Diameter-expanding flat-bottom milling shoe

Abstract

The invention discloses a diameter-expanding flat-bottom milling shoe, and belongs to the field of drill rod finishing tools applied to oil and gas exploitation. The center pipe is sleeved with the guide pipe, and a reset spring is arranged at the upper end of the center pipe. The supporting circular tube is coaxially fixed at the lower end of the central tube; the upper end of the milling shoe main body is connected with the guide pipe, and the lower end of the milling shoe main body slidably sleeves the supporting round pipe; a plurality of milling shoes are arranged at the lower end of the milling shoe main body along a circumferential array and are integrally formed with the milling shoe main body, the lower end surfaces of the milling shoes are milling surfaces, the milling surfaces are inclined relative to the axis of the milling shoe main body, and the inner walls of the milling shoes are provided with guide inclined surfaces; an annular cavity is formed among the lower end face of the guide pipe, the upper end face of the supporting round pipe, the outer wall of the center pipe and the inner wall of the milling shoe body, and a through hole communicated with the annular cavity is formed in the side wall of the center pipe. The scheme can adapt to a well hole after diameter expansion, the fish top is completely covered, so that the fish top is trimmed to be of a flat structure, and the phenomenon that a drilling tool is stuck by a side window opening machine can be prevented.

Description

Technical Field

[0001] The invention belongs to the field of drill rod dressing tools used in oil and gas production, and in particular relates to an expanded diameter flat-bottom grinding shoe. Background Art

[0002] When the fluid corrosion causes the drill bit to corrode and break off from the wellhead, it breaks at a depth of more than 1,000 meters, resulting in a fish hole of more than 300 meters in the well. At the same time, the open hole section is pickled many times and the well diameter is expanded, resulting in the upper and lower sections of the drill bit fracture crossing each other for several meters. In addition, when the drill bit breaks, it is accompanied by a large rotation torque. The top of the fish hole, that is, the fracture of the top of the fish hole, is very easy to deform, so that the fish top forms an elliptical structure or a flat mouth structure similar to an ellipse, and the fracture is not in the same section of the drill pipe, but presents an inclined structure. Therefore, before making a buckle, the fracture of the fish top needs to be corrected to a flat end face. Making a buckle means processing threads at the top of the fish hole to facilitate the connection of salvage tools. Because of the expansion of the well diameter and the crossing of the drill pipe, the fish top of the fish hole will be biased to one side of the open hole.

[0003] When correcting the fish top, conventional milling tools are limited in size and cannot normally mill the downhole drill pipe. After milling, eccentric grinding may occur, causing the fish top to become a pen tip shape, and may even cause the milled window to be drilled out sideways. If a forging and milling solution is adopted and a conical milling tool is used to mill the drill pipe, it is easy to form banana peel-like lumps of iron sheets and cause drill jamming. The so-called banana peel-like lumps of iron sheets refer to the fact that part of the iron sheets cannot form debris during milling, but are squeezed by the conical milling tool and spread out to the surroundings and get stuck with the side wall of the wellbore, causing drill jamming. Summary of the invention

[0004] In order to solve the deficiencies of the prior art, the present invention provides an expanded flat-bottom grinding shoe, which can adapt to the expanded wellbore and completely cover the fish top, thereby trimming the fish top into a flat structure and preventing the side window machine from getting stuck.

[0005] In order to achieve the purpose of the present invention, the following scheme is proposed: A diameter-enlarged flat-bottom grinding shoe comprises a center pipe, a guide pipe, a supporting circular pipe and a grinding shoe body.

[0006] The upper end of the center tube is used to connect the drill pipe; The guide tube is coaxially sleeved on the center tube, and a return spring is provided at the upper end of the center tube for applying a downward thrust to the guide tube; The supporting circular tube is coaxially fixed to the lower end of the central tube; The main body of the grinding shoe is a round tube structure, the upper end of which is connected to the guide tube, and the lower end of which is slidably sleeved on the outside of the supporting round tube; A plurality of grinding shoes are arranged along the circumference of the lower end of the grinding shoe body, which are integrally formed with the grinding shoe body. The lower end surface of the grinding shoe is a milling surface, which is inclined relative to the axis of the grinding shoe body. The inner wall of the grinding shoe has a guiding inclined surface, which is inclined toward the upper side of the axis of the grinding shoe body. An annular chamber is formed between the lower end surface of the guide tube, the upper end surface of the supporting circular tube, the outer wall of the central tube and the inner wall of the grinding shoe body, and a through hole communicating with the annular chamber is opened on the side wall of the central tube; When the circulating fluid inside the center tube enters the annular chamber through the through hole, the pressure inside the annular chamber increases, which is used to make the guide tube and the grinding shoe body move upward relative to the supporting circular tube. The lower end of the supporting circular tube pushes the grinding shoe to open outward through sliding contact with the guide inclined surface, which is used to make the milling surfaces of all the grinding shoes in the same plane.

