This appendix provides a regional geological analysis and conceptualisation of the Cooper GBA region. It delivers information critical for the shale, tight and deep coal gas prospectivity assessment outlined in the petroleum prospectivity technical appendix (Lech et al., 2019), and for input into assessing the potential impacts on groundwater and surface water assets detailed in the hydrogeology (Evans et al., 2019) and hydraulic fracturing (Kear et al., 2019) technical appendices. The Cooper Basin is a Carboniferous to Triassic intracratonic basin in north-eastern South Australia and south-western Queensland. It has a total area of approximately 127,000 km2, of which about three quarters lies within Queensland and the remainder lies within South Australia. Section 2 provides a comprehensive inventory and review of existing open data and information for the Cooper GBA region relevant for the prospectivity assessment (see the petroleum prospectivity technical appendix (Lech et al., 2019)) and hydrogeological characterisation (see the hydrogeology technical appendix (Evans et al., 2019)). It includes discussion of the datasets incorporated in the data inventory. A broad range of datasets were utilised to develop a three-dimensional conceptualisation of the geological basin. These include: geographic and cultural datasets which details the location and nature of administrative boundaries, infrastructure and topography; and geological datasets such as surface geology and geological provinces, well and seismic data and geophysical data. A range of public domain publications, reports and data packages for the Cooper Basin are also utilised to characterise the basin architecture and evolution. Section 3 reviews the Cooper Basin’s geological setting and the GBA region’s basin evolution from pre-Permian basement to creation of the Cooper, Eromanga and Lake Eyre basins. Section 4 reviews the main structural elements of the Cooper Basin and how these relate to the basin’s stratigraphy and evolution. The base of the Cooper Basin succession sits at depths of up to 4500 m, and reaches thicknesses in excess of 2400 m. The Cooper Basin is divided into north-eastern and south-western areas, which show different structural and sedimentary histories, and are separated by a series of north-west–south-east trending ridges. In the south-west the Cooper Basin unconformably overlies lower Paleozoic sediments of the Warburton Basin, and includes three major troughs (Patchawarra, Nappamerri and Tenappera troughs) separated by ridges (the Gidgealpa–Merrimelia–Innamincka and Murteree ridges). The depocentres include a thick succession of Permian to Triassic sediments (the Gidgealpa and Nappamerri groups) deposited in fluvio-glacial to fluvio-lacustrine and deltaic environments. The north-eastern Cooper Basin overlies Devonian sediments associated with the Adavale Basin. Here the Permian succession is thinner than in the south-west, and the major depocentres, including the Windorah Trough and Ullenbury Depression, are generally less well defined. The Cooper Basin is entirely and disconformably overlain by the Jurassic–Cretaceous Eromanga Basin. In the Cooper GBA region the Eromanga Basin includes two major depocentres, the Central Eromanga Depocentre and the Poolowanna Trough, and exceeds thicknesses of 2500 m. Deposition within the Eromanga Basin was relatively continuous and widespread and was controlled by subsidence rates and plate tectonic events along the eastern margins of the Australian Plate. The Eromanga Basin is comprised of a succession of terrestrial and marine origin. It includes a basal succession of terrestrial sedimentary rocks, followed by a middle marine succession, then finally an upper terrestrial succession. The Lake Eyre Basin is a Cenozoic sedimentary succession overlying the Eromanga Basin, covering parts of northern and eastern South Australia, south-eastern Northern Territory, western Queensland and north-western New South Wales. The Lake Eyre Basin is subdivided into sub-basins, with the northern part of the Callabonna Sub-basin overlying the Cooper Basin. Here the basin is up to 300 m thick and contains sediments deposited from the Paleocene through to the Quaternary. Deposition within the Lake Eyre Basin is recognised to have occurred in three phases, punctuated by periods of tectonic activity and deep weathering. This technical appendix provides the conceptual framework to better understand the potential connectivity between the Cooper Basin and overlying aquifers of the Great Artesian Basin and to help understand potential impacts of shale, tight and deep coal gas development on water and water-dependent assets.

