The Canning Basin is a large intracratonic basin in Western Australia that remains one of the least explored Paleozoic basins in the world. Recent resource assessments have renewed interest in the basin, in particular for unconventional gas within Ordovician organic-rich shales, although these proposed plays remain untested. Exploring for the Future (EFTF) is a program dedicated to exploring Australia’s resource potential and boosting investment. Launched in 2016 with $100.5 million in funding from the Australian Government, it initially focused on northern Australia. Geoscience Australia and the Geological Survey of Western Australia collected new, pre-competitive datasets in the frontier Kidson Sub-basin to better understand its energy resource potential. Here we present an overview of the regional petroleum systems with a focus on the modelled Ordovician section within the Kidson Sub-basin and Barnicarndy Graben (previously Waukarlycarly Embayment). Three Larapintine petroleum systems are recognised in the Ordovician (L2), Devonian‒earliest Carboniferous (L3), and Carboniferous (L4) successions of the Canning Basin. Integration of petroleum systems with interpretation of the Kidson Sub-basin seismic survey 18GA-KB1 shows that the Ordovician section is extensive, and hence, the Larapintine 2 Petroleum System is of most exploration interest across this frontier region. Ordovician organic-rich units are known within the Nambeet (Tremadocian–Floian), Goldwyer (Dapingian–Darriwilian) and Bongabinni (Sandbian) formations; however, only Nambeet and Goldwyer source rocks are considered to be present within the Kidson Sub-basin. Oil and gas shows occur within Ordovician and Silurian reservoirs, of which many are sub-salt. The range in the geochemical profile of shows from Goldwyer, Nita and Sahara reservoirs implies generation from numerous source units within the Goldwyer and Bongabinni formations. The origin of oil and gas shows within the Nambeet and Willara formations, including those in Patience 2 in the Kidson Sub-basin, is unknown but imply the presence of multiple lower Ordovician source units and include the Nambeet Formation. Within the Kidson Sub-basin, Kidson 1 is located closest to the main depocentre, whereas other wells are proximal to shelves and margins. In general, these latter wells return discouraging hydrocarbon potential pyrolysis parameters as a consequence of their sub-optimal location for source rock development and thermal maturation history. Kidson 1 penetrates the Goldwyer Formation and has TOC contents that are considered more representative of source rock richness (although diesel contamination is present) within the depocentre. Data paucity is the key limitation in resource evaluation for the Kidson Sub-basin, as such, an evaluation with volumetrics is not possible. 1D petroleum systems models of ten wells located in either the Kidson Sub-basin, Willara Sub-basin or Barnicarndy Graben were constructed to resolve whether potential source rocks were capable of hydrocarbon generation. The models demonstrate maturation of Ordovician source rocks resulting in near-complete transformation during Permian to Triassic deposition and burial. A 2D petroleum systems model constructed along the regional 2D seismic line 18GA-KB1 predicts full maturation of Larapintine 2 source rocks in the deeper parts of the Kidson Sub-basin. Expulsion and migration is considered to have taken place during the Permian‒Triassic, with potential accumulations trapped by evaporitic and fine-grained units of Ordovician and Silurian age.

Presentation for the Exploring for the Future Roadshow presentation about the Kidson Sub-basin seismic survey, Waukarlycarly-1 stratigraphic well, in addition to the Centralian Super Basin well correlation study.

