Removable ball seat assembly and assembly, anti-corrosion drilling liner hanger and seat hanging method

Abstract

The invention discloses a liftable ball seat assembly and assembly, an anti-corrosion drilling liner hanger and a seat hanging method. The liftable ball seat assembly comprises a body, a gear rack assembly arranged in a through hole of the body, a pressing cap assembly and a ball seat. A central pipe connecting part is arranged at one end of the body; the pressing cap assembly is provided with at least one conical surface and an explosion valve; the ball seat is provided with a ball bowl structure; the gear and rack assembly comprises a rack push sleeve and a gear, the rack push sleeve is arranged outside the pressing cap assembly and can move in the axial direction under the action of pressure, and the gear rotates under the action of the rack push sleeve; the ball seat is arranged in the ball bowl and is provided with two coaxial conical surfaces and a ball seat through hole of which the central axis is vertical to the central axis of the conical surfaces; the ball seat is provided with a gear installation groove for installing a gear used for driving the ball seat to rotate. Comprising the ball seat assembly can realize multiple times of ball injection and multiple times of sealing, guarantee smooth seat hanging of the hanger, effectively avoid seat hanging failure, can be lifted out through a central pipe, and does not have the problem that an alloy ball seat cannot be drilled.

Description

Technical Field

[0001] The present invention relates to the technical field of cementing, and particularly to a retrievable ball seat assembly and components, a corrosion-resistant liner hanger, and a method for realizing liner setting. Background Art

[0002] With the continuous development of oil and gas exploration and development towards deeper and ultra-deeper depths, higher requirements are put forward for cementing technology. During the cementing process, liner hanging operations are often required. Currently, most of the liner hanger setting systems use a hydraulic setting method. A pressure-holding ball is dropped from the wellhead, and the hanger is set by the pressure-holding ball seating and pressure-holding with a drillable aluminum alloy ball seat installed at the bottom of the well. Summary of the Invention

[0003] The inventors of the present application found that in the currently commonly used hydraulic setting method, due to the long circulation time before the hanger is set and the corrosion of the aluminum alloy ball seat caused by the strong alkali and high salt environment in the wellbore, the problem that the hanger cannot be set frequently occurs. If other anti-corrosion alloy ball seats are used, after the hanger is set, the alloy ball seat cannot be drilled out, resulting in abnormal construction of subsequent operations. Moreover, the currently commonly used metal ball seats can only be set once. In the case of poor setting effect, the setting operation cannot be completed. In short, the hydraulic setting method in the prior art cannot meet the setting requirements of the continuously increasing well depth and continuously lengthening liner.

[0004] In view of the above problems, the present invention is proposed to provide a retrievable ball seat assembly and components, a corrosion-resistant liner hanger, and a method for realizing liner setting that can overcome or at least partially solve the above problems.

[0005] An embodiment of the present invention provides a retrievable ball seat assembly, including: a body, a gear-rack assembly, a compression cap assembly, and a ball seat disposed in the through hole of the body;

[0006] One end of the body is provided with a central pipe connection portion for connecting the central pipe;

[0007] The compression cap assembly is provided with at least one conical surface for receiving the pressure-holding ball, and a blasting valve for rupturing under the pressure-holding state so that the wellbore pressure acts on the gear-rack assembly. The compression cap assembly has a ball bowl structure;

[0008] The gear-rack assembly includes a rack push sleeve and a gear assembly. The rack push sleeve is disposed outside the compression cap assembly and can move axially under pressure. The gear assembly rotates under the action of the rack push sleeve;

[0009] The ball seat is arranged in the ball bowl. The ball seat is provided with two coaxial conical surfaces and a ball seat through hole whose central axis is perpendicular to the central axis of the conical surface. The ball seat is provided with a gear mounting groove for mounting the gear assembly, and the gear assembly is used to drive the ball seat to rotate along a rotating shaft perpendicular to the central axis of the gland assembly.

[0010] In some alternative embodiments, the gland assembly includes an upper gland and a lower gland.

[0011] The upper gland is provided with a first conical surface, a second conical surface and a first ball bowl. The diameter of the small-diameter end of the first conical surface is the same as the diameter of the large-diameter end of the second conical surface. The upper gland is provided with a bursting disc mounting hole for mounting a bursting disc. The bursting disc mounting hole can communicate the body through hole with the annulus outside the gland assembly, so that the wellbore pressure acts on the gear in the gear-rack assembly to push the sleeve after the bursting disc bursts.

[0012] The lower gland is provided with a second ball bowl.

[0013] In some alternative embodiments, the bursting disc includes two hollow cylinders and a bursting disc located between the two central cylinders. The bursting disc can rupture under the wellbore pressure to connect the through holes of the two hollow cylinders.

[0014] In some alternative embodiments, the rack push sleeve includes a piston sleeve and two ear plates.

[0015] The ear plates are provided with racks and anti-rotation bosses, so that the rack push sleeve moves along the axis under the action of the wellbore pressure.

[0016] The gear assembly includes a gear and an anti-rotation shaft. The gear assembly is installed in the gear mounting groove of the ball seat, can mesh with the rack, and rotates when the rack push sleeve moves axially to drive the ball seat to rotate.

[0017] In some alternative embodiments, the ball seat includes a spherical surface and two parallel side surfaces.

[0018] The ball seat is provided with a coaxial third conical surface and a fourth conical surface.

[0019] The central axis of the shaft seat through hole provided on the ball seat is perpendicular to the central axes of the third conical surface and the fourth conical surface.

[0020] The ball seat is provided with two gear mounting grooves. The central axis of the gear mounting groove is perpendicular to the central axis of the shaft seat through hole, and is also perpendicular to the central axes of the third conical surface and the fourth conical surface.

[0021] In some alternative embodiments, a tail pipe plug connecting mechanism is provided at the other end of the body to connect to a tail pipe plug; an anti-rotation groove for a rack push sleeve is provided on the body to cooperate with an anti-rotation boss on an ear plate of the rack push sleeve, and an anti-rotation groove for a gear is provided on the body to cooperate with an anti-rotation boss on the gear, enabling the gear to rotate about its axis.

[0022] In some alternative embodiments, seals are provided between the body and the ball cap assembly, between the body and the gear-rack assembly, between the ball cap assembly and the ball seat, and between the ball cap assembly and the gear-rack assembly.

[0023] An embodiment of the present invention provides a retrievable ball seat assembly, including: a central pipe, a ball seat assembly, and a tail pipe plug connected in sequence.

[0024] The ball seat assembly is the above-mentioned retrievable ball seat assembly.

[0025] In some alternative embodiments, a central pipe connection thread is provided at one end of the body of the ball seat assembly to connect to the central pipe; a pin hole is provided at the other end of the body of the ball seat assembly to connect to the tail pipe plug through a pin.

[0026] In some alternative embodiments, the tail pipe plug includes a plug body, a metal elastic support framework, and a rubber disc.

[0027] The rubber disc is elastic and includes a cylindrical rubber disc body and at least one elastic conical cylinder extending from the rubber disc body; the rubber disc is fixed to the plug body by a vulcanization process, and the outer diameter of the rubber disc is greater than the inner diameter of the tail pipe.

