Drilling guidance device and drilling tool for small radius of curvature

Abstract

The application belongs to the technical field of drilling, and particularly provides a drilling guiding device for small curvature radius and a drilling tool. The drilling guiding device for small curvature radius comprises a shell, a mandrel and a plurality of pushing units, the mandrel is rotationally matched with the shell, and a plurality of pushing units are arranged on the shell at equal intervals. The pushing unit comprises a radially slidable pushing block and a pushing claw hingedly arranged on the pushing block, and the pushing block and the pushing claw jointly constitute a two-stage pushing mechanism. When drilling and deflecting guiding is performed, the pushing block is first driven by a first pushing piece to radially extend by a certain distance, and then the pushing claw is further extended by a second pushing piece until the pushing claw abuts against the well wall to generate a pushing force, so that the mandrel is bent and deformed. When a wellbore with the same diameter is constructed, the diameter of the shell in the application can be designed to be smaller, which not only reduces the risk of sticking, but also better realizes bending and deflecting, and is helpful for drilling construction with small curvature radius and high deflecting rate.

Description

Technical Field

[0001] This application belongs to the field of drilling technology, specifically a drilling guidance device and drilling tool for small radius of curvature. Background Technology

[0002] In the field of drilling engineering, push-type directional drilling devices are commonly used to achieve directional drilling and trajectory control. These devices are typically installed between the drill bit and drill pipe. Their core working principle involves using the downhole hydraulic system to drive one or more push blocks to extend radially outward. When the push blocks are in close contact with the wellbore wall, a reverse force is generated and transmitted to the drill pipe, causing it to bend elastically in a controllable manner. This guides the drill bit to drill in a specific direction, achieving wellbore trajectory build-up and adjustment. This technology forms the basis of modern directional drilling, and its performance directly affects the accuracy of wellbore trajectory control and the efficiency of drilling operations.

[0003] Short-radius drilling technology, as an important branch of directional drilling, is characterized by its ability to achieve extremely high wellbore build-up rates and extremely small radii of curvature. In short-radius drilling, the drill string's ability to navigate curved sections becomes a primary challenge. Traditional long-length directional tools often fail to pass smoothly through extremely short turning sections due to excessive rigidity and axial length. For push-type directional devices to adapt to the demands of short-radius drilling, the contradiction between their outer diameter and radial push stroke becomes even more pronounced—the extremely small wellbore curvature radius not only imposes stricter constraints on the overall size and axial length of the tool but also requires efficient push-guided operation within a limited annular space. This is precisely the core challenge in directional device design.

[0004] However, existing push-type guide devices face a significant design contradiction and performance bottleneck in practical applications: the conflict between the strict limitation of their overall outer diameter and the required radial push stroke. Because the device must be installed around the drill pipe and lowered into the well along with the drill string, its maximum outer diameter is strictly constrained, typically only slightly smaller than the drill bit's outer diameter, while its axial length is relatively long, reaching approximately 100 centimeters. This narrow annular space results in minimal clearance between the device and the wellbore during downhole movement, making it highly susceptible to obstruction or even stuck pipe, threatening operational safety. Furthermore, an excessively large diameter reduces the drill pipe's bending radius, affecting the radius of curvature during directional drilling. Conversely, if the overall design diameter of the device is deliberately reduced to lower the risk of stuck pipe, it directly compresses the installation space and piston stroke of the internal drive hydraulic cylinder. Since the radial extension and retraction of the push block depends entirely on the drive of this built-in hydraulic cylinder, a reduction in the hydraulic cylinder's stroke inevitably limits the maximum extension range of the push block. In cases where the well diameter is large or the well wall is irregular, the shrinking push block may not be able to effectively contact the well wall, thus failing to generate sufficient radial support force and causing the directional drilling to fail.

