An anisotropy travel time acquisition method and device based on slowness domain and a terminal

Abstract

The application discloses a kind of anisotropy travel time acquisition method, device and terminal based on slowness domain, belong to geophysical exploration technical field.Method includes: obtaining target interval, target range and anisotropic medium parameter, based on the target interval, the target range and the anisotropic medium parameter constructs space grid model;When the travel time of target position is calculated, based on the relative position of target position and actual target seismic source point obtains target grid point in the space grid model;Obtain anisotropic eikonal equation, based on the anisotropic eikonal equation obtains target slowness domain equation;Based on the target slowness domain equation, from the target seismic source point, according to preset scanning order traverses all grid points in the space grid model, to obtain the shortest travel time of the target grid point.The application can be suitable for the travel time calculation of complex anisotropic medium, significantly reduce overall computing resource consumption, reduce parameter adjustment cost.

Description

Technical Field

[0001] This invention relates to the field of geophysical exploration technology, and in particular to a method, apparatus and terminal for obtaining anisotropic travel time based on the slow-degree domain. Background Technology

[0002] In geophysical exploration, seismic wave travel time calculation is used for static correction, tomography, and... Kirchhoff Migration (a seismic wave migration imaging technique based on Kirchhoff's integral method, also known as Kirchhoff migration or...) Kirchhoff Travel time calculations are core components of technologies such as migration and seismic location, crucial for constructing subsurface velocity models, improving data processing accuracy, and monitoring oil and gas exploration and seismic activity. However, the complexity of actual geological conditions and the widespread presence of anisotropic media pose significant challenges to travel time calculations. In anisotropic media, seismic wave propagation characteristics become complex; the propagation function depends on the phase velocity angle, and the ray path depends on the group velocity angle. qP ( quasi - Pwave Quasi-longitudinal wave), qSV ( quasi - SVwave Quasi-vertical shear wave / quasi-vertical shear wave SV Wave), qSH ( quasi - SHwave Quasi-horizontal shear wave / quasi-horizontal shear wave SH The formation of coupled surfaces by waves leads to exceptionally complex expressions for the anisotropic functional equations, increasing the computational difficulty. Therefore, the development of efficient and high-precision techniques for solving anisotropic functional equations is urgently needed.

[0003] Currently, the fast travel method in the finite difference method ( FMM , FastMarchingMethod ) and fast scanning method ( FSM , FastSweepingMethod It has a wide range of applications. However, FMM It is difficult to adapt to strong anisotropy and cannot guarantee the causality of time travel; FSM Although it can handle anisotropy, it is inefficient. FSM The mesh size and convergence count both depend on the model complexity. Complex models require fine meshes to ensure accuracy, leading to a surge in memory and computation costs, potentially exceeding hardware capabilities; conversely, using fine meshes for simple models is wasteful of resources. Furthermore, complex models require more scans to converge, which is time-consuming and the number of scans is unpredictable, while simple models converge quickly. This dependence on model complexity makes the method lack generality; when model complexity is difficult to predict, mesh and parameter selection need repeated adjustments, increasing costs.

[0004] Therefore, a stable and efficient method is urgently needed to solve the problem that the grid and convergence times depend on the model complexity in the fast scanning method.

[0005] Therefore, existing technologies still need to be improved and enhanced. Summary of the Invention

[0006] To address the aforementioned shortcomings of existing technologies, this invention provides a method, apparatus, and terminal for acquiring anisotropic travel time based on the slow-degree domain. The aim is to solve the problem that existing fast scanning methods rely on model complexity for grid and convergence counts, making it impossible to quickly and efficiently calculate the travel time of complex anisotropic media.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A first aspect of the present invention provides a method for obtaining anisotropic travel time based on a slow-degree domain, the method comprising:

[0009] The target spacing, target range, and anisotropic medium parameters are obtained. A spatial grid model is constructed based on the target spacing, target range, and anisotropic medium parameters. The spatial grid model includes target seismic source points, and the travel time of the target seismic source points is a target value. The target spacing is the grid spacing of the spatial grid model; the target range is the total size of the spatial grid model; and the anisotropic medium parameters are used to assign geological conditions to the spatial grid model.

[0010] When calculating the travel time of the target location, the target grid point in the spatial grid model is obtained based on the relative position of the target location and the actual target seismic source point;

[0011] Obtain the anisotropic equation, and obtain the target slowness domain equation based on the anisotropic equation.

[0012] Based on the target slowness domain equation, starting from the target seismic source point, all grid points in the spatial grid model are traversed according to a preset scanning order to obtain the shortest travel time of the target grid point.

[0013] In one implementation, constructing the spatial grid model includes:

[0014] Obtain the length and depth range of the target geological body, and obtain the spatial boundary of the spatial grid model based on the length and depth range of the target geological body to obtain the target range;

[0015] The resolution requirements and numerical stability conditions of the target geological body are obtained, and the target spacing is obtained based on the resolution requirements and numerical stability conditions of the target geological body.

[0016] In one implementation, the anisotropic equation includes a first anisotropic equation and a second anisotropic equation, wherein the first anisotropic equation is: qP wave and qSV The anisotropic equation of the wave, the second anisotropic equation is: qSH The anisotropic equation of a wave;

[0017] The first anisotropic equation is:

[0018] ;

[0019] ;

[0020] ;

[0021] ;

[0022] ;

[0023] ;

[0024] The second anisotropic equation is:

[0025] ;

[0026] in, , These represent the horizontal and vertical travel gradient components, respectively. and They are respectively in the axially symmetric direction P wave and S wave speed, , and All parameters are from Thomson.

[0027] In one implementation, obtaining the target slowness domain equation based on the anisotropic equation includes:

[0028] Obtain the target relation, which includes a first relation and a second relation, and the target relation represents the relationship between travel time gradient and slowness.

[0029] The first anisotropic equation is decomposed to obtain the first sub-equation and the second sub-equation.

