The Exploring for the Future program Showcase 2023 was held on 15-17 August 2023. Day 3 - 17th August talks included: Geological Processes and Resources Session Large scale hydrogen storage: The role of salt caverns in Australia’s transition to net zero – Dr Andrew Feitz Basin-Hosted Base Metal Deposits – Dr Evgeniy Bastrakov Upper Darling Floodplain: Groundwater dependent ecosystem assessment – Dr Sarah Buckerfield Atlas of Australian Mine Waste: Waste not, want not – Jane Thorne Resource Potential Theme National-scale mineral potential assessments: supporting mineral exploration in the transition to net zero – Dr Arianne Ford Australia’s Onshore Basin Inventories: Energy – Tehani Palu Prioritising regional groundwater assessments using the national hydrogeological inventory – Dr Steven Lewis Assessing the energy resources potential in underexplored regions – Dr Barry Bradshaw You can access the recording of the talks from YouTube here: <a href="https://youtu.be/pc0a7ArOtN4">2023 Showcase Day 3 - Part 1</a> <a href="https://youtu.be/vpjoVYIjteA">2023 Showcase Day 3 - Part 2</a>

Underground hydrogen storage (UHS) in halite caverns will become an essential technology to supplement energy supply networks. This study examines the feasibility of UHS in the offshore Polda Basin by integrating previous seismic interpretation, well data and regional geology information. The Mercury structure in the central – east Polda Basin has extensive halite accumulations (both vertically and laterally) and has been identified as an area with high UHS potential. The net halite thickness is more than 1000 m, while the total potential area is about 217 km². Well data from the Mercury 1 well show a low thermal gradient (1.7–2.1 °C/100m) and overburden pressure gradient of approximately 18 ppg, providing effective gas operation pressure for UHS. To illustrate the feasibility of UHS, a conceptual design of a halite cavern is provided for a depth range of 1650–2000 m. Caverns with diameters of 60 m and 100 m are estimated to have storage capacities of approximately 240 GWh and 665 GWh, respectively. Multiple halite caverns could be constructed within the extensive Mercury halite accumulation. Further investigation into the potential for salt accumulations in the onshore Polda Basin is recommended. <b>Citation: </b>Feitz A. J., Wang L., Rees S. & Carr L., 2022. Feasibility of underground hydrogen storage in a salt cavern in the offshore Polda Basin. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, https://dx.doi.org/10.26186/146501

The Exploring for the Future program Showcase 2023 was held on 15-17 August 2023. Day 1 - 15th August talks included: Resourcing net zero – Dr Andrew Heap Our Geoscience Journey – Dr Karol Czarnota You can access the recording of the talks from YouTube here: <a href="https://youtu.be/uWMZBg4IK3g">2023 Showcase Day 1</a>

The Adavale Basin, home to the Boree Salt, is a potential option for underground hydrogen storage (UHS) due to its close proximity to industrial infrastructure, existing pipelines and significant renewable energy sources. This study builds upon a previously constructed 3D geological model to examine the feasibility of developing salt caverns for UHS. The study integrates well data and regional geology, as well as analyses on mineralogy, geochemistry and petrophysical and geomechanical properties of the Boree Salt. Results highlight that the Boree Salt is predominantly halite (96.5%), with a net salt thickness of ~540 m encountered in Bury 1, and has excellent seal properties. Furthermore, the formation overburden pressure gradient implies favourable conditions for storing hydrogen in the Boree Salt. To illustrate the feasibility of UHS, a conceptual design of a cylindrical salt cavern at depth intervals of 1600 – 1950 m is presented. A single 60 m diameter cavern could provide up to 203 GWh (or ~ 6000 tonnes) of hydrogen energy storage. Further investigation to improve our understanding on the Boree Salt extent is recommended.

Natural hydrogen is receiving increasing interest as a potential low-carbon fuel. There are various mechanisms for natural hydrogen generation but the reduction of water during oxidation of iron in minerals is recognised to be the major source of naturally generated H2. While the overall reaction is well known, the identity and nature of the key rate limiting steps is less understood. This study investigates the dominant reaction pathways through the use of kinetic modelling. The modelling results suggest there are a number of conditions required for effective H2 production from iron minerals. These include the presence of ultramafic minerals that are particularly high in Fe rather than Mg content, pH in the range of 8 to 10, solution temperatures in the 200 to 300oC range, and strongly reducing conditions. High reaction surface area is key and this could be achieved by the presence of finely deposited material and/or assemblages of high porosity or with mineral assemblages with surface sites that are accessible to water. Finally, conditions favouring the co-deposition of Ni together with FeO/Fe(OH)2-containing minerals such as brucite (and, possibly, magnetite) could enhance H2 generation

Internationally, the number of carbon capture and storage (CCS) projects has been increasing with more than 61 new CCS facilities added to operations around the globe in 2022, including six projects in Australia (GCCSI, 2022). The extraction of reservoir fluid will be an essential component of the CCS workflow for some of projects in order to manage reservoir pressure variations and optimise the subsurface storage space. While we refer to reservoir fluid as brine throughout this paper for simplicity, reservoir fluids can range from brackish to more saline (briny) water. Brine management requires early planning, as it has implications for the project design and cost, and can even unlock new geological storage space in optimal locations. Beneficial use and disposal options for brine produced as a result of carbon dioxide (CO2) storage has been considered at a regional or national scale around the world, but not yet in Australia. For example, it may be possible to harvest energy, water, and mineral resources from extracted brine. Here, we consider how experiences in brine management across other Australian industries can be transferred to domestic CCS projects.

