Method for evaluating geological stability of shale gas development

Abstract

The invention discloses a shale gas development geological stability evaluation method, which comprises the following steps of: acquiring geological structure data and earthquake monitoring data of a shale gas development area, dividing a space map of the shale gas development area into a plurality of grid units, and determining a minimum complete earthquake magnitude Mc; calculating a fault activation potential coefficient FAP in the grid unit based on a corrected Mohr-Coulomb fault activation criterion, and calculating a geological structure evaluation index TRI of the grid unit; carrying out fusion on earthquake b values in the earthquake monitoring data, constructing an ETAS model to calculate an external triggering rate of engineering activities, and calculating an earthquake activity disturbance index SDI of a grid unit; and calculating a geological stability index by using the geological structure evaluation index TRI and the seismic activity disturbance index SDI, and evaluating the geological stability of the shale gas development area. According to the invention, the geological stability dynamic tracking evaluation of the shale gas development full period can be realized.

Description

Technical Field

[0001] This invention relates to the field of geological safety research in shale gas development, and specifically to a method for evaluating the geological stability of shale gas development. Background Technology

[0002] Hydraulic fracturing operations during shale gas development inject high-pressure fluids into the formation, which can easily trigger geological stability problems such as increased pore pressure, fault activation, and induced earthquakes. Earthquakes of magnitude ML3.0 or higher related to hydraulic fracturing in shale gas development areas can cause casualties and property damage, severely hindering the safe and efficient development of shale gas. Therefore, geological stability assessment is particularly important during shale gas development. Currently, the relevant technologies for geological stability assessment in shale gas development areas have the following shortcomings: 1. The evaluation system is too narrow in scope. Existing technologies mostly focus on the static assessment of the activation risk of a single fault, without systematically integrating the multi-dimensional coupling effects of regional geological tectonic background, dynamic evolution of seismic activity, and intensity of engineering development disturbances. This makes it impossible to comprehensively characterize the geological stability changes throughout the entire shale gas development cycle. 2. Insufficient ability to identify and quantify induced earthquakes. Existing technologies are unable to accurately separate natural tectonic earthquakes from engineering-induced earthquakes, and cannot quantify the degree of disturbance to regional geological stability caused by engineering development activities, resulting in evaluation results that cannot effectively guide on-site construction management. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for evaluating the geological stability of shale gas development. By constructing an evaluation system that couples geological structure and seismic activity, it enables a quantitative, refined, and dynamic evaluation of the geological stability of shale gas development areas.

[0004] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: A method for evaluating the geological stability of shale gas development is provided, comprising: Step S1: Collect geological structure data and seismic monitoring data of the shale gas development area, divide the spatial zoning map of the shale gas development area into several grid units, and determine the minimum complete magnitude based on the seismic monitoring data. Mc ; Step S2: Using the geological structure data within the grid cell, calculate the fault activation potential coefficient (FAP) within the grid cell based on the modified Mohr-Coulomb fault activation criterion, and objectively assign weights to the geological structure data within the grid cell using principal component analysis (PCA) to calculate the geological structure evaluation index (TRI) of the grid cell. Step S3: Fuse the earthquake b-values ​​in the earthquake monitoring data to obtain the standardized coefficients of the earthquake b-values, construct the ETAS model to calculate the external triggering rate of engineering activities, calculate the standardized coefficients of the external triggering rate, and calculate the seismic activity disturbance index SDI of the grid cells based on the standardized coefficients of the earthquake b-values ​​and the standardized coefficients of the external triggering rate. Step S4: Calculate the geological stability index using the Geological Structure Evaluation Index (TRI) and the Seismic Activity Disturbance Index (SDI). To assess the geological stability of shale gas development areas.

