Pressure-balancing degradable ball seat

Abstract

The present application discloses a pressure-balanced degradable ball seat. The pressure-balanced degradable ball seat includes an external shell, a seating ball and a sliding shear mechanism. The external shell is used to connect to the oil and gas well tubing. The seating ball is configured to be pumped into the interior of the external shell along the oil and gas well tubing. The sliding shear mechanism is installed inside the external shell and forms a first sealing surface with the external shell. The sliding shear mechanism includes a ball receiver, which is used to receive the seating ball and form a seal with the seating ball, and is configured to be separated from the external shell by the force of the seating ball. Among them, the seating ball and the ball receiver are both degradable parts that can be degraded by the action of the well fluid. The pressure-balanced degradable ball seat also includes a pressure balancing mechanism, which is arranged in the external shell, one end of the pressure balancing mechanism is connected to the first sealing surface, and the other end of the pressure balancing mechanism is connected to the outside world, and the pressure balancing mechanism is configured to balance the pressure between the outside world and the first sealing surface.

Description

Technical Field

[0001] The present application relates to the field of drilling technology, and in particular to a pressure-balanced degradable ball seat. Background Art

[0002] As drilling and completion depths continue to increase, reducing debris in the later stages of completion becomes crucial to avoid accidents during wellbore handling. Conventional ball seats, after shearing, can create significant debris, posing a significant safety risk for re-entry during subsequent wellbore handling. Conventional ball seats are no longer fully capable of meeting the demands of oil and gas well exploration and development in ultra-deep wells, necessitating a new solution. Summary of the Invention

[0003] The present application provides a pressure-balanced degradable ball seat, which can reduce the amount of debris falling downhole after the ball seat is sheared to near zero, and the degradation products can be discharged along with the production fluid, thereby ensuring that the wellbore is unobstructed, reducing the safety risks caused by the debris re-entering the wellbore for subsequent measures, and ensuring that the wellbore is unobstructed.

[0004] The present application provides a pressure-balanced degradable ball seat, comprising an external shell, a seating ball and a sliding shear mechanism. The external shell is used to be connected to an oil and gas well tubing. The seating ball is configured to be pumped into the interior of the external shell along the oil and gas well tubing. The sliding shear mechanism is installed inside the external shell and forms a first sealing surface with the external shell. The sliding shear mechanism includes a ball receiver, which is used to receive the seating ball and form a seal with the seating ball, and is configured to be separated from the external shell by the force of the seating ball. Wherein, the seating ball and the ball receiver are both degradable parts that can be degraded by the action of well fluid. The pressure-balanced degradable ball seat also includes a pressure balancing mechanism, which is arranged in the external shell, one end of the pressure balancing mechanism is connected to the first sealing surface, and the other end of the pressure balancing mechanism is connected to the outside world, and the pressure balancing mechanism is configured to balance the pressure between the outside world and the first sealing surface.

[0005] As the depth of drilling and completion continues to deepen, reducing downhole debris becomes extremely important in the later stage of completion. It is necessary to avoid the occurrence of wellbore handling accidents in the later stage. Conventional ball seats cannot dissolve the ball receiver and the sealing ball after shearing, which then becomes a large downhole debris, which creates a great safety risk for re-entry of the later wellbore measures. For this reason, conventional ball seats can no longer fully meet the use requirements of oil and gas well mining for the exploration and development of ultra-deep wells in the later stage. In view of this, some embodiments provided by this application set the ball receiver and the sealing ball as degradable parts that can be degraded by the action of the well fluid. Therefore, after the packer is seated, the pressure in the tubing string continues to increase, and the ball receiver is gradually separated from the external shell due to the increasing force of the sealing ball. Finally, the ball receiver and the sealing ball contact the well fluid and are immersed in the well fluid. They are decomposed and dissipated under the action of the well fluid, and the degradation products are discharged with the well fluid production, thereby achieving the effect of no downhole debris and reducing the risk of wellbore construction in the later stage. Affected by the downhole pressure, the difference between the first sealing surface and the downhole pressure is large. Since the material strength of the degradable part is low, it is easy to deform under pressure, which affects the size coordination with the ball receiver and the shear sleeve, resulting in shear failure after sealing. Therefore, in order to improve the extrusion damage to the ball receiver and the external shell caused by excessive downhole pressure, resulting in shear failure and extrusion damage to the external shell, some embodiments of the present application are also provided with a pressure balancing mechanism to balance the pressure between the outside world and the first sealing surface, reduce the risk of damage to the ball receiver, and ensure that the normal function of the degradable ball seat can be safely achieved.

