Underground plunger gas lift uniflow limiter

Abstract

According to the downhole plunger gas lift uniflow limiter, in the limiter, a throwing-fishing assembly comprises a solid throwing-fishing head arranged at the top and a hollow buffer cylinder located at the bottom, and the inner wall of the bottom of the hollow buffer cylinder extends inwards in an inclined mode to form a fixing head; when the plunger falls to the limiting stopper, the buffer spring retracts, and the solid buffer rod moves and slides upwards in the hollow buffer cylinder to achieve buffering; the annular sealing assembly is hollow, a sealing piece is arranged on the outer wall, a sliding sleeve is arranged on the inner wall, the sliding sleeve shrinks under external force, and the sealing piece is extruded to expand and seal so as to seal an annular space between the limiting stopper and the oil pipe. When the liquid level is lower than a preset value, the sealing assembly is tightly attached to the throat to prevent the liquid from falling back to achieve the effect of the check valve, when the liquid level is higher than the preset value, the elastic structure shrinks, the sealing assembly moves downwards to the diffusion section, a gap is formed between the sealing assembly and the diffusion section, and the liquid falls down from the gap and then flows down through the second liquid inlet and outlet. The limiting stopper can adjust the falling amount of liquid above the limiting stopper.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas production, and in particular to a downhole plunger gas lift single flow limiter. Background Art

[0002] Plunger gas lift is a water-discharge gas production process that utilizes bottom-hole energy for lifting. The plunger, as a gas-liquid solid interface, can effectively reduce gas channeling and liquid slippage and improve liquid lifting efficiency. It has been widely used in oil and gas fields due to its high input-output ratio and high degree of automation.

[0003] The downhole limiter installed at a certain position in the wellbore in the plunger gas lift equipment system plays the role of limiting the plunger position and shock absorption during the plunger gas lift drainage and gas production, and plays a key role in the drainage and gas production effect of the plunger gas lift process.

[0004] The prior art uses a downhole single-flow limiter for plunger gas lift to prevent the liquid above the limiter in the wellbore from falling back to the bottom of the well after the well is shut in, by means of a rubber cylinder and a single-flow valve. This prevents the liquid from falling back to the bottom of the well in the wellbore after the well is shut in, thereby increasing the amount of liquid lifted by the plunger gas lift and the lifting efficiency. However, in some high-water-content gas wells and horizontal wells, there is a lot of liquid in the wellbore when the well is shut in. After the well is shut in, the liquid falls back by gravity. Due to the settings of the rubber cylinder and the single-flow valve, the liquid level above the limiter is too high. When the well is opened for lifting next time, the formation energy cannot lift the plunger and the liquid that is too high above the plunger, resulting in the plunger being unable to move upward or even being flooded and shut down the well.

[0005] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0006] The purpose of the present invention is to provide a downhole plunger gas lift single-flow limiter. Through an adjustable upper liquid volume single-flow valve, when the liquid level above the limiter is too high, the adjustable upper liquid volume single-flow valve will release part of the liquid column, thereby solving the technical problem that the liquid level above the limiter is too high, resulting in the formation energy being unable to lift the plunger, and then the plunger is unable to move upward or even flooded and shut down the well, and the liquid fall amount above the limiter can be adjusted accurately and reliably.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A downhole plunger gas lift single flow limiter of the present invention comprises:

[0009] A fishing assembly, comprising a solid fishing head arranged at the top and a hollow buffer cylinder located at the bottom, wherein the inner wall of the bottom of the hollow buffer cylinder extends inwardly to fix the head;

[0010] A buffer component is connected to the casting and fishing component, and the buffer component includes:

[0011] The solid buffer rod has a lower wedge-shaped spring block at the top thereof which is elastically clamped to the fixed head.

[0012] A buffer spring is sleeved on the solid buffer rod. When the plunger falls to the stopper, the buffer spring retracts, and the solid buffer rod moves upward and slides in the hollow buffer cylinder to achieve buffering;

[0013] A first liquid inlet and outlet cylinder, which is a hollow cylinder with a first liquid inlet and outlet port provided on the cylinder wall, and the first liquid inlet and outlet cylinder is threadedly connected to the solid buffer rod;

[0014] An annular sealing assembly, which is threadedly connected to the bottom of the first inlet and outlet cylinder, is hollow inside and has a sealing member on the outer wall and a sliding sleeve on the inner wall. When subjected to external force, the sliding sleeve contracts and the sealing member is squeezed and expanded to seal the annular space between the stopper and the oil pipe;

