The Great Artesian Basin Research Priorities Workshop, organised by Geoscience Australia (GA), was held in Canberra on 27 and 28 April 2016. Workshop attendees represented a spectrum of stakeholders including government, policy, management, scientific and technical representatives interested in GAB-related water management. This workshop was aimed at identifying and documenting key science issues and strategies to fill hydrogeological knowledge gaps that will assist federal and state/territory governments in addressing groundwater management issues within the GAB, such as influencing the development of the next Strategic Management Plan for the GAB. This report summarises the findings out of the workshop.

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., 2016; 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. 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 (Hall et al., 2015a; 2016a; 2016b, 2016c; 2016d). 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., 2016a). A Geoscience Australia record 'Cooper Basin Petroleum Systems Analysis: Regional Hydrocarbon Prospectivity of the Cooper Basin, Part 3' providing full documentation of the model input data, workflow and results is currently in press. This work provides important insights into the hydrocarbon prospectivity of the basin (Hall et al., 2015b; Kuske et al., 2015). This product contains the working Cooper Basin Trinity-Genesis-KinEx petroleum systems model used to generate the results presented in these studies. This includes maps describing thickness, TOC and original HI for the following Permian source intervals: Toolachee Fm coals and coaly shales Daralingie Fm coals and coaly shales Roseneath Shale Epsilon Fm coals and coaly shales Murteree Shale Patchawarra Fm coals and coaly shales This model is designed for use as a regional scale hydrocarbon prospectivity screening tool. Model resolution is not high enough for this product to be used for sub-basin to prospect scale analysis, without further modification. However, the model provides a regional framework, into which more detailed prospect scale data may be embedded. The systematic workflow applied 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.

<b>This data package is superseded by a second iteration presenting updates on 3D geological and hydrogeological surfaces across eastern Australia that can be accessed through </b><a href="https://dx.doi.org/10.26186/148552">https://dx.doi.org/10.26186/148552</a> The Australian Government, through the National Water Infrastructure Fund – Expansion, commissioned Geoscience Australia to undertake the project ‘Assessing the Status of Groundwater in the Great Artesian Basin’ (GAB). The project commenced in July 2019 and will finish in June 2022, with an aim to develop and evaluate new tools and techniques to assess the status of GAB groundwater systems in support of responsible management of basin water resources. While our hydrogeological conceptual understanding of the GAB continues to grow, in many places we are still reliant on legacy data and knowledge from the 1970s. Additional information provided by recent studies in various parts of the GAB highlights the level of complexity and spatial variability in hydrostratigraphic units across the basin. We now recognise the need to link these regional studies to map such geological complexity in a consistent, basin-wide hydrostratigraphic framework that can support effective long-term management of GAB water resources. Geological unit markers have been compiled and geological surfaces associated with lithostratigraphic units have been correlated across the GAB to update and refine the associated hydrogeological surfaces. Recent studies in the Surat Basin in Queensland and the Eromanga Basin in South Australia are integrated with investigations from other regions within the GAB. These bodies of work present an opportunity to link regional studies and develop a revised, internally consistent geological framework to map geological complexity across the GAB. Legacy borehole data from various sources, seismic and airborne electromagnetic (AEM) data were compiled, then combined and analysed in a common 3D domain. Correlation of interpreted geological units and stratigraphic markers from these various data sets are classified using a consistent nomenclature. This nomenclature uses geological unit subdivisions applied in the Surat Cumulative Management Area (OGIA (Office of Groundwater Impact Assessment), 2019) to correlate time equivalent regional hydrogeological units. Herein we provide an update of the surface extents and thicknesses for key hydrogeological units, reconciling geology across borders and providing the basis for a consistent hydrogeological framework at a basin-wide scale. The new surfaces can be used for facilitating an integrated basin systems assessment to improve our understanding of potential impacts from exploitation of sub-surface resources (e.g., extractive industries, agriculture and injection of large volumes of CO2 into the sub-surface) in the GAB and providing a basis for more robust water balance estimates. This report is associated with a data package including (Appendix A – Supplementary material): • Nineteen geological and hydrogeological surfaces from the Base Permo-Carboniferous, Top Permian, Base Jurassic, Base Cenozoic to the surface (Table 2.1), • Twenty-one geological and hydrogeological unit thickness maps from the top crystalline basement to the surface (Figure 3.7 to Figure 3.27), • The formation picks and constraining data points (i.e., from boreholes, seismic, AEM and outcrops) compiled and used for gridding each surface (Table 3.8).

