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  • Effective mineral, energy and groundwater resource management and exploration rely on accurate geological maps. While geological maps of the surface exist and increase in resolution, maps of the subsurface are sparse, and the underpinning geological and geophysical constraints are disordered or non-existent. The Estimates of Geological and Geophysical Surfaces (EGGS) database seeks to enable robust subsurface geological mapping by establishing an ordered collection of precious geological and geophysical interpretations of the subsurface. EGGS stores the depth to geological boundaries derived from boreholes as well as interpretations of depth to magnetic top assessments, airborne electromagnetics inversions and reflection seismic profiles. Since geological interpretation is iterative, links to geophysical datasets and processing streams used to image the subsurface are stored. These metadata allow interpretations to be readily associated with the datasets from which they are derived and re-examined. The geological basis for the interpretation is also recorded. Stratigraphic consistency is maintained by linking each interpretation to the Australian Stratigraphic Units Database. As part of the Exploring for the Future program, >170 000 points were entered into the EGGS database. These points underpin construction of cover thickness models and economic fairway assessments. <b>Citation:</b> Mathews, E.J., Czarnota, K., Meixner, A.J., Bonnardot, M.-A., Curtis, C., Wilford, J., Nicoll, M.G., Wong, S.C.T., Thorose, M. and Ley-Cooper, Y., 2020. Putting all your EGGS in one basket: the Estimates of Geological and Geophysical Surfaces database. In: Czarnota, K., Roach, I., Abbott, S., Haynes, M., Kositcin, N., Ray, A. and Slatter, E. (eds.) Exploring for the Future: Extended Abstracts, Geoscience Australia, Canberra, 1–4.

  • This dataset contains the limit and extent of Northern Australia as defined by the Northern Australia Infrastructure Facility Act 2016 (https://www.legislation.gov.au/Details/C2021C00228) and Northern Australia Infrastructure Facility Amendment (Extension and Other Measures) Act 2021 (https://www.aph.gov.au/Parliamentary_Business/Bills_Legislation/bd/bd2021a/21bd062).

  • <p>The Roebuck Basin on Australia’s offshore north-western margin is the focus of a regional hydrocarbon prospectivity assessment being undertaken by the North West Margin Energy Studies Section (NWMES). This offshore program is designed to produce pre-competitive information to assist with the evaluation of the hydrocarbon resource potential of the central North West Shelf and attract exploration investment to Australia. <p>The recent oil and gas discoveries at Phoenix South 1 (2014), Roc 1 (2015-16), Roc 2 (2016), Phoenix South 2 (2016), Phoenix South 3 (2018) and Dorado 1 (2018) in the Bedout Sub-basin demonstrate the presence of a petroleum system in Lower Triassic strata. The current study aims to better understand this new petroleum system and establish its extent. <p>As part of this program, TOC and Rock-Eval pyrolysis analyses were undertaken by Geoscience Australia on selected rock samples from the well Roc 2 to establish their hydrocarbon-generating potential and thermal maturity.

  • <p>The Roebuck Basin and adjoining Beagle Sub-basin are underexplored areas on Australia’s North West Shelf and are undergoing renewed exploration interest since the discovery of oil at Phoenix South 1 and gas at Roc 1, 2 in the Bedout Sub-basin. A well folio of 24 offshore wells across the Beagle, Bedout, Rowley and Barcoo sub-basins was completed as part of Geoscience Australia’s assessment of hydrocarbon prospectivity across the region. The study consists of composite well log plots summarising lithology, stratigraphy, GA’s newly acquired biostratigraphic and geochemical data and petrophysical analysis, in conjunction with revised sequence interpretations. <p>The wells included in the well folio package are: <p>Anhalt 1, Barcoo 1 ST2, Bedout 1, Bruce 1, Cossigny 1, De Grey 1A ST1, Delambre 1, Depuch 1, East Mermaid 1B ST1, Hanover South 1, Huntsman 1, Keraudren 1. Lagrange 1, Minilya 1, Nebo 1, Omar 1, Phoenix 1, Phoenix 2, Phoenix South 1 ST1 ST2, Picard 1, Poissonnier 1, Roc 1, Steel Dragon 1 and Wigmore 1

  • Geological storage of CO2 has been identified as an effective technology to reduce greenhouse gas emissions and mitigate global climate change. Deep saline aquifers are recognised as having the highest CO2 storage potential. The Junggar Basin is located in the northern Xinjiang and has extensive distributed deep saline aquifers, which could be the effective sites for CO2 storage. CO2 injectivity and storage capacity were investigated through both static and dynamic modelling on the Cretaceous Donggou Formation aquifer in Zhundong area, Junggar Basin. A static reservoir model was constructed by integrating well data and seismic attributes, and the best estimate of storage capacity (P50) was estimated to be approximately 72 million tonnes using a storage coefficient of 2.4% (P50). Dynamic simulation provided a comprehensive understanding of injectivity, storage capacity and explanation of the different storage mechanisms after CO2 injection. The total injection of CO2 was 31.4 million tonnes with five injection wells. Simulations suggest that at year 300 after injection, 28% of the injected CO2 was stored by residual trapping and 26% of the injected CO2 was dissolved into formation water. The modelling results suggest that there is good potential for large scale CO2 aquifer storage in the Junggar Basin.

