A tubing thread sealant for shallow coalbed methane wells, and a preparation method and application thereof

Abstract

This application provides a tubing thread sealant for shallow coalbed methane wells, its preparation method, and its application, belonging to the field of oilfield development. The tubing thread sealant comprises: component A, component B, and component C; wherein, by weight, component A includes the following chemical components: 41-61 parts of polymer matrix, 15-23 parts of 5-methylthio-7-fluoro-1H-indene, and 23-37 parts of excipients; component B includes the following chemical components by weight: 80-90 parts of epoxy curing agent and 10-25 parts of epoxy curing accelerator; and component C is an additive. In component A, a polymer matrix is ​​used as the matrix. By introducing molecularly designed active substances containing fluorine and sulfur elements, such as 5-methylthio-7-fluoro-1H-indene, the material combines the weather resistance and toughness of rubber while maintaining stable performance at high temperatures, making it less prone to deformation or failure.

Description

Technical Field

[0001] This application relates to the field of oilfield development technology, and in particular to a thread sealant for oil pipes in shallow coalbed methane wells and its preparation method. Background Technology

[0002] As an essential material for production and operation in various oil and gas fields, the use of tubing increases year by year due to the introduction of new wells and the maintenance of old wells, resulting in a consistently high proportion of costs in the oil and gas field production process. In recent years, with various oil fields advocating cost reduction and efficiency improvement, and exploring the entire life cycle of materials and equipment, through detailed surveys of field conditions and innovative research and development of new materials, combined with actual field conditions, the service life of tubing strings has been extended, thereby reducing the oilfield's material procurement costs and old material management expenses.

[0003] Currently, the reuse of old oil pipes only uses the cutting and reprocessing process. Even if the thread quality can be guaranteed, it increases the cost of pipe repair and transportation. There has been no in-depth excavation for the reuse of oil pipes retrieved from the field, no determination of thread quality control parameters for oil pipe reuse, and no specific thread sealant. As a result, the reuse of old oil pipes is prone to thread sticking, thread breakage, or thread crevice corrosion, which can lead to pipe string failure.

[0004] Field monitoring of tubing conditions in shallow coalbed methane wells revealed that 99% of the retrieved old tubing, having been reused twice, did not meet API 5B standards for thread parameters (thread length and thread tightness). This resulted in gap corrosion at the threaded connections between tubing strings, and increased risk of sticking and breakage during well workovers when the pump was stuck. The field operating conditions involved an internal pressure of approximately 10 MPa in the tubing string, with a tensile strength of 469 kN and an average service life of about 360 days. If the traditional operating method of using large quantities of old tubing with general API oil-based thread grease is followed, unstable sealing and pressure maintenance during initial tubing installation are likely to occur. Therefore, there is an urgent need to develop a special functional tubing thread sealant. This sealant should not only improve the sealing integrity of the tubing string when used with new tubing, sealing leaks in API threads and compensating for inherent sealing deficiencies in API structures, but also overcome issues such as oil stains, rust, and minor thread defects on the surface of old tubing, thus improving the sealing integrity of the tubing string. This can significantly improve the reuse rate of old tubing, extend the life cycle of the tubing string, and reduce the operating and production costs of the oilfield. Summary of the Invention

[0005] This application provides a tubing thread sealant for shallow coalbed methane wells, its preparation method, and its application, in order to solve the following technical problem: how to improve the medium sealing performance of the tubing thread sealant to enhance the sealing integrity performance of the tubing string.

[0006] In a first aspect, embodiments of this application provide a tubing thread sealant for shallow coalbed methane wells, the tubing thread sealant comprising: component A, component B, and component C; wherein...

[0007] By weight, component A comprises the following chemical components: 41 to 61 parts of polymer matrix, 15 to 23 parts of 5-methylthio-7-fluoro-1H-indene, and 23 to 37 parts of excipients;

[0008] By weight, component B comprises the following chemical components: 80-90 parts epoxy curing agent, 10-25 parts epoxy curing accelerator; and

[0009] Component C is an auxiliary agent.

[0010] Optionally, the mass ratio of component A, component B, and component C is 100:(20-30):(10-15).

[0011] Optionally, by weight, the polymer matrix material comprises the following chemical components: 25 to 35 parts epoxy resin, 10 to 16 parts carboxylated nitrile rubber, and 6 to 10 parts nitrile rubber; and / or,

[0012] By weight, the excipients include the following chemical components: 10 to 16 parts carbon black, 12 to 18 parts glass microspheres, and 1 to 3 parts fumed silica.

[0013] Optionally, the carbon black has a particle size of 45 μm to 60 μm; and / or,

[0014] The glass microspheres have a particle size of 45μm to 60μm.

[0015] Optionally, the epoxy curing agent is a polyetheramine; and / or,

[0016] The epoxy curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

[0017] Optionally, by weight, the additives include the following chemical components: 18 to 26 parts trichloroethylene, 45 to 55 parts citric acid, 10 to 20 parts sodium gluconate, and 8 to 16 parts diluent.

