Soluble bridge plug for casing deformation well

Abstract

The invention relates to the technical field of non-uniformly distributed oil and gas reservoir transformation, and particularly discloses a soluble bridge plug for a casing deformation well, which comprises a limiting joint, a connecting pull rod, a rubber sleeve, a slip assembly, a central pipe, a locking ring and an expansion component, and the expansion component comprises a first cone expansion piece and a second cone expansion piece; the first cone expansion piece is arranged on the central pipe in a sleeving mode and located between the rubber sleeve and the slip assembly, one end of the first cone expansion piece is used for limiting the other end of the rubber sleeve, the other end of the first cone expansion piece is used for expanding one end of the slip assembly, and the first cone expansion piece is connected to the other end of the connecting pull rod; the second cone expansion part is used for expanding the other end of the slip assembly, and the locking ring is connected into the second cone expansion part and slidably connected to the connecting pull rod. The soluble bridge plug can achieve effective packing in an ultra-large annular gap after passing through a casing change point, it is guaranteed that the casing change well passing through the casing change point transformation process is smoothly implemented, section loss is reduced, and the reservoir transformation efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of reservoir transformation of unevenly distributed oil and gas reservoirs, in particular to a soluble bridge plug for casing-changing wells. Background Art

[0002] At present, when soluble bridge plugs are faced with wellbore shrinkage and other well conditions, soluble alloy materials and soluble rubber tubes are often used to improve the strength of the tool itself while reducing the outer diameter of the tool; however, in actual field applications, when the soluble rubber tube seals the annular gap too large, the sealing performance cannot meet the requirements of subsequent fracturing construction; at the same time, when the bridge plug encounters a serious shrinkage of the wellbore and needs to seal the super-large annular gap, in order to ensure the sealing effect of the rubber tube, the radial size of the rubber tube cannot be further reduced, resulting in the inability to smoothly lower and seal. The continuous tubing hydraulic jet fracturing process is often used on site, which greatly increases the cost of transformation and greatly reduces the efficiency of transformation. In addition, the existing sealing tool will have the risk of premature sealing due to collision with the wellbore wall during the process of lowering into the wellbore, and it is necessary to rely on shear pins and other structures to prevent premature sealing to strengthen the connection, which increases the manufacturing cost. For example, a fully soluble bridge plug disclosed in the patent document (China Patent Publication No.: CN112647891B) does not have a secondary expansion function, has low expansion efficiency, poor anchoring effect, and has the risk of premature sealing and unreliable sealing. Summary of the invention

[0003] The purpose of the present invention is to provide a soluble bridge plug for a casing change well, which can achieve a small diameter and a large expansion rate. Based on the two-stage expansion design concept, the main body adopts a soluble magnesium alloy and a soluble rubber material. After passing the casing change point, the ultra-large annular space gap is effectively sealed, ensuring the smooth implementation of the casing change well through the casing change point transformation process, reducing the loss of sections, and improving the efficiency of reservoir transformation.

[0004] The purpose of the present invention can be achieved by the following technical solutions:

[0005] A soluble bridge plug for a casing-changing well comprises a limit joint, a connecting rod, a rubber cylinder, a slip assembly, a center pipe, a locking ring and an expansion assembly, wherein the rubber cylinder is sleeved on the center pipe, the center pipe is sleeved on the connecting rod, one end of the connecting rod is provided with a connector for connecting to a driving rod of a sealing tool, the limit joint is connected to the connecting rod, and one end of the limit joint is used for connection and limiting of the connector, the other end of the limit joint is used for limiting the position of one end of the center pipe and the rubber cylinder, the other end of the connecting rod is sequentially passed through the center pipe and the slip assembly and then connected to the expansion assembly, the expansion assembly is sequentially connected to the rubber cylinder, the slip assembly and A locking ring, which can be unidirectionally locked with the other end of the center tube, and the expansion assembly includes a first cone expansion piece and a second cone expansion piece, the first cone expansion piece is sleeved on the center tube and is located between the rubber sleeve and the cava assembly, one end of the first cone expansion piece is used to limit the other end of the rubber sleeve, and the other end of the first cone expansion piece is used for the expansion of one end of the cava assembly, the first cone expansion piece is connected to the other end of the connecting rod, and the second cone expansion piece is used for the expansion of the other end of the cava assembly, the locking ring is connected in the second cone expansion piece, and the locking ring can be slidably connected to the connecting rod.

