A variable-diameter bi-directional underreaming device while drilling and its usage method

Abstract

The present invention provides a variable-diameter bi-directional reaming device while drilling and a usage method thereof, which includes an upper sub, an upper body, a lower body and a lower sub connected in sequence. A plurality of cutter holes are provided on the circumferential side of the upper body. A helical cutter wing that slides radially is arranged in the cutter hole. One end of the helical cutter wing is provided with a cutter-out mechanism, and the other end is provided with a reset cutter-retracting mechanism. A cutter-wing control mechanism is arranged on one side of the cutter-out mechanism. The helical cutter wing is pushed out and retracted by the cutter-out mechanism and the reset cutter-retracting mechanism. Among them, the cutter-out mechanism is controlled by the cutter-wing control mechanism. By adjusting the displacement of the mud pump, the mandrel in the cutter-wing control mechanism is driven to rotate and adjusted, so that the mandrel hole communicates with the side hole of the intermediate connecting cylinder, and high-pressure mud enters it, thereby controlling the cutter-out mechanism to push the helical cutter wing out. The helical cutter wing can perform bi-directional operations, reaming the front and the rear by lowering or raising the well. By controlling the displacement of the mud pump to open the helical cutter wing, misoperation can be prevented, and the reaming operation is more efficient and reliable.

Description

Technical Field

[0001] The present invention relates to the field of oil drilling, and particularly to a variable-diameter bidirectional hole reamer device while drilling and a using method thereof. Background Art

[0002] With the deepening of oil and gas exploitation, the drilling depth is gradually increasing, and the problems encountered in drilling are becoming more and more complex, facing more and more complex wellbore structures and formation structures. During construction in some areas, situations such as wellbore diameter reduction, irregular wellbore, or narrow annulus space for casing running may be encountered. Conventional methods can only perform long-term reaming operations during drilling or tripping to achieve the purpose of removing diameter reduction and trimming the wellbore wall, which will consume a large amount of manpower, material resources, and time.

[0003] In the prior art, technicians have manufactured a tool for enlarging the wellbore - downhole hole reamer, also known as reaming bit. Common hole reamers can generally be divided into fixed-wing hole reamers and movable-wing hole reamers. Movable-wing hole reamers are divided into arm-type hole reamers and block-type hole reamers according to different reaming bodies. The reaming body of the arm-type hole reamer is usually fixed to the body by a pin shaft and can rotate around a fixed axis within a certain angle range. After the reaming body is opened, it is like two outstretched arms; the reaming body of the block-type hole reamer is wedge-shaped and cannot rotate, and can protrude or retract into the body under the action of hydraulic or mechanical thrust. Due to the use of vulnerable parts such as springs, the opening and closing actions of the arm-type hole reamer are easily affected by the performance of drilling fluid, especially the solid content; the machining accuracy requirements for the cutter wings of the block-type hole reamer are relatively high. In addition, due to the limitation of the body wall thickness on the block size, the radial size of the reaming body is small, so the pilot hole can only be enlarged by about 25%.

[0004] In addition, after the fixed-wing hole reamer and most movable-wing hole reamers complete the hole reaming operation, the drill string must be pulled out of the well, and only after replacing the conventional drill string can drilling continue. The operation instructions of the hole reamers in the prior art are single. After entering the well, it can only perform hole reaming operations and cannot perform selective hole reaming operations. For example, in the section where the wellbore wall is stable and no hole reaming is required, it will also perform hole reaming operations, which increases the equipment burden; for example, when the cutter body is worn, only the drill string can be pulled out of the well to replace the hole reamer, and it is impossible to temporarily suspend hole reaming and wait until the drill bit is worn and then pull out the drill string to replace them together, and so on.

