A high-strength and high-toughness shale oil and gas drill pipe and its preparation method

Abstract

This invention discloses a high-strength, high-toughness pipe for shale oil and gas drilling and its preparation method. The weight percentage composition of the pipe is: 0.18%≤C≤0.22%, 0.15%≤Si≤0.35%, 1.6%≤Mn≤2.0%, 0.16%≤Mo≤0.20%, 0.02%≤Ti≤0.04%, 0.001%≤B≤0.002%, 0.01%≤Al≤0.04%, N≤0.006%, P≤0.01%, S≤0.002%, with the balance being Fe and unavoidable impurities. The pipe prepared by this invention has a fine and uniform tempered bainite and tempered sorbite microstructure with a grain size of 9-10. It possesses ultra-high strength, along with matching toughness and plasticity. Furthermore, it uses fewer alloying elements and has a lower alloy content, significantly reducing production costs and showing broad application prospects in the field of shale oil and gas extraction.

Description

Technical Field

[0001] This invention relates to the field of materials metallurgy, and in particular to a high-strength, high-toughness pipe for shale oil and gas drilling and its preparation method. Background Technology

[0002] Shale gas refers to natural gas resources contained in shale formations, which are mainly composed of shale. According to data from the Ministry of Natural Resources, my country has approximately 22 trillion cubic meters of recoverable shale gas resources at depths shallower than 4,500 meters. Shale gas is expected to become an important driver of future natural gas production growth.

[0003] However, shale gas reservoirs are unconventional oil and gas reservoirs, and differ significantly from conventional oil and gas reservoirs. Shale gas reservoirs are relatively deep, and the reservoirs generally exhibit low porosity and low permeability characteristics, typically with permeability less than 1×10⁻⁶. -3 The shale gas reservoir has a porosity of only 4%-5%, resulting in greater airflow resistance than conventional natural gas and making extraction more difficult. Hydraulic fracturing of the reservoir is required for extraction. Therefore, extremely high requirements are placed on the comprehensive performance of pipe materials used in shale gas reservoirs. The yield strength of the pipe material must reach at least 125 kJ / s, the impact energy must be greater than 1 / 10 of the yield strength of the pipe body, and good plasticity is also required.

[0004] Traditional ultra-high strength pipes are typically designed using medium-carbon chromium-molybdenum steel. Carbon, chromium, and molybdenum are used to improve hardenability and strength, and high-temperature tempering is employed to obtain a sorbitic structure, further enhancing impact toughness. Commonly used steels have a carbon content of 0.2%-0.3% and a molybdenum content of 0.3%-0.8%, and generally require the addition of trace alloying elements such as niobium and vanadium. This alloying process is costly, and niobium and vanadium are relatively rare in the Earth's crust. Therefore, developing economical high-strength, high-toughness pipes has become a pressing issue in the shale gas reservoir development field. Summary of the Invention

[0005] To address the problems of low strength, toughness, and plasticity, as well as high production costs, of existing pipes used in oil and gas drilling, this invention provides a high-strength, high-toughness pipe for shale oil and gas drilling and its preparation method.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the embodiments of the present invention is as follows:

[0007] A high-strength, high-toughness shale oil and gas drill pipe has the following composition by weight percentage: 0.18%≤C≤0.22%, 0.15%≤Si≤0.35%, 1.6%≤Mn≤2.0%, 0.16%≤Mo≤0.20%, 0.02%≤Ti≤0.04%, 0.001%≤B≤0.002%, 0.01%≤Al≤0.04%, N≤0.006%, P≤0.01%, S≤0.002%, with the balance being Fe and unavoidable impurities.

[0008] Compared to existing technologies, the high-strength, high-toughness shale oil and gas drill pipes provided by this invention have a simple alloy composition system, without adding precious alloying elements such as Nb, V, and Cr. Appropriately reducing the C content and controlling the carbon content to 0.18%-0.22% can reduce element segregation during continuous casting and improve the toughness of the steel. By controlling the Mn content to 1.6%-2.0%, it not only compensates for the strength reduction caused by the low carbon content but also improves the impact toughness of the steel pipe. Adding trace amounts of B increases the hardenability of the steel during heat treatment, thereby improving the toughness and microstructure uniformity of the steel, effectively reducing the amount of Mo added and saving costs. Adding Ti for microalloying controls the morphology of inclusions, refines grains, and creates a uniform microstructure. Adding Al as an alloying and deoxidizing element further improves the strength and impact toughness of the steel. Strictly controlling the nitrogen, phosphorus, and sulfur content in the steel ensures the effective titanium content, which is beneficial for fully utilizing the microalloying effect of titanium and improving the performance stability of the steel.

