Reamer while drilling capable of being activated and closed multiple times and activating and closing method

Abstract

The invention provides a while-drilling reamer capable of being activated and closed for multiple times, which comprises a reamer body and an executing mechanism, a center flow channel allowing drilling fluid to pass through is formed in the reamer body, the executing mechanism comprises a side hole pressure transmission connector arranged in the center flow channel and a side through sleeve connected outside the side hole pressure transmission connector in a sleeving mode, and the side hole pressure transmission connector is connected with the side through sleeve in a sleeving mode. The side through sleeve is fixed on the reamer body, the piston outer sleeve is fixed outside the side through sleeve, the piston push rod is embedded in the reamer body and abuts against the piston outer sleeve, a cutter body is arranged on the piston push rod, and a guide step allowing the cutter body to move outwards in the radial direction is arranged on the reamer body.

Description

[0001] This invention claims the priority of the patent application with the patent number 202410126981.8 and the invention title "While-drilling reamer and activation and closing method", which was filed on January 30, 2024. Technical Field

[0002] This invention relates to the field of oil and gas well drilling, and specifically to a while-drilling reamer that can be activated and closed multiple times, as well as an activation and closing method. Background Art

[0003] With the increase in complex drilling operations such as deep wells, slim holes, and casing sidetracking, in order to increase the clearance between the casing and the wellbore wall and improve the cementing quality of this type of well, downhole reaming operations become very important, especially for reaming operations in the lower slim hole sections of deep and ultra-deep wells.

[0004] Form a complete construction technology for while-drilling reamers, provide technical support for solving the drilling and completion problems in complex formations and complex wellbore structures, improve the cementing quality, and reduce the development cost; provide technical reserves for the development of new technologies such as casing drilling, small-clearance casing programs, and sidetracked wells.

[0005] Currently, through the downhole reaming technology using reamers, the wellbore in the pay zone can be enlarged, which not only improves the cementing quality in the pay zone, but also increases the exposed area of the reservoir and improves the oil well recovery rate. And it can make full use of the cutting characteristics of PDC composite inserts to achieve the operation goals of rapid reaming drilling and extending the tool service life. The diameter of the wellbore enlarged by this tool can reach more than 45 mm, and it can efficiently carry out reaming drilling. The cutter wings are reasonably toothed, the welding process is safe, and the hydraulic design achieves the purpose of effective cleaning and cooling.

[0006] In the prior art, there are various methods to enable the drill string assembly to pass through the cased wellbore and enlarge the wellbore at the lower end of the casing. Among them, one method is to use a reamer. The reamer basically has two working states. One is the closed state, which enables the cutter to pass through the existing cased wellbore. The other is the open state, where the cutters protrude from the body at the end. In this state, when the reamer rotates and descends in the borehole, the borehole diameter can be enlarged.

[0007] However, conventional roller cone reamers have potential accident hazards of roller cone falling into the well due to the limitation of roller cone bearing size, and it is difficult to solve the drilling and completion problems in complex formations and complex wellbore structures.

[0008] Therefore, in this field, there is a desire to provide a while-drilling reamer that can be activated and closed multiple times to solve the above technical problems. Summary of the Invention

[0009] The object of the present invention is to provide a reamer while drilling that can be activated and deactivated multiple times, which can perform multiple activation and deactivation actions downhole, thereby solving the problem that the conventional roller reamer has a problem of the roller falling into the well due to the limitation of the roller bearing size.

[0010] According to a first aspect of the present invention, there is provided a reamer while drilling that can be activated and deactivated multiple times, including a reamer body, which has a central flow passage formed therein to allow drilling fluid to pass through, and

[0011] an actuating mechanism, the actuating mechanism includes a side-hole pressure-transfer joint disposed in the central flow passage, a side-pass sleeve sleeved outside the hole pressure-transfer joint, and a piston outer sleeve fixed outside the side-pass sleeve, and

[0012] a piston push rod nested in the reamer body and abutting against the piston outer sleeve,

[0013] wherein, a cutter body is provided on the piston push rod, and a guiding step is provided on the reamer body to allow the cutter body to move radially outward,

[0014] The side-hole pressure-transfer joint is configured to be able to descend after changing the displacement of the drilling fluid and generating a pressure drop until it communicates with the side-pass sleeve to allow the drilling fluid to enter the piston outer sleeve, thereby pushing the piston push rod upward to cause the cutter body to open outward.

