Dissolvable bridge plug with upper and lower sealing structures

Abstract

The utility model provides a dissoluble bridge plug with an upper sealing structure and a lower sealing structure, and relates to the technical field of bridge plugs. The dissolvable bridge plug solves the technical problems that an existing dissolvable bridge plug is poor in setting reliability and insufficient in pressure bearing capacity. The dissolvable bridge plug with the upper sealing structure and the lower sealing structure. Comprising a releasing lever, a central shaft, a releasing ring, a bottom support, a lower slip, a lower cone, a lower thrust ring, a lower rubber sleeve, a lower protective cover and a bipyramid, wherein the central shaft is arranged on the upper section of the releasing lever in a sleeving manner and is provided with a central hole; the releasing ring, the bottom support and the lower slip are sequentially stacked from bottom to top and are arranged on the lower section of the releasing lever in a sleeving manner; the lower cone, the lower thrust ring, the lower rubber sleeve, the lower protective cover and the bipyramid are sequentially stacked from bottom to top and are arranged on the central shaft in a sleeving manner; the number of the upper protective covers, the number of the upper rubber barrels, the number of the upper thrust rings, the number of the upper cones, the number of the upper slips, the number of the push discs, the number of the lower rubber barrels and the number of the upper rubber barrels are at least one. The packer is better in setting reliability and higher in pressure bearing capacity.

Description

Technical Field

[0001] This utility model relates to the field of bridge plug technology, specifically to a soluble bridge plug with an upper and lower sealing structure. Background Technology

[0002] Dissolvable bridge plugs are widely used in the oil and gas extraction field. How to scientifically and rationally design the structure of dissolvable bridge plugs to ensure their setting reliability and sufficient pressure bearing capacity has always been a difficult problem in this technical field.

[0003] The existing dissolvable bridge plug is structured as disclosed in Chinese Patent Application No. 202121517196.3. This dissolvable bridge plug includes a central rod, a detachable support body, a slip assembly, a sealing ring, a support ring, and a support cone. When the dissolvable bridge plug is placed inside a casing used for oil and gas extraction, the central rod is pulled up and the support cone is pressed using a setting tool. The slip assembly moves upward and disengages the detachable support body. Simultaneously, as the support cone descends, it compresses the interior of the slip assembly, causing it to expand. The anchoring teeth (referred to as anchor teeth) of the slip assembly abut against the inner wall of the casing, thus firmly setting the dissolvable bridge plug inside the casing. The slip assembly seals the gap between the support cone and the inner wall of the casing, and the sealing ring seals the gap between the support cone and the slip assembly. At this point, a plugging ball is dropped into the casing. When the plugging ball blocks the upper port of the slip assembly, the soluble bridge plug divides the casing into two independent and sealed spaces. Since the height of the casing corresponds to the formation, when the casing is divided into two independent and sealed spaces by the soluble bridge plug, fracturing of formations at different heights can be achieved in different independent spaces, thereby enabling oil and gas extraction from different formations.

[0004] The applicant has discovered that the prior art has at least the following technical problems:

[0005] In existing technologies, dissolvable bridge plugs rely solely on the anchoring teeth of a single slip assembly to press against the inner wall of the sleeve to achieve setting. The slip assembly and anchoring teeth have limited pressure-bearing capacity and cannot withstand high pressures, making them prone to failure. Furthermore, the slip assembly and the support cone rely on friction to achieve a contact seal. When a large pressure is applied above the slip assembly, it is prone to sliding downwards, causing it to easily detach from the support cone and resulting in failure of the contact seal. Consequently, existing dissolvable bridge plugs suffer from poor setting reliability and insufficient pressure-bearing capacity. Utility Model Content

[0006] This utility model provides a soluble bridge plug with an upper and lower sealing structure, which solves the technical problems of poor setting reliability and insufficient pressure bearing capacity of existing soluble bridge plugs.

[0007] The present invention provides the following technical solution:

[0008] This utility model provides a soluble bridge plug with an upper and lower sealing structure, comprising a release lever, a central shaft sleeved on the upper section of the release lever and having a central hole, a release ring, a base, a lower slip, and a lower cone, a lower thrust ring, a lower rubber sleeve, a lower protective cover, a double cone, an upper protective cover, an upper rubber sleeve, an upper thrust ring, an upper cone, an upper slip, and a push plate, all stacked on the central shaft from bottom to top.

[0009] The drop ring is connected to the bottom end of the drop stick (the connection between the drop ring and the bottom end of the drop stick can break when the soluble bridge plug with the upper and lower sealing structure switches to the setting state, and the drop ring falls down accordingly).

[0010] The number of the lower glue tube and the upper glue tube is at least one;

[0011] When the soluble bridge plug with upper and lower sealing structure is placed inside the sleeve and the soluble bridge plug with upper and lower sealing structure is switched to the setting state, the release lever is pulled and the push plate is pressed. (The release lever can push the lower slip upward through the base, and the push plate and the base respectively axially press the upper slip and the lower slip between the push plate and the base.) The outer conical surface of the lower cone can press the lower slip, causing the lower slip to expand radially and anchor to the inner wall of the sleeve. At the same time, the upper rubber cylinder can expand radially and abut against the inner wall of the sleeve under the action of the upper protective cover and the upper thrust ring, and the lower rubber cylinder can expand radially and abut against the inner wall of the sleeve under the squeezing action of the lower protective cover and the lower thrust ring. The upper slip can slide under the pressure of the push plate and is squeezed by the outer conical surface of the upper cone to expand radially and anchor to the inner wall of the sleeve.