[0018] Secondly, this application provides a method for preparing the oil pipe thread sealant according to any one of the first aspects, the method comprising:

[0019] Component A is obtained by mixing epoxy resin, 5-methylthio-7-fluoro-1H-indene, carboxylated nitrile rubber, nitrile rubber, carbon black, glass microspheres and fumed silica.

[0020] The epoxy curing agent and the epoxy curing accelerator are mixed to obtain component B;

[0021] Trichloroethylene, citric acid, sodium gluconate, and diluent are mixed to obtain component C;

[0022] The oil pipe thread sealant is obtained by mixing the components A, B, and C.

[0023] Optionally, the preparation method of the 5-methylthio-7-fluoro-1H-indene includes:

[0024] 6-Bromo-4-fluoro-2,3-dihydro-1H-indanone was dissolved in methanol, and then NaBH4 was added in batches to carry out a reduction reaction to obtain intermediate 1; the temperature of the reduction reaction was 0℃~10℃, and the time of the reduction reaction was 50min~65min.

[0025] The intermediate 1 was dissolved in toluene, and then p-toluenesulfonic acid was added to obtain the first mixture;

[0026] The first mixture is heated to reflux to carry out a dehydration reaction, yielding intermediate 2; the reflux time is 5h to 7h.

[0027] Under nitrogen protection, intermediate 2 was dissolved in tetrahydrofuran, and then n-butyllithium was added dropwise to carry out a stirring reaction to obtain a second mixture; the stirring reaction temperature was -72℃ to -68℃, and the stirring reaction time was 20 min to 40 min.

[0028] A tetrahydrofuran solution of dimethyl disulfide was added to the second mixture to carry out a substitution reaction to obtain the 5-methylthio-7-fluoro-1H-indene; the temperature of the substitution reaction was -72℃ to -68℃, and the time of the substitution reaction was 20 min to 40 min.

[0029] Optionally, the intermediate 1 has the structural formula shown in Formula 1.

[0030]

[0031] The structural formula of the intermediate 2 is shown in Formula 2.

[0032]

[0033] The structural formula of the 5-methylthio-7-fluoro-1H-indene is shown in Formula 3.

[0034]

[0035] Thirdly, this application provides an application of the oil pipe thread sealant according to any one of the first aspects, the application including:

[0036] The tubing thread sealant is applied to the surface of the tubing thread to form a sealing layer; the tubing thread is a shallow coalbed gas well tubing thread.

[0037] The technical solutions provided in this application have the following advantages compared with the prior art:

[0038] This application provides a shallow coalbed methane well tubing thread sealant, comprising three components: A, B, and C. Component A, by weight, comprises the following chemical components: 41-61 parts of a polymer matrix, 15-23 parts of 5-methylthio-7-fluoro-1H-indene, and 23-37 parts of excipients. Component B, by weight, comprises the following chemical components: 80-90 parts of an epoxy curing agent and 10-25 parts of an epoxy curing accelerator. Component C is an additive. Through the three-component design of the tubing thread sealant, component A, as the main body of the sealant, provides the essential structural and functional properties required by the sealant. The main function of component B is to cross-link and cure the polymer matrix in component A, forming a stable network structure and improving the strength and durability of the sealant. The main function of component C is to adjust the viscosity of the sealant, improve its workability, and enhance its corrosion resistance. On the other hand, component A uses a polymer matrix as its base and introduces molecularly designed active substances containing fluorine and sulfur, such as 5-methylthio-7-fluoro-1H-indene. The introduction of fluorine enables the sealant to maintain stable performance under harsh environments such as high temperature, high humidity, and corrosion, making it less prone to aging or failure. The addition of sulfur enhances the sealant's toughness and elasticity, allowing it to better adapt to the minute deformations of the oil pipe threads, thereby improving sealing performance. Thus, it combines the weather resistance and toughness of rubber while simultaneously ensuring stable performance at high temperatures, preventing deformation or failure. This ultimately improves the media sealing performance of the oil pipe thread sealant. Attached Figure Description

[0039] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0040] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1A schematic flowchart illustrating a method for preparing a pipe thread sealant according to an embodiment of this application;

[0042] Figure 2 The chemical reaction formula for preparing 5-methylthio-7-fluoro-1H-indene provided in the embodiments of this application is shown. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0044] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0045] Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. "Parts representation," such as parts by weight or parts by mass, indicates the proportional relationship between components. In the proportional relationships discussed in this article, parameters described by proportion should be understood as the first term of the proportion in the order of description, while the proportion figure should be understood as the second term. For example, if the mass ratio of substance A, substance B, and substance C is 1:2:3, then substances A, B, and C should correspond one-to-one with the proportion figure in the proportion in the order of description, i.e., the mass of substance A : the mass of substance B : the mass of substance C = 1:2:3.

[0046] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0047] This application provides a tubing thread sealant for shallow coalbed methane wells, the tubing thread sealant comprising: component A, component B, and component C; wherein...