[0015] In one embodiment, the reamer while drilling further includes a housing disposed below the reamer body, a guide rail concentrically arranged in the housing and below the side-hole pressure-transfer joint, and a central tube disposed below the guide rail,

[0016] wherein, the reamer while drilling further includes a support sleeve sleeved outside the central tube and fixed to the housing by screws, and a lower spring is provided between the support sleeve and the central tube.

[0017] In one embodiment, a shear pin seat is provided below the central tube, and the central tube is fixed to the shear pin seat by a shear pin in the initial state.

[0018] In one embodiment, a pressure sleeve is provided below the shear pin seat,

[0019] The reamer while drilling further includes a first joint disposed below the housing, and a limiting chamber adapted to the pressure sleeve is formed in the first joint.

[0020] In one embodiment, a first through groove and a second through groove are arranged at intervals on the outer wall of the guide rail, and the reamer while drilling further includes a reversing pin disposed on the housing and used for engaging with the first through groove or the second through groove to judge the activation state.

[0021] In one embodiment, the cutter body is hinged to one end of the piston push rod away from the piston outer sleeve through a pin shaft.

[0022] In one embodiment, a spring mandrel is provided above the piston push rod.

[0023] The reamer while drilling further includes a second joint provided above the reamer body, a guide sleeve concentrically arranged in the second joint and connected to the spring mandrel, and an upper spring sleeved outside the guide sleeve and abutted against the spring mandrel.

[0024] In one embodiment, a sealing sleeve is provided at the joint of the reamer body and the piston push rod.

[0025] In one embodiment, a side nozzle which is inclinedly arranged and allows the drilling fluid to pass through is provided on the piston push rod, and the outlet direction of the side nozzle is aligned with the cutter body.

[0026] According to a second aspect of the present invention, an activation and closing method is provided, which uses the reamer while drilling as described above and includes the following steps:

[0027] S1. Lower the reamer while drilling to a specified depth.

[0028] S2. Generate a pressure drop by changing the displacement of the drilling fluid, thereby shearing the shear pin to cause the side-hole pressure transmission joint to move downward and compress the lower spring until the side-hole pressure transmission joint communicates with the side-through sleeve, and the drilling fluid enters the piston outer sleeve and then pushes the piston push rod upward to cause the cutter body to expand outward along the guiding step.

[0029] S3. After the pump is stopped, the side-hole pressure transmission joint resets under the action of the lower spring, and the piston push rod resets under the action of the upper spring and causes the cutter body to contract inward.

[0030] Compared with the prior art, the advantages of the present invention are as follows: BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be described in detail below with reference to the drawings. In the drawings:

[0032] Figure 1 Schematically shows the closed state of the reamer while drilling that can be activated and closed multiple times according to the present invention;

[0033] Figure 2 Schematically shows the activated state of the reamer while drilling that can be activated and closed multiple times according to the present invention.

[0034] In the drawings, like reference numerals are used for like components. The drawings are not drawn to scale. Detailed Description of the Invention

[0035] In order to make the technical solutions and advantages of the present invention clearer and more understandable, the exemplary embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than an exhaustive list of all embodiments. And without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0036] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0037] In the present invention, unless otherwise clearly defined and limited, terms such as "installed", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside two components.

[0038] For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] The present invention will be further described below with reference to the accompanying drawings.

[0040] As Figure 1 and 2 shown, according to the first aspect of the present invention, a reamer 100 that can be activated and deactivated multiple times mainly includes a reamer body 10 and an actuator. Preferably, a central flow channel allowing drilling fluid to pass through is formed inside the reamer body 10; the actuator includes a side-hole pressure transmission joint 21 located in the central flow channel, and a side-pass sleeve 22 fixed in the central flow channel and sleeved outside the side-hole pressure transmission joint 21.

[0041] In the present invention, side through-holes are provided on the side wall of the side-hole pressure transmission joint 21, and circular holes are provided on the side-pass sleeve 22. Therefore, when the side through-holes of the side-hole pressure transmission joint 21 are aligned with the circular holes of the side-pass sleeve 22, drilling fluid can enter the piston outer sleeve 32 (introduced below).

