Method and apparatus for elastic wave mode separation in a vti medium
By obtaining polarization vectors and pseudo-derivative operators to separate elastic wave fields in vertically and laterally isotropic media, the problems of imaging bias and wave mode aliasing in anisotropic media in existing technologies are solved, and high-quality imaging of underground structures is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-12-23
- Publication Date
- 2026-06-23
Smart Images
Figure CN122260432A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of elastic wave inversion imaging technology in petroleum seismic exploration, and more specifically, to a method and apparatus for separating elastic wave modes in VTI media. Background Technology
[0002] In the field of geophysical exploration, especially in seismic wave exploration, elastic wave propagation simulation and imaging techniques are key tools for understanding subsurface structures. Traditional seismic data processing methods typically assume that the medium is isotropic, using a single velocity model to describe the subsurface medium. However, real subsurface media often exhibit anisotropic characteristics, such as vertical transverse isotropy (VTI), diagonal transverse isotropy (TTI), and orthorhombic anisotropy.
[0003] With the development of exploration technology, the demand for accurate imaging of underground structures is increasing, especially in complex geological environments such as pre-salt oil and gas reservoirs and shale gas reservoirs. The anisotropic characteristics of the medium in these areas have a significant impact on the propagation of seismic waves and the quality of imaging.
[0004] Existing seismic data processing techniques mainly include seismic wavefield reconstruction, wave mode separation, and extraction of imaging conditions. For example, Helmholtz decomposition is a commonly used wave mode separation method that uses divergence and curl operators to decompose the seismic wavefield into scalar and vector potentials.
[0005] However, this method is effective in isotropic media but has limitations in anisotropic media. The main problems include: insufficient handling of anisotropic media: existing techniques often simplify anisotropic media to isotropic models, ignoring the true physical properties of the medium, leading to imaging biases. Incomplete wave mode separation: in anisotropic media, the propagation velocities and polarization directions of P-waves and S-waves are closely related to the anisotropy parameters of the medium. Traditional separation methods cannot accurately distinguish aliased wave modes, affecting image quality. Limitations of imaging conditions: existing imaging conditions, such as conventional cross-correlation imaging, cannot effectively separate different wave modes, resulting in wave mode aliasing and image artifacts in the imaging results. Balancing computational efficiency and accuracy: when processing large-scale 3D seismic data, a balance needs to be found between computational efficiency and imaging accuracy.
[0006] Therefore, how to solve the above problems is an urgent issue that needs to be addressed. Summary of the Invention
[0007] This application provides a method and apparatus for separating elastic wave modes in VTI media, aiming to improve the above-mentioned problems.
[0008] In a first aspect, this application provides a method for separating elastic wave modes in a VTI medium, the method comprising:
[0009] Obtain the polarization vector of the elastic wave to be separated at each point in the vertically and laterally isotropic medium;
[0010] Calculate the pseudo-derivative operator of the polarization vector in the spatial domain;
[0011] The field of the elastic wave is separated into the field of the compression wave and the field of the shear wave according to the pseudo-derivative operator.
[0012] In one possible embodiment, obtaining the polarization vector of the elastic wave to be separated at each point in the vertically and laterally isotropic medium includes:
[0013] Obtain the medium density of the vertically and laterally isotropic medium and the phase velocity of the elastic wave;
[0014] The Christoph equation is solved based on the medium density and the phase velocity to obtain the polarization vector of each medium point.
[0015] In one possible embodiment, solving the Christopher equation yields:
[0016]
[0017] Where ρ is the density of the medium, v is the phase velocity, and E is the identity matrix;
[0018] Solve Obtain the feature vector U = {U x U z The eigenvectors are used to represent the polarization vectors of compression waves and shear waves.
[0019] In one possible embodiment, the operator for calculating the pseudo-derivative of the polarization vector in the spatial domain includes:
[0020] Calculate the polarization vector components of the polarization vector in the wavenumber domain;
[0021] Perform an inverse Fourier transform on the polarization vector components to obtain the pseudo-derivative operator of the polarization vector in the spatial domain.
[0022] In one possible embodiment, the pseudo-derivative operator satisfies:
[0023]
[0024] Among them, B i (x, z) is the pseudo-derivative operator, where i represents the x or z direction. U represents the inverse Fourier transform. i (kx k z ) represents the polarization vector component.
[0025] In one possible embodiment, the field of the compression wave satisfies:
[0026] P = B x W x +B z W z ;
[0027] Where P represents the field of the compression wave, W x and W z These are the components of the elastic wave field in the x and z directions.
[0028] In one possible embodiment, the field of the shear wave satisfies:
[0029] S = B z W x -B x W z ;
[0030] Where S represents the field of the shear wave, W x and W z These are the components of the elastic wave field in the x and z directions.
