Kilometer directional hydraulic fracturing hole protecting device

Abstract

The invention discloses a kilometer directional hydraulic fracturing hole protecting device which comprises a grouting pump, a slurry container and a conveying pipeline, the grouting pump is communicated with the slurry container, the first end of the conveying pipeline is connected with the grouting pump, the second end of the conveying pipeline extends into a directional drill hole for grouting, and the grouting pump is communicated with the slurry container. The end portion of the second end is arranged to be a T-shaped opening, and it is ensured that grout is sprayed out in the circumferential direction of the drill opening. The kilometer directional hydraulic fracturing hole protecting device has the advantage of being good in hole protecting effect.

Description

Technical Field

[0001] This invention relates to the field of fracturing borehole protection technology, and in particular to a kilometer-long directional hydraulic fracturing borehole protection device and method. Background Technology

[0002] Kilometer-long directional hydraulic fracturing technology is mainly used in the fracturing of hard roofs. In this process, drilling begins from the initial borehole location. Due to geological conditions, borehole collapse often occurs when drilling reaches softer mudstone strata, hindering drilling progress and preventing normal hydraulic fracturing. Drilling continues after washing away the mudstone fracture zone. However, this washing process leads to an increasing area of ​​collapsed sections and a gradual decrease in borehole stability. Even if directional drilling is successfully implemented, the instability of the surrounding rock during later fracturing stages prevents proper pressure maintenance in the fracturing zone, resulting in poor fracturing performance. Summary of the Invention This invention is based on the inventor's discoveries and understanding of the following facts and problems: The rock mass at the borehole location lacks effective protection and reinforcement.

[0003] The present invention aims to at least partially solve one of the technical problems in the related art.

[0004] Therefore, embodiments of the present invention propose a kilometer-long directional hydraulic fracturing borehole protection device, comprising a grouting pump, a grout container, and a delivery pipeline. The grouting pump is connected to the grout container, the first end of the delivery pipeline is connected to the grouting pump, and the second end of the delivery pipeline extends into the directional borehole for grouting. The end of the second end is configured with a T-shaped opening to ensure that the grout is ejected along the circumferential direction of the borehole.

[0005] The embodiments of the present invention have the advantages and technical effects of good borehole protection. This application ensures borehole integrity and prevents secondary borehole collapse.

[0006] In some embodiments, a guide cone is provided at the front end of the T-shaped opening to reduce scratching and collision with the hole wall.

[0007] An embodiment of the present invention proposes a method for maintaining a kilometer-long directional hydraulic fracturing borehole, comprising the following steps: Install the grouting pump, prepare the grouting slurry, determine the cross-hole area, and send the delivery pipeline into the directional borehole; Start the grouting pump to perform grouting. Stop grouting when the grout flows out from the borehole wall and wait for the grout to solidify. Branch boreholes are drilled in the area surrounding the directional borehole; Grouting is performed on the branch boreholes. Grouting is stopped when the grout flows out from the borehole wall and the grout solidifies.

[0008] In some embodiments, the method further includes cross-hole area positioning, which determines the location and extent of the cross-hole area based on changes in drilling resistance and the state of slurry return within the hole.

[0009] In some embodiments, during the grouting process, the grouting pressure is gradually increased to inject cement grout into the cross-hole area under high pressure. During the grouting process, the grout flow rate and pressure changes are monitored in real time using a flow meter.

[0010] In some embodiments, if the mudstone around the main borehole is severely fractured, the fissures are densely developed, and the area spanning the borehole is large, the distance between the branch borehole and the directional borehole is controlled at 1.5-3m. If the rock mass around the main borehole is intact, the mudstone interlayers are thin, and the fissures are not developed, the distance between the branch borehole and the directional borehole is controlled at 3-5m.

[0011] In some embodiments, the effective diffusion radius of the grout after directional drilling is a, and the distance between the branch borehole and the directional borehole is 1.5a-2a, ensuring that the diffusion range of adjacent branch boreholes and the diffusion range of the directional borehole form an overlapping area, and the width of the overlapping area is greater than or equal to 0.5m.