[0009] The above-mentioned components are combined in specific proportions to significantly improve the strength, toughness, and plasticity of the steel. At the same time, it effectively reduces the amount of Mo required and eliminates the need for precious elements such as Nb, V, and Cr. The tensile strength of the steel can reach 1030-1080 MPa, the yield strength can reach 959-1010 MPa, the Charpy impact energy at 0℃ is 98-127 J, the toughness meets the requirement of 10% yield strength, the elongation can reach 24%-28%, and the crush resistance can reach 166-174 MPa. It can be widely used in the field of shale oil and gas extraction and effectively reduce the cost of oil and gas extraction, showing broad application prospects.

[0010] Furthermore, the metallographic structure of the pipe used in the high-strength and high-toughness shale oil and gas drill is tempered bainite and tempered sorbite, with a grain size of 9-10.

[0011] This invention also provides a method for preparing the above-mentioned high-strength and high-toughness pipe used in shale oil and gas drilling, comprising the following steps:

[0012] The continuous casting round billet with the same chemical composition as the pipe material used in the high-strength and high-toughness shale oil and gas drill is heated in an annular furnace, pierced and made into a rough tube. The rough tube is rolled to obtain a blank tube. The blank tube is then subjected to micro-tension reduction and cooling in a walking beam cooling bed to obtain a seamless steel pipe.

[0013] The seamless steel pipe is heat-treated to obtain the high-strength, high-toughness pipe used in shale oil and gas drilling.

[0014] The high-strength and high-toughness shale oil and gas drill pipe preparation method provided by this invention is simple and easy to implement in production.

[0015] Preferably, the continuously cast round billet is made by melting steelmaking raw materials in an electric arc furnace, refining in a ladle, vacuum refining in VD, and continuous casting.

[0016] Furthermore, after the electric arc furnace smelting is completed, when the steel is tapped to 1 / 3 of its total volume, FeAl alloy is added to the molten steel for deoxidation and alloying, and then lime and ladle top slag modifier are added for slag formation.

[0017] It should be noted that lime and ladle top slag modifier are added to the ladle immediately after tapping to form slag, so as to ensure that the lime and ladle top slag modifier spread and melt as soon as possible.

[0018] Adding FeAl alloy when the steel is 1 / 3 full for deoxidation and alloying, and then slag formation after deoxidation and alloying, helps to reduce the number and size of inclusions in the molten steel and improve the purity of the finished steel.

[0019] Furthermore, the ladle top slag modifier has the following composition by weight percentage: CaO 15%-20%, SiO2 5%-10%, Al2O3 30%-35%, Al 10%-20%, C 10%-20%, with the balance being unavoidable impurities.

[0020] For example, the amount of the ladle top slag modifier added is 1kg / t-3kg / t.

[0021] The selected ladle top slag modifier has the advantages of good reducing properties and rapid slag formation, which can achieve continuous and stable modification of ladle top slag, give full play to the role of ladle top slag in steel desulfurization, steel oxidation and adsorption of inclusions, and significantly improve the purity of steel.

[0022] Preferably, in the ladle refining process, the weight percentage of each component of the refining slag is controlled within the following range: CaO 45%-55%, SiO2 10%-15%, Al2O3+B2O3 25%-30%, MgO 4%-8%, wherein the content of B2O3 is 2%-20%, and the balance is unavoidable impurities.

[0023] The Al2O3 and B2O3 added to the refining slag of this invention can effectively reduce the melting point and viscosity of steel slag, giving the refining slag good adsorption of inclusions and desulfurization capabilities, thereby effectively improving the quantity, morphology and size of inclusions in steel, increasing the purity of molten steel, and thus improving the toughness of steel.

[0024] Preferably, after the VD vacuum refining process is completed, FeTi alloy is added to the molten steel, and after soft blowing for 2-4 minutes, FeB alloy is added for alloying.

