Dissolvable bridge plug with upper and lower sealing structures and application method of dissolvable bridge plug

Abstract

The invention provides a dissoluble bridge plug with an upper sealing structure and a lower sealing structure and an application method of the dissoluble bridge plug, 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] The invention relates to the technical field of bridge plugs, and in particular to a soluble bridge plug with upper and lower sealing structures and an application method thereof. Background Art

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

[0003] The soluble bridge plug in the prior art is disclosed in the Chinese patent document with application number 202121517196.3. The soluble bridge plug includes a center rod, a detachable support body, a slip assembly, a sealing ring, a support ring and a support cone. When the soluble bridge plug is placed in a casing for oil and gas extraction, the center rod is lifted and the support cone is pressed by a setting tool, and the slip assembly goes up and pushes off the detachable support body through the slip assembly. At the same time, during the downward movement of the support cone, the support cone squeezes the inside of the slip assembly so that the slip assembly expands, and the anchor teeth (referred to as anchor teeth) of the slip assembly will push against the inner wall of the casing so that the soluble bridge plug is firmly set in the casing, and the slip assembly blocks the gap between the support cone and the inner wall of the casing, and the sealing ring blocks the gap between the support cone and the slip assembly. At this time, a plugging ball is dropped into the casing, and when the plugging ball blocks the upper port of the slip assembly, the soluble bridge plug will separate the casing into two independent and sealed spaces. Since the height of the casing corresponds to the formation, when the casing is separated into two independent and sealed spaces by the soluble bridge plug, the fracturing of formations at different heights can be achieved in different independent spaces, thereby extracting oil and gas in different formations.

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

[0005] In the prior art, the soluble bridge plug only relies on the anchoring teeth of a slip assembly to press against the inner wall of the casing to achieve sealing. The slip assembly and the anchoring teeth have limited pressure-bearing capacity and cannot withstand high pressure, and are prone to failure. At the same time, the slip assembly and the support cone rely on friction to achieve a contact sealing connection. When a large pressure is applied from above the slip assembly, the slip assembly is prone to slide downward under pressure, making it easy for the slip assembly to disengage from the support cone and causing the contact sealing connection to fail. As a result, the existing soluble bridge plug has technical problems such as poor sealing reliability and insufficient pressure-bearing capacity. Summary of the invention

[0006] The embodiment of the present invention provides a soluble bridge plug with upper and lower sealing structures and an application method thereof, which solves the technical problems of poor setting reliability and insufficient pressure bearing capacity of existing soluble bridge plugs.

[0007] The embodiment of the present invention provides the following technical solutions:

[0008] A dissolvable bridge plug with an upper and lower sealing structure provided in an embodiment of the present invention comprises a release lever, a central shaft sleeved on the upper section of the release lever and having a central hole, a release ring, a bottom bracket, a lower slip stacked in sequence from bottom to top and sleeved on the lower section of the release lever, and a lower cone, a lower thrust ring, a lower rubber cylinder, a lower protective cover, a double cone, an upper protective cover, an upper rubber cylinder, an upper thrust ring, an upper cone, an upper slip and a push plate stacked in sequence from bottom to top and sleeved on the central shaft, wherein:

[0009] The release ring is connected to the bottom end of the release lever (the connection between the release ring and the bottom end of the release lever can be broken when the soluble bridge plug with upper and lower sealing structures is switched to the setting state, and the release ring falls accordingly);

[0010] The number of the lower rubber cylinder and the number of the upper rubber cylinder are at least one;

[0011] When the soluble bridge plug with upper and lower sealing structures is placed in the casing and the soluble bridge plug with upper and lower sealing structures 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 bottom bracket, and the push plate and the bottom bracket respectively axially squeeze the upper slip and the lower slip between the push plate and the bottom bracket) the outer conical surface of the lower cone can squeeze the lower slip so that the lower slip expands in the radial direction and anchors to the inner wall of the casing, and at the same time, the upper rubber cylinder can expand in the radial direction and press against the inner wall of the casing under the action of the upper protective cover and the upper thrust ring, and the lower rubber cylinder can expand in the radial direction under the extrusion of the lower protective cover and the lower thrust ring, and the upper slip can slide under the pressure of the push plate and be squeezed by the outer conical surface of the upper cone to expand in the radial direction and anchor to the inner wall of the casing;

[0012] When the soluble bridge plug with upper and lower sealing structures is in a set state, the friction force between the upper slip and the casing is smaller than the friction force between the lower slip and the casing.

[0013] Optionally, the inner conical surface of the lower slip and the outer conical surface of the lower cone are each provided with a plurality of anti-slip ratchets, and the anti-slip ratchets of the two respectively engage with each other to prevent the lower slip and the lower cone from being detached 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 both provided with a plurality of stop ratchet teeth, and the stop ratchet teeth of the two mesh with each other to prevent the upper slip and the upper cone from being disengaged from each other in the axial direction;

[0015] The inner circumference of the lower cone and the outer circumference of the central shaft are both provided with a plurality of position-limiting ratchets, and the position-limiting ratchets of the two respective ones are engaged with each other to prevent the lower cone and the central shaft from being disengaged 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 peripheral surface of the slip body. The soluble bridge plug with upper and lower sealing structures is made of soluble or degradable materials except the anchor teeth. When the soluble bridge plug with upper and lower sealing structures is in a setting state, the lower slip and the upper slip are respectively anchored to the inner wall of the casing through their respective anchor teeth.

