A kind of advance reamer for casing directional drilling

Abstract

The application discloses a leading reamer for casing directional drilling, a middle hole is coaxially arranged at the top end of the reamer body, a plurality of blade wings capable of being folded under the extrusion of the inner wall of the casing are equidistantly and circumferentially hinged at the bottom end of the reamer body, a pressure valve core capable of being pushed by mud is movably arranged in the middle hole along the axial direction of the middle hole, a blind hole for the mud to pass through is arranged at the top end of the pressure valve core, a water eye is arranged on the side wall of the pressure valve core and is in communication with the blind hole, the bottom end of the pressure valve core extends out of the reamer body and abuts against the top end of each blade wing, a first flushing pipeline and a second flushing pipeline are arranged on the reamer body and are in communication with the water eye, when the mud enters the blind hole and pushes the pressure valve core to move, the mud rapidly passes through the blind hole and the water eye and flows to the first flushing pipeline and the second flushing pipeline respectively, then the inside and outside of the blade wings are flushed, the reamer body is kept free of cuttings, the reamer body is not hindered by the cuttings when being folded, and the process and action are simple.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of drilling equipment, in particular to a leading reaming bit suitable for casing directional drilling. BACKGROUND

[0002] Casing drilling refers to a drilling process in which a casing is directly used (instead of a traditional drill rod) to drill and lower the casing during drilling, and the casing is directly left in the well for cementing operations after drilling. Casing directional drilling is a process that realizes directional drilling by using logging while drilling technology on the basis of casing drilling, and can achieve the purpose of completing directional drilling and lowering the casing in one trip, thereby saving drilling time. In the casing directional drilling technology, the casing can be regarded as a bent screw rod with an angle in the transmission directional drilling technology, and downhole tools such as a leading reaming bit and a logging while drilling instrument need to be assembled into the casing. Since the casing has a bend, the reaming bit needs to have an angle adjustment function to allow the downhole tools to be smoothly lowered into the bent casing. At the same time, the outer diameter of the leading reaming bit when closed needs to be smaller than the inner diameter of the bent casing. After the downhole tools are assembled, the reaming bit needs to be ahead of the casing end by a distance to provide space for the opening of the reamer blade. When casing directional drilling is performed, the reamer blade needs to be opened, and the designed outer diameter of the opened reamer blade needs to be greater than the outer diameter of the bent casing to enable normal operation. For example, when the inner diameter of the casing is 220 mm, the outer diameter of the reaming bit in the closed state needs to be smaller than 220 mm to pass through the casing and exceed the casing. When drilling mud is performed, the reaming bit needs to be opened under the action of mud hydraulic pressure, and at this time, the outer diameter of the reaming bit needs to be greater than 270 mm (the outer diameter of the casing coupling) to enable normal drilling. When the operation is completed, the downhole tools need to be recovered, and the reamer blade is closed by being squeezed and contracted by the inner wall of the bent casing during the upward recovery process and enters the casing.

[0003] Further, the patent document with the publication number CN115199214A, a locally openable reaming bit in a geological borehole, is retracted and closed by a spring, and if the spring is blocked or crushed by rock cuttings, there is no restoring force to retract and close the blade. The patent document with the authorized publication number CN212837595U, a reamable casing drilling bit, is ground off by using a shoe to open the inner expander and the opening ball after the bit is opened, has no closing function, and has a complex process. SUMMARY

[0004] The purpose of the present application is to provide a leading reaming bit suitable for casing directional drilling to solve the problems existing in the prior art. Water eyes and blind holes are connected by first and second flushing pipelines. When mud enters the blind hole to push the valve core to move, the mud quickly passes through the blind hole and the water eyes and flows to the first and second flushing pipelines, respectively, and then flushes the inner and outer sides of the blade, keeps the bit free of rock cuttings, and does not be hindered by rock cuttings when closed, and the process and action are simple.