[0012] In some embodiments, the spacing between the branch borehole and the directional borehole is matched with the range of fracturing fracture propagation, and the spacing does not exceed 1.5 times the expected propagation length of the fracturing fracture.

[0013] In some embodiments, the branch boreholes are evenly distributed in a ring shape at an angle, centered on the directional borehole and in a plane perpendicular to the axis of the directional borehole.

[0014] In some embodiments, the cross-hole area crushing is divided into light crushing, medium crushing, and heavy crushing. Construction parameters are selected according to the crushing level of the cross-hole area. Light crushing is the same as the directional drilling construction parameters; for medium crushing, the grouting hole sections are densified to increase the grout solidification speed; for heavy crushing, the grout is injected in sections to ensure reinforcement strength.

[0015] This application has the following advantages: it has strong precision and adaptability. By dividing the cross-hole area into three levels of fracturing—light, medium, and heavy—and matching them with differentiated construction parameters, it can achieve reinforcement as needed. This avoids over-construction in lightly fracturing areas caused by uniform processes, and also solves the problem of incomplete reinforcement in medium and heavy fracturing areas. At the same time, it scientifically sets the spacing between branch boreholes and the uniform ring distribution form by combining geological conditions (rock mass integrity, fracture development), effective grout diffusion radius, and fracturing crack propagation range, ensuring that the reinforcement layout is precisely matched with the actual working conditions and subsequent fracturing needs.

[0016] The construction is scientifically sound. The grouting process adopts a gradual pressurization to avoid the expansion of surrounding rock fissures by high pressure impact. It can promptly respond to abnormal working conditions such as pipeline blockage and grout leakage. The structure of the T-shaped port and guide cone of the delivery pipeline takes into account both the uniform circumferential spraying of grout and the protection of the hole wall, reducing the secondary disturbance to the surrounding rock during construction and further improving the controllability of construction.

[0017] Significantly improving rock mass stability, in moderately to severely fractured areas, the techniques of densifying grouting sections, increasing grout solidification speed, and segmented grouting, combined with the three-dimensional reinforcement network formed by branch holes and main holes, effectively fill the fractures in the cross-hole area, suppress secondary hole collapse, and greatly improve the integrity and bearing capacity of the surrounding rock of the borehole; the design of the guide cone and the gradual pressure increase grouting further reduces the disturbance of the fragile borehole wall during construction, reducing the risk of hole collapse from the source.

[0018] To ensure the smooth operation of hydraulic fracturing, a continuous and complete reinforcement zone provides a stable rock environment for subsequent fracturing, ensuring normal pressure maintenance during the fracturing process. The annular uniform distribution and spacing design of the branch holes provide a comprehensive channel for the fracturing fractures to expand, promote the interconnection of fractures to form a three-dimensional fracturing network, and prevent fractures from being interrupted or deviated due to encountering unreinforced weak areas, thus significantly improving the coverage and uniformity of regional fracturing. Attached Figure Description

[0019] Figure 1 This is a schematic flowchart of the kilometer-long directional hydraulic fracturing borehole protection method according to an embodiment of the present invention. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0021] An embodiment of the present invention proposes a kilometer-long directional hydraulic fracturing borehole protection device, comprising a grouting pump, a grout container, and a delivery pipeline. The grouting pump is connected to the grout container, the first end of the delivery pipeline is connected to the grouting pump, and the second end of the delivery pipeline extends into the directional borehole for grouting. The end of the second end is configured with a T-shaped opening to ensure that the grout is ejected along the circumferential direction of the borehole.

[0022] The connection between the grouting pump and the grout container ensures a continuous and stable supply of grout, preventing discontinuous reinforcement due to grout interruptions during grouting. This guarantees the continuity and efficiency of borehole protection operations. The reliable connection between the first end of the delivery pipeline and the grouting pump ensures sealing performance during high-pressure grouting, preventing pressure loss and material waste caused by grout leakage. The structure extending into the directional borehole at the second end is suitable for long-distance construction needs of kilometer-level directional boreholes, allowing precise delivery of grout to the core area of ​​the cross-hole collapse, ensuring direct action on the affected areas. The T-shaped opening at the second end of the delivery pipeline guides the grout to be sprayed evenly around the borehole opening, achieving 360-degree coverage of the borehole wall and surrounding fractures without dead angles. This avoids reinforcement blind spots caused by unidirectional grouting, effectively improving the uniformity and density of grout filling, thereby enhancing the integrity and stability of the surrounding rock, suppressing the risk of secondary borehole collapse, and laying the foundation for normal pressure maintenance, fracture propagation, and overall fracturing effect improvement in subsequent hydraulic fracturing operations.

