Discharge valve, tubular column assembly and pressure relief control method

Abstract

The invention discloses a discharge valve, a tubular column assembly and a pressure relief control method, and belongs to the technical field of oil extraction equipment. The discharge valve comprises a shell, a valve element, a valve element sleeve and an elastic locking piece. A through hole is formed in the shell, the valve element is arranged in the through hole, and the end, in the axis direction of the through hole, of the valve element is provided with a conical surface, so that a gap flow channel with the width increased in one direction is formed between the valve element and the inner wall of the through hole. The valve core sleeve is arranged in the through hole, and the valve core sleeve can be movably and annularly sleeved on the conical surface along the axis direction of the through hole so as to adjust the width of the gap runner; the elastic locking piece is connected between the shell and the valve element sleeve so as to provide acting force for filling and pressing the valve element sleeve into the gap flow channel to reduce the width of the gap flow channel. According to the discharge valve, the pipe column assembly and the pressure relief control method, the convenience and reliability of residual oil removal operation of the upward oil conveying pipe of the electric submersible pump can be effectively improved, and the pipe lifting safety risk of the electric submersible pump is reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of oil production equipment, and in particular relates to a relief valve, a pipe column assembly and a pressure relief control method. Background Art

[0002] In the ESP production process, the ESP will be lowered into the well, and the outlet is connected to a pipe string to transport oil upward. When the ESP is shut down and the pipe string is raised, there is a large amount of crude oil inside the oil pipe above the ESP, which poses a risk of oil impacting the impeller of the ESP, which can easily cause risks to the motor and impeller. For this reason, a one-way check valve is added to the pipe string above the ESP to prevent the crude oil from flowing back into the pipe, thereby reducing the risk of damage to the ESP.

[0003] However, the one-way check valve also causes the oil in the pipe string to be unable to be discharged when the pipe string is lifted up, resulting in a large amount of crude oil in the pipe being brought out of the ground during wellhead operations, polluting the well site on a large scale, and also posing a safety risk of harmful gases. On the other hand, the check valve works better in shallow wells. As the depth of the well increases, the hydraulic pressure on the check valve gradually increases, and the risk of failure to seal and damage gradually increases, and the protection ability of the electric submersible pump is unreliable. In some solutions, a relief valve is set on the pipe string, but it is necessary to operate the relief valve downhole on the service pipe string under the ground, which is very inconvenient to operate, and due to the effect of hydraulic pressure, the opening resistance and difficulty are also very large. Summary of the invention

[0004] The present application provides a relief valve, a tubing assembly and a pressure relief control method, which are intended to at least to some extent solve the technical problems that the oil in the tubing above the electric submersible pump is easy to impact and damage the electric submersible pump during the pipe lifting process, the function of the relief structure is unreliable, and the operation is inconvenient.

[0005] In one aspect of an embodiment of the present application, a drain valve is provided, comprising: a housing, a valve core, a valve core sleeve and an elastic locking member;

[0006] A through hole is provided in the housing, the valve core is arranged in the through hole, and one end of the valve core along the axial direction of the through hole is provided with a conical surface to form a gap flow channel with a unidirectionally increasing width between the valve core and the inner wall of the through hole;

[0007] The valve core sleeve is arranged in the through hole, and the valve core sleeve can be movably sleeved on the conical surface along the axial direction of the through hole to adjust the width of the gap flow channel;

[0008] The elastic locking member is connected between the housing and the valve core sleeve to provide a force to fill and press the valve core sleeve into the gap flow channel to reduce the width of the gap flow channel.

[0009] In some embodiments, the valve core is a columnar member, and the axis of the valve core coincides with the central axis of the through hole.

[0010] In some embodiments, the valve core sleeve is a cylindrical member, and the inner wall of the valve core sleeve is configured as an inner conical surface that matches the conical surface.

[0011] In some embodiments, the outer peripheral surface of the valve core sleeve abuts against the hole wall of the through hole.

[0012] In some embodiments, the elastic locking member includes a coil spring, which is sleeved on the outside of the valve core sleeve, and the first end of the coil spring abuts against a stop portion on the outer circumferential surface of the valve core sleeve, and the second end abuts against the shell to apply a force to push the valve core sleeve in the direction of filling and reducing the width of the gap flow channel.

