Mechanical reducing drifting device and using method thereof

Abstract

The invention provides a mechanical variable-diameter drifting device and a using method thereof.The mechanical variable-diameter drifting device comprises a shell, a lower connector and a variable-diameter block, a connecting lock sleeve, a cam rotating shaft and a screw shaft which are sequentially connected from top to bottom are arranged in the shell, the connecting lock sleeve can move up and down in the axial direction, a plurality of grooves are evenly distributed in the circumferential direction of the cam rotating shaft, and the screw shaft is connected with the lower connector. The pin shafts correspond to the grooves in a one-to-one mode, the connecting lock sleeve is fixedly connected with the shell, and the screw shaft drives the cam rotating shaft to move in the circumferential direction when moving in the axial direction. The cam rotating device moves circumferentially through the axial movement of the screw shaft, so that the bulge of the cam is in contact with the pin shaft, the variable-diameter block is pushed by the pin shaft to extend out of the shell, and the variable diameter is realized. Due to the fact that the large ratchet between the connecting lock sleeve and the cam rotating shaft is in a locking state, it is guaranteed that rotation is not generated in the diameter changing process. State circulation of the outer diameter of the tool is achieved through two times of ball throwing in each period, repeated conversion of the outer diameter is achieved, and the reducing state of the tool is stably kept through a mechanical structure.

Description

Technical Field

[0001] The invention belongs to downhole tools for petroleum drilling, and in particular relates to a mechanical variable-diameter wellbore cleaner and a use method thereof. Background Art

[0002] In the drilling and completion of directional wells, horizontal wells and extended reach wells, well-drilling operations are required. Different well-drilling tool combinations need to be replaced according to different wellbore structures. When using rigid centralizers, multiple well-drilling operations are required, which greatly reduces the efficiency of the operation and construction and increases the drilling cost. Therefore, the use of downhole variable diameter tools has become an effective way to improve the efficiency of operations.

[0003] The announcement number of the National Intellectual Property Administration on September 4, 2018 is CN1067614708. The patent name is a variable diameter stabilizer, which includes a housing, a piston, a sliding sleeve, a conical sleeve arranged at the bottom of the piston, and a straightening column arranged on the housing. The conical sleeve and the straightening column cooperate to achieve diameter change. This variable diameter stabilizer can be controlled by the ground for the purpose of diameter change. The stabilizer is placed in an expanded state by dropping balls multiple times at the wellhead, so that the corresponding stabilizer can be opened without drilling to achieve the purpose of well clearance with different drilling tool combinations. When it is necessary to achieve double or triple well clearance, it is only necessary to pull the drill string to the casing foot, and by dropping balls, control the extension of the straightening column of the two-support (or three-support) well clearance variable diameter stabilizer, so that single, double, and three-support well clearance can be achieved.

[0004] However, the above-mentioned variable diameter stabilizer has the following shortcomings: 1. It does not have the function of clearing the well; 2. The stable variable diameter state usually requires keeping the mud pump in the open state; 3. The control method adopts electronic control, and the stability is not as good as the pure mechanical structure; 4. The ball-throwing variable diameter tool is mostly a one-time use variable diameter, and does not have the function of repeated ball-throwing variable diameter. Summary of the invention

[0005] The purpose of the present invention is to provide a mechanical variable diameter well dredge to overcome the above technical problems existing in the prior art.

[0006] Another object of the present invention is to provide a method for using a mechanical variable diameter well drilling device, which realizes outer diameter conversion by throwing the ball twice in each cycle, simplifies operation, has a simple structure, is easy to operate, and improves drilling efficiency.