[0005] Based on the above analysis, the diameter design of push-type guide devices in the existing technology has always been a trade-off between avoiding the risk of stuck drill and ensuring effective directional drilling capability, which restricts the application of this technology in more complex well conditions or scenarios with higher precision requirements. Summary of the Invention

[0006] Based on the above-mentioned technical problems, this application provides a drilling guide device and drilling tool for small curvature radius, so as to solve the technical problem that the outer diameter of the existing drilling guide device cannot simultaneously achieve both high build-up rate and anti-sticking functions.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows: In a first aspect, a drilling guidance device for small radii of curvature is provided, comprising: The outer shell is a hollow cylindrical shape, and at least three mounting slots are equally spaced on the side wall of the outer shell along its circumference. A mandrel, penetrating the housing and rotatably engaged with it, one end of the mandrel connected to the drill rod and the other end connected to the drill bit; and Multiple push-back units are correspondingly arranged in the mounting slot; each push-back unit includes a push-back block, a push-back claw, a first pusher and a second pusher. The push-back block is arranged in the mounting slot and has a receiving slot on its side away from the mandrel. The first pusher is arranged in the housing and is used to drive the push-back block to extend or retract radially along the housing. The push-back claw is arranged axially along the housing in the receiving slot. One end of the push-back claw is hinged to the push-back block to form a mounting end, and the other end forms a free end. One end of the second pusher is hinged to the push-back block, and the other end is hinged to the push-back claw near its own mounting end. The pusher claw has an idle state in which it is housed in the receiving groove, and an operating state in which the free end extends out of the receiving groove under the drive of the second pusher.

[0008] In the working state, the push-fit block extends radially along the outer shell as a primary extension, and the push-fit claw extends radially outward around its mounting end as a secondary extension, causing the free end of the push-fit claw to extend further radially outward relative to the outer surface of the push-fit block. Thus, the radial extension of the push-fit block and the additional radial extension of the free end of the push-fit claw together constitute the total radial pushing stroke of the pushing unit. In the idle state, the push-fit claw is retracted into the receiving groove of the push-fit block, and the push-fit block is retracted into the mounting groove of the outer shell, ensuring that the entire pushing unit does not extend beyond the outer perimeter of the outer shell.

[0009] In one possible implementation, the pushing unit includes two pushing claws, and the second pushing member is provided with two corresponding pushing claws; The two push claws are defined as a first push claw and a second push claw; wherein, the upper end of the first push claw is hinged to the push pressing block and the lower end forms a free end, and the lower end of the second push claw is hinged to the push pressing block and the upper end forms a free end.

[0010] In one possible implementation, the free ends of the first pusher claw and the second pusher claw are respectively provided with protruding teeth, and a tooth groove is formed between two adjacent protruding teeth. When in an idle state, the first pusher claw and the second pusher claw are engaged with each other through the protruding teeth and the tooth groove.

[0011] In one possible implementation, the mounting end of the first pusher claw is inclined from top to bottom outwards from the side opposite to the mandrel to form a guide slope. The guide slope is provided with protruding breaking teeth, which are wear-resistant cemented carbide blocks or polycrystalline diamond composite (PDC) teeth.

[0012] In one possible implementation, the first pusher is a primary hydraulic cylinder, the cylinder body of which is fixed inside the housing, and the piston rod of which is connected to the pusher block; the housing is provided with a hydraulic flow channel communicating with the primary hydraulic cylinder, and the spindle is provided with a central channel for conveying hydraulic medium to the hydraulic flow channel; the second pusher is a secondary hydraulic cylinder, the cylinder body of which is hinged to the side wall of the receiving groove, and the piston rod of which is hinged to the pusher claw.

[0013] In one possible implementation, the push-fit block has a connecting hole that connects the receiving groove and the mounting groove, and the connecting hole is used for the hydraulic pipeline of the secondary hydraulic cylinder to pass through.

[0014] In one possible implementation, two housings are spaced apart along the length of the mandrel, with the two housings located at opposite ends of the mandrel; the number of mounting slots on the housings is even, and during drilling guidance, the upper housing and the lower housing are positioned relative to each other about the axis of the mandrel.

[0015] In one possible implementation, both the pushing block and the pushing claw have arc-shaped sides facing away from the mandrel.

[0016] Compared with the prior art, the beneficial effects of the drilling guidance device for small radius of curvature provided in this application are: The drilling guidance device for small radii of curvature provided in this application includes a housing, a mandrel, and multiple push-fit units. The mandrel is rotatably coupled to the housing, and multiple push-fit units are evenly spaced on the housing. Each push-fit unit includes a radially sliding push-fit block and a push-fit claw hinged to the push-fit block. The push-fit block and push-fit claw together constitute a two-stage push-fit mechanism. During drilling directional guidance, the push-fit block is first driven to extend radially a certain distance by a first pusher, and then the push-fit claw is driven to extend further by a second pusher until it abuts against the well wall, generating a pushing force that causes the mandrel to bend and deform, driving the drill bit to drill obliquely. The push-fit claw is hinged to the push-fit block, and the connection position between the second pusher and the push-fit claw is located near the mounting end. The second pusher only needs to make a small amplitude movement to allow the push-fit claw to extend a large length out of the receiving groove, ensuring that the push-fit claw smoothly contacts the well wall and generates a pushing force.

