CN111794710A - A soluble bridge plug - Google Patents

Abstract

The present invention proposes a soluble bridge plug. It includes a conical cylinder member made of soluble alloy material, the outer surface of the conical cylinder member is a conical surface, and the outer surface is provided with a protruding coarse thread or a groove matching with the coarse thread; it also includes a soluble The slip group includes a plurality of slips made of soluble alloy material; the inner surface of the soluble slip group is formed with a groove matching with the coarse thread on the outer surface of the conical cylinder member, or is The coarse thread matched with the grooves on the outer surface of the conical cylindrical part enables the soluble slip group to perform a helical expansion movement relative to the conical cylindrical part on the outer surface of the conical cylindrical part; the annular tailstock, Made of soluble alloy material, a screw hole is formed in the center of the annular tailstock to match the threaded section at the end of the central connecting shaft, and one side of the annular tailstock abuts against the soluble slip One side of the group, under the pulling action of the central connecting shaft, can push the soluble slip group to perform a helical expansion motion relative to the conical cylindrical part along the outer surface of the conical cylindrical part.

Description

A soluble bridge plug

technical field

The invention relates to the technical field of oil and gas field and shale gas development, in particular to a soluble bridge plug for multi-stage fracturing.

current technology

In the development of shale gas, it is necessary to perform staged fracturing of shale gas wells, and bridge plugs play an important role in the plugging of shale gas wells. At present, in the development of shale gas, soluble bridge plugs are mainly used. The soluble bridge plugs are made of soluble metal and degradable rubber. They are matched with conventional setting tools and pumped into the well to realize staged fracturing. After the fracturing is completed It can be directly tested and put into production, and the bridge plug is quickly dissolved under the action of the flowback fluid. No salvage, no drilling and grinding, and it is convenient for production and post-measure construction without any intervention.

For the soluble bridge plug shown in CN203925413U, during downhole setting, as shown in Fig. 1-Fig. 2, the push ring 3 is displaced downward under the action of the setting force, and first the lower cone 9 pushes the soluble slip group 10. The well wall 1 is expanded and stuck, and then the rubber cylinder group 7 is expanded to achieve setting. Finally, the upper cone 5 pushes the upper soluble slip group 4 to expand and block the well wall, and the setting process is over.

After the fracturing process, the bridge plug 12 remains in the well pipe 1 as a whole, and the soluble upper slip group 4 and the soluble lower slip group 10 made of soluble metal materials degrade and disappear by themselves after a period of time. The cartridge group 7 elastically recovers and unpacks. In the prior art, the rubber tube is difficult to degrade, and the wellbore is often blocked due to the rubber tube in the later stage of construction.

Technical solutions

In order to overcome the above problems, the present invention proposes a soluble bridge plug.

In one solution, the soluble bridge plug includes a conical cylindrical member made of a soluble alloy material, an axial channel is provided inside the conical cylindrical member, an outer surface of the conical cylindrical member is a conical surface, and the outer surface There is a protruding coarse thread or a groove matching with the coarse thread; the central connecting shaft can be axially slidably inserted into the channel inside the conical cylinder, and the end surface of the central connecting shaft is provided with A thread segment; also includes a soluble slip group, including a plurality of slips made of soluble alloy material, the soluble slip group is surrounded on the outer surface of the conical cylinder in a relatively movable manner, and can be The inner surface of the dissolving slip group is an inner conical surface that matches the shape of the outer surface of the conical cylinder member, and the outer surface is a cylindrical surface coaxial with the central connecting shaft; on the inner surface of the dissolving slip group, there are formed The grooves that match the coarse thread on the outer surface of the conical cylinder member, or the coarse thread that matches the grooves on the outer surface of the cone cylinder member, enable the soluble slip group to be in the conical cylinder. The outer surface of the piece performs a helical expansion movement relative to the conical cylinder piece; the annular tailstock is made of soluble alloy material, and the center of the annular tailstock forms a matching connection with the threaded section at the end of the central connecting shaft The screw hole, one side of the annular tailstock abuts on one side of the soluble slip group, and under the pulling action of the central connecting shaft, the soluble slip group can be pushed along the outer surface of the cone. The surface performs a helical expansion motion relative to the cone.