[0015] A second liquid inlet and outlet cylinder is a hollow cylinder with a second liquid inlet and outlet port at the lower part of the cylinder wall, the second liquid inlet and outlet cylinder is threadedly connected to the bottom of the annular sealing assembly, and an inverted trapezoidal protrusion is provided on the inner wall of the upper part of the second liquid inlet and outlet cylinder to form a venturi tube structure, the venturi tube structure includes a contraction section with a gradually contracting inner diameter, a throat maintaining a minimum inner diameter, and a diffusion section with a gradually expanding inner diameter, which are connected in sequence;

[0016] An adjustable upper liquid check valve comprising:

[0017] The elastic structure is elastically arranged in the second inlet and outlet cylinder,

[0018] The sealing assembly includes a valve seat elastically supported on the elastic structure and a sealing ball arranged on the valve seat. When the liquid level is lower than a predetermined value, the sealing assembly is tightly attached to the throat to prevent the liquid from falling back to realize the function of a single-flow valve. When the liquid level is higher than the predetermined value, the elastic structure contracts and the sealing assembly moves down to the diffusion section, forming a gap between the sealing assembly and the diffusion section, and the liquid falls from the gap and flows through the second inlet and outlet.

[0019] The downhole plunger gas lift single flow limiter also includes a limit assembly, which includes:

[0020] The positioning member is threadedly connected to the bottom of the second inlet and outlet cylinder, and the bottom of the positioning member is a wide-diameter entity protruding in the width direction.

[0021] A moving part is connected to the positioning part. The moving part is provided with an inner wall protrusion located in the middle, a fixing tooth located at the bottom and an outer hook connecting rod connected to the fixing tooth. When the limiter is lowered, the outer hook connecting rod is cross-forced to tighten the moving part so that it can be smoothly lowered to the specified position. When lifted, the outer hook connecting rod hooks the inner wall of the oil pipe, and the outer hook connecting rod is forced to open so that the moving part opens. When shocked, the moving part moves upward, the inner wall protrusion moves to the wide diameter entity, and the moving part is stretched open so that the fixing tooth is stuck at the oil pipe coupling to complete the sealing.

[0022] In the downhole plunger gas lift single-flow limiter described, the sealing ball is a steel ball, the valve seat is a wide-diameter valve seat with an outer diameter slightly smaller than the throat diameter, and a sealing rubber ring is provided on the outer wall of the wide-diameter valve seat. When there is liquid on the upper part of the adjustable upper liquid volume single-flow valve, the gravity of the liquid pushes the elastic structure to retract. When the liquid level is lower than a predetermined value, the sealing rubber ring is tightly attached to the throat, and the sealing effect of the steel ball and the sealing rubber ring prevents the liquid from falling back to the second inlet and outlet liquid cylinder; when the liquid level is higher than the predetermined value, as the gravity of the liquid further pushes the elastic structure to retract, the sealing rubber ring retreats to the diffusion section, a gap is formed between the sealing assembly and the diffusion section, and the liquid falls from the gap and flows to the bottom of the well through the second inlet and outlet.

[0023] In the downhole plunger gas lift single-flow limiter described, the sealing ball is an elastic sealing ball with steel inside and elastic rubber outside, the valve seat is a narrow-diameter valve seat with an outer diameter smaller than the throat diameter, and the outer diameter of the elastic sealing ball is slightly larger than the throat diameter. When there is liquid on the upper part of the adjustable upper liquid volume single-flow valve, the gravity of the liquid pushes the elastic structure to retract. When the liquid level is lower than a predetermined value, the rubber of the elastic sealing ball is squeezed and expanded to fit tightly against the throat, and the sealing effect of the elastic sealing ball prevents the liquid from falling back into the second inlet and outlet liquid cylinder; when the liquid level is higher than the predetermined value, as the gravity of the liquid further pushes the elastic structure to retract, the elastic sealing ball retreats to the diffusion section, a gap is formed between the sealing assembly and the diffusion section, and the liquid falls through the gap and flows to the bottom of the well through the second inlet and outlet.

[0024] In the downhole plunger gas lift single-flow limiter described, after opening the well or at the end of well closing, when there is a pressure difference between the lower and upper parts of the adjustable upper liquid volume single-flow valve, the formation pressure pushes the formation liquid into the second inlet and outlet liquid cylinder through the second inlet and outlet liquid port, pushes the sealing ball into the first inlet and outlet liquid cylinder, and the formation liquid enters the upper part of the limiter through the first inlet and outlet liquid port. After closing the well, the liquid in the oil pipe falls back and enters the upper compression elastic structure of the adjustable upper liquid volume single-flow valve through the first inlet and outlet liquid port to retract.