[0025] Preferably, the FeTi alloy is added at a rate of 0.6 kg / t to 1.2 kg / t, and the FeB alloy is added at a rate of 0.06 kg / t to 0.12 kg / t.

[0026] This invention utilizes FeTi alloy for microalloying to control the morphology of inclusions, refine grains, and achieve a uniform microstructure. Simultaneously, the addition of FeB alloy improves the uniformity and hardenability of the steel microstructure. While significantly enhancing the overall performance of the steel, this invention also effectively reduces the amount of Mo required and avoids the addition of Nb, V, and Cr. This provides a new compositional design approach for pipes used in shale oil and gas drilling and is of great significance for developing new high-strength and high-toughness pipes.

[0027] Preferably, the elongation coefficient of the rolling process is 5-10.

[0028] Controlling the elongation coefficient of the rolling process to 5-10 helps to reduce the banded structure and improve the impact toughness of the pipe.

[0029] Preferably, the heat treatment process includes the following steps: heating the seamless steel pipe to 930℃-980℃ and holding it at that temperature, then water quenching it, and then heating the steel pipe to 450℃-600℃ and holding it at that temperature, followed by air cooling.

[0030] Preferably, in the heat treatment process, the heat treatment time for the seamless steel pipe is 3-5 minutes at 930℃-980℃ and 10-15 minutes at 450℃-600℃.

[0031] Heating seamless steel pipes to 930℃-980℃ promotes the full dissolution of TiC in austenite, providing conditions for the formation of extremely fine grains in subsequent quenching and tempering treatments. Subsequent water quenching and tempering at 450℃-600℃ facilitate the precipitation of fine and dispersed TiC particles, resulting in uniform and fine tempered bainite and tempered sorbite, thereby improving the strength and toughness of the pipe.

[0032] The beneficial effects of adopting the above technical solution are as follows:

[0033] This invention employs precise chemical composition design and a unique preparation process, resulting in high purity molten steel with fine and dispersed inclusions. The metallographic structure consists of fine and uniform tempered bainite and tempered sorbite with a grain size of 9-10. This results in steel with ultra-high strength, as well as matching toughness and plasticity. Furthermore, the invention uses fewer alloying elements and has a lower alloy content, significantly reducing production costs. It has broad application prospects in the field of shale oil and gas extraction. Attached Figure Description

[0034] Figure 1Metallographic diagram of the high-strength, high-toughness shale oil and gas drill pipe prepared in Example 1 of the present invention;

[0035] Figure 2 Metallographic structure of the high-strength, high-toughness shale oil and gas drill pipe prepared in Example 2 of this invention;

[0036] Figure 3 The metallographic structure of the high-strength, high-toughness shale oil and gas drill pipe prepared in Example 3 of the present invention is shown in Figure 3. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0038] To better illustrate the present invention, further examples are provided below.

[0039] Example 1

[0040] This invention provides a high-strength, high-toughness pipe for shale oil and gas drilling, the chemical composition of which is:

[0041] C 0.18%, Si 0.25%, Mn 2.0%, Mo 0.16%, Ti 0.04%, B 0.002%, Al 0.01%, N 0.004%, P 0.008%, S 0.0015%, balance Fe and unavoidable impurities.

[0042] The preparation steps for the pipes used in the aforementioned high-strength, high-toughness shale oil and gas drills are as follows:

[0043] S1, steelmaking raw materials are smelted in an 80t electric arc furnace, refined in a ladle, degassed in a VD vacuum, and continuously cast to produce a continuously cast round billet with the same chemical composition as the above-mentioned pipe material with a diameter of Φ200mm.

[0044] S2, the continuously cast round billet is heated in an annular furnace, pierced to form a rough tube, the rough tube is rolled by a three-roll continuous rolling mill to obtain a blank tube, the blank tube is removed by a three-stand tube remover, micro-tension diameter reduction, and cooling by a walking beam cooling bed to produce a seamless steel pipe with an outer diameter of 139.7 mm and a wall thickness of 12.7 mm.

[0045] S3. The above-mentioned seamless steel pipe is heat-treated to obtain a high-strength and high-toughness pipe for shale oil and gas drilling.

