A borehole fracture stress field inversion analysis method and system based on direct dihedral angle method

Abstract

This application discloses a method and system for inverting and analyzing borehole fracture stress fields based on the right dihedral method, relating to the fields of geophysics and geological engineering technology. The method includes: batch loading fault data through a GUI interface and converting it to NED direction cosines; using the right dihedral method to divide the fault into compression and tension zones; using a coarse-fine two-stage grid search to determine the optimal principal stress direction and matching rate; searching for the minimum principal stress direction in the vertical plane and calculating the dual stress axis matching rate; finally, outputting the three principal stress directions based on the comprehensive matching probability and generating a stereographic projection map. This application improves data input efficiency through batch loading via a GUI interface; the two-stage grid search algorithm eliminates human error and improves the calculation accuracy of the optimal principal stress direction and matching rate; multiple statistical indicators provide quantitative evaluation, improving the reliability of the inversion results; and the GUI interface's visualization of the inversion results enhances engineering applicability and interactive efficiency.

Description

Technical Field

[0001] This application relates to the fields of geophysics and geological engineering technology, and in particular to a method and system for inverting and analyzing borehole fracture stress fields based on the right dihedral angle method. Background Technology

[0002] In fields such as geological engineering, oil and gas engineering, mining engineering, and seismic geology research, accurately determining the current stress field of the Earth's crust has extremely important engineering and scientific value. Stress field information is crucial for the following key applications: Rock mass stability assessment: In geotechnical engineering design such as mining, tunneling, and slope engineering, understanding the in-situ rock stress state is a fundamental condition for assessing rock mass stability, predicting rockburst and roof fall risks, and optimizing support design. The direction and magnitude of the stress field directly determine the deformation characteristics and failure modes of the surrounding rock. Oil and gas resource development optimization: In the development of unconventional oil and gas resources (shale gas, tight oil, etc.), hydraulic fracturing is a major production enhancement measure. The propagation direction of fracturing fractures is mainly controlled by the direction of geostress, and the direction of the maximum principal stress determines the main orientation of the fracturing fractures. Accurate stress field information can optimize well network deployment, fracturing design, and recovery rate prediction. Applications of Borehole Imaging Technology: With the widespread adoption of borehole imaging technologies (such as electrical imaging, ultrasonic imaging, and optical imaging), identifying and interpreting fractures from borehole wall images has become a standard procedure in various borehole engineering projects (oil and gas exploration, geothermal development, engineering geology, mining, etc.). Borehole imaging can not only identify the occurrence of natural structural fractures but also observe stress-induced fracturing of the borehole wall (borehole collapse, induced cracks), providing a valuable data source for obtaining underground stress information. Earthquake Hazard Assessment: The sliding mode and earthquake rupture mechanism of active faults are closely related to the regional stress field. By analyzing historical earthquake focal mechanism solutions or field fault striation data, the regional stress field can be inverted, providing a basis for earthquake hazard assessment and fault activity analysis. Geological Structural Evolution Research: Paleostress field inversion is an important means of reconstructing the tectonic evolution history of basins, understanding the dynamic processes of orogenic belts, and reconstructing the history of plate tectonics. Tectonic movements at different periods leave records of faults, joints, folds, etc., in rocks. By analyzing these tectonic elements, the paleostress state can be reconstructed.

[0003] Existing borehole stress inversion techniques largely rely on manual graphical methods or simplified calculations, which have significant limitations. Current methods generally have low levels of automation, are inefficient when processing large amounts of data, and manual operation is prone to introducing human error, making it difficult to guarantee inversion accuracy. Secondly, the analysis process often only provides a single "optimal solution," lacking quantitative evaluation indicators for the reliability of the results and the possibility of multiple solutions. Existing tools typically do not fully consider engineering application scenarios; data import is cumbersome, coordinate systems are inconsistent, inversion results are not intuitive, and seamless integration with engineering design software is difficult, limiting their promotion and application efficiency in practical applications. Summary of the Invention

[0004] The purpose of this application is to provide a method and system for inverting and analyzing the stress field of borehole fractures based on the right dihedral angle method. It can load data in batches through a GUI interface, which improves the efficiency of data input. The two-stage grid search algorithm eliminates human error and improves the calculation accuracy of the optimal principal stress direction and matching rate. The quantitative evaluation of multiple statistical indicators improves the reliability of the inversion results. The visualization of the inversion results through the GUI interface improves the engineering applicability and interaction efficiency.