[0025] In the downhole plunger gas lift single-flow limiter, the outer wall of the hollow buffer tube is provided with a plurality of straightening blocks for preventing the limiter from tilting during the placement process, and the straightening blocks are arranged equidistantly along the outer wall of the hollow buffer tube.

[0026] In the downhole plunger gas lift single flow limiter, the sealing element is a rubber rubber cylinder.

[0027] In the downhole plunger gas lift single-flow limiter, the elastic structure includes a spring.

[0028] In the downhole plunger gas lift single-flow limiter, a plurality of first liquid inlet and outlet ports are provided, which are arranged equidistantly along the wall of the first liquid inlet and outlet cylinder.

[0029] In the downhole plunger gas lift single-flow limiter, a plurality of second liquid inlet and outlet ports are provided, which are arranged equidistantly along the wall of the second liquid inlet and outlet cylinder.

[0030] In the above technical scheme, the present invention provides a downhole plunger gas lift single-flow limiter, which has the following beneficial effects: the downhole plunger gas lift single-flow limiter can prevent the liquid above the limiter in the wellbore from falling back to the bottom of the well after the well is shut down through the first inlet and outlet liquid cylinder, the annular sealing assembly, the second inlet and outlet liquid cylinder, and the adjustable upper liquid volume single-flow valve, and can effectively control the liquid level above the limiter. Thus, while retaining the function of the single-flow valve, it solves the problem that in high-water-content gas wells, due to the setting of the rubber cylinder and the single-flow valve, the liquid level above the limiter is too high. When the well is opened and lifted next time, the formation energy cannot lift the plunger and the liquid too high above the plunger, resulting in the plunger being unable to move upward or even being flooded and shut down. The technical problem, thereby increasing the plunger gas lift lifting liquid volume and lifting efficiency, and improving the plunger gas lift drainage and gas production effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0032] Figure 1 A schematic structural diagram of a downhole plunger gas lift single flow limiter provided in an embodiment of the present invention.

[0033] Figure 2 A schematic structural diagram of an adjustable upper liquid check valve of a downhole plunger gas lift check valve provided by an embodiment of the present invention.

[0034] Figure 3A schematic diagram of the structure of an adjustable upper liquid check valve of a downhole plunger gas lift single-flow limiter provided in another embodiment of the present invention. Among them: 1-casting assembly, 2-buffer assembly, 3-first inlet and outlet liquid cylinder, 4-annular sealing assembly, 5-second inlet and outlet liquid cylinder, 6-adjustable upper liquid check valve, 7-limit assembly, 8-hollow buffer cylinder, 9-fixed head, 10-righting block, 11-solid buffer rod, 12-buffer spring, 13-lower wedge-shaped spring block, 14-first inlet and outlet, 15-seal, 16-sleeve, 17-inverted trapezoidal protrusion, 18- Contraction section, 19-throat, 20-diffusion section, 21-second liquid inlet and outlet, 22-sealing assembly, 23-elastic structure, 24-sealing ball, 25-valve seat, 26-positioning piece, 27-moving piece, 28-wide diameter entity, 29-inner wall protrusion, 30-locking tooth, 31-external hook connecting rod, 241-steel ball, 242-elastic sealing ball, 251-wide diameter valve seat, 252-sealing rubber ring, 253-narrow diameter valve seat. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] 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, further definition and explanation thereof is not required in subsequent drawings.

[0038] In the description of the present invention, 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", "counterclockwise" and the like 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 invention 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 invention.

[0039] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0040] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In the present invention, 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.

[0042] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0043] See also Figure 1-3 As shown, in one embodiment, a downhole plunger gas lift single flow limiter of the present invention comprises:

[0044] The dredging assembly 1 comprises a solid dredging head arranged at the top and a hollow buffer tube 8 located at the bottom, wherein the inner wall of the bottom of the hollow buffer tube 8 extends inwardly and obliquely to a fixed head 9;

[0045] A buffer component 2 is connected to the casting and fishing component 1, and the buffer component 2 includes:

[0046] The solid buffer rod 11 has a lower wedge-shaped spring block 13 at its top for elastically clamping the fixed head 9.

