Small-diameter soluble bridge plug

Abstract

The invention relates to the field of oil and gas drilling, and provides a small-diameter soluble bridge plug which comprises a push sleeve, a connecting sleeve part, a sawtooth part, a positioning part and a releasing part, the sawtooth part, the positioning part and the releasing part are formed by splicing at least two parts, the push sleeve is detachably connected with the connecting sleeve part, and the inner wall of one end of the sawtooth part is movably connected with sawteeth on the outer wall of the connecting sleeve part. The outer diameter of the end, close to the sawtooth part, of the connecting sleeve part is gradually decreased, the outer wall of the other end of the sawtooth part is movably connected with sawteeth of the inner wall of the positioning part, the outer diameter of the end, matched with the positioning part, of the sawtooth part is gradually decreased, the outer diameter of the end, matched with the releasing part, of the positioning part is gradually increased, and the inner wall of the other end of the positioning part is slidably connected with the outer wall of the releasing part. And the two positioning parts are separated under the pushing of all the parts and move to abut against the inner wall of the oil casing. The two parts of the positioning part are pushed to move to abut against the inner wall of the oil casing pipe, enough anchoring force is provided for plugging the oil pipe sleeve, uniform anchoring of the positioning part is ensured, unbalance loading is avoided, and the pressure bearing capacity and stability of the anchoring structure are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas drilling, and in particular relates to a small-diameter soluble bridge plug. Background Art

[0002] During the large-scale development of deep shale oil and gas, horizontal well casing deformation occurs frequently. In recent years, the incidence and severity of well casing deformation have shown an upward trend, which seriously affects the timeliness and reservoir transformation effect of large-scale fracturing of shale oil and gas horizontal wells. Specifically, the bridge plug is a necessary tool for multi-stage fracturing. During the staged fracturing construction, the bottom casing is sealed by setting the bridge plug at a predetermined position in the wellbore to ensure the effective construction of staged fracturing of oil and gas wells. Once the horizontal well casing is severely deformed, a small-diameter or ultra-small-diameter soluble bridge plug is required to pass through the severely deformed well section and then be lowered to the predetermined position for sealing. This can greatly alleviate the construction requirements of severe deformation of the well casing and ensure the staged fracturing operation of the severely deformed well.

[0003] However, when fracturing a well with severe casing deformation, a small-diameter soluble bridge plug is used to plug the casing wellbore. Due to the limited size of the bridge plug (especially the soluble bridge plug with a diameter of less than or equal to 70 mm), the diameter difference between the bridge plug and the inner diameter of the casing is large, resulting in an increase in the annular space, a longer slip engagement distance, and a higher expansion rate, making it difficult to provide sufficient anchoring force and stable sealing pressure bearing capacity, which greatly increases the design difficulty of the soluble bridge plug. The conventional soluble bridge plug structure has been unable to provide sufficient anchoring force and sealing pressure bearing capacity. Summary of the invention

[0004] In view of the above problems, the present invention provides a small-diameter soluble bridge plug for being installed in an oil casing to seal the inner cavity of the oil casing, comprising: a push sleeve and a connecting sleeve portion, and a serrated portion, a positioning portion and a release portion, all of which are formed by splicing at least two parts, the push sleeve and the connecting sleeve portion are detachably connected, the inner wall of one end of the serrated portion and the outer wall of the connecting sleeve portion are serrated and movably connected, and the outer diameter of one end of the connecting sleeve portion close to the serrated portion gradually decreases, the outer wall of the other end of the serrated portion and the inner wall of the positioning portion are serrated and movably connected, the outer diameters of one end of the serrated portion and the positioning portion that cooperate with each other are gradually reduced, the outer diameters of one end of the positioning portion and the release portion that cooperate with each other are gradually increased, and the inner wall of the other end of the positioning portion is slidably connected to the outer wall of the release portion, so that the two parts of the positioning portions are separated and moved to abut against the inner wall of the oil casing under the push of each component.

[0005] Optionally, the positioning portion includes at least a first positioning block and a second positioning block, the first positioning block and the second positioning block are spliced ​​to form an axial hole to cooperate with the setting shaft, and the first positioning block and the second positioning block are provided with saw teeth on the inner wall of the same end to cooperate with the protrusion on the outer wall of the sawtooth portion, and a protrusion is also provided on the inner wall of the same end to cooperate with the groove on the outer wall of the release portion.

