Fracture network three-dimensional reconstruction and connectivity evaluation method and system based on Monte Carlo simulation

Abstract

The invention discloses a fracture network three-dimensional reconstruction and connectivity evaluation method and system based on Monte Carlo simulation, and belongs to the technical field of geotechnical engineering geological exploration and digital rock mass modeling. The method comprises the following steps: firstly, acquiring a two-dimensional fracture image of a drill hole, extracting geometric parameters, and acquiring three-dimensional plane initial parameters through a dimension conversion model; introducing Monte Carlo simulation, extending the deterministic plane model into a probability distribution model, and generating a large number of plane instances; calculating statistical characteristics of distances and included angles between fracture planes, and constructing a connectivity probability mapping function to evaluate a comprehensive connectivity probability; and finally, generating a global uncertainty cloud picture based on analysis results of all fracture pairs to identify a high-uncertainty region, and proposing an optimization and supplementation drilling scheme according to the high-uncertainty region. According to the method, the fracture network is transformed from deterministic reconstruction to probabilistic evaluation, connectivity can be quantified, uncertainty can be visualized, and a scientific basis is provided for engineering exploration decision making.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering geological exploration and digital rock mass modeling technology, and in particular relates to a method and system for three-dimensional reconstruction and connectivity assessment of fracture networks based on Monte Carlo simulation. Background Technology

[0002] The fracture network structure within a rock mass is a key factor affecting its stability, permeability, and engineering safety. In practical engineering scenarios such as underground coal mining, slope stability analysis, and groundwater seepage assessment, accurately understanding the three-dimensional spatial distribution and interconnections of fractures within the rock mass is crucial for disaster early warning and engineering decision-making. Currently, engineering practice primarily relies on borehole imaging technologies such as borehole television and optical imaging to obtain geological information. However, these technologies can only provide one-dimensional traces or two-dimensional unfolded images of the intersection of fractures and the borehole wall. Based on this limited local information, inferring the complete planar morphology and connectivity of fractures in three-dimensional space presents a significant "dimensionality-upgrading uncertainty" problem. To address this issue, existing technologies typically employ deterministic models, such as the least squares method, to perform three-dimensional planar fitting on the data to reconstruct the fracture network. While this method is direct, its inherent limitations are readily apparent in practical applications: it completely ignores unavoidable noise in the measurement data, errors generated during the planar fitting process itself, and the influence of the actual roughness of the rock mass surface. These factors collectively lead to insufficient reliability of the reconstructed 3D fracture network model. The model results are merely a deterministic and idealized geometric expression, failing to reflect its inherent uncertainty. Therefore, the binary "yes" or "no" judgments made by such models regarding the connectivity of fractures are often severely out of touch with complex engineering realities, lacking probabilistic assessments and leaving risk assessment and subsequent decision-making without a solid quantitative foundation. Furthermore, existing methods, after initial modeling, struggle to systematically identify areas with the highest cognitive uncertainty due to data scarcity. This results in a lack of a scientific and quantitative decision-making framework when optimizing subsequent exploration plans or deploying supplementary boreholes to obtain maximum information increments. Decisions often rely on engineers' experience, leading to inefficiency and a lack of specificity, failing to effectively reduce the global cognitive uncertainty of the rock mass structure across the entire engineering area. Therefore, the engineering field urgently needs a rock fracture network analysis method that can systematically quantify reconstruction uncertainty, probabilistically assess connectivity, and scientifically guide exploration optimization. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a method and system for three-dimensional reconstruction and connectivity assessment of fracture networks based on Monte Carlo simulation. This method transforms fracture networks from deterministic reconstruction to probabilistic assessment, quantifies connectivity, and visualizes uncertainties, providing a scientific basis for engineering exploration decisions.

