A method for predicting a favorable area for fracturing near a deep shale fault

Abstract

The application discloses a method for predicting a fracturing favorable area near a deep shale fault, comprising the following steps: obtaining reservoir geological parameters and fault attribute parameters; establishing a near-fault in-situ stress field distribution calculation model of deep shale; characterizing a non-uniform stress field near the fault based on the near-fault in-situ stress field distribution calculation model of deep shale; determining a horizontal stress difference drop area and a stress turning area; and superimposing the horizontal stress difference drop area and the non-stress turning area to obtain the fracturing favorable area near the deep shale fault. The method combines basic theories such as elastic mechanics, fracture mechanics and displacement discontinuity method, considers the interference stress field generated by the fault, overcomes the fact that previous researches are usually based on a uniform stress field and cannot effectively predict the fracturing favorable area near the deep shale fault, and provides a better theoretical basis for the optimization of a fracture network fracturing favorable area near a deep shale fault structure and the optimization design of fracture network fracturing.

Description

Technical Field

[0001] This invention relates to a method for predicting favorable fracturing zones near deep shale faults, belonging to the field of shale gas development technology. Background Technology

[0002] Deep shale, due to its long burial time and multiple tectonic movements, exhibits significant uplift and erosion, resulting in the widespread development of complex structures such as faults. Studies show that faults formed by tectonic movements have a significant impact on in-situ stress in deep shale. Firstly, the direction and amplitude of stress deflection are closely related to the scale and nature of the fault. Excessive deflection angle of the maximum principal stress hinders proppant transport, increases fracturing pressure, and is detrimental to fracturing operations. Secondly, fault development affects the horizontal stress gradient. When the horizontal stress gradient is large, hydraulic fracturing fractures are distributed in parallel strips, but a fracture network cannot be formed, and the parallel fractures have poor connectivity, leading to poor overall fracturing results. Conversely, when the horizontal stress gradient is small, fractures extend in multiple directions, easily forming a fracture network and achieving good fracturing results. Under deep burial conditions, areas with gentle tectonic stress differences and relatively small stress gradients are favorable targets for deep shale gas exploration. Therefore, due to the influence of fault development, the "engineering sweet spot" zone with good hydraulic fracturing effect in deep shale is unlikely to appear on a large scale. Quickly and accurately identifying and predicting the "fracturing favorable zone" near deep shale faults is one of the keys to ensuring the high-quality development of deep shale gas.

[0003] Numerous studies by domestic and international scholars have analyzed the impact of fault structures on the geostress field. Zhang et al. proposed a new model for calculating the confining stress of reverse faults. This method can effectively determine the direction and magnitude of the stress field near the reverse fault plane in fault-block reservoirs and predict fracture morphology and propagation paths. However, this method is only applicable to reservoirs near reverse faults and is not suitable for deep shale reservoirs with complex structures. Li Jing et al. used COMSOL Multiphyics software to simulate and analyze the geostress distribution and influencing factors in multi-fault reservoirs in the Junggar Basin. They obtained the qualitative variation law of geostress magnitude with fault properties, but did not make a quantitative analysis of the range of favorable fracturing zones caused by geostress changes near faults. Lin B and Jin Y used three-dimensional seismic profiles to record the direction and magnitude of fault slip and used the Skempton coefficient to calculate pore pressure based on the predicted stress. This method can quantitatively predict the in-situ stress and pore pressure field of shale reservoirs with finite faults. However, this method cannot calculate the induced stress field generated by the fault, and therefore cannot accurately predict the favorable fracturing zone under the influence of the fault. Zhou et al. analyzed the geostress measurement results in the hydraulic fracturing well area near the fault and concluded that the distribution of the geostress field is affected by the spatial distribution of the fault in the strata, the dynamic mechanism of the fault, and the lithology of the strata. However, the analysis results cannot be used for quantitative calculation of the geostress field near the fault and accurate prediction of the favorable fracturing area.