[0006] Optionally, the positioning portion further includes a plurality of positioning teeth and a plurality of first rubber rings, a plurality of cylindrical holes and rectangular annular grooves are provided on the outer walls of the first positioning block and the second positioning block, the first rubber ring is provided in the rectangular annular groove, the axis of the cylindrical hole is not perpendicular to the axial line of the first positioning block and the second positioning block, the positioning teeth are provided in the cylindrical holes, and the positioning teeth are anchored to the inner wall of the oil casing.

[0007] Optionally, the serrated portion includes at least a first serrated block and a second serrated block, and a first hoop and a second rubber ring. The first serrated block and the second serrated block are spliced ​​to form an axial hole to cooperate with the setting shaft. The serrated protrusions on the inner and outer walls at both ends of the first serrated block and the second serrated block respectively cooperate with the rectangular protrusions on the inner and outer walls of the positioning portion and the connecting portion. The first hoop is sleeved on one end of the first serrated block and the second serrated block, and close to one side of the connecting portion. A first limiting groove is provided on the first hoop sleeve, and the second rubber ring is placed in the first limiting groove.

[0008] Optionally, the release part includes at least a first sliding block and a second sliding block, a second hoop and a third rubber ring, the first sliding block and the second sliding block are spliced ​​to form an axial hole to cooperate with the setting shaft, the groove on the inner wall of one end of the first sliding block and the second sliding block cooperates with the protrusion on the outer wall of the positioning part, the second hoop is sleeved on the other end of the first sliding block and the second sliding block, and a second limiting groove is provided on the second hoop, and the third rubber ring is placed in the second limiting groove.

[0009] Optionally, the release part also includes a release ring, which is provided with an axial hole to cooperate with the sealing shaft, and a sliding groove on the outer wall of one end of the release ring cooperates with the protruding blocks on the inner walls of the first sliding block and the second sliding block, and the second hoop is located near one end of the release ring.

[0010] Optionally, the connecting sleeve portion includes a sealing assembly and a locking sleeve, the push sleeve and the sealing assembly are detachably connected, one end of the sealing assembly and the locking sleeve are threaded, and the other end of the locking sleeve is movably connected to the teeth of the serrated portion.

[0011] Optionally, the outer diameter of one end of the locking sleeve that cooperates with the serrated portion gradually decreases, and the serrated thread on the outer wall of the locking sleeve cooperates with the protrusion on the inner wall of the serrated portion.

[0012] Optionally, the sealing assembly includes a connecting shaft, a setting seal shaft, a throw-away glove and a center sleeve, the connecting shaft is arranged in the push sleeve, the connecting shaft and the setting seal shaft are threadedly connected, one end of the throw-away glove is stuck on a step in the push sleeve, and the throw-away glove and the push sleeve are detachably connected, the other end of the throw-away glove is connected to one end of the center sleeve, and the other end of the center sleeve is threadedly connected to the locking sleeve, the setting seal shaft passes through the throw-away glove, the center sleeve, the serrated portion and the positioning portion in sequence and is connected to the throw-away glove.

[0013] Optionally, the sealing assembly further comprises a long pin, and corresponding pin holes are provided on the outer walls of the throw-away glove and the push sleeve, and the long pin passes through the corresponding pin holes to connect the throw-away glove and the push sleeve.

[0014] The small-diameter soluble bridge plug of the present invention pushes the push sleeve to move the connecting sleeve portion, and the connecting sleeve portion can be movably connected with the sawtooth portion. When the connecting sleeve portion moves, the outer diameter of one end of the connecting sleeve portion close to the sawtooth portion gradually decreases. As the connecting sleeve portion enters the inner wall of the sawtooth portion and pushes the sawtooth portion to move in the axial direction, the two parts of the sawtooth portion gradually separate, and the sawtooth portion also pushes the positioning portion to move in the axial direction. Because the outer diameters of one end of the sawtooth portion and the positioning portion that cooperate with each other are gradually reduced, the two parts of the sawtooth portion move on the inner walls of the two parts of the positioning portion respectively, and the outer diameters of one end of the positioning portion and the release portion that cooperate with each other are gradually increased, so that the other end of the positioning portion slides on the release portion, so that the two parts of the positioning portion gradually separate, and finally the two parts of the positioning portion move respectively to abut against the inner wall of the oil casing, thereby providing sufficient anchoring force for plugging the inner cavity of the oil casing, and providing a stable sealing pressure for the plugged oil casing, so that the design of the soluble bridge plug is reduced.

[0015] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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.

