Pressure relief device for hanger tailpipe

Abstract

The application provides a pressure relief device for liner hanger, which comprises a ball seat shell, a pressure receiving seat arranged in the ball seat shell, a ball seat mechanism arranged on the pressure receiving seat and capable of being connected with a pressure holding ball, wherein after the pressure holding ball is put in, the pressure holding ball falls on the ball seat mechanism to hold pressure above, the liner hanger is hung, and then the pressure holding is continued to open the pressure holding environment in the pipe for circulating well cementation operation. The liner hanger can be hung by putting the ball in the liner to hold pressure, the pressure in the pipe is slowly released through the pressure relief mechanism by continuing to hold pressure, and besides, the conventional liner string structure is not changed, the installation is simple and convenient, and the sealing is reliable.

Description

Technical Field

[0001] This invention relates to a pressure relief and pressure-reducing device for tailpipe suspension, belonging to the field of oil well cementing. Background Technology

[0002] Tail-end suspension cementing is a commonly used cementing process in petroleum engineering. It involves connecting the drill pipe to a tail-end suspension device, lowering the tail-end into the well, and then suspending and cementing the tail-end. The conventional tail-end cementing string structure, from top to bottom, is: "cement head + drill pipe string + tail-end suspension device + tail-end string + ball seat + casing + float collar + casing + float shoe". One of the key aspects of tail-end suspension cementing is the tail-end suspension itself. Conventional tail-end suspension devices are hydraulically activated suspension mechanisms. This involves dropping a ball into the ball seat inside the pipe, creating internal pressure, activating the suspension mechanism, and then continuing to create pressure until the ball seat pressure device is broken, creating a circulation channel for tail-end cementing. Because the tail-end suspension pressure and the ball seat pressure need to be designed with a pressure difference, and to prevent premature activation of the suspension mechanism due to hydraulic turbulence during tail-end lowering, the tail-end suspension pressure is typically designed to be 9-10 MPa, and the ball seat pressure to be 17-19 MPa.

[0003] In practical application, the instantaneous release of pressure during ball-end cementing creates instantaneous pressure at the bottom of the well. In wells with easily leaky formations, this can easily cause formation leakage, leading to drilling fluid loss and making tailpipe cementing impossible. This necessitates circulation plugging or pulling out the tailpipe string for re-plugging, significantly increasing operational risks and economic costs. Therefore, there is an urgent need to improve the tailpipe suspension cementing pressure-relief system to reduce formation leakage caused by instantaneous pressure release. This invention relates to a pressure-relieving device for tailpipe suspension. After the tailpipe suspension is completed, the high pressure inside the pipe is slowly released through the pressure-relieving device, effectively avoiding the impact of instantaneous high pressure release on the formation. This is of great significance for the implementation of tailpipe cementing technology in oil and gas exploration and development. Summary of the Invention

[0004] To address the aforementioned technical problems in the existing technology, this invention proposes a pressure relief and pressure-suppressing device for tailpipe suspension. In the tailpipe suspension cementing process, the pressure relief and pressure-suppressing device connected to the tailpipe string can achieve tailpipe suspension by dropping a ball to suppress pressure. Continued pressure suppression is achieved by slowly releasing the high pressure inside the pipe through a pressure relief mechanism. Furthermore, it does not change the conventional tailpipe string structure, is easy to install, and has reliable sealing.

[0005] This invention proposes a pressure relief and depressurization device for tailpipe suspension, comprising:

[0006] A ball seat housing, wherein a pressing seat is provided inside the ball seat housing;

[0007] A ball seat mechanism is provided on the pressing seat, and the ball seat mechanism can be connected to the pressing ball;

[0008] In this process, after the pressure-retaining ball is inserted, it falls onto the ball seat mechanism to create pressure above, allowing the pressure-retaining hanger to be seated. Then, pressure is maintained to open up the pressure environment inside the pipe and carry out circulating cementing operations.

[0009] A further improvement of the present invention is that the ball seat mechanism includes an upper ball seat core and a lower ball seat core, and a sealing surface is provided in the middle of the upper ball seat core. After the pressure ball falls into the sealing surface, it causes pressure above.