[0006] In a further solution, the cava assembly includes a rubber seat, a ceramic column and a cava frame, the ceramic column is connected to the outer surface of the cava frame, and the rubber seats are provided at both ends of the cava frame. The rubber seats are used to press against the first cone expansion piece and the second cone expansion piece to drive the cava frame to expand outward.

[0007] In a further solution, the cava skeleton includes a plurality of cava pieces and an intermediate sleeve, wherein the plurality of cava pieces are evenly connected to the intermediate sleeve in a spoke shape, and the cava pieces and the intermediate sleeve can be sheared, and mounting holes for connecting the ceramic columns are evenly distributed on the cava pieces.

[0008] In a further solution, an axial hole for coaxially cooperating with the connecting rod is provided at the center of the intermediate sleeve, and the outer circle of the axial hole forms a regular polygon, the number of sides of the regular polygon is equal to the number of the tile pieces, and the connection between adjacent sides of the regular polygon is connected to the inner wall of the tile piece through spokes which are wide at the top and narrow at the bottom.

[0009] In a further solution, the rubber seat is in the shape of a cone sleeve, and the surface in contact with the slip frame and the expansion component is a cone surface.

[0010] In a further solution, the distance from the outer end surface of the rubber seat to the center of the connecting rod is greater than the distance from the outer end surface of the ceramic column to the center of the connecting rod.

[0011] In a further embodiment, the rubber seat is vulcanized and adhered to the slip frame.

[0012] In a further solution, the first cone expansion member includes a first cone, a first wrist guard is provided at one end of the first cone close to the rubber tube, the first wrist guard has a conical cavity at one end of the first cone close to the rubber tube, the two ends of the rubber tube are configured as conical bosses, the conical cavity is used to wrap the conical boss, the second cone expansion member includes a soluble base and a second cone, the second cone is connected to the soluble base, and a cavity for accommodating the locking ring is provided between the two.

[0013] In a further solution, a second wristguard is arranged inside the first wristguard, the second wristguard is in the shape of a cone sleeve, and one end of the second wristguard is used to connect with the conical cavity of the first wristguard, and the other end is used to press against the conical boss at the end of the rubber tube. The limit joint is provided with a third wristguard near one end of the rubber tube, and the third wristguard has a conical cavity that matches the conical boss at the end of the rubber tube.

[0014] In a further solution, the soluble base and the second frustum as well as the soluble base and the connecting rod are connected via a constant pressure disconnection structure.

[0015] Beneficial effects of the present invention:

[0016] (1) The invention adopts a two-point expansion structure design to achieve small-diameter isolation of ultra-large annular gaps, effectively solving the problem of fracturing through the casing reduction section (severe deformation leads to a significant reduction in the diameter).

[0017] (2) In the sealing pressure-bearing system of the present invention, soluble wrist guards are provided at both ends of the rubber cylinder, which can provide support and limit for the expansion seal of the rubber cylinder. During the stage of lowering the bridge plug, since the size of the wrist guard is slightly larger than the outer diameter of the rubber cylinder, the sealing surface of the rubber cylinder can be effectively protected from being scratched.

[0018] (3) The soluble rubber tube of the invention has a large axial length. When the bridge plug is seated in the wellbore, the anchoring structure composed of the rubber tube and the wrist guards and slips at both ends has a stronger anchoring effect. When sealing, the rubber tube and slips cooperate with each other in soft and hard ways to achieve adaptive straightening and automatically adjust the seating posture of the bridge plug, effectively ensuring that the bridge plug is centered when seated, thereby effectively ensuring the sealing pressure-bearing reliability of the bridge plug.

[0019] (4) The slip assembly of the present invention is designed with vulcanized soluble rubber on the slip frame, which effectively protects the slip from premature sealing caused by the collision of the wellbore with the bridge plug during the lowering process. Compared with the anti-premature sealing structure relying on shear pins, this structure has no risk of premature sealing.