[0012] When the soluble bridge plug with upper and lower sealing structures is in the set-sealed state, the frictional force between the upper slip and the sleeve is less than the frictional force between the lower slip and the sleeve.

[0013] Optionally, both the inner conical surface of the lower slip and the outer conical surface of the lower cone are provided with a plurality of anti-disengagement ratchet teeth, and the anti-disengagement ratchet teeth of both are engaged with each other to prevent the lower slip and the lower cone from disengaging from each other in the axial direction.

[0014] The inner conical surface of the upper slip and the outer conical surface of the upper cone are each provided with a number of anti-retraction ratchet teeth, and the anti-retraction ratchet teeth of each are interlocked to prevent the upper slip and the upper cone from disengaging from each other in the axial direction.

[0015] The inner circumferential surface of the lower cone and the outer circumferential surface of the central shaft are each provided with a plurality of limiting ratchet teeth, and the limiting ratchet teeth of each of them mesh with each other to prevent the lower cone and the central shaft from disengaging from each other in the axial direction.

[0016] The lower slip and the upper slip each include a slip body and a plurality of anchor teeth distributed on the outer periphery of the slip body. Except for the anchor teeth, the soluble bridge plug with upper and lower sealing structure is made of soluble or biodegradable material. When the soluble bridge plug with upper and lower sealing structure is in the set-sealing state, the lower slip and the upper slip are respectively anchored to the inner wall of the sleeve by their respective anchor teeth.

[0017] Optionally, the number of rows of anchor teeth in the lower slip is greater than the number of rows of anchor teeth in the upper slip, and the total number of anchor teeth in the lower slip is greater than the total number of anchor teeth in the upper slip.

[0018] Optionally, the number of anti-detachment ratchet teeth is greater than the number of anti-retraction ratchet teeth, and the number of anti-retraction ratchet teeth is greater than the number of limiting ratchet teeth.

[0019] Optionally, the taper of the outer conical surface of the lower cone is smaller than the taper of the outer conical surface of the upper cone.

[0020] Optionally, a reducing ring is threaded onto the inner circumferential surface of the bottom of the central shaft. The reducing ring is sleeved on the release lever. The reducing ring has a plurality of connecting holes, which are evenly distributed radially along the entire circumferential direction of the reducing ring. The cavity between the central shaft and the release lever is connected to the cavity between the lower cone and the release lever through the connecting holes. The inner contour line of the cross-section of the connecting hole is a superior arc.

[0021] Optionally, both the upper thrust ring and the lower thrust ring include an outer thrust ring and an inner thrust ring stacked together. The contact surfaces of the outer and inner thrust rings are both sloped, and limiting protrusions are provided at the edges of the contact surfaces. The limiting protrusions of the outer thrust ring and the limiting protrusions of the inner thrust ring are at the same height. The central hole of the outer thrust ring is heart-shaped, and the central hole of the inner thrust ring is circular. The thinnest sections of both the outer and inner thrust rings are provided with pre-fabricated cracks. The pre-fabricated cracks on the outer thrust ring extend radially to a position close to the limiting protrusions of the inner thrust ring. The pre-fabricated cracks on the inner thrust ring also extend radially to a position close to the limiting protrusions of the outer thrust ring.

[0022] The outer thrust ring of the upper thrust ring abuts against the upper cone, the outer thrust ring of the lower thrust ring abuts against the lower cone, the inner thrust ring of the upper thrust ring abuts against the upper rubber sleeve, and the inner thrust ring of the lower thrust ring abuts against the lower rubber sleeve; the limiting protrusions of the outer and inner thrust rings of the upper thrust ring are embedded in the bottom of the upper cone, and the limiting protrusions of the outer and inner thrust rings of the lower thrust ring are embedded in the top of the lower cone;

[0023] Both the lower and upper protective covers are annular structures with guide cone surfaces on their inner walls. The bottom edge of the upper rubber tube has a chamfered structure, which abuts against the guide cone surface of the upper protective cover. There is a gap between the bottom surface of the upper rubber tube and the bottom port edge of the upper protective cover. The top edge of the lower rubber tube has a chamfered structure, which abuts against the guide cone surface of the lower protective cover. There is a gap between the top surface of the lower rubber tube and the top port edge of the lower protective cover.

[0024] Optionally, the double cone comprises, from top to bottom, an upper cone, a middle cylindrical portion, and a lower cone. The central hole of the double cone is formed by the central holes of the upper cone, the middle cylindrical portion, and the lower cone. The upper cone and the lower cone are symmetrical. Several sealing grooves are provided on the inner circumferential surface of the double cone. Each sealing groove is fitted with a sealing ring sleeved on the central shaft. The sealing ring is made of an elastic, soluble, or biodegradable material.

[0025] The intermediate cylindrical part is made of a soluble or biodegradable elastic material. The intermediate cylindrical part, the upper conical part, and the lower conical part are a separate structure. When the soluble bridge plug with the upper and lower sealing structure is in the set-sealing state, the intermediate cylindrical part can expand in the radial direction and abut against the inner wall of the sleeve after being squeezed by the upper conical part and the lower conical part.

[0026] Optionally, the dissolvable bridge plug with upper and lower sealing structures further includes a connecting nut, which is sleeved on the upper section of the release lever and threaded between the release lever and the inner wall of the central shaft. The top outer circumferential surface and the top inner circumferential surface of the connecting nut are both provided with threads. The connecting nut can form a threaded connection with the setting tool that pulls the release lever through the thread on the top outer circumferential surface of the connecting nut. The connecting nut is also provided with a radial connecting screw hole. The end of the connecting screw that is threaded to the radial connecting screw hole can abut against and lock the release lever lifting test tool that is threaded with the top inner circumferential surface of the connecting nut.