[0006] According to some embodiments of the present application, the pressure balancing mechanism includes a piston and a channel formed in the wall of the external shell, the piston is movably arranged in the channel and divides the channel into a first sub-channel and a second sub-channel, the first sub-channel is connected to the first sealing surface, and the second sub-channel is connected to the outside world; the first sub-channel is filled with an isolation fluid.

[0007] In the above solution, the isolation fluid is a fluid that does not chemically react with the biodegradable component. When external pressure changes, the piston moves within the channel, balancing the pressure between the first and second sub-channels, thereby balancing the pressure on the first sealing surface with the external environment. This prevents possible compression damage to the biodegradable ball receiver and external housing caused by excessive downhole pressure in ultra-deep wells, ensuring the safe and effective function of the biodegradable ball seat.

[0008] According to some embodiments of the present application, the channel includes a first section and a second section, the first section extends axially along the external shell and has a first opening connected to the outside world, and the second section is perpendicular to the first section and has a second opening connected to the first sealing surface; the pressure balancing mechanism also includes a limit member, which is arranged at the first opening and is used to limit the piston from falling out of the first opening.

[0009] In the above solution, the risk of the piston falling out of the first opening can be reduced by providing a limiter, thereby ensuring that the piston balances the internal and external pressure differences.

[0010] According to some embodiments of the present application, the limiting member includes a limiting screw, which is threadedly connected to the first opening, and the limiting screw is formed with a pressure transmission hole connecting the outside and the channel.

[0011] In the above solution, the limit member has a simple structure and is easy to manufacture. Before assembling the limit screw, the piston can be easily placed in the hole, and then the limit screw is locked to the first opening, thereby reducing the difficulty of assembly.

[0012] According to some embodiments of the present application, the pressure balancing mechanism further includes a first sealing ring and a first backing ring;

[0013] A groove is formed on the circumferential surface of the piston. The first sealing ring and the first back ring are placed on the circumferential surface of the piston and are located in the groove. The first sealing ring is located between the two first back rings. The first sealing ring forms a seal with the inner wall of the channel.

[0014] In the above solution, a first sealing ring is provided to form a seal between the piston and the interior of the channel, thereby reducing the risk of the isolation fluid leaking into the second sub-channel, so that the pressure balancing mechanism effectively balances the pressure between the outside world and the first sealing surface.

[0015] According to some embodiments of the present application, the outer shell includes an upper joint and a lower joint. Along the axial direction of the outer shell, the upper joint has a first female buckle and a first male buckle arranged opposite to each other, and the lower joint has a second female buckle and a second male buckle arranged opposite to each other. The first male buckle and the second female buckle are threadedly connected. The upper joint is connected to a section of oil and gas well tubing through the first female buckle, and the lower joint is connected to another section of oil and gas well tubing through the second male buckle.

[0016] In the above solution, the outer shell has a simple structure and is easy to manufacture and assemble.

[0017] According to some embodiments of the present application, the sliding shear mechanism further includes a shear sleeve and a shear pin;

[0018] Along the axial direction of the outer shell, the shear sleeve is located between the first male buckle and the lower joint, and is sleeved on the outer periphery of the ball receiver;

[0019] The shear pin passes through the shear sleeve and is connected to the ball receiver. The shear pin is used to limit the axial movement of the ball receiver along the outer shell. The shear pin is configured to be sheared by the force of the setting ball.

[0020] In the above scheme, the setting ball is placed in the oil pipe and is sent to the ball receiver by gravity and liquid pump. The liquid column at the front end of the ball receiver is further pressurized through the wellhead and the oil pipe. The pressure acts on the setting ball and the ball receiver and is simultaneously transmitted to the shear pin. When the breaking pressure of the shear pin is reached, the ball receiver will move downward with the setting ball and the shear pin, breaking away from the original fixed position of the ball receiver until it reacts with the well fluid and degrades.