[0020] (5) The slip assembly of the invention is designed as a combined structure. The rubber is vulcanized on the slip frame. When the bridge plug is set, the connection between the slip frame and the slip frame is evenly broken. The wedge-shaped structures at both ends continue to wedge into the slip along the inclined surface. The outer diameter of the slip continues to increase, achieving secondary expansion of the slip, thereby achieving the wellbore isolation again through the sleeve change / neck shrinkage section.

[0021] (6) Both ends of the cava assembly of the present invention are provided with cones for straightening, so that the cava assembly is evenly loaded as a whole, which effectively improves the anchoring performance of the bridge plug anchoring system.

[0022] (7) After the soluble base of the bridge plug of the present invention falls off, it dissolves by itself, does not occupy the wellbore, and does not affect subsequent construction; at the same time, after the soluble base falls off, the locking ring is directly exposed and can come into contact with the liquid. After the fracturing construction is completed, the bridge plug disintegrates quickly, thereby maximizing the contact area between the soluble part of the bridge plug and the liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 This is a connection schematic diagram of a soluble bridge plug for a casing-changing well in an embodiment of the present invention;

[0025] Figure 2 is a connection schematic diagram of the slip assembly in an embodiment of the present invention;

[0026] Figure 3 yes Figure 2 Schematic diagram of the cross-section at AA in the middle;

[0027] Figure 4 is an axial schematic diagram of a slip frame in an embodiment of the present invention;

[0028] Figure 5 is a schematic front view of the end of the slip frame in an embodiment of the present invention;

[0029] In the figure: 1. limit joint; 11. third wrist guard; 2. connecting rod; 21. connecting head; 3. rubber cylinder; 4. cava assembly; 41. rubber seat; 42. ceramic column; 43. cava frame; 431. cava piece; 430. mounting hole; 432. intermediate sleeve; 5. center tube; 6. locking ring; 7. expansion assembly; 71. first cone expansion piece; 711. first cone; 712. first wrist guard; 72. second cone expansion piece; 721. soluble base; 722. second cone; 8. second wrist guard; 9. constant pressure disconnect structure. DETAILED DESCRIPTION

[0030] 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.

[0031] like Figure 1 As shown, a soluble bridge plug for a casing-changing well comprises a limit joint 1, a connecting rod 2, a rubber cylinder 3, a slip assembly 4, a central tube 5, a locking ring 6 and an expansion assembly 7. The rubber cylinder 3 is sleeved on the central tube 5, the central tube 5 is sleeved on the connecting rod 2, one end of the connecting rod 2 is provided with a connector 21 for connecting to a driving rod of a sealing tool, the limit joint 1 is connected to the connecting rod 2, and one end of the limit joint 1 is used for connection and limiting of the connector 21, the other end of the limit joint 1 is used for limiting the position of one end of the central tube 5 and the rubber cylinder 3, the other end of the connecting rod 2 passes through the central tube 5 and the slip assembly 4 in sequence, and then is connected to the expansion assembly 7, and the expansion assembly 7 is connected to the rubber cylinder 3, the slip assembly 4 and the locking ring 6 in sequence. The locking ring 6 can be one-way locked with the other end of the center tube 5, and the one-way locking can be achieved through a one-way locking thread. The expansion assembly 7 includes a first cone expansion piece 71 and a second cone expansion piece 72. The first cone expansion piece 71 is sleeved on the center tube 5 and is located between the rubber sleeve 3 and the cava assembly 4. One end of the first cone expansion piece 71 is used to limit the other end of the rubber sleeve 3, and the other end of the first cone expansion piece 71 is used for the expansion of one end of the cava assembly 4. The first cone expansion piece 71 is connected to the other end of the connecting rod 2, and the second cone expansion piece 72 is used for the expansion of the other end of the cava assembly 4. The locking ring 6 is connected in the second cone expansion piece 72, and the locking ring 6 can be slidably connected to the connecting rod 2.

