Earthquake processing method and device based on seismic wave field numerical simulation

Abstract

The invention relates to a seismic processing method and device based on seismic wave field numerical simulation, and belongs to the technical field of seismic exploration, and the method comprises the steps: carrying out the polynomial approximate expansion of an anisotropic pure-mode P wave and SV wave frequency dispersion relational expression, and obtaining an expanded polynomial; solving a target function corresponding to the expanded polynomial according to a preset optimization algorithm, and obtaining a polynomial optimization coefficient of the expanded polynomial; converting the optimized frequency dispersion relational expression of the P wave and the SV wave into a time-space domain, and obtaining an anisotropic pure mode wave equation; and solving the anisotropic pure-mode wave equation to realize numerical simulation of a seismic wave field, and performing prediction processing on a real-time earthquake based on a numerical simulation result. By adopting the seismic wave field numerical simulation method, high-precision numerical simulation of the seismic wave field can be realized, an effective wave field extrapolation tool is provided for subsequent anisotropic imaging and inversion, and earthquake prediction processing is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of seismic exploration, and in particular to a seismic processing method and device based on seismic wave field numerical simulation. Background Art

[0002] In the exploration of fossil energy such as oil and natural gas, seismic exploration technology is widely popular due to its advantages in accuracy and efficiency. According to the workflow, seismic exploration technology can be divided into three major links: field data acquisition, indoor data processing, and interpretation of the results profile. As one of the basic contents of seismic exploration technology, seismic forward modeling can guide the design of seismic acquisition observation systems, test the correctness of seismic data processing methods, and verify the rationality of interpretation. Therefore, it has received more attention in the research and development of high-precision seismic exploration technology in recent years.

[0003] The use of different numerical algorithms to numerically solve high-precision seismic wave equations is one of the core contents of seismic forward modeling technology. When accurately describing the propagation characteristics of seismic waves in the earth's medium, numerical simulations of seismic wave equations represented by anisotropic acoustic wave equations and elastic wave equations have been widely studied and applied. The elastic wave equation can provide richer wave field information and has more complete dynamic characteristics. However, its problems are coupling crosstalk between multiple wave types (P waves, S waves and converted waves), complex wave field characteristics, and difficulty in numerical solution. Therefore, in anisotropic wave field simulation, imaging and inversion, pseudo-acoustic wave equations based on acoustic assumptions are more popular. However, the traditional pseudo-acoustic wave equation is derived from a simplified mathematical form and lacks a clear physical meaning. Therefore, when the anisotropic parameters do not meet the elliptical assumption, the simulation results based on the pseudo-acoustic wave equation are prone to pseudo-shear wave interference and numerical instability. In view of this, in order to eliminate or reduce the problems of the pseudo-acoustic wave equation, scholars have developed various forms of pure acoustic wave equations, which can effectively avoid pseudo-shear wave interference and instability. To date, the pure acoustic wave equation is mainly derived from the original precise pure P-wave phase velocity relationship using different approximate schemes. Therefore, the problem focuses on the accuracy and efficiency of the approximate method adopted in the solution process. Taking one of the most commonly used Taylor series expansion methods as an example, the square root terms in the precise pure P-wave phase velocity relationship are expanded using a first-order or high-order Taylor series to obtain the corresponding approximate expansion and wave equation. Of course, as the expansion order increases, more computational effort is usually required. In recent years, based on the Taylor technical expansion, other more accurate approximate expansion methods, such as parameter substitution expansion method and optimization expansion method, have received more attention.

[0004] In general, there are currently two main problems in the high-precision numerical simulation of anisotropic pure P-wave equations: first, the dispersion relation of pure P waves and the approximate accuracy of their wave equations need to be further improved; second, conventional schemes usually treat SV waves as interference sources and eliminate them when obtaining pure P-wave responses. Therefore, how to "turn waste into treasure" for SV waves and consider the propagation of pure SV waves while studying pure P waves requires further in-depth research. In view of this, further improving the solution accuracy of pure P-wave equations while fully considering the propagation of pure SV waves for numerical simulation, imaging and inversion of two-dimensional and three-dimensional anisotropic seismic wave fields has become an important research direction and goal.

[0005] In the field of exploration seismology, a large number of indoor experiments and field practices have shown that anisotropy is common in the earth's medium, that is, the propagation speed of seismic waves in the medium will change with the change of direction. Therefore, with the development of high-precision seismic exploration technology, it is of great significance to continuously improve seismic processing technology based on anisotropy theory. Numerical simulation technology of seismic wave fields is an effective means to understand the laws and characteristics of seismic wave propagation, which is crucial for subsequent imaging and inversion. In terms of numerical simulation of anisotropic seismic wave fields, compared with elastic wave fields, acoustic wave field characteristics are clearer and simpler, and easy to implement, so they are widely favored. Traditional anisotropic wave field simulation mainly uses pseudo-acoustic wave equations based on acoustic approximation, which are prone to interference and numerical instability. To address this problem, scholars have developed various forms of pure P-wave equations. However, there are two main problems in the existing research on the pure P-wave equation: first, the approximate accuracy of the pure P-wave equation needs to be further improved, and it is difficult to accurately predict earthquake conditions when the accuracy is not high; second, when obtaining the pure P-wave equation, SV waves are usually removed as interference and have not been effectively studied, resulting in inaccurate earthquake predictions.