[0021] According to some embodiments of the present application, the shear sleeve and the shear pin are both degradable parts that can be degraded by reacting with well fluid.

[0022] According to some embodiments of the present application, a second sealing ring and a third sealing ring are provided on the circumference of the ball receiver, the second sealing ring forms a seal with the inner wall of the upper joint, and the third sealing ring forms a seal with the inner wall of the lower joint;

[0023] Wherein, along the axial direction of the outer shell, the second sealing ring is located on one side of the shear pin, and the third sealing ring is located on the other side of the shear pin.

[0024] According to some embodiments of the present application, an isolation coating is provided on the surface of the ball receiver, and the isolation coating is used to prevent the well fluid from contacting the ball receiver.

[0025] In the above solution, the isolation coating refers to a high-temperature, high-pressure rubber coating with a certain strength to prevent downhole fluid from coming into contact with the degradable ball receiver, thereby preventing premature degradation of the degradable ball receiver. In some embodiments, if the ball receiver is separated from the outer housing due to pressure, the setting ball can be pressurized to destroy the isolation coating, and the ball receiver will also degrade and dissipate due to the immersion of the well fluid.

[0026] The pressure-balanced, degradable ball seat provided in some embodiments of the present application has the following advantages over conventional ball seats:

[0027] Some embodiments of the present application provide a degradable ball seat for setting hydraulic packers in ultra-deep, high-temperature, and high-pressure wells in oil and gas fields. This seat replaces conventional ball seats, thereby reducing downhole debris and eliminating the safety risk of re-entry during later wellbore construction. The seat works by placing a degradable metal ball on top of a degradable ball receiver inside the seat. Hydraulic pressure is applied to the top of the degradable ball receiver to set the hydraulic packer. Once the packer is set, the pressure in the tubing string is increased, shearing the degradable metal ball and the degradable ball receiver to the bottom of the well. The degradable metal ball and the degradable ball receiver degrade and dissipate under the action of the well fluid, and their degraded products are discharged with the production of the oil and gas well, thus achieving a zero-downhole debris effect and reducing the risk of later wellbore construction. If the degradable ball receiver cannot be sheared, the degradable metal ball and the degradable ball receiver will also degrade and dissipate under the action of the well fluid after the packer is set, preventing wellbore blockage. This provides dual protection for the cleanliness and large diameter of the completion tubing in ultra-deep, high-temperature, and high-pressure oil and gas wells. At the same time, by setting up a pressure balancing mechanism, the disadvantage of low strength of degradable metal materials can be overcome to meet the needs of ultra-deep, high-temperature, and high-pressure well completion and fracturing production. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0029] Figure 1 This is a schematic diagram of a pressure-balanced degradable ball seat in some embodiments of the present application;

[0030] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0031] Figure 3 for Figure 1 Enlarged view of point B in the middle;

[0032] Figure 4 for Figure 1 Enlarged view of point C in the middle;

[0033] Figure 5 for Figure 1 Enlarged view of point D in the middle;

[0034] Figure 6 Schematic diagram of the isolation coating and the ball receiver in some embodiments of the present application.

[0035] Icons: 10-external shell; 11-upper joint; 110-first male buckle; 12-lower joint; 120-second female buckle; 13-fourth sealing ring; 14-fixing screw; 20-sealing ball; 30-sliding shear mechanism; 31-ball receiver; 310-second sealing ring; 311-third sealing ring; 312-second back ring; 313-third back ring; 32-isolating coating; 33-shear sleeve; 34-shear pin; 40-pressure balancing mechanism; 41-piston; 42-first sub-channel; 43-second sub-channel; 44-limiting member; 45-pressure transmission hole; 46-first sealing ring; 47-first back ring. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments in the present application without creative work are within the scope of protection of the present application.

[0038] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0039] In the description of the embodiments of the present application, it should be understood that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the application is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0040] In the description of the embodiments of this application, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections, indirect connections through an intermediate medium, or internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0041] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0042] The technical solution in this application will be described below with reference to the accompanying drawings.