[0027] The application method of the soluble bridge plug with upper and lower sealing structure provided by this utility model includes the following steps:

[0028] Step A: Place the soluble bridge plug with upper and lower sealing structure provided by any of the technical solutions of this utility model inside the sleeve;

[0029] Step B: Pull the release lever and press the push plate. The outer conical surface of the lower cone squeezes the lower slip, causing the lower slip to expand radially and anchor to the inner wall of the sleeve. At the same time, the upper rubber cylinder expands radially under the action of the upper protective cover and the upper thrust ring, and the lower rubber cylinder expands radially under the squeezing action of the lower protective cover and the lower thrust ring, and abuts against the inner wall of the sleeve. The upper slip slides under the pressure of the push plate and is squeezed by the outer conical surface of the upper cone to expand radially and anchor to the inner wall of the sleeve, so that the soluble bridge plug with upper and lower sealing structure switches to the setting state.

[0030] Step C: Insert a plug into the casing and use the plug to seal the upper port of the central shaft. The plug and the soluble bridge plug with upper and lower sealing structure in the set-sealed state will separate the lower and upper parts of the casing. Perform fracturing operations on the soluble bridge plug with upper and lower sealing structure, the casing above the plug, and the formation and extract oil and gas.

[0031] Step D: After the soluble bridge plug with upper and lower sealing structure has been in the set state for a predetermined time, the soluble bridge plug with upper and lower sealing structure dissolves or degrades in the fracturing fluid of the formation inside the casing. The part of the soluble bridge plug with upper and lower sealing structure that is not completely dissolved or degraded falls under its own weight, so that the casing is in the conductive state.

[0032] The above-described technical solutions provided by this utility model embodiment produce at least the following technical effects:

[0033] This utility model provides a soluble bridge plug with an upper and lower sealing structure. Firstly, the lower slipper and lower cone, the upper slipper and upper cone, the upper rubber sleeve, and the lower rubber sleeve together form a four-layer sealing structure that can seal the sleeve (in a preferred embodiment, the intermediate cylindrical part serving as the intermediate rubber sleeve can also form a sealing sleeve structure). Compared to existing soluble bridge plug sealing structures, this utility model has more sealing layers, and the distribution of the sealing structure is not only more uniform and symmetrical, but also has a larger contact area between the sealing structure and the sleeve, resulting in higher sealing reliability and stronger pressure resistance. Secondly, in the preferred embodiment, the interlocking anti-disengagement ratchet prevents the lower slipper and lower cone from separating axially; the interlocking anti-retraction ratchet prevents the upper slipper and upper cone from separating axially; and the interlocking limiting ratchet prevents the lower cone from separating axially. This ensures the connection reliability between the lower slipper and lower cone, between the upper slipper and upper cone, and between the lower cone and central shaft, greatly improving the sealing reliability of the upper and lower sealing structure. The dissolvable bridge plug with upper and lower sealing structures improves the overall connection reliability, setting reliability, and pressure bearing capacity. Furthermore, during the setting process, the upper slip can slide under the pressure of the pusher plate and is squeezed by the outer conical surface of the upper cone, expanding radially until it is anchored to the casing. Simultaneously, when the dissolvable bridge plug with upper and lower sealing structures is in the setting state, the friction between the upper slip and the casing is less than that between the lower slip and the casing. Therefore, even if the upper slip expands to anchor to the casing, it will still slide when subjected to a large thrust from above. The upper and lower rubber sleeves themselves have elasticity and vibration damping properties, acting like a spring. This allows the upper slip to absorb the large thrust from above through a short-stroke sliding motion, reducing the thrust transmitted to the lower slip. Consequently, the setting stability between the lower slip and the casing is stronger, the sealing reliability is higher, and the pressure bearing capacity is stronger. Therefore, this solves the technical problems of poor setting reliability and insufficient pressure bearing capacity of existing dissolvable bridge plugs. Attached Figure Description

[0034] The technical effects of this utility model can be better understood by those skilled in the art through the following figures, wherein:

[0035] Figure 1 This is a plan view of a soluble bridge plug with an upper and lower sealing structure provided for an embodiment of the present invention.

[0036] Figure 2 for Figure 1 The diagram shows a cross-sectional view of a soluble bridge plug with an upper and lower sealing structure.

[0037] Figure 3 This is a cross-sectional schematic diagram of a soluble bridge plug with an upper and lower sealing structure in its natural state, provided as an embodiment of the present invention.

[0038] Figure 4 This is a cross-sectional schematic diagram illustrating the process by which a soluble bridge plug with an upper and lower sealing structure switches from its natural state to its set-sealing state, as provided in an embodiment of this utility model.

[0039] Figure 5 This is a cross-sectional schematic diagram of a soluble bridge plug with an upper and lower sealing structure in a set-sealed state, as provided in an embodiment of the present invention.

[0040] Figure 6 for Figure 5 The diagram shows an enlarged schematic of a soluble bridge plug with an upper and lower sealing structure.

[0041] Figure 7 for Figure 6 An enlarged schematic diagram of part A in the middle.

[0042] Figure 8 This is a planar schematic diagram of a soluble bridge plug with an upper and lower sealing structure and a variable diameter ring, provided as an embodiment of the present invention.

[0043] Figure 9 This is a plan view of the upper thrust ring in a soluble bridge plug with an upper and lower sealing structure, provided as an embodiment of the present invention.

