave equation transformed to the frequency domain to obtain the compensated wavefield, including:

[0020] Based on the inverse dispersion acoustic wave equation transformed to the frequency domain, the attenuation-dispersion model, and the optimal nine-point difference algorithm, the seismic wave is subjected to absorption attenuation compensation and discretization processing to obtain the compensated wave field.

[0021] In some embodiments, the method further includes:

[0022] If the source function in the compensated wavefield is a source wavelet, then the compensated wavefield is a compensated forward propagation wavefield.

[0023] In some embodiments, the attenuation-dispersion model includes:

[0024]

[0025] Where v(ω) is the velocity, v is the phase velocity at the reference angular frequency ω0, π is pi, Q is the quality factor, ω is the angular frequency, ω0 is the reference angular frequency, and j is a complex number.

[0026] In some embodiments, the compensated wave field includes:

[0027] A Q+ (v,ω)U(ω)=f(ω)

[0028] Among them, A Q+ (v,ω) is the impedance matrix, U(ω) is the displacement, and f(ω) is the source function. In some embodiments, the compensated forward propagation wavefield includes:

[0029] S c (ω)=(A Q+ (v,ω)) -1 f(ω)

[0030] Among them, S c (ω) represents the compensated propagating wave field, A Q+ (v,ω) is the impedance matrix, and f(ω) is the source function.

[0031] In some embodiments, the compensated antipropagating wavefield includes:

[0032] R c (ω)=(A Q+ (v,ω)) -1 (r Q- (ω)) *

[0033] Among them, R c (ω) represents the compensated anti-propagating wavefield, A Q+ (v,ω) is the impedance matrix, r Q- (ω) represents the seismic record in the viscoelastic medium.

[0034] In some embodiments, a compensated reverse-time migration image is obtained based on the compensated forward propagation wavefield and the compensated reverse propagation wavefield, including:

[0035] I c (x)=ω 2 S c (ω)R c (ω)

[0036] Among them, I c (x) is the compensated reverse-time offset image, ω is the angular frequency, and S c (ω) represents the compensated propagating wave field, R c (ω) represents the compensated reverse propagation wave field.

[0037] Secondly, embodiments of this application provide an electronic device, including:

[0038] At least one processor; and

[0039] A memory that is communicatively connected to at least one processor; wherein,

[0040] The memory stores instructions that can be executed by at least one processor, which enables the at least one processor to perform the reverse time offset method as described in the first aspect.

[0041] Thirdly, embodiments of this application provide a non-volatile computer-readable storage medium storing computer-executable instructions for causing an electronic device to perform the reverse time offset method as described in the first aspect.

[0042] The beneficial effects of the embodiments of this application are as follows: Unlike existing technologies, the embodiments of this application provide a reverse-time migration method, including: acquiring seismic exploration data in a viscoelastic medium; calculating a compensated backpropagation wavefield based on the inverse dispersion acoustic wave equation transformed to the frequency domain and the seismic exploration data; and obtaining a compensated reverse-time migration image based on the compensated forward propagation wavefield and the compensated backpropagation wavefield. By acquiring seismic exploration data in a viscoelastic medium, calculating a compensated backpropagation wavefield based on the inverse dispersion acoustic wave equation transformed to the frequency domain and the seismic exploration data, and obtaining a compensated reverse-time migration image based on the compensated forward propagation wavefield and the compensated backpropagation wavefield, this application can compensate for energy loss caused by absorption attenuation during the reverse-time migration process while suppressing high-frequency noise, ensuring the stability of the reverse-time migration results. Attached Figure Description

[0043] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0044] Figure 1 This is a schematic diagram of an application environment provided in an embodiment of this application;

[0045] Figure 2 This is a flowchart illustrating a reverse-time offset method provided in an embodiment of this application;

[0046] Figure 3 yes Figure 2 A detailed flowchart of step S202 in the process;

[0047] Figure 4 yes Figure 3 A detailed flowchart of step S221 in the process;

[0048] Figure 5a This is a schematic diagram of a seismic record obtained by applying a velocity model according to an embodiment of this application;

[0049] Figure 5b This is a schematic diagram of a seismic record obtained by applying a quality factor model according to an embodiment of this application;

[0050] Figure 6a This is a schematic diagram of an acoustic wave equation simulating a seismic record, provided in an embodiment of this application;

[0051] Figure 6b This is a schematic diagram of an inverse dispersion acoustic wave equation simulating a seismic record, provided in an embodiment of this application;

[0052] Figure 7a This is a schematic diagram of a reverse time migration image obtained by performing conventional reverse time migration on a seismic record simulated by the acoustic equation, provided in an embodiment of this application;

[0053] Figure 7b This is a schematic diagram of a reverse time migration image obtained by performing conventional reverse time migration on a seismic record simulated by the inverse dispersion acoustic equation, as provided in an embodiment of this application.

