Mesh transformation method, system, device and medium based on model region decomposition

Abstract

The application discloses a grid conversion method, system, device and medium based on model area decomposition. The method comprises the following steps: mapping a three-dimensional grid body to a two-dimensional chessboard, and representing a grid unit by a chessboard grid number; sorting the grid units according to the chessboard grid number and storing the grid units in a file; fusing the number and storage position of the grid units in each chessboard grid into a two-dimensional chessboard to obtain a template, and storing the template in the file; determining a three-dimensional grid body calculation area corresponding to each shot, obtaining the number and storage position of the grid units to be cut based on the template, and obtaining the grid units to be subjected to finite element calculation from the file. The system comprises function modules for realizing the above steps. The device is realized by a processor executing a computer program stored in a memory. The medium is realized by a computer program stored in a memory being executed by a processor. According to the application, the problem of low calculation efficiency of the existing finite element forward algorithm applied to seismic wave numerical simulation can be solved.

Description

Technical Field

[0001] This invention belongs to the field of seismic forward modeling three-dimensional finite element mesh generation, and more specifically, relates to a mesh transformation method, system, device and medium based on model domain decomposition. Background Technology

[0002] Currently, the key areas for oil and gas exploration in my country are mainly in the western region. However, the complex surface and subsurface conditions in the western region bring many difficulties to seismic exploration, such as static correction and signal-to-noise ratio issues. Solving these problems requires exploration personnel to have a deep understanding of the development mechanisms of various surface and subsurface waves, and high-precision seismic numerical simulation algorithms will provide powerful tools and support for this. Compared with the finite difference algorithm, the finite element algorithm is more suitable for simulating wavefields on complex surfaces, but the three-dimensional finite element algorithm has a large computational load and is difficult to mesh. Therefore, improving the computational efficiency of the three-dimensional finite element algorithm and solving the related technical problems of mesh generation as soon as possible is of great significance for the algorithm to reach the level of practical application.

[0003] Specifically, in numerical simulations of seismic waves, it is usually unnecessary to calculate the entire geological model for each shot. Instead, the simulation focuses on a computational region within the geological model corresponding to the seismic exploration and observation system range of the current shot. This numerical simulation method is generally well-implemented using the finite difference algorithm, but fully automating the entire process from obtaining the model's geometric information for the computational region (current shot) to effective mesh generation using the finite element method (FEM) is quite challenging. Typically, the FEM algorithm first meshes the entire model based on its geometric information and then performs wavefield calculations. This requires calculating the entire model for each shot, significantly reducing computational efficiency. Summary of the Invention

[0004] The purpose of this invention is to solve the problem of low computational efficiency of existing finite element forward modeling algorithms used in numerical simulation of seismic waves.

[0005] To achieve the above objectives, the present invention provides a mesh transformation method, system, device, and medium based on model domain decomposition.

[0006] According to a first aspect of the present invention, a mesh transformation method based on model domain decomposition is provided, the method comprising the following steps:

[0007] Obtain a three-dimensional geological model of the target seismic exploration area;

[0008] The three-dimensional geological model is meshed using the finite element method to obtain a three-dimensional mesh volume;

[0009] The ground area of ​​the three-dimensional mesh is divided into a chessboard pattern to obtain a two-dimensional chessboard.

[0010] Each grid cell of the three-dimensional mesh is mapped onto the two-dimensional chessboard, and the grid cell is characterized by the number of the chessboard square on the two-dimensional chessboard that has a mapping relationship with each grid cell.

[0011] Sort all grid cells according to their checkerboard grid numbers, and store the sorted grid cells in a file.

[0012] The number and storage position of the grid cells in each chessboard square are merged into the two-dimensional chessboard to obtain a template, and the template is stored in the file;

[0013] After each seismic exploration blast, the finite element calculation area in the three-dimensional mesh corresponding to each seismic exploration blast is determined based on the seismic exploration observation system;

[0014] Based on the region to be calculated using finite element analysis, the number and storage location of the mesh elements to be cut are obtained from the template, so as to obtain the mesh elements corresponding to the region to be calculated using finite element analysis from the file.

[0015] Preferably, the two-dimensional chessboard has a differential grid, the size of the two-dimensional chessboard is Nx*My, and the chessboard grid with coordinates (ix, jy) is numbered as (jy-1)*Nx+ix.