[0028] The metal elastic support framework is embedded in the rubber disc, and the metal elastic support framework includes a plurality of sub-frameworks, each sub-framework including a thin-walled cylinder and a thin-walled conical cylinder connected together.

[0029] An embodiment of the present invention provides an anti-corrosion tail pipe hanger, including: a tie-back cylinder, a releasing sub, a suspension assembly, and a tail pipe that are connected in sequence and form an inner through hole; and the above-mentioned retrievable ball seat assembly that can be placed into the inner through hole.

[0030] In some alternative embodiments, the releasing sub is a mechanical reverse releasing sub, the suspension assembly is a hydraulically actuated slip hanger, and the central pipe in the ball seat assembly can be connected to a running-in tool joint.

[0031] The suspension assembly includes a piston and slips, and the piston and slips move axially under the condition of wellbore pressure buildup to complete setting.

[0032] An embodiment of the present invention provides a method for realizing tail pipe setting, which is realized by the above-mentioned anti-corrosion tail pipe hanger.

[0033] An embodiment of the present invention provides a method for realizing a liner hanger, including:

[0034] After inserting a No. 1 pressure - holding ball that fits with the fourth conical surface on the ball seat in the retrievable ball seat assembly to block the central flow channel, the liquid enters the annulus between the suspension assembly and the central pipe, and pushes the piston and slips in the suspension assembly to move axially to complete the hanging;

[0035] After the hanging is completed, the liquid pressure acts on the bursting valve of the gland assembly in the retrievable ball seat assembly, penetrates the bursting disc in the bursting valve, the gland assembly pushes the rack push sleeve in the rack - and - pinion assembly to move and drives the pinion to rotate, drives the ball seat to rotate through the pinion, and makes the No. 1 pressure - holding ball fall to the bottom of the well through the through - hole of the ball seat.

[0036] In some alternative embodiments, the above - mentioned method further includes:

[0037] In the case where the No. 1 pressure - holding ball and the fourth conical surface cannot form an effective sealed pressure - holding, after inserting a No. 2 pressure - holding ball that fits with the third conical surface on the ball seat in the retrievable ball seat assembly to block the central flow channel, the liquid enters the annulus between the suspension assembly and the central pipe, and pushes the piston and slips in the suspension assembly to move axially to complete the hanging;

[0038] After the hanging is completed, the liquid pressure acts on the bursting valve of the gland assembly in the retrievable ball seat assembly, penetrates the bursting disc in the bursting valve, the gland assembly pushes the rack push sleeve in the rack - and - pinion assembly to move and drives the pinion to rotate, drives the ball seat to rotate through the pinion, and makes the No. 2 pressure - holding ball fall to the bottom of the well through the through - hole of the ball seat.

[0039] In some alternative embodiments, the above - mentioned method further includes:

[0040] In the case where neither the No. 1 pressure - holding ball and the fourth conical surface nor the No. 2 pressure - holding ball and the third conical surface can form an effective sealed pressure - holding, insert a No. 3 pressure - holding ball that fits with the second conical surface on the gland assembly in the retrievable ball seat assembly, or insert a No. 4 pressure - holding ball that fits with the first conical surface on the gland assembly in the retrievable ball seat assembly; after blocking the central flow channel through the No. 3 pressure - holding ball or the No. 4 pressure - holding ball, the liquid enters the annulus between the suspension assembly and the central pipe, and pushes the piston and slips in the suspension assembly to move axially to complete the hanging; after the hanging is completed, the No. 3 pressure - holding ball or the No. 4 pressure - holding ball deforms under pressure and falls to the bottom of the well; the No. 3 pressure - holding ball and the No. 4 pressure - holding ball are made of elastic materials;

[0041] Or

[0042] When the No. 1 pressure-holding ball and the fourth conical surface, or the No. 2 pressure-holding ball and the third conical surface can form an effective sealed pressure hold, if the ball seat rotates in place incompletely, resulting in the No. 1 pressure-holding ball or the No. 2 pressure-holding ball not dropping, then insert the No. 3 pressure-holding ball that fits with the second conical surface on the pressure cap assembly in the retrievable ball seat assembly, or insert the No. 4 pressure-holding ball that fits with the first conical surface on the pressure cap assembly in the retrievable ball seat assembly. After blocking the central flow channel with the No. 3 pressure-holding ball or the No. 4 pressure-holding ball, the liquid pressure acts on the bursting valve of the pressure cap assembly in the retrievable ball seat assembly, piercing the bursting disc in the bursting valve. The pressure cap assembly pushes the rack push sleeve in the gear-rack assembly to move and drives the gear to rotate. The gear drives the ball seat to rotate, causing the No. 1 pressure-holding ball or the No. 2 pressure-holding ball to drop to the bottom of the well through the through hole of the ball seat.

[0043] The beneficial effects of the above technical solutions provided by the embodiments of the present invention at least include:

[0044] In the retrievable ball seat assembly of the embodiment of the present invention, multiple conical surfaces are provided on the pressure cap assembly and the ball seat. Through the multiple conical surfaces, the placement of multiple different models of pressure-holding balls can be realized; two conical surfaces are provided on the ball seat assembly. In the case where one of the conical surfaces fails due to erosion sealing, the other conical surface can still be used for pressure-holding sealing; the pressure-holding ball that fits with the conical surface on the ball seat after placement can drop to the bottom of the well through the through hole of the ball seat after pressure holding and completing the setting; when the pressure-holding ball that fits with the ball seat fails or the ball seat rotates in place incompletely and cannot drop, the pressure-holding ball that fits with the conical surface on the pressure cap assembly can be inserted to seal and hold pressure again, enabling the pressure-holding ball to drop smoothly. Using this ball seat assembly for the suspension of the hanger shortens the circulation time before the hanger is set, and the hanger can be retrieved. Therefore, corrosion-resistant materials can be used to avoid corrosion, without worrying about the problem that the pressure-holding balls made of corrosion-resistant materials such as metal cannot drop, nor worrying about the problem that the ball seats made of corrosion-resistant materials such as metal cannot be drilled, ensuring the smooth progress of the construction and meeting the setting requirements of the continuously increasing well depth and the continuously lengthening liner.

[0045] The ball seat assembly provided by the embodiment of the present invention includes the above-mentioned ball seat assembly, which can realize multiple ball placements and multiple seals, and can be retrieved through the central pipe, without worrying about the problem that the ball seats made of corrosion-resistant materials such as metal cannot be drilled, ensuring the smooth progress of the construction and meeting the different requirements of drilling at different times.

[0046] The corrosion-resistant liner hanger provided by the embodiment of the present invention includes the above-mentioned ball seat assembly, which can realize multiple ball placements and multiple seals, ensuring that the suspension assembly can be successfully set in the wellbore and will not fail to set due to corrosion or other reasons. After the setting is completed, the ball seat assembly can be retrieved through the central pipe, without worrying about the problem that the ball seats made of corrosion-resistant materials such as metal cannot be drilled, ensuring the smooth progress of the construction and meeting the different requirements of drilling at different times.