[0032] Its working principle and implementation method are as follows: check the setting tool matched with the above-mentioned soluble bridge plug for the casing change well, complete the preparation work of connecting the limit joint 1 and the connecting rod 2 in the bridge plug with the setting tool and the continuous oil pipe; use the continuous oil pipe to transport the soluble bridge plug and the setting tool to the predetermined position of the wellbore; after being transported to the predetermined position, the ground pump is pressurized through the continuous oil pipe, the bridge plug setting tool is started, the left end face of the limit joint 1 is against the right end face of the setting tool and remains motionless, and the connecting rod 2 is driven by the driving rod of the setting tool to move to the left, and combined with the limiting effect of the second cone expansion piece 72, the compression expansion of the rubber cylinder 3 and the secondary expansion of the slip assembly 4 are realized, so as to realize the firm fit of the rubber cylinder to the inner wall of the casing, and the tight bite of the slip assembly with the inner wall of the wellbore casing to achieve firm anchoring; the second cone expansion piece 72 is connected to the connecting rod 2 by a thread, and the base is made of soluble magnesium alloy material. When the thread is subjected to tension and reaches the shear limit of the material, the second cone expansion piece 72 The thread between the connecting rod 2 is disengaged, and the center tube 5 and the locking ring 6 are provided with special threads, and the threads have a one-way locking function. During the continuous leftward movement of the rod, the one-way locking of the special thread of the locking ring is mainly to prevent the compression effect of the load applied by the rod to the rubber cylinder and the slip assembly from rebounding. Relying on the limiting effect of the special thread and the locking ring 6, the rubber cylinder 3 and the slip assembly 4 are kept in an expanded state, and force is applied to both ends of the slip assembly 4 and the rubber cylinder 3, and the middle part is driven to expand through the two ends to achieve contact and engagement with the wellbore casing wall, and observe the change in pump pressure; after lifting the continuous oil pipe to take out the driving rod of the sealing tool and the connecting rod 2, start to throw the soluble ball; after sending the soluble ball into the limiting joint 1 and the connected center tube 5, start fracturing transformation; after the transformation is completed, the soluble bridge plug automatically starts to dissolve, and it will soon be completely dissolved without affecting the subsequent fracturing operation and the production construction, so as to realize the wellbore emptying; then it can be connected and transported to the next set of wells for soluble bridge plug.

[0033] The sealing tool, coiled tubing, dissolvable ball, surface pump, and one-way locking structure of the lock ring 6 and the center pipe 5 can all be applied to existing technologies and installation methods, which are not drawn one by one in the figure.

[0034] According to the above working principle or implementation mode, some preferred embodiments or structures are provided, such as Figure 2 As shown, the slip assembly 4 includes a rubber seat 41, a ceramic column 42 and a slip frame 43. The ceramic column 42 is connected to the outer surface of the slip frame 43. Both ends of the slip frame 43 are provided with rubber seats 41. The rubber seat 41 is used to press against the first cone expansion member 71 and the second cone expansion member 72 to drive the slip frame 43 to expand outward. The elastic contact of the rubber seat 41 can reduce the resistance of the slip frame 43 when it is lowered into the well.

[0035] like Figure 4As shown, the slip frame 43 includes a plurality of slip pieces 431 and an intermediate shaft sleeve 432. The plurality of slip pieces 431 are evenly connected to the intermediate shaft sleeve 432 in a spoke shape, and the slip pieces 431 and the intermediate shaft sleeve 432 can be sheared. The slip pieces 431 are evenly provided with mounting holes 430 for connecting the ceramic column 42. This structure facilitates the slip pieces 431 to expand outward.

[0036] like Figure 5 As shown, the center of the intermediate sleeve 432 is provided with an axial hole for coaxially cooperating with the connecting rod 2, the outer ring of the axial hole forms a regular polygon, and the connection between adjacent sides of the regular polygon is connected to the inner wall of the tile piece through spokes that are wide at the top and narrow at the bottom. Here, the number of the tile pieces 431 can be preferably 5, the number of sides of the regular polygon is preferably 5, and the shape of the spokes that are wide at the top and narrow at the bottom is preferably an inverted triangle.

