Corrosion of matrials in the petroleum industry

The objectives of the oil industry are to extract, transport and refine oil in very large quantities under the most efficient economic conditions and with optimum safety and equipment reliability. In 2008, 88.7 million barrels of oil were refined worldwide every day. The cost of corrosion in this industry corresponds to around 3.7% of the overall cost of corrosion. For the global oil industry, a cost of 35 billion dollars per year has been estimated, due to direct and indirect impacts, as well as to control and prevention measures. Per barrel of oil produced, the cost of corrosion is approximately $0.3 to $0.6 per barrel. These figures do not include unforeseen events. For example, in 2006, leaks caused by bacterial corrosion shut down Alaskan oil production for several days, causing severe tensions on the oil market. The environmental impact of such accidents can also be considerable.

The oil industry is traditionally divided into two main areas: upstream oil (which corresponds to the drilling, production and transportation of crude oil), and downstream oil (where the oil is refined into kerosene, gasoline, diesel, fuel oils, naphtha, basic chemical compounds...). This industry is also required to eliminate the acid gases (CO ₂ and/or H ₂ S) associated with crudes throughout its chain.

The various stages of acid gas production, refining and processing are carried out in certain common chemical environments (which may be encountered in other industries) or in specific environments. In offshore production, for example, marine corrosion is an important factor in material selection. This aspect will not be developed in this article, the reader being invited to consult the articles in Techniques de l'Ingénieur dedicated to this environment. The same applies to high-temperature oxidation.

In the presence of liquid water, acid gases (CO ₂ and/or H ₂ S) can strongly corrode oil production equipment, but also in refineries as well as in units processing these gases. These acid gases are removed by processes involving chemical solvents (amine-based) which can strongly attack certain steels. Bacteria present in aqueous oil effluents can also be responsible for very rapid corrosion phenomena (with speeds of up to 15 mm/year).

Oil refining operations involve processes whose operating conditions can be highly corrosive, due to the chemical nature of the environments and the high pressures and temperatures involved: phenomena such as hydrochloric acid formation by salt hydrolysis, attack by carboxylic acids (naphthenic) present in certain crude oils,...