Geoscience Australia’s Exploring for the Future (EFTF) program has established new techniques to collect onshore pre-competitive datasets on an unprecedented scale. The Exploration Incentive Scheme (EIS) is a Western Australian Government initiative that aims to encourage exploration for the long-term sustainability of the state’s resources sector. Integration of EFTF and EIS datasets has improved understanding of the geology across northern Australia, and the associated energy, mineral and groundwater resources potential. The onshore Canning Basin covers approximately 530 000 km2, and has proven prospectivity for conventional oil and gas, mainly in the northern part of the basin. Potential exists for unconventional resources that remain largely unexplored and untested. Gas resource assessments suggest that the basin has significant potential for recoverable shale gas and tight gas. Even with exploration continuing along the flanks of the Fitzroy Trough, the Canning Basin remains one of the least explored Paleozoic basins in the world (DMIRS, 2020). Australia’s longest onshore seismic line, 18GA-KB1, acquired in the southern Canning Basin addresses a long standing data gap across the Kidson Sub-basin and Waukarlycarly Embayment that assists with the resource evaluation of this frontier region. The Kidson Sub-basin covers 91 000 km2 and has a sag basin architecture. Preliminary interpretation of the seismic data indicates that the sedimentary basin is approximately 6 km deep, and includes a conformable package of Ordovician–Devonian siliciclastic, carbonate and evaporite facies of exploration interest. The Carboniferous succession is interpreted as not being present. Located on the western end of the seismic line, the newly drilled deep stratigraphic well Waukarlycarly 1 penetrated 2680.53 m of Cenozoic and Paleozoic strata and provides stratigraphic control for the geology imaged in the Waukarlycarly Embayment. A comprehensive elemental and δ13C isotope chemostratigraphy study assists with stratigraphic correlations within Ordovician sedimentary strata across the region (Forbes et al., 2020a, b). Oil and gas discoveries throughout the Canning Basin were generated from Paleozoic marine source rocks, deposited under stratified oxic and euxinic water columns. Three distinct petroleum systems, the Ordovician (Larapintine 2), Late Devonian (Larapintine 3) and latest Devonian–early Carboniferous (Larapintine 4), are recognized based on the geochemical character of their associated fluids and each display strong stratigraphic control (Carr et al., 2020). Widespread generation of gas from Paleozoic sources is evident from molecular analyses of gases recovered from petroleum wells and fluid inclusions (Boreham et al., 2020). Currently the Larapintine 2 Petroleum System is deemed most prospective system in the Kidson Sub-basin.

The Ordovician is an important period in Earth’s history with exceptionally high sea levels that facilitated the Great Ordovician Biodiversification Event. This crucial biological event is regarded as the second most significant evolutionary event in the history of Paleozoic life, after the Cambrian radiation. The present study integrates palynological, petrographic, molecular and stable isotopic (δ13C of biomarkers) analyses of cores from five boreholes that intersected the Goldwyer Formation, Canning Basin, Western Australia, to determine depositional environments and microbial diversity within a Middle Ordovician epicontinental, tropical sea. A major transgression was detected in the laminated shales of the lower Goldwyer Formation (Units 1+2) which were deposited in anoxic bottom waters, as confirmed by low (<1) Pristane/Phytane ratios, and elevated dibenzothiophene and gammacerane indices. A second, less extensive, flooding event is recorded by shallow marine sediments of the upper Goldwyer Formation (Unit 4). Cores of these sediments, from two wells (Solanum-1 and Santalum-1A) are bioturbated and biomarkers indicate relatively oxygenated conditions, as well as the presence of methanotrophic bacteria, as determined from the high 3-methylhopane indices. Typical Ordovician marine organisms including acritarchs, chitinozoans, conodonts and graptolites were present in the lower and upper Goldwyer Formation, whereas the enigmatic organism Gloeocapsomorpha prisca (G. prisca) was only detected in Unit 4. The presence of G. prisca was based on microfossils and specific biosignatures presenting an odd-over-even predominance in the C15 to C19 n-alkane range. Cryptospores were identified in Unit 4 in the Theia-1 well and are most likely derived from bryophytes, making this is the oldest record of land plants in Australian Middle Ordovician strata. Biomarkers in some samples from Unit 4 that also support derivation from terrestrial organic matter include retene, benzonaphthofurans and δ13C-depleted mid-chain n-alkanes. This research contributes to understanding Ordovician marine environments from a molecular perspective since few biomarker studies have been undertaken on age-equivalent sections. Furthermore, the identification of the oldest cryptospores in Australia and their corresponding terrestrial biomarkers contributes to understanding the geographical evolution of early land plants.