[0016] Preferably, the size of the chessboard squares in the two-dimensional chessboard does not exceed the size of the smallest grid cell in the three-dimensional grid.

[0017] Preferably, the step of mapping each grid cell of the three-dimensional mesh onto the two-dimensional chessboard, and characterizing the grid cell using the chessboard grid number that has a mapping relationship with each grid cell, specifically involves:

[0018] The three-dimensional centroid coordinates of each grid cell of the three-dimensional mesh are mapped onto the two-dimensional chessboard, and the three-dimensional centroid coordinates of each grid cell are converted into the numbers of the associated chessboard cells on the two-dimensional chessboard.

[0019] Preferably, the file is in .imm format.

[0020] Preferably, the file includes information about the template, storage location information of the grid cells, checkerboard grid number information of the grid cells, and three-dimensional centroid coordinate information of the grid cells.

[0021] Preferably, the three-dimensional mesh is a regular mesh or an unstructured mesh.

[0022] According to a second aspect of the present invention, a mesh transformation system based on model domain decomposition is provided, the system comprising the following functional modules:

[0023] The 3D geological model acquisition module is used to acquire a 3D geological model of the target seismic exploration area;

[0024] The three-dimensional mesh acquisition module is used to perform finite element mesh generation on the three-dimensional geological model to obtain a three-dimensional mesh.

[0025] The two-dimensional chessboard acquisition module is used to divide the ground area of ​​the three-dimensional mesh into a chessboard to obtain a two-dimensional chessboard.

[0026] The chessboard grid numbering and characterization module is used to map each grid cell of the three-dimensional mesh onto the two-dimensional chessboard, and to characterize the grid cell by using the number of the chessboard grid on the two-dimensional chessboard that has a mapping relationship with each grid cell.

[0027] The grid cell sorting module is used to sort all grid cells according to the checkerboard grid number of the grid cells and store the sorted grid cells to a file;

[0028] The template acquisition module is used to merge the number and storage position of the grid cells in each chessboard square into the two-dimensional chessboard to obtain a template, and to store the template in the file;

[0029] The module for obtaining the finite element calculation area is used to determine the finite element calculation area in the three-dimensional mesh corresponding to each seismic exploration blasting based on the seismic exploration observation system after each seismic exploration blasting.

[0030] The finite element calculation mesh cell acquisition module is used to obtain the number and storage location of the mesh cells to be cut out based on the template according to the finite element calculation region, so as to obtain the mesh cells corresponding to the finite element calculation region from the file.

[0031] According to a third aspect of the present invention, a mesh transformation device based on model domain decomposition is provided, the device comprising a processor and a memory, wherein the processor executes a computer program stored in the memory to implement any of the above-described mesh transformation methods based on model domain decomposition.

[0032] According to a fourth aspect of the present invention, a computer-readable storage medium is provided that, when executed by a processor, implements any of the above-described mesh transformation methods based on model domain decomposition.

[0033] The beneficial effects of this invention are as follows:

[0034] The mesh transformation method based on model region decomposition of the present invention comprises the following steps: First, obtaining a three-dimensional geological model of the target seismic exploration area; second, performing finite element meshing on the three-dimensional geological model to obtain a three-dimensional mesh volume; third, dividing the ground area of ​​the three-dimensional mesh volume into a checkerboard pattern to obtain a two-dimensional checkerboard; fourth, mapping each mesh unit of the three-dimensional mesh volume onto the two-dimensional checkerboard, and characterizing the mesh unit using the checkerboard grid number on the two-dimensional checkerboard that has a mapping relationship with each mesh unit; fifth, sorting all mesh units according to the checkerboard grid number of the mesh unit, and storing the sorted mesh units in a file; sixth, merging the number and storage position of the mesh units in each checkerboard grid into the two-dimensional checkerboard to obtain a template, and storing the template in the file; seventh, after each seismic exploration blast, determining the region to be calculated by finite element analysis in the three-dimensional mesh volume corresponding to each seismic exploration blast based on the seismic exploration observation system; finally, based on the region to be calculated by finite element analysis, obtaining the number and storage position of the mesh units to be cut based on the template, so as to obtain the mesh units corresponding to the region to be calculated by finite element analysis from the file.