[0023] The advantages and technical effects brought about by the independent claims according to the embodiments of the present invention.

[0024] In some embodiments, a guide cone is provided at the front end of the T-shaped opening to reduce scratching and collision with the hole wall.

[0025] Specifically, the guide cone can play a guiding role during the advancement of the delivery pipeline, greatly reducing the scraping and collision between the pipeline and the borehole wall, avoiding secondary disturbance to the already fragile borehole wall, preventing new borehole collapses or expanding the original fracture area, while helping the delivery pipeline to more smoothly adapt to the turning path and long-distance advancement requirements of directional drilling, further ensuring the accuracy and safety of grouting operations, and ultimately enhancing the integrity and stability of the surrounding rock of the borehole.

[0026] An embodiment of the present invention proposes a method for maintaining a kilometer-long directional hydraulic fracturing borehole, comprising the following steps: Install the grouting pump, prepare the grouting slurry, determine the cross-hole area, and introduce the delivery pipeline into the directional borehole. When installing the grouting pump, ensure the equipment is securely fixed and the pipeline is well-sealed, adapting to the high-pressure grouting requirements of kilometer-long directional boreholes. When preparing the grouting slurry, a quick-setting agent can be added according to geological conditions to balance slurry fluidity and setting strength. Start the grouting pump and begin grouting. Stop grouting when the grout flows out of the borehole wall and wait for it to solidify. Slowly insert the delivery pipeline into the borehole, ensuring the pipeline accurately reaches the reinforcement area. Branch boreholes are drilled in the area surrounding the directional borehole; Grouting is performed on the branch boreholes. Grouting stops when the grout flows out of the borehole wall and is allowed to solidify. Allowing the grout to solidify allows the reinforced structure to develop sufficient strength, preventing borehole collapse during subsequent construction. The directional drilling and branch boreholes form a three-dimensional reinforcement network, comprehensively improving the integrity and stability of the surrounding rock mass. In some embodiments, the method further includes cross-hole area positioning, which determines the location and extent of the cross-hole area based on changes in drilling resistance and the state of slurry return within the hole.

[0027] Specifically, real-time monitoring of resistance changes and grout return status during drilling provides a dual basis for determining the location of the cross-hole area. During normal drilling, the rock mass integrity is good, the drilling resistance remains stable, and the grout return volume and concentration are uniform. However, when the borehole encounters a mudstone fracture zone that causes a cross-hole, the fractured rock mass cannot provide stable support, leading to a sudden increase or frequent fluctuation in drilling resistance. At the same time, the fractured fissures will absorb some grout, significantly reducing the grout return volume. If the cross-hole area is severely fractured, there will also be phenomena such as grout carrying rock fragments and uneven concentration. Combining these two indicators can pinpoint the specific location and extension range of the cross-hole area. This not only avoids material waste and reinforcement blind spots caused by blind grouting, allowing subsequent grouting of the main borehole and branch boreholes to be targeted at the core area of ​​the hidden danger, but also provides accurate geological reference for the spacing and distribution planning of branch boreholes. This ensures that branch boreholes can be scientifically arranged around the cross-hole risk area, improving the overall reinforcement effect of the surrounding rock and enabling the smooth progress of subsequent hydraulic fracturing operations.

[0028] In some embodiments, during the grouting process, the grouting pressure is gradually increased to inject cement grout into the cross-hole area under high pressure. During the grouting process, the grout flow rate and pressure changes are monitored in real time using a flow meter.