Publicly available data was compiled to provide a common information base for resource development, environmental and regulatory decisions in the Eromanga Basin region. This data guide gives an example of how these data can be used to create the components of a workflow to identify unconventional hydrocarbon resource opportunities. The data guide is designed to support the data package that provide insights on unconventional hydrocarbon resources in the Eromanga Basin. The unconventional hydrocarbon assessment for the Eromanga Basin includes shale resources (shale oil and gas) and coal seam gas for 6 of the 9 geological intervals, termed plays – these intervals have been defined by Wainman et al. (2023a, 2023b). Tight gas was not assessed due to play intervals lying above the zone of significant overpressure zone (2,800 m below ground level) in the Cooper-Eromanga region. The assessment captures data from well completion reports and government data sources to inform the components required for unconventional hydrocarbons to be present in the Eromanga Basin. The assessment captures data from the Great Artesian Basin geological and hydrogeological surfaces update (Vizy and Rollet, 2022), the Queensland Petroleum Exploration Database (QPED) from the Geological Survey of Queensland (GSQ) Open Data Portal (2020a), the Petroleum Exploration and Production System of South Australia (PEPS, 2021) and Draper 2002. These datasets were used to map out gross depositional environments and their geological properties relevant for unconventional hydrocarbon assessments. The data are compiled at a point in time to inform decisions on resource development activities. The data guide will outline the play-based workflow for assessing unconventional hydrocarbon prospectivity. Each of the elements required for a prospective unconventional hydrocarbon system is explained and mapped. These data are integrated and merged to show the relative assessment of unconventional prospectivity across the basin, at both play interval and basin scale. As an example of assessments contained within the dataset, this data guide showcases the prospectivity of shale resources in the Birkhead Play interval.

Publicly available groundwater data have been compiled to provide a common information base to inform environmental, resource development and regulatory decisions in the Adavale Basin region. This data guide gives examples of how these data can be used. The data package included with this data guide captures existing knowledge of Eromanga Basin aquifers in the Adavale Basin region and their properties, including salinity, water levels, resource size, potential aquifer yield and surface water interactions. The methods used to derive these data for all Eromanga Basin aquifers in the Adavale Basin region are outlined in the associated metadata files. These are described in groundwater conceptual models (Gouramanis et al., 2023). The Eromanga Basin overlying the Adavale Basin includes 5 broadly defined aquifer intervals: from deepest to shallowest, these are the Poolowanna, Hutton, Adori, Cadna-owie–Hooray and Winton-Mackunda aquifers. Compiled data are assigned to these intervals and used to characterise groundwater systems at the basin scale. The data are compiled for a point-in-time to inform decisions on potential resource developments in the Basin. The available historical groundwater data can be used to assess the potential effects on groundwater. The data can also be used for other purposes, such as exploring unallocated groundwater resource potential. Data to January 2022 are used for this compilation.