[0054] Figure 7c This is a schematic diagram of a reverse time migration image obtained by viscoelastic reverse time migration of a seismic record simulated by the inverse dispersion acoustic equation, provided in an embodiment of this application.

[0055] Figure 7d This is a schematic diagram of a reverse time-migrated image obtained by using the reverse time-migration method of the inverse dispersion acoustic equation to perform reverse time-migration on a seismic record.

[0056] Figure 8 This is a schematic diagram of single-channel contrast of the image in Figure 7;

[0057] Figure 9 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Detailed Implementation

[0058] To facilitate understanding of this application, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as "connected to" another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this specification are for illustrative purposes only.

[0059] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0060] To facilitate understanding of the methods provided in the embodiments of this application, the terms used in the embodiments of this application will first be introduced:

[0061] (1) Equation of sound waves

[0062] The acoustic wave equation is the scalar part of the elastic wave equation, used to describe the spatiotemporal laws governing the propagation of longitudinal wave displacement in an elastic medium.

[0063] (2) Absorption attenuation effect

[0064] Absorption attenuation effect refers to the attenuation of seismic wave amplitude and phase distortion caused by the viscoelasticity of the medium.

[0065] (3) Reverse time offset

[0066] Reverse time migration (RTM) is a seismic wave migration imaging method. Because the acquisition methods used in seismic exploration result in inconsistencies between the phase axes in the raw data and the actual interfaces, RTM is used to correct these inconsistencies. RTM generally involves three steps: ① forward extrapolation of the wavefield using finite difference or finite element methods; ② backward extrapolation using seismic data as the vibration source; ③ correcting the phase axes using cross-correlation or excitation time imaging conditions.

[0067] Before introducing the embodiments of this application, a brief introduction will be given to the reverse time offset method known to the inventors of this application, so as to facilitate the understanding of the embodiments of this application later.

[0068] Traditional wave equations treat the subsurface medium as an elastic body, while the actual subsurface medium is closer to a viscoelastic medium. Therefore, during seismic wave propagation, its amplitude undergoes non-geometric diffusion, resulting in amplitude attenuation, with higher frequency components attenuating more than lower frequency components. Furthermore, the propagation speeds of different frequency components differ, causing phase distortion in the seismic waves. These phenomena ultimately lead to reduced resolution in seismic exploration data processing (such as reverse time migration). Therefore, to improve the resolution of seismic exploration data, compensation for absorption attenuation effects is necessary.

[0069] In some reverse-time migration methods, absorption attenuation compensation during the reverse-time migration process is achieved by establishing a model (such as the generalized standard linear body model) using one or more springs and dampers connected in series and parallel, deriving the viscoelastic wave equation based on this model, and then using this equation for compensation. A drawback of these equations is that the amplitude attenuation effect and velocity dispersion effect cannot be decoupled, leading to a change in phase velocity while the amplitude is compensated, resulting in phase distortion on the in-phase axis of the final migration profile. Least-squares reverse-time migration based on these equations can avoid this phenomenon, but multiple iterations significantly increase the computation time.

[0070] In some reverse-time migration methods, absorption attenuation compensation during the reverse-time migration process is achieved by approximating a fractional-order Laplace wave equation based on a constant Q model. While this equation can decouple the amplitude attenuation effect and the velocity dispersion effect, it is not thorough enough. Furthermore, to ensure the stability of the compensation, high-frequency noise needs to be removed in the frequency wavenumber domain, which increases the computation time.

[0071] To address the aforementioned issues, this application provides a reverse time migration method and electronic device to compensate for energy loss caused by absorption attenuation during the reverse time migration process while suppressing high-frequency noise, ensuring the stability of the reverse time migration results, and improving the resolution of seismic exploration data.

[0072] The technical solution of this application is described in detail below with reference to the accompanying drawings:

[0073] Please see Figure 1 , Figure 1 This is a schematic diagram of an application environment provided in an embodiment of this application;

[0074] like Figure 1 As shown, the application environment 100 includes: a seismic data acquisition device 10 and electronic equipment 20. The network of the seismic data acquisition device 10 and electronic equipment 20 includes wired and / or wireless networks. It is understood that the network includes wireless networks such as 2G, 3G, 4G, 5G, wireless LAN, and Bluetooth, and may also include wired networks such as serial cables and network cables.

