Tunnel seismic and electrical method joint inversion method and system based on structural constraint

Abstract

The application provides a tunnel seismic and electrical method joint inversion method and system based on structural constraints, constructs resistivity models and wave velocity models of different detection distances; performs seismic and electrical method single inversion, calculates a structural constraint term for a common joint inversion area of the resistivity model and the wave velocity model according to inversion results; based on the characteristics of the structural constraint, different coefficients are set for the structural constraint term to balance the data term and the structural constraint term, to obtain the final structural constraint term, which is alternately added to the loss functions of the seismic and electrical methods, to obtain respective joint inversion results based on the structural constraint. The application can optimize the tunnel full waveform inversion and improve the effect of the joint inversion.

Description

Technical Field

[0001] This invention belongs to the field of geophysical exploration technology and relates to a method and system for joint inversion of tunnel seismic and electrical methods based on structural constraints. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] To reveal the structure and physical property distribution of subsurface media, various geophysical methods, including gravity, magnetometry, seismic, and electrical methods, are increasingly being used in exploration. Each method utilizes its observational data, relying on different geophysical properties to infer subsurface structures and reflect specific physical properties of subsurface materials, each with its own advantages and disadvantages. Seismic and electrical methods are two important geophysical exploration methods; however, with increasing exploration depth and environmental complexity, the effective information obtained by a single geophysical method is limited and often faces the problem of insufficient data volume, leading to potential multiple solutions in inversion methods.

[0004] Joint inversion, a significant trend in the field of geophysical inversion, integrates multiple exploration methods and geophysical observation data to effectively suppress inversion ambiguity and obtain more accurate subsurface medium information. Joint inversion based on structural similarity includes methods based on model curvature information, cross gradients, model gradient point products, and local correlations. Cross gradients, as an effective means of joint inversion, do not rely on prior physical property information, have strong applicability, and are currently a research hotspot. Furthermore, utilizing prior information to provide better initial models for wave velocity and resistivity models in both numerical and structural aspects can effectively improve the results of joint inversion.

[0005] Currently, there are two main challenges in achieving joint seismic and electrical inversion of tunnels based on structural constraints:

[0006] The quality of seismic and electrical resistivity inversions heavily relies on artificially set initial models. However, it is difficult to provide a good initial model that includes large-scale structures in tunnel exploration, making the inversion process prone to getting trapped in local extrema. Utilizing numerical and structural information from geological survey data, pre-drilled boreholes, and pilot tunnels to provide a good initial model for tunnel inversion is fundamental to achieving joint inversion.

[0007] Post-processing for seismic inversion and electrical resistivity inversion with different detection distances is crucial. Current joint inversion methods often only invert the common detection space of different detection methods, failing to utilize the joint inversion results for methods with larger detection distances for further optimization. Achieving global optimization of detection methods with different detection distances is a problem that must be solved to improve the overall effectiveness of joint inversion. Summary of the Invention

[0008] To address the aforementioned problems, this invention proposes a method and system for joint inversion of tunnel seismic and electrical methods based on structural constraints. This invention can optimize the full waveform inversion of tunnels and improve the effect of joint inversion.

[0009] According to some embodiments, the present invention adopts the following technical solution:

[0010] A joint seismic and electrical inversion method for tunnels based on structural constraints includes the following steps:

[0011] Construct resistivity and wave velocity models for different detection distances;

[0012] Seismic and electrical inversions were performed separately, and structural constraint terms were calculated for the joint inversion region of the resistivity model and wave velocity model based on the inversion results.

[0013] Based on the characteristics of structural constraints, different coefficients are set for the structural constraint terms to balance the data terms and structural constraint terms, resulting in the final structural constraint terms. These are then alternately added to the loss functions of seismic and electrical methods to obtain joint inversion results based on structural constraints.