[0031] Secondly, this application provides an elastic wave mode separation device in a VTI medium, the device comprising:
[0032] The first processing unit is used to obtain the polarization vector of the elastic wave to be separated at each medium point in the vertically and laterally isotropic medium.
[0033] The second processing unit is used to calculate the pseudo-derivative operator of the polarization vector in the spatial domain;
[0034] A separation unit is used to separate the field of the elastic wave into the field of the compression wave and the field of the shear wave according to the pseudo-derivative operator.
[0035] In one possible embodiment, the first processing unit is specifically used for:
[0036] Obtain the medium density of the vertically and laterally isotropic medium and the phase velocity of the elastic wave;
[0037] The Christoph equation is solved based on the medium density and the phase velocity to obtain the polarization vector of each medium point.
[0038] In one possible embodiment, the second processing unit is specifically used for:
[0039] Calculate the polarization vector components of the polarization vector in the wavenumber domain;
[0040] Performing an inverse Fourier transform on the polarization vector components yields the pseudo-derivative operator of the polarization vector in the spatial domain.
[0041] The present application provides a method and apparatus for separating elastic wave modes in VTI media. This application obtains the polarization vector of the elastic wave to be separated at each point in a vertically and laterally isotropic medium; calculates the pseudo-derivative operator of the polarization vector in the spatial domain; and separates the elastic wave field into compression wave and shear wave fields based on the pseudo-derivative operator. Thus, the polarization vector is obtained and converted into a pseudo-derivative operator in the spatial domain, achieving effective separation of P-waves and S-waves. This method is applicable to VTI media, can adapt to spatial variations in medium parameters, significantly improves the quality and accuracy of seismic imaging, and has broad application prospects and significant practical application value. Attached Figure Description
[0042] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0043] Figure 1 This is a schematic diagram of the structure of an electronic device provided in the first embodiment of this application;
[0044] Figure 2 A flowchart of an elastic wave mode separation method in a VTI medium provided in the second embodiment of this application;
[0045] Figure 3 for Figure 2 A schematic diagram of the polarization vectors of P-wave and S-wave in an elastic wave mode separation method in VTI medium is shown.
[0046] Figure 4 for Figure 2 The diagram shows a method for separating elastic wave modes in a VTI medium before and after elastic wave separation.
[0047] Figure 5 This is a functional module diagram of an elastic wave mode separation device in a VTI medium provided in the third embodiment of this application. Detailed Implementation
[0048] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0049] First embodiment:
[0050] Figure 1 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. In this application, it can be... Figure 1 The schematic diagram shown illustrates an example electronic device 100 for implementing the elastic wave mode separation method and apparatus in the VTI medium according to embodiments of this application.
[0051] like Figure 1 The diagram shows the structure of an electronic device 100. The electronic device 100 includes one or more processors 102, one or more storage devices 104, input devices 106, and output devices 108. These components are interconnected via a bus system and / or other forms of connection mechanisms (not shown). It should be noted that... Figure 1 The components and structure of the electronic device 100 shown are merely exemplary and not limiting; the electronic device may have, as needed. Figure 1 The components shown may also have Figure 1 Other components and structures not shown.
[0052] The processor 102 may be a central processing unit (CPU) or other form of processing unit with data processing capabilities and / or instruction execution capabilities, and may control other components in the electronic device 100 to perform desired functions.
[0053] It should be understood that the processor 102 in the embodiments of this application can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.
[0054] The storage device 104 may include one or more computer program products, which may include various forms of computer-readable storage media.
[0055] It should be understood that the storage device 104 in the embodiments of this application may be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory may be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of random access memory (RAM) are available, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate synchronous DRAM (DDR SDRAM), enhanced synchronous DRAM (ESDRAM), synchronous linked DRAM (SLDRAM), and direct rambus RAM (DR RAM).
[0056] The computer-readable storage medium may store one or more computer program instructions, which the processor 102 may execute to implement the client functions (implemented by the processor) in the embodiments of this application described below, and / or other desired functions. Various applications and various data may also be stored in the computer-readable storage medium, such as various data used and / or generated by the applications.
[0057] The input device 106 may be a device used by a user to input commands, and may include one or more of the following: keyboard, mouse, microphone, and touch screen.
[0058] Second embodiment:
[0059] Reference Figure 2 The flowchart shown illustrates a method for separating elastic wave modes in a VTI medium. This method specifically includes the following steps:
[0060] Step S201: Obtain the polarization vector of the elastic wave to be separated at each point in the vertically and laterally isotropic medium.
[0061] Optionally, step S021 includes: obtaining the medium density of the vertically and laterally isotropic medium and the phase velocity of the elastic wave; solving the Christopher equation based on the medium density and the phase velocity to obtain the polarization vector of each medium point.
