A shale reservoir anti-suiting fracturing construction method

Abstract

The present application belongs to the field of unconventional oil and gas reservoir stimulation, and particularly relates to a shale reservoir casing deformation prevention fracturing construction method, comprising the following steps: S1, establishing a fracturing pre-horizontal well casing deformation risk evaluation mathematical model; S2, optimizing fracturing parameter design of the horizontal well casing deformation risk section; S3, establishing a horizontal well section multi-cluster fracturing fracture complex extension mode identification model; S4, optimizing temporary plugging and fracture control materials in the horizontal well section multi-cluster fracturing fracture and fracture mouth; S5, establishing a dynamic regulation and control strategy for preventing horizontal well casing deformation in the fracturing process. The present application performs static risk evaluation on the fracturing section where casing deformation may occur before fracturing, dynamically predicts and regulates casing deformation in the fracturing process based on horizontal well fracturing fracture complex extension mode identification, and comprehensively reduces the risk of casing deformation through static parameter design before fracturing and dynamic construction adjustment in the fracturing process, thereby improving the shale reservoir stimulation effect.

Description

Technical Field

[0001] This invention relates to the field of reservoir enhancement and stimulation, and more specifically, to a method for preventing casing-type fracturing in shale reservoirs. Background Technology

[0002] Deep shale formations are characterized by deep reservoir depth, high horizontal stress differences, and strong heterogeneity, exhibiting numerous complexly distributed macroscopic natural fracture zones. During hydraulic fracturing for reservoir stimulation, the horizontal well casing is highly susceptible to deformation and damage under the stress of concentrated perforation, high pumping pressure, and shear slippage within the natural fracture zones. This affects downhole operations such as bridge plug insertion and perforation coordination, increasing the economic cost of reservoir stimulation and severely hindering the large-scale, efficient development of shale gas.

[0003] Currently, the common solution to casing deformation in deep shale horizontal wells is to increase the length of the fracturing section and reduce the fluid volume, using a long-section, multi-cluster, small-scale fracturing design to prevent casing deformation. However, this fracturing process parameter selection is somewhat arbitrary. While it can reduce casing deformation to some extent, it fails to fully consider the geological characteristics of the casing deformation risk section and cannot conduct targeted fracturing construction design. Existing technologies that reduce the scale of reservoir stimulation to reduce casing deformation risk cannot assess and predict the horizontal casing deformation risk, nor can they effectively stimulate the reservoir in fracturing sections with casing deformation risk. Summary of the Invention

[0004] To address the aforementioned problems, this invention creatively provides a fracturing construction method for preventing casing deformation in shale reservoirs. It considers geological factors that induce horizontal well casing deformation, statically evaluates the risk level of casing deformation before fracturing, and adopts different fracturing construction design schemes for different risk levels. Furthermore, by constructing a complex extension pattern recognition model for multiple clusters of fracturing fractures within the horizontal well section, it identifies fracture extension during the fracturing process in real time. By adding temporary plugging materials within and at the fracture opening in a timely manner, it regulates the fracture extension pattern, achieving dynamic prediction and reduction of casing deformation risk during fracturing, and improving the production enhancement effect of shale reservoirs.

[0005] This application discloses a method for preventing variable pressure fracturing in shale reservoirs, characterized by the following steps:

[0006] S1. Establish a static evaluation model for the deformation risk section of the horizontal well casing before fracturing;

[0007] S2. Optimize the design of fracturing parameters for the deformation risk section of the horizontal well casing;

[0008] S3. Establish a model for recognizing complex extension patterns of multiple clusters of fracturing fractures within horizontal well sections;

[0009] S4. Design multiple clusters of fracture openings and temporary plugging materials within the fractures in the horizontal well section;

[0010] S5. Establish a dynamic control strategy to prevent deformation of the horizontal well casing during fracturing.