In a further solution, it also includes a sealing ring made of soluble rubber, abutting on one end of the annular tailstock away from the soluble slip group, and the sealing ring is pushed by the slip group that performs a spiral expansion motion. , which can move and expand along the outer surface of the cone.

In a further solution, a snap ring is also included, and the through hole in the center of the snap ring has an inner thread for being sleeved on the central connecting shaft through a threaded connection, and the outer diameter of the snap ring is larger than the outer diameter of the inner channel of the conical cylinder. , in order to limit the position of the conical cylinder, the conical cylinder and the soluble slip group are positioned on the retaining ring and the annular tail through the snap ring and the annular tailstock connected with the threaded section at the end of the central connecting shaft. between seats.

In a further solution, the outer surface of the slip has a pawl structure with parallel lines.

In a further solution, the pitch of the coarse thread protruding on the outer surface of the conical cylindrical member or the groove matching the coarse thread is set to a variable pitch or a fixed pitch; when the pitch is set to a variable pitch, the The pitch of the coarse thread or groove is larger on the side of the conical cylinder member near the top of the cone, while the pitch on the side near the bottom of the cone is smaller; when the pitch is set to a fixed pitch, the inner surface of the slip group The radian of the cone is set to match the radian of the outer surface of the cone member near the bottom of the cone.

In a further solution, only one row of coarse threads or grooves is provided on the inner surface of the slip.

In a further solution, a radial sliding groove is concavely provided on the side of the annular tailstock that abuts against the slip group, and the side where the slips are matched is convexly provided with the sliding groove along the radial direction. The rib matched with the groove enables the slip group to slide along the sliding groove during the radial expansion process.

In a further solution, the slip group includes 6 slips, and the shape of the groove or coarse thread on the surface of the cone member is set to be 6 involutes, and each involute is at the surface of the cone member. The rotation angle is one revolution.

In a further scheme, an experimental device is also proposed. On the inner surface of one end of the slip group close to the annular tailstock, a displacement sensor is arranged to detect the rotational movement between the slip group and the cone member in the circumferential direction. Whether it occurs and detects the relative displacement in the axial direction between the slip group and the cone member; and between the annular tailstock and the slip group, a pressure sensor is installed to detect the pressing force of the annular tailstock on the slip group, The sensing signals of the displacement sensor and the pressure sensor are transmitted to the ground for monitoring through the signal transmission line set in the central connecting shaft.

An experimental method is also proposed. A recording device is set up on the ground to receive and record the relative rotational displacement signal between the cone and the slip group in the circumferential direction sent by the displacement sensor, the cone and the slip. The relative rotational displacement signal between the shoe groups in the axial direction and the pressure signal between the annular tailstock and the slip group sensed by the pressure sensor, for the pitch, tooth shape, There are many possible combinations of tooth height, groove shape, and groove depth. For each combination, a downhole setting experiment is performed separately. For each group of experiments, according to the relative rotational displacement signal and pressure signal, determine the ring shape Whether there is a circumferential rotation between the tailstock and the slip group, record the magnitude of the pressure and tension required when the circumferential rotation starts, determine whether there is a tripping between the coarse thread and the groove, and record the central connecting shaft The pressure when tripping from the annular tailstock, through multiple sets of experiments, selects the optimal combination of coarse thread and groove pitch, tooth shape, tooth height, groove shape, and groove depth.

Compared with the prior art, the present invention only uses soluble rubber in the sealing ring, which saves the amount of insoluble soluble rubber, so that the bridge plug can be fully disintegrated. In addition, because the soluble rubber is used to make the sealing ring, The sealing effect can also be improved.

In addition, axial locking is achieved between the slip group and the conical cylinder through the mating relationship between the coarse thread and the groove, thereby enhancing the bonding strength of the slips and the conical cylinder and preventing axial disengagement. Compared with the prior art technology in which the locking connector is additionally provided, the number of components is saved, the processing and assembly are simple, the integrity is better and the strength is higher.

