A sealing grease for high-pressure valve plugging and a preparation method and application thereof

Abstract

The application discloses a sealing grease for high-pressure valve plugging and a preparation method and application thereof. The formula of the sealing grease comprises key components such as methyl silicone oil, oxidized castor oil, butyl phthalate, molybdenum disulfide, graphite, hydrophobic aerogel silicon, hydrophilic aerogel silicon, anti-rust antioxidant and hydrogen sulfide corrosion inhibitor, and the weight parts and specific indexes of the raw materials are specified in detail. Through a specific preparation process, the sealing grease exhibits excellent high-pressure resistance, corrosion resistance, rapid curing and plugging capacity, and is particularly suitable for gate valve sealing under complex working conditions of oilfield sites. The preparation method of the sealing grease comprises steps of accurate proportioning of raw materials, heating and stirring, degassing treatment and three-roller machine grinding, so that the product performance is stable, and the cone penetration is moderate. The application of the sealing grease significantly improves the reliability of oilfield valve sealing, and has wide application prospect and important practical value.

Description

Technical Field

[0001] This invention belongs to the field of sealing grease technology, and more specifically, relates to a sealing grease for sealing high-pressure valves, its preparation method, and its application. Background Technology

[0002] In fluid transport systems, valves, as critical control components, directly affect the safe and efficient operation of the entire system through their performance and reliability. Especially in the specialized field of oilfield mining, valves must withstand extreme working environments and cope with complex and ever-changing media conditions; gate valves are one such widely used type. Through their unique gate structure, gate valves effectively cut off and regulate fluid flow, and are widely used in various stages of oil well extraction, oil and gas transportation, and fracturing operations, making them an indispensable and crucial component in ensuring the safety and efficiency of oilfield production.

[0003] However, the operating environment of gate valves in oilfields is extremely harsh, placing extremely high demands on valve design, materials, and sealing technology. Firstly, common media in oilfield operations include crude oil, acidic fracturing fluids, and various hydrocarbons. These substances are not only corrosive but may also contain solid particles such as sand and mineral fragments, causing wear and erosion on the valve's sealing surfaces and accelerating the aging and damage of the seals. Acidic fracturing fluids, in particular, pose a significant challenge to the corrosion resistance of valve materials due to their strong corrosiveness.

[0004] Secondly, oilfield operations are often accompanied by high-pressure environments, especially in deep oil and gas extraction and high-pressure water injection and fracturing operations, where system pressures can reach 140 MPa or even higher. These high-pressure conditions pose a severe challenge to the protective properties of valve sealing greases. Traditional sealing greases are prone to deformation, loss, or hardening under high pressure, leading to decreased sealing performance and subsequent leaks. This not only affects operational efficiency but can also cause environmental pollution and safety accidents.

[0005] Furthermore, the variable operating conditions at oilfield sites and the need for rapid response in emergencies place special demands on the immediate repair capability of valve seals. If a valve seal fails and cannot be effectively plugged in a timely manner, it could lead to production interruptions, resource waste, and even environmental disasters. Therefore, developing a sealing grease that can adapt to extreme operating conditions, respond quickly, and effectively plug leaks has become crucial for solving the sealing challenges of gate valves in oilfields. Summary of the Invention

[0006] To address the above problems, this invention provides a sealing grease for high-pressure valve sealing, its preparation method, and its application.

[0007] This invention includes the following technical solutions: A sealing grease for sealing high-pressure valves is made from the following raw materials in parts by weight: 60-76 parts of methyl silicone oil 8-12 parts of oxidized castor oil Butyl phthalate (DBP) 6.5-12 parts 1.5-3.5 parts of molybdenum disulfide Graphite 1.2-2.9 parts Hydrophobic fumed silica 2.8-4.8 parts Hydrophilic silica 2.8-4.8 parts Rust inhibitor and antioxidant 3.5-4.5 parts 0.2-0.3 parts of hydrogen sulfide corrosion inhibitor.