[0011] Further, step S1 establishes a static evaluation model for the deformation risk section of the horizontal well casing before fracturing, including:

[0012] (1) Based on the causes of horizontal well casing deformation, static evaluation indicators for the risk section of horizontal well casing deformation before fracturing are established using the length of the natural fracture zone, the angle between the natural fracture and the horizontal wellbore, and the cementing quality parameters of the horizontal well:

[0013] (2) Based on the characteristics of shale reservoirs and fracturing technology, and considering the influence weights of natural fracture zone length, natural fracture angle with horizontal wellbore, and horizontal well cementing quality on induced casing deformation, the casing deformation risk level of each fracturing section of the horizontal well is comprehensively evaluated, and the calculation formula is as follows:

[0014] ;

[0015] In the formula: F represents the comprehensive evaluation standard for casing deformation risk level; S represents the risk level of casing deformation, which is taken as I, II, III, IV, V from low to high;

[0016] Furthermore, step S2, which optimizes the fracturing parameter design for the deformation-risk section of the horizontal well casing, includes:

[0017] (1) Based on well logging, well logging and microseismic data, obtain the size and location distribution of natural fracture zones in shale reservoirs, and combine with the static evaluation model of casing deformation risk section of horizontal well to determine the casing deformation risk level of each fracture section of horizontal well;

[0018] (2) For the fracturing section of the horizontal well casing with risk level I~II, a multi-cluster fracturing construction design is adopted in the large-scale dense cutting section of the main fracturing section, and a complex fracturing fracture network is formed through the composite temporary plugging process of the fracture opening and the fracture interior to fully transform the reservoir.

[0019] (3) For the fracturing section of the horizontal well casing with risk level III to V, if the angle between the natural fracture and the horizontal wellbore is less than 45°, a multi-cluster fracturing construction design with large cluster spacing, high viscosity, and small scale within the section is adopted to promote the extension of hydraulic fractures through the natural fracture zone and to control the activation of the natural fracture zone by reducing filtration loss. If the angle between the natural fracture and the horizontal wellbore is greater than 45°, a multi-cluster fracturing construction design with close cutting and small scale within the section is adopted to control the overall length of the hydraulic fracture and reduce the risk of casing deformation caused by activating the natural fracture zone.

[0020] Furthermore, step S3 establishes a complex propagation pattern recognition model for multiple clusters of fracturing fractures within the horizontal well section, including:

[0021] (1) Collect on-site geological data, completion data, construction data and fracture monitoring data of horizontal well fracturing in shale reservoirs;

[0022] (2) By using numerical simulation, a model for the extension of multiple clusters of hydraulic fracturing fractures in the horizontal well section of shale reservoirs under the influence of natural fracture zones was established.

[0023] (3) Using geological data, well completion data and construction data from the fracturing site as input parameters, the fracture propagation trajectory under different construction conditions is obtained by inversion simulation through the multi-cluster fracturing fracture extension model in the horizontal well section of the shale reservoir, and the model is corrected by fracture monitoring data.

[0024] (4) Extract the variation characteristics of the fracturing construction curve and the extension characteristics of multiple fracturing fractures in the horizontal well section. Through machine learning training, establish a complex extension pattern recognition model for multiple fracturing fractures in the horizontal well section. The fracture extension patterns and pattern judgment criteria are as follows:

[0025] ;

[0026] In the formula: k This indicates the slope of the net pressure curve during construction. p net This represents the net pressure at the current moment; Q This indicates the current construction displacement. M This indicates the result of the crack propagation pattern judgment at the previous moment; f This refers to a pattern recognition model trained using machine learning.

[0027] Furthermore, step S4 involves designing multiple clusters of fracture openings and temporary plugging materials within the fractures in the horizontal well section, including:

[0028] (1) Based on the perforation parameters of the horizontal well, considering the erosion effect of proppant and temporary plugging material on the perforation hole, as well as the material deformation effect under the action of flowing pressure, a flexible deformable temporary plugging material is designed. It needs to effectively seal the perforation hole during the fracturing process and achieve harmless dissolution after the fracturing is completed. Alternatively, the shielding temporary plugging theory can be used to seal the perforation hole by simultaneously adding temporary plugging balls and temporary plugging agents to achieve the control of the extension of the horizontal well fracturing fracture.