[0005] To achieve the above object, the present application provides the following scheme: the present application provides a kind of ahead reaming drill bit suitable for casing directional drilling, including reaming drill bit body, coaxial hole is set in the top end of the reaming drill bit body, the bottom end of the reaming drill bit body is equidistantly articulated with several cutter wings capable of being extruded by casing inner wall, the movable pressure valve core capable of being pushed by mud is arranged in the hole along its axial direction, the top end of the pressure valve core is provided with a blind hole for mud to pass through, the side wall of the pressure valve core is provided with a water hole connected with the blind hole, the bottom end of the pressure valve core extends out of the reaming drill bit body and abuts on the top end of each cutter wing, and the cutter wing can be pushed to spread outward around its hinge point, the first flush pipe and the second flush pipe are provided on the reaming drill bit body, and the first flush pipe and the second flush pipe are connected with the water hole, the outlet of the first flush pipe is directed to the outer peripheral edge of the cutter wing, and the outlet of the second flush pipe is directed to the inner side position of each cutter wing.

[0006] Preferably, the water hole gradually extends to the outer peripheral side of the pressure valve core along the direction of mud flow, and the inlets of the first flush pipe and the second flush pipe are located on the side of the water hole outlet close to the cutter wing.

[0007] Preferably, the top end of the reaming drill bit body is clamped with a torque adapter abutting on the inner side wall of the casing, the side of the transmission joint away from the reaming drill bit body is provided with a single-sided universal joint, and the transmission joint is provided with a spherical groove rotationally connected with the single-sided universal joint, and the transmission joint and the single-sided universal joint are provided with a mud pipe connected with the hole.

[0008] Preferably, the flow cross section of the blind hole and the water hole is smaller than the flow cross section of the mud pipe.

[0009] Preferably, the inner wall of the spherical groove is provided with a spline and a spline groove embeddedly connected with the single-sided universal joint. Preferably, the opening end of the spherical groove is provided with a ball pressing ring for limiting the single-sided universal joint from coming out, and the ball pressing ring abuts on the outer peripheral side of the single-sided universal joint.

[0010] Preferably, the mud pipe on the transmission joint includes a sealing section close to the pressure valve core, the top end of the pressure valve core extends out of the hole, and is slidingly and sealingly inserted in the sealing section.

[0011] Preferably, the bottom end of the reaming drill bit body is provided with a plurality of cutter wing mounting portions respectively used for mounting each cutter wing, each cutter wing mounting portion is circumferentially arranged on the outer peripheral side of the pressure valve core, the cutter wing mounting portion is provided with a mounting groove for accommodating the cutter wing, and the cutter wing pin shaft for articulating the cutter wing is arranged in the mounting groove.

[0012] Preferably, the side wall of the mounting groove is provided with a positioning pin sliding along the direction perpendicular to the opening direction of the blade, the blade is provided with a positioning pin hole spaced along the rotating direction of the blade, and the mounting groove is provided with a spring for abutting the positioning pin in the positioning pin hole.

[0013] Preferably, the side wall of the mounting groove is provided with a positioning channel for sliding of the positioning pin, and a pin shaft pressing plate is detachably connected to the end of the positioning channel away from the blade, and the spring abuts between the pin shaft pressing plate and the positioning pin.

[0014] The present application has the following technical effects relative to the prior art:

[0015] First, the coaxial hole is arranged at the top end of the reamer body, a plurality of blades capable of being extruded and closed by the inner wall of the casing are equidistantly hinged at the bottom end of the reamer body in the circumferential direction, a pressure valve core capable of being pushed by the mud is movably arranged in the coaxial hole in the axial direction, a blind hole for the mud to pass through is arranged at the top end of the pressure valve core, a water eye is arranged on the side wall of the pressure valve core and communicates with the blind hole, the bottom end of the pressure valve core extends out of the reamer body and abuts on the top end of each blade and can push the blade to unfold outward around the hinge point, a first flushing pipeline and a second flushing pipeline that both communicate with the water eye are arranged on the reamer body, the outlet of the first flushing pipeline is directed to the outer peripheral edge of the blade, and the outlet of the second flushing pipeline is directed to the inner side of each blade. During the specific reaming work, the mud flows to the blind hole of the pressure valve core, pushes the pressure valve core to move downward along the coaxial hole to unfold the blade, and flows into the water eye communicating with the blind hole, and then flows into the gap between the pressure valve core and the coaxial hole, and then flows into the first flushing pipeline and the second flushing pipeline. The mud passing through the first flushing pipeline sprays the outer peripheral edge of the blade to flush the cuttings at the outer peripheral edge of the blade, and the mud passing through the second flushing pipeline sprays the inner side of the blade to flush the cuttings at the inner side of the blade, so that the blade and the hinge position are no longer attached by the cuttings, the drill bit is kept clean, and the blade is not hindered when closing or unfolding, so that the blade can fully unfold or close, the transportation of the drill bit is facilitated, and the effective reaming work is ensured.