[0029] Specifically, during the grouting process, the pressure is gradually increased to avoid direct impact of the initial high pressure on the already fractured surrounding rock in the borehole area, preventing further expansion of fractures or triggering new borehole collapses. The grout first slowly penetrates shallow fractures, then gradually penetrates deeper into finer fractures as the pressure increases, achieving comprehensive filling from the outside in. High-pressure injection provides sufficient kinetic energy to the cement grout, effectively overcoming the resistance of long-distance transport and the seepage resistance of fractured rock masses, ensuring that the grout fully wets and fills all types of fractures in the borehole area, forming a dense and coherent reinforced structure. By monitoring the grout flow rate and pressure changes in real time using a flow meter, the grouting process can be dynamically tracked: when the pressure steadily increases and the flow rate remains stable, it indicates that the grout is filling the fractures in an orderly manner and the grouting status is normal; if the pressure rises sharply and the flow rate drops sharply, it may be due to pipeline blockage or local fracture saturation, requiring timely investigation or pressure adjustment; if the pressure is too low and the flow rate is too high, it may be due to grout leakage or the cross-hole range exceeding the prediction, which can be optimized by increasing the grout concentration or extending the grouting time to avoid material waste caused by blind grouting, timely avoidance of incomplete reinforcement caused by abnormal grouting, and timely assurance that the reinforcement effect of the cross-hole area meets the standards, providing support for subsequent rock mass stability and fracturing pressure maintenance.

[0030] In some embodiments, if the mudstone around the main borehole is severely fractured, the fissures are densely developed, and the area spanning the borehole is large, the distance between the branch borehole and the directional borehole is controlled at 1.5-3m. If the rock mass around the main borehole is intact, the mudstone interlayers are thin, and the fissures are not developed, the distance between the branch borehole and the directional borehole is controlled at 3-5m.

[0031] Specifically, when the mudstone surrounding the main borehole is severely fractured, with dense fissures and a large span across the borehole, a narrower spacing of 1.5-3m ensures that the grout from the branch holes overlaps sufficiently with the reinforced area of ​​the main borehole, allowing the grout to fully cover the dense fissures and the potential for large-scale borehole collapse, avoiding reinforcement blind spots. At the same time, the densely distributed branch holes form a three-dimensional support network, rapidly improving the integrity and bearing capacity of the fractured surrounding rock. When the rock mass surrounding the main borehole has good integrity, thin mudstone interlayers, and undeveloped fissures, a wider spacing of 3-5m satisfies the effective connection of the grout diffusion range, achieving full-area reinforcement without the need for additional drilling, reducing additional disturbance to the rock mass during drilling, lowering the risk of fissure development due to excessive drilling, reducing equipment investment and construction period, and balancing reinforcement effect with construction economy. Differentiated spacing control allows the branch borehole layout to better fit the actual geological conditions, avoiding insufficient reinforcement or waste of resources caused by uniform spacing. It enhances the synergistic reinforcement effect of directional boreholes, i.e., main boreholes and branch boreholes, and provides a stable rock mass foundation for the pressure holding requirements and fracture propagation of subsequent hydraulic fracturing.

[0032] In some embodiments, the effective diffusion radius of the grout after directional drilling is a, and the distance between the branch borehole and the directional borehole is 1.5a-2a, ensuring that the diffusion range of adjacent branch boreholes and the diffusion range of the directional borehole form an overlapping area, and the width of the overlapping area is greater than or equal to 0.5m.

[0033] Specifically, setting the branch borehole spacing based on the effective diffusion radius of the grout allows for more precise branch borehole placement. Using the actual effective diffusion radius *a* after directional drilling grouting as a benchmark, the spacing between branch boreholes and directional boreholes is controlled between 1.5a and 2a. This avoids excessive grout overlap due to insufficient spacing (reducing material waste and stress concentration risks on the borehole wall), while also preventing reinforced faults caused by excessive spacing. An overlap zone width of no less than 0.5m ensures a tight connection and fusion of the grout diffusion range in the main borehole and each branch borehole, forming a continuous reinforced zone without dead zones, rather than isolated and dispersed reinforced areas, significantly improving the overall integrity and bearing capacity of the rock mass. Spacing based on grout diffusion patterns overcomes the limitations of relying solely on geological experience, allowing for precise matching between the reinforced area and the actual grout's effectiveness. This strengthens the synergistic reinforcement effect of the main borehole and branch boreholes, providing a uniform and stable rock mass environment for pressure maintenance and smooth fracture propagation during subsequent hydraulic fracturing, and avoiding fracturing failure caused by discontinuous reinforcement.

