A method, apparatus, equipment, and storage medium for near-surface modeling in the Loess Plateau region.

Abstract

This invention discloses a method, apparatus, equipment, and storage medium for near-surface modeling in the Loess Plateau region, belonging to the field of geophysical exploration technology. The method includes calculating the shallow surface velocity field, calculating the weathered layer velocity obtained from tomographic inversion, calculating the weighting coefficients for correcting the weathered layer velocity, smoothing, calculating the weathered layer velocity, calculating the weathered layer thickness, and calculating the elevation of the high-velocity top interface, smoothing again, and obtaining the final constructed near-surface model. This method does not rely on excessive ultra-deep micro-logging, and can obtain a high-precision near-surface model while reducing exploration investment and saving costs, providing high-quality basic data for subsequent static correction and pre-stack depth migration processing.

Description

Technical Field

[0001] This invention belongs to the field of geophysical exploration technology, and relates to a method, apparatus, equipment and storage medium for near-surface modeling in the Loess Plateau region, and in particular to a surface modeling method, apparatus, equipment and storage medium for static correction and processing technology in seismic exploration of areas with thick weathering layers. Background Technology

[0002] Near-surface modeling is fundamental to both field seismic acquisition and indoor processing. First, the accuracy of the near-surface model directly impacts the design of excitation well depths, the design of geophone assembly elevation differences, and the accuracy of field static corrections—factors that determine the quality of the raw data. Second, the accuracy of the near-surface model affects the accuracy of subsequent first-arrival static correction inversions. Only by using a high-accuracy near-surface model as the initial / constraint condition for refraction / tomography inversions can the accuracy of first-arrival static corrections be guaranteed, thereby improving the imaging results of time-level stacking and pre-stack depth migration processing. Finally, the accuracy of the near-surface model is one of the key factors in the effectiveness of pre-stack depth migration processing; low accuracy will severely affect the final imaging quality.

[0003] There are two most commonly used near-surface modeling methods: surface modeling and first-arrival wave (including tomography and refraction) inversion. Surface modeling primarily uses the interpretation results of survey points in the low-velocity zone to interpolate and obtain the near-surface model. Its accuracy is limited by the precision and density of the control points in the low-velocity zone and the accuracy of the interlayer relationship coefficients. Accuracy is generally guaranteed at the low-velocity zone survey points; however, the model between these points is obtained through interpolation, making accuracy difficult to guarantee. Tomography / refraction inversion is a method for inverting the near-surface model based on the first-arrival time of the artillery. Due to the large trace spacing, tomography inversion lacks sufficient detail in depicting very shallow surface layers; refraction inversion requires known, highly accurate weathering layer velocity / thickness as initial conditions before the weathering layer thickness / velocity can be calculated, but such conditions are difficult to meet in actual exploration.

[0004] Another modeling method for the near-surface layer in transitional areas can combine the advantages of tomographic inversion static correction in areas with thick weathered layers and high accuracy of long-wavelength static correction, with the advantages of refraction static correction in mountainous areas with high accuracy of short-wavelength static correction. However, the purpose of this method is to improve the accuracy of static correction, but this cannot guarantee the accuracy of the near-surface model.

[0005] Surface modeling is the simplest modeling method, but in the Loess Plateau region where the weathering layer is hundreds of meters thick, only micro-logging surveys can guarantee accuracy. Due to the limitations of exploration investment and input-output ratio, it is impossible to carry out too many ultra-deep micro-logging surveys to support near-surface modeling work.

[0006] Therefore, in the process of seismic exploration, especially in the near-surface area with a thick weathering layer, how to provide a method that can reduce the number of ultra-deep micro-logging wells used while constructing a high-precision near-surface model is a real problem in the field of geophysical exploration technology. Summary of the Invention

[0007] The purpose of this invention is to solve the problems in the prior art and provide a method, apparatus, equipment and storage medium for near-surface modeling in the Loess Plateau region. This method can obtain a high-precision near-surface model by relying on only a small number of ultra-deep micro-logging wells.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] This invention provides a method for near-surface modeling in the Loess Plateau region, comprising the following steps:

[0010] Based on the structure of the Loess Plateau, physical points are set according to the design requirements. These physical points include excitation points, detector points, and micro-logging well locations.

