Seawater-based high-salinity superhigh-temperature high-pressure differential full-soluble bridge plug

Abstract

The application discloses a seawater-based high-mineralization superhigh-temperature high-pressure differential full-soluble bridge plug, which comprises a tension shaft, the upper part and the lower end of the tension shaft are respectively threadedly connected with a locking sleeve and a shearing seat; an expansion cone, an expansion sealing sleeve, a cone sleeve and a slip assembly are sequentially arranged between the locking sleeve and the shearing seat and are mutually inserted; a central pipe is further arranged in the expansion cone, the expansion sealing sleeve, the cone sleeve, the slip assembly and the shearing seat, the central pipe is used for centralizing, and the locking sleeve, the tension shaft and the shearing seat are threadedly fastened to the middle part to fix the whole product. The application is suitable for various well conditions of the sea and land, and can be used for efficient, safe and reliable operation on a >37500mg / L high-mineralization seawater, 204 DEG C superhigh-temperature, 105MPa superhigh-pressure differential large-inclination, horizontal unconventional oil and gas well of the offshore oil field.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well development operations, and in particular to a seawater-based, high-salinity, ultra-high temperature, high-pressure differential, fully soluble bridge plug. Background Technology

[0002] Shale gas, tight oil, and other unconventional oil and gas reservoirs have low porosity and permeability, making extraction difficult. In unconventional oil and gas extraction, perforation, besides establishing channels for oil and gas flow, primarily serves to create pressurization channels for subsequent fracturing, characterized by multiple perforation layers and short perforation lengths per layer. To reduce operating costs and improve efficiency, multiple perforation and plugging operations need to be completed in a single tubing run. Multi-stage bridge perforation technology is the main approach and important operational method for its safe and efficient development.

[0003] Multi-stage bridge-perforation technology utilizes a cable-driven perforator and bridge plug. First, the bridge plug propellant is ignited by electricity, setting the plug above the first perforation layer to seal between layers. Then, the cable is raised and the depth is adjusted, followed by the detonation of the first cluster of perforators; the cable is raised again and the depth adjusted, then the second cluster of perforators is detonated, and so on, completing the multi-cluster perforation operation. Finally, the cable-driven perforation tool string is retrieved, and a ball is dropped into the wellhead for fracturing operations. The bridge plug is a key product in the entire multi-stage bridge-perforation technology string, used to achieve inter-layer separation and sealing of multiple oil and gas layers.

[0004] Currently, many offshore oil fields both domestically and internationally contain unconventional tight oil and gas reservoirs. These reservoirs are buried at depths exceeding 5000 meters, operate at temperatures as high as 204℃, experience pressure differentials as high as 105 MPa, and suffer from low recovery rates. Conventional extraction methods are costly and inefficient. Multi-stage bridge-jetting technology is proposed for these reservoirs, but the high salinity and temperature of seawater cause corrosion to conventional soluble bridge plugs, making them unsuitable for high pressure differential operations. Therefore, a new seawater-based, high-salinity, ultra-high temperature, high-pressure, fully soluble bridge plug has been developed to meet the requirements of offshore operations.

