No abstract available

No abstract available

Compelling evidence is presented for the process of lipid sulfurisation in humic coal-forming environments. The production of reduced inorganic sulfides by sulfate-reducing bacteria during early diagenetic marine transgression enabled the selective sequestration of functionalised lipids in the polar and asphaltene fractions from the Eocene, marine-influenced Heartbreak Ridge lignite deposit, southeast Western Australia. Nickel boride desulfurisation experiments conducted on these fractions released small, but significant, quantities of sulfur-bound hydrocarbons. These comprised mostly higher plant triterpanes, C29 steranes and extended 17?(H),21?(H)-hopanes, linked by one sulfur atom at, or close to, sites of oxygenation in the original natural product precursors. These sulfurised lipids mostly derive from the same carbon sources as the free hydrocarbon lipids, the exception being the sulfurised extended hopanoids, which may be partially derived from a different bacterial source compared to the free hopanoids. These results indicate that the selectivity and nature of steroid and hopanoid vulcanisation in coal-forming mires is akin to that observed in other sedimentary environments. However, the diversity of sulfurised higher plant triterpanes is greater than that typically reported in immature coals. This selective preservation mechanism explains the formation of the structurally-related biomarkers in more mature sulfur-rich humic coals.

The technique of Reaction Gas Chromatography-Mass Spectrometry (R-GCMS) has been applied to the analysis of the polar extracts from a Heartbreak Ridge lignite (Bremer Basin, Western Australia; Eocene age) and a Monterey Formation shale (Naples Beach, USA; Miocene age). A catalyst, palladium black, is packed into glass liners for split vaporising injection. The liners are then placed into the injection port to catalyse the gas phase reaction of volatile polar mixtures. Hydrogen gas is used both as the reactant for hydrogenation/hydrogenolysis, and as the carrier gas for the subsequent separation. The reaction products are mostly hydrocarbons, and are swept on to the column where they are chromatographically resolved by the non-polar stationary phase. The products are then identified by mass spectrometry. The fully active catalyst is effective in hydrogenating and isomerising alkenes as well as partially hydrogenating aromatic moieties. Desulphurisation of thiols, sulphides, and thiophenes readily occurs also. Oxygenated compounds such as primary alcohols, acids, esters and ethers undergo a decarbonylation/decarboxylation, while secondary alcohols are reduced to the parent hydrocarbon. Polar fractions react to produce compound distributions that are characteristic of the organic matter source, namely angiosperm-derived triterpenoids and bacterially-derived hopanoids. The reaction of the polar fraction from the Monterey Formation shale results in the formation of high relative amounts of pristane and phytane. A suite of steroids and triterpenoids, typical of marine organic matter, is also observed. R-GCMS provides less detailed information on the exact nature of the functionalised lipids partitioned within the polar fraction compared to more conventional wet chemical analyses. However, this technique requires only a GCMS instrument fitted with a vaporising injector, which acts as a chemical reactor at the inlet of the column. The main advantages of R-GCMS are its speed, low sample requirement, and production of easily resolved and identified products.

This paper discusses the applicability of Smalll Angle X-ray Scattering (SAXS) and Small Angle Neutron Scattering (SANS) techniques for determining the porosity, pore size distribution and internal specific surface area in coals. The method is non-invasive, fast, inexpensive and does not require complex sample preparation. It uses coal grains of about 0.7mm size mounted in standard pellets as used for petrographic studies.

This product is a Microsoft Access database which contains the raw data, calculated biomarker ratios and reporting output forms. 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 database 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 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. 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.

A laboratory study has been conducted to determine the best methods for the detection of C10 to C40 hydrocarbons at naturally occurring oil seeps in marine sediments. The results indicate that a commercially available method using hexane to extract sediments and gas chromatography to screen the resulting extract is effective at recognizing the presence of migrated hydrocarbons at concentrations between 50 to 5,000 ppm. When the oil charge is unbiodegraded the level of charge is effectively tracked by the sum of n-alkanes in the gas chromatogram. However, once the charge oil becomes biodegraded, with the loss of n-alkanes and isoprenoids, the level of charge is tracked by the quantification of the Unresolved Complex Mixture (UCM). The use of GC-MS was also found to be very effective for the recognition of petroleum related hydrocarbons and results indicate that GC-MS would be a very effective tool for screening samples at concentrations below 50 ppm oil charge.

First paragraph of abstract: The importance of organic sulphur fixation in the preservation of organic matter in humic coal-forming environments is demonstrated in this thesis. The transgression of coal depositional systems by marine waters during their deposition and early diagenesis enables the production of reduced inorganic sulphur species by sulphate-reducing bacteria. The presence of these reactive sulphur species, in combination with the altered chemical and microbial regime, influences the preservation and petroleum potential of humic coal.

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A recent Geoscience Australia sampling survey in the Bight Basin recovered hundreds of dredge samples of Early Cenomanian to Late Maastrichtian age. Given the location of these samples near the updip northern edge of the Ceduna Sub-basin, they are all immature for hydrocarbon generation with vitrinite reflectance - 0.5% RVmax, Tmax < 440oC and PI < 0.1. Excellent hydrocarbon generative potential is seen for marine, outer shelf, black shales and mudstones with TOC to 6.9% and HI up to 479 mg hydrocarbons/g TOC. These sediments are exclusively of Late Cenomanian-Early Turonian (C/T) in age. The high hydrocarbon potential of the C/T dredge samples is further supported by a dominance of the hydrogen-rich exinite maceral group (liptinite, lamalginite and telalginite macerals), where samples with the highest HI (> 200 mg hydrocarbons/g TOC) contain > 70% of the exinite maceral group. Pyrolysis-gas chromatography and pyrolysis-gas chromatography mass spectrometry of the C/T kerogens reveal moderate levels of sulphur compounds and the relative abundances of aliphatic and aromatic hydrocarbons predict the generation of a paraffinic-naphthenic-aromatic low wax oil in nature. Not enough oom for rest of Abstract