This report, completed as part of Geoscience Australia’s Exploring for the Future Program National Groundwater Systems (NGS) Project, presents results of the second iteration of 3D geological and hydrogeological surfaces across eastern Australian basins. The NGS project is part of the Exploring for the Future (EFTF) program—an eight-year, $225 million Australian Government funded geoscience data and precompetitive information acquisition program. The program seeks to inform decision-making by government, community, and industry on the sustainable development of Australia's mineral, energy, and groundwater resources, including those to support the effective long-term management of GAB water resources. This work builds on the first iteration completed as part of the Great Artesian Basin Groundwater project. The datasets incorporate infills of data and knowledge gaps in the Great Artesian Basin (GAB), Lake Eyre Basin (LEB), Upper Darling Floodplain (UDF) and existing data in additional basins in eastern Australia. The study area extends from the offshore Gulf of Carpentaria in the north to the offshore Bight, Otway, and Gippsland basins in the South and from the western edge of the GAB in the west to the eastern Australian coastline to the east. The revisions are an update to the surface extents and thicknesses for 18 region-wide hydrogeological units produced by Vizy & Rollet, 2022. The second iteration of the 3D model surfaces further unifies geology across borders and provides the basis for a consistent hydrogeological framework at a basin-wide, and towards a national-wide, scale. The stratigraphic nomenclature used follows geological unit subdivisions applied: (1) in the Surat Cumulative Management Area (OGIA - Office of Groundwater Impact Assessment, 2019) to correlate time equivalent regional hydrogeological units in the GAB and other Jurassic and Cretaceous time equivalent basins in the study area and (2) in the LEB to correlate Cenozoic time equivalents in the study area. Triassic to Permian and older basins distribution and thicknesses are provided without any geological and hydrogeological unit sub-division. Such work helps to (1) reconcile legacy and contemporary regional studies under a common stratigraphic framework, (2) support the effective management of groundwater resources, and (3) provide a regional geological context for integrated resource assessments. The 18 hydrogeological units were constructed using legacy borehole data, 2D seismic and airborne electromagnetic (AEM) data that were compiled for the first iteration of the geological and hydrogeological surfaces under the GAB groundwater project (Vizy & Rollet, 2022a) with the addition of: • New data collected and QC’d from boreholes (including petroleum, CSG [Coal Seam Gas], stratigraphic, mineral and water boreholes) across Australia (Vizy & Rollet, 2023a) since the first iteration, including revised stratigraphic correlations filling data and knowledge gaps in the GAB, LEB, UDF region (Norton & Rollet, 2023) with revised palynological constraints (Hannaford & Rollet 2023), • Additional AEM interpretation since the first iteration in the GAB, particularly in the northern Surat (McPherson et al., 2022b), as well as in the LEB (Evans et al., in prep), in the southern Eromanga Basin (Wong et al., 2023) and in the UDF region (McPherson et al., 2022c), and • Additional 2D seismic interpretation in the Gulf of Carpentaria (Vizy & Rollet, 2023b) and in the western and central Eromanga Basin (Szczepaniak et al., 2023). These datasets were then analysed and interpreted in a common 3D domain using a consistent chronostratigraphic framework tied to the geological timescale of 2020, as defined by Hannaford et al. (2022). Confidence maps were also produced to highlight areas that need further investigation due to data gaps, in areas where better seismic depth conversion or improved well formation picks are required. New interpretations from the second iteration of the 18 surfaces include (1) new consistent and regionally continuous surfaces of Cenozoic down to Permian and older sediments beyond the extent of the GAB across eastern Australia, (2) revised extents and thicknesses of Jurassic and Cretaceous units in the GAB, including those based on distributed thickness, (3) revised extents and thicknesses of Cenozoic LEB units constrained by the underlying GAB 3D model surfaces geometry. These data constraints were not used in the model surfaces generated for the LEB detailed inventory (Evans et al., 2023), and (4) refinements of surfaces