[0007] To this end, the technical solution provided by the present invention is as follows:

[0008] A mechanical variable diameter well dredge comprises a shell, a lower joint and a variable diameter block, wherein the shell is connected to the lower joint, a ball receiving basket is arranged in the lower joint, a plurality of thrust lock blocks are evenly distributed in the outer circumference of the shell, a pressure cap and a variable diameter block reset spring are arranged in the thrust lock block, the pressure cap is connected to the variable diameter block reset spring and the pressure cap is close to the inside, the variable diameter block is arranged in the shell, the variable diameter block is multiple and both upper and lower ends thereof are connected to the pressure cap, the variable diameter block can move radially out of the shell, and a pin is connected to the inside of the variable diameter block;

[0009] The shell is provided with a connecting lock sleeve, a cam rotating shaft and a screw shaft which are connected in sequence from top to bottom. The connecting lock sleeve can move up and down along the axial direction. The cam rotating shaft is evenly distributed with a plurality of grooves in the circumferential direction. The pin shafts correspond to the grooves one by one. The connecting lock sleeve is fixedly connected to the shell. When the screw shaft moves axially, it drives the cam rotating shaft to move circumferentially.

[0010] The connecting lock sleeve is evenly distributed with a plurality of movement grooves in the circumferential direction, the movement grooves are arranged up and down and pass through up and down, the connecting lock sleeve is limited on the shell by a positioning pin, the connecting lock sleeve is provided with a lock sleeve pressure cap spring, the lock sleeve pressure cap spring is provided with a lock sleeve pressure cap, and the lock sleeve pressure cap is limited in the shell by a retaining spring.

[0011] A claw sleeve and a claw nut are arranged from top to bottom in the cam rotating shaft, and the claw sleeve and the claw nut are connected by a ratchet mechanism. The claw nut is spirally connected to the screw shaft, and a bearing and a claw sleeve reset spring are arranged on the top of the claw sleeve. A threaded pressure nut is arranged in the cam rotating shaft, and the bottom end of the claw nut is limited by the threaded pressure nut.

[0012] A head is provided at the lower part of the screw shaft, and a semicircular groove 1 is opened in the head. A return spring seat is provided under the screw shaft, and the return spring seat is fixed to the shell through a positioning pin. A return spring is installed on the return spring seat, and the return spring is sleeved on the screw shaft. A semicircular groove 2 is opened in the return spring seat.

[0013] The connecting lock sleeve and the cam rotating shaft are connected through a second ratchet mechanism. A ring groove is provided on the cam rotating shaft. The cam rotating shaft is limited on the housing through a positioning pin.

[0014] The claw sleeve is evenly distributed with a plurality of convex keys on the outer circumference, and the cam rotating shaft is provided with a plurality of key slots, the convex keys correspond to the key slots one by one, and the cam rotating shaft limits the claw sleeve through a key connection, and the claw sleeve can only move axially in the cam rotating shaft.

[0015] The screw shaft has a plurality of motion limiting grooves evenly distributed in the circumferential direction, and the screw shaft is limited on the housing by positioning pins.

[0016] A method for using a mechanical variable-diameter well cleaner, using the mechanical variable-diameter well cleaner, comprises the following steps:

[0017] Step 1) Throw a ball into the wellbore, and the screw shaft moves axially downward under the thrust of the throttling pressure difference to compress the return spring;

[0018] Step 2) The claw nut performs circumferential rotational motion under the action of the spiral connection. At this time, the claw nut and the claw sleeve are in a locked state. The claw nut drives the claw sleeve to perform synchronous circumferential rotational motion. The claw sleeve drives the cam rotating shaft to perform synchronous circumferential motion through the key connection;

[0019] Step 3) The cam rotating shaft rotates, and the pin shaft disengages from the groove of the cam rotating shaft, so that the protrusion of the cam contacts and pushes the pin shaft, and the pin shaft pushes the reducing block to make radial movement, and the reducing block pushes the pressing cap to compress the reducing block reset spring, and the reducing block extends out of the housing, connecting the locking sleeve and the large ratchet lock of the cam rotating shaft, so that the cam rotating shaft cannot rotate, and the tool is kept in the reduced diameter state;

[0020] Step 4) When the screw shaft moves to the bottom, the semicircular groove 1 in the screw shaft head is aligned with the semicircular groove 2 in the return spring seat to form a ball channel, and the ball falls into the ball receiving basket after passing through, and the throttling pressure difference thrust acting on the screw shaft disappears, and the screw shaft moves upward axially under the thrust of the return spring;

[0021] Step 5) The claw nut is subjected to the action of the spiral connection to perform reverse circumferential rotational motion, and the diameter change is completed to reach the maximum outer diameter state.

