Telescopic drilling tools

Abstract

The present invention discloses a telescopic reaming while drilling drilling tool, comprising a piston, an end cover, a housing, a reaming cutter body and a pilot drill bit. The piston is installed in the housing, and the piston and the housing can slide axially relative to each other. The upper end of the housing is connected to the end cover, and the lower end of the housing is connected to the pilot drill bit. The reaming cutter body is arranged between the piston and the pilot drill bit and installed in the housing. The reaming cutter body can radially extend and retract and slide relative to the housing; the piston guide cone head pushes the reaming cutter body to extend under the pressure of the upper drill string to achieve reaming. When drilling, the piston moves upward, and the reaming cutter body is radially retracted when it contacts the well wall or a smaller wellbore section to complete the contraction. The telescopic reaming while drilling drilling tool of the present invention has a simple structure, is easy to operate, can quickly enter the reaming working state, and ensures the wellbore trajectory, and can realize the process of reaming while drilling. At the same time, the reaming cutter body can be easily retracted, which improves the efficiency and reliability of reaming work and prolongs the service life.

Description

Technical Field

[0001] The invention belongs to the technical field of rock-breaking tools for drilling of petroleum, natural gas, geothermal and the like, and in particular relates to a telescopic while-drilling expanding drilling tool. Background Art

[0002] With the increasing number of side drilling with casing windows and secondary development of old wells, reaming tools have been widely used. There are usually two ways to expand holes in drilling projects: first, use a conventional drill bit to drill a pilot hole (i.e., a pilot hole), and then use a reaming drill bit or tool to expand the hole, that is, the pilot hole drilling and reaming construction are carried out separately; second, use the "reaming while drilling" method to expand the hole while drilling, and complete the drilling and expansion construction at one time. Mechanical reaming while drilling is a tool used to expand the wellbore at the same time during the drilling process. Its main feature is the use of mechanical structure to control the expansion and closing of the reaming blade. These blades are usually made of wear-resistant materials and are designed to withstand high stress and wear during drilling. The expansion and closing of the blades are usually achieved by mechanical components such as springs, hinges or sliders. In addition, it is usually installed at the bottom of the drill string and connected to the drill string through specific connecting components.

[0003] The main advantages of mechanical reaming while drilling tools are their relatively simple structure and high reliability. Their design reduces the reliance on complex systems (such as hydraulic or electronic control systems), thus providing better durability and stability in harsh drilling environments, regardless of well depth and drilling fluid properties. At the same time, mechanical reaming while drilling tools are easy to operate and suitable for a variety of drilling environments, especially where reliability and cost-effectiveness are required.

[0004] However, there are also some problems with mechanical reaming while drilling tools. First, it may not be as good as hydraulic or electric reaming tools in terms of adjustment flexibility and precision, especially in complex drilling tasks that require precise control of the reaming diameter. Second, mechanical components may face a higher risk of wear in extreme drilling environments, which may lead to performance degradation and increased maintenance frequency. In addition, mechanical reaming tools may not be as flexible and effective as more advanced reaming systems when dealing with variable geological conditions. Finally, due to its design limitations, this type of drill tool may not be suitable for specific high-difficulty or special-demand drilling operations. In addition, the radial stroke of the reaming assembly is limited, the tool is large in size, and the expansion of the wellbore diameter is limited. In small-sized wellbores, due to the limitation of the tool space size, if a larger reaming size is required, it is easy to weaken the strength of the main structure and cause safety hazards. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the mechanical drilling-while-reaming drilling tools described above, and to provide a telescopic drilling-while-reaming tool to enhance the reaming capacity, improve the reaming effect, increase the drilling rate and reliability, and extend the service life.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A telescopic drilling tool for reaming while drilling comprises a piston, an end cover, a housing, a reaming cutter body and a pilot drill bit. The piston is installed in the housing, and the piston and the housing can slide axially relative to each other. The upper end of the housing is connected to the end cover, and the lower end of the housing is connected to the pilot drill bit. The reaming cutter body is arranged between the piston and the pilot drill bit and installed in the housing. The reaming cutter body can extend and retract radially relative to the housing. The reaming cutter body has at least two pieces, which are distributed circumferentially in the housing.