[0062] Solving the Christopher equation yields:
[0063]
[0064] Where ρ is the density of the medium, v is the phase velocity, and E is the identity matrix;
[0065] Solve Obtain the feature vector U = {U x U z The eigenvectors are used to represent the polarization vectors of compression and shear waves. That is, U x U represents the polarization vector of the compression wave (i.e., the polarization vector of the P-wave); z This represents the polarization vector of the shear wave (i.e., the polarization vector of the P-wave).
[0066] For example, such as Figure 3 As shown in Figure a, the polarization vector of the P-wave is as follows: Figure 3 As shown in b, this is the polarization vector of the S-wave.
[0067] Understandably, by using the Christoffel equations to determine the phase velocity and polarization direction of waves propagating in a medium, a wave mode separation operator applicable to anisotropic media can be constructed.
[0068] Step S202: Calculate the pseudo-derivative operator of the polarization vector in the spatial domain.
[0069] As one implementation, step S202 includes: calculating the polarization vector component in the wavenumber domain; performing an inverse Fourier transform on the polarization vector component to obtain the pseudo-derivative operator of the polarization vector in the spatial domain.
[0070] The pseudo-derivative operator satisfies:
[0071]
[0072] Among them, B i (x,z) is the pseudo-derivative operator, where i represents the x or z direction. U represents the inverse Fourier transform. i (kx k z ) represents the polarization vector component.
[0073] Understandably, by using the formula in step S201 to transform the polarization vector in the wavenumber domain to the spatial domain, a local "pseudo" derivative operator is constructed. These operators are then used to simulate spatially varying derivative operations, adapting to the anisotropic characteristics of the medium.
[0074] Step S203: Separate the field of the elastic wave into the field of the compression wave and the field of the shear wave according to the pseudo-derivative operator.
[0075] The field of the compression wave satisfies:
[0076] P = B x W x +B z W z ;
[0077] Where P represents the field of the compression wave, W x and W z These are the components of the elastic wave field in the x and z directions.
[0078] The field of the shear wave satisfies:
[0079] S = B z W x -B x W z ;
[0080] Where S represents the field of the shear wave, W x and W z These are the components of the elastic wave field in the x and z directions.
[0081] For example, such as Figure 4 As shown in Figure a, the original elastic wave X component W is represented. x , Figure 4 The original elastic wave Z component W shown in Figure b z , Figure 4 The separated P-wave is shown in Figure c. Figure 4 The S-wave after separation is shown in d.
[0082] In summary, the elastic wave mode separation method in VTI media provided in this application obtains the polarization vector by solving the Christoffel equation and converts it into a pseudo-derivative operator in the spatial domain, thus achieving effective separation of P-waves and S-waves. This method is applicable to VTI media, can adapt to spatial variations in medium parameters, significantly improves the quality and accuracy of seismic imaging, and has broad application prospects and significant practical value. Especially in complex geological structures, such as pre-salt oil and gas reservoirs, this invention can effectively reduce wave mode aliasing and provide clearer images of subsurface structures.
[0083] Third embodiment:
[0084] Based on the same inventive concept, this embodiment provides an elastic wave mode separation device in a VTI medium, such as... Figure 5 As shown, the elastic wave mode separation device in the VTI medium includes: a first processing unit 510, a second processing unit 520, and a separation unit 530, wherein the specific functions of each unit are as follows:
[0085] The first processing unit 510 is used to acquire the polarization vector of the elastic wave to be separated at each medium point in the vertical and transverse isotropic medium.
[0086] The second processing unit 520 is used to calculate the pseudo-derivative operator of the polarization vector in the spatial domain;
[0087] The separation unit 530 is used to separate the field of the elastic wave into the field of the compression wave and the field of the shear wave according to the pseudo-derivative operator.
[0088] Optionally, the first processing unit 510 is specifically used to: obtain the medium density of the vertically and laterally isotropic medium and the phase velocity of the elastic wave; and solve the Christopher equation based on the medium density and the phase velocity to obtain the polarization vector of each medium point.
[0089] Alternatively, solving the Christopher equation yields:
[0090]
[0091] Where ρ is the density of the medium, v is the phase velocity, and E is the identity matrix;
[0092] Solve Obtain the feature vector U = {U x U z The eigenvectors are used to represent the polarization vectors of compression waves and shear waves.
[0093] Optionally, the second processing unit 520 is specifically used to: calculate the polarization vector component in the wavenumber domain; and perform an inverse Fourier transform on the polarization vector component to obtain the pseudo-derivative operator of the polarization vector in the spatial domain.
[0094] Optionally, the pseudo-derivative operator satisfies:
[0095]
[0096] Among them, B i (x,z) is the pseudo-derivative operator, where i represents the x or z direction. U represents the inverse Fourier transform. i (k x k z ) represents the polarization vector component.