[0005] In summary, the self-structure of the existing hole reamers is still not perfect enough to fully meet the requirements of drilling engineering, and it is still necessary to improve the design according to actual needs and explore a more reasonable structural form. Summary of the Invention

[0006] The main purpose of the present invention is to provide a variable-diameter bidirectional hole reamer device while drilling and a using method thereof to solve the problems in the above background art.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is as follows: It includes an upper joint, an upper body, a lower body, and a lower joint connected in sequence. A plurality of knife outlet holes are provided on the periphery of the upper body. A spiral knife wing that slides radially is provided in the knife outlet hole. One end of the spiral knife wing is provided with a knife outlet mechanism, and the other end is provided with a reset knife retraction mechanism. A knife wing control mechanism is provided on one side of the knife outlet mechanism.

[0008] In a preferred embodiment, the spring seat plug in the reset knife retraction mechanism is fixed in the upper body. An upper spring seat and an upper guide shaft are provided outside the spring seat plug. A first spring is provided between the upper spring seat and the upper guide shaft. An upper push plate is provided at the end of the upper guide shaft, and the upper push plate abuts against the top of the spiral knife wing.

[0009] In a preferred embodiment, the upper spring seat is abutted and fixed on the spring seat plug through an open retaining ring. The outside of the upper guide shaft abuts against the inner wall of the upper body and slides in a sealed manner, and the inside of the upper guide shaft abuts against the outer wall of the spring seat plug and slides in a sealed manner;

[0010] One end of the first spring abuts against the upper spring seat, and the other end abuts against the upper guide shaft. The upper guide shaft is driven by the compression elastic force of the first spring to drive the upper push plate to push the spiral knife wing to move.

[0011] In a preferred embodiment, the lower sleeve in the knife outlet mechanism is fixed in the upper body. An intermediate connecting cylinder is fixed on one side of the lower sleeve. A sliding lower guide shaft is provided on one side of the intermediate connecting cylinder. A lower push plate is fixed at the end of the lower guide shaft, and the lower push plate abuts against the bottom of the spiral knife wing.

[0012] In a preferred embodiment, the outside of the lower guide shaft abuts against the inner wall of the upper body and slides in a sealed manner, and the inside of the lower guide shaft abuts against the outer wall of the spring seat plug and slides in a sealed manner;

[0013] The outside of the upper end of the intermediate connecting cylinder abuts against the inner wall of the upper body for sealing, the inside of the upper end abuts against the end of the spring seat plug for sealing, and the lower end abuts against the lower sleeve for sealing.

[0014] In a preferred embodiment, a plurality of upper holes of the intermediate connecting cylinder are provided on the periphery of the end of the intermediate connecting cylinder. A side hole of the intermediate connecting cylinder is provided on one side of the intermediate connecting cylinder. The cavity formed between the lower guide shaft and the intermediate connecting cylinder is communicated with the cavity formed between the intermediate connecting cylinder and the lower sleeve through the upper holes of the intermediate connecting cylinder;

[0015] The side hole of the intermediate connecting cylinder is communicated with the inner cavity of the drilling pipeline. High-pressure mud enters the above cavity through the side hole of the intermediate connecting cylinder, thereby pushing the lower guide shaft to drive the lower push plate to push the spiral knife wing to move.

[0016] In a preferred embodiment, the mandrel in the knife wing control mechanism abuts against and slides in the lower body. A lower plug is provided outside the mandrel, and the lower plug is fixed on the lower joint. A second spring is provided between the lower plug and the mandrel. A plurality of mandrel holes are provided on the periphery of the end of the mandrel, and the mandrel holes are communicated with the side hole of the intermediate connecting cylinder;

[0017] One end of the second spring abuts against the lower plug, and the other end abuts against the mandrel.

[0018] In a preferred embodiment, a limit pin is fixedly provided on one side of the lower body, a track groove is provided on the outer side of the middle part of the mandrel, and the limit pin abuts in the track groove;

[0019] Under the pushing action of the mud pressure and the elastic force of the second spring at the end of the mandrel, the limit pin abuts against the track groove and moves, adjusting and positioning the rotation of the mandrel so that the mandrel hole communicates with the side hole of the middle connecting cylinder.