[0008] Furthermore, in the aforementioned sealing grease for high-pressure valve sealing, the methyl silicone oil has a viscosity of 25,000-35,000 centistokes at 40°C.

[0009] Furthermore, in the aforementioned sealing grease for high-pressure valve sealing, the oxidized castor oil has a viscosity between 100-600 centipoise, a color between Caldwell 6-16, an acid value between 10-20 mg KOH / g, and an iodine value between 50-80 gI / 100g.

[0010] Furthermore, in the aforementioned sealing grease for sealing high-pressure valves, the graphite is graphite powder with an average particle size of 5-20 μm.

[0011] Furthermore, in the aforementioned sealing grease for high-pressure valve sealing, the hydrophobic silicone is hydrophobic silicone R106.

[0012] Furthermore, in the aforementioned sealing grease for sealing high-pressure valves, the hydrophilic silica is hydrophilic silica N2O.

[0013] Furthermore, in the aforementioned sealing grease for sealing high-pressure valves, the rust-preventive and antioxidant agent is composed of antioxidant BHT, tris(2-ethylhexyl) phosphate, and EDTA in a mass ratio of 1:2 to 4:1.

[0014] Furthermore, in the aforementioned sealing grease for sealing high-pressure valves, the hydrogen sulfide corrosion inhibitor is MY-80A, an anti-hydrogen sulfide corrosion inhibitor.

[0015] This invention discloses a method for preparing the above-mentioned sealing grease for high-pressure valve sealing, comprising the following steps: (1) Place methyl silicone oil in a stirring device and stir to raise the temperature to 80-140℃; (2) Add oxidized castor oil and butyl phthalate, and stir to dissolve; (3) Add hydrophobic fumed silica, hydrophilic fumed silica, graphite, molybdenum disulfide, rust inhibitor and antioxidant and hydrogen sulfide corrosion inhibitor, stir for 1-5 hours, and degas during stirring; (4) Grind with a three-roll mill to obtain a sealing grease with an unworked cone penetration of 290-310.

[0016] The present invention also discloses the application of the above-mentioned sealing grease in gate valves in oilfields.

[0017] Compared with the prior art, the present invention has the following innovations and beneficial effects: (1) Excellent acid and hydrocarbon resistance: The present invention uses methyl silicone oil as the base oil, combined with the synergistic effect of castor oil oxide, molybdenum disulfide, graphite and fumed silica (including hydrophobic and hydrophilic fumed silica), so that the sealing grease is structurally stable and does not disperse in acidic and hydrocarbon environments, thereby greatly extending the service life and reliability of the sealing grease; (2) Excellent lubrication and sealing performance: The addition of molybdenum disulfide and graphite not only plays a role in filling and thickening, but also significantly improves the lubrication performance of the sealing grease, reduces friction, and improves the sealing effect, so that the high-pressure valve can maintain a good sealing state even under extreme working conditions; (3) Excellent rust prevention and oxidation resistance: The addition of rust inhibitors and antioxidants effectively inhibits the deterioration of the sealing grease caused by oxidation and corrosion during use, which can not only extend the service life of the sealing grease, but also protect the metal parts of the valve. (4) Enhanced resistance to hydrogen sulfide corrosion: The addition of hydrogen sulfide corrosion inhibitor, especially the anti-hydrogen sulfide corrosion inhibitor MY-80A, effectively protects the sealing grease from the corrosion damage of hydrogen sulfide. This is especially important for harsh environments containing hydrogen sulfide, such as oil fields, and can significantly improve the safety and reliability of valves; (5) Stable product structure: By selecting appropriate raw material ratios and preparation processes, the sealing grease prepared by this invention has a stable product structure. During the stirring and grinding process, the uniformity and stability of the product are further improved by degassing treatment, ensuring the stable performance of the sealing grease during long-term use; (6) Wide range of applications: The sealing grease described in this invention is not only suitable for sealing high-pressure valves, but also particularly suitable for use in harsh environments such as gate valves in oil fields. Its excellent performance and stability make the sealing grease have a wide range of application prospects in the petroleum, chemical, and metallurgical industries. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0019] Examples 1-5 This example is a preparation example. The formulations of Examples 1-5 are shown in Table 1.

