<p>The Paleoproterozoic Isa Superbasin and the Mesoproterozoic South Nicholson Basin in the Northern Territory and northwestern Queensland contain organic rich sedimentary units with the potential to host both conventional and unconventional petroleum systems (Gorton & Troup, 2018). On the Lawn Hill Platform, the River and Lawn supersequences of the Isa Superbasin host the recently discovered Egilabria shale gas play and are considered highly prospective shale gas targets. However, the lateral extent of these plays is currently unknown due to the limited well and associated geochemical data. Until recently, little attention had been given to the petroleum prospectivity of the Mesoproterozoic South Nicholson Basin; however there is evidence to suggest that these units also contain potential source rocks. For example, shale in drill core NTGS 00/1 Soudan, tentatively assigned as the Mullera Formation, has a reported TOC value of 3.5 wt% indicating good source rock potential (Carr et al. 2016 and references therein). Additionally, the Mullera Formation is considered equivalent to the Roper Group of the McArthur Basin (Carr et al. 2016), where shales of the Kyalla and Velkerri Formations host commercial quantities of shale gas (e.g. Revie, 2018). <p>The Energy component of Geoscience Australia’s Exploring for the Future (EFTF) program is aimed at improving our understanding of the petroleum resource potential of northern Australia, including the Lawn Hill Platform region, through delivery of a suite of new pre-competitive geoscience data and knowledge. To aid in the identification of new areas with the potential to host active petroleum systems, and to target future areas for study as part of the EFTF program, this report assesses the organic richness, quality and thermal maturity of source rocks of the South Nicholson Basin (South Nicholson Group) and Isa Superbasin (Fickling and McNamara groups). This assessment is based on a compilation of updated and quality controlled publicly available total organic carbon (TOC), Rock-Eval pyrolysis and organic matter reflectance data. Furthermore, hydrocarbon shows for the region were compiled primarily based on well completion reports and supplementary petroleum reports. <p>Seven source rocks are investigated within the Isa Superbasin and a further two in South Nicholson Basin. For the Fickling and McNamara groups of the Isa Superbasin, source rock statistics are presented by supersequence (River, Lawn, Loretta, Term, Wide, Gun and Doom supersequences). In the South Nicholson Basin, where no sequence stratigraphic framework has yet been defined, source rock statistics are presented by lithostratigraphic unit. Shales from the River and Lawn supersequences have excellent source rock potential, as is evident from the multiple gas shows. Source rocks of the River and Lawn supersequences are typically organic rich (River: average TOC 2.2 wt%, maximum 11.7 wt%; Lawn: average TOC 3.3 wt%, maximum 7.1 wt%). However, the high maturity of the analysed sediments (Lawn: Tmax average 503°C ± 87°C) indicates that the kerogen has effectively expelled hydrocarbons (HI = 21 ± 27 mg HC/ g TOC), making original source rock quality difficult to determine. <p>The Loretta, Term and Wide supersequences have a large spread of TOC values. The average TOC for all supersequences is < 1 wt%, with maximum values of 2 wt%, 5 wt% and 7 wt% respectively, demonstrating poor to good source potential. The wide range of source potential may be a product of the mixed lithologies contained within each supersequence, which include sandstone, carbonaceous shale, micaceous siltstone and organic rich siltstone. The Loretta Supersequence kerogens contain the potential to generate gas and condensate (HI = 112 ± 43 mg HC/ g TOC) over a large area from drillcores ND2 to Amoco 83-4 in the CALVERT HILLS and WESTMORELAND 1:250 000 Sheet areas respectively. The Term and Wide Supersequences require more Tmax data for a statistical analysis. The Gun and Doom supersequences appear organically lean with an average TOC < 1 wt%. However, data is extremely limited (n = 4 and 7 respectively). Gun Supersequence sediments appear to be affected by oil staining and hence warrant further investigation into their oil or condensate potential. <p>Source rocks in the South Nicholson Group contain poor to good potential to generate gas (Constance Sandstone: HI = 49 ± 27 mg HC/g TOC; Mullera Formation: HI = 49 ± 37 mg HC/g TOC). TOC averages < 1 wt% for both the Constance Sandstone and Mullera Formation with a maximum value of 1.2 wt% in the Constance Sandstone (fair gas potential) and 3.5 wt% in the Mullera Formation (good gas potential). <p>This is the first regional synthesis of source rock data sampled from the South Nicholson Basin and Fickling and McNamara groups of the Isa Superbasin and builds on the previous North Australian Basins Resource Evaluation (NABRE) studies of the 1990s. The resulting source rock statistics provide the baseline data for targeting future work within the EFTF program. Although nine stratigraphic intervals are described as a 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. In addition, future work is needed to improve our understanding of the geochemistry of generated fluids and how these correlate with source rocks. Such studies, in addition to having a robust lithostratigraphic and sequence stratigraphic framework, will assist in accurate petroleum systems analysis and future resource assessment studies.

