A sucker rod dynamic sealing device

Abstract

The present application relates to oil and gas field development downhole tool technical field, specifically to a sucker rod dynamic sealing device, including from top to bottom sequentially arranged upper joint, upper centralizing sleeve, center tube, lower centralizing sleeve and lower joint, the center tube is provided with several sealing assemblies for sealing coiled tubing, the inner wall of the upper centralizing sleeve and the inner wall of the lower centralizing sleeve are provided with several centralizing assemblies for centralizing coiled tubing;The sealing assembly includes rubber tube with triangular cross section, the inner wall of the rubber tube is a sharp end, the rubber tube is symmetrically provided with a retainer ring on both sides;The centralizing assembly includes a pressure ring and a buckle ring symmetrically arranged on both sides of the pressure ring, the cross section of the pressure ring is a shape with a bulge in the middle.The present application ensures that the centralizing assembly can effectively centralize the coiled tubing, and also enables the triangular sealing ring to have good sealing performance.And it can adapt to 150 DEG C high temperature environment, and 70 MPa high pressure environment, long service life.

Description

Technical Field

[0001] This invention relates to the field of downhole tools technology for oil and gas field development, and specifically to a dynamic sealing device for sucker rods. Background Technology

[0002] Currently, coiled tubing technology is increasingly used in oil and gas well production. Coiled tubing completion effectively avoids leakage problems caused by corrosion at threaded connections. It is also convenient to install, highly automated, and allows for stratified extraction, significantly shortening operation time and reducing operating costs. However, during the running-in of coiled tubing, the sealing rings of the dynamic sealing device are prone to flipping and falling off, causing seal failure. Furthermore, it requires a high degree of surface smoothness for the sealing surface and cannot achieve subsequent insertion, among other issues.

[0003] Patent CN107989569B discloses a dynamic sealing device for coiled tubing. The technical solution involves connecting a lower sealing and scraping structure to an upper straightening structure via a limiting support plate and connecting bolts. The inner cavity of the limiting support plate serves as a sealing cylinder. A sealing base sleeve, a sealing rubber core, and a replaceable rubber gasket are added to the inner cavity of the sealing cylinder. The sealing rubber core is installed within the inner cavity of the sealing base sleeve, thereby opening or closing the limiting support plate and allowing for replacement of the sealing base sleeve, sealing rubber core, or replaceable rubber gasket within the sealing cylinder. The beneficial effects are: by adding multiple sets of positioning and straightening steel balls, the coiled tubing is straightened and friction is reduced; by installing replaceable sealing base sleeves, sealing rubber cores, and replaceable rubber gaskets within the sealing cylinder, dynamic sealing of the coiled tubing is achieved, and replacement of the corresponding seals is convenient. Furthermore, the addition of a scraping device improves the dynamic sealing effect, extends the service life of the coiled tubing, and prevents wellhead leakage accidents. However, this sealing device exerts significant friction on the coiled tubing, making insertion of the coiled tubing difficult.

[0004] Patent CN213743337U also discloses a dynamic sealing device for continuous tubing. A long rubber sleeve is fitted onto the outer wall of the continuous tubing, with an annular space between the outer wall of the long rubber sleeve and the inner wall of the outer sleeve. The upper end of the annular space can be connected to liquid, while the lower end is sealed, causing the flowing liquid to remain stationary. When the triangular seal fails, the inner wall of the long rubber sleeve comes into contact with the high-speed flowing liquid, creating a pressure difference with the stationary liquid in the annular space. This pressure difference pushes the long rubber sleeve radially inward, gripping the outer wall of the continuous tubing. This invention creates a pressure difference between the inner and outer walls of the long rubber sleeve, allowing it to retract and grip the continuous tubing even if the initial rubber sleeve seal fails, forming a second seal and effectively ensuring normal operation. However, after gripping the continuous tubing, it is difficult to pull it out, making subsequent operations challenging.

[0005] Therefore, there is an urgent need to provide a dynamic sealing device for sucker rods that is simple to operate and has good sealing performance. Summary of the Invention

[0006] To address the aforementioned problems, the present invention provides a dynamic sealing device for sucker rods.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] A dynamic sealing device for a sucker rod includes an upper connector, an upper centralizing sleeve, a central cylinder, a lower centralizing sleeve, and a lower connector arranged sequentially from top to bottom. The central cylinder is provided with a plurality of sealing components for sealing the coiled tubing. The inner walls of the upper centralizing sleeve and the lower centralizing sleeve are each provided with a plurality of centralizing components for centralizing the coiled tubing.