[0013] In some embodiments, an anti-slip frame is disposed on the housing, and the anti-slip frame extends into the through hole, and the second end of the coil spring abuts against the anti-slip frame.

[0014] In some embodiments, the valve core sleeve is a sealing rubber member.

[0015] According to another aspect of an embodiment of the present application, a pipe column assembly is provided, comprising a pipe column and any one of the above-mentioned relief valves, wherein the relief valve is connected to a relief hole opened on a side wall of the pipe column.

[0016] Another aspect of the embodiment of the present application further provides a pressure relief control method, which is applied to the pipe pulling operation of an electric submersible pump equipped with the above-mentioned pipe string assembly;

[0017] The pressure relief control method comprises:

[0018] The height of the annular liquid column between the oil pipeline string and the outer casing string is adjusted so that the hydraulic pressure at the outlet side of the relief valve is lower than the hydraulic pressure inside the oil pipeline string by a magnitude greater than the opening pressure of the relief valve.

[0019] In some embodiments, the opening pressure is the elastic deformation force of the elastic locking member when the spacing width between the valve core sleeve and the conical surface reaches a preset value.

[0020] The embodiments of the present application have at least the following beneficial effects:

[0021] The relief valve, tubing assembly and pressure relief control method provided in the embodiment of the present application are provided by arranging a valve core in the through hole opened on the shell along the axial direction thereof, and opening the axial end of the valve core into a conical surface, so as to form a gap flow channel with a width that increases in one direction between the valve core and the inner wall of the through hole; and sleeved on the conical surface, so that the filling, compression and sealing of the gap flow channel can be achieved by moving the valve core sleeve along the axial direction of the valve core, or increasing the gap of the release flow channel to achieve the opening adjustment of the relief valve. When the relief valve is applied to the oil pipeline, there is fluid oil on both sides of it and it is subjected to fluid pressure, so that by adjusting the fluid pressure difference on both sides of the relief valve, the valve core sleeve can be pushed by the thrust in the oil pipeline to move the valve core sleeve, disengage from and move away from the conical surface, and achieve one-way opening, or approach and press on the conical surface, and achieve the closing function. When the submersible pump is stopped and the pipe is lifted underground, the liquid level in the casing annulus outside the oil pipeline is adjusted, and the hydraulic pressure is adjusted to be lower than the oil pressure of the residual oil in the oil pipeline, so as to open the relief valve and discharge the residual oil in the oil pipeline, thereby reducing the safety risk of residual oil impacting the impeller of the submersible pump and improving the safety of operation. At the same time, the elastic locking member applies a stable elastic force to the valve core sleeve, which can push the valve core sleeve in the direction of sealing the gap flow channel, so that it can maintain its normally closed locking state and ensure the reliability of its pressure relief operation; and when pressure relief is required, the elastic locking member can be deformed to give the valve core sleeve a moving space, open and increase the gap flow channel, and ensure the reliability of the relief valve function. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 A cross-sectional view of a relief valve in an embodiment of the present application is shown;

[0024] Figure 2 Shows Figure 1 A cross-sectional view of the matching state of the housing and the valve core in the relief valve;

[0025] Figure 3 Shows Figure 1 A cross-sectional view of the valve core sleeve in the relief valve.

[0026] Reference numerals:

[0027] 100-housing, 110-anti-drop frame, 120-shearing arm, 130-through hole, 131-gap flow channel;

[0028] 200-valve core, 210-conical surface;

[0029] 300 - valve core sleeve, 310 - outer peripheral surface, 311 - first cylinder diameter portion, 312 - second cylinder diameter portion, 313 - stop portion, 320 - cylinder cavity, 321 - inner conical surface. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in 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. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0031] In addition, the present application may repeat reference numbers and / or reference letters in different examples, and such repetition is for the purpose of simplicity and clarity, and does not in itself indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides various specific examples of processes and materials, but those of ordinary skill in the art may recognize the application of other processes and / or the use of other materials.