[0075] In this embodiment, the seismic data acquisition device 10 is communicatively connected to an electronic device 20, used to acquire seismic exploration data in a viscoelastic medium, i.e., subsurface medium, and to transmit the seismic exploration data to the electronic device 20. In this embodiment, the seismic data acquisition device 10 includes, but is not limited to, a seismic detector and a seismic exploration instrument.

[0076] In this embodiment, the electronic device 20 is communicatively connected to the seismic data acquisition device 10. It acquires seismic exploration data in a viscoelastic medium transmitted by the seismic data acquisition device 10 and obtains a compensated reverse-time migration image based on the seismic exploration data and the inverse dispersion acoustic wave equation transformed to the frequency domain. For example, based on the seismic exploration data and the inverse dispersion acoustic wave equation transformed to the frequency domain, a compensated backpropagation wavefield is calculated, and a compensated reverse-time migration image is obtained based on the compensated forward propagation wavefield and the compensated backpropagation wavefield. In this embodiment, the electronic device 20 includes, but is not limited to, mobile electronic devices such as laptops, handheld computers, and ultra-mobile personal computers (UMPCs), and non-mobile electronic devices such as servers and network-attached storage (NAS).

[0077] Please see Figure 2 , Figure 2 This is a flowchart illustrating a reverse-time offset method provided in an embodiment of this application;

[0078] This time-off method is applied to electronic devices, such as terminals or servers. Specifically, the execution subject of this time-off method is one or at least two processors of the electronic device.

[0079] like Figure 2 As shown, the reverse time offset method includes:

[0080] Step S201: Obtain seismic exploration data in viscoelastic media;

[0081] Specifically, the electronic device receives seismic exploration data in the viscoelastic medium, i.e., the subsurface medium, sent by the seismic data acquisition device. This seismic exploration data in the viscoelastic medium is acquired by the seismic data acquisition device at the receiving point.

[0082] In this embodiment of the application, after acquiring seismic exploration data in a viscoelastic medium, the method further includes:

[0083] Wavefield extrapolation of seismic waves is performed in the frequency domain using the inverse dispersion acoustic wave equation.

[0084] Specifically, the wavefield extrapolation of seismic waves in the frequency domain is performed using the inverse dispersion acoustic wave equation, including steps S1-S2, as follows:

[0085] Step S1: Establish the equation for the inverse dispersion acoustic wave;

[0086] Specifically, the equations for inverse-dispersion acoustic waves include:

[0087]

[0088] Where x represents the horizontal coordinate of space, z represents the vertical coordinate of space, u(t) represents the displacement, σ represents the mathematical value used to quantify the degree of stability and instability, v represents the velocity, t represents the time, and f represents the source function.

[0089] In this embodiment, σ is a positive real number. By adjusting its size, instability can be suppressed. When σ is set to 0, the anti-dispersion acoustic wave equation degenerates into the traditional acoustic wave equation.

[0090] Step S2: Transform the inverse dispersion acoustic wave equation to the frequency domain to extrapolate the wavefield of the seismic wave;

[0091] Specifically, the equations for inverse dispersion acoustic waves transformed into the frequency domain include:

[0092]

[0093] Where σ is a mathematical value used to quantify the degree of stability and instability, ω is the angular frequency, v is the velocity, x is the spatial abscissa, z is the spatial ordinate, U is the displacement, and f is the source function.

[0094] Understandably, compared to the traditional sound wave equation, the inverse dispersion sound wave equation introduces a regularization term, which in the frequency domain is:

[0095]

[0096] Where σ is a positive real number, and its size can be adjusted to suppress instability. When σ is set to 0, the inverse dispersion acoustic wave equation degenerates into the traditional acoustic wave equation.

[0097] It is understandable that high-frequency noise will also be amplified during the process of compensating for wave field energy loss. By introducing the regularization term in the anti-dispersion acoustic wave equation, the influence of high-frequency noise can be effectively suppressed, ensuring the stability of the compensation process.

[0098] In the embodiments of this application, by applying the anti-dispersion acoustic wave equation originally used to suppress numerical dispersion to the compensation process of viscoelastic reverse time migration, this application can ensure the stability of the compensation process without significantly increasing the computational overhead.

