Natural or native molecular hydrogen (H2) can be a major component in natural gas, and yet its role in the global energy sector’s usage as a clean energy carrier is not normally considered. Here, we update the scarce reporting of hydrogen in Australian natural gas with new compositional and isotopic analyses of H2 undertaken at Geoscience Australia. The dataset involves ~1000 natural gas samples from 470 wells in both sedimentary and non-sedimentary basins with reservoir rock age ranging from the Neoarchean to Cenozoic. Pathways to H2 formation can involve either organic matter intermediates and its association with biogenic natural gas or chemical synthesis and its presence in abiogenic natural gas. The latter reaction pathway generally leads to H2-rich (>10 mol% H2) gas in non-sedimentary rocks. Abiogenic H2 petroleum systems are described within concepts of source-migration-reservoir-seal but exploration approaches are different to biogenic natural gas. Rates of abiogenic H2 generation are governed by the availability of specific rock types and different mineral catalysts, and through chemical reactions and radiolysis of accessible water. Hydrogen can be differently trapped compared to hydrocarbon gases; for example, pore space can be created in fractured basement during abiogenic reactions, and clay minerals and evaporites can act as effective adsorbents, traps and seals. Underground storage of H2 within evaporites (specifically halite) and in depleted petroleum reservoirs will also have a role to play in the commercial exploitation of H2. Estimated H2 production rates from water radiolysis in mafic-ultramafic and granitic rocks and serpentinisation of ultramafic-mafic rocks gives a H2 inferred resource potential between ~1.6 to ~58 MMm3 y-1 for onshore Australia down to a depth of 1 km. The prediction and subsequent identification of subsurface H2 that can be exploited remains enigmatic and awaits robust exploration guidelines and targeted drilling for proof of concept. Appeared in The APPEA Journal 61(1) 163-191, 2 July 2021

<div><strong>Output type: </strong>Exploring for the Future Extended Abstract <strong> </strong></div><div><br></div><div><strong>Short abstract: </strong>There is an increased international focus on achieving high environmental, socio-economic, and governance (ESG) outcomes within mineral supply chains, in addition to delivering positive economic results. Mineral exploration and development projects must balance these disparate objectives to the satisfaction of separate stakeholders. However, the challenge of reconciling distinct preferences can obscure viable outcomes and confound project selection, particularly in the early stages of project development. Here, we discuss how such investment decisions can be treated as multicriteria optimization problems. In appraising the pre-competitive potential for nickel sulphide developments, we show how this approach can be used to effectively evaluate competing objectives and to locate regions that perform best under a range of different metrics. We outline a mapping framework that identifies Australian regions that optimally balance geological potential, economic value, and environmental impact. Our workflow creates a new capability within Australia to incorporate high-level, holistic information into the earliest stages of exploration. While this abstract focuses on mineral exploration, the modelling could be extended to other Australian resource development applications. Importantly, our results further underscore the need to compile baseline ESG datasets across Australia to help drive sustainable exploration decisions.</div><div><br></div><div><strong>Citation:</strong> Walsh S.D.C., Haynes M.W. &amp; Wang C., 2024. Multicriteria resource potential mapping: balancing geological, economic &amp; environmental factors. In: Czarnota, K. (ed.) Exploring for the Future: Extended Abstracts. Geoscience Australia, Canberra. https://doi.org/10.26186/149250</div>

To help the management and exploration at depth of increasing demand for mineral, energy and water resources, integration of new data acquired in frontier areas in a common 3D sub-surface geological model is critical. The Exploring for the Future Program has facilitated the acquisition of major datasets in northern Australia, where rocks are mostly undercover and the basin evolution and resource potential is not well understood. Here we present a case study in the South-Nicholson Basin, located in a vast, poorly exposed area between two highly prospective Paleo- to Mesoproterozoic provinces, the Mt Isa Province and the McArthur Basin. Both regions host major base metal mineral deposits, and contain units prospective for hydrocarbons. In this study we integrate new large-scale data, which include ~1 900 km of deep seismic reflection data and 60 000 line kilometers of AusAEM1 airborne electromagnetic survey, with legacy information and new tools, to help build a semi-continental geological framework, as input to national coverage databases and inform decision-making for mining and petroleum exploration. This study provides a 3D chronostratigraphic cover model down to the Paleoproterozoic basement. We mapped the depth to the base of geological eras, as well as deeper pre-Neoproterozoic Superbasin sequence boundaries to refine the cover model. The depth estimates are based on the interpretation, compilation and integration of boreholes, solid geology, reflection seismic, airborne electromagnetic data and depth to magnetic source estimates. These depth estimates are consistently stored in national databases. These integrated datasets inform on the basin evolution in relation to the basement architecture and provided key outcomes: 1) expanded the size of the basin, significantly increasing the extent of regional petroleum systems in the region, 2) revealed a large concealed sedimentary sub-basin interpreted to include rocks that host the world class Mount Isa Cu-Pb-Zn deposits, 3) linked the stratigraphy with correlation of prospective stratigraphic units across the region, 4) identified major crustal boundaries and structures showing evidence for crustal-scale fluid flow and localised groundwater springs. Presented at the 2020 American Geophysical Union (AGU) Fall Meeting (Online)

<div>NDI Carrara 1 is a 1750 m stratigraphic drill hole completed in 2020 as part of the MinEx CRC National Drilling Initiative (NDI) in collaboration with Geoscience Australia under the Exploring for the Future program and the Northern Territory Geological Survey. It is the first stratigraphic test of the Carrara Sub-basin, a recently discovered depocentre in the South Nicholson region. The drill hole intersected Cambrian and Proterozoic sediments consisting of organic-rich black shales and a thick sequence of interbedded black shales and silty sandstones with hydrocarbon shows. A comprehensive analytical program carried out by Geoscience Australia on the recovered core samples from 283 m to total depth at 1751&nbsp;m provides critical data for calibration of burial and thermal history modelling.</div><div>Using data from this drilling campaign, burial and thermal history modelling was undertaken to provide an estimate of the time-temperature maxima that the sub-basin has experienced, contributing to an understanding of hydrocarbon maturity. Proxy kerogen kinetics are assessed to estimate the petroleum prospectivity of the sub-basin and attempt to understand the timing and nature of hydrocarbon generation. Combined, these newly modelled data provide insights into the resource potential of this frontier Proterozoic hydrocarbon province, delivering foundational data to support explorers across the eastern Northern Territory and northwest Queensland.</div> <b>Citation:</b> Palu Tehani J., Grosjean Emmanuelle, Wang Liuqi, Boreham Christopher J., Bailey Adam H. E. (2023) Thermal history of the Carrara Sub-basin: insights from modelling of the NDI Carrara 1 drill hole. <i>The APPEA Journal</i><b> 63</b>, S263-S268. https://doi.org/10.1071/AJ22048