Self-dissolving soluble bridge plug and unfreezing method

Abstract

The invention belongs to the technical field of downhole tools, and particularly relates to a self-dissolving soluble bridge plug and an unfreezing method. The self-dissolving soluble bridge plug comprises: a central tube; the outer wall of the central pipe is coaxially sleeved with a rubber sleeve and a lower cone in sequence from top to bottom, the upper end of the rubber sleeve abuts against the central pipe in the axial direction, and an axial gap exists between the lower cone and the rubber sleeve; a lower slip is coaxially arranged on the outer wall of the lower end of the lower cone; a guide shoe slip fixing seat is coaxially and fixedly arranged at the lower end of the lower slip; at least one capsule part is arranged in the central pipe and / or the lower cone, a cosolvent is arranged in the capsule part, and the capsule part can be broken in response to the pressure of an inner cavity of the self-dissolving soluble bridge plug, so that the cosolvent in the capsule part flows out.

Description

Technical Field

[0001] The invention belongs to the technical field of downhole tools, and in particular relates to a self-dissolving soluble bridge plug and a method for releasing the plug. Background Art

[0002] At present, in the process of oil and gas well operation, soluble bridge plugs have been widely used for formation isolation. The use of bridge plugs for formation isolation can effectively achieve staged fracturing.

[0003] As the drilling depth of oil and gas wells increases, the wellbore temperature becomes deeper and deeper, the formation pressure becomes greater and greater, and the casing deformation of the wellbore becomes more and more serious, thus placing higher and higher requirements on soluble bridge plugs. In the case of severe deformation of the wellbore casing, the probability of the soluble bridge plug encountering resistance during the wellbore entry gradually increases, so the unblocking method becomes particularly important. It is necessary to complete the unblocking of the soluble bridge plug as soon as possible, restore the wellbore in time, avoid the waiting of existing personnel and equipment, and shorten the time of ineffective operations.

[0004] Chinese patent document CN110656904A discloses a method for accelerating the dissolution rate of soluble bridge plugs. The metal soluble ball is a double-layer structure, including soluble metal and filler, the filler is a filler sphere, and the soluble metal is wrapped outside the filler sphere to form a double-layer solid sphere. After the soluble ball dissolves, the filler will accelerate the dissolution of the soluble bridge plug and greatly accelerate the dissolution rate of the soluble bridge plug, thereby reducing the soaking time, reducing the difficulty of wellbore treatment after pressure, reducing the cost of wellbore treatment after pressure, and improving the well production time rate. The starting point of the dissolution aid in this patent is different from that of this patent. This patent can cope with normal well construction and achieve dissolution aid by throwing dissolution aid balls. However, for wells with complex conditions, once the bridge plug is suddenly stuck, the ball throwing operation cannot be carried out, and thus the dissolution of the soluble bridge plug cannot be accelerated.

[0005] Chinese patent document CN110513075A discloses a soluble bridge plug and a soluble device for accelerating the dissolution of the bridge plug. The bridge plug is made of a soluble material and dissolves within a first predetermined time based on the fluid characteristics. The soluble device includes: a soluble body configured to be inserted into the hole of the mandrel of the bridge plug, the soluble body having a through hole and at least one storage space for a dissolution-promoting substance, wherein the through hole is connected to the hole of the mandrel so that the fluid can contact the bridge plug; the soluble body dissolves within a second predetermined time based on the fluid characteristics, so that the dissolution-promoting substance stored in the storage space for the dissolution-promoting substance dissolves into the fluid in which the bridge plug is located, thereby promoting the dissolution of the bridge plug. This patent cannot be triggered actively, and can only wait for the bridge plug to dissolve on its own, and cannot be manually intervened.

