Fracturing ball seat

Abstract

The invention relates to the technical field of fracturing construction, in particular to a fracturing ball seat. Comprising a valve body, a shear pin seat mounted in the valve body and in threaded connection with the valve body, a nozzle arranged in a side wall runner of the valve body, a standby cap I in threaded connection with the side wall runner of the valve body and used for fixing the nozzle, a ball seat arranged on the inner side of the shear pin seat, a standby cap II in threaded connection with the lower part of the valve body, and a steel ball arranged on a sealing surface in the ball seat, the ball seat is connected with the shear pin seat through the shear pin body, and the seal ring is arranged in a seal groove in the outer cylindrical surface of the shear pin seat; the high unification of multiple functions of pressure building, throttling, erosion resistance and the like is achieved, it is ensured that a compression type packer above the device is fully set, meanwhile, the device can be used for detecting the sealing performance of an oil pipe, after a shear pin is sheared off, a ball seat falls onto a second standby cap on the lower portion and is reliably borne, and the risk that the ball seat and a steel ball fall into a well is effectively prevented; after the ball seat falls off, an overflowing channel is formed, and a reliable pressure source is provided.

Description

Technical Field

[0001] This invention relates to the field of fracturing construction technology, and in particular to a fracturing ball seat. Background Technology

[0002] In oilfield fracturing, layer inspection, and perforation repair operations, multiple fracturing ball seats are often connected in series on the tubing string to enable multi-stage fracturing in a single run. These ball seats, equipped with fracturing balls of different sizes, facilitate a top-down, step-by-step start-up process. During this process, the fracturing ball seat must simultaneously perform several critical functions: reliably pressurize after ball deployment to ensure a secure setting of the compression packer connected above; after the ball seat shears off, it must open the flow channel for fracturing and provide the necessary stable differential pressure for setting the expansion packer connected above through a throttling effect; simultaneously, because fracturing fluid typically contains high-concentration, high-hardness proppant (fracturing sand), the fracturing ball seat and its flow channel must possess excellent resistance to erosion and wear to ensure the reliability and service life of the tool during prolonged proppant loading operations.

[0003] However, existing fracturing ball seats often have significant shortcomings in terms of functional integration and durability. Conventional slip-out ball seats have a simple structure; after the ball is dropped and pressurized, the ball detaches. However, the flow channels after detachment are often straight-through or open, which not only fails to create a stable throttling pressure differential, leading to insufficient or failed setting of the expansion packer, but also lacks wear-resistant protection on the inner wall of the channel. Under the continuous erosion of high-speed sand-carrying fluid, wear is easily caused, affecting tool performance or even causing tool failure and leading to complex downhole situations. Another type of fracturing ball seat with some throttling function usually has a simple design for its core throttling element (such as the nozzle), which does not fully consider the erosive characteristics of high-pressure sand-carrying fluid and has insufficient wear resistance. At the same time, its internal pressurization and detachment structure has reliability risks, or after the ball detaches, the ball body and steel ball may lose restraint, posing a risk of falling into the well and affecting the safety of subsequent operations. The existing design scheme cannot meet the three core requirements of "reliable pressure control", "stable flow control" and "long-term erosion resistance". Its design logic of "single function, simple structure and poor durability" directly conflicts with the current technical requirements of fracturing technology to develop "high sand ratio, long cycle and multiple sections in one tubing run", which restricts the efficiency, success rate and economic benefits of operation.

[0004] Therefore, in view of the problems mentioned above, the existing fracturing ball seats have a single function and cannot simultaneously achieve reliable pressure holding, stable throttling and long-term erosion resistance. They have unreliable pressure holding, unstable throttling pressure differential, are easily damaged by fracturing sand, and have the risk of falling into the well after the ball seat falls off. A fracturing ball seat can be designed that can achieve reliable pressure holding after the ball is deployed to ensure packer setting, and can form a throttling channel with good wear resistance after the ball seat falls off. Summary of the Invention

[0005] In order to overcome the problems of existing fracturing ball seats having a single function and being unable to simultaneously achieve reliable pressure holding, stable throttling and long-term erosion resistance, there are issues such as unreliable pressure holding, unstable throttling pressure differential, susceptibility to erosion damage by fracturing sand, and the risk of the ball seat falling into the well after falling off.

