Preparation method of rare-earth-containing 110ksi steel grade high-collapse-resistance oil well pipe

Abstract

The invention discloses a preparation method of a rare earth containing 110ks i steel grade high collapse resistance oil well pipe which comprises the following chemical components in percentage by mass: 0.25-0.30% of C, 0.17-0.37% of S i, 0.9-1.30% of Mn, 0.9-1.4% of Cr, 0.001-0.05% of A, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.001-0.003% of RE and the balance of Fe and trace impurities, and the total mass fraction is 100%. The invention further discloses a preparation process and parameter control. Comprising a steelmaking process; a rolling process; and a tempering production process. The invention aims to provide the preparation method of the rare earth-containing 110ks i steel grade high-collapse-resistance oil well pipe, so that the material has good impact toughness, tensile strength and collapse resistance, the production cost is low, and the standard performance requirements can be met.

Description

Technical Field

[0001] This invention relates to the field of materials metallurgy, and in particular to a method for preparing a high-strength oil well pipe containing rare earth 110ksi steel grade. Background Technology

[0002] With the continuous advancement of technology, drilling depths are increasing, especially in areas with complex geological conditions and high extraction difficulty, such as the western and southwestern oil and gas fields and offshore oil and gas fields. Oil and gas exploration and extraction are characterized by continuous development into deeper areas, with increasingly complex geological conditions. High-difficulty wells, such as deep wells, ultra-deep wells, complex structure wells, horizontal wells, extended reach wells, underbalanced wells, and piedmont structural wells, place higher demands on the performance and quality of oil tubing. This results in increasingly higher external extrusion loads and axial loads on the casing during well completion, thus requiring casings with excellent comprehensive mechanical properties and dimensional accuracy. 110ksi grade high-strength crush-resistant casing products combine high strength and high toughness, while effectively resisting the casing deformation risk caused by formation changes during casing running-in. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a high-strength oil well pipe containing rare earth 110ksi steel grade, which results in a material with good impact toughness, tensile strength, and anti-strength properties, low production cost, and the ability to meet standard performance requirements.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] This invention discloses a method for preparing a high-strength, crush-resistant oil well pipe containing rare earth elements (110ksi grade). The chemical composition by mass percentage is: C 0.25–0.30, Si 0.17–0.37, Mn 0.9–1.30, Cr 0.9–1.4, Al 0.001–0.05, P≤0.015, S≤0.010, and RE 0.001–0.003, with the remainder being Fe and trace impurities, totaling 100% by mass. The preparation process and parameter control include:

[0006] In the steelmaking process, the incoming molten iron must have P ≤ 0.012% and S ≤ 0.05%. A single-slag process is used for smelting, and the final slag basicity is controlled at 3.0-5.0. Deoxidation and alloying are carried out using ferrosilicon manganese and ferromanganese, and the final deoxidation process uses an aluminum-containing deoxidation process. The LF process uses a method of gradually increasing the heating rate from low to high stages. Rare earth alloys are added before VD (Vacuum Deposition). The VD vacuum degree must be ≤ 0.10 kPa, and the deep vacuum time must be ≥ 15 minutes. After vacuum treatment, a 180-meter silicon-calcium wire is fed in, and the soft blowing time after wire feeding is ≥ 15 minutes. The continuous casting billet is controlled by a constant casting speed.

[0007] During the rolling process, the billet is heated in the ring furnace as follows: heating stage 1: 700-920℃; heating stage 2: 900℃-1050℃; heating stage 3: 1000℃-1200℃; heating stage 4: 1200℃~1275℃; heating stage 5: 1250℃-1275℃; heating stage 6: 1230℃-1250℃; piercing temperature of round billet: 1200℃~1250℃; rolling temperature of steel pipe: 1000℃~1200℃.