[0029] (2) In order to further effectively control the extension of fractures, based on reservoir stress, reservoir temperature, construction scale and fracturing fluid physical parameters, a temporary plugging material for fracture control is designed so that it can accumulate at the hydraulic fracture front and form a low-permeability plugging zone during the fracturing process, meeting the requirements of low density, high strength and easy solubility.

[0030] Furthermore, step S5 establishes a dynamic control strategy to prevent deformation of the horizontal well casing during fracturing, including:

[0031] (1) During on-site fracturing operations, the complex extension pattern of multiple fracturing fractures in the horizontal well section is identified by the model and the wellhead construction pressure monitoring data, and the fracture extension pattern is calculated and judged in real time.

[0032] (2) When the current fracture extension mode is identified as rapid extension, the hydraulic fracture length increases rapidly. The hydraulic fracture is very likely to connect with the horizontal well of the adjacent well on the same platform and cause casing deformation. At this time, it is necessary to add temporary plugging material in the fracture to form a low-permeability sealing layer in the fracture tip area, control the growth of fracture length, reduce the risk of casing deformation of the horizontal well on the same platform, and realize dynamic prediction and control of the deformation of the horizontal well casing during the fracturing process.

[0033] (3) When the current fracture extension mode is identified as a few clusters of simple fracture extension, the rapid expansion speed of the dominant hydraulic fractures leads to a rapid increase in fracture length, which can also easily cause the casing of this horizontal well or other horizontal wells on the same platform to deform. At this time, it is necessary to add temporary plugging material to control the fracture opening, or add temporary plugging ball and temporary plugging agent at the same time to seal the perforation hole, change the fracture extension mode, reduce the risk of casing deformation caused by uncontrolled hydraulic fracture extension, and realize dynamic prediction and control of horizontal well casing deformation during fracturing.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] (1) This invention can assess the risk level of casing deformation in horizontal wells of shale reservoirs, which facilitates the design of targeted fracturing schemes;

[0036] (2) This invention uses the construction pressure data during the fracturing process to determine the crack propagation mode in real time, dynamically predict the possibility of casing deformation, and enhance the scientific nature of the application of temporary plugging and crack control materials at the crack opening and inside the crack.

[0037] (3) This invention combines static assessment and dynamic control to reduce the risk of horizontal well casing deformation, and controls the extension of horizontal well fracturing fractures by adding fracture control materials at the fracture opening and inside the fracture. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the implementation process of the present invention.

[0040] Figure 2Image showing the predicted fracture results of multi-level seismic fracture bodies within shale reservoirs.

[0041] Figure 3 Schematic diagram of static assessment results for casing deformation risk level in the fracturing section of a horizontal well.

[0042] Figure 4 Simulated fracture trajectory diagram of a multi-cluster fracturing fracture extension model within a horizontal well section of a shale reservoir.

[0043] Figure 5 Figure 1 shows the net pressure curve at the bottom of the well during the fracturing process of a horizontal well in a shale reservoir.

[0044] Figure 6 A schematic diagram showing the matching of net pressure curve variation characteristics with fracturing fracture propagation mode characteristics.

[0045] Figure 7 Figure showing monitoring results of horizontal well fracturing operations in shale reservoirs.

[0046] Figure 8 Image showing the results of fracture propagation pattern identification in horizontal wells of shale reservoirs. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the described 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.