[0017] Figure 1a A schematic diagram of a portion of a small-diameter soluble bridge plug in an embodiment of the present invention is shown;

[0018] Figure 1b Another schematic diagram of a small-diameter soluble bridge plug according to an embodiment of the present invention is shown;

[0019] Figure 2 It shows a schematic diagram of installation and positioning of a small-diameter soluble bridge plug in an embodiment of the present invention;

[0020] Figure 3 A schematic diagram of a small-diameter soluble bridge plug locking sleeve in an embodiment of the present invention is shown;

[0021] Figure 4 A schematic diagram of a serrated portion of a small-diameter soluble bridge plug in an embodiment of the present invention is shown;

[0022] Figure 5 A schematic diagram of a positioning portion of a small-diameter soluble bridge plug in an embodiment of the present invention is shown;

[0023] Figure 6 A schematic diagram of a first sliding block of a small-diameter soluble bridge plug in an embodiment of the present invention is shown;

[0024] Figure 7 A schematic diagram of a small-diameter soluble bridge plug discarding ring in an embodiment of the present invention is shown.

[0025] In the figure, 1, push sleeve; 2, connecting sleeve part; 3, serration part; 4, positioning part; 5, hand release part; 22, setting shaft; 20, sealing assembly; 25, locking sleeve; 21, connecting shaft; 23, hand release ring; 24, center sleeve; 26, long pin; 31, first serration block; 32, second serration block; 33, first hoop; 34, second rubber ring; 35, protrusion; 41, first positioning block; 42, second positioning block; 43, positioning teeth; 44, first rubber ring; 46, cylindrical hole; 45, rectangular ring groove; 51, first sliding block; 52, second sliding block; 53, hand release ring; 54, second hoop; 55, groove; 48, protrusion; 531, slide groove; 56, protrusion block. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0027] like Figure 1a and 1b As shown, the present invention provides a small-diameter soluble bridge plug, which is used to be installed in an oil casing to seal the inner cavity of the oil casing, and comprises: a push sleeve 1 and a connecting sleeve part 2, and a serrated part 3, a positioning part 4 and a release part 5, all of which are formed by splicing at least two parts. The push sleeve 1 and the connecting sleeve part 2 are detachably connected, the inner wall of one end of the serrated part 3 and the outer wall of the connecting sleeve part 2 are serrated and movably connected, and the outer diameter of one end of the connecting sleeve part 2 close to the serrated part 3 gradually decreases, and the outer wall of the other end of the serrated part 3 and the inner wall of the positioning part 4 are serrated and movably connected, the outer diameter of one end of the serrated part 3 and the positioning part 4 that cooperate with each other is gradually reduced, and the outer diameter of one end of the positioning part 4 and the release part 5 that cooperate with each other is gradually increased, and the inner wall of the other end of the positioning part 4 is slidably connected with the outer wall of the release part 5, so that the two parts of the positioning part 4 are separated and moved to abut against the inner wall of the oil casing under the push of each component. Therefore, sufficient anchoring force can be provided for plugging the inner cavity of the oil casing, and stable sealing pressure is provided for the plugged oil casing, so that the design of the soluble bridge plug is reduced. It should be noted that the push sleeve 1 and the connecting sleeve part 2 are detachably connected, that is, when a certain thrust is reached, the push sleeve 1 and the connecting sleeve part 2 are no longer connected and can move relative to each other, that is, the push sleeve 1 and the throw-away glove 23 on the connecting sleeve part 2 are no longer connected together, the purpose is to enable the push sleeve 1 to push the sealing component on the outer wall of the throw-away glove 23 to expand the sealing component and finally abut against the inner wall of the oil casing, thereby sealing the oil casing. Of course, before the positioning part 4 moves to the positioning position of the oil casing, the push sleeve 1 and the connecting sleeve part 2 will not separate. When the two parts of the positioning part 4 move respectively to abut against the inner wall of the oil casing, the positioning part 4 is positioned, and under the action of the thrust, the push sleeve 1 and the connecting sleeve part 2 are no longer connected together, and finally it can also be achieved that the sealing component on the outer wall of the throw-away glove 23 is pushed to expand the sealing component and finally abut against the inner wall of the oil casing, thereby achieving sealing of the oil casing. Optionally, the push sleeve 1 is a cylindrical structure, one end of which is provided with a connecting thread in the inner cavity, connected to the downhole adapter, and the other end of which is in the form of a stepped hole, with the smallest diameter in the middle. A threaded through hole is provided on the circumference of the middle step position, and one end of the connecting sleeve part 2 is in the stepped hole of the push sleeve 1 and is stuck by the step, so as not to fall out of the push sleeve 1. In fact, the outer wall of the connecting sleeve part 2 can slide in the push sleeve 1, which requires that the push sleeve 1 and the connecting sleeve part 2 are no longer connected together.