[0006] Therefore, it is necessary to improve the existing numerical simulation methods of seismic waves in order to achieve accurate prediction and processing of earthquakes. Summary of the invention

[0007] In view of this, it is necessary to provide a numerical simulation method of seismic wave fields to realize high-precision numerical simulation of anisotropic pure P-wave equations and SV waves, and then realize the prediction and processing of anisotropic seismic waves.

[0008] In order to achieve the above object, in a first aspect, the present invention provides a method for numerical simulation of seismic wave fields, comprising: The dispersion relation of anisotropic pure mode P wave and SV wave is expanded by polynomial approximation to obtain the expanded polynomial; Solve the objective function corresponding to the expanded polynomial according to a preset optimization algorithm to obtain the polynomial optimization coefficient of the expanded polynomial; Convert the optimized dispersion relation of P wave and SV wave to the time-space domain to obtain anisotropic pure mode wave equation, wherein the optimized dispersion relation of P wave and SV wave is the expanded polynomial after the optimized coefficient of the polynomial is brought into the equation; The anisotropic pure mode wave equation is solved to realize the numerical simulation of the seismic wave field, and the real-time earthquake is predicted and processed based on the numerical simulation results.

[0009] In a possible implementation, before performing polynomial approximate expansion on the dispersion relation of anisotropic pure mode P wave and SV wave, the following is further included: Obtain the decoupled P-wave phase velocity relationship and SV-wave phase velocity relationship in anisotropic media; Based on the relationship between wave number, phase velocity and angular frequency, the decoupled P-wave phase velocity relation and SV-wave phase velocity relation are transformed into anisotropic pure mode P-wave and SV-wave dispersion relation.

[0010] In a possible implementation, the dispersion relation of anisotropic pure mode P wave and SV wave is expanded by polynomial approximation to obtain the expanded polynomial, including: The improved expansion method is used to perform polynomial approximate expansion on the dispersion relation of anisotropic pure mode P wave and SV wave to obtain the expansion polynomial.

[0011] In a possible implementation, before solving the objective function corresponding to the expanded polynomial according to a preset optimization algorithm, the method further includes: Based on the relationship between phase velocity and dispersion relation, an approximate expanded dispersion relation is obtained; The objective function is constructed based on the exact dispersion relation and the approximate expanded dispersion relation.

[0012] In a possible implementation, solving the objective function corresponding to the expanded polynomial according to a preset optimization algorithm to obtain the polynomial optimization coefficient of the expanded polynomial includes: The objective function is solved according to a least squares optimization algorithm to obtain polynomial optimization coefficients of the expanded polynomial.

[0013] In a possible implementation, solving the anisotropic pure mode wave equation to obtain a numerical value of the anisotropic pure mode wave equation includes: The pure mode wave equation is solved by combining finite difference and pseudo-spectral method to obtain the numerical value of the anisotropic pure mode wave equation.

[0014] In a second aspect, the present invention further provides a seismic processing device based on numerical simulation of seismic wave fields, comprising: An approximate expansion module is used to perform polynomial approximate expansion on the dispersion relation of anisotropic pure mode P waves and SV waves to obtain the expansion polynomial; A first processing module, used to solve the objective function corresponding to the expanded polynomial according to a preset optimization algorithm, and obtain the polynomial optimization coefficient of the expanded polynomial; A conversion module, used for converting the optimized dispersion relation of P wave and SV wave into the time-space domain to obtain anisotropic pure mode wave equation, wherein the optimized dispersion relation of P wave and SV wave is an expanded polynomial after the optimized coefficient of the polynomial is brought into the equation; The second processing module is used to solve the anisotropic pure mode wave equation, realize the numerical simulation of the seismic wave field, and predict the real-time earthquake based on the numerical simulation result.

[0015] In a possible implementation, the seismic processing device based on seismic wave field numerical simulation further includes: An acquisition module, used to obtain the decoupled P-wave phase velocity relationship and SV-wave phase velocity relationship in anisotropic media; The conversion module is used to convert the decoupled P-wave phase velocity relation and SV-wave phase velocity relation into anisotropic pure mode P-wave and SV-wave dispersion relation based on the relationship between wave number, phase velocity and angular frequency.

[0016] In a third aspect, the present invention further provides an electronic device comprising a memory and a processor, wherein the memory stores a computer program executable on the processor, and when the program code is executed by the processor, the steps of the seismic processing method based on numerical simulation of seismic wave fields as described above are implemented.

[0017] In a fourth aspect, the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the above-mentioned seismic processing method based on numerical simulation of seismic wave fields.

