Method for determining width and strength of stress disturbance bands of structures on two sides of upright fracture

Abstract

The invention discloses a method for determining the width and strength of tectonic stress disturbance bands on the two sides of a vertical fracture, and aims to solve the problem that the width and strength of the tectonic stress disturbance bands on the two sides of the vertical fracture are difficult to accurately determine in the prior art. Static rock mechanical parameters are solved by counting the trend and the plane extension length of the vertical fracture in the research area; constructing a geomechanical model and a mathematical model related to sliding of the upright fracture along the trend, and carrying out a tectonic stress field numerical simulation test to obtain the horizontal maximum principal stress intensity of each position; counting the average value of the horizontal maximum principal stress of each interval; and drawing a contour map, and judging the width and the disturbance intensity of the stress disturbance band according to the contour map. According to the method, the accurate numerical value of the widths of the tectonic stress disturbance bands on the two sides of the fracture under the specific regional tectonic stress background is given, the accurate numerical value of the tectonic stress disturbance intensity is also given, and the judgment precision is remarkably improved.

Description

Technical Field

[0001] This application relates to the technical field of reservoir geomechanics in geology, and particularly to a method for determining the width and strength of the tectonic stress disturbance zones on both sides of a vertical fault. Background Art

[0002] In-situ stress is a kind of stress existing in rock masses (Jing Feng, Sheng Qian, Zhang Yonghui, et al., 2011. Research progress on in-situ stress measurement and in-situ stress field analysis in China [J]. Rock and Soil Mechanics, 32(S2): 51-58), including paleo-stress and present-day stress. Among them, tectonic stress is very important in both paleo-stress and present-day stress, and is of great significance in all aspects of oil and gas field exploration and development. Tectonic stress is significantly affected by fractures (HUDSON J A, HARRISON J P, 2000. Engineering rock mechanics an introduction to the principles [M]. Oxford: Elsevier). It is mainly manifested that compared with ordinary sedimentary strata, the intensity and direction of tectonic stress change significantly in the strata near fractures, which is called tectonic stress disturbance. Recent important oil and gas discoveries in the Shunbei area of the Tarim Basin indicate that the study of the strike-slip along the pre-existing nearly vertical fractures and their associated tectonic fracture zones has very important oil and gas geological significance. Tectonic fractures caused by paleo-tectonic stress are important factors controlling the activity of vertical fractures and the development of tectonic fractures (Ding, W. L., Fan, T. L., Yu, B. S., Huang, X. B. & Liu, C., 2012. Ordovician carbonate reservoir fracture characteristics and fracture distribution forecasting in the Tazhong area of Tarim Basin, Northwest China, Journal of Petroleum Science and Engineering, 86-87, 62-70; Huang, L., Liu, C., He, F., Jia, H., Zhou, Y., Wang, Z., Wang, J., Liu, Y. & Li, X., 2022. Strike-slip deformation characteristics of fault in craton Basin, Journal of Northwest University. Natural Science Edition, 52(6), 930-942).The study of the control effect of paleotectonic stress perturbation on the distribution characteristics of tectonic fracture zones along vertical faults is crucial. The width and intensity of the paleotectonic stress perturbation zone caused by the strike-slip along the vertical fault have a strong control effect on the width and development degree of the tectonic fracture zone (Li, Y., Ding, W., Han, J., Chen, X., Huang, C., Li, J. & Ding, S., 2024. Quantitative Prediction of the Development and Opening Sequence of Fractures in an Ultradeep Carbonate Reservoir: A Case Study of the Middle Ordovician in the Shunnan Area, Tarim Basin, China, SPE Journal, 29(6), 3091-3117; Li, Y., Ding, W., Han, J., Chen, X., Huang, C., Li, J. & Ding, S., 2024. Tectonic fractures induced by strike-slip faulting in intracratonic ultradeep carbonate rocks: Insights from the finite element method and self-adaptive constraints computational model for boundary conditions, GSA Bulletin, 136(11-12), 4512-4540). Therefore, the study of the paleotectonic stress perturbation zone caused by the strike-slip along the vertical fault will have very important significance for oil and gas geology and development.

[0003] At present, the first research method for the tectonic stress disturbance zone is as follows: set the pre-existing fracture as an abnormal zone of rock mechanical properties, then construct a geomechanical model and a mathematical model and carry out three-dimensional finite element numerical simulation. According to the numerical simulation results, qualitatively and quantitatively analyze the width of the stress disturbance zone near the fracture, the changes in the magnitude and direction of in-situ stress, and their influencing factors (Weng Jianqiao, Zeng Lianbo, Lv Wenya, Liu Qi & Zu Kewei, 2020. Width of in-situ stress disturbance zone near faults and its influencing factors, Acta Geomechanica Sinica, 26(01), 39-47; Wang Laiyuan, Huang Cheng, Gong Wei, etc. Analysis of fracture characteristics and stress field disturbance in the Silurian system in the Shunbei area of Tazhong and well location optimization [J]. Acta Petrolei Sinica (Petroleum Geology & Experiment), 2024, 46(04): 674-682; Ding Wenlong, Li Yuntao, Han Jun, etc. High-precision tectonic stress field simulation and fracture multi-parameter distribution prediction method for carbonate reservoirs and its application [J]. Oil & Gas Geology, 2024, 45(03): 827-851; Shen Jie, Xu Hao, Deng Hucheng, etc. Study on the distribution characteristics and disturbance mechanism of in-situ stress field in complex fracture areas - taking the Upper Paleozoic in the Dingbei area of the Ordos Basin as an example [J / OL]. Geology in China, 1-19 [2025-01-22]; Lei Xianghui, Xu Dongsheng, Shi Leiting, etc. Characteristics and inversion method of in-situ stress disturbance in fault-developed oil and gas reservoirs [J]. Journal of Liaoning Technical University (Natural Science), 2023, 42(03): 293-300).

[0004] The second method is as follows: combine multiple methods (hydraulic fracturing method, acoustic emission experimental measurement, borehole wall sloughing method, logging calculation, imaging logging method, borehole size method, wave velocity anisotropy method, etc.) to accurately interpret the current in-situ stress of a single well near the fracture, and analyze the disturbance effect of the in-situ stress accordingly (Zhang Jiawei, Li Ruixue, Deng Hucheng, etc. Characteristics of in-situ stress field disturbance in tight sandstone reservoirs of ultra-deep thrust nappe structures - taking the Cretaceous reservoirs in the Bozhi-Dabei area of the Tarim Basin as an example [J]. Acta Petrolei Sinica (Petroleum Geology & Experiment), 2024, 46(04): 760-774). Summary of the Invention

[0005] The present application provides a method for determining the width and strength of the tectonic stress disturbance zones on both sides of an upright fracture, aiming to solve the problem in the prior art that it is difficult to accurately determine the width and disturbance strength of the tectonic stress disturbance zones on both sides of an upright fracture based on the characteristics of the regional tectonic stress field and the upright fracture.

[0006] In a first aspect, a method for determining the width and strength of the tectonic stress disturbance zones on both sides of an upright fracture includes:

[0007] Step S1: Determine the study area and the target formation, count the strike and planar extension length of the vertical faults in the study area, and define the key periods of fault activity and the paleotectonic stress field environment; further define the direction, intensity of the regional maximum horizontal principal stress, intensity of the minimum horizontal principal stress, and intensity of the vertical stress during the key period;

[0008] Step S2: Based on the core, conventional logging, and array acoustic logging data of the target formation, solve the static rock mechanical parameters;

[0009] Step S3: Construct a geomechanical model and a mathematical model related to the strike-slip of the vertical fault, and conduct numerical simulation tests of the tectonic stress field to obtain the intensity of the maximum horizontal principal stress at each position;

[0010] Step S4: In the simulation experiment, calculate the distance from all nodes to the vertical fault, divide intervals according to the distance and the research accuracy requirements, set the interval length or the number of intervals, and count the average value of the maximum horizontal principal stress in each interval; use the midpoint of the interval to represent the overall distance from the nodes in the interval to the vertical fault;

[0011] Step S5: Select the nearest intervals on both sides of the vertical fault, and define the width and intensity of the tectonic stress perturbation zones on both sides of the vertical fault;

[0012] Step S6: Draw an isogram showing the variation of the width and intensity of the tectonic stress perturbation zone with the boundary conditions, and judge the width and intensity of the stress perturbation zone based on the isogram.

[0013] In the above solution, further optionally, step S2 includes:

[0014] Calculate the dynamic rock mechanical parameters based on the conventional logging and array acoustic logging data, where the dynamic rock mechanical parameters include the dynamic Young's modulus and the dynamic Poisson's ratio;

[0015] Obtain the static rock mechanical parameters from the rock mechanical experiments of the core samples, where the static rock mechanical parameters include the static Young's modulus and the static Poisson's ratio parameters;

[0016] Fit the dynamic and static rock mechanical parameters of the target formation in the study area to obtain a conversion model for the dynamic and static rock mechanical parameters:

[0017]

[0018] where E represents the static Young's modulus; μ represents the static Poisson's ratio; E d represents the dynamic Young's modulus; μ d represents the dynamic Poisson's ratio.

[0019] In the above solution, further optionally, the calculation of the dynamic rock mechanical parameters based on the conventional logging and array acoustic logging data includes:

[0020] Based on the conventional logging data, construct a conversion model between the acoustic travel time AC and the direct wave travel time DTC; then based on the array acoustic logging data, construct a conversion model between the direct wave travel time DTC and the shear wave travel time DTS; use the two conversion models to calculate DTC and DTS,

[0021] The calculation formulas for the dynamic Young's modulus and the dynamic Poisson's ratio of the well drilling in the target formation are:

[0022]

[0023] where E d represents the dynamic Young's modulus, with the unit of GPa; μ d is the dynamic Poisson's ratio; Δt p is the direct wave travel time DTC, with the unit of μs / ft; Δt s is the shear wave travel time DTS, with the unit of μs / ft; ρ is the density, with the unit of g / cm3.