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

[0018] Optionally, the number of the anti-slip ratchets is greater than the number of the stop-retreat ratchets, and the number of the stop-retreat ratchets is greater than the number of the limiting ratchets.

[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 threadedly connected to the inner circumferential surface of the bottom of the central shaft, the reducing ring is sleeved on the release lever, a plurality of communicating holes are provided on the reducing ring, and the plurality of communicating holes are evenly distributed in a radial shape along the entire circumferential direction of the reducing ring; the chamber between the central shaft and the release lever is connected to the chamber between the lower cone and the release lever through the communicating holes, and the inner contour line of the cross section of the communicating hole is a major arc line.

[0021] Optionally, the upper thrust ring and the lower thrust ring each include an outer thrust ring and an inner thrust ring stacked together, the contact surfaces of the outer thrust ring and the inner thrust ring are sloped surfaces, and limiting protrusions are arranged at the edges of the contact surfaces; the limiting protrusion of the outer thrust ring is at the same height as the limiting protrusion of the inner thrust ring, the center hole of the outer thrust ring is heart-shaped, and the center hole of the inner thrust ring is circular, and the thinnest sections of the outer thrust ring and the inner thrust ring are each provided with prefabricated cracks, and the prefabricated cracks on the outer thrust ring extend along the radial direction of the outer thrust ring to a position close to the limiting protrusion of the inner thrust ring; the prefabricated cracks on the inner thrust ring extend along the radial direction of the inner thrust ring to a position close to the limiting protrusion 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 tube, and the inner thrust ring of the lower thrust ring abuts against the lower rubber tube; the respective limiting protrusions of the outer thrust ring and the inner thrust ring of the upper thrust ring are embedded in the bottom of the upper cone, and the respective limiting protrusions of the outer thrust ring and the inner thrust ring of the lower thrust ring are embedded in the top of the lower cone;

[0023] Both the lower protective cover and the upper protective cover are annular structures with a guide cone surface on the inner wall. The edge of the bottom surface of the upper rubber cylinder is provided with a chamfered structure and abuts against the guide cone surface of the upper protective cover through the chamfered structure, and there is a gap between the bottom surface of the upper rubber cylinder and the edge of the bottom port of the upper protective cover; the edge of the top surface of the lower rubber cylinder is provided with a chamfered structure and abuts against the guide cone surface of the lower protective cover through the chamfered structure, and there is a gap between the top surface of the lower rubber cylinder and the edge of the top port of the lower protective cover.

[0024] Optionally, the double cone includes an upper cone portion, an intermediate cylindrical portion and a lower cone portion from top to bottom, the center hole of the double cone is formed by the center holes of the upper cone portion, the intermediate cylindrical portion and the lower cone portion, the upper cone portion and the lower cone portion are symmetrical structures, a plurality of sealing grooves are arranged on the inner circumference of the double cone, each of the sealing grooves is embedded with a sealing ring sleeved on the central axis, and the sealing ring is made of an elastic soluble material or a degradable material;

[0025] The middle cylindrical portion is made of a soluble or degradable elastic material. The middle cylindrical portion, the upper cone portion and the lower cone portion are split structures. When the soluble bridge plug with upper and lower sealing structures is in a set state, the middle cylindrical portion can expand in the radial direction and press against the inner wall of the casing after being squeezed by the upper cone portion and the lower cone portion.

[0026] Optionally, the soluble bridge plug with upper and lower sealing structures also includes a connecting nut, which is sleeved on the upper section of the release rod and threadedly connected between the release rod and the inner wall of the central shaft, and the top outer circumferential surface and the top inner circumferential surface of the connecting nut are both provided with threads, and the connecting nut can form a threaded connection with a sealing tool that pulls the release rod through the threads on the top outer circumferential surface of the connecting nut; radial connecting screw holes are also provided on the connecting nut, and the end of the connecting screw threadedly connected to the radial connecting screw hole can abut and lock the release rod pulling test tool that cooperates with the thread of the top inner circumferential surface of the connecting nut.

[0027] The application method of the soluble bridge plug with upper and lower sealing structures provided by the present invention comprises the following steps:

[0028] Step A, placing the dissolvable bridge plug with upper and lower sealing structures provided by any technical solution of the present invention in the casing;

[0029] Step B, pulling the release lever and pressing the push plate, the outer cone surface of the lower cone squeezes the lower slip so that the lower slip expands in the radial direction and is anchored on the inner wall of the casing, and at the same time, the upper rubber cylinder expands in the radial direction and presses against the inner wall of the casing under the action of the upper protective cover and the upper thrust ring, and the lower rubber cylinder expands in the radial direction under the extrusion of the lower protective cover and the lower thrust ring, and the upper slip slides under the pressure of the push plate and is squeezed by the outer cone surface of the upper cone to expand in the radial direction and be anchored on the inner wall of the casing, so that the soluble bridge plug with upper and lower sealing structures is switched to the setting state;

