The complex geochemical characteristics of crude oils can provide important information on oil generation, such as the input of organic matter and their depositional environments, also supporting exploration, extraction, and production. This work reports the first organic geochemical evaluation of oils from the first commercial Brazilian onshore field (Carmopolis, Sergipe, Brazil) via both classical biomarkers and petroleomics data collected via ultrahigh-resolution and accuracy Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Gas chromatography/mass spectrometry (GC/MS) was used to characterize the oil composition in terms of n-alkane, isoprenoid, terpane, and sterane biomarkers, whereas either positive or negative electrospray ionization (ESI) and FT-ICR were used to profile the polar constituents of the oils. GC/MS revealed geochemical characteristics that classify the oil at different levels of thermal evolution and biodegradation. FT-ICR MS attributed molecular formulas to more than 3000 polar oil constituents, allowing geochemical parameters to be inferred mainly from the carbon number (Cn) and double bond equivalent (DBE) trends, along with the N and O-2 classes. The Dia27(S + R)/alpha alpha alpha C-27(S + R), % C-28, and % C-29 parameters and S/(S + R)alpha alpha alpha C-29, alpha beta beta(S + R)/alpha beta beta + alpha alpha alpha(S + R)C-29, and % C-27 biomarkers obtained from GC/MS were responsible to indicate similarity between samples, whereas N and O-2 classes provided the most distinction among the crude oil blends in terms of the level of biodegradation and thermal maturity.