[0035] The mesh transformation method based on model domain decomposition of this invention employs two main approaches. First, it maps a 3D mesh to a 2D chessboard and stores it in a sorted manner. The core idea behind this approach is dimensionality reduction, transforming a 3D problem into a 2D problem. Second, it selects the computational domain of the entire 3D geological model based on a seismic exploration and observation system. Before each selection, a template is used to obtain the number of mesh elements to be extracted and their storage location in the file, thus achieving a computational domain segmentation similar to the finite difference algorithm. Since the reordered mesh elements have properties similar to the differential regular mesh in terms of their spatial distribution on the Earth's surface, the computational efficiency of subsequent finite element forward modeling algorithms is significantly improved, exceeding 2.5 times compared to conventional finite element forward modeling algorithms. Therefore, the mesh transformation method based on model domain decomposition of this invention effectively solves the problem of low computational efficiency in existing finite element forward modeling algorithms applied to seismic wave numerical simulation.

[0036] The mesh conversion system, mesh conversion device, and computer-readable storage medium based on model domain decomposition of the present invention belong to the same general inventive concept as the mesh conversion method based on model domain decomposition described above, and therefore have the same beneficial effects as the mesh conversion method based on model domain decomposition described above, which will not be repeated here.

[0037] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0038] The above and other objects, features and advantages of the present invention will become more apparent from the more detailed description of exemplary embodiments of the invention in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the invention.

[0039] Figure 1 A flowchart illustrating the implementation of a mesh transformation method based on model domain decomposition according to Embodiment 1 of the present invention is shown.

[0040] Figure 2 A schematic diagram of chessboard-like division of the ground region of a three-dimensional mesh according to Embodiment 1 of the present invention is shown. Detailed Implementation

[0041] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0042] Example 1: Figure 1 A flowchart illustrating the implementation of the mesh transformation method based on model domain decomposition according to an embodiment of the present invention is shown. (Refer to...) Figure 1 The mesh transformation method based on model domain decomposition in this invention includes the following steps:

[0043] Step S100: Obtain a three-dimensional geological model of the target seismic exploration area;

[0044] Step S200: Perform finite element mesh generation on the three-dimensional geological model to obtain a three-dimensional mesh volume;

[0045] Step S300: Divide the ground area of ​​the three-dimensional mesh into a chessboard pattern to obtain a two-dimensional chessboard, as shown below. Figure 2 As shown;

[0046] Step S400: Map each grid cell of the three-dimensional mesh onto the two-dimensional chessboard, and characterize the grid cell by using the number of the chessboard square on the two-dimensional chessboard that has a mapping relationship with each grid cell;

[0047] Step S500: Sort all grid cells according to their checkerboard grid numbers and store the sorted grid cells in a file;

[0048] Step S600: Merge the number and storage position of the grid cells in each chessboard square into the two-dimensional chessboard to obtain a template, and store the template in the file;

[0049] Step S700: After each seismic exploration blast, determine the finite element calculation area in the three-dimensional mesh corresponding to each seismic exploration blast based on the seismic exploration observation system;

[0050] Step S800: Based on the region to be calculated by finite element method, obtain the number and storage location of the mesh elements to be cut out based on the template, so as to obtain the mesh elements corresponding to the region to be calculated by finite element method from the file;

[0051] In this embodiment of the invention, step S800 is used to provide mesh data of the finite element calculation area of ​​the three-dimensional geological model selected based on the seismic exploration and observation system for forward modeling.

[0052] Furthermore, in step S300 of this embodiment of the invention, the chessboard grid of the two-dimensional chessboard is a differential grid, the grid size is a user-specified parameter, and each chessboard grid has a unique number.

[0053] Specifically, the size of the two-dimensional chessboard is Nx*My, and the chessboard square with coordinates (ix, jy) is numbered as (jy-1)*Nx+ix.

[0054] Furthermore, in step S300 of this embodiment of the invention, the size of the chessboard grid in the two-dimensional chessboard does not exceed the size of the smallest grid unit in the three-dimensional grid. This setting is to ensure that each grid unit underground is more likely to have a different corresponding chessboard grid number.