[0099] Step S202: Calculate the compensated back propagation wave field based on the inverse dispersion acoustic wave equation transformed to the frequency domain and the seismic exploration data.

[0100] For details, please refer to Figure 3 , Figure 3 yes Figure 2 A detailed flowchart of step S202 in the process;

[0101] like Figure 3As shown, step S202: Based on the inverse dispersion acoustic wave equation transformed to the frequency domain and the seismic exploration data, the compensated back propagation wave field is calculated, including:

[0102] Step S221: During the wave field extrapolation process, the seismic wave is subjected to absorption attenuation compensation and discretization processing according to the inverse dispersion acoustic wave equation transformed to the frequency domain to obtain the compensated wave field.

[0103] For details, please refer to Figure 4 , Figure 4 yes Figure 3 A detailed flowchart of step S221 in the process;

[0104] like Figure 4 As shown, step S221: During the wavefield extrapolation process, the seismic waves are subjected to absorption attenuation compensation and discretization processing to obtain the compensated wavefield, including:

[0105] Step S2211: Based on the inverse dispersion acoustic wave equation transformed to the frequency domain, the attenuation-dispersion model, and the optimal nine-point difference algorithm, the seismic wave is subjected to absorption attenuation compensation and discretization processing to obtain the compensated wave field.

[0106] Understandably, seismic waves propagating in the real underground medium typically exhibit frequency-dependent absorption attenuation and phase velocity dispersion. This attenuation effect is caused by the inelasticity of the strata. This intrinsic absorption attenuation effect inevitably reduces the resolution and fidelity of the seismic signal, thus affecting the accuracy of seismic migration imaging. Therefore, it is necessary to establish a suitable attenuation-dispersion model.

[0107] The commonly used attenuation-dispersion model to describe the absorption and attenuation effect of seismic waves is the Kolsky-Futterman model, which is expressed as follows:

[0108]

[0109] Where v(ω) is the velocity, v is the phase velocity at the reference angular frequency ω0, π is pi, Q is the quality factor, ω is the angular frequency, ω0 is the reference angular frequency, and j is a complex number.

[0110] in, This is the dispersion term, used to describe the dispersion effect of seismic waves in viscoelastic media. This is the attenuation term, used to describe the amplitude attenuation effect of seismic waves in a viscoelastic medium.

[0111] Understandably, when applying the Kolsky-Futterman model, the traditional wave equations based on standard linear bodies and Maxwell bodies cannot decouple the dispersion and attenuation terms in the Kolsky-Futterman model (equivalent to having to change the signs of the dispersion and attenuation terms simultaneously during the compensation process). This leads to changes in the phase velocity during the compensation process, resulting in phase distortion in the final result.

[0112] To address the aforementioned issues, this application proposes a novel attenuation-dispersion model that can compensate for energy loss caused by absorption attenuation during the reverse time migration process without changing the phase velocity, thus avoiding phase distortion in the compensation result.

[0113] Specifically, by reversing the sign of the attenuation term in the Kolsky-Futterman model while keeping the sign of the dispersion term unchanged, the attenuation-dispersion model in this application embodiment is obtained.

[0114] Specifically, the attenuation-dispersion model includes:

[0115]

[0116] Where v(ω) is the velocity, v is the phase velocity at the reference angular frequency ω0, π is pi, Q is the quality factor, ω is the angular frequency, ω0 is the reference angular frequency, and j is a complex number.

[0117] Please also refer to Figure 5a and Figure 5b , Figure 5a This is a schematic diagram of a seismic record obtained by applying a velocity model according to an embodiment of this application;

[0118] Figure 5b This is a schematic diagram of a seismic record obtained by applying a quality factor model according to an embodiment of this application;

[0119] in, Figure 5a The velocity model in the text is the velocity in the decay-dispersion model. Figure 5b The quality factor model in the model is the quality factor in the decay-dispersion model.

[0120] It is understandable that the attenuation-dispersion model is a mathematical model in which the two variables, velocity and quality factor, are not constants, and their spatial distributions are as follows: Figure 5a and Figure 5b As shown, specifically, earthquake records under corresponding conditions can be obtained by first setting up a velocity model and a quality factor model, and then using numerical simulation methods.

[0121] In this embodiment, by reversing the sign of the attenuation term in the Kolsky-Futterman model while keeping the sign of the dispersion term unchanged, the attenuation-dispersion model in this embodiment is obtained. This application can avoid phase distortion in the compensated reverse time-shifted image.

