The recently drilled deep stratigraphic drill hole NDI Carrara 1 penetrates the carbonate formations of the Cambrian Georgina Basin as well as the underlying Proterozoic successions of the Carrara Sub-basin. The Proterozoic section consists predominantly of tight shales, siltstones, and calcareous clastic rocks. This study aims to assess the petrophysical properties of the Proterozoic shales using conventional wireline logs. Gamma ray and neutron-density crossplots were used to calculate shale volume fraction, and neutron-density crossplots were applied to compute the total and effective porosity of non-shale rocks. Total organic carbon (TOC) content was interpreted using artificial neural networks, and was used to derive the volume of organic matter was converted from TOC content. Bulk density logs were corrected by removing the kerogen effect in the organic-rich shales. Matrix and kerogen densities were obtained by correlating the reciprocal of grain density with TOC content. Total shale porosity was calculated from kerogen-corrected density porosity and organic porosity. Effective porosity was estimated by removing the shaliness effect. Water saturation was derived using the Simandoux equation. The Proterozoic Lawn Hill Formation in NDI Carrara 1 exhibits petrophysical properties that indicate a favourable potential for shale gas resources. Herein, we define three informal intervals within the intersected Lawn Hill Formation; the upper Lawn Hill, the Lawn Hill shale, and the lower Lawn Hill. The net shale thickness of the upper Lawn Hill and Lawn Hill shale intervals are 165 m and 149 m, respectively. The increased TOC content and organic porosity of the upper Lawn Hill and Lawn Hill shale implies higher adsorbed gas content potential. The Lawn Hill shale has the highest gas saturation (average of 31.1%) and the highest potential for free gas content, corresponding to the highest methane responses in logged mud gas profiles. This extended Abstract was submitted to/presented at the Australasian Exploration Geoscience Conference (AEGC) 2023, Brisbane (https://2023.aegc.com.au/)

Geoscience Australia’s Exploring for the Future (EFTF) 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, $225m investment by the Australian Government. The deep stratigraphic drill hole, NDI Carrara 1 (~1751 m), was completed in December 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 1100 m of Proterozoic sedimentary rocks uncomformably overlain by 630 m of Cambrian Georgina Basin carbonates. This contractor report (FIT - Schlumberger) presents hydrocarbon and aqueous fluid inclusion petrology and data (micro-thermometry, salinities etc.) on four hydrocarbon-bearing calcite veins sampled from NDI Carrara 1 between 762.56-763.60 m depth, (under contract to, and fully funded by, Geoscience Australia as part of the Exploring for the Future program).

<div>The South Nicholson 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. The drilling aimed to gather new subsurface data on the potential mineral and energy resources in the newly identified Carrara Sub-basin. NDI Carrara 1 is located in the eastern Northern Territory, on the western flanks of the Carrara Sub-basin on the South Nicholson Seismic line, reaching a total depth of 1751 m, intersecting ca. 630 m of Cambrian Georgina Basin overlying ca. 1100 m of Proterozoic carbonates, black shales and minor siliciclastics (https://portal.ga.gov.au/bhcr/minerals/648482).</div><div>&nbsp;</div><div>Following a public data release of the borehole completion report, CSIRO was contracted by Geoscience Australia (GA) under the Exploring for the Future program to analyse samples from NDI Carrara 1 for quantitative bulk and clay fraction analysis. This report presents results for quantitative bulk and clay (<2 µm) fraction analysis by X-ray powder diffraction (XRD) on 32 bulk core samples from the NDI Carrara 1. Samples were prepared and analysed at the CSIRO’s Waite Laboratories in South Australia.</div><div><br></div>

The National Drilling Initiative (NDI) will manage and deliver drilling programs in multiple case study areas proposed by MinEx CRC’s partner geological survey organisations. The NDI vision is to drill multiple holes in a region to map the regional geology and architecture and define the potential for mineral systems in 3D. The areas shown in this web service describe the spatial locations of the study areas.