[0030] Step C, throwing a plugging body into the casing, using the plugging body to plug the upper port of the central axis, so that the plugging body and the soluble bridge plug with upper and lower sealing structures in a set state are used to separate the lower part of the casing from the upper part, and the soluble bridge plug with upper and lower sealing structures, the casing above the plugging body and the formation are subjected to fracturing operations to extract oil and gas;

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

[0032] Any of the above technical solutions provided by the embodiments of the present invention produces at least the following technical effects:

[0033] The soluble bridge plug with upper and lower sealing structures provided by the present invention, on the one hand, has the lower cava and the lower cone, the upper cava and the upper cone, the upper rubber tube and the lower rubber tube together forming a four-layer sealing structure that can seal the casing (the intermediate cylindrical portion as the intermediate rubber tube in the preferred embodiment can also form a sealing structure that seals the casing). Compared with the sealing structure of the existing soluble bridge plug, the present invention has more sealing levels, and the distribution of the sealing structure is not only more uniform and more symmetrical up and down, but also the contact area between the sealing structure and the casing is larger, so the sealing reliability is higher and the pressure-bearing capacity is also stronger; on the other hand, the anti-slip ratchet teeth that bite each other in the preferred embodiment can prevent the lower cava and the lower cone from disengaging from each other in the axial direction; the anti-retraction ratchet teeth that bite each other can prevent the upper cava and the upper cone from disengaging from each other in the axial direction; the limiting ratchet teeth that bite each other can prevent the lower cone and the central axis from disengaging from each other in the axial direction, thereby ensuring the connection reliability between the lower cava and the lower cone, between the upper cava and the upper cone, and between the lower cone and the central axis, greatly improving the sealing structure with upper and lower sealing structures The overall connection reliability, sealing reliability and pressure-bearing performance of the soluble bridge plug; on the other hand, during the sealing process of the soluble bridge plug with upper and lower sealing structures, the upper cava can slide under the pressure of the push plate and be squeezed by the outer cone surface of the upper cone during the sliding process and expand in the radial direction to be anchored on the casing. At the same time, when the soluble bridge plug with upper and lower sealing structures is in the sealing state, the friction between the upper cava and the casing is less than the friction between the lower cava and the casing. Therefore, even if the upper cava expands to be anchored on the casing, it will slide when it is subjected to a large thrust from above the upper cava. The upper rubber cylinder and the lower rubber cylinder themselves have elasticity and vibration reduction effects, thus playing a role similar to a spring, thereby allowing the upper cava to absorb the large thrust from above the upper cava through short-stroke sliding, reducing the thrust transmitted to the lower cava, thereby achieving stronger sealing stability, higher sealing reliability and stronger pressure-bearing capacity between the lower cava and the casing, thereby solving the technical problems of poor sealing reliability and insufficient pressure-bearing capacity of the existing soluble bridge plug. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Those skilled in the art may better understand the technical effects of the present invention through the following drawings, wherein:

[0035] Figure 1 A schematic plan view of a dissolvable bridge plug with upper and lower sealing structures provided in an embodiment of the present invention.

[0036] Figure 2 for Figure 1 A cross-sectional schematic diagram of a dissolvable bridge plug having upper and lower sealing structures is shown.

[0037] Figure 3 A cross-sectional schematic diagram of a soluble bridge plug with upper and lower sealing structures in a natural state provided by an embodiment of the present invention.

[0038] Figure 4 A cross-sectional schematic diagram of a process in which a soluble bridge plug with upper and lower sealing structures is switched from a natural state to a set sealing state provided in an embodiment of the present invention.

[0039] Figure 5 A cross-sectional schematic diagram of a soluble bridge plug with upper and lower sealing structures provided in an embodiment of the present invention when in a set state.

[0040] Figure 6 for Figure 5 An enlarged schematic diagram of a dissolvable bridge plug having upper and lower sealing structures is shown.

[0041] Figure 7 for Figure 6 Enlarged schematic diagram of part A.

[0042] Figure 8 A schematic plan view of a variable diameter ring in a soluble bridge plug with upper and lower sealing structures provided in an embodiment of the present invention.

[0043] Fig. 9 A schematic plan view of an upper thrust ring in a soluble bridge plug with upper and lower sealing structures provided in an embodiment of the present invention.

[0044] Fig.10 A schematic plan view of another dissolvable bridge plug with upper and lower sealing structures provided in an embodiment of the present invention.

[0045] Fig.11 for Fig.10 A cross-sectional schematic diagram of a dissolvable bridge plug having upper and lower sealing structures is shown.

[0046] Fig.12 for Fig.10 A cross-sectional schematic diagram of the entire process of switching a dissolvable bridge plug having upper and lower sealing structures from a natural state to a set sealing state is shown.