[0011] Obtain 2D or 3D exploration data of the Loess Plateau region, and perform tomographic inversion on the obtained data to calculate the shallow surface velocity field of the 2D or 3D work area.

[0012] Based on the results of the micro-logging survey, the elevation of the high-velocity top interface of each physical point in the shallow velocity field of the 2D or 3D work area is extracted, and the weathering layer velocity value of each physical point is calculated by tomographic inversion.

[0013] Based on the average velocity of the weathered layer obtained from the micrologging survey and the weathered layer velocity value obtained from the tomographic inversion at the micrologging location, the weighting coefficient for correcting the weathered layer velocity is calculated.

[0014] The weathering layer velocity at each physical point is calculated based on the weathering layer velocity values ​​obtained from the tomographic inversion at each physical point and the weighting coefficients for correcting the weathering layer velocity.

[0015] Based on the weathering velocity at each physical point, the initial arrival of the 2D or 3D cannon is refracted and inverted to calculate the weathering thickness at each physical point.

[0016] Based on the surface elevation and weathering layer thickness of each physical point, the elevation of the high-velocity top interface of each physical point is calculated, and then a near-surface model is constructed.

[0017] Preferably, based on the results of micro-logging surveys, the elevation of the high-velocity top interface of each physical point in the shallow surface velocity field of the 2D or 3D work area is extracted, and the weathering layer velocity value of each physical point is calculated by tomographic inversion.

[0018] The elevation of the high-velocity top interface at the micro-logging location is calculated by subtracting the elevation of the micro-logging location from the weathered layer thickness interpreted in the shallow velocity field of the 2D or 3D work area.

[0019] Based on the elevation of the high-velocity top interface at the micro-logging location, the instantaneous velocity at the micro-logging location is calculated using tomographic inversion. This velocity value is then used as a parameter to interpret the shallow velocity field of the 2D or 3D work area. The top interface of this velocity is extracted, and the weathering layer velocity value below the surface and above the top interface of this velocity at each physical point is calculated using tomographic inversion.

[0020] Preferably, the method for calculating the weighting coefficient of the corrected weathering layer velocity based on the average velocity of the weathering layer obtained from the micro-logging survey and the weathering layer velocity value obtained from the tomographic inversion at the micro-logging location in the physical point is as follows: the average velocity value of the weathering layer obtained from the micro-logging survey is compared with the weathering layer velocity value obtained from the tomographic inversion at the micro-logging location to obtain the weighting coefficient of the corrected weathering layer velocity.

[0021] Preferably, the method for calculating the corrected weathering layer velocity value of each physical point based on the weathering layer velocity value obtained by tomography inversion of each physical point and the weighting coefficient of the corrected weathering layer velocity is as follows: the obtained weathering layer velocity value obtained by tomography inversion of each physical point is multiplied by the weighting coefficient of the corrected weathering layer velocity to obtain the corrected weathering layer velocity value of each physical point.

[0022] Then, the corrected weathering layer velocity values ​​of each physical point are smoothed with a smoothing radius of 100-2000m to obtain the weathering layer velocity of each physical point.

[0023] Preferably, the method for calculating the weathering layer thickness at each physical point by performing refraction inversion on the initial arrival of a 2D or 3D cannon based on the weathering layer velocity at each physical point is as follows:

[0024] Based on the initial offset range of the 2D or 3D refraction layer cannon, refraction layering should be carried out reasonably.

[0025] The refraction velocity can be calculated using the interchange method or the CMP domain fitting method.

[0026] When calculating the delay, the weathering velocity at each physical point is used as the initial condition for refraction inversion, and the weathering thickness is calculated using the following method:

[0027]

[0028] Where h0 is the thickness of the weathered layer; T1 is the time delay; v0 is the velocity of the weathered layer; v R The velocity of the refractive layer.

[0029] Preferably, the method for calculating the delay is the Gauss-Seidel method, the extended generalized interchange, or a hybrid algorithm.