[0005] For example, Chinese utility model patent CN222991496U discloses a rapid-dissolving bridge plug, including a bridge plug body and a dissolution-promoting component. The bridge plug body is provided with a receiving groove, and the dissolution-promoting component includes a solution bladder and a V-shaped rod. Rotation of the V-shaped rod causes the solution bladder to rupture, allowing corrosive fluid to flow out and dissolving the bridge plug. The V-shaped rod has a uniform opening size, allowing the use of only one size fracturing ball during operation, reducing the variety of fracturing ball specifications. This utility model provides a rapid-dissolving bridge plug that enables interlayer sealing operations in multi-stage bridge-jetting operations in onshore oilfields and reduces the types of fracturing balls. Another example is Chinese utility model patent CN223034965U, which discloses a composite sealing soluble bridge plug structure, including a sealing sleeve, a protective ring, a protective gasket, a variable-diameter sealing ring, a cone, a tailstock, a mounting block, a connecting shaft, and a slip assembly. The sealing sleeve is used to compensate for sealing defects caused by casing deformation or damage to the variable-diameter sealing ring. For example, Chinese invention patent CN120312161A discloses a soluble bridge plug designed to prevent detachment, comprising a central tube, an inner sleeve, a sealing rubber tube, a rubber cylinder, and positioning pins (upper tube, lower tube, spring, limiting plate, positioning pin, push rod, top plate, crushing groove, sealing ring, and waterproof cap). The product's positioning pins increase the fixed distance and sealing distance between the bridge plug and the sleeve, adapting to the non-uniform surface of the sleeve, enhancing sealing stability, preventing bridge plug detachment, and improving fracturing effect. For example, Chinese invention patent CN119710400A discloses a soluble magnesium alloy material and a soluble bridge plug using the soluble magnesium alloy. The soluble magnesium alloy material includes magnesium, zinc, aluminum, nickel, copper, neodymium, and cerium, with the following mass percentages: magnesium >85%, zinc 2-5%, aluminum 2-4%, nickel 1-3%, copper 1-3%, neodymium 1-2%, and cerium 1-2%. The soluble bridge plug made using the material of this invention meets the requirements for well operations in onshore oil fields with a temperature resistance of 200℃ / 24h and a pressure differential resistance of 70MPA.

[0006] For unconventional oil and gas reservoir operations, the main problems with using the above products are: 1) In the utility model patent with publication number CN222991496U, the rapid soluble bridge plug has a complex structure, the V-shaped rod has unreliable rotation and cannot open the solution bladder; the formula of the corrosive liquid inside the solution bladder is fixed and cannot be adjusted in real time at the wellhead according to the needs of the operation, which affects the efficiency and effect of the operation; the outer diameter is large and the throughput is poor, which easily leads to stuck well and pump detachment from the tubing string.

[0007] 2) The soluble bridge plugs in CN222991496U, CN223034965U, and CN120312161A do not have domestically available sealing sleeves with a temperature resistance of 204℃. Their temperature and pressure resistance are low, and they are currently only suitable for shallow well operations with a well temperature of 150℃ and a pressure difference of 70MPA or less. They cannot meet the requirements of offshore oilfield operations with high salinity of 37500mg / L, high temperature of 204℃, and high pressure difference of 105MPA.

[0008] 3) The soluble bridge plug in CN119710400A has a pressure differential resistance of 70MPA and is only suitable for freshwater fracturing operations in onshore oil fields. It cannot simultaneously meet the requirements of offshore oil fields with high salinity seawater of 37500mg / L, high temperature of 204℃, and high pressure differential of 105MPA. Summary of the Invention

[0009] To solve the above-mentioned technical problems, the present invention provides a seawater-based, high-mineralization, ultra-high temperature and high pressure differential fully soluble bridge plug.

[0010] The present invention is achieved by the following technical solution.

[0011] A seawater-based, high-mineralization, ultra-high temperature, high-pressure differential, fully soluble bridge plug includes a tension shaft, the upper and lower ends of which are threadedly connected to a locking sleeve and a shear seat, respectively. Between the locking sleeve and the shear seat, an expansion cone, an expansion sealing sleeve, a cone sleeve, and a slip assembly are sequentially arranged and interlocked. A central tube is also provided inside the expansion cone, expansion sealing sleeve, cone sleeve, slip assembly, and shear seat. The central tube is used to straighten the plug, and the entire product is fixed by being screwed towards the center by the threads of the locking sleeve, tension shaft, and shear seat.

[0012] By adopting the above technical solution, the seawater-based high-mineralization ultra-high temperature and high pressure differential fully soluble bridge plug is transported to the oil and gas layer by cable, and is equipped with bridge plug tools and bridge plug explosives. The bridge plug is moved relative to the casing by the thrust of the bridge plug explosives, and is set in the casing to achieve interlayer separation and sealing of multiple oil and gas layers. After 360 hours, it dissolves into powder to form a smooth passage, which can be directly used for subsequent operations and oil and gas extraction.