[0016] Second, the water eye gradually extends to the outer peripheral side of the pressure valve core along the direction of the mud flow. On the one hand, the inclined arrangement of the water eye enables the mud to form a downward pressure component on the pressure valve core when the mud flows through the water eye, thereby ensuring that the pressure valve core can effectively move towards the blade side to complete the full unfolding of the blade. On the other hand, the inclined arrangement of the water eye enables the mud to sufficiently reduce the kinetic energy loss in the axial direction of the pressure valve core during the flow process, thereby ensuring the kinetic energy of the mud flowing out of the first and second flushing pipelines, and further ensuring the flushing effect on the cuttings. The inlets of the first and second flushing pipelines are located on the side of the outlet of the water eye close to the blade, so that the mud can continuously flow in the direction of the movement of the pressure valve core after flowing out of the pressure valve core, thereby flowing into the first and second flushing pipelines, ensuring the continuity of the mud flow, and further reducing the kinetic energy loss.

[0017] Third, the top end of the reaming bit body is clamped with a torque transmission joint, the side of the transmission joint away from the reaming bit body is provided with a single-sided universal joint, and the transmission joint is provided with a spherical groove in rotational connection with the single-sided universal joint. The reaming bit body is provided with a slurry supply pipeline in communication with the middle hole. The bending adjustment of the reaming bit is realized through the universal connection of the spherical groove and the single-sided universal joint. If the existing drill bit needs to realize bending adjustment, a universal joint needs to be connected above the drill bit. However, without the constraint of the casing (the reaming bit drilling tool is in the casing), the drill bit will eccentrically rotate when drilling, which cannot guarantee the wellbore quality and normal drilling. In casing directional drilling, the casing is curved, and the bottom hole drilling tools such as the reaming bit need to be lowered into the curved casing. Only the reaming bit has adjustable bending, can it pass through the bending point of the casing, and the reaming bit can exceed the curved casing to realize drilling. In the present application, the casing in the casing directional drilling is curved, and the bottom hole drilling tools such as the reaming bit lowered into the curved casing need to be angle-adjustable to be lowered into the casing. The bending adjustment is realized through the universal connection of the spherical groove and the single-sided universal joint, which avoids the reaming bit and other downhole drilling tools from being stuck in the curved casing. After the blade extends out of the casing, the torque transmission joint abuts against the inner wall of the casing, which ensures that the drill bit body is constrained by the casing, so that the blade will not eccentrically rotate during drilling, thereby ensuring the wellbore quality.

[0018] Fourth, the flow cross section of the blind hole and the water eye is smaller than that of the slurry supply pipeline. After the pump is opened, the flow cross section of the blind hole and the water eye becomes smaller when the mud passes through them, so that the mud generates a throttling effect at the pressure valve core. According to Bernoulli's principle, a thrust is generated at this position to push the end point of the blade in contact with the pressure valve core, and the blade is pushed up by the pressure valve core with the hinge point as the fulcrum to complete the unfolding action of the blade. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0020] Figure 1 The profile and sectional view of the reamer body of the present application when the blades are closed;

[0021] Figure 2 The profile and sectional view of the reamer body of the present application when the blades are opened;