[0030] Substituting the first relation into the first sub-equation, we obtain the first target slowness domain equation;

[0031] Substituting the second relation into the second sub-equation, we obtain the second objective slowness domain equation;

[0032] Substituting the first and second relations into the second anisotropic equation, a third target slowness domain equation is obtained, which is composed of the first target slowness domain equation, the second target slowness domain equation, and the third target slowness domain equation.

[0033] In one implementation, the first relation is:

[0034]

[0035] ;

[0036] The second relation is:

[0037]

[0038] ;

[0039] in, d The distance between the target grid point and the target seismic source point. S The slowness of the target grid point. h The grid spacing is... , These represent the gradient components in the horizontal and vertical directions, respectively. i , j These represent the horizontal and vertical grid values ​​of the target grid point, respectively. For grid points ( i -1, j The slowness of ) For grid points ( i +1, j The slowness of ) For grid points ( i , j The slowness of ) For grid points ( i , j -1) slowness, For grid points ( i , j +1) slowness, d and All of these are the distances between the target grid points and the target seismic source points. , These represent the distance components in the horizontal and vertical directions, respectively. express d right x Find the partial derivative. express d right z Find the partial derivatives.

[0040] In one implementation, the first objective slowness domain equation is:

[0041] ;

[0042] The second objective slowness domain equation is:

[0043] ;

[0044] in, ; ;

[0045] The equation for the third objective slowness domain is:

[0046] .

[0047] In one implementation, the step of traversing all grid points in the spatial grid model according to a preset scanning order, starting from the target seismic source point based on the target slowness domain equation, to obtain the shortest travel time of the target grid point includes:

[0048] An initial travel time is preset for all grid points except the target seismic source point, and the initial travel time is greater than the quotient of the maximum distance and the minimum wave velocity in the spatial grid model;

[0049] Starting from the target seismic source point based on the preset scanning order, a local travel time solution is calculated based on the travel time of adjacent solved points. If the local travel time solution is greater than the current travel time solution, the current travel time solution is replaced based on the local travel time solution.

[0050] Repeat the steps of starting from the target seismic source point based on the preset scanning order and calculating the local travel time solution based on the travel time of adjacent solved points until the target convergence condition is met, and output the shortest travel time of the target grid point.

[0051] In one implementation, after the target convergence condition is met, the method further includes:

[0052] The travel time of each grid point in the spatial grid model is verified based on the anisotropic medium parameters. If a negative value appears or the wavefront propagation direction is inconsistent with the anisotropic law corresponding to the anisotropic medium parameters, the output result is judged to be unreasonable.

[0053] If no negative value appears and the wavefront propagation direction is consistent with the anisotropic law corresponding to the anisotropic medium parameters, then the travel time grid data in the spatial grid model is output.

[0054] A second aspect of the present invention provides an anisotropic time-travel acquisition device based on the slow-range domain, comprising:

[0055] A mesh construction module is used to acquire target spacing, target range, and anisotropic medium parameters, and to construct a spatial mesh model based on the target spacing, target range, and anisotropic medium parameters. The spatial mesh model includes target seismic source points, and the travel time of the target seismic source points is a target value. The target spacing is the mesh spacing of the spatial mesh model; the target range is the total size of the spatial mesh model; and the anisotropic medium parameters are used to assign simulated geological conditions to the spatial mesh model.

[0056] The grid point acquisition module is used to acquire target grid points in the spatial grid model based on the relative positions of the target location and the actual target seismic source point when calculating the travel time of the target location.

[0057] The slow-degree domain equation acquisition module is used to acquire anisotropic equations and acquire target slow-degree domain equations based on the anisotropic equations.

[0058] The scanning module is used to start from the target seismic source point based on the target slowness domain equation and traverse all grid points in the spatial grid model according to a preset scanning order to obtain the shortest travel time of the target grid point.

[0059] A third aspect of the present invention provides a terminal, the terminal including a processor and a computer-readable storage medium communicatively connected to the processor, the computer-readable storage medium being adapted to store a plurality of instructions, the processor being adapted to invoke the instructions in the computer-readable storage medium to perform the steps of implementing the anisotropic time-travel acquisition method based on the slow-degree domain as described in any of the preceding claims.

[0060] Compared with existing technologies, this invention provides an anisotropic travel time acquisition method based on the slow-degree domain. This method involves acquiring target spacing, target range, and anisotropic medium parameters. A spatial grid model is constructed based on these parameters. The spatial grid model includes a target hypocenter, and the travel time of the target hypocenter is a target value. The target spacing is the grid spacing of the spatial grid model; the target range is the total size of the spatial grid model; and the anisotropic medium parameters are used to simulate geological conditions in the spatial grid model. When calculating the travel time of the target location, target grid points in the spatial grid model are obtained based on the relative positions of the target location and the actual target hypocenter. Then, the anisotropic equation is obtained, and the target slow-degree domain equation is obtained based on the anisotropic equation. Finally, based on the target slow-degree domain equation, all grid points in the spatial grid model are traversed from the target hypocenter according to a preset scanning order to obtain the shortest travel time of the target grid point. The proposed solution addresses the problem in existing fast scanning methods where the mesh size and convergence count depend on model complexity, making it difficult to quickly and efficiently calculate travel times in complex anisotropic media. This solution eliminates the need for significantly denser meshes due to model complexity when calculating seismic wave travel times, reducing hardware requirements for mesh size. It is suitable for travel time calculations in complex anisotropic media, ensuring imaging accuracy in key areas under complex geological structures while significantly reducing overall computational resource consumption, lowering parameter adjustment costs, and improving versatility and computational efficiency. Attached Figure Description

[0061] Figure 1 A flowchart illustrating an embodiment of the anisotropic time travel acquisition method based on the slow domain provided by the present invention;

[0062] Figure 2 A local triangular network diagram of an embodiment of the anisotropic time travel acquisition method based on the slow-degree domain provided by the present invention;

[0063] Figure 3 This is an embodiment of the anisotropic time travel acquisition method based on the slow domain provided by the present invention. BP Model parameters Figure 1 ;

[0064] Figure 4 This is an embodiment of the anisotropic time travel acquisition method based on the slow domain provided by the present invention. BP Model parameters Figure 2 ;