[0004] In summary, qualitative studies on the geostress field of reservoirs, especially oil reservoirs, near faults are relatively comprehensive. However, these studies have not taken into account the characteristics of deep shale, such as strong structural deformation, large differences in brittleness, and complex geostress states. The simulation methods established cannot be used to accurately characterize the geostress field near multi-type and multi-attribute faults, and therefore cannot identify and predict favorable fracturing zones near complex faults in deep shale.

[0005] Therefore, there is an urgent need to establish a method for predicting favorable fracturing zones near deep shale faults. This will help to further improve the scientific nature and relevance of fracturing design for deep shale gas near faults, and improve the fracturing and production enhancement effect of deep shale near faults. Summary of the Invention

[0006] In order to overcome the shortcomings of the existing technology, the present invention aims to provide a method for predicting the favorable fracturing zone near deep shale faults.

[0007] The technical solution provided by this invention to solve the above-mentioned technical problems is: a method for predicting favorable fracturing zones near deep shale faults, comprising:

[0008] Obtain reservoir geological parameters and fault attribute parameters;

[0009] Establish a calculation model for the distribution of geostress field near the fault;

[0010] Based on the established calculation model of the stress field distribution near the fault, the non-uniform stress field of the strata near the fault is characterized, and vector diagrams of the distribution of the maximum horizontal principal stress, minimum horizontal principal stress, and horizontal stress difference near the fault are drawn.

[0011] Based on the vector diagram of the distribution of the maximum horizontal principal stress, the minimum horizontal principal stress, and the horizontal stress difference, the region where the current direction of the maximum horizontal principal stress at any location in the formation is inconsistent with the original direction of the maximum horizontal principal stress is identified as the stress turning region.

[0012] Determine the non-stress-shifting region based on the stress-shifting region;

[0013] Based on the maximum horizontal principal stress, minimum horizontal principal stress, and horizontal stress difference distribution vector diagram, the region where the current horizontal stress difference at any location in the formation is less than the original horizontal stress difference is the horizontal stress difference decrease region.

[0014] By superimposing the horizontal stress difference reduction region and the non-stress turning region, a favorable fracturing region can be obtained.

[0015] A further technical solution is that the reservoir geological parameters include the minimum horizontal principal stress, the maximum horizontal principal stress, the vertical principal stress, the Young's modulus of the formation rocks, and the Poisson's ratio of the formation rocks; the fault attribute parameters include the fault displacement, the fault length, the fault dip angle, the fault height, and the fault strike.

[0016] A further technical solution is that the calculation model for the distribution of the geostress field near the fault includes induced stress equations, strain calculation equations, boundary conditions, global coordinate and local coordinate transformation equations, and stress superposition equations.

[0017] A further technical solution is that the induced stress equation is:

[0018]

[0019]

[0020]

[0021] Δσ fault-zz =ν(Δσ xx +Δσ yy )

[0022] In the formula: Δσ fault-xx , Δσ fault-yy , Δσ fault-zz , Δσ fault-xy The induced stress component of the fault is represented in MPa; G represents the shear modulus of the reservoir rock in MPa; ν represents the Poisson's ratio of the reservoir rock, dimensionless; D n D tξ represents the horizontal and strike displacement of the fault, in meters (m); ξ represents the x-value transformed from the global coordinate system to the local coordinate system; ζ represents the y-value transformed from the global coordinate system to the local coordinate system; e and g are the cosines of the angles between the ζ-axis of the local coordinate system and the x-axis and y-axis of the global coordinate system, respectively; a j F3, F4, and F5 represent the partial derivative equations of the Papkovitch function;

[0023] The strain calculation equation is as follows:

[0024]

[0025]

[0026] In the formula: u x u y The value m represents the fault-induced strain components in the x and y directions. Indicates the fault normal displacement, in meters (m).