[0013] Furthermore, the soluble bridge plug also includes a soluble ball.

[0014] Furthermore, the expansion sealing sleeve is provided with stepped holes and five sealing grooves of different sizes, and two types of O-rings are provided in the sealing grooves.

[0015] Furthermore, an anti-seating sealing ring is fitted onto the conical sleeve.

[0016] Furthermore, the slip assembly includes slips with several cracking grooves; the outer wall of the slips is provided with several teeth, which are evenly distributed downwards along the circumference of the slips.

[0017] Furthermore, the shear seat and the slip assembly are connected by mutually coupled grooves and protrusions.

[0018] Furthermore, the soluble sphere includes a soluble sphere shell, and the soluble sphere shell contains a high concentration of KCl powder.

[0019] Furthermore, the expansion cone, expansion sealing sleeve, cone sleeve, and slip assembly are made of high-strength, slow-soluble magnesium-aluminum alloy, mainly composed of aluminum, magnesium, zinc, copper, nickel, lanthanum, lithium, neodymium, and cerium, wherein aluminum accounts for 40-50%, magnesium and zinc account for 30-40%, and rare metals such as lanthanum, lithium, neodymium, and cerium account for 10-18%, with a tensile strength of 400-500 MPa and a dissolution time of >360h.

[0020] Furthermore, the preparation method of the high-strength slow-soluble magnesium-aluminum alloy is as follows: aluminum, magnesium, and zinc are used as the matrix in a high-temperature melting furnace at 1300-1800℃, rare metals are added in sequence, and then high-density bars are die-cast under 200T pressure and machined into shape.

[0021] Furthermore, the shear seat and soluble ball are made of low-strength, fast-soluble magnesium-aluminum alloy, mainly composed of magnesium, zinc, aluminum, copper, nickel, lanthanum, lithium, neodymium, and cerium, of which magnesium and zinc account for 75-80%, aluminum accounts for 10-15%, and rare metals such as lanthanum, lithium, neodymium, and cerium account for 5-10%, with a tensile strength of 200-300 MPa and a dissolution time of >24 hours.

[0022] Furthermore, the preparation method of the low-strength fast-soluble magnesium-aluminum alloy is as follows: magnesium, zinc, and aluminum are used as the matrix in a high-temperature melting furnace at 1200-1500℃, rare metals are added in sequence, and then the alloy is die-cast into medium-density bars under a pressure of 150T and machined.

[0023] Furthermore, the central tube is made of a high-strength, slow-soluble aluminum alloy, mainly composed of aluminum, zinc, nickel, neodymium, and cerium, with aluminum accounting for 60-70% and rare metals accounting for 10-20%, tensile strength of 400-500 MPa, and dissolution time > 360 h.

[0024] Furthermore, the preparation method of the high-strength slow-soluble aluminum alloy is as follows: using aluminum and zinc as the matrix in a high-temperature melting furnace at 1500-1800℃, rare metals are added sequentially, and then the alloy is die-cast into high-density bars under a pressure of 200T and machined into shape.

[0025] This application has the following beneficial effects: (1) The soluble bridge plug in this invention can reliably complete the interlayer sealing operation of tight oil and gas wells at sea, isolating multiple oil and gas layers. The operation process is simple and easy to operate. When used downhole, it is stable, safe, reliable, fast and efficient, saving the operation time and cost of multi-stage bridge-cutting technology. It is applicable to various well conditions in onshore and offshore oil and gas fields, especially capable of multi-stage bridge-cutting operations in high-angle wells and horizontal wells with ultra-high temperature and high pressure differential.