[0048] By weight, component A comprises the following chemical components: 41 to 61 parts of polymer matrix, 15 to 23 parts of 5-methylthio-7-fluoro-1H-indene, and 23 to 37 parts of excipients;

[0049] By weight, component B comprises the following chemical components: 80-90 parts epoxy curing agent, 10-25 parts epoxy curing accelerator; and

[0050] Component C is an auxiliary agent.

[0051] In some embodiments, the polymer matrix material, by weight, comprises the following chemical components: 25 to 35 parts epoxy resin, 10 to 16 parts carboxylated nitrile rubber, and 6 to 10 parts nitrile rubber; and / or,

[0052] By weight, the excipients include the following chemical components: 10 to 16 parts carbon black, 12 to 18 parts glass microspheres, and 1 to 3 parts fumed silica.

[0053] The functions of each chemical component in component A are as follows:

[0054] Epoxy resin: As the main component of the sealant, it provides stable structural support, ensuring sufficient strength and rigidity after curing. Simultaneously, it exhibits good adhesion to various materials such as metals and plastics, ensuring a tight connection between oil pipe threads. Furthermore, it can improve the tensile strength, flexural strength, and compressive strength of the sealant, enabling it to withstand various mechanical stresses. For example, the weight parts of epoxy resin can be 25 parts, 27 parts, 29 parts, 30 parts, 32 parts, 34 parts, 35 parts, etc.

[0055] 5-Methylthio-7-fluoro-1H-indene: Fluorine atoms possess extremely high electronegativity, significantly improving the chemical stability and corrosion resistance of materials, especially in acidic or alkaline environments. Simultaneously, the introduction of sulfur enhances the material's oxidation resistance, preventing aging under high temperature or light exposure conditions. The combined effect of fluorine and sulfur allows the material to maintain stable properties at high temperatures, resisting deformation or failure. For example, the weight parts of 5-methylthio-7-fluoro-1H-indene can be 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 22 parts, 23 parts, etc.

[0056] Carboxylated nitrile butadiene rubber (CBR): Forms an interpenetrating network structure with epoxy resin, giving the sealant better elasticity and toughness after curing, allowing it to adapt to minor deformations between oil pipe threads. Simultaneously, CBR exhibits excellent oil resistance, preventing corrosion of the sealant by oily media. Furthermore, it has good adhesion to metal surfaces, ensuring the sealant forms a strong adhesive layer on the oil pipe threads. For example, the CBR can be present in quantities of 10 to 16 parts by weight.

[0057] Nitrile rubber: The addition of nitrile rubber further enhances the sealant's toughness, giving it better impact resistance. Simultaneously, it works synergistically with carboxylated nitrile rubber to improve the sealant's overall performance, including strength, toughness, and oil resistance. For example, the nitrile rubber can be present in parts by weight of 6, 7, 8, 9, or 10 parts.

[0058] Carbon black: As a filler, carbon black can significantly improve the strength and hardness of sealants, making them more durable. At the same time, the addition of carbon black can enhance the abrasion resistance of the sealant, preventing it from wearing away during long-term use. Carbon black: 10 parts to 16 parts.

[0059] Glass microspheres: As a filler, glass microspheres can reduce the cost of sealants while maintaining their good performance. Simultaneously, when threaded onto oil pipe threads, glass microspheres provide lubrication, reducing resistance and making operation smoother. For example, the weight parts of the glass microspheres can be 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, etc.

[0060] Fumed silica: As a thickener, fumed silica can adjust the consistency of sealants, making them easier to process and apply. Simultaneously, the addition of fumed silica can enhance the thixotropy of the sealant, allowing it to maintain a certain consistency when at rest, while becoming more fluid under shear force. Furthermore, fumed silica can improve the stability of the sealant, preventing it from delaminating or deteriorating during long-term storage. For example, the weight parts of fumed silica can be 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, etc.

[0061] In summary, the various chemical components of component A are cleverly combined through molecular design to form a pipe thread sealant with weather resistance, media resistance, and high sealing performance. The introduction of fluorine atoms and sulfur significantly improves the material's heat resistance, oxidation resistance, oil resistance, and corrosion resistance, enabling it to withstand harsh working conditions. Simultaneously, the addition of carboxyl-based nitrile rubber and nitrile rubber enhances the system's toughness, while carbon black and glass microspheres provide strength and lubricity, and fumed silica adjusts the system's consistency. The synergistic effect of these components gives this invention excellent overall performance, meeting the stringent requirements of pipe thread sealing.

[0062] In some embodiments, the carbon black has a particle size of 45 μm to 60 μm; and / or,

[0063] The glass microspheres have a particle size of 45μm to 60μm.

[0064] By limiting the particle size of carbon black to 45μm to 60μm and the particle size of glass microspheres to 45μm to 60μm, the voids in the sealant can be filled more effectively, improving the overall density and strength. For example, the particle size of carbon black can be 45μm, 48μm, 50μm, 52μm, 55μm, 58μm, 60μm, etc., and the particle size of glass microspheres can be 45μm, 48μm, 50μm, 52μm, 55μm, 58μm, 60μm, etc.

