As part of the Offshore Energy Security Program (2007-2011), Geoscience Australia (GA) undertook an integrated regional study of the deepwater Otway and Sorell basins to improve the understanding of the geology and petroleum prospectivity of the region. Major outputs of this study include: - New interpretations of basement architecture and structural fabric resulting in the recognition of the Avoca-Sorell Fault System as a major control on sedimentary basin development, - Extension of the tectonostratigraphic framework of Krassay et. al. (2004) into the deepwater Otway and Sorell basins, leading to new insights into their structural and accommodation histories of both basins, and - Petroleum systems modelling indicating that these basins are mature for oil and gas generation.

Full paper version of the short abstract (GEOCAT# 73702) previously submitted and accepted by conference organisers

Presentation delivered on 9 March 2012 by Marita Bradshaw.

Extended abstract version of the abstract (Geocat#73747) submitted in March 2012 and accepted for an oral presentation at the symposium.

Vertical geochemical profiling of the marine Toolebuc Formation, Eromanga Basin - implications for shale gas/oil potential The regionally extensive, marine, mid-Cretaceous (Albian) Toolebuc Formation, Eromanga Basin hosts one of Australia's most prolific potential source rocks. However, its general low thermal maturity precludes pervasive petroleum generation, although regions of high heat flow and/or deeper burial may make it attractive for unconventional (shale gas and shale oil) hydrocarbon exploration. Previous studies have provided a good understanding of the geographic distribution of the marine organic matter in the Toolebuc Formation where total organic carbon (TOC) contents range to over 20% with approx. half being of labile carbon and convertible to gas and oil. This study focuses on the vertical profiling, at the decimetre to metre scale, of the organic and inorganic geochemical fingerprints within the Toolebuc Formation with a view to quantify fluctuations in the depositional environment and mode of preservation of the organic matter and how these factors influence hydrocarbon generation thresholds. The Toolebuc Formation from three wells, Julia Creek-2 and Wallimbulla-2 and -3, was sampled over an interval from 172 to 360m depth. The total core length was 27m from which 60 samples were selected. Cores from the underlying Wallumbilla Formation (11 samples over 13m) and the overlying Allaru Mudstone (3 samples) completed the sample set. Bulk geochemical analyses included %TOC, %carbonate, %total S, -15N kerogen, -13C kerogen, -13C carbonate, -18O carbonate, and major, minor and tracer elements and quantitative mineralogy. More detailed organic geochemical analyses involved molecular fossils (saturated and aromatic hydrocarbons, and metalloporphyrins), compound specific carbon isotopes of n-alkanes, pyrolysis-gas chromatography and compositional kinetics. etc.

Promotional flyer describing the GA programme in national unconventional hydrocarbon prospectivity and resource assessment commenced in 2011 by the Onshore (Unconventional) Hydrocarbons Section, Basin Resources Group, Energy Division.

A geological investigation, directed mainly towards the assessment of oil potentialities of the Basin, was commenced in 1948 by the Bureau of Mineral Resources, Geology and Geophysics when a small geological party carried out a reconnaissance of the Minilya River area. Since then up to seven geologists of the Bureau under the direction of M. A. Condon have been mapping the area in some detail each year in order to determine the stratigraphical sequence and its variations, regional structure, and the anticlinal structures and their extent. In addition to the regional mapping the two largest anticlines were mapped in detail. Geophysical work (gravity and seismic) has been carried out by the Geophysical section of the Bureau (see Record 1954/44). More recently, Seismograph Services Ltd. carried out a seismic survey for West Australian Petroleum Pty. Ltd. - mainly for the purpose of checking on the location of its first deep test, which is now being drilled on the Rough Range Anticline with some encouraging results to date. Palaeontological, petrographical and chemical examinations of specimens collected in the field are still continuing by specialists of the Bureau and outside.

<p>This data package includes raw (Level 0) and reprocessed (Level 1) HyLogging data from 25 wells in the Georgina Basin, onshore Australia. This work was commissioned by Geoscience Australia, and includes an accompanying meta-data report that documents the data processing steps undertaken and a description of the various filters (scalars) used in the processed datasets. <p>Please note: Data can be made available on request to ClientServices@ga.gov.au

Release Area W11-18 is a very large block over the offshore northern Perth Basin, covering parts of the Abrolhos, Houtman and Vlaming sub-basins and the Beagle and Turtle Dove ridges. Geoscience Australia (GA) has assessed the petroleum prospectivity of this area as part of the Australian Government's Offshore Energy Security Program. This assessment includes the first published synthesis of data from fourteen new field wildcat wells drilled in this part of the basin since the Cliff Head-1 discovery (2001), and the interpretation of new regional 2D seismic data acquired during GA survey 310 (2008-2009). A refined tectono-stratigraphic model for the offshore basin provides insights into basin evolution and prospectivity. Oil has been produced since 2006 from the Cliff Head oil field in WA-31-L, which is directly adjacent to Release Area W11-18. Three petroleum discoveries are included within the Release Area, with oil and gas in Dunsborough-1, and gas in Frankland-1 and Perseverance-1. These accumulations are reservoired in Permian sandstones and have primarily been sourced from the Hovea Member of the Kockatea Shale, which has also sourced the majority of producing oil and gas fields of the onshore Perth Basin. New seismic data show Permo-Triassic strata that are stratigraphic equivalents of the productive onshore and nearshore Perth Basin petroleum system, also occur within Permian half-graben in the outer Abrolhos and Houtman sub-basins. Source rock, oil stain and fluid inclusion sampling from this interval suggest that the proven onshore-nearshore petroleum system is also effective and widespread in the offshore. There is also evidence for an active Jurassic petroleum system within the Release Area. The Release Area offers a range of plays in a variety of water depths, predominantly less than 200 m, and is highly prospective for oil and gas.

Geoscience Australia has recently completed a marine survey in the offshore northern Perth Basin, off Western Australia (Jones et al., 2011b; Jones, 2011c, Upton and Jones, 2011). One of the principal aims of the survey was the collection of evidence for natural hydrocarbon seepage. The survey formed part of a regional reassessment of the basin's petroleum prospectivity in support of frontier exploration acreage Release Area W11-18. This reassessment was initiated under the Australian Government's Offshore Energy Security Program and formed part of Geoscience Australia's continuing efforts to identify a new offshore petroleum province. The offshore northern Perth Basin was identified as a basin with new frontier opportunities. New data demonstrated that proven onshore-nearshore petroleum system is also effective and widespread in the offshore (Jones et al., 2011a). Evidence for a Jurassic petroleum system was also demonstrated in the Release Area W11-18 (Jones et al., 2011a). The marine survey results provide additional support for the presence of an active petroleum system in the northern Perth Basin.