[0017] This application employs a two-stage pushing mechanism consisting of a pushing block and a pushing claw, thereby achieving a larger total radial extension stroke without increasing the overall diameter of the device. Compared with existing technologies, when constructing wells of the same diameter, the diameter of the outer shell in this application can be designed to be smaller, which reduces the risk of stuck pipe and enables better curved build-up, facilitating drilling operations with small curvature radii and high build-up rates.

[0018] Secondly, a drilling tool is provided, comprising: The drilling guidance device for small radius of curvature described in any of the above implementations; and A drill bit is connected to the bottom end of the mandrel; the drill bit is a PDC drill bit or a roller cone drill bit.

[0019] The drilling tool provided in this application, which employs any of the above-mentioned implementation methods for drilling guidance devices with small curvature radii, has the same technical effect and will not be described in detail here. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of the drilling tool provided in the embodiments of this application; Figure 2 An internal cross-sectional view of a drilling guidance device with a small radius of curvature provided in an embodiment of this application; Figure 3 for Figure 2 Enlarged view of part A in the middle; Figure 4 This is a structural diagram of the push-fit unit when it is in an idle state. Figure 5 This is a structural diagram showing the push unit in one of its working states. Figure 6 A schematic diagram of the push unit in another working state; Figure 7 This is a schematic diagram of the operation of existing drilling tools during directional drilling. Figure 8 A schematic diagram illustrating the operation of the drilling tool provided in this application during directional drilling; Explanation of reference numerals in the attached figures: 10. Housing; 11. Bearing; 20. Mandrel; 30. Pushing unit; 31. Pushing block; 32. First pushing component; 33. Second pushing component; 34. First pushing claw; 341. Mounting end; 342. Free end; 343. Guide slope; 344. Breaking tooth; 345. Convex tooth; 35. Second pushing claw; 351. Tooth groove; 40. Drill bit. Detailed Implementation

[0022] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0023] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0024] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and 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 this application.

[0025] 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 one or more of that feature. In the description of this application, "multiple" or "several" means two or more, unless otherwise explicitly specified.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0027] Please refer to the following: Figures 1 to 8 The drilling guidance device and drilling tool for small radius of curvature provided in this application are described below.

[0028] Please see Figures 1 to 6 In one aspect, this application provides a drilling guidance device for small radius of curvature, including a housing 10, a spindle 20 and a plurality of pushing units 30.

[0029] The outer casing 10 is a hollow, rigid cylindrical structure, typically made of high-strength alloy steel. Its outer diameter is smaller than that of the drill bit 40 to ensure smooth passage through the wellbore. The axial length of the outer casing 10 can be designed as needed, for example, 100 cm, 80 cm, etc. At least three axially extending mounting slots (e.g., three, four, or six) are evenly spaced along the circumference of the sidewalls of the outer casing 10. The cross-sectional shape of the mounting slots can be rectangular, T-shaped, or other adaptable shapes.

[0030] The mandrel 20 is a hollow shaft-shaped component passing through the center of the housing 10. Made of alloy steel, it rotates with the housing 10 via a bearing 11. During operation, the mandrel 20 rotates with the drill pipe. The housing 10 is in a conventional configuration, remaining stationary or rotating slightly under damping. One end of the mandrel 20 is threaded to the upper drill pipe, and the other end is connected to the lower drill bit 40 in the same manner, for transmitting torque and drilling pressure. If necessary, existing components such as a centralizer can also be installed between the drill bit 40 and the mandrel 20.

[0031] Multiple push-back units 30 are correspondingly arranged in the mounting groove. Each push-back unit 30 includes a push-back block 31, a push-back claw, a first push-up member 32, and a second push-up member 33. The push-back block 31 is arranged in the mounting groove and has a receiving groove on the side away from the spindle 20. The first push-up member 32 is arranged inside the housing 10 and is used to drive the push-back block 31 to extend or retract radially along the housing 10. The push-back claw is arranged in the receiving groove axially along the housing. One end of the push-back claw is hinged to the push-back block 31 to form a mounting end 341, and the other end forms a free end 342. One end of the second push-up member 33 is hinged to the push-back block 31, and the other end is hinged to the push-back claw near its own mounting end 341.