[0014] As an alternative implementation, the specific process of constructing resistivity models and wave velocity models with different detection distances includes generating corresponding three-dimensional tunnel resistivity models and three-dimensional tunnel velocity models based on the different actual detection distances. The detection distance of the three-dimensional tunnel resistivity model is smaller than the actual detection distance, and the detection distance of the three-dimensional tunnel velocity model is larger than the actual detection distance.

[0015] As an alternative implementation, the resistivity model and the wave velocity model have the same cross-sectional scale, and the same length as the resistivity model is selected in the longitudinal scale as the joint inversion region.

[0016] As an alternative implementation, the specific process for calculating structural constraint terms in the joint inversion region includes performing separate seismic and electrical inversions, calculating a cross gradient term function for the joint inversion region based on the inversion results, wherein the function is the product of the gradients of velocity and resistivity, and calculating the structural constraint term function based on the cross gradient term function.

[0017] Furthermore, the cross gradient term function is:

[0018]

[0019]

[0020]

[0021] in, and For the gradient of velocity and resistivity, These are the model parameter values ​​for velocity and resistivity, respectively, where s, b, c, and d represent the current mesh and the forward mesh in the x, y, and z directions, respectively. , , These represent the side lengths of the current grid in the x, y, and z directions, respectively. , , These are the side lengths of the forward grid in the x, y, and z directions, respectively.

[0022] As an alternative implementation method, the specific process of setting different coefficients for structural constraint terms to balance data terms and structural constraint terms includes setting weight coefficients for structural constraint terms based on the characteristics of structural constraints. These weight coefficients are adaptive weighting factors, selected according to the difference in magnitude between data terms and structural constraint terms, thereby balancing the influence of structural constraint terms and data fitting terms.

[0023] As an alternative implementation, the method also includes using the results of the joint inversion as the initial model for the overall wave velocity model, and further optimizing the wave velocity model for the non-common region.

[0024] A structurally constrained joint seismic and electrical method inversion system for tunnels includes:

[0025] The model building module is configured to construct resistivity and wave velocity models for different detection distances;

[0026] The constraint module is configured to perform separate seismic and electrical method inversions, and calculate structural constraint terms for the joint inversion region of the resistivity model and wave velocity model based on its inversion results.

[0027] The joint inversion module is configured to set different coefficients for the structural constraint terms based on the characteristics of structural constraints, so as to balance the data terms and structural constraint terms and obtain the final structural constraint terms. These are then alternately added to the loss functions of seismic and electrical methods to obtain the joint inversion results based on structural constraints.

[0028] A computer-readable storage medium storing a plurality of instructions adapted for loading by a processor of a terminal device and executing steps in the method.

[0029] A terminal device includes a processor and a computer-readable storage medium, the processor being configured to implement instructions; the computer-readable storage medium being configured to store a plurality of instructions adapted to be loaded by the processor and executed in accordance with the steps of the method described therein.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1. Based on prior information, numerical and structural information provided by geological survey data, advanced boreholes, and advanced pilot tunnels can provide a reliable initial model for seismic and electrical inversion. The large-scale structural information contained therein can be used to more effectively improve the inversion quality.

[0032] 2. Based on the characteristics of structural constraints, adaptive weight coefficients are set for structural constraint terms to balance data terms and structural constraint terms, thereby improving the reliability of constraints.

[0033] 3. This invention further optimizes the seismic wave velocity model in non-common areas. It uses the common area wave velocity model obtained by joint inversion as the initial model of the overall wave velocity model, and further optimizes the wave velocity model in non-common areas to improve the inversion effect.

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0035] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0036] Figure 1 This is a flowchart of the tunnel seismic and electrical method joint inversion method based on structural constraints in an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the joint inversion results of tunnel structural constraints in an embodiment of the present invention (a slice along the tunnel detection direction at z=15m).

