Modified polyamide drill rod and processing technology thereof

Abstract

The invention relates to the technical field of drill rods, and particularly discloses a modified polyamide drill rod and a processing technology thereof. The modified polyamide drill rod is prepared from the following raw materials in parts by weight: 80 to 100 parts of modified polyamide, 10 to 15 parts of aramid fiber, 40 to 60 parts of glass fiber, 2 to 6 parts of nano silicon dioxide, 10 to 20 parts of cellulose nanocrystal and 2 to 6 parts of maleic anhydride graft. The highest tensile strength, elasticity modulus and elongation at break of the modified polyamide drill rod prepared by the invention are 183MPa, 12.0 Gpa and 39.1% respectively, the lowest volume wear rate is 2.0 * 10 <-5 > mm / (N.m), and the mechanical property and wear resistance of the polyamide drill rod are improved.

Description

Technical Field

[0001] The present application relates to the field of drill rods, and more specifically, to a modified polyamide drill rod and a processing technology thereof. Background Art

[0002] Drill pipe is a steel pipe with a threaded tail end, used to connect the drilling rig's surface equipment to the drilling and grinding equipment or bottom hole device at the bottom of the well. It is primarily used to transport drilling mud to the drill bit and to raise, lower, or rotate the bottom hole device together with the drill bit. It is widely used in oil and gas production. During use, drill pipe must withstand enormous internal and external pressure, twisting, bending, and vibration. To meet the requirements for wear resistance and mechanical strength of drill pipe in drilling construction, iron drill pipe is usually selected. However, iron drill pipe is heavy, which will increase equipment load and energy consumption, make transportation and operation more difficult, and also limit drilling efficiency. Therefore, while meeting the use requirements, lightweighting of drill pipe has become an important research direction for drill pipe.

[0003] In related technologies, in order to meet the lightweight requirements of drill pipes, polyamide is selected as the main drill pipe material. Although it meets the lightweight requirements, its mechanical strength and wear resistance are still relatively weak, which makes it difficult to meet the actual use requirements. It can only be limited to short-term operations in shallow low-pressure, low-temperature or corrosive environments. Summary of the Invention

[0004] In order to improve the wear resistance and mechanical strength of a drill rod, the present application provides a modified polyamide drill rod and a processing technology thereof.

[0005] In a first aspect, the present application provides a modified polyamide drill pipe, which adopts the following technical solution: A modified polyamide drill rod comprises the following raw materials in parts by weight: 80-100 parts of modified polyamide, 10-15 parts of aramid fiber, 40-60 parts of glass fiber, 2-6 parts of nano-silicon dioxide, 10-20 parts of cellulose nano-whiskers, and 2-6 parts of maleic anhydride grafts.

[0006] The raw materials for the modified polyamide drill pipe of the present application can be selected from 80-100 parts of modified polyamide, 10-15 parts of aramid fiber, 40-60 parts of glass fiber, 2-6 parts of nano-silica, 10-20 parts of cellulose nanowhiskers, and 2-6 parts of maleic anhydride grafts, and any value within the respective ranges can be selected, which can improve the mechanical strength and wear resistance of the drill pipe to varying degrees.

[0007] By adopting the above technical solution, polyamide itself has high strength and can withstand the tensile, torsional and compressive stresses during the drilling process while meeting the lightweight requirements of the drill pipe. In addition, polyamide is used as the main raw material, which has natural resistance to corrosive media such as acids, alkalis, and brine, and can avoid rust and electrochemical corrosion problems of the drill pipe. In addition, polyamide has a low friction coefficient, which can reduce friction and wear with the well wall or casing, and has high wear resistance.

[0008] Aramid fiber has high strength and modulus, and its addition enhances the compressive strength of drill pipe. Glass fiber supports stress and inhibits deformation in modified polyamide drill pipe, improving its tensile strength and wear resistance. Aramid and glass fibers form a composite structure, with glass fiber enhancing the overall strength of the drill pipe and aramid fiber providing localized toughness. The addition of aramid fiber also reduces the amount of glass fiber used, ensuring a lighter drill pipe.