[0030] Preferably, the method for calculating the elevation of the high-speed top interface of each physical point based on the surface elevation and the thickness of the weathered layer of each physical point is as follows: subtract the thickness of the weathered layer of each physical point from the surface elevation of each physical point to obtain the elevation of the high-speed top interface of each physical point.

[0031] Then, the elevation of the high-speed top interface of each physical point is smoothed with a smoothing radius of 100-2000m to obtain the final elevation of the high-speed top interface of each physical point.

[0032] A near-surface modeling device for the Loess Plateau region, comprising:

[0033] The physical point setting module is used to set physical points according to the structure of the Loess Plateau and design requirements, including excitation points, detector points and micro-logging well location points, and output them.

[0034] The Loess Plateau 2D or 3D Exploration Data Acquisition Module is used to receive information from the physical point setting module, acquire 2D or 3D exploration data of the Loess Plateau, perform tomographic inversion on the acquired data, calculate the shallow surface velocity field of the 2D or 3D work area and output it.

[0035] The weathering layer velocity value calculation module for each physical point tomographic inversion is used to receive the results output by the 2D or 3D exploration data acquisition module of the Loess Plateau area, and extract the high-velocity top interface elevation of each physical point in the shallow velocity field of the 2D or 3D work area based on the results of micro-logging survey, calculate and output the weathering layer velocity value for each physical point tomographic inversion;

[0036] The module for calculating the weight coefficient of the corrected weathering layer velocity is used to receive the results output by the module for calculating the weathering layer velocity value of each physical point through tomographic inversion, and to calculate and output the weight coefficient of the corrected weathering layer velocity based on the average weathering layer velocity obtained from the micro-logging survey and the weathering layer velocity value of the micro-logging location in the physical point through tomographic inversion.

[0037] The weathering layer velocity calculation module for each physical point is used to receive the output results of the weight coefficient calculation module for correcting the weathering layer velocity and the output results of the weathering layer velocity value calculation module for each physical point through tomography inversion, and to calculate and output the weathering layer velocity of each physical point based on the weathering layer velocity value for each physical point through tomography inversion and the weight coefficient for correcting the weathering layer velocity.

[0038] The weathering layer thickness calculation module for each physical point is used to receive the output results of the weathering layer velocity calculation module for each physical point, and perform refraction inversion on the initial arrival of the 2D or 3D cannon based on the weathering layer velocity of each physical point, calculate the weathering layer thickness of each physical point and output it.

[0039] The near-surface model construction module receives the output results of the weathering layer thickness calculation module for each physical point, and calculates the high-speed top interface elevation of each physical point based on the surface elevation and weathering layer thickness of each physical point, thereby constructing and displaying the near-surface model.

[0040] A terminal device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method described above.

[0041] A computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the method described above.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] This invention effectively solves the problem of accurately establishing near-surface models in areas with extremely thick weathered layers. This method requires only one or two ultra-deep micrologging wells within an exploration area, or even none at all, to construct a near-surface model for such areas. This method not only significantly reduces the workload of micrologging, saves exploration investment, and improves production efficiency, but also, as verified by actual data, shows that the thickness and velocity errors of the weathered layer are less than 5%, providing support for current seismic exploration technology in areas with extremely thick weathered layers in the Loess Plateau. Attached Figure Description

[0044] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a flowchart of the method for near-surface modeling in the Loess Plateau region according to the present invention.

[0046] Figure 2 This is a micro-logging time-depth curve diagram in an embodiment of the present invention.

[0047] Figure 3This is an example of a tomographic inversion velocity field and an extracted high-speed top interface diagram in an embodiment of the present invention.

[0048] Figure 4 This is a graph showing the velocity curve of the weathered layer obtained by chromatographic inversion in an embodiment of the present invention.

[0049] Figure 5 The image shows the weathering layer thickness and high-velocity top interface elevation obtained by refraction inversion in an embodiment of the present invention.

[0050] Figure 6 This is a cross-sectional view of the initial stack of horizontal superposition for static correction of the field model of the present invention.

[0051] Figure 7 This is a cross-sectional view of the initial stack of horizontal superposition of the tomographic inversion combined with the residual static correction of the refracted wave, according to the present invention.

[0052] Figure 8 This is a cross-sectional view of the initial stack of horizontal superposition of the present invention, which combines the residual static correction of refracted waves.

