Stable soluble bridge plug for oil and gas well

Abstract

The invention relates to the technical field of oil and gas well bridge plugs, and discloses a stable soluble bridge plug for an oil and gas well, which comprises a hollow mandrel, a pressure cylinder is arranged in the hollow mandrel, the outer surface of the top of the pressure cylinder is fixedly communicated with an air bag pipe, and a first piston disc is movably arranged in the pressure cylinder; the outer surface of the bottom of the first piston disc is fixedly connected with a first piston rod, the outer surfaces of the four connecting shafts are fixedly sleeved with gears, the outer surfaces of the peripheries of square rods are connected with a plurality of teeth arranged in a linear array, and the other end of a movable rod is fixedly connected with a supporting plate. A negative pressure device generates negative pressure through an air bag pipe to drive a first piston disc and a square rod, so that teeth drive a gear to rotate, a fixed rod, a movable rod and a supporting plate are stored to be parallel to a hollow mandrel, and therefore after the bridge plug is conveyed to a designated position, the auxiliary device is conveniently retracted, and the follow-up construction quality is prevented from being affected.

Description

Technical Field

[0001] The invention relates to the technical field of bridge plugs for oil and gas wells, in particular to a stable soluble bridge plug for oil and gas wells. Background Art

[0002] Oil and gas well engineering belongs to the first-level discipline of petroleum and natural gas engineering. Oil and gas wells are indispensable information and material channels for human exploration and development of underground oil and natural gas resources. Oil and gas well engineering is a capital and technology intensive project implemented around the construction, measurement and protection of oil and gas wells. It mainly includes oil and gas exploration and development drilling and completion engineering, oil and gas well measurement and testing engineering, and oil and gas well protection and repair engineering. Soluble bridge plugs are needed during oil and gas well operations to temporarily block the downhole annulus and wellbore. After blocking, the upper production layer of the bridge plug can be repaired. After the construction is completed, the bridge plug can be naturally dissolved and returned within a certain period of time.

[0003] The existing patent (publication number: CN219864941U) discloses a soluble bridge plug for sealing oil and gas wells, including a joint, a slip body is fixedly connected to the bottom of the joint, a cone is movably sleeved at the bottom of the slip body, a sealing assembly is movably sleeved at the top of the outer side of the cone, a bottom fixing piece is fixedly connected to the bottom of the cone, a roller groove is opened at the other end of the movable plate, a No. 2 cylindrical block is fixedly connected to the inner side of the roller groove, a movable roller is movably sleeved on the outer side of the No. 2 cylindrical block, a No. 2 telescopic rod is movably sleeved on the inner side of the No. 2 cylindrical tube, a No. 2 fixed block is fixedly connected to the bottom of the movable plate, a No. 2 fixed rod is fixedly connected to the inner side of the No. 2 fixed block, and the outer side of the No. 2 fixed rod is movably sleeved with the other end of the No. 2 telescopic rod. The movable roller can make the bridge plug in a centered position to avoid offset and jamming during the process of being sent into the drilling well, so that the process of sending the bridge plug is smoother.

[0004] When the above patented technology is in use, rolling friction occurs between the movable roller and the inner wall of the pipe, and the friction force is small. The movable rollers on all sides can keep the bridge plug in a centered position, avoiding deviation and jamming during the process of being sent into the drilling well, making the process of sending the bridge plug smoother. Although it can ensure the stable transportation of the bridge plug, in actual use, after the bridge plug is transported to the designated position, it is difficult to retract the movable roller, resulting in the subsequent dissolution process. The movable roller and its related structures cannot be dissolved and will remain in the oil and gas well, resulting in a certain impact on the construction quality. Therefore, a stable soluble bridge plug for oil and gas wells is proposed. Summary of the invention

[0005] In view of the deficiencies of the prior art, the present invention provides a stable soluble bridge plug for oil and gas wells to solve the problems mentioned in the above background technology.

