The hydrocarbon generative potential and the thermal maturity of source rocks in the offshore northern Perth Basin was reassessed based on existing and new geochemical data to get a better understanding of the basin's prospectivity. The study establishes for the first time that the main source of onshore accumulations, the Late Permian-Early Triassic Hovea Member, is well developed offshore and contains organic-rich sediments of oil-prone character. This finding shatters the long-held view that the Hovea Member was either absent or of poor quality offshore and provides a new perspective on the basin's prospectivity. The source potential of the Hovea Member varies spatially with best source rocks observed in the Beagle Ridge and Central Abrolhos Sub-basin. The Late Permian Irwin River Sequence and several Jurassic Sequences are also identified as prime potential source rocks offshore, mostly for their gas-generative potential. Oil-generative potential was identified in the Middle to Late Jurassic Yarragadee Sequence and possibly in the Middle Jurassic Cadda Sequence.

<p>The Roebuck Basin on Australia’s offshore north-western margin is the focus of a regional hydrocarbon prospectivity assessment being undertaken by the North West Margin Energy Studies (NWMES) section. This offshore program is designed to produce pre-competitive information to assist with the evaluation of the hydrocarbon resource potential of the central North West Shelf and facilitate exploration investment in Australia. <p>The recent oil and gas discoveries at Phoenix South 1 (2014), Roc 1 (2015-16), Roc 2 (2016), Phoenix South 2 (2016), Phoenix South 3 (2018) and Dorado 1 (2018) wells in the Bedout Sub-basin demonstrate the presence of a petroleum system in Lower Triassic strata. The current study aims to better understand this new petroleum system and establish its extent. <p>As part of this program, a range of organic geochemical analyses were acquired on two crude oils from the Phoenix South 1 ST2 well with these data released in this dataset.

<p>The Roebuck Basin on Australia’s offshore north-western margin is the focus of a regional hydrocarbon prospectivity assessment being undertaken by the North West Margin Energy Studies Section (NWMES). This offshore program is designed to produce pre-competitive information to assist with the evaluation of the hydrocarbon resource potential of the central North West Shelf and attract exploration investment to Australia. <p>The recent oil and gas discoveries at Phoenix South 1 (2014), Roc 1 (2015-16), Roc 2 (2016), Phoenix South 2 (2016), Phoenix South 3 (2018) and Dorado 1 (2018) in the Bedout Sub-basin demonstrate the presence of a petroleum system in Lower Triassic strata. The current study aims to better understand this new petroleum system and establish its extent. <p>As part of this program, TOC and Rock-Eval pyrolysis analyses were undertaken by Geoscience Australia on selected rock samples from the well Roc 2 to establish their hydrocarbon-generating potential and thermal maturity.

The Roebuck Basin on Australia’s offshore north-western margin is the focus of a regional hydrocarbon prospectivity assessment being undertaken by the Offshore Energy Studies section. This offshore program is designed to produce pre-competitive information to assist with the evaluation of the hydrocarbon resource potential of the central North West Shelf and facilitate exploration investment in Australia. The recent oil and gas discoveries at Phoenix South 1 (2014), Roc 1 (2015-16), Roc 2 (2016), Phoenix South 2 (2016), Phoenix South 3 (2018), Dorado 1 (2018), Dorado 2 (2019) and Dorado 3 (2019) wells in the Bedout Sub-basin demonstrate the presence of a petroleum system in Lower Triassic strata (Thompson, 2020; Thompson et al., 2015 and 2018). The current study aims to better understand this new petroleum system and establish its extent. As part of this program, a range of organic geochemical analyses were acquired on source rocks from the Roc 2 well with these data released in this report.

A regional hydrocarbon prospectivity study was undertaken in the onshore Canning Basin in Western Australia as part of the Exploring for the Future (EFTF) program, an Australian Government initiative dedicated to driving investment in resource exploration. As part of this program, significant work has been carried out to deliver new pre-competitive data including new seismic acquisition, drilling of a stratigraphic well, and the geochemical analysis of geological samples recovered from exploration wells. A regional, 872 km long 2D seismic line (18GA-KB1) acquired in 2018 by Geoscience Australia (GA) and the Geological Survey of Western Australia (GSWA), images the Kidson Sub-basin of the Canning Basin. In order to provide a test of geological interpretations made from the Kidson seismic survey, a deep stratigraphic well, Barnicarndy 1, was drilled in 2019 in a partnership between Geoscience Australia (GA) and the Geological Survey of Western Australia (GSWA) in the Barnicarndy Graben, 67 km west of Telfer, in the southwest Canning Basin. Drilling recovered about 2100 m of continuous core from 580 mRT to the driller’s total depth (TD) of 2680.53 mRT. An extensive analytical program was carried out to characterise the lithology, age and depositional environment of these sediments. This data release presents organic geochemical analyses undertaken on rock extracts obtained from cores selected from the Barnicarndy 1 well. The molecular and stable isotope data carbon and hydrogen will be used to understand the type of organic matter being preserved, the depositional facies and thermal maturity of the Lower Ordovician sedimentary rocks penetrated in this well. This information provides complementary information to other datasets including organic petrological and palynological studies.