[0053] Figure 9 This is a diagram of the apparatus for near-surface modeling in the Loess Plateau region according to the present invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0055] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0056] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0057] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0058] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0059] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0060] The present invention will now be described in further detail with reference to the accompanying drawings:

[0061] This invention is based on a seismic exploration and acquisition project in a complex near-surface area of ​​the Tarim Basin. Due to the extremely thick weathered layer in this area, reaching over 500 meters, cost constraints prevented the implementation of numerous ultra-deep micro-logging operations. Only a small number of sparse ultra-deep micro-logging operations were conducted at key locations for surface investigation. Therefore, conventional surface investigation methods could not complete the surface modeling work. This invention discloses a method for near-surface modeling in the Loess Plateau region to address the above-mentioned problems. Taking a two-dimensional survey line from this project as an example, near-surface modeling work was carried out.

[0062] See Figures 1 to 5 The specific implementation is as follows: A method for near-surface modeling in the Loess Plateau region includes the following steps:

[0063] First, based on the structure of the Loess Plateau, appropriate locations were selected to set up excitation points, detector points, and micro-logging wells, which will be collectively referred to as physical points below for ease of description; the micro-logging wells selected were ultra-deep micro-logging wells.

[0064] Acquire 2D or 3D exploration data of the Loess Plateau region, and perform tomographic inversion on the acquired data to calculate the shallow surface velocity field of the 2D or 3D work area. Specifically, based on accurately capturing the initial 2D or 3D borehole data, assign a surface velocity of 500–1500 m / s and a gradient factor of 1–10 s². -1 An initial velocity model is established; a grid size of 5–20 m is selected vertically and 0.5–8 times the track spacing horizontally (generally within the range of 10–200 m); travel-time ray tomography is performed with an initial arrival time of 2–7 km and 8–15 iterations to obtain the 2D or 3D shallow surface velocity field of the work area. Taking 2D exploration data as an example, based on the accurate acquisition of the 2D initial arrival time, the following tomography parameters are reasonably selected:

[0065] Grid parameters: 15m horizontal spacing, 10m vertical spacing;

[0066] Initial velocity model parameters: initial velocity 800 m / s, gradient factor 3 s -1 ;

[0067] Initial offset range: 0–4 km;

[0068] Number of iterations: 10.

[0069] After travel-time tomography inversion using the above parameters, the shallow surface velocity field of the 2D work area was obtained.

[0070] See Figure 2 and Figure 3Based on the results of micrologging surveys, the elevation of the high-velocity top interface of each physical point in the shallow velocity field of the 2D work area is extracted, and the weathered layer velocity value obtained from tomographic inversion is calculated for each physical point. Specifically, the elevation of the high-velocity top interface at the micrologging location is calculated based on the difference between the elevation at the ultra-deep micrologging point and its interpreted weathered layer thickness. In the obtained shallow velocity field of the 2D work area, the instantaneous velocity obtained from tomographic inversion at the high-velocity top interface elevation of the micrologging location can be obtained. This instantaneous velocity value is then used as a parameter to interpret the shallow velocity field of the 2D work area, and the top interface of the instantaneous velocity at this tomographic inversion is extracted to obtain the weathered layer velocity value obtained from tomographic inversion below the surface and above the velocity top interface for each physical point. For example, if an ultra-deep micrologging well with a depth of 215m is drilled at a horizontal distance of 2715m from a 2D survey line, and the surface elevation of this micrologging well is 2514.5m, and the interpretation results of the micrologging well show that the weathered layer thickness is 202.4m, then at a horizontal distance of 2715m, the elevation of the high-velocity top interface of this micrologging well is 2514.5 - 202.4 = 2312.1m. In the obtained 2D shallow surface velocity field, the high-velocity top interface at the location of the micrologging well is... At the surface elevation, the instantaneous velocity obtained from the tomographic inversion at that location is 2050 m / s (at the same time, the average velocity of the weathered layer obtained from the tomographic inversion between the surface and the top interface elevation of this high velocity is 980.0 m / s). The instantaneous velocity value of 2050 m / s obtained from the tomographic inversion is used as a parameter to interpret the shallow surface velocity field. The top interface of this velocity is extracted, and then the tomographic inversion velocity value of the weathered layer below the surface and above the top interface of this velocity is obtained for each physical point.