[0005] To achieve the above objectives, this application provides the following solution: Firstly, this application provides a method for inverting and analyzing the stress field of borehole fractures based on the right dihedral angle method. The method includes: batch loading fault data of borehole fractures using a GUI integrated interface; for each fault data point, calculating the normal vector and slip vector of the fault plane, and converting the normal vector and slip vector of the fault plane into direction cosines in the NED coordinate system; the fault data includes fault orientation and slicken orientation; the GUI integrated interface supports loading data formats including at least CSV, TXT, and Excel; for any candidate principal stress direction in the borehole fracture stress field space, dividing the fault region using the right dihedral angle method based on the slip vector and direction cosines of the fault plane; the fault region includes compression and tension zones; and using a coarse-fine two-stage mesh search strategy to determine the optimal principal stress direction in the borehole fracture stress field space. Matching rate with principal stress axes Specifically, this includes: in the coarse search phase, generating a coarse test mesh with a first preset angle step size, determining the optimal region, and calculating the principal stress axis matching rate. In the fine search phase, the optimal region is scanned at a second preset angle to determine the optimal principal stress direction. The principal stress axis matching rate Used to characterize the percentage of fault data falling into the compression zone out of the total fault data; in relation to the optimal principal stress direction Searching for the direction of minimum principal stress in a vertical plane For each candidate principal stress direction in the plane, calculate the bi-stress axis matching rate P2, and select the candidate direction with the largest bi-stress axis matching rate as the minimum principal stress direction. The direction of the intermediate principal stress is determined according to the right-hand rule. The dual stress axis matching ratio P2 is used to characterize the optimal principal stress direction. Located in the compression zone and in the direction of minimum principal stress The percentage of fault data located in the tension zone out of the total fault data; based on the principal stress axis matching rate. The overall matching probability is calculated by multiplying the product of the matching rate P2 and the bi-stress axis matching rate. And will combine the matching probability With the direction of optimal principal stress , direction of intermediate principal stress direction of minimum principal stress The inversion result is output as the result of the inversion; the inversion result is visualized graphically using a GUI integrated interface, and a stereographic projection map is output; the stereographic projection map is a projection map after the fault striation projection layer and the stress field P-value thermal layer are superimposed.

[0006] In a second aspect, this application also provides a computer system, including: 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 borehole fracture stress field inversion analysis method based on the right dihedral angle method described in the first aspect.

[0007] According to the specific embodiments provided in this application, the following technical effects are disclosed: This application improves data input efficiency by using a GUI interface for batch loading; the two-stage mesh search algorithm eliminates human error and improves the calculation accuracy of the optimal principal stress direction and matching rate; multiple statistical indicators are used for quantitative evaluation to improve the reliability of the inversion results; and the GUI interface provides a visual display of the inversion results, improving engineering applicability and interaction efficiency. Attached Figure Description

[0008] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0009] Figure 1 This is a flowchart illustrating a borehole fracture stress field inversion analysis method and system based on the right dihedral angle method, provided for embodiments of this application.

[0010] Figure 2 A schematic diagram of the geometric principle of the right dihedral angle method provided in the embodiments of this application.

[0011] Figure 3 This is a schematic diagram of data loading for the GUI integrated interface provided in an embodiment of this application.

[0012] Figure 4 P-value heatmap provided for embodiments of this application; in, Figure 4 The heatmap of the principal stress axis matching ratio P value in Figure 'a'; Figure 4 In the figure, b represents the thermogram of the matching ratio P value of the two stress axes.