[0009] The sealing assembly includes a rubber tube with a triangular cross-section, the inner wall of the rubber tube being pointed, and protective rings symmetrically arranged on both sides of the rubber tube, the protective rings on both sides cooperating with the rubber tube to form a cylinder; the inner diameter of the rubber tube is smaller than the inner diameter of the protective rings;

[0010] The straightening component includes a pressure ring and buckles symmetrically arranged on both sides of the pressure ring. The cross-section of the pressure ring is bulging in the middle, and the pressure ring and the two buckles cooperate to form a cylinder.

[0011] The inner diameter of the rubber sleeve is 0.3mm-1mm smaller than the outer diameter of the continuous tubing; the inner diameter of the pressure ring is 0.1mm-0.5mm larger than the outer diameter of the continuous tubing.

[0012] Furthermore, the sealing assembly also includes a spacer ring disposed between the rubber sleeve and the central cylinder; the spacer ring is L-shaped, and the rubber sleeve and the retaining ring are embedded in the spacer ring, with the rubber sleeve, the retaining ring and the spacer ring forming a cylindrical structure.

[0013] Furthermore, a first groove is provided on the outer wall of the spacer ring, and a first sealing ring is provided in the first groove.

[0014] Furthermore, the central cylinder is symmetrically provided with spacer ring grooves on both sides, and the spacer rings are embedded in the spacer ring grooves. The spacer rings are arranged in an L-shaped upward direction in the upper spacer ring groove, and the spacer rings are arranged in an L-shaped downward direction in the lower spacer ring groove.

[0015] Furthermore, the upper connector is embedded in the upper straightening sleeve below, and the upper connector and the upper straightening sleeve are connected by a shear pin. A second groove is provided on the outer wall of the upper connector embedded in the upper straightening sleeve, and a second sealing ring is provided in the second groove.

[0016] Furthermore, the lower connector is embedded in the lower straightening sleeve, and the lower connector and the lower straightening sleeve are connected by a shear pin. A third groove is provided on the outer wall of the lower connector embedded in the lower straightening sleeve, and a third sealing ring is provided in the third groove.

[0017] Furthermore, the upper straightening sleeve is embedded in the upper end of the central cylinder at its lower end, and the upper straightening sleeve and the central cylinder are connected by shear pins; the lower straightening sleeve is embedded in the lower end of the central cylinder at its upper end, and the lower straightening sleeve and the central cylinder are connected by shear pins.

[0018] Furthermore, a first straightening groove is provided above the upper straightening sleeve, and the straightening component is disposed in the first straightening groove; a second straightening groove is provided below the lower straightening sleeve, and the straightening component is disposed in the second straightening groove.

[0019] Furthermore, both the pressure ring and the retaining ring are made of PEEK material.

[0020] Furthermore, the number of sealing components is 12 sets, with 6 sets on each side of the central cylinder; the number of straightening components is 8 sets, with 4 sets inside the upper straightening sleeve and the lower straightening sleeve.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. This invention, by setting a triangular seal and a bulging-type centralizing component, and defining the size relationship between the inner diameter of the triangular sealing ring, the inner diameter of the centralizing pressure ring, and the outer diameter of the coiled tubing, ensures that the centralizing component can effectively centralize the coiled tubing and that the triangular sealing ring has good sealing performance. Furthermore, the triangular sealing sleeve reduces the contact area between the sleeve and the coiled tubing, providing better sealing performance while reducing the frictional resistance of the coiled tubing. Since the tip of the triangular sealing sleeve faces the coiled tubing, the size requirements for the inner wall of the sleeve are relaxed, increasing the process design space for the inner wall of the sleeve.

[0023] 2. In this invention, the straightening component is set as a middle pressure ring and two side buckles. The pressure ring has a bulging structure, which ensures that the pressure ring has high strength and good support. Furthermore, the pressure ring and the two side buckles have arc-shaped surface contact, and the contact between the two is equivalent to a ball bearing, which can adapt to the angle change of the sucker rod and play a role in fine-tuning the angle, which is beneficial to the straightening of the sucker rod.

[0024] 3. This invention is easy to install, does not seize up, and can adapt to high temperature environments of 150℃ and high pressure environments of 70MPa, with a long service life. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the present invention.

[0026] Figure 2 This is a schematic diagram of the sealing assembly described in this invention.