[0022] When it is necessary to reach the minimum outer diameter state, the ball is thrown again, and the screw shaft is thrust by the throttling pressure difference to make axial movement downward to compress the reset spring. At the same time, the cam rotating shaft rotates circumferentially, so that the cam on the cam rotating shaft turns from the convex position to the groove position, and the reset spring of the reducing block generates thrust on the pressing cap, and the pressing cap pushes the reducing block to make axial movement and retract to reach the minimum outer diameter state.

[0023] The beneficial effects of the present invention are:

[0024] The mechanical variable diameter well dredge provided by the present invention makes the cam rotating device move circumferentially through the axial movement of the screw shaft, so that the protrusion of the cam contacts the pin shaft, and the pin shaft pushes the variable diameter block out of the housing to achieve diameter change. Since the second ratchet mechanism (large ratchet tooth) connecting the locking sleeve and the cam rotating shaft is in a locked state, it is ensured that no rotation occurs during the diameter change process.

[0025] Compared with the existing variable diameter stabilizer, the present invention adds a well-clearing function, and realizes the state cycle of the tool outer diameter by throwing the ball twice in each cycle, realizes multiple repeated conversions of the outer diameter, and stably maintains the variable diameter state of the tool through a mechanical structure. There is no need to keep the mud pump turned on, which simplifies the operation, has a simple structure, is easy to operate, improves drilling timeliness, and saves production costs at the drilling site.

[0026] The present invention can control the outer diameter of the variable diameter wellbore by throwing a ball, so that the outer diameter of the wellbore can be changed by ground control and wellbores with different outer diameters can be used in different well sections, reducing the number of trips and drilling. Compared with the stabilizer that realizes variable diameter by ground electrical control, it has higher reliability. The device has a simple structure and is easy to operate, which can effectively improve the drilling time efficiency and the efficiency of the well team. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall structure of an implementation method of the present invention;

[0028] Figure 2 1. It is a schematic diagram of the structure of the connecting lock sleeve;

[0029] Figure 3 This is a schematic diagram of the structure of the cam rotating shaft

[0030] Figure 4 It is a schematic diagram of the structure of the claw nut;

[0031] Figure 5 It is a schematic diagram of the structure of the claw sleeve;

[0032] Figure 6 It is a schematic diagram of the structure of the screw shaft;

[0033] Figure 7 It is a structural schematic diagram of the screw shaft head;

[0034] Figure 8 It is a structural schematic diagram of the return spring seat;

[0035] Fig. 9 This is a schematic diagram when the diameter is not changed;

[0036] Fig.10 This is a schematic diagram after the diameter is reduced.

[0037] In the figure: 1. housing; 2. connecting lock sleeve; 3. cam rotating shaft; 4. cam; 5. annular groove; 6. claw sleeve; 7. claw nut; 8. screw shaft; 9. motion limit groove; 10. reset spring; 11. ball receiving basket; 12. retaining spring; 13. lock sleeve pressure cap; 14. lock sleeve pressure cap spring; 15. thrust lock block; 16. reducing block; 17. pin; 18. pressure cap; 19. reducing block reset spring; 20. claw sleeve reset spring; 21. bearing; 22. threaded pressure cap; 23. reset spring seat; 24. head; 25. lower joint; 26. motion groove; 27. large ratchet; 28. convex key; 29. ​​semicircular groove two; 30. inner spiral; 31. small ratchet; 32. outer spiral; 33. semicircular groove one. DETAILED DESCRIPTION

[0038] The following describes the implementation of the present invention through specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0039] The exemplary embodiments of the present invention are now described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0040] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0041] Example 1