[0037] like Figure 3 As shown, the rubber seat 41 is in a cone sleeve shape, and the surface in contact with the slip frame 43 and the expansion assembly 7 is a cone surface. The cone surface structure facilitates the expansion of the slip frame 43 from the inside to the outside.

[0038] In this way, when the cava assembly is lowered into the well, the middle sleeve 432 can maintain radial stability under the coaxial limiting action of the connecting rod 2, and can maintain axial stability under the axial limiting action of the rubber seats 41 at both ends, so that the cava piece 431 can remain stable on the middle sleeve 432 during the process of being lowered into the well, and is not easy to be displaced during installation, resulting in premature sealing. During sealing, the cava piece 431 is pulled by the connecting rod 2 and squeezed by the first cone expansion piece 71 and the second cone expansion piece 72 on both sides, and is evenly broken at the corner of the pentagon and expands outward once. The broken cava piece 431 continues to expand outward for a second time under the squeezing action of the rubber seat 41, and is finally tightly anchored to the inner wall of the well casing.

[0039] The outer end surface of the rubber seat 41 is as Figure 1 The distance between the center of the connecting rod 2 shown is greater than the distance between the outer end face of the ceramic column 42 and the center of the connecting rod 2. In this way, the ceramic column 42 and the rubber tube 3 can be protected to prevent them from expanding prematurely and causing midway sealing. Those skilled in the art should be able to think that the distance between the outer end face of the limit joint 1, the first cone expansion member 71, and the second cone expansion member 72 and the central axis of the connecting rod 2 is slightly greater than the distance between the outer end face of the rubber tube 3 and the ceramic column 42 and the center of the connecting rod 2. In this way, it can not only play a role in straightening when going down the well, but also prevent premature sealing.

[0040] The rubber seat 41 is vulcanized and adhered to the slip frame 43 through a vulcanization process. This can prevent the two from being separated, causing the rubber seat 41 to not play a connecting role.

[0041] See also Figure 1As shown, the first cone expansion member 71 includes a first cone 711, and the first cone 711 is provided with a first wrist guard 712 at one end close to the rubber tube 3. The first wrist guard 712 has a conical cavity at one end close to the rubber tube 3. The two ends of the rubber tube 3 are provided with conical bosses, and the conical cavity is used to wrap the conical bosses. The second cone expansion member 72 includes a soluble base 721 and a second cone 722. The second cone 722 is connected to the soluble base 721, and a cavity for accommodating the lock ring 6 is provided between the two. The two ends of the slip frame 43 are simultaneously expanded outward through the two cone structures, and the structure is simple. The use of the soluble base 721 is not only convenient for the installation of the lock ring 6, but also can reduce the structure when the hand is lost.

[0042] The first wrist guard 712 is provided with a second wrist guard 8, which is in a cone sleeve shape, and one end of which is used to connect with the cone cavity of the first wrist guard 712, and the other end is used to press against the cone boss at the end of the rubber tube 3. The third wrist guard 11 is provided at one end of the limit joint 1 close to the rubber tube 3, and the third wrist guard 11 has a cone cavity that matches the cone boss at the end of the rubber tube 3. The first wrist guard 712, the second wrist guard 8, and the third wrist guard 11 are provided to protect the rubber tube 3, and they are preferentially contacted with the well casing wall when going down the well, so as to prevent the rubber tube 3 from colliding with the well casing wall and setting the seal in advance when it is not straightened when going down the well.

[0043] The soluble base 721 and the second cone 722 and the soluble base 721 and the connecting rod 2 are connected by a constant pressure disconnection structure 9. The constant pressure disconnection structure 9 is that when the connection pressure between the two reaches a fixed value, the connection between the two can be disconnected, preferably a constant pressure disconnection thread, which is convenient for dropping. A shear pin can also be used.