[0020] In a preferred embodiment, a plurality of inclined sliders are provided on both sides of the matrix in the spiral cutter blade, a plurality of inclined sliding grooves are provided on both sides of the cutter outlet hole, and the sliders abut and slide in the sliding grooves. When the sliders slide to the top of the sliding grooves, the matrix is clamped;

[0021] The end of the matrix is provided with a spiral cutter blade, the middle part of the cutter blade is provided with a gauge protection tooth, and a plurality of cutting teeth are provided on both sides of the cutter blade;

[0022] The cutting teeth on both sides of the cutter blade are arranged oppositely.

[0023] The method is as follows: S1. The initial state of the spiral cutter blade is the retracted cutter position. When drilling to the section where the hole needs to be enlarged, the mud pump is shut down. At this time, the limit pin is at the C1 position in the track groove;

[0024] S2. Open the mud pump and gradually increase the displacement to a small displacement value so that the limit pin is at the C2 position in the track groove, then shut down the mud pump. The limit pin is at the C3 position in the track groove. At this time, open the mud pump to the normal displacement, and the limit pin is at the C4 position in the track groove. At this time, the mandrel hole communicates with the side hole of the middle connecting cylinder;

[0025] S3. High-pressure mud can enter the cavity from the mandrel hole and the side hole of the middle connecting cylinder, thereby pushing the lower guide shaft and the lower push plate so that the spiral cutter blade extends out of the outlet hole and starts the hole enlargement operation;

[0026] S4. After the operation is completed, shut down the mud pump, the mud in the cavity flows out, the mandrel moves upward under the pushing action of the second spring, the limit pin is at the C3' position in the track groove, and the spiral cutter blade moves downward under the pushing action of the first spring and retracts into the cutter outlet hole; [[ID=3l]]

[0027] S5. Open the mud pump to the small displacement value, the limit pin is at the C5 position in the track groove, then shut down the mud pump, and the limit pin resets to the C1' position in the track groove. The tool enters the standby state, and repeating the above steps can perform the hole enlargement operation again.

[0028] The present invention provides a variable-diameter bi-directional reaming device while drilling and a usage method. By arranging a cutter outlet hole on the outer side of the upper body, the spiral cutter blade moves in the cutter outlet hole, and the spiral cutter blade is pushed to extend and retract through the cutter outlet mechanism and the reset cutter retraction mechanism. Among them, the cutter outlet mechanism is controlled by the cutter blade control mechanism. When reaming operation is required, the displacement of the mud pump can be adjusted to drive the rotation of the mandrel in the cutter blade control mechanism for adjustment, so that the mandrel hole communicates with the side hole of the intermediate connecting cylinder, and high-pressure mud enters it, thereby controlling the cutter outlet mechanism to push the spiral cutter blade to extend. The spiral cutter blade can perform bi-directional operations, reaming the front and the rear by lowering or raising the well. By controlling the displacement of the mud pump to open the spiral cutter blade, misoperation can be prevented, and the reaming operation is more efficient and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described below in conjunction with the drawings and embodiments:

[0030] Figure 1 is the front view of the overall structure of the present invention;

[0031] Figure 2 is the A-A cross-sectional view of the present invention;

[0032] Figure 3 is the partial enlarged view a of the present invention;

[0033] Figure 4 is the C-C cross-sectional view of the present invention;

[0034] Figure 5 is the axonometric view of the spiral cutter blade of the present invention;

[0035] Figure 6 is the top view of the spiral cutter blade of the present invention;

[0036] Figure 7 is the axonometric view of the mandrel of the present invention;

[0037] Figure 8 is the moving path diagram of the normal drilling limit pin in the track groove of the present invention;

[0038] Figure 9 is the moving path diagram of the reaming operation limit pin in the track groove of the present invention;

[0039] Figure 10 is the multi-angle view of the retracted spiral cutter blade of the present invention;

[0040] Figure 11 is the multi-angle view of the extended spiral cutter blade of the present invention;

[0041] In the figure: upper sub 1; upper body 2; spring seat plug 3; snap ring 4; upper spring seat 5; upper guide shaft 6; upper push plate 7; spiral cutter blade 8; matrix 801; cutter blade 802; cutting tooth 803; gauge protection tooth 804; lower push plate 9; lower guide shaft 10; intermediate connecting cylinder 11; lower sleeve 12; mandrel 13; limit pin 14; lower body 15; lower plug 16; lower sub 17; first spring 18; second spring 19; mandrel hole 20; side hole of intermediate connecting cylinder 21; upper hole of intermediate connecting cylinder 22; track groove 23. Detailed implementation mode