[0007] The beneficial effects of the present invention are as follows: the present invention utilizes circulating fluid to push the mill shoe body to move relative to the center tube and the supporting circular tube, and during the downward movement of the supporting circular tube relative to the mill shoe body, the mill shoe is pushed to open outward, so that it can adapt to the enlarged open hole wellbore, so that the milling surface completely covers the fish top, and after the mill shoe is opened, the milling surface is in the same plane, so the fish top can be processed into a flat structure; the present invention can effectively prevent the side window phenomenon of the mill shoe when trimming the fish top, and the present invention utilizes the milling surface formed on the bottom of the mill shoe to completely cover the fish top port, which can effectively prevent the formation of banana peel-like iron sheets and cause drill jamming. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present invention.

[0009] Figure 1 The overall external structure diagram of the present application is shown when the grinding shoes are folded.

[0010] Figure 2 An overall cross-sectional view of the present application is shown when the grinding shoe is folded.

[0011] Figure 3 Shows Figure 2 A partial enlarged view of point A in the middle.

[0012] Figure 4 Shown along Figure 2 Cross-sectional view along the BB direction.

[0013] Figure 5 The structural explosion diagram of the center tube, the supporting circular tube, the mill shoe body and the mill shoe is shown.

[0014] Figure 6 The overall external structure of the present application is shown when the grinding shoe is opened.

[0015] Figure 7 Shows Figure 6 A partial enlarged view of point C in the middle.

[0016] Figure 8 An overall cross-sectional view of the present application is shown when the grinding shoe is opened.

[0017] Fig. 9 Shows Figure 8 A partial enlarged view of point D in the middle.

[0018] Fig.10 Shown along Figure 8 Cross-sectional view along the EE direction.

[0019] Markings in the figure: center tube-1, return spring-11, annular chamber-12, through hole-13, guide tube-2, supporting circular tube-3, limit strip-31, chamfered slope-32, water eye-33, grinding shoe body-4, grinding shoe-41, milling surface-411, guide slope-412, guide groove-413, upper joint-5. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions and advantages of the embodiments of the present invention more clear, the implementation modes of the present invention are described in detail below with reference to the accompanying drawings. However, the embodiments described in the present invention are only part of the embodiments of the present invention, rather than all the embodiments.

[0021] like Figures 1 to 3 and Figures 6 to 9 As shown, an expanded diameter flat-bottom grinding shoe comprises: a center tube 1, a guide tube 2, a supporting circular tube 3 and a grinding shoe body 4.

[0022] The upper end of the central tube 1 is used to connect the drill pipe.

[0023] The guide tube 2 is coaxially sleeved on the central tube 1 . A return spring 11 is provided at the upper end of the central tube 1 for applying a downward thrust to the guide tube 2 .

[0024] The supporting circular tube 3 is coaxially fixed to the lower end of the central tube 1, that is, a fixed connection structure is maintained between the supporting circular tube 3 and the central tube 1, and the upper and lower ends of the central tube 1 and the supporting circular tube 3 are connected for circulating the circulating fluid.

[0025] The grinding shoe body 4 is a circular tube structure, the upper end of which is connected to the guide tube 2 , and the lower end of which is slidably sleeved on the outside of the supporting circular tube 3 .