[0047] Markings in the figure: 1. release lever; 2. center axis; 3. release ring; 4. bottom bracket; 5. lower slip; 6. lower cone; 7. lower thrust ring; 8. lower rubber cylinder; 9. lower protective cover; 10. double cone; 11. upper protective cover; 12. upper rubber cylinder; 13. upper thrust ring; 14. upper cone; 15. upper slip; 16. push plate; 17. connecting nut; 18. anti-drop ratchet; 19. anti-retraction ratchet; 2 0. Limit ratchet; 21. Anchor tooth; 22. Variable diameter ring; 220. Connecting hole; 23. Outer thrust ring; 24. Inner thrust ring; 25. Limiting protrusion; 26. Prefabricated 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. Casing. DETAILED DESCRIPTION

[0048] The following is combined with the above Figure 1-Figure 12 The preferred implementation modes and various optional implementation schemes provided by the embodiments of the present invention are described in more detail.

[0049] like Figure 1-Figure 12 As shown, a dissolvable bridge plug with an upper and lower sealing structure provided by an embodiment of the present invention comprises 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 bottom bracket 4, a lower slip 5, and a lower cone 6, a lower thrust ring 7, a lower rubber cylinder 8, a lower protective cover 9, a double cone 10, an upper protective cover 11, an upper rubber cylinder 12, an upper thrust ring 13, an upper cone 14, an upper slip 15 and a push plate 16 stacked from bottom to top and sleeved on the central shaft 2, wherein:

[0050] The release ring 3 is connected to the bottom end of the release lever 1 (the connection between the release ring 3 and the bottom end of the release lever 1 is broken when the soluble bridge plug with upper and lower sealing structures is switched to the setting state, and the release ring 3 falls accordingly);

[0051] The number of the lower rubber cylinder 8 and the upper rubber cylinder 12 is at least one; the number of the lower rubber cylinder 8 and the upper rubber cylinder 12 can also be two or more;

[0052] When the dissolvable bridge plug with upper and lower sealing structures is placed in the casing 32 and the dissolvable bridge plug with upper and lower sealing structures is switched to the setting state, the release lever 1 is pulled and the push plate 16 is pressed. (The release lever 1 pushes the lower slip 5 upward through the bottom bracket 4, and the push plate 16 and the bottom bracket 4 respectively squeeze the upper slip 15 and the lower slip 5 between the push plate 16 and the bottom bracket 4 in the axial direction) The outer cone surface of the lower cone 6 can squeeze the lower slip 5 so that the lower slip 5 expands in the radial direction and is anchored on the inner wall of the casing 32. At the same time, the upper rubber cylinder 12 is on the upper protective cover 11 and the upper thrust ring 13. Under the action of the lower protective cover 9 and the lower thrust ring 7, the lower rubber cylinder 8 can expand in the radial direction and press against the inner wall of the casing 32 (the lower rubber cylinder 8 forms a lower sealing structure after expansion, and the upper rubber cylinder 12 forms an upper sealing structure after expansion), and the upper cava 15 can slide under the pressure of the push plate 16 and be squeezed by the outer cone surface of the upper cone 14 to expand in the radial direction and anchor on the inner wall of the casing 32; when the soluble bridge plug with upper and lower sealing structures is in the setting state, the friction between the upper cava 15 and the casing 32 is less than the friction between the lower cava 5 and the casing 32.

[0053] As an optional implementation mode of the present invention, in this embodiment, the inner conical surface of the lower cava 5 and the outer conical surface of the lower cone 6 are each provided with a plurality of anti-slip ratchet teeth 18, and the respective anti-slip ratchet teeth 18 of the two mesh with each other to prevent the lower cava 5 and the lower cone 6 from disengaging from each other in the axial direction; the inner conical surface of the upper cava 15 and the outer conical surface of the upper cone 14 are each provided with a plurality of anti-retreat ratchet teeth 19, and the respective anti-retreat ratchet teeth 19 of the two mesh with each other to prevent the upper cava 15 and the upper cone 14 from disengaging from each other in the axial direction; the inner circumferential surface of the lower cone 6 and the outer circumferential surface of the center axis 2 are each provided with a plurality of limiting ratchet teeth 20, and the respective limiting ratchet teeth 20 of the two mesh with each other to prevent the lower cone 6 and the center axis 2 from disengaging from each other in the axial direction.

[0054] The dissolvable bridge plug with upper and lower sealing structures provided by the present invention comprises, on the one hand, the lower slip 5 and the lower cone 6, the upper slip 15 and the upper cone 14, the upper rubber tube 12 and the lower rubber tube 8, which together form a four-layer sealing structure that can seal the casing 32 (the middle cylindrical portion 292 of the rubber tube in the middle position in the preferred embodiment can also form a sealing structure that seals the casing). Compared with the sealing structure of the existing dissolvable bridge plug, the present invention has more sealing levels, and the distribution of the sealing structure is not only more uniform and symmetrical, but also more in contact with the casing 32. The area is also larger, so the sealing reliability is higher and the pressure-bearing capacity is also stronger; on the other hand, in the preferred scheme, the anti-slip ratchet teeth 18 that mesh with each other can prevent the lower slip 5 and the lower cone 6 from disengaging from each other in the axial direction; the anti-retraction ratchet teeth 19 that mesh with each other can prevent the upper slip 15 and the upper cone 14 from disengaging from each other in the axial direction; the limiting ratchet teeth 20 that mesh with each other can prevent the lower cone 6 and the central axis 2 from disengaging from each other in the axial direction, thereby ensuring the lower slip 5 and the lower cone 6, the upper slip 15 and the upper cone 14, and the lower cone 6 and the central axis 2. The connection reliability between the upper and lower sealing structures is greatly improved, which greatly improves the connection reliability, setting reliability and pressure bearing performance of the soluble bridge plug with upper and lower sealing structures as a whole; on the other hand, during the setting process of the soluble bridge plug with upper and lower sealing structures, the upper slip 15 can slide under the pressure of the push plate 16 and be squeezed by the outer cone surface of the upper cone 14 during the sliding process and expand in the radial direction to be anchored on the casing 32. At the same time, 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 casing 32 is smaller than that between the lower slip 5 and the casing The friction between the upper cava 15 and the lower cava 32 causes the upper cava 15 to slide even if it expands to be anchored on the casing 32, and the upper rubber cylinder 12 and the lower rubber cylinder 8 themselves have elasticity and vibration reduction effects, thus playing a role similar to a spring, so that the upper cava 15 absorbs the larger thrust from the upper cava 15 through a short-stroke sliding, and reduces the thrust transmitted to the lower cava 5, so that the sealing stability between the lower cava 5 and the casing 32 is stronger, the sealing reliability is higher, and the pressure-bearing capacity is stronger.

