Plant biomarker study for oil source rock correlation in the Carnarvon Basin

Summary

This project applied recently developed biomarker technology to correlate oils and source rocks from the Carnarvon Basin, and to explore new approaches to the use of biomarkers for characterising crude oils and source rocks.

Results of a previous project M0220 had showed that higher plant derived biomarkers in sediments can provide a fingerprint characterising the time of deposition. Results of this study of the differences in distribution of aromatic biomarkers in crude oils and sediments resulted in several applications: oil source rock correlation, recognition of climate and sea-level changes over geological time, age correlation of sediments and accurate assessment of thermal maturities of crude oils in Jurassic sediments of the Barrow and Dampier Sub-basins.

The recently developed higher plant fingerprint (HPF) and higher plant index (HPI) parameters give insight into the nature and abundance of terrestrial organic matter. Depth profiles of HPF from three different wells covering the same age range (Jurassic) correlate extremely well. This is evidence that HPF may be characteristic of the time of deposition, and hence useful to correlate sedimentary sequences from different areas. Several events marking significant changes in HPF and HPI profiles were identified that correlate well with proposed boundaries of geological megasequences in the Carnarvon Basin.

Keywords: plant biomarkers, source rock correlation, sequence boundary, global sea-level change