Natural gas downhole throttler with self-compensation sealing structure

Abstract

The invention relates to the technical field of underground throttlers, in particular to a natural gas underground throttler with a self-compensation sealing structure, which comprises a throttler body and a first spring, the first spring is connected in the throttler body, two ends of the first spring are respectively connected with a connecting ring, the outer side of the throttler body is connected with a protective cover, and the protective cover is connected with a sealing ring. And a compensation assembly is arranged in the protective cover. Efficient sealing and pressure regulation and control are achieved through the multiple sets of symmetrically-arranged compensation assemblies, and a spring-sliding block-connecting rod force transmission chain is formed on a structure cooperation mechanism; the multi-stage compensation technology has the remarkable advantages, multiple sets of assemblies are symmetrically distributed in the circumferential direction to synergistically generate force, graded stacked compensation force is formed, underground pressure fluctuation and sealing face abrasion can be dynamically adapted, the uniformity and long-term stability of sealing pressure are greatly improved, and the sealing requirement under the complex working condition is effectively met.

Description

Technical Field

[0001] This invention relates to the field of downhole choke technology, specifically a natural gas downhole choke with a self-compensating sealing structure. Background Technology

[0002] To adapt to the development of various oilfields and based on the well conditions of different blocks within each oilfield, downhole choke technology has been researched and developed as a new technology, resulting in a wide variety of downhole chokes. Downhole chokes can be broadly classified into two types: movable and fixed. Movable downhole chokes can be run into any well section as needed, with adjustable setting positions, making deployment and retrieval convenient and reliable, especially suitable for older wells requiring choke control. Fixed downhole chokes are deployed to positions determined by the downhole working cylinder. They have higher pressure differential resistance, better sealing performance, and simpler and more reliable deployment and retrieval operations, making them suitable for use in newly commissioned wells. Self-compensating sealing structures are key components in industrial equipment such as natural gas downhole chokes, automatically adjusting the sealing force to adapt to temperature, pressure changes, or component wear. Self-compensating sealing structures achieve automatic adjustment of the sealing force through elastic elements (such as springs or rubber sealing rings) or pressure balancing mechanisms, realizing a two-stage rubber sleeve seal achieved through springs and airflow pressure differential.

[0003] A search revealed patent application number (201410528057.9), which discloses "a downhole choke," belonging to the field of oilfield natural gas extraction technology. The downhole choke includes a first central rod, a second central rod, and a release head, a body, and a guide head connected in sequence. The choke also includes a retaining ring, an elastic slip structure, and an upper seal, a lower skeleton, a lower seal, a sealing activation block, a spring, and a limiting block, sequentially arranged between the wedge-shaped protrusion and the other end of the body. The second central rod has a first protrusion and a second protrusion arranged sequentially along the direction from the release head to the guide head. The sealing activation block and the body have corresponding first through holes opposite to the first protrusion, and the limiting block and the body have corresponding second through holes opposite to the second protrusion. Limiting components are placed in the first and second through holes respectively. The downhole choke provided by this invention can be easily retrieved from the well.

[0004] However, the above-mentioned device has the following problems: The spring self-compensating sealing structure is the most common form of self-compensating sealing. When the spring is compressed, it generates an outward radial force, which pushes the sealing element (such as the sealing lip of the polymer jacket) to press tightly against the sealing surface to form an initial seal. Under high pressure and high temperature conditions for a long time, the elastic element such as the spring is prone to stress relaxation or plastic deformation, which leads to a decrease in compensation capacity. To address this problem, we propose a natural gas downhole throttle with a self-compensating sealing structure. Summary of the Invention

[0005] The purpose of this invention is to provide a natural gas well throttle with a self-compensating sealing structure to solve the problem mentioned in the background art that single elastic elements, such as springs, are prone to stress relaxation or plastic deformation under long-term high pressure and high temperature conditions, resulting in a decrease in compensation capacity.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a natural gas well downhole throttle with a self-compensating sealing structure, comprising a throttle body and a first spring, wherein the first spring is connected inside the throttle body, and connecting rings are respectively connected to both ends of the first spring; a protective cover is connected to the outside of the throttle body, and a compensation component is provided inside the protective cover.

[0007] The compensation component consists of a movable groove, a slider, a second spring, a connector, and a connecting rod. The protective cover has a movable groove inside, a slider is installed inside the movable groove, a second spring is installed outside the slider, a connector is connected to the outside of the connecting ring, a connecting rod is installed inside the connector, and an adjustment component is installed inside the movable groove.