[0004] To achieve the above objectives, this invention provides a method for three-dimensional reconstruction and connectivity evaluation of fracture networks based on Monte Carlo simulation, comprising: Two-dimensional fracture unfolding images of multiple boreholes are obtained, and two-dimensional geometric characterization parameters of each fracture are extracted; Based on the dimension transformation model, the two-dimensional geometric representation parameters of the crack are transformed into the initial parameters of the plane in three-dimensional space; Monte Carlo random sampling is performed on the three-dimensional parameters of each fracture plane to generate several plane instances that conform to the probability distribution; For any two crack plane instances, based on Monte Carlo simulation samples, calculate the statistical characteristics of the spatial distance and the angle between the normal vectors; Construct a connectivity probability mapping function and calculate the comprehensive connectivity probability between two fracture planes based on statistical characteristics; The connectivity of all fracture pairs is analyzed based on the comprehensive connectivity probability, generating a global uncertainty cloud map and identifying high uncertainty regions. Based on the global uncertainty cloud map, an optimal supplementary borehole layout scheme is proposed in the high uncertainty region.

[0005] Optionally, according to the dimensional transformation model, the transformation of the two-dimensional geometric representation parameters of the crack into the initial parameters of the plane in three-dimensional space includes: establishing a mapping relationship between the two-dimensional image coordinate system and the three-dimensional spatial coordinate system; using a three-dimensional plane fitting method based on the least squares method to fit the discrete point set of the two-dimensional crack curve into a three-dimensional plane equation, and using the fitted three-dimensional plane parameters as the initial parameters of the plane.

[0006] Optionally, generating several plane instances conforming to the probability distribution includes: using the initial parameters of the plane as the mean of a normal distribution; calculating the standard deviation of the normal distribution based on the uncertainty index of the crack; and independently and randomly sampling the normal vector parameters of each crack plane based on the mean and standard deviation to generate several plane instances conforming to the probability distribution.

[0007] Optionally, the uncertainty index of the fracture includes at least one of the following: rock joint roughness coefficient and two-dimensional plane fitting error.

[0008] Optionally, calculating the overall connectivity probability between two fracture planes based on statistical characteristics includes: determining confidence intervals based on Monte Carlo results of distance and angle for all fracture pairs; calculating connectivity probability mapping functions based on distance and angle respectively; and taking the average of the results calculated by the connectivity probability mapping functions based on distance and angle as the overall connectivity probability.

[0009] Optionally, generating a global uncertainty cloud map includes: projecting the center of each borehole opening onto a two-dimensional plane; traversing all borehole pair combinations, normalizing the angular standard deviation obtained from the fracture connectivity analysis between each pair of boreholes, and using it as the uncertainty quantification value of the center point of the connecting line between the borehole pairs; and using all borehole points and connecting line center points as observation samples, constructing a global uncertainty cloud map using an interpolation method.

[0010] On the other hand, to achieve the above objectives, the present invention also provides a three-dimensional reconstruction and connectivity evaluation system for fracture networks based on Monte Carlo simulation, comprising: The data acquisition and processing module is used to acquire two-dimensional fracture unfolding images of multiple boreholes and extract the two-dimensional geometric characterization parameters of each fracture. The 3D initial reconstruction module is used to transform the two-dimensional geometric representation parameters of the crack into planar initial parameters in three-dimensional space according to the dimension transformation model. The probabilistic simulation module is used to perform Monte Carlo random sampling of the three-dimensional parameters of each fracture plane to generate several plane instances that conform to a probability distribution. The geometric relationship analysis module is used to calculate the statistical characteristics of the spatial distance and the angle between the normal vectors for any two crack plane instances based on Monte Carlo simulation samples. The connectivity assessment module is used to construct a connectivity probability mapping function and calculate the comprehensive connectivity probability between two fracture planes based on statistical characteristics. The uncertainty visualization module is used to analyze the connectivity of all fracture pairs based on the comprehensive connectivity probability, generate a global uncertainty cloud map, and identify high uncertainty regions. The exploration optimization module is used to propose the optimal supplementary borehole layout scheme in areas of high uncertainty based on a global uncertainty cloud map.