[0065] In some embodiments, the epoxy curing agent is a polyetheramine; and / or,

[0066] The epoxy curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

[0067] The functions of each chemical component in component B are as follows:

[0068] Epoxy curing agent: The epoxy curing agent is a key component in the sealant curing process. It reacts chemically with the epoxy resin in component A to form a cross-linked network structure, transforming the sealant from a liquid to a solid state, resulting in excellent mechanical properties and chemical stability. Simultaneously, the cured sealant exhibits higher tensile strength, compressive strength, and shear strength, enabling it to withstand various mechanical stresses between oil pipe threads. For example, the epoxy curing agent can be present in weight proportions of 80 parts, 82 parts, 84 parts, 86 parts, 88 parts, 90 parts, etc.

[0069] Epoxy curing accelerators: Epoxy curing accelerators can significantly reduce the activation energy of the curing reaction, accelerate the chemical reaction between epoxy resin and curing agent, and shorten the curing time of sealant. For example, the weight parts of epoxy curing accelerators can be 10 parts, 15 parts, 20 parts, 22 parts, 25 parts, etc.

[0070] In some embodiments, the additives, by weight, include the following chemical components: 18 to 26 parts trichloroethylene, 45 to 55 parts citric acid, 10 to 20 parts sodium gluconate, and 8 to 16 parts diluent.

[0071] The functions of each chemical component in additive C are as follows:

[0072] Trichloroethylene: Trichloroethylene has good solubility and volatility, and can act as a solvent to help other components disperse better in the polymer matrix, improving the uniformity and stability of the sealant. Simultaneously, during the sealant curing process, the volatilization of trichloroethylene helps form a denser cured structure, improving sealing performance. For example, the trichloroethylene can be present in parts by weight of 18, 20, 22, 24, or 26 parts, etc.

[0073] Citric acid: Citric acid is an organic acid with excellent chelating and corrosion-inhibiting properties. In sealants, it can act as a corrosion inhibitor, preventing corrosion of metal components such as oil pipe threads in humid or corrosive environments. Furthermore, citric acid can form complexes with certain metal ions, helping to improve the adhesion between the sealant and the metal surface. For example, the citric acid can be present in parts by weight of 45, 47, 49, 50, 52, 55, etc.

[0074] Sodium gluconate: Sodium gluconate is a polyhydroxycarboxylate with excellent corrosion inhibition and dispersing properties. In sealants, it can act as a corrosion inhibitor, synergistically working with citric acid to further improve the sealant's corrosion resistance. Simultaneously, sodium gluconate can also improve the sealant's flowability, helping to form a more uniform coating between tubing threads. For example, the sodium gluconate can be present in parts by weight of 10, 12, 14, 16, 18, or 20 parts.

[0075] Thinner: The main function of the thinner is to adjust the viscosity of the sealant, making it easier to apply and coat. During preparation, an appropriate amount of thinner ensures the sealant has good flowability and penetration, effectively filling the tiny gaps between oil pipe threads. Simultaneously, the evaporation of the thinner helps the sealant form a denser structure during curing. For example, the thinner can be present in parts by weight of 8, 10, 12, 14, or 16 parts, etc.

[0076] The components of Additive C work synergistically within specified ranges to enhance the performance of the tubing thread sealant. The solubility and volatility of trichloroethylene contribute to a denser, cured structure; the corrosion-inhibiting properties of citric acid and sodium gluconate improve the sealant's corrosion resistance; and the diluent adjusts the sealant's viscosity, making it easier to apply and coat. The combined effect of these components gives the tubing thread sealant excellent weather resistance, media resistance, and high sealing performance, meeting the requirements for use in harsh environments such as shallow coalbed methane wells.

[0077] In some embodiments, the mass ratio of component A, component B, and component C is 100:(20-30):(10-15).

[0078] Component A, as the main component of the sealant, provides the essential structural and functional properties required for the sealant. Component B's main function is to cross-link and solidify the polymer matrix material in component A, forming a stable network structure. Component C's main function is to adjust the sealant's viscosity, improve its workability, and enhance its corrosion resistance. When components A, B, and C are mixed in a mass ratio of 100:(20-30):(10-15), complex chemical and physical reactions occur between them, collectively forming a high-performance tubing thread sealant. This sealant not only possesses good weather resistance, media resistance, and high sealing performance, but also excellent workability and corrosion resistance. Furthermore, by adjusting the proportions of each component, the sealant's performance can be further optimized to meet the requirements of different well conditions and construction processes. For example, the mass ratio of component A, component B and component C can be 100:20:10, 100:22:10, 100:24:10, 100:25:10, 100:26:10, 100:28:10, 100:30:10, 100:25:11, 100:25:12, 100:25:13, 100:25:14, 100:25:15, etc.

[0079] Figure 1 This is a schematic flowchart illustrating a method for preparing a pipe thread sealant according to an embodiment of this application.

