A self-locking ball seat

Abstract

The application provides a self-locking ball seat, which comprises an opening sleeve, a ball catching cylinder, a pressure receiving seat and a stopper, all of which are arranged in a shell; the ball catching cylinder is arranged in the opening sleeve and connected with the opening sleeve through a first fixing part; the opening sleeve is connected with the shell through a second fixing part; the lower part of the ball catching cylinder is connected with an elastic member; the stopper is connected with the pressure receiving seat through a third fixing part, and the stopper is in contact with the side wall of the opening sleeve; the pressure receiving seat has a channel extending from the pressure receiving seat to the upper part of the ball catching cylinder; the first fixing part is cut off, so that the ball catching cylinder moves downward and compresses the elastic member; the second fixing part is cut off, so that the opening sleeve moves downward and pushes the stopper to move radially inward; the stopper cuts off the third fixing part and moves radially inward to a position; the ball catching cylinder and the ball can move upward; the side wall of the ball catching cylinder is in contact with and sealed with the inner wall of the channel, and the ball is in contact with and limited by the lower surface of the stopper. The application can prevent cement slurry from returning, realize self-locking sealing of the ball seat and improve well cementing quality.

Description

Technical Field

[0001] This invention relates to the field of oil and gas well cementing, and more specifically, to a self-locking ball seat. Background Technology

[0002] In the field of cementing deep or ultra-deep oil and gas wells, the use of tailpipe cementing technology can improve wellbore stability, protect oil and gas reservoirs, reduce drilling costs, adapt to complex geological conditions, and improve the efficiency of subsequent operations during oil and gas well drilling and completion.

[0003] Tailpipe cementing technology mainly involves: in the later stages of drilling, the tailpipe, tailpipe hanger, ball seat, float collar, and float shoe are lowered into the drilled section. After the tailpipe is in place, the ball is dropped and set, the ball seat is cleared, and the handle is released. Subsequently, cement slurry is injected into the annular space between the tailpipe and the well wall. After the cement slurry solidifies, it will form a solid cement ring that tightly bonds the tailpipe to the formation, thereby sealing the formation, supporting the well wall, preventing fluid cross-flow, and protecting the oil and gas reservoir.

[0004] Existing tailpipe cementing technology is prone to problems due to high temperature and pressure, insufficient wellbore cleaning and drilling fluid treatment, and product quality issues. These problems can easily lead to the failure of float collars and float shoes during tailpipe cementing operations, as well as inaccurate displacement metering. Consequently, the displacement plug may not be able to press against the ball seat, failing to form a seal. This can cause cement slurry backflow, resulting in a decrease in the annular fluid column, unstable well pressure, reduced cementing quality, increased economic losses, and increased safety risks. These issues can significantly impact the production progress of oil and gas wells and subsequent oil and gas development. Summary of the Invention

[0005] One objective of this invention is to provide a self-locking ball seat that can prevent cement slurry backflow under conditions where the float collar and float shoe fail and the slurry plug does not come into contact with the surface, thereby achieving a self-locking seal of the ball seat, avoiding well pressure instability caused by a decrease in the annular fluid column, improving cementing quality and reducing safety risks.

[0006] According to the present invention, a self-locking ball seat is provided, comprising: an opening sleeve, a ball-catching tube, a pressing seat, and a stop block disposed between the opening sleeve and the pressing seat, all disposed within a housing. The ball-catching tube is disposed inside the opening sleeve and connected to the opening sleeve via a first fixing part. The opening sleeve is connected to the housing via a second fixing part. An elastic element is connected to the lower part of the ball-catching tube. The stop block is connected to the pressing seat via a third fixing part, and the stop block contacts the side wall of the opening sleeve. The pressing seat has an upper part extending from the pressing seat to the ball-catching tube. The passage is designed with a square channel. After the ball is thrown and pressurized, the first fixing part is sheared, causing the ball-catching tube to descend and compress the elastic element until the lower end of the ball-catching tube contacts the inner step of the opening sleeve. Under the action of pressure difference, the second fixing part is sheared, causing the opening sleeve to descend and push the stop block to move radially inward. The stop block shears the third fixing part and moves radially inward into place. After the pump is stopped and the pressure is released, the ball-catching tube and the ball can rise. The side wall of the ball-catching tube contacts and seals the inner wall of the passage, and the ball contacts and is limited by the lower surface of the stop block.

