Self-locking ball seat

Abstract

The invention provides a self-locking ball seat which comprises a hole opening sleeve, a ball catching barrel, a bumping seat and a stop dog which are all arranged in a shell, the ball catching barrel is arranged in the hole opening sleeve and connected with the hole opening sleeve through a first fixing part, the hole opening sleeve is connected with the shell through a second fixing part, the lower portion of the ball catching barrel is connected with an elastic piece, and the elastic piece is connected with the bumping seat. The stop block is connected with the bumping seat through a third fixing part, and the stop block is in contact with the side wall of the trepanning sleeve; a channel extending to the position above the ball catching barrel from the bumping seat is formed in the bumping seat. The first fixing part is cut off, so that the ball catching barrel moves downwards and compresses the elastic piece; the second fixing part is sheared off, so that the tapping sleeve moves downwards and pushes the check block to move inwards in the radial direction, and the check block shears off the third fixing part and moves inwards in place in the radial direction; the ball catching barrel and the ball can move upwards, the side wall of the ball catching barrel makes contact with the inner wall of the channel and is sealed, and the ball makes contact with the lower surface of the check block and is limited. Cement paste can be prevented from returning, self-locking sealing of the ball seat is achieved, and the well cementation quality is improved.

Description

Technical Field

[0001] The invention relates to the field of oil and gas well cementing, and in particular to a self-locking ball seat. Background Art

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

[0003] The liner cementing technology mainly involves: in the later stage of drilling, the liner, liner hanger, ball seat, float collar and float shoe are lowered into the drilled section. After the liner is in place, the ball is dropped and hung, the ball seat is blocked and the hand is released. Subsequently, cement slurry is injected into the annular space between the liner and the well wall. After the cement slurry solidifies, a solid cement ring will be formed to tightly consolidate the liner and the formation together, thereby isolating the formation, supporting the well wall, preventing fluid crossflow and protecting the oil and gas layer.

[0004] The existing liner cementing technology is prone to failure of the float collar and float shoe during liner cementing operations and inaccurate slurry replacement metering due to high temperature and high pressure, inadequate wellbore cleaning and drilling fluid treatment, and product quality. This makes it difficult for the slurry replacement plug to hit the ball seat and form a seal, causing cement slurry backflow, resulting in a reduction in the annular liquid column, unstable well pressure, reduced cementing quality, increased economic losses, and increased safety risks, which greatly affects the production progress of oil and gas wells and subsequent oil and gas development. Summary of the invention

[0005] One purpose of the present invention is to provide a self-locking ball seat, which can prevent cement slurry from returning when the floating collar and floating shoe fail and the slurry replacement plug does not collide and press, thereby achieving self-locking sealing of the ball seat, avoiding unstable well pressure due to the reduction of the annular liquid column, improving cementing quality and reducing safety risks.

[0006] According to the present invention, a self-locking ball seat is provided, comprising: an aperture sleeve, a ball catching tube, a pressure seat and a stopper arranged between the aperture sleeve and the pressure seat, the ball catching tube being arranged inside the aperture sleeve and connected to the aperture sleeve via a first fixing portion, the aperture sleeve and the shell being connected via a second fixing portion, an elastic member being connected to the lower portion of the ball catching tube, the stopper being connected to the pressure seat via a third fixing portion, and the stopper being in contact with the side wall of the aperture sleeve; the pressure seat has an upper portion extending from the pressure seat to the ball catching tube. the first fixing part is sheared off after the ball is thrown and the pressure is accumulated, so that the ball catching tube moves downward and compresses the elastic member until the lower end of the ball catching tube contacts the inner step of the opening sleeve; under the action of the pressure difference, the second fixing part is sheared off, so that the opening sleeve moves downward and pushes the stopper to move radially inward, and the stopper shears off the third fixing part and moves radially inward into position; after the pump is stopped and the pressure is released, 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 by the lower surface of the stopper.

[0007] In a preferred embodiment, a circulation hole is opened on the side of the opening sleeve, one side of which is connected to the space below the well, and the side surface of the impact and pressure seat can block the other side of the circulation hole. After the opening sleeve descends into place, the other side of the circulation hole is separated from the impact and pressure seat and exposed so as to be connected to the channel.

[0008] In a preferred embodiment, the opening sleeve stops at a limit position after descending to a certain position.

[0009] In a preferred embodiment, the mating inner wall of the hole-opening sleeve contacts the mating outer wall of the impact and pressure seat, and the mating outer wall blocks the circulation hole, the mating inner wall is provided with a retaining spring groove, a limiting retaining spring is provided in the retaining spring groove, and the mating outer wall is provided with a limiting groove, and during the downward movement of the hole-opening sleeve, the limiting retaining spring cooperates with the limiting groove to limit the hole-opening sleeve.