[0008] The piston is provided with a piston mounting end, a piston connecting outer wall, a piston anti-slip outer wall and a piston guide cone head; the diameter of the piston connecting outer wall is smaller than the diameter of the piston anti-slip outer wall, a piston anti-slip step is formed between the piston connecting outer wall and the piston anti-slip outer wall, the diameter of the piston anti-slip outer wall is larger than the inner diameter of the end cover, the piston anti-slip step is axially limited by the end cover, and a groove is provided on the piston anti-slip outer wall. The piston guide cone head includes a cylinder and a guide cone. The piston guide cone head extends into a cavity surrounded by a plurality of circumferentially distributed reaming cutter bodies. A protrusion matching the groove on the piston anti-slip outer wall is provided on the inner wall of the shell, so that the shell can rotate circumferentially with the piston and transmit torque, and can slide axially at the same time.

[0009] The angle α between the extension line of the line connecting point a and point b on the contraction surface of the extended end of the reamer body and the central axis is ≤25°. The outer diameter D1 formed by the reamer body in the contracted state is not greater than the outer diameter D of the pilot drill bit, and the outer diameter D2 formed by the reamer body in the fully extended state is greater than the outer diameter D of the pilot drill bit, exceeding D / 10 to D / 3. The outer diameter expansion H formed by the reamer body is H=D2-D1≥0.75×(L2-40), where L2 is the distance the piston moves downward relative to the housing. The length L1≥L2 of the piston connecting the outer wall.

[0010] When the telescopic reaming while drilling drill tool is lowered to the bottom of the well, the pilot drill bit contacts the bottom of the well, and under the pressure of the upper drill string, the piston is pressed to move downward along the shell, and the piston guide cone head moves downward in the cavity surrounded by the reaming cutter body, pushing the reaming cutter body to extend radially. After the reaming cutter body is extended, the outer diameter increases. Driven by the rotation of the upper drill string, the extended reaming cutter body performs the reaming work. When the drill string is lifted, the piston moves upward along the shell, the piston anti-slip step contacts the end cover to drive the reaming drill tool to rise, and the distance between the piston guide cone head and the reaming cutter body is pulled apart to form a neutral position, and the reaming cutter body can be freely contracted radially. When the reaming cutter body contacts the well wall or contacts a smaller wellbore section upward, the reaming cutter body is radially retracted to complete the contraction so as to pass through the small wellbore section.

[0011] In the above scheme, the pressure of the upper drill string is used to press the piston downward, pushing the reaming cutter body to extend radially to achieve hole expansion. When drilling, the drill string is lifted up to form a gap between the piston guide cone head and the reaming cutter body. When the reaming cutter body contacts the well wall or contacts a smaller wellbore section, the reaming cutter body is radially retracted. This working method avoids the problem of leakage, blockage or other failures of the hydraulic system of the hydraulic reaming drill due to harsh drilling environment, thereby reducing the performance of the reaming drill. The telescopic reaming drill relies on a mechanical structure to control the reaming blades. It works stably and is not affected by the well depth and drilling fluid performance. At the same time, it ensures the working efficiency of the reaming drill.

[0012] Preferably, the inner wall of the shell and the anti-slip outer wall of the piston are installed by means of straight grooves and straight protrusions, or the protrusion on the inner wall of the shell that cooperates with the groove on the anti-slip outer wall of the piston is a key, or the inner wall of the shell and the anti-slip outer wall of the piston are installed by means of splines, or the inner wall of the shell and the anti-slip outer wall of the piston are installed by means of a prismatic structure, and it is at least a quadrangular prism.

[0013] In the above scheme, the matching installation of the inner wall of the shell and the outer wall of the piston anti-slipping can transmit torque and directional movement, which is safe, reliable, simple and easy to operate. It can not only effectively transmit power, but also serve as a guide rail to allow the piston to move freely up and down. The inner wall of the shell and the outer wall of the piston anti-slipping are matched and installed through a straight groove and a straight protrusion, or the protrusion on the inner wall of the shell that matches the groove on the outer wall of the piston anti-slipping is a key, or the inner wall of the shell and the outer wall of the piston anti-slipping are matched and installed through a spline, which can reduce the friction between the inner wall of the shell and the outer wall of the piston anti-slipping and increase the moving speed of the piston. The inner wall of the shell and the outer wall of the piston anti-slipping are matched and installed through a prismatic structure, which can increase the transmitted torque.

[0014] Preferably, the number of grooves on the piston anti-slip outer wall is at least two, and the number of protrusions on the inner wall of the shell is the same as the number of grooves.