[0043] Some embodiments of the present application provide a pressure-balanced degradable ball seat for replacing a conventional ball seat. On the one hand, the sealing ball and the ball receiver are configured as degradable parts that can be degraded by reacting with the well fluid, thereby reducing falling objects in the well and eliminating the safety risks of re-entry during subsequent wellbore measures; on the other hand, the disadvantage of low strength of the degradable parts is overcome to ensure that the normal functions of the degradable ball seat can be safely realized.

[0044] See Figure 1-Figure 3 , Figure 1 This is a schematic diagram of a pressure-balanced degradable ball seat in some embodiments of the present application. Figure 2 for Figure 1 The enlarged view of point A in the middle. Figure 3 for Figure 1 Enlarged view of point B in the middle.

[0045] The pressure-balanced, degradable ball seat comprises an outer shell 10, a setting ball 20, and a sliding shear mechanism 30. The outer shell 10 is connected to an oil or gas well tubing. The setting ball 20 is configured to be pumped along the oil or gas well tubing into the outer shell 10. The sliding shear mechanism 30 is mounted within the outer shell 10 and forms a first sealing surface therewith. The sliding shear mechanism 30 includes a ball receiver 31, which receives and seals the setting ball 20 and is configured to be released from the outer shell 10 by the force of the setting ball 20.

[0046] The setting ball 20 and ball receiver 31 are both biodegradable components that degrade upon interaction with well fluid. The pressure-balanced biodegradable ball seat further includes a pressure-balancing mechanism 40 disposed within the external housing. One end of the pressure-balancing mechanism 40 is connected to the first sealing surface, while the other end of the pressure-balancing mechanism 40 is connected to the outside world. The pressure-balancing mechanism 40 is configured to balance the pressure between the outside world and the first sealing surface.

[0047] In some embodiments, degradable parts refer to metal materials that come into contact with corrosive downhole fluids (well fluids), can react chemically with them, and eventually dissolve and dissipate. The magnesium-aluminum alloy materials currently commonly used on the market can come into contact with and react with downhole fluids in oil field production environments, and degrade themselves within a controllable time.

[0048] The pressure balancing mechanism 40 is a mechanism for balancing the downhole pressure and the pressure inside the ball seat, reducing the risk of damage and deformation of the ball receiver 31 due to excessive pressure difference, resulting in failure to seal with the sealing ball 20, and the risk of the external shell being damaged by external extrusion.

[0049] The first sealing surface is a connection surface between the sliding shear mechanism 30 and the inner wall of the outer shell 10 that forms a seal and blocks the flow of liquid.

[0050] As drilling and completion depths continue to increase, reducing debris in the later stages of completion becomes crucial. This is crucial to avoid wellbore handling accidents. Conventional ball seats, due to the sheared ball receiver 31 and setting ball 20, cannot dissolve, resulting in large debris. This poses a significant safety risk to re-entry during later wellbore handling procedures. Consequently, conventional ball seats are no longer fully capable of meeting the requirements for oil and gas well production during the later stages of ultra-deep well exploration and development.

[0051] In view of this, some embodiments provided in the present application set the ball receiver 31 and the sealing ball 20 as degradable parts that can be degraded by the action of well fluid. Therefore, after the packer is sealed, due to the continuous increase in the pressure in the tubing, the ball receiver 31 is gradually separated from the external shell 10 due to the increasing force of the sealing ball 20. Finally, the ball receiver 31 and the sealing ball 20 come into contact with the well fluid and are immersed in the well fluid. They are decomposed and dissipated under the action of the well fluid, and their degradation products are discharged with the production of the oil and gas well, thereby achieving the effect of no bottom well debris and reducing the risk of later wellbore construction.

[0052] Affected by downhole pressure, the difference between the first sealing surface and the downhole pressure is large. Due to the low material strength of the degradable component, it is easily damaged. After the ball receiver 31 is damaged and deformed, it cannot seal with the setting ball 20, resulting in setting failure. Therefore, in order to improve the problem of extrusion damage to the ball receiver 31 and the external shell 10 caused by excessive downhole pressure, leading to setting failure, some embodiments of the present application are further provided with a pressure balancing mechanism 40 to balance the pressure between the external environment and the first sealing surface, avoiding the risk of extrusion damage to the ball receiver 31 and ensuring the normal function of the degradable ball seat can be safely achieved.