[0042] According to the present invention, as Figure 1As shown, the reamer 100 that can be activated and deactivated multiple times further includes a piston outer sleeve 32 fixedly installed outside the side through sleeve 22, and a piston push rod 23 nested inside the reamer body 10. Preferably, the piston push rod 23 axially abuts against the piston outer sleeve 32 in the initial state, so as to effectively limit the movement path of the piston push rod 23. Preferably, the piston outer sleeve 32 is threadedly connected to the side through sleeve 22.

[0043] In one embodiment, as Figure 1 and 2 shown, a cutter body 24 is provided on the piston push rod 23, and a guiding step 102 allowing the cutter body 24 to move radially outward is provided on the reamer body 10. Preferably, the cutter body 24 is hinged to one end of the piston push rod 23 far from the piston outer sleeve 32 through a pin shaft 241. Therefore, the cutter body 24 can extend outward under the guiding action of the guiding step 102 to help complete the subsequent reaming work.

[0044] In the present invention, when the reamer 100 that can be activated and deactivated multiple times reaches the specified reaming depth, the displacement of the drilling fluid is changed to generate a pressure drop, so as to cause the side hole pressure transmission joint 21 to move downward under the action of the pressure drop until the side through hole of the side hole pressure transmission joint 21 is aligned with the round hole of the side through sleeve 22. At this time, the drilling fluid will flow into the piston outer sleeve 32 through the side hole pressure transmission joint 21 and the side through sleeve 22 in sequence. Since then, the piston push rod 23 will move upward under the liquid column pressure formed by the drilling fluid, and at the same time, the cutter body 24 will also open outward along the guiding step 102, which is beneficial to the downhole reaming operation.

[0045] In the present invention, the piston push rod 23 and the cutter body 24 are configured into a reaming mechanism, and at least three sets of reaming mechanisms are arranged circumferentially along the reamer body 10 to further improve the downhole reaming operation ability of the reamer 100 that can be activated and deactivated multiple times. Preferably, an elastic retaining ring is provided outside the pin shaft 241, so as to limit the deflection angle of the cutter body 24 to ensure that the cutter body 24 can extend outward smoothly.

[0046] In one embodiment, as Figure 1 and 2 shown, the reamer 100 that can be activated and deactivated multiple times further includes a housing 31 fixedly installed at the bottom end of the reamer body 10, and a guide rail 41 and a central tube 42 arranged in sequence inside the housing 31. Preferably, the guide rail 41 and the central tube 42 are both concentrically arranged inside the housing 31, and the guide rail 41 is fixedly connected to the bottom of the side hole pressure transmission joint 21, and the central tube 42 is fixedly connected to the bottom of the guide rail 41. Therefore, the side hole pressure transmission joint 21, the guide rail 41 and the central tube 42 will move synchronously during the reaming operation.

[0047] In one embodiment of the present invention, as Figure 1 and2 As shown, the reamer 100 that can be activated and deactivated multiple times further includes a support sleeve 55 disposed in the annulus between the central tube 42 and the housing 31, and a lower spring 56 sleeved outside the central tube 42 and axially abutting against the support sleeve 55 and the guide rail 41 respectively. Preferably, the support sleeve 55 is fixedly installed on the inner wall of the housing 31 by screws 551; when the side-hole pressure transmission joint 21 descends, the lower spring 56 will be compressed, and after the pump is stopped, the side-hole pressure transmission joint 21 will also be smoothly reset under the elastic force of the lower spring 56 to achieve the function of activating or deactivating the reamer multiple times.

[0048] Preferably, as Figure 1 and 2 shown, a shear pin seat 43 is provided below the central tube 42, and the central tube 42 can be fixed to the shear pin seat 43 by a shear pin 431 in the initial state. Through this layout, the shear pin 431 can only be cut when the pressure drop is generated by changing the drilling fluid displacement to cause the side-hole pressure transmission joint 21 to descend, thereby effectively avoiding the situation of premature opening during the lowering process of the reamer 100 that can be activated and deactivated multiple times.

[0049] In one embodiment, as Figure 1 and 2 shown, a pressure sleeve 44 is provided below the shear pin seat 43, and the reamer 100 that can be activated and deactivated multiple times further includes a first joint 33 disposed below the housing 31. Preferably, a limiting chamber adapted to the pressure sleeve 44 is formed in the first joint 33.