[0065] Figure 5 This is an embodiment of the anisotropic time-travel acquisition method based on the slow-degree domain provided by the present invention. BP Model parameters Figure 3 ;

[0066] Figure 6 A slow-degree domain distribution diagram for an embodiment of the anisotropic time travel acquisition method based on the slow-degree domain provided by the present invention;

[0067] Figure 7 Comparison of embodiments of the anisotropic time-travel acquisition method based on the slow-degree domain provided by the present invention Figure 1 ;

[0068] Figure 8 Comparison of embodiments of the anisotropic time-travel acquisition method based on the slow-degree domain provided by the present invention Figure 2 ;

[0069] Figure 9 A comparison of traditional methods with embodiments of the anisotropic time-travel acquisition method based on the slow-degree domain provided by the present invention. Figure 1 ;

[0070] Figure 10 A comparison of traditional methods with embodiments of the anisotropic time-travel acquisition method based on the slow-degree domain provided by the present invention. Figure 2 ;

[0071] Figure 11 A schematic diagram illustrating the structural principle of an embodiment of the anisotropic time-travel acquisition device based on the slow-degree domain provided by the present invention.

[0072] Figure 12 A schematic diagram illustrating the principle of an embodiment of the terminal provided by the present invention. Detailed Implementation

[0073] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0074] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connections or wireless coupling. The term “and / or” as used herein includes all or any units and all combinations of one or more associated listed items.

[0075] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0076] The anisotropic travel time acquisition method based on the slow domain provided by this invention can be applied to terminals with computing capabilities. The terminal can execute the anisotropic travel time acquisition method based on the slow domain provided by this invention to solve the travel time of seismic waves.

[0077] Example 1

[0078] This embodiment describes an anisotropic travel time acquisition method based on the slow-degree domain. In geophysical exploration, seismic wave travel time calculation is used for static correction, tomography, and... Kirchhoff Migration imaging and seismic location are key technologies crucial for accurately constructing subsurface velocity models, improving the accuracy of seismic data processing, and effectively conducting oil and gas resource exploration and seismic activity monitoring. However, the complex and variable geological conditions and the widespread distribution of anisotropic media pose significant challenges to seismic wave travel time calculations. In anisotropic media, the propagation characteristics of seismic waves change significantly; the propagation function equation depends on the phase velocity direction, while the ray path is determined by the group velocity direction. Furthermore, anisotropic conditions can lead to… qP Wave, qSV wave and qSH The presence of various wave types, such as waves, with their wavefronts coupling with each other, results in an extremely complex form of the travel time equation, significantly increasing the difficulty of numerical solutions. Therefore, developing efficient and high-precision methods for solving anisotropic travel time equations has become an urgent need to overcome current technological bottlenecks and improve the accuracy and efficiency of travel time calculations.

[0079] Currently, the finite difference method is the mainstream method for solving equations, among which the fast travel method ( FMM ) and fast scanning method ( FSM (This is the most widely used method.) FMM Based on the "wavefront advancement" mechanism, this method manages the state of grid points (accepted, under consideration, unprocessed) through stack sorting, always selecting the node with the smallest current travel time for expansion, strictly adhering to the causal principle, and avoiding repeated traversal of the entire grid. This method exhibits good stability in strongly inhomogeneous media, is suitable for small-scale, high-precision modeling, and possesses local early convergence characteristics; however, its time complexity is O(n log n). O ( MlogM ), MFor the number of grid points, efficiency is lower than [a certain value] on simple models. FSM Furthermore, it is difficult to satisfy the true time-travel causal constraints in strongly anisotropic media. FSM A multi-directional alternating scanning strategy is employed, decomposing the propagation direction into several groups. The Gauss-Seidel iterative method is used to solve the headwind differential discretization scheme, updating the entire travel time in a fixed order each time, repeating this process multiple times until convergence. This method exhibits near-perfect performance in homogeneous or segmented constant-velocity media. O ( M It has a linear complexity, is easy to implement and efficient; however, in strongly anisotropic or complex velocity structures, the number of scans increases dramatically due to frequent changes in the direction of the feature lines, resulting in a significant decrease in efficiency. At the same time, its performance is highly dependent on the mesh orientation.

[0080] It is evident that existing technologies have significant limitations: FMM Due to the inconsistency between the phase velocity and group velocity directions, the physical correctness of traveltime updates cannot be guaranteed in anisotropic media, and it is only applicable to weakly anisotropic or simplified models; while FSM While it can adapt well to anisotropic environments, its overall efficiency is relatively low. More importantly, FSM The performance of this method is highly dependent on model complexity. Complex media require high-density meshes to ensure accuracy, leading to a dramatic increase in computational scale, memory consumption, and computation time, especially in large-scale 3D problems where it can easily exceed hardware capacity. Conversely, using overly dense meshes for simple models results in wasted resources. Furthermore, complex models, due to their variable wavefront morphology, often require more scans to converge, resulting in longer processing times and unpredictable convergence behavior, while simpler models converge faster. This high sensitivity to model complexity makes the method lack universality. In practical applications, users often cannot determine the optimal mesh resolution and iteration parameters in advance, requiring repeated trial and error adjustments, significantly increasing manpower and computational costs.

[0081] Therefore, in this embodiment, an anisotropic travel time acquisition method based on the slow-degree domain is provided. This method is an efficient and high-precision anisotropic equation decomposition technique in the slow-degree domain. By representing travel time as the product of slowness and propagation distance, it realizes the mathematical transformation from the traditional travel time domain to the slow-degree domain, thereby effectively alleviating the limitations of fast scanning methods. FSMThis addresses the issue of the high dependence of grid resolution and iteration convergence number on model complexity in seismic wave travel time acquisition. Within the slow-degree domain framework, the changes in physical parameters caused by medium anisotropy are smoother, and the spatial gradient is significantly reduced. Therefore, it eliminates the need for excessively dense computational grids for complex geological structures, thus drastically reducing grid size and the associated memory and computational resource consumption. Simultaneously, the characteristic curves in the slow-degree domain exhibit stronger regularity and predictability, making the algorithm's convergence behavior more stable, and significantly reducing the impact of model complexity on the number of iterations required for convergence. This characteristic allows users to pre-define robust scanning iteration strategies based on typical working conditions, reducing the need for frequent parameter adjustments due to model differences, lowering the barrier to entry, and improving the method's versatility. The slow-degree domain-based anisotropic travel time acquisition method provided in this embodiment significantly improves computational efficiency while maintaining high accuracy, making it particularly suitable for seismic wave travel time simulation tasks in complex medium environments with strong anisotropy and high non-homogeneity.