[0006] Chinese patent document CN109488251A discloses a pre-set dissolving medium mechanism and a method of using it. It includes a central tube, a main body, and shear pins and sealing rings arranged on the main body. The central tube is a reducer with a smaller inner diameter at the top and a larger inner diameter at the bottom, and a ball seat is arranged inside the central tube. The main body is an annular tube with two sections of equal outer diameters and unequal inner diameters. A sealing screw is arranged on the top of the main body, and shear pins are symmetrically arranged on the upper end to connect with the central tube. The upper and lower parts of the main body are respectively provided with sealing rings, and the shear pins are located higher than the ball seat of the central tube. The pre-set dissolving medium mechanism provided by the invention is provided with an opening device for soluble isolation tools (such as soluble bridge plugs), which can extend the working time of the isolation tools without affecting the normal operation of the ball seat. The opening device requires the outside world to open the release channel of the dissolved material after throwing the ball, so as to realize fixed-point and timed dissolution and achieve the control of the dissolution time of the soluble isolation tool. However, in wells encountering complex situations, once the bridge plug is suddenly stuck, the ball throwing operation cannot be carried out, thereby failing to accelerate the dissolution of the soluble bridge plug. Summary of the invention

[0007] In view of the technical problems mentioned above, the present invention aims to propose a self-dissolving soluble bridge plug, which can accelerate the dissolution of the bridge plug through human intervention, thereby completing the unblocking and unblocking.

[0008] According to the present invention, a self-dissolving soluble bridge plug is provided, comprising:

[0009] Central tube;

[0010] A rubber sleeve and a lower cone are coaxially sleeved on the outer wall of the central tube from top to bottom, the upper end of the rubber sleeve is axially abutted against the central tube, and an axial gap exists between the lower cone and the rubber sleeve;

[0011] A lower slip is coaxially arranged on the outer wall of the lower end of the lower cone;

[0012] A guide shoe slip fixing seat is coaxially fixedly arranged at the lower end of the lower slip;

[0013] At least one capsule is arranged in the central tube and / or the lower cone, and a solvent is arranged in the capsule. The capsule can be broken in response to the pressure in the inner cavity of the self-dissolving soluble bridge plug, so that the solvent in the capsule can flow out.

[0014] In a preferred embodiment, the capsule is made of soluble rubber.

[0015] In a preferred embodiment, the co-solvent comprises ferric chloride.

[0016] In a preferred embodiment, a plurality of mounting grooves are provided on the inner walls of the central tube and the lower cone, the depth of the mounting grooves is 2-3 mm smaller than the wall thickness of the central tube or the lower cone, and the capsule is located in the mounting grooves.

[0017] In a preferred embodiment, a sealing member for sealing the capsule member is arranged at the position of the mounting groove.

[0018] In a preferred embodiment, the blocking member is made of a soluble magnesium alloy material.

[0019] In a preferred embodiment, the blocking member is bonded to the mounting groove by high temperature resistant sealing glue.

[0020] In a preferred embodiment, the lower end surface of the central tube is located within the axial length range of the lower cone.

[0021] In a preferred embodiment, an adapter connecting rod is provided in an intermittent coaxial sleeve in the central tube, and the adapter connecting rod is connected to the guide shoe slip fixing seat via a shear pin.

[0022] According to the present invention, a method for unblocking a soluble bridge plug is also proposed. When the self-dissolving soluble bridge plug provided by the present invention encounters obstruction or gets stuck during the process of entering the well, fluid is pumped into the self-dissolving soluble bridge plug to increase the pressure in the center pipe and the inner cavity of the lower cone, thereby squeezing and rupturing the capsule part, allowing the co-solvent in the capsule part to flow out, and dissolving the self-dissolving soluble bridge plug.

[0023] Compared with the prior art, the present application has at least the following advantages.

[0024] A capsule is arranged on the central tube and / or the lower cone, and the capsule can rupture in response to the pressure in the inner cavity of the self-dissolving soluble bridge plug, so that the solvent inside the capsule flows out, accelerating the dissolution speed of the self-dissolving soluble bridge plug, thereby realizing rapid unblocking and unstuck of the bridge plug. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be described below with reference to the accompanying drawings.

[0026] Figure 1 A schematic diagram showing an embodiment of a self-dissolving soluble bridge plug according to the present invention;

[0027] Figure 2 A schematic structural diagram showing the connection between the self-dissolving soluble bridge plug of the present invention and the adapter is shown.