[0053] According to some embodiments of this application, see Figure 2 and Figure 3The pressure balancing mechanism 40 includes a piston 41 and a channel formed on the wall of the external shell 10. The piston 41 is movably arranged in the channel and divides the channel into a first sub-channel 42 and a second sub-channel 43. The first sub-channel 42 is connected to the first sealing surface, and the second sub-channel 43 is connected to the outside world; the first sub-channel 42 is filled with an isolation liquid.

[0054] The isolation liquid may be a fluid used to fill the first sub-channel 42 and is a fluid that does not chemically react when in contact with the degradable component.

[0055] The first sub-channel 42 is connected to the interior of the ball seat, and the internal pressure thereof can refer to the internal pressure of the ball seat. The second sub-channel 43 is connected to the outside, and the internal pressure thereof can be equal to the downhole pressure.

[0056] The piston 41 may refer to a component that can extend along the direction of the hole, such as Figure 2 As shown, the piston 41 can slide left and right in the channel. When a pressure difference is formed between the first sub-channel 42 and the second sub-channel 43, the piston 41 can slide left and right under the action of the pressure difference and the isolation fluid to balance the internal and external pressure difference.

[0057] In the above solution, the isolation fluid is a fluid that does not chemically react with the biodegradable component. When external pressure changes, the piston 41 can move within the channel, balancing the pressure between the first sub-channel 42 and the second sub-channel 43. This balances the pressure between the first sealing surface and the external environment. This prevents excessive downhole pressure in ultra-deep wells from causing damage to the biodegradable ball receiver 31 and the outer shell 10, ensuring the safe and proper function of the biodegradable ball seat.

[0058] According to some embodiments of this application, please combine Figure 2 and Figure 3 The channel includes a first section and a second section. The first section extends axially along the outer housing 10 and has a first opening communicating with the outside. The second section is perpendicular to the first section and has a second opening communicating with the first sealing surface. The pressure balancing mechanism 40 also includes a stopper 44 disposed at the first opening to prevent the piston 41 from exiting the first opening.

[0059] In some embodiments, the first section extends along the axial direction of the outer shell 10 so that the piston 41 has a sufficiently long movement path to meet the pressure balance requirement. The second section is the portion connecting the first sealing surface and the first section.

[0060] The stopper 44 is provided at the first opening, and the function of the stopper 44 is to prevent the piston 41 from being disengaged from the passage through the first opening. In some embodiments, when assembling the piston 41, the stopper 44 can be removed first, then the piston 41 is assembled, and finally the stopper 44 is assembled.

[0061] In the above solution, the risk of the piston 41 falling out of the first opening can be reduced by providing the limiting member 44 , thereby ensuring that the piston 41 balances the internal and external pressure differences.

[0062] According to some embodiments of the present application, see Figure 3 The limiting member 44 includes a limiting screw, which is threadedly connected to the first opening, and the limiting screw forms a pressure transmission hole 45 communicating with the outside and the channel.

[0063] In the above solution, the limiting member 44 has a simple structure and is easy to manufacture. Before assembling the limiting screw, the piston 41 can be easily placed in the hole, and then the limiting screw is locked to the first opening to reduce the difficulty of assembly.

[0064] According to some embodiments of the present application, see Figure 3 The pressure balancing mechanism 40 further includes a first sealing ring 46 and a first backing ring 47. A groove is formed on the circumference of the piston 41. The first sealing ring 46 and the first backing ring 47 are sleeved on the circumference of the piston 41 and located in the groove. The first sealing ring 46 is located between the two first backing rings 47, and the first sealing ring 46 forms a seal with the inner wall of the channel.

[0065] In the above solution, a first sealing ring 46 is provided to form a seal between the piston 41 and the interior of the channel, thereby reducing the risk of the isolation fluid leaking into the second sub-channel 43, so that the pressure balancing mechanism 40 effectively balances the pressure between the outside and the first sealing surface.