Across Australia, groundwater is a vital resource that supports and strengthens communities, culture, the environment and numerous industries. Movement of groundwater is complicated, taking place horizontally, vertically and across different timescales from weeks to millions of years. It is affected by changes in climate, human use and geological complexities such as the type, geometry and distribution of rocks. Understanding how all these factors interact is known as a groundwater conceptual model and it is an important first step. This groundwater conceptualisation includes the Cooper Basin and the overlying Eromanga and Lake Eyre basins as well as surface-groundwater interactions. Figure 1 shows the locations of the cross sections used to conceptualise groundwater in the Cooper Basin region. In the Cooper Basin this includes 1 aquifer in the Lake Eyre Basin, 5 aquifers in the Eromanga Basin and 1 aquifer in the Cooper Basin (Wainman et al., 2023a, b). Additional aquifers in the Permian sequence have not been included in this assessment, as they are yet to be fully investigated (Evans et al., 2020). Confidence for each aquifer was calculated for both salinity and water levels (Gouramanis et al., 2023a, b, c). The confidence for each aquifer was added to show the overall confidence for the basin. The level of knowledge across all aquifer is moderate to low. The groundwater conceptualisations summarises the groundwater flow and potential connectivity between aquifers. Figures also show the distribution of the aquifers and aquitards, average salinity, potential aquifer yield and confidence over an area of 50 km along the cross section lines.

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 web service summarises salinity and water levels for the Cooper Basin located within the Cooper Basin region.

The potential for hydrogen production in the Cooper Basin region is assessed to provide a joint information base for hydrogen generation potential from renewable energy, groundwater, and natural gas coupled with carbon capture and storage (CCS). Hydrogen generation requires water, whether using electrolysis with renewable energy or steam methane reforming (SMR) of gas with CCS. The data package includes the regional renewable energy capacity factor, aquifers and their properties (potential yield, salinity, and reserves or storativity), and geological storage potential of carbon dioxide (CO2). This data guide gives examples of how the compiled data can be used. The renewable hydrogen potential is assessed based on renewable energy capacity factor and groundwater information (potential yield, salinity, and reserves or storativity). Three aquifers from overlying basins (Eromanga and Lake Eyre basins) are included in the assessment. The Cooper Basin region has high renewable hydrogen potential. The presence of good aquifer throughout the basin combined with high renewable energy capacity factor resulted in significant areas with high hydrogen potential. The Cooper Basin has significant hydrocarbon resources, primarily for gas (Geoscience Australia, 2022). Although most known hydrocarbon resources have depleted since production began in the 1960s (Smith et al., 2015), a large amount of gas remains, including conventional gas (1,058 PJ reserves and 1,598 PJ resources) and unconventional basin-centred gas (2,265 PJ resources). An assessment in the overlying Eromanga Basin suggests that most areas over the Cooper Basin are prospective for potential CO2 geological storage (Bradshaw et al., 2023). Further work on identifying detailed gas potential is needed to assess hydrogen generation potential from SMR coupled with CCS.

The potential for hydrogen production in the Cooper Basin region is assessed to provide a joint information base for hydrogen generation potential from renewable energy, groundwater, and natural gas coupled with carbon capture and storage (CCS). This web service summarises hydrogen potential in the Cooper Basin region.

Publicly available geological data in the Cooper Basin region are compiled to produce statements of existing knowledge for natural hydrogen, hydrogen storage, coal and mineral occurrences. This web service summarises mineral potential in the Cooper Basin region.

Publicly available data was compiled to provide a common information base for resource development, and environmental and regulatory decisions in the Cooper Basin. This web service summarises the geological storage of carbon dioxide prospectivity of the Cooper Basin.

Publicly available data was compiled to provide a common information base for resource development, and environmental and regulatory decisions in the Cooper Basin. This web service summarises the geological storage of carbon dioxide prospectivity of the Cooper Basin.

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 web service summarises salinity and water levels for the Cooper Basin located within the Cooper Basin region.

Statements of existing knowledge are compiled for known mineral, coal, hydrocarbon and carbon capture and storage (CCS) resources and reserves in the Cooper Basin. This data guide illustrates the current understanding of the distribution of these key resource types within the Cooper Basin region based on trusted information sources. It provides important contextual information on the Cooper Basin and where additional details on discovered resources can be found. To date, mineral or coal deposits have not been found in the Cooper Basin, due to its depth. There are significant hydrocarbon resources found in the basin, including conventional and unconventional hydrocarbons. The Cooper Basin has been a major producer of oil and gas since the 1960s (Smith, Cassel and Evans, 2015). It is one of the largest sources of onshore hydrocarbon production in Australia. Some of the largest unconventional gas resources are contained in the basin. This is mostly basin-centred gas. The geology in the Cooper Basin is considered suitable for use in Carbon Capture and Storage (CCS) projects. The Cooper Basin and overlying Eromanga Basin contain 2 CCS projects that are currently being developed.