[0028] In the figure:

[0029] 1. Center tube; 2. Rubber cylinder; 3. Metal support ring; 4. Lower cone; 5. Lower slip; 6. Guide shoe slip fixing seat; 7. Slip anchoring teeth; 8. Lower rubber cylinder protection ring; 9. Threaded connection sleeve; 10. Floating rubber cylinder shoulder ring; 11. Capsule part; 12. Large diameter part; 13. Small diameter part; 14. Adapter push cylinder; 15. Adapter connecting rod; 16. Mounting groove; 17. Sealing part; 18. Shear pin; 100. Self-dissolving soluble bridge plug.

[0030] In the present application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention and are not drawn according to the actual scale. DETAILED DESCRIPTION

[0031] The present invention will be described below with reference to the accompanying drawings.

[0032] It should be noted that the directional term or qualifier "up" used in this application refers to the direction close to the wellhead after the self-dissolving soluble bridge plug 100 is placed in the well, that is, Figure 1 "Down" refers to the direction away from the wellhead after the self-dissolving soluble bridge plug 100 enters the well, i.e. Figure 1 They are not intended to define the absolute positions of the components involved but may vary depending on the circumstances.

[0033] Embodiment 1:

[0034] Figure 1 The structure of the self-dissolving soluble bridge plug 100 is shown. Figure 1 As shown, the self-dissolving soluble bridge plug 100 includes a central tube 1, on the outer wall of the central tube 1, a rubber sleeve 2 and a lower cone 4 are coaxially sleeved in sequence from top to bottom, the upper end of the rubber sleeve 2 is axially abutted against the central tube 1, and an axial gap exists between the lower cone 4 and the rubber sleeve 2. A lower slip 5 is coaxially arranged on the outer wall of the lower end of the lower cone 4, and a guide shoe slip fixing seat 6 is coaxially fixedly arranged at the lower end of the lower slip 5.

[0035] At least one capsule 11 is arranged in the central tube 1 and / or the lower cone 4. A solvent is arranged in the capsule 11. The capsule 11 can rupture in response to the pressure in the cavity of the self-dissolving soluble bridge plug, so that the solvent in the capsule 11 flows out.

[0036] Specifically, when the self-dissolving soluble bridge plug 100 encounters obstruction or jamming, drilling fluid is pumped from the ground into the well, thereby increasing the pressure in the inner cavity of the central pipe 1 and the lower cone 4, and then squeezing and rupturing the capsule 11, so that the solvent in the capsule 11 flows out, and the solvent and the drilling fluid come into contact with the self-dissolving soluble bridge plug 100 together, thereby accelerating the dissolution of the self-dissolving soluble bridge plug 100 and completing the unblocking or unjamming.

[0037] In a preferred embodiment, the capsule member 11 is made of soluble rubber. The solvent comprises ferric chloride, which is wrapped in the capsule member 11 made of soluble rubber. It is easy to understand that the soluble rubber is an existing material and is not a technical point of the present invention, and will not be described in detail here. By using the capsule member 11 made of soluble rubber, even if the pressure in the inner cavity of the central tube 1 and the lower cone 4 is low, the capsule member 11 can be dissolved by itself, thereby preventing the phenomenon that the capsule member 11 cannot be fractured due to insufficient pressure.

[0038] In a specific embodiment, a plurality of mounting grooves 16 are provided on the inner walls of the central tube 1 and the lower cone 4 . The depth of the mounting grooves 16 is 2 to 3 mm less than the wall thickness of the central tube 1 or the lower cone 4 . The capsule 11 is located in the mounting grooves 16 .

[0039] In a preferred embodiment, a plugging member 17 for sealing the capsule member 11 is provided at the position of the installation groove 16. Specifically, the plugging member 17 is made of a soluble magnesium alloy material, and the plugging member 17 is bonded to the installation groove 16 by high temperature resistant sealing glue. Through this arrangement, the plugging member 17 can protect the internal capsule member 11 to prevent the capsule member 11 from rupturing prematurely. At the same time, under the bonding effect of the high temperature resistant sealing glue, only a small pressure is required to separate the plugging member 17 from the installation groove 16, so that the drilling fluid contacts the capsule member 11.

