Low alloy steel for the pipe for oil well use and seamless steel pipe

A seamless steel pipe and low-alloy technology, which is applied in the field of seamless steel pipe and low-alloy oil well pipe steel, can solve the problems such as uncertain prevention methods, and achieve the effect of superior HIC resistance and SSC resistance

Active Publication Date: 2009-09-23
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Therefore, the method of preventing HIC and SSC in the case of using low-alloy oil well pipes in a high hydrogen sulfide environment has not yet been determined.

Method used

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  • Low alloy steel for the pipe for oil well use and seamless steel pipe
  • Low alloy steel for the pipe for oil well use and seamless steel pipe
  • Low alloy steel for the pipe for oil well use and seamless steel pipe

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Embodiment

[0068] Next, in order to examine the effects of the present invention, steels having the chemical compositions shown in Table 1 and Table 2 were melted and various properties were evaluated. Steels A~B, steels L~O, steels P~T, steels d~e, and steels w~aa are steel billets formed after melting, and are pierced and rolled to form seamless steel pipes. For other steels, steel ingots with a thickness of 40 mm are taken by hot forging, and these ingots are hot-rolled to a thickness of 12 mm to form plates.

[0069] In addition, the cooling rate in the temperature range of 1500-1200°C after melting was 20°C / min for steels A and B, 100°C / min for steels C-D, and 500°C / min for steels E-K. In addition, in steels A and B, S, N, and O (oxygen) were controlled to be 0.003% or less, 0.005% or less, and 0.001% or less, respectively. The cooling rate of steels L to O and steels d to e was 150° C. / minute, and that of steels a to c and steels f to v was 500° C. / minute. In addition, the coolin...

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Abstract

The invention aims at providing a low alloy steel for the pipe for oil well use and a seamless steel pipe which are excellent in the resistance to sulfide stress cracking. A low alloy steel for the pipe for oil well use which exhibits a yield strength of 654 to 757MPa, characterized by having a composition which contains by mass C: 0.10 to 0.60%, Si: 0.05 to 0.5%, Mn: 0.05 to 3.0%, P: 0.025% or below, S: 0.010% or below, Al: 0.005 to 0.10%, O (oxygen): 0.01% or below, Cr: 3.0% or below and Mo: 3.0% or below in a total amount of Cr and Mo of 1.2% or above with the balance consisting of Fe and unavoidable impurities and by 10 or fewer non-metallic inclusions of 10[mu]m or above in length per mm as determined by observation of the section.

Description

technical field [0001] The present invention relates to a low-alloy oil well pipe steel used in environments containing hydrogen sulfide, such as oil wells and gas wells, and a seamless steel pipe made of the steel. Background technique [0002] In oil wells, gas wells, etc., oil well pipes of 80ksi grade (YS: 551-654MPa) have been used in the past, but as oil wells deepen, oil well pipes are required to have higher strength. Therefore, oil well pipes such as 95ksi grade (YS: 654-758MPa) and 110ksi grade (YS: 758-861MPa) have been used more recently. [0003] On the other hand, shallow wells with low corrosiveness have been exhausted, and deep wells with high corrosiveness containing high-pressure hydrogen sulfide above 2 atm have been excavated more and more in recent years. While high strength is required for oil well pipes used in such an environment, there is also a problem of hydrogen embrittlement called hydrogen induced cracking (Hydrogen Induced Cracking: HIC) and s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C22C38/22
CPCC22C38/002C22C38/06C22C38/26C22C38/02C22C38/28C22C38/12C22C38/04C21D9/08C21D8/12C22C38/32C22C38/24C22C38/22Y10T428/12292
Inventor 大村朋彦荒井勇次友松邦彰阿部俊治
Owner NIPPON STEEL CORP
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