An oil casing resistant to sulfide stress cracking

Abstract

The present invention discloses a sulfide stress cracking resistance tubing and casing, and a production method thereof, and belongs to the field of tubing and casing. The components of the tubing and casing comprise, by mass, 0.12-0.20% of C, 0.15-0.40% of Si, 0.30-1.0% of Mn, 0.50-1.60% of Cr, 0.60-1.20% of Mo, 0.50-2.0% of Ni, 0.02-0.08% of Nb, 0.005-0.015% of Ti, 0.01-0.10% of Al, 0.001-0.01% of Ca, 0.005-0.03% of N, less than 0.015% of P, less than 0.01% of S, less than 0.001% of B, and the balance of Fe and other unavoidable impurities. According to the present invention, the contents of Cr, Mo, Ni and Nb are optimized, and the C content is reduced so as to control the ratio of the average Cr concentration to the average Fe concentration in the M23C6 type carbide, the M3C type carbide and the carbide in the tempering martensite structure within a certain range, such that the tubing and casing with the fine and uniform tempering martensite structure is obtained, it is ensured that the steel grade achieves 125 ksi or above, and the tubing and casing concurrently has characteristics of high strength, SSC resistance and high toughness.

Description

technical field [0001] The invention relates to the field of oil pipes and casings, in particular to a 125ksi steel grade low-alloy oil pipe and casing with high resistance to sulfide stress cracking and a manufacturing method thereof. Background technique [0002] containing H 2 S, CO 2 and Cl - During the development of highly acidic oil and gas fields with corrosive media, tubing and casing (referred to as tubing and casing) will not only undergo weight loss corrosion and localized corrosion with a high corrosion rate, but also sulfide stress cracking (sulfide stress cracking referred to as SSC) . Severe corrosion coexisting in various forms poses a huge challenge to the anti-corrosion technology of oil casing. [0003] At present, there are usually two protective measures for the corrosion of tubing and casing in high acid gas fields: the first is to use super 13Cr, 22Cr stainless steel or nickel-based alloy pipes; the second is to use carbon steel or low alloy steel...

AI Technical Summary

Problems solved by technology

There are two defects of this technology: one is that there is no grain refinement element, and the C content is too high, and C is easy to form coarse grained M with Cr. 23 C 6 Type carbide, can not guarantee good impact toughness and good SSC resistance

Second, the total amount of alloying elements is low, and the final product cannot guarantee a high content of tempered martensitic structure, so it cannot be guaranteed that the steel grade of the oil casing pipe reaches 125ksi or above

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