[0009] The addition of nano-silica can, on the one hand, fill the overall defects of the modified polyamide and improve the wear resistance. On the other hand, it can also improve the interface bonding between aramid fiber and glass fiber and modified polyamide, forming a multi-scale reinforced network with aramid fiber and glass fiber. Aramid fiber and glass fiber provide the main stress bearing capacity, and nano-silica can inhibit micro-cracks in the drill pipe, thereby improving the mechanical strength and wear resistance of the drill pipe.

[0010] Cellulose nanowhiskers have higher tensile strength and modulus, are easier to disperse, and can improve the mechanical strength of the drill pipe. The fiber network structure of cellulose nanocrystals can absorb impact and improve the brittleness of the drill pipe.

[0011] Maleic anhydride grafted products can improve the interfacial adhesion between aramid fiber, glass fiber, nano-silica, nano-cellulose and modified polyamide, ensuring the role of each raw material, thereby improving the wear resistance and mechanical strength of the drill pipe.

[0012] Preferably, a modified polyamide drill pipe comprises the following raw materials in parts by weight: 85-95 parts of modified polyamide, 12-14 parts of aramid fiber, 45-55 parts of glass fiber, 3-5 parts of nano-silicon dioxide, 14-17 parts of cellulose nanowhiskers, and 3-5 parts of maleic anhydride grafts.

[0013] The modified polyamide drill rod of the present application can be made of 85-95 parts of modified polyamide, 12-14 parts of aramid fiber, 45-55 parts of glass fiber, 3-5 parts of nano-silica, 14-17 parts of cellulose nanowhiskers, and 3-5 parts of maleic anhydride grafts, and any value within the respective ranges can be selected, which can improve the wear resistance and mechanical strength of the drill rod to varying degrees.

[0014] Preferably, the weight ratio of the aramid fiber to the glass fiber is 1:(5-10).

[0015] By adopting the above solution and adjusting the weight ratio of aramid fiber to glass fiber, the overall mechanical strength and local toughness of the drill rod can be further ensured, thereby improving the wear resistance and mechanical strength of the drill rod.

[0016] As a preference: the specific modification method of the modified polyamide is: S1. Mixing graphene oxide and sodium stearate, adding them to water, and stirring them evenly with a magnetic stirrer at 50-70° C. to obtain a graphene oxide dispersion; S2, melting the polyamide monomer at 220-240° C., adding sodium hydroxide with stirring, vacuum drying, adding the graphene oxide dispersion at 125-135° C. and stirring uniformly at a constant temperature, adding adipic acid and glutaric acid, polymerizing under nitrogen at 230-260° C., extruding, cooling, and pelletizing to obtain a modified polyamide; The mass ratio of graphene oxide to sodium stearate is 1:(0.5-1.5); the volume ratio of the graphene oxide mass to water is 1:(4-6); the mass ratio of the graphene oxide dispersion to the polyamide monomer is 1:(8-12); the mass ratio of sodium hydroxide to the polyamide monomer is 1:(0.001-0.01); and the mass ratio of the total mass of adipic acid and glutaric acid to the polyamide monomer is 1:(97-99).

[0017] Wherein, the polyamide monomer can be caprolactam monomer.

[0018] By adopting the above scheme and modifying polyamide with graphene oxide, the mechanical strength and wear resistance of the polyamide can be improved while also meeting the lightweight requirements of the drill pipe. Furthermore, the addition of sodium hydroxide to the polyamide monomer after melting activates the monomer and removes moisture, inducing rapid chain growth and increasing molecular weight, thus providing optimal reaction conditions for subsequent ring-opening polymerization. The addition of sodium hydroxide during vacuum drying is intended to remove residual moisture and prevent bubbles from forming during subsequent high-temperature polymerization, which could affect the density of the modified polyamide.

[0019] After the polyamide monomer and the graphene oxide dispersion are mixed, glutaric acid is added to enhance the interfacial bonding between the graphene oxide and the polyamide monomer. In addition, the carboxyl group of glutaric acid can also form hydrogen bonds with the polyamide monomer, reducing the agglomeration of graphene oxide, thereby improving the uniformity of the modified polyamide and ensuring the mechanical strength and wear resistance of the modified polyamide.