[0018] Beneficial effects of the present invention: The above-mentioned seismic processing method, device, electronic device and storage medium based on numerical simulation of seismic wave field, by performing polynomial approximation expansion of the anisotropic pure mode P wave and SV wave dispersion relation, obtains the expansion polynomial, thereby taking into account the seismic waves of two modes and retaining more wave field information. According to the preset optimization algorithm, the objective function corresponding to the expansion polynomial is solved to obtain the polynomial optimization coefficient of the expansion polynomial. The objective function can be constructed based on the improved expansion polynomial with undetermined coefficients, and the polynomial coefficients can be obtained by using the optimization strategy to obtain the expansion polynomial with high approximation, that is, the optimized dispersion relation of P wave and SV wave. Then, the optimized dispersion relation of P wave and SV wave is converted to the time-space domain, and the anisotropic pure mode wave equation that is easy to solve can be obtained. Finally, the anisotropic pure mode wave equation is solved to obtain the high-precision numerical value of the anisotropic pure mode wave equation, and the high-precision numerical extrapolation of the pure mode seismic wave field is realized, thereby realizing the high-precision numerical simulation of the seismic wave field, providing an effective wave field extrapolation tool for subsequent anisotropic imaging and inversion, and realizing earthquake prediction processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A method flow chart of an embodiment of a seismic processing method based on seismic wave field numerical simulation provided by the present invention; Figure 2 A method flow chart of another embodiment of the seismic processing method based on seismic wave field numerical simulation provided by the present invention; Figure 3a A graph of the P-wave phase velocity of a two-dimensional anisotropic model calculated in the first embodiment of the seismic processing method based on numerical simulation of seismic wave fields provided by the present invention; Figure 3b is the traditional first-order Taylor expansion method and Figure 3a The error curve between the P-wave phase velocity of the optimized expansion method and the reference solution; Figure 4a A graph showing the SV wave phase velocity of a two-dimensional anisotropic model calculated in the first embodiment of the seismic processing method based on seismic wave field numerical simulation provided by the present invention; Figure 4b is the traditional first-order Taylor expansion method and Figure 4a The error curve between the SV wave phase velocity of the optimized expansion method and the reference solution; Figure 5a A graph of the P-wave phase velocity of a two-dimensional anisotropic model calculated in the second embodiment of the seismic processing method based on seismic wave field numerical simulation provided by the present invention; Figure 5b is the traditional first-order Taylor expansion method and Figure 5a The error curve between the P-wave phase velocity of the optimized expansion method and the reference solution; Figure 6aA graph of SV wave phase velocity of a two-dimensional anisotropic model calculated in the second embodiment of the seismic processing method based on seismic wave field numerical simulation provided by the present invention; Figure 6b is the traditional first-order Taylor expansion method and Figure 6a The error curve between the SV wave phase velocity of the optimized expansion method and the reference solution; Figure 7a A graph of the P-wave phase velocity of a three-dimensional anisotropic model calculated in the first embodiment of the seismic processing method based on numerical simulation of seismic wave fields provided by the present invention; Figure 7b is calculated by the traditional first-order Taylor expansion method Figure 7a The error curve between the P-wave phase velocity and the reference solution; Figure 7c The optimized expansion method in the present invention calculates Figure 7a The error curve between the P-wave phase velocity and the reference solution; Figure 8a A graph showing the SV wave phase velocity of a three-dimensional anisotropic model calculated in the first embodiment of the seismic processing method based on seismic wave field numerical simulation provided by the present invention; Figure 8b is calculated by the traditional first-order Taylor expansion method Figure 8a The error curve between the SV wave phase velocity and the reference solution; Figure 8c The optimized expansion method in the present invention calculates Figure 8a The error curve between the SV wave phase velocity and the reference solution; Figure 9a A graph of the P-wave phase velocity of a three-dimensional anisotropic model calculated in the second embodiment of the seismic processing method based on seismic wave field numerical simulation provided by the present invention; Figure 9b is calculated by the traditional first-order Taylor expansion method Figure 9a The error curve between the P-wave phase velocity and the reference solution; Fig.9c The optimized expansion method in the present invention calculates Figure 9a The error curve between the P-wave phase velocity and the reference solution; Fig.10a A graph of SV wave phase velocity of a three-dimensional anisotropic model calculated in the second embodiment of the seismic processing method based on seismic wave field numerical simulation provided by the present invention; Fig.10b is calculated by the traditional first-order Taylor expansion method Fig.10a The error curve between the SV wave phase velocity and the reference solution; Fig.10c The optimized expansion method in the present invention calculates Fig.10a The error curve between the SV wave phase velocity and the reference solution; Fig.11a is the calculation result of the pseudo-acoustic wave equation with a shear wave velocity of 0 in the instantaneous wave field snapshot calculated in the two-dimensional uniform anisotropic model of the present invention; Fig.11b It is the calculation result of the pseudo-acoustic wave equation in which the shear wave velocity is not 0 in the instantaneous wave field snapshot calculated in the two-dimensional uniform anisotropic model of the present invention; Fig.11c It is the calculation result of the pure P-wave equation in the instantaneous wave field snapshot calculated in the two-dimensional uniform anisotropic model in the present invention; Fig.11d It is the calculation result of the pure SV wave equation in the instantaneous wave field snapshot calculated in the two-dimensional uniform anisotropic model in the present invention; Fig.12a It is the calculation result of the pseudo-acoustic wave equation with the shear wave velocity of 0 in the instantaneous wave field snapshot calculated in the three-dimensional uniform anisotropic model of the present invention; Figure 12b It is the calculation result of the pseudo-acoustic wave equation in which the shear wave velocity is not 0 in the instantaneous wave field snapshot calculated in the three-dimensional uniform anisotropic model of the present invention; Fig.12c It is the calculation result of the pure P-wave equation in the instantaneous wave field snapshot calculated in the three-dimensional uniform anisotropic model of the present invention; Fig.12d It is the calculation result of the pure SV wave equation in the instantaneous wave field snapshot calculated in the three-dimensional uniform anisotropic model of the present invention; Fig.13a It is the velocity model diagram in the modified two-dimensional Sigsbee anisotropic medium model; Fig.13b is the parameter model in the Thomsen anisotropic parameter model ε ; Fig.13c is the parameter model in the Thomsen anisotropic parameter model δ ; Fig.14a The calculation results of the pseudo-acoustic wave equation with a shear wave velocity of 0 in the instantaneous wave field snapshot calculated in the modified two-dimensional Sigsbee anisotropic medium model; Fig.14b The results of pseudo-acoustic wave equation calculations for the instantaneous wave field snapshots calculated in the modified two-dimensional Sigsbee anisotropic medium model where the shear wave velocity is not zero; Fig.14c It is the calculation result of the pure P-wave equation in the present invention; Fig.14d It is the calculation result of the pure SV wave equation in the present invention; Fig.15a It is the velocity model diagram in the modified three-dimensional Marmousi VTI medium model; Fig.15b is the parameter model in the Thomsen anisotropic parameter model ε ; Fig.15c is the parameter model in the Thomsen anisotropic parameter model δ ; Fig.16a The calculation results of the pseudo-acoustic wave equation with a shear wave velocity of 0 in the instantaneous wave field snapshot calculated in the modified three-dimensional Marmousi VTI medium model; Fig.16b The results of pseudo-acoustic wave equation calculations for non-zero shear wave velocity in the instantaneous wave field snapshots calculated in the modified three-dimensional Marmousi VTI medium model; Fig.16c It is the calculation result of the pure P-wave equation in the present invention; Fig.16d It is the calculation result of the pure SV wave equation in the present invention; Fig.17 A schematic structural diagram of an embodiment of a seismic processing device based on seismic wave field numerical simulation provided by the present invention; Fig.18 A schematic structural diagram of an electronic device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0021] To solve the above problems, please refer to Figure 1 In one embodiment of the present application, a seismic processing method based on numerical simulation of seismic wave fields is disclosed, comprising: S101, performing polynomial approximation expansion on the dispersion relation of anisotropic pure mode P wave and SV wave to obtain the expansion polynomial; S102, solving the objective function corresponding to the expanded polynomial according to a preset optimization algorithm, and obtaining the polynomial optimization coefficient of the expanded polynomial; S103, converting the optimized dispersion relation of P wave and SV wave into the time-space domain to obtain anisotropic pure mode wave equation, wherein the optimized dispersion relation of P wave and SV wave is an expanded polynomial after the optimized coefficient of the polynomial is brought into the equation; S104, solving the anisotropic pure mode wave equation to achieve numerical simulation of the seismic wave field, and predicting and processing real-time earthquakes based on the numerical simulation results.