[0055] As an optional implementation mode of the present invention, 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 peripheral surface of the slip body. The soluble bridge plug with upper and lower sealing structures is made of soluble or degradable materials except the anchor teeth 21. When the soluble bridge plug with upper and lower sealing structures is in a set state, the lower slip 5 and the upper slip 15 are anchored on the inner wall of the casing 32 by their respective anchor teeth 21.

[0056] The anchor teeth 21 are preferably made of ceramic material. Ceramic material has the advantages of high hardness and strong pressure bearing capacity. The anchor teeth 21 have a small total volume and occupy a small space. Even if they fail to degrade or dissolve, they will not block the liquid channel in the sleeve 32.

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

[0058] The above structure can ensure that when the soluble bridge plug with upper and lower sealing structures is in a setting state, the friction between the upper slip 15 and the casing 32 is less than the friction between the lower slip 5 and the casing 32, thereby forming a setting structure in which the lower slip 5 and the lower cone 6 are stationary, and the upper slip 15 and the upper cone 14 can slide slightly downward to buffer the upper pressure.

[0059] As an optional implementation mode of the present invention, in this embodiment, the number of the anti-slip ratchets 18 is greater than the number of the anti-retraction ratchets 19 , and the number of the anti-retraction ratchets 19 is greater than the number of the limiting ratchets 20 .

[0060] The anti-slip ratchet 18, the stop ratchet 19 and the stop 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 can ensure that when the soluble bridge plug with upper and lower sealing structures is in the setting state, the reliability of the anti-slip ratchet 18 on the lower slip 5 and the lower cone 6, which have the highest stability requirements, is greater than the stop ratchet 19 on the upper slip 15 and the upper cone 14, and is also greater than the limit ratchet 20 on the lower cone 6 and the central shaft 2, thereby ensuring the overall stability.

[0061] As an optional implementation of the present invention, in this embodiment, the taper of the outer cone surface of the lower cone 6 is smaller than the taper of the outer cone surface of the upper cone 14. The lower cone 6 has the highest stability requirement, so its structural design requires that it has a stronger pressure bearing capacity. The smaller the taper, the smaller the radial force component and the larger the axial force component. The axial pressure resistance of the cone structure is stronger than the radial pressure resistance, so the smaller the taper, the stronger the ability of the lower cone 6 to bear axial pressure.

[0062] As an optional embodiment of the present invention, in this embodiment, the inner circumferential surface of the bottom of the central shaft 2 is threadedly connected with a reducing ring 22, which is sleeved on the release lever 1. The reducing ring 22 is provided with a plurality of connecting holes 220, and the plurality of connecting holes 220 are evenly distributed in a radial line shape along the entire circumferential direction of the reducing ring 22; the chamber between the central shaft 2 and the release lever 1 is connected to the chamber between the lower cone 6 and the release lever 1 through the connecting holes 220, and the inner contour line of the cross section of the connecting hole 220 is a major arc.

[0063] The reducing ring 22 can provide radial support and axial guidance for the release lever 1, thereby ensuring the position accuracy of the release lever 1 in the pulling direction. The setting of the connecting hole 220 ensures that the internal pressure of the chamber between the central axis 2 and the release lever 1 and the chamber between the lower cone 6 and the release lever 1 are consistent, thereby ensuring that the release lever 1 can be pulled smoothly.