[0047] A buffer spring 12 is sleeved on the solid buffer rod 11. When the plunger falls to the stopper, the buffer spring 12 retracts, and the solid buffer rod 11 moves upward and slides in the hollow buffer cylinder 8 to achieve buffering;

[0048] A first liquid inlet and outlet cylinder 3, which is a hollow cylinder with a first liquid inlet and outlet port 14 on the cylinder wall, and the first liquid inlet and outlet cylinder 3 is threadedly connected to the physical buffer rod 11;

[0049] An annular sealing component 4 is threadedly connected to the bottom of the first inlet and outlet cylinder 3. The annular sealing component 4 is hollow inside and has a sealing member 15 on the outer wall and a sliding sleeve 16 on the inner wall. When subjected to external force, the sliding sleeve 16 contracts and the sealing member 15 is squeezed and expanded to seal the annular space between the stopper and the oil pipe.

[0050] A second liquid inlet and outlet cylinder 5 is a hollow cylinder with a second liquid inlet and outlet port 21 at the lower part of the cylinder wall, the second liquid inlet and outlet cylinder 5 is threadedly connected to the bottom of the annular sealing assembly 4, and an inverted trapezoidal protrusion 17 is provided on the upper inner wall of the second liquid inlet and outlet cylinder 5 to form a venturi tube structure, and the venturi tube structure includes a contraction section 18 with a gradually contracting inner diameter, a throat 19 with a minimum inner diameter, and a diffusion section 20 with a gradually expanding inner diameter, which are connected in sequence;

[0051] The adjustable upper liquid check valve 6 comprises:

[0052] The elastic structure 23 is elastically arranged in the second liquid inlet and outlet cylinder 5.

[0053] The sealing assembly 22 includes a valve seat 25 elastically supported on the elastic structure 23 and a sealing ball 24 arranged on the valve seat 25. When the liquid level is lower than a predetermined value, the sealing assembly 22 is tightly attached to the throat 19 to prevent the liquid from falling back to realize the function of a one-way valve. When the liquid level is higher than the predetermined value, the elastic structure 23 contracts and the sealing assembly 22 moves down to the diffusion section 20. A gap is formed between the sealing assembly 22 and the diffusion section 20, and the liquid falls from the gap and flows through the second liquid inlet and outlet 21.

[0054] In a preferred embodiment of the downhole plunger gas lift single flow limiter, a limiter assembly 7 is also included, which includes:

[0055] The positioning member 26 is threadedly connected to the bottom of the second inlet and outlet cylinder 5, and the bottom of the positioning member 26 is a wide-diameter entity 28 protruding in the width direction.

[0056] The movable member 27 is connected to the positioning member 26. The movable member 27 is provided with an inner wall protrusion 29 located in the middle, a fixing tooth 30 located at the bottom and an outer hook connecting rod 31 connected to the fixing tooth 30. When the limiter is lowered, the outer hook connecting rod 31 is cross-forced to tighten the movable member 27 so that it can be smoothly lowered to the specified position. When lifted, the outer hook connecting rod 31 hooks the inner wall of the oil pipe, and the outer hook connecting rod 31 is forced to open so that the movable member 27 is opened. When shocked, the movable member 27 moves upward, the inner wall protrusion 29 moves to the wide diameter entity 28, and the movable member 27 is stretched open so that the fixing tooth 30 is stuck at the oil pipe coupling to complete the sealing.

[0057] In a preferred embodiment of the downhole plunger gas lift single-flow limiter, the sealing ball 24 is a steel ball 241, and the valve seat 25 is a wide-diameter valve seat 251 whose outer diameter is slightly smaller than the diameter of the throat 19. The outer wall of the wide-diameter valve seat 251 is provided with a sealing rubber ring 252. When there is liquid on the upper part of the adjustable upper liquid volume single-flow valve 6, the gravity of the liquid pushes the elastic structure 23 to retract. When the liquid level is lower than a predetermined value, the sealing rubber ring 252 is tightly attached to the throat 19. The sealing effect of the steel ball 241 and the sealing rubber ring 252 prevents the liquid from falling back to the second inlet and outlet liquid cylinder 5; when the liquid level is higher than the predetermined value, as the gravity of the liquid further pushes the elastic structure 23 to retract, the sealing rubber ring 252 retreats to the diffuser 20, and a gap is formed between the sealing assembly 22 and the diffuser 20. After the liquid falls from the gap, it flows to the bottom of the well through the second inlet and outlet port 21.