[0013] Figure 5 This is an internal structure diagram of a computer system provided in an embodiment of this application. Detailed Implementation

[0014] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0015] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0016] Stress field inversion analysis methods have evolved from manual graphical methods to computer programs. Among them, the Right Dihedra Method, proposed by Angelier and Mechler in 1977, is a classic and effective stress field inversion method. This method is based on slip lineation data on fault / fracture surfaces and determines the direction of principal stresses through geometric analysis.

[0017] As shown in Table 1, the main symbols are explained below: Table 1 Symbol Table

[0018] Example 1, as Figures 1-3 As shown in the figure, this embodiment provides a method for inverting and analyzing the stress field of borehole fractures based on the right dihedral angle method. The method includes: S1. Using a GUI integrated interface, batch load the fault data of borehole fractures. For each fault data, calculate the normal vector and slip vector of the fault plane, and convert the normal vector and slip vector of the fault plane into direction cosines in the NED coordinate system. The fault data includes: fault orientation and slicken orientation. The GUI integrated interface supports loading data formats including at least any one of CSV, TXT and Excel.

[0019] Furthermore, step S1 specifically includes: S11. Import fault data of borehole fractures in batches at once using the file selector or drag-and-drop operation in the GUI integrated interface, and automatically classify and match the fault data of borehole fractures.

[0020] S12. For each fault data point, calculate the normal vector of the fault plane based on the fault attitude, and calculate the slip vector of the fault plane based on the striation attitude.

[0021] S13. Calculate the auxiliary vector perpendicular to the striation within the fault plane based on the normal vector and the slip vector of the fault plane, and output it as the direction cosine in the NED coordinate system.

[0022] Furthermore, the calculation formula for the auxiliary direction perpendicular to the scratch within the fracture surface is as follows: .

[0023] In the formula, For fault data The corresponding auxiliary vector perpendicular to the striation within the fault plane; For fault data The normal vector of the corresponding fault plane; For fault data The slip vector of the corresponding fault plane.

[0024] Optionally, the GUI integrated interface is responsible for reading, parsing, storing, and managing fault / fracture data. Its main functions include: 1) Multi-format data import: Supports CSV, TXT, Excel and other formats, and automatically recognizes data columns (tendency, tilt angle, lateral angle, lateral direction, sliding properties, etc.).

[0025] 2) Data structure definition: The Fault class is used to encapsulate a single fault data, and the FaultDataSet class manages the fault collection.

[0026] 3) Automatic coordinate conversion: Converts various attitude representations into direction cosines in the internal NED coordinate system.

[0027] 4) Data validation: Check the validity of the data (angle range, required fields, etc.) and mark abnormal data.

[0028] Optionally, the NED (North-East-Down) coordinate system is used as the internal calculation coordinate system, defined as follows: N (North): Points to due north, which is the positive direction of the π axis.

[0029] E (East): Points to due east, which is the positive direction of the y-axis.

[0030] D (down): Points towards the Earth's center (vertically downwards), which is the positive direction of the z-axis.

[0031] Optional, tomographic data conversion process.

[0032] For each fault data point i, perform the following transformation: 1) Calculate the normal vector of the fault plane ° The normal vector (pole) of the fault plane is determined by the fault dip angle δ and dip direction α. ​​The dip angle of the normal vector is (90°-δ), and the azimuth angle is (α+180°) mod 360°. .

[0033] 2) Calculate the sliding vector .

[0034] The slip vector (scratches / lineage) is determined by its plenum angle. and azimuth Sure: .

[0035] The sign of the slip vector is corrected based on the fault / fracture slip characteristics (normal / reverse fault): Normal fault / normal fracture .

[0036] Reverse fault / reverse fracture .

[0037] Optional, the slip vector (auxiliary vector) of the fault plane. The calculation formula is as follows: The slip vector (auxiliary vector) of the fault plane. It is the cross product of the normal vector and the slip vector, representing the direction perpendicular to the slip direction within the fault / fracture plane: .

[0038] Expand and normalize: .

[0039] Optionally, the direction cosine transformation formula is as follows: Given the plunge angle of a linear feature. The formula for converting the azimuth angle θ to the direction cosine (L, M, N) is: .