[0047] Other features and advantages of the present invention will be set forth in the following description, and in part will be obvious from the description, or may be learned by practice of the present invention. The objectives and other advantages of the present invention may be realized and attained by the structure particularly pointed out in the written description, claims, as well as the drawings.

[0048] The technical solution of the present invention will be further described in detail below with reference to the drawings and embodiments. Description of the Drawings

[0049] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, but do not constitute a limitation to the present invention. In the drawings:

[0050] Figure 1 is a schematic structural diagram of the corrosion-resistant liner hanger in the embodiment of the present invention;

[0051] Figure 2 is a schematic structural diagram of the retrievable ball seat assembly in the embodiment of the present invention;

[0052] Figure 3 is a schematic structural diagram of the retrievable ball seat assembly in the embodiment of the present invention;

[0053] Figure 4 is a schematic structural diagram of the retrievable ball seat assembly after the ball seat rotates in the embodiment of the present invention;

[0054] Figure 5 is a three-dimensional structural diagram of the retrievable ball seat assembly after assembly in the embodiment of the present invention;

[0055] Figure 6 is a schematic structural diagram of the blasting valve in the embodiment of the present invention;

[0056] Figure 7 is a three-dimensional structural diagram of the rack push sleeve in the embodiment of the present invention;

[0057] Figure 8 is a front projection view of the rack push sleeve in the embodiment of the present invention;

[0058] Figure 9 is a schematic cross-sectional structure diagram of the anti-rotation groove on the body in the embodiment of the present invention;

[0059] Figure 10 is a schematic structural diagram of the metal elastic support framework in the embodiment of the present invention;

[0060] Figure 11 is a schematic partial structural diagram of the suspension system in the embodiment of the present invention.

[0061] Description of the Reference Numerals:

[0062] 1. Feed-through joint; 2. Retrievable barrel; 3. Release sub; 4. Hanger assembly; 5. Central tube; 6. Ball seat assembly; 7. Liner plug; 8. Liner;

[0063] 4-1. Piston; 4-2. Slip;

[0064] 5-1. Pressure transfer inclined hole;

[0065] 6-1. Body; 6-2. Upper pressure cap; 6-3. Burst valve; 6-4. Filter screen; 6-5. Rack push sleeve; 6-6. Ball seat; 6-7. Gear assembly; 6-8. Lower pressure cap;

[0066] 6-2-1. First sealing ring; 6-2-2. Second sealing ring; 6-2-3. Third sealing ring; 6-2-4. Pressure cap shear pin;

[0067] 6-3-1. Threaded connection head; 6-3-2. Bursting disc; 6-3-3. Sealing plug; 6-3-4. Burst valve sealing ring;

[0068] 6-5-1. Fifth sealing ring; 6-5-2. Piston sleeve; 6-5-3. Ear plate; 6-5-4. First anti-rotation boss; 6-5-5. Second anti-rotation boss; 6-5-6. Rack meshing teeth;

[0069] 6-7-1. Gear; 6-7-2. Anti-rotation shaft; 6-7-3. Gear connection thread;

[0070] 6-8-1. Fourth sealing ring;

[0071] 7-1. Plug shear pin; 7-2. Plug sealing ring; 7-3. Plug matrix; 7-4. Rubber disc; 7-5. Metal elastic support skeleton;

[0072] C1. Second gear assembly anti-rotation groove; C3. Second gear assembly anti-rotation groove; C2. First rack push sleeve anti-rotation groove; C4 Second rack push sleeve anti-rotation groove;

[0073] Z1. First conical surface; Z2. Second conical surface; Z3. Third conical surface; Z4. Fourth conical surface. Detailed implementation manners

[0074] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be completely conveyed to those skilled in the art.

[0075] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0076] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0077] Since the existing hydraulic seat-hanging method can no longer meet the requirements of setting and hanging for the continuously increasing well depth and the continuously lengthening liner, and during the setting and hanging process, the wear resistance and wall-scraping effect of the liner plug also need to be further improved. Therefore, in order to solve the problems existing in the prior art, it is very necessary to develop an anti-corrosion retrievable ball seat for a corrosion-resistant liner hanger. Based on this, the embodiments of the present invention provide a retrievable ball seat assembly and a corresponding hanger to realize the setting and hanging of the liner. For this retrievable ball seat liner hanger, the erosion resistance and corrosion resistance of its ball seat are greatly improved. At the same time, it also has the advantages of retrievable ball seat, capable of multiple setting, good wall-scraping effect, short waiting time for ball throwing, etc., and can well meet the setting and hanging requirements under the conditions of increasing well depth and lengthening liner.

[0078] The embodiments of the present invention provide a retrievable ball seat corrosion-resistant liner hanger, and its structure is as Figure 1 shown, including: a tie-back cylinder 2, a release sub 3, a suspension assembly 4 and a liner 8 that are sequentially connected and form an inner through hole, and a retrievable ball seat assembly that can be placed into the inner through hole. The retrievable ball seat assembly includes a central tube 5, a retrievable ball seat assembly 6 and a liner plug 7 that are sequentially connected.

[0079] Optionally, the above corrosion-resistant liner hanger may further include a running-in sub 1, and the running-in sub 1 is connected to the central tube 5.

[0080] The embodiments of the present invention provide a retrievable ball seat assembly, including a central tube 5, a retrievable ball seat assembly 6 and a liner plug 7 that are sequentially connected. Its structure is shown in Figure 2 shown, Figure 2The retrievable ball seat assembly placed in the liner 8 is shown.

[0081] The central tube 5 is provided with pressure transmission inclined holes 5-1, so as to realize the transmission of the pressure in the internal through hole of the central tube to the annulus between the central tube and the liner 8, the hanging assembly 4, and the releasing sub 3.

[0082] The retrievable ball seat assembly 6 has a multi-stage setting and ball seat rotation function. After at least one pressure-holding ball is put into the retrievable ball seat assembly 6 to form a pressure-holding state, the hanging assembly 4 completes the setting under the action of pressure.

[0083] The liner plug 7 is a liner plug with an elastic skeleton. The elastic skeleton has a certain elasticity and a certain rigidity, so as to form a good seal between the liner plug and the liner.

[0084] The embodiment of the present invention provides a retrievable ball seat assembly, and its structure is as Figure 3 、 Figure 4 and Figure 5 shown, wherein Figure 3 is the front view of the ball seat assembly, Figure 4 is Figure 3 the front view of the ball seat assembly after the ball seat in Figure 5 is turned over, and

[0085] One end of the body 6-1 is provided with a central tube connection part to connect the central tube 5;

[0086] The pressure cap assembly is provided with at least one conical surface to receive the pressure-holding ball, and is provided with a blasting valve 6-3 so as to rupture under the pressure-holding state to make the wellbore pressure act on the gear-rack assembly. The pressure cap assembly has a ball bowl structure;

[0087] The gear-rack assembly includes a rack push sleeve 6-5 and a gear assembly 6-7. The rack push sleeve 6-5 is arranged outside the pressure cap assembly and can move axially under the action of pressure. The gear assembly 6-7 rotates under the action of the rack push sleeve 6-5;

[0088] The ball seat 6-6 is arranged in the ball bowl. The ball seat 6-6 is provided with two coaxial conical surfaces and a ball seat through hole whose central axis is perpendicular to the central axis of the conical surface. The ball seat 6-6 is provided with a gear installation groove to install the gear assembly 6-7. The gear assembly 6-7 is used to drive the ball seat 6-6 to rotate along the rotation axis perpendicular to the central axis of the pressure cap assembly.

