A kind of 125ksi steel grade anti-sulfur oil well pipe and its manufacturing method

Abstract

The invention discloses a 125ksi steel grade sulfur-resistant oil well pipe, the mass percentage of chemical elements is: C: 0.20-0.30%, Si: 0.1-0.5%, Mn: 0.2-0.6%, Cr: 0.30-0.70%, Mo : 0.60~1.00%, V: 0.10~0.20%, Nb: 0.01~0.06%, Ti: 0.015~0.035%, W: 0.20~0.60%, Al≤0.1%, N≤0.008%, the balance is Fe and others unavoidable impurities. The invention also discloses a method for manufacturing the above-mentioned 125ksi steel grade sulfur-resistant oil well pipe, which includes the steps of: (1) preparing the pipe blank; (2) piercing and hot rolling the pipe blank to obtain a blank pipe; Controlled cooling; (4) Quenching+tempering: the quenching temperature in the quenching step is Ac3+(30~50°C), where Ac3(°C)=910‑203[C%] 1 / 2 +44.7[Si%]+104[V%]+31.5[Mo%]+13.1[W%], then water quenching, the water quenching speed is ≥30℃ / s; the tempering temperature in the tempering step is 680~700℃ , then air cool.

Description

technical field [0001] The invention relates to an oil well pipe and a manufacturing method thereof, in particular to a sulfur-resistant oil well pipe and a manufacturing method thereof. Background technique [0002] With the increasing depletion of oil and natural gas, the exploitation and development of oil and gas are developing towards deep wells and ultra-deep wells. Correspondingly, the environment of oil and gas wells has higher pressure, higher temperature and higher corrosiveness, especially the Hydrogen sulfide corrodes the medium, which puts forward higher requirements for the strength and hydrogen sulfide stress corrosion resistance of oil well pipe materials. [0003] In the American Petroleum Institute Standard Casing and Tubing Specifications (API Spec 5CT), the existing standardized sulfur-resistant pipe steel grades have yield strengths of 80ksi (that is, 551MPa), 90ksi (that is, 620MPa), and 95ksi (that is, 655MPa) And 110ksi (that is, 758MPa), and the sul...

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Problems solved by technology

[0004] The publication number is CN103160752A, and the publication date is June 19, 2013. The Chinese patent document entitled "A High-Strength Seamless Steel Tube with Excellent Low-Temperature Toughness and Its Manufacturing Method" discloses a high-strength seamless steel tube with excellent low-temperature toughness. Its composition is: C: 0.15% ~ 0.20%, Si: 0.20% ~ 0.30%, Mn: 0.20% ~ 0.50%, P: ≤0.010%, S: ≤0.003%, Cr: 0.6% ~ 0.8%, Mo: 0.4%~0.7%, Ni: 1.0%~1.4%, Nb: 0.01%~0.035%, Als: 0.01%~0.05%, the Cr-Mo-Ni system is used to obtain the 125ksi steel grade oil well pipe, although the toughness is obtained Significantly improved, the impact energy at -60°C reaches over 40J, but there is no guarantee of sulfur resistance

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