[0042] Embodiment 1

[0043] As Figures 1 to 11 shown, a variable-diameter bi-directional reaming device while drilling and its using method include an upper sub 1, an upper body 2, a lower body 15 and a lower sub 17 which are connected in sequence. A plurality of cutter holes are provided on the circumferential side of the upper body 2, and spiral cutter blades 8 that slide radially are arranged in the cutter holes. One end of the spiral cutter blade 8 is provided with a cutter-out mechanism, the other end is provided with a reset cutter-retracting mechanism, and a cutter blade control mechanism is arranged on one side of the cutter-out mechanism. With such a structure, the cutter-out mechanism can push the spiral cutter blade 8 to move from bottom to top so that the spiral cutter blade 8 extends, the reset cutter-retracting mechanism can push the spiral cutter blade 8 to move from top to bottom so that the spiral cutter blade 8 retracts, and the cutter blade control mechanism is activated by the displacement of the mud pump, thereby controlling the cutter-out mechanism to push the spiral cutter blade 8. The operation is simple and convenient, and the reaming operation is more efficient.

[0044] In a preferred solution, the spring seat plug 3 in the reset cutter-retracting mechanism is fixed in the upper body 2. An upper spring seat 5 and an upper guide shaft 6 are arranged outside the spring seat plug 3. A first spring 18 is arranged between the upper spring seat 5 and the upper guide shaft 6. An upper push plate 7 is arranged at the end of the upper guide shaft 6, and the upper push plate 7 abuts against the top of the spiral cutter blade 8. The upper spring seat 5 abuts against and is fixed on the spring seat plug 3 through the snap ring 4. The outer side of the upper guide shaft 6 abuts against and slides sealingly on the inner wall of the upper body 2, and the inner side of the upper guide shaft 6 abuts against and slides sealingly on the outer wall of the spring seat plug 3; one end of the first spring 18 abuts against the upper spring seat 5, and the other end abuts against the upper guide shaft 6. The upper guide shaft 6 is pushed by the compression elastic force of the first spring 18 to drive the upper push plate 7 to push the spiral cutter blade 8 to move. With such a structure, when the spiral cutter blade 8 is in the extended state, the first spring 18 is in a compressed state. When it is necessary to retract the spiral cutter blade 8, the extended pushing pressure is released, so that the spiral cutter blade 8 can be pushed by the resilience of the first spring 18 acting on the upper push plate 7. The sealing sliding avoids foreign objects from entering and affecting the drive.

[0045] In a preferred embodiment, the lower sleeve 12 in the tool exit mechanism is fixed within the upper body 2. An intermediate connecting cylinder 11 is fixedly provided on one side of the lower sleeve 12. A sliding lower guide shaft 10 is provided on one side of the intermediate connecting cylinder 11. A lower push plate 9 is fixedly provided at the end of the lower guide shaft 10, and the lower push plate 9 abuts against the bottom of the spiral cutter blade 8. The outer side of the lower guide shaft 10 abuts against the inner wall of the upper body 2 and slides in a sealed manner, and the inner side of the lower guide shaft 10 abuts against the outer wall of the spring seat plug 3 and slides in a sealed manner; the outer side of the upper end of the intermediate connecting cylinder 11 abuts against the inner wall of the upper body 2 in a sealed manner, the inner side of the upper end abuts against the end of the spring seat plug 3 in a sealed manner, and the lower end abuts against the lower sleeve 12 in a sealed manner. A plurality of upper holes 22 of the intermediate connecting cylinder are provided on the circumferential side of the end of the intermediate connecting cylinder 11. An intermediate connecting cylinder side hole 21 is provided on one side of the intermediate connecting cylinder 11. The cavity formed between the lower guide shaft 10 and the intermediate connecting cylinder 11 communicates with the cavity formed between the intermediate connecting cylinder 11 and the lower sleeve 12 through the upper holes 22 of the intermediate connecting cylinder; the intermediate connecting cylinder side hole 21 communicates with the inner cavity of the drilling pipeline, and high-pressure mud enters the above-mentioned cavity through the intermediate connecting cylinder side hole 21, thereby pushing the lower guide shaft 10 to drive the lower push plate 9 to push the spiral cutter blade 8 to move. With this structure, high-pressure mud enters the cavity through the intermediate connecting cylinder side hole 21, thereby pushing the lower guide shaft 10 to move from bottom to top, driving the lower push plate 9 and the spiral cutter blade 8 to move, so that the spiral cutter blade 8 extends out.

