Steel for high-frequency resistance welding petroleum casing pipe, casing pipe and manufacturing method thereof

Abstract

The invention relates to steel for a petroleum casing pipe. The steel for the petroleum casing pipe comprises the components in percentage by mass: 0.05 to 0.10 percent of C, 0.10 to 0.30 percent of Si, less than 0.015 percent of P, less than 0.003 percent of S, 0.1 to 0.3 percent of Mn, 2 to 2.5 percent of Cr, 0.01 to 0.04 percent of Al and the balance of Fe and unavoidable impurities, wherein the total amount of impurity elements is less than 0.05 weight percent; and the carbon equivalent is not greater than 0.6. The invention also relates to the petroleum casing pipe made of the steel. The manufacturing method for the steel comprises the following processes of: a hot rolling process of the steel for the petroleum casing pipe: the finish rolling temperature is 850 to 890 DEG C, and the coiling temperature is 620 to 660 DEG C; a carbon dioxide gas protection welding process for coiled plate butt welding: the wire feeding speed is 12 to 14 m / min, the current is 557 to 561 A, the welding speed is 52 to 54 cm / min, and the gas flow is 23 to 25 L / min; and overall pipe heat treatment: heating and keeping the temperature of 900 to 950 DEG C for 40 to 70 minutes, tempering at the temperature of 620 to 650 DEG C after water quenching, and keeping the temperature for 60 to 80 minutes. The high-frequency resistance welding petroleum casing pipe provided by the invention has the steel grade of 80 ksi and high carbon dioxide corrosion resistance; and the annual average corrosion rate of a finished pipe is below 1 / 3 of that of a conventional N80 oil well pipe.

Description

technical field [0001] The invention relates to an oil casing, in particular to a steel for high-frequency resistance welding oil casing used in a carbon dioxide environment, and the 80ksi steel grade made of the steel has anti-CO 2 High frequency resistance welded petroleum casing with corrosion performance and manufacturing method thereof. Background technique [0002] At present, the CO of oil well pipe products used in the development of oil and gas fields 2 Corrosion problems are becoming more and more significant in CO 2 In the corrosive environment of chloride ions, most of the foreign countries use expensive seamless 13Cr stainless steel pipes, which can effectively ensure the long-term safe and efficient production of oil fields. Some domestic oil fields use seamless 13Cr products, and some users use lower-priced seamless pipes. Sew 3Cr products. However, in terms of economy, because most of my country's oil fields are lean ore and low-permeability oil fields, an...

AI Technical Summary

Problems solved by technology

[0008] about anti-CO 2 Corrosion (or CO 2 and H 2 Most of the alloy steels used for S corrosion) are high-alloy products such as 13Cr, 15Cr and 22Cr duplex stainless steel, and the carbon equivalent exceeds 0.6. They are suitable for the production of seamless steel pipes, but not suitable for the production of ERW welded casings.

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