[0007] In a preferred embodiment, the side of the opening sleeve has a circulation hole that communicates with the space below the well on one side. The side surface of the pressing seat can block the other side of the circulation hole. After the opening sleeve descends to its position, the other side of the circulation hole disengages from the pressing seat and is exposed so that it can communicate with the channel.

[0008] In a preferred embodiment, the perforated sleeve stops at a limit switch after descending to its designated position.

[0009] In a preferred embodiment, the inner wall of the perforated sleeve contacts the outer wall of the pressing seat, and the outer wall blocks the circulation hole. The inner wall is provided with a snap ring groove, and a limit snap ring is provided in the snap ring groove. The outer wall is provided with a limit groove. During the downward movement of the perforated sleeve, the limit snap ring and the limit groove cooperate to limit the perforated sleeve.

[0010] In a preferred embodiment, the self-locking ball seat further includes a support seat disposed within the housing, the upper part of the support seat having a notch, the perforated sleeve being able to descend within the notch, the lower end of the ball-catching tube having a first vertical groove, the bottom of the notch having a second vertical groove, and the two ends of the elastic element being respectively connected to the first vertical groove and the second vertical groove.

[0011] In a preferred embodiment, the space below the well is located below the support base, and a flow space communicating with the circulation hole is formed between the side surface of the perforated sleeve, the inner wall of the shell, and the outer side of the recess. A through hole is provided on the outer side of the recess, and the flow space communicates with the space below the well through the through hole.

[0012] In a preferred embodiment, the outer wall of the mating structure has a plurality of stop grooves that communicate with the channel evenly distributed radially inward on its outer peripheral surface, and each stop is accommodated in the stop groove.

[0013] In a preferred embodiment, the inner wall of the mating structure has an inclined groove at a position opposite to the stop block groove. The inclined groove contacts the side of the stop block away from the channel. During the downward movement of the opening sleeve, the inclined groove can push the stop block to extend radially inward.

[0014] In a preferred embodiment, the three-stage shear pin is disposed on the side of the stop groove near the channel and extends axially to prevent the stop from moving radially inward.

[0015] In a preferred embodiment, the upper surface of the stop block is provided with a limiting protrusion, and the inside of the stop block groove has a protrusion that can cooperate with the limiting protrusion. After the opening sleeve is stopped by limiting, the inner wall of the fitting is in abutting contact with the side of the stop block away from the channel, and the protrusion of the stop block groove cooperates with the limiting protrusion to limit the stop block.

[0016] This invention has at least the following technical effects:

[0017] According to the present invention, after the ball is thrown and pressurized, the first fixing part is sheared off, so that the ball-catching tube moves downward and compresses the elastic element; then, under the action of pressure difference, the second fixing part is sheared off, so that the opening sleeve moves downward and pushes the stop block to move radially inward, and the stop block shears off the third fixing part and moves radially inward into place; after the pump is stopped and pressure is released, under the action of the elastic force of the elastic element, the ball-catching tube and the ball can move upward, the side wall of the ball-catching tube contacts and seals the inner wall of the channel, and the ball contacts and is limited to the lower surface of the stop block, so that the ball and the ball-catching tube always maintain a contact and sealing state to form a self-locking, thereby preventing the backflow of cement slurry under the condition that the float ring and float shoe fail and the slurry plug does not touch the pressure, realizing the self-locking seal of the ball seat, avoiding the instability of well pressure caused by the reduction of the annular fluid column, improving the cementing quality and reducing safety risks.

[0018] Furthermore, due to the failure of the float ring and float shoe, the pressure difference between the liquid column of cement slurry outside the pipe and the liquid column of drilling fluid inside the pipe, together with the pressure applied by the elastic element to the ball catcher and the lower end of the ball, is greater than the pressure on the upper end of the ball catcher and the ball. Under the action of the pressure difference, the sealing between the ball catcher and the pressure seat, and between the ball and the stop block, is further increased. Attached Figure Description

[0019] Figure 1 A schematic diagram of the overall structure of the self-locking ball seat according to the present invention is shown.

