Linking the geochemistry of crude oils and petroleum inclusions in the Ubarana and Lorena oilfields, Potiguar Basin, Brazilian Equatorial Margin

Position-specific distribution of hydrogen isotopes in natural propane: Effects of thermal cracking, equilibration and biodegradation

“…For Type I/II kerogens, oil-associated gases are commonly the primary gases of kerogen cracking, whereas non-associated gases are the secondary gases from further cracking of oil. The majority of our sample set are gases derived from Type II kerogen, except for the Potiguar sample, which was generated from a lacustrine section (the Lower Cretaceous (130 Ma) Pendência Formation) mainly related to an organic-rich shale with Type I kerogen(Pestilho et al, 2018). The source origin of the nonassociated Hogsback gas is unclear, though we favor an interpretation that it is a primary gas derived from a more gas-prone mixed Type II/III source rock, based on the  18 apparent temperature of its methane, compound specific  13 C of methane, ethane and propane, and biomarker data (not presented here) of co-produced condensate.…”