[0024] In the above solution, optionally, the step S3 includes:

[0025] According to the geological characteristics of the study area, construct a three-dimensional geomechanical model, which includes the position, strike, extension length of the vertical fracture and the geometric characteristics of the target formation; set the vertical fracture as a discontinuous surface with a certain friction coefficient to simulate the relative sliding of the strata on both sides of the fracture;

[0026] Convert the geomechanical model into a mathematical model, and through finite element analysis software, perform mesh division to divide the model into several elements and nodes;

[0027] Assign the static rock mechanical parameters obtained from step S2 to each element in the mathematical model; according to the requirements of the research accuracy, set the boundary conditions and constraint conditions of the mathematical model; carry out a numerical simulation test of the tectonic stress field, and obtain the horizontal maximum principal stress intensity at each position of the model from the test results;

[0028] Compare the simulation results with the actual geological data to verify the accuracy and reliability of the model.

[0029] In the above solution, optionally, the step S4 includes:

[0030] Adjust the coordinate system of the model to be consistent with the direction of the regional stress field, and calculate the distance from each node in the model to the vertical fracture; count the maximum value D MAX and the minimum value D MIN ; set the interval length D according to the requirements of the research accuracyINT ; The range of each interval is:

[0031] [D MIN +(i - 1) / n*(D MAX - D MIN ), D MIN + i / n*(D MAX - D MIN )]

[0032] Where n represents the preset number of intervals; i represents the interval number;

[0033] For each interval, record the horizontal maximum principal stress of each node within the interval. After multiple numerical simulation tests of the tectonic stress field, calculate the average value of the horizontal maximum principal stress of the interval;

[0034] Use the interval median to represent the overall distance of the nodes within the interval from the vertical fracture; the interval median is:

[0035] D MIN +(i - 0.5) / m*(D MAX - D MIN )

[0036] In the above solution, optionally, the step S5 includes:

[0037] Obtain the median of each interval from step S4. For all interval medians less than or equal to 0, find the interval median with the smallest absolute value, denoted as D LEFT-MIN , and the corresponding average value of the horizontal maximum principal stress is denoted as S LEFT-MIN ; For all interval medians greater than or equal to 0, find the interval median with the smallest absolute value, denoted as D RIGHT-MIN , and the corresponding average value of the horizontal maximum stress is denoted as S RIGHT-MIN ; If D LEFT-MIN = D RIGHT-MIN = 0, then these two intervals are actually the same interval, and the same interval is still used in subsequent analysis;

[0038] For each interval, check whether the average value S H (k, i) of the horizontal maximum principal stress satisfies one of the following conditions:

[0039] [S H (k, i)- S H (k, i - 1)]·[S H (k, i + 1)- S H (k, i)] < 0

[0040]

[0041] Where S *Denote the horizontal maximum principal stress threshold; S H Denote the average value of the horizontal maximum principal stress simulation results; i denotes the interval number; k denotes the simulation experiment number;

[0042] For the interval median less than or equal to 0, find the interval that meets the above conditions, and denote the interval median as D LEFT-MAX (k), and denote the corresponding average horizontal maximum principal stress as S LEFT-MAX (k); for the interval median greater than or equal to 0, find the interval that meets the above conditions, and denote the interval median as D RIGHT-MAX (k), and denote the corresponding stress average value as S RIGHT-MAX (k);

[0043] Obtain the intervals on both sides of the vertical fracture representing the mutation of the horizontal maximum principal stress in all simulation tests, and calculate the width and strength of the tectonic stress disturbance zone on both sides of the vertical fracture according to the following equation set:

[0044]

[0045] When the interval medians are all less than or equal to 0, the width and strength of the tectonic stress disturbance zone are △D LEFT (k) and △S LEFT (k); when the interval medians are all greater than or equal to 0, the width and strength of the tectonic stress disturbance zone are △D RIGHT (k) and △S RIGHT (k);

[0046] Divide both △D LEFT (k) and △D RIGHT (k) by the length of the vertical fracture preset in the model to obtain the tectonic stress disturbance zone width coefficients △D’ LEFT (k) and △D’ RIGHT (k).

[0047] In the above solution, optionally, the step S6 includes:

[0048] Draw the plane contour maps of △D’ LEFT (k), △S LEFT (k), △D’ RIGHT (k) and △S RIGHT (k) at different angles of θ. The horizontal axis of this plane contour map is the ratio of the horizontal maximum principal stress to the vertical stress σ H / σ V , and the vertical axis is the ratio of the horizontal minimum principal stress to the horizontal maximum principal stress σ h / σ H ; where θ represents the angle between the strike of the vertical fracture and the regional horizontal maximum principal stress direction;

[0049] Determine the width and strength of the tectonic stress disturbance zone on this side as ΔD RIGHT (k) and ΔS RIGHT (k); on the other side, they are ΔD LEFT (k) and ΔS LEFT (k);

[0050] Observe the trend in the isogram, determine the variation law of the width and strength of the stress disturbance zone, and identify the boundary position of the stress disturbance zone, i.e., the position of stress mutation; determine the width and strength of the tectonic stress disturbance zone on both sides of the vertical fracture according to the isogram.

[0051] Calculate the disturbance zone width coefficient ΔD’ LEFT (k) and ΔD’ RIGHT (k), as well as the disturbance intensity ΔS LEFT (k) and ΔS RIGHT (k).

[0052] In the above solution, further optionally, the determination of the width and strength of the tectonic stress disturbance zone on both sides of the vertical fracture includes:

[0053] Successively number multiple different θ values as α 1 ~α t , where θ represents the angle between the strike of the vertical fracture and the direction of the regional horizontal maximum principal stress;

[0054] Obtain the isogram corresponding to α k and obtain ΔD’ LEFT (Fi, α k ), ΔS LEFT (Fi, α k ), ΔD’ RIGHT (Fi, α k ) and ΔS RIGHT (Fi, α k ) corresponding to the vertical fracture Fi from this isogram;

[0055] Obtain the isogram corresponding to α k+1 and obtain ΔD’ LEFT (Fi, α k+1 ), ΔS LEFT (Fi, α k+1 ), ΔD’ RIGHT (Fi, α k+1 ) and ΔS RIGHT (Fi, α k+1 ) corresponding to the vertical fracture Fi from this isogram;

[0056] Calculate the actual ΔD’ LEFT (Fi, θ i)、△S LEFT (Fi,θ i )、△D’ RIGHT (Fi,θ i ) and △S RIGHT (Fi,θ i ),The calculation formula is:

[0057]

[0058] After calculating the actual △D of all fractures LEFT (Fi,θ i ) and △D RIGHT (Fi,θ i ), it is also necessary to calculate the actual width of the tectonic stress disturbance zone according to the actual length of the fracture. At this time, △D’ LEFT (Fi,θ i ) and △D’ RIGHT (Fi,θ i ) are the disturbance zone width coefficients.

[0059] Compared with the prior art, the present application has at least the following beneficial effects:

[0060] Based on further analysis and research on the problems of the prior art, it is recognized that compared with the prior art where the tectonic stress disturbance zone near a fracture is usually regarded as a whole, the method proposed in the present application takes into account the width and intensity of the tectonic stress disturbance zones on different sides of the fracture (determined by the regional horizontal maximum principal stress). Therefore, it has more advantages in describing the heterogeneity of the tectonic stress state near the fracture.

[0061] Compared with the prior art where the range of the width of the tectonic stress disturbance zone near a fracture is usually given, the present application not only gives the exact numerical values of the widths of the tectonic stress disturbance zones on both sides of the fracture under a specific regional tectonic stress background, but also gives the exact numerical values of the tectonic stress disturbance intensities, which reduces the errors caused by manual determination and significantly improves the judgment accuracy.

[0062] Compared with the prior art where pre-existing fractures are usually set as abnormal rock mechanical properties to carry out the analysis of the width of the tectonic stress disturbance zone, the method proposed in the present application sets the pre-existing vertical fracture as a discontinuous surface with a certain friction coefficient, resulting in relative sliding of the strata on both sides of the vertical fracture under the background of the regional tectonic stress field, thus being closer to the actual deformation characteristics of the strata on both sides when the vertical fracture slides along its strike. Therefore, compared with the prior art, the method proposed in the present application considers the genetic mechanism of tectonic stress more comprehensively and deeply, and has more practical significance and application value. Description of the Drawings

[0063] Figure 1Schematic flow chart of a method for determining the width and strength of the tectonic stress disturbance zone on both sides of a vertical fracture provided by an embodiment of the present application.

[0064] Figure 2 Linear conversion mathematical model of AC and DTC obtained from the AC and DTC data of the target formation in the study area provided by an embodiment of the present application.

[0065] Figure 3 Linear conversion mathematical model of DTC and DTS obtained from the DTC and DTS data of the target formation in the study area provided by an embodiment of the present application.

[0066] Figure 4 Geomechanical model size setting, vertical fracture setting, boundary condition setting, and nine different geomechanical models corresponding to setting the included angle θ between the vertical fracture and one side of the geomechanical model to nine different values, and the corresponding mathematical models provided by an embodiment of the present application.