[0082] like Figure 1 As shown, in one embodiment of the anisotropic time travel acquisition method based on the slow-degree domain provided by the present invention, the anisotropic time travel acquisition based on the slow-degree domain includes the following steps:

[0083] S 100. Obtain the target spacing, target range, and anisotropic medium parameters. Construct a spatial grid model based on the target spacing, target range, and anisotropic medium parameters. The spatial grid model includes target seismic source points, and the travel time of the target seismic source points is a target value. The target spacing is the grid spacing of the spatial grid model; the target range is the total size of the spatial grid model; and the anisotropic medium parameters are used to assign geological conditions to the spatial grid model.

[0084] The construction of the spatial grid model includes:

[0085] Obtain the length and depth range of the target geological body, and obtain the spatial boundary of the spatial grid model based on the length and depth range of the target geological body to obtain the target range;

[0086] The resolution requirements and numerical stability conditions of the target geological body are obtained, and the target spacing is obtained based on the resolution requirements and numerical stability conditions of the target geological body.

[0087] Specifically, this embodiment provides a numerical simulation workflow for calculating seismic wave travel times, aiming to efficiently and accurately solve the travel time field in complex anisotropic media. The core idea is to simplify the equations and improve computational stability and efficiency by transforming the traditional travel time domain problem into a slow-degree domain problem. The entire workflow consists of three main stages: preprocessing, core calculation, and post-processing.

[0088] In the preprocessing stage, parameters reflecting the physical properties of the rock are first input, such as P-wave velocity, S-wave velocity, and parameters describing the anisotropy of the medium. Thomsen The parameters are set, and the spatial range of the simulation is defined. Specifically, the anisotropic medium parameters include the longitudinal wave velocity. transverse wave velocity , Thomsen parameter , and These parameters describe the differences in physical properties of the subsurface medium in different directions, such as velocity and density, and are crucial for accurately simulating the propagation characteristics of seismic waves.

[0089] When constructing the spatial grid model, the target range is determined based on the length and depth range of the actual medium, and then the grid cells are set according to the resolution requirements and numerical stability conditions of the target geological body. x and z The step size in the direction ensures that geological details are captured while avoiding numerical oscillations. Based on the above parameters, the following calculations are performed. x and z The number of nodes in each direction is determined to construct a structured grid model. This model not only includes a core computational region reflecting the main geological features but also incorporates a boundary layer to enhance the stability of boundary condition handling. Finally, precise spatial coordinates are assigned to each grid node, forming a complete discretized geometric framework. In other words, based on the required resolution and numerical stability requirements, the study area is divided into a structured grid, with each grid point assigned corresponding coordinates, resulting in a complete and usable structured grid model.

[0090] In this embodiment, each grid point has a defined coordinate location and is marked according to its relative position to the target hypocenter. The target hypocenter, as the starting point of the seismic waves, holds a special position in the spatial grid model, and its travel time is set to the target value, which is typically 0, conforming to the physical definition of a time starting point. With this setup, in this embodiment, the time it takes for seismic waves to reach other grid points can be calculated by starting from the hypocenter and gradually expanding outwards.

[0091] S 200. When calculating the travel time of the target location, the target grid point in the spatial grid model is obtained based on the relative position of the target location and the actual target seismic source point.

[0092] Specifically, when it is necessary to calculate the travel time of a specific target location, the corresponding target grid point must first be accurately located in the spatial grid model based on the relative positional relationship between the target location and the actual seismic source point.

[0093] S 300. Obtain the anisotropic equation, and obtain the target slowness domain equation based on the anisotropic equation.

[0094] Specifically, the anisotropic equation includes a first anisotropic equation and a second anisotropic equation, wherein the first anisotropic equation is: qP wave and qSV The anisotropic equation of the wave, the second anisotropic equation is: qSH The anisotropic equation of a wave;

[0095] In anisotropic media, qP wave and qSV The quartic equation of an anisotropic medium coupled with waves, which is also the first anisotropic equation, is as follows:

[0096] ;

[0097] ;

[0098] ;

[0099] ;

[0100] ;

[0101] ;

[0102] in, , These represent the horizontal and vertical travel gradient components, respectively. and They are respectively in the axially symmetric direction P wave and S wave speed, , and All parameters are from Thomson.

[0103] and qSH The anisotropic equation of the wave, also known as the second anisotropic equation, is as follows:

[0104] .

[0105] Based on this, the velocity model is transformed into a slowness model (i.e., the reciprocal of the velocity is taken), and a new type of functional equation applicable to the slowness domain is established. This is a key step to achieve efficient subsequent calculations.

[0106] Specifically, obtaining the target slowness domain equation based on the anisotropic equation includes:

[0107] S 210. Obtain the target relation, which includes a first relation and a second relation, and the target relation represents the relationship between travel time gradient and slowness.

[0108] S 220. Decompose the first anisotropic equation into a first sub-equation and a second sub-equation;

[0109] S 230. Substitute the first relation into the first sub-equation to obtain the first target slowness domain equation;

[0110] S 240. Substitute the second relation into the second sub-equation to obtain the second objective slowness domain equation;

[0111] S 25. Substitute the first relation and the second relation into the second anisotropic equation to obtain the third target slowness domain equation, which is composed of the first target slowness domain equation, the second target slowness domain equation and the third target slowness domain equation.

[0112] Specifically, travel time is decomposed into the product of slowness and distance, and the travel time is updated point by point using the wavefront spread algorithm.