Description of drawings

Figure 1 is a half-section view of a soluble bridge plug in the prior art before setting

Figure 2 is a half-section view of the soluble bridge plug in the prior art after setting

Figure 3A is a perspective view of the bridge plug in its original state

Figure 3B is a cross-sectional view of the bridge plug in its original state

Figure 3C is an exploded view of the bridge plug

Figure 4 is a perspective view of the cone member

Figure 5 is a perspective view of the slip

Figure 6 shows the three-dimensional state of the bridge plug after the setting is completed

Figure 7 is a cross-sectional view of the bridge plug experimental device

Detailed ways

As shown in Figures 3A, 3B, and 3C, the bridge plug in this patent includes a cone 1 made of a soluble alloy material, a recyclable central connecting shaft 2 that can withstand strong tensile forces, and a soluble alloy material. The soluble slip group 3 and the annular tailstock 4 made of soluble alloy material.

Wherein, the cone-shaped member 1 is made of soluble alloy material, an axial channel 10 is arranged inside the cone-shaped member 1 , the outer surface of the cone-shaped member 1 is a cone surface, and the outer surface is provided with an axial channel 10 . The protruding coarse thread 11, or the groove 11 matched with the coarse thread;

The central connecting shaft 2 can be axially slidably inserted into the channel 10 inside the conical cylindrical member, and the end surface of the central connecting shaft 2 is provided with a threaded segment 21;

The soluble slip group 3 includes a plurality of slips 31-36 made of soluble alloy materials, preferably 6 slips, and the soluble slip group 3 is surrounded by the cone in a relatively movable manner. The outer surface of the cylinder member 1 and the inner surface of the soluble slip group 3 are inner cone surfaces that match the shape of the outer surface of the conical cylinder member 1 , and the outer surface is a cylindrical surface coaxial with the central connecting shaft 2 .

A groove 30 matching the coarse thread 11 on the outer surface of the conical cylinder member 1 is formed on the inner surface of the soluble slip group 3 , or corresponding to the groove 11 on the outer surface of the conical cylinder member 1 . The matching coarse thread 30 enables the soluble slip group 3 to perform a helical expansion movement relative to the conical cylindrical part 1 on the outer surface of the conical cylindrical part 1;

The annular tailstock 4 is made of soluble alloy material, and a screw hole 41 is formed in the center of the annular tailstock 4 to match with the threaded section 21 at the end of the central connecting shaft 2. The annular tailstock 4 One side of the soluble slip group 3 abuts against the side of the soluble slip group 3, and under the pulling action of the central connecting shaft 2, the soluble slip group 3 can be pushed along the outer surface of the cone member 1 relative to the cone member 1 Do a spiral expansion exercise.

It also includes a snap ring 6. The through hole in the center of the snap ring 6 has an inner thread, which is used to be sleeved on the central connecting shaft 2 through a threaded connection. In order to limit the position of the conical cylinder member 1, the conical cylinder member 1 and the soluble slip group 3 are positioned in the position through the snap ring 6 and the annular tailstock 4 connected with the threaded section 21 at the end of the central connecting shaft 2. between the snap ring 6 and the annular tailstock 4 .

The surface of each slip is provided with a ceramic jaw structure 311 with parallel grains.