[0080] Based on a general inventive concept, such as Figure 1 As shown, this application provides a method for preparing the oil pipe thread sealant according to any one of the above claims, the method comprising:

[0081] S1. Epoxy resin, 5-methylthio-7-fluoro-1H-indene, carboxylated nitrile rubber, nitrile rubber, carbon black, glass microspheres and fumed silica are mixed to obtain component A.

[0082] S2. Mix the epoxy curing agent and the epoxy curing accelerator to obtain component B;

[0083] S3. Mix trichloroethylene, citric acid, sodium gluconate and diluent to obtain component C;

[0084] S4. Mix the components A, B and C to obtain the oil pipe thread sealant.

[0085] In some embodiments, the preparation method of the 5-methylthio-7-fluoro-1H-indene includes:

[0086] 6-Bromo-4-fluoro-2,3-dihydro-1H-indanone was dissolved in methanol, and then NaBH4 was added in batches to carry out a reduction reaction to obtain intermediate 1; the temperature of the reduction reaction was 0℃~10℃, and the time of the reduction reaction was 50min~65min.

[0087] The intermediate 1 was dissolved in toluene, and then p-toluenesulfonic acid was added to obtain the first mixture;

[0088] The first mixture is heated to reflux to carry out a dehydration reaction, yielding intermediate 2; the reflux time is 5h to 7h.

[0089] Under nitrogen protection, intermediate 2 was dissolved in tetrahydrofuran, and then n-butyllithium was added dropwise to carry out a stirring reaction to obtain a second mixture; the stirring reaction temperature was -72℃ to -68℃, and the stirring reaction time was 20 min to 40 min.

[0090] A tetrahydrofuran solution of dimethyl disulfide was added to the second mixture to carry out a substitution reaction to obtain the 5-methylthio-7-fluoro-1H-indene; the temperature of the substitution reaction was -72℃ to -68℃, and the time of the substitution reaction was 20 min to 40 min.

[0091] In some embodiments, the intermediate 1 has the structural formula shown in Formula 1.

[0092]

[0093] The structural formula of the intermediate 2 is shown in Formula 2.

[0094]

[0095] The structural formula of the 5-methylthio-7-fluoro-1H-indene is shown in Formula 3.

[0096]

[0097] The product prepared by the method of preparing the oil pipe thread sealant is the oil pipe thread sealant mentioned above. The chemical composition and microstructure of the oil pipe thread sealant prepared by the method of preparing the oil pipe thread sealant can be referred to the above embodiments. Since the method of preparing the oil pipe thread sealant adopts some or all of the technical solutions of the oil pipe thread sealant embodiments, it has at least all the beneficial effects brought about by the technical solutions of the oil pipe thread sealant embodiments, which will not be elaborated here.

[0098] The oil pipe thread sealant and its preparation method provided in this application have many significant advantages, mainly reflected in the following aspects:

[0099] (1) Excellent weather resistance and corrosion resistance. Fluorine and sulfur atoms are introduced into the sealant through the molecular design of 5-methylthio-7-fluoro-1H-indene. Fluorine atoms have extremely high electronegativity, which can significantly improve the chemical stability and corrosion resistance of the material, especially in acidic or alkaline environments. The introduction of sulfur enhances the material's oxidation resistance, preventing aging under high temperature or light conditions. This design allows the sealant to maintain stable performance under harsh working conditions, making it less prone to deformation or failure. Simultaneously, citric acid and sodium gluconate in additive C act as corrosion inhibitors, further improving the sealant's corrosion resistance. They can form complexes with metal ions, preventing corrosion of metal parts such as oil pipe threads in humid or corrosive environments, thereby extending the service life of the oil pipe.

[0100] (2) High sealing performance and strength. The polymer matrix material in component A includes epoxy resin, carboxylated nitrile rubber, and nitrile rubber. These components form an interpenetrating network structure, giving the sealant better elasticity and toughness after curing, enabling it to adapt to minor deformations between oil pipe threads. Simultaneously, they provide stable structural support, ensuring sufficient strength and rigidity of the sealant after curing. Furthermore, carbon black and glass microspheres, as fillers, significantly improve the strength and hardness of the sealant, making it more durable. The addition of carbon black also enhances the sealant's abrasion resistance, preventing wear during long-term use. Glass microspheres provide lubrication when threading the oil pipe threads, reducing resistance and making operation smoother.

[0101] (3) Good workability and processability. The trichloroethylene and diluent in Additive C adjust the viscosity of the sealant, making it easier to apply and coat. During preparation, an appropriate amount of diluent ensures the sealant has good flowability and penetration, fully filling the tiny gaps between the tubing threads. Simultaneously, the volatilization of trichloroethylene helps the sealant form a denser structure during curing. Furthermore, the preparation method of this application is relatively simple and easy to industrialize. By mixing components A, B, and C in a certain proportion, a tubing thread sealant with excellent performance can be obtained.