[0113] That is, the relationship between running time and slowness is:

[0114] ;

[0115] in, S It is an equivalent parameter, referred to as slowness in this embodiment. T For the time of departure, d The distance between the target grid point and the target seismic source point. , The coordinates of the target grid point are... and The x and y coordinates of the target seismic source point are represented respectively, and the slowness is... S The physical meaning is: to equate the curved propagation path to a straight-line distance. d The required "average slowness" (which includes the combined effects of path curvature and medium heterogeneity) is then determined.

[0116] Based on this, by deriving the travel time gradient and slowness using mathematical formulas, the target relation can be obtained. The target relation includes a first relation and a second relation, and the target relation represents the relationship between the travel time gradient and slowness.

[0117] The first relation is:

[0118]

[0119] ;

[0120] The second relation is:

[0121]

[0122] ;

[0123] in, d The distance between the target grid point and the target seismic source point. S The slowness of the target grid point. h The grid spacing is... , These represent the gradient components in the horizontal and vertical directions, respectively. i , j These represent the horizontal and vertical grid values ​​of the target grid point, respectively. For grid points ( i -1, j The slowness of ) For grid points ( i +1, j The slowness of ) For grid points ( i , j The slowness of ) For grid points ( i , j -1) slowness, For grid points ( i , j +1) slowness, d and All of these are the distances between the target grid points and the target seismic source points. , These represent the distance components in the horizontal and vertical directions, respectively. express d right x Find the partial derivative. express d right z Find the partial derivatives.

[0124] Furthermore, d for x and z The derivative of the direction, i.e. , It can be solved analytically; that is, the distance component formula is:

[0125] ;

[0126] in, and The x-coordinate and y-coordinate of the target seismic source point are respectively represented.

[0127] Furthermore, the travel gradient and travel time can be derived from the local space grid. , The formula for the travel time gradient components can be obtained as follows:

[0128] ;

[0129] Among them, reference Figure 2 , Figure 2 Includes A point, B and C point, , and They represent A point, B Dot and C The time of the point, , and They represent A point, B Dot and C The x-coordinate of the point, , and They represent A point, B Dot and C The ordinate value of the point.

[0130] Furthermore, for Figure 2 In Unit 1, the derivation result of the relationship between travel time gradient and slowness is shown in the first formula:

[0131] ;

[0132] for Figure 2 In Unit 2, the derivation result of the relationship between travel time gradient and slowness is shown in the second formula:

[0133] ;

[0134] For the target grid point ( i , j The unknown variables obtained by the first and second formulas are... For example, taking the first formula as an example, where... It is known, and This includes the unknown variable, slowness. This way When deduced as a whole from mathematical relations, the first anisotropic equation can be decomposed into two sub-equations: the first sub-equation and the second sub-equation.

[0135] The first sub-equation is:

[0136] ;

[0137] The second sub-equation is:

[0138] ;

[0139] in: ;

[0140] .

[0141] Then, the target slowness domain equation can be obtained. Specifically, the target slowness domain equation includes a first target slowness domain equation, a second target slowness domain equation, and a third target slowness domain equation.

[0142] Specifically, substituting the first relation into the first sub-equation yields the first target slowness domain equation; substituting the second relation into the second sub-equation yields the second target slowness domain equation.

[0143] ;

[0144] ;

[0145] ;

[0146] ;

[0147] The solution approach is similar for Unit 2, except that the unknown variable here is... The only change is in the form of the equation.

[0148] And for qSH By directly substituting the first and second relations into the second anisotropic equation, the third target slowness domain equation can be obtained. The target slowness domain equation is composed of the first target slowness domain equation, the second target slowness domain equation, and the third target slowness domain equation.

[0149] .

[0150] In fast scanning method FSM In this context, the target slow-degree domain equation demonstrates significant advantages. For example, referring to... Figure 3 , Figure 4 and Figure 5 ,in, Figure 3 This demonstrates the velocity distribution with depth and distance in anisotropic media. Figure 4 This demonstrates the different characteristics in anisotropic media. The distribution of parameters with depth and distance, Figure 5 Demonstrates the properties of anisotropic media The distribution of parameters with depth and distance. For Figure 3 , Figure 4 and Figure 5 This complex anisotropic model can make the slow-degree domain distribution smoother, as detailed in the following reference. Figure 6 This avoids the computational instability and inaccurate imaging caused by abrupt changes in the original slow velocity. Furthermore, it can mitigate source errors and reduce their interference with imaging; simultaneously, it allows for increased grid spacing, significantly reducing computational load and improving efficiency. See [link to documentation] for details. Figure 7 and Figure 8 .and Figure 9 and Figure 10 That is tradition FSM Comparison with reference solution time isochrones and traditional FSM The error distribution of the reference solution shows that the slow-degree domain method has significantly improved efficiency compared to traditional methods, and the error is smaller than that of traditional methods, ultimately achieving efficient and high-precision seismic imaging.

[0151] Refer again Figure 1 After obtaining the target slowness domain equation, the following steps are also included:

[0152] S 400. Based on the target slowness domain equation, starting from the target seismic source point, traverse all grid points in the spatial grid model according to a preset scanning order to obtain the shortest travel time of the target grid point.

[0153] The step of traversing all grid points in the spatial grid model according to a preset scanning order, starting from the target seismic source point based on the target slowness domain equation, to obtain the shortest travel time of the target grid point includes:

[0154] An initial travel time is preset for all grid points except the target seismic source point, and the initial travel time is greater than the quotient of the maximum distance and the minimum wave velocity in the spatial grid model;

[0155] Starting from the target seismic source point based on the preset scanning order, a local travel time solution is calculated based on the travel time of adjacent solved points. If the local travel time solution is greater than the current travel time solution, the current travel time solution is replaced based on the local travel time solution.

[0156] Repeat the steps of starting from the target seismic source point based on the preset scanning order and calculating the local travel time solution based on the travel time of adjacent solved points until the target convergence condition is met, and output the shortest travel time of the target grid point.