[0122] Furthermore, the inverse dispersion acoustic wave equation transformed to the frequency domain is discretized by combining the optimal nine-point difference algorithm.

[0123] Specifically, the optimal nine-point difference algorithm is used to solve partial differential equations, and its specific principle is as follows:

[0124] In the frequency domain, the traditional two-dimensional acoustic wave equation has the following form:

[0125]

[0126] Where x is the abscissa, z is the ordinate, v is the velocity, ω is the angular frequency, U(ω) is the displacement, and f(ω) is the source function.

[0127] The above equations are discretized using the optimal nine-point difference algorithm, including:

[0128]

[0129] Where a is a coefficient, U is displacement, v is velocity, ω is angular frequency, and f is the source function.

[0130] in,

[0131]

[0132]

[0133]

[0134] Among them, the optimization coefficients are a = 0.5641, c = 0.6248, and d = 0.09381.

[0135] Furthermore, the equation for the velocity of sound waves in an elastic medium... Substituting into the above formula, we obtain the simplified equation for sound waves:

[0136] A(v,ω)U(ω)=f(ω)

[0137] Where A(v,ω) is the impedance matrix, U(ω) is the displacement, and f(ω) is the source function.

[0138] In this embodiment, the elements of the impedance matrix are related to velocity, frequency, and differential method. The simplified acoustic wave equation can be solved using LU decomposition or iterative method. The solution is the wave field at each frequency, and the wave field at each time can be obtained by inverse Fourier transform.

[0139] Among them, LU factorization is a type of matrix factorization that can decompose a matrix into the product of a lower triangular matrix and an upper triangular matrix (sometimes the product of them and a permutation matrix); iterative methods are a class of methods that use recursive formulas or iterative algorithms to construct sequences to find approximate solutions to problems; inverse Fourier transform is the inverse of Fourier transform, used to convert images from the frequency domain to the spatial domain; in the embodiments of this application, iterative methods include, but are not limited to, Newton's method, steepest descent method, conjugate iteration method, variable scaling iteration method, least squares method, etc.

[0140] It is understandable that if the dispersion and attenuation terms in the Kolsky-Futterman model are removed, the Kolsky-Futterman model degenerates into the equation for the velocity of sound waves in an elastic medium.

[0141] In this embodiment of the application, the process of discretizing the inverse dispersion acoustic wave equation using the optimal nine-point difference algorithm is similar to the method for the traditional two-dimensional acoustic wave equation.

[0142] Specifically, the optimal nine-point difference algorithm is used to discretize the inverse dispersion acoustic wave equation transformed to the frequency domain, including:

[0143]

[0144] Where a is a coefficient. σ is the regularization term, ω is the mathematical value used to quantify the degree of stability and instability, ω is the angular frequency, v is the velocity, U is the displacement, v is the velocity, ω is the angular frequency, and f is the source function.

[0145] in,

[0146]

[0147]

[0148]

[0149] Among them, the optimization coefficients are a = 0.5641, c = 0.6248, and d = 0.09381.

[0150] Furthermore, the attenuation-dispersion model Substituting into the above formula, we obtain the compensated wave field.

[0151] Specifically, the compensated wave field includes:

[0152] A Q+ (v,ω)U(ω)=f(ω)

[0153] Among them, A Q+ (v,ω) is the impedance matrix, U(ω) is the displacement, and f(ω) is the source function.

[0154] In the embodiments of this application, by applying the attenuation-dispersion model and the optimal nine-point difference algorithm to process the anti-dispersion acoustic wave equation in the frequency domain, this application can achieve the decoupling of amplitude attenuation effect and velocity dispersion effect without approximation, making the reverse time migration result more accurate.

[0155] In this embodiment, by applying the attenuation-dispersion model and the optimal nine-point difference algorithm in the frequency domain to solve the anti-dispersion acoustic wave equation, this application can realize the extrapolation of the wave field of longitudinal waves in viscoelastic media.

[0156] In this embodiment of the application, the method further includes:

[0157] If the source function in the compensated wavefield is a source wavelet, then the compensated wavefield is a compensated forward propagation wavefield.

[0158] Specifically, the compensated forward propagation wave field includes:

[0159] S c (ω)=(A Q+ (v,ω)) -1 f(ω)

[0160] Among them, S c (ω) represents the compensated propagating wave field, A Q+ (v,ω) is the impedance matrix, and f(ω) is the source function.