[0048] It should be noted that in the description of this invention, the terms "lateral," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used solely for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0049] Reference Figure 1 This invention proposes a method for preventing variable pressure fracturing in shale reservoirs, which mainly includes the following five steps:

[0050] S1. Establish a static evaluation model for the deformation risk section of the horizontal well casing before fracturing;

[0051] S2. Optimize the design of fracturing parameters for the deformation risk section of the horizontal well casing;

[0052] S3. Establish a model for recognizing complex extension patterns of multiple clusters of fracturing fractures within horizontal well sections;

[0053] S4. Design multiple clusters of fracture openings and temporary plugging materials within the fractures in the horizontal well section;

[0054] S5. Establish a dynamic control strategy to prevent deformation of the horizontal well casing during fracturing.

[0055] Specifically, step S1 includes:

[0056] (1) Taking a horizontal shale well in southern Sichuan as an example, refer to Figure 2 Based on the fracture prediction results of the multi-level earthquake fracture body, it can be seen that the horizontal wellbore intersects with numerous natural fracture zones, which are important causes of wellbore deformation. Therefore, the length of the natural fracture zone, the angle between the natural fracture and the horizontal wellbore, and the cementing quality of the horizontal well are used as indicators for the static evaluation of the deformation risk section of the horizontal well casing before fracturing, and the corresponding risk levels are divided into five levels: I, II, III, IV, and V.

[0057] ;

[0058] ;

[0059] ;

[0060] (2) Based on the characteristics of shale reservoirs and fracturing technology, and considering the influence weights of natural fracture zone length, the angle between natural fractures and the horizontal wellbore, and the cementing quality of the horizontal well on induced casing deformation, the casing deformation risk level of each fracturing section of the horizontal well is comprehensively evaluated. In this embodiment, the comprehensive evaluation standard for casing deformation risk level is as follows:

[0061] ;

[0062] To reduce the impact of the casing deformation risk level assessment results on actual engineering projects, the risk level of the comprehensive evaluation is rounded up.

[0063] Specifically, step S2 includes:

[0064] (1) Based on well logging, well logging and microseismic data, obtain the size and location distribution of natural fracture zones in shale reservoirs. Combined with the static evaluation model of casing deformation risk section in horizontal wells, determine the casing deformation risk level of each fractured section of the horizontal well, and refer to Figure 3 The casing deformation risk level was assessed for four fracturing sections (A, B, C, and D) of the horizontal well.

[0065] (2) For the fracturing section of the horizontal well casing with a risk level of I~II, a multi-cluster fracturing construction design within a large-scale densely cut section of the main fracturing section is adopted. A complex fracturing network is formed through a composite temporary plugging process at the fracture opening and within the fracture to fully transform the reservoir. In this embodiment, refer to... Figure 3 For the fracturing section corresponding to area A, some fracturing design parameters include: cluster spacing of 8~10m, perforation clusters of 6~8, construction flow rate of 16~18 cubic meters / minute, fracturing fluid fracturing of 1~5mPa.s, fracturing fluid carrying sand of 10~30mPa.s, and the use of a mixed temporary plugging process of intra-fracture plugging particles and temporary plugging balls at the fracture opening.

[0066] (3) For the fracturing section of the horizontal well casing with a risk level of III to V, if the angle between the natural fracture and the horizontal wellbore is less than 45°, a multi-cluster fracturing construction design with large cluster spacing, high viscosity, and small scale within the section is adopted to promote the extension of hydraulic fractures through the natural fracture zone, and to activate the natural fracture zone by reducing filtration loss. In this embodiment, refer to Figure 3 For the fracturing sections corresponding to regions C and D, some fracturing design parameters include: cluster spacing of 15~20m, 3~4 perforation clusters, construction flow rate quickly increased to 16~18 cubic meters / minute, high viscosity fracturing fluid of 50~100mPa.s for fracturing, medium viscosity fracturing fluid of 20~50mPa.s for proppant carrying, and no temporary plugging process.