[0027] Figure 3 This is a schematic diagram of the structure of the straightening component described in this invention.

[0028] Figure 4 This is a graph showing the pressure-bearing data of the present invention at room temperature.

[0029] Figure 5 This is a graph showing the pressure data of the present invention after 150 meters of wear at room temperature.

[0030] Figure 6 This is a graph showing the pressure data of the present invention after 150 meters of wear at 150°C.

[0031] Explanation of reference numerals in the attached figures:

[0032] 1-Upper connector; 2-Upper straightening sleeve; 3-Center cylinder; 4-Spacer ring; 5-Lower connector; 6-Snap ring; 7-Pressure ring; 8-Guard ring; 9-Glue tube; 10-Shear pin; 11-Second sealing ring; 12-First sealing ring; 13-Lower straightening sleeve; 14-Third sealing ring. Detailed Implementation

[0033] The technical solution of the present invention will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention. It should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0034] like Figure 1-3 As shown, the present invention provides a dynamic sealing device for a sucker rod, comprising an upper connector 1, an upper straightening sleeve 2, a central cylinder 3, a lower straightening sleeve 13 and a lower connector 5 arranged sequentially from top to bottom. The central cylinder 3 is provided with a plurality of sealing components for sealing the continuous tubing. The inner walls of the upper straightening sleeve 2 and the lower straightening sleeve 13 are each provided with a plurality of straightening components for straightening the continuous tubing.

[0035] The sealing assembly includes a rubber sleeve 9 with a triangular cross-section. The inner wall of the rubber sleeve 9 is pointed, and the outer wall of the rubber sleeve 9 is a cylindrical surface parallel to the axis of the rubber sleeve. Protective rings 8 are symmetrically arranged on both sides of the rubber sleeve 9. The protective rings 8 are made of a relatively hard PEEK material, and the protective rings 8 on both sides cooperate with the rubber sleeve 9 to form a cylindrical shape. The inner diameter of the rubber sleeve 9 is smaller than the inner diameter of the protective rings 8. The inner diameter of the rubber sleeve 9 can be adjusted according to the outer diameter of the sucker rod and the working pressure. When the sucker rod passes through the sealing assembly, a seal is formed between the rubber sleeve 9 and the sucker rod. As the sucker rod moves, it causes the rubber sleeve 9 to deflect to one side, but the protective rings 8 prevent the rubber sleeve from shifting, thereby reducing the change in the inner diameter of the rubber sleeve 9 and maintaining a stable seal between the rubber sleeve 9 and the sucker rod. At the same time, the protective rings 8 on both sides can prevent the rubber sleeve 9 from falling off.

[0036] In addition, since the inner wall of the triangular rubber tube 9 is pointed, the inner wall of the rubber tube 9 can be compressed within a large range of diameter variation. Therefore, the design requirements for the inner diameter of the rubber tube 9 are reduced, and the process design window is increased.

[0037] The straightening component includes a pressure ring 7 and two buckles 6 symmetrically arranged on both sides of the pressure ring 7. The cross-section of the pressure ring 7 is bulging in the middle. The pressure ring 7 and the two buckles 6 cooperate to form a cylinder. Preferably, the inner diameter of the pressure ring 7 is smaller than the inner diameter of the buckles 6.

[0038] The inner diameter of the rubber sleeve 9 is 0.3mm-1mm smaller than the outer diameter of the continuous tubing; the inner diameter of the pressure ring 7 is 0.1mm-0.5mm larger than the outer diameter of the continuous tubing.

[0039] When the sucker rod passes through the dynamic sealing device, the small gap between the straightening component and the sucker rod ensures that the sucker rod passes through smoothly and also straightens the sucker rod; the relatively large gap between the rubber sleeve 9 and the sucker rod ensures the sealing performance between the rubber sleeve 9 and the sucker rod without causing serious wear to the rubber sleeve 9.

[0040] Furthermore, the sealing assembly also includes a spacer ring 4, which is disposed between the rubber sleeve 9 and the central cylinder 3; the spacer ring 4 is L-shaped, and the rubber sleeve 9 and the retaining ring 8 are embedded in the spacer ring 4, and the rubber sleeve 9, the retaining ring 8 and the spacer ring 4 form a cylindrical structure.

[0041] Furthermore, the outer wall of the spacer ring 4 is provided with a first groove, and a first sealing ring 12 is provided in the first groove. The first sealing ring 12 is preferably an O-ring.