  • <p>The Roebuck Basin on Australia’s offshore north-western margin is the focus of a regional hydrocarbon prospectivity assessment being undertaken by the North West Margin Energy Studies (NWMES) section. This offshore program is designed to produce pre-competitive information to assist with the evaluation of the hydrocarbon resource potential of the central North West Shelf and facilitate exploration investment in Australia. <p>The recent oil and gas discoveries at Phoenix South 1 (2014), Roc 1 (2015-16), Roc 2 (2016), Phoenix South 2 (2016), Phoenix South 3 (2018) and Dorado 1 (2018) wells in the Bedout Sub-basin demonstrate the presence of a petroleum system in Lower Triassic strata. The current study aims to better understand this new petroleum system and establish its extent. <p>As part of this program, a range of organic geochemical analyses were acquired on two crude oils from the Phoenix South 1 ST2 well with these data released in this dataset.

  • It is generally accepted that the near surface search space for mineral deposits in Australia and elsewhere in the world has been well explored and the frontier of exploration lies beneath post-mineralisation cover. The Exploring for the Future program aims to unlock this new search space in northern Australia and parts of southern Australia by reducing the technical risk of mineral exploration through the provision of innovative pre-competitive data and information. The first step to de-risk undercover exploration is to simply define the depth to prospective rocks as cover-thickness places first order constraints on the economic search space. With this aim in mind we present a preliminary model of the depth to pre-Neoproterozoic rocks between Tennant Creek and Mt Isa, an area of focused integrated studies of the Exploring for the Future program. This work aims to compliment recent and ongoing mineral potential assessments in this region, which suggest covered pre-Neoproterozoic rocks are prospective for iron oxide-copper-gold and sediment hosted base metal mineral deposits. Our model utilises a dasets of over eight four thousand point estimates of the depth to pre- Neoproterozoic strata from boreholes, reflection seismic profile interpretations and depth to magnetic top estimates mostly sourced from the new Estimates of Geological and Geophysical Surfaces database supplemented by the distribution of pre-Neoproterozoic strata outcrops. These constraints were objectively queried based on their reliability, subsampled at 0.05 degrees and gridded using an adjustable tension continuous curvature-surfacing algorithm. The result shows Palaeozoic cover-thickness generally increases away from outcrops with a notable exception east of Tennant Creek where cover-thickness is typically less than 250 m thick. Fortuitously, this region of shallow cover termed the East Tennant Ridge corresponds with a region recently assess to have potential to host iron oxide-copper-gold mineralisation.

  • <p>In the South Nicholson region of Queensland and the Northern Territory, the Paleoproterozoic Isa Superbasin and the Mesoproterozoic South Nicholson Basin have the potential to host both conventional and unconventional petroleum systems (Gorton & Troup, 2018). The region remains poorly explored however with only 19 petroleum wells drilled in total (Carr et al., 2016). Although nine stratigraphic intervals are described as potential source rocks, data coverage is extremely limited and a large proportion of the available data is old and of poor quality. To more comprehensively characterise these organic rich source rocks, higher resolution coverages of pre-competitive geochemical data is required (Jarrett et al. 2018). <p>This report contains the total organic carbon (TOC) content and Rock-Eval pyrolysis data of 674 samples selected from twelve drill cores housed in the Geological Survey of Queensland’s Brisbane core repository including Amoco DDH 83-1, Amoco DDH 83-2, Amoco DDH 83-3, Amoco DDH 83-4, Argyle Creek 1, Armraynald 1, Burketown 1, Desert Creek 1, Egilabria 1, Egilabria 2 DW1, Egilabria 4, Morstone 1, MORSTONE DDH1. This data was generated at the Isotope and Organic Geochemistry Laboratory at Geoscience Australia as part of the Exploring for the Future program.