[0027] The boundary conditions are as follows:

[0028]

[0029] In the formula: (σ t ) i and (σ) n ) i The residual shear stress and residual normal stress, Pa and T, are respectively expressed as the stresses of fault element i in the local coordinate system. i P represents the residual tangential stress of the fault, Pa; i Represents the residual normal stress of the fault, in Pa; S i Represents the residual tangential strain of the fault, in Pa and C. i Represents the residual normal strain of the fault, in Pa;

[0030] The global coordinate to local coordinate transformation equation is:

[0031] ξ ij =e j (x i -x j )-g j (y i -y j )

[0032] ζ ij =g j (x i -x j )+e j (y i -y j )

[0033] The stress superposition equation is:

[0034]

[0035] Where: σ xx (0) σ yy (0) σ zz (0) σ xy (0) σ yz (0) σ xz (0) Represents the original geostress components, MPa; σ fault-xx σ fault-yy σ fault-zz σ fault-xy σ fault-yz σ fault-xz This represents the stress component near the fault, expressed in MPa.

[0036] A further technical solution is that the specific process of characterizing the non-uniform stress field of the strata near the fault is as follows: based on the established calculation model of the stress field distribution near the fault, the induced stress generated by the fault is calculated using the displacement discontinuity method, and the induced stress is superimposed with the original stress field to obtain the current stress field under the influence of the fault, thereby characterizing the non-uniform stress field distribution of the strata near the fault.

[0037] A further technical solution is that the equation for calculating the direction of the current maximum horizontal principal stress at any location in the formation is:

[0038] The direction of the current maximum horizontal principal stress at any location in the stratum is the direction of the first eigenvector (x1, y1, z1) of the stress tensor;

[0039]

[0040]

[0041]

[0042] In the formula: V represents the eigenvalue matrix of the current geostress tensor matrix, Pa; D represents the eigenvector matrix of the current geostress tensor matrix, m; eig represents the eigenvalue and eigenvector operators; σ1, σ2, σ3 represent the current principal stress values ​​of the formation (σ1>σ2>σ3), Pa; x1, y1, z1, x2, y2, z2, x3, y3, z3 represent the current principal stress direction vector component values ​​of the formation, m.

[0043] A further technical solution is that the equation for calculating the area of ​​the non-stress-directing region is:

[0044] S 非转 =SS 转

[0045] In the formula: S 非转 S represents the area of ​​the non-stressed turning region. 转 denoted as , where S is the area of ​​the stress shifting zone; and S is the area of ​​the reservoir region.

[0046] A further technical solution is that the current horizontal stress difference at any location in the formation is:

[0047] Δσ 当前 =σ fault-xx -σ fault-yy

[0048] In the formula: Δσ 当前 σ represents the current horizontal stress difference at any location in the formation. fault-xx σ fault-yy This represents the stress component near the fault, expressed in MPa.

[0049] A further technical solution is that the original horizontal stress difference at any location in the stratum is:

[0050]

[0051] In the formula: Δσ 原始 σ represents the original horizontal stress difference at any location in the formation; xx (0) σ yy (0) This represents the original geostress component, in MPa.

[0052] A further technical solution is to increase the area S of the favorable fracturing zone. 有利 The calculation equation is:

[0053] S 有利 =S 非转 ∩S 下降

[0054] In the formula: S 下降 S represents the area of ​​the region where the horizontal stress difference decreases; 有利 This represents the area of ​​the favorable fracturing zone.

[0055] The present invention has the following beneficial effects:

[0056] 1. This method is specifically designed for the mechanical characteristics of shale reservoirs near deep shale faults. It establishes a calculation model for the distribution of geostress field near deep shale faults, and thus proposes a method for predicting favorable fracturing zones near deep shale faults.