[0058] In a preferred embodiment of the downhole plunger gas lift single-flow limiter, the sealing ball 24 is an elastic sealing ball 242 with steel inside and elastic rubber outside, the valve seat 25 is a narrow-diameter valve seat 253 with an outer diameter smaller than the diameter of the throat 19, and the outer diameter of the elastic sealing ball 242 is slightly larger than the diameter of the throat 19. When there is liquid on the upper part of the adjustable upper liquid volume single-flow valve 6, the gravity of the liquid pushes the elastic structure 23 to retract. When the liquid level is lower than a predetermined value, the rubber of the elastic sealing ball 242 is squeezed and expanded to fit tightly with the throat 19, and the sealing effect of the elastic sealing ball 242 prevents the liquid from falling back to the second inlet and outlet liquid cylinder 5; when the liquid level is higher than the predetermined value, as the gravity of the liquid further pushes the elastic structure 23 to retract, the elastic sealing ball 242 retreats to the diffuser 20, a gap is formed between the sealing assembly 22 and the diffuser 20, and the liquid falls from the gap and flows to the bottom of the well through the second inlet and outlet port 21.

[0059] In a preferred embodiment of the downhole plunger gas lift single-flow limiter, after the well is opened or at the end of the well closing, when there is a pressure difference between the lower and upper parts of the adjustable upper liquid volume single-flow valve 6, the formation pressure pushes the formation liquid into the second inlet and outlet liquid cylinder 5 through the second inlet and outlet liquid port 21, pushes the sealing ball 24 into the first inlet and outlet liquid cylinder 3, and the formation liquid enters the upper part of the limiter through the first inlet and outlet liquid port 14. After the well is closed, the liquid in the oil pipe falls back and enters the upper compression elastic structure of the adjustable upper liquid volume single-flow valve through the first inlet and outlet liquid port 14 to retract.

[0060] In a preferred embodiment of the downhole plunger gas lift single-flow limiter, the outer wall of the hollow buffer tube 8 is provided with a plurality of straightening blocks 10 to prevent the limiter from tilting during the placement process, and the straightening blocks 10 are arranged equidistantly along the outer wall of the hollow buffer tube 8.

[0061] In a preferred embodiment of the downhole plunger gas lift single flow limiter, the sealing element 15 is a rubber rubber cylinder.

[0062] In a preferred embodiment of the downhole plunger gas lift single flow limiter, the elastic structure 23 includes a spring.

[0063] In a preferred embodiment of the downhole plunger gas lift single-flow limiter, a plurality of first liquid inlet and outlet ports 14 are provided, which are arranged equidistantly along the wall of the first liquid inlet and outlet cylinder 3 .

[0064] In a preferred embodiment of the downhole plunger gas lift single-flow limiter, a plurality of second liquid inlet and outlet ports 21 are provided, which are arranged equidistantly along the wall of the second liquid inlet and outlet cylinder 5 .

[0065] In one embodiment, Figure 1 As shown, the downhole plunger gas lift single-flow stopper includes a casting assembly 1, a buffer assembly 2, a first inlet and outlet liquid cylinder 3, an annular sealing assembly 4, a second inlet and outlet liquid cylinder 5, an adjustable upper liquid volume single-flow valve 6 and a stopper assembly 7. The casting assembly 1 is provided with a solid casting head at the top, the lower periphery of the casting head is reduced, the bottom of the casting assembly is a hollow buffer cylinder 8, and the inner wall of the bottom of the hollow buffer cylinder 8 extends out of the fixed head 9 of the lower ramp protrusion. Furthermore, the outer wall of the hollow buffer cylinder 8 is provided with a straightening block 10 to prevent the stopper from tilting during the process of the stopper being released. The straightening blocks are arranged equidistantly along the outer wall, and the number can be multiple, and in this embodiment, there are 3.

[0066] The buffer assembly 2 includes a physical buffer rod 11 and a buffer spring 12 sleeved on the physical buffer rod, wherein the top of the physical buffer rod 11 is provided with a lower wedge-shaped bullet 13, and the bottom of the physical buffer rod 11 has an external thread. During installation, the upper part of the physical buffer rod 11 abuts against the bottom of the hollow buffer tube 8, and the lower wedge-shaped bullet 13 retracts after applying an external force, and the upper part of the physical buffer rod 11 enters the hollow buffer tube 8 and the bullet rebounds and is stuck on the upper end of the fixed head 9. The bottom of the physical buffer rod 11 has an internal thread, which is connected to the first inlet and outlet liquid cylinder 3. When the plunger falls to the stopper, the buffer spring 12 retracts, and the physical buffer rod 11 moves up and slides, thereby playing a buffering role.

