Wellhead sealing composite packing with special weaving structure, manufacturing method and application thereof

Abstract

This invention discloses a wellhead sealing composite packing with a special braided structure, its manufacturing method, and its application. The composite packing includes a main body with corner braids at its edges. The manufacturing method includes the following steps: braiding the corner braids; and braiding the main body using the corner braids as a framework. When the composite packing of this invention is used to install on a polished rod sealer, the sealing cavity is first cleaned, and the packing is inserted sequentially in a predetermined direction, ensuring the corner braids are correctly positioned. An appropriate preload is applied when the polished rod passes through the packing, and finally, the pressure cap is installed and the clamping force is adjusted. The composite packing of this invention has low frictional resistance between itself and the polished rod, reducing power loss and lowering equipment operating energy consumption.

Description

Technical Field

[0001] This invention relates to the field of oilfield production engineering technology, specifically to a wellhead sealing composite packing with a special woven structure, its manufacturing method, and its application. Background Technology

[0002] As oilfield development deepens, pumping units are commonly used for oil extraction. During equipment production, polished rod sealing devices are typically installed to prevent crude oil and natural gas leakage from the polished rod. Traditional polished rod seals usually use rubber as the sealing material to ensure no leakage during production. The sealing method involves an interference fit with the polished rod, resulting in poor high-temperature resistance. Prolonged friction with the reciprocating polished rod gradually diminishes its sealing performance, requiring frequent tightening of the pressure cap or replacement of the packing, thus affecting equipment operation. Furthermore, synthetic rubber materials have a high coefficient of friction, high wear rate, and poor resistance to media aging, failing to meet the requirements of oilfield operating conditions. With prolonged use, traditional polished rod seals may loosen and shift between the sealing device and the wellhead, leading to oil leakage between the sealing device or the upper pressure device and the packing. This affects the sealing effect of the polished rod seal and poses a certain impact on production and equipment safety.

[0003] Announcement No. CN111439957B discloses a method for preparing high-temperature resistant vermiculite metal wire mesh braided packing, including steps such as material preparation, coating, knitting, weaving, shaping, and spraying. The material preparation includes expanded vermiculite, adhesive, dispersant, siloxane, foaming agent, and inorganic filler. This invention uses expanded vermiculite as the main material to weave the packing. By adding a foaming agent, the packing expands under heat. A mold box is used to limit the foaming expansion volume of the packing, and a counterweight plate is used to apply a certain external pressure to the foaming of the packing. This not only produces uniform and compact foamed packing, but also helps to reduce the compression set and improve the pressure resistance.

[0004] Announcement No. CN103351488B discloses a flexible sealing packing for pumps and its manufacturing method. The sealing packing is composed of 4-6 wt% graphite and molybdenum disulfide mixed material, 32-38 wt% PTFE fiber, 15-20 wt% Kevlar fiber, 28-32 wt% lubricant, 8-12 wt% natural rubber, and 2-4 wt% calcium carbonate. The mass ratio of graphite to molybdenum disulfide in the graphite and molybdenum disulfide mixed material is 3:2; the lubricant includes high-temperature silicone oil and petroleum jelly, with a mass ratio of high-temperature silicone oil to petroleum jelly of 5:1.

[0005] Publication No. CN201016287Y discloses a carbonized aramid fiber blended packing sealing assembly, including a packing body. The packing body is circular and has openings on its sidewalls. Its distinguishing feature is that both the upper and lower surfaces of the packing body are conical, forming a concave bowl shape. Six to ten packing bodies are sequentially placed inside a packing box. The packing body is composed of carbonized fiber, aramid fiber, and a blending agent, wherein the blending agent is one of polytetrafluoroethylene, graphite emulsion, or molybdenum dicarbide.

[0006] The packing structure of the prior art differs from that of the present invention, as do the manufacturing method and the proportion of manufacturing materials. The composite packing of the present invention has better wear resistance.