  • Exploring for the Future (EFTF) is a four year $100.5 million initiative by the Australian Government conducted in partnership with state and territory government agencies, Geoscience Australia, CSIRO, and universities. The EFTF initiative aims to boost northern Australia’s attractiveness as a destination for resource exploration investment. As part of this program, Geoscience Australia’s researchers have gathered, on an unprecedented scale, new pre-competitive data and information about the energy, mineral, and groundwater resource potential concealed beneath the surface in northern Australia. A major EFTF deliverable, the acquisition of crustal seismic reflection data in the region between the southern McArthur Basin and the Mount Isa western succession, crossing the South Nicholson Basin and Murphy Province, was completed in August 2017 (Figure 1). Prior to this survey, the region contained no seismic data, minimal well data and minor subsurface geological data (Carr et al 2016). Five seismic lines were acquired in an orientation to best image geological features as identified in outcrop, and subsurface geophysical anomalies as identified in gravity and magnetics data (Figure 1). The acquisition was designed to explore both exposed and undercover sedimentary basins to better understand the location and scale of the region’s potential resources and crustal architecture. The seismic program was undertaken in tandem with regional groundwater (Wallace et al 2018), surface geochemistry (Bastrakov et al 2018), and petroleum and mineral systems geochemistry (Jarrett et al 2018a; 2018a,b) studies. The primary aim of the survey was to investigate prominent areas with a low measured gravity response (‘gravity lows’) in the region to determine if they represent thick basin sequences similar to the nearby Beetaloo Sub‑basin, a highly prospective petroleum province (Cote et al 2018, Close et al 2016) . The gravity low that straddles the Northern Territory–Queensland border to the north of Camooweal (Figure 1), which is entirely overlain by the Georgina Basin, was a primary target of the survey. This new dataset has greatly improved our understanding of the geology and resources of the region. It was initially released in Alice Springs at the 2018 Annual Geoscience Exploration Seminar (Henson et al 2018). This paper provides an update of project results and presents an initial interpretation of the sequence stratigraphy.

  • <p>Organic matter in sedimentary rocks changes physical properties and composition in an irreversible and often sequential manner after burial, diagenesis, catagenesis and metagenesis with increasing thermal maturity. Characterising these changes and identifying the thermal maturity of sedimentary rocks is essential for calculating thermal models needed in a petroleum systems analysis. <p>In the Isa Superbasin, the thermal history of the sediments is difficult to model due to erratic thermal maturity profiles, which are often inverted with depth (e.g. Glikson et al. 2006; Gorton & Troup, 2018). In previous studies, these erratic profiles have been attributed to multiple fluid flow events through the basin (Glikson et al. 2006). However, another reason to explain some of these results may be due to low statistical significance and quality control of legacy data. The Australian Standard for reflectance measurements Australian Standard AS2856.3-1998. Coal petrography: Method for microscopical determination of the reflectance of coal macerals requires a minimum of 30 reflectance measurements to be taken on a sample for statistical significance and to maintain confidence in the results. However, Barker & Pawlewicz (1993) suggest a minimum of 20 measurements in sedimentary rocks which may have fewer macerals than coals. The numbers of reflectance measurements are not always provided with legacy data, however some core samples have very low values (n < 5) suggesting low confidence in some results. <p>In order to maintain confidence in the legacy data, Geoscience Australia contracted CSIRO Energy to conduct a thorough organic petrological analysis of 22 shale samples from two drill cores; Amoco DDH 83-4 and Desert Creek 1 from the Fickling and McNamara groups of the Isa Superbasin. These two wells were selected as Geoscience Australia has recently conducted a full suite of organic geochemistry on these wells and there is legacy reflectance data available. <p>The estimated organic matter (OM) content of the samples analysed ranged from <0.1% to 30% by volume. The majority of the OM is bitumen that occurs as fine disseminations throughout the mineral matrix in addition to infilling inter-granular porosity of carbonates and other minerals. The abundance of bitumen resulted in reflectance measurements consistent with Australian Standards for most samples, ensuring high confidence in the results. <p>In Amoco DDH 83-4, the reflectance data generated in this study show a broadly linear increase with depth down core, ranging from thermally mature to overmature. The outliers in the down core trend represent samples with low OM, a minimum amount of bitumen to conduct reflectance measurements on and hence, low statistical significance and low confidence in the results. These results highlight the need to work within the guidelines specified by the Australian standard to maintain confidence in the data. In Desert Creek-1, samples studied are mature for dry gas generation. Although still broadly consistent with previously published work, the down well reflectance profile produced for this study is much less erratic compared with reflectance profiles generated from legacy data. This is likely due to the careful analysis of the same OM type in the samples. For the legacy Desert Creek 1 data, neither reflectance histograms nor the number of reflectance measurements are provided and therefore reasons for the differences between results are not certain. <p>The results of this study have major implications in a petroleum systems modelling context, as thermal and burial history modelling requires reliable equivalent vitrinite reflectance data for calibration purposes. In the Fickling Group, the new results show that hydrocarbon generation has occurred. As the thermal maturity in the previous study was largely immature, the hydrocarbon prospectivity of the area has been upgraded. The statistically significant results of this study provide a more robust calibration dataset for use in petroleum systems models in the Isa Superbasin. Similar studies on other wells in the basin may be necessary to further reduce uncertainty.