[0032] The present application is described below with reference to the accompanying drawings and specific embodiments:

[0033] In order to prevent the residual oil in the upward oil pipeline from impacting and damaging the impeller of the submersible pump when the submersible pump is lifted from the well, a check valve is often used to limit the downward movement of the oil. However, as the depth of the well increases and the height of the residual oil column increases, the reliability of the one-way check valve will be greatly reduced, and it is very easy to be damaged by pressure and impact the impeller of the submersible pump; at the same time, the residual oil is also easy to follow the oil pipeline to the surface well site, causing on-site pollution. Alternatively, a mechanical relief valve is installed on the oil pipeline, which requires ground operators to remotely operate the service pipe column. This operation mode will increase dramatically with the increase of the depth of the well, and the opening resistance will be very large due to the effect of fluid pressure. The overall operating efficiency is not ideal, and it may even be impossible to open. The operability increases significantly with the increase of the depth of the well.

[0034] To this end, the present application provides a relief valve, a tubing assembly and a pressure relief control method, which aim to improve the convenience of removing residual oil in the upward oil pipeline of the electric submersible pump, reduce the difficulty of operation, improve the operating efficiency, and improve the safety of the use of the electric submersible pump.

[0035] Figure 1 A cross-sectional view of a relief valve in an embodiment of the present application is shown; Figure 2 Shows Figure 1 A cross-sectional view of the matching state of the housing and the valve core in the relief valve; Figure 3 Shows Figure 1 A cross-sectional view of the valve core sleeve in the relief valve.

[0036] See also Figure 1 , Figure 2 and Figure 3 In some embodiments, in order to adapt to the working conditions of downhole use, and there is a certain amount of fluid on the inner side of the oil pipeline and in the annulus between it and the outer casing, a relief valve structure based on the pressure difference opening and closing principle can be adopted, and the pressure difference control inside and outside the oil pipeline is used as a control means for opening and closing the relief valve.

[0037] Specifically, the pressure relief valve includes: a housing 100 , a valve core 200 , a valve core sleeve 300 and an elastic locking member 400 .

[0038] The housing 100 is the installation base of the pressure relief valve. On the one hand, it is used to be installed on the oil pipeline column. On the other hand, it serves as the installation base of the structure and components with the pressure relief function. In order to realize the flow discharge function, a through hole 130 can be opened in the housing 100 as a flow discharge channel, so that when it is installed on the oil pipeline, the inside and outside of the oil pipeline are connected to discharge the residual oil inside.

[0039] The valve core 200 and the valve core sleeve 300 are arranged in the through hole 130, and the valve core sleeve 300 and the valve core 200 can move relative to each other to cooperate in sealing or opening the through hole 130. One end of the valve core 200 along the axial direction of the through hole 130 can be opened into a conical surface 210 to form a gap flow channel 131 with a unidirectionally changing width between the conical surface 210 and the inner wall of the through hole 130, which is connected with the cylindrical cavity 320 of the valve core sleeve 300 to form a drainage flow channel. The valve core sleeve 300 is sleeved on the valve core 200, and can be specifically sleeved on the conical surface 210, and can move along the axial direction of the conical surface 210, so that the width of the gap flow channel 131 can be adjusted through the relative movement of the two, and the opening of the discharge valve can be adjusted to achieve opening and closing.

[0040] When the valve core sleeve 300 moves to the bottom area of ​​the conical surface 210, it can fill and seal the gap flow channel 131, isolate the through hole 130, and thus close the leakage valve; when the valve core sleeve 300 moves to the top area of ​​the conical surface 210, it can gradually increase the opening of the gap flow channel 131 until it reaches the maximum, thereby fully opening the leakage valve.

[0041] It is worth noting that when the relief valve is applied to the oil pipeline, there is fluid oil on both sides of the relief valve, which is subjected to fluid pressure. Therefore, by adjusting the fluid pressure difference on both sides of the relief valve, the valve core sleeve 300 as a whole is pushed by the thrust in the oil pipeline to move the valve core sleeve 300, disengage from and move away from the conical surface 210, and realize one-way opening; or, the valve core sleeve 300 as a whole is pressed against and pressed against the conical surface 210 by the oil pressure outside the oil pipeline, and realizes the closing function. When the electric submersible pump is shut down and the pipe is lifted, the liquid level in the casing annulus outside the oil pipeline is adjusted, and the hydraulic pressure is adjusted to be lower than the oil pressure of the residual oil in the oil pipeline, so as to open the relief valve and discharge the residual oil in the oil pipeline, thereby reducing the safety risk of residual oil impacting the impeller of the electric submersible pump and improving the safety of operation.