[0040] In a specific embodiment, the lower end surface of the central tube 1 is located within the axial length range of the lower cone 4 .

[0041] According to the present invention, Figure 2 As shown, an adapter rod 15 is intermittently coaxially sleeved in the central tube 1, and the adapter rod 15 is connected to the guide slip fixing seat 6 through a shear pin 18. Under this arrangement, the drilling fluid can pass through the annular space between the adapter rod 15 and the central tube 1, thereby reaching the location of the mounting groove 16, thereby causing the capsule 11 to rupture.

[0042] According to the present invention, a method for releasing a soluble bridge plug is also provided. When the self-dissolving soluble bridge plug 100 encounters resistance or gets stuck during entering the well, fluid is pumped into the self-dissolving soluble bridge plug 100 to increase the pressure in the inner cavity of the central pipe 1 and the lower cone 4, thereby squeezing and rupturing the capsule 11, causing the solvent in the capsule 11 to flow out, dissolving the self-dissolving soluble bridge plug, and then completing the release.

[0043] Embodiment 2:

[0044] In a specific embodiment, the central pipe 1 is connected to the lower cone 4 through threads, the lower slip 5 is connected to the lower cone 4 through a conical surface, and the lower slip 5 is connected to the guide shoe slip fixing seat 6 through threads.

[0045] Tungsten carbide coatings are provided on the inner and outer surfaces of the central tube 1, the lower cone 4, the lower slip 5 and the guide slip fixing seat 6.

[0046] Specifically, in this embodiment, a tungsten carbide coating mainly containing tungsten carbide is sprayed as a soluble corrosion-inhibiting particle coating, which can improve the acid resistance of the self-dissolving soluble bridge plug 100. Among them, the content of tungsten carbide in the material mainly containing tungsten carbide is more than 95%.

[0047] According to the present invention, the method for spraying tungsten carbide coating is as follows: a plasma arc driven by direct current is used as a heat source to heat a material mainly containing tungsten carbide to a molten or semi-molten state, and the tungsten carbide is set on the inner and outer surfaces of the central tube 1, the lower cone 4, the lower slip 5 and the guide slip fixing seat 6 by spraying, thereby forming a tungsten carbide coating.

[0048] Furthermore, a molten or semi-molten material containing tungsten carbide as the main body is sprayed onto the inner and outer surfaces of the central tube 1, the lower cone 4, the lower slip 5 and the guide slip fixing seat 6 at a spray speed higher than 150m / s to form a tungsten carbide coating, and the thickness of the tungsten carbide coating is set to 0.5-1.0mm.

[0049] In a preferred embodiment, an acid-resistant resin shatterable protective film is provided on the lower slip 5. The lower slip 5 is anchored by the slip anchoring teeth 7. In order to ensure the biting ability and stability of the lower slip 5, it is necessary to slow down the dissolution rate of the lower slip 5. Therefore, an acid-resistant resin shatterable protective film is provided on the lower slip 5.

[0050] It is easy to understand that the specific composition of the acid-resistant resin shatterable protective film is not the technical key point of the present invention, and will not be repeated here. The acid-resistant resin shatterable protective film can prevent the lower slip 5 from directly contacting the well fluid. The acid-resistant resin shatterable protective film can protect the lower slip 5 from reacting with the well fluid within 24 hours. After 24 hours, the acid-resistant resin shatterable protective film falls off, and the lower slip 5 reacts quickly with the well fluid.

[0051] In a specific embodiment, the dissolved acid-resistant resin liquid is sprayed on the lower slip 5 by a spray gun to form an acid-resistant resin breakable protective film.

[0052] The self-dissolving soluble bridge plug 100 can perform sealing operations under high temperature, high pressure and acidic environment, and can dissolve after a certain period of time, thereby improving work efficiency.

