Exploring for the Future (EFTF) is an Australian Government initiative that gathers new data and information about potential mineral, energy and groundwater resources. Commencing in 2016 with a focus on northern Australia, an EFTF extension to 2024 was recently announced, with expanded coverage across mainland Australia and Tasmania. The EFTF energy component aims to improve our understanding of the petroleum potential of frontier onshore Australian basins and has acquired significant pre-competitive datasets, including the recently drilled Barnicarndy 1 deep stratigraphic well in Western Australia’s Canning Basin (in partnership with the Geological Survey of Western Australia), and NDI Carrara 1 deep stratigraphic well in the South Nicholson region of the Northern Territory (in partnership with the MinEX CRC). These are the first stratigraphic wells drilled in a petroleum basin by Geoscience Australia since the formation in 2001 from its predecessor agencies. Both wells were sited along two-dimensional, deep crustal seismic surveys acquired by Geoscience Australia as part of EFTF, and provide stratigraphic control for the imaged geology. The sedimentary fill intersected by the Barnicarndy 1 and NDI Carrara 1 wells were cored and logged with a broad suite of wireline tools, providing substantial new data in two frontier basins. These data provide insights into regional stratigraphy and local lithology. Geochronology, petrographic, organic and inorganic geochemistry, petrophysical rock properties, petroleum systems elements, palaeontological, and fluid inclusion studies have been undertaken upon which inferences on regional prospectivity can made in these data-poor regions. Moving into the next phase of EFTF, these wells provide a template for new pre-competitive data acquisition by Geoscience Australia, expanding our knowledge of frontier regions making them attractive for new investment and exploration.

NDI Carrara 1 is a deep stratigraphic well completed in 2020 as part of the MinEx CRC National Drilling Initiative (NDI), in collaboration with Geoscience Australia and the Northern Territory Geological Survey. It is the first stratigraphic test of the Carrara Sub-Basin, a newly discovered depocentre in the South Nicholson region. The well intersected Proterozoic sediments with numerous hydrocarbon shows, likely to be of particular interest due to affinities with the known Proterozoic plays of the Beetaloo Sub-basin and the Lawn Hill Platform, including two organic-rich black shales and a thick sequence of interbedded black shales and silty-sandstones. Alongside an extensive suite of wireline logs, continuous core was recovered from 283.9 m to total depth at 1750.8 m, providing high-quality data to support comprehensive analysis. Presently, this includes geochronology, geochemistry, geomechanics, and petrophysics. Rock Eval pyrolysis data demonstrates the potential for several thick black shales to be a source of hydrocarbons for conventional and unconventional plays. Integration of these data with geomechanical properties highlights potential brittle zones within the fine-grained intervals where hydraulic stimulation is likely to enhance permeability, identifying prospective Carrara Sub-basin shale gas intervals. Detailed wireline log analysis further supports a high potential for unconventional shale resources. Interpretation of the L210 and L212 seismic surveys suggests that the intersected sequences are laterally extensive and continuous throughout the Carrara Sub-basin, potentially forming a significant new hydrocarbon province and continuing the Proterozoic shale play fairway across the Northern Territory and northwest Queensland. This abstract was submitted and presented at the 2022 Australian Petroleum Production and Exploration Association (APPEA), Brisbane (https://appea.eventsair.com/appea-2022/)