[0022] Further, the technical solution of the embodiment of the present invention is detailed in Figure 2 Among them, for the two-dimensional / three-dimensional anisotropic accurate phase velocity relationship, obtaining the expansion polynomial coefficients, and deriving the pure mode dispersion relationship and wave equation are the key to the embodiments of the present invention.

[0023] In a specific embodiment, before performing polynomial approximation expansion on the anisotropic pure mode P wave and SV wave dispersion relation, the method further includes: Obtain the decoupled P-wave phase velocity relationship and SV-wave phase velocity relationship in anisotropic media; among them, the decoupled P-wave phase velocity and SV wave phase velocity They are as follows: (1) (2) (3) in, is the vertical P-wave velocity, is the vertical S-wave velocity, θ is the phase angle, ε and δ is the Thomsen anisotropy parameter.

[0024] Furthermore, based on the relationship between wave number, phase velocity and angular frequency, the decoupled P-wave phase velocity relation and SV-wave phase velocity relation are transformed into the dispersion relation of anisotropic pure mode P-wave and SV-wave. Specifically, equations (1)-(3) can be transformed into the dispersion relation of P-wave and SV-wave in three-dimensional anisotropic medium: (P wave) (4) (SV wave) (5) , (6) In particular, when When , the above equation degenerates into a two-dimensional dispersion relation.

[0025] Equations (4) and (5) are the dispersion relations of anisotropic pure modes (P waves and SV waves). Since they contain complex square root terms D , it is difficult to solve directly with conventional algorithms. In view of this, even if we let , we can get a simplified pseudo-acoustic wave equation. The pseudo-acoustic wave equation based on the acoustic approximation idea has been widely used in anisotropic wave field simulation, migration imaging and waveform inversion.

[0026] It should be noted that Taylor expansion is essentially a low-frequency approximation, so when the frequency / wave number increases, the dispersion relation or wave equation constructed based on Taylor expansion has a large numerical error. The embodiment of the present invention will use a polynomial to expand the precise dispersion relation, and use a more accurate optimization algorithm to obtain the polynomial coefficients, so as to achieve a more accurate approximation effect.