[0046] In a preferred embodiment, the mandrel 13 in the cutter blade control mechanism abuts against the inside of the lower body 15 and slides. A lower plug 16 is provided on the outer side of the mandrel 13. The lower plug 16 is fixed to the lower sub 17. A second spring 19 is provided between the lower plug 16 and the mandrel 13. A plurality of mandrel holes 20 are provided on the circumferential side of the end of the mandrel 13, and the mandrel holes 20 communicate with the intermediate connecting cylinder side hole 21; one end of the second spring 19 abuts against the inside of the lower plug 16, and the other end abuts against the mandrel 13. With this structure, the end of the mandrel 13 abuts against the inner wall of the intermediate connecting cylinder 11, and the mud pressure can act on the end face of the mandrel 13, thereby pushing the mandrel 13 to move from top to bottom and compressing the second spring 19. After the mud pressure disappears, the resilience of the second spring 19 can push the mandrel 13 to move from bottom to top, so that under the action of the mud pressure, the mandrel 13 rotates by a certain angle, so that the mandrel holes 20 communicate with the intermediate connecting cylinder side hole 21, so that high-pressure mud can enter the cavity and push the spiral cutter blade 8 to extend out.

[0047] In a preferred embodiment, a limit pin 14 is fixedly provided on one side of the lower body 15, a track groove 23 is provided on the outer side of the middle part of the mandrel 13, and the limit pin 14 abuts against the track groove 23; under the pushing action of the mud pressure on the end of the mandrel 13 and the pushing action of the elastic force of the second spring 19, the limit pin 14 abuts against the track groove 23 and moves, so as to rotate and adjust the position of the mandrel 13, so that the mandrel hole 20 communicates with the side hole 21 of the middle connecting cylinder. With this structure, the mandrel 13 is pushed to move from top to bottom by the mud pressure, and the second spring 19 pushes the mandrel 13 to move from bottom to top, so that the limit pin 14 abuts against the track groove 23 and moves. The position of the limit pin 14 in the track groove 23 can make the mandrel hole 20 communicate with the side hole 21 of the middle connecting cylinder, and the spiral cutter blade 8 can be extended.

[0048] In a preferred embodiment, a plurality of inclined sliders are provided on both sides of the base body 801 in the spiral cutter blade 8, a plurality of inclined chutes are provided on both sides of the cutter outlet hole, and the sliders abut against the chutes and slide. When the sliders slide to the top of the chutes, the base body 801 is clamped; a spiral cutter blade 802 is provided at the end of the base body 801, a diameter retaining tooth 804 is provided in the middle of the cutter blade 802, and a plurality of cutting teeth 803 are provided on both sides of the cutter blade 802; the cutting teeth 803 on both sides of the cutter blade 802 are arranged in opposite directions. With this structure, the chute is arranged from the inside to the outside of the cutter outlet hole, and the outside of the chute is blocked. When the slider moves from the inside to the outside of the chute, when the lower push plate 9 or the upper push plate 7 pushes the base body 801 to move up and down, the spiral cutter blade 8 can move away from or close to the axis. The cutting teeth 803 on both sides of the cutter blade 802 are arranged in a conical shape, decreasing from the middle to both sides, so that both ends of the spiral cutter blade 8 can perform reaming operations, and the diameter retaining tooth 804 can ensure the final reaming size.