[0053] A plurality of slip anchoring teeth 7 are provided on the outer wall of the lower slip 5. In a preferred embodiment, as Figure 1 As shown, at least four circles of slip anchoring teeth 7 are arranged on the outer wall of the lower slip 5, and the slip anchoring teeth 7 are made of high-strength ceramic particles.

[0054] In a preferred embodiment, the lower slip 5 and the slip anchoring teeth 7 are made of high-strength ceramic particles of 8×5mm or 9.5×7.5mm. After the lower slip 5 is dissolved, the insoluble matter remaining in the well is less than 2%, thereby achieving the effect of facilitating the dissolution of the bridge plug.

[0055] In one embodiment, the central tube 1 and the guide slip fixing seat 6 are made of high temperature resistant soluble magnesium or soluble magnesium alloy.

[0056] In this embodiment, the central pipe 1 and the guide slip fixing seat 6 are made of 7050 aluminum alloy. Under this setting, the self-dissolving soluble bridge plug 100 can withstand a pressure of 70MPa and a temperature range of 150℃ to 200℃, and can withstand pressure, dissolve quickly and completely dissolve within 6 to 10 days after construction in a complex wellbore environment.

[0057] In a preferred embodiment, the thickness of the tungsten carbide coating is set to 0.5-1.0 mm. The tungsten carbide coating prevents the central tube 1, the lower cone 4, the lower slip 5 and the guide slip fixing seat 6 from reacting with 15% hydrochloric acid within 8 hours, delaying the reaction time of the 7050 aluminum alloy with hydrochloric acid, improving the sealing efficiency, and making the bridge plug resistant to ultra-high temperature and acid corrosion.

[0058] In a preferred embodiment, Figure 1 As shown, the center pipe 1 includes a large diameter portion 12 and a small diameter portion 13, and a threaded connection sleeve 9 is provided on the lower outer wall of the small diameter portion 13 of the center pipe 1 through a thread, and the inner wall of the lower cone 4 is connected to the outer wall of the threaded connection sleeve 9 through a ratchet connection. When the bridge plug is set, the lower cone 4 and the center pipe 1 will slide relative to each other, compressing the rubber cylinder 2, so that the lower cone 4 and the rubber cylinder 2 are completely pressed, and the threaded connection sleeve 9 only allows the lower cone 4 to move in one direction relative to the center pipe 1, completing self-locking and preventing the lower cone 4 and the center pipe 1 from separating.

[0059] The central pipe 1 and the lower slip 5 are connected into an integrated structure, which increases the effective diameter of the soluble bridge plug, ensures that the fluid in the well is discharged quickly and without throttling, and improves the efficiency of fracturing after setting. Because before and during the lowering, due to the size of the setting release tool, the inner diameter of the guide slip fixing seat 6 needs to be made relatively small. Once the release is successful, the guide slip fixing seat 6 with a smaller inner diameter will be separated from the upper part of the bridge plug body, so that the effective inner diameter of the overall soluble bridge plug after setting will become larger.

[0060] Combination Figure 2As shown, during the setting process, the adapter connecting rod 15 moves upward relative to the adapter push tube 14, and the adapter connecting rod 15 can drive the guide shoe slip fixing seat 6 to move upward, while the central tube 1 is relatively fixed to the adapter push tube 14, so that the guide shoe slip fixing seat 6 pushes the lower slip 5, the lower cone 4, the rubber cylinder 2, etc. to be compressed, and the rubber cylinder 2 radially expands to complete the sealing, and the lower slip 5 radially expands through the conical surface of the lower cone 4, so that the slip anchoring teeth 7 complete the anchoring. In this process, after the lower cone 4 moves upward, the ratchet between the outer wall of the threaded connection sleeve 9 and the lower cone 4 can prevent the lower cone 4 from moving downward, thereby locking the lower cone 4.

[0061] In a preferred embodiment, the outer walls of both axial ends of the rubber cylinder 2 are tapered. One end of the rubber cylinder 2 extends into the large diameter portion 12 , and the axial end surface and radial outer wall of the rubber cylinder 2 abut against the large diameter portion 12 .