[0010] In a preferred embodiment, the self-locking ball seat also includes a support seat arranged in the shell, the support seat is provided with a recess on the upper portion, the open hole sleeve can move downward in the recess, the lower end of the ball catching tube is provided with a first vertical groove, the bottom of the recess is provided with a second vertical groove, and the two ends of the elastic member are 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 seat, and a circulation space connected to the circulation hole is formed between the side surface of the opening sleeve, the inner wall of the shell and the outer side of the recess, and a through hole is opened on the outer side of the recess, and the circulation space is connected to the space below the well through the through hole.

[0012] In a preferred embodiment, the mating outer wall has a plurality of block grooves uniformly distributed radially inwardly on the outer circumferential surface thereof and communicating with the channel, and each of the blocks is accommodated in the block groove.

[0013] In a preferred embodiment, the mating inner wall is provided with an oblique groove at a position opposite to the block groove, the oblique groove contacts the side of the block away from the channel, and during the downward movement of the opening sleeve, the oblique groove can push the block to extend radially inward.

[0014] In a preferred embodiment, the three-stage shear nail is arranged on a side of the stopper groove close to the channel and extends axially to prevent the stopper from moving radially inward.

[0015] In a preferred embodiment, a limiting protrusion is provided on the upper surface of the block, and the inside of the block groove has a convex portion that can cooperate with the limiting protrusion. After the opening sleeve is stopped by limiting, the cooperating inner wall is pressed and contacted with the side of the block away from the channel and the convex portion of the block groove cooperates with the limiting protrusion to limit the block.

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

[0017] According to the present invention, after the ball is thrown and the pressure is built up, the first fixing part is sheared off, so that the ball catching tube moves downward and compresses the elastic member; subsequently, under the action of the pressure difference, the second fixing part is sheared off, so that the perforated sleeve moves downward and pushes the stopper to move radially inward, and the stopper shears off the third fixing part and moves radially inward into position; after the pump is stopped and the pressure is released, under the action of the elastic force of the elastic member, the ball catching tube and the ball can move upward, the side wall of the ball catching tube contacts and seals with the inner wall of the channel, and the ball contacts and is limited with the lower surface of the stopper, so that the ball and the ball catching tube always maintain a contact and sealing state to form a self-locking state, thereby preventing cement slurry from returning under the condition that the floating collar and the floating shoe fail and the slurry replacement plug does not collide and press, realizing the self-locking seal of the ball seat, avoiding the instability of the wellbore pressure due to the reduction of the annular liquid column, improving the cementing quality and reducing the safety risk.

[0018] In addition, due to the failure of the float hoop and the 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 to the lower end of the ball catch tube and the ball by the elastic member, is greater than the pressure exerted on the upper end of the ball catch tube and the ball. Under the action of the pressure difference, the sealing between the ball catch tube and the impact seat, and between the ball and the block is further increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The overall structure diagram of the self-locking ball seat according to the present invention is schematically shown;

[0020] Figure 2Schematically shows Figure 1 The schematic diagram of the structure after the enlargement of A in the middle;

[0021] Figure 3 The overall structure diagram of the self-locking ball seat after self-locking according to the present invention is schematically shown;

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

[0023] Figure 5 The schematic diagram of the structure of the impact and pressure seat of the self-locking ball seat according to the present invention is shown schematically;

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

[0025] Figure 7 The structure diagram of the ball catching cylinder of the self-locking ball seat according to the present invention is schematically shown;

[0026] Figure 8 The structural diagram of the stopper of the self-locking ball seat according to the present invention is schematically shown.

[0027] In the present application, all drawings are schematic drawings, which are only used to illustrate the principles of the present invention and are not drawn according to the actual scale. DETAILED DESCRIPTION

[0028] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In the description of the present 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 drawings, and are 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 cannot be understood as limiting the present invention. In the present invention, "multiple" refers to two or more.

[0030] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixed" and the like 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, an electrical connection, or a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] like Figure 1 to Figure 2 As shown, the self-locking ball seat 100 of the present invention comprises an opening sleeve 4, a ball catching tube 7, a collision seat 2, and a stopper 9 arranged between the opening sleeve 4 and the collision seat 2, the ball catching tube 7 being arranged in the hollow space inside the opening sleeve 4, and the ball catching tube 7 being connected to the opening sleeve 4 through a first fixing portion 10, and the first fixing portion 10 extending radially outward from the ball catching tube 7 into the opening sleeve 4. The collision seat 2 contacts the inner wall of the outer shell 1 and is fixedly connected by threads, the collision seat 2 is arranged above the opening sleeve 4 and has a passage P inside for the ball 6 to pass, and the passage P extends from the collision seat 2 to the upper part of the ball catching tube 7. The lower part of the ball catching tube 7 is connected with an elastic member 8, the opening sleeve 4 contacts the inner wall of the outer shell 1 and is connected through a second fixing portion 3, and the second fixing portion 3 extends radially outward from the opening sleeve 4 into the outer shell 1. Optionally, the first fixing portion 10 and the second fixing portion 3 can both be shear nails. The stopper 9 is connected to the impact and pressure seat 2 through the third fixing portion 12 and contacts the side wall of the perforated sleeve 4. The elastic member 8 can be a spring. After the ball catching tube 7 is connected to the perforated sleeve 4 through the first fixing portion 10, the elastic member 8 is in a compressed state.