[0049] Embodiment 2

[0050] As Figures 8 to 9, Further described in conjunction with Embodiment 1, the initial state of the spiral cutter blade 8 is the cutter retracted position. When drilling to the section where hole enlargement is required, the mud pump is shut down. At this time, the limit pin 14 is at the C1 position of the track groove 23; the mud pump is turned on and the displacement is gradually increased to a small displacement value so that the limit pin 14 is at the C2 position of the track groove 23, and then the mud pump is shut down. The limit pin 14 is at the C3 position of the track groove 23. At this time, the mud pump is turned on to the normal displacement, and the limit pin 14 is at the C4 position of the track groove 23. At this time, the core shaft hole 20 communicates with the side hole 21 of the intermediate connecting cylinder; high-pressure mud can enter the cavity from the core shaft hole 20 and the side hole 21 of the intermediate connecting cylinder, thereby pushing the lower guide shaft 10 and the lower push plate 9, so that the spiral cutter blade 8 extends out of the outlet hole and starts the hole enlargement operation; after the operation is completed, the mud pump is shut down, and the mud in the cavity flows out. The core shaft 13 moves upward under the pushing action of the second spring 19. The limit pin 14 is at the C3' position of the track groove 23. The spiral cutter blade 8 moves downward under the pushing action of the first spring 18 and retracts into the cutter outlet hole; the mud pump is turned on to a small displacement value, the limit pin 14 is at the C5 position of the track groove 23, and then the mud pump is shut down. The limit pin 14 resets to the C1' position of the track groove 23, and the tool enters the standby state. Repeating the above steps can perform the hole enlargement operation again.

[0051] The above embodiments are only the preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. The protection scope of the present invention should be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A variable-diameter bi-directional reaming device while drilling, characterized in that: It includes an upper joint (1), an upper body (2), a lower body (15), and a lower joint (17) connected in sequence. A plurality of knife - out holes are provided on the circumferential side of the upper body (2). A helical blade (8) that slides radially is provided in the knife - out hole. One end of the helical blade (8) is provided with a knife - out mechanism, and the other end is provided with a reset and knife - retracting mechanism. A blade control mechanism is provided on one side of the knife - out mechanism; The spring seat plug (3) in the reset and knife - retracting mechanism is fixed in the upper body (2). An upper spring seat (5) and an upper guide shaft (6) are provided outside the spring seat plug (3). A first spring (18) is provided between the upper spring seat (5) and the upper guide shaft (6). An upper push plate (7) is provided at the end of the upper guide shaft (6), and the upper push plate (7) abuts against the top of the helical blade (8); The upper spring seat (5) abuts and is fixed on the spring seat plug (3) through a snap - ring (4). The outer side of the upper guide shaft (6) abuts and slides sealingly on the inner wall of the upper body (2), and the inner side of the upper guide shaft (6) abuts and slides sealingly on the outer wall of the spring seat plug (3); One end of the first spring (18) abuts against the upper spring seat (5), and the other end abuts against the upper guide shaft (6). By the compressive elastic force of the first spring (18), the upper guide shaft (6) is pushed to drive the upper push plate (7) to push the helical blade (8) to move; The lower sleeve (12) in the knife - out mechanism is fixed in the upper body (2). An intermediate connecting cylinder (11) is fixedly provided on one side of the lower sleeve (12). A sliding lower guide shaft (10) is provided on one side of the intermediate connecting cylinder (11). A lower push plate (9) is fixedly provided at the end of the lower guide shaft (10), and the lower push plate (9) abuts against the bottom of the helical blade (8); The core shaft (13) in the blade control mechanism abuts and slides in the lower body (15). A lower plug (16) is provided outside the core shaft (13). The lower plug (16) is fixed on the lower joint (17). A second spring (19) is provided between the lower plug (16) and the core shaft (13). A plurality of core - shaft holes (20) are provided on the circumferential side of the end of the core shaft (13), and the core - shaft holes (20) communicate with the side holes (21) of the intermediate connecting cylinder; One end of the second spring (19) abuts inside the lower plug (16), and the other end abuts against the core shaft (13); A plurality of inclined sliders are provided on both sides of the base body (801) in the helical blade (8). A plurality of inclined chutes are provided on both sides of the knife - out hole. The sliders abut and slide in the chutes. When the sliders slide to the top of the chutes, the base body (801) is clamped; A helical blade (802) is provided at the end of the base body (801). A diameter - retaining tooth (804) is provided in the middle of the blade (802). A plurality of cutting teeth (803) are provided on both sides of the blade (802); The cutting teeth (803) on both sides of the blade (802) are arranged oppositely.