[0102] (4) Wide range of applications. The tubing thread sealant of this application is particularly suitable for sealing tubing threads in harsh environments such as shallow coalbed methane wells. It can work with tubing threads to seal thread leakage gaps, improve the sealing performance of the tubing string, and thus ensure the safe operation of the oil well. At the same time, this sealant can be used not only with new tubing threads, but also with old tubing threads, meeting the requirements of various well conditions and construction conditions.

[0103] (5) Environmental protection and sustainability. During preparation and use, the sealant of this application exhibits low volatility, reducing environmental pollution. Furthermore, after reaching its service life, the sealant's components can be recycled and reused through appropriate treatment, reducing resource waste.

[0104] In summary, the tubing thread sealant and its preparation method of this application possess numerous advantages, including excellent weather resistance, corrosion resistance, high sealing performance and strength, good workability and processability, wide application range, and environmental friendliness and sustainability. These advantages make this sealant a promising candidate for sealing tubing threads in harsh environments such as shallow coalbed methane wells.

[0105] Based on a general inventive concept, this application provides an application of the oil pipe thread sealant described in any one of the above claims, the application including:

[0106] The tubing thread sealant is applied to the surface of the tubing thread to form a sealing layer; the tubing thread is a shallow coalbed gas well tubing thread.

[0107] This application presents a three-component product. The three components are primarily based on epoxy resin, incorporating molecularly designed active substances containing fluorine and sulfur elements. By combining the weather resistance and toughness of rubber, a fiberglass thread sealant with long-term weather resistance, corrosion resistance, media sealing performance, and resistance to long-term high-frequency vibration has been invented. It can be used with oil pipe threads to seal thread leakage gaps and can also be used with existing oil pipe threads to improve the sealing performance of oil pipe strings.

[0108] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0109] Example 1

[0110] This application provides a tubing thread sealant for shallow coalbed methane wells, the tubing thread sealant comprising: component A, component B, and component C; wherein...

[0111] The components of Component A by weight are: 30 parts of E-51 epoxy resin (Phoenix brand epoxy resin), 19 parts of 5-methylthio-7-fluoro-1H-indene, 13 parts of carboxylated nitrile rubber (Lanzhou Petrochemical), 8 parts of nitrile rubber-40 (Lanzhou Petrochemical), 13 parts of carbon black (Cabot Carbon Black N550 from the United States), 15 parts of glass microspheres, and 2 parts of fumed silica (Degussa A380).

[0112] The components of component B are as follows by weight: 85 parts of polyetheramine (D2000 / MA2200, Changde New Material Technology Co., Ltd.) and 15 parts of DMP-30.

[0113] The components of Component C are as follows by weight: 23 parts trichloroethylene, 50 parts citric acid, 15 parts sodium gluconate, and 12 parts 501 diluent.

[0114] The preparation method of the oil pipe thread sealant is as follows: Prepare 5-methylthio-7-fluoro-1H-indene, then add it sequentially according to the above-mentioned proportion of component A and mix and stir for 3.2 hours to prepare component A; Component B is prepared by mixing and stirring for 2.2 hours according to the above proportion; Component C is prepared by mixing and stirring the above components for 2.2 hours. After the preparation of components A, B, and C, before use, mix components A and B first according to the ratio of component A: component B: component C = 100:25:12, then add component C, mix the three together evenly, and then apply evenly to the surface of the oil pipe thread using the provided brush.

[0115] Figure 2 The chemical reaction formula for preparing 5-methylthio-7-fluoro-1H-indene provided in the embodiments of this application is shown.

[0116] like Figure 2 As shown, 5-methylthio-7-fluoro-1H-indene in component A is prepared according to the following method:

[0117] Step 1: 20 g of 6-bromo-4-fluoro-2,3-dihydro-1H-inden-1-one was dissolved in 250 mL of methanol, cooled to 0 °C, and 3 g of NaBH4 was added in portions. After the addition was complete, the mixture was allowed to react at this temperature for 1 h. The reaction was quenched with 25 mL of water, and the solution was concentrated under reduced pressure and evaporated to dryness. 200 mL of ethyl acetate was added to the resulting oil, and the mixture was washed with 100 mL of saturated brine. The organic phase was dried over anhydrous sodium sulfate, filtered, and the filtrate was concentrated under reduced pressure to give 20 g of a pale yellow oil, with a yield of 92%.

[0118] Step 2: Dissolve intermediate 1 (15g) in anhydrous toluene (100mL) and add a water separator. Heat the reaction to reflux and react for 6 hours. After the reaction is complete, cool to room temperature, evaporate the reaction solution to dryness, and purify the crude product by silica gel column chromatography to obtain 12g of yellow liquid, yield 80%.

[0119] Step 3: Dissolve intermediate 2 (8g) in anhydrous THF (100mL), cool to -70℃ under nitrogen protection, add n-butyllithium (20mL) dropwise, and stir at -70℃ for 0.5 hours. Add a THF (50mL) solution of dimethyl disulfide (4.5g), and stir at this temperature for 0.5 hours after the addition is complete. Quench the reaction with saturated ammonium chloride solution (10mL), concentrate the resulting solution under reduced pressure, and purify by silica gel column chromatography to obtain 5.5g of a yellow oily substance, with a yield of 70%. Product 3 is 5-methylthio-7-fluoro-1H-indene.

