Publications

A series of petroleum supersystems have been identified in Australia ranging in age from Proterozoic to Cainozoic. Each supersystem has been divided into a number of regional systems based on an understanding of the distribution of organic-rich-rocks (ORRs) that appear to have generated hydrocarbons. Petroleum discovered in the sedimentary basins of the North West Shelf of Australia appear to be part of four supersystems, the Larapintine, Transitional, Gondwana and Westralian. However, because most of the information on the supersystems and their component systems is derived from trapped hydrocarbons and on-structure penetrations of ORRs, the picture is very incomplete.How many systems are present on the North West Shelf? How many should we expect to find? Five approaches are being pursued in an effort to provide reliable answers to these questions. The first involves determining whether sediments were deposited in basins in the North West Shelf during periods of global or more widespread ORR deposition. Secondly, a tectonostratigraphic framework for the North West Shelf is under construction to help predict the most likely periods of ORR deposition. ORRs are most likely to be preserved during periods when the rate of generation of sediment accommodation space is at a maximum, often at the beginning of a new basin phase. In addition, a more detailed analysis of the structural/stratigraphic framework, aimed at defining the distribution and character of ORRs and the drainage divides between them within each basin phase in specific sub-basins, constitutes the third approach. The fourth approach involves multivariate statistical analysis of geochemical data derived from liquid hydrocarbons obtained from wells in most areas of the North West Shelf. Up to twenty-three attributes have been correlated to define a number of 'oil families'. The oil families have been mapped geographically to gain insights into the location of the likely sources for the liquids. In addition, we hope to undertake a regional gas maturity study. Lastly, a regional study of trap integrity and charge history of a number of the systems is presently underway and an information system to access petroleum systems, plays and play elements within the tectonostratigraphic framework, is under construction. The combination of petroleum systems and basin analysis techniques is paying off. One new regional system has been defined and it is suggested that at least 5 more regionally significant systems exist on the North West Shelf.