[0032] The number of push-fit units 30 corresponds one-to-one with the mounting slots. The push-fit block 31 is a block-shaped component that is slidably mounted within the corresponding mounting slot. The outer surface of the push-fit block 31 away from the mandrel 20 is typically machined into an arc-shaped surface that conforms to the wellbore contour. An outward-facing receiving slot is provided inside the push-fit block 31 for mounting the push-fit claw. Sealing elements such as gaskets and sealing rings can be installed between the push-fit block 31 and the inner wall of the mounting slot to prevent drilling fluid from entering the housing 10 through gaps. The use of sealing rings is existing technology and will not be described in detail here.

[0033] The first pusher 32 is disposed in a cavity inside the housing 10, providing the power to drive the pusher block 31 to slide outward radially (i.e., perpendicular to the axis of the spindle 20) along the housing 10. The pusher claw is a rod-shaped component, disposed vertically (parallel to the axis of the spindle 20) within the receiving groove of the pusher block 31. One end of the pusher claw is hinged to the pusher block 31 by a pin, allowing it to rotate around the hinge point; the other end is not fixed. The pusher claw is mounted on the pusher block 31 and does not occupy internal space of the housing 10.

[0034] The second pusher 33 is used to drive the pusher claw. One end of the second pusher 33 is hinged to the pusher block 31 by a pin, and the other end is hinged to the pusher claw near its mounting end 341 by a pin. A small movement of the second pusher 33 can cause the free end 342 to swing a large range.

[0035] The first pusher 32 and the second pusher 33 can be in the form of a hydraulic cylinder, an electric cylinder, or other linear drive mechanism. Preferably, they are hydraulic cylinders, powered by high-pressure drilling fluid or a hydraulic pump integrated within the housing 10. The extension and retraction of the hydraulic cylinder can be controlled by an electrically controlled valve. The power for the electrically controlled valve is provided by a battery installed within the housing 10. This battery is a rechargeable battery that can store electrical energy and can also be charged by a drilling fluid self-generating system installed on the drill pipe.

[0036] like Figures 4 to 6The pusher claw has an idle state, housed within a receiving groove, and an operational state, driven by the second pusher 33, in which its free end 342 extends out of the receiving groove. Specifically, the pusher block 31 constitutes the first-stage extension of the pusher unit 30. When the first pusher 32 actuates, the pusher block 31 extends radially outward along the outer casing 10, forming a first-stage radial extension amount c. The pusher claw constitutes the second-stage extension of the pusher unit 30. When the second pusher 33 actuates, the pusher claw rotates around its mounting end 341, causing the free end 342 to swing out of the receiving groove and further extend radially outward relative to the outer surface of the pusher block 31, forming an additional radial extension amount d. Thus, the total radial push stroke of the pusher unit 30 is c+d.

[0037] like Figure 8 As shown, during drilling with a small radius of curvature (large dogleg), the first pusher 32 is first controlled to push the push block 31 to its maximum limit position, at which point the first pusher 32 has not yet contacted the well wall. Subsequently, driven by the second pusher 33, the push claw rotates around the hinge point of its mounting end 341, causing its free end 342 to extend outward from the receiving groove of the push block 31 until it abuts against the well wall, entering the working state. Under the reaction force of the second pusher 33, the mandrel 20 undergoes bending deformation, changing the drilling direction of the drill bit 40 and achieving drilling guidance. After the directional drilling is completed, the second pusher 33 and the first pusher 32 are retracted in sequence, the push block 31 is housed in the mounting groove, and the push claw is housed in the receiving groove, in an idle state.

[0038] like Figure 7 The diagram shows the working principle of drilling tools in the prior art when performing directional drilling. In the prior art, the working end of the push-type rotary guide device (equivalent to the push-press block 31 in this application) has a travel of c and a directional drilling angle of a. In order to ensure that the working end can contact the well wall, the overall diameter of the guide device is slightly smaller than the diameter of the drill bit 40 (e.g., less than 10mm), which makes it easy for movement to become stuck. Moreover, the bending deformation is small, and the radius of curvature is correspondingly larger during directional drilling.