[0034] In some embodiments, the spacing between the branch borehole and the directional borehole is matched with the range of fracturing fracture propagation, and the spacing does not exceed 1.5 times the expected propagation length of the fracturing fracture.

[0035] Specifically, matching the spacing between branch boreholes and directional boreholes with the fracturing fracture propagation range achieves synergy between borehole reinforcement and subsequent hydraulic fracturing depth, avoiding a disconnect between reinforcement effectiveness and fracturing requirements. Limiting the spacing to no more than 1.5 times the expected fracture propagation length ensures that the reinforced areas of the main borehole and branch boreholes precisely cover the potential fracture extension range. This allows the fracture to smoothly extend from the directional borehole to the reinforced areas of each branch borehole during fracturing, preventing interruptions or deviations due to unreinforced weak surrounding rock caused by excessive spacing, and avoiding construction redundancy due to insufficient spacing. The reinforced area acts as a "guiding channel" for fracture propagation. The continuous and stable reinforced zone formed by the main borehole and branch boreholes provides a uniform stress environment for the fracture, promoting interconnection and the formation of a complete fracturing network, rather than isolated, scattered fractures. This significantly improves the coverage and effectiveness of regional fracturing. Setting the spacing based on the fracturing target ensures the smooth progress of fracturing operations, leverages the synergistic effect of main boreholes and branch boreholes, and avoids resource waste and excessive disturbance of the rock mass caused by blindly arranging branch boreholes.

[0036] In some embodiments, the branch boreholes are evenly distributed in a ring shape at an angle, centered on the directional borehole and in a plane perpendicular to the axis of the directional borehole.

[0037] Specifically, by using a directional borehole as the center and distributing branch boreholes at uniform angles in a plane perpendicular to its axis, 360-degree reinforcement of the surrounding rock around the main borehole can be achieved without any blind spots. The uniform angle layout ensures that each branch borehole is consistently distanced from the main borehole, allowing the grout to diffuse evenly across the entire plane, avoiding weak areas in any single direction. Simultaneously, it evenly distributes stress in all directions, preventing borehole instability caused by localized stress concentration, and is suitable for geological scenarios where fractures around the main borehole do not exhibit obvious directional characteristics. The uniform angle distribution also facilitates the sequential advancement of the directional drilling rig at fixed angles, reducing the difficulty of directional control, improving borehole positioning accuracy, and avoiding interference or spacing deviations between branch boreholes. The ring-shaped branch holes provide a comprehensive fracture propagation channel for subsequent hydraulic fracturing, allowing fracturing fractures to extend evenly in all directions from the main borehole to the reinforced area of ​​the branch holes, forming a three-dimensional fracturing network rather than being limited to a single direction. This improves the coverage and uniformity of regional fracturing, while further enhancing the synergistic reinforcement effect of the main borehole and branch holes. This results in a structurally stable and stress-balanced reinforcement system for the entire rock mass, providing a reliable guarantee for fracturing pressure maintenance and smooth fracture propagation.

[0038] In some embodiments, the cross-hole area crushing is divided into light crushing, medium crushing, and heavy crushing. Construction parameters are selected according to the crushing level of the cross-hole area. Light crushing is the same as the directional drilling construction parameters; for medium crushing, the grouting hole sections are densified to increase the grout solidification speed; for heavy crushing, the grout is injected in sections to ensure reinforcement strength.