[0020] Figure 2schematically shown Figure 1 A magnified structural diagram of point A in the middle;

[0021] Figure 3 A schematic diagram of the overall structure of the self-locking ball seat according to the present invention after self-locking is achieved is shown.

[0022] Figure 4 A schematic diagram of the structure of the perforated sleeve of the self-locking ball seat according to the present invention is shown.

[0023] Figure 5 A schematic diagram of the structure of the self-locking ball seat according to the present invention is shown.

[0024] Figure 6 A schematic diagram of the support base of the self-locking ball seat according to the present invention is shown.

[0025] Figure 7 A schematic diagram of the ball-catching cylinder of the self-locking ball seat according to the present invention is shown.

[0026] Figure 8 A schematic diagram of the structure of the stop block of the self-locking ball seat according to the present invention is shown.

[0027] In this application, all drawings are schematic and are used only to illustrate the principles of the invention, and are not drawn to scale. Detailed Implementation

[0028] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be understood that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In this invention, "a plurality of" refers to two or more.

[0030] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0031] like Figures 1 to 2 As shown, the self-locking ball seat 100 of the present invention includes an opening sleeve 4, a ball-catching tube 7, a pressing seat 2, and a stop block 9 disposed between the opening sleeve 4 and the pressing seat 2, all disposed within the outer casing 1. The ball-catching tube 7 is disposed in the hollow space inside the opening sleeve 4, and the ball-catching tube 7 and the opening sleeve 4 are connected by a first fixing part 10, which extends radially outward from the ball-catching tube 7 into the opening sleeve 4. The pressing seat 2 contacts the inner wall of the outer casing 1 and is fixedly connected by threads. The pressing seat 2 is disposed above the opening sleeve 4 and has a channel P for the ball 6 to pass through. The channel P extends from the pressing seat 2 to the top of the ball-catching tube 7. An elastic element 8 is connected to the lower part of the ball-catching tube 7. The opening sleeve 4 contacts the inner wall of the outer casing 1 and is connected by a second fixing part 3, which extends radially outward from the opening sleeve 4 into the outer casing 1. Optionally, both the first fixing part 10 and the second fixing part 3 can be shear pins. The stop block 9 is connected to the pressing seat 2 via the third fixing part 12 and contacts the side wall of the opening sleeve 4. The elastic element 8 can be a spring. After the ball-catching tube 7 and the opening sleeve 4 are connected via the first fixing part 10, the elastic element 8 is in a compressed state.

[0032] When ball 6 is dropped into the wellhead, it can enter the ball-catching tube 7 through the channel P inside the pressure seat 2. After the pump is turned on and pressure is built up, a pressure difference is formed inside and outside the tubing string under the sealing action of the ball-catching tube 7 and the perforated sleeve 4, thereby realizing the mounting of the tailpipe hanger. Continued pressure buildup can shear off the first fixing part 10, so that the ball-catching tube 7 moves down and compresses the elastic element 8 until the lower end of the ball-catching tube 7 contacts the inner step a of the perforated sleeve 4; under the action of the pressure difference formed by continuous pressure buildup (the pressure difference between the channel P above the ball 6 and the pressure difference below the perforated sleeve 4), the second fixing part 3 is sheared off, so that the perforated sleeve 4, the ball-catching tube 7 and the ball 6 move down together. During the downward movement of the perforated sleeve 4, its side wall can push the stop block 9 to move radially inward to shear off the third fixing part 12; after the perforated sleeve 4 moves down to the position, it is stopped by the limit, and the stop block 9 moves radially inward to the position (the position where it can contact the ball 6 after it moves up), and is limited by the side surface of the perforated sleeve 4 and the pressure seat 2.