[0038] Figure 3 This is a schematic diagram of the optimization and inversion results of the overall tunnel wave velocity model in this embodiment of the invention (a slice along the tunnel detection direction at z=15m). Detailed Implementation

[0039] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0040] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0041] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0042] Example 1

[0043] In one or more embodiments, a joint inversion method for tunnel seismic and electrical methods based on structural constraints is disclosed, combining... Figure 1 Specifically, it includes the following process:

[0044] (1) Construct wave velocity model and resistivity model. According to actual needs, the size of the resistivity model in this embodiment is 30×30×30m. The background resistivity of the resistivity model is 1000Ωm, the low-resistivity anomaly is 100Ωm, and the low-resistivity interface is 500Ωm. The size of the wave velocity model is 30×100×30m. The background wave velocity of the wave velocity model in the common area is 3000m / s, the low-speed anomaly is 2100m / s, the low-speed interface is 2500m / s, the background wave velocity in the last 70m is 2500m / s, and the high-speed interface is 3200m / s.

[0045] (2) Seismic inversion and electrical inversion are highly dependent on the initial model. If the initial model has a large error with the actual model, the inversion will fall into a local minimum. Therefore, geological exploration data, advanced borehole and advanced pilot tunnel information should be used to provide a more reliable initial model for seismic and electrical inversion in terms of structure and numerical values.

[0046] (3) Applying structural constraints and obtaining joint inversion results. In this embodiment, based on the characteristics of structural constraints, adaptive weight coefficients are set for the structural constraint terms, and the structural constraint terms are alternately added to the loss functions of seismic and electrical methods to obtain joint inversion results based on structural constraints. The specific process is as follows:

[0047] (3-1) First, perform separate inversions of seismic and electrical methods. Calculate the cross-gradient function based on the inversion results. Its expression is:

[0048]

[0049]

[0050]

[0051]

[0052] in, and For the gradient of velocity and resistivity, These are the model parameter values ​​for velocity and resistivity, respectively, where s, b, c, and d represent the current mesh and the forward mesh in the x, y, and z directions, respectively. , , These represent the side lengths of the current grid in the x, y, and z directions, respectively. , , These are the side lengths of the forward grid in the x, y, and z directions, respectively.

[0053] (3-2) Adaptive weighting coefficients are set for the structural constraint terms to balance the data terms and structural constraint terms, resulting in the final structural constraint terms, which take the following form:

[0054]

[0055]

[0056] Where k is the number of iterations. Let k be the adaptive weighting factor. For the cross gradient term, This is the overall structural constraint term.

[0057] (3-3) The obtained structural constraint terms are alternately added to the loss functions of seismic and electrical methods to obtain the joint inversion results based on structural constraints.

[0058] (4) Based on the results of the joint inversion, use them as the initial model of the overall wave velocity model to further improve the inversion results of the wave velocity model in the non-public area (such as the last 70m).

[0059] The present invention also provides the following product examples:

[0060] A structurally constrained joint seismic and electrical method inversion system for tunnels includes:

[0061] The model building module is configured to construct resistivity and wave velocity models for different detection distances;

[0062] The constraint module is configured to perform separate seismic and electrical method inversions, and calculate structural constraint terms for the joint inversion region of the resistivity model and wave velocity model based on its inversion results.

[0063] The joint inversion module is configured to set different coefficients for the structural constraint terms based on the characteristics of structural constraints, so as to balance the data terms and structural constraint terms and obtain the final structural constraint terms. These are then alternately added to the loss functions of seismic and electrical methods to obtain the joint inversion results based on structural constraints.

[0064] A computer-readable storage medium storing a plurality of instructions adapted for loading by a processor of a terminal device and executing steps in the method.

[0065] A terminal device includes a processor and a computer-readable storage medium, the processor being configured to implement instructions; the computer-readable storage medium being configured to store a plurality of instructions adapted to be loaded by the processor and executed in accordance with the steps of the method described therein.