[0044] A specific method of use may be that the connecting rod 2 is connected to the driving rod of the sealing tool through a thread, and the left end of the limiting joint 1 contacts the connecting rod 2, and the two remain in a fixed state during the process of the bridge plug being lowered into the well. When the bridge plug is sealed, the left end face of the limiting joint 1 abuts against the sealing tool and remains stationary, and the connecting rod 2 moves to the left under the drive of the sealing tool driving rod, and combines the limiting effects of the second cone expansion piece 72, the first cone expansion piece 71, the locking ring 6 and the center tube 5 to realize the compression expansion of the rubber cylinder 3 and the secondary expansion of the slip assembly 4, thereby firmly fitting to the inner wall of the casing in the well; the second cone expansion piece 72 is connected to the connecting rod 2 through the Through threaded connection, the soluble base 721 is made of soluble magnesium alloy material. When the thread that can be disconnected at a constant pressure is subjected to tension that reaches the shear limit of the material, the thread between the second cone expansion piece 72 and the connecting rod 2 is disengaged, and the soluble base 721 is separated from the second cone 722; at the same time, the center tube 5 and the locking ring 6 are connected by a structure with a one-way locking function, such as a one-way locking thread limiter, similar to a ratchet pawl, so that the connecting rod 2 is continuously moved to the left, ensuring that when the thread between the second cone expansion piece 72 and the connecting rod 2 is disengaged, the positional relationship between the various components connected on the connecting rod 2 for expansion does not change, and the expanded state is maintained.

[0045] The wristband material is made of high-elongation soluble magnesium alloy. When the rubber tube 3 is compressed and expanded, the third wristband 11, the second wristband, and the first wristband 712 expand and open toward the rubber tube 3. The mechanical strength of the second wristband is weaker than that of the first wristband 712. The first wristband 712 can provide support for the second wristband.

[0046] The first cone 711 , the second cone 722 and the slip assembly 4 are connected in series via conical surfaces. When the bridge plug is set, the first cone 711 and the second cone 722 are compressed and wedged into the slip assembly 4 , thereby expanding the slip assembly 4 .

[0047] See also Figure 2 As shown, the rubber seat 41 is made of soluble rubber material, and the slip frame 43 is made of high-strength magnesium alloy material. The rubber seat 41 is vulcanized on the slip frame 43 through a vulcanization process, and the ceramic column 42 is placed in the preset mounting hole of the slip frame 43. When the bridge plug is set, the first cone 711 and the second cone 722 are wedged into the expansion rubber seat 41, and the rubber seat 41 links the slip frame 43 to achieve secondary expansion of the slip sheet 431. The ceramic column 42 contacts the inner wall of the casing and is firmly anchored under a certain load. The surface of the soluble bridge plug can be combined with surface treatment processes such as passivation to meet the requirements of complex working conditions such as acid fracturing and high temperature, and effectively improve the comprehensive performance of the bridge plug. After the connection rod 2 is set, it can be smoothly lifted up with the setting pipe string. After the fracturing construction is completed, the remaining part of the bridge plug can be automatically dissolved. The particle size of the dissolved product is micron-level and can be smoothly discharged back to the wellhead.

[0048] It should be noted that the terms "first", "second" etc. in the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged in appropriate circumstances, so that the embodiments of the present application described here. In the present application, the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inside", "outside", "middle", "vertical", "horizontal", "lateral", "longitudinal" etc. are based on the orientation or positional relationship shown in the accompanying drawings.

[0049] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0050] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A soluble bridge plug for a casing-changing well, comprising a limit joint (1), a connecting rod (2), a rubber sleeve (3), a slip assembly (4), a central tube (5), a locking ring (6) and an expansion assembly (7), wherein the rubber sleeve (3) is sleeved on the central tube (5), the central tube (5) is sleeved on the connecting rod (2), one end of the connecting rod (2) is provided with a connector (21) for connecting to a driving rod of a sealing tool, the limit joint (1) is connected to the connecting rod (2), and the limit joint (21) is connected to the connecting rod (2). One end of the head (1) is used for connection limiting of the connecting head (21), and the other end of the limiting joint (1) is used for limiting the center tube (5) and one end of the rubber cylinder (3). The other end of the connecting rod (2) passes through the center tube (5) and the slip assembly (4) in sequence and is connected to the expansion component (7). The expansion component (7) is connected to the rubber cylinder (3), the slip assembly (4) and the locking ring (6) in sequence. The locking ring (6) can be unidirectionally locked with the other end of the center tube (5), characterized in that: The expansion component (7) includes a first cone expansion member (71) and a second cone expansion member (72), wherein the first cone expansion member (71) is sleeved on the central tube (5) and is located between the rubber sleeve (3) and the cava assembly (4), one end of the first cone expansion member (71) is used to limit the other end of the rubber sleeve (3), and the other end of the first cone expansion member (71) is used to expand one end of the cava assembly (4), the first cone expansion member (71) is connected to the other end of the connecting rod (2), and the second cone expansion member (72) is used to expand the other end of the cava assembly (4), the locking ring (6) is connected in the second cone expansion member (72), and the locking ring (6) can be slidably connected to the connecting rod (2).