[0042] This embodiment provides a mechanical variable diameter well dredge, such as Figure 1 As shown, it includes a shell 1, a lower joint 25 and a reducing block 16, the shell 1 and the lower joint 25 are connected, the lower joint 25 is provided with a ball receiving basket 11, the outer circumference of the shell 1 is evenly distributed with multiple groups of thrust lock blocks 15, the thrust lock blocks 15 are equipped with a pressure cap 18 and a reducing block reset spring 19, the pressure cap 18 and the reducing block reset spring 19 are connected and the pressure cap 18 is close to the inside, the reducing block 16 is arranged in the shell 1, the reducing block 16 is a plurality of pieces and the upper and lower ends are connected to the pressure cap 18, the reducing block 16 can move radially out of the shell 1, and the inner side of the reducing block 16 is connected with a pin 17;

[0043] The housing 1 is provided with a connecting lock sleeve 2, a cam rotating shaft 3 and a screw shaft 8 which are sequentially connected from top to bottom. The connecting lock sleeve 2 can move up and down along the axial direction. The cam rotating shaft 3 has a plurality of grooves evenly distributed circumferentially. The pin shafts correspond to the grooves one by one. The connecting lock sleeve 2 is fixedly connected to the housing 1. When the screw shaft 8 moves axially, it drives the cam rotating shaft 3 to move circumferentially.

[0044] The mechanical variable diameter well dredge provided by the present invention makes the cam 4 rotating device move circumferentially through the axial movement of the screw shaft 8, so that the protrusion of the cam 4 contacts the pin shaft, and the pin shaft pushes the variable diameter block 16 out of the housing 1 to achieve diameter change.

[0045] Example 2

[0046] On the basis of Example 1, this embodiment provides a mechanical variable diameter well dredge, wherein the connecting lock sleeve 2 is evenly distributed with a plurality of movement grooves 26 in the circumferential direction, the movement grooves 26 are arranged up and down and penetrate up and down, the connecting lock sleeve 2 is limited on the housing 1 by a positioning pin, the connecting lock sleeve 2 is provided with a lock sleeve pressure cap spring 14, the lock sleeve pressure cap spring 14 is provided with a lock sleeve pressure cap 13, and the lock sleeve pressure cap 13 is limited in the housing 1 by a retaining spring 12. Figure 1 shown.

[0047] In this embodiment, the connecting lock sleeve 2 has two vertically penetrating movement grooves 26 evenly distributed in the circumference, and is limited on the housing 1 by the positioning pins, so that the connecting lock sleeve 2 can only move axially in the housing 1. The function of the lock sleeve pressure cap spring 14 is to provide axial space for the connecting lock sleeve 2 and keep the connecting lock sleeve 2 in contact with the cam rotating shaft 3.

[0048] Example 3

[0049] On the basis of Example 1, this embodiment provides a mechanical variable diameter well cleaning device, wherein a claw sleeve 6 and a claw nut 7 are provided in the cam rotating shaft 3 from top to bottom, and the claw sleeve 6 and the claw nut 7 are connected by a ratchet mechanism, and the claw nut 7 is spirally connected to the screw shaft 8. A bearing 21 and a claw sleeve reset spring 20 are provided at the top of the claw sleeve 6, and a threaded pressure nut 22 is provided in the cam rotating shaft 3, and the bottom end of the claw nut 7 is limited by the threaded pressure nut 22.

[0050] like Figure 4 , Figure 5 As shown, the ratchet mechanism 1 is composed of a small ratchet wheel arranged on a claw sleeve 6 and a claw nut 7. Figure 4 As shown, the claw nut 7 is provided with an internal spiral 30, as shown in FIG. Figure 6 As shown, the screw shaft 8 is provided with an external spiral 32, and the two are connected by a thread. The function of the claw sleeve reset spring 20 is to provide axial movement space for the claw nut 7 when the screw shaft 8 drives the claw nut 7 to rotate in the non-locking direction of the ratchet mechanism 1, while maintaining the contact between the claw nut 7 and the claw sleeve 6 to maintain the integrity of the ratchet mechanism 1.