[0010] A further improvement of the present invention is that the upper core of the ball seat is connected to the pressing seat by a shear pin. When the pressure-holding suspension is engaged, the pressure continues to break the shear pin, and the upper core of the ball seat and the pressure-holding ball move into the lower core of the ball seat under the action of pressure.

[0011] A further improvement of the present invention is that a plurality of circulating side holes are provided on the lower side wall of the ball seat lower core, and the circulating side holes are uniformly arranged along the circumference of the ball seat lower core.

[0012] A further improvement of the present invention is that the lower core of the ball seat is sleeved on the lower part of the pressing seat and connected by a slider;

[0013] The ball seat lower core is provided with a first slider groove, the lower part of the pressing seat is provided with a trapezoidal groove, the slider passes through the first slider groove and its outer end is inserted into the trapezoidal groove, and the inner end of the slider is blocked by the outer wall of the ball seat upper core.

[0014] A further improvement of the present invention is that a pressure relief cavity is provided on the outer wall of the lower part of the ball seat core, and the thickness of the pressure relief cavity matches the thickness of the ball seat core.

[0015] A further improvement of the present invention is that the core of the ball seat is provided with a pressure relief hole that connects the inner side and the pressure relief cavity.

[0016] A further improvement of the present invention is that a second slider groove is provided on the upper part of the pressure relief cavity side of the ball seat upper core. After the ball seat upper core moves downward into the ball seat lower core, the second slider groove is opposite to the first slider groove, and the slider slides into the second slider groove.

[0017] A further improvement of the present invention is that the mating surfaces of the pressing seat, the upper core of the ball seat, and the lower core of the ball seat are all provided with slidable sealing rings.

[0018] A further improvement of the present invention is that the outer periphery of the impact seat is provided with threads that connect to the ball seat housing, and the upper end of the impact seat is provided with an impact ring for cementing impact and receiving the cementing plug.

[0019] Compared with the prior art, the advantages of the present invention are as follows:

[0020] The pressure relief and pressure-suppressing device for tailpipe suspension described in this invention enables tailpipe suspension in the tailpipe suspension cementing process by connecting the device to the tailpipe string and using ball-dropping pressure-suppressing to continue pressure suppression. The high pressure inside the pipe is slowly released through the pressure relief mechanism. Furthermore, it does not change the conventional tailpipe string structure, is easy to install, and has reliable sealing.

[0021] The pressure relief device for tailpipe suspension described in this invention uses a compression relief chamber and micro-relief holes to slowly release high pressure inside the pipe. Its simple mechanical structure effectively prevents instantaneous release of high pressure from leaking into the formation. The ball seat mechanism consists of an upper ball seat core and a lower ball seat core. The upper ball seat core receives the pressure-relief ball and is connected by a shear pin; the lower ball seat core forms the pressure relief chamber and is connected by a slider. This structural design creates the pressure relief space and time for the upper ball seat and lower ball seat core to fall.

[0022] The pressure relief and depressurization device for tailpipe suspension described in this invention allows the ball seat core to fall after depressurization is completed, without affecting circulation or tailpipe cementing operations. The pressure relief and depressurization device has a simple structure, is safe and reliable, and offers advantages such as convenient operation and low risk during construction; it ensures the smooth progress of the tailpipe suspension depressurization and depressurization process, and its operational reliability and safety are high. Attached Figure Description

[0023] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, in which:

[0024] Figure 1 The diagram shown is a structural schematic of a pressure relief device for tailpipe suspension according to an embodiment of the present invention, showing the initial state;

[0025] Figure 2 The diagram shown is a structural schematic of a pressure relief and pressure-suppressing device for tailpipe suspension according to an embodiment of the present invention, showing the state of the pressure-suppressing ball after it falls into the ball seat mechanism;

[0026] Figure 3 The diagram shown is a structural schematic of a pressure relief device for tailpipe suspension according to an embodiment of the present invention, illustrating the state after the pressure buildup environment inside the pipe is cleared.

[0027] In the accompanying drawings, the same parts use the same reference numerals. The drawings are not drawn to scale.