[0066] According to some embodiments of the present application, see Figure 1 The outer shell 10 includes an upper joint 11 and a lower joint 12. Along the axial direction of the outer shell 10, the upper joint 11 has a first female buckle and a first male buckle 110 arranged opposite to each other, and the lower joint 12 has a second female buckle 120 and a second male buckle arranged opposite to each other. The first male buckle 110 and the second female buckle 120 are threadedly connected. The upper joint 11 is connected to a section of oil and gas well tubing through the first female buckle, and the lower joint 12 is connected to another section of oil and gas well tubing through the second male buckle.

[0067] In some embodiments, in order to improve the connection stability between the upper joint 11 and the lower joint 12, a fixing screw 14 is provided between the upper joint 11 and the lower joint 12. The fixing screw 14 is arranged along the radial direction of the upper joint 11 and the lower joint 12 to prevent the thread between the first male buckle 110 and the second female buckle 120 from loosening and disengaging, thereby limiting the relative movement of the upper joint 11 and the lower joint 12 along the axial direction.

[0068] In the above solution, the outer shell 10 has a simple structure and is easy to manufacture and assemble.

[0069] According to some embodiments of the present application, see Figure 1The sliding shear mechanism 30 further includes a shear sleeve 33 and a shear pin 34. Along the axial direction of the outer shell 10, the shear sleeve 33 is located between the first male buckle 110 and the lower joint 12, and is sleeved on the outer periphery of the ball receiver 31.

[0070] The shear pin 34 passes through the shear sleeve 33 and is connected to the ball receiver 31 . The shear pin 34 is used to limit the axial movement of the ball receiver 31 along the outer shell 10 . The shear pin 34 is configured to be sheared by the force of the setting ball 20 .

[0071] In some embodiments, a slot is formed on the outer periphery of the ball receiver 31 , and the slot is corresponding to the shear pin 34 , and the shear pin 34 is inserted into the slot.

[0072] The shear pins 34 are used to fix the ball receiver 31 and provide rated shear force. The number of the shear pins 34 can be adjusted during use.

[0073] In the above scheme, the setting ball 20 is placed in the oil pipe and is transported to the ball receiver 31 by gravity and liquid pumping. The liquid column at the front end of the ball receiver 31 is further pressurized through the wellhead and the oil pipe. The pressure acts on the setting ball 20 and the ball receiver 31, and is simultaneously transmitted to the shear pin 34. When the breaking pressure of the shear pin 34 is reached, the ball receiver 31 will move downward with the setting ball 20 and the shear pin 34, breaking away from the original fixed position of the ball receiver 31 until it reacts with the well fluid and degrades.

[0074] According to some embodiments of the present application, the shear sleeve 33 and the shear pin 34 are both degradable parts that can be degraded by reacting with the well fluid. For example, the shear sleeve 33 and the shear pin 34 are both made of magnesium-aluminum alloy material, which can contact and react with the downhole fluid in the oil field production environment and degrade by themselves within a controllable time.

[0075] According to some embodiments of this application, see Figure 4 and Figure 5 , Figure 4 for Figure 1 The enlarged image of point C in the middle, Figure 5 for Figure 1 Enlarged view of point D in the middle.

[0076] A second sealing ring 310 and a third sealing ring 311 are provided around the periphery of the ball receiver 31. The second sealing ring 310 forms a seal with the inner wall of the upper joint 11, while the third sealing ring 311 forms a seal with the inner wall of the lower joint 12. Axially, along the outer housing 10, the second sealing ring 310 is located on one side of the shear pin 34, while the third sealing ring 311 is located on the other side of the shear pin 34.

[0077] See also Figure 4The circumferential surface of the ball receiver 31 is formed with a groove corresponding to the second sealing ring 310 and a groove corresponding to the third sealing ring 311.

[0078] The second sealing ring 310 is disposed in the corresponding groove and is restrained by two second back rings 312. The third sealing ring 311 is disposed in the corresponding groove and is restrained by two third back rings 313.