[0011] Technical Effects of this Invention: This invention discloses a method and system for three-dimensional reconstruction and connectivity assessment of fracture networks based on Monte Carlo simulation. By establishing a universal two-dimensional to three-dimensional coordinate transformation model, it provides initial expected values ​​for Monte Carlo simulation, thus adapting to diverse borehole orientations in practical engineering. It innovatively introduces Monte Carlo simulation into rock fracture network analysis, describing the uncertainty of fracture planes through probability distribution. This transforms the three-dimensional reconstruction results from a single deterministic model into a set containing rich probabilistic information, significantly improving the model's reliability and robustness. By defining dual connectivity probability indices based on distance and normal angle and establishing a mapping function, it achieves quantitative and probabilistic assessment of fracture connectivity, overcoming the limitations of traditional binary judgments. The global uncertainty quantification model proposed in this invention can intuitively visualize the uncertainty distribution of the entire region, accurately identify high-uncertainty areas with scarce information, and provide a scientific and quantitative decision-making basis for optimizing subsequent exploration borehole layout schemes, thereby effectively reducing global cognitive uncertainty. By introducing a fracture uncertainty index to constrain the uncertainty of the normal vector parameters, the model can more reasonably reflect the true morphology of the rock mass structure and the impact of data quality, thereby improving the physical meaning and accuracy of the model. Attached Figure Description

[0012] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a flowchart illustrating a method for three-dimensional reconstruction and connectivity evaluation of fracture networks based on Monte Carlo simulation, according to an embodiment of the present invention. Figure 2 This is an example diagram showing the unfolded image of a borehole fracture according to an embodiment of the present invention; Figure 3 This is an example diagram of the three-dimensional planar orientation after conversion according to an embodiment of the present invention; Figure 4 These are example images of the 10 pairs of fractures with the highest angular connectivity probability generated in this embodiment of the invention; Figure 5 This is an example diagram of the 10 pairs of fractures with the highest distance connectivity probability generated in an embodiment of the present invention; Figure 6 These are example diagrams of the 10 pairs of fractures with the highest overall connectivity probability generated in this embodiment of the invention; Figure 7 The global uncertainty cloud map generated for embodiments of the present invention. Detailed Implementation

[0013] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0014] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0015] like Figure 1 As shown, this embodiment provides a method for three-dimensional reconstruction and connectivity evaluation of fracture networks based on Monte Carlo simulation, including: Two-dimensional fracture unfolding images of multiple boreholes are obtained, and two-dimensional geometric characterization parameters of each fracture are extracted; Based on the dimension transformation model, the two-dimensional geometric representation parameters of the crack are transformed into the initial parameters of the plane in three-dimensional space; Monte Carlo random sampling is performed on the three-dimensional parameters of each fracture plane to generate several plane instances that conform to the probability distribution; For any two crack plane instances, based on Monte Carlo simulation samples, calculate the statistical characteristics of the spatial distance and the angle between the normal vectors; Construct a connectivity probability mapping function and calculate the comprehensive connectivity probability between two fracture planes based on statistical characteristics; The connectivity of all fracture pairs is analyzed based on the comprehensive connectivity probability, generating a global uncertainty cloud map and identifying high uncertainty regions. Based on the global uncertainty cloud map, an optimal supplementary borehole layout scheme is proposed in the high uncertainty region.

[0016] Furthermore, according to the dimension transformation model, the transformation of the two-dimensional geometric representation parameters of the crack into the initial parameters of the plane in three-dimensional space includes: establishing the mapping relationship between the two-dimensional image coordinate system and the three-dimensional spatial coordinate system; using a three-dimensional plane fitting method based on the least squares method to fit the discrete point set of the two-dimensional crack curve into a three-dimensional plane equation, and using the fitted three-dimensional plane parameters as the initial parameters of the plane.