[0006] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: A stable soluble bridge plug for oil and gas wells, comprising a hollow core shaft, a pressure cylinder is arranged inside the hollow core shaft, an air bag tube is fixedly connected to the top outer surface of the pressure cylinder, a first piston disc is movably arranged inside the pressure cylinder, a first piston rod is fixedly connected to the bottom outer surface of the first piston disc, a square rod is fixedly connected to the bottom outer surface of the first piston rod, a sleeve is fixedly connected to the bottom outer surface of the pressure cylinder, the first piston rod movably penetrates the outer surface of the sleeve, four rectangular blocks are fixedly connected inside the sleeve, connecting shafts are rotatably connected between the opposite outer surfaces of the four rectangular blocks, gears are fixedly sleeved on the outer surfaces of the four connecting shafts, a plurality of teeth arranged in a linear array are connected to the outer surfaces of the square rod, the teeth are movably meshed with the outer surfaces of four gears respectively, the outer surfaces of the four gears are fixedly connected to a fixed rod, a movable rod is movably inserted inside the fixed rod, the other end of the movable rod is fixedly connected to a support plate, and a plurality of balls are arranged on the other end of the support plate.

[0007] As a further explanation of the present invention, a winding wheel is fixedly provided on the outer surface of the connecting shaft on the left side, a pull rope is wound around the outer surface of the winding wheel, the outer surface of the pressure cylinder is fixedly connected to a pressure relief pipe, the interior of the pressure relief pipe is movably connected to a piston column, and the side of the piston column located outside the pressure relief pipe is fixedly connected to a fixed block, the pull rope movably passes through the outer surface of the sleeve and the other end of the pull rope is fixedly connected to the fixed block.

[0008] As a further explanation of the present invention, the left and right outer surfaces of the pressure cylinder are fixedly connected with connecting tubes, a second piston disk is movably arranged inside the connecting tube, a second piston rod is fixedly connected to the outer surface of the second piston disk, and one end of the second piston rod away from the second piston disk is fixedly connected to a limiting block, and two limiting holes are provided on the inner wall of the hollow core shaft, and the two limiting holes correspond to the two limiting blocks respectively.

[0009] As a further explanation of the present invention, a rubber plug is provided at the middle end of the outer surface of the hollow core shaft, and cones are provided on the outer surfaces of both sides of the hollow core shaft located at the rubber plug, and slips are provided on the outside of the two cones, and the other parts of the two slips are respectively provided at the two ends of the hollow core shaft.

[0010] As a further explanation of the present invention, a plurality of receiving grooves are provided inside the conical body, a second spring is fixedly connected inside each of the plurality of receiving grooves, a friction column is fixedly connected to the other end of the second spring, and an anti-slip protrusion is provided on the outer surface of the friction column.

[0011] As a further illustration of the present invention, a third spring is fixedly connected to the inner wall of the fixed column, and the other end of the third spring is fixedly connected to the movable column.

[0012] As a further explanation of the present invention, the outer surface of the pressure cylinder is fixedly connected to a connecting plate, the outer surface of the connecting plate is rotatably connected to a support shaft, the outer surface of the support shaft is fixedly sleeved with a guide wheel, and the pull rope is laid on the outer surface of the guide wheel.

[0013] As a further explanation of the present invention, a conical cylinder is fixedly connected to the inside of the pressure relief pipe, a circular hole is opened at one end of the conical cylinder facing the piston column, a conical block is movably connected to the inside of the circular hole, a first spring is fixedly connected between the inner wall of the conical cylinder away from the piston column and the conical block, and a through hole is opened on the side of the conical cylinder away from the conical block.

[0014] As a further illustration of the present invention, when the fixed rod and the movable rod are stored to be parallel to the hollow core shaft, the piston column just detaches from the inner wall of the pressure relief pipe.

[0015] As a further illustration of the present invention, the bottom ends of the hollow core shaft and the sleeve are both provided with through grooves for the fixed rod and the movable rod to move.