The Exploring for the Future (EFTF) program is an initiative by the Australian Government dedicated to boosting investment in resource exploration in Australia. Geoscience Australia’s EFTF Energy program is aimed at improving the understanding of the petroleum resource potential of Australia. A key to understanding resource potential and basin evolution is a reliable time frame to correlate rock units. This palynological reconnaissance study focusses on the acid-resistant organic-walled microfossils (or palynomorphs) recovered from 42 samples taken within the fully cored Lower Ordovician Nambeet Formation (1354.80–2435.04 mRT) in the Barnicarndy 1 stratigraphic well, located in the Barnicarndy Graben, Canning Basin. The lack of palynomorph recovery from the Barnicarndy Formation, Yapukarninjarra Formation, and Neoproterozoic Yeneena Basin, also intersected in this well, means that the age of those units remain undated using micropalaeontological methods. The purpose of this study is to assess the yield and preservation of recovered palynomorphs, and determine their utility for regional, and international, correlation of the Lower Ordovician sedimentary section. Although the total organic matter content of the sampled Lower Ordovician core is typically low (average ≤0.2 wt%), reflecting sediment deposition in an oxidising, open marine environment, a diverse suite of palynomorphs has been identified and includes: acritarchs (of probable algal origin); other algal microfossils (including green algae, or prasinophytes); probable cyanobacteria; cryptospores (derived from the earliest land plants); graptolites and chitinozoans (both from extinct marine groups); scolecodonts (detached elements of worm jaws); and organic-walled tubes, some of which are of either probable fungal or cyanobacterial origin. Digital images accompany this record and include examples of all of these aforementioned microfossils. Microfossil yield per sample is, mostly, low; and preservation ranges from poor, where specimens are either fragmentary and/or distorted by pyrite crystal growth, to good; and commonly both preservation states occur together within the same sample. As with the admixture of preservation states per sample, palynomorph colour, typically used as an indicator of thermal maturity of organic matter, commonly ranges from thermally mature (brown) to over mature (black), often within the same Lower Ordovician core sample. This is tempered by the fact that these observations are based, mostly, on oxidised kerogen preparations, but, the relative maturity indicators remain valid. The occurrence of acritarchs assigned to the Rhopaliophora pilata–R. palmata complex, together with Athabascaella playfordii, and Aryballomorpha grootaertii, allows correlation with assemblages previously recovered from the Nambeet Formation intersected in two petroleum exploration wells in the Canning Basin (Samphire Marsh 1, type section; and Acacia 2). These species also occur globally, with A. grootaertii recovered from sedimentary rocks in southern China and Canada that have been independently dated as Early Ordovician, late Tremadocian–early Floian (about 475–482 Ma). Conodont faunas from cores in Barnicarndy 1 record the same (late Tremadocian–early Floian) age, which enhances the utility of A. grootaertii for age dating. The dates also demonstrate that the Barnicarndy 1 well intersects some of the oldest Paleozoic sedimentary rocks in the Canning Basin. There are compositional differences between the palynological assemblages from the younger Samphire Marsh Member and underlying Fly Flat Member of the Nambeet Formation which, despite difficulties in sample processing, are genuine and reflect changes in the depositional environment. Most obvious is the record of Gloeocapsomorpha prisca and ?Eomerismopedia maureeniae, both of probable cyanobacterial affinity, with in situ occurrences in the Lower Ordovician Samphire Marsh Member. Earlier studies suggested that G. prisca was confined to younger (Middle) Ordovician palynological assemblages in the Canning Basin, and its common abundance was used as a biozone marker, but the occurrences reported here and in unpublished studies, have shown that this is no longer applicable. In younger Ordovician formations in the Canning Basin (notably the upper Goldwyer Formation), and globally, G. prisca is an important organism contributing to the hydrocarbon potential of Paleozoic marine source rocks. If present in greater abundance elsewhere in the basin, it could increase the petroleum prospectivity of the Nambeet Formation. A distinctively shaped