[0017] Specifically, the implementation process of this embodiment includes: The dimensional transformation model employs a three-dimensional plane fitting method based on the least squares approach to discretize the fracture curve set on the borehole cylindrical surface. Fit to three-dimensional plane equation , where vector It is the normal vector of the plane.

[0018] Dimensional transformation model: Two-dimensional expression for a crack image: ; Where the horizontal axis The vertical axis represents the circumferential development distance of the borehole (unit: mm). Indicates the axial depth of the borehole (unit: mm). , R Where is the borehole radius, L This represents the drilling depth.

[0019] For each sampling point x i According to the arc length formula: ; Find the corresponding central angle measured from the baseline: ; Then for each sampling point ( x i , y i ), its three-dimensional coordinates ( X i , Y i , Z i )for: ; ; ; in, X’ The x-coordinate of the borehole opening is... Y’ The vertical coordinate is the coordinate of the borehole opening.

[0020] Based on the coordinates of discrete points on the curve of the crack plane on the cylindrical surface, a least squares method is used to fit a plane, that is, to fit a plane such that the distance from all discrete points to this plane is minimized. For ease of writing, ( X , Y , Z ) is denoted as ( x , y , z Let the equation of the plane be: ; Then vector ( A , B , C Let be the normal vector of the plane. For each ( x i , y i , z i The distance from the point to the plane is: ; The objective function of the least squares method is: ; In the process of fitting a plane based on the least squares method, three-dimensional reconstruction can be achieved by solving the plane equation.

[0021] Furthermore, generating several plane instances conforming to the probability distribution includes: using the initial parameters of the plane as the mean of a normal distribution; calculating the standard deviation of the normal distribution based on the uncertainty index of the crack; and independently and randomly sampling the normal vector parameters of each crack plane based on the mean and standard deviation to generate several plane instances conforming to the probability distribution.

[0022] Specifically, the implementation process of this embodiment includes: The obtained three-dimensional plane initial parameters As the mean of the normal distribution; The standard deviation σ of this normal distribution is constrained by the uncertainty index of the crack, and the calculation formula is: ; in, The basic error for smooth cracks, This represents the value of the uncertainty index for the current crack. and These are the maximum and minimum values ​​among all measured values ​​of crack uncertainty indices. This is a parameter that can be adjusted based on the specific value of the uncertainty indicator; Based on the mean and standard deviation, the normal vector parameters for each fracture plane are... Perform independent random sampling to generate several planar instances that conform to the probability distribution.

[0023] Furthermore, the uncertainty index of the fracture includes at least one of the following: rock joint roughness coefficient and two-dimensional plane fitting error.

[0024] Furthermore, for any two crack planes and In each Monte Carlo sampling middle: Calculate the angle between the normal vectors of the two planes. ; Calculate the minimum spatial distance between two planes ; After completing all n samplings, calculate the sample mean of the included angle and distance. , and sample standard deviation , .

[0025] Furthermore, the calculation of the comprehensive connectivity probability between two fracture planes based on statistical characteristics includes: determining confidence intervals based on Monte Carlo results of the distance and angle of all fracture pairs; calculating connectivity probability mapping functions based on distance and angle respectively; and taking the average of the results calculated by the connectivity probability mapping functions based on distance and angle as the comprehensive connectivity probability.

[0026] Specifically, the implementation process of this embodiment includes: Based on the Monte Carlo results for the distance and included angle of all fracture pairs, their 95% confidence intervals were determined. and ; For the distance metric, the connectivity probability mapping function is defined as: ; in, When the value exceeds the range, the probability is truncated to 0 or 1. For the angle index, the connectivity probability mapping function is defined as: ; in, When the value exceeds the range, the probability is truncated to 0 or 1. Overall connectivity probability This is the average of the distance probability and the angle probability. .

[0027] Furthermore, generating a global uncertainty cloud map includes: projecting the center of each borehole opening onto a two-dimensional plane; traversing all borehole pair combinations, normalizing the angular standard deviation obtained from the fracture connectivity analysis between each pair of boreholes, and using it as the uncertainty quantification value of the center point of the connecting line between the borehole pairs; and using all borehole points and connecting line center points as observation samples, constructing a global uncertainty cloud map using interpolation.