[0022] Figure 3 The profile and sectional view of the reamer body of the present application when the blades are opened; Figure 1 Another sectional view of the reamer body of the present application;

[0023] Figure 4 The profile and sectional view of the reamer body of the present application when the blades are closed;

[0024] Figure 5 The sectional view of the reamer body of the present application when the blades are closed;

[0025] Figure 6 The schematic view of the connection of the reamer body, torque transmission joint and single-sided universal joint of the present application;

[0026] Figure 7 The schematic view of the pressure valve core structure of the present application;

[0027] Figure 8 The schematic view of the single-sided universal joint structure of the present application;

[0028] Figure 9 The schematic view of the blade structure of the present application;

[0029] Wherein, 1-reamer body; 2-blade; 3-pin shaft pressure plate; 4-positioning pin; 5-blade pin shaft; 6-first fixing bolt; 7-pressure valve core; 8-return spring; 9-torque transmission joint; 10-single-sided universal joint; 11-ball pressure ring; 12-second fixing bolt; 13-blade mounting part; 14-positioning pin hole; 15-middle hole; 16-PDC blade; 17-first flushing pipeline; 18-water eye; 19-second flushing pipeline; 20-sluurry supply pipeline; 21-sealing groove; 22-ball head; 23-spline; 24-V-shaped structure; 25-hinge hole. DETAILED DESCRIPTION

[0030] Clearly, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present application.

[0031] The purpose of the present application is to provide a kind of advance reaming drill bit suitable for casing directional drilling, to solve the problems existing in the prior art described above, by first flush pipe and second flush pipe guide water eye and blind hole, when mud enters blind hole and pushes the movement of pressure valve core, mud quickly passes through blind hole and water eye and respectively flows to first flush pipe and second flush pipe, then forms flush to the inside and outside of blade, keeps the place of drill bit without debris, and will not be hindered by debris when closing, and process, action is simple.

[0032] In order to make the above-mentioned purpose, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below in combination with the drawings and specific embodiments.

[0033] As Figures 1 to 9As shown, the embodiment provides a kind of suitable for casing directional drilling with advance reamer, including reamer body 1, coaxial hole 15 is set in the top end of reamer body 1, the bottom end of reamer body 1 is hinged with several cutter wing 2 that can be extruded by casing inner wall and be folded, specifically, when drilling is finished, the reamer in casing and other downhole tools need to be recycled to the ground, and the casing is left in the well, realize " one trip " complete drilling and casing, during the process of lifting, the cutter wing 2 of reamer in the open state will encounter casing inner wall, and cutter wing 2 is pressed back into closed state under the action of casing inner wall, so that it can be recycled from casing and come up. Preferably, cutter wing 2 is plate structure, its extension direction is radially extending, and hard alloy or PDC piece 16 is welded on its outer edge to improve its strength and ensure drilling effect, hollow blind hole is set in the axial direction of middle hole 15, and the pressure valve core 7 that can be pushed by mud is movably arranged in the blind hole, the top end of pressure valve core 7 is provided with a blind hole for mud to pass through, and the side wall of pressure valve core 7 is provided with a water eye 18 in communication with the blind hole, the water eye 18 is evenly distributed along the circumferential direction of pressure valve core 7, the bottom end of pressure valve core 7 extends out of reamer body 1 and abuts on the top end of each cutter wing 2, and can drive cutter wing 2 to unfold outward around its hinge point, the first flushing pipe 17 and the second flushing pipe 19 that are in communication with the water eye 18 are arranged on the reamer body 1, the outlet of the first flushing pipe 17 is directed to the outer peripheral edge of cutter wing 2, and the outlet of the second flushing pipe 19 is directed to the inner side position of each cutter wing 2, so that in the specific reaming process, mud flows into the blind hole of pressure valve core 7, pushes pressure valve core 7 to move downward along the axial direction of middle hole 15 to make it push cutter wing 2 to unfold, at the same time, mud flows into the water eye 18 in communication with the blind hole, and then flows into the gap between pressure valve core 7 and middle hole 15, and then flows into the first flushing pipe 17 and the second flushing pipe 19, the mud passing through the first flushing pipe 17 sprays towards the outer peripheral edge of cutter wing 2, and the cuttings on the outer peripheral edge of cutter wing 2 are flushed, the mud passing through the second flushing pipe 19 sprays towards the inner side of cutter wing 2, and the cuttings on the inner side of cutter wing 2 are flushed, so that cutter wing 2 and its hinge position are no longer attached by cuttings, the reamer is kept clean, and cutter wing 2 is not hindered when it is closed or unfolded, so that cutter wing 2 can fully unfold or close, the transportation of reamer is facilitated, and the effective reaming work is ensured.