[0051] Example 4

[0052] On the basis of Example 1, this embodiment provides a mechanical variable diameter well clearing device, wherein a head 24 is provided at the lower part of the screw shaft 8, a semicircular groove 33 is opened in the head 24, a return spring seat 23 is provided under the screw shaft 8, the return spring seat 23 is fixed to the housing 1 by a positioning pin, a return spring 10 is installed on the return spring seat 23, the return spring 10 is sleeved on the screw shaft 8, and a semicircular groove 29 is opened in the return spring seat 23.

[0053] Head 24 Figure 7As shown, the return spring seat 23 is as shown in Figure 8 As shown, the screw shaft 8 moves downward, and when the head 24 is inserted into the return spring seat 23, the semicircular groove 1 33 is aligned with the semicircular groove 29, and the ball can pass through.

[0054] Example 5

[0055] Based on Example 1, this example provides a mechanical variable diameter well-draining device, wherein the connecting lock sleeve 2 and the cam rotating shaft 3 are connected via a second ratchet mechanism, an annular groove 5 is provided on the cam rotating shaft 3, and the cam rotating shaft 3 is limited on the housing 1 via a positioning pin.

[0056] like Figure 2 and Figure 3 As shown, the ratchet mechanism 2 is composed of a large ratchet wheel arranged on the connecting locking sleeve 2 and the cam rotating shaft 3. During the circumferential movement of the cam rotating shaft 3, the ratchet mechanism 2 is in a locked state, ensuring that no rotation occurs during the diameter change process.

[0057] Example 6

[0058] Based on Example 1, this example provides a mechanical variable diameter well opening device, such as Figure 5 As shown, a plurality of convex keys 28 are evenly distributed on the outer circumference of the claw sleeve 6, and a plurality of key slots are arranged in the cam rotating shaft 3, and the convex keys 28 correspond to the key slots one by one. The cam rotating shaft 3 limits the claw sleeve 6 by a key connection, and the claw sleeve 6 can only move axially in the cam rotating shaft 3.

[0059] Example 7

[0060] On the basis of Example 1, this embodiment provides a mechanical variable-diameter well-draining device, wherein the screw shaft 8 has a plurality of motion limiting grooves 9 evenly distributed in the circumferential direction, and the screw shaft 8 is limited on the housing 1 by positioning pins.

[0061] like Figure 6 As shown, the movement limiting groove 9 allows the screw shaft 8 to move only axially in the housing 1 .

[0062] Example 8

[0063] Based on Example 1, this example provides a mechanical variable diameter well opening device, such as Figure 1As shown, it includes a housing 1, and three threaded thrust lock blocks 15 are evenly distributed on the outer circumference of the housing 1, which play a role in limiting the reducer block 16. The thrust lock block 15 is equipped with a pressure cap 18 and a reducer block reset spring 19; the housing 1 is provided with a cam rotating shaft 3 and a reducer block 16, and the reducer block 16 is sleeved on the pin 17. The upper end of the cam rotating shaft 3 is connected to the lock sleeve 2, and the cam rotating shaft 3 is provided with a claw nut 7 and a claw sleeve 6. The claw nut 7 and the screw shaft 8 are connected in a spiral pair, and a reset spring 10 is provided between the screw shaft 8 and the reset spring seat 23. The housing 1 is connected to a lower joint 25, and a ball receiving basket 11 is provided in the lower joint 25.

[0064] The connecting lock sleeve 2 has two vertically penetrating motion grooves 26 evenly distributed in the circumference, which are limited on the housing 1 by the positioning pins, and the connecting lock sleeve 2 can only move axially in the housing 1. The cam rotating shaft 3 has an annular groove 5, which is limited on the housing 1 by the positioning pins, and the cam rotating shaft 3 can only rotate circumferentially in the housing 1. The screw shaft 8 has three incompletely penetrating motion limiting grooves 9 evenly distributed in the circumference, which are limited on the housing 1 by the positioning pins, and the screw shaft 8 can only move axially in the housing 1. The claw sleeve 6 has six convex keys 28 evenly distributed in the circumference, and the inner hole of the cam rotating shaft 3 is correspondingly provided with six key slots. The cam rotating shaft 3 limits the claw sleeve 6 through the key connection, and the claw sleeve 6 can only move axially in the cam rotating shaft 3.