The Energy component of Geoscience Australia’s Exploring for the Future (EFTF) program is aimed at improving our understanding of the petroleum resource potential of northern Australia, including the Lawn Hill Platform region of the Isa Superbasin. The Paleoproterozoic Isa Superbasin in northwestern Queensland contains organic rich sedimentary units with the potential to host both conventional and unconventional petroleum systems (Gorton & Troup, 2018). On the Lawn Hill Platform, the River and Lawn supersequences of the Isa Superbasin host the recently discovered Egilabria shale gas play and are considered highly prospective shale gas targets. However, the lateral extent of these plays is currently unknown due to the limited well and associated geochemical data. To aid in the identification of new areas with the potential to host active petroleum systems, this work assesses the burial and thermal history of the Lawn Hill Platform (Figure 1) by using organic richness, quality and thermal maturity of source rocks of the Isa Superbasin. This assessment is based on a compilation of updated and quality controlled publicly available total organic carbon (TOC), Rock-Eval pyrolysis and organic matter reflectance data, and combines revised assessments of the depth structure and isopach mapping by Bradshaw et al., (2018, in press). Burial-thermal relationships in the basin have been difficult to determine in the past, usually attributed to multiple hydrothermal events which has resulted in erratic, and occasionally inverted, maturity reflectance profiles (Gorton and Troup, 2018; Glikson, 1993). Additional difficulties that contribute large uncertainties to our understanding are estimating the burial history across the basin, especially the maximum depth of burial and hence the estimated amount of erosion. Initial modelling suggests erosion amounts could range anywhere from several hundreds of meters to several thousands of meters across the Lawn Hill Platform region (Figure 2). Burial and thermal history modelling is calibrated using paleo-maturity data (reflectance profiles as mentioned above, Figure 2), which is poorly constrained. Because of the age (Paleoproterozoic) of the organic matter, reflectance values of alginite and bitumen were used, which are not always comparable to the standard vitrinite reflectance profiles that are typically used for burial and thermal history modelling calibration. In this study other options of burial-thermal model calibrations were assessed to aid in characterising the petroleum potential of this region, including; bottom hole temperature, developing an improved Tmax conversion equation specific to the Isa Superbasin region, using published conversion equations to convert alginite and bitumen reflectance to vitrinite equivalent reflectance, using HI as an indicator of thermal history, oxygen isotopes (δ18O), and fluid inclusion geothermometry. Abstract and poster for presentation at the Australian Organic Geochemistry Conference 2018

Exploring for the Future (EFTF) is a four-year $100.5 million initiative by the Australian Government conducted by Geoscience Australia in partnership with state and Northern Territory government agencies, CSIRO and universities to provide new geoscientific datasets for frontier regions. As part of this program, Geoscience Australia acquired two new seismic surveys that collectively extend across the South Nicholson Basin (L120 South Nicholson seismic line) and into the Beetaloo Sub-basin of the McArthur Basin (L212 Barkly seismic line). Interpretation of the seismic has resulted in the discovery of new basins that both contain a significant section of presumed Proterozoic strata. Integration of the seismic results with petroleum and mineral systems geochemistry, structural analyses, geochronology, rock properties and a petroleum systems model has expanded the knowledge of the region for energy and mineral resources exploration. These datasets are available through Geoscience Australia’s newly developed Data Discovery Portal, an online platform delivering digital geoscientific information, including seismic locations and cross-section images, and field site and well-based sample data. Specifically for the EFTF Energy project, a petroleum systems framework with supporting organic geochemical data has been built to access source rock, crude oil and natural gas datasets via interactive maps, graphs and analytical tools that enable the user to gain a better and faster understanding of a basin’s petroleum prospectivity. <b>Citation:</b> Henson Paul, Robinson David, Carr Lidena, Edwards Dianne S., MacFarlane Susannah K., Jarrett Amber J. M., Bailey Adam H. E. (2020) Exploring for the Future—a new oil and gas frontier in northern Australia. <i>The APPEA Journal</i><b> 60</b>, 703-711. https://doi.org/10.1071/AJ19080

