Materials and corrosion trends in offshore and subsea oil and gas production

Abstract

The ever-growing energy demand requires the exploration and the safe, profitable exploitation of unconventional reserves. The extreme environments of some of these unique prospects challenge the boundaries of traditional engineering alloys, as well as our understanding of the underlying degradation mechanisms that could lead to a failure. Despite their complexity, high-pressure and high-temperature, deep and ultra-deep, pre-salt, and Arctic reservoirs represent the most important source of innovation regarding materials technology, design methodologies, and corrosion control strategies. This paper provides an overview of trends in materials and corrosion research and development, with focus on subsea production but applicable to the entire industry. Emphasis is given to environmentally assisted cracking of high strength alloys and advanced characterization techniques based on in situ electrochemical nanoindentation and cantilever bending testing for the study of microstructure-environment interactions.

Films Formed on Carbon Steel in Sweet Environments - A Review

“…Low carbon steels are the most commonly used materials because these are readily available in the market and can meet many of the mechanical, manufacturing and cost requirements. [1][2][3] Despite these advantages, carbon steels have relatively low corrosion resistance and require qualification for use in environments containing carbon dioxide, hydrogen sulfide and brine. [4][5][6] Corrosion occurs in several different ways, but two types are characteristic of these industries, sweet and sour corrosion.…”

“…When the inside walls of a pipeline suffer from corrosion, steel may lose its mechanical properties, which might lead to a catastrophic failure, causing huge losses. 3,8,15 Pipelines can suffer localized or generalized attack, depending on carbon steel, oil and operating conditions such as pressure, temperature and fluid dynamics. Localized corrosion arises from the existence of galvanic pairs formed between the predominant phase (e.g., ferritic phase) and the nonmetallic (e.g., MnS) or intermetallic (e.g., Fe 3 C) inclusions, 16 and it commonly manifests as pitting or mesa attack.…”

Effect of Nickel on the Hydrogen Stress Cracking Resistance of Ferritic/Pearlitic Low Alloy Steels

“…2 Likewise, an increasing number of reservoirs can be in the arctic region and exposed to extreme temperature gradients. 1,3,4 Harsh environments invoke strict material requirements. In this regard, researchers argue that, in the next 10 to 15 years, there will be an increased demand for low alloy steels (LAS) with a unique combination of mechanical, corrosion, and technological properties.…”

“…At present, carbon and low alloy steels exceeding the 1 wt% Ni restriction require complicated and expensive qualification testing, which often implies a de facto ban in allowable Ni content. 3 SSC is a form of hydrogen stress cracking (HSC) that results from the combined presence of atomic hydrogen in the metal and tensile stresses in an H2S environment. 8 One of the first reports suggesting a negative effect of Ni on SSC resistance was presented by Treseder and Swanson 9 in 1967.…”

A Study on Praseodymium 4-Hydroxycinnamate as an Inhibitor for Carbon Steel in Fresh Cooling Water System of Ca Mau Fertilizer Plant

“…Pitting corrosion is one of the forms of extremely localized attack causing holes in a metal, especially in chloride solution [6,7], which is often difficult to detect and becomes an insidious destructive process because of the small size of the pits and the coating of corrosion products [8]. To illustrate, the first step of the anodic dissolution of Fe in chloride solutions is the formation of passive oxide layer Fe x O y /Fe(OH) y covering the surface of the steel [9] to prevent contacting directly to the corrosion environment, according to the reaction (1,2). However, the passivating film is likely to be weaker and the potential difference between the layer and the defect in the steel surface increases, due to the mechanical damage of the film [10], caused by stress or particles of a second phase and therefore, the initial pits were formed.…”