Patent Grant
11966001
This application claims priority to Chinese Patent Application No. 202311139493.2, filed on Sep. 6, 2023, which is hereby incorporated by reference in its entirety.
The present disclosure relates to the field of geophysical exploration and acoustic exploration technologies, and in particular, to a calculation method, storage medium, and device for a seabed reflection coefficient of point source elastic wave.
The reflection coefficient of seabed elastic wave contains rich information on seismic wave fields (or sound fields) and elastic parameters of seabed sediments. The calculation of seabed reflection coefficient is the foundation of analyzing seabed reflection wave fields and inverting seabed elastic parameters. At present, the calculation methods for the seabed reflection coefficient are mostly based on the plane wave assumption, while the hypocenter (sound source) is mostly equivalent point sources, which renders the calculation method based on plane wave only be able to accurately describe the seabed reflection coefficient in far-field, high-frequency, and small incidence angles. The plane wave assumption cannot accurately describe the frequency variation and phase characteristics of the seabed reflection coefficient, and also cannot provide an appropriate amplitude information of the reflection coefficient under large incidence angles. Although the calculation complexity of plane wave reflection coefficient is low, the limitations of plane wave assumption limit its applicability in the above scenarios. Although the calculation method of point source reflection coefficient can avoid the limitations of plane wave assumption, its calculation process is complex and inefficient, which hinders the practical application of point source reflection coefficient. Therefore, it is necessary to improve the original calculation method to address the complex and inefficient calculation of point source seabed reflection coefficient. A concise and efficient method for calculating the seabed reflection coefficient of point source elastic wave is provided to ensure calculation accuracy and meet the needs of seabed reflection wave field analysis and seabed elastic parameter inversion.
In order to solve the problems of high complexity and low efficiency in the calculation process of a seabed reflection coefficient of point source elastic wave mentioned above, the present disclosure proposes a calculation method, storage medium, and device for a seabed reflection coefficient of point source elastic wave. The method converts the solution of seabed reflection coefficient of point source into the solution of an undetermined coefficient of an equivalent equation and a concise expression of the seabed reflection coefficient of point source by solving the undetermined coefficient of the equivalent equation in advance is obtained, and the seabed reflection coefficient of point source elastic wave is efficiently calculated by using this expression.
The present disclosure is implemented through the following technical solutions.
A calculation method for a seabed reflection coefficient of point source elastic wave, including the following steps:
In an embodiment of the present disclosure, in step 2, the parameter space is discretized to obtain M=[m1 m2 . . . mn]T, a corresponding seabed reflection coefficient of point source elastic wave is denoted as R=[r1′ r2′ . . . rn′]T, m is discrete points for each parameter that are evenly distributed within an initialized parameter space calculation range at intervals in the accuracy set in step 1; r′ is the seabed reflection coefficient obtained from the traditional calculation method for the seabed reflection coefficient of point source elastic wave. Where, the traditional calculation method for the seabed reflection coefficient of point source elastic wave includes a reflection spherical wave integration method, a wave equation method, and a reflectivity calculation method.
In an embodiment of the present disclosure, in step 3, the equivalent equation and the traditional calculation equation for the seabed reflection coefficient of point source elastic wave are combined by the following equation:
f(W,m)=r←r′ (1),
in equation (1), f(w,m)=r represents the equivalent equation, W is an undetermined coefficient of the equivalent equation, r is the seabed reflection coefficient, ← represents an assignment to a variable, and r′ is the seabed reflection coefficient obtained by the traditional calculation method for the seabed reflection coefficient of point source elastic wave; the combination is performed within a parameter space range to obtain the following:
f(W,M)=R (2),
in equation (2), R is the seabed reflection coefficient of the point source elastic wave.
In an embodiment of the present disclosure, in step 4, the undetermined coefficient of the equivalent equation is solved by the following equation:
W=G−1R (3),
in equation (3), G is a symmetric matrix Gij=φ(mi,mj) composed of Gaussian kernel function, i,j∈{k|k>0&k∈N}, R is the seabed reflection coefficient of the point source elastic wave.
In an embodiment of the present disclosure, the concise expression for the seabed reflection coefficient of point source obtained in step 5 is as follows:
r=g(m)·W (4),
in equation (4), g(m)=[φ(m1,m)φ(m2,m) . . . φ(mi,m)], W is the undetermined coefficient of the equivalent equation.
An embodiment of the present disclosure further provides a computer-readable storage medium, where a computer program is stored thereon, the computer program implements the calculation method for a seabed reflection coefficient of point source elastic wave when be loaded and executed by a processor.
An embodiment of the present disclosure further provides a computer device including a memory and a processor, where a computer program is stored on the memory, the computer program implements the calculation method for a seabed reflection coefficient of point source elastic wave when executed by the processor.
The beneficial effects of the present disclosure compared to prior art are as following:
the present disclosure proposes a calculation method for a seabed reflection coefficient of point source elastic wave, which converts a solution of the seabed reflection coefficient of point source into a solution of the undetermined coefficient of the equivalent equation. By solving the undetermined coefficient of the equivalent equation in advance, a concise expression for the seabed reflection coefficient of point source is obtained. The calculation time of the calculation method required by the present disclosure is greatly reduced, which greatly improves the calculation efficiency, and on the premise of ensuring calculation accuracy, a problem of high complexity and low efficiency in the calculation process of seabed reflection coefficient of point source elastic wave has been avoided, thereby promoting a practical application of the reflection coefficient of point source.