[0089] In some alternative embodiments, sealing elements are provided between the body and the ball cap assembly, between the body and the gear-rack assembly, between the ball cap assembly and the ball seat, and between the ball cap assembly and the gear-rack assembly.

[0090] In some alternative embodiments, the ball seat 6-6 includes a spherical surface and two parallel sides; a coaxial third conical surface Z3 and a fourth conical surface Z4 are provided on the ball seat 6-6; the central axis of the shaft seat through hole provided on the ball seat 6-6 is perpendicular to the central axes of the third conical surface Z3 and the fourth conical surface Z4; two gear mounting grooves are provided on the ball seat 6-6, and the central axes of the gear mounting grooves are perpendicular to the central axis of the shaft seat through hole and are also perpendicular to the central axes of the third conical surface Z3 and the fourth conical surface Z4.

[0091] The outer surface of the ball seat 6-6 includes a spherical surface and two symmetric parallel sides. The interior of the ball seat 6-6 includes an upper and a lower set of third conical surfaces Z3 and fourth conical surfaces Z4 with the same cone angle, and also includes a straight through hole coaxial with the fourth conical surface Z4. The ball seat 6-6 also includes a through hole with a diameter the same as the large end diameter of the third conical surface Z3 and the small end diameter of the second conical surface Z2 of the upper pressing cap. The central axis of this through hole is perpendicular to the central axis of the third conical surface Z3, that is, it is also perpendicular to the central axis of the fourth conical surface Z4 and parallel to the two sides of the ball seat 6-6. Two sets of symmetrically distributed gear assembly connection threaded holes are included on the two symmetric parallel sides of the ball seat 6-6 for connecting the gears in the gear assembly. The third conical surface Z3 and the fourth conical surface Z4 are the inner surfaces of the conical holes, and the large end diameter of the third conical surface Z3 is larger than the large end diameter of the fourth conical surface Z.

[0092] In some alternative embodiments, the pressing cap assembly includes an upper pressing cap 6-2 and a lower pressing cap 6-8;

[0093] The upper pressing cap 6-2 is provided with a first conical surface Z1, a second conical surface Z2, and a first ball bowl. The small diameter end diameter of the first conical surface is the same as the large diameter end diameter of the second conical surface; a blasting valve mounting hole is provided on the upper pressing cap 6-2 to mount the blasting valve 6-3. The blasting valve mounting hole can communicate the body through hole with the annulus outside the pressing cap assembly so that the wellbore pressure acts on the rack push sleeve 6-5 in the gear rack assembly after the blasting valve 6-3 blasts; the lower pressing cap 6-8 is provided with a second ball bowl. The small end diameter of the first conical surface Z1 is equal to the large end diameter of the second conical surface Z2.

[0094] The outer surface of the upper pressing cap 6-2 is a stepped structure. One set of first sealing rings 6-2-1 is designed on the first step surface and is fixedly connected to the body 6-1 through threads. One set of second sealing rings 6-2-2 and one set of pressing cap shear pin 6-2-4 mounting threaded holes are designed on the second step surface. The inner surface of the upper pressing cap 6-2 includes a first conical surface Z1, a second conical surface Z2, and a sealing spherical surface that mates with the ball seat 6-6. A blasting valve mounting hole and a pressure transmission channel coaxial with the body are designed on the first conical surface Z1. The upper end of the mounting hole is a threaded hole and the lower end is a through hole. One set of third sealing rings 6-2-3 is designed on the spherical surface.

[0095] The inner surface of the lower pressing cap 6-8 is a sealing spherical surface designed with a fourth sealing ring 6-8-1. The outer surface of the lower pressing cap 6-8 is designed with threads and a sealing surface for connection to the body 6-1.

[0096] Among them, a filter screen 6-4 can be arranged in the bursting valve mounting hole, and the lower end of the bursting valve 6-3 contacts the filter screen 6-4 to achieve limit. The structure of the bursting valve 6-3 is as Figure 6 shown, including two hollow cylinders and a bursting disc located between the two central cylinders. The bursting disc can rupture under the wellbore pressure to connect the through holes of the two hollow cylinders.

[0097] The filter screen 6-4 is a circular filter sheet with multiple holes, which is installed at the bottom end of the bursting valve mounting hole and limited by the mounting hole step. Refer to Figure 6 shown, the bursting valve 6-3 includes a threaded connection head 6-3-1, a bursting disc 6-3-2, a sealing plug 6-3-3, and a bursting valve sealing ring 6-3-4, which can all be made of metal parts. Each metal part is connected together by a welding process and fixed in the bursting valve mounting hole of the upper pressing cap 6-2 by a threaded connection method, and its lower end contacts the filter screen 6-4 for limit.

[0098] In some alternative embodiments, the structure of the rack push sleeve is shown in Figure 7 and Figure 8 shown, including a piston sleeve 6-5-2 and two ear plates; racks and anti-rotation bosses are provided on the ear plates so that the rack push sleeve moves along the axis under the wellbore pressure; the gear assembly includes a gear and an anti-rotation shaft, and the gear assembly is installed in the gear mounting groove of the ball seat and can mesh with the rack and rotate when the rack push sleeve moves axially to drive the ball seat to rotate.

[0099] Refer to Figure 7 shown, the rack push sleeve 6-5 includes an annular piston sleeve 6-5-2 with a fifth sealing ring 6-5-1, ear plates 6-5-3, a first anti-rotation boss 6-5-4, a second anti-rotation boss 6-5-5, and rack meshing teeth 6-5-6. Observed axially, the outer surface of the ear plate 6-5-3 is a cylindrical surface concentric with the annular piston sleeve 6-5-2, the inner surface is a horizontal plane, and both sides are straight surfaces. The two ear plates 6-5-3 are symmetrically distributed on one side of the central plane, and a plurality of rack meshing teeth 6-5-6 are evenly distributed on the vertical plane on one side of the ear plate 6-5-3 close to the vertical center line. The outer surfaces of the first anti-rotation boss 6-5-4 and the second anti-rotation boss 6-5-5 are concentric with the annular piston sleeve 6-5-2. The intersection line of the plane where the side surface of the first anti-rotation boss 6-5-4 and the side surface of the second anti-rotation boss 6-5-5 are located coincides with the axis of the annular piston sleeve. The first anti-rotation boss 6-5-4 and the second anti-rotation boss 6-5-5 can move axially in the rack push sleeve anti-rotation groove on the body 6-1 but cannot rotate around the axis of the body 6-1.

[0100] There are two sets of gear assemblies 6-7, including gears 6-7-1, anti-rotation shafts 6-7-2, and gear connection threads 6-7-3, which are symmetrically fixed on the ball seat 6-6 by means of threaded connection. The anti-rotation shaft 6-7-2 of the gear assembly 6-7 can axially move in the anti-rotation groove of the gear assembly on the main body 6-1, and the gear assembly 6-7 can rotate around the anti-rotation shaft 6-7-2, but cannot rotate around the axis of the main body 6-1.

