Exploratory Analysis of Campos Basin Crude Oils via Geochemical Parameters by Comprehensive Two-Dimensional Gas Chromatography/Time-of-Flight Mass Spectrometry

Abstract

Comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC–TOFMS) was used for geochemical characterization of 18 oil samples from Campos Basin, Brazil. Conventional analyses were also performed on these oils (API gravity and GC-FID) and in the maltenic fraction (saturated, aromatic, and polar analysis) after asphaltene precipitation, aiming the oil screening for a rapid assessment of general characteristics. The results from principal component analysis with the biomarker parameters of source, maturity, and biodegradation obtained by GC×GC–TOFMS separated the oils into two groups, mainly explained by gammacerane content. The higher sensitivity and resolution of GC×GC–TOFMS allowed the identification of unusual compounds in oils from this basin, such as methylhopanes (whose calculated ratios allowed the oils in this work to be classified as having a marine, lacustrine, or “mixed” source, the same interpretation obtained by statistical analysis), moretanes (with results that reinforce the hypothesis of same thermal evolution for the studied samples), and short-chain steranes (C21 and C22), detected in very low concentrations in all of the samples. This study is the first to show the presence of these compounds in Campos Basin crude oils.

Estudo in Silico De Estruturas Asfaltênicas Utilizando Dinâmica Molecular E Teoria Do Funcional Da Densidade

“…Em geral considera-se petróleos ácidos, com alto potencial de corrosão, aqueles com TAN maior que 0,5 mg de KOH/g de óleo (SLAVCHEVA et al, 1999;TERRA et al, 2014;DIAS et al, 2014) Os maiores níveis de biodegradação para as amostras C05 e C08 são consistentes com os valores das razões Pr/n-C17 e Ft/n-C18 desses óleos (SANTOS et al, 2018).…”

Application of the Electron Spin Resonance Technique in the Characterization of Brazilian Oils: Correlation with Their Biodegradation Level and Polar Composition

“…The maltenic fraction of the crude oil samples was fractioned into three other fractions, saturated hydrocarbons, aromatic hydrocarbons, and resins . Approximately 0.2 g of the maltenic fraction was used in liquid chromatography with previously activated (120 °C for 12 h) silica gel, and the saturated, aromatic, and resin fractions were eluted with 40 mL of n -hexane, n -hexane:dicloromethane (6:4 v/v), and dicloromenthane:methanol (9:1 v/v), respectively, on the basis of the work of Santos et al (all solvents with chromatographic grade). For the C19 and C10 crude oil samples, finally 40 mL of methanol was used to recover the resin fractions.…”

“…Asphaltene Precipitation. On the basis of the work of Santos et al 28 asphaltenes were precipitated from 2 g crude oil samples with 60 mL of n-hexane (chromatographic grade) using an ultrasonic bath for 10 min. After precipitation, the asphaltene fraction was separated from the maltene fraction by filtration in atmospheric pressure and washed four times with 60 mL of n-hexane.…”

Comprehensive Two-Dimensional Gas Chromatography Advances in Technology and Applications: Biennial Update

“…The composition of crude oils was the focus of many works in the past 2 years. ,,,− The work of Brazilian research groups led by Azevedo − and Augusto ,,,, focus on determining geochemical fingerprinting of samples from many regions in the country and optimizing methods for the resolution of crude oils and diesel composition. The use of GC×GC−TOFMS and other techniques such as Fourier transform ion cyclotron resonance-mass spectrometry (FTICR-MS) enabled the identification not only of hydrocarbons but also oxygen-, nitrogen-, and sulfur-containing volatile and nonvolatile compounds in crude oils with minimal sample preparation, with the latter promoted as a no-fractionation petroleomics technique. , GC×GC coupled with a VUV photoionization source TOFMS detector enabled the direct characterization and determination of the total sum of aromatic and aliphatic hydrocarbon species in different crude oils …”