[0006] The technical solution of the present invention is as follows: a fracturing ball seat, comprising a valve body, a shear pin seat installed inside the valve body and threadedly connected thereto, a nozzle disposed in a flow channel on the side wall of the valve body, a spare cap I threadedly connected to the flow channel on the side wall of the valve body for fixing the nozzle, a ball seat disposed inside the shear pin seat, a spare cap II threadedly connected to the lower part of the valve body, and a steel ball disposed on the inner sealing surface of the ball seat; it also includes a shear pin body and a sealing ring, the ball seat being connected to the shear pin seat through the shear pin body, and a sealing ring being disposed in the sealing groove on the outer cylindrical surface of the shear pin seat.

[0007] Preferably, the tool is lowered into the well to a predetermined position along with the tubing string. At this point, the ball seat is fixed inside the shear pin body, blocking the lateral nozzle. A steel ball of a specified size is dropped into the tubing from the wellhead. A small-displacement pump delivers the steel ball to the tool's position, where it sits on the sealing surface of the ball seat. Increasing the pump pressure creates a downward force on the steel ball and ball seat. Because there is a sealing ring between the shear pin body and the valve body, and the ball seat blocks the nozzle, the pressure is trapped above the tool. The tubing seal can be judged by observing whether the casing pressure rises synchronously with the tubing pressure. When the oil pressure continues to rise to the setting pressure required by the compression packer, the pressure is stabilized for a period to allow the compression packer sleeve to fully expand and set against the inner wall of the casing. The pump pressure continues to increase. When the pressure reaches the preset shear pressure of the shear pin body, the shear pin body is sheared. After the shear pin body fails, the ball seat, along with the steel ball on it, moves downward under hydraulic pressure. After detaching from the shear pin seat, the detached ball seat and steel ball fall and are reliably received and blocked by the spare cap connected at the lower end, preventing them from falling to the bottom of the well, thus acting as a "plug". After the ball seat moves down, the side nozzle that was previously blocked is completely exposed and connected to the valve body, forming a new, mainstream fracturing fluid flow channel, and formal fracturing operations begin. When the high-pressure sand-carrying fluid flows through the valve body, some of the fluid flows to the annulus through the throttling orifice of the nozzle. Since the size of the throttling orifice is much smaller than that of the upstream flow channel, a significant throttling effect is generated when the fluid flows through it, forming a stable pressure difference (P1>P2) before and after the nozzle. This pressure difference acts on the expansion packer above the tool, causing it to set. At the same time, most of the high-pressure fluid continues to flow down through the valve body to fracture the target formation. The nozzle is made of wear-resistant material, which can effectively resist the erosion of high-speed sand particles, ensuring the stability of the throttling pressure difference and the durability of the tool during long-term sand fracturing.

[0008] Preferably, the valve body is a hollow cylindrical shape with a through central flow channel. The upper outer side is provided with a threaded structure for connecting the pipe column, and the lower outer side is provided with a threaded structure for connecting the spare cap.

[0009] Preferably, the valve body sidewall has one or more lateral through holes communicating with the central flow channel, the nozzle is disposed in the lateral through hole, the inner wall of the lateral through hole is provided with threads, and is threadedly connected to the spare cap.

[0010] Preferably, the inner wall of the clipper seat is provided with a support shoulder that fits against the ball seat. The support shoulder is an annular bearing surface used to bear the downward pressure transmitted between the steel ball and the ball seat before the ball seat is knocked off.

[0011] Preferably, the outer cylindrical surface of the shear pin seat is provided with external threads, which are engaged and fixed with the threaded section of the valve body cavity. The shear pin seat and the ball seat sidewall are provided with at least one radial mounting hole for installing the shear pin body. The shear pin body is a standard cylindrical pin type shear screw, and its shank diameter is designed according to the required shearing pressure. The ball seat sidewall is provided with a corresponding limiting groove or through hole for the shear pin body to be inserted.

[0012] Preferably, the nozzle is a hollow tubular or perforated plate-shaped part made of wear-resistant material, with a throttling orifice in the center, and a cap in the shape of a cover or nut with a through hole in the center.

[0013] Preferably, the outer cylindrical surface of the shear pin holder is provided with at least one sealing groove, and the sealing ring is an O-ring or a rectangular sealing ring, made of fluororubber or hydrogenated nitrile rubber.

[0014] Preferably, a cushioning pad is also included, which is located at the lower end of the ball seat. The cushioning pad is a disc-shaped or annular elastomer with a through hole in the center. The cushioning pad is made of polyurethane or rubber material.