The integrated use of seismic and gravity data can help to assess the potential for underground hydrogen storage in salt caverns in the offshore Polda Basin, South Australia. Geophysical integration software was trialled to perform simultaneous modelling of seismic amplitudes and traveltime information, gravity, and gravity gradients within a 2.5D cross-section. The models were calibrated to existing gravity data, seismic and well logs improving mapping of the salt thickness and depth away from well control. Models included known salt deposits in the offshore parts of the basin and assessed the feasibility for detection of potential salt deposits in the onshore basin, where there is limited well and seismic coverage. The modelling confirms that candidate salt cavern storage sites with salt thicknesses greater than 400-500 m should be detectable on low altitude airborne gravity surveys. Identification of lower cost onshore storage sites will require careful calibration of gravity models against measured data, rather than relying on the observation of rounded anomalies associated with salt diapirism. Ranking of the most prospective storage sites could be optimized after the acquisition of more detailed gravity and gradiometry data, preferably accompanied by seismic reprocessing or new seismic data acquisition.

<div>Geoscience Australia’s Onshore Basin Inventories program provides a whole-of-basin inventory of geology, energy systems, exploration status and data coverage of onshore Australian basins. Volume 1 of the inventory covers the McArthur, South Nicholson, Georgina, Wiso, Amadeus, Warburton, Cooper and Galilee basins and Volume 2 expands this list to include the Officer, Perth and onshore Canning basins. These reports provide a single point of reference and create a standardised national inventory of onshore basins. In addition to summarising the current state of knowledge within each basin, the onshore basin inventory identifies critical science questions and key exploration uncertainties that may help inform future work program planning and aid in decision making for both government and industry organisations. Under Geoscience Australia’s Exploring for the Future (EFTF) program, six new onshore basin inventory reports will be delivered. </div><div>&nbsp;</div><div>These reports will be supported by selected value-add products that aim to address identified data gaps and evolve regional understanding of basin evolution and prospectivity. Petroleum system modelling is being undertaken in selected basins to highlight the hydrocarbon potential in underexplored provinces, and seismic reprocessing and regional geochemical studies are underway to increase the impact of existing datasets. The inventories are supported by the ongoing development of the nationwide source rock and fluids atlas, accessed through Geoscience Australia’s Exploring for the Future Data Discovery Portal, which continues to improve the veracity of petroleum system modelling in Australian onshore basins.</div><div>&nbsp;</div><div>In summarising avenues for further work, the Onshore Basin Inventories program has provided scientific and strategic direction for pre-competitive data acquisition under the EFTF work program. Here, we provide an overview of the current status of the Onshore Basin Inventories, with emphasis on its utility in shaping EFTF data acquisition and analysis, as well as new gap-filling data acquisition</div> This Abstract was submitted/presented at the 2023 Australasian Exploration Geoscience Conference (AEGC) 13-18 March (https://2023.aegc.com.au/)

<div>The Adavale Basin is located approximately 850 km west-northwest of Brisbane and southwest of Longreach in south-central Queensland. The basin system covers approximately 100,000 km2 and represents an Early to Late Devonian (Pragian to Famennian) depositional episode, which was terminated in the Famennian by widespread contractional deformation, regional uplift and erosion. </div><div>Burial and thermal history models were constructed for nine wells using existing open file data to assess the lateral variation in maturity and temperature for potential source rocks in the Adavale Basin, and to provide an estimate of the hydrocarbon generation potential in the region.</div>

The discovery of strategically located salt structures, which meet the requirements for geological storage of hydrogen, is crucial to meeting Australia’s ambitions to become a major hydrogen producer, user and exporter. The use of the AusAEM airborne electromagnetic (AEM) survey’s conductivity sections, integrated with multidisciplinary geoscientific datasets, provides an excellent tool for investigating the near-surface effects of salt-related structures, and contributes to assessment of their potential for underground geological hydrogen storage. Currently known salt in the Canning Basin includes the Mallowa and Minjoo salt units. The Mallowa Salt is 600-800 m thick over an area of 150 × 200 km, where it lies within the depth range prospective for hydrogen storage (500-1800 m below surface), whereas the underlying Minjoo Salt is generally less than 100 m thick within its much smaller prospective depth zone. The modelled AEM sections penetrate to ~500 m from the surface, however, the salt rarely reaches this level. We therefore investigate the shallow stratigraphy of the AEM sections for evidence of the presence of underlying salt or for the influence of salt movement evident by disruption of near-surface electrically conductive horizons. These horizons occur in several stratigraphic units, mainly of Carboniferous to Cretaceous age. Only a few examples of localised folding/faulting have been noted in the shallow conductive stratigraphy that have potentially formed above isolated salt domes. Distinct zones of disruption within the shallow conductive stratigraphy generally occur along the margins of the present-day salt depocentre, resulting from dissolution and movement of salt during several stages. This study demonstrates the potential AEM has to assist in mapping salt-related structures, with implications for geological storage of hydrogen. In addition, this study produces a regional near-surface multilayered chronostratigraphic interpretation, which contributes to constructing a 3D national geological architecture, in support of environmental management, hazard mapping and resource exploration. <b>Citation: </b>Connors K. A., Wong S. C. T., Vilhena J. F. M., Rees S. W. & Feitz A. J., 2022. Canning Basin AusAEM interpretation: multilayered chronostratigraphic mapping and investigating hydrogen storage potential. In: Czarnota, K (ed.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, https://dx.doi.org/10.26186/146376