[0028] This embodiment also provides a three-dimensional reconstruction and connectivity evaluation system for fracture networks based on Monte Carlo simulation, including: The data acquisition and processing module is used to acquire two-dimensional fracture unfolding images of multiple boreholes and extract the two-dimensional geometric characterization parameters of each fracture. The 3D initial reconstruction module is used to transform the two-dimensional geometric representation parameters of the crack into planar initial parameters in three-dimensional space according to the dimension transformation model. The probabilistic simulation module is used to perform Monte Carlo random sampling of the three-dimensional parameters of each fracture plane to generate several plane instances that conform to a probability distribution. The geometric relationship analysis module is used to calculate the statistical characteristics of the spatial distance and the angle between the normal vectors for any two crack plane instances based on Monte Carlo simulation samples. The connectivity assessment module is used to construct a connectivity probability mapping function and calculate the comprehensive connectivity probability between two fracture planes based on statistical characteristics. The uncertainty visualization module is used to analyze the connectivity of all fracture pairs based on the comprehensive connectivity probability, generate a global uncertainty cloud map, and identify high uncertainty regions. The exploration optimization module is used to propose the optimal supplementary borehole layout scheme in areas of high uncertainty based on a global uncertainty cloud map.

[0029] An electronic device, characterized in that the electronic device comprises: a processor and a memory storing computer program instructions; When the processor executes the computer program instructions, it implements the method for three-dimensional reconstruction and connectivity evaluation of fracture networks based on Monte Carlo simulation.

[0030] A computer storage medium, characterized in that the computer storage medium stores computer program instructions, which, when executed by a processor, implement the method for three-dimensional reconstruction and connectivity evaluation of fracture networks based on Monte Carlo simulation.

[0031] An application example of this invention is as follows: Taking the analysis of borehole fractures in underground coal mining as an example, this method was applied to analyze fracture images of six exploration boreholes, specifically including: Step 1: Obtain the 2D unfolded images of the 6 boreholes.

[0032] Step 2: Based on the preprocessed image, extract the characterization parameters of each fracture and use a dimensionality transformation model to convert the two-dimensional image into a three-dimensional image. For borehole fractures, a borehole unfolding diagram is shown below. Figure 2 As shown, image processing algorithms were used to identify fractures within each borehole. The borehole unfolding diagram corresponds to the NESEN azimuth sequence (North-East-South-East-North) from left to right. The horizontal axis x represents the unfolding distance along the borehole circumference, and the vertical axis... y This represents the depth along the borehole axis. In the transformed 3D coordinate system, the positive X-axis is east, the positive Y-axis is north, and the positive Z-axis is vertically upward. For example... Figure 3 As shown. Extract the two-dimensional sine curve characterization parameters (amplitude) of the borehole. ,cycle Phase Centerline position The JRC value was then determined. Subsequently, through least-squares fitting, each crack was transformed into a plane equation in three-dimensional space with a defined direction, and its initial normal vector was obtained. And spatial location.

[0033] Step 3: Generate a large number of planar instances conforming to the probability distribution through Monte Carlo simulation. For each crack in Table 1, calculate the standard deviation of the normal vector parameters using the formula based on its JRC mean and the set JRC extreme values. Then proceed with... n =1000 Monte Carlo random samplings to generate 10,000 possible three-dimensional plane instances for each crack.

[0034] Table 1

[0035] Step 4: Calculate the statistical characteristics of the spatial distance and the angle between the normal vectors of the two planes, and calculate the connectivity probability between the planes based on these characteristics. Perform pairwise combinations for all fractures. For each pair of fractures (e.g., fracture 11 in borehole 2 and fracture 1 in borehole 4), calculate the angle between their normal vectors in each of the 10,000 samplings. and spatial distance Statistics show that... Based on the statistical results of all fracture pairs, the 95% confidence intervals for distance and angle were determined as follows: and Substituting the values ​​into the probability mapping function and using the formula, the overall connectivity probability of the fracture pair is calculated to be 0.607.