[0015] The beneficial effects of this invention are as follows: Through integrated structural design, multiple functions such as pressure build-up, throttling, and erosion resistance are successfully unified in a single tool. First, the structure of fixing the ball seat with shear pins achieves precise pressure build-up control and reliable setting. After the ball is dropped, pressure can be stably built up to ensure that the compression packer above it is fully set. It can also be used to check the tubing sealing performance. Second, after the shear pins are sheared at the set pressure, the ball seat falls off to the lower spare cap and is reliably received, effectively preventing the risk of the ball seat and steel ball falling into the well. After the ball seat falls off, the special nozzle set on the side wall is exposed to form a flow channel. This nozzle is specially designed to generate a stable and controllable throttling pressure differential, which is conducive to expanding the flow channel. The setting seal of the tension packer provides a reliable pressure source. Most importantly, the nozzle is made of high-strength wear-resistant material, and its flow channel structure is optimized for sand-carrying fluids, possessing excellent erosion resistance. It can withstand the scouring of long-term, high-sand-ratio fracturing operations, greatly extending the tool's service life and reliability. In addition, the sealing ring between the shear pin seat and the valve body ensures the sealing during the pressure build-up stage, and the buffer pad at the lower end of the ball seat can absorb the impact when the ball seat falls off, protecting the lower structure. This invention has a compact structure and complete functions, solving the problems of functional fragmentation and insufficient durability in the prior art, and meeting the stringent requirements of high performance and high reliability for tools in a multi-stage fracturing process of a single tubing string. Attached Figure Description

[0016] Figure 1 The diagram shown is a three-dimensional cross-sectional view of Embodiment 1 of the fracturing ball seat of the present invention; Figure 2 The diagram shown is a three-dimensional structural schematic of embodiment 1 of the fracturing ball seat of the present invention; Figure 3 The diagram shown is a partially enlarged structural diagram of the support shoulder in Embodiment 1 of the fracturing ball seat of the present invention; Figure 4 The diagram shown is a three-dimensional split structure of the shear pin seat and the spare cap in the fracturing ball seat trimming assembly of the present invention; Figure 5 The diagram shown is a three-dimensional cross-sectional view of Embodiment 2 of the fracturing ball seat of the present invention; Figure 6 The diagram shown is a partially enlarged schematic of the buffer pad structure in Embodiment 2 of the fracturing ball seat of the present invention.

[0017] Explanation of reference numerals in the attached drawings: 1. Valve body; 2. Shear pin seat; 3. Shear pin body; 4. Nozzle; 5. Spare cap one; 6. Ball seat; 7. Spare cap two; 8. Steel ball; 9. Sealing ring; 10. Buffer pad; 11. Lateral through hole; 12. Support shoulder; 13. Central flow channel. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Example 1 Please see Figures 1-4This invention provides an embodiment: a fracturing ball seat, comprising a valve body 1, a shear pin seat 2 installed inside the valve body 1 and threadedly connected thereto, a nozzle 4 disposed in a flow channel on the side wall of the valve body 1, a first cap 5 threadedly connected to the flow channel on the side wall of the valve body 1 for fixing the nozzle 4, a ball seat 6 disposed inside the shear pin seat 2, a second cap 7 threadedly connected to the lower part of the valve body 1, and a steel ball 8 disposed on the inner sealing surface of the ball seat 6; further comprising a shear pin body 3 and a sealing ring 9, the ball seat 6 being connected to the shear pin seat 2 via the shear pin body 3, a sealing ring 9 being disposed in a sealing groove on the outer cylindrical surface of the shear pin seat 2, the valve body 1 being a hollow cylindrical shape with a through central flow channel 13, a threaded structure for connecting a tubing string on its upper outer side, and a threaded structure for connecting the second cap 7 on its lower outer side, one or more lateral through holes 11 communicating with the central flow channel 13 on the side wall of the valve body 1, the nozzle 4 being disposed in the lateral through holes 11, the lateral through holes 11 being... 1. The inner wall of the shear pin seat 2 is threaded and threadedly connected to the spare cap 5. The inner wall of the shear pin seat 2 is provided with a support shoulder 12 that fits against the limiting ball seat 6. The support shoulder 12 is an annular bearing surface, used to bear the downward pressure transmitted between the steel ball 8 and the ball seat 6 before the ball seat 6 is knocked off. The outer cylindrical surface of the shear pin seat 2 is provided with external threads, which are engaged and fixed with the threaded section of the inner cavity of the valve body 1. The side walls of the shear pin seat 2 and the ball seat 6 are provided with at least one radial mounting hole for installing the shear pin body 3. The shear pin body 3 is a standard cylindrical pin shear screw, and its shank diameter is designed according to the required shearing pressure. The side wall of the ball seat 6 is provided with a corresponding limiting groove or through hole for the shear pin body 3 to be inserted. The nozzle 4 is a hollow tubular or perforated plate part made of wear-resistant material, with a throttling hole in the center. The spare cap 5 is cap-shaped or nut-shaped, with a through hole in the center. The outer cylindrical surface of the shear pin seat 2 is provided with at least one sealing groove. The sealing ring 9 is an O-ring or rectangular sealing ring, made of fluororubber or hydrogenated nitrile rubber.