[0161] Step S222: If the source function in the compensated wavefield is the complex conjugate of the frequency domain seismic record, then substitute the seismic exploration data into the compensated wavefield to calculate the compensated back propagation wavefield.

[0162] Specifically, the compensated antipropagation wave field includes:

[0163] R c (ω)=(A Q+ (v,ω)) -1 (r Q- (ω)) *

[0164] Among them, R c (ω) represents the compensated anti-propagating wavefield, A Q+ (v,ω) is the impedance matrix, r Q-(ω) represents the seismic record in the viscoelastic medium.

[0165] In this embodiment of the application, the seismic record in the viscoelastic medium, i.e., the seismic exploration data in the viscoelastic medium, is collected by the seismic data acquisition device at the receiving point.

[0166] Step S203: Based on the compensated forward propagation wave field and the compensated reverse propagation wave field, obtain the compensated reverse time offset image.

[0167] Specifically, the compensated reverse-time migration image is obtained by applying cross-correlation imaging conditions, which include:

[0168] I c (x)=ω 2 S c (ω)R c (ω)

[0169] Among them, I c (x) is the compensated reverse-time offset image, ω is the angular frequency, and S c (ω) represents the compensated propagating wave field, R c (ω) represents the compensated reverse propagation wave field.

[0170] In this embodiment, a compensated reverse-time migration image is obtained based on the compensated forward propagation wave field and the compensated reverse propagation wave field. This application can ensure the stability of the compensation process without filtering or constructing a stable compensation operator. Compared with the traditional acoustic wave equation reverse-time migration, the computational load of the reverse-time migration method in this application is significantly reduced.

[0171] Please also refer to Figure 6a and Figure 6b , Figure 6a This is a schematic diagram of an acoustic wave equation simulating a seismic record, provided in an embodiment of this application;

[0172] Figure 6b This is a schematic diagram of an inverse dispersion acoustic wave equation simulating a seismic record, provided in an embodiment of this application.

[0173] Please also refer to Figure 7a , Figure 7b , Figure 7c and Figure 7d , Figure 7a This is a schematic diagram of a reverse time migration image obtained by performing conventional reverse time migration on a seismic record simulated by the acoustic equation, provided in an embodiment of this application;

[0174] Figure 7b This is a schematic diagram of a reverse time migration image obtained by performing conventional reverse time migration on a seismic record simulated by the inverse dispersion acoustic equation, as provided in an embodiment of this application.

[0175] Figure 7c This is a schematic diagram of a reverse time migration image obtained by viscoelastic reverse time migration of a seismic record simulated by the inverse dispersion acoustic equation, provided in an embodiment of this application.

[0176] Figure 7d This is a schematic diagram of a reverse time-migrated image obtained by using the reverse time-migration method of the inverse dispersion acoustic equation to perform reverse time-migration on a seismic record simulated by the inverse dispersion acoustic equation, provided in an embodiment of this application.

[0177] like Figure 7a As shown, the reverse time migration image obtained by performing conventional reverse time migration on the seismic record simulated by the acoustic wave equation is used as the reference solution; as Figure 7b As shown, the reverse-time migration image obtained by performing conventional reverse-time migration on the seismic record simulated by the inverse dispersion acoustic equation, compared to... Figure 7a The image quality of the reverse-time migrated image is significantly degraded, reflecting the importance of absorption attenuation compensation during the migration process; for example... Figure 7c As shown, no high-frequency noise was suppressed during the viscoelastic reverse-time migration of the seismic record simulated by the inverse-frequency dispersion acoustic wave equation to obtain the reverse-time migration image; as Figure 7d As shown, the reverse time migration image obtained by using the reverse time migration method in this application to simulate earthquake records using the inverse dispersion acoustic wave equation effectively compensates for the absorption attenuation effect while suppressing high-frequency noise.

[0178] Please see Figure 8 , Figure 8 This is a schematic diagram of single-channel contrast of the image in Figure 7;

[0179] Specifically, Figure 8 yes Figure 7a That is, the reverse time migration image obtained by performing conventional reverse time migration on the seismic record simulated by the acoustic wave equation. Figure 7b That is, the reverse time migration image obtained by performing conventional reverse time migration on the seismic record simulated by the inverse dispersion acoustic wave equation. Figure 7c This is a schematic diagram of single-channel comparison of reverse time migration images obtained by viscoelastic reverse time migration of seismic records simulated by the inverse dispersion acoustic wave equation.