[0057] 2. Since this method is based on the theoretical model of elasticity, it uses the displacement discontinuity method to calculate the induced stress field generated by the fault, and superimposes it with the original geostress to calculate the distribution of the non-uniform stress tensor field in the formation. Simultaneously, combining the experience of shale gas horizontal well fracturing, principal stress deflection is a factor unfavorable to fracturing, while stress difference reduction is a factor favorable to fracturing. Therefore, the intersection of the stress difference reduction region and the non-stress deflection region is considered the favorable fracturing region. Thus, based on the actual fault development, the non-uniform stress difference near the fault can be characterized, and a map of the favorable fracturing region near the fault can be drawn, solving the problem of the lack of theoretical basis for fracturing near deep shale faults. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the calculation process of the present invention;

[0059] Figure 2 This is a fault distribution map of a deep shale well area according to the present invention;

[0060] Figure 3 This is a distribution map of geostress components near a fault in a deep shale well area according to the present invention;

[0061] Figure 4 This is a vector distribution diagram of the maximum and minimum horizontal principal stress directions near a fault in a deep shale well area according to the present invention;

[0062] Figure 5 This is a diagram showing the distribution of the maximum horizontal principal stress near a fault in a deep shale well area according to the present invention.

[0063] Figure 6 This invention relates to a stress reversal region (gray area) near a fault in a deep shale well area.

[0064] Figure 7 To discover the stress difference reduction region (gray area) near a fault in a deep shale well area;

[0065] Figure 8 To discover a favorable fracturing area (grey area) near a fault in a deep shale well area. Detailed Implementation

[0066] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0067] like Figure 1 As shown, a method for predicting favorable fracturing zones near deep shale faults according to the present invention includes the following steps:

[0068] Step 1: Obtain reservoir geological parameters and fault attribute parameters;

[0069] The reservoir geological parameters include the minimum horizontal principal stress, the maximum horizontal principal stress, the vertical principal stress, the Young's modulus of the formation rocks, and the Poisson's ratio of the formation rocks.

[0070] Fault attribute parameters include fault displacement, fault length, fault dip angle, fault height, and fault strike;

[0071] Step 2: Using the theory of elasticity, establish a calculation model for the distribution of the geostress field near the fault;

[0072] Step 3: Based on the established calculation model of the stress field distribution near the fault, characterize the non-uniform stress field of the strata near the fault, and draw vector diagrams of the distribution of the maximum horizontal principal stress, minimum horizontal principal stress, and horizontal stress difference near the fault.

[0073] The calculation model for the distribution of the geostress field near the fault includes the induced stress equation, strain calculation equation, boundary conditions, global coordinate and local coordinate transformation equation, and stress superposition equation.

[0074] The induced stress equation is:

[0075]

[0076]

[0077]

[0078] Δσ fault-zz =ν(Δσ xx +Δσ yy (4)

[0079] Where the partial derivative equation of the Papkovitch function F k for:

[0080]

[0081]

[0082]

[0083]

[0084] In the formula: Δσ fault-xx , Δσ fault-yy , Δσ fault-zz , Δσ fault-xy The induced stress component of the fault is represented in MPa; G represents the shear modulus of the reservoir rock in MPa; ν represents the Poisson's ratio of the reservoir rock, dimensionless; D nD t ξ represents the horizontal and strike displacement of the fault, in meters (m); ξ represents the x-value transformed from the global coordinate system to the local coordinate system; ζ represents the y-value transformed from the global coordinate system to the local coordinate system; e and g are the cosines of the angles between the ζ-axis of the local coordinate system and the x-axis and y-axis of the global coordinate system, respectively; a j F represents half the length of element j, m; k Let represent the partial derivative equation of the Papkovitch function, k∈{3-6}.

[0085] The strain calculation equation is as follows:

[0086]

[0087]

[0088] In the formula: u x u y The value m represents the fault-induced strain components in the x and y directions. Indicates the fault normal displacement, in meters (m).