due to additional seismic and AEM interpretation used to infill data and knowledge gaps. Significant revisions include: • The use of additional seismic data to better constrain the base of the Poolowanna-Evergreen formations and equivalents and the top of Cadna-owie Formation and equivalents in the western and central Eromanga Basin, and the extent and thicknesses of the GAB units and Cenozoic Karumba Basin in the Gulf of Carpentaria, • The use of AEM interpretations to refine the geometry of outcropping units in the northern Surat Basin and the basement surface underneath the UDF region, and • A continuous 3D geological surface of base Cenozoic sediments across eastern Australia including additional constraints for the Lake Eyre Basin (borehole stratigraphy review), Murray Basin (AEM interpretation) and Karumba Basin (seismic interpretation). These revisions to the 18 geological and hydrogeological surfaces will help improve our understanding on the 3D spatial distribution of aquifers and aquitards across eastern Australia, from the groundwater recharge areas to the deep confined aquifers. These data compilations and information brought to a common national standard help improve hydrogeological conceptualisation of groundwater systems across multiple jurisdictions to assist water managers to support responsible groundwater management and secure groundwater into the future. These 3D geological and hydrogeological modelled surfaces also provide a tool for consistent data integration from multiple datasets. These modelled surfaces bring together variable data quality and coverage from different databases across state and territory jurisdictions. Data integration at various scale is important to assess potential impact of different water users and climate change. The 3D modelled surfaces can be used as a consistent framework to map current groundwater knowledge at a national scale and help highlight critical groundwater areas for long-term monitoring of potential impacts on local communities and Groundwater Dependant Ecosystems. The distribution and confidence on data points used in the current iteration of the modelled surfaces highlight where data poor areas may need further data acquisition or additional interpretation to increase confidence in the aquifers and aquitards geometry. The second iteration of surfaces highlights where further improvements can be made, notably for areas in the offshore Gulf of Carpentaria with further seismic interpretation to better constrain the base of the Aptian marine incursion (to better constrain the shape and offshore extent of the main aquifers). Inclusion of more recent studies in the offshore southern and eastern margins of Australia will improve the resolution and confidence of the surfaces, up to the edge of the Australian continental shelf. Revision of the borehole stratigraphy will need to continue where more recent data and understanding exist to improve confidence in the aquifer and aquitard geometry and provide better constraints for AEM and seismic interpretation, such as in the onshore Carpentaria, Clarence-Moreton, Sydney, Murray-Darling basins. Similarly adding new seismic and AEM interpretation recently acquired and reprocessed, such as in the eastern Eromanga Basin over the Galilee Basin, would improve confidence in the surfaces in this area. Also, additional age constraints in formations that span large periods of time would help provide greater confidence to formation sub-divisions that are time equivalent to known geological units that correlate to major aquifers and aquitards in adjacent basins, such as within the Late Jurassic‒Early Cretaceous in the Eromanga and Carpentaria basins. Finally, incorporating major faults and structures would provide greater definition of the geological and hydrogeological surfaces to inform with greater confidence fluid flow pathways in the study area. This report is associated with a data package including (Appendix A – Supplementary material): • Nineteen geological and hydrogeological surfaces from the Base Permo-Carboniferous, Top Permian, Base Jurassic, Base Cenozoic to the surface (Table 1.1), • Twenty-one geological and hydrogeological unit thickness maps from the top crystalline basement to the surface (Figure 3.1 to Figure 3.21), • The formation picks and constraining data points (i.e., from boreholes, seismic, AEM and outcrops) compiled and used for gridding each surface (Table 2.7). Detailed explanation of methodology and processing is described in the associated report (Vizy & Rollet, 2023).