[0097] Optionally, the field of the compression wave satisfies:
[0098] P = B x W x +B z W z ;
[0099] Where P represents the field of the compression wave, W x and W z These are the components of the elastic wave field in the x and z directions.
[0100] The field of the shear wave satisfies:
[0101] S = B z V x -B x W z ;
[0102] Where S represents the field of the shear wave, W x and W z These are the components of the elastic wave field in the x and z directions.
[0103] Furthermore, this embodiment also provides a computer-readable storage medium storing a computer program, which, when run by a processing device, executes the steps of any of the elastic wave mode separation methods in the VTI medium provided in Embodiment 2 above.
[0104] The computer program product of the elastic wave mode separation method and apparatus in VTI medium provided in this application includes a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the methods described in the preceding method embodiments. For specific implementation, please refer to the method embodiments, which will not be repeated here.
[0105] In summary, the elastic wave mode separation method and apparatus in VTI media provided in this application achieves effective separation of P-waves and S-waves by solving the Christoffel equation to obtain the polarization vector and converting it into a pseudo-derivative operator in the spatial domain. This method is applicable to VTI media, adapts to spatial variations in medium parameters, significantly improves the quality and accuracy of seismic imaging, and has broad application prospects and significant practical value. Especially in complex geological structures, such as pre-salt oil and gas reservoirs, this invention can effectively reduce wave mode aliasing and provide clearer images of subsurface structures.
[0106] It should be noted that the above embodiments can be implemented, in whole or in part, by software, hardware (such as circuits), firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, in the form of a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. A semiconductor medium can be a solid-state drive.
[0107] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.
[0108] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, at least one of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple.
[0109] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.
[0110] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.
[0111] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.
[0112] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.
[0113] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.
[0114] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.
[0115] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.
Claims
1. A method for separating elastic wave modes in a VTI medium, characterized in that, The method includes: Obtain the polarization vector of the elastic wave to be separated at each point in the vertically and laterally isotropic medium; Calculate the pseudo-derivative operator of the polarization vector in the spatial domain; The field of the elastic wave is separated into the field of the compression wave and the field of the shear wave according to the pseudo-derivative operator.
2. The method according to claim 1, characterized in that, The process of obtaining the polarization vector of the elastic wave to be separated at each point in the vertically and laterally isotropic medium includes: Obtain the medium density of the vertically and laterally isotropic medium and the phase velocity of the elastic wave; The Christoph equation is solved based on the medium density and the phase velocity to obtain the polarization vector of each medium point.
3. The method according to claim 2, characterized in that, Solving the Christopher equation yields: Where ρ is the density of the medium, v is the phase velocity, and E is the identity matrix; Solve Obtain the feature vector U = {U x U z The eigenvectors are used to represent the polarization vectors of compression waves and shear waves.
4. The method according to claim 1, characterized in that, The operator for calculating the pseudo-derivative of the polarization vector in the spatial domain includes: Calculate the polarization vector components of the polarization vector in the wavenumber domain; Perform an inverse Fourier transform on the polarization vector components to obtain the pseudo-derivative operator of the polarization vector in the spatial domain.
5. The method according to claim 4, characterized in that, The pseudo-derivative operator satisfies: Among them, B i (x, z) is the pseudo-derivative operator, where i represents the x or z direction. U represents the inverse Fourier transform. i (k x k z ) represents the polarization vector component.
6. The method according to claim 5, characterized in that, The field of the compression wave satisfies: P=B x W x +B z W z ; Where P represents the field of the compression wave, W x and W z These are the components of the elastic wave field in the x and z directions.
7. The method according to claim 5, characterized in that, The field of the shear wave satisfies: S=B z W x -B x W z ; Where S represents the field of the shear wave, W x and W z These are the components of the elastic wave field in the x and z directions.
8. An elastic wave mode separation device in a VTI medium, characterized in that, The device includes: The first processing unit is used to obtain the polarization vector of the elastic wave to be separated at each medium point in the vertically and laterally isotropic medium. The second processing unit is used to calculate the pseudo-derivative operator of the polarization vector in the spatial domain; A separation unit is used to separate the field of the elastic wave into the field of the compression wave and the field of the shear wave according to the pseudo-derivative operator.
9. The apparatus according to claim 8, characterized in that, The first processing unit is specifically used for: Obtain the medium density of the vertically and laterally isotropic medium and the phase velocity of the elastic wave; The Christoph equation is solved based on the medium density and the phase velocity to obtain the polarization vector of each medium point.
10. The apparatus according to claim 8, characterized in that, The second processing unit is specifically used for: Calculate the polarization vector components of the polarization vector in the wavenumber domain; Perform an inverse Fourier transform on the polarization vector components to obtain the pseudo-derivative operator of the polarization vector in the spatial domain.