[0046] In this process, after the electric arc furnace smelting process is completed and the steel is tapped to one-third capacity, FeAl alloy is added to the molten steel for deoxidation and alloying. Then, lime and ladle top slag modifier are added to form slag. The ladle top slag modifier has the following composition by weight percentage: CaO 15%, SiO2 10%, Al2O3 35%, Al 20%, C 15%, with the balance being unavoidable impurities.

[0047] In the ladle refining process, the weight percentage of each component of the refining slag is controlled within the following range: CaO 45%, SiO2 15%, Al2O3 20%, B2O3 10%, MgO 8%, with the balance being unavoidable impurities.

[0048] After the VD vacuum refining process is completed, 1.2 kg / t of FeTi alloy is added to the molten steel, and after soft blowing for 2-4 minutes, 0.12 kg / t of FeB alloy is added for alloying.

[0049] The elongation factor of the rolling process is 8.

[0050] The heat treatment process includes the following steps: heating the seamless steel pipe to 950℃ and holding it at that temperature for 4 minutes, then water quenching it, then heating the steel pipe to 550℃ and holding it at that temperature for 12 minutes, and finally air cooling it.

[0051] The microstructure of the pipe prepared using this embodiment is mainly tempered bainite and tempered sorbite, with fine grains and a grain size of 9-10. Figure 1 As shown.

[0052] Example 2

[0053] This invention provides a high-strength, high-toughness pipe for shale oil and gas drilling, the chemical composition of which is:

[0054] C 0.22%, Si 0.15%, Mn 1.6%, Mo 0.18%, Ti 0.03%, B 0.001%, Al 0.02%, N 0.005%, P 0.007%, S 0.0013%, balance Fe and unavoidable impurities.

[0055] The preparation steps for the pipes used in the aforementioned high-strength, high-toughness shale oil and gas drills are as follows:

[0056] S1, steelmaking raw materials are smelted in an 80t electric arc furnace, refined in a ladle, degassed in a VD vacuum, and continuously cast to produce a continuously cast round billet with the same chemical composition as the above-mentioned pipe material with a diameter of Φ200mm.

[0057] S2, the continuously cast round billet is heated in an annular furnace, pierced to form a rough tube, the rough tube is rolled by a three-roll continuous rolling mill to obtain a blank tube, the blank tube is removed by a three-stand tube remover, micro-tension diameter reduction, and cooling by a walking beam cooling bed to produce a seamless steel pipe with an outer diameter of 139.7 mm and a wall thickness of 12.7 mm.

[0058] S3. The above-mentioned seamless steel pipe is heat-treated to obtain a high-strength and high-toughness pipe for shale oil and gas drilling.

[0059] In this process, after the electric arc furnace smelting process is completed and the steel is tapped to 1 / 3 capacity, FeAl alloy is added to the molten steel for deoxidation and alloying. Then, lime and ladle top slag modifier are added to form slag. The ladle top slag modifier has the following composition by weight percentage: CaO 18%, SiO2 5%, Al2O3 30%, Al 18%, C 20%, with the balance being unavoidable impurities.

[0060] In the ladle refining process, the weight percentage of each component of the refining slag is controlled within the following range: CaO 50%, SiO2 13%, Al2O3 2%, B2O3 23%, MgO 6%, with the balance being unavoidable impurities.

[0061] After the VD vacuum refining process is completed, 1.0 kg / t of FeTi alloy is added to the molten steel, and after soft blowing for 2-4 minutes, 0.06 kg / t of FeB alloy is added for alloying.

[0062] The elongation factor of the rolling process is 5.

[0063] The heat treatment process includes the following steps: heating the seamless steel pipe to 930℃ and holding it at that temperature for 5 minutes, then water quenching it, and then heating the steel pipe to 450℃ and holding it at that temperature for 15 minutes, followed by air cooling.

[0064] The microstructure of the pipe prepared using this embodiment is mainly tempered bainite and tempered sorbite, with fine grains and a grain size of 9-10. Figure 2 As shown.

[0065] Example 3

[0066] This invention provides a high-strength, high-toughness pipe for shale oil and gas drilling, the chemical composition of which is:

[0067] C 0.2%, Si 0.35%, Mn 1.8%, Mo 0.2%, Ti 0.02%, B 0.0015%, Al 0.04%, N 0.005%, P 0.006%, S 0.0012%, balance Fe and unavoidable impurities.

