High temperature resistant steel for oil well pipe and its manufacturing method

Abstract

The invention relates to high temperature resistant steel for an oil well pipe. The steel is composed of the following chemical components by mass: 0.05-0.15% of C, 0.15-0.45% of Si, 0.3-0.6% of Mn, 8.5-14.0% of Cr, 0.004-0.016% of N, 0.01-0.05% of Al; and at least three of, less than or equal to 0.15% of V, less than or equal to 0.05% of Ti, less than or equal to 0.05% of Nb, less than or equal to 1.5% of Mo, and less than or equal to 1.5% of W; and the balance Fe as well as unavoidable impurities. The manufacturing method of the high temperature resistant steel for an oil well pipe comprises: smelting molten steel, and conducting continuous casting so as to obtain a round billet or casting the smelted molten steel into a square billet which is then rolled into a round billet; rolling the billet into a seamless steel pipe, then conducting normalizing at a temperature of 900-1100DEG C for 30-120min; then carrying out high temperature tempering at a temperature of 680-750DEG C, and keeping tempering insulation for 60-90min. The high temperature resistant steel for an oil well pipe in the method has yield strength constantly greater than 350MPa in a use temperature range of room temperature to 600DEG C, and an oxidation speed of less than 2 micrometers / y.

Description

technical field [0001] The invention relates to a steel for oil well pipes for oil and gas wells, in particular to a steel for high temperature resistant oil well pipes for fire flooding oil production with a service temperature up to 600°C and a manufacturing method thereof. Background technique [0002] Heavy oil occupies a large proportion of the world's oil and gas resources. my country is rich in heavy oil resources. Oil fields such as Liaohe Oilfield, Karamay Oilfield, Shengli Oilfield and Dagang Oilfield are the main heavy oil development areas in my country, and there is great potential for heavy oil exploitation. In the production process of heavy oil, in order to increase the temperature of the oil layer, reduce the viscosity of the heavy oil, and make the heavy oil easy to flow, so as to extract the heavy oil, there are thermal oil recovery methods such as steam huff and puff, steam flooding, hot water flooding, and burning the oil layer. method. Among them, fir...

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Problems solved by technology

[0005] Existing high-temperature oil casing products are mainly made of plain carbon steel, Cr-Mo steel or Cr-Mo low-alloy steel containing W, such as the products designed in Chinese patent applications with publication numbers CN1873041A, CN1401809A, and CN1904120A. The operating temperature is lower than 400°C, and the high temperature oxidation resistance is very poor

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