Seismic reflection mapping, geochemical analyses and petroleum systems modelling have increased our understanding of the highly prospective Mesoproterozoic and Paleoproterozoic source rocks across northern Australia, expanding the repertoire of exploration targets currently being exploited in Proterozoic petroleum systems. Data collected during the Exploring for the Future program have enabled us to redefine and increase the extent of regional petroleum systems, which will encourage additional interest and exploration activity in frontier regions. Here, we present a review of the Paleoproterozoic McArthur and Mesoproterozoic Urapungan petroleum supersystems, and the most up-to-date interpretation of burial and thermal history modelling in the greater McArthur Basin (including the Beetaloo Sub-basin), South Nicholson Basin and Isa Superbasin. We also present potential direct hydrocarbon indicators imaged in the 2017 South Nicholson Deep Crustal Seismic Survey that increase the attractiveness of this frontier region for hydrocarbon exploration activities. <b>Citation:</b> MacFarlane, S.K., Jarrett, A.J.M., Hall, L.S., Edwards, D., Palu, T.J., Close, D., Troup, A. and Henson, P., 2020. A regional perspective of the Paleo- and Mesoproterozoic petroleum systems of northern Australia. In: Czarnota, K., Roach, I., Abbott, S., Haynes, M., Kositcin, N., Ray, A. and Slatter, E. (eds.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, 1–4.

Interpretation of newly acquired seismic data in the northern Houtman Sub-basin (Perth Basin) suggests the region contains potential source rocks similar to those in the producing Abrolhos Sub-basin. The regionally extensive late Permian–Early Triassic Kockatea Shale has the potential to contain the oil-prone Hovea Member source interval. Large Permian syn-rift half-graben, up to 10 km thick, are likely to contain a range of gas prone source rocks. Further potential source rocks may be found in the Jurassic-Early Cretaceous succession, including the Cattamarra Coal Measures, Cadda shales and mixed sources within the Yarragadee Formation. This study investigates the possible maturity and charge history of these different source rocks. A regional pseudo-3D petroleum systems model is constructed using new seismic interpretations. Heat flow is modelled using crustal structure and possible basement composition determined from potential field modelling, and subsidence analysis is used to investigate lithospheric extension through time. The model is calibrated using temperature and maturity data from 9 wells in the Houtman and Abrolhos sub-basins. Source rock properties are assigned based on an extensive review of TOC, Rock Eval and kinetic data for the offshore northern Perth Basin. Petroleum systems analysis results show that Permian, Triassic and Early Jurassic source rocks may have generated large cumulative volumes of hydrocarbons across the northern Houtman Sub-basin, whilst Middle Jurassic‒Cretaceous sources remain largely immature. However the timing of hydrocarbon generation and expulsion with respect to trap formation and structural reactivation is critical for the successful development and preservation of hydrocarbon accumulations.

The Cooper Basin is Australia's premier onshore hydrocarbon producing province and hosts a range of conventional and unconventional gas play types. This study investigates the petroleum generation potential of the basin's major Permian source rocks, to improve regional understanding of the basin's hydrocarbon prospectivity. Source rock distribution, thickness, present-day amount of total organic carbon (TOC), quality (Hydrogen Index) and maturity were mapped across the basin, together with original source quality maps prior to the on-set of generation. Results of the source rock property mapping and basin-specific kinetics were integrated with 1D burial and thermal history models and a 3D basin model to create a regional pseudo-3D petroleum system model for the basin. The modelling outputs quantify the spatial distribution of both the maximum possible hydrocarbon yield, as well as the oil/ gas expelled and retained, for ten Permian source rocks. Monte Carlo simulations were used to quantify the uncertainty associated with hydrocarbon yields and to highlight the sensitivity of results to each input parameter. The principal source rocks are the Permian coal and coaly shales of the Gidgealpa Group, with highest potential yields from the Patchawarra Formation coals and coaly shales. The broad extent of the Cooper Basin's Permian source kitchen and its large total generation potential (P50 scenario >2000 bboe) highlights the basin¿s significance as a world-class hydrocarbon province. The difference between the P90 (~800 bboe) and P10 (>4000 bboe) scenarios demonstrate the range of uncertainties inherent in this modelling.

The petroleum systems summary report provides a compilation of the current understanding of petroleum systems for the McArthur Basin, including the prospective Beetaloo Sub-basin. The contents of this report are also available via the Geoscience Australia Portal at https://portal.ga.gov.au/, called The Petroleum Systems Summary Assessment Tool (Edwards et al., 2020). Three summaries have been developed as part of the Exploring for the Future (EFTF) program (Czarnota et al., 2020); the McArthur Basin, the Canning Basin, and a combined summary of the South Nicholson Basin and Isa Superbasin region. The petroleum systems summary reports aim to facilitate exploration by summarising key datasets related to conventional and unconventional hydrocarbon exploration, enabling a quick, high-level assessment the hydrocarbon prospectivity of the region.