[0027] Specifically, the dispersion relation of anisotropic pure mode P wave and SV wave is expanded by polynomial approximation to obtain the expanded polynomial, including: The improved expansion method is used to perform polynomial approximate expansion on the dispersion relation of anisotropic pure mode P wave and SV wave to obtain the expansion polynomial.

[0028] Among them, for the accurate three-dimensional pure mode P wave and SV wave dispersion relationship, the following polynomial is used to approximate it: (7) Find the polynomial coefficients in the above equation ( ), in an embodiment of the present invention, before solving the objective function corresponding to the expanded polynomial according to a preset optimization algorithm, it also includes: Based on the relationship between phase velocity and dispersion relation, an approximate expanded dispersion relation is obtained; The objective function is constructed based on the exact dispersion relation and the approximate expanded dispersion relation.

[0029] Specifically, the objective function is: (8) in, (9) With respect to the objective function (8), which is linear with respect to the polynomial coefficients, in a possible embodiment, solving the objective function corresponding to the expanded polynomial according to a preset optimization algorithm to obtain the polynomial optimization coefficients of the expanded polynomial includes: The objective function is solved according to a least squares optimization algorithm to obtain polynomial optimization coefficients of the expanded polynomial.

[0030] In particular, in equation (9), the symbol “ When the "+" sign is used, the coefficients of the pure P-wave polynomial expansion are obtained. ", the pure SV wave polynomial expansion coefficients are obtained.

[0031] Equation (7) is a three-dimensional optimized pure mode dispersion relation constructed in an embodiment of the present invention, and its coefficients are obtained by solving the objective function (8) using an optimization algorithm.

[0032] Furthermore, the optimized pure mode dispersion relation is transformed into the time-space domain, and the optimized pure mode wave equation can be obtained. The specific form of the equation is no longer given, and the pure mode wave equation is directly solved by combining the finite difference method and the pseudospectral method.

[0033] In a possible embodiment, solving the anisotropic pure mode wave equation to obtain a value of the anisotropic pure mode wave equation includes: The pure mode wave equation is solved by combining finite difference and pseudo-spectral method to obtain the numerical value of the anisotropic pure mode wave equation.

[0034] Specifically, the solution form in three-dimensional case is as follows: (10) Among them, the operator is the Fourier transform, is the inverse Fourier transform. In particular, for the anisotropic optimization of the pure mode wave equation, the finite difference method is used to solve the first half of the equation, and the pseudo-spectral method is used to solve the second half, so that the high-precision numerical extrapolation of the pure mode seismic wave field can be achieved. It should be noted that when the equations (7)-(10) are y When the directional wave number and partial derivatives vanish, the above equation can be degenerated into a two-dimensional form.

[0035] In order to study the rationality of the scheme of the seismic processing method based on the numerical simulation of the seismic wave field, the embodiment of the present invention also provides the content of the comparative analysis of the phase velocity accuracy of anisotropic media.

[0036] Specifically, Figure 3a , Figure 3b , Figure 4a , Figure 4b , Figure 5a , Figure 5b , Figure 6a and Figure 6b A total of two sets of P-wave and SV-wave phase velocity curves calculated by the reference solution in the two-dimensional anisotropic model and the phase velocity error curves between different expansion methods and the reference solution are shown. Figure 7a , Figure 7b , Figure 7c , Figure 8a , Figure 8b , Figure 8c , Figure 9a , Figure 9b , Fig.9c , Fig.10a , Fig.10b and Fig.10cThe P-wave and SV-wave phase velocity surfaces calculated by the reference solution in two sets of three-dimensional anisotropic models, as well as the phase velocity error surfaces between the three expansion methods and the reference solution are shown. Among them, the relevant parameters of the anisotropic model I (i.e., the model under the first embodiment) are , , , The relevant parameters of the anisotropic model II (i.e., the model in the second embodiment) are , , , . It can be seen from the content in the figure that compared with the reference phase velocity curve / surface, the P-wave and SV-wave phase velocity results calculated by the traditional first-order Taylor expansion method have large errors. In contrast, the optimized expansion method in the present invention can produce high-precision approximate results along different phase angles and azimuth angles, thereby providing a reliable basis for subsequent wave field extension.

[0037] It should be noted that in the above content, the embodiments of the present invention have sorted out the basic theory and method flow. Overall, the workflow of high-precision numerical simulation of anisotropic pure mode seismic wave fields based on optimization strategy is mainly composed of the following steps: ① Based on the improved approximate expansion strategy, the high-precision phase velocity relations of pure P waves and pure SV waves in two-dimensional and three-dimensional anisotropic media are obtained; ② Based on the relationship between phase velocity and dispersion relation, obtain two-dimensional and three-dimensional approximate expansion dispersion relation; ③ Based on the exact dispersion relation and the approximate expanded dispersion relation, the objective function is constructed and the two-dimensional and three-dimensional P-wave and SV-wave polynomial coefficients are obtained by using the least squares optimization algorithm; ④ Optimize the dispersion relation for P-wave and SV-wave, convert it into the time-space domain, and obtain the anisotropic pure mode wave equation. Combine the finite difference and pseudo-spectral method to solve the pure mode wave equation; ⑤ Two sets of anisotropic models are used to compare and analyze the phase velocity accuracy of different approximation methods in two-dimensional and three-dimensional P waves and SV waves. Two-dimensional and three-dimensional uniform models and complex models are used to test the numerical simulation accuracy of the traditional method and the optimized expansion method developed by the present invention, and the effectiveness is verified by comparing the simulation results of different schemes.