[0071] Based on the average velocity of the weathered layer obtained from micrologging and the velocity values ​​of the weathered layer obtained from tomographic inversion at the micrologging locations within the physical points, a weighting coefficient for correcting the weathered layer velocity is calculated. Specifically, the average velocity value of the weathered layer obtained from the micrologging is compared with the tomographic inversion velocity value of the weathered layer obtained at the micrologging locations within the physical points to obtain the weighting coefficient for correcting the weathered layer velocity. Based on the micrologging results, i.e., the micrologging time-depth curve, the thicknesses of each layer at the micrologging locations are calculated to be 3.5m, 15.8m, 31.7m, 63.9m, and 87.5m; the corresponding weathered layer velocities are 287m / s, 476m / s, 821m / s, 1025m / s, and 1272m / s, respectively. Therefore, the average velocity value of the weathered layer obtained from the micrologging can be calculated as follows:

[0072]

[0073] Compared to the weathering layer velocity of 980.0 m / s obtained from the tomographic inversion at the micro-logging location, the weighting coefficient is:

[0074]

[0075] Where V0 is the average velocity value of the weathered layer obtained from micrologging survey, and R is the weighting coefficient.

[0076] See Figure 4 The weathering layer velocity at each physical point is calculated based on the tomographically derived weathering layer velocity values ​​and the weighting coefficients for correcting the weathering layer velocity. Specifically, the tomographically derived weathering layer velocity value for each physical point is productted with the weighting coefficient for correcting the weathering layer velocity to obtain the corrected weathering layer velocity value for each physical point. This corrected value is then smoothed with a smoothing radius of 100–2000 m to obtain the final weathering layer velocity for each physical point. Alternatively, the tomographically derived weathering layer velocity value for each physical point is productted with the weighting coefficient for correcting the weathering layer velocity (0.96) to obtain the corrected weathering layer velocity value for each physical point. This corrected value is then smoothed with a smoothing radius of 500 m to obtain the final weathering layer velocity for each physical point.

[0077] Based on the weathering velocity at each physical point, refraction inversion is performed on the initial arrival of a 2D or 3D cannon to calculate the weathering thickness at each physical point. Specifically, after refraction stratification, the refraction velocity and time delay are calculated. Then, the corrected and smoothed weathering velocity is used as the initial condition. Refraction stratification is reasonably performed based on the offset range of the initial arrival of the refraction layer. The refraction velocity is calculated using methods such as the interchange method or CMP domain fitting method. The time delay is calculated using the Gauss-Seidel method, extended generalized interchange, or hybrid algorithms. The weathering velocity at each physical point is then used as the initial condition for refraction inversion. Based on the time delay calculation formula, the formula for calculating the weathering thickness can be derived.

[0078]

[0079] In the formula, h0 is the thickness of the weathered layer (m); T1 is the delay time (ms); v i V is the velocity of the regolith (m / s); R The velocity of the refractive layer is (m / s).

[0080] See Figure 5 Based on the surface elevation and weathering layer thickness of each physical point, the elevation of the high-speed top interface of each physical point is calculated, and a near-surface model is constructed. Specifically, the surface elevation of each physical point is subtracted from its own weathering layer thickness to obtain the elevation of the high-speed top interface. Then, the elevation of the high-speed top interface is smoothed with a smoothing radius of 500m to obtain the final elevation of the high-speed top interface.