[0040] in: θ is the tilt angle, ranging from 0° to 90°, where 0° is horizontal and 90° is vertically downward. θ is the azimuth angle, ranging from 0° to 360°, measured clockwise from true north.

[0041] S2. For any candidate principal stress direction in the borehole fracture stress field space, the fault region is divided using the right dihedral angle method based on the sliding vector and direction cosine of the fault plane; the fault region includes: compression zone and tension zone.

[0042] Furthermore, step S2 specifically includes: S21. For any candidate principal stress direction in the borehole fracture stress field space, the sliding vector projection scalar is calculated based on the dot product of the candidate principal stress direction and the sliding vector of the fault plane.

[0043] S22. The auxiliary vector projection scalar is obtained by calculating the dot product of the candidate principal stress direction and the direction cosine.

[0044] S23. Determine whether the product of the sliding vector projection scalar and the auxiliary vector projection scalar is greater than 0. If yes, the candidate principal stress direction is located in the compression zone of the fault corresponding to the current fault data; if no, the candidate principal stress direction is located in the tension zone of the fault corresponding to the current fault data.

[0045] In practical applications, the core algorithm of the right dihedral angle method is based on the Wallace-Bott hypothesis: the sliding direction on a fault plane is consistent with the direction of the maximum shear stress on that plane. The mechanical implication of this hypothesis is that when the sliding direction (scratching or lining) of a fault / fracture is known, the geometric constraints that the stress field causing the sliding must satisfy can be deduced.

[0046] 1) Geometric principles For each fault / fracture, its fault / fracture surface and auxiliary surface (a plane passing through the slip line and perpendicular to the fault / fracture surface) divide the three-dimensional space into four quadrants: Compression dihedral angle (P-dihedra): The region where the maximum principal stress σ1 should be located, satisfying... .

[0047] Tension dihedral angle (T-dihedra): The region where the minimum principal stress σ3 should be located, satisfying... .

[0048] in, The dot product of the test direction and the sliding vector; The dot product of the test direction and the auxiliary vector.

[0049] 2) Implementation of the decision algorithm.

[0050] For any assumed principal stress direction in space (based on the tilt angle) (and the definition of azimuth angle θ):

[0051] .

[0052] Dihedral angle determination rule: .

[0053] S3. Using a coarse-fine two-stage mesh search strategy, determine the optimal principal stress direction in the borehole fracture stress field space. Matching rate with principal stress axes Specifically, this includes: in the coarse search phase, generating a coarse test mesh with a first preset angle step size, determining the optimal region, and calculating the principal stress axis matching rate. In the fine search phase, the optimal region is scanned at a second preset angle to determine the optimal principal stress direction. The principal stress axis matching rate Used to characterize the percentage of fault data falling into the compression zone out of the total fault data.

[0054] Furthermore, the first preset angle step size is 10°.

[0055] Furthermore, the second preset angle step size is 2°.

[0056] In practical applications, the coarse-fine two-stage grid search strategy adopts a two-stage grid search strategy from coarse to fine to balance computational efficiency and accuracy. This is a key technology for achieving high-precision automated inversion.

[0057] Phase 1: Coarse search.

[0058] Within the global surface of the lower hemisphere projection, a regular test mesh is generated with a large angular step size (default Δ=10°): Number of grid nodes: .

[0059] For each grid node Calculate the P1 value (the proportion of this direction falling into all fault compression zones): .

[0060] Record the optimal solution for the coarse search: .

[0061] Phase Two: Detailed Search.

[0062] Perform a fine scan within the neighborhood of the optimal solution found in the coarse search: Search scope: .

[0063] Fine step size: (default).

[0064] Number of nodes in the fine search grid: .

[0065] Finally, the optimal σ1 direction was determined: .

[0066] Preferred selection rule: When multiple directions have the same P1 value, the direction with the larger tilt angle (closer to vertical) is preferred.

[0067] S4. In the direction of the optimal principal stress Searching for the direction of minimum principal stress in a vertical plane For each candidate principal stress direction in the plane, calculate the bi-stress axis matching rate P2, and select the candidate direction with the largest bi-stress axis matching rate as the minimum principal stress direction. The direction of the intermediate principal stress is determined according to the right-hand rule. The dual stress axis matching ratio P2 is used to characterize the optimal principal stress direction. Located in the compression zone and in the direction of minimum principal stress The percentage of fault data located in the extensional zone out of the total fault data.