In the process of carrying out the fracturing experiment, the first assembly is carried out, and the snap ring 6, the cone piece 1, the sealing ring 5, the soluble slip group 3, and the annular tailstock 4 are threaded or screwed on the central connecting shaft 2 in turn. , and wrap the slip group through the sealing ring 5 to ensure that the components will not fall loosely during the process of conveying the bridge plug to the downhole. Secondly, the setting tool and the bridge plug are transported along the shaft to the predetermined position to be sealed by the transport tool. Then, use the setting tool to press against the end face of the cone member 1, so that the cone member 1 is fixed, and the central connecting shaft 2 is pulled uphole; driven by the central connecting shaft 2, the screw is connected in the center The annular tailstock 4 at the end of the connecting shaft 2 moves synchronously in the axial direction, thereby pushing the slip group 3 and the sealing ring 5 to move synchronously along the axial direction of the central connecting shaft 2 to the uphole direction; thus making the slips The relative displacement occurs between the group 3, the sealing ring 5 and the fixed cone 1. As shown in FIG. 6 , the slip group 3 and the sealing ring 5 are expanded by the extrusion of the outer cone surface of the cone 1, so that the ceramic claw structure 311 on the surface of the slip 3 can be embedded and grip the well wall. The bridge plug is firmly fixed in the well, prevents the bridge plug from sliding in the well, and forms a certain seal at the same time. In addition, the sealing ring 5 made of soluble rubber forms a tight seal with the well wall due to extrusion and expansion, so that the fracturing experiment can be carried out smoothly. Finally, as the pulling force of the central connecting shaft 2 increases, the threaded section 21 at the end of the central connecting shaft 2 is released from the screw hole 41 of the annular tailstock 4, and the setting tool and the central connecting shaft 2 are withdrawn from the ground. Thus, the setting construction is completed, and the fracturing experiment can be carried out. After the fracturing experiment is completed, the bridge plug is dissolved by the solvent to facilitate oil and gas extraction operations.

In the present invention, in order to prevent the axial separation between the slips 3 and the cone-shaped member 1 during the fracturing experiment, coarse threads and grooves are arranged on the contact surface of the slip group 3 and the cone-shaped member 1 cooperation. When the slip group 3 moves relative to the surface of the conical cylinder member 1 in the axial direction, due to the cooperation of the coarse thread and the groove, the slip group 3 and the surface of the conical cylinder member 1 undergo circumferential relative rotational movement, so that the The coarse thread 30 on the inner surface of the slip 3 takes the groove 11 on the outer surface of the conical cylinder member as a track and performs a spiral motion. Axial locking is achieved between the slip group 3 and the conical cylinder 1 through the mating relationship between the coarse thread and the groove, thereby enhancing the bonding strength of the slips and the conical cylinder and preventing axial disengagement. Compared with the prior art technology in which the locking connector is additionally provided, the number of components is saved, the processing and assembly are simple, the integrity is better and the strength is higher.

As shown in FIG. 4 , it is a three-dimensional outline view of the conical cylinder member 1 of the present invention.

The arrangement of the grooves 11 on the outer surface of the cone member 1 can be more clearly understood. The groove 11 is matched with the coarse thread 30 on the inner surface of the slip 3 . Since the groove 11 has a variable diameter on the cone surface of the cone member 1, in the process of changing the direction from the cone top to the cone bottom, the diameter of the curve formed by the groove increases with the increase of the diameter of the cone. Since the curvature of the groove has changed, there may be a problem that the groove does not match the rough thread on the inner surface of the slip.

In order to solve this problem, when the groove 11 on the surface of the cone member 1 adopts a fixed pitch, the diameter of the groove will increase from small to large, and the radian will gradually increase. At this time, in order to match the radian of the groove 11 of the cone 1 when the slip 3 is in the locked position, the radian of the inner surface of the slip 3 is set to a large diameter, so as not to affect the rough thread 30 in the groove. Orbital movement in 11. In addition, the pitch of the groove 11 on the surface of the cone body 1 can also be designed as a variable pitch, that is, the pitch is larger when it is close to the top of the cone, and the pitch is smaller when it is close to the bottom of the cone, so as to ensure the groove. 11 has the same curvature on the surface of the cone.

The setting of the pitch of the groove 11 and the coarse thread 30 is very important. When the pitch is set to a small value, possibly due to the small thread angle, the reaction force of the tapered piece to the slips in the circumferential direction will be insufficient, and the slips 3 cannot rotate along the groove 11, resulting in the gap between the groove 11 and the coarse thread 30. tripping, so that the locking effect between the slip group 3 and the cone 1 cannot be achieved. When the pitch is set large, although the slips 3 are easy to perform helical movement along the groove 11, the occlusal force between the groove 11 and the coarse thread 30 is small, and the axial locking effect is weak.