[0026] A plurality of grinding shoes 41 are provided along a circumferential array at the lower end of the grinding shoe body 4, which are integrally formed with the grinding shoe body 4. During specific processing and manufacturing, a plurality of cracks are opened along a circumferential array at the lower end of the grinding shoe body 4, and the solid parts between adjacent cracks are the grinding shoes 41. The lower end surface of the grinding shoe 41 is a milling surface 411, and the milling surface 411 is inclined relative to the axis of the grinding shoe body 4. The inner wall of the grinding shoe 41 has a guide bevel 412, and the guide bevel 412 is inclined toward the upper side of the axis of the grinding shoe body 4.

[0027] An annular chamber 12 is formed between the lower end surface of the guide tube 2 , the upper end surface of the supporting circular tube 3 , the outer wall of the central tube 1 and the inner wall of the grinding shoe body 4 . A through hole 13 communicating with the annular chamber 12 is formed on the side wall of the central tube 1 .

[0028] When the return spring 11 is extended, the lower end of the supporting circular tube 3 is located at the upper end of the grinding shoe 41 . It can be seen that at this time, the distance between the guide tube 2 and the supporting circular tube 3 is the smallest.

[0029] When the circulating fluid in the center tube 1 enters the annular chamber 12 through the through hole 13, the internal pressure of the annular chamber 12 increases, so that the guide tube 2 and the grinding shoe body 4 move upward together relative to the supporting circular tube 3. In this process, the reset spring 11 will be compressed, and the lower end of the supporting circular tube 3 pushes the grinding shoe 41 to open outward through sliding contact with the guide inclined surface 412, so that the milling surfaces 411 of all the grinding shoes 41 are in the same plane. As a further preferred solution, the plane is perpendicular to the axis of the grinding shoe body 4. It can be known from the reverse deduction that when the reset spring 11 is extended, the inclination of the milling surface 411 is toward the bottom of the axis of the grinding shoe body 4; the outer wall of the supporting circular tube 3 and the inner hole of the grinding shoe body 4 and the guide tube 2 and the center tube 1 are all sealed connections. Specifically, a sealing ring can be provided between the outer wall of the supporting circular tube 3 and the inner hole of the grinding shoe body 4 or a labyrinth sealing structure can be designed to achieve the purpose of sealing connection. From the above structure and state description, it can be seen that when the expanded flat-bottomed mill is lowered into the well, there is no need to increase the pressure inside the annular chamber 12. At this time, under the action of the reset spring 11, the lower end of the supporting circular tube 3 will be at the upper end of the mill 41. At this time, the mill 41 has not yet opened outwards and is in a retracted state, so as to facilitate the lowering of the expanded flat-bottomed mill into the well. When trimming the fish top, the expanded flat-bottomed grinding shoe is lowered to the fish top, the circulating pump on the bottom is started, and circulating water is added to the central tube 1 through the drill pipe. The circulating water enters the annular chamber 12 through the through hole 13, pushing the guide tube 2 to move upward, and making the grinding shoe body 4 move upward relative to the supporting circular tube 3, so that the lower end edge of the supporting circular tube 3 is used to slide in contact with the guiding inclined surface 412. Because the guiding inclined surface 412 is inclined toward the upper end of the axis of the grinding shoe body 4, when the supporting circular tube 3 moves downward, it will push the grinding shoe 41 to open outward, so as to adapt to the enlarged open hole wellbore, so that the milling surface 411 completely covers the fish top, and after the grinding shoe 41 is opened, the milling surface 411 is in the same plane, and the fish top can be processed into a flat structure after processing the fish top, so as to facilitate subsequent processing of the fish top. After the fish top is trimmed, the circulating water pressure is reduced or the circulating water is turned off. Under the action of the reset spring 11, the guide tube 2 will drive the mill shoe body 4 to descend relative to the center tube 1, and the supporting circular tube 3 will also remove the thrust on the guide slope 412. Because the mill shoe 41 and the mill shoe body 4 are an integrally formed structure, the elastic deformation of the metal can be used to make the mill shoe 41 automatically contract toward the middle, so as to facilitate the removal of the expanded diameter flat-bottom mill shoe from the well.

[0030] Preferably, Figure 1 , Figure 2 and Figure 6 , Figure 8 As shown, the upper end of the center tube 1 is connected to the upper joint 5 by threads, and the return spring 11 is a cylindrical spring structure, which is sleeved on the center tube 1. The return spring 11 is compressed between the lower end surface of the upper joint 5 and the upper end surface of the guide tube 2.