acritarch, of probable algal origin, assigned to the genus Dactylofusa is restricted to an assemblage from the Fly Flat Member, and may be useful for future basinal biozone correlation. Most samples from the Samphire Marsh Member contain early land-plant spores, of probable bryophyte affinity, that sometimes occur together with irregularly-shaped spore clusters, likely derived from aeroterrestrial charophyte algae; both of which are collectively known as cryptospores. In addition, Grododowon orthagonalis, superficially similar to E. maureeniae and recorded in some samples from the Samphire Marsh Member, is also considered to be of charophyte algal origin. The cryptospores include the species Dyadospora murusattenuata, Tetraplanarisporites sp., and Laevolancis divellomedium. Collectively, these cryptospores are important as they herald the first emergence of plants onto wetlands during the Early Ordovician; and being of late Tremadocian–early Floian age, they are amongst the oldest land-plant spores known in Australia and globally. The record of cryptospores from Barnicarndy 1 enhances those recently reported from the Nambeet Formation in Samphire Marsh 1, and from the lower Goldwyer Formation in Theia 1. Locally, the cryptospore record demonstrates a supply of terrestrial material into the marine environment during deposition of the Samphire Marsh Member. Globally, records of these cryptospores contribute to the understanding of the evolution and geographic distribution of the earliest land flora. Inevitably, there are microfossils found in this study that could be described as new species, and a detailed systematic study of all fossil groups is recommended to realise their utility for zonal correlation and age dating. The palynological data presented here provide complementary information to the conodont age dating, organic petrological, and organic geochemical studies conducted on the Barnicarndy 1 core. Collectively, these studies contribute to a better understanding of the depositional history and hydrocarbon prospectivity of the Canning Basin.

<p>The Early Paleozoic, specifically the Middle Ordovician, marks a significant period in Earth's history due to the appearance and diversification of life on land. Plant megafossil records indicate vascular plants first appeared in the Early Silurian and by Devonian times had diversified rapidly (e.g. Wellman and Gray, 2000; Steemans et al., 2009; Kenrick et al., 2012; Strother, 2016). However non-vascular plants (bryophytes) predating vascular plants are rarely preserved as body fossils and the bryophyte microfossil record in the lowermost Palaeozoic is scarce. This lack of fossil data severely limits our understanding of life in the earliest non-marine environments and the origin of land plants. <p>In comparison to microfossils, molecular fossils (biomarkers) are more ubiquitous in the sedimentary record and have a higher preservation potential, thus providing a powerful tool to track terrestrial signals when microfossils are either scarce or absent. Molecular proxies such as long chain n-alkanes have been used extensively in both modern and ancient environments to identify terrestrial contributions to the organic matter (e.g. Eglinton and Hamilton, 1967; Ficken et al., 2000; Hautevelle et al., 2006). Furthermore, the isotopic composition of these molecules can be used to further distinguish between sources (e.g. Bird et al., 1995; Sikes et al., 2009; Rouillard et al., 2016). That being said, only relatively few studies have combined palynological evidence with geochemical proxies to assess geochemical signatures of early land plants. <p>This work presents biomarker and palynological data of the Middle Ordovicianupper Goldwyer Formation which records the earliest occurrence of land plant microfossils (cryptospores) in Australia. The higher-molecular-weight n-alkane distributions and their isotopic compositions recorded in the upper Goldwyer show high resemblances to modern day bryophytes and aquatic macrophytes. Retene, a biomarker conventionally used as a proxy for gymnosperms, was also identified in some extracts. The presence of retene in Middle Ordovician (this work) and Silurian (Romero-Sarmiento et al., 2010) rocks indicates conifers are not the sole source of this compound. <p>Linking biomarkers and palynology has shown to beuseful in the study of early land plants where fossil records are sparse. Molecular and isotopic proxies distinctive of these plants can provide a more complete record of the geographical distribution of early land plants, providing useful information to understand their early