The unexpected discovery of oil in Triassic sedimentary rocks of the Phoenix South 1 well on Australia’s North West Shelf (NWS) has catalysed exploration interest in pre-Jurassic plays in the region. Subsequent neighbouring wells Roc 1–2, Phoenix South 2–3 and Dorado 1–3 drilled between 2015 and 2019 penetrated gas and/or oil columns, with the Dorado field containing one of the largest oil resources found in Australia in three decades. This study aims to understand the source of the oils and gases of the greater Phoenix area, Bedout Sub-basin using a multiparameter geochemical approach. Isotopic analyses combined with biomarker data confirm that these fluids represent a new Triassic petroleum system on the NWS unrelated to the Lower Triassic Hovea Member petroleum system of the Perth Basin. The Bedout Sub-basin fluids were generated from source rocks deposited in paralic environments with mixed type II/III kerogen, with lagoonal organofacies exhibiting excellent liquids potential. The Roc 1–2 gases and the Phoenix South 1 oil are likely sourced proximally by Lower–Middle Triassic TR10–TR15 sequences. Loss of gas within the Phoenix South 1 fluid due to potential trap breach has resulted in the formation of in-place oil. These discoveries are testament to new hydrocarbon plays within the Lower–Middle Triassic succession on the NWS.

The Browse Basin is located offshore on Australia’s North West Shelf and is a proven hydrocarbon province hosting gas with associated condensate. Oil reserves in the area are small with most in-place oil likely the result of hydrocarbon fluids experiencing pressures less than their saturation pressure resulting in dual phase fluids, coupled with secondary alteration processes and gas leakage. This study reviews the distribution, quality and maturity of source rocks and fluid characteristics in the Browse Basin. All publicly-available Total Organic Carbon (TOC) and Rock-Eval pyrolysis data were compiled and quality checked to determine multiple, viable source rock units. Jurassic and Cretaceous source rock distributions and net thickness were studied using integrated seismic and well log lithofacies mapping, combined with organic geochemistry data. Source rock transformation ratio and generation potential were investigated using a regional pseudo-3D petroleum systems model constructed from new seismic interpretations and calibrated using temperature and maturity data from 34 wells. Results show that the Jurassic Plover Formation (J10-J20 supersequences) coals and carbonaceous shales are effective, primarily gas-prone source rocks which may have some liquid potential when the generated gas migrates into shallow reservoirs at reduced pressures. Additional sources of hydrocarbons include shales in the Upper Jurassic lower Vulcan Formation (J40 supersequence), Lower Cretaceous upper Vulcan Formation (K10 supersequence) and Echuca Shoals Formation (K20-K30 supersequences). However, these are likely to have only expelled hydrocarbons locally in areas of optimal organic-richness and maturity. Key uncertainties include TOC and HI variability due to lack of well penetration in the depocentres. The molecular composition of the fluids were compiled and quality checked and used to investigate the relationship between the saturation pressure and condensate-gas ratio (CGR). By combining the bulk properties and molecular and isotopic compositions of the fluids with the geochemical compositions of the source rocks in a petroleum systems model, four Mesozoic petroleum systems have been identified and mapped to help understand the source rock potential and fluid characters for the Browse Basin.