[0028] The meanings of the reference numerals in the attached figures are as follows:

[0029] 1. Ball seat housing; 2. Upper ball seat core; 3. Lower ball seat core; 4. Pressure-reducing ball; 11. Pressing seat; 12. Shear pin; 13. Trapezoidal groove; 14. Sealing ring; 21. Sealing surface; 22. Pressure relief chamber; 23. Pressure relief hole; 24. Second slider groove; 31. Circulation side hole; 32. First slider groove; 33. Slider. Detailed Implementation

[0030] To make the technical solutions and advantages of the present invention clearer, exemplary embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not an exhaustive list of all embodiments. Furthermore, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0031] Figure 1 The illustration schematically shows a pressure relief device for tailpipe suspension according to an embodiment of the present invention, comprising a ball seat housing 1, which is a cylindrical structure, with its upper and lower ends connected to a sleeve via threads, the inner diameter of which is the same as the inner diameter of the sleeve. A pressure-bearing seat 11 is disposed inside the ball seat housing 1, the pressure-bearing seat 11 being a cylindrical structure, its outer wall being threaded and connected to the ball seat housing 1.

[0032] A ball seat mechanism is provided on the pressure seat 11. The ball seat mechanism can be connected to the pressure-holding ball 4. After the pressure-holding ball 4 is put in, the pressure-holding ball 4 falls into the ball seat mechanism to hold the pressure above, and the pressure-holding hanger is hung. Then the pressure-holding continues to open up the pressure-holding environment in the pipe and carry out the circulating cementing operation.

[0033] In one embodiment, the ball seat mechanism includes an upper ball seat core 2 and a lower ball seat core 3. The upper ball seat core 2 and the lower ball seat core 3 are both cylindrical structures. The upper ball seat core 2 is located in the upper part of the pressing seat 11, and the lower ball seat core 3 is located in the lower part of the pressing seat 11. Initially, both the upper ball seat core 2 and the lower ball seat core 3 are connected to the pressing seat 11, and the upper ball seat core 2 and the lower ball seat core 3 are sleeved together. A sealing surface 21 is provided in the middle of the upper ball seat core 2. After the pressure ball 4 falls onto the sealing surface 21, it causes pressure on the upper part.

[0034] In a preferred embodiment, the upper core 2 of the ball seat is connected to the pressing seat 11 by a shear pin 12. When the pressure-holding suspension is seated, the pressure continues to hold the ball seat, causing the shear pin 12 to break. Under the action of pressure, the upper core 2 of the ball seat and the pressure-holding ball 4 move into the lower core 3 of the ball seat.

[0035] When using the pressure relief and pressure-reducing device for tailpipe suspension according to this embodiment, after the pressure-reducing ball 4 is inserted, the pressure-reducing ball 4 falls onto the sealing surface 21 of the upper core 2 of the ball seat, and pressure begins to build up from above. When the pressure reaches a certain value, the pressure-reducing hanger is seated, and then pressure continues to build up. After reaching a certain value, the shear pin 12 is sheared, and the upper core 2 of the ball seat falls into the lower core 3 of the ball seat. Then the lower core 3 of the ball seat separates from the pressure-bearing seat 11, thereby causing the entire ball seat mechanism to move downward and detach from the pressure-bearing seat 11, opening up the pressure-reducing environment inside the pipe, so that circulating cementing operations can be performed.

[0036] In one embodiment, a plurality of circulation side holes 31 are provided on the lower side wall of the lower core 3 of the ball seat, and the circulation side holes 31 are evenly arranged along the circumference of the lower core 3 of the ball seat. This ensures that the upper core, lower core, and pressure ball 4 can circulate through the circulation side holes 31 after falling, keeping the inside of the sleeve unobstructed.

[0037] In one embodiment, the lower core 3 of the ball seat is sleeved on the lower part of the pressing seat 11, and the outer diameter of the lower core 3 matches the inner diameter of the pressing seat 11. The two are connected by a slider 33. The lower core 3 of the ball seat has a first slider groove 32, which is radially arranged and is a through groove. The lower part of the pressing seat 11 has a trapezoidal groove 13. The slider 33 passes through the first slider groove 32 and its outer end is inserted into the trapezoidal groove 13. The inner end of the slider 33 is blocked by the outer wall of the upper core 2 of the ball seat.