[0050] According to the present invention, the reamer 100 that can be activated and deactivated multiple times further includes a commutation mechanism. As Figure 1 and 2 shown, the commutation mechanism includes a first through groove 61 and a second through groove 62 disposed on the outer wall of the guide rail 41. Preferably, the first through groove 61 and the second through groove 62 are arranged at intervals and are both on the same axis, so as to be more easily matched with the commutation pin 63 (introduced below) to improve the ability to judge the real-time state of the reamer 100.

[0051] In one embodiment, the reamer 100 that can be activated and deactivated multiple times further includes a commutation pin 63 fixedly installed on the inner wall of the housing 31. Preferably, when the guide rail 41 moves axially, the commutation pin 63 can selectively engage with the first through groove 61 or the second through groove 62, thereby helping to judge whether the reamer 100 is in the activated state or the deactivated state.

[0052] In the present invention, when the commutation pin 63 enters from the first through groove 61 into the second through groove 62, it is as Figure 2As shown, the hole opener 100 while drilling is in the activated state; when the reversing pin 63 enters the first through slot 61 from the second through slot 62, then Figure 1 As shown, the hole opener 100 while drilling is in the closed state.

[0053] Preferably, through the engagement relationship between the reversing pin 63 and the first through slot 61 or the second through slot 62, the hole opener 100 while drilling can be more easily and accurately switched between the activated state and the closed state.

[0054] In one embodiment, as Figure 1 and 2 shown, a spring mandrel 53 and a guide sleeve 52 are successively arranged above the piston push rod 23. Preferably, the piston push rod 23 is axially abutted against the spring mandrel 53, the guide sleeve 52 is arranged on the spring mandrel 53, and the spring mandrel 53 can form a sliding connection with the guide sleeve 52.

[0055] According to the present invention, as Figure 1 and 2 shown, the hole opener 100 while drilling that can be activated and closed multiple times further includes a second joint 51 arranged above the hole opener body 10. Preferably, the guide sleeve 52 is concentrically arranged in the second joint 51, and an upper spring 54 is further arranged in the annulus between the hole opener body 10 and the second joint 51.

[0056] In the present invention, when the drilling fluid flows into the piston outer sleeve 32, the piston push rod 23 will move upward under the liquid column pressure formed by the drilling fluid. At the same time, the spring mandrel 53 axially moves relative to the guide sleeve 52 to compress the upper spring 54. Since then, the cutter body 24 will also open outward along the guiding step 102. Preferably, after the pump is stopped, the spring mandrel 53 will also be reset smoothly under the elastic force of the upper spring 54, further prompting the cutter body 24 to reset, which is beneficial for the next stage of downhole operation.

[0057] In one embodiment, an annular cavity is formed between the hole opener body 10, the piston push rod 23 and the spring mandrel 53. Therefore, in the present invention, by filling a sealing sleeve 25 in the annular cavity, the sealing performance between the piston push rod and the hole opener body 10 during the hole opening operation can be ensured. Preferably, the sealing sleeve 25 is threadedly connected to the hole opener body 10.

[0058] In one embodiment of the present invention, as Figure 1 and 2 shown, an inclined side nozzle 231 is arranged on the piston push rod 23. Preferably, as Figure 2As shown, when the reamer 100 that can be activated and deactivated multiple times is in the activated state, the side nozzle 231 can communicate with the central flow channel in the reamer body 10, allowing the drilling fluid to spray out through the side nozzle 231. Preferably, the spraying direction of the side nozzle 231 is aligned with the cutter body 24 (i.e., the reaming operation location). In this way, the drilling ability of the cutter body 24 can be effectively improved, and further, the service life of the reamer 100 is extended.

[0059] Combined with Figures 1 - 2 to specifically introduce the working principle of the reamer 100 that can be activated and deactivated multiple times:

[0060] When the reamer 100 reaches the specified reaming depth, the displacement of the drilling fluid is changed to generate a pressure drop, thereby shearing the shear pin 431 and activating the reversing mechanism to prompt the reversing pin 63 to enter from the first through slot 61 into the second through slot 62.