Exploring for the Future (EFTF) is an Australian Government program led by Geoscience Australia, in partnership with state and Northern Territory governments. The first phase of the EFTF program (2016-2020) aimed to drive industry investment in resource exploration in frontier regions of northern Australia by providing new precompetitive data and information about their energy, mineral and groundwater resource potential (Carr et al 2018). The South Nicholson Basin and immediate surrounding region is situated between Paleo-Mesoproterozoic Mount Isa Province and McArthur Basin. Both the Mount Isa Province and McArthur Basin are well studied. By contrast, the adjacent South Nicholson region is less studied, and contains rocks that are mostly undercover, for which the basin evolution and resource potential is not well understood. To address this gap, the L210 South Nicholson Deep Crustal Seismic Survey was collected in 2017 in the region between the southern McArthur Basin to the Mount Isa western succession, crossing the South Nicholson Basin and Murphy Province, providing a fundamental data link across these regions (L210 South Nicholson Deep Crustal Seismic Reflection Survey). The primary aim of the survey was to investigate areas with a low measured gravity response in the region to determine whether they represent thick basin sequences, as is the case for the nearby prospective Beetaloo Sub-basin. The interpretation of this survey led to the discovery of a new basin, the Carrara Sub-basin, coinciding with a gravity low in the south-eastern South Nicholson Basin Region. This data set contains an exported set of XYZ points from interpreted horizons (Carr et al 2019) on the South Nicholson Seismic Survey (L210) in both two way time (TWT ms on PreSTM_17ga lines) and depth (m) re-interpreted on depth indexed PreSDM_17GA lines. The coordinate reference system for this dataset is WGS 1984 Australian Centre for Remote Sensing Lambert. Seismic reference datum is 350 m. The seismic reference datum are described in the EBCDIC headers of the SEGY files for each of the survey lines. Carr, L.K., Southby, C., Henson, P., Costello, R., Anderson, J.R., Jarrett, A.J M., Carson, C.J., Gorton, J., Hutton, L.J., Troup, A., Williams, B., Khider, K., Bailey, A. & Fomin, T. 2019. Exploring for the Future: South Nicholson Basin geological summary and seismic interpretation. Record 2019/21, Geoscience Australia, Canberra. http://dx.doi.org/10.11636/Record.2019.021 Carr, L.K., Southby, C., Henson, P., Anderson, J.R., Costelloe, R., Jarrett, A.J.M., Carson, C.J., MacFarlane, S.K., Gorton, J., Hutton, L., Troup, A, Williams, B., Khider, K., Bailey, A.H.E., Fomin, T. 2020. South Nicholson Basin seismic interpretation. Geoscience Australia, Canberra. http://dx.doi.org/10.11636/132029 L210 South Nicholson Deep Crustal Seismic Reflection Survey, NT and QLD, 2017. Geoscience Australia, Canberra. https://pid.geoscience.gov.au/dataset/ga/116881.

NDI Carrara 1 is a deep stratigraphic drill hole completed in 2020 as part of the MinEx CRC National Drilling Initiative (NDI) in collaboration with Geoscience Australia and the Northern Territory Geological Survey. It is the first test of the Carrara Sub-Basin, a depocentre newly discovered in the South Nicholson region based on interpretation from seismic surveys (L210 in 2017 and L212 in 2019) recently acquired as part of the Exploring for the Future program. The drill hole intersected approximately 1120 m of Proterozoic sedimentary rocks unconformably overlain by 630 m of Cambrian Georgina Basin carbonates. Continuous cores recovered from 283 m to a total depth of 1750 m provide samples of the highest quality for a comprehensive geochemical program designed to inform on the energy and mineral prospectivity of the Carrara Sub-basin. Total Organic Carbon (TOC) contents from Rock-Eval pyrolysis of the Cambrian and Proterozoic sections demonstrate the potential for several thick black shales as source rocks and unconventional plays. Evidence for retained hydrocarbons included bituminous oil stains in centimetre-scale vugs within the Cambrian Georgina Basin and several oil bleeds within the Proterozoic section. The latter also contains surface gas with up to 2% methane concentrations measured within carbonaceous mudstones. Geochemical analyses of hydrocarbon shows highlight the occurrence of several petroleum systems operating in this frontier region. The results at NDI Carrara 1 offer the promise of a new exciting resource province in northern Australia.

As part of Geoscience Australia’s Exploring for the Future program, this study aims to analyse the hydrocarbon prospectivity in the Carrra Sub-basin through wireline log interpretation and shale gas reservoir characterisation. NDI Carrara 1 is the first stratigraphic test of the Carrara Sub-basin, a recently uncovered depocentre located within the South Nicholson region of the eastern Northern Territory and northwestern Queensland. Four chemostratigraphic packages were defined according to the informal sub-division of stratigraphy and inorganic geochemical properties. Wireline log interpretation has been conducted to derive the clay mineral compositions, porosity, gas saturation and gas contents for the unconventional shale gas reservoirs in the Proterozoic succession in NDI Carrara 1. The predominant clay minerals include illite/muscovite, mixed-layer clay, smectite, kaolinite, and minor contents of glauconite and chlorite. The average geothermal gradient is estimated to be 35.04 °C/km with a surface temperature of 29.4 °C. The average formation pressure gradient is calculated to be < 10.7 MPa/km from mud weight records. Artificial neural network technology is used to interpret the TOC content from wireline logs for unconventional shale gas reservoirs. TOC content is positively correlated with methane and ethane concentrations in mudlog gas profiles, shale porosity, formation resistivity and gas content for NDI Carrara 1. The organic-rich shales in P2 have favourable adsorbed, free and total gas contents. The organic-rich micrites within P3 have the potential in adsorbed gas, but with very low average gas saturation (< 0.01 m3/m3). Our interpretation has identified potential shale gas reservoirs, as well as tight non-organic-rich shales and siltstones with potential as gas reservoirs. These occur throughout several of the identified chemostratigraphic packages within the Proterozoic section of NDI Carrara 1.