[0068] In practical applications, the search strategy is as follows: On the great circle plane perpendicular to σ1, traverse all possible σ3 directions (with a step size of δ=2°), and calculate the P2 value for each candidate direction: .

[0069] Choose the direction that maximizes P2 as the optimal σ3: .

[0070] σ² calculation: Based on the orthogonality of the stress tensor, σ² is determined by the right-hand rule (cross product): .

[0071] It also performs normalization and lower hemisphere constraint processing.

[0072] S5. Based on principal stress axis matching rate The overall matching probability is calculated by multiplying the product of the matching rate P2 and the bi-stress axis matching rate. And will combine the matching probability With the direction of optimal principal stress , direction of intermediate principal stress direction of minimum principal stress The result is output as the inversion result.

[0073] S6. Visualize the inversion results graphically using the GUI integrated interface and output a stereographic projection map; the stereographic projection map is a projection map after superimposing the fault striation projection layer and the stress field P-value thermal layer.

[0074] Furthermore, step S6 specifically includes: using a GUI integrated interface to display the optimal principal stress direction by varying the background color intensity. , direction of intermediate principal stress and the direction of minimum principal stress probability density distribution and overall matching probability Simultaneously, the fault poles and striation symbols are superimposed and displayed, and the stress mechanism of the region is shown.

[0075] Furthermore, the GUI integrated interface is based on the MVC architecture developed in Python.

[0076] Optionally, a modern GUI can be built based on the PySide6 framework, and professional visualizations can be implemented using Matplotlib: 1. Data Input Interface: Tabular data editor, supporting CRUD operations, copy and paste, and data validation.

[0077] 2. Parameter settings panel: Visual configuration of parameters such as search step size, projection type, and map style.

[0078] 3. Real-time visualization: After the analysis is completed, an epicentric projection diagram is automatically generated, supporting interactive operation.

[0079] 4. Result Export: Supports exporting high-resolution images (PNG / PDF / SVG) and data reports (TXT / JSON).

[0080] In practical applications, this embodiment achieves professional stereographic (Schmidt) visualization and generates publication-quality graphics.

[0081] The Schmidt projection (Lambert equal-area projection) is used to project points on the lower hemisphere onto the equatorial plane while keeping the area constant. .

[0082] Dual-panel layout like Figure 4 As shown in 'a', the left panel is a contour heatmap with the following color mapping: white → yellow → orange → red.

[0083] Contour levels: 50%, 60%, 70%, 80%, 90%, 100%.

[0084] like Figure 4 As shown in b, the contour heatmap on the right panel uses the YlGnBu color scale.

[0085] Figure 4 The symbols in the figure are explained in Table 2: Table 2. Symbols for Isoline Heatmaps

[0086] Furthermore, after step S6, the following steps are also included: S7. When the stereographic projection map shows two high-value centers with a separation degree greater than the separation threshold, the dataset composed of fault data is split using the selection function or data filter of the GUI integrated interface, and the pre-existing tectonic period and the late tectonic period are identified after inversion.

[0087] Furthermore, the sources of borehole fracture data and the specific principles of borehole imaging are as follows: Data for borehole fracture stress field inversion mainly comes from borehole imaging interpretation. Borehole imaging techniques (such as electrical imaging, ultrasonic imaging, optical imaging, etc.) can acquire high-resolution images of the borehole wall and identify natural structural fractures and stress-induced fractures.

[0088] Wellbore stress-induced fracture.

[0089] When a borehole penetrates rock formations, stress concentration around the well can lead to two types of characteristic fractures: Borehole breaks (BOs): When the tangential stress around the well exceeds the compressive strength of the rock, shear failure occurs in the direction of the minimum horizontal principal stress (Shmin), forming a symmetrical elliptical breakout zone. The breakout azimuth indicates the Shmin direction.