[0044] Figure 10 A plan view of another soluble bridge plug with an upper and lower sealing structure provided for an embodiment of this utility model.

[0045] Figure 11 for Figure 10 The diagram shows a cross-sectional view of a soluble bridge plug with an upper and lower sealing structure.

[0046] Figure 12 for Figure 10 The diagram shows a cross-sectional view illustrating the entire process of a soluble bridge plug with an upper and lower sealing structure switching from its natural state to its set state.

[0047] Markings in the diagram: 1. Release lever; 2. Central shaft; 3. Release ring; 4. Base; 5. Lower slip; 6. Lower cone; 7. Lower thrust ring; 8. Lower rubber sleeve; 9. Lower protective cover; 10. Double cone; 11. Upper protective cover; 12. Upper rubber sleeve; 13. Upper thrust ring; 14. Upper cone; 15. Upper slip; 16. Push plate; 17. Connecting nut; 18. Anti-disengagement ratchet; 19. Anti-reverse ratchet; 2 0. Limiting ratchet; 21. Anchor tooth; 22. Variable diameter ring; 220. Connecting hole; 23. Outer thrust ring; 24. Inner thrust ring; 25. Limiting protrusion; 26. Pre-cast crack; 27. Guide cone surface; 28. Gap; 291. Upper cone; 292. Middle cylindrical part; 293. Lower cone; 294. Sealing groove; 30. Radial connecting screw hole; 31. Setting tool; 32. Sleeve. Detailed Implementation

[0048] The following is a combination of the above appendices Figures 1-12 The preferred embodiments and numerous alternative implementation schemes provided by the present invention will be described in more detail below.

[0049] like Figures 1-12 As shown, this utility model embodiment provides a dissolvable bridge plug with an upper and lower sealing structure, including a release lever 1, a central shaft 2 sleeved on the upper section of the release lever 1 and having a central hole, a release ring 3 stacked from bottom to top and sleeved on the lower section of the release lever 1, a base 4, a lower slip 5, and a lower cone 6, a lower thrust ring 7, a lower rubber sleeve 8, a lower protective cover 9, a double cone 10, an upper protective cover 11, an upper rubber sleeve 12, an upper thrust ring 13, an upper cone 14, an upper slip 15, and a pusher plate 16, wherein:

[0050] The drop ring 3 is connected to the bottom end of the drop lever 1 (the connection between the drop ring 3 and the bottom end of the drop lever 1 breaks when the soluble bridge plug with the upper and lower sealing structure switches to the setting state, and the drop ring 3 falls down accordingly).

[0051] The number of each of the lower glue cylinder 8 and the upper glue cylinder 12 is at least one; the number of each of the lower glue cylinder 8 and the upper glue cylinder 12 may also be two or more.

[0052] When the soluble bridge plug with upper and lower sealing structure is placed inside the sleeve 32 and the soluble bridge plug with upper and lower sealing structure is switched to the setting state, pull the release lever 1 and press the push plate 16. (The release lever 1 pushes the lower slip 5 upward through the base support 4. The push plate 16 and the base support 4 respectively axially press the upper slip 15 and the lower slip 5 between the push plate 16 and the base support 4.) The outer conical surface of the lower cone 6 can press the lower slip 5, causing the lower slip 5 to expand radially and anchor to the inner wall of the sleeve 32. At the same time, the upper rubber sleeve 12 is on the upper protective cover 11 and the upper thrust ring 13. Under the action of the lower rubber sleeve 8 and the squeezing action of the lower protective cover 9 and the lower thrust ring 7, the lower rubber sleeve 8 can expand in the radial direction and abut against the inner wall of the sleeve 32 (the lower rubber sleeve 8 forms a lower sealing structure after expansion, and the upper rubber sleeve 12 forms an upper sealing structure after expansion). The upper slip 15 can slide under the pressure of the push plate 16 and be squeezed by the outer conical surface of the upper cone 14 to expand in the radial direction and anchor to the inner wall of the sleeve 32. When the soluble bridge plug with upper and lower sealing structures is in the setting state, the friction between the upper slip 15 and the sleeve 32 is less than the friction between the lower slip 5 and the sleeve 32.

[0053] As an optional embodiment of this utility model, in this embodiment, both the inner conical surface of the lower slip 5 and the outer conical surface of the lower cone 6 are provided with a plurality of anti-disengagement ratchet teeth 18, and the anti-disengagement ratchet teeth 18 of both are engaged with each other to prevent the lower slip 5 and the lower cone 6 from disengaging from each other in the axial direction; both the inner conical surface of the upper slip 15 and the outer conical surface of the upper cone 14 are provided with a plurality of anti-retraction ratchet teeth 19, and the anti-retraction ratchet teeth 19 of both are engaged with each other to prevent the upper slip 15 and the upper cone 14 from disengaging from each other in the axial direction; both the inner circumferential surface of the lower cone 6 and the outer circumferential surface of the central shaft 2 are provided with a plurality of limiting ratchet teeth 20, and the limiting ratchet teeth 20 of both are engaged with each other to prevent the lower cone 6 and the central shaft 2 from disengaging from each other in the axial direction.