[0039] like Figure 8 As shown, during well drilling and directional drilling, the extension stroke of the push block 31 is c, the extension stroke of the push claw is d, and the overall extension stroke of the push unit 30 is c+d. The larger stroke allows for a smaller diameter design for the outer casing 10. The directional drilling angle is b, which is greater than a. Compared to existing technologies, this angle is larger, the radius of curvature is smaller, and the slope is greater.

[0040] Compared with the prior art, the beneficial effects of the drilling guidance device for small radius of curvature provided in this application are: The drilling guidance device for small radius of curvature provided in this application includes a housing 10, a mandrel 20, and multiple push units 30. The mandrel 20 is rotatably coupled to the housing 10, and multiple push units 30 are evenly spaced on the housing 10. Each push unit 30 includes a radially sliding push block 31 and a push claw hinged to the push block 31. The push block 31 and the push claw together constitute a two-stage push mechanism. During drilling directional guidance, the push block 31 is first driven to extend radially a certain distance by the first pusher 32, and then the push claw is driven to extend further by the second pusher 33 until it abuts against the well wall, generating a push force that causes the mandrel 20 to bend and deform, driving the drill bit 40 to drill obliquely. The push claw is hinged to the push block 31, and the connection position of the second pusher 33 and the push claw is located near the mounting end 341. The second pusher 33 only needs to make a small movement to make the push claw extend a large length out of the receiving groove, ensuring that the push claw can smoothly contact the well wall and generate a pushing force.

[0041] This application utilizes a two-stage pushing mechanism consisting of a pushing block 31 and a pushing claw, thereby achieving a larger total radial extension stroke without increasing the overall diameter of the device. Compared with existing technologies, when constructing wells of the same diameter, the diameter of the outer casing 10 in this application can be designed to be smaller, which reduces the risk of stuck pipe and enables better curved build-up, facilitating drilling operations with small curvature radii and high build-up rates.

[0042] The sides of the push-adhesive block 31 and the push-adhesive claw away from the spindle 20 are both arc-shaped to better fit the well wall surface, reduce contact stress, and improve support stability and tool life.

[0043] Please see Figures 4 to 6 The pushing unit 30 includes two pushing claws, and the second pushing member 33 is provided with two corresponding pushing claws; the two pushing claws are defined as the first pushing claw 34 and the second pushing claw 35; wherein, the upper end of the first pushing claw 34 is hinged to the pushing pressure block 31, and the lower end forms a free end 342, and the lower end of the second pushing claw 35 is hinged to the pushing pressure block 31, and the upper end forms a free end 342.

[0044] By incorporating two pusher claws, the base area with the well wall can be increased, providing a more stable support effect. The free end 342 of the pusher claw is used to contact the well wall and can be equipped with protrusions made of wear-resistant alloy material to increase friction and prevent slippage. The two second pusher components 33 can be controlled independently, allowing the two pusher claws to operate individually or simultaneously.

[0045] To avoid interference between the first pusher claw 34 and the second pusher claw 35, such as Figure 5 and Figure 6As shown, the free ends 342 of the first pusher claw 34 and the free ends 342 of the second pusher claw 35 are respectively provided with protruding teeth 345, and a tooth groove 351 is formed between two adjacent protruding teeth 345. When in an idle state, the first pusher claw 34 and the second pusher claw 35 are engaged with each other through the protruding teeth 345 and the tooth groove 351.

[0046] The shape of the protruding teeth 345 can be triangular, trapezoidal, or rectangular. When both push claws are in an idle state (i.e., fully retracted into the receiving slot), the protruding teeth 345 of the free end 342 of the first push claw 34 and the protruding teeth 345 of the free end 342 of the second push claw 35 are arranged alternately and interlocked with each other through the tooth grooves 351 on the side of the protruding teeth 345, forming a compact, interlocking structure. This helps to reduce the overall envelope size and improve the structural stability in the retracted state.

[0047] When retracted into the receiving groove, the protrusion 345 and the groove 351 engage with each other, improving the overall rigidity and vibration resistance of the push unit 30 in the retracted state.

