Double-clamping and double-sealing type soluble bridge plug

Abstract

The invention discloses a double-clamping and double-sealing type soluble bridge plug, which belongs to the technical field of borehole packing tools and comprises a lower central pipe, an upper central pipe, a locking ring, a conical sleeve, a slip sleeve and a rubber sleeve. The outer wall of the upper end of the lower center pipe is provided with one-way outer insection, and the peripheral side of the lower end of the lower center pipe is provided with a lower shoulder part. The upper end of the lower central pipe is coaxially sleeved with the upper central pipe, and an upper shoulder part is arranged on the periphery of the upper end of the upper central pipe. The locking ring is arranged on the middle section in the upper center pipe, one-way inner insections meshed with the one-way outer insections are arranged on the inner wall of the locking ring, and a notch penetrating through the two ends is formed in one side of the locking ring. The number of the conical sleeves is two, the lower central pipe and the upper central pipe are sleeved with the conical sleeves respectively, and the conical surfaces of the two conical sleeves are oppositely arranged. And the slip sleeves are sleeved outside the conical surfaces of the two conical sleeves. The two rubber sleeves are located at the outer ends of the two conical sleeves respectively. According to the scheme, the packing time efficiency of the soluble bridge plug can be effectively prolonged, and a good sealing effect is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of wellbore isolation tools, and in particular relates to a double-card double-seal type soluble bridge plug. Background Art

[0002] Soluble bridge plug is a commonly used wellbore isolation tool in drilling technology. Its structure mainly includes central pipe, slip anchoring mechanism and sealing rubber cylinder. When in use, the bridge plug is lowered to the predetermined position of the wellbore casing by cable or continuous tubing, and the rubber cylinder is squeezed by hydraulic pressure to compress and expand, while driving the cone of the slip anchoring mechanism downward, so that the slip is forced to open, and the outer wall of the slip is used to bite the casing, thereby fixing the bridge plug at the predetermined position of the casing. In this process, the rubber cylinder is further squeezed and expanded, thereby sealing the casing. When the thrust reaches the shear value of the release pin, the pin is cut off, and then the bridge plug can be separated from the cable or tubing, and the bridge plug is left in the casing to form a sealing structure. The soluble bridge plug is mainly composed of soluble magnesium-aluminum alloy material and soluble rubber cartridge. The structure made of aluminum-magnesium alloy mainly includes the slip anchoring mechanism. When the bridge plug comes into contact with water, the magnesium-aluminum material will undergo an electrochemical reaction with the water, thereby achieving the purpose of dissolution. The soluble rubber cartridge will also degrade in water, and the degradation rate of the rubber cartridge is usually lower than the dissolution rate of the magnesium-aluminum alloy.

[0003] In the prior art, a Chinese patent application with application number 202011553271.1 discloses a fully soluble bridge plug, which includes a group of petal-type cava assemblies and rubber cartridges arranged along the axis of the central tube; a Chinese patent application with application number 201910252838.2 discloses a fully soluble bridge plug, which includes a rubber cartridge arranged on the central shaft and two groups of anchoring assemblies located at both ends of the rubber cartridge. The bridge plug structure recorded in the above content is the common structural design of the current soluble bridge plug. The above structures have one thing in common, the anchoring component, more specifically the slip. After the bridge plug is lowered into the well, the slip is immersed in a large amount of liquid. The moment the bridge plug comes into contact with the liquid in the well, the slip begins to dissolve. When the slip is dissolved to a predetermined degree, it will lose its seating effect, which will cause the bridge plug to loosen and the rubber cylinder to gradually lose its sealing effect. Therefore, the sealing time of this type of soluble bridge plug is usually short, and the effective sealing time is generally one to three days. Therefore, this type of soluble bridge plug cannot meet longer sealing requirements. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the present invention provides a double-card double-seal soluble bridge plug, which can effectively prolong the sealing time of the soluble bridge plug and has a good sealing effect.

[0005] In order to achieve the purpose of the present invention, the following scheme is proposed: A double-card double-seal soluble bridge plug comprises: a lower center pipe, an upper center pipe, a locking ring, a conical sleeve, a slip sleeve and a rubber cylinder.