[0055] Furthermore, in this embodiment of the invention, step S400, which maps each grid cell of the three-dimensional mesh onto the two-dimensional chessboard and uses the chessboard grid number that has a mapping relationship with each grid cell to characterize the grid cell, specifically involves:

[0056] The three-dimensional centroid coordinates of each grid cell of the three-dimensional mesh are mapped onto the two-dimensional chessboard, and the three-dimensional centroid coordinates of each grid cell are converted into the numbers of the associated chessboard cells on the two-dimensional chessboard.

[0057] Furthermore, in this embodiment of the invention, the file format is .imm.

[0058] Furthermore, in this embodiment of the invention, the file includes information about the template, storage location information of the grid cell, checkerboard number information of the grid cell, and three-dimensional centroid coordinate information of the grid cell.

[0059] Furthermore, in step S200 of this embodiment of the invention, the three-dimensional mesh is a regular mesh or an unstructured mesh.

[0060] The mesh transformation method based on model domain decomposition in this invention calculates the number of mesh cells to be cut and their storage location in the file using a template before each cutting of the 3D mesh volume, thereby achieving block cutting similar to finite difference. Clearly, the reordered mesh cells exhibit similar properties in terms of spatial distribution on the Earth's surface as those of a difference regular mesh.

[0061] The mesh transformation method based on model domain decomposition in this invention selects the finite element calculation area of ​​the 3D geological model based on a seismic exploration and observation system, which greatly improves the computational efficiency of the finite element forward modeling algorithm. Compared with conventional algorithms, the computational efficiency of this method is more than 2.5 times higher. This method is the first of its kind proposed and implemented both domestically and internationally, and has significant practical value.

[0062] Example 2: Based on the mesh transformation method based on model domain decomposition proposed in Example 1, this embodiment of the invention proposes a mesh transformation system based on model domain decomposition.

[0063] The mesh transformation system based on model domain decomposition in this invention includes the following functional modules:

[0064] The 3D geological model acquisition module is used to acquire a 3D geological model of the target seismic exploration area;

[0065] The three-dimensional mesh acquisition module is used to perform finite element mesh generation on the three-dimensional geological model to obtain a three-dimensional mesh.

[0066] The two-dimensional chessboard acquisition module is used to divide the ground area of ​​the three-dimensional mesh into a chessboard to obtain a two-dimensional chessboard.

[0067] The chessboard grid numbering and characterization module is used to map each grid cell of the three-dimensional mesh onto the two-dimensional chessboard, and to characterize the grid cell by using the number of the chessboard grid on the two-dimensional chessboard that has a mapping relationship with each grid cell.

[0068] The grid cell sorting module is used to sort all grid cells according to the checkerboard grid number of the grid cells and store the sorted grid cells to a file;

[0069] The template acquisition module is used to merge the number and storage position of the grid cells in each chessboard square into the two-dimensional chessboard to obtain a template, and to store the template in the file;

[0070] The module for obtaining the finite element calculation area is used to determine the finite element calculation area in the three-dimensional mesh corresponding to each seismic exploration blasting based on the seismic exploration observation system after each seismic exploration blasting.

[0071] The finite element calculation mesh cell acquisition module is used to obtain the number and storage location of the mesh cells to be cut out based on the template according to the finite element calculation region, so as to obtain the mesh cells corresponding to the finite element calculation region from the file.

[0072] Example 3: Based on the mesh transformation method based on model domain decomposition proposed in Example 1, this embodiment of the invention proposes a mesh transformation device based on model domain decomposition.

[0073] The mesh transformation device based on model domain decomposition according to this invention includes a processor and a memory. When the processor executes the computer program stored in the memory, it implements the mesh transformation method based on model domain decomposition proposed in Embodiment 1.

[0074] Example 4: Based on the mesh transformation method based on model domain decomposition proposed in Example 1, this embodiment of the invention proposes a computer-readable storage medium.

[0075] The computer-readable storage medium of this invention is used to store a computer program, which, when executed by a processor, implements the mesh transformation method based on model region decomposition proposed in Embodiment 1.