[0048] Please see Figure 6 The mounting end 341 of the first pusher claw 34 is inclined outward from top to bottom on the side opposite to the mandrel 20, forming a guide slope 343, which makes it easier to pass through narrow positions when lifting the drill pipe. The guide slope 343 and other positions on the outer side of the first pusher claw 34 are provided with protruding breaking teeth 344, which are wear-resistant cemented carbide blocks or polycrystalline diamond composite (PDC) teeth. During vertical drilling, the first pusher claw 34 can be opened to a smaller extent by the second pusher 33. At this time, multiple first pusher claws 34 are opened simultaneously, and the first pusher claws 34 do not contact the well wall. When drilling into loose formations and encountering debris falling from the well wall, the breaking teeth 344 contact the debris. Lifting the drill pipe up and down helps the breaking teeth 344 break larger debris, helping to prevent debris from affecting the operation of the drill bit 40.

[0049] Please see Figure 2 and Figure 3 The first pusher 32 is a primary hydraulic cylinder, the cylinder body of which is fixed inside the outer casing 10, and the piston rod of which is connected to the pusher block 31. The outer casing 10 is provided with a hydraulic flow channel communicating with the primary hydraulic cylinder, and the spindle 20 is provided with a central channel for conveying hydraulic medium to the hydraulic flow channel. The second pusher 33 is a secondary hydraulic cylinder, the cylinder body of which is hinged to the side wall of the receiving groove, and the piston rod of which is hinged to the pusher claw.

[0050] The push-pressing block 31 has a connecting hole that connects the receiving groove and the mounting groove. The connecting hole is used for the hydraulic pipeline of the secondary hydraulic cylinder to pass through.

[0051] Please see Figure 1Two housings 10 are provided at intervals along the length of the mandrel 20, and the two housings 10 are located at the two ends of the mandrel 20 respectively; the number of mounting slots of the housings 10 is even (such as four, six, or eight). When drilling guidance is performed, the upper housing 10 and the lower housing 10 are positioned relative to each other about the axis of the mandrel 20.

[0052] During directional drilling, the push-fit unit 30 on the upper housing 10 and the push-fit unit 30 on the lower housing 10 are positioned 180 degrees relative to each other about the axis of the mandrel 20. The push-fit units 30 on the upper and lower housings 10 operate synchronously and act in opposite directions on the mandrel 20, generating a bending couple on the mandrel 20. Compared to conventional single-point push-fit, this method can achieve more precise and efficient deflection of the drill bit 40, which is particularly beneficial for drilling operations with smaller radii of curvature and greater dogleg.

[0053] Secondly, this application provides a drilling tool, including the aforementioned drilling guidance device for small radius of curvature; and a drill bit 40, which is connected to the bottom end of the mandrel 20. The drill bit 40 is a PDC drill bit or a roller cone drill bit, and the specific shape and structure of the drill bit 40 are prior art and will not be described in detail here.

[0054] It should be noted that the technical solution described in this application may involve controlling the sequence of actions, extension position, and magnitude of the pushing force of the pushing unit. This requires relying on a downhole measurement system (such as a measurement while drilling system), a signal transmission system, and corresponding controllers or processors. These sensors (such as pressure sensors, displacement sensors, and attitude sensors), electronic control modules, signal encoders and decoders, microprocessors, and control strategies based on preset logic or surface commands (e.g., determining which pushing unit to activate and the extension amount based on real-time well inclination and azimuth data) are all common knowledge and mature existing technologies in the field of drilling technology. Those skilled in the art can select and integrate a suitable measurement and control system according to specific drilling process requirements and tool configurations. Even if the hardware connection details are not described in this application, it does not affect the completeness and feasibility of this technical solution. The core innovation of this application lies in the improvement of the mechanical structure. The specific implementation of the measurement and control system is not the focus of protection claimed in this application, and its application is conventional for those skilled in the art.