[0067] Figure 5 Numerical simulation results of the horizontal maximum principal stress on the top interface of the model provided by an embodiment of the present application, with the boundary condition that σ H / σ V equals 3, σ h / σ H equals 0.2, and θ equals 30°.

[0068] Figure 6 Numerical simulation results of the horizontal maximum principal stress on the top interface of the model provided by an embodiment of the present application, with the boundary condition that σ H / σ V equals 2, σ h / σ H equals 0.6, and θ equals 60°.

[0069] Figure 7 Calculation results of the distance between the nodes on the top interface of the model and the vertical fracture provided by an embodiment of the present application, with the boundary condition that θ equals 30°.

[0070] Figure 8 Calculation results of the distance between the nodes on the top interface of the model and the vertical fracture provided by an embodiment of the present application, with the boundary condition that θ equals 60°.

[0071] Figure 9 Relationship between the average value of the horizontal maximum principal stress in each interval and the median of the interval provided by an embodiment of the present application, with the boundary condition that σ H / σ V equals 1 and θ equals 45°, where curves 1 to 9 respectively correspond to σ h / σ HEqual to 0.1 to 0.9 and at intervals of 0.1.

[0072] Figure 10 This is the relationship between the average value of the horizontal maximum principal stress and the median value of the interval provided by an embodiment of the present application. The boundary condition is σ h / σ H Equal to 0.3 and θ equal to 45°, where curves 1 to 9 respectively correspond to σ H / σ V Equal to 1 to 3 and at intervals of 0.25.

[0073] Figure 11 This is the planar contour map of △D provided by an embodiment of the present application when θ is equal to 50° LEFT Regarding σ H / σ V And σ h / σ H And the planar contour map of.

[0074] Figure 12 This is the planar contour map of △S provided by an embodiment of the present application when θ is equal to 50° LEFT Regarding σ H / σ V And σ h / σ H And the planar contour map of.

[0075] Figure 13 This is the planar contour map of △D provided by an embodiment of the present application when θ is equal to 50° RIGHT Regarding σ H / σ V And σ h / σ H And the planar contour map of.

[0076] Figure 14 This is the planar contour map of △S provided by an embodiment of the present application when θ is equal to 50° RIGHT Regarding σ H / σ V And σ h / σ H And the planar contour map of.

[0077] Figure 15 This is the planar contour map of △D provided by an embodiment of the present application when θ is equal to 60° LEFT Regarding σ H / σ V And σ h / σ H And the planar contour map of.

[0078] Figure 16 This is the planar contour map of △S provided by an embodiment of the present application when θ is equal to 60° LEFT Regarding σ H / σ V and σ h / σ H plane contour map of

[0079] Figure 17 For an embodiment of the present application, when θ is equal to 60°, △D RIGHT with respect to σ H / σ V and σ h / σ H plane contour map of

[0080] Figure 18 For an embodiment of the present application, when θ is equal to 60°, △S RIGHT with respect to σ H / σ V and σ h / σ H plane contour map of Detailed implementation manners

[0081] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0082] In the description of the present application: Unless otherwise specified, "a plurality of" means two or more. Expressions such as "including", "comprising", "having", etc. also mean "not limited to" (certain units, components, materials, steps, etc.).

[0083] Based on further analysis and research of the problems in the prior art, the present application recognizes that the method mentioned in the background art has the following three problems:

[0084] Problem 1: Usually, the pre-existing fracture is set as an anomaly in rock mechanical properties to analyze the width of the tectonic stress disturbance zone. Such a setting is applicable in the analysis of present-day in-situ stress disturbance characteristics, but not in the analysis of paleo-tectonic stress disturbance zones, because there is no relative sliding between the strata on both sides of the fracture, which does not conform to the actual geological situation.

[0085] Problem 2: Usually, the tectonic stress disturbance zone near the fracture is regarded as a whole, but the differences in paleo-tectonic stress disturbance characteristics on both sides of the fracture are not clearly characterized. In the context of regional tectonic movement, there must be significant differences in the tectonic stress disturbance characteristics between the side of the fracture closer to the regional stress source and the side of the fracture farther from the regional stress source.

[0086] Problem 3: Usually, the range of the width of the tectonic stress disturbance zone near the fracture is given, rather than an exact coefficient or ratio, which increases the error caused by manual determination and reduces the research accuracy. Therefore, it is urgent to carry out quantitative research on the width and intensity of the palaeotectonic stress disturbance zone related to the strike-slip of the vertical fracture. During this process, attention should also be paid to the differences in the width and intensity of the palaeotectonic stress disturbance zones on both sides of the vertical fracture, and the strata near the fracture cannot be simply considered as a whole.

[0087] The purpose of this application is to provide a method for determining the width and intensity of the tectonic stress disturbance zones on both sides of a vertical fracture, so as to solve the problem in the prior art that it is difficult to quickly determine the width and disturbance intensity of the tectonic stress disturbance zones on both sides of a vertical fracture based on the characteristics of the regional tectonic stress field and the vertical fracture, and to promote the process of oil and gas field exploration and development and reservoir geomechanics research.

[0088] In an embodiment of this application, a method for determining the width and intensity of the tectonic stress disturbance zones on both sides of a vertical fracture is provided, including:

[0089] Step S1, determine the study area and the target formation series, count the strike and planar extension length of the vertical fractures that cut through the target formation series in the study area, and determine the key tectonic geological historical periods and corresponding palaeotectonic stress field environments when the vertical fractures slip along the strike.

[0090] Step S11, according to the actual research needs of oil and gas exploration and development, determine the study area and the target formation series, and count the strike and planar extension length of the vertical fractures that cut through the target formation series in the study area.

[0091] Select the study area and the target formation series according to the actual research needs of oil and gas exploration and development, and clarify the lithology of the target formation series and the depth distribution characteristics of its top and bottom interfaces in the study area. Based on the fine interpretation of 2D or 3D seismic data, identify all the vertical fractures that cut through the target formation series in the study area, number these vertical fractures, and determine their strikes (represented by the azimuth angles of the fractures, ranging from 0° to 180°) and planar extension lengths. These vertical fractures are required to completely cut through the target formation series, and the intersection lines with the top and bottom interfaces of the target formation series should be continuous and clearly visible on the plane.

[0092] In an embodiment of the present application, Basin A in China is taken as the study area, and important oil and gas producing formation B is taken as the target formation system. When conducting comprehensive stratigraphic-structural interpretation based on 3D seismic data in Basin A, the conversion between two-way travel time and actual depth was not carried out. Therefore, the depth on a time scale was used, and the top interface depth of producing formation B was approximately 2400 ms, the bottom interface depth was approximately 2600 ms, and the total thickness was approximately 200 ms. Based on the fine interpretation of 2D or 3D seismic data, the planar distribution characteristics of a total of 13 vertical faults that cut through producing formation B in Basin A were determined. These faults all cut through producing formation B, the planar traces were nearly straight lines and clearly identifiable, and the azimuth angles and planar extension lengths of these faults are shown in Table 1.

[0093] Table 1

[0094]

[0095]

[0096] Step S12: Determine the key tectonic geological historical periods and corresponding paleotectonic stress field environments in which each vertical fault in the study area slides along its strike.

[0097] According to relevant literature on the tectonic evolution analysis of the study area and map compilation techniques for tectonic evolution history, etc., determine the key tectonic geological historical periods related to the sliding of each vertical fault in the study area along its strike. Each fault needs to be analyzed separately because vertical faults cutting through the same target formation do not necessarily form in the same tectonic geological historical period. After determining the key tectonic geological historical periods related to the sliding of each vertical fault in the study area along its strike, further determine the direction of the regional horizontal maximum principal stress (σ H ), the intensity of σ H , the intensity of the regional horizontal minimum principal stress (σ h ), and the intensity of the vertical stress (σ V ). It should be noted that the direction of σ H refers to the direction from the stress source to the fault. For example, if σ H points from the due east direction to the due west direction and the stress source is on the due east side of the vertical fault, then the direction of σ H is -90°; if σ H points from the southwest direction to the northeast direction and the stress source is on the southwest side of the vertical fault, then the direction of σ H is 45°; if σ H points from the south-southeast direction to the north-northwest direction and the stress source is on the south-east side of the vertical fault, then the direction of σ H should be between -45° and -90°.

[0098] In an embodiment of the present application, the key tectonic geological historical periods related to the sliding along the strike of fractures F1 - F6 in Table 1 are the same, and are designated as Period I; the key tectonic geological historical periods related to the sliding along the strike of fractures F7 - F9 are the same, and are designated as Period II; the key tectonic geological historical periods related to the sliding along the strike of fractures F10 - F13 are the same, and are designated as Period III. The σ H direction, σ H strength, σ h strength, and σ V strength are shown in Table 2.

[0099] Table 2

[0100]

[0101] Step S2: Understand the data of cores, conventional logging, and array acoustic logging of the target formation in the study area, and solve the static rock mechanical parameters of the target formation in the study area.

[0102] Step S21: Understand the data of cores, conventional logging, and array acoustic logging of the target formation in the study area. Conduct a detailed statistics on the cores, conventional logging, and array acoustic logging of each well that drills through the target formation in the study area. If there are no well data and core data for the target formation in the study area, or only conventional logging data is available, it is identified as a Type I study area; if the target formation in the study area has core data but no array acoustic logging data, it is identified as a Type II study area; if the target formation in the study area has logging data such as cores, conventional logging, and array acoustic logging, it is identified as a Type III study area; if the target formation in the study area has conventional logging and array acoustic logging data but no core data, it is identified as a Type IV study area.

[0103] In an embodiment of the present application, Formation B in Basin A has core data, conventional logging data, and array acoustic logging data, so it belongs to a Type III study area.