[0120] Example 2

[0121] This application provides a tubing thread sealant for shallow coalbed methane wells, the tubing thread sealant comprising: component A, component B, and component C; wherein...

[0122] The components of Component A by weight are: 28 parts of E-51 epoxy resin (Phoenix brand epoxy resin), 20 parts of 5-methylthio-7-fluoro-1H-indene, 13 parts of carboxylated nitrile rubber (Lanzhou Petrochemical), 8 parts of nitrile rubber-40 (Lanzhou Petrochemical), 13 parts of carbon black (Cabot Carbon Black N550 from the United States), 16 parts of glass microspheres, and 2 parts of fumed silica (Degussa A380).

[0123] The components of component B are as follows by weight: 83 parts of polyetheramine (D2000 / MA2200, Changde New Material Technology Co., Ltd.) and 17 parts of DMP-30.

[0124] The components of component C, by weight, are: 20 parts trichloroethylene, 52 parts citric acid, 14 parts sodium gluconate, and 14 parts 501 diluent.

[0125] The preparation method of the oil pipe thread sealant is as follows: 5-methylthio-7-fluoro-1H-indene is prepared according to the method of Example 1. Then, it is added sequentially according to the above proportion of component A and mixed and stirred for 3.2 hours to prepare component A. Component B is prepared by mixing and stirring for 2.2 hours according to the above proportion. Component C is prepared by mixing and stirring the above components for 2.2 hours. After the preparation of components A, B, and C, before use, components A and B are mixed first according to the ratio of component A: component B: component C = 100:26:13. Then, component C is added and mixed evenly. It can then be used by applying it evenly to the surface of the oil pipe thread using the provided brush.

[0126] Example 3

[0127] This application provides a tubing thread sealant for shallow coalbed methane wells, the tubing thread sealant comprising: component A, component B, and component C; wherein...

[0128] The components of Component A by weight are: 32 parts of E-51 epoxy resin (Phoenix brand epoxy resin), 17 parts of 5-methylthio-7-fluoro-1H-indene, 13 parts of carboxylated nitrile rubber (Lanzhou Petrochemical), 8 parts of nitrile rubber-40 (Lanzhou Petrochemical), 11 parts of carbon black (Cabot Carbon Black N550 from the United States), 17 parts of glass microspheres, and 2 parts of fumed silica (Degussa A380).

[0129] The components of component B are as follows by weight: 85 parts of polyetheramine (D2000 / MA2200, Changde New Material Technology Co., Ltd.) and 15 parts of DMP-30.

[0130] The components of Component C by weight are: 23 parts trichloroethylene, 51 parts citric acid, 12 parts sodium gluconate, and 14 parts 501 diluent.

[0131] The preparation method of the oil pipe thread sealant is as follows: 5-methylthio-7-fluoro-1H-indene is prepared according to the method of Example 1. Then, it is added sequentially according to the above proportion of component A and mixed and stirred for 3.2 hours to prepare component A. Component B is prepared by mixing and stirring for 2.2 hours according to the above proportion. Component C is prepared by mixing and stirring the above components for 2.2 hours. After the preparation of components A, B, and C, before use, components A and B are mixed first according to the ratio of component A: component B: component C = 100:25:13. Then, component C is added and mixed evenly. It can then be used by applying it evenly to the surface of the oil pipe thread using the provided brush.

[0132] Comparative Example 1

[0133] Based on the disclosure in Example 1, the following modifications are made:

[0134] 5-Methylthio-7-fluoro-1H-indene is not added to component A.

[0135] Comparative Example 2

[0136] Based on the disclosure in Example 1, the following modifications are made:

[0137] The components of Component A by weight are: 30 parts of E-51 epoxy resin (Phoenix brand epoxy resin), 5 parts of 5-methylthio-7-fluoro-1H-indene, 13 parts of carboxylated nitrile rubber (Lanzhou Petrochemical), 8 parts of nitrile rubber-40 (Lanzhou Petrochemical), 13 parts of carbon black (Cabot Carbon Black N550 from the United States), 15 parts of glass microspheres, and 2 parts of fumed silica (Degussa A380).

[0138] Comparative Example 3

[0139] Based on the disclosure in Example 1, the following modifications are made:

[0140] Nitrile rubber-40 is not added to component A.

[0141] The performance of the oil pipe thread sealants obtained in Examples 1-3 and Comparative Examples 1-3 was tested, and the results are shown in Table 1.

[0142] Table 1. Performance of the tubing thread sealants in Examples 1-3 and Comparative Examples 1-3

[0143]

[0144] As shown in Table 1, the density of the oil pipe thread sealant obtained in the example is 1.1 g / cm³. 3 ~1.2g / cm 3 With a curing strength >1 N·M, it can still achieve curing strength even when there is rust on the thread surface, which directly proves its ability to overcome and seal rust and oil stains on the thread surface. In addition, its low-temperature coating and storage performance can also adapt to different working conditions and reasonable storage period requirements.

