Biomarkers: Assessment of Petroleum Source-Rock Age and Depositional Environment

Abstract

A common occurrence during petroleum exploration is the discovery of crude oil that may have migrated to the surface as a seep or to a porous and permeable reservoir rock far from its origin in an organic-rich, thermally mature petroleum source rock. Exploration risk for additional resources can be reduced, provided that one can link the oil sample to a source rock in the basin, thus establishing a petroleum system and effective migration pathways that may include additional traps and reservoirs. Despite complexity introduced by migration, a petroleum system can be established by direct oil-source rock correlation, provided that the oil and an extract of the mature source rock are available for biomarker analysis. Even when samples of the source rock are unavailable, biomarkers in oil that were inherited from the source rock can be used for indirect correlation because they provide information on its character, including the type of organic matter, lithology, redox conditions during deposition, and age.