[0016] Compared with the prior art, the present invention has the following beneficial effects: In a stable soluble bridge plug for oil and gas wells provided by the present invention, negative pressure is generated by a negative pressure device through an airbag tube, driving a first piston disk, a first piston rod and a square rod, so that the teeth drive the gears to rotate, so that the fixed rod, the movable rod and the support plate are stored in a state parallel to the hollow core shaft, thereby facilitating the retraction of the auxiliary device after the bridge plug is transported to a specified position, thereby avoiding affecting the subsequent construction quality.

[0017] In a stable soluble bridge plug for oil and gas wells provided by the present invention, when the support plate is retracted by rotating the gear, the connecting shaft drives the winding wheel to reel in the pull rope. When the support plate is completely retracted, the pull rope causes the piston column to disengage from the pressure relief pipe, thereby allowing the negative pressure device to suck air out of the pressure relief pipe, thereby preventing the negative pressure from continuing to be generated when the support plate is retracted, causing the teeth of the square rod to continue to mesh with the gear and unable to rise, thereby affecting the service life of the square rod and the gear.

[0018] In a stable soluble bridge plug for oil and gas wells provided by the present invention, when pressure is applied in the pressure cylinder, when the first piston disc moves to the bottom of the connecting pipe, the second piston disc is squeezed under the action of pressure, so that the second piston rod drives the limit block to be inserted into the limit hole, thereby limiting the pressure cylinder inside the hollow core shaft. When negative pressure occurs, the second piston disc is driven to cooperate with the second piston rod to make the limit block disengage from the limit hole, thereby releasing the limit on the pressure cylinder and the center hole core shaft.

[0019] In a stable soluble bridge plug for oil and gas wells provided by the present invention, when the sealing tool clamps two slips toward the middle to cause the rubber plug to expand, the friction column fits against the inner wall of the wellbore, and the friction between the friction column and the inner wall of the wellbore is increased by the elastic force of the second spring and the anti-slip protrusions on the surface of the friction column, thereby ensuring that the bridge plug will not deviate. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a front view structural schematic diagram of the present invention; Figure 2 It is a bottom view structural schematic diagram of the present invention; Figure 3 It is a partial front view cross-sectional structure schematic diagram of the present invention; Figure 4 For the present invention Figure 3 The enlarged structural diagram at A in the middle; Figure 5 This is a schematic diagram of the structure of the present invention when the support plate is retracted; Figure 6 It is a schematic diagram of the internal structure of the fixed rod and the movable rod of the present invention; Figure 7 For the present invention Figure 3 The enlarged structural diagram at B in the middle; Figure 8 This is a schematic diagram of the internal structure of the pressure relief pipe of the present invention; Fig. 9 For the present invention Figure 3 Enlarged structural diagram at point C in the middle.