[0006] The outer wall of the upper end of the lower center tube has a unidirectional external tooth pattern, which includes an upper inclined surface inclined toward the outer side of the upper end of the lower center tube and a lower limit surface adjacent to the upper inclined surface and perpendicular to the axis of the lower center tube. A lower shoulder is provided on the outer peripheral side of the lower end of the lower center tube.

[0007] The upper center tube is coaxially sleeved on the upper end of the lower center tube, the lower end of the upper center tube is in sliding contact with the outer wall of the lower center tube, the outer periphery of the upper end of the upper center tube is provided with an upper shoulder, and the upper center tube and the lower center tube are relatively movable along the axial direction.

[0008] The locking ring is arranged in the middle section inside the upper center tube, and its inner wall is provided with a unidirectional internal tooth pattern that meshes with the unidirectional external tooth pattern. The unidirectional internal tooth pattern includes a lower inclined surface opposite to the upper inclined surface, and an upper limit surface opposite to the lower limit surface. A notch running through both ends is opened on one side of the locking ring.

[0009] There are two conical sleeves, which are respectively sleeved on the outside of the lower center tube and the upper center tube, and the conical surfaces of the two conical sleeves are arranged opposite to each other.

[0010] The slip sleeve is arranged outside the conical surfaces of the two conical sleeves, and the two ends of the inner wall of the slip sleeve are matched with the conical surfaces of the two conical sleeves respectively. The side wall of the slip sleeve is provided with a cutting slit, and its length direction is consistent with the axis of the slip sleeve.

[0011] There are two rubber sleeves, one of which is sleeved on the lower center tube and located between the lower shoulder and the end face of the conical sleeve on the lower center tube, and the other rubber sleeve is sleeved on the upper center tube and located between the upper shoulder and the end face of the conical sleeve on the upper center tube.

[0012] The beneficial effects of the present invention are as follows: the present scheme utilizes the sealing space of the annular structure formed between the two rubber cylinders and between the sleeve and the upper center tube and the lower center tube, and the cone sleeve and the slip sleeve are both located in the sealing space, thereby avoiding the cone sleeve and the slip sleeve from being immersed in a large amount of liquid from the very beginning. Instead, it is necessary to wait until the rubber cylinder is degraded by the liquid and loses its sealing effect before the cone sleeve and the slip sleeve begin to contact with a large amount of liquid and decompose, thereby preventing the cone sleeve and the slip sleeve from decomposing prematurely, extending the setting time of the bridge plug, and utilizing the sealing space to effectively prevent impurities from entering and affecting the normal operation of the slip. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present invention.

[0014] Figure 1 An overall cross-sectional view of the soluble bridge plug of the present application is shown.

[0015] Figure 2 Shows Figure 1 A partial enlarged view of point A in the middle.

[0016] Figure 3 An overall cross-sectional view of the setting tool when connected to the soluble bridge plug is shown.

[0017] Figure 4 A cross-sectional view of the soluble bridge plug when set is shown.

[0018] Figure 5 An end view of the locking ring is shown.

[0019] Figure 6 A structural cross-sectional view of the slip sleeve is shown.

[0020] Figure 7 A schematic structural diagram of a tapered sleeve is shown.

[0021] Figure 8 A cross-sectional view of a slip is shown.

[0022] Markings in the figure: lower center tube -1, upper inclined surface -11, lower limit surface -12, lower shoulder -13, upper center tube -2, upper shoulder -21, locking ring -3, lower inclined surface -31, upper limit surface -32, notch -33, tapered sleeve -4, guide groove -41, slip sleeve -5, cutting seam -51, carbide tooth -52, countersunk hole -53, guide rib -54, rubber cylinder -6, pull rod -91, push cylinder -92, shear pin -93, retaining ring -94. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions and advantages of the embodiments of the present invention more clear, the implementation modes of the present invention are described in detail below with reference to the accompanying drawings. However, the embodiments described in the present invention are only part of the embodiments of the present invention, rather than all the embodiments.

[0024] like Figures 1 to 8 As shown, a double-card double-seal soluble bridge plug includes: a lower center pipe 1, an upper center pipe 2, a locking ring 3, a conical sleeve 4, a slip sleeve 5 and a rubber cylinder 6.