[0064] As an optional implementation mode of the present invention, in this embodiment, the upper thrust ring 13 and the lower thrust ring 7 each include an outer thrust ring 23 and an inner thrust ring 24 stacked together, and the contact surfaces of the outer thrust ring 23 and the inner thrust ring 24 are both sloped surfaces, and a limiting protrusion 25 is provided at the edge of the contact surface; 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, and the center hole of the outer thrust ring 23 is a peach heart. The inner thrust ring 24 is in the shape of a circle, and the center hole of the inner thrust ring 24 is circular. The thinnest sections of the outer thrust ring 23 and the inner thrust ring 24 are each provided with prefabricated cracks 26. The prefabricated cracks 26 on the outer thrust ring 23 extend along the radial direction of the outer thrust ring 23 to a position close to the limiting protrusion 25 of the inner thrust ring 24; the prefabricated cracks 26 on the inner thrust ring 24 extend along the radial direction of the inner thrust ring 24 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 tube 12, and the inner thrust ring 24 of the lower thrust ring 7 abuts against the lower rubber tube 8; the respective limiting protrusions 25 of the outer thrust ring 23 of the upper thrust ring 13 and the inner thrust ring 24 are embedded in the bottom of the upper cone 14, and the respective limiting protrusions 25 of the outer thrust ring 23 of the lower thrust ring 7 and the inner thrust ring 24 are embedded in the top of the lower cone 6.

[0066] The design of the above structure enables the upper thrust ring 13 and the lower thrust ring 7 to expand smoothly in the radial direction together with the upper rubber cylinder 12 and the lower rubber cylinder 8 when under pressure, thereby providing good support for the upper rubber cylinder 12 and the lower rubber cylinder 8. The design of the prefabricated cracks 26 can not only reduce the resistance that the upper thrust ring 13 and the lower thrust ring 7 need to overcome when expanding in the radial direction, but also make the outer thrust ring 23 and the inner thrust ring 24 of the upper thrust ring 13 and the lower thrust ring 7 both annular before setting, with sufficient strength, and convenient for production and installation.

[0067] As an optional implementation mode of the present invention, in this embodiment, both the lower protective cover 9 and the upper protective cover 11 are annular structures with a guide cone 27 on the inner wall, the edge of the bottom surface of the upper rubber cylinder 12 is provided with a chamfered structure and abuts with the guide cone 27 of the upper protective cover 11 through the chamfered structure, and there is a gap 28 between the bottom surface of the upper rubber cylinder 12 and the edge of the bottom port of the upper protective cover 11; the edge of the top surface of the lower rubber cylinder 8 is provided with a chamfered structure and abuts with the guide cone 27 of the lower protective cover 9 through the chamfered structure, and there is a gap 28 between the top surface of the lower rubber cylinder 8 and the edge of the top port of the lower protective cover 9.

[0068] The existence of the above-mentioned gap 28 reserves a certain space for the axial deformation of the upper rubber cylinder 12 and the lower rubber cylinder 8, thereby ensuring that the lower protective cover 9 and the upper protective cover 11 have sufficient installation space on the one hand, and on the other hand, when the upper rubber cylinder 12 and the lower rubber cylinder 8 are axially deformed, the axial pressure on the lower protective cover 9 and the upper protective cover 11 gradually increases, and they will not be damaged due to the sharp increase in axial pressure when the upper rubber cylinder 12 and the lower rubber cylinder 8 are axially deformed.

[0069] As an optional embodiment of the present invention, the double cone 10 in this embodiment includes an upper cone 291, an intermediate cylindrical portion 292 and a lower cone 293 from top to bottom. The center hole of the double cone 10 is formed by the center holes of the upper cone 291, the intermediate cylindrical portion 292 and the lower cone 293. The upper cone 291 and the lower cone 293 are symmetrical structures. A plurality of sealing grooves 294 are arranged on the inner circumference of the double cone 10. Each sealing groove 294 is embedded with a sealing ring sleeved on the central axis 2. The sealing ring is made of elastic soluble material or degradable material. The cooperation of the sealing ring and the sealing groove 294 improves the reliability of the seal between the double cone 10 and the central axis 2.

[0070] As an optional embodiment of the present invention, the middle cylindrical portion 292 in this embodiment is made of a soluble or degradable elastic material, and the middle cylindrical portion 292, the upper cone portion 291 and the lower cone portion 293 are split structures. When the soluble bridge plug with upper and lower sealing structures is in the setting state, the middle cylindrical portion 292 can expand in the radial direction and abut against the inner wall of the casing 32 after being squeezed by the upper cone portion 291 and the lower cone portion 293 (the middle cylindrical portion 292 is a rubber cylinder set in the middle position, and forms a sealing structure in the middle position after expansion). This structure can make the overall structure form 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 the present invention, the soluble bridge plug with upper and lower sealing structures in this embodiment also includes a connecting nut 17, which is sleeved on the upper section of the release lever 1 and threadedly connected 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 a sealing tool 31 that pulls the release lever 1 through the threads on the top outer circumferential surface of the connecting nut 17; radial connecting screw holes 30 are also provided on the connecting nut 17, and the end of the connecting screw threadedly connected to the radial connecting screw hole 30 can abut and lock the release lever 1 pulling test tool that cooperates with the top inner circumferential surface thread of the connecting nut 17.

[0072] The connecting nut 17 connects the release rod 1 and the center shaft 2 together, and becomes a component that connects the setting tool 31 with the release rod 1 and the center shaft 2. The existence of the connecting nut 17 reduces the difficulty of processing the release rod 1 and the center 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 rod 1 lifting test tool, which facilitates the implementation of the setting operation.