Stratigraphic drill hole NDI Carrara 1 was drilled as a collaboration between Geoscience Australia (GA), the Northern Territory Geological Survey (NTGS) and the Mineral Exploration Cooperative Research Centre (MinEx CRC). It reached a total depth of 1751 m in late 2020 and is the first drill hole to intersect the undifferentiated Proterozoic rocks of the Carrara Sub-Basin. It intersected approximately 630 m of Cambrian Georgina Basin sedimentary rocks overlying the ~1100 m of Proterozoic carbonates, black shales and other siliciclastics of the Carrara Sub-Basin succession. The formational assignments of the Georgina Basin succession are preliminary and were assigned in the field. The units intersected comprise the Border Waterhole Formation (~531m to ~630m), which is overlain by the Currant Bush Limestone (~249m to ~531m), which in turn is overlain by the Camooweal Dolostone (0m to ~249m). Of these, only the lower 80% of the Currant Bush Limestone and the entire Border Waterhole Formation were cored. This report presents biostratigraphic results from macrofossil examination of NDI Carrara 1 core samples within the Georgina Basin section.

<div>Geoscience Australia’s Onshore Basin Inventories project delivers a single point of reference and creates a standardised national basin inventory that provides a whole-of-basin catalogue of geology, petroleum systems, exploration status and data coverage of hydrocarbon-prone onshore Australian sedimentary basins. In addition to summarising the current state of knowledge within each basin, the onshore basin inventory reports identify critical science questions and key exploration uncertainties that may help inform future work program planning and decision making for both government and industry. 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. Under Geoscience Australia’s Exploring for the Future (EFTF) program, several new onshore basin inventory reports are being delivered. Upcoming releases include the Adavale Basin of southern Queensland, and a compilation report addressing Australia’s poorly understood Mesoproterozoic basins. These are supported by value-add products that address identified data gaps and evolve regional understanding of basin evolution and prospectivity, including petroleum systems modelling, seismic reprocessing and regional geochemical studies. The Onshore Basin Inventories project continues to provide scientific and strategic direction for pre-competitive data acquisition under the EFTF work program, guiding program planning and shaping post-acquisition analysis programs.</div>

<div>Geoscience Australia’s Exploring for the Future program provides precompetitive information to inform decision-making by government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. By gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge, we are building a national picture of Australia’s geology and resource potential. This leads to a strong economy, resilient society and sustainable environment for the benefit of all Australians. This includes supporting Australia’s transition to a low emissions economy, strong resources and agriculture sectors, and economic opportunities and social benefits for Australia’s regional and remote communities. The Exploring for the Future program, which commenced in 2016, is an eight year, $225 m investment by the Australian Government. </div><div>As part of this program, Geoscience Australia led two deep crustal reflection seismic surveys in the South Nicholson region, revealing the existence of the Carrara Sub-basin, a large sedimentary depocentre up to 8 km deep, beneath the Georgina Basin (Carr et al., 2019; 2020). The depocentre is believed to contain thick sequences of highly prospective Proterozoic rocks for base metals and unconventional hydrocarbons. To confirm geological interpretations and assess resource potential, the National Drilling Initiative, NDI Carrara 1 stratigraphic drill hole was completed in late 2020, as a collaboration between Geoscience Australia, the Northern Territory Geological Survey (NTGS) and the MinEx CRC (Geoscience Australia, 2021). NDI Carrara 1 is located on the western flank of the Carrara Sub-basin on the South Nicholson seismic line (17GA-SN1) (Figure 1.1; Figure 1.2), reaching a total depth of 1751 m, intersecting sedimentary rocks comprising ca. 630 m of Cambrian calcareous shales of the Georgina Basin and ca. 1100 m of Proterozoic carbonates and siliciclastics that include black shales of the Carrara Sub-basin.</div><div>This report presents data on selected rock samples from NDI Carrara&nbsp;1, conducted by the Mawson Analytical Spectrometry Services, University of Adelaide, under contract to Geoscience Australia. These results include bulk carbon isotope ratios (δ13C) of bitumens and isolated kerogens. In addition, a selection of 10 samples was analysed at Geoscience Australia for comparison purposes.</div><div><br></div>