In 2014, the surprise discovery of oil in the well Phoenix South 1 on Australia’s North West Shelf (NWS) heralded the Bedout Sub-basin as Australia’s new petroleum province. The well had initially targeted gas in Triassic reservoirs of the Keraudren Formation and Locker Shale but unexpectedly encountered oil instead. This has fuelled a revival of exploration in the area with subsequent wells Roc 1, Roc 2, Phoenix South 2 and Dorado 1 all successful in penetrating hydrocarbon columns. The Phoenix South 1 accumulation is significant as it demonstrates the occurrence of an effective oil-prone source rock within the Lower–Middle Triassic for the first time on the NWS. It also raised the possibility that a source rock analogue to the Hovea Member of the Lopingian–Lower Triassic Kockatea Shale, a well-established source of oil and gas in the northern Perth Basin, may also be effective on the NWS. In order to understand the origin of the Phoenix South 1 accumulation, its geochemical composition was compared to those of Triassic-sourced oils from the Perth Basin and petroleum fluids from the neighbouring Browse Basin, and Beagle and Dampier sub-basins.

Program and Abstracts from the conference

This database contains geochemical data for samples analysed both for inorganic and organic geochemistry. Analytical data are sourced from Geoscience Australia's Inorganic Geochemistry Database (OZCHEM) and Organic Geochemistry Database (ORGCHEM), respectively. The data are joined on a unique sample number. Inorganic geochemical data cover the majority of the periodic table, with metadata on analytical methods and detection limits. Organic geochemical data include results of pyrolysis, derivative calculated values, and, where available, isotopic composition of carbonates (D13C) and isotopic composition of rock nitrogen (D15N). Further, there are provisions for delivery of isotopic data for kerogen (H, C, N) and oxygen (O) for carbonates. Where available, sample descriptions include stratigraphic unit names and ages, and lithology. Location information includes coordinates of the sampled feature (eg, borehole), coordinates of the sample and sample depth. Interpretation of the combined inorganic and organic geochemistry for organic-rich shales will facilitate comprehensive characterisation of hydrocarbons source rocks and mineral commodities source and trap environments. All are achieved within the frameworks of petroleum and mineral systems analysis. The initial data delivered by this service include 1785 samples from 35 boreholes from 14 geological provinces, including recently released data for 442 samples from the South Nicholson National Drilling Initiative Carrara 1 stratigraphic drill hole (Butcher et al., 2021; Carson et al., 2021). Many sampled boreholes are located within the polygon of the Exploring for the Future Barkly-Isa-Georgetown project. This dataset will be updated periodically as more data become available.

Geoscience Australia and its predecessors have analysed hydrochemistry of water sampled from boreholes (both pore water and groundwater), surface features, and rainwater. Sampling was undertaken during drilling or monitoring projects, and this dataset represents a significant subset of stored analyses. Water chemistry including isotopic data is essential to better understand groundwater origins, ages and dynamics, processes such as recharge and inter-aquifer connectivity and for informing conceptual and numerical groundwater models. This GA dataset underpins a nationally consistent data delivery tool and web-based mapping to visualise, analyse and download groundwater chemistry and environmental isotope data. This dataset is a spatially-enabled groundwater hydrochemistry database based on hydrochemistry data from projects completed in Geoscience Australia. The database includes information on physical-chemical parameters (EC, pH, redox potential, dissolved oxygen), major and minor ions, trace elements, nutrients, pesticides, isotopes and organic chemicals. Basic calculations for piper plots colours are derived from Peeters, 2013 - A Background Color Scheme for Piper Plots to Spatially Visualize Hydrochemical Patterns - Groundwater, Volume 52(1) <https://doi.org/10.1111/gwat.12118>. Upon loading the data to the database, all hydrochemistry data are assessed for reliability using Quality Assurance/Quality Control procedures and all datasets were standardised. This data is made accessible with open geospatial consortium (OGC) web services and is discoverable via the Geoscience Australia Portal (<a href="https://portal.ga.gov.au/">https://portal.ga.gov.au/</a>). This dataset is published with the permission of the CEO, Geoscience Australia.

The Roebuck Basin on Australia’s offshore north-western margin is the focus of a regional hydrocarbon prospectivity assessment being undertaken by the Offshore Energy Systems Section. This offshore program is designed to produce pre-competitive information to assist with the evaluation of the hydrocarbon resource potential of the central North West Shelf and attract exploration investment to Australia. The recent oil and gas discoveries at Phoenix South 1 (2014), Roc 1 (2015-16), Roc 2 (2016), Phoenix South 2 (2016), Phoenix South 3 (2018), Dorado 1 (2018) and Dorado 2–3 (2019) in the Bedout Sub-basin demonstrate the presence of a petroleum system in Lower Triassic strata (Grosjean et al., 2021; Rollet et al., 2019). As part of this program, a range of organic geochemical analyses were acquired on petroleum fluids from the Dorado 1 and Roc 2 wells with these data released in this report.