[0067] If the angle between the natural fracture and the horizontal wellbore is greater than 45°, a multi-cluster fracturing construction design with closely spaced small sections is adopted. By controlling the overall length of the hydraulic fracture, the risk of casing deformation caused by activating the natural fracture zone is reduced. In this embodiment, refer to... Figure 3 For the fracturing section corresponding to area B, some fracturing design parameters include: cluster spacing of 5~8m, perforation clusters of 7~10, construction flow rate of 14 cubic meters / minute, fracturing fluid fracturing of 1~5mPa.s, fracturing fluid carrying sand of 10~30mPa.s, and the use of a mixed temporary plugging process of intra-fracture plugging particles and temporary plugging balls at the fracture opening.

[0068] Specifically, step S3 includes:

[0069] (1) Collect on-site geological data, completion data, construction data and fracture monitoring data of horizontal well fracturing in shale reservoirs;

[0070] (2) A model of multiple clusters of hydraulic fractures extending in the horizontal well section of shale reservoir under the influence of natural fracture zones was established by numerical simulation method. In this embodiment, the numerical simulation method used is the boundary element method and the finite volume method.

[0071] (3) Using geological data, well completion data, and construction data from the fracturing site as input parameters, the fracture propagation trajectory under different construction conditions is obtained by inversion simulation using a multi-cluster fracturing fracture propagation model within the horizontal well section of the shale reservoir. The model is then corrected using fracture monitoring data. In this embodiment, the fracture trajectory distribution simulated by the multi-cluster fracturing fracture propagation model within the horizontal well section of the shale reservoir is referenced. Figure 4 .

[0072] (4) Extract the variation characteristics of the fracturing construction curve and the extension characteristics of multiple clusters of fracturing fractures in the horizontal well section. Through machine learning training, establish a complex extension pattern recognition model of multiple clusters of fracturing fractures in the horizontal well section. In this embodiment, firstly, the field construction pressure curve of the horizontal well that has been fracturing in the shale reservoir block is converted into the bottom hole net pressure curve (refer to the...). Figure 5 Then, segment the data and extract Δ for each time interval segment by segment. t The net pressure curve variation characteristics within the reservoir and the fracture propagation pattern obtained based on the multi-cluster fracturing fracture propagation model in the horizontal well section of the shale reservoir (refer to...) Figure 6 Finally, machine learning was used to obtain a recognition model for complex extension patterns of multiple clusters of fracturing fractures in the horizontal well section of this shale reservoir block. The discrimination features of different extension patterns of the selected shale horizontal well and the corresponding extension pattern results are as follows:

[0073] ;

[0074] In the formula: k This indicates the slope of the net pressure curve during construction. p net This represents the net pressure at the current moment; Q This indicates the current construction displacement. M This indicates the result of the crack propagation pattern judgment at the previous moment.

[0075] Specifically, step S4 includes:

[0076] (1) Based on the perforation parameters of the horizontal well, considering the erosion effect of proppant and temporary plugging material on the perforation hole, as well as the material deformation effect under the action of flowing pressure, a flexible deformable temporary plugging material is designed. It needs to effectively seal the perforation hole during the fracturing process and achieve harmless dissolution after the fracturing is completed. Alternatively, the shielding temporary plugging theory can be used to seal the perforation hole by simultaneously adding temporary plugging balls and temporary plugging agents to the perforation hole, thereby controlling the extension of the horizontal well fracturing fracture. In this embodiment, a flexible rope knot is used as the temporary plugging material.

[0077] (2) In order to further effectively control the extension of fractures, based on reservoir stress, reservoir temperature, construction scale and fracturing fluid physical parameters, a temporary plugging material is designed to be used in the fracture to form a low-permeability sealing zone at the hydraulic fracture front during the fracturing process, so as to meet the requirements of low density, high strength and easy dissolution. In this embodiment, temporary plugging particles are used as the temporary plugging material in the fracture.

