The Oils of Western Australia II report summarises the findings of a collaborative research program between Geoscience Australia and GeoMark Research undertaken on the petroleum geochemistry of crude oils and condensates discovered within the basins of western Australia and the Papuan Basin, Papua New Guinea prior to March 2000. The interpretations documented herein build on research that Geoscience Australia and GeoMark Research undertook previously in The Oils of Western Australia (AGSO and GeoMark, 1996) and The Oils of Eastern Australia (Geoscience Australia and GeoMark, 2002) studies.
To make informed decisions regarding Australia's petroleum resources, it is important to understand the relationship between the liquid hydrocarbons within and between basins. This Study has geochemically characterised the liquid hydrocarbon accumulations of western Australian basins and the Papuan Basin into genetically related families. From a total of 316 samples, 33 oil/condensate families were identified in the western Australian basins; Bonaparte (10), Browse (2), Canning (4), Carnarvon (11) and Perth (6), as well as some vagrant and contaminated samples. Three oil/condensate families were recognised in the Papuan Basin. The geographic distribution of each oil/condensate family is mapped within each basin/sub-basin. Using the geochemical characteristics of each family, the nature of their source facies, thermal maturity level and degree of preservation has been determined.
This Study used a set of standardised geochemical protocols that include bulk geochemical (API gravity, elemental analysis of nickel, vanadium and sulphur), molecular (gas chromatography of the whole-oil and gas chromatography-mass spectrometry of the saturated and aromatic hydrocarbons) and bulk stable carbon isotopic analyses. n-Alkane-specific 13C isotopic analyses were carried out on only a selected set of oils and condensates. Statistical analyses were performed on these data using the software Pirouette provided by Infometrix.
In addition to this report, the geochemical data acquired for the crude oils and condensates in this Study are provided in the accompanying Microsoft Access2000 database. These data may be viewed spatially and plotted on x-y cross-plots in the charting application included in the ESRI Australia GIS ArcView3.2 georeferencing package that also accompanies this report.