[0067] The first liquid inlet and outlet cylinder 3 is hollow inside, with external threads at the top and bottom, connected to the bottom of the solid buffer rod 11 and the top of the annular sealing assembly 4 through the external threads, and the first liquid inlet and outlet cylinder 3 is provided with a first liquid inlet and outlet port 14 on the wall. Further, the first liquid inlet and outlet port 14 is provided with a plurality of ports, which are arranged equidistantly along the wall, and there are two ports in this embodiment.

[0068] The annular sealing assembly 4 is hollow inside, with an internal thread at the top and an external thread at the bottom, connected to the bottom of the first inlet and outlet fluid cylinder 3 through the internal thread, and connected to the top of the second inlet and outlet fluid cylinder 5 through the external thread, and the outer wall of the annular sealing assembly 4 is provided with a sealing member 15, and the inner wall is provided with a sliding sleeve 16. When subjected to external force from top to bottom, the inner wall contracts through the sliding sleeve 16, and the sealing member 15 is squeezed and expanded to seal, thereby sealing the annulus between the stopper and the oil pipe. Preferably, the sealing member 15 is a rubber rubber cylinder, which has the advantages of corrosion resistance, heat resistance, cold resistance, etc., and can adapt to the complex environment downhole.

[0069] The second inlet and outlet cylinder 5 is hollow inside, with an internal thread at the top and an external thread at the bottom, connected to the bottom of the annular sealing assembly 4 through the internal thread, and connected to the top of the limit assembly 7 through the external thread. The upper inner wall of the second inlet and outlet cylinder 5 is provided with an inverted trapezoidal protrusion 17 to form a venturi tube structure, including a contraction section 18, a throat 19 and a diffusion section 20, and the lower part of the second inlet and outlet cylinder 5 is provided with a second liquid inlet and outlet port 21. Further, the second liquid inlet and outlet port 21 is provided with a plurality of them, which are arranged equidistantly along the cylinder wall, and there are two in the present embodiment.

[0070] The adjustable upper liquid volume check valve 6 includes a sealing component 22 and an elastic structure 23. The sealing component 22 is composed of a sealing ball 24 and a valve seat 25. When the upper liquid level is not high, the sealing component 22 is close to the throat 19 to prevent the liquid from falling back, thereby playing the role of a check valve. When the upper liquid level is too high, the elastic structure 23 further contracts, and the sealing component 22 moves down to the diffusion section 20. A gap is formed between the sealing component 22 and the diffusion section 20. After the liquid falls from the gap, it flows to the bottom of the well through the second liquid inlet and outlet.

[0071] Preferably, if Figure 2As shown, the sealing ball 24 is a steel ball 241, and the valve seat 25 is a wide-diameter valve seat 251 whose outer diameter is slightly smaller than the diameter of the throat 19. A sealing rubber ring 252 is provided on the outer wall of the wide-diameter valve seat 251. When there is liquid on the upper part of the adjustable upper liquid volume check valve 6, the gravity of the liquid pushes the elastic structure 23 to retract. When the liquid volume is small, the sealing rubber ring 252 is tightly attached to the throat 19, and the sealing effect of the steel ball 241 and the sealing rubber ring 252 prevents the liquid from falling back to the second inlet and outlet liquid cylinder 5; when the liquid volume is large, after reaching a certain liquid volume, as the gravity of the liquid further pushes the elastic structure 23 to retract, the sealing rubber ring 252 retreats to the diffuser 20, and a gap is formed between the sealing component 22 and the diffuser 20. After the liquid falls from the gap, it flows to the bottom of the well through the second inlet and outlet port 21.

[0072] Preferably, if Figure 3 As shown, the sealing ball 24 is an elastic sealing ball 242 with steel inside and elastic rubber outside, the valve seat 25 is a narrow valve seat 253 with an outer diameter smaller than the diameter of the throat 19, and the outer diameter of the elastic sealing ball 242 is slightly larger than the diameter of the throat 19. When there is liquid on the upper part of the adjustable upper liquid volume check valve 6, the gravity of the liquid pushes the elastic structure 23 to retract. When the liquid volume is small, the rubber of the elastic sealing ball 242 is squeezed and expanded to fit tightly with the throat 19. The sealing effect of the elastic sealing ball 242 prevents the liquid from falling back to the second inlet and outlet liquid cylinder 5; when the liquid volume is large, after reaching a certain liquid volume, as the gravity of the liquid further pushes the elastic structure 23 to retract, the elastic sealing ball 242 retreats to the diffuser 20, a gap is formed between the sealing component 22 and the diffuser 20, and the liquid falls from the gap and flows to the bottom of the well through the second inlet and outlet port 21.