[0015] In the above scheme, multiple grooves and corresponding multiple protrusions cooperate to make the load of the piston on the housing more balanced, improving the stability and reliability of the work. More grooves and protrusions can be provided to improve the stability of torque transmission between the piston and the housing.

[0016] Preferably, the piston guide cone head is a cylindrical and truncated cone structure, and the truncated cone angle β is less than 157.16°.

[0017] In the above scheme, the cylindrical surface and the frustum surface of the piston guide cone head can withstand the huge load of the reaming cutter body during reaming, ensuring that the reaming cutter body is not retracted under pressure, so that the reaming diameter of the oil well is consistent from top to bottom. The cone angle of the piston guide cone head is less than 157.16° to prevent the piston from self-locking when it moves downward.

[0018] Preferably, the contraction surface of the extended end of the reamer body is an inclined surface.

[0019] In the above scheme, the contraction surface of the extended end of the reaming cutter body is an inclined surface to realize the cutter body recovery. When it is necessary to pull out the drill, the drill string is lifted up and the piston moves upward. When the reaming cutter body contacts the well wall or contacts a smaller wellbore section upward, the contraction surface of the extended end of the reaming cutter body is subjected to the force exerted by the well wall. The horizontal component of this force causes the reaming cutter body to be radially retracted, thereby ensuring that the reaming drill tool passes through the small wellbore section. The functional inclined surface inclination range can avoid the occurrence of self-locking.

[0020] Preferably, the reaming cutter body has three or four pieces, which are evenly arranged around the circumference.

[0021] Among the above solutions, three-piece reamer is the most common configuration, which can provide good balance and effective reaming coverage. Four or more reamer can be applied to large diameter reaming needs, which can provide a larger coverage area and higher reaming efficiency, but it may also increase the complexity and cost of the drilling tool.

[0022] Preferably, nozzles corresponding to the reaming cutter bodies are arranged obliquely upward on the outer wall of the shell.

[0023] In the above scheme, the hydraulic structure adopts a reverse nozzle, through which the cutting surface of the reaming cutter body is cleaned, effectively reducing or even avoiding the occurrence of mud packing on the reaming cutter body.

[0024] Preferably, the outer diameter D2 formed by the reamer body in a fully extended state satisfies D2-D≥D / 6-D / 4, where D is the outer diameter of the pilot drill bit.

[0025] In the above scheme, the outer diameter range enclosed by the reamer body in the fully extended state is smaller, making the telescopic drilling reaming tool more compact and reasonable.

[0026] Preferably, an anti-drop device is provided on the lower end surface of the reaming cutter body mounting hole on the shell.

[0027] In the above scheme, the anti-drop device cooperates with the lower end surface of the reaming cutter body to prevent the reaming cutter body from falling during the drilling process.

[0028] Preferably, the housing is provided with a guide cone hole, the guide cone hole is provided with a sealing device, and the sealing device is arranged at the sliding connection between the housing guide cone hole and the piston guide cone head.

[0029] In the above scheme, the sealing device provided at the sliding connection between the casing guide cone hole and the piston guide cone head can prevent drilling fluid leakage caused by the up and down fluctuation of the piston due to drilling pressure instability caused by drill jumping or other reasons during the operation of the reaming drill.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The present invention provides a telescopic reaming while drilling tool, which utilizes the pressure of the upper drill string to press the piston downward, push the reaming cutter body radially out to achieve reaming. The reaming while drilling tool has a simple structure, is easy to operate, can quickly enter the reaming working state, ensures the wellbore trajectory, and can reame the wellbore while drilling, without the need to trip the drill, thus saving costs.

[0032] (2) When it is necessary to start drilling, the drill string is lifted up to form a gap between the piston guide cone head and the reaming cutter body. When the reaming cutter body contacts the well wall or contacts a smaller wellbore section, the reaming cutter body is radially retracted. The operation is simple, the reaming cutter body is easy to retract, and the reaming drill tool passes through the wellbore smoothly, which improves work efficiency and reliability and extends service life.

[0033] (3) The telescopic drilling reaming tool has a simple structure, and does not require additional mechanisms and power for extension and retraction. It is highly reliable and easy to operate. The tool controls the extension and retraction of the reaming cutter body through normal conventional drilling operations, thereby expanding the wellbore diameter during the drilling process. This simplified design makes them particularly durable and reliable in harsh drilling environments, while also reducing the complexity and cost of maintenance and repair. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The present invention is a schematic diagram of the structure of a telescopic while-drilling hole-reaming drilling tool.