[0021] In the figure: 1. hollow core shaft; 2. pressure cylinder; 3. airbag tube; 4. first piston disk; 5. first piston rod; 6. square rod; 7. sleeve; 8. rectangular block; 9. connecting shaft; 10. gear; 11. fixed rod; 12. movable rod; 13. support plate; 14. ball; 15. reel; 16. pull rope; 17. pressure relief pipe; 18. piston column; 19. conical cylinder; 20. conical block; 21. first spring; 22. through hole; 23. connecting pipe; 24. second piston rod; 25. limit block; 26. limit hole; 27. conical body; 28. rubber plug; 29. ​​slip; 30. second spring; 31. friction column. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0023] Example 1: Please refer to Figure 1-Figure 9 The present invention provides a technical solution: a stable soluble bridge plug for oil and gas wells, comprising a hollow core shaft 1, a pressure cylinder 2 is arranged inside the hollow core shaft 1, the top outer surface of the pressure cylinder 2 is fixedly connected with an air bag tube 3, a first piston disc 4 is movably arranged inside the pressure cylinder 2, a first piston rod 5 is fixedly connected to the bottom outer surface of the first piston disc 4, a square rod 6 is fixedly connected to the bottom outer surface of the first piston rod 5, a sleeve 7 is fixedly connected to the bottom outer surface of the pressure cylinder 2, the first piston rod 5 movably passes through the outer surface of the sleeve 7, four rectangular blocks 8 are fixedly connected inside the sleeve 7, connecting shafts 9 are rotatably connected between the opposite outer surfaces of the four rectangular blocks 8, gears 10 are fixedly sleeved on the outer surfaces of the four connecting shafts 9, a plurality of teeth arranged in a linear array are connected to the outer surfaces of the square rod 6, and the teeth on the four sides are respectively connected to the outer surfaces of the four gears 10. The surfaces are movably meshed, and the outer surfaces of the four gears 10 are fixedly connected with a fixed rod 11, and a movable rod 12 is movably inserted inside the fixed rod 11. The other end of the movable rod 12 is fixedly connected with a support plate 13, and the other end of the support plate 13 is provided with a plurality of balls 14. Specifically, it is connected with the airbag tube 3 through an external negative pressure device, and air is sucked into the airbag tube 3 through the negative pressure device, so that the internal pressure of the pressure cylinder 2 becomes smaller, thereby driving the first piston disk 4 upward, and the first piston disk 4 drives the first piston rod 5 upward, so that the square rod 6 moves upward, so that the teeth drive the gear 10 to rotate, so that the fixed rod 11 and the movable rod 12 drive the support plate 13 to rotate, so that the support plate 13 is retracted to a state parallel to the central core axis, and then the pressure cylinder 2 and the sleeve 7 are taken out together, so that the auxiliary device for conveying the bridge plug can be taken out to avoid affecting the quality of subsequent construction.

[0024] In this embodiment, a third spring is fixedly connected to the inner wall of the fixed column, and the other end of the third spring is fixedly connected to the movable column. Specifically, the elastic force of the third spring enables the ball 14 to cling to the inner wall of the wellbore.

[0025] In this embodiment, the bottom ends of the hollow core shaft 1 and the sleeve 7 are both provided with through grooves for the fixed rod 11 and the movable rod 12 to move. Specifically, the through grooves provide space for the movement of the fixed rod 11 and the movable rod 12.

[0026] In the specific implementation process, when the bridge plug is sent into the oil and gas well, rolling friction occurs between the ball 14 and the inner wall of the pipeline, and the friction force is small, so as to avoid the bridge plug from being offset and stuck in the process of being sent into the oil and gas well. When the bridge plug is transported to a suitable position, it will be connected to the airbag tube 3 through an external negative pressure device, and air will be sucked into the airbag tube 3 through the negative pressure device, so that the pressure inside the pressure cylinder 2 becomes smaller, thereby driving the first piston disk 4 upward, and the first piston disk 4 drives the first piston rod 5 upward, so that the square rod 6 moves upward, so that the teeth drive the gear 10 to rotate, so that the fixed rod 11 and the movable rod 12 drive the support plate 13 to rotate, so that the support plate 13 is retracted to a state parallel to the central core axis, and then the pressure cylinder 2 and the sleeve 7 are taken out together, so that the auxiliary device for transporting the bridge plug can be taken out to avoid affecting the quality of subsequent construction.