[0026] (2) The soluble bridge plug in this invention is based on ultra-high temperature and ultra-high pressure special rubber and fully soluble magnesium-aluminum alloys with different strengths and dissolution rates. It features an innovative design of the product's sealing structure, setting structure, support structure, and release structure. This design prevents the bridge plug from rapidly corroding and dissolving in ultra-high temperature, high-mineralization seawater, thus preventing unreliable setting and sealing. It solves the problems of unreliable setting and low temperature and pressure resistance. It remains insoluble for 24 hours in the initial stage of operation and completely dissolves after 360 hours. It is a key product in the multi-stage bridge-jetting technology for unconventional tight oil and gas reservoir development.

[0027] (3) The soluble bridge plug in this invention is delivered by cable. The bridge plug has a small diameter, a large flow hole, is soluble as a whole, is easy to lift and lower, and has a high throughput. It can effectively pass through the deformation of the downhole casing, avoiding the situation where the tubing gets stuck and the pump gets off the tubing, thus solving the problem of horizontal well tubing pumping.

[0028] (4) The soluble bridge plug in this invention is an ultra-high temperature and high pressure differential bridge plug for offshore operations, which can meet the requirements of offshore oilfield operations with high salinity seawater of 37,500 mg / L, ultra-high temperature of 204℃, and high pressure differential of 105 MPa. It has strong environmental adaptability and will not fail due to temperature, pressure, seawater mineral corrosion in the well, resulting in high success rate and reliability of operations. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the seawater-based, high-mineralization, ultra-high temperature, high-pressure differential fully soluble bridge plug of the present invention; Figure 2 This is a schematic diagram of the expansion sealing sleeve structure of the present invention; Figure 3 This is a schematic diagram of the structure of the KOV assembly of the present invention; Figure 4 This is a schematic diagram of the structure of the soluble sphere of the present invention.

[0030] Among them, 1. tension shaft, 2. locking sleeve, 3. expansion cone, 4. O-ring, 5. expansion sealing sleeve, 6. central tube, 7. cone sleeve, 8. anti-seating sealing ring, 9. retaining tooth, 10. retaining slip, 11. shear seat, 12. soluble ball, 13. KCl powder. Detailed Implementation

[0031] This invention relates to a seawater-based, high-salinity, ultra-high temperature, high-pressure differential fully soluble bridge plug. It is delivered to the oil and gas reservoir via cable, and operated with matching bridge plug tools and propellant. The propellant thrust causes the soluble bridge plug to move relative to the casing, setting it in place and achieving interlayer separation and sealing of multiple oil and gas layers. After 360 hours, it dissolves into powder, forming a smooth flow path for direct subsequent operations and oil and gas extraction. It can be applied in offshore oilfields under conditions of >37500 mg / L high-salinity seawater, 204℃ ultra-high temperature, and 105 MPa high-pressure differential. The operation is simple, convenient, fast, efficient, safe, and reliable.

[0032] This invention is based on ultra-high temperature and ultra-high pressure special rubber and fully soluble magnesium-aluminum alloys with different dissolution rates. It innovatively designs the product's sealing structure, setting structure, support structure, and release structure to form a seawater-based, high-salinity, ultra-high temperature and high pressure differential fully soluble bridge plug, which is applied to interlayer separation and plugging in offshore oil and gas wells. It is a key product in multi-stage bridge-jetting technology for unconventional oil and gas reservoir development.

[0033] This invention solves the problems of conventional soluble bridge plugs rapidly corroding and dissolving in ultra-high temperature, high-salinity seawater, making reliable setting and sealing impossible; low temperature and pressure differential resistance; small diameter and low flow rate; no dissolution in the first 24 hours of operation, and complete dissolution in the later 360 hours. It also solves the problems of composite bridge plugs being unable to dissolve downhole, difficulties in handling stuck plugs during pumping, the need for post-operation drilling and refining, long operation time, low efficiency, and high cost. It is suitable for various well conditions both offshore and onshore, especially for high-angle, horizontal, unconventional oil and gas wells in offshore oil fields with high salinity seawater (>37500 mg / L), ultra-high temperature (204℃), and ultra-high pressure differential (105 MPa) for efficient, safe, and reliable operation.