[0025] The outer wall of the upper end of the lower center tube 1 has a unidirectional external tooth pattern, which includes an upper inclined surface 11 inclined toward the outer side of the upper end of the lower center tube 1 and a lower limit surface 12 adjacent to the upper inclined surface 11 and perpendicular to the axis of the lower center tube 1. A lower shoulder 13 is provided on the outer peripheral side of the lower end of the lower center tube 1.

[0026] The upper center tube 2 is coaxially sleeved on the upper end of the lower center tube 1, the lower end of the upper center tube 2 is in sliding contact with the outer wall of the lower center tube 1, the outer periphery of the upper end of the upper center tube 2 is provided with an upper shoulder 21, and the upper center tube 2 and the lower center tube 1 are relatively movable along the axial direction.

[0027] The locking ring 3 is arranged in the middle section inside the upper center tube 2, and its inner wall is provided with a unidirectional internal tooth pattern meshing with the unidirectional external tooth pattern. The unidirectional internal tooth pattern includes a lower inclined surface 31 facing opposite to the upper inclined surface 11, and an upper limit surface 32 facing opposite to the lower limit surface 12. A notch 33 running through both ends is opened on one side of the locking ring 3.

[0028] There are two conical sleeves 4, which are respectively sleeved on the outside of the lower center tube 1 and the upper center tube 2, and the conical surfaces of the two conical sleeves 4 are arranged opposite to each other.

[0029] The slip sleeve 5 is coaxially sleeved on the outside of the conical surfaces of the two conical sleeves 4, and the two ends of the inner wall of the slip sleeve 5 are respectively matched with the conical surfaces of the two conical sleeves 4. The side wall of the slip sleeve 5 is provided with a cutting slit 51, and its length direction is consistent with the axis of the slip sleeve 5. When hanging, the solid part between adjacent cutting slits 51 is used to form a slip.

[0030] There are two rubber cylinders 6, one of which is sleeved on the lower center tube 1 and located between the lower shoulder 13 and the end surface of the tapered sleeve 4 on the lower center tube 1, and the other rubber cylinder 6 is sleeved on the upper center tube 2 and located between the upper shoulder 21 and the end surface of the tapered sleeve 4 on the upper center tube 2.

[0031] When in use, a sealing tool is needed to drive the bridge plug to sit. The conventional sealing tool includes a pull rod 91, a push cylinder 92 sleeved on the outside of the pull rod 91, and a retaining ring 94 connected to the lower end of the pull rod 91 by a shear pin 93. The push cylinder 92 is driven to move toward the lower end of the pull rod 91 by the pressure generated by hydraulic pressure or gunpowder explosion.

[0032] Before going down into the well, pass the pull rod 91 from top to bottom through the upper central pipe 2 and the lower central pipe 1, connect the retaining ring 94 to the lower end of the pull rod 91 by means of the shear pin 93, use the retaining ring 94 to abut the lower end of the lower central pipe 1 to prevent the bridge plug from falling, and sleeve the push tube 92 on the pull rod 91, so that the lower end of the push tube 92 abuts against the top of the upper central pipe 2, and the upper end of the pull rod 91 is connected to the oil pipe or cable.

[0033] When setting the seal, the oil pipe or cable is used to drive the setting tool and the soluble bridge plug to descend to the predetermined depth position in the well; then the pressure generated by hydraulic pressure or gunpowder explosion is used to drive the push tube 92 to move toward the lower end of the pull rod 91. Since the bottom of the lower center tube 1 is restricted by the retaining ring 94, the push tube 92 will push the upper center tube 2 to move downward relative to the lower center tube 1, and the upper center tube 2 and the lower center tube 1 will be in a state of relative movement along the axis. In this way, the upper shoulder 21 of the upper center tube 2 and the lower shoulder 13 of the lower center tube 1 can be used to squeeze the two rubber cylinders 6 toward the middle at the same time, so that the rubber cylinder 6 expands outward. While the rubber cylinder 6 expands, it will push the two cone sleeves 4 to move toward the middle, and use the conical surface of the cone sleeve 4 to squeeze the slip sleeve 5 to open outward. When the outward extrusion force on the slip sleeve 5 reaches a predetermined value, the slip sleeve 5 will be split into multiple slips from the cutting seam 51, and the outer wall of the slip will bite on the inner wall of the casing to achieve the purpose of setting. After expansion, the rubber cylinder 6 will fit with the inner wall of the casing, and form a sealed space of annular structure between the two rubber cylinders 6 and between the casing and the upper center pipe 2 and the lower center pipe 1, and the cone sleeve 4 and the slip sleeve 5 are both located in the sealed space, so as to avoid the cone sleeve 4 and the slip sleeve 5 being immersed in a large amount of liquid from the beginning, and prevent the cone sleeve 4 and the slip sleeve 5 from decomposing prematurely. Instead, it is necessary to wait until the rubber cylinder 6 is degraded by the liquid and loses its sealing effect, and then the cone sleeve 4 and the slip sleeve 5 will begin to contact with a large amount of liquid and decompose, and the use of the sealed space can effectively prevent impurities from entering and affecting the normal operation of the slip. The above method can effectively extend the setting time of the bridge plug; although a small amount of liquid is inevitably retained in the sealed space, due to the limited amount of liquid retained, it will not be able to provide enough liquid for the decomposition of the cone sleeve 4 and the slip sleeve 5.