[0157] Specifically, after obtaining the target slow-degree domain equation, based on the target slow-degree domain equation, starting from the target seismic source point, all grid points in the spatial grid model are traversed in a preset scanning order. This scanning order is usually pre-designed to efficiently explore the entire space and ensure that each grid point is properly processed.

[0158] Specifically, in this embodiment, only the travel time of the source point is set to zero, while all other grid points are assigned a relatively large initial travel time. This initial travel time is greater than the quotient of the maximum distance and minimum wave velocity in the spatial grid model, and can be 1.5 times the quotient of the maximum distance and minimum wave velocity in the spatial grid model, signifying that it has not yet been updated. Next, following the preset scanning order, i.e., the four preset directions (from left to right, from top to bottom, from right to left, and from bottom to top), the entire grid is traversed sequentially. Using the information of the updated neighbors and combining it with the target slowness domain equation, the minimum possible travel time of the current point is iteratively calculated. Based on Fermat's principle, each update follows the "minimum value first" principle to ensure that the result conforms to the physical causality law. Fermat's principle, also known as Fermat's minimum time principle, was proposed by the French mathematician and physicist Pierre de Fermat. This principle states that when light travels between two points, it always chooses the path with the shortest travel time. This principle is not only applicable to optics but also has important applications in seismology, namely, the travel time of seismic waves propagating along rays is minimized compared to the travel time along other paths.

[0159] The process involves multiple iterations of scanning until the target convergence condition is met. Specifically, in this embodiment, a target threshold is set. If the change between two adjacent iterations is less than the set target threshold, the travel time field is considered to have converged, thus obtaining the complete wavefront propagation time distribution. The target threshold is set based on the complexity and error range requirements of the spatial grid model.

[0160] Ultimately, through this series of calculation steps, the travel time of the target grid points can be obtained, providing important basic data for further seismic data processing and interpretation.

[0161] By repeatedly scanning in cycles until the change between two adjacent iterations is less than a set threshold, the travel time field is considered to have converged, thus obtaining the complete wavefront propagation time distribution.

[0162] After the target convergence condition is met, the following is also included:

[0163] The travel time of each grid point in the spatial grid model is verified based on the anisotropic medium parameters. If a negative value appears or the wavefront propagation direction is inconsistent with the anisotropic law corresponding to the anisotropic medium parameters, the output result is judged to be unreasonable.

[0164] If no negative value appears and the wavefront propagation direction is consistent with the anisotropic law corresponding to the anisotropic medium parameters, then the travel time grid data in the spatial grid model is output.

[0165] Specifically, this embodiment also includes a post-processing stage, in which the calculated travel time field is checked for reasonableness, such as checking for negative values ​​or phenomena that do not conform to the anisotropy law. After confirming that there are no errors, structured travel time data is output for subsequent applications such as seismic imaging, resource exploration, or geological structure inversion.

[0166] As can be seen, in this embodiment, slow-degree domain modeling makes the originally complex anisotropic problem smoother and more controllable, reduces the dependence on high-density grids, and lowers hardware requirements; at the same time, the direction of the feature path is more regular, which improves the convergence and robustness of the algorithm, making it particularly suitable for real underground environments with high non-uniformity and strong anisotropy.

[0167] In this embodiment, to address the limitations of traditional uniform grids in seismic wave travel time calculation, an anisotropic travel time acquisition method based on the slowness domain is proposed. This method is based on adaptive adjustment of the slowness gradient and dynamic grid optimization. By analyzing the spatial variation characteristics of the slowness field in the medium, it identifies key regions causing abrupt changes in slowness, such as faults and lithological interfaces. A localized mesh refinement strategy is implemented in these high-gradient regions to accurately capture subtle differences in the integral term of "slowness multiplied by distance." In regions with gentle slowness distribution, a sparse grid is used to avoid unnecessary computational overhead. This anisotropic travel time acquisition method based on the slowness domain, combined with the reconstruction of the anisotropic equation within the slowness domain, can simultaneously and efficiently solve the problem. qP Wave, qSV wave and qSH Wave travel time field, while ensuring imaging accuracy in key areas under complex geological structures, significantly reduces overall computational resource consumption and improves the processing efficiency of large-scale 3D models.

[0168] In summary, this embodiment provides an anisotropic travel time acquisition method based on the slow-degree domain. It acquires target spacing, target range, and anisotropic medium parameters, and constructs a spatial grid model based on these parameters. The spatial grid model includes a target hypocenter, and the travel time of the target hypocenter is a target value. The target spacing is the grid spacing of the spatial grid model; the target range is the total size of the spatial grid model; and the anisotropic medium parameters are used to simulate geological conditions in the spatial grid model. When calculating the travel time of the target location, the target grid points in the spatial grid model are obtained based on the relative positions of the target location and the actual target hypocenter. Then, the anisotropic equation is obtained, and the target slow-degree domain equation is obtained based on the anisotropic equation. Finally, based on the target slow-degree domain equation, starting from the target hypocenter, all grid points in the spatial grid model are traversed according to a preset scanning order to obtain the shortest travel time of the target grid point. The proposed solution in this embodiment solves the problem that the mesh and convergence times in the existing fast scanning method depend on the model complexity, making it impossible to quickly and efficiently calculate the travel time of complex anisotropic media. This eliminates the need to significantly refine the mesh due to model complexity when calculating seismic wave travel time, reducing the hardware requirements for mesh size. It is suitable for travel time calculation in complex anisotropic media, ensuring imaging accuracy in key areas under complex geological structures while significantly reducing overall computational resource consumption, reducing parameter adjustment costs, and improving versatility and computational efficiency.

[0169] It should be understood that although the steps in the flowcharts shown in the accompanying drawings are displayed sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowchart may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least a portion of the sub-steps or stages of other steps.