[0073] The application method of the dissolvable bridge plug with upper and lower sealing structures provided by the present invention comprises the following steps: step A, placing the dissolvable bridge plug with upper and lower sealing structures provided by any technical solution of the present invention in the casing 32;

[0074] 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 bottom bracket 4, and the push plate 16 and the bottom bracket 4 respectively squeeze the upper slip 15 and the lower slip 5 between the push plate 16 and the bottom bracket 4 in the axial direction) the outer cone surface of the lower cone 6 squeezes the lower slip 5 so that the lower slip 5 expands in the radial direction and anchors on the inner wall of the casing 32, and at the same time, the upper rubber cylinder 12 expands in the radial direction and presses against the inner wall of the casing 32 under the action of the upper protective cover 11 and the upper thrust ring 13, and the lower rubber cylinder 8 expands in the radial direction under the extrusion of the lower protective cover 9 and the lower thrust ring 7, and 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 in the radial direction and anchor on the inner wall of the casing 32, so that the soluble bridge plug with upper and lower sealing structures is switched to the setting state;

[0075] Step C, throwing a plugging body into the casing 32, using the plugging body to plug the upper port of the central axis 2, so that the plugging body and the soluble bridge plug with upper and lower sealing structures in the set state are used to separate the lower part of the casing 32 from the upper part, and the soluble bridge plug with upper and lower sealing structures, the casing 32 above the plugging body, and the formation are subjected to fracturing operations to extract oil and gas;

[0076] Step D: After the soluble bridge plug with upper and lower sealing structures is in the set state for a predetermined time, the soluble bridge plug with upper and lower sealing structures is dissolved or degraded in the fracturing fluid of the formation in the casing 32, and the part of the soluble bridge plug with upper and lower sealing structures that has not been completely dissolved or degraded falls under its own weight, so that the casing 32 is in a conductive state.

[0077] The present invention solves the technical problems of poor setting reliability and insufficient pressure bearing capacity of existing soluble bridge plugs. Therefore, the present invention is applied to oil and gas production, which is not only more reliable but also applicable to more types and numbers of oil and gas wells.

[0078] The above technical solutions are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A dissolvable bridge plug with upper and lower sealing structures, characterized in that: The invention comprises a release lever, a central shaft sleeved on the upper section of the release lever and having a central hole, a release ring, a bottom bracket, a lower slip stacked in sequence from bottom to top and sleeved on the lower section of the release lever, and a lower cone, a lower thrust ring, a lower rubber cylinder, a lower protective cover, a double cone, an upper protective cover, an upper rubber cylinder, an upper thrust ring, an upper cone, an upper slip and a push plate stacked in sequence from bottom to top and sleeved on the central shaft, wherein: The release ring is connected to the bottom end of the release lever; The number of the lower rubber cylinder and the number of the upper rubber cylinder are at least one; When the soluble bridge plug with upper and lower sealing structures is placed in the casing and the soluble bridge plug with upper and lower sealing structures is switched to the setting state, the release lever is pulled and the push plate is pressed, and the outer cone surface of the lower cone can squeeze the lower slip so that the lower slip expands in the radial direction and anchors to the inner wall of the casing. At the same time, the upper rubber cylinder can expand in the radial direction and press against the inner wall of the casing under the action of the upper protective cover and the upper thrust ring, and the lower rubber cylinder can expand in the radial direction under the extrusion of the lower protective cover and the lower thrust ring, and the upper slip can slide under the pressure of the push plate and be squeezed by the outer cone surface of the upper cone to expand in the radial direction and anchor to the inner wall of the casing; When the soluble bridge plug with upper and lower sealing structures is in a set state, the friction force between the upper slip and the casing is smaller than the friction force between the lower slip and the casing.

2. The dissolvable 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 both provided with a plurality of anti-slip ratchets, and the anti-slip ratchets of the two mesh with each other to prevent the lower slip and the lower cone from being detached 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 both provided with a plurality of stop ratchet teeth, and the stop ratchet teeth of the two mesh with each other to prevent the upper slip and the upper cone from being disengaged from each other in the axial direction; The inner circumference of the lower cone and the outer circumference of the central shaft are both provided with a plurality of position-limiting ratchets, and the position-limiting ratchets of the two respective ones are engaged with each other to prevent the lower cone and the central shaft from being disengaged 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 peripheral surface of the slip body. The soluble bridge plug with upper and lower sealing structures is made of soluble or degradable materials except the anchor teeth. When the soluble bridge plug with upper and lower sealing structures is in a setting state, the lower slip and the upper slip are respectively anchored to the inner wall of the casing through their respective anchor teeth.

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

4. The dissolvable bridge plug with upper and lower sealing structures according to claim 2, characterized in that: The number of the anti-slip ratchets is greater than the number of the stop-retreat ratchets, and the number of the stop-retreat ratchets is greater than the number of the limit ratchets.

5. The dissolvable bridge plug with upper and lower sealing structures according to claim 1, characterized in that: 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.

6. The dissolvable bridge plug with upper and lower sealing structures according to claim 1, characterized in that: A reducing ring is threadedly connected to the inner circumferential surface of the bottom of the central shaft, and the reducing ring is sleeved on the release lever. The reducing ring is provided with a plurality of communicating holes, and the plurality of communicating holes are evenly distributed in a radial line shape along the entire circumferential direction of the reducing ring; the chamber between the central shaft and the release lever is connected with the chamber between the lower cone and the release lever through the communicating holes, and the inner contour line of the cross section of the communicating hole is a major arc line.