[0065] After the ball is thrown, when the screw shaft 8 is subjected to the throttling thrust and moves axially downward, it drives the cam rotating shaft 3 to rotate circumferentially to the maximum outer diameter of the cam rotating shaft 3 and the cam 4, pushes the pin 17, and then pushes the diameter reducing block 16 to achieve the purpose of diameter reduction. The large ratchet 27 is locked so that the cam rotating shaft 3 cannot rotate, and the tool is kept in the diameter reducing state. When the screw shaft 8 moves to the lowermost end, the ball passes through the aligned semicircular groove 1 33 and the semicircular groove 2 29 and falls into the ball receiving basket 11. The screw shaft 8 is restored to its original position by the thrust of the reset spring 10, and the remaining structure is locked by the small ratchet 31 and does not move. After the ball is thrown again, the above action is repeated, and the diameter reducing block 16 is retracted. When the ball reaches the head 24 of the screw shaft 8 and falls into the ball receiving basket 11, pressure changes will occur. The wellhead operator can judge the diameter reducing state of the tool by the change of pump pressure.

[0066] Working process and principle of the present invention:

[0067] When the assembly is completed, the tool is in the initial state, such as Fig. 9 As shown. At this time, the screw shaft 8 is kept at the highest position by the thrust of the return spring 10. The pin is in the groove of the cam 4 of the cam rotating shaft 3, and the pressure cap 18 is pressed against the reducer 16 by the thrust of the reducer return spring 19, so that the tool maintains the minimum outer diameter state.

[0068] When the ball is thrown for the first time, it seats on the head 24 of the screw shaft 8 after being thrown in place. The screw shaft 8 is thrusted downward by the throttling pressure difference to compress the reset spring 10, and the claw nut 7 is subjected to the spiral connection to make a circumferential rotation. At this time, the small ratchet teeth 31 of the claw nut 7 and the claw sleeve 6 are in a locked state, and the claw nut 7 drives the claw sleeve 6 to make a synchronous circumferential rotation. The claw sleeve 6 drives the cam rotating shaft 3 to make a synchronous circumferential movement through the key connection. The cam 4 on the cam rotating shaft 3 rotates from the groove to the convex part, pushing the pin shaft to make a radial movement, and the pin shaft pushes the reducing block 16 to make a radial movement and extend out, and the pressure cap 18 compresses the reducing block reset spring 19, and the large ratchet 27 between the locking sleeve 2 and the cam rotating shaft 3 is in a locked state, keeping the cam rotating shaft 3 from rotating. When the screw shaft 8 moves to the bottom under the limit, the semicircular groove of the screw shaft 8 head 24 is aligned with the semicircular groove 29 of the reset spring seat 23, and the ball falls into the ball receiving basket 11 through the aligned groove. At this time, the throttling pressure difference thrust acting on the screw shaft 8 disappears, and the screw shaft 8 is pushed upward by the reset spring 10. The claw nut 7 is reversed by the spiral connection. The small ratchet 31 of the claw nut 7 and the claw sleeve 6 is in the working state, and the claw nut 7 does not drive the other parts to move. At this time, the tool diameter is successfully reduced and reaches the maximum outer diameter state, such as Fig.10 shown.

[0069] When the ball is thrown for the second time, the parts repeat the above movement, the cam 4 on the cam rotating shaft 3 rotates from the convex position to the concave position, the return spring 19 of the reducing block generates a thrust on the pressure cap 18, and the pressure cap 18 pushes the reducing block 16 to retract in the axial direction, and the large ratchet 27 connecting the locking sleeve 2 and the cam rotating shaft 3 is in a locked state, keeping the cam rotating shaft 3 from rotating. At this time, the tool changes diameter successfully again and reaches the minimum outer diameter state, such as Fig. 9 shown.

[0070] The mechanical variable diameter well drilling device performs two working cycles by throwing balls in each cycle to achieve outer diameter conversion, which simplifies the operation, has a simple structure, is easy to operate, and improves drilling efficiency.