[0020] Table 1: Formulations of the sealing grease for Examples 1-5 (unit: parts by weight)

[0021] The methyl silicone oil has a viscosity of 3000 centistokes at 40°C; The oxidized castor oil has a viscosity of 400 centipoise, a Gardner color of 10, an acid value of 15 mgKOH / g, and an iodine value of 65 g I / 100g; The graphite is graphite powder with an average particle size of 10 μm; The hydrophobic fumed silica is hydrophobic fumed silica R106; The hydrophilic fumed silica is hydrophilic fumed silica N20; The rust and antioxidant inhibitor is prepared by mixing antioxidant BHT, tris(2-ethylhexyl) phosphate and EDTA at a mass ratio of 1:3:1; The hydrogen sulfide corrosion inhibitor is hydrogen sulfide corrosion resistant inhibitor MY-80A.

[0022] Comparative Example 1 It does not contain oxidized castor oil, and the rest is the same as Example 3.

[0023] Comparative Example 2 It does not contain molybdenum disulfide and graphite, and the rest is the same as Example 3.

[0024] Comparative Example 3 It does not contain hydrophobic fumed silica R106 and hydrophilic fumed silica N20, and the rest is the same as Example 3.

[0025] Test Example Performance tests were performed on the sealing greases prepared in Examples 1-5 and Comparative Examples 1-3. Wherein, pressure resistance test (140 MPa): the sealing grease is applied to the valve surface of a plate valve, and the test is considered passed if the valve can continuously pass 10 times of 140 MPa tests (3 h each time) without water leakage and the pressure drop is less than 5 MPa. The test methods for other test items are carried out according to the standards described in the table. Specific test method standards and results are shown in Table 2 and Table 3.

[0026] Table 2: Performance tests of the sealing greases of Examples 1-5

[0027] Table 3: Performance tests of the sealing greases of Comparative Examples 1-3

[0028] As can be seen from the data in Table 2 (Examples 1-5), the sealing grease disclosed in this invention meets the testing standards for acid resistance, oil resistance, and hydrocarbon resistance. It does not disperse, harden, or decompose; it has suitable unworked cone penetration, high colloidal stability and high-temperature stability, extremely low evaporation and water loss. Furthermore, it passed all corrosion tests, acid resistance tests, oil resistance tests, hydrocarbon resistance tests, and pressure tests, proving its excellent sealing performance and suitability for use in harsh environments such as oilfield gate valves. A comparison of the test data in Example 3 and Table 3 (Comparative Examples 1-3) shows that if the sealing grease is made solely from silicone-thickened silicone oil, its structure is relatively loose (density generally around 1 g / cm³), making it prone to structural damage when exposed to acidic and hydrocarbon media. Therefore, the addition of graphite and molybdenum disulfide serves to both fill the sealing grease structure and increase its density (1.3-1.4 g / cm³), and also to prevent the penetration of acids and hydrocarbons. Methyl silicone oil: high viscosity, good low-temperature fluidity, and excellent resistance to acids and hydrocarbons compared to mineral oil. Vaporized silica: Primarily functions as a thickener; chemically stable. Oxidized castor oil: Stabilizes product structure; oil- and acid-resistant. Graphite: Chemically stable; acid- and hydrocarbon-resistant; increases product density; thickens; and provides wear resistance. Molybdenum disulfide: Chemically stable; acid- and hydrocarbon-resistant; increases sealant density; thickens; and provides wear resistance. DBP: Acts as a dissolving rust inhibitor, antioxidant, and hydrogen sulfide corrosion inhibitor. Rust inhibitor and antioxidant: Provides rust prevention and oxidation resistance. Hydrogen sulfide corrosion inhibitor: Protects against the corrosive damage of hydrogen sulfide to sealant.