[0055] It is understood that the parts in the above embodiments can be freely combined or deleted to form different combined embodiments. The specific contents of each combined embodiment will not be repeated here. After this description, it can be considered that the present invention specification has recorded each combined embodiment and can support different combined embodiments.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A drilling guidance device for small radii of curvature, characterized in that, include: The outer shell (10) is a hollow cylindrical shape, and the side wall of the outer shell (10) is provided with at least three mounting grooves at equal intervals along its circumference. The mandrel (20) passes through the outer shell (10) and is rotatably engaged with the outer shell (10). One end of the mandrel (20) is connected to the drill rod, and the other end is connected to the drill bit (40). as well as Multiple push-back units (30) are arranged in the mounting groove one by one; each push-back unit (30) includes a push-back block (31), a push-back claw, a first push-up member (32) and a second push-up member (33). The push-back block (31) is arranged in the mounting groove and has a receiving groove on the side away from the spindle (20). The first push-up member (32) is arranged in the outer shell (10) and is used to drive the push-back block (31) to extend or retract radially along the outer shell (10). The push-back claw is arranged in the receiving groove axially along the outer shell. One end of the push-back claw is hinged to the push-back block (31) to form a mounting end (341) and the other end forms a free end (342). One end of the second push-up member (33) is hinged to the push-back block (31) and the other end is hinged to the push-back claw near its own mounting end (341). The pusher claw has an idle state that is accommodated in the receiving groove, and an operating state that allows the free end (342) to extend out of the receiving groove under the drive of the second pusher (33); In the working state, the free end (342) of the push claw extends radially outward relative to the side of the push block (31) away from the spindle (20). The radial extension of the push block (31) and the additional radial extension of the free end (342) of the push claw together constitute the total radial push stroke of the push unit (30). In the idle state, the push claw is housed in the receiving groove of the push block (31), the push block (31) is housed in the mounting groove of the outer shell (10), and the push block (31) and the push claw do not extend beyond the outer periphery of the outer shell (10).

2. The drilling guidance device for small radius of curvature according to claim 1, characterized in that, The pushing unit (30) includes two pushing claws, and the second pushing member (33) is provided with two corresponding pushing claws; The two push claws are defined as the first push claw (34) and the second push claw (35); wherein the upper end of the first push claw (34) is hinged to the push pressing block (31) and the lower end forms a free end (342); the lower end of the second push claw (35) is hinged to the push pressing block (31) and the upper end forms a free end (342).

3. The drilling guidance device for small radius of curvature according to claim 2, characterized in that, The free end (342) of the first push claw (34) and the free end (342) of the second push claw (35) are respectively provided with protruding teeth (345), and a tooth groove (351) is formed between two adjacent protruding teeth (345). When in an idle state, the first push claw (34) and the second push claw (35) are engaged with each other through the protruding teeth (345) and the tooth groove (351).

4. The drilling guidance device for small radius of curvature according to claim 2, characterized in that, The mounting end (341) of the first push claw (34) is inclined from top to bottom outward on the side away from the mandrel (20) to form a guide slope (343). The guide slope (343) is provided with protruding breaking teeth (344). The breaking teeth (344) are wear-resistant hard alloy blocks or polycrystalline diamond composite PDC teeth.

5. The drilling guidance device for small radius of curvature according to claim 1, characterized in that, The first pusher (32) is a primary hydraulic cylinder, the cylinder body of which is fixed inside the outer shell (10), and the piston rod of which is connected to the push block (31); the outer shell (10) is provided with a hydraulic flow channel communicating with the primary hydraulic cylinder, and the spindle (20) is provided with a central channel for conveying hydraulic medium to the hydraulic flow channel; the second pusher (33) is a secondary hydraulic cylinder, the cylinder body of which is hinged to the side wall of the receiving groove, and the piston rod of which is hinged to the push claw.

6. The drilling guidance device for small radius of curvature according to claim 5, characterized in that, The push-press block (31) has a connecting hole that connects the receiving groove and the mounting groove. The connecting hole is used for the hydraulic pipeline of the secondary hydraulic cylinder to pass through.

7. The drilling guidance device for small radius of curvature according to claim 1, characterized in that, Two outer shells (10) are provided at intervals along the length direction of the mandrel (20), and the two outer shells (10) are respectively located at both ends of the mandrel (20); the number of mounting slots of the outer shells (10) is even. When drilling guidance is performed, the upper outer shell (10) push-back unit (30) and the lower outer shell (10) push-back unit (30) are arranged relative to each other about the axis of the mandrel (20).

8. The drilling guidance device for small radius of curvature according to claim 1, characterized in that, The sides of the push-press block (31) and the push-press claw that are away from the spindle (20) are both arc-shaped.

9. A drilling tool, characterized in that, include: The drilling guidance device for small radius of curvature as described in any one of claims 1 to 8; as well as The drill bit (40) is connected to the bottom end of the mandrel (20).

10. The drilling tool according to claim 9, characterized in that, The drill bit (40) is a PDC drill bit (40) or a roller cone drill bit (40).

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