[0042] Furthermore, the central cylinder 3 is symmetrically provided with spacer ring grooves on both sides. The upper spacer ring groove contacts the upper straightening sleeve 2, and the lower spacer ring groove contacts the lower straightening sleeve 13. The spacer ring 4 is embedded in the spacer ring groove. The spacer ring 4 is arranged in an L-shaped upward direction in the upper spacer ring groove, and the spacer ring 4 is arranged in an L-shaped downward direction in the lower spacer ring groove.

[0043] Furthermore, the upper connector 1 is embedded in the upper straightening sleeve 2 below, and the upper connector 1 and the upper straightening sleeve 2 are connected by a shear pin 10. A second groove is provided on the outer wall of the upper connector 1 embedded in the upper straightening sleeve 2, and a second sealing ring 11 is provided in the second groove. The second sealing ring 11 is preferably an O-ring.

[0044] Furthermore, the lower connector 5 is embedded in the lower straightening sleeve 13 above, and the lower connector 5 and the lower straightening sleeve 13 are connected by a shear pin. A third groove is provided on the outer wall of the lower connector 5 embedded in the lower straightening sleeve 13, and a third sealing ring 14 is provided in the third groove. The third sealing ring 14 is preferably an O-ring.

[0045] Furthermore, the upper straightening sleeve 2 is embedded in the upper end of the central cylinder 3, and the upper straightening sleeve 2 and the central cylinder 3 are connected by shear pins; a fourth groove is provided on the outer wall of the upper straightening sleeve 2 embedded in the central cylinder 3, and a fourth sealing ring is provided in the fourth groove; the lower straightening sleeve 13 is embedded in the lower end of the central cylinder 3, and the lower straightening sleeve 13 and the central cylinder 3 are connected by shear pins; a fifth groove is provided on the outer wall of the lower straightening sleeve 13 embedded in the central cylinder 3, and a fifth sealing ring is provided in the fifth groove.

[0046] Furthermore, a first straightening groove is provided above the upper straightening sleeve 2, and the straightening component is disposed in the first straightening groove; a second straightening groove is provided below the lower straightening sleeve 13, and the straightening component is disposed in the second straightening groove.

[0047] Furthermore, both the pressure ring 7 and the retaining ring 6 are made of PEEK material.

[0048] Furthermore, the number of sealing components is 12 sets, with 6 sets on each side of the central cylinder 3; the number of straightening components is 8 sets, with 4 sets in each of the upper straightening sleeve 2 and the lower straightening sleeve 13.

[0049] To verify the pressure-bearing capacity and sealing performance of the present invention, a combination test was conducted on the dynamic sealing device of the present invention under three simulated conditions: pressure simulation, temperature simulation, and wear simulation.

[0050] Pressure simulation involves placing the sucker rod into the dynamic sealing device of this invention, and then installing a connector device at the reserved pressure hole in the middle of the central cylinder 3. The sealing components on both sides of the central cylinder 3 and the outer wall of the sucker rod form a sealed space. The bottom hole pressure is input to this invention through the reserved pressure hole to simulate the downhole pressure environment and thus test the tool performance.

[0051] Temperature simulation is based on pressure simulation device. A heating device is loaded on the outer surface of the invention corresponding to the sealing component, heated to a specified temperature and kept at that temperature for a certain time, so that the heat is fully transferred to the sealing component and the sealing component is kept at high temperature for a certain time. Then the pressure bearing capacity and sealing performance of the invention are measured.

[0052] The water wear simulation involves pushing and pulling a continuous rod of the same size as an actual sucker rod back and forth inside the dynamic sealing device of this invention to complete the required stroke, and then measuring the pressure-bearing capacity and sealing performance of this invention.

[0053] The experimental conditions used in this invention are as follows:

[0054] The pressure simulation was conducted at a pressure of 35 MPa; the temperature simulation was conducted at a heating temperature of 150°C for 60 minutes; and the water abrasion simulation was conducted at a stroke of 150 meters.

[0055] The experimental results are as follows:

[0056] like Figure 4 The figure shows a pressure simulation of the present invention under normal temperature conditions. The pressure was 35 MPa and held for a certain period of time. The pressure sensor was placed in the honeycomb space formed by the sealing components on both sides of the central cylinder, and the pressure value measured by the pressure sensor was measured. There was no obvious pressure drop, indicating that the sealing performance of the present invention is good.