The Barkly Seismic Survey data images a complete seismic profile from the newly discovered Carrara Sub-basin of the South Nicholson region (e.g. Carr et al 2019) to the eastern margins of the Beetaloo Sub-basin. The survey, comprising five lines and a total of 813 line kms, links into the recently acquired EFTF South Nicholson Seismic Survey (L210; Henson et al 2018, Carr et al 2019, 2020) and the Camooweal 2D seismic survey completed by the Geological Survey of Queensland in 2019. The survey has identified Paleoproterozoic to Mesoproterozoic successions extending from the Carrara Sub-basin to the highly prospective Beetaloo Sub-basin of the McArthur Basin. These successions are concealed by a persistent cover of up to 600 m of Paleozoic Georgina Basin sediments. The recent completion of the MinEx CRC deep (1751 m) stratigraphic drillhole, NDI Carrara-1, located on the western margin of the Carrara Sub-basin have greatly improved the geological constraints on our preliminary stratigraphic interpretations. Our geological interpretation (Southby et al., 2021) of the Barkly Seismic Survey established three informal geological domains, each defined by dominant structural elements and/or basin characteristics. These informal domains are, from southeast to northwest. • Carrara domain: includes the south-western margins of the Carrara Sub-basin and a shoulder of shallow metamorphic basement, where overlying Proterozoic sediments of the Carrara Sub-basin are absent. The Carrara Sub-basin is as much as 10 000 m deep (Carr et al. 2019, 2020), and interpreted to comprise four superbasin sequences from oldest to youngest, the Paleoproterozoic Leichhardt (ca. 1790–1750 Ma), Calvert (ca. 1735–1690 Ma) and Isa (ca. 1670–1575 Ma) Superbasins and the Mesoproterozoic Roper Superbasin • Brunette Downs rift corridor (BDrc) is characterised by south-easterly deepening half-grabens, controlled by steeply dipping extensional bounding faults and minor sub-parallel subsidiary faults. The rift corridor has been divided into two rift packages containing the same sedimentary sequences as in the Carrara domain. The Leichhardt Superbasin successions show stratal thickening away from the bounding fault, to the northwest, whereas the Calvert Superbasin and, in particular, the Isa Superbasin, show marked southeast-directed stratal thickening into the bounding fault. However, most importantly these features share remarkably similar orientation, geometry and structural evolution to similar half grabens identified along strike in the South Nicholson and Lawn Hill Platform regions to the north-east, representing a continuous rift corridor extending over 400 km. • Beetaloo-McArthur domain: The seismic data reveals continuation of mostly flat lying Proterozoic sedimentary successions of the Beetaloo Sub-basin (the Redbank, Glyde and Nathan packages) over some 250 km southeast towards the BDrc. The southern boundary of this domain is a fault-bounded horst of Proterozoic basement rocks interpreted to be a concealed south-west extension of Murphy Province basement and which separates the Beetaloo-McArthur domain from the BDrc. The seismic data from the Barkly Seismic Survey, in conjunction the South Nicholson survey and the ongoing work on the Carrara 1 well, has identified similarities in sedimentary successions and architecture between the Carrara Sub-basin basin and the Beetaloo Sun-basin. It has also revealed extensive Paleoproterozoic successions between the Carrara and Beetaloo sub-basins. This work will greatly improve regional resource evaluations, and stimulate greenfield exploration across this part of northern Australia. Abstract/Poster presented at the 2022 Central Australian Basins Symposium IV (https://agentur.eventsair.com/cabsiv/)

<div>This study aims to understand both the burial and thermal history of the Carrara Sub-basin to further develop an understanding of possible geo-energy resources, particularly that for unconventional resources such as shale gas. A 1D and 2D model were developed using data from the above mentioned seismic and drilling campaigns, combined with previously published knowledge of the basin. This work contributes to Australia’s Future Energy Resources (AFER) Project, specifically the Onshore Basin Inventories study, which aims to promote exploration and investment in selected underexplored onshore basins. Inventory reports and petroleum systems modelling are being undertaken in select basins to highlight the oil and gas potential in underexplored provinces and to increase the impact of existing datasets.</div><div><br></div>