[0005] Further, step S2 includes: Step S21: Using geological structural data within the grid cells, calculate the fault activation potential coefficient (FAP) within the grid cells based on the modified Mohr-Coulomb fault activation criterion; ; in, The shear stress on the fracture surface. The static internal friction coefficient of the fault plane is given. The normal stress on the fault plane, The pore fluid pressure at the fault plane, The cohesion at the fracture surface, This is a function representing the value of the fault dip angle influence coefficient. This is a function representing the value of the fault extension length influence coefficient. This is a function for determining the value of the fault displacement influence coefficient. The fault dip angle; Step S22: Determine the fault dip angle Length of extension L and vertical displacement H Standardization was performed to obtain the fault dip coefficient. Elongation coefficient and vertical displacement coefficient ; , , ; in, These represent the maximum and minimum fault dip angles in the shale gas development area, respectively. These represent the maximum and minimum fault extension lengths in shale gas development areas, respectively. These represent the maximum and minimum vertical fault displacement values ​​in the shale gas development area, respectively. Step S23: Based on the fault dip coefficient of each grid cell Elongation coefficient and vertical displacement coefficient Constructing the fault parameter normalization matrix ; ; in, m The number of grid cells, The first m Fault dip coefficient of each grid cell Elongation coefficient and vertical displacement coefficient ; Step S24: Standardize the matrix based on fault parameters Calculate the correlation coefficient matrix ; ; Step S25: Solve the characteristic equation The characteristic values ​​of fault dip angle, extension length and vertical displacement are obtained. , It is a unit vector; Step S26: Based on eigenvalues Objective weights for calculating fault dip angle, extension length, and vertical displacement. ; ; Step S27: Utilize objective weights and fault dip coefficient Elongation coefficient and vertical displacement coefficient Calculate the Geological Structure Evaluation Index (TRI) for grid cells; .

[0006] Furthermore, the function for determining the influence coefficient of fault dip angle. Specifically: ; The function for determining the influence coefficient of fault extension length. Specifically: ; The function for determining the influence coefficient of fault displacement. Specifically: ;in, H This represents the vertical displacement of the fault.

[0007] Further, step S3 includes: Step S31: Based on the minimum complete magnitude Mc Calculate the b-value of the earthquake; ; in, eIt is a natural constant. For earthquakes with a magnitude greater than or equal to the minimum complete magnitude Mc The time-averaged magnitude of earthquakes; Step S32: Standardize the seismic b-values ​​to obtain the standardized coefficients of the seismic b-values ​​within the grid cells. ; ; Step S33: Construct the ETAS model to calculate the earthquake occurrence rate ; ; in, t For time, Background earthquake incidence rate, k This is the aftershock induction capacity coefficient. For the first i The time of occurrence of an earthquake event c The aftershock decay time constant. p The aftershock attenuation index. This is the coefficient representing the influence of magnitude on the aftershock rate. For the first i The magnitude of the earthquake event; Step S34: Based on earthquake occurrence rate Calculate the external triggering rate of engineering activities within the grid cell. ; ; Step S35: External triggering rate of the mesh cell The normalization process is performed to obtain the normalized coefficients of the external trigger rate of the grid cells. ; ; in, These represent the minimum and maximum trigger rates within and outside the shale gas development area, respectively. Step S36: Based on the standardized coefficients of the earthquake b-value Standardized coefficients of external trigger rate Calculate the seismic activity disturbance index (SDI) of the grid cells; ; in, These are the weighting coefficients for engineering activities and seismic activities, respectively.

[0008] Further, step S4 includes: Step S41: Set the threshold for the Geological Structure Evaluation Index (TRI) of the grid cells. Threshold of the Seismic Activity Disturbance Index (SDI) Calculate the geological stability index ; ; Step S42: Set the geological stability index threshold ;like If the geological stability of the shale gas development area corresponding to the grid unit is good, then the geological stability of the shale gas development area corresponding to the grid unit is determined to be poor; otherwise, the geological stability of the shale gas development area corresponding to the grid unit is determined to be good.

[0009] The beneficial effects of this invention are as follows: This invention breaks through the limitations of traditional single-fault evaluation, constructing an evaluation system coupled with "static geological structural background - dynamic seismic activity response." It simultaneously integrates three major fault activation mechanisms: fluid diffusion, porosity-elastic coupling, and fault creep, comprehensively covering the main controlling factors of geological stability in shale gas development. The completeness and accuracy of the evaluation results are significantly improved compared to traditional methods. This invention, through the coupling of seismic b-value fitting calculations and the ETAS model, accurately separates natural tectonic earthquakes from engineering-induced earthquakes, quantifies the degree of disturbance to seismic activity by engineering development activities, and overcomes the limitation of traditional methods in being unable to identify the dynamic impact of engineering activities on geological stability. It can achieve dynamic tracking and evaluation of geological stability throughout the entire shale gas development cycle. Attached Figure Description

[0010] Figure 1 A flowchart for evaluating the geological stability of shale gas development. Detailed Implementation