[0078] Specifically, step S5 includes:

[0079] (1) During on-site fracturing operations, the complex extension pattern of multiple fracturing fractures in the horizontal well section is identified using a model that identifies complex extension patterns of multiple fracturing fractures and the wellhead construction pressure monitoring data. The fracture extension pattern is calculated and determined in real time. In this embodiment, the wellhead construction pressure monitoring data results are referenced. Figure 7 The crack propagation pattern recognition results obtained are referenced. Figure 8 .

[0080] (2) When the current fracture propagation mode is identified as a few clusters of simple fractures, the rapid propagation speed of the dominant hydraulic fractures leads to a rapid increase in fracture length, which can easily cause casing deformation in this horizontal well or other horizontal wells on the same platform. In this case, it is necessary to add temporary plugging material to control the fracture, or simultaneously add temporary plugging balls and temporary plugging agents to seal the perforation orifice, thereby changing the fracture propagation mode. In this embodiment, the time period for adding flexible knots is... Figure 8 Time period A.

[0081] (3) When the current fracture extension pattern is identified as rapid extension, the hydraulic fracture length increases rapidly. The hydraulic fracture can easily connect with the horizontal well of the adjacent well on the same platform, leading to casing deformation. In this case, it is necessary to add fracture control material to form a low-permeability plugging layer in the fracture tip area, controlling the fracture length growth and reducing the risk of casing deformation in the horizontal well on the same platform. In this embodiment, the time period for adding the fracture temporary plugging particles is... Figure 8 Time period B and time period C in the text.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the technical content. With respect to the technical solution of the present invention, some modifications or alterations can be made to the above-disclosed technical content to form equivalent embodiments. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preventing variable pressure fracturing in shale reservoirs, characterized in that, It includes the following steps: S1. Establish a static evaluation model for the deformation risk section of the horizontal well casing before fracturing; S2. Optimize the design of fracturing parameters for the deformation risk section of the horizontal well casing; S3. Establish a model for recognizing complex extension patterns of multiple clusters of fracturing fractures within horizontal well sections; S4. Design multiple clusters of fracture openings and temporary plugging materials within the fractures in the horizontal well section; S5. Establish a dynamic control strategy to prevent deformation of horizontal well casing during fracturing. Step S1 involves establishing a static evaluation model for the deformation risk section of the horizontal well casing before fracturing, including: (1) Based on the causes of horizontal well casing deformation, static evaluation indicators for the risk section of horizontal well casing deformation before fracturing are established using the length of the natural fracture zone, the angle between the natural fracture and the horizontal wellbore, and the cementing quality parameters of the horizontal well: (2) Based on the characteristics of shale reservoirs and fracturing technology, and considering the influence weights of natural fracture zone length, natural fracture angle with horizontal wellbore, and horizontal well cementing quality on induced casing deformation, the casing deformation risk level of each fracturing section of the horizontal well is comprehensively evaluated, and the calculation formula is as follows: ； In the formula: F represents the comprehensive evaluation standard for casing deformation risk level; S represents the risk level of casing deformation, which is I, II, III, IV, and V from low to high.

2. The method for preventing casing fracturing in shale reservoirs according to claim 1, characterized in that, Step S2 includes: (1) Based on well logging, well logging and microseismic data, obtain the size and location distribution of natural fracture zones in shale reservoirs, and combine with the static evaluation model of casing deformation risk section of horizontal well to determine the casing deformation risk level of each fracture section of horizontal well; (2) For the fracturing section of the horizontal well casing with risk level I~II, a multi-cluster fracturing construction design is adopted in the large-scale dense cutting section of the main fracturing section, and a complex fracturing fracture network is formed through the composite temporary plugging process of the fracture opening and the fracture interior to fully transform the reservoir. (3) For the fracturing section of the horizontal well casing with risk level III to V, if the angle between the natural fracture and the horizontal wellbore is less than 45°, a multi-cluster fracturing construction design with large cluster spacing, high viscosity, and small scale within the section is adopted to promote the extension of hydraulic fractures through the natural fracture zone and to control the activation of the natural fracture zone by reducing filtration loss. If the angle between the natural fracture and the horizontal wellbore is greater than 45°, a multi-cluster fracturing construction design with close cutting and small scale within the section is adopted to control the overall length of the hydraulic fracture and reduce the risk of casing deformation caused by activating the natural fracture zone.