[0090] Drilling-induced tensile fractures (DITFs): When the perimeter tangential stress is lower than the tensile strength of the rock (becoming tensile stress), tensile fractures occur at the maximum horizontal principal stress. The direction forms axial tensile cracks. DITFs directly indicate the orientation. direction.

[0091] Natural structural fissures: Natural tectonic fractures are fracture surfaces formed under tectonic stress during geological history, and their characteristics include: 1) Fracture surface orientation: described by dip direction and dip angle, and appears as a sinusoidal curve trace on the borehole imaging unfolded diagram.

[0092] 2) Slip lines: Slip marks preserved on the fracture surface record the slip direction during fault activity.

[0093] 3) Slip properties: Determine the nature of the fault as a normal fault, reverse fault, or strike-slip fault based on the orientation of the lineation.

[0094] In the borehole imaging unfolded diagram, the intersection line between the inclined fracture surface and the cylindrical borehole wall unfolds into a sine curve, with its amplitude reflecting the dip angle and the azimuth of the crest reflecting the dip direction.

[0095] The relationship between data extraction and the right dihedral method: Fracture data extracted from borehole imaging data includes: 1) Crack surface normal vector N: Calculated from dip and dip angle, it is one of the core inputs of the right dihedral angle method.

[0096] 2) Slip vector S: obtained from the lineation orientation on the fracture surface, recording the slip direction.

[0097] 3) Sliding properties: Determine the sign of the scratch vector (positive / reverse).

[0098] These parameters constitute the complete fault striation data required for inversion using the right dihedral angle method. By statistically analyzing the dihedral angle constraints of multiple fracture data, the paleostress field orientation at the time of fracture formation can be inverted.

[0099] Illustration: 1) Fault / fracture surface (blue): Natural structural fracture surface interpreted by imaging logging, whose occurrence is determined by dip and dip angle.

[0100] 2) Auxiliary surface (orange): A plane passing through the slip line and perpendicular to the fault plane, spanned by the normal vector N and the slip vector S.

[0101] 3) Normal vector The extreme point of the fault plane points perpendicular to the fault plane and towards the hanging wall.

[0102] 4) Sliding vector The direction of slip lineation on the fracture surface records the direction of movement during fault activity.

[0103] 5) Auxiliary vector : A vector perpendicular to the sliding direction within the fault plane. .

[0104] 6) Region P (red): The area where the compressed dihedral angle σ1 should fall, satisfying... .

[0105] 7) T-zone (blue): The area where the dihedral angle σ3 should fall, satisfying the following conditions. .

[0106] 8) The line of intersection of two planes is the sliding vector. direction.

[0107] The technology in this application is as follows: Effect 1: High-precision automated inversion.

[0108] 1) Significantly improved computational accuracy: The two-stage grid search algorithm (coarse search + fine search) is adopted, and the angular resolution can reach 1°~2°, which is far superior to the 5°~10° accuracy of manual graphical methods.

[0109] 2) Eliminate human subjective error: The algorithm automatically traverses the entire space to find the optimal solution, and the results are completely repeatable and are not affected by the operator's subjective judgment.

[0110] 3) Efficiently process massive amounts of data: Analyzes hundreds of fault data points in milliseconds, supporting large-scale data application scenarios such as borehole imaging.

[0111] 4) Controllable algorithm complexity: The overall computational complexity is O(445n), where n is the number of faults, which ensures computational efficiency.

[0112] Effect 2: High-quality visualization in multiple dimensions.

[0113] 1) Publication-grade plot quality: Generates high-resolution plots of 300dpi and above based on Matplotlib, and supports exporting in multiple formats such as PNG, PDF, and SVG.

[0114] 2) Probability distribution heatmap: The spatial distribution of σ1 and σ3 compatibility is visually displayed by using contour lines.

[0115] 3) Dual-panel comparison display: The left side displays the P1 (compression zone compatibility) diagram, and the right side displays the P3 (tension zone compatibility) diagram.

[0116] 4) Complete primitive overlay: Simultaneously displays fault poles (distinguishing between normal / reverse / unknown faults), striation projection points, and principal stress axis positions.