[0104] S22: Solve the static rock mechanical parameters of the target formation in the study area.

[0105] For the Type II study area mentioned in step S21, conduct rock mechanics tests on core samples to obtain parameters such as the static Young's modulus, static Poisson's ratio, and density of the rock. For each parameter, take the average of the corresponding static parameters of all samples. For the Type III study area mentioned in step S21, first calculate the dynamic rock mechanics parameters based on conventional logging and array acoustic logging, and then convert the dynamic rock mechanics parameters to static rock mechanics parameters according to parameters such as the static Young's modulus and static Poisson's ratio obtained from the rock mechanics tests of core samples, as follows: The acoustic travel time (AC) logging data, longitudinal wave travel time (DTC), and shear wave travel time (DTS) logging data in the conventional logging data belong to travel time data and are considered to have good correlation. Therefore, first construct a conversion model for AC and DTC, and then construct a conversion model for DTC and DTS based on the array acoustic logging data; according to these two conversion models, DTC and DTS can be calculated, and the dynamic Young's modulus and dynamic Poisson's ratio of all wells in the target formation can be calculated according to the following formulas (1) and (2):

[0106]

[0107] where E d is the dynamic Young's modulus, with the unit of GPa; μ d is the dynamic Poisson's ratio; Δt p is the longitudinal wave travel time DTC, with the unit of μs / ft; Δt s is the shear wave travel time DTS, μs / ft; ρ is the density, with the unit of g / cm 3 .

[0108] According to the wells and depths of the core samples for which the rock mechanics tests are conducted, obtain the dynamic rock mechanics parameters at the corresponding positions, and then combine the static rock mechanics parameters obtained from the rock mechanics tests to construct a conversion model between the dynamic rock mechanics parameters and the static rock mechanics parameters. According to this conversion model, the calculation results of the dynamic rock mechanics parameters of all wells in the target formation in the study area can be converted into static rock mechanics parameters. Solve the average value of the static rock mechanics parameters of all wells in the target formation in the study area.

[0109] For the Type I or Type IV study area mentioned in step S21, based on the identification of the main lithology of the target formation in the study area, obtain the static rock mechanics parameters of the corresponding lithology in the nearby area by referring to the literature.

[0110] In an embodiment of the present application, Basin A belongs to the Type III study area. Therefore, construct a conversion model for AC and DTC based on the AC and DTC data of all wells in the study area, as Figure 2 shown. Adopt the method of linear fitting, and the goodness of fit R 2It is 0.66. Then, based on the DTC and DTS data of all the wells in the study area, a conversion model of DTC and DTS is constructed. As shown in Figure 3 , a linear fitting method is also adopted, and the goodness of fit R 2 is 0.86. According to Figure 2 and Figure 3 shown in the conversion model, all the AC data in the study area can be converted into DTC and DTS data, and then the dynamic Young's modulus and dynamic Poisson's ratio can be calculated according to formulas (1) and (2). The static rock mechanics parameters can be obtained from the rock mechanics experiments of the rock samples in the target formation in the study area. The corresponding relationships between these static rock mechanics parameters and the calculation results of the dynamic rock mechanics parameters at the corresponding wells and corresponding depths are shown in Table 3.

[0111] Table 3

[0112] Sample number Dynamic Young's modulus / GPa Static Young's modulus / GPa Dynamic Poisson's ratio Static Poisson's ratio 1 75.807 47.151 0.341 0.238 2 75.997 46.749 0.340 0.212 3 76.288 43.695 0.344 0.210 4 73.650 39.600 0.345 0.240 5 74.662 41.265 0.342 0.226 6 64.259 34.800 0.307 0.205 7 67.457 34.791 0.302 0.217 8 70.906 42.865 0.321 0.238 9 71.300 41.329 0.309 0.205 10 67.752 42.304 0.320 0.268

[0113] By fitting the dynamic and static rock mechanics parameters in Table 3, the conversion models of the dynamic and static rock mechanics parameters of the target formation can be obtained, as shown in formulas (3) and (4) respectively:

[0114]

[0115] The goodness of fit of formulas (3) and (4) is 0.62 and 0.63 respectively. According to formulas (3) and (4) and the calculation results of the dynamic rock mechanics parameters of the target formation in the study area, the static rock mechanics parameters of the target formation in the study area can be calculated. The calculation results show that the average value of the static Young's modulus is 39.15 GPa, the average value of the static Poisson's ratio is 0.232, and the average value of the rock density is 2.683 g / cm 3 .

[0116] Step S3: Construct a geomechanical model and a mathematical model related to the strike-slip along the vertical fault, and conduct a numerical simulation test of the tectonic stress field to obtain the horizontal maximum principal stress intensity at each position of the model from the test results.

[0117] Step S31: Set the size of the regular quadrangular prism geomechanical model, set the vertical fault as the contact pair in the finite element analysis, and set several different regular quadrangular prism geomechanical models according to the plane extension orientation of the vertical fault.

[0118] Set the geomechanical model as a regular quadrangular prism, with the top and bottom interfaces of the regular quadrangular prism being congruent squares. To facilitate subsequent mathematical model construction and result analysis, set the side length of the top and bottom interfaces of the regular quadrangular prism to 6000 m, and set the height H of the regular quadrangular prism to 5000 m. Set the vertical fracture as a cavity enclosed by four vertical planes with a height of H. These four planes can be divided into two groups, and the planes belonging to different groups are perpendicular to each other. Each group consists of two planes: the spacing of the first group of planes is set to 5 m, and the plane extension length is 5000 m; the spacing of the second group of planes is 5000 m, and the plane extension length is 5 m. The top and bottom surfaces of the pre-existing basement fracture area are both rectangles with a length of 5000 m and a width of 5 m. The height of this area is H, and the volume is 1.25×10 8 m 3 . The pre-existing basement fracture area penetrates the geomechanical model from top to bottom. The center of the intersection line of this area and the top surface of the geomechanical model is consistent with the center of the top surface of the geomechanical model, and the center of the intersection line of the fracture and the bottom surface of the geomechanical model is consistent with the center of the bottom surface of the geomechanical model.

[0119] Introduce the concept of contact pair in the contact analysis of the static module in finite element analysis and apply it to the setting of pre-existing fractures in the 3D geomechanical model. The contact pair consists of two planes (or curved surfaces), namely the contact surface and the target surface. Among them, the contact surface is the surface that undergoes passive deformation, so it is defined as the fault surface on the side that undergoes passive deformation in the regional tectonic stress field, while the target surface is the surface that undergoes active deformation, so it is defined as the fault surface on the side that undergoes active deformation in the regional tectonic stress field. According to the regional stress direction related to the target formation system and the activity of fracture F1 in the study area, set the fault surface on the side close to the regional stress direction as the target surface, and set the fault surface on the side far from the regional stress direction as the contact surface. The plane extension lengths of both are 5000 m, the heights are both 5000 m, and the spacing is 5 m. Set the friction coefficient between the contact surface and the target surface according to the friction coefficient of the vertical fracture in the formation close to the lithology of the target formation system. Under the action of the regional tectonic stress, when the stress intensity at the fault surface exceeds the stress intensity threshold for relative sliding between the contact surface and the target surface, the contact surface and the target surface can undergo relative sliding, thereby realizing the relative displacement of the strata on both sides of the pre-existing fracture. After completing the size setting of the geomechanical model and the contact pair setting of the vertical fracture, set the angle between the vertical fracture and any side Surface of the geomechanical model as θ. According to the research accuracy requirements, select n values θ i (1≤i≤n) within 0 - 90°, and each θ i corresponds to a different geomechanical model. Thus, the deformation characteristics differences of the strata on both sides of the fracture can be studied when the angle between the vertical fracture F1 and the regional horizontal stress is different.

[0120] In one embodiment of the present application, the three-dimensional geomechanical model is set as a regular quadrangular prism with the length and width of the top surface both being 6000 m, and the height H of the geomechanical model being equal to 5000 m. The vertical fracture is set as a cavity enclosed by four vertical planes with a height of 5000 m. These four planes can be divided into two groups, and the planes belonging to different groups are perpendicular to each other. Each group consists of two planes: the spacing between the planes in the first group is 5 m, and the plane extension length is 5000 m; the spacing between the planes in the second group is 5000 m, and the plane extension length is 5 m. The top and bottom surfaces of the pre-existing basement fracture region are both rectangles with a length of 5000 m and a width of 5 m, the height of this region is 5000 m, and the volume is 1.25×10 8 m 3 . The pre-existing basement fracture region penetrates the geomechanical model from top to bottom. The center of the intersection line of this region and the top surface of the geomechanical model coincides with the center of the top surface of the geomechanical model, and the center of the intersection line of the fracture and the bottom surface of the geomechanical model coincides with the center of the bottom surface of the geomechanical model.

[0121] In one embodiment of the present application, the direction of the horizontal maximum principal stress is fixed from south to north. Therefore, the south side section of the vertical fracture is set as the target surface, and the north side section is set as the contact surface. The plane extension lengths of both are 5000 m, the heights are both 5000 m, and the spacing is 5 m. The friction coefficient of the pre-existing fracture is considered to be 0.15. Therefore, the friction coefficient between the contact surface and the target surface is set to 0.15. Under the action of regional tectonic stress, when the stress intensity at the section exceeds the stress intensity threshold for relative sliding between the contact surface and the target surface, relative sliding can occur between the contact surface and the target surface, and the relative displacement of the strata on both sides of the pre-existing fracture is achieved. θ is set to 10°, 20°, 30°, 40°, 45°, 50°, 60°, 70° and 80°, corresponding to 9 different three-dimensional geomechanical models.