[0035] Figure 2 It is a schematic diagram of the structure of the telescopic while-drilling reaming drill cutter body in an initial state.

[0036] Figure 3 It is a structural schematic diagram of a telescopic while-drilling reaming drill tool with the reaming cutter body in an extended state.

[0037] Figure 4 It is a schematic diagram of the end cover structure.

[0038] Figure 5 It is a schematic diagram of the piston structure.

[0039] Figure 6 is with Figure 5 A schematic diagram of the general structure of a housing in which the piston is mounted.

[0040] Figure 7 yes Figure 6 Front view of the shell.

[0041] Figure 8 It is a schematic diagram of the shell structure in which the protrusions on the inner wall of the shell serve as keys.

[0042] Fig. 9 It is a schematic diagram of a piston structure in which splines are arranged on the anti-dropout outer wall of the piston.

[0043] Fig.10 is with Fig. 9 Schematic diagram of the housing structure in which the piston is installed.

[0044] Fig.11 The diagram is a schematic diagram of a piston structure in which the piston anti-dropping outer wall is a pentagonal prism structure.

[0045] Fig.12 is with Fig.11 Schematic diagram of the housing structure in which the piston is installed.

[0046] Fig.13 It is a schematic diagram of a piston structure in which the piston guide cone head is a cylindrical and truncated cone structure.

[0047] Fig.14 is with Figure 5 , Fig. 9 and Fig.11 Schematic diagram of the structure of the reamer body matching the piston shown.

[0048] Fig.15 is with Fig.13 Schematic diagram of the structure of the reamer body matching the piston shown.

[0049] Fig.16 The present invention is a schematic diagram of the end face limit structure of the piston guide cone head of the telescopic drilling and hole enlarging drilling tool.

[0050] Fig.17 It is a schematic diagram of the structure of the telescopic while-drilling reaming drill tool in the state of hole enlarging and drilling.

[0051] Fig.18 It is a schematic diagram of the structure of the telescopic while-drilling reaming drill tool reaming cutter body in the state ready to be retracted.

[0052] Reference numerals: 1-piston; 2-end cover; 3-housing; 4-reamer body; 5-pilot drill bit; 6-reverse nozzle; 7-sealing device; 8-anti-drop device; 9-flow channel; 10-well bottom; 11-reamer; 12-well wall;

[0053] 101-piston mounting end; 102-piston connecting outer wall; 103-piston anti-slip outer wall; 104-piston guide cone head; 1011-piston mounting end inner hole thread; 1031-piston upper end anti-slip step; 1032-piston anti-slip outer wall groove; 1033-piston lower end anti-slip step; 1041-piston guide cone head end face; 201-end cover inner hole step surface; 202-end cover inner hole thread; 301-housing inner wall; 302 -External thread of the shell; 303-mounting hole of the reamer body; 304-guide cone hole of the shell; 305-thread of the drill bit joint; 3011-protrusion of the inner wall of the shell; 3012-annular step of the inner wall of the shell; 3031-blind hole; 3041-bottom surface of the guide cone hole of the shell; 401-contraction surface of the extended end of the reamer body; 402-working surface of the extended end of the reamer body; 403-hemispherical pit; 404-matching surface of the reamer body; 51-nozzle of the pilot drill bit. DETAILED DESCRIPTION

[0054] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be further described below with reference to the accompanying drawings and in combination with specific embodiments.

[0055] like Figure 1-Figure 18 As shown, the present invention provides a telescopic drilling-while-drilling reaming tool and a method of using the same, comprising a piston 1, an end cover 2, a housing 3, a reaming cutter body 4 and a pilot drill bit 5. The piston 1 is installed in the housing 3, and the piston 1 and the housing 3 can slide axially relative to each other. The upper end of the housing 3 is connected to the end cover 2, and the lower end of the housing 3 is connected to the pilot drill bit 5. The reaming cutter body 4 is arranged between the piston 1 and the pilot drill bit 5, and is installed in the housing 3. The reaming cutter body 4 can radially extend and retract and slide relative to the housing 1. The reaming cutter body 4 has at least two pieces, which are distributed circumferentially in the housing 1.