[0101] In some alternative embodiments, one end of the main body 6-1 is provided with a central tube connection portion to connect the central tube 5, and the other end of the main body 6-1 is provided with a tail tube rubber plug connection mechanism to connect the tail tube rubber plug; a rack push sleeve anti-rotation groove is provided on the main body 6-1 to cooperate with the anti-rotation boss on the rack push sleeve ear plate, and a gear anti-rotation groove is provided on the main body 6-1 to cooperate with the anti-rotation boss on the gear, so that the gear rotates around its axis.

[0102] In some alternative embodiments, the above-mentioned ball seat assembly can be proposed. One end of the main body of the ball seat assembly is provided with a central tube connection thread as the central tube connection portion to connect the central tube; the other end of the main body of the ball seat assembly is provided with a pin hole as the tail tube rubber plug connection mechanism, so as to connect the tail tube rubber plug through the rubber plug shear pin 7-1. See Figure 2 As shown, the ball seat assembly 6 is connected to the bottom end of the central tube 5 by means of threaded connection, and the tail tube rubber plug 7 is fixed to the lower end of the ball seat 6-6 through the rubber plug shear pin 7-1 and sealed by a sealing ring.

[0103] The above-mentioned ball seat assembly can be proposed, and the metal part material thereof can be processed by using 13Cr or other anti-corrosion materials, and the rubber part material is fluororubber. The main body 6-1 is connected to the central tube 5 by means of threaded connection, and its lower end is inserted together with the tail tube rubber plug 7 and fixed through the rubber plug shear pin 7-1, and is sealed by the rubber plug sealing ring 7-2 at the same time. The inside of the main body 6-1 is designed with an upper pressing cap sealing groove and an upper pressing cap connection thread, a rack push sleeve 6-5 sealing surface, a rack push sleeve anti-rotation groove, a gear assembly anti-rotation groove, a lower pressing cap sealing groove and a lower pressing cap connection thread from top to bottom in sequence.

[0104] For the cross-sectional structure of the anti-rotation groove on the main body, see Figure 9 As shown, there are two sets of rack push sleeve anti-rotation grooves and gear assembly anti-rotation grooves, which are symmetrically distributed on both sides of the central plane. See Figure 9 As shown, the first gear assembly anti-rotation groove C1 and the second gear assembly anti-rotation groove C3 are symmetrically arranged, and the center line thereof passes through the central axis of the main body; the first rack push sleeve anti-rotation groove C2 and the second rack push sleeve anti-rotation groove C4 are located on one side of the connection line of C1 and C3 and are symmetrically arranged with respect to the axis perpendicular to the connection line of C1 and C3.

[0105] The bottom of the anti-rotation groove C2 of the first rack push sleeve, the anti-rotation groove C4 of the second rack push sleeve, the anti-rotation groove C1 of the first gear assembly, and the anti-rotation groove C3 of the second gear assembly are arc-shaped and concentric with the body 6-1. The intersection line of the planes where the two side surfaces of the anti-rotation groove C2 of the first rack push sleeve and the anti-rotation groove C4 of the second rack push sleeve are located coincides with the central axis of the body 6-1. The central planes of the anti-rotation groove C2 of the first rack push sleeve and the anti-rotation groove C4 of the second rack push sleeve are misaligned with the central planes of the anti-rotation groove C1 of the first gear assembly and the anti-rotation groove C3 of the second gear assembly by an angle α. The two sides of the anti-rotation groove C1 of the first gear assembly and the anti-rotation groove C3 of the second gear assembly are symmetric straight surfaces.

[0106] In some alternative embodiments, the tail pipe rubber plug of the above-mentioned ball seat assembly includes a rubber plug matrix 7-3, a metal elastic support skeleton 7-5, and a rubber disc 7-4;

[0107] The rubber disc is elastic and includes a cylindrical rubber disc matrix and at least one elastic conical cylinder extending from the rubber disc matrix; the rubber disc is fixed to the rubber plug matrix by a vulcanization process, and the outer diameter of the rubber disc is greater than the inner diameter of the tail pipe;

[0108] The metal elastic support skeleton is embedded in the rubber disc, and the metal elastic support skeleton includes a plurality of sub-skeletons, and each sub-skeleton includes a thin-walled cylinder and a thin-walled conical cylinder connected together.

[0109] For the structure of the metal elastic support skeleton, see Figure 10 As shown, the tail pipe rubber plug 7 and the lower end of the ball seat assembly 6 are coaxially fixed by a rubber plug shear pin and sealed by a rubber plug sealing ring 7-2. The rubber disc 7-4 of the tail pipe rubber plug is integrally vulcanized on the rubber plug matrix 7-3 by a vulcanization process, and the metal elastic support skeleton 7-5 is embedded in the rubber disc 7-4. The metal elastic support skeleton 7-5 is composed of multiple groups of thin-walled conical cylinders and thin-walled cylinders welded together, and each conical cylinder and cylinder are designed with a plurality of uniformly distributed round holes. The outer end of each conical cylinder is bent. The outer diameter of the rubber disc 7-4 is greater than the inner diameter of the tail pipe 8, and the rubber disc 7-4 fits against the inner wall of the tail pipe 8 to seal the annular channel between the tail pipe 8 and the tail pipe rubber plug 7. Through the elastic extrusion of the rubber and the elastic force of the metal elastic support skeleton 7-5, the sealing pressure can be increased, and the bending part of the elastic skeleton 7-5 can enhance the rubber scraping effect on the wall.

[0110] The anti-corrosion tail pipe hanger proposed above in the embodiments of the present invention includes a running-in sub 1, a tie-back cylinder 2, a releasing sub 3, a suspension assembly 4, a central pipe 5, a ball seat assembly 6, a tail pipe rubber plug 7, and a tail pipe 8. The upper end of the running-in sub 1 can be connected to the running-in drill string, and the lower end is connected to the central pipe 5. The tie-back cylinder 2 is a sealing cylinder for the tie-back plug of the tail pipe hanger, the releasing sub is a mechanical reverse-thread releasing sub, and the suspension assembly is a hydraulically actuated slip-type hanger; the central pipe 5 is provided with a reverse-thread releasing mechanism and a sealing sleeve that cooperate with the releasing sub 3.

[0111] The above anti-corrosion liner hanger can be divided into a running-in system and a hanging system. Among them, the running-in system includes a running-in sub 1, a central tube 5, and a ball seat assembly 6, which are connected together by threads. The hanging system includes a tie-back cylinder 2, a releasing sub 3, a hanging assembly 4, and a liner 8. The tie-back cylinder 2, the releasing sub 3, the hanging assembly 4, and the liner 8 are connected together by threads. For the local structure of the hanging system, refer to Figure 11 As shown, an annulus is formed between the central tube 5 and the hanging assembly 4, and an annulus is also formed between the piston 4-1 and the releasing sub 3. There is a through hole connecting the two annuli, so that the liquid pressure can act on the piston 4-1 to push the piston 4-1 to move axially and cooperate with the slips 4-2 to complete setting and make the anti-corrosion liner hanger complete hanging.