[0028] like Figure 1bAs shown, in one embodiment, the positioning portion 4 includes at least one first positioning block 41 and a second positioning block 42, and the first positioning block 41 and the second positioning block 42 are spliced ​​to form an axial hole to cooperate with the setting shaft 22. The first positioning block 41 and the second positioning block 42 are provided with saw teeth on the inner wall of the same end to cooperate with the protrusion 35 on the outer wall of the sawtooth portion 3, so that the entire positioning portion 4 can move on the outer wall of the sawtooth portion 3, and the sawtooth portion 3 can only move toward the positioning portion 4, and finally the first positioning block 41 and the second positioning block 42 are separated. In addition, a protrusion 48 is provided on the inner wall of the same end to cooperate with the groove 55 on the outer wall of the release portion 5. At this time, the other ends of the first positioning block 41 and the second positioning block 42 can slide on the release portion 5, as shown in FIG. Figure 2 As shown, the first positioning block 41 and the second positioning block 42 are finally pushed to move to abut against the inner wall of the oil casing to achieve the positioning of the positioning part 4. Optionally, the upper and lower surfaces corresponding to the first positioning block 41 and the second positioning block 42 are arc-shaped, and the inner wall of one end of the first positioning block 41 and the second positioning block 42 is a flat inclined surface, and an inner sawtooth-shaped protrusion is provided on the flat inclined surface, and the sawtooth-shaped protrusion cooperates with the upper protrusion 35 of the sawtooth part 3. The other ends of the first positioning block 41 and the second positioning block 42 are also inclined surface structures, and a sawtooth-shaped protrusion is provided on the inclined surface, so that it can cooperate with the groove 55 on the outer wall of the hand-release part 5 to achieve sliding.

[0029] like Figure 5 As shown, in one embodiment, the positioning part 4 further includes a plurality of positioning teeth 43 and a plurality of first rubber rings 44. A plurality of cylindrical holes 46 and rectangular annular grooves 45 are provided on the outer walls of the first positioning block 41 and the second positioning block 42. The first rubber ring 44 is provided in the rectangular annular groove 45. The axis of the cylindrical hole 46 is not perpendicular to the axial line of the first positioning block 41 and the second positioning block 42. The positioning teeth 43 are provided in the cylindrical hole 46, and the positioning teeth 43 are anchored on the inner wall of the oil casing. Optionally, n cylindrical holes 46 arranged in a linear shape are processed on the first positioning block 41 and the second positioning block 42. It should be noted that the axis of the cylindrical hole 46 is not perpendicular to the axial line of the first positioning block 41 and the second positioning block 42, so that the positioning teeth 43 installed on the cylindrical hole 46 are in an inclined state, so that when positioning, the inclined positioning teeth 43 cooperate with the positioning holes on the inner wall of the oil casing to achieve positioning. The first rubber ring 44 is also elastic, so even if the first positioning block 41 and the second positioning block 42 are separated, the first rubber ring 44 will always be sleeved in the rectangular annular groove 45. When the first positioning block 41 and the second positioning block 42 abut against the inner wall of the oil casing, the first rubber ring 44 can also seal the cavity of the oil casing.

[0030] like Figure 2 and Figure 4As shown, in one embodiment, the sawtooth portion 3 includes at least a first sawtooth block 31 and a second sawtooth block 32, as well as a first hoop 33 and a second rubber ring 34. The first sawtooth block 31 and the second sawtooth block 32 are spliced ​​to form an axial hole to cooperate with the setting shaft 22. The protrusions 35 on the inner and outer walls of both ends of the first sawtooth block 31 and the second sawtooth block 32 are respectively matched with the rectangular protrusions on the inner and outer walls of the positioning portion 4 and the sleeve portion 2, so that the entire sawtooth portion 3 can move on the inner wall of the positioning portion 4, and only The sleeve part 2 can be moved toward the serrated part 3, and the serrated part 3 can be moved toward the positioning part 4, so that the first serrated block 31 and the second serrated block 32 can be separated and can move on the first positioning block 41 and the second positioning block 42, and the first positioning block 41 and the second positioning block 42 are separated at the same time. The first hoop 33 is sleeved on one end of the first serrated block 31 and the second serrated block 32, and is close to the side of the sleeve part 2. A first limiting groove is provided on the first hoop 33, and the second rubber ring 34 is sleeved in the first limiting groove. It should be noted that the first hoop 33 is annular and will automatically break when the thrust reaches a certain level. Before breaking, the whole set of bridge plugs is in the initial state, which is convenient for pushing each component to the target position in the oil casing. When the first hoop 33 breaks, the whole bridge plug starts to move relative to each other under the action of the push sleeve 1, that is, it can push the serrated part 3 and the positioning part 4 to move relative to each other, and finally realize the sealing positioning of the oil casing.