[0011] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0012] like Figure 1 As shown, a method for evaluating the geological stability of shale gas development includes: Step S1: Collect geological structure data and seismic monitoring data of the shale gas development area, divide the spatial zoning map of the shale gas development area into several grid units, and determine the minimum complete magnitude based on the seismic monitoring data. Mc ; In this embodiment, artificial blasting events and outliers are removed from the earthquake catalog data collected from earthquake monitoring data to complete earthquake relocation, and the minimum complete magnitude is determined based on the GR relationship using the maximum curvature method. Mc ; ; in, MThe magnitude of the earthquake. a The intercept of the GR relationship is the fitting value. b For the earthquake b-value, For earthquakes with a magnitude greater than or equal to M Cumulative earthquake frequency; Step S2: Using the geological structural data within the grid cells, calculate the fault activation potential coefficient (FAP) within the grid cells based on the modified Mohr-Coulomb fault activation criterion, and objectively weight the geological structural data within the grid cells using principal component analysis (PCA) to calculate the geological structural evaluation index (TRI) of the grid cells. Step S2 specifically includes: Step S21: Using geological structural data within the grid cells, calculate the fault activation potential coefficient (FAP) within the grid cells based on the modified Mohr-Coulomb fault activation criterion; ; in, The shear stress on the fracture surface. The static internal friction coefficient of the fault plane is given. The normal stress on the fault plane, The pore fluid pressure at the fault plane, The cohesion at the fracture surface, This is a function representing the value of the fault dip angle influence coefficient. This is a function representing the value of the fault extension length influence coefficient. This is a function for determining the value of the fault displacement influence coefficient. The fault dip angle; Function for determining the influence coefficient of fault dip angle Specifically: ; The function for determining the influence coefficient of fault extension length. Specifically: ; The function for determining the influence coefficient of fault displacement. Specifically: ;in, H The vertical displacement of the fault; The Fault Activation Potential Coefficient (FAP) quantifies the coupling relationship between the stress state, geometric properties, and mechanical parameters of a fault plane. It is a physical deduction process to determine whether a fault meets the critical slip condition under shale gas development (hydraulic fracturing) disturbance. The core logic is to transform the complex geomechanical problem of fault activation into quantifiable parameter calculations, ultimately using the FAP value to intuitively reflect the potential for a fault to transition from a "stable state" to a "slip state." Based on the "ratio of actual shear stress to critical shear strength of the fault plane," and by superimposing corrections for activation difficulty using fault geometric parameters (dip angle, length, and displacement), the FAP is finally obtained.

[0013] The ratio is used to quantify the difference between the current stress state of the fault plane and the critical activation state. It is essentially a direct application of the Mohr-Coulomb fracture criterion. A ratio of 1 indicates that the shear stress of the fault plane is exactly equal to the critical shear strength, and the fault is in a "critical activation state". Even a small external disturbance (such as an increase in the amount of hydraulic fluid injected) can trigger slip. A ratio > 1 indicates that the shear stress exceeds the critical shear strength, and the fault has met the activation conditions. Slip is likely to occur (natural earthquake or engineering-induced earthquake). A ratio < 1 indicates that the shear stress has not reached the critical strength, and the fault is in a stable state. External disturbances (such as high-pressure injection leading to an increase in shear stress) are required to approach the activation critical value.

[0014] This is a geometric correction term used to correct the limitations of "pure mechanical parameters"—the geometric characteristics of a fault can change the actual effect of "dynamic-resistance" interaction, and even with the same mechanical parameters, the activation potential of faults with different geometric characteristics will vary significantly.

[0015] Step S22: Determine the fault dip angle Length of extension L and vertical displacement H Standardization was performed to obtain the fault dip coefficient. Elongation coefficient and vertical displacement coefficient ; , , ; in, These represent the maximum and minimum fault dip angles in the shale gas development area, respectively. These represent the maximum and minimum fault extension lengths in shale gas development areas, respectively. These represent the maximum and minimum vertical fault displacement values ​​in the shale gas development area, respectively. Step S23: Based on the fault dip coefficient of each grid cell Elongation coefficient and vertical displacement coefficient Constructing the fault parameter normalization matrix ; ; in, m The number of grid cells, The first m Fault dip coefficient of each grid cell Elongation coefficient and vertical displacement coefficient ; Step S24: Standardize the matrix based on fault parameters Calculate the correlation coefficient matrix ; ; Step S25: Solve the characteristic equation The characteristic values ​​of fault dip angle, extension length and vertical displacement are obtained. , It is a unit vector; Step S26: Based on eigenvalues Objective weights for calculating fault dip angle, extension length, and vertical displacement. ; ; Step S27: Utilize objective weights and fault dip coefficient Elongation coefficient and vertical displacement coefficient Calculate the Geological Structure Evaluation Index (TRI) for grid cells; .