[0020] During operation, the tool is lowered into the well to a predetermined position along with the tubing string. At this time, the ball seat 6 is fixed to the support shoulder 12 of the shear pin seat 2 by the shear pin body 3, blocking the lateral nozzle 4. The central flow channel 13 of the tool remains unobstructed and can serve as a flow passage. A steel ball 8 of a specified size is dropped from the wellhead into the tubing. A small-volume pump delivers the steel ball 8 to the tool's position, where it rests on the sealing surface of the ball seat 6. This increases the pump pressure, and the liquid pressure acts on the steel ball 8 and the ball seat 6, generating a downward force. Due to the shear pin seat... There is a sealing ring 9 between valve body 1 and valve body 2, and the ball seat 6 blocks the nozzle 4. The pressure is trapped above the tool. The oil pipe sealing performance can be judged by observing whether the casing pressure rises synchronously with the oil pipe pressure. When the oil pressure continues to rise to the setting pressure required by the compression packer, the pressure is stabilized for a period of time to allow the compression packer sleeve to fully expand and set on the inner wall of the casing. The pump pressure is continued to increase. When the pressure reaches the preset shearing pressure of the shear pin body 3, the shear pin body 3 is sheared. After the shear pin body 3 fails, the ball seat 6, along with its upper part... Under hydraulic pressure, the steel ball 8 moves downward, detaching from the shear pin seat 2. The detached ball seat 6 and steel ball 8 fall and are reliably caught and blocked by the lower end-connected spare cap 7, preventing them from falling to the bottom of the well, thus acting as a "plug". After the ball seat 6 moves downward, the side nozzle 4, which was previously blocked, is completely exposed and connected to the central flow channel 13 of the valve body 1, forming a new, mainstream fracturing fluid flow channel, and formal fracturing operations begin. When the high-pressure sand-carrying fluid flows through the valve body 1, some of the fluid flows into the annulus through the throttling orifice of the nozzle 4. Because the orifice size is much smaller than the upstream channel, a significant throttling effect is generated when the fluid flows through it, forming a stable pressure difference (P1 > P2) before and after the nozzle 4. This pressure difference acts on the expansion packer above the tool, causing it to set. At the same time, most of the high-pressure fluid continues to flow downward through the tool's central channel 13 to fracturing the target layer. The nozzle 4 is made of wear-resistant material, which can effectively resist the erosion of high-speed sand particles, ensuring the stability of the throttling pressure difference and the durability of the tool during long-term sand fracturing.

[0021] Example 2 Please see Figures 5-6 In this embodiment, based on the complete structure of embodiment 1, a buffer pad 10 is added, which is located at the lower end of the ball seat 6. The buffer pad 10 is a disc-shaped or ring-shaped elastomer with a through hole in the center. The buffer pad 10 is made of polyurethane or rubber material.

[0022] The working principle of the downhole, pressure build-up, and shearing steps is exactly the same as in Example 1. When the shearing nail body 3 is sheared, the ball seat 6 and steel ball 8 impact downwards rapidly under the drive of high-pressure liquid. The buffer pad 10 is located at the end of its falling path. The bottom of the ball seat 6 impacts the buffer pad 10 instead of directly impacting the spare cap 7. The elastic buffer pad 10 effectively absorbs and buffers the impact kinetic energy when the ball seat 6 falls off through its own compression deformation. This avoids deformation, damage, or sealing surface damage to metal parts such as the ball seat 6 and spare cap 7 due to hard collisions. It improves the reliability and service life of key tool components, buffers the impact, reduces vibration inside the tool and the tubing system, and is conducive to the stability of downhole tools.

