Abstract

During diagenesis and conversion of the original lipid fraction of biological systems to petroleum hydrocarbons, the following four basic events needed for paleoreconstruction can be monitored by biological markets: (1) sourcing, (2) maturation, (3) migration, and (4) biodegradation.

Actual cases of applying biological markers to petroleum exploration problems in different parts of the world are demonstrated.

Cretaceous – and Phosphoria-sourced oils in the Wyoming Thrust Belt can clearly be distinguished from one another by high quality source fingerprinting of biomarker terpanes using gas chromatography mass spectrometry. Identification of recently discovered biological markers, head-to-head isoprenoids, allows subtle source differentiation between oils from Sumatra.

The degree of crude oil maturation in basins from California, Alaska, Russia, Wyoming, and Louisiana can be assessed by specific novel biomarker ratios (20S/20R sterane epimers).

Field evidence from such interpretation is confirmed by laboratory pyrolysis of the rock. An example of immature Sumatra rock is given.

Extensive migration is documented by biomarkers in several oils.

The effect of biodegradation on biomarker steranes and terpanes is exemlified in a California basin.

All biological marker results are consistent with the geological setting and add a new dimension in assisting the petroleum explorationist toward paleo-reconstruction.