[0054] The soluble bridge plug with upper and lower sealing structures provided by this utility model has, on the one hand, a four-layer sealing structure consisting of the lower slip 5 and lower cone 6, the upper slip 15 and upper cone 14, the upper rubber sleeve 12, and the lower rubber sleeve 8, which can seal the sleeve 32 (in a preferred embodiment, the middle cylindrical part 292 of the rubber sleeve in the middle position can also form a sealing structure for the sleeve). Compared with the existing sealing structures of soluble bridge plugs, this utility model has more sealing layers, and the distribution of the sealing structure is not only more uniform and symmetrical, but also the sealing structure and the sleeve 32 are more evenly and symmetrically distributed. The larger contact area results in higher sealing reliability and stronger pressure resistance. Furthermore, in the preferred embodiment, the interlocking anti-disengagement ratchet 18 prevents the lower slip 5 and lower cone 6 from disengaging axially; the interlocking anti-reverse ratchet 19 prevents the upper slip 15 and upper cone 14 from disengaging axially; and the interlocking limiting ratchet 20 prevents the lower cone 6 and central shaft 2 from disengaging axially. This ensures proper sealing between the lower slip 5 and lower cone 6, between the upper slip 15 and upper cone 14, and between the lower cone 6 and central shaft. The improved connection reliability between the two components significantly enhances the overall connection reliability, setting reliability, and pressure resistance of the soluble bridge plug with upper and lower sealing structures. Furthermore, during the setting process of this soluble bridge plug with upper and lower sealing structures, the upper slip 15 slides under the pressure of the pusher 16 and is compressed by the outer conical surface of the upper cone 14 during sliding, expanding radially until it is anchored to the sleeve 32. Simultaneously, when the soluble bridge plug with upper and lower sealing structures is in the setting state, the friction between the upper slip 15 and the sleeve 32 is less than that between the lower slip 5 and the sleeve 32. The friction between the tubes 32 means that even if the upper slip 15 expands to anchor itself on the sleeve 32, it will still slide when subjected to a large thrust from above. The upper rubber sleeve 12 and the lower rubber sleeve 8 themselves have elasticity and vibration damping functions, thus acting like a spring. This allows the upper slip 15 to absorb the large thrust from above through short-stroke sliding, reducing the thrust transmitted to the lower slip 5. Consequently, the setting stability between the lower slip 5 and the sleeve 32 is stronger, the sealing reliability is higher, and the pressure resistance is stronger.

[0055] As an optional embodiment of this utility model, in this embodiment, the lower slip 5 and the upper slip 15 each include a slip body and a plurality of anchor teeth 21 distributed on the outer periphery of the slip body. Except for the anchor teeth 21, the soluble bridge plug with upper and lower sealing structure is made of soluble or biodegradable material. When the soluble bridge plug with upper and lower sealing structure is in the setting state, the lower slip 5 and the upper slip 15 are respectively anchored to the inner wall of the sleeve 32 by their respective anchor teeth 21.

[0056] The anchor tooth 21 is preferably made of ceramic material. Ceramic material has the advantages of high hardness and strong pressure resistance. The anchor tooth 21 has a small overall volume and occupies little space, and will not block the liquid channel inside the sleeve 32 even if it fails to degrade or dissolve.

[0057] As an optional embodiment of this utility model, in this embodiment, the number of rows of anchor teeth 21 in the lower slip 5 is greater than the number of rows of anchor teeth 21 in the upper slip 15, and the total number of anchor teeth 21 in the lower slip 5 is greater than the total number of anchor teeth 21 in the upper slip 15.

[0058] The above structure ensures that when the soluble bridge plug with upper and lower sealing structures is in the setting state, the friction between the upper slip 15 and the sleeve 32 is less than the friction between the lower slip 5 and the sleeve 32. This results in a setting structure where the lower slip 5 and the lower cone 6 are stationary, while the upper slip 15 and the upper cone 14 can slide slightly downwards to buffer the pressure above.

[0059] As an optional embodiment of this utility model, in this embodiment, the number of anti-detachment ratchet teeth 18 is greater than the number of anti-retraction ratchet teeth 19, and the number of anti-retraction ratchet teeth 19 is greater than the number of limiting ratchet teeth 20.

[0060] The anti-dislodge ratchet 18, the anti-reverse ratchet 19, and the anti-reverse ratchet 19 all increase the stability of the soluble bridge plug with upper and lower sealing structures when it is in the setting state. The above structure ensures that when the soluble bridge plug with upper and lower sealing structures is in the setting state, the reliability of the anti-dislodge ratchet 18 on the lower slip 5 and the lower cone 6, which has the highest stability requirement, is greater than that of the anti-reverse ratchet 19 on the upper slip 15 and the upper cone 14, and also greater than that of the limiting ratchet 20 on the lower cone 6 and the central shaft 2, thereby ensuring overall stability.

[0061] As an optional embodiment of this utility model, in this embodiment, the taper of the outer conical surface of the lower cone 6 is smaller than the taper of the outer conical surface of the upper cone 14. The lower cone 6 has the highest stability requirement, so its structural design requires stronger pressure-bearing capacity. The smaller the taper, the smaller the radial component of the force and the larger the axial component of the force. The axial compressive strength of the cone structure is stronger than that of the radial component. Therefore, the smaller the taper, the stronger the ability of the lower cone 6 to bear axial pressure.

[0062] As an optional embodiment of this utility model, in this embodiment, a variable diameter ring 22 is threadedly connected to the bottom inner circumferential surface of the central shaft 2. The variable diameter ring 22 is sleeved on the release lever 1. The variable diameter ring 22 is provided with a plurality of connecting holes 220. The plurality of connecting holes 220 are evenly distributed radially along the entire circumferential direction of the variable diameter ring 22. The cavity between the central shaft 2 and the release lever 1 is connected to the cavity between the lower cone 6 and the release lever 1 through the connecting holes 220. The inner contour line of the cross-section of the connecting hole 220 is an arc line.