[0023] Through the above steps and integrated structural design, a high degree of unity of multiple functions such as pressure build-up, throttling, and erosion resistance is successfully achieved in a single tool. First, the structure of the ball seat 6, which is fixed by shear pins, achieves precise pressure build-up control and reliable setting. After the ball is dropped, it can stably build up pressure, ensuring that the compression packer above it is fully set. It can also be used to check the tubing sealing performance. Second, after the shear pins are cut off when the set pressure is reached, the ball seat 6 falls onto the lower spare cap 7 and is reliably received, effectively preventing the risk of the ball seat 6 and steel ball 8 falling into the well. After the ball seat 6 falls off, the special nozzle 4 set on the side wall is exposed to form a flow channel. This nozzle 4 is specially designed to generate a stable and controllable throttling pressure differential, providing a reliable pressure source for the setting of the expansion packer. Most importantly, the nozzle 4 is made of high-strength wear-resistant material. The flow channel structure is optimized for sand-carrying fluids, possessing excellent erosion resistance and the ability to withstand the scouring of long-term, high-sand-ratio fracturing operations, greatly extending the tool's service life and reliability. Furthermore, the sealing ring 9 between the shear pin seat 2 and the valve body 1 ensures sealing during the pressure build-up stage, while the buffer pad 10 at the lower end of the ball seat 6 absorbs the impact when the ball seat 6 detaches, protecting the lower structure. This invention features a compact structure and comprehensive functions, solving the problems of functional fragmentation and insufficient durability in existing technologies. It meets the stringent requirements of high performance and high reliability for tools in multi-stage fracturing processes using a single tubing string. It addresses the issues of existing fracturing ball seats having a single function, unable to simultaneously achieve reliable pressure build-up, stable throttling, and long-term erosion resistance, resulting in unreliable pressure build-up, unstable throttling pressure differentials, susceptibility to erosion damage by fracturing sand, and the risk of the ball seat falling into the well after detachment.

[0024] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A fracturing ball seat, comprising a valve body (1), a shear pin seat (2) installed inside the valve body (1) and screwed with the valve body (1), a nozzle (4) arranged in a flow channel of a side wall of the valve body (1), a backup cap one (5) screwed in the flow channel of the side wall of the valve body (1) for fixing the nozzle (4), a ball seat (6) arranged inside the shear pin seat (2), a backup cap two (7) screwed to a lower part of the valve body (1), and a steel ball (8) arranged on a sealing surface inside the ball seat (6); characterized in that: Also include the shear pin body (3) and sealing ring (9), ball seat (6) through the shear pin body (3) and shear pin seat (2) is connected, the sealing groove on the outer cylindrical surface of shear pin seat (2) is provided with sealing ring (9).

2. The frac ball seat of claim 1, wherein: The valve body (1) is a hollow cylinder, with a through center flow channel (13), the upper part of the outer side is provided with a threaded structure for connecting the pipe column, the lower part of the outer side is provided with a threaded structure for connecting the spare cap two (7).

3. The frac ball seat of claim 2, wherein: The valve body (1) side wall is provided with one or more lateral through holes (11) which are communicated with the center flow channel (13), the nozzle (4) is arranged in the lateral through hole (11), the inner wall of the lateral through hole (11) is provided with a thread, and the spare cap one (5) is screwed.

4. The frac ball seat of claim 1, wherein: The shear pin seat (2) inner wall is provided with a support shoulder (12) which is in contact with the limiting ball seat (6), the support shoulder (12) is an annular bearing surface, used to bear the downward pressure transmitted by the steel ball (8) and the ball seat (6) before the ball seat (6) is knocked off.

5. The frac ball seat of claim 1, wherein: The outer cylindrical surface of the shear pin seat (2) is provided with external threads, which are matched and fixed with the threaded section of the inner cavity of the valve body (1), the shear pin seat (2) and the ball seat (6) side wall are provided with at least one radial mounting hole, used for mounting the shear pin body (3), the shear pin body (3) is a standard cylindrical pin type shear screw, the diameter of the rod part is designed according to the required shear pressure, and the ball seat (6) side wall is provided with a limiting groove or a through hole corresponding to the shear pin body (3) insertion.

6. The frac ball seat of claim 1, wherein: The nozzle (4) is a hollow tubular or hole plate shaped part made of wear-resistant material, with a throttle hole in the center, and the spare cap one (5) is a cover or nut shape with a through hole in the center.

7. The frac ball seat of claim 1, wherein: The outer cylindrical surface of the shear pin seat (2) is provided with at least one sealing groove, and the sealing ring (9) is an O-shaped ring or a rectangular sealing ring made of fluororubber or hydrogenated butyronitrile rubber.

8. The frac ball seat of claim 1, wherein: Also include the buffer pad (10), which is arranged at the lower end of the ball seat (6), the buffer pad (10) is a disc or ring shaped elastic body with a through hole in the center, and the buffer pad (10) is made of polyurethane or rubber material.

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