[0038] Furthermore, anisotropy is widely developed in the earth's medium, which is mainly manifested in that the propagation speed of seismic waves in the medium changes with different directions. In exploration seismology, TI (transversely isotropic) medium is the most commonly used theoretical model to characterize the anisotropic characteristics of the medium. In terms of TI wave field simulation, imaging and inversion, in order to develop a more accurate seismic wave field extrapolation algorithm, the embodiment of the present invention develops a pure mode (mainly including P waves and SV waves) seismic wave equation for two-dimensional and three-dimensional VTI (vertical symmetry axis transverse isotropic) media and its numerical solution method. First, for the original accurate P-wave and SV-wave phase velocity formulas, they are approximated based on the currently more advanced improved expansion method to obtain the expansion polynomial. Secondly, based on the improved expansion polynomial with undetermined coefficients, the objective function is constructed, and the polynomial coefficients are obtained by using an optimization strategy. Finally, the pure mode phase velocity relationship, dispersion relationship and wave equation of P-wave and SV-wave based on the optimization algorithm are constructed, and the wave equation is effectively solved by combining finite difference and pseudo-spectral methods. Phase velocity accuracy analysis and multiple model examples show that the optimization expansion method in the present invention can significantly improve the numerical simulation accuracy of anisotropic pure P waves and pure SV waves. At the same time, the optimization scheme takes into account two modes of seismic waves at the same time, retaining more wave field information. The optimization technical scheme in the embodiment of the present invention can provide a high-precision numerical calculation tool for the development of anisotropic seismic processing technology.

[0039] The invention is described below by further specific examples.

[0040] The simulation accuracy of the traditional pseudo-acoustic wave equation with a shear wave velocity of 0, the pseudo-acoustic wave equation with a shear wave velocity of not 0, and the optimized pure mode wave equation of the present invention were compared by applying two-dimensional and three-dimensional homogeneous anisotropic medium models. The size of the two-dimensional model is 18000 m × 18000 m, the size of the three-dimensional model is 2000 m × 2000 m × 2000 m, and the size of the discrete grid unit is 10 m. The Ricker wavelet is selected as the source function and placed in the center of the model to generate vibration. The parameters of the anisotropic medium model are , , , . Fig.11a , Fig.11b , Fig.11c , Fig.11d as well as Fig.12a , Figure 12b , Fig.12c , Fig.12dThe instantaneous wave field snapshots calculated by different equations in the two-dimensional and three-dimensional uniform anisotropic models are shown respectively. From the simulation results in the figure, it can be seen that the traditional pseudo-acoustic wave equation will produce strong pseudo-transverse wave interference near the earthquake source under the premise that the anisotropic parameters do not meet the acoustic assumptions. In contrast, the optimized pure mode wave equation in the present invention can produce accurate pure P-wave and pure SV-wave responses, effectively avoiding the problems of the traditional pseudo-acoustic wave equation. In addition, while taking into account the effective P-wave response, the optimization scheme takes the SV wave field, which is traditionally considered to be interference, into consideration and processes it separately, providing richer information on the basis of the original wave field.

[0041] Furthermore, the present invention also uses a complex anisotropic model to further test the numerical accuracy of different equations. Fig.13a , Fig.13b , Fig.13c A modified two-dimensional Sigsbee anisotropic model is proposed, which includes a vertical velocity model and a Thomsen anisotropic parameter model, both with a size of 7000 m × 5000 m. Fig.14a , Fig.14b , Fig.14c , Fig.14d The calculation results of the traditional pseudo-acoustic wave equation in the two-dimensional model and the optimized pure mode wave equation in the present invention are shown. Fig.15a , Fig.15b , Fig.15c A modified 3D anisotropic Marmousi model with a size of 1800 m × 1800 m ×1800 m is presented. Ricker wavelet is used as the source function. In the complex model examples, the required shear wave velocity is set to 0.67 times the longitudinal wave velocity. Fig.16a , Fig.16b , Fig.16c , Fig.16d The simulation results of two modified three-dimensional anisotropic models, the acoustic wave equation and the optimized pure mode wave equation of the present invention, are shown. Fig.14a , Fig.14b , Fig.14c , Fig.14d and Fig.16a , Fig.16b , Fig.16c , Fig.16d It can be seen from the wave field simulation results in that the pseudo acoustic wave equation based on the shear wave velocity of 0 or the restrictive shear wave velocity will inevitably produce pseudo shear wave interference near the source, as shown by the arrow, which affects the effective P wave field. In contrast, the optimized pure mode wave equation in the present invention can produce accurate pure P wave response. At the same time, the pure SV wave information is effectively retained, which helps to study the anisotropic wave field characteristics.