[0081] See Figures 6 to 8 Compared with static correction methods for field models and static correction methods for tomographic inversion, this invention has significant advantages. Figure 6In the horizontally superimposed initial cross-section, the shallowest seismic reflection phase axis of 0.5–1.0s shows the bottom boundary of the loess. Within the two rectangular frames of 2.0–5.0km and 11.0–14.5km on the horizontal axis, the continuity of the effective seismic reflection phase axis of the static correction of the field model is poor, and the overall shape is uneven. Figure 7 In the meantime, the continuity of the effective seismic reflection phase axis after static tomography correction is relatively good and generally smooth, but there are still undulations in the fine details, which does not match the actual near-surface conditions. Figure 8 In the static correction using the method of this invention, the continuity of the effective seismic reflection phase axis in shallow layers is good, and the shape is relatively straight, truly reflecting the distribution pattern of the loess base. Deep seismic data also demonstrates the advantages of this invention: in existing technologies, in the two rectangular frames at 2.0–9.0 km and 15.0–20.5 km, and at the location indicated by the arrow near 10.0 km, the effective seismic reflection phase axis of the field static correction profile generally exhibits poor imaging effect, poor continuity, and difficulty in tracking and comparison. However, the imaging effect is improved by the tomographic static correction method of this invention. Therefore, this invention also has the advantages of the highest static correction accuracy, the best imaging effect, and the ability to continuously track and compare the effective seismic reflection phase axis.

[0082] See Figure 9 The present invention provides an apparatus for near-surface modeling of the Loess Plateau region capable of performing the above-mentioned method, including a 2D or 3D exploration data acquisition module for the Loess Plateau region, used to acquire 2D or 3D exploration data of the Loess Plateau region, perform tomographic inversion on the acquired data, calculate the shallow surface velocity field of the 2D or 3D work area and output it.

[0083] The module for calculating the weathering layer velocity value obtained by tomography inversion of each physical point is used to receive the results output by the module for acquiring 2D or 3D exploration data in the Loess Plateau area, and extract the high-velocity top interface elevation of each physical point in the shallow velocity field of the 2D or 3D work area based on the results of micro-logging survey, calculate and output the weathering layer velocity value obtained by tomography inversion of each physical point.

[0084] The module for calculating the weight coefficient of the corrected weathering layer velocity is used to receive the results output by the module for calculating the weathering layer velocity value of each physical point through tomographic inversion, and to calculate and output the weight coefficient of the corrected weathering layer velocity based on the average weathering layer velocity obtained from the micro-logging survey and the weathering layer velocity value of the micro-logging location in the physical point through tomographic inversion.

[0085] The weathering layer velocity calculation module for each physical point is used to receive the output results of the weight coefficient calculation module for correcting the weathering layer velocity and the output results of the weathering layer velocity value calculation module for each physical point through tomography inversion. Based on the weathering layer velocity value for each physical point through tomography inversion and the weight coefficient for correcting the weathering layer velocity, the module calculates and outputs the weathering layer velocity for each physical point.

[0086] The weathering layer thickness calculation module for each physical point is used to receive the output results of the weathering layer velocity calculation module for each physical point, and perform refraction inversion on the initial arrival of the 2D or 3D cannon based on the weathering layer velocity of each physical point, calculate the weathering layer thickness of each physical point and output it.

[0087] The near-surface model construction module receives the output results from the weathering layer thickness calculation module of each physical point, and calculates the high-speed top interface elevation of each physical point based on the surface elevation and weathering layer thickness of each physical point, thereby constructing and displaying the near-surface model.

[0088] In use, after setting the positions of various physical points according to the structure of the Loess Plateau, 2D or 3D exploration data is transmitted to the device. Through the action of various modules in the device, the near-surface model of the Loess Plateau area is finally completed. The device has a simple structure, is easy to operate, and improves production efficiency.

[0089] This invention provides a terminal device comprising: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the steps in the various method embodiments described above. Alternatively, when the processor executes the computer program, it implements the functions of each module / unit in the various device embodiments described above.

[0090] The computer program can be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present invention.

[0091] The terminal device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0092] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0093] The memory can be used to store the computer program and / or module. The processor implements various functions of the terminal device by running or executing the computer program and / or module stored in the memory and calling the data stored in the memory.

[0094] If the modules / units integrated into the terminal device are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electrical carrier signals and telecommunication signals.

[0095] This invention can complete the entire process of near-surface modeling in areas with extremely thick weathered layers in just six steps. The principle is clear, the operation is strong, and it only requires a small number of micro-logging wells to complete the near-surface modeling of areas with extremely thick weathered layers. This saves exploration investment costs and improves production efficiency. Moreover, as verified by actual data, the method has a weathered layer thickness error and velocity error of less than 5%, providing support for the current seismic exploration technology for areas with extremely thick weathered layers in the Loess Plateau.