[0031] Preferably, Figure 3 , Figure 4 , Figure 6 , Fig. 9 and Fig.10 As shown, a guide groove 413 is provided on the inner wall of the grinding shoe 41, and the guide groove 413 is inclined relative to the axis of the grinding shoe body 4, and the inclination angle is consistent with the guide inclined surface 412. The consistent inclination angle here includes not only the consistent angle size, but also the consistent position of the angle. The outer wall of the supporting circular tube 3 is provided with a limiting strip 31 corresponding to the guide groove 413 along the length direction. The limiting strip 31 is parallel to the supporting circular tube 3, and the limiting strip 31 is slidably arranged in the corresponding guiding groove 413. Through the cooperation between the limiting strip 31 and the guiding groove 413, the circumferential torsional strength of the grinding shoe 41 can be effectively improved, the grinding shoe 41 can be prevented from being skewed and deformed, and the finishing accuracy of the fish top can be improved; in order to meet the cooperation between the supporting circular tube 3 and the grinding shoe body 4, an avoidance groove 414 is provided on the inner wall of the grinding shoe body 4 to accommodate the limiting strip 31, which can be reasonably deduced according to the above technical solution.

[0032] Further preferably, the width dimension of the connection between the limit strip 31 and the supporting circular tube 3 is smaller than the width of the outer side of the limit strip 31. The width here refers to the dimension of the limit strip 31 along the tangent direction of the supporting circular tube 3, and the cross section of the guide groove 413 matches the cross section of the limit strip 31. Specifically, the cross section of the limit strip 31 is T-shaped, three-quarter circular or isosceles trapezoidal. When the cross section of the limit strip 31 is T-shaped, the vertical section of the cross section is connected to the supporting circular tube 3, and the horizontal section is located on the outer side of the supporting circular tube 3; when the limit strip 31 is three-quarter circular, the side corresponding to the chord length of the cross section is connected to the outer wall of the supporting circular tube 3, and the diameter parallel to the chord length is located on the outer side of the supporting circular tube 3; such as Figure 4 , Figure 5 and Fig.10 As shown, when the cross-section of the limit strip 31 is an isosceles trapezoid, the top edge of its cross-section is connected to the outer wall of the supporting circular tube 3, and the bottom edge of its cross-section is located on the outside of the supporting circular tube 3; the above three structures all meet the requirement that the width dimension of the connection between the limit strip 31 and the supporting circular tube 3 is smaller than the width of the outer side of the limit strip 31, but the structure that meets this requirement is not limited to the three structures of T-shape, three-quarter circle and isosceles trapezoid; the above structural design can further improve the strength of the matching structure between the mill shoe 41 and the supporting circular tube 3, and during the resetting process, when the mill shoe body 4 moves downward relative to the supporting circular tube 3, the mill shoe 41 will be pulled toward the middle through the cooperation between the limit strip 31 and the guide groove 413 to prevent the mill shoe 41 from being unable to be retracted and increasing the difficulty of removing the expanded diameter flat-bottomed mill shoe.

[0033] Preferably, Figure 5As shown, there is a chamfered surface 32 between the adjacent limit strips 31 at the lower end of the supporting circular tube 3, which is used to avoid the grinding shoe 41 to prevent interference between the lower end of the supporting circular tube 3 and the inner wall of the grinding shoe 41 when the limit strip 31 cooperates with the guide groove 413, thereby causing the limit strip 31 and the guide groove 413 to get stuck.

[0034] Preferably, Figure 7 , Fig. 9 As shown, water holes 33 are opened between the side walls of the supporting circular tube 3 corresponding to the adjacent milling shoes 41, and the water holes 33 are connected to the inside of the supporting circular tube 3. When the milling shoes 41 are in the retracted state, the water holes 33 are located in the milling shoe body 4. At this time, the circulating liquid cannot be sprayed outward through the water holes 33, so as to avoid insufficient internal pressure of the annular chamber 12 due to the increase in the discharge amount of the circulating liquid, which in turn affects the opening of the milling shoes 41; in order to make the inside of the central tube 1 have sufficient pressure, the bottom of the central tube 1 can also be blocked by throwing a ball into the central tube 1. When the milling shoes 41 are opened outward, the water holes 33 are located in the gap between adjacent milling shoes 41. At this time, the liquid sprayed from the water holes 33 can be used to flush the debris and impurities between the milling shoes 41, so as to avoid affecting the retraction of the milling shoes 41.