[0145] Furthermore, one or more technical solutions in the embodiments of this application have at least the following technical effects or advantages:

[0146] In this embodiment, the sealant can not only be used with new tubing to improve the sealing integrity of the tubing string, seal leakage gaps in API threads, and compensate for the inherent sealing deficiencies of API structures, but also be used with old tubing to overcome problems such as oil stains, corrosion, and minor thread defects on the surface of old tubing, thereby improving the sealing integrity requirements of the tubing string. This significantly increases the reuse rate of old tubing, extends the entire lifespan of the tubing string, and reduces the operating and production costs of the oilfield.

[0147] In this embodiment, using epoxy resin and carboxylated nitrile rubber as the matrix, new active functional groups containing fluorine and sulfur elements were introduced through molecular design, resulting in a three-component oil pipe thread sealant with weather resistance, media resistance, and high sealing performance.

[0148] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A thread sealant for tubing in shallow coalbed methane wells, the thread sealant comprising: Components A, B, and C; among which... By weight, component A comprises the following chemical components: 41 to 61 parts of polymer matrix, 15 to 23 parts of 5-methylthio-7-fluoro-1H-indene, and 23 to 37 parts of excipients; By weight, component B comprises the following chemical components: 80-90 parts epoxy curing agent, 10-25 parts epoxy curing accelerator; and Component C is an auxiliary agent.

2. The oil pipe thread sealant according to claim 1, characterized in that, The mass ratio of component A, component B and component C is 100:(20-30):(10-15).

3. The oil pipe thread sealant according to claim 1, characterized in that, By weight, the polymer matrix material comprises the following chemical components: 25-35 parts epoxy resin, 10-16 parts carboxylated nitrile rubber, and 6-10 parts nitrile rubber; and / or, By weight, the excipients include the following chemical components: 10 to 16 parts carbon black, 12 to 18 parts glass microspheres, and 1 to 3 parts fumed silica.

4. The oil pipe thread sealant according to claim 3, characterized in that, The carbon black has a particle size of 45 μm to 60 μm; and / or, The glass microspheres have a particle size of 45μm to 60μm.

5. The oil pipe thread sealant according to claim 1, characterized in that, The epoxy curing agent is polyetheramine; and / or... The epoxy curing accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

6. The oil pipe thread sealant according to claim 1, characterized in that, The additives, by weight, comprise the following chemical components: 18 to 26 parts trichloroethylene, 45 to 55 parts citric acid, 10 to 20 parts sodium gluconate, and 8 to 16 parts diluent.

7. A method for preparing a tubing thread sealant according to any one of claims 1 to 6, the method comprising: Component A is obtained by mixing epoxy resin, 5-methylthio-7-fluoro-1H-indene, carboxylated nitrile rubber, nitrile rubber, carbon black, glass microspheres and fumed silica. The epoxy curing agent and the epoxy curing accelerator are mixed to obtain component B; Trichloroethylene, citric acid, sodium gluconate, and diluent are mixed to obtain component C; The oil pipe thread sealant is obtained by mixing the components A, B, and C.

8. The method according to claim 7, characterized in that, The preparation method of the 5-methylthio-7-fluoro-1H-indene includes: 6-Bromo-4-fluoro-2,3-dihydro-1H-indanone was dissolved in methanol, and then NaBH4 was added in batches to carry out a reduction reaction to obtain intermediate 1; the temperature of the reduction reaction was 0℃~10℃, and the time of the reduction reaction was 50min~65min. The intermediate 1 was dissolved in toluene, and then p-toluenesulfonic acid was added to obtain the first mixture; The first mixture is heated to reflux to carry out a dehydration reaction, yielding intermediate 2; the reflux time is 5h to 7h. Under nitrogen protection, intermediate 2 was dissolved in tetrahydrofuran, and then n-butyllithium was added dropwise to carry out a stirring reaction to obtain a second mixture; the stirring reaction temperature was -72℃ to -68℃, and the stirring reaction time was 20 min to 40 min. A tetrahydrofuran solution of dimethyl disulfide was added to the second mixture to carry out a substitution reaction to obtain the 5-methylthio-7-fluoro-1H-indene; the temperature of the substitution reaction was -72℃ to -68℃, and the time of the substitution reaction was 20 min to 40 min.

9. The method according to claim 8, characterized in that, The structural formula of the intermediate 1 is shown in Formula 1. The structural formula of the intermediate 2 is shown in Formula 2. The structural formula of the 5-methylthio-7-fluoro-1H-indene is shown in Formula 3.

10. The application of the oil pipe thread sealant according to any one of claims 1 to 6, the application comprising: The tubing thread sealant is applied to the surface of the tubing thread to form a sealing layer; the tubing thread is a shallow coalbed gas well tubing thread.

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