3. The method for preventing casing fracturing in shale reservoirs according to claim 1, characterized in that, Step S3 includes: (1) Collect on-site geological data, completion data, construction data and fracture monitoring data of horizontal well fracturing in shale reservoirs; (2) By using numerical simulation, a model for the extension of multiple clusters of hydraulic fracturing fractures in the horizontal well section of shale reservoirs under the influence of natural fracture zones was established. (3) Using geological data, well completion data and construction data from the fracturing site as input parameters, the fracture propagation trajectory under different construction conditions is obtained by inversion simulation through the multi-cluster fracturing fracture extension model in the horizontal well section of the shale reservoir, and the model is corrected by fracture monitoring data. (4) Extract the variation characteristics of the fracturing construction curve and the extension characteristics of multiple fracturing fractures in the horizontal well section. Through machine learning training, establish a complex extension pattern recognition model for multiple fracturing fractures in the horizontal well section. The fracture extension patterns and pattern judgment criteria are as follows: ； In the formula: k This indicates the slope of the net pressure curve during construction. p net This represents the net pressure at the current moment; Q This indicates the current construction displacement. M This indicates the result of the crack propagation pattern judgment at the previous moment; f This refers to a pattern recognition model trained using machine learning.

4. The method for preventing casing fracturing in shale reservoirs according to claim 1, characterized in that, Step S4 includes: (1) Based on the perforation parameters of the horizontal well, considering the erosion effect of proppant and temporary plugging material on the perforation hole, as well as the material deformation effect under the action of flowing pressure, a flexible deformable temporary plugging material is designed. It needs to effectively seal the perforation hole during the fracturing process and achieve harmless dissolution after the fracturing is completed. Alternatively, the shielding temporary plugging theory can be used to seal the perforation hole by simultaneously adding temporary plugging balls and temporary plugging agents to achieve the control of the extension of the horizontal well fracturing fracture. (2) In order to further effectively control fracture extension, based on reservoir stress, reservoir temperature, construction scale and fracturing fluid physical parameters, a temporary plugging material is designed to control fractures, so that it can accumulate at the hydraulic fracture front and form a low-permeability sealing zone during fracturing, meeting the requirements of low density, high strength and easy dissolution.

5. The method for preventing casing fracturing in shale reservoirs according to claim 1, characterized in that, Step S5 includes: (1) During on-site fracturing operations, the complex extension pattern of multiple fracturing fractures in the horizontal well section is identified by the model and the wellhead construction pressure monitoring data, and the fracture extension pattern is calculated and judged in real time. (2) When the current fracture extension mode is identified as rapid extension, the hydraulic fracture length increases rapidly. The hydraulic fracture is very likely to connect with the horizontal well of the adjacent well on the same platform and cause casing deformation. At this time, it is necessary to add temporary plugging material in the fracture to form a low-permeability sealing layer in the fracture tip area, control the growth of fracture length, reduce the risk of casing deformation of the horizontal well on the same platform, and realize dynamic prediction and control of the deformation of the horizontal well casing during the fracturing process. (3) When the current fracture extension mode is identified as a few clusters of simple fracture extension, the rapid expansion speed of the dominant hydraulic fractures leads to a rapid increase in fracture length, which can also easily cause the casing of this horizontal well or other horizontal wells on the same platform to deform. At this time, it is necessary to add temporary plugging material to control the fracture opening, or add temporary plugging ball and temporary plugging agent at the same time to seal the perforation hole, change the fracture extension mode, reduce the risk of casing deformation caused by uncontrolled hydraulic fracture extension, and realize dynamic prediction and control of horizontal well casing deformation during fracturing.

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