[0020] In addition, after the polyamide monomer is mixed with the graphene oxide dispersion, adipic acid is also added. The adipic acid chain is longer, which introduces more flexibility and can improve the toughness and impact strength of the modified polyamide. The glutaric acid chain is shorter, which can increase the cross-linking density and interfacial bonding strength, and improve the rigidity and thermal stability of the modified polyamide. The combined addition of the two can further optimize the interfacial bonding strength and mechanical strength.

[0021] Preferably, the mass ratio of adipic acid to glutaric acid is 1:(2-3).

[0022] By adopting the above technical solution and adjusting the mass ratio of adipic acid to glutaric acid, the interfacial bonding strength and mechanical strength of the modified polyamide can be further improved, thereby improving the mechanical strength of the drill pipe.

[0023] Preferably, the modified polyamide drill rod further comprises the following raw materials in parts by weight: 0.1-0.3 parts of epoxy resin.

[0024] By adopting the above technical solution and adding epoxy resin, the polar properties of the epoxy resin cooperate with the polar anhydride groups of the maleic anhydride graft to improve the dispersibility of the maleic anhydride graft in the drill pipe raw material. The epoxy resin can also react with raw materials such as aramid fiber and glass fiber to improve the bonding strength between the raw materials such as aramid fiber and glass fiber and the modified polyamide, thereby further improving the mechanical strength and wear resistance of the drill pipe.

[0025] Preferably, the weight ratio of the epoxy resin to the maleic anhydride graft is 1:(30-35).

[0026] By adopting the above technical solution and adjusting the weight ratio of the epoxy resin and the maleic anhydride grafted product, the mechanical strength and wear resistance of the drill pipe can be further improved.

[0027] In a second aspect, the present application provides a processing technology for any of the above-mentioned modified polyamide drill rods, which is specifically achieved through the following technical solutions: A processing technology for a modified polyamide drill rod comprises the following steps: The modified polyamide is first dried, then melted at 200-230°C, other raw materials are added, the mixture is extruded and melted, molded and shaped, and heat treated to obtain a modified polyamide drill rod.

[0028] In summary, this application includes at least one of the following beneficial technical effects: (1) By controlling the raw material type and dosage of the modified polyamide drill pipe, the tensile strength and elastic modulus of the modified polyamide drill pipe are 162-165 MPa and 8.5-8.7 GPa respectively, and the volume wear rate is (3.0-3.3)×10 -5 mm 3 / (N·m), which improves the mechanical strength and wear resistance of the modified polyamide drill pipe.

[0029] (2) In this application, the tensile strength, elastic modulus and elongation at break of the modified polyamide drill pipe are 172-175 MPa, 10.3-11.2 GPa and 33.7-34.6% respectively, and the volume wear rate is (2.5-2.7)×10 -5 mm 3 / (N·m), further improving the mechanical strength and wear resistance of the modified polyamide drill rod.

[0030] (3) The present invention adds epoxy resin to the raw material of modified polyamide drill pipe and adjusts the weight ratio of epoxy resin to maleic anhydride grafted product to make the tensile strength, elastic modulus and elongation at break of modified polyamide drill pipe 180-183 MPa, 11.8-12.0 GPa and 38.5-39.1% respectively, and the volume wear rate is (2.0-2.5)×10 -5 mm 3 / (N·m), further improving the mechanical strength and wear resistance of the modified polyamide drill rod. DETAILED DESCRIPTION

[0031] The following is a detailed description of the present application in conjunction with specific examples. The following raw materials in the present application are all commercially available products, which are intended to fully disclose the raw materials of the present application and should not be construed as limiting the sources of the raw materials. Specifically: modified polyamide, brand H7140CM T; aramid fiber, 3mm in length, 13μm in diameter; glass fiber, 12mm in length, 13μm in diameter; nanosilica, 325 mesh; cellulose nanowhiskers, 99.9% active ingredient content, 10-50nm in diameter, 100-500nm in length; maleic anhydride grafts, using high-temperature resistant maleic anhydride grafts, i.e., PA-g-MAH, with a temperature resistance of >200°C; graphene oxide, 99.9% fixed carbon content, 2-3nm in particle size; sodium stearate, model YZSN, 99% active ingredient content; sodium hydroxide, 99% active ingredient content; adipic acid, 99% active ingredient content; glutaric acid, 99% active ingredient content; epoxy resin, Sinopec brand, grade E-51, viscosity 220.