The Source Rock and Fluids Atlas delivery and publication services provide up-to-date information on petroleum (organic) geochemical and geological data from Geoscience Australia's Organic Geochemistry Database (ORGCHEM). The sample data provides the spatial distribution of petroleum source rocks and their derived fluids (natural gas and crude oil) from boreholes and field sites in onshore and offshore Australian basins. The services provide characterisation of source rocks through the visualisation of Pyrolysis, Organic Petrology (Maceral Groups, Maceral Reflectance) and Organoclast Maturity data. The services also provide molecular and isotopic characterisation of source rocks and petroleum through the visualisation of Bulk, Whole Oil GC, Gas, Compound-Specific Isotopic Analyses (CSIA) and Gas Chromatography-Mass Spectrometry (GCMS) data tables. Interpretation of these data enables the characterisation of petroleum source rocks and identification of their derived petroleum fluids that comprise two key elements of petroleum systems analysis. The composition of petroleum determines whether or not it can be an economic commodity and if other processes (e.g. CO2 removal and sequestration; cryogenic liquefaction of LNG) are required for development.

The Browse Basin is located offshore on Australia's North West Shelf and is a proven hydrocarbon province hosting gas with associated condensate and where oil reserves are typically small. The assessment of a basin's oil potential traditionally focuses on the presence or absence of oil-prone source rocks. However, light oil can be found in basins where source rocks are gas-prone and the primary hydrocarbon type is gas-condensate. Oil rims form whenever such fluids migrate into reservoirs at pressures less than their dew point (saturation) pressure. By combining petroleum systems analysis with geochemical studies of source rocks and fluids (gases and liquids), four Mesozoic petroleum systems have been identified in the basin. This study applies petroleum systems analysis to understand the source of fluids and their phase behaviour in the Browse Basin. Source rock richness, thickness and quality are mapped from well control. Petroleum systems modelling that integrates source rock property maps, basin-specific kinetics, 1D burial history models and regional 3D surfaces, provides new insights into source rock maturity, generation and expelled fluid composition. The principal source rocks are Early-Middle Jurassic fluvio-deltaic coaly shales and shales within the J10-J20 supersequences (Plover Formation), Middle-Late Jurassic to Early Cretaceous sub-oxic marine shales within the J30-K10 supersequences (Vulcan and Montara formations) and K20-K30 supersequences (Echuca Shoals Formation). All of these source rocks contain significant contributions of land-plant derived organic matter and within the Caswell Sub-basin have reached sufficient maturities to have transformed most of the kerogen into hydrocarbons, with the majority of expulsion occurring from the Late Cretaceous until present.

The Source Rock and Fluids Atlas delivery and publication services provide up-to-date information on petroleum (organic) geochemical and geological data from Geoscience Australia's Organic Geochemistry Database (ORGCHEM). The sample data provides the spatial distribution of petroleum source rocks and their derived fluids (natural gas and crude oil) from boreholes and field sites in onshore and offshore Australian basins. The services provide characterisation of source rocks through the visualisation of Pyrolysis, Organic Petrology (Maceral Groups, Maceral Reflectance) and Organoclast Maturity data. The services also provide molecular and isotopic characterisation of source rocks and petroleum through the visualisation of Bulk, Whole Oil GC, Gas, Compound-Specific Isotopic Analyses (CSIA) and Gas Chromatography-Mass Spectrometry (GCMS) data tables. Interpretation of these data enables the characterisation of petroleum source rocks and identification of their derived petroleum fluids that comprise two key elements of petroleum systems analysis. The composition of petroleum determines whether or not it can be an economic commodity and if other processes (e.g. CO2 removal and sequestration; cryogenic liquefaction of LNG) are required for development.