[0056] The piston 1 is provided with a piston mounting end 101, a piston connecting outer wall 102, a piston anti-slip outer wall 103 and a piston guide cone head 104; the diameter of the piston connecting outer wall 102 is smaller than the diameter of the piston anti-slip outer wall 103, and a piston upper end anti-slip step 1031 is formed between the piston connecting outer wall 102 and the piston anti-slip outer wall 103. The diameter of the piston anti-slip outer wall 103 is larger than the inner diameter of the end cover 2. The piston upper end anti-slip step 1031 is axially limited by the end cover 2, and a groove 1032 is provided on the piston anti-slip outer wall 103.

[0057] The piston guide cone head 104 includes a cylinder and a guide cone in sequence. The piston guide cone head 104 extends into a cavity surrounded by a plurality of circumferentially distributed reaming cutter bodies 4. A protrusion 3011 is provided on the inner wall 301 of the housing to match the groove 1032 on the piston anti-slip outer wall 103, so that the housing 3 can rotate circumferentially with the piston 1 and transmit torque, and can slide axially at the same time.

[0058] The angle α between the extension line of the line connecting point a and point b on the contraction surface 401 of the extended end of the reamer body and the central axis is ≤25°. The outer diameter D1 formed by the reamer body 4 in the contracted state is not larger than the outer diameter D of the pilot drill bit 5, and the outer diameter D2 formed by the reamer body 4 in the fully extended state is larger than the outer diameter D of the pilot drill bit 5, exceeding D / 10 to D / 3. The enlarged amount H of the outer diameter formed by the reamer body 4 is H=D2-D1≥0.75×(L2-40), where L2 is the distance the piston 1 moves downward relative to the housing 3. The length L1≥L2 of the piston connecting the outer wall 102;

[0059] When the telescopic reaming-while-drilling drill tool is lowered to the bottom of the well 10, the pilot drill bit 5 contacts the bottom of the well 10, and under the pressure of the upper drill string, the piston 1 is pressed to move downward along the housing 3, and the piston guide cone head 104 moves downward in the cavity surrounded by the reaming cutter body 4, pushing the reaming cutter body 4 to extend radially. After the reaming cutter body 4 is extended, the outer diameter increases, and driven by the rotation of the upper drill string, the extended reaming cutter body 4 realizes the reaming 11 work.

[0060] When it is necessary to start drilling, the drill string is lifted up, the piston 1 moves upward along the housing 3, the anti-slip step 1031 on the upper end of the piston contacts the step surface 201 of the inner hole of the end cover to drive the reaming drill tool to rise, and the piston guide cone head 104 and the reaming cutter body 4 are separated to form a gap, and the reaming cutter body 4 can freely shrink radially. When the reaming cutter body 4 contacts the well wall 12 or contacts a smaller wellbore section upward, the reaming cutter body 4 is radially retracted to complete the shrinkage so as to pass through the small wellbore section.

[0061] like Figure 1As shown, it is a schematic diagram of the structure of the telescopic drilling reaming tool provided by an embodiment of the present invention. Specifically, the piston 1 is connected to the drill tool above through the piston mounting end 101, and the piston 1 is installed in the housing 3. The piston 1 and the housing 3 transmit torque and speed through the groove 1032 set on the piston anti-slip outer wall 103 and the protrusion 3011 set on the housing inner wall 301, and slide relative to each other axially. The piston 1 forms a piston lower end anti-slip step 1033 between the piston guide cone head 104 and the piston anti-slip outer wall 103 to limit the lower end axially, and at the same time transmit the drilling pressure to the housing. An end cover 2 is connected to the upper end of the housing 3, and its function is to limit the upper end axial position of the piston 1. The end cover 1 can be processed separately and then fixed on the outer wall of the housing 3 by threading or welding, or it can be processed integrally with the housing 3. Three reaming cutter bodies 4 are arranged between the piston 1 and the pilot drill bit 5, which are evenly distributed in the housing 1 along the circumference, and their function is to realize the reaming 11. The reaming cutter body 4 can extend radially and shrink and slide relative to the housing 1. Since the piston 1 can slide axially relative to the housing 3, as the piston 1 slides downward, the piston guide cone head 104 passes through the cavity surrounded by the reaming cutter body 4 and extends to the housing guide cone hole 304, while pushing the reaming cutter body 4 to extend radially to achieve the reaming 11. When it is necessary to start drilling, the piston 1 moves upward along the housing 3. When the reaming cutter body 4 contacts the well wall or contacts a smaller wellbore section upward, the reaming cutter body 4 is radially retracted to complete the contraction. An anti-drop device 8 is provided between the reaming cutter body 4 and the housing 3. The housing 3 is fixedly connected to the pilot drill bit 5 below through the drill bit joint thread 305. The rotation of the housing 3 drives the rotation of the pilot drill bit 5 to break the rock. It should be noted that in order to enable the drilling fluid to circulate smoothly, a flow channel 9 is provided in the core of the piston 1 and the housing 3, and is connected to the flow channel 9 of the pilot drill bit 5. Finally, the drilling fluid flows out from the pilot drill bit nozzle 51.