[0008] Preferably, a threaded rod is fixedly connected inside the movable groove, and a hole adapted to the threaded rod is opened inside the slider.

[0009] Preferably, the adjusting assembly includes a threaded rod and a nut, the outer surface of the threaded rod is movably connected to the nut, the inner wall of the nut is provided with a thread that matches the surface of the threaded rod, and the two ends of the second spring abut against the nut and the slider, respectively.

[0010] Preferably, the slider is slidably connected inside the movable groove, a damper is connected inside the second spring, one end of the connecting rod is rotatably connected to the slider, and the other end of the connecting rod is rotatably connected to the connecting piece.

[0011] Preferably, the protective cover is in four sets and is semi-circular. The outer surface of the protective cover has multiple sets of connection holes, and bolts are connected inside the connection holes.

[0012] Preferably, the protective cover has multiple sets of compensation components inside, and each set of compensation components is symmetrical to each other.

[0013] Preferably, the outer surface of the threaded rod is provided with two sets of nuts, and the thickness of the two sets of nuts differs by a factor of two.

[0014] Preferably, a knob is fixedly connected to the outer surface of the nut, and the outer surface of the knob is provided with anti-slip texture.

[0015] Compared with the prior art, the beneficial effects of the present invention are:

[0016] 1. This invention achieves efficient sealing and pressure regulation through multiple symmetrically arranged compensation components. In terms of structural coordination mechanism, each compensation component relies on the rotational cooperation of the slider, second spring, and connecting rod within the movable groove with the connecting member on the outside of the connecting ring to form a force transmission chain of "spring-slider-connecting rod". The force transmission path is that the elastic force of the second spring pushes the slider to slide radially along the movable groove, which is then transmitted through the rotation of the connecting rod and converted into a thrust on the connecting member, ultimately acting on the connecting ring to generate a radial sealing force. The multi-level compensation technology has significant advantages. Multiple components are symmetrically distributed in the circumferential direction to exert force in coordination, forming a graded superimposed compensation force, which can dynamically adapt to downhole pressure fluctuations and sealing surface wear, greatly improving the uniformity and long-term stability of the sealing pressure, and effectively meeting the sealing requirements under complex working conditions.

[0017] 2. This invention achieves precise control of sealing pressure through an adjustment component, including a threaded rod, two sets of nuts with a thickness difference of twice, and a knob with anti-slip texture. Rotating the knob moves the nut axially along the threaded rod, changing the distance between the nut and the slider to adjust the compression of the second spring, thereby precisely setting the preload of each set of second springs. In terms of operation, the knob can be manually rotated and adjusted using the anti-slip texture on its outer surface, without the need for special tools, making it convenient and efficient. In terms of technical advantages, the two sets of nuts are tightened against each other to form an anti-loosening structure. The pressure between the threaded pairs counteracts external forces to prevent parameter drift. Combined with the buffering effect of the damper, the pressure distribution is more in line with the sealing requirements of complex working conditions such as high pressure and vibration in downhole operations, significantly improving the accuracy and long-term stability of pressure control. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a front view schematic diagram of the structure of the present invention;

[0020] Figure 2 For the present invention Figure 1 Schematic diagram of the structure of the throttle body;

[0021] Figure 3 For the present invention Figure 1 A schematic cross-sectional view of the structure of the protective shield;

[0022] Figure 4 For the present invention Figure 1 Schematic diagram of the structure of the protective shield;

[0023] Figure 5 For the present invention Figure 3 A magnified view of part A in the diagram;

[0024] Figure 6 For the present invention Figure 3 A magnified view of part B in the diagram.