Geoscience Australia's Australian National Hydrocarbon Geochemistry Data Collection comprises Oracle database tables from the Organic Geochemistry (ORGCHEM) schema and derivative information in the Petroleum Systems Summary database (Edwards et al., 2020, 2023; Edwards and Buckler, 2024). The ORGCHEM schema includes organic geochemistry, organic petrology and stable isotope database tables that capture the analytical results from sample-based datasets used for the discovery and evaluation of sediment-hosted resources. A focus is to capture open file data relevant to energy (i.e., petroleum and hydrogen) exploration, including source rocks, crude oils and natural gases from both onshore and offshore Australian sedimentary basins. The database tables also include complementary physical properties and complementary inorganic analyses on sedimentary rocks and hydrocarbon-based earth materials. The data are produced by a wide range of destructive analytical techniques conducted on samples submitted by industry under legislative requirements, as well as on samples collected by research projects undertaken by Geoscience Australia, other government agencies and scientific institutions. Some of these results have been generated by Geoscience Australia, whereas other data are compiled from service company reports, well completions reports, government reports, published papers and theses. The data is non-confidential and available for use by Government, the energy exploration industry, research organisations and the community. The Petroleum Systems Summary database stores the compilation of the current understanding of petroleum systems information, including the statistical evaluation of the analytical data by basin across the Australian continent. <b>Value: </b>These data in the ORGCHEM database tables comprise the raw organic geochemistry, organic petrological and stable isotopic values generated for Australian source rocks, crude oils and natural gases and is the only public comprehensive database at the national scale. The raw data are used as input values to other studies, such as basin analysis, petroleum systems evaluation and modelling, resource assessments, enhanced oil recovery projects, and national mapping projects. Derived datasets and value-add products are created based on calculated values and interpretations to provide information on the subsurface petroleum prospectivity of the Australian continent, as summarised in the Petroleum Systems Summary database. The data collection aspires to build a national scale understanding of Australia's petroleum and hydrogen resources. This data collection is useful to government for evidence-based decision making on sediment-hosted energy resources and the energy industry for de-risking both conventional and unconventional hydrocarbon exploration programs, hydrogen exploration programs, and carbon capture, utilisation and storage programs. <b>Scope: </b>The database initially comprised organic geochemical and organic petrological data on organic-rich sedimentary rocks, crude oils and natural gas samples sourced from petroleum wells drilled in the onshore and offshore Australian continent, including those held in the Australian National Offshore Wells Data Collection. Over time, other sample types (e.g., fluid inclusions, mineral veins, bitumen) from other borehole types (e.g., minerals, stratigraphic including the Integrated Ocean Drilling Program, and coal seam gas), marine dredge samples and field sites (outcrop, mines, surface seepage samples, coastal bitumen strandings) have been analysed for their molecular and stable isotopic chemical compositions and are captured in the databases. The organic geochemical database tables and derivative data compiled in the Petroleum Systems Summary database are delivered by web services and analytical tools in the <a href="https://portal.ga.gov.au/">Geoscience Australia Data Discovery Portal </a> and specifically in the <a href="https://portal.ga.gov.au/persona/sra">Source Rock and Fluid Atlas Persona</a>. These web services enable interrogation of source rock and petroleum fluids data within boreholes and from field sites and facilitate correlation of these elements of the petroleum system within and between basins. <b>Reference</b> Edwards, D.S., Buckler, T., Grosjean, E. & Boreham, C.J. 2024. Organic Geochemistry (ORGCHEM) Database. Australian Source Rock and Fluid Atlas. Geoscience Australia, Canberra. https://pid.geoscience.gov.au/dataset/ga/149422 Edwards, D., Hawkins, S., Buckler, T., Cherukoori, R., MacFarlane, S., Grosjean, E., Sedgmen, A., Turk, R. 2023. Petroleum Systems Summary database. Geoscience Australia, Canberra. https://dx.doi.org/10.26186/148979 Edwards, D.S., MacFarlane, S., Grosjean, E., Buckler, T., Boreham, C.J., Henson, P., Cherukoori, R., Tracey-Patte, T., van der Wielen, S.E., Ray, J., Raymond, O. 2020. Australian source rocks, fluids and petroleum systems – a new integrated geoscience data discovery portal for maximising data potential. Geoscience Australia, Canberra. http://dx.doi.org/10.11636/133751.

Geoscience Australia recently commenced work on a multi-year study of Australian petroleum source rocks to improve our understanding of the petroleum resource potential of Australia's sedimentary basins. The Permian source rocks of the Cooper Basin are the first to be characterised for this project. Quantifying the spatial distribution and petroleum generation potential of these source rocks is critical for understanding both the conventional and unconventional hydrocarbon prospectivity of the basin. The Cooper Basin is an upper Carboniferous-Middle Triassic intracratonic basin in northeastern South Australia and southwestern Queensland (Gravestock et al., 1998; Draper, 2002; McKellar, 2013; Carr et al., 2015; Hall et al., 2015a). The basin is Australia's premier onshore hydrocarbon producing province and is nationally significant in providing gas to the eastern Australian gas market. The basin also hosts a range of unconventional gas play types within the Permian Gidgealpa Group, including basin-centred gas and tight gas accumulations, deep dry coal gas associated with the Patchawarra and Toolachee formations, the Murteree and Roseneath shale gas plays and deep coal seam gas in the Weena Trough (e.g. Goldstein et al., 2012; Menpes et al., 2013; Greenstreet, 2015). The principal source rocks for these plays are the Permian coals and coaly shales of the Gidgealpa Group (Boreham & Hill, 1998; Deighton et al., 2003; Hall et al., 2016a). Mapping the petroleum generation potential of these source rocks is critical for understanding the hydrocarbon prospectivity of the basin contains reviews the distribution, type, quality, maturity and generation potential of the Cooper Basin source rocks. Geoscience Australia, in conjunction with the Department of State Development, South Australia and the Geological Survey of Queensland, have recently released a series of studies reviewing the distribution, type, quality, maturity and generation potential of the Cooper Basin source rocks. - A 3D basin model, characterising regional basin architecture, was constructed through the integration of existing horizons with formation tops and seismic interpretations (Hall et al., 2015a; Hall et al., 2016d). - Source rock distribution, amount and quality were reviewed through the analysis of log data and source rock geochemical data (including data acquired from new sampling), characterising source rocks across the whole basin (Hall et al., 2016a; Hall et al., 2016e). - Petroleum systems models, incorporating new Cooper Basin kinetics (Mahlstedt et al., 2015), highlight the variability in burial, thermal and hydrocarbon generation histories for each source rock across the basin (Hall et al., 2016b in prep; Hall et al., 2016f). This GIS contains all data associated with the above reports and accompanying data packages, providing important insights into the hydrocarbon prospectivity of the basin (Hall et al., 2015b; Kuske et al., 2015). The broad extent of the Cooper Basin's Permian source kitchen and its large total generation potential, highlights the basin's significance as a world class hydrocarbon province. The systematic workflow applied here demonstrates the importance of integrated geochemical and petroleum systems modelling studies as a predictive tool for understanding the petroleum resource potential of Australia's sedimentary basins.