[0062] The anti-drop device 8 can be a combination of spring steel balls.

[0063] like Figure 2 and Figure 3 The figure shows the structure of the telescopic reaming tool reaming cutter body 4 in the initial state and the extended state. The outer diameter D1 formed by the reaming cutter body 4 in the retracted state is not larger than the outer diameter D of the pilot drill bit 5, and the outer diameter D2 formed by the reaming cutter body 4 in the fully extended state is larger than the outer diameter D of the pilot drill bit 5, exceeding D / 10 to D / 3. The outer diameter expansion amount H formed by the reaming cutter body 4 is H=D2-D1≥0.75×(L2-40), where L2 is the distance the piston 1 moves downward relative to the housing 3.

[0064] like Figure 4The figure is a schematic diagram of the structure of the end cover 2. In this embodiment, an internal thread 202 is provided in the inner hole of the end cover 2 for fixed connection with the housing 1, and an inner hole step surface 201 is provided, and the inner hole step surface 201 contacts the anti-slip step 1031 on the upper end of the piston to limit the axial upward sliding of the piston 1.

[0065] like Figure 5 The figure is a schematic diagram of the structure of the piston 1. The piston mounting end 101 is provided with an inner hole thread 1011 for connecting with the upper drilling tool housing. The piston anti-slip outer wall 103 is provided with at least one groove 1032, and a plurality of grooves 1032 are evenly distributed along the circumference, and are used to cooperate with the protrusion 3011 on the inner wall of the housing 3 to transmit torque, rotation speed and realize relative axial sliding. The groove on the piston anti-slip outer wall 103 can be a straight groove 1032, a key groove 1032, or a spline groove 1032 (such as Fig. 9 ) to achieve greater torque transmission. The piston guide cone head 104 is composed of a cylinder and a guide cone, which plays a role in pushing the reamer body 4 to extend radially. The cone angle β<157.16° can prevent self-locking when the piston 1 moves downward. The piston guide cone head 104 can also be composed of only a cylinder and a cone (such as Fig.13 ).

[0066] like Figure 6 and Figure 7 As shown, Figure 5 The upper outer wall of the housing 3 is provided with an external thread 302 for connecting with the end cover 2, and the inner wall 301 of the end housing is provided with a protrusion 3011, the number of which is consistent with the number of grooves 1032 on the piston anti-slip outer wall 103, and is used to cooperate with the grooves 1032 of the piston anti-slip outer wall for installation. The housing inner wall protrusion 3011 can be in line with the linear groove 1032 of the piston anti-slip outer wall (such as Figure 5 ) with the linear projection 3011 (such as Figure 6 and Figure 7 ), or a keyway matching the piston anti-slip outer wall keyway 1032 connected by a key 3011 (such as Figure 8 ), or it may be a spline 1032 (such as Fig. 9 ) matching spline groove 3011 (such as Fig.10 ). Among them, the groove of the piston anti-slip outer wall and the protrusion of the shell inner wall can be interchangeable. And the shell 3 and the piston 1 can also be installed in conjunction with the prismatic structure to play the role of transmitting torque, speed and achieving relative axial sliding, such as Fig.11 and Fig.12As shown, the inner wall 301 of the housing is a pentagonal prism structure and is installed in coordination with the pentagonal prism structure of the piston anti-slip outer wall 103. The lower part of the housing 3 is connected to the pilot drill 5 through the drill joint thread 305. The inner wall 301 of the housing is provided with an annular step 3012, which contacts the anti-slip step 1033 at the lower end of the piston, and plays a role in limiting the axial downward sliding of the piston 1 (such as Figure 3 ), or the piston guide cone head end face 1041 contacts the housing guide cone hole bottom face 3041 to perform axial limiting (such as Fig.16 ).