[0071] Example 9

[0072] This embodiment provides a method for using a mechanical variable-diameter well cleaner, using the mechanical variable-diameter well cleaner, including the following steps:

[0073] Step 1) Throw a ball into the wellbore, and the screw shaft 8 moves axially downward under the thrust of the throttling pressure difference to compress the return spring 10;

[0074] Step 2) The claw nut 7 performs circumferential rotational motion under the effect of the spiral connection. At this time, the claw nut 7 and the claw sleeve 6 are in a locked state. The claw nut 7 drives the claw sleeve 6 to perform synchronous circumferential rotational motion. The claw sleeve 6 drives the cam rotating shaft 3 to perform synchronous circumferential motion through the key connection;

[0075] Step 3) The cam rotating shaft 3 rotates, the pin shaft disengages from the groove of the cam rotating shaft 3, so that the protrusion of the cam 4 contacts and pushes the pin shaft, and the pin shaft pushes the reducing block 16 to make radial movement, and the reducing block 16 pushes the pressing cap 18 to compress the reducing block reset spring 19, and the reducing block 16 extends out of the housing 1, and the large ratchet 27 connecting the locking sleeve 2 and the cam rotating shaft 3 is locked, so that the cam rotating shaft 3 cannot rotate, and the tool is kept in the reduced diameter state;

[0076] Step 4) When the screw shaft 8 moves to the bottom, the semicircular groove 1 33 in the head 24 of the screw shaft 8 is aligned with the semicircular groove 29 in the return spring seat 23 to form a ball channel, and the ball falls into the ball receiving basket 11 after passing through, and the throttling pressure difference thrust acting on the screw shaft 8 disappears, and the screw shaft 8 is pushed by the return spring 10 to make an upward axial movement;

[0077] Step 5) The claw nut 7 is subjected to the action of the spiral connection to perform reverse circumferential rotational motion, and the diameter change is completed to reach the maximum outer diameter state.

[0078] When it is necessary to reach the minimum outer diameter state, the ball is thrown again, and the screw shaft 8 is thrusted by the throttling pressure difference to make axial movement downward to compress the reset spring 10, and at the same time, the cam rotating shaft 3 rotates circumferentially, so that the cam 4 on the cam rotating shaft 3 turns from the convex position to the groove position, and the reducing block reset spring 19 generates thrust on the pressing cap 18, and the pressing cap 18 pushes the reducing block 16 to make axial movement and retract, reaching the minimum outer diameter state.

[0079] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. A mechanical variable diameter well dredge, characterized in that: It includes a shell, a lower joint and a reducing block, the shell is connected to the lower joint, a ball receiving basket is arranged in the lower joint, a plurality of thrust lock blocks are evenly distributed on the outer circumference of the shell, a pressure cap and a reducing block reset spring are installed in the thrust lock block, the pressure cap and the reducing block reset spring are connected and the pressure cap is close to the inside, the reducing block is arranged in the shell, the reducing block is multiple and the upper and lower ends are connected to the pressure cap, the reducing block can move radially out of the shell, and a pin is connected to the inside of the reducing block; The shell is provided with a connecting lock sleeve, a cam rotating shaft and a screw shaft which are connected in sequence from top to bottom. The connecting lock sleeve can move up and down along the axial direction. The cam rotating shaft is evenly distributed with a plurality of grooves in the circumferential direction. The pin shafts correspond to the grooves one by one. The connecting lock sleeve is fixedly connected to the shell. When the screw shaft moves axially, it drives the cam rotating shaft to move circumferentially.

2. A mechanical variable diameter well dredge according to claim 1, characterized in that: The connecting lock sleeve is evenly distributed with a plurality of movement grooves in the circumferential direction, the movement grooves are arranged up and down and pass through up and down, the connecting lock sleeve is limited on the shell by a positioning pin, the connecting lock sleeve is provided with a lock sleeve pressure cap spring, the lock sleeve pressure cap spring is provided with a lock sleeve pressure cap, and the lock sleeve pressure cap is limited in the shell by a retaining spring.