[0031] like Figure 2 As shown, in one embodiment, the release part 5 includes at least a first sliding block 51 and a second sliding block 52, a second hoop 54 and a third rubber ring. The first sliding block 51 and the second sliding block 52 are spliced ​​to form an axial hole to cooperate with the setting shaft 22. The groove 55 on the inner wall of one end of the first sliding block 51 and the second sliding block 52 cooperates with the protrusion 48 on the outer wall of the positioning part 4. The second hoop 54 is sleeved on the other end of the first sliding block 51 and the second sliding block 52, and a second limiting groove is provided on the second hoop 54. The third rubber ring is placed in the second limiting groove. Optionally, as shown in FIG. Figure 6 As shown, the outer walls of one end of the first sliding block 51 and the second sliding block 52 are both planar structures, and a rectangular groove 55 is provided on each plane. The rectangular groove 55 cooperates with the rectangular protrusion of the positioning portion 4. The two side surfaces of the other ends of the first sliding block 51 and the second sliding block 52 are also at a certain angle, which facilitates the second hoop 54 to put the first sliding block 51 and the second sliding block 52. In addition, the functions of the second hoop 54 and the third rubber ring are the same as those of the corresponding first hoop 33 and the second rubber ring 34, and are not described here.

[0032] like Figure 7As shown, in one embodiment, the release part 5 further includes a release ring 53, in which an axial hole is provided to cooperate with the setting shaft 22, a slide groove 531 provided on the outer wall of one end of the release ring 53 cooperates with a protrusion 56 provided on the inner wall of the first sliding block 51 and the second sliding block 52, and the second hoop 54 is located at one end close to the release ring 53. Optionally, the release part 5 is conical, and a rectangular groove 55 is provided on the plane of the release ring 53, the length of the rectangular groove 55 is less than the length of the cone surface, and the rectangular groove 55 is slidably matched with the protrusion 56 provided on the inner wall of the first sliding block 51 and the second sliding block 52, wherein the axial hole has an internal thread structure, and the magnitude of the bridge plug release force is determined by the internal thread, and the magnitude of the release force is determined by the material of the release ring 53, the major diameter of the thread and the number of turns.

[0033] like Figure 1a and 1b As shown, in one embodiment, the sleeve portion 2 includes a sealing assembly 20 and a locking sleeve 25, the push sleeve 1 and the sealing assembly 20 are detachably connected, one end of the sealing assembly 20 and the locking sleeve 25 are screwed, and the other end of the locking sleeve 25 is movably connected to the serrations of the serration portion 3. The push sleeve 1 and the sealing assembly 20 are detachably connected, that is, when a certain thrust is reached, the push sleeve 1 and the sealing assembly 20 are no longer connected and can move relative to each other, that is, the push sleeve 1 and the throw-away glove 23 on the sealing assembly 20 are no longer connected together, the purpose is to enable the push sleeve 1 to push the sealing component on the outer wall of the throw-away glove 23 so that the sealing component expands and finally abuts against the inner wall of the oil casing to achieve sealing of the oil casing. Of course, when the positioning portion 4 does not move to the positioning position of the oil casing, the push sleeve 1 and the sealing assembly 20 will not separate. The inner hole of the locking sleeve 25 is a stepped hole, and the first stepped hole is an internal connecting thread, which is convenient for cooperation with the center sleeve 24 on the sealing assembly 20. The right end of the outer wall of the locking sleeve 25 is evenly provided with inclined surfaces, and the inclined surfaces are provided with external protrusions 35, which are convenient for cooperation with the serrated portion 3.

[0034] like Figure 3 As shown, in one embodiment, the outer diameter of one end of the locking sleeve 25 that matches the serrated portion 3 gradually decreases, and the sawtooth-shaped thread on the outer wall of the locking sleeve 25 matches the protrusion on the inner wall of the serrated portion 3. Thus, the locking sleeve 25 can move on the inner wall of the serrated portion 3. As the locking sleeve 25 moves on the inner wall of the serrated portion 3, the two parts of the serrated portion 3 are gradually divided into blocks.