[0034] Preferably, the reset spring 8 is sleeved on the pressure valve core 7, the reset spring 8 is cylindrical helical compression spring, provides restoring force for the upward movement of pressure valve core 7 when cutter wing 2 is recycled, and assists the driving of cutter wing 2 to pressure valve core 7.

[0035] The top end of the blade wing 2 is designed with a V-shaped structure 24 which is embedded with the bottom end of the pressure valve core 7, the middle position of the blade wing 2 is hinged with the reamer body 1, the V-shaped structure 24 of the blade wing 2 can make the pressure valve core 7 produce a lever action when the blade wing 2 is pressed down, specifically, the top end is pressed down, the bottom end moves outward around the hinge point, the blade wing 2 is opened, when the operation is finished, the bottom hole assembly needs to be recovered, the blade wing 2 is closed by being extruded by the inner wall of the bent casing pipe during the recovery process, the V-shaped structure 24 of the blade wing 2 pushes the pressure valve core 7 to reset and enter the casing, the mechanical structure is simple, and the action is reliable.

[0036] Further, the water eye 18 gradually extends to the outer peripheral side of the pressure valve core 7 along the direction of the mud flow, on the one hand, through the inclined arrangement of the water eye 18, when the mud flows through the water eye 18, a downward force on the pressure valve core 7 is formed, which ensures that the pressure valve core 7 can effectively move to the side of the blade wing 2 and fully expand the blade wing 2, on the other hand, through the inclined arrangement of the water eye 18, the kinetic energy loss along the axial direction of the pressure valve core 7 during the flow of the mud can be reduced, the kinetic energy of the mud flowing out of the first flushing pipeline 17 and the second flushing pipeline 19 is ensured, and the flushing effect on the cuttings is ensured, and the inlets of the first flushing pipeline 17 and the second flushing pipeline 19 are located on the side of the outlet of the water eye 18 close to the blade wing 2, so that the mud can continue to flow in the direction of the movement of the pressure valve core 7 after flowing out of the pressure valve core 7, and then flow into the first flushing pipeline 17 and the second flushing pipeline 19, ensuring the continuity of the mud flow and further reducing the kinetic energy loss.

[0037] As a preferred embodiment of the present application, the top end of the reamer bit body 1 is clamped with a torque transmission joint 9, the transmission joint is provided with a single universal joint 10 away from the side of the reamer bit body 1, and the transmission joint is provided with a spherical groove in rotational connection with the single universal joint 10, the spherical surface of the spherical groove provides the freedom of the bit bending, the single universal joint 10 includes a ball head 22, the ball head 22 and the spherical groove (ball socket) on the torque transmission joint 9 form a spherical hinge structure, the transmission joint and the single universal joint 10 are provided with a slurry supply pipeline 20 which is in communication with the middle hole 15, the bending adjustment of the reamer bit is realized through the universal connection of the spherical groove and the single universal joint 10, and if the existing bit needs to realize the bending adjustment, the universal joint needs to be connected above the bit, but there is no casing constraint (the reamer bit drilling tool is in the casing), the bit will eccentrically rotate when drilling, which cannot guarantee the wellbore quality and cannot normally drill. In the casing directional drilling, the casing is curved, and the reamer bit and other bottom hole drilling tools need to be lowered into the curved casing, only the reamer bit has the bending adjustment, which can pass through the bending point of the casing, the reamer bit can exceed the curved casing, and the drilling is realized. In the present application, the casing directional drilling is curved, the reamer bit and other bottom hole drilling tools lowered into the curved casing need to be angle-adjustable, which can be lowered into the casing, the bending adjustment is realized through the universal connection of the spherical groove and the single universal joint 10, the reamer bit and other downhole drilling tools are prevented from being stuck in the curved casing, and after the blade wing 2 extends out of the casing, the torque transmission joint 9 is abutted on the inner wall of the casing, which guarantees that the bit body is constrained by the casing, so that the blade wing 2 will not eccentrically rotate in the drilling process, and the wellbore quality is guaranteed.