[0007] In summary, the technical solutions, technical problems to be solved, and beneficial effects of the above-disclosed technologies are all different from those of the present invention. Regarding the more technical features, technical problems to be solved, and beneficial effects of the present invention, the above-disclosed technical documents do not provide any technical inspiration. Summary of the Invention

[0008] In view of the above-mentioned defects in the existing technology, the purpose of this invention is to provide a wellhead sealing composite packing with a special braided structure, its manufacturing method and application.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] On the one hand, the present invention provides a wellhead sealing composite packing with a special braided structure, including a main body, wherein corner lines are provided at the edges and corners of the main body.

[0011] Furthermore, the main body is woven from polytetrafluoroethylene, aramid fiber, and graphite powder yarn, the corner yarn is woven from aramid fiber, and the main body is woven with the corner yarn as a frame.

[0012] Furthermore, by weight, the composite packing contains 5%-25% aramid fiber, 60%-85% polytetrafluoroethylene, and the remainder is graphite powder.

[0013] Preferably, by weight, the composite packing contains 20-25% aramid fiber, 60-65% polytetrafluoroethylene, and the remainder is graphite powder.

[0014] Furthermore, four corner lines are provided, located on the rounded edge of the main body.

[0015] Secondly, the present invention provides a method for manufacturing a wellhead sealing composite packing with a special braided structure, comprising the following steps: braiding corner wires; and braiding the main body using the corner wires as a frame.

[0016] Furthermore, aramid fibers are used to weave the corner trim.

[0017] Furthermore, the main body is woven using double-layer black PTFE-coated graphite powder yarn and aramid fiber.

[0018] Furthermore, before weaving, the double-layer black PTFE-coated graphite powder thread and aramid fiber are soaked in PTFE emulsion to allow the fibers to fully absorb the impregnation solution; after weaving is completed, the weaved packing is soaked in PTFE emulsion, and the fully penetrated packing is placed in a constant temperature oven for drying to solidify the PTFE emulsion.

[0019] In three aspects, the present invention provides an application of a wellhead sealing composite packing with a special braided structure, which uses the composite packing described in one aspect or the composite packing manufactured by the manufacturing method described in the second aspect for wellhead sealing.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The composite packing of the present invention can maintain good physical properties and sealing effect under long-term high temperature environment, and the applicable temperature range can reach above 200℃.

[0022] 2. The composite packing of the present invention is cured at a suitable temperature and time to ensure that the impregnation liquid is fully cured and tightly bonded to the packing substrate, thereby improving the overall performance; it adopts high-performance fiber materials and a unique weaving structure, which has extremely high wear resistance and significantly extends the replacement cycle.

[0023] 3. The composite packing of the present invention can tightly fit the surface of the smooth rod under pressure, adapt to smooth rods of different diameters and complex working conditions, and provide a reliable dynamic seal; it can still maintain dimensional stability under repeated hot and cold alternation conditions, avoiding seal failure caused by thermal expansion and contraction; it has strong resistance to deformation under high pressure environment, ensuring the reliability of the seal under long-term high pressure operation.

[0024] 4. When the composite packing of the present invention is used to install on the smooth rod sealer, first clean the sealing cavity, then insert the packing in sequence according to the predetermined direction, ensuring that the corner position is correct. When the smooth rod passes through the packing, apply an appropriate pre-tightening force, and finally install the pressure cap and adjust the clamping force. The composite packing of the present invention has low frictional resistance between the composite packing and the smooth rod, reducing power loss and lowering the energy consumption of equipment operation. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a wellhead sealing composite packing with a special braided structure according to the present invention;

[0026] Figure 2 This is a table showing the material composition ratios of the fillers in all embodiments and comparative examples;

[0027] Figure 3 These are the wear test results for all embodiments and comparative examples;

[0028] Figure 4These are the tensile strength and impact strength test results for all embodiments and comparative examples;

[0029] Figure 5 This is the result of the temperature resistance weight loss rate test in Example 4. Detailed Implementation

[0030] 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.

[0031] This invention provides a special braided wellhead sealing composite packing, comprising polytetrafluoroethylene (PTFE), aramid fiber, and graphite powder thread. By mixing and weaving PTFE, aramid fiber, and graphite powder thread in a certain proportion and then impregnating with PTFE solvent, a novel wellhead sealing composite packing with characteristics such as high temperature resistance, wear resistance, and high plasticity is obtained.