[0035] like Figure 1a and 1bAs shown, in one embodiment, the sealing assembly 20 includes a connecting shaft 21, a setting shaft 22, a throwing glove 23 and a center sleeve 24, the connecting shaft 21 is arranged in the push sleeve 1, the connecting shaft 21 and the setting shaft 22 are screwed, one end of the throwing glove 23 is stuck on the step in the push sleeve 1, and the throwing glove 23 and the push sleeve 1 are detachably connected, the other end of the throwing glove 23 is connected to one end of the center sleeve 24, the other end of the center sleeve 24 is screwed to the locking sleeve 25, and the setting shaft 22 passes through the throwing glove 23, the center sleeve 24, the serration part 3 and the positioning part 4 in sequence and is connected to the throwing hand part 5. It should be noted that there is a sealing component on the throwing glove 23, when the push sleeve 1 and the throwing glove 23 cannot move relative to each other, that is, the predetermined target is not achieved, the sealing component on the throwing glove 23 is in the original state, when the predetermined target is achieved, the push sleeve 1 can push the sealing component to compress so that the sealing component gradually expands until it abuts against the inner wall of the oil pipe sleeve, and at the same time, the positioning part 4 can also abut against the oil pipe sleeve. Optionally, the setting shaft 22 is a long rod structure, with a connecting thread on the left end outer circle, connected to the connecting shaft 21; a release thread on the right end outer circle, connected to the release ring 53. The length of the release thread is longer than the left and right ends of the internal thread of the release ring 53. The release sleeve 23 is a cylindrical structure, the inner hole on the left end is a conical structure, the outer circle on the right end is provided with an external connecting thread, the outer circle of the center sleeve 24 is provided with an external protrusion 35 at the left end, and the outer circle on the right end is a smooth structure, and a seal is formed at this position. The right end of the outer circle is connected with the external thread by a conical surface.

[0036] In one embodiment, the sealing assembly 20 further includes a long pin 26, and corresponding pin holes are provided on the outer walls of the throw-away glove 23 and the push sleeve 1, and the long pin 26 passes through the corresponding pin holes to connect the throw-away glove 23 and the push sleeve 1. The throw-away glove 23 and the push sleeve 1 are fixed together by the long pin 26, and when the push sleeve 1 is pushed to a certain force, the long pin 26 will break, so that the push sleeve 1 can move on the outer wall of the throw-away glove 23. Since the throw-away glove 23 has a sealing component, the sealing component can seal the oil casing under the push of the push sleeve 1.

[0037] Except for the rubber ring, the push sleeve 1, the connecting shaft 21, the setting shaft 22 and the hand release ring 53, all the above materials are soluble metals, which can be completely dissolved in a certain concentration of CL (chlorine) solution without any residue.

[0038] In summary, the inner hole step at one end of the push sleeve 1 matches the step of the throw-off glove 23, and the long pin 26 is screwed into the threaded through hole of the push sleeve 1 and then presses against the pin hole of the throw-off glove 23. The connecting shaft 21 is connected to the adapter mandrel through the external thread at the front end, the internal thread of the connecting shaft 21 is connected to the external thread at one end of the setting shaft 22, and the end face of the connecting shaft 21 abuts against the end face of the throw-off glove 23.

[0039] When the adapter starts to work, the connecting shaft 21 and the sealing shaft 22 are fixed, and the push sleeve 1 moves backward relatively. Since the long pin 26 locks the position of the push sleeve 1 relative to the sealing sleeve 23 through the pin hole of the sealing sleeve 23, the sealing sleeve 23 will be driven to move together when the push sleeve 1 moves. Then, the sealing sleeve 23 drives the center sleeve 24 and the outer circle parts to move backward. The locking sleeve 25 at the rear end of the center sleeve 24 further pushes the serration part 3, the positioning part 4 and each sliding block to expand and slide outward. When the thrust reaches a certain level, the hoop on the outside of the serration part 3 and the sliding block will automatically break, and the structure that is still hooped into a ring under the action of the rubber ring further tightens the serration part 3 and the sliding block to make it a whole. The locking sleeve 25 continues to descend, and finally the outer circle of the positioning part 4 is close to the casing, and the positioning teeth 43 bite into the inner wall of the casing, and the sealing is successful.