[0027] Example 2: Please refer to Figure 1-Figure 9 The present invention provides a technical solution: a winding wheel 15 is fixedly sleeved on the outer surface of the left connecting shaft 9, a pull rope 16 is wound around the outer surface of the winding wheel 15, a pressure relief pipe 17 is fixedly connected to the outer surface of the pressure-applying cylinder 2, a piston column 18 is movably connected to the inside of the pressure relief pipe 17, a fixed block is fixedly connected to the piston column 18 on one side outside the pressure relief pipe 17, the pull rope 16 movably passes through the outer surface of the sleeve 7 and the other end of the pull rope 16 is fixedly connected to the fixed block. Specifically, when the support plate 13 is retracted, the gear 10 drives the connecting shaft 9 to rotate, and the connecting shaft 9 drives the winding wheel 15 to rotate The pull rope 16 is moved to reel in the pull rope 16, and the pull rope 16 drives the piston column 18 to move to the outside of the pressure relief tube 17. When the fixed rod 11 and the movable rod 12 drive the support plate 13 to be stored to a state parallel to the hollow core shaft 1, the piston column 18 is detached from the inside of the pressure relief tube 17. At this time, when the negative pressure device generates negative pressure through the airbag tube 3, the air is discharged through the piston column 18, so as to avoid that after the support plate 13 is retracted, the continuous negative pressure continues to drive the first piston disk 4 to move upward, and the teeth of the square rod 6 continue to mesh with the gear 10 but cannot rise, which affects the service life of the auxiliary device.

[0028] In this embodiment, the outer surface of the pressure cylinder 2 is fixedly connected to a connecting plate, the outer surface of the connecting plate is rotatably connected to a support shaft, the outer surface of the support shaft is fixedly sleeved with a guide wheel, and the pull rope 16 is laid on the outer surface of the guide wheel. Specifically, the pull rope 16 is supported by the guide wheel so that when the pull rope 16 is reeled in, the pull rope 16 can pull the fixed block, so that the piston cylinder moves inside the pressure relief pipe 17.

[0029] In this embodiment, a conical cylinder 19 is fixedly connected to the interior of the pressure relief tube 17, and a circular hole is opened at one end of the conical cylinder 19 facing the piston column 18, and a conical block 20 is movably connected to the interior of the circular hole. A first spring 21 is fixedly connected between the inner wall of the conical cylinder 19 away from the piston column 18 and the conical block 20, and a through hole 22 is opened on the side of the conical cylinder 19 away from the conical block 20. Specifically, when pressure is applied to the airbag tube 3 by an external pressure-applying device, the pressure will squeeze the conical block 20 so that the conical block 20 blocks the conical cylinder 19, and the pressure cannot leak from one side of the pressure relief tube 17. When negative pressure occurs, the negative pressure causes the conical block 20 to detach from the surface of the conical cylinder 19, so that air can be sucked out from the pressure relief tube 17 when negative pressure is generated.

[0030] In this embodiment, when the fixed rod 11 and the movable rod 12 are stored to be parallel to the hollow core shaft 1 , the piston rod 18 just breaks away from the inner wall of the pressure relief tube 17 .

[0031] In the specific implementation process, when the support plate 13 is retracted, the gear 10 drives the connecting shaft 9 to rotate, and the connecting shaft 9 drives the winding wheel 15 to rotate, and the pull rope 16 is retracted, and the pull rope 16 drives the piston column 18 to move to the outside of the pressure relief tube 17. When the fixed rod 11 and the movable rod 12 drive the support plate 13 to be stored to a state parallel to the hollow core shaft 1, the piston column 18 is separated from the inside of the pressure relief tube 17. At this time, when the negative pressure device generates negative pressure through the airbag tube 3, the air is discharged through the piston column 18 to avoid continuous after the support plate 13 is retracted. The negative pressure continuously drives the first piston disk 4 to move upward, while the teeth of the square rod 6 continue to mesh with the gear 10 but cannot rise, which affects the service life of the auxiliary device. When pressure is applied to the airbag tube 3 through an external pressure-applying device, the pressure will squeeze the conical block 20 so that the conical block 20 blocks the conical tube 19, and the pressure cannot leak from one side of the pressure relief tube 17. When negative pressure occurs, the negative pressure causes the conical block 20 to detach from the surface of the conical tube 19, so that air can be sucked out from the pressure relief tube 17 when negative pressure is generated.