[0180] In this embodiment, a reverse-time migration method is provided, comprising: acquiring seismic exploration data in a viscoelastic medium; calculating a compensated backpropagation wavefield based on the inverse dispersion acoustic wave equation transformed to the frequency domain and the seismic exploration data; and obtaining a compensated reverse-time migration image based on the compensated forward propagation wavefield and the compensated backpropagation wavefield. By acquiring seismic exploration data in a viscoelastic medium, calculating a compensated backpropagation wavefield based on the inverse dispersion acoustic wave equation transformed to the frequency domain and the seismic exploration data, and obtaining a compensated reverse-time migration image based on the compensated forward propagation wavefield and the compensated backpropagation wavefield, this application can compensate for energy loss caused by absorption attenuation during the reverse-time migration process while suppressing high-frequency noise, ensuring the stability of the reverse-time migration results.

[0181] Please refer to the following: Figure 9 , Figure 9 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application;

[0182] like Figure 9 As shown, the electronic device 900 includes one or more processors 901 and a memory 902. Wherein, Figure 9 Take the 901 processor as an example.

[0183] Processor 901 and memory 902 can be connected via a bus or other means. Figure 9 Taking the example of a connection between China and Israel via a bus.

[0184] The processor 901 provides computing and control capabilities to control the electronic device 900 to perform corresponding tasks, such as controlling the electronic device 900 to perform the reverse time migration method in any of the above method embodiments, including: acquiring seismic exploration data in a viscoelastic medium; calculating a compensated back propagation wavefield based on the inverse dispersion acoustic wave equation transformed to the frequency domain and the seismic exploration data; and obtaining a compensated reverse time migration image based on the compensated forward propagation wavefield and the compensated back propagation wavefield.

[0185] By acquiring seismic exploration data in a viscoelastic medium, and calculating the compensated reverse propagation wave field based on the inverse dispersion acoustic wave equation transformed to the frequency domain and the seismic exploration data, and obtaining the compensated reverse propagation wave field and the compensated forward propagation wave field, this application can compensate for the energy loss caused by absorption attenuation during the reverse migration process while suppressing high-frequency noise, thus ensuring the stability of the reverse migration results.

[0186] Processor 901 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), a hardware chip, or any combination thereof; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The aforementioned PLD can be a complex programmable logic device (CPLD), a field-programmable gate array (FPGA), a generic array logic (GAL), or any combination thereof.

[0187] Memory 902, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as the program instructions / modules corresponding to the time-off method in the embodiments of this application. Processor 901 can implement the time-off method in any of the following method embodiments by running the non-transitory software programs, instructions, and modules stored in memory 902. Specifically, memory 902 may include volatile memory (VM), such as random access memory (RAM); memory 902 may also include non-volatile memory (NVM), such as read-only memory (ROM), flash memory, hard disk drive (HDD), solid-state drive (SSD), or other non-transitory solid-state storage devices; memory 902 may also include combinations of the above types of memory.

[0188] Memory 902 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, memory 902 may optionally include memory remotely located relative to processor 901, which can be connected to processor 901 via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0189] One or more modules are stored in memory 902. When executed by one or more processors 901, they perform the reverse time offset method in any of the above method embodiments, for example, the method described above. Figure 2 The steps shown.

[0190] In this embodiment, the electronic device 900 may also have wired or wireless network interfaces, keyboards, and input / output interfaces for input and output. The electronic device 900 may also include other components for implementing device functions, which will not be described in detail here.

[0191] The electronic devices described in this application exist in various forms, and perform the above-described... Figure 2 The steps shown include, but are not limited to, electronic devices with logical operation functions such as laptops, handheld computers, ultra-mobile personal computers (UMPCs), servers, network attached storage (NAS), and personal computers (PCs).

[0192] This application also provides a computer-readable storage medium, such as a memory including program code, which can be executed by a processor to perform the reverse time offset method in the above embodiments. For example, the computer-readable storage medium may be a read-only memory (ROM), a random access memory (RAM), a compact disc read-only memory (CDROM), magnetic tape, floppy disk, and optical data storage device, etc.

[0193] This application also provides a computer program product comprising one or more lines of program code stored in a computer-readable storage medium. A processor of an electronic device reads the program code from the computer-readable storage medium and executes the program code to complete the method steps of the reverse time offset method provided in the above embodiments.

[0194] Those skilled in the art will understand that all or part of the steps of the above embodiments can be implemented by hardware, or by a program or program code related to hardware. The program can be stored in a computer-readable storage medium, such as a read-only memory, a disk, or an optical disk.