[0063] The variable diameter ring 22 provides radial support and axial guidance for the release lever 1, thus ensuring the positional accuracy of the release lever 1 in the pulling direction. The connecting hole 220 ensures that the internal pressure of the chamber between the central shaft 2 and the release lever 1 is consistent with that of the chamber between the lower cone 6 and the release lever 1, thus ensuring that the release lever 1 can be pulled out smoothly.

[0064] As an optional embodiment of this utility model, in this embodiment, both the upper thrust ring 13 and the lower thrust ring 7 include an outer thrust ring 23 and an inner thrust ring 24 stacked together. The contact surfaces of the outer thrust ring 23 and the inner thrust ring 24 are both sloped, and each contact surface has a limiting protrusion 25 at its edge. The limiting protrusion 25 of the outer thrust ring 23 and the limiting protrusion 25 of the inner thrust ring 24 are at the same height. The center hole of the outer thrust ring 23 is a peach shape. The inner thrust ring 24 has a circular central hole and pre-fabricated cracks 26 in the thinnest sections of both the outer thrust ring 23 and the inner thrust ring 24. The pre-fabricated cracks 26 on the outer thrust ring 23 extend radially to a position close to the limiting protrusion 25 of the inner thrust ring 24; the pre-fabricated cracks 26 on the inner thrust ring 24 extend radially to a position close to the limiting protrusion 25 of the outer thrust ring 23.

[0065] The outer thrust ring 23 of the upper thrust ring 13 abuts against the upper cone 14, the outer thrust ring 23 of the lower thrust ring 7 abuts against the lower cone 6, the inner thrust ring 24 of the upper thrust ring 13 abuts against the upper rubber sleeve 12, and the inner thrust ring 24 of the lower thrust ring 7 abuts against the lower rubber sleeve 8; the limiting protrusions 25 of the outer thrust ring 23 and the inner thrust ring 24 of the upper thrust ring 13 are embedded in the bottom of the upper cone 14, and the limiting protrusions 25 of the outer thrust ring 23 and the inner thrust ring 24 of the lower thrust ring 7 are embedded in the top of the lower cone 6.

[0066] The design of the above structure allows the upper thrust ring 13 and lower thrust ring 7 to expand smoothly in the radial direction along with the upper rubber sleeve 12 and lower rubber sleeve 8 when under pressure, thus providing good support for the upper rubber sleeve 12 and lower rubber sleeve 8. The design of the pre-fabricated crack 26 can reduce the resistance that the upper thrust ring 13 and lower thrust ring 7 need to overcome in the radial direction, and also ensures that the outer thrust ring 23 and inner thrust ring 24 are both annular before the upper thrust ring 13 and lower thrust ring 7 are set, which has sufficient strength and facilitates production and installation.

[0067] As an optional embodiment of this utility model, both the lower protective cover 9 and the upper protective cover 11 are annular structures with guide cone surfaces 27 on their inner walls. The bottom edge of the upper rubber tube 12 is provided with a chamfer structure, which abuts against the guide cone surface 27 of the upper protective cover 11. There is a gap 28 between the bottom surface of the upper rubber tube 12 and the bottom port edge of the upper protective cover 11. The top edge of the lower rubber tube 8 is provided with a chamfer structure, which abuts against the guide cone surface 27 of the lower protective cover 9. There is a gap 28 between the top surface of the lower rubber tube 8 and the top port edge of the lower protective cover 9.

[0068] The existence of the aforementioned gap 28 provides a certain space for the axial deformation of the upper glue cylinder 12 and the lower glue cylinder 8. This ensures that the lower protective cover 9 and the upper protective cover 11 have sufficient installation space. On the other hand, when the upper glue cylinder 12 and the lower glue cylinder 8 undergo axial deformation, the axial pressure on the lower protective cover 9 and the upper protective cover 11 gradually increases, preventing damage due to the rapid increase in axial pressure caused by the axial deformation of the upper glue cylinder 12 and the lower glue cylinder 8.

[0069] In an optional embodiment of this utility model, the double cone 10, from top to bottom, includes an upper cone portion 291, a middle cylindrical portion 292, and a lower cone portion 293. The central hole of the double cone 10 is formed by the central holes of the upper cone portion 291, the middle cylindrical portion 292, and the lower cone portion 293. The upper cone portion 291 and the lower cone portion 293 have a symmetrical structure. Several sealing grooves 294 are provided on the inner circumferential surface of the double cone 10. Each sealing groove 294 contains a sealing ring fitted on the central shaft 2. The sealing ring is made of an elastic, soluble, or biodegradable material. The cooperation between the sealing ring and the sealing grooves 294 improves the reliability of the seal between the double cone 10 and the central shaft 2.

[0070] As an optional embodiment of this utility model, in this embodiment, the intermediate cylindrical portion 292 is made of a soluble or biodegradable elastic material. The intermediate cylindrical portion 292, the upper conical portion 291, and the lower conical portion 293 are separate structures. When the soluble bridge plug with upper and lower sealing structures is in the set-sealing state, the intermediate cylindrical portion 292 can expand radially and abut against the inner wall of the sleeve 32 after being squeezed by the upper conical portion 291 and the lower conical portion 293 (the intermediate cylindrical portion 292 is a rubber tube set in the middle position, which forms a sealing structure in the middle position after expansion). This structure can make the overall structure a soluble bridge plug with upper, middle, and lower three-level sealing structures, thereby more effectively ensuring its sealing performance.