[0089] The boundary conditions are as follows:

[0090]

[0091] In the formula: (σ t ) i and (σ) n ) i The residual shear stress and residual normal stress, Pa and T, are respectively expressed as the stresses of fault element i in the local coordinate system. i P represents the residual tangential stress of the fault, Pa; i Represents the residual normal stress of the fault, in Pa; S i Represents the residual tangential strain of the fault, in Pa and C. i Represents the residual normal strain of the fault, in Pa;

[0092] The global coordinate to local coordinate transformation equation is:

[0093] ξ ij =e j (x i -x j )-g j (y i -y j (12)

[0094] ζ ij =g j (x i -x j )+e j (y i -yj (13)

[0095] The stress superposition equation is:

[0096]

[0097] Where: σ xx (0) σ yy (0) σ zz (0) σ xy (0) σ yz (0) σ xz (0) Represents the original geostress components, MPa; σ fault-xx σ fault-yy σ fault-zz σ fault-xy σ fault-yz σ fault-xz This represents the stress component near the fault, expressed in MPa.

[0098] Step 4: Based on the maximum horizontal principal stress, minimum horizontal principal stress, and horizontal stress difference distribution vector diagram, determine the stress turning region as the area where the current maximum horizontal principal stress direction is inconsistent with the original maximum horizontal principal stress direction at any location in the formation.

[0099] Define the region where the horizontal stress difference decreases and the region where the stress turns.

[0100] Based on the original horizontal stress difference in the formation, the fault causes different changes in the maximum and minimum horizontal principal stresses, which may lead to a decrease in the horizontal stress difference in some areas. It is assumed that when the horizontal stress difference near the fault is less than the original horizontal stress difference, this is considered a "stress difference reduction region." It is further assumed that when the angle between the direction of the maximum horizontal principal stress near the fault and the direction of the original maximum horizontal principal stress exceeds 10°, this is considered a "stress reversal region," and the area outside this region is considered a "non-stress reversal region." For shale gas horizontal well fracturing, principal stress deflection is an unfavorable factor, while a decrease in stress difference is a favorable factor. Therefore, the intersection of the stress difference reduction region and the non-stress reversal region is considered a "favorable fracturing region."

[0101] The equation for calculating the direction of the maximum horizontal principal stress at any location in the stratum is as follows:

[0102] The direction of the maximum horizontal principal stress at any location in the stratum is the direction of the first eigenvector (x1, y1, z1) of the stress tensor.

[0103]

[0104]

[0105]

[0106] In the formula: V represents the eigenvalue matrix of the current geostress tensor matrix, Pa; D represents the eigenvector matrix of the current geostress tensor matrix, m; eig represents the eigenvalue and eigenvector operators; σ1, σ2, σ3 represent the current principal stress values ​​of the formation (σ1>σ2>σ3), Pa; x1, y1, z1, x2, y2, z2, x3, y3, z3 represent the current principal stress direction vector component values ​​of the formation, m.

[0107] The direction of the current maximum horizontal principal stress at any location in the formation, calculated using the above formula, is similar to the original maximum horizontal principal stress σ. xx (0) When the directions are inconsistent, this location is the stress reversal region;

[0108] Step 5: Determine the non-stress-shifting region based on the stress-shifting region;

[0109] Define the reservoir region area as S, therefore the area of ​​the non-stress-shifting region is S 非转 The calculation equation is:

[0110] S 非转 =SS 转 (18)

[0111] Step 6: Based on the maximum horizontal principal stress, minimum horizontal principal stress, and horizontal stress difference distribution vector diagram, determine the region where the current horizontal stress difference at any location in the formation is less than the original horizontal stress difference as the horizontal stress difference decrease region;

[0112] The original horizontal stress difference at any location in the stratum is:

[0113]

[0114] Due to the fault, the current horizontal stress difference at this location is:

[0115] Δσ 当前 =σ fault-xx -σ fault-yy (20)

[0116] If Δσ 当前 <Δσ 原始 At that time, the location is in the region where the horizontal stress difference decreases.