[0035] The above description is only a preferred embodiment of the present invention, and is not intended to be the only one or to limit the present invention. Those skilled in the art should understand that various changes or equivalent substitutions made to the present invention without departing from the scope of the present invention are within the scope of protection of the present invention.

Claims

1. An expanded diameter flat-bottom grinding shoe, characterized in that: include: A center pipe (1), the upper end of which is used to connect to a drill pipe; The guide tube (2) is coaxially sleeved on the center tube (1), and a return spring (11) is provided at the upper end of the center tube (1) for applying a downward thrust to the guide tube (2); A supporting circular tube (3) coaxially fixed to the lower end of the central tube (1); The grinding shoe body (4) is a circular tube structure, the upper end of which is connected to the guide tube (2), and the lower end of which is slidably sleeved on the outside of the supporting circular tube (3); A plurality of grinding shoes (41) are arranged in a circumferential array at the lower end of the grinding shoe body (4), and are integrally formed with the grinding shoe body (4); the lower end surface of the grinding shoe (41) is a milling surface (411), and the milling surface (411) is inclined relative to the axis of the grinding shoe body (4); the inner wall of the grinding shoe (41) has a guiding inclined surface (412), and the guiding inclined surface (412) is inclined toward the upper side of the axis of the grinding shoe body (4); An annular chamber (12) is formed between the lower end surface of the guide tube (2), the upper end surface of the supporting circular tube (3), the outer wall of the central tube (1) and the inner wall of the grinding shoe body (4), and a through hole (13) communicating with the annular chamber (12) is provided on the side wall of the central tube (1); When the circulating fluid inside the central tube (1) enters the annular chamber (12) through the through hole (13), the pressure inside the annular chamber (12) increases, so that the guide tube (2) and the grinding shoe body (4) move upward together relative to the supporting circular tube (3), and the lower end of the supporting circular tube (3) pushes the grinding shoes (41) to open outward by sliding contact with the guide inclined surface (412), so that the milling surfaces (411) of all the grinding shoes (41) are in the same plane.

2. The expanded diameter flat-bottom grinding shoe according to claim 1, characterized in that: The upper end of the center tube (1) is connected to an upper joint (5) via a thread. The return spring (11) is a cylindrical spring structure which is sleeved on the center tube (1). The return spring (11) is compressed between the lower end surface of the upper joint (5) and the upper end surface of the guide tube (2).

3. The expanded diameter flat-bottom grinding shoe according to claim 1, characterized in that: A guide groove (413) is provided on the inner wall of the grinding shoe (41), the guide groove (413) is inclined relative to the axis of the grinding shoe body (4), and the inclination angle is consistent with the guide inclined surface (412), and a limiting strip (31) matching the guide groove (413) in a one-to-one correspondence is provided on the outer wall of the supporting circular tube (3) along the length direction, the limiting strip (31) is parallel to the supporting circular tube (3), and the limiting strip (31) is slidably arranged in the corresponding guide groove (413).

4. The expanded diameter flat-bottom grinding shoe according to claim 3, characterized in that: The width of the connection between the limiting strip (31) and the supporting circular tube (3) is smaller than the width of the outer side of the limiting strip (31), wherein the width refers to the dimension of the limiting strip (31) along the tangent direction of the supporting circular tube (3), and the cross section of the guide groove (413) matches the cross section of the limiting strip (31).

5. The expanded diameter flat-bottom grinding shoe according to claim 4, characterized in that: The lower ends of the supporting circular tubes (3) are provided with chamfered inclined surfaces (32) between the adjacent limiting strips (31) for avoiding the grinding shoes (41).

6. The expanded diameter flat-bottom grinding shoe according to claim 1, characterized in that: Water holes (33) are provided between the side walls of the supporting circular tube (3) and the adjacent grinding shoes (41). The water holes (33) are communicated with the interior of the supporting circular tube (3). When the grinding shoes (41) are in a retracted state, the water holes (33) are located inside the grinding shoe body (4). When the grinding shoes (41) are opened outward, the water holes (33) are located in the gaps between adjacent grinding shoes (41).

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