[0034] During the above-mentioned seating process, the lock ring 3 will also move downward relative to the lower center tube 1. When the lock ring 3 moves, the sliding fit between the lower inclined surface 31 and the upper inclined surface 11 will open the notch 33 of the lock ring 3, so that the one-way inner tooth pattern and the one-way outer tooth pattern are temporarily separated. After the lock ring 3 moves downward by a tooth pattern spacing, the lock ring 3 will automatically close under the action of its own elastic force, so that the one-way inner tooth pattern and the one-way outer tooth pattern are meshed again. Through this structural design, even after the sealing tool is taken out, the structure between the lower limit surface 12 and the upper limit surface 32 can be used to abut each other to prevent the lower center tube 1, the lock ring 3 and the upper center tube 2 from moving toward both ends, thereby preventing the rubber tube 6 from rebounding and keeping it in a compressed state during the effective time, so as to ensure the continuity of the seating and the sealing effect of the rubber tube 6.

[0035] After the seating is completed, continue to apply thrust to the push tube 92. When the thrust reaches the predetermined value, the shear pin 93 will be cut off, the retaining ring 94 will be separated from the pull rod 91, and then the pull rod 91 and the push tube 92 can be taken out upward. By dropping a ball above the soluble bridge plug or below the soluble bridge plug in advance, the inner hole of the bridge plug can be blocked with the ball. Among them, when the ball is dropped above the bridge plug, the bridge plug is used to withstand the downward pressure from above, and when the ball is dropped below the bridge plug, the bridge plug is used to withstand the upward pressure from below; and there will only be pressure in one direction at the same time in the wellbore. Therefore, in this case, no matter which direction the bridge plug is used to withstand pressure, only the rubber cylinder 6 close to the pressure-applying party will withstand the axial pressure on its end face, while the other rubber cylinder 6 can avoid being compressed, so that the bridge plug has a better pressure-bearing capacity. The single rubber tube bridge plug commonly used in the prior art will creep downward when subjected to an upper pressure difference; and creep upward when subjected to a lower pressure difference. Such back-and-forth creeping will cause the strength of the rubber tube to decrease, thereby reducing the overall sealing pressure and shortening the sealing time.

[0036] Preferably, Figure 8 As shown, both ends of the outer wall of the cava sleeve 5 have a barb structure, and the barbs are all facing the middle of the cava sleeve 5. When the cava sleeve 5 is subjected to an extrusion force from above, the barbs can be squeezed more firmly with the inside of the sleeve; similarly, when the cava sleeve 5 is subjected to an extrusion force from below, the barbs can be squeezed more firmly with the inside of the sleeve.

[0037] Preferably, Figure 6 , Figure 8 As shown, the outer wall of the slip sleeve 5 is provided with carbide teeth 52 at the solid parts between the adjacent cutting seams 51, so as to improve the bite force between the slip sleeve 5 and the casing.

[0038] Further preferably, Figure 8 As shown, countersunk holes 53 are opened at the positions of the outer wall of the cava sleeve 5 corresponding to the locations where the carbide teeth are set, and the countersunk holes 53 are tapered hole structures with the small ends of the tapered holes facing outwards, and the carbide teeth 52 are tapered column structures matching the countersunk holes 53, and the specific tapers of the countersunk holes 53 and the carbide teeth 52 are both 4-6°.

