A rapidly degradable sealing structure and its application method

Abstract

The present invention protects a rapidly degradable sealing structure and its application method, including a hollow truncated cone-shaped degradable metal cone, the outer wall sliding sleeve of the degradable metal cone is provided with a degradable metal sealing ring and a degradable metal pressure ring that are closely attached to each other, the degradable metal sealing ring is close to the large-diameter end of the degradable metal cone, and the outer wall of the degradable metal sealing ring is provided with an annular groove, a degradable rubber sealing ring is sleeved in the annular groove, and when the inner wall size deviation of the casing is large, the star-shaped degradable rubber sealing ring in the sealing ring groove is used to ensure that the irregular gap between the casing and the sealing ring is filled. The rapidly degradable sealing structure is used as a sealing mechanism of an oil and gas well fracturing isolation tool, the main purpose of which is to achieve inter-stage isolation during the fracturing process, and has the advantages of simple structure, reliable sealing, and rapid degradation after the fracturing is completed, which solves the problem of difficulty in wellbore handling after fracturing of fracturing tools using traditional rubber seals.

Description

Technical Field

[0001] The invention belongs to the field of downhole operation tools, and in particular relates to a rapidly degradable sealing structure and an application method thereof. Background Art

[0002] During the fracturing process of oil and gas wells, the isolation between sections mainly relies on tools such as bridge plugs, packers, and soluble ball seats. The core of such tools is the sealing mechanism, which is used to block the flow of fluid between sections. Currently, the sealing mechanism mainly uses rubber seals. After fracturing, in order to restore the full bore of the wellbore, it is necessary to remove the packer or drill the bridge plug, which is difficult and risky to construct.

[0003] In recent years, soluble rubber seals and soluble metal seals have emerged. However, soluble rubber seals dissolve slowly and require a long time to degrade after fracturing, which affects the subsequent drainage. Soluble metal seals require that the soluble metal has both high plasticity and high strength, and there is a contradiction between the two. High elongation means poor pressure bearing capacity, and poor pressure bearing capacity means it is easy to break when deformed. The mechanical properties of current soluble metal materials cannot meet the requirements.

[0004] In addition, due to the limitations of the casing molding process, the inner wall of some casings is an irregular cylindrical surface. According to statistical data, the maximum inner diameter deviation can reach 1mm. Therefore, a single soluble metal seal is difficult to effectively seal the pressure difference between sections. Summary of the invention

[0005] The embodiments of the present invention provide a rapidly degradable sealing structure and an application method thereof, the first purpose of which is to solve the problem that the metal of a single soluble metal seal cannot simultaneously achieve high plasticity and high strength; the second purpose is to solve the problem that the soluble rubber seal has a long degradation time, which affects the subsequent drainage; the third purpose is that the existing sealing structure can only be applied to cylindrical sleeves and cannot meet the problem of use on irregular sleeve surfaces.

[0006] In order to solve the above technical problems, the present invention provides a rapidly degradable sealing structure, which at least comprises a hollow truncated cone-shaped degradable metal cone, wherein the outer wall sliding sleeve of the degradable metal cone is provided with a degradable metal sealing ring and a degradable metal pressure-bearing ring which are closely attached to each other, the degradable metal sealing ring is close to the large-diameter end of the degradable metal cone and can be tightened on the large-diameter end, and the outer wall of the degradable metal sealing ring is provided with an annular groove, and a degradable rubber sealing ring is sleeved in the annular groove;

[0007] The cavity wall of the hollow cavity of the degradable metal cone extends toward the axial center line to form a receiving cavity for receiving the soluble ball.

[0008] Furthermore, a plurality of through holes communicating with the hollow cavity are formed on the surface of the degradable metal cone, and all the through holes are distributed in a spiral shape along the surface of the degradable metal cone.

[0009] Preferably, the inner ring surface of the degradable metal sealing ring is a conical surface, which fits the outer wall of the degradable metal cone. The outer ring surface of the degradable metal sealing ring is a cylindrical surface, and an annular groove is opened on the cylindrical surface, and the depth of the annular groove is less than the thickness of the degradable rubber sealing ring.