[0067] At least two reaming cutter body mounting holes 303 are provided in the shell 3, and a blind hole 3031 is also provided on the lower end surface of the reaming cutter body mounting hole, and an anti-drop device 8 is installed to limit the small load of the reaming cutter body 4. When the radial thrust generated by the piston guide cone head 104 on the reaming cutter body 4 increases, the anti-drop device 8 fails, so that the reaming cutter body 4 can slide radially relative to the shell 3 and extend. Of course, there can be other ways to prevent the reaming cutter body 4 from falling off the shell 3. A shell guide cone hole 304 is provided below the reaming cutter body mounting hole 303 in the shell 3, which is used to axially guide and straighten the piston guide cone head 104 when the piston 1 moves downward, so that the piston 1 moves more smoothly when moving downward. A sealing device 7 is provided in the shell guide cone hole 304 to prevent leakage of high-pressure drilling fluid. A reverse nozzle 6 corresponding to the reaming cutter body 4 is arranged on the outer wall of the shell 3 below the shell reaming cutter body mounting hole 303. The reverse nozzle 6 is used to effectively reduce or even avoid the occurrence of mud balling.

[0068] The sealing device 7 may include a sleeve and a rubber sleeve. The sleeve is mainly used to press the rubber sleeve to fix it, thereby preventing the rubber sleeve from falling off during transportation and the like.

[0069] The reverse nozzle 6 can be fixed in the nozzle hole of the housing by an internal retaining spring, and the nozzle processing hole is blocked by a screw.

[0070] like Fig.14 As shown, Figure 5 , Fig. 9 and Fig.11 Schematic diagram of the structure of the reaming tool body 4 matching the piston 1 shown. The angle α between the extension line of the line connecting point a and point b on the shrinking surface 401 of the extended end of the reaming tool body and the central axis is ≤25°, which can prevent self-locking when the reaming tool body 4 shrinks. In this embodiment, the shrinking surface 401 of the extended end of the reaming tool body is an inclined surface, and the working surface 402 of the extended end is inlaid with cutting teeth. The mating surface 404 of the reaming tool body in contact with the piston guide cone head 104 is a curved surface to increase the contact area and better fit the piston guide cone head 104, and its contour shape matches the piston guide cone head 104. The mating surface 404 of the reaming tool body can be composed of a cylindrical surface and a frustum (such as Fig.14 ), or it may be with the piston guide cone head 104 (such as Fig.13 ) matching conical surface (such as Fig.15 ). The lower end of the reamer body 4 is provided with an anti-drop hemispherical pit 403, and the anti-drop device 8 is used to limit the sliding.

[0071] like Fig.17 The figure shows a schematic diagram of the structure of the telescopic reaming while drilling tool in the state of reaming drilling. When the telescopic reaming while drilling tool is lowered to the bottom of the well 10, the pilot drill bit 5 contacts the bottom of the well 10, and under the pressure of the upper drill string, the piston 1 moves downward along the housing 3, and the piston guide cone head 104 moves downward in the cavity surrounded by the reaming cutter body 4 to the guide cone hole 304 of the housing, pushing the reaming cutter body 4 to extend radially, and the outer diameter of the reaming cutter body 4 increases after being extended, and driven by the rotation of the upper drill string, the extended reaming cutter body 4 realizes the work of reaming 11.

[0072] like Fig.18 The figure shows a schematic diagram of the structure of the telescopic reaming tool while drilling in the state of preparing for the contraction of the reaming cutter body. When it is necessary to start drilling, the drill string is lifted, the piston 1 moves upward along the housing 3, the anti-slip step 1031 on the upper end of the piston contacts the step surface 201 of the inner hole of the end cover to drive the reaming tool to rise, and the distance between the piston guide cone head 104 and the reaming cutter body 4 is pulled apart to form a neutral position, and the reaming cutter body 4 can freely contract radially. When the reaming cutter body 4 contacts the well wall 12 or contacts a smaller wellbore section upward, the reaming cutter body 4 is radially retracted to complete the contraction so as to pass through the small wellbore section.

[0073] 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 in the protection scope of the present invention.