[0170] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided by this invention can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM). ROM Programmable ROM ( PROM ), electrically programmable ROM ( EPROM Electrically erasable programmable ROM ( EEPROM ) or flash memory. Volatile memory may include random access memory (RAM) RAM Alternatively, an external cache memory. This is for illustrative purposes only and not as a limitation. RAM It can be obtained in various forms, such as static RAM ( SRAM ),dynamic RAM ( DRAM ),synchronous DRAM ( SDRAM ), double data rate SDRAM ( DDR SDRAM ), Enhanced SDRAM ( ESDRAM ), Synchronization Link ( Synchlink ), DRAM ( SLDRAM ), memory bus ( Rambus )direct RAM ( RDRAM ), Direct Memory Bus Dynamics RAM ( DRDRAM ), and memory bus dynamics RAM ( RDRAM )wait.

[0171] Example 2

[0172] Based on the above embodiments, the present invention also provides an anisotropic time-travel acquisition device based on the slow-degree domain, such as... Figure 11 As shown, the anisotropic time travel acquisition device based on the slow domain includes:

[0173] A mesh construction module is used to acquire target spacing, target range, and anisotropic medium parameters, and to construct a spatial mesh model based on the target spacing, target range, and anisotropic medium parameters. The spatial mesh model includes target seismic source points, and the travel time of the target seismic source points is a target value. The target spacing is the mesh spacing of the spatial mesh model; the target range is the total size of the spatial mesh model; the anisotropic medium parameters are used to assign geological conditions to the spatial mesh model, as described in Embodiment 1.

[0174] The grid point acquisition module is used to acquire target grid points in the spatial grid model based on the relative position of the target location and the actual target seismic source point when calculating the travel time of the target location, as specifically described in Embodiment 1;

[0175] The slow-degree domain equation acquisition module is used to acquire the anisotropic equation and acquire the target slow-degree domain equation based on the anisotropic equation, as described in Embodiment 1.

[0176] The scanning module is used to start from the target seismic source point based on the target slowness domain equation and traverse all grid points in the spatial grid model according to a preset scanning order to obtain the shortest travel time of the target grid point, as specifically described in Embodiment 1.

[0177] Example 3

[0178] Based on the above embodiments, the present invention also provides a terminal, such as... Figure 12 As shown, the terminal includes a processor 10 and a memory 20. Figure 12 Only some of the terminal components are shown; however, it should be understood that it is not required to implement all of the components shown, and more or fewer components may be implemented instead.

[0179] In some embodiments, the memory 20 may be an internal storage unit of the terminal, such as the terminal's hard drive or memory. In other embodiments, the memory 20 may also be an external storage device of the terminal, such as a plug-in hard drive or smart memory card equipped on the terminal. SmartMediaCard , SMC ), Secure Digital ( SecureDigital , SD ) card, flash memory card ( FlashCardFurthermore, the memory 20 may include both internal storage units and external storage devices of the terminal. The memory 20 is used to store application software and various types of data installed on the terminal. The memory 20 can also be used to temporarily store data that has been output or will be output. In one embodiment, the memory 20 stores an anisotropic timekeeping acquisition program 30 based on the slow domain, which can be executed by the processor 10 to implement the anisotropic timekeeping acquisition method based on the slow domain in this application.

[0180] In some embodiments, the processor 10 may be a central processing unit (CPU). Central Processing Unit , CPU (a microprocessor or other chip) is used to run the program code stored in the memory 20 or process data, such as executing the anisotropic time-travel acquisition method based on the slow domain.

[0181] In one embodiment, when the processor 10 executes the anisotropic time-travel acquisition program 30 based on the slow domain in the memory 20, the following steps are performed:

[0182] The target spacing, target range, and anisotropic medium parameters are obtained. A spatial grid model is constructed based on the target spacing, target range, and anisotropic medium parameters. The spatial grid model includes target seismic source points, and the travel time of the target seismic source points is a target value. The target spacing is the grid spacing of the spatial grid model; the target range is the total size of the spatial grid model; and the anisotropic medium parameters are used to assign geological conditions to the spatial grid model.

[0183] When calculating the travel time of the target location, the target grid point in the spatial grid model is obtained based on the relative position of the target location and the actual target seismic source point;

[0184] Obtain the anisotropic equation, and obtain the target slowness domain equation based on the anisotropic equation.

[0185] Based on the target slowness domain equation, starting from the target seismic source point, all grid points in the spatial grid model are traversed according to a preset scanning order to obtain the shortest travel time of the target grid point.

[0186] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for obtaining anisotropic travel time based on the slow-degree domain, characterized in that, The anisotropic time travel acquisition method based on the slow domain includes: The target spacing, target range, and anisotropic medium parameters are obtained. A spatial grid model is constructed based on the target spacing, target range, and anisotropic medium parameters. The spatial grid model includes target seismic source points, and the travel time of the target seismic source points is a target value. The target spacing is the grid spacing of the spatial grid model; the target range is the total size of the spatial grid model; and the anisotropic medium parameters are used to assign geological conditions to the spatial grid model. When calculating the travel time of the target location, the target grid point in the spatial grid model is obtained based on the relative position of the target location and the actual target seismic source point; Obtain the anisotropic equation, and obtain the target slowness domain equation based on the anisotropic equation. Based on the target slowness domain equation, starting from the target seismic source point, all grid points in the spatial grid model are traversed in a preset scanning order to obtain the shortest travel time of the target grid point; The anisotropic equations include a first anisotropic equation and a second anisotropic equation, wherein the first anisotropic equation is: qP wave and qSV The anisotropic equation of the wave, the second anisotropic equation is: qSH The anisotropic equation of a wave; The first anisotropic equation is: ； ； ； ； ； ； The second anisotropic equation is: ； in, , These represent the horizontal and vertical travel gradient components, respectively. and They are respectively in the axially symmetric direction P wave and S wave speed, , and All parameters are Thomson parameters; The target slowness domain equation is obtained based on the anisotropic equation, including: Obtain the target relation, which includes a first relation and a second relation, and the target relation represents the relationship between travel time gradient and slowness. The first anisotropic equation is decomposed to obtain the first sub-equation and the second sub-equation. Substituting the first relation into the first sub-equation, we obtain the first target slowness domain equation; Substituting the second relation into the second sub-equation, we obtain the second objective slowness domain equation; Substituting the first and second relations into the second anisotropic equation, a third target slowness domain equation is obtained, which is composed of the first target slowness domain equation, the second target slowness domain equation, and the third target slowness domain equation. The first relation is: ； The second relation is: ； in, d The distance between the target grid point and the target seismic source point. S The slowness of the target grid point. h The grid spacing is... , These represent the gradient components in the horizontal and vertical directions, respectively. i , j These represent the horizontal and vertical grid values ​​of the target grid point, respectively. For grid points ( i -1, j The slowness of ) For grid points ( i +1, j The slowness of ) For grid points ( i , j The slowness of ) For grid points ( i , j -1) slowness, For grid points ( i , j +1) slowness, d and All of these are the distances between the target grid points and the target seismic source points. , These represent the distance components in the horizontal and vertical directions, respectively. express d right x Find the partial derivative. express d right z Find the partial derivatives; The equation for the first target slowness domain is: ； The second objective slowness domain equation is: ； in, ; ; The equation for the third objective slowness domain is: 。 2. The anisotropic travel time acquisition method based on the slow-degree domain according to claim 1, characterized in that, The construction of the spatial grid model includes: Obtain the length and depth range of the target geological body, and obtain the spatial boundary of the spatial grid model based on the length and depth range of the target geological body to obtain the target range; The resolution requirements and numerical stability conditions of the target geological body are obtained, and the target spacing is obtained based on the resolution requirements and numerical stability conditions of the target geological body.