[0025] In the diagram: 1. Throttling device body; 2. First spring; 3. Connecting ring; 4. Protective cover; 5. Compensation component; 501. Movable groove; 502. Slider; 503. Second spring; 504. Connecting piece; 505. Connecting rod; 6. Adjusting component; 601. Threaded rod; 602. Knob; 603. Nut; 7. Connecting hole; 8. Bolt. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Please see Figure 1-6 One embodiment of the present invention provides a natural gas well downhole choke with a self-compensating sealing structure, comprising a choke body 1 and a first spring 2. The first spring 2 is coaxially mounted inside the choke body 1. The two ends of the first spring 2 are respectively connected to connecting rings 3 through a detachable snap-fit ​​structure that engages with a flange via annular grooves. The connecting rings are made of wear-resistant rubber wrapped around a metal skeleton structure, used to stably support the sealing element and uniformly transmit radial sealing force. Four sets of semi-circular protective covers 4 made of high-strength alloy steel are fixedly connected to the outside of the choke body 1 by high-strength bolts 8. The protective covers 4 have the dual functions of isolating downhole impurities and protecting internal components and precisely installing compensation components 5. The compensation components 5 are symmetrically arranged inside the protective covers 4. The compensation components 5 consist of a movable groove 501, a slider 502, and a second spring. The system comprises a spring 503, a connector 504, and a connecting rod 505. The inner wall of the protective cover 4 has a radially movable groove 501 to guide the slider 502 to slide radially in a directional manner. The groove 501 and the slider 502 are precisely fitted with a clearance. The outer side of the slider 502 abuts against the second spring 503, providing continuous dynamic sealing compensation force for the sealing system. The outer side of the connecting ring 3 is symmetrically welded with a connector 504. The connector 504 and one end of the connecting rod 505 are rotatably connected via a stainless steel pin. The other end of the connecting rod 505 is rotatably connected to the slider 502, achieving efficient directional conversion from radial force to sealing thrust. The groove 501 also contains an adjustment assembly 6 consisting of a threaded rod 601, an adjustment knob 602, and a locking nut 603, used to precisely adjust the preload of the second spring.

[0028] This device, through the symmetrical distribution of four sets of compensation components 5 along the circumference of the throttle body, solves the problem that single elastic elements, such as springs, are prone to stress relaxation or plastic deformation under long-term high-pressure and high-temperature conditions, leading to a decrease in compensation capacity. The multi-component collaborative design can respond in real time to downhole pressure fluctuations and sealing surface wear. Through the linkage mechanism between the slider 502 and the connecting rod 505, the elastic force of the second spring 503 is evenly transmitted to the connecting ring 3, forming a stable dynamic compensation sealing force. This effectively avoids the risk of sealing failure caused by fatigue failure of a single spring, and significantly improves the sealing reliability and service life of the throttle in complex downhole environments.

[0029] Furthermore, a threaded rod 601 (with a galvanized anti-rust treatment) is welded to the inside of the movable groove 501. The slider 502 has an H7 / g6 precision clearance fit hole adapted to the threaded rod 601. A second spring 503 (made of 304 stainless steel) is sleeved on the outside of the threaded rod 601, with its two ends abutting against the end face of the slider 502 and the nut 603 of the adjusting assembly, respectively. Figure 4 and Figure 5 As shown, the core functions of this structure are as follows: Structurally, the threaded rod 601 serves as the core guiding element, limiting the movement trajectory of the slider 502 to the axial direction, while the second spring 503 relies on the threaded rod to achieve uniform force distribution; in terms of the guiding mechanism, the slider 502 slides along the axial direction of the threaded rod 601 through the hole, and the cylindrical surface of the threaded rod 601 strictly restricts the radial displacement of the slider 502, avoiding deviation caused by downhole vibration and ensuring accurate movement trajectory; in terms of stability enhancement, the threaded rod 601 eliminates the unnecessary degrees of freedom of the slider 502, allowing the elastic force of the second spring 503 to act evenly on the slider 502, reducing local wear, while the clearance fit ensures smooth movement.

[0030] Furthermore, the adjusting component 6 includes a threaded rod 601 and a nut 603. The nut 603 is movably connected to the outer surface of the threaded rod 601. The threaded rod 601 is axially engraved with scale lines with an accuracy of 0.5mm. Each scale line corresponds to a preset preload value of the second spring 503, such as scale 1 corresponding to 50N, scale 2 corresponding to 100N, etc. The inner wall of the movable groove 501 is synchronously marked with force reference values. The inner wall of the nut 603 is provided with threads adapted to the threaded rod 601. The two ends of the second spring 503 respectively abut against the end face of the slider 502 and the main nut 603. Figure 6 As shown, the core mechanism of this structure is as follows: the adjustment principle is that rotating the knob 602 drives the nut 603 to move axially along the threaded rod 601, changing the distance between the nut 603 and the slider 502 to adjust the compression of the second spring 503; the scale marking system realizes visual and precise adjustment, and the operator can quickly locate the target preload through the scale.