[0057] like Figure 5 As shown, under normal temperature conditions, after the continuous rod reciprocates for 150 meters in the dynamic sealing device of the present invention, pressure simulation is performed. The pressure is 38MPa, 55MPa, and 70MPa. The pressure is held for a certain period of time under each pressure, and there is no significant pressure drop.

[0058] like Figure 6 As shown, temperature simulation was performed on the present invention. The heating temperature was raised to 150°C and then held for 60 minutes. During the heating process, a continuous rod was used to simulate water wear on the dynamic sealing device of the present invention. The wear stroke was 150 meters. After that, pressure simulation was performed. The pressure was gradually increased to 70 MPa and held for a certain period of time. There was no obvious pressure drop, indicating that the sealing performance of the present invention is good.

[0059] The above specific embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A dynamic sealing device for a sucker rod, comprising, from top to bottom, an upper connector, an upper centralizing sleeve, a central sleeve, a lower centralizing sleeve, and a lower connector, wherein the central sleeve contains a plurality of sealing components for sealing the coiled tubing, and the inner walls of the upper and lower centralizing sleeves are each provided with a plurality of centralizing components for centralizing the coiled tubing; characterized in that, The sealing assembly includes a rubber tube with a triangular cross-section, the inner wall of the rubber tube being pointed, and protective rings symmetrically arranged on both sides of the rubber tube, the protective rings on both sides cooperating with the rubber tube to form a cylinder; the inner diameter of the rubber tube is smaller than the inner diameter of the protective rings; The straightening component includes a pressure ring and buckles symmetrically arranged on both sides of the pressure ring. The cross-section of the pressure ring is bulging in the middle, and the pressure ring and the two buckles cooperate to form a cylinder. The inner diameter of the rubber sleeve is 0.3mm-1mm smaller than the outer diameter of the continuous tubing; the inner diameter of the pressure ring is 0.1mm-0.5mm larger than the outer diameter of the continuous tubing. The pressure ring and the retaining rings on both sides have an arc-shaped contact surface, and the contact between the two can adapt to the angle change of the sucker rod, playing a role in fine-tuning the angle; both the pressure ring and the retaining ring are made of PEEK material; The sealing assembly further includes a spacer ring disposed between the rubber sleeve and the central cylinder; the spacer ring is L-shaped, and the rubber sleeve and the retaining ring are embedded in the spacer ring, with the rubber sleeve, the retaining ring and the spacer ring forming a cylindrical structure; A first straightening groove is provided above the upper straightening sleeve, and the straightening component is disposed in the first straightening groove; a second straightening groove is provided below the lower straightening sleeve, and the straightening component is disposed in the second straightening groove.

2. The polished rod dynamic seal assembly of claim 1, wherein, The outer wall of the spacer ring is provided with a first groove, and a first sealing ring is provided in the first groove.

3. The polished rod dynamic seal assembly of claim 1, wherein, The central cylinder is symmetrically provided with spacer ring grooves on both sides, and the spacer rings are embedded in the spacer ring grooves. The spacer rings are arranged in an L-shaped upward direction in the upper spacer ring groove, and the spacer rings are arranged in an L-shaped downward direction in the lower spacer ring groove.

4. The polished rod dynamic seal assembly of claim 1, wherein, The upper connector is embedded in the upper straightening sleeve below, and the upper connector and the upper straightening sleeve are connected by a shear pin. A second groove is provided on the outer wall of the upper connector embedded in the upper straightening sleeve, and a second sealing ring is provided in the second groove.

5. The polished rod dynamic seal assembly of claim 1, wherein, The lower connector is embedded in the lower straightening sleeve above, and the lower connector and the lower straightening sleeve are connected by a shear pin. A third groove is provided on the outer wall of the lower connector embedded in the lower straightening sleeve, and a third sealing ring is provided in the third groove.

6. The polished rod dynamic seal assembly of claim 1, wherein, The upper straightening sleeve is embedded in the upper end of the central cylinder below, and the upper straightening sleeve and the central cylinder are connected by shear pins; the lower straightening sleeve is embedded in the lower end of the central cylinder above, and the lower straightening sleeve and the central cylinder are connected by shear pins.

7. The polished rod dynamic seal assembly of claim 1, wherein, The number of sealing components is 12 sets, with 6 sets on each side of the central cylinder; the number of straightening components is 8 sets, with 4 sets in each of the upper straightening sleeve and the lower straightening sleeve.

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