[0042] In summary, from the examples of uniform models and complex models, it can be seen that the optimized pure mode wave equation and its numerical solution in the embodiment of the present invention can provide an effective wave field numerical simulation tool for subsequent high-precision anisotropic seismic processing, thereby providing a data basis for earthquake prediction and achieving accurate prediction.

[0043] In order to better implement the seismic processing method based on seismic wave field numerical simulation in the embodiment of the present invention, on the basis of the seismic processing method based on seismic wave field numerical simulation, the embodiment of the present invention also provides a seismic processing device based on seismic wave field numerical simulation. As shown in FIG. 3 , the seismic processing device 1700 based on seismic wave field numerical simulation includes: An approximate expansion module 1701 is used to perform polynomial approximate expansion on the anisotropic pure mode P wave and SV wave dispersion relation to obtain an expanded polynomial; A first processing module 1702 is used to solve the objective function 1703 corresponding to the expanded polynomial according to a preset optimization algorithm to obtain the polynomial optimization coefficient of the expanded polynomial; A conversion module, used for converting the optimized dispersion relation of P wave and SV wave into the time-space domain to obtain anisotropic pure mode wave equation, wherein the optimized dispersion relation of P wave and SV wave is an expanded polynomial after the optimized coefficient of the polynomial is brought into the equation; The second processing module 1704 is used to solve the anisotropic pure mode wave equation, realize the numerical simulation of the seismic wave field, and predict the real-time earthquake based on the numerical simulation results.

[0044] The seismic processing device 1700 based on seismic wave field numerical simulation provided in the above embodiment can implement the technical solution described in the above embodiment of the seismic processing method based on seismic wave field numerical simulation. The specific implementation principles of the above modules or units can refer to the corresponding contents in the above embodiment of the seismic processing method based on seismic wave field numerical simulation, which will not be repeated here.

[0045] In some embodiments, the seismic processing device 1700 based on seismic wavefield numerical simulation further includes: An acquisition module, used to obtain the decoupled P-wave phase velocity relationship and SV-wave phase velocity relationship in anisotropic media; The conversion module is used to convert the decoupled P-wave phase velocity relation and SV-wave phase velocity relation into anisotropic pure mode P-wave and SV-wave dispersion relation based on the relationship between wave number, phase velocity and angular frequency.

[0046] like Fig.18 As shown, the present invention also provides an electronic device 1800. The electronic device 1800 includes a processor 1801, a memory 1802 and a display 1803. Fig.18Only some components of the electronic device 1800 are shown, but it should be understood that it is not required to implement all of the shown components, and more or fewer components may be implemented instead.

[0047] In some embodiments, the processor 1801 may be a central processing unit (CPU), a microprocessor or other data processing chip, used to run program codes or process data stored in the memory 1802, such as the seismic processing method based on numerical simulation of seismic wave fields in the present invention.

[0048] In some embodiments, processor 1801 may be a single server or a server group. The server group may be centralized or distributed. In some embodiments, processor 1801 may be local or remote. In some embodiments, processor 1801 may be implemented in a cloud platform. In one embodiment, the cloud platform may include a private cloud, a public cloud, a hybrid cloud, a community cloud, a distributed cloud, an internal cloud, a multi-cloud, etc., or any combination thereof.

[0049] In some embodiments, the memory 1802 may be an internal storage unit of the electronic device 1800, such as a hard disk or memory of the electronic device 1800. In other embodiments, the memory 1802 may also be an external storage electronic device of the electronic device 1800, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device 1800.

[0050] Furthermore, the memory 1802 may include both an internal storage unit of the electronic device 1800 and an external storage electronic device. The memory 1802 is used to store application software installed in the electronic device 1800 and various data.

[0051] In some embodiments, the display 1803 may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, an OLED (Organic Light-Emitting Diode) touch device, etc. The display 1803 is used to display information of the electronic device 1800 and to display a visual user interface. The components 1801-1803 of the electronic device 1800 communicate with each other via a device bus.

[0052] In some embodiments of the present invention, when the processor 1801 executes the seismic processing program based on seismic wave field numerical simulation in the memory 1802, the following steps may be implemented: The dispersion relation of anisotropic pure mode P wave and SV wave is expanded by polynomial approximation to obtain the expanded polynomial; Solve the objective function corresponding to the expanded polynomial according to a preset optimization algorithm to obtain the polynomial optimization coefficient of the expanded polynomial; Convert the optimized dispersion relation of P wave and SV wave to the time-space domain to obtain anisotropic pure mode wave equation, wherein the optimized dispersion relation of P wave and SV wave is the expanded polynomial after the optimized coefficient of the polynomial is brought into the equation; The anisotropic pure mode wave equation is solved to realize the numerical simulation of the seismic wave field, and the real-time earthquake is predicted and processed based on the numerical simulation results.

[0053] It should be understood that: when the processor 1801 executes the seismic processing program based on seismic wave field numerical simulation in the memory 1802, in addition to the above functions, other functions can also be realized. For details, please refer to the description of the above related method embodiments.