[0038] In the present application, the torque transmission joint 9 and the single universal joint 10 form an angle deflection and can be sealed while supplying slurry, specifically, the ball head 22 of the single universal joint 10 is designed with a sealing groove 21, and an O-ring is installed in the sealing groove 21 in abutment with the spherical surface. The universal joint of the prior art is solid, and a flow divider joint needs to be matched between the universal joint and the screw motor to guide the slurry out, and when the slurry flows to the bit, most of the hydraulic power has been lost, resulting in poor wellbore flushing effect. Compared with the prior art, the slurry supply pipeline 20 of the single universal joint 10 body and the torque transmission joint 9 can effectively flush the wellbore, avoid mud cake, and help the reamer bit realize the closing action of the blade wing 2.

[0039] Further, the flow cross section of the blind hole and the water eye 18 is smaller than the flow cross section of the slurry supply pipeline 20, and after the pump is opened to supply slurry, the flow cross section of the slurry passing through the blind hole and the water eye 18 becomes smaller, so that the slurry generates a throttling effect at the pressure valve core 7, according to Bernoulli's principle, a thrust is generated at this position, which pushes the pressure valve core 7 to press the end point in contact with the blade wing 2, specifically, the thrust of the slurry mainly acts on the top end of the pressure valve core 7, and the blade wing 2 is pushed up by the pressure valve core 7 with the hinge point as the fulcrum, and the action of the blade wing 2 unfolding is completed.

[0040] Moreover, the inner wall of the spherical groove is provided with a spline 23 and a spline 23 groove in a matching connection between the spline 23 and the one-way universal joint 10, and the transmission between the spherical groove and the one-way universal joint 10 is realized through the matching of the spline 23 and the spline 23 groove, thereby providing torque for the rotation of the drill bit.

[0041] As a preferred embodiment of the present application, the open end of the spherical groove is provided with a ball pressing ring 11 for limiting the disengagement of the one-way universal joint 10, the ball pressing ring 11 abuts against the outer circumferential side of the one-way universal joint 10, the one-way universal joint 10 is connected and limited by the ball pressing ring 11 and the torque transmission joint 9, and preferably the ball pressing ring 11 is a two-semicircular thin sheet with threaded holes. Preferably, the ball pressing ring 11 is fixed on the torque transmission joint 9 by the second fixing bolt 12, the ball pressing ring 11 abuts against the outer circumferential side of the one-way universal joint 10 at the same time, the ball head 22 of the entire one-way universal joint 10 is pressed on the spherical surface of the torque transmission joint 9, thereby pressing the O-ring, realizing sealing, when the pump is started, the mud will enter the torque transmission joint 9 along the mud supply channel of the one-way universal joint 10, then enter the water eye 18 through the middle hole 15 of the valve core 7, thereby avoiding mud leakage and loss, and ensuring the compact matching of the spline 23 and the spline 23 groove.