[0034] The present patent application will be further described below with reference to the accompanying drawings and embodiments.

[0035] like Figures 1-4 As shown, a seawater-based, high-mineralization, ultra-high temperature, high-pressure differential fully soluble bridge plug includes components such as a tension shaft 1, a locking sleeve 2, an expansion cone 3, an O-ring 4, an expansion sealing sleeve 5, a central tube 6, a cone sleeve 7, an anti-seating sealing ring 8, a locking tooth 9, a locking slip 10, a shear seat 11, and a soluble ball 12.

[0036] The expansion cone 3, expansion sealing sleeve 5, central tube 6, cone sleeve 7, anti-seating sealing ring 8, slip assembly, shear seat 11, and soluble ball 12 are made of soluble metal and will dissolve into powder after being run into the well. The tension shaft 1 and locking sleeve 2 are made of high-strength alloy structural steel and will not dissolve after being run into the well. They will be recovered together with the working tubing.

[0037] The expansion cone 3, expansion sealing sleeve 5, cone sleeve 7, and slip assembly are made of high-strength, slow-dissolving magnesium-aluminum alloy, mainly composed of metals such as aluminum, magnesium, zinc, copper, nickel, lanthanum, lithium, neodymium, and cerium. It is cast using a special melting process, controlling the melting temperature, addition sequence, and pressure forming technology of various metals to achieve a stable chemical composition and crystal structure, ensuring slow dissolution performance, high mechanical strength, and high corrosion resistance. Aluminum accounts for 40-50%, magnesium and zinc for 30-40%, and rare metals such as lanthanum, lithium, neodymium, and cerium for 10-18%. In a high-temperature melting furnace at 1300-1800℃, aluminum, magnesium, and zinc are used as the base material, with rare metals added sequentially. Then, it is die-cast into high-density rods under 200T pressure and machined. The tensile strength is 400-500 MPa, and the dissolution time is >360 hours.

[0038] The shear seat 11 and soluble ball 12 are made of low-strength, fast-dissolving magnesium-aluminum alloy, mainly composed of magnesium, zinc, aluminum, copper, nickel, lanthanum, lithium, neodymium, cerium, and other metals. They are cast using a special melting process, controlling the melting temperature, addition order, and pressure forming technology of various metals to achieve a stable chemical composition and crystal structure, ensuring rapid dissolution, low mechanical strength, and low corrosion resistance. Magnesium and zinc account for 75-80%, aluminum for 10-15%, and rare metals such as lanthanum, lithium, neodymium, and cerium for 5-10%. In a high-temperature melting furnace at 1200-1500℃, magnesium, zinc, and aluminum are used as the matrix, with rare metals added sequentially. The mixture is then die-cast into medium-density bars under 150T pressure and machined. The tensile strength is 200-300 MPa, and the dissolution time is >24 hours.

[0039] The central tube 6 is made of high-strength, slow-dissolving aluminum alloy, mainly composed of metals such as aluminum, zinc, nickel, neodymium, and cerium. It is cast using a special melting process, controlling the melting temperature, addition order, and pressure forming technology of various metals to achieve a stable chemical composition and crystal structure, ensuring slow dissolution performance, high mechanical strength, and high corrosion resistance. Aluminum accounts for 60-70%, and rare metals account for 10-20%. In a high-temperature melting furnace at 1500-1800℃, aluminum and zinc are used as the base material, with rare metals added sequentially. Then, it is die-cast into a high-density rod under 200T pressure and machined. The tensile strength is 400-500 MPa, and the dissolution time is >360 hours.

[0040] The tension shaft 1 is threadedly connected to the shear seat 11 and the locking sleeve 2, which cooperate with each other to secure the overall structure.

[0041] The expansion cone 3 is inserted into the expansion sealing sleeve 5, and the expansion sealing sleeve 5 is aligned with the central tube 6.