evolution. <p>Bird, M.I., Summons, R.E., Gagan, M.K., Roksandic, Z., Dowling, L., Head, J., Fifield, L.K., Cresswell, R.G., Johnson, D.P., 1995. Terrestrial vegetation change inferred from n-alkane δ13C analysis in the marine environment. Geochimica et Cosmochimica Acta 59, 2853-2857. <p>Eglinton, G., Hamilton, R.J., 1967. Leaf epicuticular waxes. Science 156, 1322-1335. <p>Ficken, K.J., Li, B., Swain, D.L., Eglinton, G., 2000. An n-alkane proxy for the sedimentary input of submerged/floating freshwater aquatic macrophytes. Organic Geochemistry 31, 745-749. <p>Hautevelle, Y., Michels, R., Malartre, F., Trouiller, A., 2006. Vascular plant biomarkers as proxies for palaeoflora and palaeoclimatic changes at the Dogger/Malm transition of the Paris Basin (France). Organic Geochemistry 37, 610-625. <p>Kenrick, P., Wellman, C.H., Schneider, H., Edgecombe, G.D., 2012. A timeline for terrestrialization : consequences for the carbon cycle in the Palaeozoic. Philosophical Transactions of the Royal Society B: Biological Sciences 367, 519-536. <p>Romero-Sarmiento, M.F., Riboulleau, A., Vecoli, M., Versteegh, G.J.M., 2010. Occurrence of retene in upper Silurian-lower Devonian sediments from North Africa: origin and implications. Organic Geochemistry 41, 302-306. <p>Rouillard, A., Greenwood, P.F., Grice, K., Skrzypek, G., Dogramaci, S., Turney, C., Grierson, P.F., 2016. Interpreting vegetation change in tropical arid ecosystems from sediment molecular fossils and their stable isotope compositions: a baseline study from the Pilbara region of northwest Australia. Palaeogeography, Palaeoclimatology, Palaeoecology 459, 495-507. <p>Sikes, E.L., Uhle, M.E., Nodder, S.D., Howard, M.E., 2009. Sources of organic matter in a coastal marine environment: Evidence from n-alkanes and their delta13C distributions in the Hauraki Gulf, New Zealand. Marine Chemistry 113, 149-163. <p>Steemans, P., Herisse, A. Le, Melvin, J., Miller, M. a, Paris, F., Verniers, J., Wellman, C.H., 2009. Origin and radiation of the earliest vascular land plants. Science (New York, N.Y.) 324, 353. <p>Strother, P.K., 2016. Systematics and evolutionary significance of some new cryptospores from the Cambrian of eastern Tennessee, USA. Review of Palaeobotany and Palynology 227, 28-41. <p>Wellman, C.H., Gray, J., 2000. The microfossil record of early land plants. Philosophical Transactions of the Royal Society B: Biological Sciences 355, 717-732.

<div>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 net zero emissions, strong, sustainable resources and agriculture sectors, and economic opportunities and social benefits for Australia’s regional and remote communities. The EFTF program, which commenced in 2016, is an eight year, $225m investment by the Australian Government.</div><div>The onshore Canning Basin in Western Australia was the focus of a regional hydrocarbon prospectivity assessment undertaken by the EFTF program dedicated to increasing investment in resource exploration in northern Australia, with the objective being to acquire new data and information about the potential mineral, energy and groundwater resources concealed beneath the surface. As part of this program, significant work has been carried out to deliver pre-competitive data in the region including new seismic acquisition, drilling of a stratigraphic well, and geochemical analysis from historic exploration wells.</div><div>As part of this program, a compilation of the compound-specific isotopic compositions of crude oils from 30 petroleum wells in the Canning Basin have been completed. The samples were analysed in Geoscience Australia’s Isotope and Organic Geochemistry Laboratory and the collated results are released in this report. This report provides additional stable carbon and hydrogen isotopic data to build on the oil-oil correlations previously established by Edwards and Zumberge (2005) and Edwards et al. (2013). This information can be used in future geological programs to determine the origin of the crude oils, and hence increase our understanding of the Larapintine Petroleum Supersystem, as established by Bradshaw (1993) and Bradshaw et al. (1994).</div><div><br></div>