7. The dissolvable bridge plug with upper and lower sealing structures according to claim 1, characterized in that: The upper thrust ring and the lower thrust ring each include an outer thrust ring and an inner thrust ring stacked together, the contact surfaces of the outer thrust ring and the inner thrust ring are sloped surfaces, and limiting protrusions are arranged at the edges of the contact surfaces; the limiting protrusion of the outer thrust ring is at the same height as the limiting protrusion of the inner thrust ring, the center hole of the outer thrust ring is heart-shaped, and the center hole of the inner thrust ring is circular, and the thinnest sections of the outer thrust ring and the inner thrust ring are each provided with prefabricated cracks, and the prefabricated cracks on the outer thrust ring extend along the radial direction of the outer thrust ring to a position close to the limiting protrusion of the inner thrust ring; the prefabricated cracks on the inner thrust ring extend along the radial direction of 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, and the outer thrust ring of the lower thrust ring abuts against the The lower cone is abutted against each other, the inner thrust ring of the upper thrust ring is abutted against the upper rubber cylinder, and the inner thrust ring of the lower thrust ring is abutted against the lower rubber cylinder; the respective limiting protrusions of the outer thrust ring of the upper thrust ring and the inner thrust ring are embedded in the bottom of the upper cone, and the respective limiting protrusions of the outer thrust ring and the inner thrust ring of the lower thrust ring are embedded in the top of the lower cone; both the lower protective cover and the upper protective cover are annular structures with guide cone surfaces on the inner walls, the edge of the bottom surface of the upper rubber cylinder is provided with a chamfered structure and abuts against the guide cone surface of the upper protective cover through the chamfered structure, and there is a gap between the bottom surface of the upper rubber cylinder and the edge of the bottom port of the upper protective cover; the edge of the top surface of the lower rubber cylinder is provided with a chamfered structure and abuts against the guide cone surface of the lower protective cover through the chamfered structure, and there is a gap between the top surface of the lower rubber cylinder and the edge of the top port of the lower protective cover.

8. The dissolvable bridge plug with upper and lower sealing structures according to claim 1, characterized in that: The double cone includes an upper cone portion, an intermediate cylindrical portion and a lower cone portion from top to bottom, the central hole of the double cone is formed by the central holes of the upper cone portion, the intermediate cylindrical portion and the lower cone portion, the upper cone portion and the lower cone portion are symmetrical structures, a plurality of sealing grooves are arranged on the inner circumference of the double cone, each of the sealing grooves is embedded with a sealing ring sleeved on the central axis, and the sealing ring is made of elastic soluble material or degradable material; The middle cylindrical portion is made of a soluble or degradable elastic material. The middle cylindrical portion, the upper cone portion and the lower cone portion are split structures. When the soluble bridge plug with upper and lower sealing structures is in a set state, the middle cylindrical portion is squeezed by the upper cone portion and the lower cone portion and can expand in the radial direction and press against the inner wall of the casing.

9. The dissolvable 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, which is sleeved on the upper section of the release rod and threadedly connected between the release rod and the inner wall of the central shaft. The top outer circumference and the top inner circumference of the connecting nut are both provided with threads, and the connecting nut can form a threaded connection with a sealing tool that pulls the release rod through the threads on the top outer circumference of the connecting nut; radial connecting screw holes are also provided on the connecting nut, and the end of the connecting screw threadedly connected to the radial connecting screw hole can abut and lock the release rod lifting test tool that is threadedly matched with the top inner circumference of the connecting nut.

10. A method for using the soluble bridge plug with upper and lower sealing structures according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step A, placing the dissolvable bridge plug with upper and lower sealing structures as described in any one of claims 1 to 9 in the casing; Step B, pulling the release lever and pressing the push plate, the outer cone surface of the lower cone squeezes the lower slip so that the lower slip expands in the radial direction and is anchored on the inner wall of the casing, and at the same time, the upper rubber cylinder expands in the radial direction and presses against the inner wall of the casing under the action of the upper protective cover and the upper thrust ring, and the lower rubber cylinder expands in the radial direction under the extrusion of the lower protective cover and the lower thrust ring, and the upper slip slides under the pressure of the push plate and is squeezed by the outer cone surface of the upper cone to expand in the radial direction and be anchored on the inner wall of the casing, so that the soluble bridge plug with upper and lower sealing structures is switched to the setting state; Step C, throwing a plugging body into the casing, using the plugging body to plug the upper port of the central axis, so that the plugging body and the soluble bridge plug with upper and lower sealing structures in a set state are used to separate the lower part of the casing from the upper part, and the soluble bridge plug with upper and lower sealing structures, the casing above the plugging body and the formation are subjected to fracturing operations to extract oil and gas; Step D: After the soluble bridge plug with upper and lower sealing structures is in the sealing state for a predetermined time, the soluble bridge plug with upper and lower sealing structures is dissolved or degraded in the fracturing fluid of the formation in the casing, and the part of the soluble bridge plug with upper and lower sealing structures that is not completely dissolved or degraded falls under its own weight, so that the casing is in a conductive state.

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