[0042] The elastic locking member 400 is connected between the housing 100 and the valve core sleeve 300, and applies an initial force to the valve core sleeve 300 based on the housing 100 to keep it in the initial position; usually, the relief valve can be set as a normally closed valve, that is, under normal conditions, it remains in a locked state to meet the use requirements of the closed state of the oil pipeline during operation; at this time, the elastic locking member 400 can apply elastic pressure to the valve core sleeve 300 to fill and press it into the gap flow channel 131, reduce the width of the gap flow channel, and even completely fill and seal the gap flow channel 131.

[0043] It is worth mentioning that, by applying a stable elastic force to the valve core sleeve 300 through the elastic locking piece 400, the valve core sleeve 300 can be pushed in the direction of sealing the gap flow channel 131, thereby maintaining its normally closed locking state and ensuring the reliability of its pressure relief operation; and when pressure relief is required, the oil in the oil pipeline can drive the valve core sleeve 300 to push the elastic locking piece 400 to deform, thereby making room for the valve core sleeve 300 to move, opening and increasing the opening of the gap flow channel 131, and ensuring the reliability of the relief valve function.

[0044] In some embodiments, in order to maintain the sealing performance, the valve core 200 can be set as a columnar member, and the axis of the valve core 200 coincides with the central axis of the through hole 130. The valve core sleeve 300 is a cylindrical member, and the inner wall of the valve core sleeve 300 is set as an inner conical surface 321 adapted to the conical surface 210. Therefore, when the valve core sleeve 300 is sleeved on the valve core 200, it can move stably and conveniently to achieve sealing and unsealing.

[0045] In some embodiments, in order to take into account both sealing performance and flow channel leakage stability, the outer peripheral surface of the valve core sleeve 300 can be abutted against the hole wall of the through hole 130 and continuously maintained in a sealed state as a normal state; the gap flow channel 131 is mainly composed of the conical surface 210 and the inner conical surface 321 of the valve core sleeve 300, so that the openable area can be used as the main leakage flow channel to ensure leakage stability.

[0046] In some embodiments, the elastic locking member 400 can exert an elastic maintaining force to press the valve core sleeve 300 onto the valve core 200 to maintain a stable sealing state.

[0047] In some embodiments, considering the annular sealing mode of the valve core sleeve 300, the elastic locking member 400 may include a coil spring, which is sleeved on the outside of the valve core sleeve 300, and the coil spring is compressed and abutted against the housing 100 and the valve core sleeve 300, so that pressure can be evenly applied to the annular sealing surface of the valve core sleeve 300 to maintain the reliability of the seal.

[0048] In some embodiments, in order to facilitate the fixation of the coil spring, a stop portion 313 may be provided on the outer peripheral surface 310 of the valve core sleeve 300, the first end of the coil spring abuts against the stop portion 313, and the second end of the coil spring abuts against the housing 100 to apply a force to push the valve core sleeve 300 in the direction of filling and reducing the width of the gap flow channel 131.

[0049] In some embodiments, the cylinder body of the valve core sleeve 300 can be set as a stepped cylinder, that is, the outer peripheral surface 310 is divided into two sections according to the difference in diameter: a first cylinder diameter portion 311 and a second cylinder diameter portion 312, and the outer diameter of the first cylinder diameter portion 311 is greater than the outer diameter of the second cylinder diameter portion 312.

[0050] The outer peripheral surface of the first cylindrical portion 311 contacts and abuts against the through hole 130, and maintains a surface contact seal. A stopper 313 protruding from the peripheral surface of the second cylindrical portion 312 is formed at the boundary between the second cylindrical portion 312 and the first cylindrical portion 311, so that the coil spring can be sleeved on the second cylindrical portion 312 and the first end of the coil spring abuts against the stopper 313.

[0051] In some embodiments, in order to facilitate compression limiting of the coil spring, an anti-slip frame 110 may be provided on the housing 100 , and the anti-slip frame 110 extends into the through hole 130 , and the second end of the coil spring abuts against the anti-slip frame 110 .