[0032] Example 3: Please refer to Figure 1-Figure 9 The present invention provides a technical solution: the left and right outer surfaces of the pressure cylinder 2 are fixedly connected with a connecting pipe 23, a second piston disc is movably arranged inside the connecting pipe 23, a second piston rod 24 is fixedly connected to the outer surface of the second piston disc, and one end of the second piston rod 24 away from the second piston disc is fixedly connected to a limiting block 25, and two limiting holes 26 are provided on the inner wall of the hollow core shaft 1, and the two limiting holes 26 correspond to the two limiting blocks 25 respectively.

[0033] During the specific implementation process, when the pressure-applying device generates pressure in the airbag tube 3 so that the first piston disc 4 moves to the bottom of the connecting tube 23, the pressure squeezes the second piston disc through the connecting tube 23 so that the second piston disc drives the limit block 25 to be inserted into the inner hole, and the sleeve 7 and the pressure tube are fixed in the hollow core shaft 1. When negative pressure occurs, negative pressure is first generated on the second piston disc, so that the second piston rod 24 drives the limit block 25 to disengage from the limit hole 26, thereby releasing the limit on the sleeve 7 and the pressure tube.

[0034] Example 4: Please refer to Figure 1-Figure 9 The present invention provides a technical solution: a rubber plug 28 is provided at the middle end of the outer surface of the hollow core shaft 1, and conical bodies 27 are provided on the outer surfaces of both sides of the hollow core shaft 1 located at the rubber plug 28. Slips 29 are provided outside the two conical bodies 27, and the other parts of the two slips 29 are respectively provided at both ends of the hollow core shaft 1. Specifically, the two slips 29 are clamped toward the middle by a sealing tool, and the two slips 29 push the two conical bodies 27 to move, compressing the rubber plug 28 so that it expands radially to seal the inner wall of the wellbore.

[0035] In this embodiment, a plurality of receiving grooves are provided inside the conical body 27, and a second spring 30 is fixedly connected inside each of the plurality of receiving grooves. A friction column 31 is fixedly connected to the other end of the second spring 30, and an anti-slip protrusion is provided on the outer surface of the friction column 31. Specifically, when the rubber plug 28 expands, the friction column 31 contacts the inner wall of the wellbore and causes the second spring 30 to deform. The elastic force of the second spring 30 cooperates with the anti-slip protrusion of the friction column 31 to increase the friction force between the friction column 31 and the inner wall of the wellbore, thereby ensuring that the bridge plug will not deviate.

[0036] During the specific implementation process, the two slips 29 are clamped toward the middle by the sealing tool, and the two slips 29 push the two cones 27 to move, compressing the rubber plug 28, causing it to expand radially to seal the inner wall of the wellbore. While the rubber plug 28 expands, the friction column 31 contacts the inner wall of the wellbore and causes the second spring 30 to deform. The elastic force of the second spring 30 cooperates with the anti-slip protrusions of the friction column 31 to increase the friction between the friction column 31 and the inner wall of the wellbore, thereby ensuring that the bridge plug will not shift. After the auxiliary device is taken out, the soluble ball is put in to seal the hollow core shaft 1, and finally the bridge plug is completely dissolved.

[0037] It is worth noting that the friction column 31 is made of magnesium-based alloy, and the second spring 30 is made of magnesium-based alloy spring coil, so that the friction column 31 and the second spring 30 can also be dissolved.

[0038] Working principle: When the present invention is in use, in the process of sending the bridge plug into the oil and gas well, rolling friction occurs between the ball 14 and the inner wall of the pipeline, and the friction force is small, so as to avoid the bridge plug from being offset and stuck in the process of being sent into the oil and gas well. After the bridge plug is transported to a suitable position, it will be connected with the airbag tube 3 through an external negative pressure device, and air will be sucked into the airbag tube 3 through the negative pressure device, so that the pressure inside the pressure cylinder 2 becomes smaller, thereby driving the first piston disk 4 upward, and the first piston disk 4 drives the first piston rod 5 upward, so that the square rod 6 moves upward, so that the teeth drive the gear 10 to rotate, so that the fixed rod 11 and the movable rod 12 drive the support plate 13 to rotate, so that the support plate 13 is retracted to a state parallel to the central core axis, and then the pressure cylinder 2 and the sleeve 7 are taken out together, so that the auxiliary device for transporting the bridge plug can be taken out to avoid affecting the quality of subsequent construction.