After testing, in the present invention, the grooves 11 on the surface of the cone member 1 are set to 6 involutes, which match the number of slips in the slip group 3, and each involute is on the surface of the cone member 1. The rotation angle is one revolution. It can solve the above contradictions of inability to rotate and weak locking effect.

In another embodiment, the grooves 11 on the surface of the conical cylindrical member 1 in the above solution can be replaced by coarse threads.

As shown in FIG. 5 , the slip 3 is usually provided with only one row of coarse threads 31 on its inner surface. When multiple rows of coarse threads 31 are provided, due to the problem of diameter reduction during relative movement, it is difficult for both the slips 3 and the cone 1 to slide relative to each other, and the problem of jamming, tripping, and inability to match the buckle occurs. When the surface of the conical cylinder member 1 is provided with coarse threads, the inner surface of the slips 3 is correspondingly provided with grooves.

As shown in FIG. 3A and FIG. 3C , a radial sliding groove 42 is recessed on the side where the annular tailstock 4 abuts against the slip group 3 , and the matching side of the slips 3 is along the radial direction. Ribs 312-362 are protrudingly provided with the sliding groove 42, so that the slip group 3 can slide along the sliding groove 42 during the radial expansion process, so as to prevent the slip group from being pushed by the annular tailstock. Circumferential sliding occurs between them, avoiding squeezing and interference between multiple slips 3 . At the same time, when the slip group 3 expands and rotates along the helical line, it can drive the annular tailstock 4 to rotate in the circumferential direction, so that the annular tailstock 4 rotates relative to the threaded central connecting shaft 2 . As a result, the connection strength between the central connecting shaft 2 and the annular tailstock 4 is gradually reduced, which facilitates the tripping at the end of setting.

Example 2

As described above, the setting of the pitch of the groove 11 and the coarse thread 30 is very important. When the pitch is set to a small value, possibly due to the small thread angle, the reaction force of the tapered piece to the slips in the circumferential direction will be insufficient, and the slips 3 cannot rotate along the groove 11, resulting in the gap between the groove 11 and the coarse thread 30. tripping, so that the locking effect between the slip group 3 and the cone 1 cannot be achieved. When the pitch is set large, although the slips 3 are easy to perform helical movement along the groove 11, the occlusal force between the groove 11 and the coarse thread 30 is small, and the axial locking effect is weak.

In addition, since the groove 11 has a variable diameter on the cone surface of the cone member 1, the diameter of the curve formed by the groove increases with the increase of the diameter of the cone in the process of changing the direction from the top of the cone to the bottom of the cone. If the groove is large, the curvature of the groove is changed, and there may be a problem that the groove does not match the rough thread on the inner surface of the slip.

In order to solve the problem of selecting the pitch between the groove and the coarse thread, as shown in FIG. 7 , in this embodiment, an experimental device for bridge plug setting is also provided. In the technical solution in Embodiment 2, an experimental device in which the displacement sensor 8 cooperates with the tension sensor 7 is adopted. So as to facilitate the pitch selection test.

On the inner surface of one end of the slip group 3 close to the annular tailstock 4, a displacement sensor 8 is arranged to detect whether the rotational movement in the circumferential direction between the slip group 3 and the cone member 1 occurs and to detect The relative displacement in the axial direction between the cone members 1; and between the annular tailstock 4 and the slip group 3, a pressure sensor 7 is arranged to detect the pressing force of the annular tailstock on the slip group. The sensing signals of the displacement sensor 8 and the pressure sensor 7 are transmitted to the ground for monitoring through the signal transmission line provided in the central connecting shaft 2 .

For the schemes with different pitches, several experiments are carried out using the experimental device, so that the preferred pitch scheme can be selected.

