Study of naphthenic acidity and corrosivity of Brazilian crude oils by ESI(-) FT-ICR MS

Abstract

In the last years most of the petroleum reserves discovered in Brazil, except for the large pre-salt reserves, as well in many parts of the world, contain unconventional oils with lower API gravity and high total acid number (TAN). The main species responsible by the high acidity are the naphthenic acids, which also leads to several problems in the petroleum industry, such as corrosivity in both up and downstream production processes. In this context, the aim of this work was to study the naphthenic acidity and corrosiveness of 35 Brazilian crude oil samples using the relative abundance of O2 class, obtained via Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) with electrospray ionization (ESI) in negative ion mode, and correlate it with the TAN and corrosion rate in a stainless steel type (316L). It was observed poor correlation between O2 class abundance and TAN, probably due to others heteroatom compounds that contribute to total acidity. Besides, %O2 is likely more reliable to evaluate petroleum corrosivity than TAN, based on corrosion testes using a 316L steel cupons.