[0122] Step S32: In the finite element analysis software, mesh the geomechanical model constructed in step S31 with tetrahedral elements to obtain the corresponding mathematical model, where the mesh division density of the top interface of the model is higher than other positions of the model. After constructing the mathematical model, export the coordinates of all elements and nodes of the geomechanical model from the finite element analysis software.

[0123] The geomechanical model is meshed with triangular (2D) or tetrahedral (3D) elements, dividing the geological model into a series of elements and nodes. The meshing accuracy of the top surface of the geomechanical model is higher than that of the bottom surface and the four side surfaces. This is because the top interface of the model is on the outside of the model and is a horizontal plane, which can more intuitively reflect the planar heterogeneity of the horizontal stress. If it is necessary to draw the contour map of the maximum principal horizontal stress on the top interface of the model, this approach will significantly improve the accuracy. After the mathematical model is constructed, the spatial coordinates (E_X, E_Y, E_Z) of all elements and the spatial coordinates (N_X, N_Y, N_Z) of the nodes of the geomechanical model are exported from the finite element analysis software.

[0124] In an embodiment of the present application, tetrahedral elements are used to mesh the 3D geomechanical model, dividing the geological model into a series of elements and nodes. The ANSYS computer software is used to mesh the geomechanical model. Based on the characteristics of the elements, the SOLID 45 element is selected to mesh the 3D geomechanical model in an embodiment of the present application. The improvement of the meshing accuracy is achieved by the method of free meshing, and the meshing accuracy of the top surface of the geomechanical model is higher than that of the bottom surface and the four side surfaces. After the mathematical model is constructed, the spatial coordinates (E_X, E_Y, E_Z) of all elements and the spatial coordinates (N_X, N_Y, N_Z) of the nodes of the geomechanical model are exported from the finite element analysis software. The total number of elements and the total number of nodes after meshing each 3D geomechanical model in step S21 are shown in Figure 4 .

[0125] Step S33: Assign the static rock mechanical parameters (Young's modulus, Poisson's ratio, and density) of the target formation in the study area obtained from the solution in step S22 to each element in the mathematical model, set different boundary conditions and constraint conditions for the mathematical model, and conduct numerical simulation of the tectonic stress field to obtain the simulation results corresponding to each test.

[0126] According to the calculation results of the static rock mechanical parameters in step S22, assign the static rock mechanical parameters (Young's modulus, Poisson's ratio, and density) to all elements of all geomechanical models. Define the three parameters of θ, the ratio of the regional maximum principal horizontal stress to the vertical stress (σ H / σ V ), and the ratio of the regional minimum principal horizontal stress to the regional maximum principal horizontal stress (σ h / σ H ) as the key parameters affecting the numerical simulation results of the tectonic stress field. The influence of θ has been reflected in step S31, while σ H / σ V and σ h / σ HThe influence needs to be achieved by changing the boundary conditions of the mathematical model. According to the research accuracy requirements, set σ H / σ V and the test data sets of σ h / σ H , where σ h / σ H is less than 1. The boundary conditions and constraint conditions of the mathematical model mainly include the regional stress application method, application intensity, and displacement constraint method on the sides and top surfaces of the mathematical model. After setting reasonable boundary conditions and constraint conditions for each mathematical model, carry out numerical simulation of the tectonic stress field to obtain the simulation results corresponding to each test. The key point is to statistically analyze the horizontal maximum principal stress intensity at each position of the model in each numerical simulation of the tectonic stress field. For any simulation test i (where 1 ≤ i ≤ n, and n is the total number of numerical simulation tests of the tectonic stress field carried out), the one-to-one correspondence between the node position and the horizontal maximum principal stress can be obtained, that is, {σ H} i = F i (N_X,N_Y,N_Z).

[0127] In an embodiment of the present application, according to the calculation results of the static rock mechanics parameters in step S22, the same static rock elastic parameters are assigned to all elements of all mathematical models, specifically the static Young's modulus (39.15 GPa), static Poisson's ratio (0.232), and rock density (2.683 g / cm 3 ). When carrying out numerical simulation of the tectonic stress field for each mathematical model, σ V is set to 100 MPa to study the deformation characteristics of the model under the action of the same overlying formation gravity. σ H / σ V is set to 1, 2, and 3, namely 100, 200, and 300 MPa, to study the deformation characteristics of the model when σ H / σ V is different. σ h / σ H is set to 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9 to study the deformation characteristics of the model when σ h / σ H is different. Considering the comprehensiveness of this study and the efficiency of numerical simulation operations based on FEM, when σ h / σ H is equal to 0.3, three-dimensional numerical simulation of the tectonic stress field when σ H / σ V is equal to 1.25, 1.50, 1.75, 2.25, 2.50, and 2.75 is also supplemented to more clearly show σ H / σ VEffect on the deformation of the model. Therefore, in an embodiment of the present application, a total of 297 three-dimensional tectonic stress field numerical simulation experiments are involved.

[0128] As Figure 4 shown, the displacements of the nodes on the XZ plane on the south side of the three-dimensional geomechanical model are not constrained, and σ H is applied. The displacements of the nodes on the YZ plane on the east side are not constrained, and the horizontal minimum principal stress (σ h ) is applied. The displacements of the nodes on the XZ plane on the north side and the YZ plane on the west side of the geomechanical model in the X and Y directions are set to a fixed value of 0, and the displacement in the Z direction is not constrained. The displacements of the nodes on the XY plane on the upper side of the geomechanical model are not constrained, and the vertical downward vertical stress (σ V ) is applied. The displacement of the nodes on the XY plane on the lower side of the model in the Z direction is set to a fixed value of 0, and the displacements in the X and Y directions are not constrained. The entire three-dimensional geomechanical model is given a vertically downward acceleration of gravity so that the simulation results are closer to the characteristic that the vertical stress increases with the increase of depth in the actual geological situation. Under the above boundary conditions and constraint conditions, a numerical simulation of the tectonic stress field is carried out for each mathematical model, and the corresponding simulation results of each model are obtained. The key point is to statistically analyze the horizontal maximum principal stress intensity of the nodes on the top surface of the model in each tectonic stress field numerical simulation. A partial horizontal maximum principal stress intensity plane contour map of the top interface of the model drawn according to the tectonic stress field numerical simulation results in an embodiment of the present application is shown in Figure 5 and Figure 6 . For any simulation test i (where 1 ≤ i ≤ 297) in the embodiment of the present application, a one-to-one correspondence between the node position and the horizontal maximum principal stress can be obtained, that is, {σ H} i = F i (N_X, N_Y, N_Z).

[0129] Step S4. For each simulation test, calculate the distance of all nodes from the vertical fracture, and set the interval length or the number of intervals according to the distance and the requirement of the research accuracy. When the distance of the nodes from the vertical fracture is in a certain interval, statistically analyze the average value of the horizontal maximum principal stress at the corresponding nodes.

[0130] Step S41. For each simulation test i, calculate the distance D i (N_X, N_Y, N_Z) of all nodes from the vertical fracture.

[0131] For the i-th simulation test, the coordinates (N_X, N_Y, N_Z) of each node in the corresponding mathematical model have been obtained in step S32. First, all nodes are rotated counterclockwise by an angle θ around the axis (N_X = 0, N_Y = 0) (the definition of θ is shown in step S31). The coordinates (N_X’, N_Y’, N_Z’) of the new nodes are as follows:

[0132]

[0133] The distance D of the node from the vertical fracture i The expression of (N_X, N_Y, N_Z) is:

[0134] D i (N_X, N_Y, N_Z) = N_X'(6)

[0135] After calculating the distance D of all nodes from the vertical fracture in the first simulation test through equations and equation groups (5) and (6) 1 (N_X, N_Y, N_Z), this operation can be repeated until the distances of the nodes from the vertical fracture in all simulation tests are calculated.

[0136] In an embodiment of the present application, the distances of the nodes from the vertical fracture in 297 simulation tests are calculated according to equation groups (5) and (6). The plane contour maps of the distances of the nodes on the top interface of the model in some simulation tests from the vertical fracture are as shown in Figure 7 and Figure 8 shown.

[0137] Step S42, set the interval length or the number of intervals according to the distance of the node from the vertical fracture obtained in step S41 and the requirement of the research accuracy.

[0138] According to the distance of the node from the vertical fracture obtained in step S41, set the interval length or the number of intervals according to the research accuracy requirement. If setting the interval length, for any simulation test, first count the minimum value and the maximum value of the distance of the node from the vertical fracture, and define them as D MIN and D MAX , respectively. Then, according to the difference between D MAX and D MIN and the research accuracy requirement, set the interval length D INT . The higher the research accuracy requirement, the smaller D INT , and vice versa, D INT is larger. If setting the number of intervals, a unified number of intervals n can be set for all simulation tests, and then according to the minimum value D MIN and the maximum value D MAX of the distance of the node from the vertical fracture in each simulation test, it is equally divided into n intervals. The distance D of the node from the vertical fracture in the i-th interval (1 ≤ i ≤ n and i is a positive integer) isi (N_X, N_Y, N_Z) has a numerical range of [D MIN +(i - 1) / n*(D MAX - D MIN ), D MIN +i / n*(D MAX - D MIN )].

[0139] In an embodiment of the present application, according to the distance from the node to the vertical fracture obtained in step S41, the number of intervals is set to 30. Then, for each simulation test, the distance D from the node to the vertical fracture i (N_X, N_Y, N_Z) is divided into 30 corresponding numerical intervals. The distance D from the node to the vertical fracture in the i-th interval (1 ≤ i ≤ 30 and i is a positive integer) i (N_X, N_Y, N_Z) has a numerical range of [D MIN +(i - 1) / 30*(D MAX - D MIN ), D MIN +i / 30*(D MAX - D MIN )].