[0068] The preparation steps for the pipes used in the aforementioned high-strength, high-toughness shale oil and gas drills are as follows:

[0069] S1, steelmaking raw materials are smelted in an 80t electric arc furnace, refined in a ladle, degassed in a VD vacuum, and continuously cast to produce a continuously cast round billet with the same chemical composition as the above-mentioned pipe material with a diameter of Φ200mm.

[0070] S2, the continuously cast round billet is heated in an annular furnace, pierced to form a rough tube, the rough tube is rolled by a three-roll continuous rolling mill to obtain a blank tube, the blank tube is removed by a three-stand tube remover, micro-tension diameter reduction, and cooling by a walking beam cooling bed to produce a seamless steel pipe with an outer diameter of 139.7 mm and a wall thickness of 12.7 mm.

[0071] S3. The above-mentioned seamless steel pipe is heat-treated to obtain a high-strength and high-toughness pipe for shale oil and gas drilling.

[0072] In this process, after the electric arc furnace smelting process is completed and the steel is tapped to 1 / 3 capacity, FeAl alloy is added to the molten steel for deoxidation and alloying. Then, lime and ladle top slag modifier are added to form slag. The ladle top slag modifier has the following composition by weight percentage: CaO 20%, SiO2 10%, Al2O3 35%, Al 10%, C 13%, with the balance being unavoidable impurities.

[0073] In the ladle refining process, the weight percentage of each component of the refining slag is controlled within the following range: CaO 55%, SiO2 10%, Al2O3 10%, B2O3 18%, MgO 4%, with the balance being unavoidable impurities.

[0074] After the VD vacuum refining process is completed, 0.6 kg / t of FeTi alloy is added to the molten steel, and after soft blowing for 2-4 minutes, 0.1 kg / t of FeB alloy is added for alloying.

[0075] The elongation factor of the rolling process is 10.

[0076] The heat treatment process includes the following steps: heating the seamless steel pipe to 980℃ and holding it at that temperature for 3 minutes, then water quenching it, then heating the steel pipe to 600℃ and holding it at that temperature for 10 minutes, and finally air cooling it.

[0077] The microstructure of the shale oil and gas drill pipe prepared using this embodiment is mainly tempered bainite and tempered sorbite, with fine grains and a grain size of 9-10. Figure 3 As shown.

[0078] According to the requirements of API SPECIFICATION 5CT standard, 10th edition, shale oil and gas drills prepared in Examples 1-3 were randomly sampled from the pipes for analysis of yield strength, tensile strength, lateral impact energy, and elongation; and the crush resistance of each sample was tested according to the requirements of SY / T6238.1 standard; the results are shown in Table 1.

[0079] Table 1 Statistical Table of Mechanical Properties

[0080] Inspection items Sample size Minimum value Maximum value average value Standard deviation Yield strength / MPa 77 959 1010 980.6 14.3 Tensile strength / MPa 77 1030 1080 1055.3 12.5 Xia's Impact Power / J 77 98 127 110.2 11.2 Elongation / % 77 24 28 26.5 0.6 Crushing strength / MPa 28 166.2 173.5 170.3 1.3

[0081] As shown in the table, the pipes produced by the above methods have a yield strength of 959-1010 MPa, a tensile strength of 1030-1080 MPa, a transverse full-size Charpy impact energy of 98-127 J at 0℃, and a yield-to-tensile ratio ≤0.93. The average yield strength is 980.6 MPa with a standard deviation of 14.3 MPa; the average tensile strength is 1055.3 MPa with a standard deviation of 12.5 MPa; and the average transverse full-size Charpy impact energy at 0℃ is 110.2 J with a standard deviation of 11.2 J. The elongation of the material is 24%-28%, with an average of 26.5% and a standard deviation of 0.6%.

[0082] According to the requirements of GB / T 10561 standard, 25 samples were randomly selected from the pipes of shale oil and gas drills prepared in Examples 1-3 for inclusion rating. The statistical analysis results are shown in Table 2.