[0038] In the tailpipe suspension pressure relief device according to this embodiment, the slider 33 passes through the first slider groove 32 and extends into the trapezoidal groove 13. Its other end is blocked by the outer wall of the upper core 2 of the ball seat. Thus, under the action of the slider 33, the lower core 3 of the ball seat and the pressing seat 11 are connected. The trapezoidal groove 13 has a trapezoidal cross-section. The hypotenuse of the trapezoid provides an inward force to the slider 33, giving it an inward tendency. When the obstruction of the outer wall of the upper core 2 of the ball seat is released, the slider 33 moves inward, thereby sliding out of the trapezoidal groove 13, separating the lower core 3 of the ball seat and the pressing seat 11.

[0039] In one embodiment, a circumferential groove is provided on the lower outer wall of the upper core 2 of the ball seat, forming an annular space between the groove and the pressing seat 11, serving as a pressure relief cavity 22. The thickness of the pressure relief cavity 22 matches the thickness of the lower core 3 of the ball seat. During the downward movement of the upper core 2, the lower core 3 moves upward relative to the upper core 2, thereby extending into the pressure relief cavity 22. The pressure relief cavity 22 can accommodate the lower core 3, allowing it to move smoothly.

[0040] Preferably, the upper core 2 of the ball seat is provided with a pressure relief hole 23 that connects the inner side of the ball seat to the pressure relief chamber 22. The pressure relief hole 23 is a small hole, and the flow rate of the liquid inside it is very small. As the lower core 3 of the ball seat moves downward, the pressure in the pressure relief chamber 22 is slowly released through the pressure relief hole 23, thereby achieving the effect of pressure relief.

[0041] In one embodiment, a second slider groove 24 is provided on the upper part of one side of the pressure relief chamber 22 of the ball seat upper core 2. After the ball seat upper core 2 moves downward into the ball seat lower core 3, the second slider groove 24 is opposite to the first slider groove 32, and the slider 33 slides into the second slider groove 24.

[0042] When the slider 33 slides into the second slider groove 24, the other end slides out from the trapezoidal groove 13. The lower core 3 of the ball seat loses the support of the slider 33 from the pressure seat 11, thus separating from the pressure seat 11. Under the action of pressure, it slides down, thereby opening up the pressure environment inside the pipe, and then carrying out the circulating cementing operation.

[0043] In one embodiment, the mating surfaces of the pressing seat 11, the upper core of the ball seat, and the lower core of the ball seat are all provided with slidable sealing rings 14 to maintain a seal during sliding.

[0044] In one embodiment, the outer periphery of the pressing seat 11 is provided with threads that connect to the ball seat housing 1, and the upper end of the pressing seat 11 is provided with a pressing ring for cementing pressing and receiving the cementing plug.

[0045] In the cementing process, the pressure relief and pressure suffocation device for tailpipe suspension as described in this embodiment is designed to be located at the lower part of the tailpipe string, above the float collar, at the position of one casing.

[0046] After the tailpipe string is lowered to the predetermined well depth, drilling fluid is circulated and flushed. At this time, the pressure relief device is open, and the drilling fluid circulation process will not affect the stress on the components of the device. Moreover, the pressure relief chamber 22 is filled with drilling fluid by itself during the tailpipe lowering process.

[0047] A pressure-reducing ball 4 is inserted into the tubing. Once the ball 4 falls to the sealing surface 21 on the upper part of the core of the ball seat in the pressure-relieving pressure-reducing device, a pressure-reducing environment is formed inside the tubing. This allows for pressure-reducing operations. Generally, the pressure is increased by 1-2 MPa on top of the tailpipe hanger mounting pressure before the tailpipe hanger mounting operation is performed.