[0061] At the same time, the side hole pressure transmission joint 21, the guide rail 41, and the central tube 42 move downward synchronously and compress the lower spring 56 until the pressure sleeve 44 abuts against the limiting chamber. At this time, the side hole of the side hole pressure transmission joint 21 is aligned with the round hole of the side through sleeve 22.

[0062] Then, the drilling fluid enters the piston outer sleeve 32 through the side hole of the side hole pressure transmission joint 21 and the round hole of the side through sleeve 22, and pushes the piston push rod 23 upward. Since then, the cutter body 24 will move radially outward under the action of the guiding step 102. At the same time, the piston push rod 23 and the spring core shaft 53 move upward synchronously to compress the upper spring 54, ensuring that the reamer 100 is in the activated state as Figure 2 shown.

[0063] In the present invention, as the grinding time changes, the outer diameter of the cutter body 24 gradually increases until it reaches the theoretical outer diameter until the step formation is completed.

[0064] Preferably, when the reaming operation is completed, the cutter body 24 can be retracted by stopping the pump. Specifically, after stopping the pump, the spring core shaft 53 and the piston push rod 23 move downward and reset under the action of the upper spring 54, and the cutter body 24 is also retracted synchronously. At the same time, the side hole pressure transmission joint 21, the guide rail 41, and the central tube 42 move upward and reset under the action of the lower spring 56. Since then, the reamer 100 will be in the closed state as Figure 1 shown. At this time, the reversing pin 63 has entered from the second through slot 62 into the first through slot 61.

[0065] Preferably, the above working process can be switched repeatedly, so that the reamer 100 can be more easily converted into the activation mode or the closed mode downhole, ensuring that the cutter body 24 can complete the extension or retraction actions more accurately according to the requirements of downhole operations and achieving the effect of continuous downhole operations.

[0066] It should be noted that when the reamer 100 is folded, each cutter body 24 is limited by the structure composed of the first spring 54, the side through sleeve 22, and the piston outer sleeve 32 and stored in the corresponding cutter groove. And when the reamer 100 expands, the lower part of the cutter body 24 is axially upwardly moved by the force, and at the same time extends radially outward from the reamer body 10, and since then the reamer 100 is activated.

[0067] According to the second aspect of the present invention, an activation and closing method is provided, which uses the reamer as described above and includes the following steps:

[0068] First, lower the reamer 100 that can be activated and closed multiple times to the designated depth;

[0069] Then, generate a pressure drop by changing the drilling fluid displacement, so as to cut the shear pin 431 to prompt the side hole pressure transmission joint 21 to move downward and compress the lower spring 56 until the side hole pressure transmission joint 21 communicates with the side through sleeve 22. At this time, the drilling fluid will enter the piston outer sleeve 32 and form a liquid column to push the piston push rod 23 upward, and the cutter body 24 will open outward along the guiding step 102, so that the reamer 100 that can be activated and closed multiple times enters the activation state;

[0070] Finally, after the pump is stopped, the side hole pressure transmission joint 21 is reset under the action of the lower spring 56, and the piston push rod 23 is reset under the action of the upper spring 54 and the cutter body 24 contracts inward, so that the reamer 100 that can be activated and closed multiple times enters the closed state.

[0071] Compared with the prior art, the advantages of the present invention are as follows:

[0072] First, the present invention can activate and close the reamer 100 multiple times downhole, thus solving the problem that the conventional roller reamer has the problem of roller falling into the well due to the limitation of the roller bearing size, and this device can also be used as a stabilizer for controlling the drill bit trajectory during the drilling process, so that it can more easily solve the drilling and completion problems in complex formations and complex wellbore structures.

[0073] Second, the present invention can more easily control the activation state and the closed state of the reamer 100 through the commutation mechanism, that is, through the clamping action of the commutation pin 63 with the first through groove 61 or the second through groove 62, ensuring that the cutter body 24 can complete the extension or retraction actions more accurately according to the requirements of downhole operations.

[0074] Thirdly, the present invention can increase the casing annulus clearance without changing the casing size to improve the cementing quality. In addition, by applying the reaming technology, the safe time for casing running in the gypsum salt layer creep formation is increased.