[0079] See Figure 4 A fourth sealing ring 13 is provided between the upper joint 11 and the lower joint 12. The fourth sealing ring 13 is sleeved on the outer periphery of the first male buckle 110 of the upper joint 11, and a seal is formed between the fourth sealing ring 13 and the inner wall of the second female buckle 120 of the lower joint 12.

[0080] According to some embodiments of the present application, an isolation coating 32 is provided on the surface of the ball receiver 31 , and the isolation coating 32 is used to prevent the well fluid from contacting the ball receiver 31 .

[0081] In some embodiments, see Figure 6 , Figure 6 Schematic diagram of the isolation coating 32 and the ball receiver 31 in some embodiments of the present application.

[0082] The isolation coating 32 is processed, wrapped and bonded to the inner surface of the degradable ball receiver 31 and extends to the grooves on both sides of the ball receiver 31 corresponding to the second sealing ring 310 and the third sealing ring 311.

[0083] In some embodiments, an isolation coating 32 may also be provided on the surface of the setting ball 20 .

[0084] In the above embodiment, the isolation coating 32 is a high-temperature, high-pressure rubber coating with a certain strength to prevent downhole fluid from coming into contact with the degradable ball receiver 31, thereby preventing premature degradation of the degradable ball receiver 31. In some embodiments, if the ball receiver 31 is separated from the outer housing 10 due to pressure, the setting ball 20 can be pressurized to destroy the isolation coating 32, and the ball receiver 31 will also degrade and dissipate due to the immersion of the well fluid.

[0085] According to some embodiments of the present application, a pressure-balanced degradable ball seat is provided. The specific structure of the pressure-balanced degradable ball seat can be found in the above description. The pressure-balanced degradable ball seat has the following three states:

[0086] The outer shell 10 is sealed inside and outside: the upper joint 11 and the lower joint 12 are connected by threads and sealed by O-rings (the first sealing ring 46 and the fourth sealing ring 13) to separate the inside and the outside and prevent communication.

[0087] The ball receiver 31 is isolated from the internal fluid of the ball seat: a sealed isolation is formed between the isolation coating 32, the O-ring (the second sealing ring 310 and the third sealing ring 311), and the inner holes of the upper joint 11 and the lower joint 12.

[0088] Pressure balance system: The inner sides of the upper joint 11, the inner sides of the lower joint 12, the outer sides of the ball receiver 31, and the inner sides of the piston 41 form an internal closed space formed by O-rings (second and third sealing rings 310 and 311), the isolation coating 32, the O-ring (fourth sealing ring 13), and the O-ring (first sealing ring 46). This internal closed space is filled with an isolation fluid. When the external pressure changes, the piston 41 inside the lower joint 12 can move left and right to balance the pressure inside the closed space with the external pressure, thereby preventing the degradable ball receiver 31 and the outer wall of the ball seat from being squeezed and damaged by excessive downhole pressure in ultra-deep wells.

[0089] The following is a use of a pressure-balanced degradable ball seat:

[0090] First, a degradable metal ball (i.e., setting ball 20) is placed in the tubing and pumped to the degradable ball receiver 31 by gravity and a liquid pump. The line seal between the two isolates the space at both ends of the ball receiver 31. Pressure is then applied to the liquid column at the front end of the ball receiver 31 through the wellhead and tubing. Due to the line seal between the setting ball 20 and the ball receiver 31, and the second sealing ring 310 between the ball receiver 31 and the upper joint 11, pressure acts on the setting ball 20 and the ball receiver 31, and is simultaneously transmitted to the shear pin 34. When the shear pin 34 reaches its breaking pressure, the ball receiver 31, along with the second and third sealing rings 310 and 311, the isolation coating 32, and the shear pin 34, moves downward, freeing it from its original fixed position. Once free, the exposed metal parts of the ball receiver 31, shear sleeve 33, and shear pin 34 come into contact with the well fluid. The process then requires only waiting for the ball receiver 31, shear sleeve 33, and shear pin 34 to degrade. The oil and gas well can then resume normal production, and impurities produced by degradation can be discharged from the wellbore along with the production fluid, ensuring a zero-drop effect at the bottom of the well.

[0091] If the ball receiver 31 cannot shear normally, the setting ball 20 can destroy the isolation coating 32 by applying pressure, and the ball receiver 31, shear sleeve 33, and shear pin 34 will also degrade and dissipate by themselves under the immersion of well fluid.

