This product is an ArcView GIS CD containing coverages of North West Shelf regional geology and petroleum exploration themes, and oil family maps linked to graphs of specific chemical parameters which define the families. This product includes 120 oils from the first Oils of Western Australia study (WOZ1) and 150 oils from the second Oils of Western Australia study (WOZ2). This CD is one component of "The Oils of Western Australia II" product which comprises two other components: an interpretative report documenting the petroleum geochemistry of the oils in the study and assignment of each sample to an oil family, and a Microsoft Access database which contains the raw data, calculated biomarker ratios and reporting output forms. 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.

Legacy product - no abstract available

An inverted phase (polar to non-polar) column set has been compared with a non-polar to polar column set for the GC-GC separation of petroleum hydrocarbons crude oil. This is shown to provide greatly enhanced resolution for less polar compounds and makes greater use of the two-dimensional separation space. This column configuration improves resolution of a greater number of components within one analysis and offers new possibilities for crude oil fingerprinting.

We have demonstrated for the first time the application of a small angle neutron scattering (SANS) technique for the precise determination of the onset of hydrocarbon transport (primary migration) in shaly source rocks. We used a sequence of rocks pyrolysed in the laboratory under nitrogen at temperatures in the range 310-370°C. These rocks contained several percent of dispersed marine Type II organic matter. Geochemical analysis indicated a peak of the hydrocarbon generation in the middle of the temperature range (at 340°C). We observed a sharp decrease of SANS intensity in a narrow maturity range within the geochemically determined region of the onset of hydrocarbon generation. This decrease was a direct consequence of the SANS contrast variation caused by the invasion of the pore space by bitumen during the primary migration of hydrocarbons. A similar phenomenon was observed for a natural maturity sequence of source rocks originating from the same location.

A growing need to manage marine biodiversity sustainably at local, regional and global scales cannot be met by applying the limited existing biological data. Abiotic surrogates of biodiversity are thus increasingly valuable in filling the gaps in our knowledge of biodiversity patterns, especially identification of hotspots, habitats needed by endangered or commercially valuable species and systems or processes important to the sustained provision of ecosystem services. This review examines the use of abiotic variables as surrogates for patterns in benthic assemblages with particular regard to how variables are tied to processes affecting biodiversity and how easily those variables can be measured at scales relevant to resource management decisions.

This article focuses on the re-evaluation of the source rock potential of the basal Kockatea Shale in the offshore portion of the northern Perth Basin.

Organic geochemists are increasingly involved in multi-disciplinary collaborative studies but not often in the initial sample collection phase, so understanding the origin and source of contaminants derived from sample handling and containers is of vital importance as standard laboratory blanks cannot assess this contamination. A variety of organic contaminants was detected in different sediments collected during Geoscience Australia marine survey S282. These include fatty acid amides, chemical antioxidants such as butylated hydroxytoluene and octadecyl-3, 5-di-tert-butyl-4-hydroxyhydrocinnamate (Irganox 1076), plus the UV absorbers octabenzone and octyl methoxycinnamate. These compounds were introduced during sampling on board the research vessel or during subsequent handling. Solvent extraction of potential contamination sources identified two brands of plastic sampling bags as the main source for the fatty acid amides, butylated hydroxytoluene and Irganox 1076. Direct contact of samples with hands covered with sunscreen appears to have caused contamination by octabenzone and octyl methoxycinnamate. As the primary aim of the survey was to detect evidence for hydrocarbon seepage in the Arafura Sea, care was also taken to identify potential sources of hydrocarbons that might have been introduced during sampling and storage. Detailed examination of solvent extracts from plastic bags revealed the occurrence of several homologous series of branched alkanes with quaternary carbon atoms (BAQCs), as well as distributions of alkyl cyclohexanes and alkyl cyclopentanes with strong even over odd carbon predominance. These compounds were also found in sediment samples collected during the survey. Other potential sources of contamination used on board the ship, such as PVC core liners and lubricants, yielded hydrocarbons that could easily be mistaken for evidence of naturally occurring petroleum if care is not taken during interpretation.