[0036] Step 5: After calculating all fracture pairs, sort them by angle, distance, and overall connectivity probability to obtain the top ten fracture pairs with the highest connectivity probability, and then perform 3D visualization, as shown below. Figures 4-6 As shown.

[0037] Step Six: Generate an Uncertainty Cloud Map. Normalize the angular standard deviations obtained from the connectivity analysis of all fracture pairs and assign them to the center points of the corresponding borehole pair connections. Use interpolation to generate an uncertainty cloud map. Figure 7 The global uncertainty cloud map shown. Figure 7 The data clearly shows that the areas near coordinates (1000,2000), (2000,2000), and (2000,1500) are areas of high uncertainty (in red).

[0038] Step 7: Based on the uncertainty cloud map, it is recommended to deploy supplementary boreholes in the center of the three high uncertainty areas mentioned above to obtain new information to the greatest extent and reduce the uncertainty of understanding the entire rock mass fracture network.

[0039] This invention discloses a method and system for three-dimensional reconstruction and connectivity assessment of fracture networks based on Monte Carlo simulation. By establishing a general two-dimensional to three-dimensional coordinate transformation model, it provides initial expected values ​​for Monte Carlo simulation, thus adapting to diverse borehole orientations in practical engineering. It innovatively introduces Monte Carlo simulation into rock fracture network analysis, describing the uncertainty of fracture planes through probability distributions. This transforms the three-dimensional reconstruction results from a single deterministic model into a set containing rich probabilistic information, significantly improving the model's reliability and robustness. By defining dual connectivity probability indices based on distance and normal angle and establishing a mapping function, it achieves quantitative and probabilistic assessment of fracture connectivity, overcoming the limitations of traditional binary judgments. The global uncertainty quantification model proposed in this invention can intuitively visualize the uncertainty distribution of the entire region, accurately identify high-uncertainty areas with scarce information, and provide a scientific and quantitative decision-making basis for optimizing subsequent exploration borehole layout schemes, thereby effectively reducing global cognitive uncertainty. By introducing fracture uncertainty indices to constrain the uncertainty of normal vector parameters, the model can more reasonably reflect the true morphology of rock mass structural surfaces and the influence of data quality, improving the model's physical meaning and accuracy.

[0040] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for three-dimensional reconstruction and connectivity evaluation of fracture networks based on Monte Carlo simulation, characterized in that, include: Two-dimensional fracture unfolding images of multiple boreholes are obtained, and two-dimensional geometric characterization parameters of each fracture are extracted; Based on the dimension transformation model, the two-dimensional geometric representation parameters of the crack are transformed into the initial parameters of the plane in three-dimensional space; Monte Carlo random sampling is performed on the three-dimensional parameters of each fracture plane to generate several plane instances that conform to the probability distribution; For any two crack plane instances, based on Monte Carlo simulation samples, calculate the statistical characteristics of the spatial distance and the angle between the normal vectors; Construct a connectivity probability mapping function and calculate the comprehensive connectivity probability between two fracture planes based on statistical characteristics; The connectivity of all fracture pairs is analyzed based on the comprehensive connectivity probability, generating a global uncertainty cloud map and identifying high uncertainty regions. Based on the global uncertainty cloud map, an optimal supplementary borehole layout scheme is proposed in the high uncertainty region.

2. The method for three-dimensional reconstruction and connectivity evaluation of fracture networks based on Monte Carlo simulation as described in claim 1, characterized in that, According to the dimensional transformation model, the transformation of the two-dimensional geometric representation parameters of the crack into the initial parameters of the plane in three-dimensional space includes: establishing the mapping relationship between the two-dimensional image coordinate system and the three-dimensional space coordinate system; using a three-dimensional plane fitting method based on the least squares method to fit the discrete point set of the two-dimensional crack curve into a three-dimensional plane equation, and using the fitted three-dimensional plane parameters as the initial parameters of the plane.

