Steel oil well pipe having excellent sulfide stress cracking resistance

A technology for steel pipes and oil wells, applied in the direction of improvement of process efficiency, furnace type, furnace, etc., to achieve the effect of excellent SSC resistance

Active Publication Date: 2014-04-30
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, recently, the use of oil country tubular goods with a strength grade of 110 ksi (yield strength 110 to 125 ksi, that is, yield strength 758 to 861 MPa) has increased.

Method used

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  • Steel oil well pipe having excellent sulfide stress cracking resistance
  • Steel oil well pipe having excellent sulfide stress cracking resistance
  • Steel oil well pipe having excellent sulfide stress cracking resistance

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0128] Steel pipes for oil wells with various chemical compositions are manufactured under various manufacturing conditions. The SSC resistance of the produced steel pipe for oil well was evaluated.

[0129] [Manufacturing method of steel pipe for oil well]

[0130] Molten steels of steels A to J having the chemical compositions shown in Table 1 were produced.

[0131]

[0132] A round billet with a diameter of 310 mm was produced by a continuous casting method using molten steel (230 tons) of steels A to J. The round billets were heated in a heating furnace under the billet heating conditions shown in Table 2. The heated round steel billet is pierced and rolled according to the Mannesmann method to manufacture a tube billet. The blank pipe was quenched at the quenching temperature shown in Table 2, and tempered at the tempering temperature shown in Table 2 to manufacture steel pipes for oil wells. Adjust the quenching and tempering conditions so that the yield strength...

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Abstract

Provided is a steel oil well pipe which has excellent sulfide stress cracking resistance (SSC resistance). A steel oil well pipe of the present invention contains, in mass%, 0.15-0.35% of C, 0.1-0.75% of Si, 0.1-1.0% of Mn, 0.1-1.7% of Cr, 0.1-1.2% of Mo, 0.01-0.05% of Ti, 0.010-0.030% of Nb, 0.01-0.1% of Al, 0.03% or less of P, 0.01% or less of S, 0.007% or less of N and 0.01% or less of O, with the balance made up of Fe and impurities. The Ti content and the Nb content in the residue obtained by bromine-methanol extraction satisfy the following formula (1). 100*[Nb] / ([Ti] + [Nb]) <= 27.5 (1) In this connection, the Ti content (mass%) and the Nb content (mass%) in the residue are respectively assigned to [Ti] and [Nb].

Description

technical field [0001] The present invention relates to steel pipes, in particular, to steel pipes for oil wells. Background technique [0002] Steel pipes for oil wells are used as casings or pipes for oil and gas wells. Oil wells and gas wells are collectively referred to as "oil wells" hereinafter. With the deepening of oil wells, high strength is required for oil well pipes. In the past, 80ksi grade (yield strength of 80 to 95ksi, that is, yield strength of 551 to 654MPa) or 95ksi grade (yield strength of 95 to 110ksi, that is to say, yield strength of 654 to 758MPa) was mainly used. Oil well pipe. However, recently, the use of oil country tubular goods having a strength grade of 110 ksi class (yield strength 110 to 125 ksi, that is, yield strength 758 to 861 MPa) has been increasingly used. [0003] Recently developed deep oil wells contain corrosive hydrogen sulfide. Under such circumstances, if the strength of steel is increased, the susceptibility of steel to su...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C22C38/28C22C38/32C21D9/00
CPCC21D8/105C22C38/22C22C38/32C22C38/04C22C38/24C22C38/28C22C38/001C22C38/002C21D9/00C22C38/26C22C38/02C22C38/00C21D9/08C22C38/06C21D9/085Y02P10/20
Inventor 相马贵志大村朋彦荒井勇次沼田光裕高山透妹尾昌尚
Owner NIPPON STEEL CORP
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