[0075] The above is only the preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art can easily make changes or variations within the disclosure scope of the present invention, and such changes or variations should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A reamer for use while drilling that can be activated and deactivated multiple times, comprising: A reamer body (10) having a central flow passage formed therein for allowing drilling fluid to pass through, and An actuator, the actuator including a side-hole pressure-transfer joint (21) disposed in the central flow passage, a side-pass sleeve (22) sleeved outside the hole pressure-transfer joint (21), and a piston outer sleeve (32) fixed outside the side-pass sleeve (22), and A piston push rod (23) nested inside the reamer body (10) and abutting against the piston outer sleeve (32), Wherein, a cutter body (24) is provided on the piston push rod (23), and a guiding step (102) allowing the cutter body (24) to move radially outward is provided on the reamer body (10), The side-hole pressure-transfer joint (21) is configured to be able to descend after changing the displacement of the drilling fluid and generating a pressure drop until it communicates with the side-pass sleeve (22) to allow the drilling fluid to enter the piston outer sleeve (32), thereby pushing the piston push rod (23) upward to cause the cutter body (24) to open outward.

2. The reamer while drilling that can be activated and deactivated multiple times according to claim 1, characterized in that, The reamer for use while drilling further includes a housing (31) disposed below the reamer body (10), a guide rail (41) concentrically arranged inside the housing (31) and below the side-hole pressure-transfer joint (21), and a central tube (42) disposed below the guide rail (41), Wherein, the reamer for use while drilling further includes a support sleeve (55) sleeved outside the central tube (42) and fixed to the housing (31) by screws (551), and a lower spring (56) is provided between the support sleeve (55) and the central tube (42).

3. The reamer while drilling that can be activated and deactivated multiple times according to claim 2, characterized in that, A shear pin seat (43) is provided below the central tube (42), and the central tube (42) is fixed to the shear pin seat (43) by a shear pin (431) in the initial state.

4. The reamer while drilling that can be activated and deactivated multiple times according to claim 3, characterized in that A pressure sleeve (44) is provided below the shear pin seat (43), The reamer for use while drilling further includes a first joint (33) disposed below the housing (31), and a limiting chamber adapted to the pressure sleeve (44) is formed inside the first joint (33).

5. The reamer while drilling that can be activated and deactivated multiple times according to claim 4, wherein First through slots (61) and second through slots (62) are arranged at intervals on the outer wall of the guide rail (41), and the reamer for use while drilling further includes a reversing pin (63) provided on the housing (31) and used for engaging with the first through slot (61) or the second through slot (62) to judge the activation state.

6. The reamer while drilling that can be activated and deactivated multiple times according to claim 1, wherein The cutter body (24) is hinged to one end of the piston push rod (23) far from the piston outer sleeve (32) by a pin shaft (241).

7. The reamer while drilling that can be activated and deactivated multiple times according to claim 2, characterized in that, A spring mandrel (53) is provided above the piston push rod (23), The reamer for use while drilling further includes a second joint (51) disposed above the reamer body (10), a guide sleeve (52) concentrically arranged inside the second joint (51) and connected to the spring mandrel (53), and an upper spring (54) sleeved outside the guide sleeve (52) and abutting against the spring mandrel (53).

8. The reamer while drilling that can be activated and deactivated multiple times according to claim 3, characterized in that, A sealing sleeve (25) is provided at the joint of the reamer body (10) and the piston push rod (23).

9. The reamer while drilling that can be activated and deactivated multiple times according to claim 1, characterized in that, A side nozzle (231) which is arranged obliquely and allows the drilling fluid to pass through is provided on the piston push rod (23), and the outlet direction of the side nozzle (231) is aligned with the cutter body (24).

10. An activation and closing method, which uses the reamer while drilling according to any one of claims 1 to 9, comprising the following steps: S1. Lower the reamer while drilling to a specified depth; S2. Generate a pressure drop by changing the displacement of the drilling fluid, so as to cut the shear pin (431) to cause the side-hole pressure transmission joint (21) to move downward and compress the lower spring (56) until the side-hole pressure transmission joint (21) communicates with the side-connection sleeve (22), and the drilling fluid enters the piston outer sleeve (32) and then pushes the piston push rod (23) upward to make the cutter body (24) expand outward along the guiding step (102); S3. After the pump is stopped, the side-hole pressure transmission joint (21) resets under the action of the lower spring (56), and the piston push rod (23) resets under the action of the upper spring (54) and makes the cutter body (24) contract inward.

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