Effect of secondary oil migration distance on composition of acidic NSO compounds in crude oils determined by negative-ion electrospray Fourier transform ion cyclotron resonance mass spectrometry

Abstract

The acidic and neutral NSO compounds in a series of Duvernay-sourced oils in Canada, which are believed to have migrated extensively over relatively long distances such as along the Rimbey-Meadowbrook reef trends, were characterized by negative-ion electrospray (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Heteroatomic compounds were characterized according to their class (number of nitrogen, oxygen and sulfur heteroatoms), degree of aromaticity [rings plus double bonds (DBE)] and carbon number distribution. The N1, N1O1, N1O2, N1S1, O1 and O2 classes were identified in Duvernay-sourced oils. With increasing migration distance, the relative abundance of O2, N1O1 and N1O2 showed a significant decrease, while the O1 class increased from <10% to nearly 30% of the total. With increasing migration along the Rimbey-Meadowbrook reef trend, pyrrolic nitrogen compounds (N1 class) shows an enrichment of alkylcarbazoles (DBE=9) relative to alkylbenzocarbazoles (DBE=12), and of higher homologous relative to the lower homologous. O1 compounds show a relative enrichment of those with low DBE values. Additionally, the N1O1 and N1S1 compounds show a relative enrichment of those with high DBE values, and of higher homologues compared to the lower homologues, indicating great potential for developing new migration indices.