Claims

1. A telescopic drilling tool for reaming while drilling, comprising a piston, an end cover, a housing, a reaming cutter body and a pilot drill bit, characterized in that: The piston is installed in the housing, and the piston and the housing can slide axially relative to each other. The upper end of the housing is connected to the end cover, and the lower end of the housing is connected to the pilot drill bit. The reaming cutter body is arranged between the piston and the pilot drill bit and installed in the housing. The reaming cutter body can extend and retract radially relative to the housing and slide. The reaming cutter body has at least two pieces and is distributed circumferentially in the housing. The piston is provided with a piston mounting end, a piston connecting outer wall, a piston anti-slipping outer wall and a piston guide cone head; the diameter of the piston connecting outer wall is smaller than the diameter of the piston anti-slipping outer wall, a piston anti-slipping step is formed between the piston connecting outer wall and the piston anti-slipping outer wall, the diameter of the piston anti-slipping outer wall is larger than the inner diameter of the end cover, the piston anti-slipping step is axially limited by the end cover, and a groove is provided on the piston anti-slipping outer wall; The piston guide cone head comprises a cylinder and a guide cone, and the piston guide cone head is a cylinder and a truncated cone structure, and the truncated cone angle β is less than 157.16°; The piston guide cone head extends into a cavity surrounded by a plurality of circumferentially distributed reaming cutter bodies; The inner wall of the housing is provided with a protrusion that matches with the groove on the anti-slip outer wall of the piston, so that the housing can rotate circumferentially with the piston and transmit torque, and can slide axially at the same time; The angle α between the extension line of the line connecting point a and point b on the contraction surface of the extended end of the reamer body and the central axis is ≤25°; The outer diameter D1 of the reamer body in the retracted state is not greater than the outer diameter D of the pilot drill bit, and the outer diameter D2 of the reamer body in the fully extended state is greater than the outer diameter D of the pilot drill bit, exceeding D / 10 to D / 3; The outer diameter expansion H formed by the reamer body is H=D2-D1≥0.75×(L2-40), where L2 is the distance the piston moves downward relative to the housing; The length of the piston connecting the outer wall is L1≥L2; When the telescopic reaming while drilling drill tool is lowered to the bottom of the well, the pilot drill bit contacts the bottom of the well, and under the pressure of the upper drill string, the piston is pressed to move downward along the shell, and the piston guide cone moves downward in the cavity surrounded by the reaming cutter body, pushing the reaming cutter body to extend radially. After the reaming cutter body is extended, the outer diameter increases, and driven by the rotation of the upper drill string, the extended reaming cutter body realizes the reaming work; When the drill string is lifted up, the piston moves upward along the shell, the piston anti-slip step contacts the end cover to drive the reaming drill tool to rise, and the piston guide cone head and the reaming cutter body are separated to form a gap, and the reaming cutter body can freely shrink radially. When the reaming cutter body contacts the well wall or contacts a smaller wellbore section, the reaming cutter body is radially retracted to complete the shrinkage so as to pass through the small wellbore section.

2. The telescopic drilling tool for expanding the hole while drilling according to claim 1, characterized in that: The inner wall of the shell and the anti-slip outer wall of the piston are installed by means of a straight groove and a straight protrusion, or the protrusion on the inner wall of the shell that cooperates with the groove on the anti-slip outer wall of the piston is a key, or the inner wall of the shell and the anti-slip outer wall of the piston are installed by means of a spline, or the inner wall of the shell and the anti-slip outer wall of the piston are installed by means of a prismatic structure, and it is at least a quadrangular prism.

3. The telescopic drilling tool for expanding the hole while drilling according to claim 2, characterized in that: The number of grooves on the anti-dropping outer wall of the piston is at least two, and the number of protrusions on the inner wall of the shell is the same as the number of the grooves.

4. The telescopic drilling-while-drilling drilling tool according to claim 1, characterized in that: The contraction surface of the extended end of the reamer body is an inclined surface.

5. The telescopic drilling tool for expanding the hole while drilling according to claim 1, characterized in that: The reaming cutter body has three or four pieces, which are evenly arranged in a circle.

6. The telescopic drilling-while-drilling drilling tool according to claim 1, characterized in that: The outer wall of the shell is obliquely upwardly provided with nozzles corresponding to the reaming cutter bodies one by one.

7. The telescopic drilling tool for expanding the hole while drilling according to claim 1, characterized in that: The outer diameter D2 formed by the reamer body in the fully extended state satisfies D2-D≥D / 6~D / 4, where D is the outer diameter of the pilot drill bit.

8. The telescopic drilling-while-drilling drilling tool according to claim 1, characterized in that: The lower end surface of the reaming cutter body mounting hole on the shell body is provided with an anti-drop device.

9. The telescopic drilling-while-drilling drilling tool according to claim 1, characterized in that: The housing is provided with a guide cone hole, the guide cone hole is provided with a sealing device, and the sealing device is arranged at the sliding connection between the guide cone hole of the housing and the guide cone head of the piston.

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