[0052] At the same time, by stopping and limiting the second end of the coil spring, the movement range of the valve core sleeve 300 can be substantially limited, and its separation from the through hole 130 can be limited, thereby ensuring the stability of the functional structure.

[0053] In some embodiments, the anti-drop frame 110 can be configured as a stop ring protruding from the inner wall of the through hole 130, so as to be matched and abutted by the coil spring.

[0054] In some embodiments, the valve core sleeve 300 can be configured as a sealing rubber member having adaptive deformation sealing capability to obtain stable and reliable sealing performance.

[0055] In some embodiments, a shear arm 120 may also be provided on the housing 100, and the shear arm 120 may be provided on the moving trajectory of the valve core sleeve 300 to limit the extent to which the valve core sleeve 300 moves away from the valve core 200; this is intended to maintain the reliability of the locking of the relief valve and ensure that a certain degree of sealing of the relief valve is maintained when the above-mentioned oil pipeline is working, and even if a leakage gap occurs, it is at a relatively low level that can be ignored.

[0056] Only when the discharge valve is opened to discharge, the valve core sleeve will push and shear the shear arm after moving a certain range, so that the valve core sleeve can further move in the direction of opening the discharge valve.

[0057] Another aspect of an embodiment of the present application provides a tubular column assembly, comprising a tubular column and a drain valve as described above, wherein the drain valve is connected to a drain hole opened on a side wall of the tubular column and can maintain a normally closed state of the drain valve.

[0058] In another aspect of the embodiment of the present application, a pressure relief control method is provided, which is applied to the tubing lifting operation of an electric submersible pump equipped with the above-mentioned tubing string assembly.

[0059] Before the actual operation, the electric submersible pump, oil pipe string, casing and blowout prevention components are strictly set inside and outside the oil well. When the pipe needs to be pulled up and the electric submersible pump is retracted, the following pressure relief control operations can be performed:

[0060] The height of the annular liquid column between the oil pipeline string and the outer casing string is adjusted so that the hydraulic pressure at the outlet side of the relief valve is lower than the hydraulic pressure inside the oil pipeline string by a magnitude greater than the opening pressure of the relief valve.

[0061] Generally speaking, considering that the residual oil in the oil pipe is difficult to be directly extracted, the fluid in the annular space between the oil pipeline and the outer casing can be extracted to reduce the internal liquid level, thereby reducing the hydraulic pressure on the outlet side of the pressure relief valve. When the residual oil hydraulic pressure in the oil pipeline is basically unstable, the hydraulic pressure difference component increases until it is greater than the elastic pressure of the elastic locking member, which will cause the combined force on the valve core sleeve to push the valve core sleeve toward the outer casing, thereby gradually expanding the width of the gap flow channel, and the corresponding residual oil will gradually be discharged. Finally, the opening of the relief valve reaches the maximum, and the residual oil is discharged at a continuous large flow rate. In this way, the residual oil discharge of the oil pipeline can be achieved remotely and stably.

[0062] In some embodiments, generally speaking, the elastic coefficient of the elastic locking member can be set based on empirical data so that the opening pressure is the elastic deformation force of the elastic locking member when the spacing width between the valve core sleeve and the conical surface reaches a preset value.

[0063] The weight of the impeller in the oil pipe is known, and the initial height and vertical depth of the liquid level are H. t , that is, the depth of the electric pump, the pressure acting on the oil pipe side of the suction port is P1, P1 = ρ o HkDJ t , the pressure on the outer casing side of the suction port is P2, P2 = ρ o HkDJ a , ΔP=P1-P2. The cone structure in the relief valve is controlled by the pressure difference between P1 and P2 and the internal coil spring. The coil spring set value pressure F=ΔP max ×S cone, ΔP max It is the initial state, the pressure difference between the full oil pipe liquid column pressure and the annulus liquid column pressure. Its overall shape changes from a conical step to an ordinary step. When the operation starts from the pipe string to the last stage of the oil pipe, the control nozzle is fully opened to ensure normal pressure relief without damaging the impeller and the electric pump motor.