This data package, completed as part of Geoscience Australia’s National Groundwater Systems (NGS) Project, presents results of the second iteration of the 3D Great Artesian Basin (GAB) and Lake Eyre Basin (LEB) (Figure 1) geological and hydrogeological models (Vizy & Rollet, 2023) populated with volume of shale (Vshale) values calculated on 2,310 wells in the Surat, Eromanga, Carpentaria and Lake Eyre basins (Norton & Rollet, 2023). This provides a refined architecture of aquifer and aquitard geometry that can be used as a proxy for internal, lateral, and vertical, variability of rock properties within each of the 18 GAB-LEB hydrogeological units (Figure 2). These data compilations and information are brought to a common national standard to help improve hydrogeological conceptualisation of groundwater systems across multiple jurisdictions. This information will assist water managers to support responsible groundwater management and secure groundwater into the future. This 3D Vshale model of the GAB provides a common framework for further data integration with other disciplines, industry, academics and the public and helps assess the impact of water use and climate change. It aids in mapping current groundwater knowledge at a GAB-wide scale and identifying critical groundwater areas for long-term monitoring. The NGS project is part of the Exploring for the Future (EFTF) program—an eight-year, $225 million Australian Government funded geoscience data and precompetitive information acquisition program. The program seeks to inform decision-making by government, community, and industry on the sustainable development of Australia's mineral, energy, and groundwater resources, including those to support the effective long-term management of GAB water resources. This work builds on the first iteration completed as part of the Great Artesian Basin Groundwater project (Vizy & Rollet, 2022; Rollet et al., 2022), and infills previous data and knowledge gaps in the GAB and LEB with additional borehole, airborne electromagnetic and seismic interpretation. The Vshale values calculated on additional wells in the southern Surat and southern Eromanga basins and in the whole of Carpentaria and Lake Eyre basins provide higher resolution facies variability estimates from the distribution of generalised sand-shale ratio across the 18 GAB-LEB hydrogeological units. The data reveals a complex mixture of sedimentary environments in the GAB, and highlights sand body development and hydraulic characteristics within aquifers and aquitards. Understanding the regional extents of these sand-rich areas provides insights into potential preferential flow paths, within and between the GAB and LEB, and aquifer compartmentalisation. However, there are limitations that require further study, including data gaps and the need to integrate petrophysics and hydrogeological data. Incorporating major faults and other structures would also enhance our understanding of fluid flow pathways. The revised Vshale model, incorporating additional boreholes to a total of 2,310 boreholes, contributes to our understanding of groundwater flow and connectivity in the region, from the recharge beds to discharge at springs, and Groundwater Dependant Ecosystems (GDEs). It also facilitates interbasinal connectivity analysis. This 3D Vshale model offers a consistent framework for integrating data from various sources, allowing for the assessment of water use impacts and climate change at different scales. It can be used to map groundwater knowledge across the GAB and identify areas that require long-term monitoring. Additionally, the distribution of boreholes with gamma ray logs used for the Vshale work in each GAB and LEB units (Norton & Rollet, 2022; 2023) is used to highlight areas where additional data acquisition or interpretation is needed in data-poor areas within the GAB and LEB units. The second iteration of surfaces with additional Vshale calculation data points provides more confidence in the distribution of sand bodies at the whole GAB scale. The current model highlights that the main Precipice, Hutton, Adori-Springbok and Cadna-owie‒Hooray aquifers are relatively well connected within their respective extents, particularly the Precipice and Hutton Sandstone aquifers and equivalents. The Bungil Formation, the Mooga Sandstone and the Gubberamunda Sandstone are partial and regional aquifers, which are restricted to the Surat Basin. These are time equivalents to the Cadna-owie–Hooray major aquifer system that extends across the Eromanga Basin, as well as the Gilbert River Formation and Eulo Queen Group which are important aquifers onshore in the Carpentaria Basin. The current iteration of the Vshale model confirms that the Cadna-owie–Hooray and time equivalent units form a major aquifer system that spreads across the whole GAB. It consists of sand bodies within multiple channel belts that have varying degrees of connectivity' i.e. being a channelised system some of the sands will be encased within overbank deposits and isolated, while others will be stacked, cross-cutting systems that provide vertical connectivity. The channelised systemtransitions vertically and laterally into a shallow marine environment (Rollet et al., 2022). Sand-rich areas are also mapped within the main Poolowanna, Brikhead-Walloon and Westbourne interbasinal aquitards, as well as the regional Rolling Downs aquitard that may provide some potential pathways for upward leakage of groundwater to the shallow Winton-Mackunda aquifer and overlying Lake Eyre Basin. Further integration with hydrochemical data may help groundtruth some of these observations. This metadata document is associated with a data package including: • Seventeen surfaces with Vshale property (Table 1), • Seventeen surfaces with less than 40% Vshale property (Table 2), • Twenty isochore with average Vshale property (Table 3), • Twenty isochore with less than 40% Vshale property (Table 4), • Sixteen Average Vshale intersections of less than 40% Vshale property delineating potential connectivity between isochore (Table 5), • Sixteen Average Vshale intersections of less than 40% Vshale property delineating potential connectivity with isochore above and below (Table 6), • Seventeen upscaled Vshale log intersection locations (Table 7), • Six regional sections showing geology and Vshale property (Table 8), • Three datasets with location of boreholes, sections, and area of interest (Table 9).