[0033] like Figure 3As shown, after the pump is stopped and pressure is released, since there is no pressure difference between the top of ball 6 and the bottom of ball catcher 7 and the elastic element 8 is in a compressed state, ball catcher 7 and ball 6 can move upward under the rebound force of elastic element 8, so that the side wall of ball catcher 7 can contact and seal with the inner wall of channel P, and ball 6 contacts and is limited by the lower surface of stop 9, so that ball 6 and ball catcher 7 always maintain contact and sealing state to form self-locking. In this way, it can prevent cement slurry backflow under the condition that float ring and float shoe fail and the slurry plug does not touch the pressure, realize ball seat self-locking seal, avoid well pressure instability caused by the reduction of annular liquid column, improve cementing quality and reduce safety risks. Furthermore, due to the failure of the float ring and float shoe, the pressure difference between the liquid column of cement slurry outside the pipe and the liquid column of drilling fluid inside the pipe, together with the pressure applied by the elastic element to the ball catcher and the lower end of the ball, is greater than the pressure on the upper end of the ball catcher and the ball. Under the action of pressure difference, the sealing between the ball catcher and the pressure seat, and between the ball and the stop block, is further increased.

[0034] like Figure 3 , Figure 4 As shown, in one or more embodiments, the side of the opening sleeve 4 is provided with a plurality of circulation holes 16 that communicate with the space below the well on one side. The side surface of the pressure seat 2 can block the other side of the circulation hole 16. After the opening sleeve 4 is lowered into place, the other side of the circulation hole 16 is disengaged from the pressure seat 2 and exposed so as to communicate with the internal channel P of the pressure seat. This can prevent the ball 6 of the self-locking valve from falling off after being blocked, and always keep the ball 6 in contact with the upper part of the ball-catching cylinder 7 to form a seal, which facilitates the formation of self-locking.

[0035] like Figure 4 , Figure 5 As shown, in one or more embodiments, the opening sleeve 4 stops after descending to its designated position. Specifically, the inner wall of the opening sleeve 4 contacts the outer wall of the pressing seat 2, and the outer wall blocks the circulation hole 16. A retaining spring groove 17 is provided on the inner wall, and a limiting retaining spring 11 is provided in the retaining spring groove 17. A limiting groove 15 is provided on the outer wall. During the descent of the opening sleeve 4, the limiting retaining spring 11 can cooperate with the limiting groove 15 to limit the opening sleeve 4 and prevent the opening sleeve 4 from continuing to descend.

[0036] like Figure 6 , Figure 7 As shown, in one or more embodiments, the self-locking ball seat 100 of the present invention further includes a support seat 5 disposed within the housing 1 and fixedly connected to the housing 1. Optionally, the support seat 5 contacts the inner wall of the housing 1 and is connected by threads. A notch 51 is provided on the upper part of the support seat 5, and the perforated sleeve 4 can move downward within the notch 51. A first vertical groove 21 is provided at the lower end of the ball-catching cylinder 7, and a second vertical groove 20 is provided on the bottom surface of the notch 51. The two ends of the elastic member 8 are respectively connected to the first vertical groove 21 and the second vertical groove 20.

[0037] In one or more embodiments, the space below the well is located below the support base 5. A flow space communicating with the circulation hole 16 is formed between the side surface of the opening sleeve 4, the inner wall of the housing 1, and the upper surface of the outer side of the recess 51. A plurality of through holes 19 in the axial direction are provided on the outer side of the recess 51. The flow space is connected to the space below the well through the through holes 19.

[0038] In one or more embodiments, the outer wall has a plurality of stop grooves 14 that communicate with the channel P evenly distributed radially inward on the outer peripheral surface. The stop grooves 14 are close to the bottom of the channel P and the limiting grooves 15 are located above the stop grooves 14. Each stop 9 is accommodated in the stop groove 14.

[0039] like Figure 1 , Figure 2 , Figure 4 and Figure 8 As shown, in one or more embodiments, the inner wall of the mating device has an inclined groove 18 at a position opposite to the stop groove 14. The inclined groove 18 contacts the side of the stop 9 away from the channel P. During the downward movement of the opening sleeve 4, the inclined groove 18 can gradually push the stop 9 radially inward through its inclined surface. The upper surface of the stop 9 is provided with a limiting protrusion. The inside of the stop groove 14 has a protrusion that can cooperate with the limiting protrusion. After the opening sleeve 4 stops at the limit, the inner wall of the mating device abuts against the side of the stop 9 away from the channel P, and the protrusion of the stop groove 14 cooperates with the limiting protrusion to limit the stop 9.

[0040] In one or more embodiments, a third fixing part 12 is disposed on the side of the stop groove 14 near the channel P and extends in the axial direction to prevent the stop 9 from moving radially inward.