[0042] Further, the mud supply pipeline 20 on the transmission joint includes a sealing section close to the valve core 7, the top end of the valve core 7 extends out of the middle hole 15 and is slidingly and sealingly inserted into the sealing section, and preferably the valve core 7 is a stepped shaft with a large top end structure and a small bottom end structure, wherein when the valve core 7 moves downward, the top end of the valve core 7 abuts against the top end of the middle hole 15, thereby limiting the valve core 7 and avoiding the bottom end of the valve core 7 from disengaging from the V-shaped structure. During operation, the valve core 7 is inserted into the middle hole 15, the bottom end extends out of the middle hole 15 and abuts against the V-shaped structure 24 of the blade wing 2. The outer circumferential wall of the top end of the valve core 7 is provided with a sealing groove 21, the sealing section of the torque transmission joint 9 is connected with the top end of the valve core 7, the sealing section is designed with a sealing surface matched with the sealing groove 21, thereby preventing mud from flowing into the annular space between the valve core 7 and the torque transmission joint 9, strengthening the flushing effect of the mud in the water eye 18 on the blade wing 2, and at the same time, the sealing section provides a path for the axial movement of the valve core 7.

[0043] Moreover, the bottom end of the reamer bit body 1 is provided with a plurality of blade wing mounting portions 13 respectively used for mounting the blade wings 2, each blade wing mounting portion 13 circumferentially surrounds the outer circumferential side of the valve core 7, the blade wing mounting portion 13 is provided with a mounting groove used for accommodating the blade wing 2, the blade wing pin 5 used for hingedly connecting the blade wing 2 is arranged in the mounting groove, and the blade wing 2 is provided with a hinge hole 25 through which the blade wing pin 5 passes, thereby completing the hinged mounting of the blade wing 2 and facilitating the unfolding or folding of the blade wing 2.

[0044] Further, the side wall of the mounting groove is provided with a positioning pin 4 sliding along the direction perpendicular to the unfolding direction of the blade wing 2, the blade wing 2 is provided with positioning pin holes 14 distributed along the rotating direction of the blade wing 2, and the mounting groove is provided with springs for pressing the positioning pin 4 against the positioning pin holes 14. Specifically, the blade wing 2 is provided with two positioning pin holes 14, when the blade wing 2 is gathered, the positioning pin 4 is pressed against the positioning pin hole 14 close to the inner side of the blade wing 2, i.e. the first positioning pin hole 14, the valve core 7 is pressed downward to push the V-shaped structure 24 on the blade wing 2, so that the blade wing 2 is unfolded to a specified outer diameter around the positioning pin 4. At this time, the positioning pin 4 slides from the first positioning pin hole 14 on the blade wing 2 to the positioning pin hole 14 close to the outer side of the blade wing 2, i.e. the second positioning pin hole 14, at this time, the blade wing 2 is fixed in the unfolded state, and through the cooperation of the positioning pin 4 and the second positioning pin hole 14, the blade wing 2 is prevented from closing during the reaming drilling. When the reaming drilling is completed, the pump is stopped, the drill pipe is lifted, the blade wing 2 is closed after being extruded by the casing wall, at this time, the positioning pin 4 slides from the second positioning pin hole 14 on the blade wing 2 to the first positioning pin hole 14, the blade wing 2 is fixed in the closed state, and the blade wing 2 is prevented from being unfolded to cause the jamming of the bottom hole assembly during the lifting process.

[0045] Moreover, the side wall of the mounting groove is provided with a positioning channel for the positioning pin 4 to slide, the end of the positioning channel away from the blade wing 2 is detachably connected with a pin shaft pressing plate 3, preferably the installation of the pin shaft pressing plate 3 is completed through the first fixing bolt 6, the spring is abutted between the pin shaft pressing plate 3 and the positioning pin 4, wherein one end of the positioning pin 4 is designed as a round head, one end is designed as a thin rod, which is installed in the positioning channel, the spring is sleeved on the thin rod, and the round head is pressed in the positioning pin hole 14 of the blade wing 2 through the extrusion of the pin shaft pressing plate 3 on the spring. The pin shaft pressing plate 3 is fixed on the blade wing mounting portion 13 through the bolt.

[0046] The adaptive changes according to actual needs are within the protection scope of the present application.

[0047] It should be noted that, for those skilled in the art, it is obvious that the present application is not limited to the details of the above exemplary embodiments, and the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims involved.