[0112] The running-in system and the hanging system are connected by a reverse-thread releasing mechanism, and the annular space between the running-in system and the hanging system is sealed off by a sealing sleeve. After the anti-corrosion liner hanger is lowered in place, circulation is carried out through the running-in sub 1, the central tube 5, the ball seat conical hole, and the inner hole of the liner plug 7. A plurality of evenly distributed pressure-transferring inclined holes 5-1 are designed at the bottom end connecting sleeve of the central tube 5 to connect the inner cavities of the central tube 5 and the hanging assembly 4.

[0113] The retrievable ball seat anti-corrosion liner hanger provided by the embodiment of the present invention improves the erosion resistance and backpressure resistance of the float shoe (a device for guiding the casing string into the well smoothly). In order to achieve the anti-corrosion function, the whole set of tools is processed with non-metallic sealing materials and alloy materials with alkali-proof and high-salt corrosion resistance, or the surface treatment technology of chemical but not limited to chemical methods is adopted to achieve the anti-alkali and high-salt corrosion of the tools.

[0114] For the above anti-corrosion liner hanger, its setting ball seat is connected to the bottom end of the central tube of the hanger, which can shorten the waiting time for ball dropping; the ball seat is made of erosion-resistant and corrosion-resistant alloy materials, which can improve the anti-corrosion and erosion resistance performance. The setting ball seat has a plurality of sealing conical surfaces, which can realize multiple ball dropping and setting to ensure the smooth hanging of the hanger. After the hanger is hung, the gear mechanism is rotated by the hydraulic system to force the ball seat core to rotate, and the setting channel is converted to a large-diameter circulation channel. After the construction is completed, the ball seat can be retrieved from the wellbore along with the central tube without drilling. At the same time, an elastic skeleton is used to strengthen the strength and scraping effect of the plug, improving the sealing reliability and displacement efficiency. Using the retrievable ball seat anti-corrosion liner hanger for the hanging operation of the liner hanger can greatly improve the hanging success rate of the liner hanger.

[0115] The above retrievable ball seat assembly, ball seat component, and anti-corrosion liner hanger can enable the function of multiple ball dropping, setting, and pressure building. Specifically, multi-stage setting means that the ball seat assembly 6 has the function of multiple ball dropping, setting, and pressure building.

[0116] Based on the same inventive concept, the embodiment of the present invention also provides a method for realizing liner hanging, including:

[0117] After inserting the No. 1 pressure-holding ball that fits the fourth conical surface on the ball seat in the input and retrievable ball seat assembly to block the central flow channel, the liquid enters the annulus between the hanging assembly and the central pipe, and pushes the piston and slips in the hanging assembly to move axially to complete the setting;

[0118] After the setting is completed, the liquid pressure acts on the bursting valve of the pressure cap assembly in the retrievable ball seat assembly, piercing the bursting disc in the bursting valve. The pressure cap assembly pushes the rack push sleeve in the rack and pinion assembly to move and drives the gear to rotate. The ball seat is driven by the gear to rotate, so that the No. 1 pressure-holding ball drops to the bottom of the well through the through hole of the ball seat.

[0119] In the above method, when setting is required, the No. 1 pressure-holding ball is inserted from the wellhead and lands on the fourth conical surface Z4 of the ball seat to block the circulation channel. Continue to hold pressure. The liquid enters the annulus between the hanging assembly 4 and the central pipe 5 through the pressure transmission inclined hole 5-1 of the central pipe, and enters the inner cavity of the piston 4-1, further pushing the piston 4-1 and slips 4-2 of the setting assembly to move axially to complete the setting. Further continue to hold pressure. The piston 4-1 reaches the limit position and stops moving. The pressure acts on the bursting valve 6-3, piercing the bursting disc 6-3-2. The pressure is transmitted to the end face of the rack push sleeve 6-5, shearing the pressure cap shear pin 6-2-4 and pushing the rack ear plate 6-5-3 to move downward axially, and driving the gear to rotate through the meshing teeth 6-5-6 of the rack and the gear 6-7-1, driving the ball seat 6-6 to rotate around the central axis. The stroke of the rack push sleeve 6-5 can drive the gear 6-7-1 and the ball seat 6-6 to rotate 90°, and turn to the through hole circulation channel with the same diameter as the small end of the second conical surface Z2 of the upper pressure cap. The No. 1 ball falls to the bottom of the well through the channel. The rack push sleeve 6-5 is separated from the second sealing ring 6-2-2, losing the seal, and the pressure difference between its upper and lower parts is the same, and it stops moving.

[0120] In some alternative embodiments, the above method further includes:

[0121] In the case where the No. 1 pressure-holding ball and the fourth conical surface cannot form an effective seal to hold pressure, after inserting the No. 2 pressure-holding ball that fits the third conical surface on the ball seat in the retrievable ball seat assembly to block the central flow channel, the liquid enters the annulus between the hanging assembly and the central pipe, and pushes the piston and slips in the hanging assembly to move axially to complete the setting;

[0122] After the setting is completed, the liquid pressure acts on the bursting valve of the pressure cap assembly in the retrievable ball seat assembly, piercing the bursting disc in the bursting valve. The pressure cap assembly pushes the rack push sleeve in the rack and pinion assembly to move and drives the gear to rotate. The ball seat is driven by the gear to rotate, so that the No. 2 pressure-holding ball drops to the bottom of the well through the through hole of the ball seat.

[0123] Since there is more than one conical surface provided on the ball seat of the ball seat assembly, when a problem occurs with one of the conical surfaces, for example, when it cannot form an effective seal with the corresponding pressure - holding ball to achieve sealed pressure - holding, another conical surface can be used in cooperation with the corresponding pressure - holding ball to achieve sealed pressure - holding. For example: when the No. 1 pressure - holding ball seats, if the fourth conical surface Z4 of the ball seat is eroded and cannot hold pressure, then the No. 2 pressure - holding ball that cooperates with the third conical surface Z3 of the ball seat is put in, and the processes such as setting - up, ball - seat flipping, and the falling off of the setting ball are completed in a similar process after the No. 1 pressure - holding ball is put in. Or when it is known that the fourth conical surface Z4 of the ball seat is eroded and cannot hold pressure, the No. 1 pressure - holding ball is not put in and the No. 2 pressure - holding ball is directly put in to cooperate with the third conical surface Z3 of the ball seat, and the processes such as setting - up, ball - seat flipping, and the falling off of the setting ball are completed in a similar process after the No. 1 pressure - holding ball is put in.

[0124] The No. 1 pressure - holding ball and the No. 2 pressure - holding ball can be rigid balls, such as metal balls, specifically copper balls.