[0039] Preferably, Figure 6 , Figure 7 As shown, the outer wall of the conical surface of the conical sleeve 4 is provided with a guide groove 41, and the guide groove 41 is arranged along the generatrix of the conical surface of the conical sleeve 4, and the inner wall of the cava sleeve 5 is provided with a guide rib 54 that matches the guide groove 41 one by one to ensure that the cava can be directional and open outward to prevent the cava sleeve 5 from being deflected after the cava sleeve 5 is split into multiple cava.

[0040] The above description is only a preferred embodiment of the present invention, and is not intended to be the only one or to limit the present invention. Those skilled in the art should understand that various changes or equivalent substitutions made to the present invention without departing from the scope of the present invention are within the scope of protection of the present invention.

Claims

1. A double-card double-seal soluble bridge plug, characterized in that: include: The lower center tube (1) has an outer wall at the upper end with a unidirectional outer tooth pattern, the unidirectional outer tooth pattern comprising an upper inclined surface (11) inclined toward the outer side of the upper end of the lower center tube (1) and a lower limit surface (12) adjacent to the upper inclined surface (11) and perpendicular to the axis of the lower center tube (1), and a lower shoulder (13) is provided on the outer peripheral side of the lower end of the lower center tube (1); An upper center tube (2) is coaxially sleeved on the upper end of the lower center tube (1), the lower end of the upper center tube (2) is in sliding contact with the outer wall of the lower center tube (1), an upper shoulder (21) is provided on the outer periphery of the upper end of the upper center tube (2), and the upper center tube (2) and the lower center tube (1) are arranged to move relative to each other along the axial direction; A lock ring (3) is arranged in the middle section of the upper center tube (2), and its inner wall is provided with a unidirectional inner tooth pattern that meshes with the unidirectional outer tooth pattern, the unidirectional inner tooth pattern includes a lower inclined surface (31) facing opposite to the upper inclined surface (11), and an upper limit surface (32) facing opposite to the lower limit surface (12), and a notch (33) is opened on one side of the lock ring (3) and passes through both ends; There are two conical sleeves (4), which are respectively sleeved on the outside of the lower center tube (1) and the upper center tube (2), and the conical surfaces of the two conical sleeves (4) are arranged opposite to each other; The slip sleeve (5) is sleeved on the outside of the conical surfaces of the two conical sleeves (4), the two ends of the inner wall of the slip sleeve (5) respectively match the conical surfaces of the two conical sleeves (4), and the side wall of the slip sleeve (5) is provided with a cutting slit (51), the length direction of which is consistent with the axis of the slip sleeve (5); There are two rubber cylinders (6), one of which is sleeved on the lower center tube (1) and located between the lower shoulder (13) and the end surface of the conical sleeve (4) on the lower center tube (1), and the other rubber cylinder (6) is sleeved on the upper center tube (2) and located between the upper shoulder (21) and the end surface of the conical sleeve (4) on the upper center tube (2).

2. A double-card double-seal soluble bridge plug according to claim 1, characterized in that: Both ends of the outer wall of the slip sleeve (5) have barb structures, and the barbs are directed toward the middle of the slip sleeve (5).

3. A double-card double-seal soluble bridge plug according to claim 1, characterized in that: Hard alloy teeth (52) are provided on the outer wall of the slip sleeve (5) at the physical parts corresponding to the adjacent cutting seams (51).

4. A double-card double-seal soluble bridge plug according to claim 3, characterized in that: The outer wall of the slip sleeve (5) is provided with countersunk holes (53) at positions corresponding to the locations where the hard alloy teeth are arranged, and the countersunk holes (53) are tapered hole structures with the small ends of the tapered holes facing outwards, and the hard alloy teeth (52) are tapered column structures matching the countersunk holes (53).

5. The double-card double-seal soluble bridge plug according to claim 1, characterized in that: The outer wall of the conical surface of the conical sleeve (4) is provided with a guide groove (41), and the guide groove (41) is arranged along the generatrix of the conical surface of the conical sleeve (4), and the inner wall of the slip sleeve (5) is provided with a guide rib (54) that matches the guide groove (41) one by one.

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