[0071] As an optional embodiment of this utility model, the dissolvable bridge plug with upper and lower sealing structure in this embodiment also includes a connecting nut 17. The connecting nut 17 is sleeved on the upper section of the release lever 1 and threaded between the release lever 1 and the inner wall of the central shaft 2. The top outer circumferential surface and the top inner circumferential surface of the connecting nut 17 are both provided with threads. The connecting nut 17 can form a threaded connection with the setting tool 31 that pulls the release lever 1 through the thread on the top outer circumferential surface of the connecting nut 17. The connecting nut 17 is also provided with a radial connecting screw hole 30. The end of the connecting screw that is threaded to the radial connecting screw hole 30 can abut against and lock the release lever 1 lifting test tool that is threaded with the top inner circumferential surface of the connecting nut 17.

[0072] The connecting nut 17 connects the release lever 1 and the central shaft 2 together, and becomes the component connecting the setting tool 31, the release lever 1, and the central shaft 2. The presence of the connecting nut 17 reduces the processing difficulty of the release lever 1 and the central shaft 2. At the same time, the connecting nut 17 can be matched and designed according to the structure of the setting tool 31 and the release lever 1 lifting test tool, which facilitates the implementation of the setting operation.

[0073] The application method of the soluble bridge plug with upper and lower sealing structure provided by this utility model includes the following steps:

[0074] Step A: Place the soluble bridge plug with upper and lower sealing structure provided by any of the technical solutions of this utility model inside the sleeve 32;

[0075] Step B: Pull the release lever 1 and press the push plate 16. (The release lever 1 pushes the lower slip 5 upward through the base 4. The push plate 16 and the base 4 respectively axially press the upper slip 15 and the lower slip 5 between the push plate 16 and the base 4.) The outer cone surface of the lower cone 6 presses the lower slip 5, causing the lower slip 5 to expand radially and anchor to the inner wall of the sleeve 32. At the same time, the upper rubber cylinder 12 expands radially under the action of the upper protective cover 11 and the upper thrust ring 13, and the lower rubber cylinder 8 expands radially under the squeezing action of the lower protective cover 9 and the lower thrust ring 7, and abuts against the inner wall of the sleeve 32. The upper slip 15 slides under the pressure of the push plate 16 and is squeezed by the outer cone surface of the upper cone 14 to expand radially and anchor to the inner wall of the sleeve 32, so that the soluble bridge plug with the upper and lower sealing structure switches to the setting state.

[0076] Step C: Insert a plug into the casing 32 to seal the upper port of the central shaft 2. The plug and the soluble bridge plug with upper and lower sealing structure in the set state will separate the lower and upper parts of the casing 32. Fracturing operation will be carried out on the soluble bridge plug with upper and lower sealing structure and the casing 32 and formation above the plug and the casing to extract oil and gas.

[0077] Step D: After the soluble bridge plug with upper and lower sealing structure has been in the set state for a predetermined time, the soluble bridge plug with upper and lower sealing structure dissolves or degrades in the fracturing fluid of the formation within the casing 32. The portion of the soluble bridge plug with upper and lower sealing structure that is not completely dissolved or degraded falls under its own weight, so that the casing 32 is in the conductive state.

[0078] This invention solves the technical problems of poor setting reliability and insufficient pressure bearing capacity of existing soluble bridge plugs. Therefore, when this invention is applied to oil and gas extraction, it not only has higher reliability, but is also applicable to a wider variety and number of oil and gas wells.

[0079] The above technical solutions are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A soluble bridge plug with upper and lower sealing structures, characterized in that: The device includes a release lever, a central shaft with a central hole fitted onto the upper section of the release lever, a release ring stacked from bottom to top and fitted onto the lower section of the release lever, a base, a lower slip, and a lower cone, a lower thrust ring, a lower rubber sleeve, a lower protective cover, a double cone, an upper protective cover, an upper rubber sleeve, an upper thrust ring, an upper cone, an upper slip, and a push plate stacked from bottom to top and fitted onto the central shaft. The drop ring is connected to the bottom end of the drop stick; The number of the lower glue cylinder and the upper glue cylinder is at least one; When the soluble bridge plug with upper and lower sealing structure is placed inside the sleeve and the soluble bridge plug with upper and lower sealing structure is switched to the setting state, the release lever is pulled and the push plate is pressed. The outer conical surface of the lower cone can squeeze the lower slip, causing the lower slip to expand radially and anchor to the inner wall of the sleeve. At the same time, the upper rubber cylinder can expand radially and abut against the inner wall of the sleeve under the action of the upper protective cover and the upper thrust ring, and the lower rubber cylinder can expand radially and abut against the inner wall of the sleeve under the squeezing action of the lower protective cover and the lower thrust ring. The upper slip can slide under the pressure of the push plate and is squeezed by the outer conical surface of the upper cone to expand radially and anchor to the inner wall of the sleeve. When the soluble bridge plug with upper and lower sealing structures is in the set-sealed state, the frictional force between the upper slip and the sleeve is less than the frictional force between the lower slip and the sleeve.