3. The method for three-dimensional reconstruction and connectivity evaluation of fracture networks based on Monte Carlo simulation as described in claim 1, characterized in that, Generating several plane instances that conform to the probability distribution includes: using the initial parameters of the plane as the mean of a normal distribution; calculating the standard deviation of the normal distribution based on the uncertainty index of the crack; and generating several plane instances that conform to the probability distribution by independently and randomly sampling the normal vector parameters of each crack plane based on the mean and standard deviation.

4. The method for three-dimensional reconstruction and connectivity evaluation of fracture networks based on Monte Carlo simulation as described in claim 3, characterized in that, The uncertainty index of the fracture includes at least one of the following: rock joint roughness coefficient and two-dimensional plane fitting error.

5. The method for three-dimensional reconstruction and connectivity evaluation of fracture networks based on Monte Carlo simulation as described in claim 1, characterized in that, The calculation of the overall connectivity probability between two fracture planes based on statistical characteristics includes: determining confidence intervals based on Monte Carlo results of distance and angle for all fracture pairs; calculating connectivity probability mapping functions based on distance and angle respectively; and taking the average of the results calculated by the connectivity probability mapping functions based on distance and angle as the overall connectivity probability.

6. The method for three-dimensional reconstruction and connectivity evaluation of fracture networks based on Monte Carlo simulation as described in claim 1, characterized in that, The process of generating a global uncertainty cloud map includes: projecting the center of each borehole opening onto a two-dimensional plane; traversing all borehole pair combinations and normalizing the angular standard deviation obtained from the fracture connectivity analysis between each pair of boreholes as the uncertainty quantification value of the center point of the connecting line between the borehole pairs; and using all borehole points and the center point of the connecting line as observation samples and constructing a global uncertainty cloud map using an interpolation method.

7. A three-dimensional reconstruction and connectivity evaluation system for fracture networks based on Monte Carlo simulation, characterized in that, The system is used to implement the Monte Carlo simulation-based three-dimensional reconstruction and connectivity assessment method for fracture networks as described in any one of claims 1-6, the system comprising: The data acquisition and processing module is used to acquire two-dimensional fracture unfolding images of multiple boreholes and extract the two-dimensional geometric characterization parameters of each fracture. The 3D initial reconstruction module is used to transform the two-dimensional geometric representation parameters of the crack into planar initial parameters in three-dimensional space according to the dimension transformation model. The probabilistic simulation module is used to perform Monte Carlo random sampling of the three-dimensional parameters of each fracture plane to generate several plane instances that conform to a probability distribution. The geometric relationship analysis module is used to calculate the statistical characteristics of the spatial distance and the angle between the normal vectors for any two crack plane instances based on Monte Carlo simulation samples. The connectivity assessment module is used to construct a connectivity probability mapping function and calculate the comprehensive connectivity probability between two fracture planes based on statistical characteristics. The uncertainty visualization module is used to analyze the connectivity of all fracture pairs based on the comprehensive connectivity probability, generate a global uncertainty cloud map, and identify high uncertainty regions. The exploration optimization module is used to propose the optimal supplementary borehole layout scheme in areas of high uncertainty based on a global uncertainty cloud map.

8. An electronic device, characterized in that, The electronic device includes: a processor and a memory storing computer program instructions; When the processor executes the computer program instructions, it implements the method for three-dimensional reconstruction and connectivity evaluation of fracture networks based on Monte Carlo simulation as described in any one of claims 1-6.

9. A computer storage medium, characterized in that, The computer storage medium stores computer program instructions, which, when executed by a processor, implement the method for three-dimensional reconstruction and connectivity evaluation of fracture networks based on Monte Carlo simulation as described in any one of claims 1-6.

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