[0032] When the ball 6 is dropped at the wellhead, the ball 6 can enter the ball catching tube 7 through the channel P inside the impact and pressure seat 2. After the pump is turned on and the pressure is held, a pressure difference is formed between the inside and outside of the pipe string under the sealing effect of the ball catching tube 7 and the perforated sleeve 4, thereby realizing the hanging of the tail pipe hanger. Continuing to hold the pressure can shear off the first fixing part 10, so that the ball catching tube 7 moves downward and compresses the elastic member 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 upper and lower pressure difference formed by the continuous holding pressure (the pressure difference between the pressure of 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 downward together, wherein, during the downward process of the perforated sleeve 4, its side wall can push the stopper 9 to move radially inward to shear off the third fixing part 12; after the perforated sleeve 4 moves downward to the position, it stops after limiting, and the stopper 9 moves radially inward to the position (the position where it can contact the ball 6 after the ball 6 moves upward), and is limited by the side surface of the perforated sleeve 4 and the impact and pressure seat 2.

[0033] like Figure 3As shown, after the pump is stopped and the pressure is released, since there is no pressure difference between the top of the ball 6 and the bottom of the ball catching tube 7 and the elastic member 8 is in a compressed state, the ball catching tube 7 and the ball 6 can move upward under the rebound force of the elastic member 8, so that the side wall of the ball catching tube 7 can contact and seal with the inner wall of the channel P, and the ball 6 contacts and is limited by the lower surface of the stopper 9, so that the ball 6 and the ball catching tube 7 always maintain a contact and sealing state to form a self-locking, so that when the floating collar and the floating shoe fail and the slurry replacement plug does not collide and press, the cement slurry can be prevented from returning, the ball seat can be self-locking and sealed, and the unstable pressure in the well due to the reduction of the annular liquid column can be avoided, the cementing quality can be improved and the safety risk can be reduced. And because the float hoop and float shoe fail, 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 member to the lower end of the ball catch tube and the ball, is greater than the pressure on the upper end of the ball catch tube and the ball. Under the action of the pressure difference, the sealing between the ball catch tube and the impact seat, and between the ball and the block is further increased.

[0034] like Figure 3 , Figure 4 As shown, in one or more embodiments, a plurality of circulation holes 16 are opened on the side of the perforated sleeve 4, one side of which is connected to the space below the well, and the side surface of the impact and pressure seat 2 can block the other side of the circulation hole 16. After the perforated sleeve 4 descends into place, the other side of the circulation hole 16 is separated from the impact and pressure seat 2 and exposed, so as to be connected with the internal channel P of the impact and pressure seat, thereby preventing the ball 6 of the self-locking valve from falling after being blocked, and always keeping the ball 6 in contact and sealing with the upper part of the ball catching tube 7, so as to form a self-locking valve.

[0035] like Figure 4 , Figure 5 As shown, in one or more embodiments, the perforated sleeve 4 stops after being moved downward to the right position. Specifically, the matching inner wall of the perforated sleeve 4 contacts the matching outer wall of the impact seat 2, and the matching outer wall blocks the circulation hole 16. A retaining spring groove 17 is provided on the matching inner wall, and a limiting retaining spring 11 is provided in the retaining spring groove 17. A limiting groove 15 is provided on the matching outer wall. During the downward movement of the perforated sleeve 4, the limiting retaining spring 11 can cooperate with the limiting groove 15 to limit the perforated sleeve 4 and prevent the perforated sleeve 4 from continuing to move downward.

[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 in 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 portion of the support seat 5, and the perforated sleeve 4 can move downward in the notch 51. A first vertical groove 21 is provided at the lower end of the ball catching tube 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 connected to the first vertical groove 21 and the second vertical groove 20, respectively.

[0037] In one or more embodiments, the space below the well is located below the support seat 5, and a circulation space connected to the circulation hole 16 is formed between the side surface of the perforated sleeve 4, the inner wall of the shell 1, and the upper surface of the outer side of the recess 51. A plurality of through holes 19 are opened along the axial direction on the outer side of the recess 51, and the circulation space is connected to the space below the well through the through holes 19.