[0010] Furthermore, the degradable rubber sealing ring adopts a star-shaped sealing ring with a star-shaped cross-section, and the width of the star-shaped sealing ring is less than 5 mm.

[0011] Preferably, the inner ring surface of the degradable metal pressure ring is a conical surface, the conical surface fits with the outer wall of the degradable metal cone, and the outer ring surface of the degradable metal pressure ring is a cylindrical surface.

[0012] Furthermore, a gap is reserved between the outer surface of the degradable metal cone and the inner ring of the degradable metal pressure ring, and the outer diameter of the degradable metal pressure ring is smaller than the outer diameter of the degradable metal sealing ring.

[0013] Preferably, the degradable metal cone and the degradable metal pressure ring are made of degradable metal materials with different hardnesses, wherein the hardness value of the degradable metal pressure ring is greater than the hardness value of the degradable metal cone.

[0014] Furthermore, the degradable metal cone has a large-diameter end and a small-diameter end, the large-diameter end is provided with a shoulder for connecting an adapter of a sealing tool, and the outer wall of the small-diameter end is provided with a thread for connecting a push cylinder of a sealing tool.

[0015] The present invention also protects an application method of a rapidly degradable sealing structure: the rapidly degradable sealing structure is placed between an adapter of a sealing tool and a push tube of the sealing tool and lowered into a casing along with the sealing tool, wherein the large-diameter end of the degradable metal cone is connected to the adapter, and the small-diameter end of the degradable metal cone is connected to the push tube;

[0016] The push cylinder pushes the degradable metal pressure ring and the degradable metal sealing ring to slide along the outer wall of the degradable metal cone from the small-diameter end to the large-diameter end, and the degradable metal sealing ring and the degradable metal pressure ring expand at the same time until the degradable metal sealing ring and the degradable metal pressure ring are close to the shoulder and do not block any through hole. At this time, the outer surface of the degradable metal sealing ring, the outer surface of the degradable rubber sealing ring and the outer surface of the degradable metal pressure ring are all close to the inner wall of the casing to complete the sealing and isolation.

[0017] The beneficial effects of the present invention are as follows:

[0018] (1) The degradable metal sealing ring realizes the sealing of the mechanism, and the degradable metal pressure-bearing ring supports the pressure difference between the segments borne by the sealing ring. That is, the present invention separates the sealing function from the pressure-bearing function, reduces the requirements for the mechanical properties of the degradable metal, and improves the reliability of the sealing mechanism. It can ensure both sealing and pressure-bearing at the same time, and reduce the difficulty of research and development of degradable materials.

[0019] (2) When the inner wall size deviation of the casing is large, the star-shaped biodegradable rubber sealing ring can seal the tiny gap between the casing and the sealing ring due to its large deformation, making the sealing mechanism suitable for casings with irregular inner diameters.

[0020] (3) The sealing mechanism is made of degradable metal and degradable rubber materials. The degradable rubber is extremely small. At the same time, spiral holes are arranged on the degradable cone to increase the contact area with the dissolving liquid and reduce the volume of soluble metal. The sealing mechanism can dissolve quickly after fracturing is completed and can maintain the full diameter of the wellbore after fracturing.

[0021] In order to make the above contents of the present invention more clearly understood, preferred embodiments are given below and described in detail in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of a rapidly degradable sealing structure.

[0023] Figure 2 It is a schematic diagram of the structure of a degradable metal sealing ring.

[0024] Figure 3 It is a schematic diagram of the structure of a degradable metal pressure ring.

[0025] Figure 4 It is a schematic diagram of the structure of a degradable rubber sealing ring.

[0026] Figure 5 Application of rapidly degradable sealing structures Figure 1 .

[0027] Figure 6 Application of rapidly degradable sealing structures Figure 2 .

[0028] Figure 7 It is a stress analysis diagram of a rapidly degradable sealing structure.

[0029] Figure 8 It is a plan view of the spiral hole arrangement of the degradable metal cone.