[0040] During the upward expansion of the positioning part 4, the required thrust becomes larger and larger. When the thrust reaches a certain level, the long pin 26 fixed between the front end of the throwing glove 23 and the push sleeve 1 breaks, and the push sleeve 1 pushes the positioning sleeve forward relative to the throwing glove 23. The push sleeve 1 can move on the outer wall of the throwing glove 23. Since the throwing glove 23 has a sealing component, the sealing component can seal the oil casing under the push of the push sleeve 1.

[0041] The present invention cooperates with each hoop and each rubber ring, so that even after the hoop is broken, it still presents a circular structure under the action of the rubber ring, and keeps the serrated portion 3 and each sliding block tightly attached to the locking sleeve 25 and the release ring 53, and will not fall apart. The rectangular groove of the release ring 53 is at a certain distance from the high point of the cone surface, so that when the sliding block slides upward, the sliding distance can be limited, and the sealing failure will not be caused by the sliding block sliding upward and driving the sliding block to slide away from the release ring 53. Through multi-stage sliding, the positioning portion 4 expands upward along the serrated portion 3 and the sliding block while the serrated portion 3 and the sliding block slide upward. The rectangular groove cooperates between the positioning portion 4 and the sliding block to ensure the sliding direction of the positioning portion 4. The serrated protrusion cooperates to ensure that it will not move in the opposite direction after the sliding expansion, and finally ensures that the positioning portion 4 is mutually restricted while contacting the casing and sealing, and the process is safe and reliable.

[0042] The present invention proposes a multi-stage sliding scheme of the positioning part 4 through optimized design on the basis of conventional soluble bridge plugs, so that the positioning part 4 and the serrated block are matched by a serrated protrusion, and the positioning part 4 and the sliding block are matched by a rectangular protrusion / groove. The sealing and setting process is safe and reliable, and effectively breaks through the bottleneck that conventional bridge plugs can only meet the sealing pressure in casings with a small diameter difference. When encountering severe deformation or shrinkage of the casing, the soluble bridge plug is prone to encountering resistance, jamming or premature setting during the lowering process. The small-diameter soluble bridge plug structure design proposed in the present invention can meet the design needs of small-diameter soluble bridge plugs with a diameter less than or equal to 65mm, greatly improve the applicability and passability of complex working conditions such as casing deformation and shrinkage, and ensure the effective and uniform anchoring of the positioning block, avoid problems such as eccentric loading or uneven anchoring, improve the pressure bearing capacity and anchoring stability of the anchoring structure, meet the needs of small-diameter bridge plugs in large annular casing setting and complex working conditions, and provide a design reference for the customized design of small-diameter soluble bridge plugs under special working conditions. At the same time, it can effectively ensure efficient fracturing operations under complex conditions such as severe deformation or shrinkage of casing in the existing oil and gas production process, and provide strong technical support for the efficient development of unconventional oil and gas resources and the quality improvement and cost reduction of horizontal well staged fracturing.

[0043] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A small diameter soluble bridge plug, used for installation in an oil casing to seal the inner cavity of the oil casing, characterized in that: include: A push sleeve (1) and a sleeve part (2), as well as a serrated part (3), a positioning part (4) and a release part (5) all formed by splicing at least two parts, wherein the push sleeve (1) and the sleeve part (2) are detachably connected, the inner wall of one end of the serrated part (3) and the outer wall of the sleeve part (2) are serrated and movably connected, and the outer diameter of one end of the sleeve part (2) close to the serrated part (3) gradually decreases, the outer wall of the other end of the serrated part (3) and the inner wall of the positioning part (4) are serrated and movably connected, the outer diameter of one end of the serrated part (3) and the positioning part (4) that cooperate with each other is gradually reduced, the outer diameter of one end of the positioning part (4) and the release part (5) that cooperate with each other is gradually increased, and the inner wall of the other end of the positioning part (4) is slidably connected to the outer wall of the release part (5), so that the two parts of the positioning part (4) are separated and moved to abut against the inner wall of the oil casing under the push of each component.

2. The small diameter soluble bridge plug according to claim 1, characterized in that: The positioning portion (4) comprises at least one first positioning block (41) and a second positioning block (42); the first positioning block (41) and the second positioning block (42) are spliced ​​to form an axial hole to cooperate with the setting shaft (22); the first positioning block (41) and the second positioning block (42) are provided with saw teeth on the inner wall of the same end to cooperate with the protrusion (35) on the outer wall of the sawtooth portion (3); and a protrusion (48) is provided on the inner wall of the same end to cooperate with the groove (55) on the outer wall of the release portion (5).