[0073] Preferably, the elastic structure 23 is a spring. Specifically, after the well is opened or at the end of the well closing, when there is a pressure difference between the lower and upper parts of the adjustable upper liquid check valve 6, the formation pressure pushes the formation liquid into the second inlet and outlet liquid cylinder 5 through the second inlet and outlet liquid port 21, pushes the sealing ball 24 into the first inlet and outlet liquid cylinder 3, and the formation liquid enters the upper part of the limiter through the first inlet and outlet liquid port 14. After the well is closed, the liquid in the oil pipe falls back and enters the upper part of the adjustable upper liquid check valve through the first inlet and outlet liquid port 14 to retract the compression spring.

[0074] The limiting assembly includes a positioning member 26 and a moving member 27. The top of the positioning member 26 has an external thread and is connected to the bottom of the second inlet and outlet fluid cylinder 5. The bottom of the positioning member is a wide-diameter entity 28. The moving member 27 has a middle inner wall protrusion 29, a bottom locking tooth 30, and an outer hook connecting rod 31. When the limiter is lowered, the outer hook connecting rod 31 cross-forces and tightens the moving member 27, so that it can be smoothly lowered to the specified position, lifted up, and the outer hook connecting rod 31 hooks the inner wall of the oil pipe. The outer hook connecting rod 31 is forced to open, and the moving member 27 is opened and shaken. The moving member 27 moves up, the inner wall protrusion 29 moves to the wide-diameter entity 28, the moving member 27 is stretched open, and the bottom locking tooth clamp 30 completes the sealing at the oil pipe coupling.

[0075] Finally, it should be noted that the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making any creative work are within the scope of protection of the present application.

[0076] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A downhole plunger gas lift single flow limiter, It is characterized in that These include, A catching assembly, comprising a solid catching head arranged at the top and a hollow buffer cylinder located at the bottom, wherein the inner wall of the bottom of the hollow buffer cylinder extends inwardly and tilts to fix the head; A buffer component is connected to the casting and fishing component, and the buffer component includes: The solid buffer rod has a lower wedge-shaped spring block at the top thereof which is elastically clamped to the fixed head. A buffer spring is sleeved on the solid buffer rod. When the plunger falls to the stopper, the buffer spring retracts, and the solid buffer rod moves upward and slides in the hollow buffer cylinder to achieve buffering; A first liquid inlet and outlet cylinder, which is a hollow cylinder with a first liquid inlet and outlet port provided on the cylinder wall, and the first liquid inlet and outlet cylinder is threadedly connected to the solid buffer rod; An annular sealing assembly, which is threadedly connected to the bottom of the first inlet and outlet cylinder, is hollow inside and has a sealing member on the outer wall and a sliding sleeve on the inner wall. When subjected to external force, the sliding sleeve contracts and the sealing member is squeezed and expanded to seal the annular space between the stopper and the oil pipe; A second liquid inlet and outlet cylinder is a hollow cylinder with a second liquid inlet and outlet port at the lower part of the cylinder wall, the second liquid inlet and outlet cylinder is threadedly connected to the bottom of the annular sealing assembly, and an inverted trapezoidal protrusion is provided on the inner wall of the upper part of the second liquid inlet and outlet cylinder to form a venturi tube structure, the venturi tube structure includes a contraction section with a gradually contracting inner diameter, a throat maintaining a minimum inner diameter, and a diffusion section with a gradually expanding inner diameter, which are connected in sequence; An adjustable upper liquid check valve comprising: The elastic structure is elastically arranged in the second inlet and outlet cylinder, The sealing assembly includes a valve seat elastically supported on the elastic structure and a sealing ball arranged on the valve seat. When the liquid level is lower than a predetermined value, the sealing assembly is tightly attached to the throat to prevent the liquid from falling back to realize the function of a single-flow valve. When the liquid level is higher than the predetermined value, the elastic structure contracts and the sealing assembly moves down to the diffusion section, forming a gap between the sealing assembly and the diffusion section, and the liquid falls from the gap and flows through the second inlet and outlet.