[0030] Description of reference numerals:

[0031] 1. Degradable metal cone; 2. Degradable metal sealing ring; 3. Degradable rubber sealing ring; 4. Degradable metal pressure ring; 5. Thread; 6. Through hole; 7. Receiving cavity; 8. Shoulder; 9. Conical surface; 10. Annular groove; 11. Sleeve; 12. Star-shaped section; 13. Adapter; 14. Push cylinder. DETAILED DESCRIPTION

[0032] The following describes the implementation of the present invention through specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0033] It should be noted that, in the present invention, the top, bottom, left and right in the figure are deemed to be the top, bottom, left and right of the rapidly degradable sealing structure described in this specification.

[0034] The exemplary embodiments of the present invention are now described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0035] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0036] First embodiment:

[0037] The first embodiment of the present invention relates to a rapidly degradable sealing structure, referring to Figure 1 , at least includes a hollow truncated cone-shaped degradable metal cone 1, the outer wall sliding sleeve of the degradable metal cone 1 is provided with a degradable metal sealing ring 2 and a degradable metal pressure ring 4 which are tightly attached to each other, the degradable metal sealing ring 2 is close to the large-diameter end of the degradable metal cone 1 and can be tightened on the large-diameter end, and the outer wall of the degradable metal sealing ring 2 is provided with an annular groove 10, and a degradable rubber sealing ring 3 is sleeved in the annular groove 10; the cavity wall of the hollow cavity of the degradable metal cone 1 extends toward the axial center line to form a receiving cavity 7 for receiving the soluble ball.

[0038] The working principle of the rapidly degradable seal structure is as follows:

[0039] The rapidly degradable sealing structure is placed between the adapter 13 of the setting tool and the push tube 14 of the setting tool and lowered into the casing 11 along with the setting tool, wherein the large-diameter end of the degradable metal cone 1 is connected to the adapter 13 to ensure that the degradable metal cone 1 and the adapter 13 are coaxial, and the small-diameter end of the degradable metal cone 1 is connected to the push tube 14;

[0040] Figure 1 The figure shows the initial state of the sealing mechanism. A ball is thrown into the well, and the soluble ball enters the receiving cavity 7 to block the internal fluid channel to achieve internal sealing. The push tube 14 pushes the degradable metal pressure ring 4 and the degradable metal sealing ring 2 to slide along the outer wall of the degradable metal cone 1 from the small-diameter end to the large-diameter end. The degradable metal sealing ring 2 and the degradable metal pressure ring 4 expand at the same time until the degradable metal sealing ring 2 and the degradable metal pressure ring 4 are close to the shoulder 8 and do not block any through hole 6. At this time, the outer surface of the degradable metal sealing ring 2, the outer surface of the degradable rubber sealing ring 3 and the outer surface of the degradable metal pressure ring 4 are all in close contact with the inner wall of the casing 11, as shown in FIG. Figure 6 As shown, the sealing is completed.

[0041] The adapter 13 and push tube 14 may be a bridge plug adapter or a bridge plug push tube, or a ball seat adapter or a ball seat push tube, that is, they may be adapters or push tubes of any setting tool without limitation.

[0042] It can be seen that the sealing mechanism is mainly made of two materials, namely, degradable metal and degradable rubber, among which the sealing ring and the pressure ring are both made of degradable metal, the difference is that the sealing ring is made of high-elongation degradable metal, and the pressure ring is made of high-strength degradable metal, that is, the metal properties of the two are different. This is because the function of the degradable metal sealing ring 2 is sealing, and a large deformation amount is required when the diameter is expanded; and the degradable metal pressure ring 4 is used to support the pressure difference between the segments of the degradable metal sealing ring 2 to prevent the degradable metal sealing ring 2 from being crushed. In view of the above reasons, different metal materials are selected for the degradable metal sealing ring 2 and the degradable metal pressure ring 4.

[0043] Considering that the soluble rubber seal has a slow dissolution rate and requires a long degradation time after fracturing, in the present invention, only the degradable rubber seal ring 3 is made of soluble rubber material, which can ensure sealing and minimize the volume of rubber material with a slow degradation rate.