[0032] The following is an example of the preparation of modified polyamide: Preparation Example 1 The modified polyamide of Preparation Example 1 is obtained by the following steps: S1. 1 kg of graphene oxide and 1 kg of sodium stearate were mixed and added into 5 L of water, and magnetically stirred at 60 ° C for 1 h to obtain a graphene oxide dispersion; S2. Melt 1 kg of polyamide monomer at 220° C., add 50 g of sodium hydroxide and stir, vacuum dry, add 100 g of graphene oxide dispersion at 130° C. and stir evenly at a constant temperature, add 5 g of adipic acid and 5 g of glutaric acid, and polymerize under nitrogen at 240° C., extrude, cool, and pelletize to obtain modified polyamide.

[0033] The polyamide monomer is caprolactam monomer.

[0034] Preparation Example 2-5 The preparation method of the modified polyamide of Preparation Examples 2-5 is the same as the preparation method and raw material types of Preparation Example 1, except that the amounts of adipic acid and glutaric acid used are 3.33g and 6.67g, 2.85g and 7.15g, 2.5g and 7.5g, and 2.22g and 7.78g, respectively, and the amounts of other raw materials are the same as those in Preparation Example 1.

[0035] Example 1 The modified polyamide drill pipe of Example 1 is prepared by the following steps: According to the dosage in Table 1, the modified polyamide was dried at 80℃ for 4h, melted at 230℃, added with other raw materials, extruded and melted, molded and shaped, and heat treated at 80℃ for 2h to obtain the modified polyamide drill pipe. The modified polyamide was purchased and the brand is H7140CM T.

[0036] Examples 2-5 The modified polyamide drill rods of Examples 2-5 are prepared using the same methods and raw materials as those of Example 1, except for the different amounts of aramid fiber and glass fiber used, as shown in Table 1.

[0037] Table 1 Amount of each raw material in Examples 1-5 modified polyamide drill pipe (kg) Example 1 Example 2 Example 3 Example 4 Example 5 Modified polyamide 90 90 90 90 90 Aramid fiber 40.5 30 60 50 60 fiberglass 15 10 15 10 10 Nanosilica 4 4 4 4 4 Cellulose nanowhiskers 15 15 15 15 15 Maleic anhydride grafted 4 4 4 4 4 Examples 6-10 The modified polyamide drill rods of Examples 6-10 are identical in preparation method and raw material type and dosage to those of Example 3, except that the modified polyamides prepared in Preparation Examples 1-5 are used respectively, and the other raw material dosages are the same as those of Example 1.

[0038] Examples 11-15 The modified polyamide drill rods of Examples 11-15 are prepared in exactly the same manner and in the same raw material types and proportions as those of Example 8, except that 0.2 kg, 0.13 kg, 0.12 kg, 0.11 kg, and 0.1 kg of epoxy resin are further added to the raw materials of the modified polyamide drill rods, respectively.

[0039] Comparative Example 1 The modified polyamide drill pipe of Comparative Example 1 was prepared in exactly the same manner as in Example 1, except that an equal amount of cellulose nanowhiskers in the modified polyamide drill pipe raw material was replaced with cellulose nanocrystals. The remaining raw materials and dosages were the same as in Example 1. The cellulose nanocrystals had an effective substance content of 99%, a diameter of 20 nm, and a length of 100 nm.

[0040] Comparative Example 2 The preparation method of the modified polyamide drill rod of Comparative Example 2 is exactly the same as that of Example 1, except that an equal amount of aramid fiber in the raw material of the modified polyamide drill rod is replaced by carbon fiber, and the remaining raw materials and dosages are the same as those of Example 1.