[0096] The above are merely preferred embodiments of the present invention and are not intended to limit the present 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.

Claims

1. A method for near-surface modeling in a loess plateau region, characterized in that, The method comprises the following steps: According to the structure of the loess plateau, physical points including excitation points, detection points and micro-logging position points are set according to design requirements; 2D or 3D exploration data of the loess plateau area are acquired, and the acquired data are tomographically inverted to calculate 2D or 3D work area shallow layer velocity field; According to the results of the micro-logging survey, the high-speed top interface elevation of each physical point in the 2D or 3D work area shallow layer velocity field is extracted, and the weathering layer velocity value of each physical point tomographically inverted is calculated; According to the average velocity of the weathering layer obtained by the micro-logging survey and the weathering layer velocity value of the micro-logging position point tomographically inverted, the weight coefficient of the corrected weathering layer velocity is calculated; According to the weathering layer velocity of each physical point, the 2D or 3D shot first arrival is refracted and inverted to calculate the weathering layer thickness of each physical point; According to the ground elevation of each physical point and the weathering layer thickness of each physical point, the high-speed top interface elevation of each physical point is calculated, and a near-surface model is constructed. According to the results of the micro-logging survey, the high-speed top interface elevation of each physical point in the 2D or 3D work area shallow layer velocity field is extracted, and the weathering layer velocity value of each physical point tomographically inverted is calculated; 2. The method for modeling the near-surface of a loess plateau region according to claim 1, wherein, The elevation of the micro-logging position point in the 2D or 3D work area shallow layer velocity field is subtracted from the interpreted weathering layer thickness to calculate the high-speed top interface elevation of the micro-logging position point; According to the high-speed top interface elevation of the micro-logging position point, the tomographically inverted instantaneous velocity at the micro-logging position is calculated, and the velocity value is taken as a parameter for interpreting the 2D or 3D work area shallow layer velocity field, the top interface of the velocity is extracted, and the weathering layer velocity value tomographically inverted above the top interface and below the ground of each physical point is calculated. According to the average velocity of the weathering layer obtained by the micro-logging survey and the weathering layer velocity value of the micro-logging position point tomographically inverted, the weight coefficient of the corrected weathering layer velocity is calculated; 3. The method for modeling the near-surface of a loess plateau region according to claim 1, wherein, According to the weathering layer velocity of each physical point, the 2D or 3D shot first arrival is refracted and inverted to calculate the weathering layer thickness of each physical point; 4. The method for modeling the near-surface of a loess plateau region according to claim 1, wherein, According to the ground elevation of each physical point and the weathering layer thickness of each physical point, the high-speed top interface elevation of each physical point is calculated, and a near-surface model is constructed. The method for calculating the high-speed top interface elevation of each physical point in the 2D or 3D work area shallow layer velocity field according to the results of the micro-logging survey is as follows:

5. The method for near-surface modeling of loess table region according to claim 1, characterized in that, The elevation of the micro-logging position point in the 2D or 3D work area shallow layer velocity field is subtracted from the interpreted weathering layer thickness to calculate the high-speed top interface elevation of the micro-logging position point; According to the high-speed top interface elevation of the micro-logging position point, the tomographically inverted instantaneous velocity at the micro-logging position is calculated, and the velocity value is taken as a parameter for interpreting the 2D or 3D work area shallow layer velocity field, the top interface of the velocity is extracted, and the weathering layer velocity value tomographically inverted above the top interface and below the ground of each physical point is calculated. The method for calculating the weight coefficient of the corrected weathering layer velocity according to the average velocity of the weathering layer obtained by the micro-logging survey and the weathering layer velocity value of the micro-logging position point tomographically inverted is as follows: The average velocity of the weathering layer obtained by the micro-logging survey is divided by the weathering layer velocity value obtained by the micro-logging position point tomographically inverted to obtain the weight coefficient of the corrected weathering layer velocity. The method for calculating the weathering layer velocity of each physical point according to the weathering layer velocity value of each physical point tomographically inverted and the weight coefficient of the corrected weathering layer velocity is as follows: The weathering layer velocity value of each physical point tomographically inverted is multiplied by the weight coefficient of the corrected weathering layer velocity to obtain the corrected weathering layer velocity value of each physical point; The corrected weathering layer velocity value of each physical point is smoothed with a smoothing radius of 100-2000 m to obtain the weathering layer velocity of each physical point. The method for calculating the weathering layer thickness of each physical point by refracting and inverting the 2D or 3D shot first arrival according to the weathering layer velocity of each physical point is as follows: The 2D or 3D refracted layer shot first arrival is reasonably refracted and layered according to the offset range of the 2D or 3D refracted layer shot first arrival; The refracted velocity is calculated by using the interchange method or the CMP domain fitting method; When the delay is calculated, the weathering layer velocity of each physical point is taken as the initial condition of the refraction inversion, and the following method is used to calculate the weathering layer thickness: where h0 is the weathered layer thickness; T1 is the delay time; v0 is the weathered layer velocity; v R is the refracted layer velocity.