2. The variable-diameter bi-directional reaming device while drilling according to claim 1, wherein: The outer side of the lower guide shaft (10) abuts and slides sealingly on the inner wall of the upper body (2), and the inner side of the lower guide shaft (10) abuts and slides sealingly on the outer wall of the spring seat plug (3); The outer side of the upper end of the intermediate connecting cylinder (11) abuts and seals on the inner wall of the upper body (2), the inner side of the upper end abuts and seals on the end of the spring seat plug (3), and the lower end abuts and seals on the lower sleeve (12).

3. The variable-diameter bi-directional reaming device while drilling according to claim 2, characterized in that: A plurality of upper holes (22) are provided on the circumferential side of the end of the intermediate connecting cylinder (11). A side hole (21) of the intermediate connecting cylinder is provided on one side of the intermediate connecting cylinder (11). The cavity formed between the lower guide shaft (10) and the intermediate connecting cylinder (11) communicates with the cavity formed between the intermediate connecting cylinder (11) and the lower sleeve (12) through the upper holes (22) of the intermediate connecting cylinder; The side hole (21) of the intermediate connecting cylinder communicates with the inner cavity of the drilling pipeline. High-pressure mud enters the above-mentioned cavity through the side hole (21) of the intermediate connecting cylinder, thereby pushing the lower guide shaft (10) to drive the lower push plate (9) to push the spiral cutter blade (8) to move.

4. The variable-diameter bi-directional reaming device while drilling according to claim 1, wherein: A limit pin (14) is fixedly arranged on one side of the lower body (15). A track groove (23) is provided on the outer side of the middle part of the core shaft (13). The limit pin (14) abuts in the track groove (23); Under the pushing action of the mud pressure at the end of the core shaft (13) and the pushing action of the elastic force of the second spring (19), the limit pin (14) abuts and moves in the track groove (23) to rotationally adjust and position the core shaft (13) so that the core shaft hole (20) communicates with the side hole (21) of the intermediate connecting cylinder.

5. The method for using a variable-diameter while-drilling two-way reaming device according to claim 4, the method is as follows: S1. The initial state of the spiral cutter blade (8) is the cutter-retracted position. When drilling to the well section that needs to be reamed, the mud pump is shut down. At this time, the limit pin (14) is at the C1 position of the track groove (23); S2. Open the mud pump and gradually increase the displacement to a small displacement value so that the limit pin (14) is at the C2 position of the track groove (23), then shut down the mud pump. The limit pin (14) is at the C3 position of the track groove (23). At this time, open the mud pump to the normal displacement. The limit pin (14) is at the C4 position of the track groove (23). At this time, the core shaft hole (20) communicates with the side hole (21) of the intermediate connecting cylinder; S3. High-pressure mud can enter the cavity from the core shaft hole (20) and the side hole (21) of the intermediate connecting cylinder, thereby pushing the lower guide shaft (10) and the lower push plate (9) to make the spiral cutter blade (8) extend out of the outlet hole and start the reaming operation. The well can be reamed forward when going down the well and reamed backward when pulling the well out; S4. After the operation is completed, shut down the mud pump. The mud in the cavity flows out. The core shaft (13) moves upward under the pushing action of the second spring (19). The limit pin (14) is at the C3' position of the track groove (23). The spiral cutter blade (8) moves downward under the pushing action of the first spring (18) and retracts into the cutter outlet hole; S5. Open the mud pump to a small displacement value. The limit pin (14) is at the C5 position of the track groove (23), then shut down the mud pump. The limit pin (14) resets to the C1' position of the track groove (23). The tool enters the standby state. Repeating the above steps can perform the reaming operation again.

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