The identification of suitable abiotic surrogates for biological diversity requires the collection of both physical and biological data. However, logistical constraints often preclude experimental designs that incorporate spatial and temporal replication. Given the quite limited resources normally available for surveys, the investigation of appropriate surrogates involves a trade-off between overall spatial coverage and replication. We have completed a survey in Jervis Bay in which environmental and infaunal data were collected contemporaneously in order to be combined with similar data from a previous winter survey (survey number GA309) to investigate variation across seasons. Because there will be a certain error in sampling at the exact location as the previous survey, the survey design also required that replicate samples be taken at a set number of stations in order to investigate fine-scale variability (at the scale of metres). We used grabs to collect paired geochemical and biological samples from thirty-two stations in a defined grid near Darling Rd; at eight of these stations we deployed three pairs of grabs to investigate fine-scale variability. Due to good weather and extra ship time available, we also deployed a CTD to investigate vertical temperature and salinity profiles at each station in the Darling Rd grid, as well as at stations throughout the entire bay. Samples are expected to be processed and analysed by late 2009, but preliminary results indicate that most physical variables and infaunal assemblages varied between seasons. In addition, variation among infaunal assemblages seems greater among stations (hundreds of meters) than within replicates at stations (meters).

This study undertook geochemical and isotopic analyses on a wide selection of oil stains from the Thorntonia Limestone, Arthur Creek Formation and the Arrinthrunga Formation and its lower Hagen Member in order to define geochemical inter-relationships between the oils, characterize their source facies and to determine the extent of post-emplacement alteration. Oil stains were collected from BHD-4 and -9, Elkedra-2 and -7A, Hacking-1, MacIntyre-1, M13 PD, NTGS99/1, Owen-2, Randall-1 and Ross-1 over a depth range from 91 to 1065 m and were analysed for bulk, molecular (biomarkers) and carbon isotopic compositions. Gas chromatograph of the saturated hydrocarbon fraction clearly showed biodegradation as the main alteration process in the shallow reservoirs. Unaltered oil stains show a dominance of medium weight n-alkanes with a maximum at n-C15. Biodegradation results in a progressive loss of the lighter hydrocarbons and an accompanying shift in n-alkane maximum to C27, to finally a complete loss of n-alkanes and a large unresolved complex mixture (UCM). The absence of 25-norhopanes suggests a mild level of biodegradation. The low ratio of saturated hydrocarbons/aromatic hydrocarbons (<1, down to 0.42) compared to high ratios (up to 4.35) for oils with abundant lower molecular weight n-alkanes is consistent with biodegradation. However, low ratios are also seen for otherwise pristine oils, suggesting a complex charge history of initial biodegraded and subsequent re-charge with n-alkane-laden oil. The level of biodegradation is not too severe as to overtly affect the distribution of the biomarkers C19 - C26 tricyclic terpanes, C24 tetracyclic terpane, C27 - C35 hopanes, C30 triterpane (gammacerane) and C27- C29 desmethylsteranes, enabling their use in oil-oil correlation and definition of oil populations. To clarify the inter-relationships among the Georgina Basin oil stains multivariate statistical analysis was used involving a wide range of biomarker ratios that are source-specific and environmental indicators. Resulting oil populations showed a strong correlation with their reservoir unit across the basin, suggesting juxtaposition of source and reservoir within the same stratigraphic unit. Oil-source correlation based on biomarker, bulk carbon isotopes of saturated and aromatic hydrocarbons and n-alkane-specific carbon isotopes identified Thorntonia(!), Arthur Creek(!) and Hagen(.) Petroleum Systems. The latter petroleum system is characterised by relatively high gammacerane, indicating an evaporitic depositional environment. Alternatively, an evaporatic organic facies from an Arthur Creek Formation source may have sourced the Hagen Member oil stains, considering that other oil stains reservoired within the Arrinthrunga Formation show a close affinity with oil stains from the Arthur Creek(!) Petroleum System, suggesting an inter-formational Arthur Creek-Hagen Petroleum System at Elkedra-2. An Arthur Creek-Hagen(!) petroleum system is evident at Elkedra-7A while there is a mixed Thorntonia Limestone and Arthur Creek source contribute to the oil stain at Ross-1.

No abstract available