[0195] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented using software plus a general-purpose hardware platform, or of course, using hardware. Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0196] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them; under the concept of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations as described above in different aspects of this application, which are not provided in detail for the sake of brevity; although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A reverse time migration method, characterized in that, The method includes: Acquire seismic exploration data in viscoelastic media; The compensated back propagation wave field is calculated based on the inverse dispersion acoustic wave equation transformed to the frequency domain and the seismic exploration data. Based on the compensated forward propagation wavefield and the compensated reverse propagation wavefield, a compensated reverse time migration image is obtained; before calculating the compensated reverse propagation wavefield based on the inverse dispersion acoustic wave equation transformed to the frequency domain and the seismic exploration data, the method further includes: Establish the equation for the inverse dispersion sound wave; The inverse dispersion acoustic wave equation is transformed to the frequency domain to extrapolate the wave field of the seismic wave. The calculation of the compensated back propagation wavefield based on the inverse dispersion acoustic wave equation transformed to the frequency domain and the seismic exploration data includes: During the wavefield extrapolation process, the seismic wave is subjected to absorption attenuation compensation and discretization processing according to the inverse dispersion acoustic wave equation transformed to the frequency domain, so as to obtain the compensated wavefield. Calculate the compensated reverse propagation wave field based on the compensated wave field.

2. The method according to claim 1, characterized in that, The inverse dispersion acoustic wave equation transformed to the frequency domain includes: Where σ is a mathematical value used to quantify the degree of stability and instability, ω is the angular frequency, v is the velocity, x is the spatial abscissa, z is the spatial ordinate, U is the displacement, and f is the source function.

3. The method according to claim 1, characterized in that, The step of calculating the compensated backpropagation wavefield based on the compensated wavefield includes: If the source function in the compensated wavefield is the complex conjugate of the frequency domain seismic record, then the seismic exploration data is substituted into the compensated wavefield to calculate the compensated back-propagating wavefield.

4. The method according to claim 1, characterized in that, The process of extrapolating the wavefield involves performing absorption attenuation compensation and discretization on the seismic wave based on the inverse dispersion acoustic wave equation transformed to the frequency domain, resulting in a compensated wavefield, including: Based on the inverse dispersion acoustic wave equation transformed to the frequency domain, the attenuation-dispersion model, and the optimal nine-point difference algorithm, the seismic wave is subjected to absorption attenuation compensation and discretization processing to obtain the compensated wave field. The method further includes: If the source function in the compensated wavefield is a source wavelet, then the compensated wavefield is a compensated forward propagation wavefield.

5. The method according to claim 4, characterized in that, The attenuation-dispersion model includes: Where v(ω) is the velocity, v is the phase velocity at the reference angular frequency ω0, π is pi, Q is the quality factor, ω is the angular frequency, ω0 is the reference angular frequency, and j is a complex number.

6. The method according to claim 1, characterized in that, The compensated wave field includes: A Q+ (v,ω)U(ω)=f(ω) Among them, A Q+ (v,ω) is the impedance matrix, U(ω) is the displacement, and f(ω) is the source function.

7. The method according to claim 4, characterized in that, The compensated propagating wavefield includes: S c (ω)=(A Q+ (v,ω)) -1 f(ω) Among them, S c (ω) represents the compensated propagating wave field, A Q+ (v,ω) is the impedance matrix, and f(ω) is the source function.

8. The method according to claim 3, characterized in that, The compensated anti-propagating wavefield includes: R c (ω)=(A Q+ (v,ω)) -1 (r Q- (oh)) * Among them, R c (ω) represents the compensated anti-propagating wavefield, A Q+ (v,ω) is the impedance matrix, r Q- (ω) represents the seismic record in the viscoelastic medium.

9. The method according to any one of claims 1-6, characterized in that, The step of obtaining the compensated reverse-time migration image based on the compensated forward propagation wavefield and the compensated reverse propagation wavefield includes: I c (x)=ω 2 S c (ω)R c (oh) Among them, I c (x) is the compensated reverse-time offset image, ω is the angular frequency, and S c (ω) represents the compensated propagating wave field, R c (ω) represents the compensated reverse propagation wave field.

10. An electronic device, characterized in that, include: At least one processor, and The memory communicatively connected to the at least one processor, wherein, The memory stores instructions that can be executed by the at least one processor to enable the at least one processor to perform the reverse time offset method according to any one of claims 1-9.

Images