[0039] When the support plate 13 is retracted, the gear 10 drives the connecting shaft 9 to rotate, and the connecting shaft 9 drives the winding wheel 15 to rotate, so as to reel in the drawstring 16, and the drawstring 16 drives the piston column 18 to move to the outside of the pressure relief tube 17. When the fixed rod 11 and the movable rod 12 drive the support plate 13 to be stored in a state parallel to the hollow core shaft 1, the piston column 18 is separated from the inside of the pressure relief tube 17. At this time, when the negative pressure device generates negative pressure through the airbag tube 3, the air is discharged through the piston column 18, so as to avoid continuous negative pressure after the support plate 13 is retracted. The first piston disc 4 is driven to move upward, while the teeth of the square rod 6 are continuously meshed with the gear 10 but cannot rise, which affects the service life of the auxiliary device. When pressure is applied to the airbag tube 3 by an external pressure-applying device, the pressure will squeeze the conical block 20 so that the conical block 20 blocks the conical tube 19, and the pressure cannot leak from one side of the pressure relief tube 17. When negative pressure occurs, the negative pressure causes the conical block 20 to detach from the surface of the conical tube 19, so that air can be sucked out from the pressure relief tube 17 when negative pressure is generated.

[0040] When the pressure-applying device generates pressure in the airbag tube 3 so that the first piston disc 4 moves to the bottom of the connecting tube 23, the pressure squeezes the second piston disc through the connecting tube 23 so that the second piston disc drives the limiting block 25 to be inserted into the inner hole, and the sleeve 7 and the pressure-applying tube are fixed in the hollow core shaft 1. When negative pressure occurs, negative pressure is first generated on the second piston disc so that the second piston rod 24 drives the limiting block 25 to disengage from the limiting hole 26, thereby releasing the limiting of the sleeve 7 and the pressure-applying tube.

[0041] The two slips 29 are clamped toward the middle by the sealing tool, and the two slips 29 push the two cones 27 to move and compress the rubber plug 28, so that it expands radially to seal the inner wall of the wellbore. While the rubber plug 28 expands, the friction column 31 contacts the inner wall of the wellbore and causes the second spring 30 to deform. The elastic force of the second spring 30 cooperates with the anti-slip protrusions of the friction column 31 to increase the friction between the friction column 31 and the inner wall of the wellbore, thereby ensuring that the bridge plug will not deviate. After the auxiliary device is taken out, the soluble ball is put in to seal the hollow core shaft 1, and finally the bridge plug is completely dissolved.

[0042] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A stable soluble bridge plug for oil and gas wells, comprising a hollow core shaft (1), characterized in that: The hollow core shaft (1) is provided with a pressure cylinder (2) inside, the top outer surface of the pressure cylinder (2) is fixedly connected to an airbag tube (3), the inside of the pressure cylinder (2) is movably provided with a first piston disc (4), the bottom outer surface of the first piston disc (4) is fixedly connected to a first piston rod (5), the bottom outer surface of the first piston rod (5) is fixedly connected to a square rod (6), the bottom outer surface of the pressure cylinder (2) is fixedly connected to a sleeve (7), the first piston rod (5) movably passes through the outer surface of the sleeve (7), the inside of the sleeve (7) is fixedly connected to four rectangular blocks (8), the four rectangular blocks (8) The relative outer surfaces are rotatably connected with connecting shafts (9), the outer surfaces of the four connecting shafts (9) are fixedly sleeved with gears (10), the outer surfaces of the four sides of the square rod (6) are connected with a plurality of teeth arranged in a linear array, the teeth are movably meshed with the outer surfaces of the four gears (10), the outer surfaces of the four gears (10) are fixedly connected with a fixed rod (11), the interior of the fixed rod (11) is movably inserted with a movable rod (12), the other end of the movable rod (12) is fixedly connected with a support plate (13), and the other end of the support plate (13) is provided with a plurality of balls (14).