[0117] 5) Professional stereographic projection: Schmidt equal-area projection is adopted to keep the area unchanged and conform to the standards of structural geology.

[0118] 6) Interactive GUI interface: Supports real-time parameter adjustment, data editing, graphic zooming and panning, and other operations.

[0119] Effect 3: Standardized coordinate system and data interface.

[0120] 1) NED coordinate system is used uniformly: all internal calculations are based on the North-East-Down coordinate system commonly used in seismology and engineering.

[0121] 2) Flexible data input: Supports multiple attitude representation methods and automatically performs coordinate transformation.

[0122] 3) Compatible with mainstream software: The output results can be directly imported into 3D modeling software such as ParaView and GeoModeller.

[0123] 4) Standard text format: Data files are in CSV / TXT format, which is convenient for exchange with tools such as Excel, Python, and MATLAB.

[0124] Effect 4: Quantitative quality assessment system. This application introduces multiple statistical indicators to quantify the reliability of the inversion results.

[0125] Effect 5: Modernized software architecture.

[0126] 1. MVC design pattern: Separation of model (algorithm) - view (interface) - controller, which facilitates maintenance and expansion.

[0127] 2. Modular structure: The three modules of data management, core algorithm and visualization are independent and can be called individually.

[0128] 3. Dual-mode operation: It provides both command-line (CLI) and graphical interface (GUI) usage modes.

[0129] 4. Cross-platform support: Developed based on Python and PySide6, it can run on Windows, Linux, and macOS.

[0130] 5. Open source code: Facilitates academic researchers to verify algorithms, perform custom development, and conduct secondary integration.

[0131] Example 2: This example provides a computer system, which can be a server or a terminal, and its internal structure diagram can be as follows. Figure 5 As shown, the computer system includes a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides the environment for the operating system and computer programs stored in the non-volatile storage media. The database stores forced oscillation samples and sub / supersynchronous oscillation samples. The I / O interfaces are used for information exchange between the processor and external devices. The communication interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements the aforementioned method for rapid prediction and identification of the dominant frequency of sub / supersynchronous oscillations in new energy power systems based on transfer learning.

[0132] Those skilled in the art will understand that Figure 5 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer system to which the present application is applied. A specific computer system may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0133] 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, and when executed, it can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM).

[0134] The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0135] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0136] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for inverting and analyzing the stress field of borehole fractures based on the right dihedral angle method, characterized in that, The method includes: The fault data of borehole fractures are loaded in batches using a GUI integrated interface. For each fault data point, the normal vector and slip vector of the fault plane are calculated, and the normal vector and slip vector of the fault plane are converted into direction cosines in the NED coordinate system. The fault data includes fault orientation and slicken orientation. The GUI integrated interface supports loading data formats including at least any one of CSV, TXT, and Excel. For any candidate principal stress direction in the borehole fracture stress field space, the fault region is divided using the right dihedral angle method based on the sliding vector and direction cosine of the fault plane; the fault region includes: compression zone and tension zone; By employing a two-stage coarse-fine mesh search strategy, the optimal principal stress directions in the borehole fracture stress field space are determined. Matching rate with principal stress axes Specifically, this includes: in the coarse search phase, generating a coarse test mesh with a first preset angle step size, determining the optimal region, and calculating the principal stress axis matching rate. In the fine search phase, the optimal region is scanned at a second preset angle to determine the optimal principal stress direction. The principal stress axis matching rate Used to characterize the percentage of fault data falling into the compression zone out of the total fault data; In the direction of the optimal principal stress Searching for the direction of minimum principal stress in a vertical plane For each candidate principal stress direction in the plane, calculate the bi-stress axis matching rate P2, and select the candidate direction with the largest bi-stress axis matching rate as the minimum principal stress direction. The direction of the intermediate principal stress is determined according to the right-hand rule. The dual stress axis matching ratio P2 is used to characterize the optimal principal stress direction. Located in the compression zone and in the direction of minimum principal stress The percentage of fault data located in extensional zones out of the total fault data; Based on principal stress axis matching rate The overall matching probability is calculated by multiplying the product of the matching rate P2 and the bi-stress axis matching rate. And will combine the matching probability With the direction of optimal principal stress , direction of intermediate principal stress direction of minimum principal stress , as the output of the inversion result; The inversion results are visualized graphically using a GUI integrated interface, and a stereographic projection map is output. The stereographic projection map is a projection map after superimposing the fault striation projection layer and the stress field P-value thermal layer.