[0031] Furthermore, the slider 502 is slidably connected inside the movable groove 501. The inner wall of the movable groove 501 is coated with a wear-resistant coating and has a guide groove. Wear-resistant strips are embedded on both sides of the slider 502 to match the guide groove, ensuring accurate sliding trajectory without deviation. A miniature hydraulic damper is coaxially installed inside the second spring 503. The damper cylinder is connected to the fixed end of the spring, and the piston rod is hinged to the slider 502, which can suppress high-frequency vibration of the spring and buffer the impact of sudden changes in downhole pressure. The two ends of the connecting rod 505 are rotatably connected to the slider 502 and the connecting piece 504 respectively through stainless steel pins. The surface of the pins is carburized to improve wear resistance. Figure 5 As shown, the core mechanism of this structure is as follows: the slider 502 slides smoothly in the radial direction under the guidance of the movable groove 501, the elastic force of the second spring 503 is buffered by the damper and pushes the slider, the connecting rod 505 converts the radial displacement of the slider into the axial thrust on the connecting piece 504, and finally transmits it to the connecting ring 3 to realize the dynamic compensation of the sealing surface. The cooperation of multiple components ensures that the sealing force is uniform and the response is rapid.

[0032] Furthermore, the protective cover 4 is made of four sets of 5mm thick semi-circular 316L stainless steel plates. These four sets are spliced ​​together to form a complete annular structure with a diameter matching the throttle body. The outer surface is coated with an anti-corrosion coating. The mating end face of the protective cover 4 has a connection hole 7, pre-installed with a nitrile rubber O-ring for sealing. The connection hole 7 is secured with an M8 internal hexagonal head bolt 8, made of high-strength alloy steel and galvanized and passivated. Figure 3 As shown, the installation process of this structure is as follows: align and splice the four sets of semi-circular protective covers along the outer side of the throttle body 1, ensuring that the connecting holes 7 are coaxial; insert O-rings into the connecting holes 7 and then insert bolts 8; gradually tighten the bolts 8 to the preset torque using a diagonal symmetrical pre-tightening method; finally, check that the gap between the protective covers is ≤0.1mm to ensure assembly accuracy. Its maintenance characteristics are as follows: disassembly only requires reverse operation to quickly separate each set of protective covers 4, facilitating the inspection or replacement of internal compensation components during downhole operations; all connecting parts adopt standardized design, are highly versatile, and reduce maintenance costs; the combination of anti-corrosion coating and stainless steel material can effectively resist the erosion of corrosive media such as hydrogen sulfide downhole, extending service life.

[0033] Furthermore, the interior of the protective cover 4 is equipped with eight sets of compensation components 5, all of which are evenly distributed along the circumference of the inner wall of the protective cover 4, forming a completely symmetrical spatial layout. For example... Figure 4As shown, this structure achieves a multi-level compensation mechanism through multiple sets of compensation components 5: in the initial sealing stage, the outer four sets of components provide basic compensation force. When downhole pressure fluctuates or the sealing surface experiences slight wear, the inner four sets of components gradually intervene to supplement the compensation force, forming a dynamic compensation system with graded response. Its pressure distribution optimization principle is that the symmetrically distributed components work together from the circumferential direction to make the sealing pressure evenly act on all parts of the connecting ring 3, avoiding sealing failure caused by local stress concentration. The multi-level compensation mechanism can dynamically adjust the magnitude of the compensation force according to changes in working conditions, achieving more precise pressure distribution and significantly improving the adaptability and stability of the sealing system.

[0034] Furthermore, two sets of nuts 603 are provided on the outer surface of the threaded rod 601, with a thickness difference of twice. The two sets of nuts 603 are tightened against each other to form an anti-loosening structure. The pressure from the threaded pair counteracts external forces, and combined with the quantitative reference of the scale lines, this ensures long-term stability of the preload, preventing loosening caused by downhole vibration and effectively controlling the accuracy and consistency of the sealing pressure. Figure 6 As shown, this structure is used for fasteners that prevent loosening by generating additional friction through the tightening of two nuts 603 against each other. It is suitable for smooth, low-speed and heavy-load connections. Its core principle is to use the pressure between the threaded pairs to counteract external forces and keep the anti-loosening resistance torque constant.

[0035] Furthermore, a knob 602 is fixedly connected to the outer surface of the nut 603. The knob 602 is made of high-strength aluminum alloy, is circular in shape, and has raised anti-slip edges. Its outer surface is covered with diamond-shaped anti-slip patterns, 0.8mm deep and 2mm apart, covering the entire outer surface of the knob. The anti-slip patterns are machined using precision milling technology, which effectively improves friction during operation. Figure 6 As shown, the operating mechanism of this structure is as follows: the operator rotates the knob 602 by holding it. The anti-slip texture increases the contact friction between the hand and the knob, preventing slippage even when operating with gloves in a wet or oily environment downhole. This precisely drives the nut 603 to rotate along the threaded rod 601. Its anti-loosening synergy is reflected in the fact that the anti-slip texture design ensures that the force applied when rotating the nut 603 is uniform and stable, preventing the nut 603 from not rotating properly or becoming loose due to slippage. It works synergistically with the anti-loosening structure of the nut 603, which not only facilitates precise adjustment during operation but also maintains the stability of the position of the nut 603 after adjustment, preventing loosening caused by factors such as downhole vibration, and ensuring the long-term stability of the preload of the second spring 503.