2. A stable soluble bridge plug for oil and gas wells according to claim 1, characterized in that: The outer surface of the left connecting shaft (9) is fixedly sleeved with a winding wheel (15), the outer surface of the winding wheel (15) is wound with a pull rope (16), the outer surface of the pressure cylinder (2) is fixedly connected to a pressure relief pipe (17), the interior of the pressure relief pipe (17) is movably connected to a piston column (18), and the side of the piston column (18) located outside the pressure relief pipe (17) is fixedly connected to a fixed block, the pull rope (16) movably passes through the outer surface of the sleeve (7) and the other end of the pull rope (16) is fixedly connected to the fixed block.

3. A stable soluble bridge plug for oil and gas wells according to claim 1, characterized in that: The left and right outer surfaces of the pressure cylinder (2) are fixedly connected to connecting pipes (23), a second piston disc is movably arranged inside the connecting pipe (23), a second piston rod (24) is fixedly connected to the outer surface of the second piston disc, and one end of the second piston rod (24) away from the second piston disc is fixedly connected to a limiting block (25), and the inner wall of the hollow core shaft (1) is provided with two limiting holes (26), and the two limiting holes (26) correspond to the two limiting blocks (25) respectively.

4. A stable soluble bridge plug for oil and gas wells according to claim 1, characterized in that: A rubber plug (28) is provided at the middle end of the outer surface of the hollow core shaft (1), and cones (27) are provided on the outer surfaces of both sides of the rubber plug (28) of the hollow core shaft (1), and slips (29) are provided outside the two cones (27), and the other parts of the two slips (29) are respectively provided at the two ends of the hollow core shaft (1).

5. A stable soluble bridge plug for oil and gas wells according to claim 4, characterized in that: The conical body (27) is provided with a plurality of receiving grooves inside, and a second spring (30) is fixedly connected inside each of the plurality of receiving grooves. The other end of the second spring (30) is fixedly connected to a friction column (31), and the outer surface of the friction column (31) is provided with anti-slip protrusions.

6. A stable soluble bridge plug for oil and gas wells according to claim 1, characterized in that: A third spring is fixedly connected to the inner wall of the fixed column, and the other end of the third spring is fixedly connected to the movable column.

7. A stable soluble bridge plug for oil and gas wells according to claim 2, characterized in that: The outer surface of the pressure cylinder (2) is fixedly connected to a connecting plate, the outer surface of the connecting plate is rotatably connected to a support shaft, the outer surface of the support shaft is fixedly sleeved with a guide wheel, and the pull rope (16) is laid on the outer surface of the guide wheel.

8. A stable soluble bridge plug for oil and gas wells according to claim 2, characterized in that: A conical cylinder (19) is fixedly connected to the interior of the pressure relief pipe (17); a circular hole is provided at one end of the conical cylinder (19) facing the piston column (18); a conical block (20) is movably connected to the interior of the circular hole; a first spring (21) is fixedly connected between the inner wall of the conical cylinder (19) on the side away from the piston column (18) and the conical block (20); and a through hole (22) is provided on the side of the conical cylinder (19) away from the conical block (20).

9. A stable soluble bridge plug for oil and gas wells according to claim 2, characterized in that: When the fixed rod (11) and the movable rod (12) are stored until they are parallel to the hollow core shaft (1), the piston column (18) just detaches from the inner wall of the pressure relief pipe (17).

10. A stable soluble bridge plug for oil and gas wells according to claim 1, characterized in that: The bottom ends of the hollow core shaft (1) and the sleeve (7) are both provided with through slots for the fixed rod (11) and the movable rod (12) to move.

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