[0048] The principles and implementation manners of the present application are described by using specific examples in the present application, and the above examples are only used for helping to understand the method of the present application and its core idea; meanwhile, for the general technical personnel in the art, according to the idea of the present application, the specific implementation manners and application ranges will be changed. In conclusion, the content of the present specification should not be understood as the limitation of the present application.

Claims

1. An underreamer for use in directional drilling of a cased hole, comprising: The reaming drill bit body is coaxially provided with a central hole at the top end, and a plurality of blade wings capable of being folded under the extrusion of the inner wall of the casing are equidistantly and circumferentially hinged at the bottom end of the reaming drill bit body, a pressure valve core capable of being pushed by mud is movably arranged in the central hole along the axial direction, a blind hole for mud to pass through is arranged at the top end of the pressure valve core, a water hole is arranged on the side wall of the pressure valve core and is in communication with the blind hole, the bottom end of the pressure valve core extends out of the reaming drill bit body and abuts against each blade wing and can push the blade wing to spread outward around the hinge point, a first flushing pipeline and a second flushing pipeline are arranged on the reaming drill bit body and are in communication with the water hole, the outlet of the first flushing pipeline is directed to the outer peripheral edge of the blade wing, and the outlet of the second flushing pipeline is directed to the inner side of each blade wing. The water hole gradually extends to the outer peripheral side of the pressure valve core along the direction of mud flow, and the inlets of the first flushing pipeline and the second flushing pipeline are located on the side of the outlet of the water hole close to the blade wing. The top end of the reaming drill bit body is detachably connected with a transmission joint abutting against the inner wall of the casing, a single-sided universal joint is arranged on the side of the transmission joint away from the reaming drill bit body, a spherical groove is arranged on the transmission joint and is rotationally connected with the single-sided universal joint, and a slurry pipeline is arranged on the transmission joint and the single-sided universal joint and is in communication with the central hole.

2. The pilot hole reamer for use in directional drilling of a cased hole according to claim 1, characterized in that, The flow cross section of the blind hole and the water hole is smaller than the flow cross section of the slurry pipeline.

3. The pilot hole reamer for use in directional drilling of a cased hole according to claim 2, characterized in that, A spline and a spline groove are arranged in embedded connection between the inner wall of the spherical groove and the single-sided universal joint.

4. The pilot hole reamer for use in directional drilling of a cased hole according to claim 3, characterized in that, A ball pressing ring is arranged at the opening end of the spherical groove and is used for limiting the single-sided universal joint from being pulled out, and the ball pressing ring abuts against the outer peripheral side of the single-sided universal joint.

5. The pilot hole reamer for use in directional drilling of a cased hole according to claim 4, characterized in that, The slurry pipeline on the transmission joint comprises a sealing section close to the pressure valve core, the top end of the pressure valve core extends out of the central hole and is slidably and sealingly inserted into the sealing section.

6. The pilot hole reamer for use in directional drilling of a cased hole according to claim 5, characterized in that, The bottom end of the reaming drill bit body is provided with a plurality of blade wing mounting portions for mounting each blade wing, each blade wing mounting portion is circumferentially arranged on the outer peripheral side of the pressure valve core, a mounting groove for accommodating the blade wing is arranged on the blade wing mounting portion, and a blade wing pin shaft for hinging the blade wing is arranged in the mounting groove.

7. The pilot hole reamer for use in directional drilling of a cased hole according to claim 6, characterized in that, A positioning pin is arranged on the side wall of the mounting groove and slides along the direction perpendicular to the spreading direction of the blade wing, a positioning pin hole is arranged on the blade wing and is spaced apart along the rotating direction of the blade wing, and a spring is arranged on the mounting groove and is used for abutting against the positioning pin and the positioning pin hole.

8. The pilot hole reamer for use in directional drilling of a cased hole according to claim 7, characterized in that, A positioning channel for the positioning pin to slide is arranged through the side wall of the mounting groove, a pin shaft pressing plate is detachably connected to the end of the positioning channel away from the blade wing, and the spring abuts against the pin shaft pressing plate and the positioning pin.

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