2. A downhole plunger gas lift single flow limiter according to claim 1, It is characterized in that Also included is a limit assembly, which includes, The positioning member is threadedly connected to the bottom of the second inlet and outlet cylinder, and the bottom of the positioning member is a wide-diameter entity protruding in the width direction. A moving part is connected to the positioning part. The moving part is provided with an inner wall protrusion located in the middle, a fixing tooth located at the bottom and an outer hook connecting rod connected to the fixing tooth. When the limiter is lowered, the outer hook connecting rod is cross-forced to tighten the moving part so that it can be smoothly lowered to the specified position. When lifted, the outer hook connecting rod hooks the inner wall of the oil pipe, and the outer hook connecting rod is forced to open so that the moving part opens. When shocked, the moving part moves upward, the inner wall protrusion moves to the wide diameter entity, and the moving part is stretched open so that the fixing tooth is stuck at the oil pipe coupling to complete the sealing.

3. A downhole plunger gas lift single flow limiter according to claim 1, It is characterized in that The sealing ball is a steel ball, and the valve seat is a wide-diameter valve seat with an outer diameter slightly smaller than the throat diameter. A sealing rubber ring is provided on the outer wall of the wide-diameter valve seat. When there is liquid on the upper part of the adjustable upper liquid volume check valve, the gravity of the liquid pushes the elastic structure to retract. When the liquid level is lower than a predetermined value, the sealing rubber ring is tightly attached to the throat, and the sealing effect of the steel ball and the sealing rubber ring prevents the liquid from falling back to the second inlet and outlet liquid cylinder; when the liquid level is higher than the predetermined value, as the gravity of the liquid further pushes the elastic structure to retract, the sealing rubber ring retreats to the diffusion section, a gap is formed between the sealing assembly and the diffusion section, and the liquid falls from the gap and flows to the bottom of the well through the second inlet and outlet.

4. A downhole plunger gas lift single flow limiter according to claim 1, It is characterized in that The sealing ball is an elastic sealing ball with steel inside and elastic rubber outside. The valve seat is a narrow-diameter valve seat with an outer diameter smaller than the throat diameter. The outer diameter of the elastic sealing ball is slightly larger than the throat diameter. When there is liquid on the upper part of the adjustable upper liquid volume check valve, the gravity of the liquid pushes the elastic structure to retract. When the liquid level is lower than a predetermined value, the rubber of the elastic sealing ball is squeezed and expanded to fit tightly against the throat, and the sealing effect of the elastic sealing ball prevents the liquid from falling back into the second inlet and outlet liquid cylinder; when the liquid level is higher than the predetermined value, as the gravity of the liquid further pushes the elastic structure to retract, the elastic sealing ball retreats to the diffusion section, a gap is formed between the sealing assembly and the diffusion section, and the liquid falls through the gap and flows to the bottom of the well through the second inlet and outlet.

5. A downhole plunger gas lift single flow limiter according to claim 1, It is characterized in that After the well is opened or at the end of the well closing, when there is a pressure difference between the lower and upper parts of the adjustable upper liquid volume check valve, the formation pressure pushes the formation liquid into the second inlet and outlet liquid cylinder through the second inlet and outlet liquid port, pushes the sealing ball into the first inlet and outlet liquid cylinder, and the formation liquid enters the upper part of the limiter through the first inlet and outlet liquid port. After the well is closed, the liquid in the oil pipe falls back and enters the upper compression elastic structure of the adjustable upper liquid volume check valve through the first inlet and outlet liquid port to retract.

6. A downhole plunger gas lift single flow limiter according to claim 1, It is characterized in that The outer wall of the hollow buffer cylinder is provided with a plurality of straightening blocks for preventing the limiter from tilting during the placement process, and the straightening blocks are arranged at equal distances along the outer wall of the hollow buffer cylinder.

7. A downhole plunger gas lift single flow limiter according to claim 1, It is characterized in that The sealing element is a rubber cylinder.

8. A downhole plunger gas lift single flow limiter according to claim 1, It is characterized in that The elastic structure includes a spring.

9. A downhole plunger gas lift single flow limiter according to claim 1, It is characterized in that There are multiple first liquid inlet and outlet ports, which are arranged equidistantly along the wall of the first liquid inlet and outlet cylinder.

10. A downhole plunger gas lift single flow limiter according to claim 1, It is characterized in that The second liquid inlet and outlet are provided with a plurality of ports, which are arranged equidistantly along the cylinder wall of the second liquid inlet and outlet cylinder.

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