The Cooper Basin is an upper Carboniferous to Middle Triassic intracratonic basin in northeastern South Australia and southwestern Queensland (Gravestock et al., 1998; Draper, 2002; Carr et al., 2016). The basin is Australia's premier onshore hydrocarbon producing province and is nationally significant in providing gas to the eastern Australian gas market. The basin also hosts a range of unconventional gas play types within the Permian Gidgealpa Group, including basin-centred gas and tight gas accumulations, deep dry coal gas associated with the Patchawarra and Toolachee formations, the Murteree and Roseneath shale gas plays and deep coal seam gas in the Weena Trough (e.g. Goldstein et al., 2012; Menpes et al., 2013; Greenstreet, 2015). The principal source rocks for these plays are the Permian coals and coaly shales of the Gidgealpa Group (Boreham & Hill, 1998; Deighton & Hill, 1998; Deighton et al., 2003). Hall et al. (2016a) reviews the maturity and generation potential of the Cooper Basin source rocks and is the third part of a series of reports reviewing various aspects of the hydrocarbon prospectivity of the Cooper Basin (see also Hall et al., 2015a; Hall et al., 2016a). This data pack contains the supplementary material accompanying this report. Over ninety 1D thermal and burial history models were integrated with the 3D basin model and source rock property characteristics to create a regional multi-1D petroleum systems model for the basin. The burial and thermal history of the model was calibrated using present day corrected temperatures and maturity indicators (Ro, Tmax). In addition lithologies for key wells were calibrated using velocity, density and thermal conductivity data. Thermal boundary conditions were modelled as transient heat-flow from base lithosphere. Crustal thickness and radiogenic heat production properties were used from published studies (e.g. Beardsmore, 2004; Meixner et al., 2012; Hall et al. 2015a). The 1D models are integrated with a 3D regional basin model (Hall et al., 2015a) to create a multi-1D petroleum systems model of the Cooper Basin. Parameters for source rock distribution, amount and quality were added from analysis of log data and source rock geochemical data (Hall et al., 2016a) and new Cooper Basin kinetics (Mahlstedt et al., 2015). This data pack includes the following grids for each source rock: temperature (°C), maturity (%Ro), transformation ratio (%), total hydrocarbon generation (mmboe/km2), oil expelled (mmbbl/km2), gas expelled (mmboe/km2; bcf/km2), oil retained (mmbbl/km2) and gas retailed (mmboe/km2; bcf/km2). The results quantify both the maturity and total maximum hydrocarbon yield of each source rock, providing important insights into the hydrocarbon prospectivity of the basin (Hall et al., 2015b; Kuske et al., 2015).

This petroleum systems summary report provides a compilation of the current understanding of petroleum systems for the South Nicholson Basin and Isa Superbasin region. The contents of this report are also available via the Geoscience Australia Portal at https://portal.ga.gov.au/, called The Petroleum Systems Summary Assessment Tool (Edwards et al., 2020). Three summaries have been developed as part of the Exploring for the Future (EFTF) program (Czarnota et al., 2020); the McArthur Basin, the Canning Basin, and a combined summary of the South Nicholson Basin and Isa Superbasin region. The petroleum systems summary reports aim to facilitate exploration by summarizing key datasets related to conventional and unconventional hydrocarbon exploration, enabling a quick, high-level assessment the hydrocarbon prospectivity of the region.