[0032] Specifically, by weight, aramid fiber accounts for 5%-25%, polytetrafluoroethylene accounts for 60%-85%, and graphite powder is the remainder.

[0033] Furthermore, such as Figure 1 As shown, the main body is woven from polytetrafluoroethylene, aramid fiber, and graphite powder, forming a composite structure that provides both high-strength support and good sealing. The corners of the main body are fitted with corner braids woven from aramid fiber. The main body is ring-shaped, with the four corner braids woven from aramid fiber positioned on the rounded edge of the packing body, giving the packing excellent tensile strength and cut resistance, effectively preventing damage to the packing caused by the movement of the bare rod.

[0034] A method for manufacturing a wellhead sealing composite packing with a special braided structure includes the following steps:

[0035] S1. According to the design ratio, PTFE fibers and double-layer black PTFE-coated graphite powder threads are immersed in PTFE emulsion to ensure that the fibers fully absorb the impregnation solution, thereby enhancing the bonding force between fibers and the overall performance.

[0036] The double-layer black PTFE-coated graphite powder wire has an inner layer of graphite powder wire and an outer layer of double-layer polytetrafluoroethylene fiber, which provides good wear resistance and lubrication, as well as improves stability and chemical corrosion resistance at high temperatures. The packing wear amount is ≤0.3g.

[0037] S2, Weaving method: Four-sided aramid corner yarn and double-layer black PTFE-coated graphite powder yarn + aramid braiding;

[0038] S201, Initial Stage: Aramid fibers are selected as corner wires and woven into a four-sided frame structure according to the design dimensions. Only aramid fibers are used in this stage to ensure the high strength and high temperature resistance of the frame.

[0039] S202. Main Body Weaving: Within the framework formed by the yellow aramid angle wires, double-layer black PTFE-coated graphite powder wires and aramid fibers are woven together to form a layered main body structure. This maintains uniform weaving density, ensuring even distribution of the graphite powder wires within the packing, providing good thermal conductivity and sealing. The addition of aramid fibers further enhances the overall strength and tensile properties of the packing. During the weaving process, the double-layer black PTFE-coated graphite powder wires and aramid fibers of the main structure are tightly interwoven, forming a stable composite structure while ensuring a firm connection between the yellow aramid angle wires and the main body.

[0040] S203. Finishing treatment: After the main weaving is completed, the edges of the packing are smoothed, excess fibers are cut off, and the packing is made to ensure that the shape is regular and there are no burrs or looseness.

[0041] S3. Post-processing and quality inspection:

[0042] S301, Secondary Impregnation: The braided packing is immersed again in PTFE emulsion to ensure that the impregnation liquid fully penetrates every corner of the packing, forming a stable protective layer and further enhancing the packing's chemical corrosion resistance, lubricity, wear resistance and sealing performance.

[0043] S302. Drying and Shaping: Place the impregnated packing in a constant temperature oven and dry it according to the temperature and time specified for the curing of PTFE emulsion, so that the PTFE emulsion can be cured to form a stable sealing coating.

[0044] S303. Quality Inspection: Conduct visual inspection, dimensional measurement, sealing performance testing, and high temperature resistance test on the dried packing to ensure that the product meets design requirements and usage standards.

[0045] Place the newly prepared composite packing rings into the grooves of the polished rod seal one ring at a time, according to the predetermined compression ratio and direction. The weave patterns of adjacent packing rings should be staggered to improve sealing performance and extend service life. Tightening and Adjustment: Gradually tighten the gland bolts of the polished rod seal until the packing reaches the specified compression force. Simultaneously, observe for leaks or use specialized tools to test the sealing pressure and make necessary fine adjustments to ensure an effective seal is formed between the polished rod and the packing.

[0046] Example 1:

[0047] Filler B is manufactured according to the above method. The proportion of aramid fiber in filler B is 5%, polytetrafluoroethylene is 80%, and graphite powder is 15%.

[0048] Example 2:

[0049] Filler C is manufactured according to the above method. The proportion of aramid fiber in filler C is 20%, polytetrafluoroethylene is 75%, and graphite powder is 15%.