[0044] Stress analysis of sealing mechanism Figure 7As shown, when the degradable metal sealing ring 2 and the degradable metal pressure ring 4 are close to the casing wall, the sealing mechanism completes the mechanism movement. At this time, the degradable metal sealing ring 2 and the degradable metal pressure ring 4 generate an outward thrust and a reverse friction force on the degradable metal cone 1. In order to prevent the degradable metal cone 1 from being squeezed out and causing the mechanism to fail, the horizontal component of the friction force should be greater than the horizontal component of the positive pressure F to achieve self-locking of the mechanism, that is, Fηcosθ>Fsinθ (where F is the positive pressure of the degradable metal cone 1, η is the friction coefficient, and θ is the cone angle of the degradable metal cone 1). Therefore, the sealing mechanism adjusts the friction coefficient η and the cone angle θ at the same time to achieve self-locking, as follows:

[0045] (1) When the cone angle θ is too small, the mechanism can easily achieve self-locking, but the tool length will be too long. When the cone angle θ is too large, the thrust required for the expansion of the biodegradable metal sealing ring 2 and the biodegradable metal pressure ring 4 will increase. According to experimental tests, the mechanism can achieve safe self-locking when the cone angle of the biodegradable metal cone 1 is between 12° and 13°, and the mechanism length can be minimized, and the setting force can be adjusted to a reasonable range.

[0046] (2) Adjusting the material hardness: When the Brinell hardness of the degradable metal pressure ring 4 is HB10-20 greater than the Brinell hardness of the degradable metal cone 1, micro-plastic deformation occurs between the two during the extrusion and diameter expansion process, and the microstructures are embedded in each other. Therefore, increasing the friction coefficient η can achieve self-locking.

[0047] Second implementation method:

[0048] This embodiment relates to a rapidly degradable sealing structure. Figure 1 , at least includes a hollow truncated cone-shaped degradable metal cone 1, the outer wall sliding sleeve of the degradable metal cone 1 is provided with a degradable metal sealing ring 2 and a degradable metal pressure ring 4 which are tightly attached to each other, the degradable metal sealing ring 2 is close to the large-diameter end of the degradable metal cone 1 and can be tightened on the large-diameter end, and the outer wall of the degradable metal sealing ring 2 is provided with an annular groove 10, and a degradable rubber sealing ring 3 is sleeved in the annular groove 10; the cavity wall of the hollow cavity of the degradable metal cone 1 extends toward the axial center line to form a receiving cavity 7 for receiving the soluble ball.

[0049] Reference Figure 1 and Figure 8 The surface of the degradable metal cone 1 is provided with a plurality of through holes 6 connected to the hollow cavity, and all the through holes 6 are distributed in a spiral shape along the surface of the degradable metal cone 1. The spiral holes on the degradable metal cone 1 can increase the contact area with the dissolving liquid and reduce the volume of the soluble metal. The sealing mechanism can be quickly dissolved after the fracturing is completed, and the full diameter of the wellbore after fracturing can be maintained; in addition, the spiral holes can prevent the degradable metal cone 1 from being subjected to excessive force on the same cross section, and maximize the tensile strength of the degradable metal cone 1.

[0050] Third embodiment:

[0051] Based on the first implementation, Figure 2 As shown, the inner ring surface of the degradable metal sealing ring 2 is a conical surface 9, which has the same cone angle as the degradable metal cone 1. After expansion, the conical surface 9 fits with the outer wall of the degradable metal cone 1. The outer ring surface of the degradable metal sealing ring 2 is a cylindrical surface, and the annular groove 10 is opened on the cylindrical surface, and the depth of the annular groove 10 is less than the thickness of the degradable rubber sealing ring 3.

[0052] As a preference, Figure 4 As shown, the degradable rubber sealing ring 3 adopts a star-shaped sealing ring with a star-shaped cross section 12, and the width of the star-shaped sealing ring is less than 5 mm, which can not only ensure sealing but also minimize the volume of the rubber material with a slower degradation rate.

[0053] The star-shaped sealing ring has a large deformation amount. When encountering the situation of poor cylindricity of the inner wall of the casing (irregular shape), the degradable rubber sealing ring 3 has a large deformation amount and can fill the remaining gap; that is, when the size deviation of the inner wall of the casing is large, the star-shaped degradable rubber sealing ring in the sealing ring groove is used to ensure that the irregular gap between the casing and the sealing ring is filled, and the tiny gap between the casing and the sealing ring is effectively sealed.