The Proterozoic succession in the NDI Carrara 1 drill hole, Northern Territory, consists predominantly of tight shales, siltstones, and calcareous clastic rocks. As part of Geoscience Australia’s Exploring for the Future program, this study aims to derive porosity, permeability and gas content from both laboratory testing and well log interpretation from machine learning approaches, to improve the Proterozoic shale gas reservoir characterisation. The Proterozoic Lawn Hill Formation was divided into four chemostratigraphic packages. The middle two packages were further divided into seven internal units according to principal component analysis and self-organising map clustering on well logs and inorganic geochemical properties. Artificial neural networks were then applied to interpret the mineral compositions, porosity and permeability from well logs, density and neutron-density crossplot interpretations. Gas content was estimated from the interpreted porosity, gas saturation, total organic carbon and clay contents. Petrophysical interpretation results are summarised for all chemostratigraphic packages and units. Package 2 (1116–1430.1 m) has the highest potential among the four chemostratigraphic packages. P2U1 (1116–1271 m) and P2U3 (1335.5–1430.1 m) units have the most favourable petrophysical properties for organic-rich shales with the average total gas contents of 1.25 cm3/g and 1.30 cm3/g, geometric mean permeability of 4.79 µD and 17.56 µD, and net shale thickness of 54.4 m and 85.3 m, respectively. P3U4 unit (687.9–697.9 m) has high gas content and permeability, with the net shale thickness of 29.1 m. Besides the organic-rich shales, the tight non-organic-rich siltstone and shale reservoirs in package 1 (below 1430.1 m) have average gas saturation of 14% and geometric mean permeability of 1.31 µD, respectively. Published in The APPEA Journal 2023. <b>Citation:</b> Wang Liuqi, Bailey Adam H. E., Grosjean Emmanuelle, Carson Chris, Carr Lidena K., Butcher Grace, Boreham Christopher J., Dewhurst Dave, Esteban Lionel, Southby Chris, Henson Paul A. (2023) Petrophysical interpretation and reservoir characterisation on Proterozoic shales in National Drilling Initiative Carrara 1, Northern Territory. <i>The APPEA Journal</i><b> 63</b>, 230-246. https://doi.org/10.1071/AJ22049

<div>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 stratigraphic 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) 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 Georgina Basin carbonates.&nbsp;</div><div>Geoscience Australia has undertaken a range of investigations on the lithology, stratigraphy and geotechnical properties of NDI Carrara 1 as well as undertaking a range of analyses of about 500 physical samples recovered through the entire core. Analyses included geochronology, isotope studies, mineralogy, inorganic and organic geochemistry, petrophysics, geomechanics, thermal maturity and petroleum systems investigations.</div><div>Rock-Eval pyrolysis raw data undertaken by Geoscience Australia were reported in Butcher et al. (2021) on selected rock samples to establish their total organic carbon content, hydrocarbon-generating potential and thermal maturity. Interpretation of the Rock-Eval pyrolysis data concluded that a large portion of rocks within the Proterozoic section displayed unreliable Tmax values due to poorly defined S2 peaks resulting from high thermal maturity and low hydrogen content. In order to obtain more reliable Tmax values, Rock-Eval pyrolysis of selected isolated kerogens, where organic matter is concentrated and mineral matrix effects are removed, were conducted and the resulting data are presented in this report.&nbsp;</div><div><br></div>

The NDI Carrara 1 sedimentology, microstructural analysis and sequence stratigraphy program was a joint undertaking between Geoscience Australia (GA) and CSIRO (Perth) as part of the Exploring for the Future program to examine the sedimentology, sequence stratigraphy and paleogeography of the Carrara Sub-basin. The program was based on recovered core from the National Drilling Initiative (NDI) deep stratigraphic drill hole, NDI Carrara 1. NDI Carrara 1 is the first drill hole to intersect the Proterozoic rocks of the Carrara Sub-Basin, a large depocentre discovered during seismic acquisition conducted during the first phase of the EFTF program in 2017. NDI Carrara 1 is located on the western flanks of the Carrara Sub-basin, reaching a total depth of 1751 m, intersecting ca. 630 m of Cambrian Georgina Basin overlying ca. 1100 m of Proterozoic carbonates, black shales and siliciclastics. This final report, and associated appendices, compiles the findings of three milestone deliverables. The first component of the report addresses the sedimentology of the Proterozoic section of NDI Carrara 1 with an accompanying Appendix (core log, from HyLogger data). The second component is a detailed microstructural analysis based on selected thin sections in intervals of interest. The final component completed a 1D sequence stratigraphic assessment, enabling regional stratigraphic correlations to be established and an interpretive paleogeographic map generated for the Proterozoic sequences of interest across the region .

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.

NDI Carrara 1 is a deep stratigraphic drill hole (~1751m) 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 1100 m of Proterozoic sedimentary rocks uncomformably overlain by 630 m of Cambrian Georgina Basin carbonates. This report presents the petrology conducted on 50 selected thin sections of NDI Carrara 1 undertaken by Microanalysis Australia (under contract to Geoscience Australia as part of the Exploring for the Future program).

<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