[0076] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A mesh transformation method based on model domain decomposition, characterized in that, include: Obtain a three-dimensional geological model of the target seismic exploration area; The three-dimensional geological model is meshed using the finite element method to obtain a three-dimensional mesh volume; The ground area of ​​the three-dimensional mesh is divided into a chessboard pattern to obtain a two-dimensional chessboard. Each grid cell of the three-dimensional mesh is mapped onto the two-dimensional chessboard, and the grid cell is characterized by the number of the chessboard square on the two-dimensional chessboard that has a mapping relationship with each grid cell. Sort all grid cells according to their checkerboard grid numbers, and store the sorted grid cells in a file. The number and storage position of the grid cells in each chessboard square are merged into the two-dimensional chessboard to obtain a template, and the template is stored in the file; After each seismic exploration blast, the finite element calculation area in the three-dimensional mesh corresponding to each seismic exploration blast is determined based on the seismic exploration observation system; Based on the region to be calculated by finite element analysis, the number and storage location of the mesh elements to be cut are obtained based on the template, so as to obtain the mesh elements corresponding to the region to be calculated by finite element analysis from the file; The specific steps of mapping each grid cell of the three-dimensional mesh onto the two-dimensional chessboard, and representing the grid cell using the chessboard grid number that has a mapping relationship with each grid cell, are as follows: The three-dimensional centroid coordinates of each grid cell of the three-dimensional mesh are mapped onto the two-dimensional chessboard, and the three-dimensional centroid coordinates of each grid cell are converted into the numbers of the associated chessboard cells on the two-dimensional chessboard.

2. The mesh transformation method based on model domain decomposition according to claim 1, characterized in that, The two-dimensional chessboard has a differential grid, and the size of the two-dimensional chessboard is Nx*My. The chessboard grid with coordinates (ix, jy) is numbered as (jy-1)*Nx+ix.

3. The mesh transformation method based on model domain decomposition according to claim 2, characterized in that, The size of the two-dimensional chessboard grid does not exceed the size of the smallest grid cell in the three-dimensional grid.

4. The mesh transformation method based on model domain decomposition according to claim 1, characterized in that, The file is in .imm format.

5. The mesh transformation method based on model domain decomposition according to claim 4, characterized in that, The file includes information about the template, storage location information of the grid cells, checkerboard grid number information of the grid cells, and three-dimensional centroid coordinate information of the grid cells.

6. The mesh transformation method based on model domain decomposition according to claim 5, characterized in that, The three-dimensional mesh can be a regular mesh or an unstructured mesh.

7. A grid transformation system based on model domain decomposition, characterized in that, include: The 3D geological model acquisition module is used to acquire a 3D geological model of the target seismic exploration area; The three-dimensional mesh acquisition module is used to perform finite element mesh generation on the three-dimensional geological model to obtain a three-dimensional mesh. The two-dimensional chessboard acquisition module is used to divide the ground area of ​​the three-dimensional mesh into a chessboard to obtain a two-dimensional chessboard. The chessboard grid numbering and characterization module is used to map each grid cell of the three-dimensional mesh onto the two-dimensional chessboard, and to characterize the grid cell by using the number of the chessboard grid on the two-dimensional chessboard that has a mapping relationship with each grid cell. The grid cell sorting module is used to sort all grid cells according to the checkerboard grid number of the grid cells and store the sorted grid cells to a file; The template acquisition module is used to merge the number and storage position of the grid cells in each chessboard square into the two-dimensional chessboard to obtain a template, and to store the template in the file; The module for obtaining the finite element calculation area is used to determine the finite element calculation area in the three-dimensional mesh corresponding to each seismic exploration blasting based on the seismic exploration observation system after each seismic exploration blasting. The module for obtaining mesh elements for finite element calculation is used to obtain the number and storage location of mesh elements to be cut out based on the template according to the region to be calculated by finite element calculation, so as to obtain the mesh elements corresponding to the region to be calculated by finite element calculation from the file. The specific steps of mapping each grid cell of the three-dimensional mesh onto the two-dimensional chessboard, and representing the grid cell using the chessboard grid number that has a mapping relationship with each grid cell, are as follows: The three-dimensional centroid coordinates of each grid cell of the three-dimensional mesh are mapped onto the two-dimensional chessboard, and the three-dimensional centroid coordinates of each grid cell are converted into the numbers of the associated chessboard cells on the two-dimensional chessboard.

8. A mesh conversion device based on model domain decomposition, characterized in that, It includes a processor and a memory, wherein the processor executes a computer program stored in the memory to implement the mesh transformation method based on model domain decomposition as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, Used to store a computer program, which, when executed by a processor, implements the mesh transformation method based on model domain decomposition as described in any one of claims 1 to 6.

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