3. The small diameter soluble bridge plug according to claim 2, characterized in that: The positioning portion (4) further comprises a plurality of positioning teeth (43) and a plurality of first rubber rings (44); a plurality of cylindrical holes (46) and rectangular annular grooves (45) are provided on the outer walls of the first positioning block (41) and the second positioning block (42); the first rubber ring (44) is provided in the rectangular annular groove (45); the axis of the cylindrical hole (46) is not perpendicular to the axial line of the first positioning block (41) and the second positioning block (42); the positioning teeth (43) are provided in the cylindrical hole (46); and the positioning teeth (43) are anchored on the inner wall of the oil casing.

4. The small diameter soluble bridge plug according to claim 1, characterized in that: The sawtooth portion (3) comprises at least one first sawtooth block (31) and a second sawtooth block (32), a first hoop (33) and a second rubber ring (34); the first sawtooth block (31) and the second sawtooth block (32) are spliced ​​to form an axial hole to cooperate with the setting shaft (22); the sawtooth-shaped protrusions (35) provided on the inner and outer walls at both ends of the first sawtooth block (31) and the second sawtooth block (32) respectively cooperate with the rectangular protrusions provided on the inner and outer walls of the positioning portion (4) and the connecting portion (2); the first hoop (33) is sleeved on one end of the first sawtooth block (31) and the second sawtooth block (32) and close to the side of the connecting portion (2); a first limiting groove is provided on the first hoop (33), and the second rubber ring (34) is sleeved in the first limiting groove.

5. The small diameter soluble bridge plug according to claim 1, characterized in that: The release part (5) comprises at least one first sliding block (51) and a second sliding block (52), a second hoop (54) and a third rubber ring. The first sliding block (51) and the second sliding block (52) are spliced ​​to form an axial hole to cooperate with the setting shaft (22). The groove (55) provided on the inner wall of one end of the first sliding block (51) and the second sliding block (52) cooperates with the protrusion (48) provided on the outer wall of the positioning part (4). The second hoop (54) is sleeved on the other end of the first sliding block (51) and the second sliding block (52), and a second limiting groove is provided on the second hoop (54). The third rubber ring is sleeved in the second limiting groove.

6. The small diameter soluble bridge plug according to claim 5, characterized in that: The releasing part (5) further comprises a releasing ring (53), wherein an axial hole is arranged inside the releasing ring (53) to cooperate with the setting shaft (22), a sliding groove (531) provided on the outer wall at one end of the releasing ring (53) cooperates with a protruding block (56) provided on the inner walls of the first sliding block (51) and the second sliding block (52), and the second hoop (54) is located at one end close to the releasing ring (53).

7. The small diameter soluble bridge plug according to claim 1, characterized in that: The sleeve portion (2) comprises a sealing component (20) and a locking sleeve (25); the push sleeve (1) and the sealing component (20) are detachably connected; one end of the sealing component (20) and the locking sleeve (25) are threadedly connected; and the other end of the locking sleeve (25) is movably connected to the sawtooth portion (3).

8. The small diameter soluble bridge plug according to claim 7, characterized in that: The outer diameter of one end of the locking sleeve (25) that cooperates with the sawtooth portion (3) gradually decreases, and the sawtooth-shaped thread on the outer wall of the locking sleeve (25) cooperates with the protrusion on the inner wall of the sawtooth portion (3).

9. The small diameter soluble bridge plug according to claim 7, characterized in that: The sealing assembly (20) comprises a connecting shaft (21), a sealing shaft (22), a release glove (23) and a center sleeve (24); the connecting shaft (21) is arranged in the push sleeve (1); the connecting shaft (21) and the sealing shaft (22) are threadedly connected; one end of the release glove (23) is clamped on a step in the push sleeve (1); the release glove (23) and the push sleeve (1) are detachably connected; the other end of the release glove (23) is connected to one end of the center sleeve (24); the other end of the center sleeve (24) is threadedly connected to the locking sleeve (25); the sealing shaft (22) passes through the release glove (23), the center sleeve (24), the serrated portion (3) and the positioning portion (4) in sequence and is connected to the release glove (5).

10. The small diameter soluble bridge plug according to claim 9, characterized in that: The sealing assembly (20) further comprises a long pin (26), and corresponding pin holes are provided on the outer walls of the throwing glove (23) and the push sleeve (1), and the long pin (26) passes through the corresponding pin holes to connect the throwing glove (23) and the push sleeve (1).

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