[0140] Step S43: According to the interval length or the number of intervals set in step S42, for each simulation test, when the distance from the node to the vertical fracture is in a certain interval, the average value of the horizontal maximum principal stress at the corresponding node is statistically calculated.

[0141] According to the interval length or the number of intervals set in step S42, for the k-th (1 ≤ k ≤ n and k is a positive integer, n is the total number of simulation tests) simulation test, if the distance D from a certain node to the vertical fracture k (N_X, N_Y, N_Z) is in the interval [D MIN +(i - 1) / m*(D MAX - D MIN ), D MIN +i / m*(D MAX - D MIN )], where i is the interval number and m is the total number of intervals, 1 ≤ i ≤ m and i is a positive integer, then the simulation result of the horizontal maximum principal stress corresponding to this node is marked in the corresponding interval. For the k-th simulation test, after it is statistically determined which interval the distance D from all nodes to the vertical fracture k (N_X, N_Y, N_Z) belongs to, the corresponding simulation results of the horizontal maximum principal stress are also marked in each interval respectively. For the i-th interval, calculate the average value S of all the simulation results of the horizontal maximum principal stress marked as belonging to this interval H(k, i). Repeat this operation until the average value of the horizontal maximum principal stress simulation results for all intervals in all simulation tests is calculated. In subsequent analyses, the interval numbers are not used because they do not directly reflect the positions of the corresponding intervals. Instead, the median values of the intervals are used, i.e., D MIN +(i - 0.5) / m*(D MAX - D MIN ), which can directly represent the overall distance of the nodes within the interval from the vertical fracture.

[0142] In an embodiment of the present application, the number of intervals set in step S42 is 30. For the k-th (1 ≤ k ≤ 297 and k is a positive integer) simulation test, if the distance D k (N_X, N_Y, N_Z) of a certain node from the vertical fracture is within the interval [D MIN +(i - 1) / 30*(D MAX - D MIN ), D MIN +i / 30*(D MAX - D MIN )], where i is the interval number, then the horizontal maximum principal stress simulation result corresponding to this node is marked within the corresponding interval. For the k-th simulation test, after counting which interval the distance D k (N_X, N_Y, N_Z) of all nodes from the vertical fracture belongs to, the corresponding horizontal maximum principal stress simulation results are also marked within each interval respectively. For the i-th interval, calculate the average value S H (k, i) of all the horizontal maximum principal stress simulation results marked as belonging to this interval. Repeat this operation until the average value of the horizontal maximum principal stress simulation results for all intervals in all simulation tests is calculated. In an embodiment of the present application, the relationship between S H (k, i) of some simulation tests and the median value D MIN +(i - 0.5) / 30*(D MAX - D MIN ) of the corresponding interval i is as shown in Figure 9 and Figure 10 .

[0143] Step S5, for each simulation test, select 1 "distance of the node from the vertical fracture" interval closest to the vertical fracture on each side of the vertical fracture, and respectively determine the width and intensity of the tectonic stress disturbance zones on both sides of the vertical fracture.

[0144] Step S51, select 1 "distance of the node from the vertical fracture" interval closest to the vertical fracture on each side of the vertical fracture respectively.

[0145] For each simulation test, the corresponding "distance from the node to the vertical fracture" interval has been obtained from step S43 and the median D of these intervals has been calculated. MIN +(i - 0.5) / m*(D MAX -D MIN ), where i is the interval number, m is the total number of intervals, 1 ≤ i ≤ m and i is a positive integer. Then, for all interval medians less than or equal to 0, there is an interval median with the smallest absolute value, and this interval is the closest to the vertical fracture. The median of this interval is designated as D LEFT-MIN , and the average value of the maximum principal stress in the horizontal direction of the nodes in this interval is designated as S LEFT-MIN . For all interval medians greater than or equal to 0, there is also an interval median with the smallest absolute value, and this interval is the closest to the vertical fracture. The median of this interval is designated as D RIGHT-MIN , and the average value of the maximum principal stress in the horizontal direction of the nodes in this interval is designated as S RIGHT-MIN . When D LEFT-MIN is equal to D RIGHT-MIN and equal to 0, the two intervals mentioned above are actually the same interval. Then, in subsequent analyses, the same interval is still used for these two intervals. The above operation steps are applied to all simulation tests until D LEFT-MIN (k), S LEFT-MIN (k), D RIGHT-MIN (k), and S RIGHT-MIN (k) in all simulation tests are obtained, where 1 ≤ k ≤ n and k is a positive integer, and n is the total number of simulation tests.

[0146] In an embodiment of the present application, for each simulation test, the corresponding "distance from the node to the vertical fracture" interval has been obtained from step S43 and the median D of these intervals has been calculated. MIN +(i - 0.5) / 30*(D MAX -D MIN ), where i is the interval number, 1 ≤ i ≤ 30 and i is a positive integer. Then, for all interval medians less than or equal to 0, there is an interval median with the smallest absolute value, and this interval is the closest to the vertical fracture. The median of this interval is designated as D LEFT-MIN , and the average value of the maximum principal stress in the horizontal direction of the nodes in this interval is designated as S LEFT-MIN . For all interval medians greater than or equal to 0, there is also an interval median with the smallest absolute value, and this interval is the closest to the vertical fracture. The median of this interval is designated as D RIGHT-MIN , and the average value of the maximum principal stress in the horizontal direction of the nodes in this interval is designated as S RIGHT-MIN . The above operation steps are applied to all simulation tests until D LEFT-MIN (k), S LEFT-MIN (k), DRIGHT-MIN (k) and S RIGHT-MIN (k), where 1 ≤ k ≤ 297 and k is a positive integer.

[0147] Step S52: Determine the width and intensity of the tectonic stress disturbance zones on both sides of the vertical fracture respectively.

[0148] For each simulation test, D has been obtained from Step S51 LEFT-MIN (k), S LEFT-MIN (k), D RIGHT-MIN (k) and S RIGHT-MIN (k), where 1 ≤ k ≤ n and k is a positive integer, and n is the total number of simulation tests. Now, a position representing the sudden change of the horizontal maximum principal stress needs to be found on both sides of the vertical fracture respectively, and used as the boundary of the tectonic stress disturbance zones on both sides of the vertical fracture. For S H (k, i) calculated in Step S43, where i is the interval number, m is the total number of intervals, and 1 ≤ i ≤ m and i is a positive integer. First, find the position representing the sudden change of the horizontal maximum principal stress when the interval median values are all less than or equal to 0. Specifically:

[0149] When S H (k, i) satisfies the following inequality, the i-th interval is identified as the interval representing the position of the sudden change of the horizontal maximum principal stress:

[0150] [S H (k, i) - S H (k, i - 1)] · [S H (k, i + 1) - S H (k, i)] < 0 (7)

[0151] If there is no S H (k, i) that meets the inequality (9), if S H (k, i) satisfies the following inequality group, the i-th interval can also be considered to represent the position of the sudden change of the horizontal maximum principal stress:

[0152]

[0153] where S * is the threshold of the horizontal maximum principal stress. When exceeding this threshold, it indicates that a significant change in the horizontal maximum principal stress occurs between adjacent intervals. The determination of this threshold needs to be based on the research accuracy and is usually set to a small value, such as 1 MPa. The median value of the interval representing the sudden change of the horizontal maximum principal stress determined when the interval median values are all less than or equal to 0 is set as D LEFT-MAX (k), and the average value of the horizontal maximum principal stress corresponding to this interval is set as S LEFT-MAX (k).

[0154] Find the position representing the sudden change of the horizontal maximum principal stress when the median values of the intervals are all greater than or equal to 0, specifically:

[0155] When S H (k, i) satisfies the inequality (7), the i-th interval is recognized as the interval representing the position of the sudden change of the horizontal maximum principal stress. If there is no S H (k, i) that meets the requirements, and if S H (k, i) satisfies the following inequality group, it can also be considered that the i-th interval represents the position of the sudden change of the horizontal maximum principal stress:

[0156]

[0157] Define the median value of the interval representing the sudden change of the horizontal maximum principal stress determined when the median values of the intervals are all greater than or equal to 0 as D RIGHT-MAX (k), and define the average value of the horizontal maximum principal stress corresponding to this interval as S RIGHT-MAX (k).

[0158] By repeating the above steps, the intervals representing the sudden change of the horizontal maximum principal stress on both sides of the vertical fracture in all simulation tests can be obtained. According to the following equation group, the width and intensity of the tectonic stress disturbance zone on both sides of the vertical fracture can be calculated:

[0159]

[0160] Among them, when the median values of the intervals are all less than or equal to 0, the width and intensity of the tectonic stress disturbance zone are △D LEFT (k) and △S LEFT (k) respectively. When the median values of the intervals are all greater than or equal to 0, the width and intensity of the tectonic stress disturbance zone are △D RIGHT (k) and △S RIGHT (k) respectively. Since the length of the vertical fracture in the model setting is 5000m, divide △D LEFT (k) and △D RIGHT (k) by 5000m to obtain the tectonic stress disturbance zone width coefficients △D’ LEFT (k) and △D’ RIGHT (k).

[0161] In an embodiment of the present application, the horizontal maximum principal stress threshold S * is set to 1MPa. The △D’ LEFT (k), △S LEFT (k), △D’ RIGHT (k) and △S RIGHT (k) obtained according to the above steps are shown in Table 4.