[0066] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0067] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0068] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0069] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0071] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A joint seismic and electrical inversion method for tunnels based on structural constraints, characterized in that, Includes the following steps: Construct resistivity and wave velocity models for different detection distances; Seismic and electrical inversions were performed separately, and structural constraint terms were calculated for the joint inversion region of the resistivity model and wave velocity model based on the inversion results. Based on the characteristics of structural constraints, different coefficients are set for the structural constraint terms to balance the data terms and structural constraint terms, resulting in the final structural constraint terms. These are then alternately added to the loss functions of seismic and electrical methods to obtain joint inversion results based on structural constraints.

2. The method for joint inversion of tunnel seismic and electrical methods based on structural constraints as described in claim 1, characterized in that, The specific process of constructing resistivity models and wave velocity models with different detection distances includes generating corresponding three-dimensional tunnel resistivity models and three-dimensional tunnel wave velocity models based on the different actual detection distances. The detection distance of the three-dimensional tunnel resistivity model is smaller than the actual detection distance, and the detection distance of the three-dimensional tunnel wave velocity model is larger than the actual detection distance.

3. The method for joint inversion of tunnel seismic and electrical methods based on structural constraints as described in claim 1, characterized in that, The resistivity model and the wave velocity model have the same cross-sectional scale, and the same length as the resistivity model is selected as the joint inversion region in the longitudinal scale.

4. The method for joint inversion of tunnel seismic and electrical methods based on structural constraints as described in claim 1, characterized in that, The specific process for calculating the structural constraint term in the joint inversion region includes performing separate seismic and electrical method inversions, calculating the cross gradient term function for the joint inversion region based on the inversion results, wherein the function is the product of the gradients of velocity and resistivity, and calculating the structural constraint term function based on the cross gradient term function.

5. The method for joint inversion of tunnel seismic and electrical methods based on structural constraints as described in claim 4, characterized in that, The cross gradient term function is: in, and For the gradient of velocity and resistivity, These are the model parameter values ​​for velocity and resistivity, respectively, where s, b, c, and d represent the current mesh and the forward mesh in the x, y, and z directions, respectively. , , These represent the side lengths of the current grid in the x, y, and z directions, respectively. , , These are the side lengths of the forward grid in the x, y, and z directions, respectively.

6. The method for joint inversion of tunnel seismic and electrical methods based on structural constraints as described in claim 1, characterized in that, The specific process of setting different coefficients for structural constraint terms to balance data terms and structural constraint terms includes setting weight coefficients for structural constraint terms based on the characteristics of structural constraints. These weight coefficients are adaptive weighting factors, and the selection is based on the difference in magnitude between data terms and structural constraint terms to achieve a balance between the influence of structural constraint terms and data terms.

7. The method for joint inversion of tunnel seismic and electrical methods based on structural constraints as described in claim 1, characterized in that, It also includes using the results of the joint inversion as the initial model for the overall wave velocity model, and further optimizing the wave velocity model for the non-common region.

8. A joint inversion system for tunnel seismic and electrical methods based on structural constraints, characterized in that, include: The model building module is configured to construct resistivity and wave velocity models for different detection distances; The constraint module is configured to perform separate seismic and electrical method inversions, and calculate structural constraint terms for the joint inversion region of the resistivity model and wave velocity model based on its inversion results. The joint inversion module is configured to set different coefficients for the structural constraint terms based on the characteristics of structural constraints, so as to balance the data terms and structural constraint terms and obtain the final structural constraint terms. These are then alternately added to the loss functions of seismic and electrical methods to obtain the joint inversion results based on structural constraints.

9. A computer-readable storage medium, characterized in that, It stores multiple instructions adapted for loading by the processor of a terminal device and executing the steps of the method according to any one of claims 1-7.

10. A terminal device, characterized in that, It includes a processor and a computer-readable storage medium, the processor being used to implement various instructions; the computer-readable storage medium being used to store a plurality of instructions adapted to be loaded by the processor and executed in the steps of the method of any one of claims 1-7.

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