6. The method for modeling the near-surface of a loess plateau region according to claim 5, wherein, The method for calculating the delay is the Gauss-Seidel method, the extended generalized reciprocal or the mixed algorithm.

7. The method for near-surface modeling of loess table region according to claim 1, characterized in that, According to the ground elevation of each physical point and the weathering layer thickness of each physical point, the method for calculating the high-velocity top interface elevation of each physical point is: the ground elevation of each physical point is subtracted by the weathering layer thickness of each physical point itself to calculate the high-velocity top interface elevation of each physical point; Then, the high-velocity top interface elevation of each physical point is smoothed with a smoothing radius of 100-2000m to obtain the final high-velocity top interface elevation of each physical point.

8. A near-surface modeling device for loess plateau region, characterized in that, It comprises: A physical point setting module, which is used to set physical points according to the structure of the loess tableland and design requirements, including shooting points, geophone points and micro-logging position points and output; A loess tableland area 2D or 3D exploration data acquisition module, which is used to receive the information of the physical point setting module, acquire loess tableland area 2D or 3D exploration data, and perform tomographic inversion on the acquired data to calculate and output the 2D or 3D work area shallow layer velocity field; A weathering layer velocity value calculation module for each physical point tomographic inversion, which is used to receive the output results of the loess tableland area 2D or 3D exploration data acquisition module, extract the high-velocity top interface elevation of each physical point in the 2D or 3D work area shallow layer velocity field according to the micro-logging survey results, calculate the weathering layer velocity value of each physical point tomographic inversion and output; A weight coefficient calculation module for correcting the weathering layer velocity, which is used to receive the output results of the weathering layer velocity value calculation module for each physical point tomographic inversion, calculate the weight coefficient for correcting the weathering layer velocity according to the average weathering layer velocity obtained by micro-logging survey and the weathering layer velocity value of the micro-logging position in the physical point tomographic inversion and output; A weathering layer velocity calculation module for each physical point, which is used to receive the output results of the weight coefficient calculation module for correcting the weathering layer velocity and the output results of the weathering layer velocity value calculation module for each physical point tomographic inversion, calculate the weathering layer velocity of each physical point according to the weathering layer velocity value of each physical point tomographic inversion and the weight coefficient for correcting the weathering layer velocity and output; A weathering layer thickness calculation module for each physical point, which is used to receive the output results of the weathering layer velocity calculation module for each physical point, perform refraction inversion on the 2D or 3D first arrival according to the weathering layer velocity of each physical point to calculate the weathering layer thickness of each physical point and output; A near-surface model construction module, which is used to receive the output results of the weathering layer thickness calculation module for each physical point, calculate the high-velocity top interface elevation of each physical point according to the ground elevation of each physical point and the weathering layer thickness of each physical point, and then construct and display the near-surface model.

9. A terminal device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, The computer program is executed by the processor to implement the steps of the method according to any one of claims 1-7.

10. A computer-readable storage medium storing a computer program, the computer program comprising instructions that, when executed by a computer, cause the computer to perform the method of any one of claims 1 to 9. The computer program is executed by the processor to implement the steps of the method according to any one of claims 1-7.

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