[0062] A metal support ring 3 is provided on the center tube 1, and the metal support ring 3 is provided at one end of the rubber tube 2 away from the large diameter portion 12. The shape of the metal support ring 3 is adapted to the shape of the rubber tube 2, so that the axial end face and the radial outer wall of the rubber tube 2 are both in contact with the metal support ring 3. A lower rubber tube protection ring 8 is provided between the metal support ring 3 and the rubber tube 2, and the shape of the lower rubber tube protection ring 8 is also adapted to the contact surface between the metal support ring 3 and the rubber tube 2.

[0063] In a preferred embodiment, a floating rubber sleeve shoulder ring 10 is provided at one end of the rubber sleeve 2 away from the metal support ring 3, that is, at the end close to the large diameter portion 12. The axial upper end of the floating rubber sleeve shoulder ring 10 abuts against the large diameter portion, and the inner wall of the floating rubber sleeve shoulder ring 10 is set to a shape that matches the cone at the end of the rubber sleeve 2.

[0064] The self-dissolving soluble bridge plug 100 can perform setting, isolation, and sealing pressure-bearing operations in an acidic environment with an ultra-high temperature formation temperature of more than 150°C, a high-pressure working pressure difference of 70MPa, and a hydrochloric acid concentration of 10% or less, thereby providing a safe and efficient interlayer isolation guarantee for ultra-high temperature and dense layers that require ultra-high temperature, high pressure, and acid treatment of the formation, improving the working efficiency of the self-dissolving soluble bridge plug, while not affecting the normal dissolution of the soluble bridge plug after the fracturing is completed, and ensuring the normal channel for drainage and production after fracturing.

[0065] According to the present invention, a sealing and fracturing method is also provided, which uses the self-dissolving soluble bridge plug 100 proposed according to the present invention to perform sealing and fracturing, and includes the following steps.

[0066] Step A: Within 48 hours before the self-dissolving soluble bridge plug 100 is lowered into the oil and gas well, a well cleaning or simulated pumping is performed using a well cleaning gauge of a size corresponding to the oil and gas well or larger.

[0067] Step B: The self-dissolving soluble bridge plug 100 is sent into the well through an adapter, and the vertical well section entry speed is controlled at 50-70 m / min, and the horizontal section entry speed is controlled at 35-40 m / min.

[0068] The connection structure between the adapter and the self-dissolving soluble bridge plug 100 is as follows: Figure 2 The adapter includes an adapter push tube 14 and an adapter connecting rod 15. The guide shoe slip fixing seat 6 of the self-dissolving soluble bridge plug 100 is connected to the lower part of the adapter connecting rod 15, and the lower end of the adapter push tube 14 is connected to the upper end of the central pipe 1 of the self-dissolving soluble bridge plug 100.

[0069] Step C: After the adapter and the self-dissolving soluble bridge plug 100 are put into place, they are set.

[0070] The adapter and the self-dissolving soluble bridge plug 100 are normally lowered into the vertical well section at a speed of 50-70 m / min, and the horizontal well section at a speed of 35-40 m / min. In another embodiment, the horizontal well section is lowered at a speed of 35-50 m / min.

[0071] If the self-dissolving soluble bridge plug 100 is stuck during the lowering process, it can be lifted by lifting the cable to the safe tension that the cable can withstand. If the self-dissolving soluble bridge plug 100 cannot be lifted and loosened, a high concentration (10-15%) potassium chloride aqueous solution or 5-15% hydrochloric acid is injected to quickly dissolve the self-dissolving soluble bridge plug 100. After the self-dissolving soluble bridge plug 100 is dissolved or loosened, the pumping pipe string is removed for inspection. If the self-dissolving soluble bridge plug 100 is set midway and the ignition is lost during the lowering process, high concentration potassium chloride or 5-15% hydrochloric acid can be pumped in to dissolve the self-dissolving soluble bridge plug 100. After the dissolution is completed, the plug is detected, and the powder and debris produced by the dissolution are flushed into the lower part, and a new self-dissolving soluble bridge plug 100 is pumped again.