[0054] Reference Figure 3 The inner ring surface of the degradable metal pressure ring 4 is a conical surface 9, which has the same cone angle as the degradable metal cone 1. The conical surface 9 fits the outer wall of the degradable metal cone 1, and the outer ring surface of the degradable metal pressure ring 4 is a cylindrical surface.

[0055] In the initial state of the sealing mechanism, a gap (e.g., 1 mm) is reserved between the outer surface of the degradable metal cone 1 and the inner ring of the degradable metal pressure ring 4, and the outer diameter of the degradable metal pressure ring 4 is smaller than the outer diameter of the degradable metal sealing ring 2, e.g., the outer diameter of the degradable metal pressure ring 4 is 1 mm smaller than the outer diameter of the degradable metal sealing ring 2. In this way, the deformation of the degradable metal pressure ring 4 is relatively small when the diameter is expanded, ensuring that the degradable metal pressure ring 4 will not break when the diameter is expanded.

[0056] In order to achieve the self-locking of the sealing mechanism, the degradable metal cone 1 and the degradable metal pressure ring 4 in this embodiment are made of degradable metal materials with different hardness, wherein the hardness value of the degradable metal pressure ring 4 is greater than the hardness value of the degradable metal cone 1. For example, the hardness value of the degradable metal pressure ring 4 is HB10-20 greater than the hardness value of the degradable metal cone 1. During the extrusion and diameter expansion process, the two undergo micro-plastic deformation, and the microstructures are embedded in each other, increasing the friction coefficient, thereby achieving the self-locking of the mechanism and preventing it from moving.

[0057] like Figure 1As shown, in order to facilitate the interconnection or installation with other components during application, the degradable metal cone 1 has a large-diameter end and a small-diameter end, the end of its large-diameter end is provided with a shoulder 8 for connecting an adapter 13 of a sealing tool, and the end outer wall of its small-diameter end is provided with a thread 5 for connecting a push cylinder 14 of a sealing tool.

[0058] Fourth embodiment:

[0059] This embodiment protects an application method of a rapidly degradable sealing structure, referring to Figure 5 and Figure 6 , placing the rapidly degradable sealing structure between the adapter 13 of the setting tool and the push tube 14 of the setting tool and lowering it into the casing 11 along with the setting tool, wherein the large-diameter end of the degradable metal cone 1 is connected to the adapter 13, and the small-diameter end of the degradable metal cone 1 is connected to the push tube 14;

[0060] The push cylinder 14 pushes the degradable metal pressure ring 4 and the degradable metal sealing ring 2 to slide along the outer wall of the degradable metal cone 1 from the small-diameter end to the large-diameter end, and the degradable metal sealing ring 2 and the degradable metal pressure ring 4 expand at the same time until the degradable metal sealing ring 2 and the degradable metal pressure ring 4 are close to the shoulder 8 and do not block any through hole 6. At this time, the outer surface of the degradable metal sealing ring 2, the outer surface of the degradable rubber sealing ring 3 and the outer surface of the degradable metal pressure ring 4 are all close to the inner wall of the casing 11 to complete the sealing and isolation.

[0061] Regarding the self-locking of the sealing mechanism during use, this embodiment adopts two means of self-locking, so that the sealed mechanism will not move, thereby ensuring the reliability of the sealing mechanism: the first means is to adjust the cone angle of the cone to achieve self-locking of the friction angle between the pressure ring and the sealing ring and the cone; the second means is to adjust the material hardness so that the Brinell hardness of the pressure ring material is HB10-20 greater than the Brinell hardness of the cone material. During the extrusion and expansion process, micro-plastic deformation occurs in the two, and the microstructures are embedded in each other, increasing the friction coefficient.

[0062] Specifically, the rapidly degradable sealing structure comprises at least a hollow truncated cone-shaped degradable metal cone 1, the outer wall sliding sleeve of the degradable metal cone 1 is provided with a degradable metal sealing ring 2 and a degradable metal pressure-bearing ring 4 which are tightly attached to each other, the degradable metal sealing ring 2 is close to the large-diameter end of the degradable metal cone 1 and can be tightened on the large-diameter end, and the outer wall of the degradable metal sealing ring 2 is provided with an annular groove 10, and a degradable rubber sealing ring 3 is sleeved in the annular groove 10; the cavity wall of the hollow cavity of the degradable metal cone 1 extends toward the axial center line to form a receiving cavity 7 for receiving the soluble ball.