[0054] Accordingly, an embodiment of the present application also provides a computer-readable storage medium, which is used to store computer-readable programs or instructions. When the program or instructions are executed by a processor, it can implement the steps or functions of the seismic processing method based on numerical simulation of seismic wave fields provided in the above-mentioned method embodiments.

[0055] Those skilled in the art will appreciate that all or part of the processes of the above-mentioned embodiments can be implemented by instructing related hardware (such as a processor, a controller, etc.) through a computer program, and the computer program can be stored in a computer-readable storage medium, wherein the computer-readable storage medium is a disk, an optical disk, a read-only storage memory, or a random access memory, etc.

[0056] The above is a detailed introduction to the seismic processing method, device, electronic device and storage medium based on numerical simulation of seismic wave fields provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for technical personnel in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A seismic processing method based on numerical simulation of seismic wave fields, characterized in that: include: The dispersion relation of anisotropic pure mode P wave and SV wave is expanded by polynomial approximation to obtain the expanded polynomial; Solve the objective function corresponding to the expanded polynomial according to a preset optimization algorithm to obtain the polynomial optimization coefficient of the expanded polynomial; Convert the optimized dispersion relation of P wave and SV wave to the time-space domain to obtain anisotropic pure mode wave equation, wherein the optimized dispersion relation of P wave and SV wave is the expanded polynomial after the optimized coefficient of the polynomial is brought into the equation; The anisotropic pure mode wave equation is solved to realize the numerical simulation of the seismic wave field, and the real-time earthquake is predicted and processed based on the numerical simulation results.

2. The seismic processing method based on seismic wave field numerical simulation according to claim 1, characterized in that: Before the polynomial approximate expansion of the anisotropic pure mode P-wave and SV-wave dispersion relations, it also includes: Obtain the decoupled P-wave phase velocity relationship and SV-wave phase velocity relationship in anisotropic media; Based on the relationship between wave number, phase velocity and angular frequency, the decoupled P-wave phase velocity relation and SV-wave phase velocity relation are transformed into anisotropic pure mode P-wave and SV-wave dispersion relation.

3. The earthquake processing method based on seismic wave field numerical simulation according to claim 1, characterized in that: The dispersion relation of anisotropic pure mode P wave and SV wave is expanded by polynomial approximation, and the expanded polynomial is obtained, including: The improved expansion method is used to perform polynomial approximate expansion on the dispersion relation of anisotropic pure mode P wave and SV wave to obtain the expansion polynomial.

4. The earthquake processing method based on numerical simulation of earthquake wave fields according to claim 1, characterized in that: Before solving the objective function corresponding to the expanded polynomial according to the preset optimization algorithm, the method further includes: Based on the relationship between phase velocity and dispersion relation, an approximate expanded dispersion relation is obtained; The objective function is constructed based on the exact dispersion relation and the approximate expanded dispersion relation.

5. The earthquake processing method based on seismic wave field numerical simulation according to claim 1, characterized in that: Solving the objective function corresponding to the expanded polynomial according to a preset optimization algorithm to obtain the polynomial optimization coefficient of the expanded polynomial includes: The objective function is solved according to a least squares optimization algorithm to obtain polynomial optimization coefficients of the expanded polynomial.

6. The earthquake processing method based on numerical simulation of earthquake wave fields according to claim 1, characterized in that: The step of solving the anisotropic pure mode wave equation to obtain a numerical value of the anisotropic pure mode wave equation includes: The pure mode wave equation is solved by combining finite difference and pseudo-spectral method to obtain the numerical value of the anisotropic pure mode wave equation.

7. A seismic processing device based on numerical simulation of seismic wave fields, characterized in that: include: An approximate expansion module is used to perform polynomial approximate expansion on the dispersion relation of anisotropic pure mode P waves and SV waves to obtain the expansion polynomial; A first processing module, used to solve the objective function corresponding to the expanded polynomial according to a preset optimization algorithm, and obtain the polynomial optimization coefficient of the expanded polynomial; A conversion module, used for converting the optimized dispersion relation of P wave and SV wave into the time-space domain to obtain anisotropic pure mode wave equation, wherein the optimized dispersion relation of P wave and SV wave is an expanded polynomial after the optimized coefficient of the polynomial is brought into the equation; The second processing module is used to solve the anisotropic pure mode wave equation, realize the numerical simulation of the seismic wave field, and predict the real-time earthquake based on the numerical simulation result.

8. The seismic processing device based on seismic wave field numerical simulation according to claim 7, characterized in that: Also includes: An acquisition module, used to obtain the decoupled P-wave phase velocity relationship and SV-wave phase velocity relationship in anisotropic media; The conversion module is used to convert the decoupled P-wave phase velocity relation and SV-wave phase velocity relation into anisotropic pure mode P-wave and SV-wave dispersion relation based on the relationship between wave number, phase velocity and angular frequency.

9. An electronic device, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program that can be run on the processor, and when the program code is executed by the processor, the steps of the seismic processing method based on seismic wave field numerical simulation as described in any one of claims 1 to 6 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the seismic processing method based on seismic wave field numerical simulation as claimed in any one of claims 1 to 6 are implemented.

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