[0048] After the pressure-holding hanger is installed, pressure holding continues until the pressure suddenly drops slowly. The pump is then immediately stopped. Once the pressure slowly drops to 0 MPa, a small-displacement pump can be started for circulation to begin the next step of tailpipe cementing. The purpose is to open up the pressure-holding environment inside the pipe and facilitate circulation cementing. During this process, after the pressure reaches the design value of the shear pin 12, the shear pin shears against the ball seat upper core and the pressure-bearing seat 11 through relative sliding. The downward movement of the ball seat upper core causes the pressure relief chamber 22 to compress. The ball seat upper core 2, ball seat lower core 3, and pressure-bearing seat 11 all involve the sealing ring 14 fitting clearance. As the ball seat upper core slides down under the high pressure inside the pipe, the liquid in the pressure relief chamber 22 is discharged through the pressure relief hole 23 designed on the ball seat upper core to the lower part where the ball seat upper core and the pressure-holding ball 4 are sealed together. This process is the pressure relief process. When the upper core 2 of the ball seat slides down to the position of the lower core 3 of the ball seat, the slider 33 slides into the second slider groove 24 designed on the upper core 2 of the ball seat when the upper core 2 of the ball seat presses down on the top of the lower core 3 of the ball seat. The other end of the slider 33 disengages from the trapezoidal groove 13 designed on the inner wall of the pressing seat 11, so that the lower core 3 of the ball seat disengages from the pressing seat 11. At this time, the upper core 2 of the ball seat, the lower core 3 of the ball seat, and the slider 33 fall together, realizing the internal penetration of the casing and enabling circulating cementing operations.

[0049] In this invention, "above" refers to the direction closer to the wellhead, and "below" refers to the direction farther from the wellhead.

[0050] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and / or modifications falling within the scope of the invention, and all changes and / or modifications made according to embodiments of the invention should be covered within the protection scope of the invention.

Claims

1. A pressure relief and depressurization device for tailpipe suspension, characterized in that, include: Ball seat housing (1), and a pressing seat (11) is provided inside the ball seat housing (1); A ball seat mechanism is provided on the pressing seat (11), and the ball seat mechanism can be connected to the pressing ball (4); Among them, after the pressure-retaining ball (4) is put in, the pressure-retaining ball (4) falls onto the ball seat mechanism to make the upper part pressure-retaining, and the pressure-retaining hanger is hung. Then the pressure-retaining continues to open up the pressure-retaining environment in the pipe and carry out the circulating cementing operation. The ball seat mechanism includes an upper ball seat core (2) and a lower ball seat core (3). A sealing surface (21) is provided in the middle of the upper ball seat core (2). After the pressure ball (4) falls onto the sealing surface (21), it causes pressure above. A pressure relief cavity (22) is provided on the outer wall of the lower part of the upper core (2) of the ball seat, and the thickness of the pressure relief cavity (22) matches the thickness of the lower core (3) of the ball seat. The lower core (3) of the ball seat is sleeved on the lower part of the pressing seat (11) and connected by a slider (33); The ball seat lower core (3) is provided with a first slider groove (32), the lower part of the pressing seat (11) is provided with a trapezoidal groove (13), the slider (33) passes through the first slider groove (32) and its outer end is inserted into the trapezoidal groove (13), and the inner end of the slider (33) is blocked by the outer wall of the ball seat upper core (2); The ball seat core (2) is provided with a pressure relief hole (23) that connects the inner side and the pressure relief chamber (22). A second slider groove (24) is provided on the upper part of the pressure relief chamber (22) side of the upper core (2) of the ball seat. After the upper core (2) of the ball seat moves downward into the lower core (3) of the ball seat, the second slider groove (24) is opposite to the first slider groove (32), and the slider (33) slides into the second slider groove (24).

2. The pressure relief and depressurization device for tailpipe suspension according to claim 1, characterized in that, The upper core (2) of the ball seat is connected to the pressing seat (11) by a shear pin (12). When the pressure-holding hanger is seated and pressure continues to be applied, the shear pin (12) breaks. Under the action of pressure, the upper core (2) of the ball seat and the pressure-holding ball (4) move into the lower core (3) of the ball seat.

3. The pressure relief and depressurization device for tailpipe suspension according to claim 2, characterized in that, A plurality of circulating side holes (31) are provided on the lower side wall of the ball seat lower core (3), and the circulating side holes (31) are evenly arranged along the circumference of the ball seat lower core (3).

4. The pressure relief and depressurization device for tailpipe suspension according to any one of claims 1 to 3, characterized in that, The mating surfaces of the pressing seat (11), the upper core of the ball seat (2), and the lower core of the ball seat (3) are all provided with slidable sealing rings (14).

5. The pressure relief and depressurization device for tailpipe suspension according to claim 4, characterized in that, The outer periphery of the impact seat (11) is provided with threads that connect to the ball seat housing (1), and the upper end of the impact seat (11) is provided with an impact ring for cementing impact to support the cementing plug.

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