[0038] In one or more embodiments, the mating outer wall has a plurality of block grooves 14 connected to the channel P evenly distributed radially inward on the outer circumferential surface, the block grooves 14 are close to the bottom of the channel P and the limiting grooves 15 are located above the block grooves 14, and each block 9 is accommodated in the block groove 14.

[0039] like Figure 1 , Figure 2 , Figure 4 and Figure 8 As shown, in one or more embodiments, the matching inner wall is provided with an inclined groove 18 at a position opposite to the block groove 14, and the inclined groove 18 contacts the side of the block 9 away from the passage P. During the downward movement of the perforated sleeve 4, the inclined groove 18 can gradually push the block 9 to extend radially inward through its inclined surface. A limiting protrusion is provided on the upper surface of the block 9, and a convex portion capable of cooperating with the limiting protrusion is provided inside the block groove 14. After the perforated sleeve 4 stops after limiting, the matching inner wall is pressed against the side of the block 9 away from the passage P, and the convex portion of the block groove 14 cooperates with the limiting protrusion to limit the block 9.

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

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

[0042] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present 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: A perforated sleeve, a ball catching tube, a pressure seat and a stopper arranged between the perforated sleeve and the pressure seat, all of which are arranged in the shell; the ball catching tube is arranged inside the perforated sleeve and connected to the perforated sleeve via a first fixing part; the perforated sleeve is connected to the shell via a second fixing part; an elastic member is connected to the lower part of the ball catching tube; the stopper is connected to the pressure seat via a third fixing part, and the stopper contacts the side wall of the perforated sleeve; the pressure seat has a passage extending from the pressure seat to the top of the ball catching tube; After the ball is thrown and the pressure is accumulated, the first fixing part is sheared off, so that the ball catching tube moves downward and compresses the elastic part until the lower end of the ball catching tube contacts the inner step of the perforated sleeve; under the action of the pressure difference, the second fixing part is sheared off, so that the perforated sleeve moves downward and pushes the stopper to move radially inward, and the stopper shears off the third fixing part and moves radially inward into position; after the pump is stopped and the pressure is released, 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 by the lower surface of the stopper.

2. The self-locking ball seat according to claim 1, characterized in that: A circulation hole is opened on the side of the opening sleeve, one side of which is connected to the space below the well. The side surface of the impact and pressure seat can block the other side of the circulation hole. After the opening sleeve descends into place, the other side of the circulation hole is separated from the impact and pressure seat and exposed so as to be connected to the channel.

3. The self-locking ball seat according to claim 2, characterized in that: The perforated sleeve is stopped after being moved downward to a certain position.

4. The self-locking ball seat according to claim 3, characterized in that: The cooperating inner wall of the hole-opening sleeve contacts the cooperating outer wall of the impact and pressure seat, and the cooperating outer wall blocks the circulation hole. The cooperating inner wall is provided with a retaining spring groove, and a limiting retaining spring is provided in the retaining spring groove. The cooperating outer wall is provided with a limiting groove. During the downward movement of the hole-opening sleeve, the limiting retaining spring cooperates with the limiting groove to limit the hole-opening sleeve.

5. The self-locking ball seat according to claim 2, characterized in that: It also includes a support seat arranged in the shell, the upper part of the support seat is provided with a recess, the open hole sleeve can move downward in the recess, the lower end of the ball catching tube is provided with a first vertical groove, the bottom of the recess is provided with a second vertical groove, and the two ends of the elastic member are respectively connected to the first vertical groove and the second vertical groove.

6. The self-locking ball seat according to claim 5, characterized in that: The space below the well is located below the support seat, and a circulation space connected to the circulation hole is formed between the side surface of the opening sleeve, the inner wall of the shell and the outer side of the recess. A through hole is opened on the outer side of the recess, and the circulation space is connected to the space below the well through the through hole.

7. The self-locking ball seat according to claim 4, characterized in that: The matching outer wall has a plurality of block grooves uniformly distributed radially inwardly on the outer circumferential surface thereof and communicating with the channel, and each of the blocks is accommodated in the block groove.

8. The self-locking ball seat according to claim 7, characterized in that: The matching inner wall is provided with an oblique groove at a position opposite to the stopper groove, and the oblique groove contacts a side of the stopper away from the channel. During the downward movement of the opening sleeve, the oblique groove can push the stopper to extend radially inward.

9. The self-locking ball seat according to claim 8, characterized in that: The three-stage shear nail is arranged on a side of the stopper groove close to the channel and extends axially to prevent the stopper from moving radially inward.

10. The self-locking ball seat according to claim 7, characterized in that: A limiting protrusion is provided on the upper surface of the block, and a convex portion capable of cooperating with the limiting protrusion is provided inside the block groove. After the opening sleeve is stopped by limiting, the cooperating inner wall is pressed and contacted with the side of the block away from the channel and the convex portion of the block groove cooperates with the limiting protrusion to limit the block.

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