3. The anisotropic travel time acquisition method based on the slow-degree domain according to claim 1, characterized in that, The step of traversing all grid points in the spatial grid model according to a preset scanning order, starting from the target seismic source point based on the target slowness domain equation, to obtain the shortest travel time of the target grid point includes: An initial travel time is preset for all grid points except the target seismic source point, and the initial travel time is greater than the quotient of the maximum distance and the minimum wave velocity in the spatial grid model; Starting from the target seismic source point based on the preset scanning order, a local travel time solution is calculated based on the travel time of adjacent solved points. If the local travel time solution is greater than the current travel time solution, the current travel time solution is replaced based on the local travel time solution. Repeat the steps of starting from the target seismic source point based on the preset scanning order and calculating the local travel time solution based on the travel time of adjacent solved points until the target convergence condition is met, and output the shortest travel time of the target grid point.

4. The anisotropic travel time acquisition method based on the slow-degree domain according to claim 3, characterized in that, After the target convergence condition is met, the following is also included: The travel time of each grid point in the spatial grid model is verified based on the anisotropic medium parameters. If a negative value appears or the wavefront propagation direction is inconsistent with the anisotropic law corresponding to the anisotropic medium parameters, the output result is judged to be unreasonable. If no negative value appears and the wavefront propagation direction is consistent with the anisotropic law corresponding to the anisotropic medium parameters, then the travel time grid data in the spatial grid model is output.

5. An anisotropic travel time acquisition device based on the slow-degree domain, characterized in that, include: A mesh construction module is used to acquire target spacing, target range, and anisotropic medium parameters, and to construct a spatial mesh model based on the target spacing, target range, and anisotropic medium parameters. The spatial mesh model includes target seismic source points, and the travel time of the target seismic source points is a target value. The target spacing is the mesh spacing of the spatial mesh model; the target range is the total size of the spatial mesh model; and the anisotropic medium parameters are used to assign simulated geological conditions to the spatial mesh model. The grid point acquisition module is used to acquire target grid points in the spatial grid model based on the relative positions of the target location and the actual target seismic source point when calculating the travel time of the target location. The slow-degree domain equation acquisition module is used to acquire anisotropic equations and acquire target slow-degree domain equations based on the anisotropic equations. The scanning module is used to start from the target seismic source point based on the target slowness domain equation and traverse all grid points in the spatial grid model according to a preset scanning order to obtain the shortest travel time of the target grid point; The anisotropic equations include a first anisotropic equation and a second anisotropic equation, wherein the first anisotropic equation is: qP wave and qSV The anisotropic equation of the wave, the second anisotropic equation is: qSH The anisotropic equation of a wave; The first anisotropic equation is: ； ； ； ； ； ； The second anisotropic equation is: ； in, , These represent the horizontal and vertical travel gradient components, respectively. and They are respectively in the axially symmetric direction P wave and S wave speed, , and All parameters are Thomson parameters; The target slowness domain equation is obtained based on the anisotropic equation, including: Obtain the target relation, which includes a first relation and a second relation, and the target relation represents the relationship between travel time gradient and slowness. The first anisotropic equation is decomposed to obtain the first sub-equation and the second sub-equation. Substituting the first relation into the first sub-equation, we obtain the first target slowness domain equation; Substituting the second relation into the second sub-equation, we obtain the second objective slowness domain equation; Substituting the first and second relations into the second anisotropic equation, a third target slowness domain equation is obtained, which is composed of the first target slowness domain equation, the second target slowness domain equation, and the third target slowness domain equation. The first relation is: ； The second relation is: ； in, d The distance between the target grid point and the target seismic source point. S The slowness of the target grid point. h The grid spacing is... , These represent the gradient components in the horizontal and vertical directions, respectively. i , j These represent the horizontal and vertical grid values ​​of the target grid point, respectively. For grid points ( i -1, j The slowness of ) For grid points ( i +1, j The slowness of ) For grid points ( i , j The slowness of ) For grid points ( i , j -1) slowness, For grid points ( i , j +1) slowness, d and All of these are the distances between the target grid points and the target seismic source points. , These represent the distance components in the horizontal and vertical directions, respectively. express d right x Find the partial derivative. express d right z Find the partial derivatives; The equation for the first target slowness domain is: ； The second objective slowness domain equation is: ； in, ; ; The equation for the third objective slowness domain is: 。 6. A terminal, characterized in that, The terminal includes: a processor and a computer-readable storage medium communicatively connected to the processor. The computer-readable storage medium is adapted to store multiple instructions, and the processor is adapted to call the instructions in the computer-readable storage medium to execute the steps of implementing the anisotropic time travel acquisition method based on the slow-degree domain as described in any one of claims 1-4.

Images