Low alloy steel resisting CO2 and H2S corrosion

Abstract

The present invention is one kind of low alloy steel capable of being used in oil well pipe to resist CO2 and H2S corrosion. Chemically, its consists of C 0.01-0.30 wt%, Si 0.10-1.0 wt%, Mn 0.10-2.0, Cr 0.50-3.0 wt%, Mo 0.01-1.0 wt%, Ce 0.01-0.25 wt%, V 0.005-0.1 wt%, Cu 0.05-1.0 wt%, Al 0.01-0.10 wt% and small amount of Nb if necessary, except Fe and inevitable impurity, with impurity elements being less than 0.05 wt%. The alloy steel of the present invention after hardening and tempering has mechanical performance reaching the requirement on API 80 and 90 level steel but obviously improved CO2 and H2S corrosion resistance, and is economic oil well pipe steel with moderate cost.

Description

technical field [0001] The invention relates to a low-alloy steel, especially low-alloy steel for carbon dioxide and hydrogen sulfide corrosion-resistant oil well pipes. Background technique [0002] CO 2 and H 2 S corrosion has been a major problem restricting the development of oil and gas fields for a long time. 2 and H 2 Ordinary carbon steel pipes or simple anti-sulfur oil well pipes are used in the S corrosion environment, which has caused many serious corrosion accidents in the oil field, resulting in economic losses and the protective measures taken for this have seriously affected the economic benefits of the oil field. [0003] At present, severe CO is common in most oilfields. 2 and H 2 S corrosion problem. And each year due to CO 2 and H 2 Accidents caused by S corrosion have brought economic losses of more than 100 million yuan to oil fields. From the perspective of anticorrosion of materials, in high CO 2 and H 2 In the highly corrosive environment f...

AI Technical Summary

Problems solved by technology

Not only that, the patented composition only eliminates the steel's resistance to CO due to the absence of Cu elements 2 Local corrosion phenomenon, while the uniform corrosion rate of steel is still high

In addition, the addition of B element greatly increases the difficulty and cost of steel smelting; while the Cr content in JP 2000063994 patent steel is between 3.0 and 9.0%, which belongs to the category of medium alloy

Moreover, the composition of the patented steel is complex, and the cost of the alloy is greatly increased; the invention patent with the application number 00125882.6 is very easy to form TiN hard inclusions with the unavoidable element N in the steel due to the addition of the element Ti, so that the steel does not have resistance. Hydrogen sulfide corrosion performance