[0063] A plurality of through holes 6 communicating with the hollow cavity are formed on the surface of the degradable metal cone 1 , and all the through holes 6 are distributed in a spiral shape along the surface of the degradable metal cone 1 .

[0064] The inner ring surface of the degradable metal sealing ring 2 is a conical surface 9, which fits the outer wall of the degradable metal cone 1. The outer ring surface of the degradable metal sealing ring 2 is a cylindrical surface, and the annular groove 10 is opened on the cylindrical surface, and the depth of the annular groove 10 is less than the thickness of the degradable rubber sealing ring 3.

[0065] The degradable rubber sealing ring 3 is a star-shaped sealing ring with a star-shaped cross section 12, and the width of the star-shaped sealing ring is less than 5 mm.

[0066] The inner ring surface of the degradable metal pressure ring 4 is a conical surface 9, which fits the outer wall of the degradable metal cone 1, and the outer ring surface of the degradable metal pressure ring 4 is a cylindrical surface.

[0067] A gap is reserved between the outer surface of the degradable metal cone 1 and the inner ring of the degradable metal pressure ring 4 , and the outer diameter of the degradable metal pressure ring 4 is smaller than the outer diameter of the degradable metal sealing ring 2 .

[0068] The degradable metal cone 1 and the degradable metal pressure ring 4 are made of degradable metal materials with different hardnesses, wherein the hardness value of the degradable metal pressure ring 4 is greater than the hardness value of the degradable metal cone 1 .

[0069] The degradable metal cone 1 has a large-diameter end and a small-diameter end. The end of the large-diameter end is provided with a shoulder 8 for connecting an adapter 13 of a sealing tool, and the outer wall of the end of the small-diameter end is provided with a thread 5 for connecting a push tube 14 of a sealing tool.

[0070] In summary, the rapidly degradable sealing structure and its application method protected by the present invention use a combination of a highly ductile degradable metal sealing ring, a degradable star-shaped rubber sealing ring, and a high-strength degradable metal pressure ring to seal the annulus between the degradable metal cone and the casing. It has the advantages of simple structure, reliable sealing, and rapid degradation after fracturing, solving the problem of difficulty in handling the wellbore after fracturing for fracturing tools using traditional rubber seals.

[0071] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present invention, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present invention.

Claims

1. A rapidly degradable sealing structure, characterized in that: The invention comprises at least a hollow truncated cone-shaped degradable metal cone (1), wherein the outer wall of the degradable metal cone (1) is provided with a sliding sleeve of a degradable metal sealing ring (2) and a degradable metal pressure-bearing ring (4) which are closely attached to each other, the degradable metal sealing ring (2) is close to the large-diameter end of the degradable metal cone (1) and can be tightened on the large-diameter end, the outer wall of the degradable metal sealing ring (2) is provided with an annular groove (10), and a degradable rubber sealing ring (3) is sleeved in the annular groove (10); The cavity wall of the hollow cavity of the degradable metal cone (1) extends toward the axial centerline to form a receiving cavity (7) for receiving the soluble ball; When the degradable metal sealing ring (2) and the degradable metal pressure ring (4) are in close contact with the casing wall, the degradable metal sealing ring (2) and the degradable metal pressure ring (4) generate an outward thrust and a reverse friction force on the degradable metal cone (1). To prevent the degradable metal cone (1) from being squeezed out and causing the sealing mechanism to fail, the horizontal component of the friction force should be greater than the horizontal component of the positive pressure F to achieve self-locking of the mechanism, that is, Fηcosθ>Fsinθ, wherein F is the positive pressure of the degradable metal cone (1), η is the friction coefficient, and θ is the cone angle of the degradable metal cone (1). Therefore, the sealing mechanism can achieve self-locking by adjusting the friction coefficient η and the cone angle θ at the same time, as follows: (i) When the cone angle θ is too small, the mechanism can easily achieve self-locking, but the tool length will be too long. When the cone angle θ is too large, the thrust required for the degradable metal sealing ring (2) and the degradable metal pressure ring (4) to expand will increase. According to tests, when the cone angle of the degradable metal cone (1) is between 12° and 13°, the mechanism can achieve safe self-locking, and the length of the mechanism can be reduced to the maximum extent, and the sealing force can be adjusted to a reasonable range. (ii) Adjusting the material hardness: When the Brinell hardness of the degradable metal pressure ring (4) is greater than the Brinell hardness of the degradable metal cone (1) by HB10-20, micro-plastic deformation occurs between the two during the extrusion and diameter expansion process, and the microstructures are embedded in each other, thereby increasing the friction coefficient η to achieve self-locking.