2. The soluble bridge plug with upper and lower sealing structures according to claim 1, characterized in that: The inner conical surface of the lower slip and the outer conical surface of the lower cone are each provided with a number of anti-disengagement ratchet teeth, and the anti-disengagement ratchet teeth of each are interlocked to prevent the lower slip and the lower cone from disengaging from each other in the axial direction. The inner conical surface of the upper slip and the outer conical surface of the upper cone are each provided with a number of anti-retraction ratchet teeth, and the anti-retraction ratchet teeth of each are interlocked to prevent the upper slip and the upper cone from disengaging from each other in the axial direction. The inner circumferential surface of the lower cone and the outer circumferential surface of the central shaft are each provided with a plurality of limiting ratchet teeth, and the limiting ratchet teeth of each of them mesh with each other to prevent the lower cone and the central shaft from disengaging from each other in the axial direction. The lower slip and the upper slip each include a slip body and a plurality of anchor teeth distributed on the outer periphery of the slip body. Except for the anchor teeth, the soluble bridge plug with upper and lower sealing structure is made of soluble or biodegradable material. When the soluble bridge plug with upper and lower sealing structure is in the set-sealing state, the lower slip and the upper slip are respectively anchored to the inner wall of the sleeve by their respective anchor teeth.

3. The soluble bridge plug with upper and lower sealing structures according to claim 2, characterized in that: The number of rows of anchor teeth in the lower slip is greater than the number of rows of anchor teeth in the upper slip, and the total number of anchor teeth in the lower slip is greater than the total number of anchor teeth in the upper slip.

4. The soluble bridge plug with upper and lower sealing structures according to claim 2, characterized in that: The number of anti-detachment ratchet teeth is greater than the number of anti-retraction ratchet teeth, and the number of anti-retraction ratchet teeth is greater than the number of limiting ratchet teeth.

5. The soluble bridge plug with upper and lower sealing structures according to claim 1, characterized in that: The taper of the outer cone surface of the lower cone is smaller than the taper of the outer cone surface of the upper cone.

6. The soluble bridge plug with upper and lower sealing structures according to claim 1, characterized in that: A reducing ring is threaded onto the inner circumferential surface of the bottom of the central shaft. The reducing ring is fitted onto the release lever. The reducing ring has several connecting holes, which are evenly distributed radially along the entire circumferential direction of the reducing ring. The cavity between the central shaft and the release lever is connected to the cavity between the lower cone and the release lever through the connecting holes. The inner contour line of the cross-section of the connecting hole is a superior arc.

7. The soluble bridge plug with upper and lower sealing structures according to claim 1, characterized in that: Both the upper and lower thrust rings include an outer thrust ring and an inner thrust ring stacked together. The contact surfaces of both the outer and inner thrust rings are sloped, and each contact surface has a limiting protrusion at its edge. The limiting protrusions of the outer and inner thrust rings are at the same height. The center hole of the outer thrust ring is heart-shaped, and the center hole of the inner thrust ring is circular. Pre-fabricated cracks are provided in the thinnest sections of both the outer and inner thrust rings. These pre-fabricated cracks on the outer thrust ring extend radially to a position close to the limiting protrusion of the inner thrust ring. The pre-fabricated crack on the inner thrust ring extends radially along the inner thrust ring to a position close to the limiting protrusion of the outer thrust ring; the outer thrust ring of the upper thrust ring abuts against the upper cone, the outer thrust ring of the lower thrust ring abuts against the lower cone, the inner thrust ring of the upper thrust ring abuts against the upper rubber sleeve, and the inner thrust ring of the lower thrust ring abuts against the lower rubber sleeve; the limiting protrusions of both the outer and inner thrust rings of the upper thrust ring are embedded in the bottom of the upper cone, and the limiting protrusions of both the outer and inner thrust rings of the lower thrust ring are embedded in the top of the lower cone.

8. The soluble bridge plug with upper and lower sealing structures according to claim 1, characterized in that: Both the lower and upper protective covers are annular structures with guide cone surfaces on their inner walls. The bottom edge of the upper rubber tube has a chamfered structure, which abuts against the guide cone surface of the upper protective cover. There is a gap between the bottom surface of the upper rubber tube and the bottom port edge of the upper protective cover. The top edge of the lower rubber tube has a chamfered structure, which abuts against the guide cone surface of the lower protective cover. There is a gap between the top surface of the lower rubber tube and the top port edge of the lower protective cover.

9. The soluble bridge plug with upper and lower sealing structures according to claim 1, characterized in that: The double cone comprises, from top to bottom, an upper cone, a middle cylindrical portion, and a lower cone. The central hole of the double cone is formed by the central holes of the upper cone, the middle cylindrical portion, and the lower cone. The upper cone and the lower cone are symmetrical. Several sealing grooves are provided on the inner circumferential surface of the double cone. Each sealing groove is fitted with a sealing ring sleeved on the central shaft. The sealing ring is made of an elastic, soluble, or biodegradable material. The intermediate cylindrical part is made of a soluble or biodegradable elastic material. The intermediate cylindrical part, the upper conical part, and the lower conical part are three separate structures. When the soluble bridge plug with the upper and lower sealing structure is in the set-sealing state, the intermediate cylindrical part can expand in the radial direction and abut against the inner wall of the sleeve after being squeezed by the upper conical part and the lower conical part.

10. The soluble bridge plug with upper and lower sealing structures according to claim 1, characterized in that: The soluble bridge plug with upper and lower sealing structures also includes a connecting nut. The connecting nut is sleeved on the upper section of the release lever and threaded between the release lever and the inner wall of the central shaft. The top outer circumferential surface and the top inner circumferential surface of the connecting nut are both threaded. The connecting nut can form a threaded connection with the setting tool that pulls the release lever through the thread on the top outer circumferential surface of the connecting nut. The connecting nut is also provided with a radial connecting screw hole. The end of the connecting screw that is threaded to the radial connecting screw hole can abut against and lock the release lever lifting test tool that is threaded with the top inner circumferential surface of the connecting nut.

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