[0117] Step 7: Superimpose the horizontal stress difference reduction region and the non-stress turning region to obtain the favorable fracturing region;

[0118] The equation for calculating the area of ​​the favorable fracturing zone is as follows:

[0119] S 有利 =S 非转 ∩S 下降 (twenty one)

[0120] In the formula: S 下降 S represents the area of ​​the region where the horizontal stress difference decreases; 有利 This represents the area of ​​the favorable fracturing zone. Example

[0121] The actual parameters of a deep shale gas well near a typical fault are shown in Table 1. Based on... Figure 1 Process to perform instance calculations:

[0122] Table 1. Actual parameters of a deep shale gas well near a fault.

[0123]

[0124]

[0125] First, based on the theory of elasticity, a calculation model for the stress field distribution near the fault is established to characterize the non-uniform stress field distribution in the strata near the fault.

[0126] The specific steps are as follows: solve equations (1) to (14) simultaneously, use the displacement discontinuity method to calculate the induced stress generated by the fault, superimpose the induced stress with the original geostress field to obtain the current geostress field under the influence of the fault, thereby characterizing the non-uniform stress field distribution of the strata near the fault.

[0127] Subsequently, a vector diagram of the distribution of maximum horizontal principal stress, minimum horizontal principal stress, and horizontal stress difference in the deep shale reservoir near the fault was drawn:

[0128] The specific steps are as follows: Based on the calculated current geostress field under the influence of the fault, a vector diagram of the maximum horizontal principal stress, minimum horizontal principal stress, and horizontal stress difference distribution of the deep shale reservoir near the fault can be drawn.

[0129] Subsequently, the non-stress turning region and the horizontal stress difference decreasing region were identified, and the horizontal stress difference decreasing region and the non-stress turning region were superimposed to obtain the favorable fracturing region:

[0130] The specific steps are as follows: solve equations (15) to (17) simultaneously, calculate the direction of the maximum horizontal principal stress at any location in the stratum, and determine the area S of the stress turning region. 转 (Results are as follows) Figure 6 (As shown in the gray area), the area S of the non-stress turning region is calculated using equation (18). 非转 (Results are as follows) Figure 6 (As shown in the black part);

[0131] Solve the simultaneous equations (19) to (20) to calculate the area S of the stress difference decrease region. 下降 (Results are as follows) Figure 7 (As shown in the gray area);

[0132] Based on equation (21), calculate the area S of the favorable fracturing zone. 有利 (Results are as follows) Figure 8 (As shown in the gray area).

[0133] The above description is not intended to limit the present invention in any way. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for predicting favorable fracturing zones near deep shale faults, characterized in that, include: Obtain reservoir geological parameters and fault attribute parameters; Establish a calculation model for the distribution of geostress field near the fault; Based on the established calculation model of the stress field distribution near the fault, the non-uniform stress field of the strata near the fault is characterized, and vector diagrams of the distribution of the maximum horizontal principal stress, minimum horizontal principal stress, and horizontal stress difference near the fault are drawn. Based on the vector diagram of the distribution of the maximum horizontal principal stress, the minimum horizontal principal stress, and the horizontal stress difference, the region where the current direction of the maximum horizontal principal stress at any location in the formation is inconsistent with the original direction of the maximum horizontal principal stress is identified as the stress turning region. Determine the non-stress-shifting region based on the stress-shifting region; Area of ​​non-stress turning region The calculation equation is as follows: In the formula: The area of ​​the non-stress turning region; The area of ​​the stress reversal zone; For reservoir region Based on the maximum horizontal principal stress, minimum horizontal principal stress, and horizontal stress difference distribution vector diagram, the region where the current horizontal stress difference at any location in the formation is less than the original horizontal stress difference is the horizontal stress difference decrease region. The current horizontal stress difference at any location in the formation is: In the formula: This represents the current horizontal stress difference at any location within the stratum. , This represents the stress component near the fault, expressed in MPa. The original horizontal stress difference at any location in the strata is: In the formula: The original horizontal stress difference at any location in the stratum; , Represents the original geostress component, in MPa; By superimposing the horizontal stress difference reduction region and the non-stress turning region, a favorable fracturing region can be obtained; Area of ​​favorable fracturing zone S 有利 The calculation equation is: S 有利 = S 非转 ∩ S 下降 In the formula: S 下降 The area of ​​the region where the horizontal stress difference decreases; S 有利 This represents the area of ​​the favorable fracturing zone.