3. The mechanical variable diameter well dredge according to claim 1, characterized in that: A claw sleeve and a claw nut are arranged from top to bottom in the cam rotating shaft, and the claw sleeve and the claw nut are connected by a ratchet mechanism. The claw nut is spirally connected to the screw shaft, and a bearing and a claw sleeve reset spring are arranged on the top of the claw sleeve. A threaded pressure nut is arranged in the cam rotating shaft, and the bottom end of the claw nut is limited by the threaded pressure nut.

4. The mechanical variable diameter well dredge according to claim 1, characterized in that: A head is provided at the lower part of the screw shaft, and a semicircular groove 1 is opened in the head. A return spring seat is provided under the screw shaft, and the return spring seat is fixed to the shell through a positioning pin. A return spring is installed on the return spring seat, and the return spring is sleeved on the screw shaft. A semicircular groove 2 is opened in the return spring seat.

5. The mechanical variable diameter well dredge according to claim 1, characterized in that: The connecting lock sleeve and the cam rotating shaft are connected through a second ratchet mechanism. A ring groove is provided on the cam rotating shaft. The cam rotating shaft is limited on the housing through a positioning pin.

6. The mechanical variable diameter well dredge according to claim 3, characterized in that: The claw sleeve is evenly distributed with a plurality of convex keys on the outer circumference, and the cam rotating shaft is provided with a plurality of key slots, the convex keys correspond to the key slots one by one, and the cam rotating shaft limits the claw sleeve through a key connection, and the claw sleeve can only move axially in the cam rotating shaft.

7. The mechanical variable diameter well dredge according to claim 4, characterized in that: The screw shaft has a plurality of motion limiting grooves evenly distributed in the circumferential direction, and the screw shaft is limited on the housing by positioning pins.

8. A method for using a mechanical variable-diameter well dredge according to claim 1, using the mechanical variable-diameter well dredge according to claim 3, characterized in that: The following steps are involved: Step 1) Throw a ball into the wellbore, and the screw shaft moves axially downward under the thrust of the throttling pressure difference to compress the return spring; Step 2) The claw nut performs circumferential rotational motion under the action of the spiral connection. At this time, the claw nut and the claw sleeve are in a locked state. The claw nut drives the claw sleeve to perform synchronous circumferential rotational motion. The claw sleeve drives the cam rotating shaft to perform synchronous circumferential motion through the key connection; Step 3) The cam rotating shaft rotates, and the pin shaft disengages from the groove of the cam rotating shaft, so that the protrusion of the cam contacts and pushes the pin shaft, and the pin shaft pushes the reducing block to make radial movement, and the reducing block pushes the pressing cap to compress the reducing block reset spring, and the reducing block extends out of the housing, connecting the locking sleeve and the large ratchet lock of the cam rotating shaft, so that the cam rotating shaft cannot rotate, and the tool is kept in the reduced diameter state; Step 4) When the screw shaft moves to the bottom, the semicircular groove 1 in the screw shaft head is aligned with the semicircular groove 2 in the return spring seat to form a ball channel, and the ball falls into the ball receiving basket after passing through, and the throttling pressure difference thrust acting on the screw shaft disappears, and the screw shaft moves upward axially under the thrust of the return spring; Step 5) The claw nut is subjected to the action of the spiral connection to perform reverse circumferential rotational motion, and the diameter change is completed to reach the maximum outer diameter state.

9. The method for using the mechanical variable-diameter well dredge according to claim 8, characterized in that: When it is necessary to reach the minimum outer diameter state, the ball is thrown again, and the screw shaft is thrust by the throttling pressure difference to make axial movement downward to compress the reset spring. At the same time, the cam rotating shaft rotates circumferentially, so that the cam on the cam rotating shaft turns from the convex position to the groove position, and the reset spring of the reducing block generates thrust on the pressing cap, and the pressing cap pushes the reducing block to make axial movement and retract to reach the minimum outer diameter state.

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