[0008] The quenching and tempering process includes: quenching furnace → heating → water quenching → tempering furnace → heating → heated straightening → cooling bed; the heat treatment regime is: quenching furnace 890℃±10℃, holding for 30min~50min; after the steel pipes come out of the furnace, they undergo internal and external water quenching, with water temperature <30℃ and water volume >450m³. 3 / min, water pressure ≥5MPa, water quenching time adjusted according to wall thickness specifications; tempering furnace 660℃±20℃, holding for 50min~70min, steel pipes are air cooled after being taken out of the furnace.

[0009] Furthermore, its chemical composition by mass percentage is as follows: C 0.25%, Si 0.17%, Mn 1.0%, Cr 1.40%, Al 0.01%, P 0.015%, S 0.009%, RE 0.001%, with the remainder being Fe and unavoidable impurities, totaling 100% by mass.

[0010] Furthermore, its chemical composition by mass percentage is as follows: C 0.26%, Si 0.19%, Mn 1.05%, Cr 1.10%, Al 0.03%, P 0.014%, S 0.008%, RE 0.002%, with the remainder being Fe and trace impurities, totaling 100% by mass.

[0011] Furthermore, its chemical composition by mass percentage is as follows: C 0.28%, Si 0.20%, Mn 1.10%, Cr 0.95%, Al 0.023%, P 0.013%, S 0.003%, RE 0.003%, with the remainder being Fe and trace impurities, totaling 100% by mass.

[0012] Furthermore, its chemical composition by mass percentage is as follows: C 0.29%, Si 0.30%, Mn 1.250%, Cr 0.98%, Al 0.04%, P 0.012%, S 0.002%, RE 0.002%, with the remainder being Fe and trace impurities, totaling 100% by mass.

[0013] Furthermore, its chemical composition by mass percentage is as follows: C 0.30%, Si 0.37%, Mn 1.30%, Cr 1.05%, Al 0.04%, P 0.011%, S 0.001%, RE 0.003%, with the remainder being Fe and trace impurities, totaling 100% by mass.

[0014] Furthermore, its mechanical properties are as follows: longitudinal impact toughness at 0℃ ≥76J.

[0015] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0016] This invention relates to a rare earth 110ksi high-stretch-resistant oil well pipe material. Through the Mn-Cr alloy and the effects of rare earth modification inclusions and microalloying, it requires tempering heat treatment, resulting in low production costs. At the same time, the material has good anti-stretch-resistant properties, and all mechanical properties meet the standard requirements. Detailed Implementation

[0017] A method for preparing a high-strength oil well pipe containing rare earth 110ksi steel grade, including a steelmaking process, a pipe manufacturing process, and a heat treatment process;

[0018] The steelmaking process is as follows: molten iron pretreatment → converter smelting → LF refining → VD degassing → round billet continuous casting. Converter smelting uses desulfurized molten iron, with incoming molten iron composition requirements: P≤0.012%, S≤0.05%, controlling steel quality from the source. A single-slag smelting process is adopted, with the final slag basicity controlled at 3.0-5.0. Deoxidation and alloying are performed using ferrosilicon and ferromanganese, with final deoxidation employing an aluminized deoxidation process. Slag blocking or skimming is mandatory during tapping to effectively improve steel cleanliness. An appropriate amount of quicklime is added during tapping. LF refining employs a gradual heating rate increase from low to high stages, based on the converter steel composition. Slag formation, desulfurization, composition adjustment, and heating operations are carried out at different temperatures. Refining adopts a white slag formation process. Rare earth alloys are added before VD (Vacuum Deposition). The deep vacuum degree of VD is ≤0.08Kpa, and the deep vacuum time is ≥15min. After VD vacuum, 180m of silicon-calcium wire is fed, and the soft blowing time after wire feeding is 15 minutes to ensure the deformation of inclusions, so that the inclusions can float fully and reduce the inclusion and gas content in the steel. The continuous casting process adopts non-oxidizing protection casting, the superheat of molten steel is controlled within 30℃, and a constant casting speed control process is adopted. The chemical composition of each example was analyzed, and the chemical composition by mass percentage is shown in Table 1 (wt%): C 0.25, Si 0.17, Mn 1.0, Cr 1.40, Al 0.01, P 0.015, S 0.009, RE 0.001, with the remainder being Fe and unavoidable impurities, totaling 100% by mass; or, C 0.26, Si 0.19, Mn 1.05, Cr 1.10, Al 0.03, P 0.014, S 0.008, RE 0.002, with the remainder being Fe and trace impurities, totaling 100% by mass; or, C 0.28, Si 0.20, Mn 1.10, Cr 0.95, Al 0.023, P 0.013, S 0.003, RE 0.003, with the remainder being Fe and trace impurities, totaling 100% by mass; or, C 0.29, Si 0.30, Mn 1.250, Cr 0.98, Al 0.04, P 0.012, S 0.002, RE 0.002, with the remainder being Fe and trace impurities, totaling 100% by mass; or, C 0.30, Si 0.37, Mn 1.30, Cr 1.05, Al 0.04, P 0.011, S 0.001, RE 0.003, with the remainder being Fe and trace impurities, totaling 100% by mass.