[0042] The central tube 6 is located at the center of the expansion cone 3, cone sleeve 7, slip assembly, and shear seat 11. It is inserted into the shear seat 11 to support and straighten the various components of the product, prevent the components from radially deviating during insertion, ensure uniform force on the setting and sealing, and play a reinforcing supporting role to improve the pressure difference resistance.

[0043] The expansion sealing sleeve 5 is provided with stepped holes and five sealing grooves of different sizes. By adjusting the thickness and expansion rate of different parts of the sealing section and matching two types of O-rings 4, a seal from the low-pressure O-ring at the front to the overall seal of the high-pressure expansion sleeve can be achieved. The O-ring 4 is an ultra-high temperature sealing ring made of special fluororubber, manufactured using a secondary vulcanization process, and can withstand temperatures up to 230℃ / 72h.

[0044] The conical sleeve 7 is inserted into the slip assembly and aligned with the central tube 6 to open the slip assembly, causing the slip 10 to break, and the locking teeth 9 to be anchored to the sleeve.

[0045] The anti-seating ring 8 is fitted onto the cone sleeve 7 to fix the position of the cone sleeve 7 and the slip assembly, preventing the cone sleeve 7 from moving during insertion, causing the slip 10 to break and resulting in mis-seating or partial seizing.

[0046] The slip assembly includes slips 10 and teeth 9. The teeth 9 are bonded with adhesive and pressed into the tooth holes with an interference fit, forming a total of 50 teeth in 5 rows. The teeth 9 are evenly distributed downwards along the circumference of the slips 10 to ensure they do not move under a downward pressure difference of 105 MPa. The slips 10 are provided with five fracture grooves, which fracture evenly in five equal parts during setting, ensuring the slip assembly is reliably set in the sleeve.

[0047] The shear seat 11 and the slip assembly are fixed by mutually coupled grooves and protrusions to prevent the shear seat 11 from being lowered and the seat from rotating and loosening, thus ensuring reliable seating and breaking force.

[0048] The shear seat 11 is threadedly connected to the tension shaft 1. The thread type and number of teeth are strictly controlled, and the breaking force is 16±2 tons to ensure reliable setting and breaking.

[0049] The soluble ball 12 includes a soluble ball shell, KCl powder 13, and an O-ring. The shell is divided into upper and lower halves, which are connected by threads and sealed with O-rings at the ends. It contains high-concentration KCl powder 13. After being crushed, it breaks, and the KCl powder dissolves in seawater, which accelerates the dissolution of the bridge plug components.

[0050] The usage process of this invention is as follows: A soluble bridge plug is delivered to the target formation via cable. Power is applied to the wellhead for ignition, igniting the bridge plug propellant and causing relative motion in the bridge plug tool. The expansion cone 3 of the soluble bridge plug receives the thrust generated by this relative motion, propelling the expansion cone 3, expansion sealing sleeve 5, and cone sleeve 7. The cone sleeve 7 enters the slips 10, causing them to open. The teeth on the slips embed into the casing, supporting the expansion sealing sleeve 5 and the cone sleeve 7, fixing them to the casing. The expansion cone 3 continues to enter the expansion sealing sleeve 5, causing it to expand and press its upper part tightly against the casing. This, combined with the O-ring 4, forms a low-pressure sealing section, resistant to low pressure differentials of 20-35 MPa. The continued movement of the expansion cone 3 generates a tensile force of 16±2 tons between the tension shaft 1 and the shear seat 11. The tension shaft 1 breaks the threads of the shear seat 11, releasing the bridge plug from the upper tubing string and sealing it in the casing, effectively isolating and sealing multiple oil and gas layers. During fracturing, soluble balls 12 are inserted and placed on the expansion cone 3. Under the continuously increasing wellhead pressure, the expansion cone 3 continues to penetrate the expansion sealing sleeve 5, causing it to expand and tightly adhere to the casing, forming a high-pressure sealing section capable of withstanding a pressure differential of 105 MPa. This meets the operational requirements of offshore oilfields with high-salinity seawater (37,500 mg / L), ultra-high temperatures (204℃), and high pressure differentials (105 MPa).