[0016] The Geological Structure Evaluation Index (TRI) ranges from 0 to 1. A TRI closer to 1 indicates a stronger adverse impact of geological structures on stability in the region where the grid unit is located, and a higher potential risk of fault activation. The core physical logic is that larger faults with dip angles in the easy-slip range (20°~40°), larger displacements, and lower shear strength of the fault plane (determined by internal friction coefficient and cohesion) are more likely to satisfy the Mohr-Coulomb fracturing criterion under the external disturbance of hydraulic fracturing during shale gas development, triggering fault slip and inducing earthquakes. Conversely, a TRI close to 0 indicates a weaker adverse impact of geological structures on stability in the region where the grid unit is located, and a lower potential risk of fault activation. The core physical logic is that smaller faults with dip angles deviating from the easy-slip range, smaller displacements, or inactive faults (such as those formed in the early to middle Pleistocene or earlier with no recent signs of activity) have higher shear strength of the fault plane, making it difficult to exceed the critical stress condition for fault activation even under hydraulic fracturing disturbances.

[0017] The spatial distribution of the Geological Structure Evaluation Index (TRI) in shale gas development areas directly reflects the spatial heterogeneity of regional geological structural risks. For example, high TRI values ​​are typically concentrated along large active faults, at fault intersections, or along anticline axes. These areas have concentrated tectonic stress and well-developed faults, making them key areas for geological risk control in shale gas development. In contrast, low TRI values ​​are mostly found in synclinal areas with gentle structures and underdeveloped faults, exhibiting better geological stability and allowing for conventional development operations.

[0018] The Geological Structure Evaluation Index (TRI) is essentially an "inherent risk base" provided by geological structures, while engineering disturbances in shale gas development (such as injection pressure and injection volume) are "external triggering factors." Areas with high TRI values ​​(high inherent risk) are more sensitive to engineering disturbances, and even with conventional fracturing parameters, fault activation may be triggered; while areas with low TRI values ​​(low inherent risk) are more tolerant of engineering disturbances, and fracturing parameters can be appropriately optimized to improve development efficiency.

[0019] The Geological Structure Evaluation Index (TRI) and the Fault Activation Potential Coefficient (FAP) show a significant positive correlation (consistent with physical logic). A higher TRI value means a smaller critical pore pressure increment required for fault activation—that is, hydraulically injected fluid only needs a small pressure increase to reduce the effective normal stress on the fault plane to a critical value, triggering slip. Conversely, a lower TRI value means a larger critical pore pressure increment required for fault activation, making it more difficult to be triggered by engineering activities.

[0020] Step S3: The seismic b-values ​​in the seismic monitoring data are fused to obtain the standardized coefficients of the seismic b-values. An ETAS model is then constructed to calculate the external triggering rate of engineering activities. The standardized coefficients of the external triggering rate are calculated. Based on the standardized coefficients of the seismic b-values ​​and the external triggering rate, the seismic activity disturbance index (SDI) of the grid cells is calculated. Step S3 specifically includes: Step S31: Based on the minimum complete magnitude Mc Calculate the earthquake b-value; ; in, e It is a natural constant. For earthquakes with a magnitude greater than or equal to the minimum complete magnitude Mc The time-averaged magnitude of earthquakes; Step S32: Standardize the seismic b-values ​​to obtain the standardized coefficients of the seismic b-values ​​within the grid cells. ; ; Step S33: Construct the ETAS model to calculate the earthquake occurrence rate ; ; in, t For time, Background earthquake incidence rate, k This is the aftershock induction capacity coefficient. For the first i The time of occurrence of an earthquake event c The aftershock decay time constant. p The aftershock attenuation index. This is the coefficient representing the influence of magnitude on the aftershock rate. For the first i The magnitude of the earthquake event; Step S34: Based on earthquake occurrence rate Calculate the external triggering rate of engineering activities within the grid cell. ; ; Step S35: External triggering rate of the mesh cell The normalization process is performed to obtain the normalized coefficients of the external trigger rate of the grid cells. ; ; in, These represent the minimum and maximum trigger rates within and outside the shale gas development area, respectively. Step S36: Based on the standardized coefficients of the earthquake b-value Standardized coefficients of external trigger rate Calculate the seismic activity disturbance index (SDI) of the grid cells; ; in, These are the weighting coefficients for engineering activities and seismic activities, respectively.