[0162] Table 4

[0163]

[0164]

[0165]

[0166]

[0167]

[0168]

[0169]

[0170]

[0171] Step S6: Draw the contour maps of the width and strength of the tectonic stress disturbance zones on both sides of the vertical fracture with respect to the numerical simulation boundary conditions of the tectonic stress field, and determine the width and strength of the stress disturbance zones of the vertical fractures that penetrate the target formation series in the study area based on the contour maps.

[0172] Step S61: When θ is equal to 10°, 20°, 30°, 40°, 45°, 50°, 60°, 70°, and 80° in sequence, draw △D’ LEFT , △S LEFT , △D’ RIGHT and △S RIGHT 's planar contour maps. The horizontal axis of this map is σ H / σ V , and the vertical axis is σ h / σ H .

[0173] When θ is equal to 10°, draw the planar contour maps of △D’ LEFT , △S LEFT , △D’ RIGHT and △S RIGHT with respect to σ H / σ V and σ h / σ H respectively according to the results in Step S52. Repeat this operation when θ is equal to 20°, 30°, 40°, 45°, 50°, 60°, 70°, and 80° in sequence to obtain 36 contour maps.

[0174] In an embodiment of the present application, when θ is equal to 10°, draw △D’ LEFT , △S LEFT , △D’ RIGHT and △S RIGHT with respect to σ H / σ V and σ h / σ H The planar contour maps of, repeat this operation when θ equals 20°, 30°, 40°, 45°, 50°, 60°, 70° and 80° in turn, and 36 contour maps are obtained.

[0175] Step S62: Determine the width and intensity of the stress disturbance zone of the vertical fractures cutting through the target formation in the study area based on a series of contour maps obtained from step S61.

[0176] According to steps S11 and S12, the strike of the vertical fracture Fi (where 1 ≤ i ≤ n, and n is the total number of vertical fractures) cutting through the target formation in the study area and the azimuth of σ H can be obtained respectively. Therefore, the included angle θ H between the vertical fracture Fi and σ i can be calculated, and it is known on which side of the vertical fracture the regional stress source is located (see the definition of the direction of the regional horizontal maximum principal stress in step S12). According to the analysis in steps S3 to S5, when the regional stress source is on one side of the vertical fracture, the width and intensity of the tectonic stress disturbance zone on this side are respectively defined as △D RIGHT and △S RIGHT , while the width and intensity of the tectonic stress disturbance zone on the side of the vertical fracture far from the regional stress source are respectively defined as △D LEFT and △S LEFT . Therefore, according to which side of each vertical fracture the regional stress source is located, determine that the width and intensity of the tectonic stress disturbance zone on which side of the vertical fracture are △D RIGHT and △S RIGHT , while those on the other side are △D LEFT and △S LEFT . Number 10°, 20°, 30°, 40°, 45°, 50°, 60°, 70° and 80° as α 1 ~α 9 in turn. For the vertical fracture Fi, if α k ≤θ i <α k+1 , where 1 ≤ k ≤ 8, then according to α k and α k+1 and the corresponding △D’ LEFT , △S LEFT , △D’ RIGHT and △S RIGHT contour maps (obtained from step S61), obtain △D’ LEFT , △S LEFT , △D’ RIGHT and △S RIGHT of the vertical fracture Fi. The specific steps are as follows:

[0177] The first step is to obtain the regional horizontal maximum principal stress intensity, regional horizontal minimum principal stress intensity and vertical stress intensity during the tectonic movement period related to the sliding along the vertical fault Fi from step S12, and calculate the σ corresponding to the vertical fault Fi based on this. H / σ V and σ h / σ H . Obtained from step S61 and α k The corresponding △D' LEFT , △S LEFT , △D' RIGHT and △S RIGHT Contour map, according to the σ corresponding to the vertical fracture Fi H / σ V and σ h / σ H From and α k The corresponding △D' LEFT , △S LEFT , △D' RIGHT and △S RIGHT Obtain the △D' corresponding to the vertical fracture Fi in the contour map LEFT (Fi,α k ), △S LEFT (Fi,α k ), △D' RIGHT (Fi,α k ) and △S RIGHT (Fi,α k );

[0178] The second step is to obtain and α from step S61. k+1 The corresponding △D' LEFT , △S LEFT , △D' RIGHT and △S RIGHT Contour map, according to the σ corresponding to the vertical fracture Fi H / σ V and σ h / σ H From and α k+1 The corresponding △D' LEFT , △S LEFT , △D' RIGHT and △S RIGHT Obtain the △D' corresponding to the vertical fracture Fi in the contour map LEFT (Fi,α k+1 ), △S LEFT (Fi,α k+1 ), △D' RIGHT (Fi,α k+1 ) and △S RIGHT (Fi,α k+1);

[0179] In the third step, calculate the actual △D’ corresponding to the vertical fracture Fi according to the following equation set (11) LEFT (Fi, θ i ), △S LEFT (Fi, θ i ), △D’ RIGHT (Fi, θ i ) and △S RIGHT (Fi, θ i ) as follows:

[0180]

[0181] Repeat the above three steps until the actual △D’ of all vertical fractures is calculated LEFT (Fi, θ i ), △S LEFT (Fi, θ i ), △D’ RIGHT (Fi, θ i ) and △S RIGHT (Fi, θ i ). It should be noted that if θ i ≤α 1 , then set k in the above three steps to 1 and k + 1 to 2; if θ i ≥α 9 , then set k in the above three steps to 8 and k + 1 to 9. After calculating the △D’ LEFT (Fi, θ i ) and △D’ RIGHT (Fi, θ i ), it is also necessary to calculate the actual width of the tectonic stress disturbance zone according to the actual length of the fracture, because the △D’ LEFT (Fi, θ i ) and △D’ RIGHT (Fi, θ i ) at this time are ratios rather than actual widths. See step S52 for details.

[0182] In an embodiment of the present application, the strike and the azimuth angle of σ H of the vertical fracture Fi (where 1 ≤ i ≤ 13) that penetrates the target formation in the study area can be obtained according to Table 1 and S12 respectively. Based on this, the included angle θ H between the vertical fracture Fi and σ i is calculated. Number 10°, 20°, 30°, 40°, 45°, 50°, 60°, 70° and 80° as α 1 ~α 9 in sequence. Taking the vertical fracture F1 listed in Table 1 as an example, the following illustrates how to calculate △D LEFT(Fi,θ i ), △S LEFT (Fi,θ i ), △D RIGHT (Fi,θ i ) and △S RIGHT (Fi,θ i ).

[0183] For the vertical fault F1, its strike is 59.2° (Table 1), and its strike-slip occurred during tectonic activity period I (Table 2). The azimuth of σ H at this time is 0°, σ H / σ V and σ h / σ H are equal to 2.4 and 0.33 respectively. The angle θ H between Fi and σ i is 59.2°, and the regional stress source is located on the southeast side of the vertical fault F1. Therefore, the width and intensity of the tectonic stress disturbance zone calculated on the southeast side are △D’ RIGHT and △S RIGHT , and the width and intensity of the tectonic stress disturbance zone calculated on the northwest side are △D’ LEFT and △S LEFT . The included angle θ i is between α 6 and α 7 . Therefore, it is necessary to analyze according to the isogram of △D’ 6 , △S 7 , △D’ LEFT , △S LEFT , △D’ RIGHT , △S RIGHT corresponding to the α 6 obtained from step S61, and the isogram of △D’ LEFT , △S LEFT , △D’ RIGHT , △S RIGHT corresponding to the α Figures 11 - 14 is shown in 7 , and the isogram of △D’ LEFT , △S LEFT , △D’ RIGHT , △S RIGHT corresponding to the α Figures 15 - 18 is shown in H / σ V and σ h / σ H corresponding to the strike-slip along the vertical fault F1 are equal to 2.4 and 0.33 respectively. Therefore, according to Figures 11 - 14 , when σ H / σ V and σ h / σ H When they are equal to 2.4 and 0.33 respectively, △D’ LEFT , △S LEFT , △D’ RIGHT and △S RIGHT are equal to 0.1400, 64.88 MPa, 0.1363 and 75.83 MPa respectively. According to Figures 15 - 18 it can be obtained that when σ H / σ V and σ h / σ H are equal to 2.4 and 0.33 respectively, △D’ LEFT , △S LEFT , △D’ RIGHT and △S RIGHT are equal to 0.0820, 53.70 MPa, 0.1368 and 56.00 MPa respectively. Substituting these values into formula (12) gives:

[0184]

[0185] Thus, the △D’ LEFT , △S LEFT , △D’ RIGHT and △S RIGHT of the vertical fracture F1 can be calculated to be equal to 0.0867, 54.59 MPa, 0.1368 and 57.59 MPa respectively. According to the extension length of 2036 m of the vertical fracture F1 (see Table 1), the width of the tectonic stress disturbance zone on the southeast side of the vertical fracture F1 can be calculated to be 278.52 m, with a strength of 57.59 MPa, while the width of the tectonic stress disturbance zone on the northwest side of the vertical fracture F1 is 176.52 m, with a strength of 54.59 MPa.