[0050] Example 3:

[0051] Filler D is manufactured according to the above method. In filler D, the proportion of aramid fiber is 15%, the proportion of polytetrafluoroethylene is 70%, and the proportion of graphite powder is 15%.

[0052] Example 4:

[0053] Filler E is manufactured according to the above method. The proportion of aramid fiber in filler E is 20%, polytetrafluoroethylene is 65%, and graphite powder is 15%.

[0054] Example 5:

[0055] Filler F is manufactured according to the above method. The proportion of aramid fiber in filler F is 25%, polytetrafluoroethylene is 60%, and graphite powder is 15%.

[0056] Comparative example:

[0057] Filler A is manufactured according to the above method. In filler A, the proportion of aramid fiber is 0%, the proportion of polytetrafluoroethylene is 85%, and the proportion of graphite powder is 15%.

[0058] The packings obtained in Examples 1-5 and the packings obtained in the comparative example were subjected to wear resistance tests to obtain... Figure 3 The results are shown.

[0059] It can be seen that the wear rate of Examples 1-5 is significantly lower than that of the comparative example, indicating that they are more wear-resistant.

[0060] The fillers obtained in Examples 1-5 and the fillers obtained in the comparative example were subjected to tensile strength and impact strength tests, and the results were as follows: Figure 4 The results are shown.

[0061] It can be seen that the tensile strength and impact strength of the fillers obtained in Examples 1-5 are significantly higher than those in the comparative examples, and they are more durable.

[0062] The fillers manufactured in Examples 1-5 were subjected to corrosion resistance tests, and their service life was all over 20 months, demonstrating good corrosion resistance.

[0063] according to Figure 3 , Figure 4 It can be seen that the filler ratio in Examples 4 and 5 is preferred.

[0064] The high-temperature resistance test was conducted on the filler E manufactured in Example 4, and the results were as follows: Figure 5 The results show that, in the experiment, the high-temperature wellhead sealing composite packing only exhibits significant weight loss of packing E at temperatures above 260℃, demonstrating excellent high-temperature resistance.

[0065] All components not discussed in detail in this application, as well as the connection methods of these components, are well-known technologies in this field. They can be directly applied and will not be elaborated further.

[0066] In this invention, the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0067] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0068] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A wellhead seal composite packing box of special braided construction, characterized in that, Includes a main body, and corner lines are provided at the edges and corners of the main body.

2. The composite packing as set forth in claim 1, wherein The main body is woven from polytetrafluoroethylene, aramid fiber, and graphite powder yarn, and the corner yarn is woven from aramid fiber. The main body is woven with the corner yarn as a frame.

3. The composite packing as set forth in claim 2, wherein By weight, the composite packing contains 5%-25% aramid fiber, 60%-85% polytetrafluoroethylene, and the remainder is graphite powder.

4. The composite packing as set forth in claim 3, wherein By weight, the composite packing contains 20-25% aramid fiber, 60-65% polytetrafluoroethylene, and the remainder is graphite powder.

5. The composite packing as set forth in claim 1, wherein The main body is circular, and four corner lines are provided, located on the circular edge of the main body.

6. A method of manufacturing a wellhead seal composite packing box of a special braided structure, comprising the steps of: Weaving corner lines; weaving the main body using corner lines as a framework.

7. The manufacturing method according to claim 6, wherein The corner trim is made of aramid fiber.

8. The manufacturing method according to claim 7, wherein The main body is woven using double-layer black PTFE-coated graphite powder yarn and aramid fiber.

9. The manufacturing method according to claim 8, wherein Before weaving, double-layer black PTFE-coated graphite powder yarn and aramid fiber are soaked in PTFE emulsion to allow the fibers to fully absorb the impregnation solution. After weaving is completed, the woven packing is immersed in PTFE emulsion. The fully penetrated packing is then placed in a constant temperature oven for drying, allowing the PTFE emulsion to solidify.

10. A special braided construction wellhead seal composite packing application characterized by, The composite packing as described in any one of claims 1-5 or the composite packing manufactured by any one of the manufacturing methods of claims 6-9 is used for wellhead sealing.

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