2. The rapidly degradable sealing structure according to claim 1, characterized in that: The surface of the degradable metal cone (1) is provided with a plurality of through holes (6) communicating with the hollow cavity, and all the through holes (6) are distributed in a spiral shape along the surface of the degradable metal cone (1).

3. The rapidly degradable sealing structure according to claim 1, characterized in that: The inner ring surface of the degradable metal sealing ring (2) is a conical surface (9), the conical surface (9) is in contact with the outer wall of the degradable metal cone (1), the outer ring surface of the degradable metal sealing ring (2) is a cylindrical surface, the annular groove (10) is formed on the cylindrical surface, and the depth of the annular groove (10) is less than the thickness of the degradable rubber sealing ring (3).

4. The rapidly degradable sealing structure according to claim 1 or 3, characterized in that: The degradable rubber sealing ring (3) is a star-shaped sealing ring with a star-shaped cross section (12), and the width of the star-shaped sealing ring is less than 5 mm.

5. The rapidly degradable sealing structure according to claim 1, characterized in that: The inner ring surface of the degradable metal pressure-bearing ring (4) is a conical surface (9), the conical surface (9) is in contact with the outer wall of the degradable metal cone (1), and the outer ring surface of the degradable metal pressure-bearing ring (4) is a cylindrical surface.

6. The rapidly degradable sealing structure according to claim 1, 3 or 5, characterized in that: A gap is reserved between the outer surface of the degradable metal cone (1) and the inner ring of the degradable metal pressure ring (4), and the outer diameter of the degradable metal pressure ring (4) is smaller than the outer diameter of the degradable metal sealing ring (2).

7. The rapidly degradable sealing structure according to claim 1, characterized in that: The degradable metal cone (1) and the degradable metal pressure ring (4) are made of degradable metal materials with different hardnesses, wherein the hardness value of the degradable metal pressure ring (4) is greater than the hardness value of the degradable metal cone (1).

8. The rapidly degradable sealing structure according to claim 1, characterized in that: The degradable metal cone (1) has a large-diameter end and a small-diameter end, the end of the large-diameter end is provided with a shoulder (8) for connecting to an adapter (13) of a setting tool, and the outer wall of the end of the small-diameter end is provided with a thread (5) for connecting to a push tube (14) of the setting tool.

9. A method for using the rapidly degradable sealing structure according to any one of claims 1 to 8, characterized in that: The rapidly degradable sealing structure is placed between an adapter (13) of a sealing tool and a push tube (14) of the sealing tool and lowered into the casing (11) along with the sealing tool, wherein the large-diameter end of the degradable metal cone (1) is connected to the adapter (13), and the small-diameter end of the degradable metal cone (1) is connected to the push tube (14); The push cylinder (14) pushes the degradable metal pressure ring (4) and the degradable metal sealing ring (2) to slide along the outer wall of the degradable metal cone (1) from the small-diameter end to the large-diameter end, and the degradable metal sealing ring (2) and the degradable metal pressure ring (4) expand in diameter at the same time until the degradable metal sealing ring (2) and the degradable metal pressure ring (4) are close to the shoulder (8) and do not block any through hole (6). At this time, the outer surface of the degradable metal sealing ring (2), the outer surface of the degradable rubber sealing ring (3) and the outer surface of the degradable metal pressure ring (4) are all in close contact with the inner wall of the casing (11), completing the sealing and isolation.

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