[0125] In some alternative embodiments, the above - mentioned method further includes:

[0126] In the case where neither the No. 1 pressure - holding ball and the fourth conical surface nor the No. 2 pressure - holding ball and the third conical surface can form an effective sealed pressure - holding, the No. 3 pressure - holding ball that cooperates with the second conical surface on the pressure - cap assembly in the retrievable ball - seat assembly is put in, or the No. 4 pressure - holding ball that cooperates with the first conical surface on the pressure - cap assembly in the retrievable ball - seat assembly is put in; after the central flow channel is blocked by the No. 3 pressure - holding ball or the No. 4 pressure - holding ball, the liquid enters through and makes the piston and slips in the suspension assembly move axially to complete the setting - up; after the setting - up is completed, the No. 3 pressure - holding ball or the No. 4 pressure - holding ball deforms under the action of pressure and drops to the bottom of the well; the No. 3 pressure - holding ball and the No. 4 pressure - holding ball are made of elastic materials;

[0127] In some alternative embodiments, the above - mentioned method further includes:

[0128] In the case where the No. 1 pressure - holding ball and the fourth conical surface, or the No. 2 pressure - holding ball and the third conical surface can form an effective sealed pressure - holding, if the ball seat does not rotate in place and causes the No. 1 pressure - holding ball or the No. 2 pressure - holding ball not to drop, the No. 3 pressure - holding ball that cooperates with the second conical surface on the pressure - cap assembly in the retrievable ball - seat assembly is put in, or the No. 4 pressure - holding ball that cooperates with the first conical surface on the pressure - cap assembly in the retrievable ball - seat assembly is put in. After the central flow channel is blocked by the No. 3 pressure - holding ball or the No. 4 pressure - holding ball, the liquid pressure acts on the rupture valve of the pressure - cap assembly in the retrievable ball - seat assembly, piercing the rupture disk in the rupture valve, and the pressure - cap assembly pushes the rack - push sleeve in the gear - rack assembly to move and drives the gear to rotate. The ball seat is driven to rotate by the gear, so that the No. 1 pressure - holding ball or the No. 2 pressure - holding ball drops through the through - hole of the ball seat to the bottom of the well.

[0129] If the No. 1 pressure - holding ball and the No. 2 pressure - holding ball fail and cannot form an effective seal, the No. 3 pressure - holding ball that mates with the second conical surface Z2 of the upper pressure cap 6 - 2 is inserted to complete the setting process, or the No. 4 pressure - holding ball that mates with the first conical surface Z1 of the upper pressure cap 6 - 2 is inserted to complete the setting process and cause the ball seat to flip. The No. 3 pressure - holding ball and the No. 4 pressure - holding ball can be made of elastic spheres, such as plastic material balls, specifically, they can be made of polytetrafluoroethylene, but not limited to this. In this way, under continuous pressure - holding, the No. 3 pressure - holding ball or the No. 4 pressure - holding ball undergoes plastic deformation, detaches from the ball seat 6 - 6, and falls into the bottom of the well.

[0130] If the ball seat cannot flip into place after the No. 1 pressure - holding ball or the No. 2 pressure - holding ball is inserted, resulting in the pressure - holding ball being unable to drop, the No. 3 pressure - holding ball that mates with the second conical surface Z2 of the upper pressure cap 6 - 2 or the No. 4 pressure - holding ball that mates with the first conical surface Z1 of the upper pressure cap 6 - 2 can also be inserted to cause the ball seat to flip. For example: when the No. 1 pressure - holding ball or the No. 2 pressure - holding ball that mates with the ball seat 6 - 6 is pressure - held and set, during the continuous pressure - holding process, due to seal failure, the ball seat 6 - 6 cannot be completely flipped by 90°, resulting in the No. 1 pressure - holding ball or the No. 2 pressure - holding ball being unable to drop, then the No. 3 ball can be inserted to complete the flipping of the ball seat. Whether the ball seat 6 - 6 is completely flipped can be judged according to the wellhead circulation pump pressure. The No. 3 pressure - holding ball is used when both the No. 1 and No. 2 balls cannot achieve pressure - holding or setting, and the pressure - holding after setting cannot cause the ball seat to be completely flipped. Generally, it is not directly used.

[0131] During cementing, after the tail - pipe plug 7 checks and shears the plug shear pin 7 - 1 of the drill - pipe plug, and the tail - pipe plug 7 runs to the bottom of the well to complete the bump pressure, the ball - seat assembly 6 can be lifted out of the wellbore together with the running - in sub 1 and the central tube 5.

[0132] In the above - mentioned method of the embodiment of the present invention, through multiple conical holes provided in the ball - seat assembly, the placement of pressure - holding balls of various different models can be realized, and through the flipping of the ball seat, the pressure - holding ball that mates with the ball seat can fall through the straight through - hole on the ball seat, so that multiple ball - throwing and multiple setting can be realized, ensuring the smooth setting of the corrosion - resistant liner hanger.

[0133] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the protection scope of the present disclosure. The appended method claims present the elements of various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy.

[0134] In the foregoing detailed description, various features are combined in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that the embodiments of the claimed subject matter require more features than are expressly recited in each claim. On the contrary, as reflected in the appended claims, the invention lies in less than the full scope of the features of the single disclosed embodiment. Accordingly, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0135] The above description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but one of ordinary skill in the art should recognize that the various embodiments can be further combined and arranged. Accordingly, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Further, with respect to the term "comprising" as used in the specification or claims, this term is inclusive in a manner similar to the term "including", as that term is interpreted when used as a transitional word in a claim. Also, any use of the term "or" in the claims or specification is to be meant "non-exclusive or".

Claims

1. A ball seat assembly that can be withdrawn, characterized in that, Comprising: A body, a gear-rack assembly, a compression cap assembly and a ball seat disposed in a through-hole of the body; One end of the body is provided with a central pipe connection portion for connecting a central pipe; The compression cap assembly is provided with at least one conical surface for receiving a pressure-holding ball, and is provided with a bursting valve so as to burst under a pressure-holding state to enable the wellbore pressure to act on the gear-rack assembly, and the compression cap assembly has a ball bowl structure; The gear-rack assembly includes a rack push sleeve and a gear assembly. The rack push sleeve is disposed outside the compression cap assembly and can axially move under the action of pressure, and the gear assembly rotates under the action of the rack push sleeve; The ball seat is disposed in the ball bowl. The ball seat is provided with two coaxial conical surfaces and a ball seat through-hole whose central axis is perpendicular to the central axes of the conical surfaces. The ball seat is provided with a gear mounting groove for mounting the gear assembly, and the gear assembly is used for driving the ball seat to rotate around a rotating shaft perpendicular to the central axis of the compression cap assembly.

2. The ball seat assembly according to claim 1, characterized in that, The compression cap assembly includes an upper compression cap and a lower compression cap; The upper compression cap is provided with a first conical surface, a second conical surface and a first ball bowl. The diameter of the small-diameter end of the first conical surface is the same as the diameter of the large-diameter end of the second conical surface. The upper compression cap is provided with a bursting valve mounting hole for mounting a bursting valve, and the bursting valve mounting hole can communicate the through-hole of the body with the annulus outside the compression cap assembly, so that the wellbore pressure acts on the gear that pushes the sleeve in the gear-rack assembly after the bursting valve bursts; The lower compression cap is provided with a second ball bowl.

3. The ball seat assembly according to claim 1, characterized in that, The bursting valve includes two hollow cylinders and a bursting disc located between the two central cylinders. The bursting disc can burst under the wellbore pressure to communicate the through-holes of the two hollow cylinders.