[0041] Comparative Example 3 The preparation method of the modified polyamide drill rod of Comparative Example 3 is exactly the same as that of Example 1, except that an equal amount of glass fiber in the raw material of the modified polyamide drill rod is replaced by carbon fiber, and the remaining raw materials and dosages are the same as those of Example 1.

[0042] Comparative Example 4 The preparation method of the modified polyamide drill rod of Comparative Example 4 is exactly the same as that of Example 1, except that an equal amount of glass fiber in the raw material of the modified polyamide drill rod is replaced by aramid fiber, and the remaining raw materials and dosages are the same as those of Example 1.

[0043] Comparative Example 5 The preparation method of the modified polyamide drill rod of Comparative Example 5 is exactly the same as that of Example 1, except that an equal amount of aramid fiber in the raw material of the modified polyamide drill rod is replaced by glass fiber, and the remaining raw materials and dosages are the same as those of Example 1.

[0044] Comparative Example 6 The preparation method of the modified polyamide drill pipe of Comparative Example 6 is exactly the same as that of Example 1, except that no nano-silica is added to the raw materials of the modified polyamide drill pipe, and the other raw materials and dosages are the same as those of Example 1.

[0045] Comparative Example 7 The preparation method of the modified polyamide drill rod of Comparative Example 7 is exactly the same as that of Example 1, except that no cellulose nanocrystals are added to the raw materials of the modified polyamide drill rod, and the remaining raw materials and dosages are the same as those of Example 1.

[0046] Comparative Example 8 The preparation method of the modified polyamide drill pipe of Comparative Example 8 is exactly the same as that of Example 1, except that no maleic anhydride grafted product is added to the raw materials of the modified polyamide drill pipe, and the remaining raw materials and dosages are the same as those of Example 1.

[0047] Performance testing The following testing standards or methods were used to perform performance tests on the modified polyamide drill pipes obtained in different Examples 1-15 and Comparative Examples 1-8. The test results are shown in Table 2.

[0048] Tensile strength: GB / T 1040-2018 "Determination of tensile properties of plastics" is used to test the tensile strength of modified polyamide drill pipe.

[0049] Elongation at break: GB / T 1040-2018 "Determination of tensile properties of plastics" was used to test the elongation at break of modified polyamide drill pipe.

[0050] Elastic modulus: ISO 14125 “Fiber reinforced plastic composite materials - Determination of flexural properties” is used to test the elastic modulus of modified polyamide drill pipe.

[0051] Volume wear rate: GB / T 3960-2016 "Plastics - Test Methods for Sliding Friction and Wear" was used to test the volume wear rate of modified polyamide drill rods.

[0052] Table 2 Performance test results of modified polyamide drill pipe The test results in Table 2 show that the tensile strength, elastic modulus and elongation at break of the modified polyamide drill rod obtained in this application are the highest at 183 MPa, 12.0 GPa and 39.1% respectively, and the volume wear rate is the lowest at 2.0×10 -5 mm 3 / (N·m), which improves the mechanical properties and wear resistance of polyamide drill pipe.

[0053] In Examples 1-5, the tensile strength and elastic modulus of the modified polyamide drill rods of Examples 2-4 are 162-165 MPa and 8.5-8.7 GPa, respectively, which are higher than those of Examples 1 and 5, and the volume wear rate is (3.0-3.3)×10 -5 mm 3 / (N·m), which are lower than those in Example 1 and Example 5, indicating that the weight ratio of aramid fiber to glass fiber is 1:(3-5) which is more appropriate and improves the mechanical strength and wear resistance of the modified polyamide drill rod.

[0054] In Examples 6-10, the tensile strength, elastic modulus and elongation at break of the modified polyamide drill rods of Examples 6-10 were 172-175 MPa, 10.3-11.2 GPa and 33.7-34.6%, respectively, which were higher than those of Examples 6 and 10, and the volume wear rate was (2.5-2.7)×10 -5 mm 3 / (N·m), which are lower than those in Example 1 and Example 5, indicating that when modifying polyamide, a mass ratio of adipic acid to glutaric acid of 1:(2-3) is more appropriate, which improves the mechanical strength and wear resistance of the modified polyamide drill pipe.