2. The borehole fracture stress field inversion analysis method based on the right dihedral angle method according to claim 1, characterized in that, After visualizing the inversion results graphically using a GUI integrated interface and outputting the stereographic projection map, the following is also included: When the stereographic projection map shows two high-value centers with a separation degree greater than the separation threshold, the dataset composed of fault data is split using the selection function or data filter of the GUI integrated interface, and the pre-existing tectonic period and the late tectonic period are identified after inversion.

3. The borehole fracture stress field inversion analysis method based on the right dihedral angle method according to claim 1, characterized in that, The GUI integrated interface is used to batch load fault data of borehole fractures. For each fault data point, the normal vector and slip vector of the fault plane are calculated, and the normal vector and slip vector of the fault plane are converted into direction cosines in the NED coordinate system. Specifically, this includes: Import fault data of borehole fractures in batches at once using the file selector or drag-and-drop operation in the GUI integrated interface, and automatically classify and match the fault data of borehole fractures. For each fault data point, the normal vector of the fault plane is calculated based on the fault attitude, and the slip vector of the fault plane is calculated based on the slick attitude. Calculate the auxiliary vector perpendicular to the striation within the fault plane based on the normal vector and the slip vector of the fault plane, and output it as the direction cosine in the NED coordinate system.

4. The borehole fracture stress field inversion analysis method based on the right dihedral angle method according to claim 3, characterized in that, The formula for calculating the auxiliary direction perpendicular to the striation within the fracture surface is as follows: ； In the formula, For fault data The corresponding auxiliary vector perpendicular to the striation within the fault plane; For fault data The normal vector of the corresponding fault plane; For fault data The slip vector of the corresponding fault plane.

5. The borehole fracture stress field inversion analysis method based on the right dihedral angle method according to claim 1, characterized in that, For any candidate principal stress direction in the borehole fracture stress field space, the fault region is divided using the right dihedral angle method based on the slip vector and direction cosine of the fault plane, specifically including: For any candidate principal stress direction in the borehole fracture stress field space, the sliding vector projection scalar is calculated based on the dot product of the candidate principal stress direction and the sliding vector of the fault plane. The auxiliary vector projection scalar is obtained by calculating the dot product of the candidate principal stress direction and the direction cosine. Determine if the product of the sliding vector projection scalar and the auxiliary vector projection scalar is greater than 0. If it is, the candidate principal stress direction is located in the compression zone of the fault corresponding to the current fault data; otherwise, the candidate principal stress direction is located in the tension zone of the fault corresponding to the current fault data.

6. The borehole fracture stress field inversion analysis method based on the right dihedral angle method according to claim 1, characterized in that, The inversion results are visualized graphically using a GUI integrated interface, and a stereographic projection map is output, specifically including: The optimal principal stress direction is displayed using a GUI integrated interface with varying background color shades. , direction of intermediate principal stress and the direction of minimum principal stress probability density distribution and overall matching probability Simultaneously, the fault poles and striation symbols are superimposed and displayed, and the stress mechanism of the region is shown.

7. The borehole fracture stress field inversion analysis method based on the right dihedral angle method according to claim 1, characterized in that, The GUI integrated interface is based on the MVC architecture developed in Python.

8. The borehole fracture stress field inversion analysis method based on the right dihedral angle method according to claim 1, characterized in that, The first preset angle step size is 10°.

9. The borehole fracture stress field inversion analysis method based on the right dihedral angle method according to claim 1, characterized in that, The second preset angle step size is 2°.

10. A computer system, comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the computer program to implement the borehole fracture stress field inversion analysis method based on the right dihedral angle method as described in any one of claims 1-9.

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