[0072] Step D: Put the fracturing ball in 30 minutes before fracturing, with a speed of 3 to 4 m 3 / min pumping displacement will pump the fracturing ball into place. When the pumping liquid volume difference is 10m 3 When the casing volume of the target layer is reached, the pumping displacement is increased from 3 to 4 m 3 / min down to 1.5~2m 3 / min, fracturing after the ball is seated.

[0073] In this embodiment, after the sealing is completed in step C, the fracturing operation in step D is carried out within 12 to 18 hours. If the fracturing operation is delayed, 1 to 1.5 times the volume of the wellbore can be pumped into the wellbore to reduce the chloride concentration. During the fracturing process, if sand plugging occurs, the return flow rate is controlled to 15m 3 / min, flow back and flush sand. If sand blockage still occurs, run the coiled tubing to flush sand.

[0074] In the description of the present invention, “plurality” means two or more than two, unless otherwise clearly and specifically defined.

[0075] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0076] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0077] Finally, it should be noted that the above is only a preferred embodiment of the present invention and does not constitute any limitation to the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments or to replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A self-dissolving soluble bridge plug, characterized in that: include: Central tube (1); A rubber sleeve (2) and a lower cone (4) are coaxially sleeved on the outer wall of the central tube (1) in sequence from top to bottom, the upper end of the rubber sleeve (2) is axially abutted against the central tube (1), and an axial gap exists between the lower cone (4) and the rubber sleeve (2); A lower slip (5) is coaxially arranged on the outer wall of the lower end of the lower cone (4); A guide shoe slip fixing seat (6) is coaxially fixedly arranged at the lower end of the lower slip (5); At least one capsule (11) is arranged in the central tube (1) and / or the lower cone (4), and a solvent is arranged in the capsule (11). The capsule (11) can rupture in response to the pressure in the inner cavity of the self-dissolving soluble bridge plug, thereby allowing the solvent in the capsule (11) to flow out.

2. The self-dissolving soluble bridge plug according to claim 1, characterized in that: The capsule member (11) is made of soluble rubber.

3. The self-dissolving soluble bridge plug according to claim 1, characterized in that: The co-solvent includes ferric chloride.

4. The self-dissolving soluble bridge plug according to claim 1, characterized in that: A plurality of mounting grooves (16) are provided on the inner walls of the central tube (1) and the lower cone (4); the depth of the mounting grooves (16) is 2 to 3 mm less than the wall thickness of the central tube (1) or the lower cone (4); and the capsule member (11) is located in the mounting grooves (16).

5. The self-dissolving soluble bridge plug according to claim 4, characterized in that: A sealing member (17) for sealing the capsule member (11) is arranged at the position of the mounting groove (16).

6. The self-dissolving soluble bridge plug according to claim 5, characterized in that: The blocking member (17) is made of a soluble magnesium alloy material.

7. The self-dissolving soluble bridge plug according to claim 6, characterized in that: The blocking member (17) is bonded to the installation groove (16) by means of high temperature resistant sealing glue.

8. The self-dissolving soluble bridge plug according to claim 1, characterized in that: The lower end surface of the central tube (1) is located within the axial length range of the lower cone (4).

9. The self-dissolving soluble bridge plug according to any one of claims 1 to 8, characterized in that: An adapter connecting rod (15) is provided in an intermittent coaxial sleeve in the central tube (1), and the adapter connecting rod (15) is connected to the guide shoe slip fixing seat (6) via a shear pin (18).

10. A method for releasing a soluble bridge plug, characterized in that: When the self-dissolving soluble bridge plug according to any one of claims 1 to 8 encounters resistance or jamming during the process of entering the well, fluid is pumped into the self-dissolving soluble bridge plug to increase the pressure in the inner cavity of the central pipe (1) and the lower cone (4), thereby squeezing and rupturing the capsule (11), allowing the co-solvent in the capsule (11) to flow out, thereby dissolving the self-dissolving soluble bridge plug.

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