[0083] Table 2. Statistics on the Rating of Inclusions

[0084] Inclusion type Minimum value Maximum value average value A fine 0 0 0 B Fine 0 0.5 0.31 C fine 0 0 0 D fine 0 0.5 0.25 Ds 0 0.5 0.22

[0085] The results show that no coarse inclusions were found in the pipes used for shale oil and gas drilling prepared in Examples 1-3. The average grade of fine inclusions B was 0.31, the grade of fine inclusions D was 0.25, and the grade of inclusions Ds was 0.22. The pipes have high purity, which is beneficial to improving the fatigue resistance of the pipes during formation fracturing.

[0086] In summary, the pipes prepared by this invention have excellent metallurgical properties, low content of harmful elements, fine and uniform microstructure, and reliable mechanical properties. They can be widely used in the drilling and production of shale gas reservoirs and have broad market prospects.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A type of pipe used in high-strength, high-toughness shale oil and gas drilling, characterized in that, Its composition by weight percentage is as follows: 0.18%≤C≤0.22%, 0.15%≤Si≤0.35%, 1.6%≤Mn≤2.0%, 0.16%≤Mo≤0.20%, 0.02%≤Ti≤0.04%, 0.001%≤B≤0.002%, 0.01%≤Al≤0.04%, N≤0.006%, P≤0.01%, S≤0.002%, with the balance being Fe and unavoidable impurities; The method for preparing the tubing used in the high-strength, high-toughness shale oil and gas drill includes the following steps: The continuous casting round billet with the same chemical composition as the pipe material used in the high-strength and high-toughness shale oil and gas drill is heated in an annular furnace, pierced and made into a rough tube. The rough tube is rolled to obtain a blank tube. The blank tube is then subjected to micro-tension reduction and cooling in a walking beam cooling bed to obtain a seamless steel pipe. The seamless steel pipe is heat-treated to obtain the pipe material used for the high-strength and high-toughness shale oil and gas drill. The continuously cast round billet is made by smelting steelmaking raw materials in an electric arc furnace, refining in a ladle, VD vacuum refining and continuous casting processes. After the electric arc furnace smelting is completed, when the steel is tapped to 1 / 3 of its total volume, FeAl alloy is added to the steel for deoxidation and alloying, and then lime and ladle top slag modifier are added to form slag. The ladle top slag modifier has the following composition by weight percentage: CaO 15%-20%, SiO2 5%-10%, Al2O3 30%-35%, Al 10%-20%, C 10%-20%, with the balance being unavoidable impurities; The heat treatment process includes the following steps: heating the seamless steel pipe to 930℃-980℃ and holding it at that temperature, then water quenching it, and then heating the steel pipe to 450℃-600℃ and holding it at that temperature, followed by air cooling.

2. A method for preparing the high-strength, high-toughness shale oil and gas drilling pipe as described in claim 1, characterized in that, Includes the following steps: The continuous casting round billet with the same chemical composition as the pipe material used in the high-strength and high-toughness shale oil and gas drill is heated in an annular furnace, pierced and made into a rough tube. The rough tube is rolled to obtain a blank tube. The blank tube is then subjected to micro-tension reduction and cooling in a walking beam cooling bed to obtain a seamless steel pipe. The seamless steel pipe is heat-treated to obtain the high-strength and high-toughness pipe material used in shale oil and gas drilling.

3. The method for preparing high-strength, high-toughness shale oil and gas drilling pipes as described in claim 2, characterized in that, In the ladle refining process, the weight percentage of each component of the refining slag is controlled within the following range: CaO 45%-55%, SiO2 10%-15%, Al2O3+B2O3 25%-30%, MgO 4%-8%, of which the content of B2O3 is 2%-20%, and the balance is unavoidable impurities.

4. The method for preparing high-strength, high-toughness shale oil and gas drilling pipe as described in claim 2, characterized in that, After the VD vacuum refining process is completed, FeTi alloy is added to the molten steel, and after soft blowing for 2-4 minutes, FeB alloy is added for alloying.

5. The method for preparing high-strength, high-toughness shale oil and gas drilling pipes as described in claim 2, characterized in that, The elongation coefficient of the rolling process is 5-10.

6. The method for preparing high-strength, high-toughness shale oil and gas drilling pipe as described in claim 2, characterized in that, During the heat treatment process, the holding time for seamless steel pipes at 930℃-980℃ is 3min-5min, and the holding time at 450℃-600℃ is 10min-15min.

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