4. The ball seat assembly according to claim 1, characterized in that, The rack push sleeve includes a piston sleeve and two ear plates; The ear plates are provided with racks and anti-rotation bosses so that the rack push sleeve moves along the axis under the action of the wellbore pressure; The gear assembly includes a gear and an anti-rotation shaft. The gear assembly is mounted in the gear mounting groove of the ball seat, can mesh with the rack, and rotates when the rack push sleeve axially moves to drive the ball seat to rotate.

5. The ball seat assembly according to claim 1, characterized in that, The ball seat includes a spherical surface and two parallel side surfaces; The ball seat is provided with coaxial third and fourth conical surfaces; The central axis of the shaft seat through-hole provided on the ball seat is perpendicular to the central axes of the third and fourth conical surfaces; The ball seat is provided with two gear mounting grooves. The central axes of the gear mounting grooves are perpendicular to the central axis of the shaft seat through-hole, and are also perpendicular to the central axes of the third and fourth conical surfaces.

6. The ball seat assembly according to claim 1, characterized in that, The other end of the body is provided with a liner plug connection mechanism for connecting a liner plug; the body is provided with a rack push sleeve anti-rotation groove for cooperating with the anti-rotation boss on the ear plate of the rack push sleeve, and the body is provided with a gear anti-rotation groove for cooperating with the anti-rotation boss on the gear to enable the gear to rotate around its axis.

7. The ball seat assembly according to any one of claims 1-6, characterized in that, Sealing members are provided between the body and the ball cap assembly, between the body and the gear-rack assembly, between the ball cap assembly and the ball seat, and between the ball cap assembly and the gear-rack assembly.

8. A ball seat component that can be withdrawn, characterized in that, Comprising: A central pipe, a ball seat assembly and a liner plug connected in sequence; The ball seat assembly is the ball seat assembly that can be ejected as described in any one of claims 1-7.

9. The ball seat component that can be withdrawn according to claim 8, characterized in that, One end of the body of the ball seat assembly is provided with a central pipe connection thread for connecting the central pipe; the other end of the body of the ball seat assembly is provided with a pin hole for connecting the liner plug through a pin.

10. The ball seat component that can be withdrawn according to claim 8, characterized in that, The liner plug includes a plug body, a metal elastic support skeleton and a rubber disc; The rubber disc is elastic and includes a cylindrical rubber disc body and at least one elastic conical cylinder extending from the rubber disc body; the rubber disc is fixed to the plug body by a vulcanization process, and the outer diameter of the rubber disc is larger than the inner diameter of the liner. The metal elastic support skeleton is embedded in the rubber disc, and the metal elastic support skeleton includes a plurality of sub-skeletons, and each sub-skeleton includes a thin-walled cylinder and a thin-walled conical cylinder connected together.

11. An anti-corrosion liner hanger, characterized in that, Comprising: A tie-back cylinder, a release sub, a suspension assembly and a liner that are connected in sequence and form an inner through hole; and a retrievable ball seat assembly as described in any one of claims 8-10 that can be placed in the inner through hole.

12. The anti-corrosion liner hanger according to claim 11, characterized in that, The release sub is a mechanical reverse-thread release sub, the suspension assembly is a hydraulically actuated slip-type hanger, and the central pipe in the ball seat assembly can be connected to a running-in sub. The suspension assembly includes a piston and slips, and the piston and slips move axially under the condition of wellbore pressure buildup to complete setting.

13. A method for realizing a liner hanger, characterized in that, Realized by the corrosion-resistant liner hanger as described in any one of claims 11-12.

14. A method for realizing a liner hanger, characterized in that, Comprising: After putting in a No. 1 pressure buildup ball that fits the fourth conical surface on the ball seat in the retrievable ball seat assembly to block the central flow channel, the liquid enters through the annulus between the suspension assembly and the central pipe, and pushes the piston and slips in the suspension assembly to move axially to complete setting; After setting is completed, the liquid pressure acts on the burst valve of the pressure cap assembly in the retrievable ball seat assembly, piercing the burst disc in the burst valve, the pressure cap assembly pushes the rack push sleeve in the gear-rack assembly to move and drives the gear to rotate, and drives the ball seat to rotate through the gear, so that the No. 1 pressure buildup ball drops to the bottom of the well through the ball seat through hole.

15. The method according to claim 14, characterized in that, Further comprising: In the case where the No. 1 pressure buildup ball and the fourth conical surface cannot form an effective sealing pressure buildup, after putting in a No. 2 pressure buildup ball that fits the third conical surface on the ball seat in the retrievable ball seat assembly to block the central flow channel, the liquid enters through the annulus between the suspension assembly and the central pipe, and pushes the piston and slips in the suspension assembly to move axially to complete setting; After setting is completed, the liquid pressure acts on the burst valve of the pressure cap assembly in the retrievable ball seat assembly, piercing the burst disc in the burst valve, the pressure cap assembly pushes the rack push sleeve in the gear-rack assembly to move and drives the gear to rotate, and drives the ball seat to rotate through the gear, so that the No. 2 pressure buildup ball drops to the bottom of the well through the ball seat through hole.

16. The method according to claim 15, characterized in that, Further comprising: In the case where neither the No. 1 pressure-holding ball and the fourth conical surface nor the No. 2 pressure-holding ball and the third conical surface can form an effective sealed pressure hold, insert the No. 3 pressure-holding ball that mates with the second conical surface on the pressure cap assembly of the retrievable ball seat assembly, or insert the No. 4 pressure-holding ball that mates with the first conical surface on the pressure cap assembly of the retrievable ball seat assembly; after blocking the central flow channel with the No. 3 pressure-holding ball or the No. 4 pressure-holding ball, allow the liquid to enter the annulus between the suspension assembly and the central pipe, and push the piston and slips in the suspension assembly to axially move to complete setting; after setting is completed, the No. 3 pressure-holding ball or the No. 4 pressure-holding ball deforms under pressure and drops to the bottom of the well; the No. 3 pressure-holding ball and the No. 4 pressure-holding ball are made of elastic materials; or In the case where the No. 1 pressure-holding ball and the fourth conical surface or the No. 2 pressure-holding ball and the third conical surface can form an effective sealed pressure hold, if the ball seat does not rotate into place and causes the No. 1 pressure-holding ball or the No. 2 pressure-holding ball not to drop, insert the No. 3 pressure-holding ball that mates with the second conical surface on the pressure cap assembly of the retrievable ball seat assembly, or insert the No. 4 pressure-holding ball that mates with the first conical surface on the pressure cap assembly of the retrievable ball seat assembly. After blocking the central flow channel with the No. 3 pressure-holding ball or the No. 4 pressure-holding ball, the liquid pressure acts on the burst valve of the pressure cap assembly of the retrievable ball seat assembly, piercing the burst disk in the burst valve. The pressure cap assembly pushes the rack push sleeve in the rack and pinion assembly to move and drives the pinion to rotate. The pinion drives the ball seat to rotate, causing the No. 1 pressure-holding ball or the No. 2 pressure-holding ball to drop through the through hole of the ball seat to the bottom of the well.

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