[0051] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A seawater-based, high-mineralization, ultra-high temperature, high-pressure differential, fully soluble bridge plug, characterized in that: It includes a tension shaft (1), the upper and lower ends of which are threadedly connected to a locking sleeve (2) and a shear seat (11) respectively; between the locking sleeve (2) and the shear seat (11), there are interlocking expansion cones (3), expansion sealing sleeves (5), cone sleeves (7), and slip assembly; a central tube (6) is also provided in the expansion cones (3), expansion sealing sleeves (5), cone sleeves (7), slip assembly and shear seat (11), the central tube (6) is used to straighten, and the entire product is fixed by screwing the locking sleeve (2), tension shaft (1) and shear seat (11) towards the center.

2. The seawater-based, high-mineralization, ultra-high temperature, high-pressure differential fully soluble bridge plug according to claim 1, characterized in that: The soluble bridge plug also includes a soluble ball (12).

3. The seawater-based, high-mineralization, ultra-high temperature, high-pressure differential fully soluble bridge plug according to claim 1, characterized in that: The expansion sealing sleeve (5) is provided with stepped holes and five sealing grooves of different sizes, and two kinds of O-rings (4) are provided in the sealing grooves.

4. The seawater-based, high-mineralization, ultra-high temperature, high-pressure differential fully soluble bridge plug according to claim 1, characterized in that: An anti-seating sealing ring (8) is fitted onto the cone sleeve (7).

5. The seawater-based, high-mineralization, ultra-high temperature, high-pressure differential fully soluble bridge plug according to claim 1, characterized in that: The slip assembly includes a slip (10), on which several cracking grooves are provided; the outer wall of the slip (10) is provided with several teeth (9), which are evenly distributed downward along the circumference of the slip (10).

6. The seawater-based, high-mineralization, ultra-high temperature, high-pressure differential fully soluble bridge plug according to claim 1, characterized in that: The shear seat (11) and the slip assembly are connected by mutually coupled grooves and protrusions.

7. The seawater-based, high-mineralization, ultra-high temperature, high-pressure differential fully soluble bridge plug according to claim 2, characterized in that: The soluble sphere (12) includes a soluble sphere shell, which contains a high concentration of KCl powder (13).

8. The seawater-based, high-mineralization, ultra-high temperature, high-pressure differential fully soluble bridge plug according to claim 1, characterized in that: The expansion cone (3), expansion sealing sleeve (5), cone sleeve (7), and slip assembly are made of high-strength, slow-soluble magnesium-aluminum alloy, mainly composed of aluminum, magnesium, zinc, copper, nickel, lanthanum, lithium, neodymium, and cerium. Among them, aluminum accounts for 40-50%, magnesium and zinc account for 30-40%, and rare metals such as lanthanum, lithium, neodymium, and cerium account for 10-18%. The tensile strength is 400-500 MPa, and the dissolution time is >360h.

9. The seawater-based, high-mineralization, ultra-high temperature, high-pressure differential fully soluble bridge plug according to claim 1, characterized in that: The shear seat (11) and soluble ball (12) are made of low-strength fast-soluble magnesium-aluminum alloy, mainly composed of magnesium, zinc, aluminum, copper, nickel, lanthanum, lithium, neodymium and cerium. Among them, magnesium and zinc account for 75-80%, aluminum accounts for 10-15%, and rare metals such as lanthanum, lithium, neodymium and cerium account for 5-10%. The tensile strength is 200-300MPa and the dissolution time is >24h.

10. The seawater-based, high-mineralization, ultra-high temperature, high-pressure differential fully soluble bridge plug according to claim 1, characterized in that: The central tube (6) is made of high-strength slow-soluble aluminum alloy, mainly composed of aluminum, zinc, nickel, neodymium and cerium, of which aluminum accounts for 60-70%, rare metals account for 10-20%, tensile strength is 400-500MPa, and dissolution time is >360h.

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