[0041] like Figure 2 , 7 As shown, in one or more embodiments, a sealing ring groove 22 is provided on the outer periphery of the upper end of the ball-catching cylinder 7, and a sealing ring 13 is provided inside the sealing ring groove 22. The ball-catching cylinder 7 and the ball 6 move upward under the action of the elastic force of the elastic member 8, and the side wall of the ball-catching cylinder 7 is in contact with the inner wall of the channel P. The sealing performance can be further ensured by the sealing ring 13.

[0042] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A self-locking ball seat, comprising: The opening sleeve, the ball catching cylinder, the pressure receiving seat and the stopper are arranged in the shell, the ball catching cylinder is arranged in the opening sleeve and connected with the opening sleeve through the first fixing part, the opening sleeve is connected with the shell through the second fixing part, the lower part of the ball catching cylinder is connected with the elastic member, the stopper is connected with the pressure receiving seat through the third fixing part, and the stopper is in contact with the side wall of the opening sleeve; the pressure receiving seat has a channel extending from the pressure receiving seat to the upper part of the ball catching cylinder; After the ball is thrown and pressure is stored, the first fixing part is cut off, so that the ball catching cylinder goes down and compresses the elastic member until the lower end of the ball catching cylinder is in contact with the inner step of the opening sleeve; under the action of pressure difference, the second fixing part is cut off, so that the opening sleeve goes down and pushes the stopper to move radially inward, the stopper cuts off the third fixing part and moves radially inward to the position; after the pump is stopped and pressure is released, the ball catching cylinder and the ball can go up, the side wall of the ball catching cylinder is in contact with the inner wall of the channel and is sealed, and the ball is in contact with the lower surface of the stopper and is limited; The side part of the opening sleeve is provided with a circulation hole in communication with the space below the well, and the side surface of the pressure receiving seat can block the other side of the circulation hole, after the opening sleeve goes down to the position, the other side of the circulation hole is separated from the pressure receiving seat and exposed to be in communication with the channel; The matching inner wall of the opening sleeve is in contact with the matching outer wall of the pressure receiving seat, the matching outer wall is uniformly distributed with a plurality of stopper grooves in the radial direction on the outer surface, each stopper is arranged in the stopper groove, the matching inner wall is provided with an inclined groove at the position opposite to the stopper groove, the inclined groove is in contact with the side of the stopper away from the channel, and during the descending process of the opening sleeve, the inclined groove can push the stopper to extend radially inward.

2. The self-locking tee of claim 1, wherein, The opening sleeve is limited and stopped after going down to the position.

3. The self-locking tee of claim 2, wherein, The matching outer wall blocks the circulation hole, the matching inner wall is provided with a snap spring groove, a limiting snap spring is arranged in the snap spring groove, the matching outer wall is provided with a limiting groove, and during the descending process of the opening sleeve, the limiting snap spring cooperates with the limiting groove to limit the opening sleeve.

4. The self-locking tee of claim 2, wherein, The support seat arranged in the shell is further included, the upper part of the support seat is provided with a notch, the opening sleeve can go down in the notch, the lower end of the ball catching cylinder is provided with a first vertical groove, the bottom of the notch is provided with a second vertical groove, and the two ends of the elastic member are respectively connected in the first vertical groove and the second vertical groove.

5. The self-locking tee of claim 4, wherein, The space below the well is located below the support seat, the side surface of the opening sleeve, the inner wall of the shell and the outside of the notch form a flow-through space in communication with the circulation hole, the outside of the notch is provided with a through hole, and the flow-through space is in communication with the space below the well through the through hole.

6. The self-locking tee of claim 1, wherein, The third fixing part is arranged on the side of the stopper groove close to the channel and extends in the axial direction to prevent the stopper from moving radially inward.

7. The self-locking tee of claim 1, wherein, The upper surface of the stopper is provided with a limiting protrusion, the stopper groove has a protrusion capable of cooperating with the limiting protrusion, after the opening sleeve is limited and stopped, the matching inner wall is in abutting contact with the side of the stopper away from the channel, and the protrusion of the stopper groove cooperates with the limiting protrusion to limit the stopper.

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