Steel for oil casing pipe, oil casing pipe and manufacturing methods thereof

Abstract

The invention relates to steel for an oil casing pipe. The steel comprises the following chemical components by weight percent: 0.25-0.35% of C, 0.1-0.6% of Si, 0.8-1.5% of Mn, not more than 0.015% of P, not more than 0.003% of S, 1-1.5% of Cr, 1-1.5% of Mo, 0.05-0.12% of V, 0.02-0.04% of Nb, 0.01-0.04% of Ti, 0.01-0.08% of Al, 0.0005-0.005% of Ca and the balance of Fe and inevitable impurities. A steel pipe which is obtained through smelting, continuously casting, perforating and hot-rolling by using the components is insulated for 30-60 minutes at an austenitizing temperature of 880-930 DEG C, is cooled with air to 830-850 DEG C after discharged and undergoes water quenching, undergoes high-temperature tempering at 580-620 DEG C and is insulated for 40-80 minutes to obtain the oil casing pipe. The steel grade of the obtained oil casing pipe can be above 160ksi and the impact energy is above 70J. The obtained oil casing pipe has high strength and toughness.

Description

technical field [0001] The invention relates to an ultra-high-strength and high-toughness oil casing and a manufacturing method thereof, in particular to an ultra-high-strength and high-toughness oil casing above 160 ksi and a manufacturing method thereof. Background technique [0002] Casing is an indispensable special pipe suitable for oil and gas well completion operations such as deep wells and ultra-deep wells. Guarantee the function of drilling in various complex formations. In the next 10 years, the western oil fields will be one of the focuses of China's oil development. Western oilfield resources are buried extremely deep, with complex formations, usually several thousand meters in length, and the deepest well currently exceeds 8,000m. With the advancement of drilling technology, the pressure on bit and rotational speed have increased significantly, enhanced drilling technology has become more and more popular, and the production conditions such as thermal recover...

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Problems solved by technology

The design components mentioned in this patent are characterized by high carbon and high silicon. These two components can signific

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