[0019] Table 1. Percentage of Chemical Components (%) for Each Example

[0020] Example C Si Mn Cr Al P S RE Example 1 0.25 0.17 1.0 1.4 0.010 0.015 0.009 0.001 Example 2 0.26 0.19 1.05 1.10 0.03 0.013 0.008 0.002 Example 3 0.28 0.20 1.10 0.95 0.023 0.013 0.003 0.003 Example 4 0.29 0.30 1.25 0.98 0.040 0.012 0.002 0.002 Example 5 0.30 0.37 1.30 1.05 0.040 0.011 0.001 0.003

[0021] The steel rolling process includes round billet sawing → heating → piercing → tube rolling → tension reduction → cooling on a cooling bed. The heating temperature of each section of the heating furnace must be strictly controlled: the first heating section is 700-920℃, and the second heating section is 900℃.

[0022] The heating temperature is set at -1050℃, with three heating stages from 1000℃ to 1200℃, four from 1200℃ to 1275℃, five from 1250℃ to 1275℃, and six from 1230℃ to 1250℃. The billet piercing temperature is 1200℃ to 1250℃, and the steel pipe rolling temperature is 1000℃ to 1200℃. Maintaining a low and slow initial heating temperature for the billet prevents excessive stress and cracking. The billet piercing temperature is controlled at 1200℃ to 1250℃. The steel pipe rolling temperature is controlled at 1000℃ to 1200℃ to ensure that the large deformation rolling temperature is within the material's optimal plasticity range, resulting in low deformation resistance, low hot tool consumption, and improved internal and external surface quality of the steel pipe.

[0023] The rare earth-containing 110ksi high-strength oil well pipe material produced by the above process has the following chemical composition by mass percentage: C 0.25-0.30, Si 0.17-0.37, Mn 0.9-1.30, Cr 0.9-1.4, Al 0.001-0.05, P≤0.015, S≤0.010, and RE 0.001-0.003, with the remainder being Fe and trace impurities, totaling 100% by mass. By simultaneously adding rare earth elements to a medium-carbon Mn-Cr alloy system, the steel's resistance to collapse is improved through the modification and alloying effects of rare earth elements on inclusions. The chemical and mechanical property test results of each embodiment are shown in Table 2.

[0024] Table 2. Mechanical performance test results for each embodiment.

[0025]

[0026] As can be seen from Table 2, the seamless steel pipe material of the present invention has good mechanical properties. The strength of the material reaches 110 ksi grade, the longitudinal impact toughness at 0℃ is ≥76J, and it can meet the standard requirements after quenching and tempering. The material has good mechanical properties.

[0027] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a high-strength, crush-resistant oil well casing containing rare earth 110ksi steel grade, characterized in that: Its chemical composition by mass percentage is as follows: C 0.25~0.30, Si 0.17~0.37, Mn 0.9~1.30, Cr 0.9~1.4, Al 0.001~0.05, P≤0.015, S≤0.010 and RE 0.001~0.003, with the remainder being Fe and trace impurities, totaling 100% by mass. The preparation process and parameter control include: In the steelmaking process, the incoming molten iron must have P ≤ 0.012% and S ≤ 0.05%. A single-slag process is used for smelting, and the final slag basicity is controlled at 3.0-5.