[0186] The technical features of the above embodiments can be combined arbitrarily. For the sake of brief description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

Claims

1. A method for determining the width and intensity of the structural stress disturbance zone on both sides of a vertical fault, characterized in that: include: Step S1, determine the study area and target strata, count the strike and plane extension length of the vertical faults in the study area, determine the key period of fault activity and the paleo-tectonic stress field environment; further determine the direction and intensity of the regional maximum horizontal principal stress, the intensity of the minimum horizontal principal stress, and the vertical stress intensity during the key period; Step S2, solving static rock mechanical parameters based on core, conventional logging and array acoustic logging data of the target layer; Step S3, constructing a geomechanical model and a mathematical model related to the sliding of the vertical fault along the strike, and conducting a numerical simulation test of the tectonic stress field to obtain the maximum horizontal principal stress intensity at each position; Step S4, in the simulation experiment, the distances from all nodes to the vertical fractures are calculated, the intervals are divided according to the distance and the research accuracy requirements, the interval length or the number of intervals is set, and the average value of the maximum principal stress of each interval is counted; the median of the interval is used to represent the overall distance of the nodes in the interval from the vertical fracture; Step S5, selecting the nearest intervals on both sides of the vertical fault, and determining the width and disturbance intensity of the tectonic stress disturbance zone on both sides of the vertical fault; Step S6, drawing a contour map of the tectonic stress disturbance zone width and disturbance intensity as the boundary conditions change, and judging the stress disturbance zone width and disturbance intensity based on the contour map.

2. The method for determining the width and intensity of the structural stress disturbance zone on both sides of the vertical fault according to claim 1, characterized in that: The step S2 comprises: Calculating dynamic rock mechanics parameters based on conventional logging and array acoustic logging data, wherein the dynamic rock mechanics parameters include dynamic Young's modulus and dynamic Poisson's ratio; Obtaining static rock mechanics parameters from rock mechanics experiments of core samples, wherein the static rock mechanics parameters include static Young's modulus and static Poisson's ratio parameters; The dynamic rock mechanics parameters and static rock mechanics parameters of the target strata in the study area are fitted to obtain the conversion model of dynamic and static rock mechanics parameters: E=10.003·e 0.0197Ed μ=0.0076·e 10.885μd Where, E represents the static Young's modulus; μ represents the static Poisson's ratio; E d represents dynamic Young's modulus; μ d represents the dynamic Poisson's ratio.

3. The method for determining the width and intensity of the structural stress disturbance zone on both sides of a vertical fault according to claim 1, characterized in that: The dynamic rock mechanical parameters calculated based on conventional logging and array acoustic logging data include: Based on conventional logging data, a conversion model between acoustic time difference AC and longitudinal time difference DTC is constructed; based on array acoustic logging data, a conversion model between longitudinal time difference DTC and shear time difference DTS is constructed; DTC and DTS are calculated using the two conversion models. The calculation formulas for the dynamic Young's modulus and dynamic Poisson's ratio of drilling in the target layer are: Among them, E d Represents dynamic Young's modulus, in GPa; μ d is the dynamic Poisson's ratio; Δt p is the longitudinal wave time difference DTC, in μs / ft; Δt s is the shear wave time difference DTS, with the unit of μs / ft; ρ is the density, with the unit of g / cm3.

4. The method for determining the width and intensity of the structural stress disturbance zone on both sides of a vertical fault according to claim 1, characterized in that: The step S3 comprises: According to the geological characteristics of the study area, a three-dimensional geomechanical model is constructed, which includes the location, strike, extension length of the vertical fault and the geometric characteristics of the target strata; the vertical fault is set as a discontinuity with a certain friction coefficient to simulate the relative sliding of the strata on both sides of the fault; The geomechanical model is converted into a mathematical model, and meshing is performed using finite element analysis software to divide the model into several units and nodes; Assign the static rock mechanics parameters obtained from step S2 to each unit in the mathematical model; set the boundary conditions and constraint conditions of the mathematical model according to the requirements of research accuracy; carry out numerical simulation tests of tectonic stress fields, and obtain the maximum horizontal principal stress intensity at each position of the model from the test results; Compare the simulation results with the actual geological data to verify the accuracy and reliability of the model.

5. The method for determining the width and intensity of the structural stress disturbance zone on both sides of a vertical fault according to claim 1, characterized in that: The step S4 comprises: Adjust the coordinate system of the model to make it consistent with the direction of the regional stress field, calculate the distance from each node in the model to the vertical fracture; and calculate the maximum value D of the distance from the node to the vertical fracture. MAX and minimum value D MIN ; Set the interval length D according to the research accuracy requirements INT ; The range of each interval is: [D MIN +(i-1) / n*(D MAX -D MIN ),D MIN +i / n*(D MAX -D MIN )] Where n represents the number of preset intervals; i represents the interval number; For each interval, record the maximum horizontal principal stress of each node in the interval, and calculate the average value of the maximum horizontal principal stress of the interval after multiple numerical simulation tests of the stress field; The median of the interval is used to represent the overall distance between the nodes in the interval and the vertical fracture; the median of the interval is: D MIN +(i-0.5) / m*(D MAX -D MIN )。 6. The method for determining the width and intensity of the structural stress disturbance zone on both sides of a vertical fault according to claim 1, characterized in that: The step S5 comprises: Get the median of each interval from step S4. For all the medians of the intervals that are less than or equal to 0, find the median of the interval with the smallest absolute value, which is recorded as D LEFT-MIN The corresponding average value of the horizontal maximum principal stress is recorded as S LEFT-MIN ; For all interval medians greater than or equal to 0, find the interval median with the smallest absolute value, recorded as D RIGHT-MIN The corresponding average value of the maximum horizontal stress is recorded as S RIGHT-MIN ; if D LEFT-MIN =D RIGHT-MIN =0, then the two intervals are actually the same interval, and the same interval is still used in subsequent analysis; For each interval, check the average value S of the maximum horizontal principal stress H (k,i) Whether one of the following conditions is met: [S H (k,i)-S H (k,i-1)]·[S H (k,i+1)-S H (k,i)]<0 Among them, S * Indicates the horizontal maximum principal stress threshold; S H represents the average value of the simulation results of the horizontal maximum principal stress; i represents the interval number; k represents the number of the simulation experiment; For the median of the interval less than or equal to 0, find the interval that meets the above conditions and record the median of the interval as D LEFT-MAX (k), the corresponding average value of the maximum horizontal principal stress is recorded as S LEFT-MAX (k); For the median of the interval greater than or equal to 0, find the interval that meets the above conditions and record the median of the interval as D RIGHT-MAX (k), the corresponding stress average value is recorded as S RIGHT-MAX (k); The intervals representing the maximum horizontal principal stress mutation on both sides of the vertical fault in all simulation tests are obtained, and the width and intensity of the tectonic stress disturbance zone on both sides of the vertical fault are calculated according to the following set of equations: When the median values ​​of the interval are both less than or equal to 0, the width and intensity of the tectonic stress disturbance zone are △D LEFT (k) and △S LEFT (k); When the median values ​​of the interval are greater than or equal to 0, the width and intensity of the tectonic stress disturbance zone are △D RIGHT (k) and △S RIGHT (k); △D LEFT (k) and △D RIGHT (k) are divided by the length of the vertical fault preset in the model to obtain the tectonic stress disturbance zone width coefficient △D' LEFT (k) and △D' RIGHT (k).

7. The method for determining the width and intensity of the structural stress disturbance zone on both sides of a vertical fault according to claim 1, characterized in that: The step S6 comprises: Plotting θ at different angles, △D' LEFT (k), △S LEFT (k), △D' RIGHT (k) and △S RIGHT (k) plane contour map, the horizontal axis of the plane contour map is the ratio of the horizontal maximum principal stress to the vertical stress σ H / σ V , the vertical axis is the ratio of the horizontal minimum principal stress to the horizontal maximum principal stress σ h / σ H ; where θ represents the angle between the strike of the vertical fault and the direction of the regional horizontal maximum principal stress; According to the location of the regional stress source, the width and intensity of the tectonic stress disturbance zone on this side are determined as △D RIGHT (k) and △S RIGHT (k); the other side is △D LEFT (k) and △S LEFT (k); Observe the trend in the contour map, determine the changing law of the width and intensity of the stress disturbance zone, and identify the boundary position of the stress disturbance zone, that is, the position of the stress mutation; according to the contour map, determine the width and intensity of the tectonic stress disturbance zone on both sides of the vertical fault; Calculate the disturbance band width coefficient △D' LEFT (k) and △D' RIGHT (k), and the disturbance intensity △S LEFT (k) and △S RIGHT (k).

8. The method for determining the width and intensity of the structural stress disturbance zone on both sides of a vertical fault according to claim 7, characterized in that: Determining the width and intensity of the tectonic stress disturbance zone on both sides of the vertical fault includes: The different θ values ​​are numbered as α1 to α t , where θ represents the angle between the strike of the vertical fault and the direction of the regional horizontal maximum principal stress; Get and α k The corresponding contour map, and obtain the △D' corresponding to the vertical fracture Fi from the contour map LEFT (Fi,α k ), △S LEFT (Fi,α k ), △D' RIGHT (Fi,α k ) and △S RIGHT (Fi,α k ); Get and α k+1 The corresponding contour map, and obtain the △D' corresponding to the vertical fracture Fi from the contour map LEFT (Fi,α k+1 ), △S LEFT (Fi,α k+1 ), △D' RIGHT (Fi,α k+1 ) and △S RIGHT (Fi,α k+1 ); Calculate the actual △D' corresponding to the vertical fracture Fi LEFT (Fi,θ i ), △S LEFT (Fi,θ i ), △D' RIGHT (Fi,θ i ) and △S RIGHT (Fi,θ i ), the calculation formula is: After calculating the actual △D of all fractures LEFT (Fi,θ i ) and △D RIGHT (Fi,θ i ), the actual width of the tectonic stress disturbance zone needs to be calculated based on the actual length of the fault. LEFT (Fi,θ i ) and △D' RIGHT (Fi,θ i ) is the disturbance band width coefficient.

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