[0064] The embodiments of the present application have at least the following beneficial effects:

[0065] The embodiments of the present application provide a relief valve, a tubular column assembly, and a pressure relief control method. A valve core is arranged in a through hole opened on a shell along its axial direction, and the axial end of the valve core is opened into a conical surface to form a gap flow channel with a unidirectionally increasing width between the valve core and the inner wall of the through hole; and a valve core sleeve is sleeved on the conical surface, so that the valve core sleeve moves along the axial direction of the valve core to achieve filling, compression and sealing of the gap flow channel, or increase the release flow channel gap to achieve opening of the relief valve, so that the unidirectional opening function can be achieved by adjusting the pressure difference on both sides of the relief valve. When the submersible pump is shut down and the pipe is started, the liquid level in the casing annulus outside the oil pipeline can be adjusted to be lower than the oil pressure of the residual oil in the oil pipeline to open the relief valve and discharge the residual oil in the oil pipeline, thereby reducing the safety risk caused by the residual oil impacting the impeller of the submersible pump and improving the safety of operation. At the same time, by applying a stable elastic force to the valve core sleeve through the elastic locking piece, the valve core sleeve can be pushed in the direction of sealing the gap flow channel, thereby maintaining its normally closed locking state and ensuring the reliability of its pressure relief operation; and when pressure relief is required, the elastic locking piece can be deformed to make room for the valve core sleeve to move, open and increase the gap flow channel, and ensure the reliability of the relief valve function.

[0066] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0067] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise" and "counterclockwise" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element 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.

[0068] It should be noted that all directional indications in the embodiments of the present application are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0069] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0070] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0071] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0072] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0073] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. A relief valve, characterized in that: It includes: a housing, a valve core, a valve core sleeve and an elastic locking part; A through hole is provided in the housing, the valve core is arranged in the through hole, and one end of the valve core along the axial direction of the through hole is provided with a conical surface to form a gap flow channel with a unidirectionally increasing width between the valve core and the inner wall of the through hole; The valve core sleeve is arranged in the through hole, and the valve core sleeve can be movably sleeved on the conical surface along the axial direction of the through hole to adjust the width of the gap flow channel; The elastic locking member is connected between the housing and the valve core sleeve to provide a force to fill and press the valve core sleeve into the gap flow channel to reduce the width of the gap flow channel.

2. The relief valve according to claim 1, characterized in that: The valve core is a columnar member, and the axis of the valve core coincides with the central axis of the through hole.

3. The relief valve according to claim 1, characterized in that: The valve core sleeve is a cylindrical member, and the inner wall of the valve core sleeve is configured as an inner conical surface adapted to the conical surface.

4. The relief valve according to claim 3, characterized in that: The outer peripheral surface of the valve core sleeve abuts against the hole wall of the through hole.

5. The relief valve according to claim 4, characterized in that: The elastic locking member includes a coil spring, which is sleeved on the outside of the valve core sleeve, and the first end of the coil spring abuts against a stopper on the outer circumferential surface of the valve core sleeve, and the second end abuts against the shell to apply a force to push the valve core sleeve in the direction of filling and reducing the width of the gap flow channel.

6. The relief valve according to claim 5, characterized in that: An anti-slip frame is provided on the housing, and the anti-slip frame extends into the through hole, and the second end of the coil spring abuts against the anti-slip frame.

7. The relief valve according to claim 5, characterized in that: The valve core sleeve is a sealing rubber part.

8. A pipe string assembly, characterized in that: It comprises a pipe column and a relief valve as claimed in any one of claims 1 to 7, wherein the relief valve is connected to a relief hole opened on a side wall of the pipe column.

9. A pressure relief control method, characterized in that: Applicable to the pipe lifting operation of an electric submersible pump equipped with the pipe string assembly according to claim 8; The pressure relief control method comprises: The height of the annular liquid column between the oil pipeline string and the outer casing string is adjusted so that the hydraulic pressure at the outlet side of the relief valve is lower than the hydraulic pressure inside the oil pipeline string by a magnitude greater than the opening pressure of the relief valve.

10. The pressure relief control method according to claim 9, characterized in that: The opening pressure is the elastic deformation force of the elastic locking member when the spacing width between the valve core sleeve and the conical surface reaches a preset value.

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