The specific experimental method can be:

A recording device is installed on the ground to receive and record the relative rotational displacement signal between the cone 1 and the slip group 3 in the circumferential direction sent by the displacement sensor 8, and the difference between the cone 1 and the slip group 3. The relative rotational displacement signal in the axial direction and the pressure signal between the annular tailstock 4 and the slip group 3 sensed by the pressure sensor 7, the pitch, tooth shape, There are many possible combinations of tooth height, groove shape, and groove depth. For each combination, a downhole setting experiment is performed separately. For each group of experiments, according to the relative rotational displacement signal and pressure signal, determine the ring shape Whether there is a circumferential rotation between the tailstock 4 and the slip group 3, record the magnitude of the pressure and tension required when the circumferential rotation starts, determine whether there is a tripping between the coarse thread and the groove, and record the center The pressure when the connecting shaft 2 is tripped from the annular tailstock 4, through multiple sets of experiments, select the optimal combination of coarse thread and groove pitch, tooth shape, tooth height, groove shape, and groove depth .

As described in Table 1, the pitches of the coarse threads and grooves can be set to 10cm, 15cm, 20cm, 25cm, etc., respectively, and the shapes of the teeth of the coarse threads and grooves can be set to cones, rectangles, and semicircles, respectively. The depth of the teeth can be set to 0.8cm, 1cm, 1.2cm, 1.5cm, etc. respectively, and the depth of the grooves can be set to 0.6, 0.8cm, 1cm, 1.2cm, etc. respectively.

Arrange among the optional parameters of pitch, shape, depth to experiment with every possible combination. And according to the recorded sensor signal, choose the optimal solution that the slip group will not slip off the surface of the cone and can be tightly stuck on the well wall after the setting is completed.

Table 1

The above description is only a preferred embodiment of the present application and an illustration of the applied technical principles. Those skilled in the art should understand that the scope of disclosure involved in this application is not limited to the technical solutions formed by the specific combination of the above-mentioned technical features, and should also cover the above-mentioned technical features or Other technical solutions formed by any combination of its equivalent features. For example, a technical solution is formed by replacing the above-mentioned features with the technical features disclosed in this application (but not limited to) with similar functions.

Claims (10)