[0021] This invention quantifies the degree of disturbance to geological stability caused by the dynamic evolution of seismic activity in shale gas development areas through the Seismic Activity Disturbance Index (SDI). Essentially, it is a dimensionless comprehensive index that integrates seismic activity parameters (b-value) and engineering triggering correlation (ETAS external triggering rate) to characterize the activity level and potential risks of regional seismic activity under the combined effects of natural tectonics and engineering development.

[0022] The Seismic Disturbance Index (SDI) ranges from 0 to 1, and its value is positively correlated with the risk of seismic activity disturbing geological stability. The core logic is the coupling of two factors: natural background and engineering disturbance. The closer the SDI value is to 1, the stronger the disturbance of geological stability caused by seismic activity in the region, and the higher the risk of superposition of engineering-induced earthquakes and tectonic earthquakes. The physical essence is: a high proportion of small earthquakes in the region (large b-value), and a significant external triggering effect of engineering activities on earthquakes (external triggering rate). Both (high) and (high) indicate that the regional crustal stress is in an active state. Hydraulic fracturing operations for shale gas development can further disturb the stress field, trigger fault activation or exacerbate seismic activity, posing a strong threat to geological stability.

[0023] The closer the SDI value is to 0, the weaker the disturbance of geological stability by seismic activity in the region, and the lower the earthquake-related risk. The physical essence is that regional earthquakes are mainly caused by natural tectonic forces (small b-value), and the triggering effect of engineering activities on earthquakes is weak (external triggering rate). The Earth's crust is relatively stable, and even with shale gas development activities, it is difficult to cause significant seismic disturbances. Geological stability is minimally affected by seismic factors.

[0024] Step S4: Calculate the geological stability index using the Geological Structure Evaluation Index (TRI) and the Seismic Activity Disturbance Index (SDI). Assess the geological stability of the shale gas development area. Step S4 specifically includes: Step S41: Set the threshold for the Geological Structure Evaluation Index (TRI) of the grid cells. Threshold of the Seismic Activity Disturbance Index (SDI) Calculate the geological stability index ; ; Step S42: Set the geological stability index threshold ;like If the geological stability of the shale gas development area corresponding to the grid unit is good, then the geological stability of the shale gas development area corresponding to the grid unit is determined to be poor; otherwise, the geological stability of the shale gas development area corresponding to the grid unit is determined to be good.

[0025] This invention overcomes the limitations of traditional single-fault evaluation, constructing a coupled evaluation system of "static geological tectonic background - dynamic seismic activity response." It simultaneously integrates three major fault activation mechanisms: fluid diffusion, porosity-elastic coupling, and fault creep, comprehensively covering the main controlling factors of geological stability in shale gas development. The completeness and accuracy of the evaluation results are significantly improved compared to traditional methods. This invention, through the coupling of seismic b-value fitting calculations and the ETAS model, accurately separates natural tectonic earthquakes from engineering-induced earthquakes, quantifies the degree of disturbance to seismic activity by engineering development activities, and overcomes the limitation of traditional methods in being unable to identify the dynamic impact of engineering activities on geological stability. It enables dynamic tracking and evaluation of geological stability throughout the entire shale gas development cycle.

Claims

1. A method for evaluating the geological stability of shale gas development, characterized in that, include: Step S1: Collect geological structure data and seismic monitoring data of the shale gas development area, divide the spatial zoning map of the shale gas development area into several grid units, and determine the minimum complete magnitude based on the seismic monitoring data. Mc ; Step S2: Using the geological structure data within the grid cell, calculate the fault activation potential coefficient (FAP) within the grid cell based on the modified Mohr-Coulomb fault activation criterion, and objectively assign weights to the geological structure data within the grid cell using principal component analysis (PCA) to calculate the geological structure evaluation index (TRI) of the grid cell. Step S3: Fuse the earthquake b-values ​​in the earthquake monitoring data to obtain the standardized coefficients of the earthquake b-values, construct the ETAS model to calculate the external triggering rate of engineering activities, calculate the standardized coefficients of the external triggering rate, and calculate the seismic activity disturbance index SDI of the grid cells based on the standardized coefficients of the earthquake b-values ​​and the standardized coefficients of the external triggering rate. Step S4: Calculate the geological stability index using the Geological Structure Evaluation Index (TRI) and the Seismic Activity Disturbance Index (SDI). To assess the geological stability of shale gas development areas.