[0055] In Examples 11-15, the tensile strength, elastic modulus and elongation at break of the modified polyamide drill rods of Examples 12-14 were 180-183 MPa, 11.8-12.0 GPa and 38.5-39.1%, respectively, which were higher than those of Example 6 and Example 10, and the volume wear rate was (2.0-2.5)×10 -5 mm 3 / (N·m), which are lower than those in Example 1 and Example 5, indicating that adding epoxy resin to the raw materials and the weight ratio of epoxy resin to maleic anhydride grafted product being 1:(30-35) are more appropriate, thereby improving the mechanical strength and wear resistance of the modified polyamide drill pipe.

[0056] In addition, based on the various index data of the modified polyamide drill rods of Comparative Examples 1-8 and Example 1, it was found that the addition of aramid fiber, glass fiber, nano-silica, cellulose nanocrystals, and maleic anhydride grafts to the raw materials of the modified polyamide drill rod in this application can improve the mechanical strength and wear resistance of the modified polyamide drill rod to varying degrees.

[0057] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A modified polyamide drill pipe, characterized in that: The invention comprises the following raw materials in parts by weight: 80-100 parts of modified polyamide, 10-15 parts of aramid fiber, 40-60 parts of glass fiber, 2-6 parts of nano silicon dioxide, 10-20 parts of cellulose nano whiskers and 2-6 parts of maleic anhydride grafts.

2. The modified polyamide drill pipe according to claim 1, characterized in that: The invention comprises the following raw materials in parts by weight: 85-95 parts of modified polyamide, 12-14 parts of aramid fiber, 45-55 parts of glass fiber, 3-5 parts of nano silicon dioxide, 14-17 parts of cellulose nano whiskers and 3-5 parts of maleic anhydride grafted material.

3. The modified polyamide drill pipe agent according to claim 1, characterized in that The weight ratio of the aramid fiber to the glass fiber is 1:(3-5).

4. The modified polyamide drill pipe according to claim 1, characterized in that The modified polyamide is prepared from graphene oxide modified polyamide, specifically: S1. Mixing graphene oxide and sodium stearate, adding them to water, and stirring them evenly with a magnetic stirrer at 50-70° C. to obtain a graphene oxide dispersion; S2, melting the polyamide monomer at 220-240° C., adding sodium hydroxide with stirring, vacuum drying, adding the graphene oxide dispersion at 125-135° C. and stirring uniformly at a constant temperature, adding adipic acid and glutaric acid, polymerizing under nitrogen at 230-260° C., extruding, cooling, and pelletizing to obtain a modified polyamide; The mass ratio of graphene oxide to sodium stearate is 1:(0.5-1.5); the volume ratio of the graphene oxide mass to water is 1:(4-6); the mass ratio of the graphene oxide dispersion to the polyamide monomer is 1:(8-12); the mass ratio of sodium hydroxide to the polyamide monomer is 1:(0.001-0.01); and the mass ratio of the total mass of adipic acid and glutaric acid to the polyamide monomer is 1:(97-99).

5. The modified polyamide drill pipe according to claim 4, characterized in that: The mass ratio of the adipic acid to the glutaric acid is 1:(2-3).

6. The modified polyamide drill pipe according to claim 1, characterized in that: The modified polyamide drill pipe further comprises the following raw materials in parts by weight: 0.1-0.3 parts of epoxy resin.

7. The modified polyamide drill pipe according to claim 6, characterized in that: The weight ratio of the epoxy resin to the maleic anhydride grafted product is 1:(30-35).

8. A process for processing the modified polyamide drill rod according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: first drying the modified polyamide, then melting the modified polyamide at 200-230 DEG C, adding other raw materials, extruding the melt, shaping the mold, and heat treating to obtain the modified polyamide drill rod.

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