2. The soluble bridge plug for casing-changing well according to claim 1, characterized in that: The slip assembly (4) comprises a rubber seat (41), a ceramic column (42) and a slip frame (43); the ceramic column (42) is connected to the outer surface of the slip frame (43); both ends of the slip frame (43) are provided with the rubber seat (41); the rubber seat (41) is used to abut against the first cone expansion member (71) and the second cone expansion member (72) to drive the slip frame (43) to expand outward.

3. The soluble bridge plug for casing-changing well according to claim 2, characterized in that: The slip frame (43) comprises a plurality of slip pieces (431) and an intermediate shaft sleeve (432). The plurality of slip pieces (431) are evenly connected to the intermediate shaft sleeve (432) in a spoke-like manner, and the slip pieces (431) and the intermediate shaft sleeve (432) can be sheared. The slip pieces (431) are evenly provided with mounting holes (430) for connecting the ceramic columns (42).

4. The soluble bridge plug for casing-changing well according to claim 3, characterized in that: The center of the intermediate sleeve (432) is provided with an axial hole for coaxially cooperating with the connecting rod (2), the outer circle of the axial hole forms a regular polygon, the number of sides of the regular polygon is equal to the number of the tile pieces, and the connection between adjacent sides of the regular polygon is connected to the inner wall of the tile piece through spokes that are wide at the top and narrow at the bottom.

5. The soluble bridge plug for casing-changing well according to claim 2, characterized in that: The rubber seat (41) is in the shape of a cone sleeve, and the surface in contact with the slip frame (43) and the expansion component (7) is a cone surface.

6. The soluble bridge plug for casing-changing well according to claim 2, characterized in that: The distance from the outer end surface of the rubber seat (41) to the center of the connecting rod (2) is greater than the distance from the outer end surface of the ceramic column (42) to the center of the connecting rod (2).

7. The soluble bridge plug for casing-changing well according to claim 2, characterized in that: The rubber seat (41) is vulcanized and adhered to the slip frame (43).

8. The soluble bridge plug for casing-changing well according to claim 1, characterized in that: The first cone expansion member (71) includes a first cone (711), and a first wrist guard (712) is provided at one end of the first cone (711) close to the rubber tube (3). The first wrist guard (712) has a conical cavity at one end close to the rubber tube (3). The two ends of the rubber tube (3) are configured as conical bosses, and the conical cavity is used to wrap the conical boss. The second cone expansion member (72) includes a soluble base (721) and a second cone (722). The second cone (722) and the soluble base (721) are connected, and a cavity for accommodating the locking ring (6) is provided between the two.

9. The soluble bridge plug for casing-changing well according to claim 8, characterized in that: A second wrist guard (8) is arranged inside the first wrist guard (712), and the second wrist guard (8) is in the shape of a cone sleeve, and one end of the second wrist guard (8) is used to connect with the conical cavity of the first wrist guard (712), and the other end is used to press against the conical boss at the end of the rubber cylinder (3). The limit joint (1) is provided with a third wrist guard (11) at one end close to the rubber cylinder (3), and the third wrist guard (11) has a conical cavity that matches the conical boss at the end of the rubber cylinder (3).

10. The soluble bridge plug for casing-changing well according to claim 8, characterized in that: The soluble base (721) and the second cone (722) as well as the soluble base (721) and the connecting rod (2) are connected via a constant pressure disconnection structure (9).

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