2. The method for predicting favorable fracturing zones near deep shale faults according to claim 1, characterized in that, The reservoir geological parameters include the minimum horizontal principal stress, maximum horizontal principal stress, vertical principal stress, Young's modulus of the formation rocks, and Poisson's ratio of the formation rocks; the fault attribute parameters include fault displacement, fault length, fault dip angle, fault height, and fault strike.

3. The method for predicting favorable fracturing zones near deep shale faults according to claim 1, characterized in that, The calculation model for the stress field distribution near the fault includes the induced stress equation, strain calculation equation, boundary conditions, global coordinate and local coordinate transformation equation, and stress superposition equation.

4. The method for predicting favorable fracturing zones near deep shale faults according to claim 3, characterized in that, The induced stress equation is: In the formula: , , , Represents the induced stress components of the fault, in MPa; G This represents the shear modulus of the reservoir rock, expressed in MPa. This represents the Poisson's ratio of the reservoir rock, and is dimensionless. , The horizontal displacement and strike displacement of the fault are expressed in meters (m). ξ Represents the global coordinate system x Values ​​transformed to the local coordinate system; Represents the global coordinate system y Values ​​transformed to the local coordinate system; and Local coordinate systems Axis and Global Coordinate System x shaft and y The cosine of the angle between the axes; F 3. F 4. F 5 represents the partial derivative equation of the Papkovitch function; The strain calculation equation is as follows: In the formula: u x , u y This indicates that fault-induced x direction and y The strain component in the direction, m; û n Indicates the fault normal displacement, in meters (m). The boundary conditions are as follows: In the formula: ( σ t ) i and( σ n ) i Indicates fault i The residual shear stress and residual normal stress experienced by the element in the local coordinate system, in Pa; T i This represents the residual tangential stress of the fault, in Pa; P i This represents the residual normal stress of the fault, in Pa; S i This represents the residual tangential strain of the fault, in Pa; C i Represents the residual normal strain of the fault, in Pa; The global coordinate to local coordinate transformation equation is: The stress superposition equation is: In the formula: σ xx (0) , σ yy (0) , σ zz (0) , σ xy (0) , σ yz (0) , σ xz (0) Represents the original geostress component, in MPa; σ fault-xx , σ fault-yy , σ fault-zz , σ fault-xy , σ fault-yz , σ fault-xz This represents the stress component near the fault, expressed in MPa.

5. The method for predicting favorable fracturing zones near deep shale faults according to claim 1, characterized in that, The specific process for characterizing the non-uniform stress field of the strata near the fault is as follows: Based on the established calculation model of the stress field distribution near the fault, the induced stress generated by the fault is calculated using the displacement discontinuity method. The induced stress is superimposed with the original stress field to obtain the current stress field under the influence of the fault, thereby characterizing the non-uniform stress field distribution of the strata near the fault.

6. The method for predicting favorable fracturing zones near deep shale faults according to claim 1, characterized in that, The equation for calculating the direction of the current horizontal maximum principal stress at any location in the strata is: The direction of the current maximum horizontal principal stress at any location in the formation is the first eigenvector of the stress tensor. x 1, y 1, z 1) Direction; In the formula: Pa represents the eigenvalue matrix of the current geostress tensor matrix. m represents the eigenvector matrix of the current geostress tensor matrix; eig represents the eigenvalue and eigenvector operators; σ 1. σ 2. σ 3 represents the current principal stress value of the formation. σ 1> σ 2> σ 3, Pa; x 1. y 1. z 1. x 2. y 2. z 2. x 3. y 3. z 3 represents the current principal stress direction vector component value, m.

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