An updated National Seismic Hazard Assessment of Australia was released in 2018 (the NSHA18). This assessment leveraged off advances in earthquake-hazard science in Australia and analogue tectonic regions to offer many improvements over its predecessors. The outcomes of the assessment represent a significant shift in the way national-scale seismic hazard is modelled in Australia, and so challenged long-held notions of seismic hazard amongst the Australian seismological and earthquake engineering community. The NSHA18 is one of the most complex national-scale seismic hazard assessments conducted to date, comprising 19 independent seismic source models (contributed by Geoscience Australia and third-party contributors) with three tectonic region types, each represented by at least six ground motion models each. The NSHA18 applied a classical probabilistic seismic hazard analysis (PSHA) using a weighted logic tree approach, where the model weights were determined through two structured expert elicitation workshops. The response from the participants of these workshops was overwhelmingly positive and the participants appreciated the opportunity to contribute towards the model’s development. Since the model’s publication, Geoscience Australia has been able to reflect on the choices made both through the expert elicitation process and through decisions made by the NSHA18 team. The consequences of those choices on the production of the final seismic hazard model may not have been fully appreciated prior to embarking on the development of the NSHA18, nor during the expert elicitation workshops. The development of the NSHA18 revealed several philosophical challenges in terms of characterising seismic hazard in regions of low seismicity such as Australia. Chief among these are: 1) the inclusion of neotectonic faults, whose rupture characteristics are underexplored and poorly understood; 2) processes for the adjustment and conversion of historical earthquake magnitudes to be consistently expressed in terms of moment magnitude; 3) the relative weighting of different seismic-source classes (i.e., background, regional, smoothed seismicity, etc) for different regions of interest and exceedance probabilities; 4) the assignment of Gutenberg-Richter b-values for most seismic source models based on b-values determined from broad neotectonic domains, and; 5) the characterisation and assignment of ground-motion models used for different tectonic regimes. This paper discusses lessons learned through the development of the NSHA18, identifies successes in the expert elicitation and modelling processes, and explores some of the abovementioned challenges that could be reviewed for future editions of the model. Abstract presented at the 17th World Conference on Earthquake Engineering (17WCEE )

Petroleum geochemical datasets and information are essential to government for evidence-based decision making on natural resources, and to the petroleum industry for de-risking exploration. Geoscience Australia’s newly built Data Discovery Portal (https://portal.ga.gov.au/) enables digital discoverability and accessibility to key petroleum geochemical datasets. The portal’s web map services and web feature services allow download and visualisation of geochemical data for source rocks and petroleum fluids, and deliver a petroleum systems framework for northern Australian basins. The Petroleum Source Rock Analytics Tool enables interrogation of source rock data within boreholes and field sites, and facilitates correlation of these elements of the petroleum system within and between basins. The Petroleum Systems Summary Assessment Tool assists the user to search and query components of the petroleum system(s) identified within a basin. The portal functionality includes customised data searches, and visualisation of data via interactive maps, graphs and geoscientific tools. Integration of the petroleum systems framework with the supporting geochemical data enables the Data Discovery Portal to unlock the value of these datasets by affording the user a one-stop access to interrogate the data. This allows greater efficiency and performance in evaluating the petroleum prospectivity of Australia’s sedimentary basins, facilitating and accelerating decision making around exploration investment to ensure Australia’s future resource wealth <b>Citation:</b> Edwards, D.S., MacFarlane, S.K., Grosjean, E., Buckler, T., Boreham, C.J., Henson, P., Cherukoori, R., Tracey-Patte, T., van der Wielen, S., Ray, J. and Raymond, O., 2020. Australian source rocks, fluids and petroleum systems – a new integrated geoscience data discovery portal for maximising data potential. 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.

The Power System Review (Review) is prepared by the NT Government's Utilities Commission with the aim to provide the routine release of comprehensive and authoritative data to industry participants, prospective participants, customers, regulators and policymakers.

The AEMO Electricity Transmission Lines Diagrams are a schematic overview of the main transmission networks and interconnections for each region of the National Electricity Market (NEM) high voltage transmission network