[0092] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A pressure-balanced degradable ball seat, characterized in that: include: An outer shell, used for connecting to an oil pipe of an oil and gas well; a setting ball configured to be pumped along the oil and gas well tubing into the interior of the outer housing; a sliding shear mechanism installed inside the outer shell and forming a first sealing surface with the outer shell, the sliding shear mechanism including a ball receiver, the ball receiver being used to receive the setting ball and form a seal with the setting ball, and being configured to be separated from the outer shell by the force of the setting ball; Wherein, the setting ball and the ball receiver are both degradable parts that can be degraded by reacting with well fluid; The pressure-balanced degradable ball seat further comprises a pressure-balancing mechanism, which is disposed on the external shell, one end of the pressure-balancing mechanism being connected to the first sealing surface, and the other end of the pressure-balancing mechanism being connected to the outside, and the pressure-balancing mechanism being configured to balance the pressure between the outside and the first sealing surface; The pressure balancing mechanism includes a piston and a channel formed in the wall of the outer shell, the piston is movably disposed in the channel and divides the channel into a first sub-channel and a second sub-channel, the first sub-channel is connected to the first sealing surface, and the second sub-channel is connected to the outside; The first sub-channel is filled with an isolation liquid; The channel includes a first section and a second section, the first section extending along the axial direction of the outer shell and having a first opening communicating with the outside, and the second section being perpendicular to the first section and having a second opening communicating with the first sealing surface; the piston is movably disposed in the first section and divides the first section into the first sub-channel and the second sub-channel; The pressure balancing mechanism further includes a limiter, which is provided at the first opening and is used to limit the piston from being disengaged from the first opening; an isolation coating is provided on the surface of the ball receiver, and the isolation coating is used to prevent well fluid from contacting the ball receiver.

2. The pressure-balanced degradable ball seat according to claim 1, characterized in that: The limiting member includes a limiting screw, which is threadedly connected to the first opening, and the limiting screw is formed with a pressure transmission hole communicating with the outside and the channel.

3. The pressure-balanced degradable ball seat according to claim 1, characterized in that: The pressure balancing mechanism further includes a first sealing ring and a first backing ring; A groove is formed on the circumferential surface of the piston. The first sealing ring and the first back ring are placed on the circumferential surface of the piston and are located in the groove. The first sealing ring is located between the two first back rings. The first sealing ring forms a seal with the inner wall of the channel.

4. The pressure-balanced degradable ball seat according to any one of claims 1 to 3, characterized in that: The outer shell includes an upper joint and a lower joint. Along the axial direction of the outer shell, the upper joint has a first female buckle and a first male buckle arranged opposite to each other, and the lower joint has a second female buckle and a second male buckle arranged opposite to each other. The first male buckle and the second female buckle are threadedly connected. The upper joint is connected to a section of oil and gas well tubing through the first female buckle, and the lower joint is connected to another section of oil and gas well tubing through the second male buckle.

5. The pressure-balanced degradable ball seat according to claim 4, characterized in that: The sliding shearing mechanism further comprises a shearing sleeve and a shearing pin; Along the axial direction of the outer shell, the shear sleeve is located between the first male buckle and the lower joint, and is sleeved on the outer periphery of the ball receiver; The shear pin passes through the shear sleeve and is connected to the ball receiver. The shear pin is used to limit the axial movement of the ball receiver along the outer shell. The shear pin is configured to be sheared by the force of the setting ball.

6. The pressure-balanced degradable ball seat according to claim 5, characterized in that: The shear sleeve and the shear pin are both degradable parts that can be degraded by reacting with well fluid.

7. The pressure-balanced degradable ball seat according to claim 5, characterized in that: The circumference of the ball receiver is provided with a second sealing ring and a third sealing ring, the second sealing ring forms a seal with the inner wall of the upper joint, and the third sealing ring forms a seal with the inner wall of the lower joint; Wherein, along the axial direction of the outer shell, the second sealing ring is located on one side of the shear pin, and the third sealing ring is located on the other side of the shear pin.

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