[0039] Specifically, the fracture levels across the borehole area were divided into three categories: light, moderate, and severe, with differentiated selection of construction parameters. This achieved precise adaptation and targeted treatment of borehole reinforcement, avoiding insufficient reinforcement or resource waste caused by uniform parameters. For lightly fractured areas, due to the fewer and smaller fractures, the original directional drilling parameters were sufficient to meet the reinforcement requirements without additional process adjustments. This simplified the construction process, shortened the construction period, and avoided unnecessary disturbance to the rock mass caused by excessive construction. For moderately fractured areas, the density of grouting holes allowed for... The grout more densely covers the dispersed cracks, eliminating reinforcement blind spots. Increasing the grout setting speed (such as increasing the proportion of quick-setting agent) can reduce the loss of grout in the broken cracks, quickly forming a stable reinforced structure and preventing secondary hole collapse during the waiting period for setting. For severely broken areas, the segmented grout injection method can fill large-scale and dense broken cracks segment by segment, ensuring that each segment can be fully wetted and densely filled by the grout, avoiding incomplete filling of deep cracks due to one-time grouting, and effectively ensuring the overall strength and continuity of the reinforced structure.

[0040] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to 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 this invention.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0042] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0043] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "beneath" of the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0044] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0045] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A device for directional hydraulic fracturing of a wellbore, characterized in that, include: The grouting pump, the grout container, and the delivery pipeline are connected together. The first end of the delivery pipeline is connected to the grouting pump, and the second end of the delivery pipeline extends into the directional borehole for grouting. The end of the second end is configured with a T-shaped opening to ensure that the grout is sprayed out along the circumferential direction of the borehole.

2. The km directional hydraulic fracturing hole protection device according to claim 1, characterized in that, The front end of the T-shaped opening is provided with a guide cone, which is used to reduce the scraping and collision with the hole wall.

3. A method of hole protection by directional hydraulic fracturing of a kilometer, using the device for hole protection by directional hydraulic fracturing of a kilometer according to any of claims 1 and 2, characterized in that, Includes the following steps: Install the grouting pump, prepare the grouting slurry, determine the cross-hole area, and send the delivery pipeline into the directional borehole; Start the grouting pump to perform grouting. Stop grouting when the grout flows out from the borehole wall and wait for the grout to solidify. Branch boreholes are drilled in the area surrounding the directional borehole; Grouting is performed on the branch boreholes. Grouting is stopped when the grout flows out from the borehole wall and the grout solidifies.

4. The method of claim 3, wherein, It also includes the location of cross-hole areas, which determines the location and extent of the cross-hole areas based on changes in drilling resistance and the state of slurry return within the hole.

5. The method of claim 3, wherein, During the grouting process, the grouting pressure is gradually increased to inject the cement grout into the cross-hole area under high pressure. During the grouting process, the grout flow rate and pressure changes are monitored in real time using a flow meter.

6. The method of claim 3, wherein, If the mudstone around the main borehole is severely fractured, with densely developed fissures and a large cross-hole area, the distance between the branch borehole and the directional borehole should be controlled at 1.5-3m. If the rock mass around the main borehole is of good integrity, the mudstone interlayer is thin, and the fissures are not well developed, the distance between the branch borehole and the directional borehole should be controlled at 3-5m.

7. The method of claim 3, wherein, After grouting in directional drilling, the effective diffusion radius of the grout is a, and the distance between the branch borehole and the directional borehole is 1.5a-2a, ensuring that the diffusion range of adjacent branch boreholes overlaps with the diffusion range of the directional borehole, and the width of the overlap area is greater than or equal to 0.5m.

8. The method of claim 3, wherein, The spacing between the branch boreholes and the directional boreholes is matched with the range of fracturing fracture propagation, and the spacing does not exceed 1.5 times the expected propagation length of the fracturing fracture.

9. The method of claim 3, wherein, The branch boreholes are evenly distributed in a ring shape at an angle, centered on the directional borehole and in a plane perpendicular to the axis of the directional borehole.

10. The method of claim 3, wherein, The cross-hole area crushing is divided into light crushing, medium crushing, and heavy crushing. Construction parameters are selected according to the crushing level of the cross-hole area. The construction parameters for light crushing are the same as those for directional drilling; for medium crushing, the grouting hole sections are densified to increase the grout solidification speed; for heavy crushing, the grout is injected in sections to ensure reinforcement strength.

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