Low-alloy steel for resisting carbon dioxide corrosion and manufacturing method thereof

Abstract

The invention discloses low-alloy steel for resisting carbon dioxide corrosion. The low-alloy steel comprises the following chemical components in percentage by weight: 0.20 to 0.35 percent of C, 0.10 to 1.0 percent of Si, 0.20 to 1.5 percent of Mn, 0.5 to 1.5 percent of Cr, 0.02 to 0.1 percent of V, 0.01 to 0.10 percent of Al and the balance of Fe and inevitable impurities, wherein the total amount of the impurity elements is lower than 0.05 weight percent. A manufacturing method for the low-alloy steel for resisting the carbon dioxide corrosion comprises steel making, continuous casting, hot rolling and normalizing in a two-phase area at the temperature of between 820 and 870 DEG C. The strength of the alloy steel reaches 80ksi level, the alloy steel has good CO2 corrosion resistance and low price, and an oil well pipe made of the alloy steel can be widely applied to an oil gas well with light CO2 corrosion resistance.

Description

technical field [0001] The invention relates to low-alloy steel, in particular to 80ksi steel-grade low-alloy steel for carbon dioxide corrosion-resistant oil well pipes and a manufacturing method thereof. Background technique [0002] CO 2 Corrosion is one of the long-standing major problems in the development of oil and gas fields. For medium and above CO 2 The use of super 13Cr stainless steel pipes is the most effective way to ensure the safe and efficient production of oil fields due to partial pressure, high chloride ion content, low pH value, high pressure in the well and fluid erosion. However, for most lean ore and low-permeability oil fields with short mining life in my country, it is not economical to use high-chromium stainless steel tubing. For this reason, Baosteel has developed economical 3Cr series anti-CO 2 Corrosion oil casing products. [0003] For example, the Chinese patent application with publication number CN1401809A discloses a carbon dioxide cor...

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Problems solved by technology

[0007]With the change of production conditions, trace amounts of CO have appeared in many domestic and foreign oil and gas wells with low chloride ion content and no CO2 2, in view of this situation, the conventional N80 oil casing in the oil field can no longer meet the requirements of CO2 corrosion resistance, and the most advanced oil casing in the international and domestic markets The economical CO2 corrosion-resistant 3Cr series tubing is also difficult to achieve the best cost performance. For this reason, many domestic oil fields have put forward the demand for oil pipes that are slightly resistant to CO2 corrosion and have a reasonable cost performance

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