[0029] The sealing grease prepared in Example 3 of this invention was used in a gate valve in an oil field, and it was found that its service life was increased by 51% and its pressure resistance was improved by 34%; the cost of use was reduced and the sealing effect was improved.

[0030] As can be seen from the above embodiments, this invention overcomes the limitations of acid and hydrocarbon resistance. During acid and hydrocarbon resistance tests, the product structure remains stable and does not disperse. This invention uses methyl silicone oil (viscosity 30,000 Ries at 40°C) as the base oil, and adds oxidized castor oil, DBP, molybdenum disulfide, graphite, and fumed silica as auxiliary thickeners. Rust inhibitors, antioxidants, and hydrogen sulfide corrosion inhibitors are also added. This invention can pass acid and hydrocarbon resistance tests and can be used in harsh environments such as gate valves in oil fields.

[0031] The above are merely a few preferred embodiments of the present invention, described in a relatively specific and detailed manner, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A sealing grease for sealing high-pressure valves, characterized in that, Made from the following parts by weight of raw materials: 60-76 parts of methyl silicone oil 8-12 parts of oxidized castor oil 6.5-12 parts of butyl phthalate 1.5-3.5 parts of molybdenum disulfide Graphite 1.2-2.9 parts Hydrophobic fumed silica 2.8-4.8 parts Hydrophilic silica 2.8-4.8 parts Rust inhibitor and antioxidant 3.5-4.5 parts 0.2-0.3 parts of hydrogen sulfide corrosion inhibitor.

2. The sealing grease for high-pressure valve sealing according to claim 1, characterized in that, The methyl silicone oil has a viscosity of 25,000-35,000 centistokes at 40°C.

3. The sealing grease for high-pressure valve sealing according to claim 1, characterized in that, The oxidized castor oil has a viscosity between 100-600 centipoise, a color between 6-16 on the Calorie scale, an acid value between 10-20 mg KOH / g, and an iodine value between 50-80 gI / 100g.

4. The sealing grease for high-pressure valve plugging according to claim 1, characterized in that, The graphite is graphite powder with an average particle size of 5-20 μm.

5. The sealing grease for high-pressure valve sealing according to claim 1, characterized in that, The hydrophobic fumed silica is hydrophobic fumed silica R106.

6. The sealing grease for high-pressure valve plugging according to claim 1, characterized in that, The hydrophilic fumed silica is hydrophilic fumed silica N2O.

7. The sealing grease for high-pressure valve sealing according to claim 1, characterized in that, The rust inhibitor and antioxidant is composed of antioxidant BHT, tri(2-ethylhexyl) phosphate and EDTA, with a mass ratio of 1:2 to 4:

1.

8. The sealing grease for high-pressure valve sealing according to claim 1, characterized in that, The hydrogen sulfide corrosion inhibitor is MY-80A, an anti-hydrogen sulfide corrosion inhibitor.

9. The method for preparing the sealing grease for high-pressure valve plugging as described in any one of claims 1-8, characterized in that, Includes the following steps: (1) Place methyl silicone oil in a stirring device and stir to raise the temperature to 80-140℃; (2) Add oxidized castor oil and butyl phthalate, and stir to dissolve; (3) Add hydrophobic fumed silica, hydrophilic fumed silica, graphite, molybdenum disulfide, rust inhibitor and antioxidant and hydrogen sulfide corrosion inhibitor, stir for 1-5 hours, and degas during stirring; (4) Grind with a three-roll mill to obtain a sealing grease with an unworked cone penetration of 290-310.

10. The application of the sealing grease as described in any one of claims 1-8 in gate valves in oilfields.

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