1. a soluble bridge plug, is characterized in that, comprises: A cone-shaped member (1) is made of a soluble alloy material, an axial channel (10) is provided inside the cone-shaped member (1), an outer surface of the cone-shaped member (1) is a cone surface, and The outer surface is provided with a protruding coarse thread (11), or a groove (11) matched with the coarse thread; a central connecting shaft (2), which can be axially slidably inserted into the channel (10) inside the conical cylindrical member, and the end surface of the central connecting shaft (2) is provided with a threaded segment (21); A soluble slip group (3), comprising a plurality of slips (31-36) made of soluble alloy materials, the soluble slip group (3) is surrounded by the cone in a relatively movable manner The outer surface of the part (1), the inner surface of the soluble slip group (3) is an inner cone surface that matches the shape of the outer surface of the cone-shaped part (1), and the outer surface is the central connecting shaft (2) coaxial cylindrical surface; A groove (30) matching the coarse thread (11) on the outer surface of the conical cylinder member (1) is formed on the inner surface of the soluble slip group (3), or is matched with the conical cylinder member (1). 1) A coarse thread (30) matched with the groove (11) on the outer surface, so that the soluble slip group (3) can be relative to the cone (1) on the outer surface of the cone (1). 1) Do the spiral expansion movement; An annular tailstock (4) is made of soluble alloy material, and a screw hole is formed in the center of the annular tailstock (4) to match the threaded section (21) at the end of the central connecting shaft (2). (41), one side of the annular tailstock (4) abuts one side of the soluble slip group (3), and can push the soluble slip under the pulling action of the central connecting shaft (2) The tile group (3) performs a helical expansion movement relative to the conical cylindrical part (1) along the outer surface of the conical cylindrical part (1). 2. A soluble bridge plug according to claim 1, characterized in that, further comprising a sealing ring (5) made of soluble rubber, abutting against the annular tail of the soluble slip group (3) away from At one end of the seat (4), the sealing ring (5) can move and expand along the outer surface of the conical cylinder member (1) when being pushed by the slip group (3) that performs a spiral expansion motion. 3. A dissolvable bridge plug according to claim 1, characterized in that, further comprising a snap ring (6), with an internal thread at the through hole in the center of the snap ring (6), for sleeve setting through a threaded connection On the central connecting shaft (2), the outer diameter of the snap ring (6) is larger than the outer diameter of the inner channel (10) of the conical cylinder member (1), so as to limit the position of the conical cylinder member (1). (6) and the annular tailstock (4) connected with the threaded section (21) at the end of the central connecting shaft (2), the cone (1) and the soluble slip group (3) are positioned on the snap ring ( 6) and the annular tailstock (4). 4. The soluble bridge plug according to claim 1, characterized in that the outer surface of the slips (31-36) has a pawl structure (311-361) with parallel lines. 5. A soluble bridge plug as claimed in claim 1, characterized in that, the pitch of the coarse thread (11) protruding on the outer surface of the conical cylinder member (1) or the groove matched with the coarse thread is set to Variable pitch, or fixed pitch; When the pitch is set to be a variable pitch, the coarse thread or groove has a larger pitch on the side of the conical cylinder member (1) close to the top of the cone, and a smaller pitch on the side close to the bottom of the cone; When the pitch is set as a fixed pitch, the radian of the inner surface of the slip group (3) is set to match the radian of the outer surface of the cone-shaped member (1) near the bottom of the cone. 6. The soluble bridge plug according to claim 1, characterized in that, only one row of coarse threads (30) or grooves (30) is provided on the inner surface of the slips (31-36). 7. A soluble bridge plug according to claim 1, characterized in that, on the side where the annular tailstock (4) abuts against the slip group (3), there is also a concave radial sliding In the groove (42), ribs (312-362) which are matched with the sliding groove (42) are protruded along the radial direction on the side where the slips are matched, so as to make the slip group (3) expand in the radial direction In the middle, it can slide along the sliding groove (42). 8. The soluble bridge plug according to claim 1, wherein the slip group (3) comprises 6 slips, the shape of the groove or the coarse thread on the surface of the cone (1) There are 6 involutes, and the rotation angle of each involute on the surface of the cone (1) is one circle. 9. An experimental device for the soluble bridge plug described in any one of claims 1-8, on the inner surface of one end of the slip group (3) close to the annular tailstock (4), a displacement sensor (8) is provided. ) to detect whether the rotational movement in the circumferential direction between the slip group (3) and the cone (1) occurs, and to detect the relative axial direction between the slip group (3) and the cone (1) And between the annular tailstock (4) and the slip group (3), a pressure sensor (7) is arranged to detect the pressing force of the annular tailstock (4) on the slip group (3), and the displacement sensor ( 8) and the sensing signal of the pressure sensor (7) are transmitted to the ground for monitoring through the signal transmission line set in the central connecting shaft (2). 10. An experimental method for the experimental device as claimed in claim 9, characterized in that a recording device is provided on the ground to receive and record the cone (1) sent by the displacement sensor (8) The relative rotational displacement signal in the circumferential direction with the slip group (3), the relative rotational displacement signal in the axial direction between the cone (1) and the slip group (3), and the pressure sensor ( 7) The sensed pressure signal between the annular tailstock (4) and the slip group (3), set for the pitch, tooth shape, tooth height, groove shape, and groove depth of the coarse thread and groove There are many possible combinations, and for each combination, downhole setting experiments are carried out respectively. For each group of experiments, according to the relative rotational displacement signal and the pressure signal, determine the annular tailstock (4) and the slip group (3). ), record the magnitude of the pressure and tension required when the circumferential rotation starts, determine whether there is a tripping between the coarse thread and the groove, and record the central connecting shaft (2) from the ring According to the pressure at the time of tripping in the tailstock (4), through multiple sets of experiments, the optimal combination of the pitch, tooth shape, tooth height, groove shape and groove depth of the coarse thread and groove is selected.

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