0. Deoxidation and alloying are carried out using ferrosilicon manganese and ferromanganese, and the final deoxidation process uses an aluminum-containing deoxidation process. The LF process uses a method of gradually increasing the heating rate from low to high stages. Rare earth alloys are added before VD (Vacuum Deposition). The VD vacuum degree must be ≤ 0.10 kPa, and the deep vacuum time must be ≥ 15 minutes. After vacuum treatment, a 180-meter silicon-calcium wire is fed in, and the soft blowing time after wire feeding is ≥ 15 minutes. The continuous casting billet is controlled by a constant casting speed. During the rolling process, the billet is heated in the ring furnace as follows: heating stage 1: 700-920℃; heating stage 2: 900℃-1050℃; heating stage 3: 1000℃-1200℃; heating stage 4: 1200℃~1275℃; heating stage 5: 1250℃-1275℃; heating stage 6: 1230℃-1250℃; piercing temperature of round billet: 1200℃~1250℃; rolling temperature of steel pipe: 1000℃~1200℃. The quenching and tempering process includes: quenching furnace → heating → water quenching → tempering furnace → heating → heated straightening → cooling bed; the heat treatment regime is: quenching furnace 890℃±10℃, holding for 30min~50min; after the steel pipes come out of the furnace, they undergo internal and external water quenching, with water temperature <30℃ and water volume >450m³. 3 / min, water pressure ≥5MPa, water quenching time adjusted according to wall thickness specifications; tempering furnace 660℃±20℃, holding for 50min~70min, steel pipes are air cooled after being taken out of the furnace.

2. The method for preparing high-strength, crush-resistant oil well tubing containing rare earth 110ksi steel grade according to claim 1, characterized in that: Its chemical composition by mass percentage is as follows: C 0.25%, Si 0.17%, Mn 1.0%, Cr 1.40%, Al 0.01%, P 0.015%, S 0.009%, RE 0.001%, with the remainder being Fe and unavoidable impurities, totaling 100% by mass.

3. The method for preparing high-strength, crush-resistant oil well tubing containing rare earth 110ksi steel grade according to claim 1, characterized in that: Its chemical composition by mass percentage is as follows: C 0.26%, Si 0.19%, Mn 1.05%, Cr 1.10%, Al 0.03%, P 0.014%, S 0.008%, RE 0.002%, with the remainder being Fe and trace impurities, totaling 100% by mass.

4. The method for preparing high-strength, crush-resistant oil well tubing containing rare earth 110ksi steel grade according to claim 1, characterized in that: Its chemical composition by mass percentage is as follows: C 0.28%, Si 0.20%, Mn 1.10%, Cr 0.95%, Al 0.023%, P 0.013%, S 0.003%, RE 0.003%, with the remainder being Fe and trace impurities, totaling 100% by mass.

5. The method for preparing high-strength, crush-resistant oil well tubing containing rare earth 110ksi steel grade according to claim 1, characterized in that: Its chemical composition by mass percentage is as follows: C 0.29%, Si 0.30%, Mn 1.250%, Cr 0.98%, Al 0.04%, P 0.012%, S 0.002%, RE 0.002%, with the remainder being Fe and trace impurities, totaling 100% by mass.

6. The method for preparing high-strength, crush-resistant oil well tubing containing rare earth 110ksi steel grade according to claim 1, characterized in that: Its chemical composition by mass percentage is as follows: C 0.30%, Si 0.37%, Mn 1.30%, Cr 1.05%, Al 0.04%, P 0.011%, S 0.001%, RE 0.003%, with the remainder being Fe and trace impurities, totaling 100% by mass.

7. The method for preparing high-strength oil well tubing containing rare earth 110ksi steel grade according to claim 1, characterized in that: Its mechanical properties: longitudinal impact toughness at 0℃ ≥76J.

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