2. The method for evaluating the geological stability of shale gas development according to claim 1, characterized in that, Step S2 includes: Step S21: Using geological structural data within the grid cells, calculate the fault activation potential coefficient (FAP) within the grid cells based on the modified Mohr-Coulomb fault activation criterion; ； in, The shear stress on the fracture surface. The static internal friction coefficient of the fault plane is given. The normal stress on the fault plane, The pore fluid pressure at the fault plane, The cohesion at the fracture surface, This is a function for determining the value of the fault dip angle influence coefficient. This is a function representing the value of the fault extension length influence coefficient. This is a function for determining the value of the fault displacement influence coefficient. The fault dip angle; Step S22: Determine the fault dip angle Extension length L and vertical displacement H Standardization was performed to obtain the fault dip coefficient. Elongation coefficient and vertical displacement coefficient ; ， , ； in, These represent the maximum and minimum fault dip angles in the shale gas development area, respectively. These represent the maximum and minimum fault extension lengths in shale gas development areas, respectively. These represent the maximum and minimum vertical fault displacement values ​​in the shale gas development area, respectively. Step S23: Based on the fault dip coefficient of each grid cell Elongation coefficient and vertical displacement coefficient Constructing the fault parameter normalization matrix ; ； in, m The number of grid cells, The first m Fault dip coefficient of each grid cell Elongation coefficient and vertical displacement coefficient ; Step S24: Standardize the matrix based on fault parameters Calculate the correlation coefficient matrix ; ； Step S25: Solve the characteristic equation The characteristic values ​​of fault dip angle, extension length and vertical displacement are obtained. , It is a unit vector; Step S26: Based on eigenvalues Objective weights for calculating fault dip angle, extension length, and vertical displacement. ; ； Step S27: Utilize objective weights and fault dip coefficient Elongation coefficient and vertical displacement coefficient Calculate the Geological Structure Evaluation Index (TRI) for grid cells; 。 3. The method for evaluating the geological stability of shale gas development according to claim 2, characterized in that, The function for determining the influence coefficient of the fault dip angle. Specifically: ； The function for determining the influence coefficient of fault extension length. Specifically: ； The function for determining the influence coefficient of fault displacement Specifically: ;in, H This represents the vertical displacement of the fault.

4. The method for evaluating the geological stability of shale gas development according to claim 2, characterized in that, Step S3 includes: Step S31: Based on the minimum complete magnitude Mc Calculate the earthquake b-value; ； in, e It is a natural constant. For earthquakes with a magnitude greater than or equal to the minimum complete magnitude Mc The time-averaged magnitude of earthquakes; Step S32: Standardize the seismic b-values ​​to obtain the standardized coefficients of the seismic b-values ​​within the grid cells. ; ； Step S33: Construct the ETAS model to calculate the earthquake occurrence rate ; ； in, t For time, Background earthquake incidence rate, k This is the aftershock induction capacity coefficient. For the first i The time of occurrence of an earthquake event c The aftershock decay time constant. p The aftershock attenuation index. This is the coefficient representing the influence of magnitude on the aftershock rate. For the first i The magnitude of the earthquake event; Step S34: Based on earthquake occurrence rate Calculate the external triggering rate of engineering activities within the grid cell. ; ； Step S35: External triggering rate of the mesh cell The normalization process is performed to obtain the normalized coefficients of the external trigger rate of the grid cells. ; ； in, These represent the minimum and maximum trigger rates within and outside the shale gas development area, respectively. Step S36: Based on the standardized coefficients of the earthquake b-value Standardized coefficients of external trigger rate Calculate the seismic activity disturbance index (SDI) of the grid cells; ； in, These are the weighting coefficients for engineering activities and seismic activities, respectively.

5. The method for evaluating the geological stability of shale gas development according to claim 4, characterized in that, Step S4 includes: Step S41: Set the threshold for the Geological Structure Evaluation Index (TRI) of the grid cells. Threshold of the Seismic Activity Disturbance Index (SDI) Calculate the geological stability index ; ； Step S42: Set the geological stability index threshold ;like If the geological stability of the shale gas development area corresponding to the grid unit is good, then the geological stability of the shale gas development area corresponding to the grid unit is determined to be poor; otherwise, the geological stability of the shale gas development area corresponding to the grid unit is determined to be good.

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