The present disclosure is further described in detail below, and the proposed embodiments are only a part of the present application and not all of them. Based on the embodiments in the present disclosure, all other embodiments obtained by relevant technical personnel without creative work fall within the protection scope of the present disclosure.
An embodiment of the present disclosure provides a calculation method for a seabed reflection coefficient of point source elastic wave, as shown in
In this embodiment, the calculation accuracy and calculation range of the seabed reflection coefficient are constrained by initializing input parameters (including seabed elastic parameters, frequency, and propagation distance). The calculation range of parameter space is represented by Ω, Ω={(α,β, ρ, f, h)|α∈[1450 1550],β∈[100 200], ρ∈[1500 1600], f∈[40 60], h∈[90 110]} and the calculation accuracy is represented by δ, δ=[δα δβ δρ δf δh]=[50 50 50 5 5]. And the seabed longitudinal wave velocity, seabed transverse wave velocity, seabed density, frequency, and propagation distance are represented by α, β, ρ, f, h, respectively; all variables adopt the International System of Units.
Step 2: discretizing a parameter space and obtaining the seabed reflection coefficient of point source elastic wave.
By discretizing an input parameter according to an initialized parameter in step 1, M=[m1 m2 . . . mn]T is obtained, it is obvious that in this embodiment, the number of discrete samples n=675, and the parameter space includes seabed longitudinal wave velocity, seabed transverse wave velocity, seabed density, frequency, and propagation distance m=[α β ρ f h]. The discretized parameters of this embodiment are shown in
By utilizing the discretized parameters mentioned above, the seabed reflection coefficient can be obtained from the traditional calculation method of the seabed reflection coefficient of point source elastic wave. The traditional calculation method of the seabed reflection coefficient of point source elastic wave includes the reflection spherical wave integration method, wave equation method, and reflectance calculation method, and calculation results obtained from various methods are consistent with each other. The seabed reflection coefficients R=[r1′ r2′ . . . rn′]T corresponding to the discretized parameters obtained in this embodiment are shown in
Step 3: combining an equivalent equation with a traditional calculation equation for the seabed reflection coefficient of point source elastic wave.
Traditional calculation equation for the seabed reflection coefficient of point source elastic wave is combined with the equivalent equation through an assignment to a variable:
f(W,m)=r←r′ (1),
in equation (1), f (w,m)=r represents the equivalent equation, W is an undetermined coefficient of the equivalent equation, r is the seabed reflection coefficient, ← represents an assignment to a variable; the combination is performed within a parameter space range to obtain the following:
f(W,M)=R (2),
this embodiment wrote equation (2) to GW=R, G is a symmetric matrix Gij=φ(mi,mj) composed of Gaussian kernel function, i,j∈{k|k>0&k∈N}.
Step 4: solving the undetermined coefficient of the equivalent equation in step 3 with the following equation to obtain the undetermined coefficient of the equivalent equation.
W=G−1R (3),
The undetermined coefficients of the equivalent equation calculated in this embodiment are shown in
Step 5: obtaining a concise expression for the seabed reflection coefficient of point source under an accuracy in step 1 with the following equation:
r=g(m)·W (4),
in equation (4), g(m)=[φ(m1,m)φ(m2,m) . . . φ(mi,m)], φ is Gaussian function.
Step 6: calculating the seabed reflection coefficient of point source elastic wave within a given calculation accuracy range using the concise expression obtained in step 5.
As shown in Table 1, this embodiment calculates the seabed reflection coefficient of point source elastic wave for a center value (value 1) and a center deviation value (value 2, value 3) in the calculation range. Calculation results are shown in
From the above results, it can be seen that the efficient calculation method for the seabed reflection coefficient of point source elastic wave proposed by the present disclosure not only has lower computational complexity and higher computational efficiency, but also can achieve the same accuracy as existing calculation methods, which avoids the limitations caused by plane wave calculation errors, and thereby promoting a practical application of point source reflection coefficient.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202311139493.2 | Sep 2023 | CN | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20020173916 | Chakraborty | Nov 2002 | A1 |
| 20030214287 | Sun | Nov 2003 | A1 |
| Number | Date | Country |
|---|---|---|
| 104570072 | Apr 2015 | CN |
| 105629301 | Jun 2016 | CN |
| 107576388 | Jan 2018 | CN |
| 116520431 | Aug 2023 | CN |
| 116660996 | Aug 2023 | CN |
| 116859460 | Oct 2023 | CN |
| 116879952 | Oct 2023 | CN |
| 03087878 | Oct 2003 | WO |
| 2013169117 | Nov 2013 | WO |
| Entry |
|---|
| Recursive calculation of reflection coefficients in multi-component seismic records in the frequency-wavenumber domain, Gu Hanming1), Wang Jiaying1), Zhu Guangming2), Chinese Journal of Geophysics, 2002, Issue 2, issued on Mar. 31, 2002. |