Publicly available data was compiled to provide a common information base for resource development, and environmental and regulatory decisions in the Eromanga Basin. This data guide gives examples of how these data can be used to create the components of a workflow to identify geological storage of carbon dioxide (CO2) opportunities. The data guide is designed to support the data package that provide insights on the geological storage of CO2 in the Eromanga Basin. The geological storage of CO2 assessment for the Eromanga Basin overlying the Cooper, Adavale and Galilee basins encompasses 6 of the 9 geological intervals, termed plays – these intervals have been defined by Wainman et al. (2023a, b). The assessment captures data from the Great Artesian Basin geological and hydrogeological surfaces update (Vizy and Rollet, 2022), Queensland Petroleum Exploration Database (QPED) from the Geological Survey of Queensland (GSQ) Open Data Portal (2020a), the Petroleum Exploration and Production System of South Australia (PEPS, 2021); Bradshaw et al. (2009) and Draper (2002) along with the scientific literature to inform the 4 components required for a prospective geological storage of CO2 system. These datasets are used to map out gross depositional environments and their geological properties relevant for geological storage of CO2 assessments. From these datasets, the following properties were evaluated and mapped across the basin: injectivity, storage efficiency, containment and structural complexity. The data are compiled at a point in time to inform decisions on resource development opportunities. The data guide outlines the play-based workflow for assessing geological storage of CO2 prospectivity. Each of the elements required for a prospective geological storage of CO2 system are explained and mapped. These data were merged and spatially multiplied to show the relative assessment of geological storage of CO2 prospectivity across the basin, both at a play interval and basin scale. As an example of assessments contained within the data package, this data guide showcases the geological storage of CO2 prospectivity of the Namur-Murta Play interval.

Publicly available groundwater data have been compiled to provide a common information base to inform environmental, resource development and regulatory decisions in the Cooper Basin region. This data guide gives examples of how these data can be used. The data package included with this data guide captures existing knowledge of Eromanga Basin aquifers and their properties, including salinity, water levels, resource size, potential aquifer yield and surface water interactions. The methods used to derive these data for all Eromanga Basin aquifers in the Cooper Basin region are outlined in the associated metadata files. These are described in groundwater conceptualisation models (Gouramanis et al., 2023). The Eromanga Basin overlying the Cooper Basin includes 5 broadly defined aquifer intervals: from deepest to shallowest, these are the Poolowanna, Hutton, Adori, Cadna-owie-Hooray and Winton-Mackunda aquifers. Compiled data are assigned to these intervals and used to characterise groundwater systems at the basin scale. The data were compiled for a point-in-time to inform decisions on potential resource developments in the Basin. The available historical groundwater data can be used to assess the potential effects on groundwater. The data can also be used for other purposes, such as exploring unallocated groundwater resource potential. Data to January 2022 are used for this compilation.

Publicly available groundwater data have been compiled to provide a common information base to inform environmental, resource development and regulatory decisions in the Galilee Basin region. This data guide gives examples of how these data can be used. The data package included with this data guide captures existing knowledge of Galilee Basin aquifers and their properties, including salinity, water levels, resource size, potential aquifer yield and surface water - groundwater interactions. The methods used to derive these data for all Galilee Basin aquifers in the Galilee Basin region are outlined in the associated metadata files. These are described in groundwater conceptual models (Hostetler et al., 2023). The Galilee Basin includes 3 broadly defined aquifer intervals: from deepest to shallowest, these are the Joe Joe Group, Betts Creek beds and Clematis aquifers. Compiled data have been assigned to these intervals and used to characterise groundwater systems at the basin scale. The data were compiled for a point-in-time to inform decisions on potential resource developments in the Basin. The available historical groundwater data can be used to assess the potential effects on groundwater. The data can also be used for other purposes, such as exploring unallocated groundwater resource potential. Data to January 2022 were used for this compilation.