[0036] Working principle: When using, such as Figure 2 and Figure 5As shown, the first spring 2, when compressed, generates an outward radial force, driving the connecting ring 3 to push the seal tightly against the sealing surface, forming an initial seal. This lays the foundation for subsequent dynamic compensation and effectively blocks the initial leakage of downhole fluid. At this time, the second spring 503, under elastic action, pushes the slider 502 outward along the movable groove 501. Through the rotational connection of the connecting rod 505, the force is transmitted to the connecting ring 3, applying a uniform radial thrust to the connecting ring 3. This further enhances the tightness of the seal between the seal and the sealing surface, forming a dynamic compensation force. This force can offset the sealing gap caused by downhole pressure fluctuations or slight wear of the sealing surface in real time, maintaining a stable sealing state. Figure 3 and Figure 6 As shown, when adjusting the sealing force, first remove the bolt 8 from the connecting hole 7 to release the fixing constraint of the protective cover 4. Then, hold the knob 602 and rotate the nut 603. With the threaded engagement between the nut 603 and the threaded rod 601, adjust the axial position of the nut 603 on the threaded rod 601, changing the pre-compression amount and range of motion of the second spring 503. At the same time, rotate another set of knobs 602 to rotate the nut 603, making it fit against the first set of nuts 603, thereby precisely adjusting the magnitude of the sealing compensation force to adapt to the sealing requirements of different downhole pressure conditions. The above is the complete working principle of this invention.

[0037] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A natural gas wellbore choke with a self-compensating sealing structure, comprising a choke body (1) and a first spring (2), characterized in that: The throttle body (1) is internally connected to a first spring (2), and the two ends of the first spring (2) are respectively connected to connecting rings (3). The outside of the throttle body (1) is connected to a protective cover (4), and a compensation component (5) is provided inside the protective cover (4). The compensation component (5) consists of a movable groove (501), a slider (502), a second spring (503), a connector (504), and a connecting rod (505). The protective cover (4) has a movable groove (501) inside. The movable groove (501) is provided inside the movable groove (501). The slider (502) is provided inside the movable groove (501). The second spring (503) is provided outside the slider (502). The connector (504) is connected to the outside of the connecting ring (3). The connecting rod (505) is provided inside the connector (504). The movable groove (501) has an adjustment component (6) inside.

2. A natural gas wellbore throttle with a self-compensating sealing structure according to claim 1, characterized in that: The movable groove (501) is fixedly connected to a threaded rod (601), and the slider (502) has a hole inside that matches the threaded rod (601).

3. A natural gas wellbore throttle with a self-compensating sealing structure according to claim 2, characterized in that: The adjusting component (6) includes a threaded rod (601) and a nut (603). The nut (603) is movably connected to the outer surface of the threaded rod (601). The inner wall of the nut (603) is provided with a thread that matches the surface of the threaded rod (601). The two ends of the second spring (503) abut against the nut (603) and the slider (502) respectively.

4. A natural gas wellbore throttle with a self-compensating sealing structure according to claim 1, characterized in that: The slider (502) is slidably connected inside the movable groove (501), and a damper is connected inside the second spring (503). One end of the connecting rod (505) is rotatably connected to the slider (502), and the other end of the connecting rod (505) is rotatably connected to the connector (504).

5. A natural gas wellbore throttle with a self-compensating sealing structure according to claim 1, characterized in that: The protective cover (4) consists of four sets and is semi-circular. Multiple sets of connecting holes (7) are opened on the outer surface of the protective cover (4), and bolts (8) are connected inside the connecting holes (7).

6. A natural gas wellbore throttle with a self-compensating sealing structure according to claim 1, characterized in that: The protective cover (4) is provided with multiple sets of compensation components (5), and each set of compensation components (5) is symmetrical to each other.

7. A natural gas wellbore choke with a self-compensating sealing structure according to claim 3, characterized in that: The outer surface of the threaded rod (601) is provided with two sets of nuts (603), and the thickness of the two sets of nuts (603) differs by a factor of two.

8. A natural gas wellbore throttle with a self-compensating sealing structure according to claim 3, characterized in that: A knob (602) is fixedly connected to the outer surface of the nut (603), and the outer surface of the knob (602) is provided with anti-slip texture.

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