The onshore Canning Basin in Western Australia is the focus of a regional hydrocarbon prospectivity assessment being undertaken by the Exploring for the Future (EFTF) program; an Australian Government initiative dedicated to increasing investment in resource exploration in northern Australia. The four-year program led by Geoscience Australia focusses on the acquisition of new data and information about the potential mineral, energy and groundwater resources concealed beneath the surface in northern Australia and parts of South Australia. As part of this program, significant work has been carried out to deliver new pre-competitive data including new seismic acquisition, drilling of a stratigraphic well, and the geochemical analysis of geological samples recovered from exploration wells. A regional, 872 km long 2D seismic line (18GA-KB1) acquired in 2018 by Geoscience Australia (GA) and the Geological Survey of Western Australia (GSWA), images the Kidson Sub-basin of the Canning Basin. In order to provide a test of geological interpretations made from the Kidson seismic survey, a deep stratigraphic well, Waukarlycarly 1, was drilled in 2019 in partnership between Geoscience Australia (GA) and the Geological Survey of Western Australia (GSWA) in the South West Canning Basin. The Waukarlycarly 1 stratigraphic well was drilled in the Waukarlycarly Embayment, 67 km west of Telfer and provides stratigraphic control for the geology imaged by the Kidson seismic line (Figure 1). The well was drilled to a total drillers depth (TD) of 2680.53 mRT and penetrated a thin Cenozoic cover overlying a Permian fluvial clastic succession that includes glacial diamictite. These siliciclastics unconformably overlie an extremely thick (>1730 m) interpreted Ordovician succession before terminating in low-grade metasediments of Neoproterozoic age. Log characterisation, core analysis, geochronology, petrographic and palaeontological studies have been carried out to characterise the lithology, age and depositional environment of these sediments. As part of this comprehensive analytical program, magnetic susceptibility and bulk density analyses were undertaken by Geoscience Australia on selected rock samples.

Geoscience Australia currently uses two commercial petroleum system modelling software packages, PetroMod https://www.software.slb.com/products/petromod and Zetaware http://www.zetaware.com, to undertake burial and thermal history modelling on wells in Australian sedimentary basins. From the integration of geological (age-based sedimentary packages, uplift and erosional events), petrophysical (porosity, permeability, and thermal conductivity) and thermal (downhole temperature, heat flow, vitrinite reflectance, and Tmax) input data, to name the most significant, a best-fit model of the time-temperature history is generated. Since the transformation of sedimentary organic matter (kerogen) into petroleum (oil and gas) is a chemical reaction, it is governed by chemical kinetics i.e. time and temperature (in the geological setting pressure is of secondary importance). Thus, the use of chemical kinetics associated with a formation-specific, immature potential source rock (where available) from the basin of interest is considered a better practical approach rather than relying on software kinetic defaults, which are generally based on the chemical kinetics determined experimentally on Northern Hemisphere organic matter types. As part of the Australian source rock and fluids atlas project being undertaken by the Energy Systems Group’s Exploring for the Future (EFTF) program, compositional kinetics (1-, 2-, 4- and 14-component (phase) kinetics) were undertaken by GeoS4, Germany. The phase kinetics approach is outlined in Appendix 1. This report provides the compositional kinetics for potential source rocks from the Ordovician Goldwyer (Dapingian–Darriwilian) Formation and the Bongabinni (Sandbian) Formation, Carribuddy Group, Canning Basin, Western Australia.

<div>The Canning Basin is a prospective hydrocarbon frontier basin and is unusual for having limited offshore seismic and well data in comparison with its onshore extent. In this study, seismic mapping was conducted to better resolve the continuity of 13 key stratigraphic units from onshore to offshore to delineate prospective offshore hydrocarbon-bearing units, and better understand the distribution of mafic igneous units that can compartmentalise migration pathways and influence heat flow. The offshore Canning Basin strata are poorly constrained in six wells with limited seismic coverage; hence data availability was bolstered by integrating data from the onshore portion of the basin and adjacent basins into a single 3D seismic stratigraphic model. This model integrates over 10 000 km of historical 2D seismic data and 23 exploration wells to allow mapping of key stratal surfaces. Mapped seismic horizons were used to construct isochores and regional cross-sections. Seven of the 13 units were mapped offshore for the first time, revealing that the onshore and offshore stratigraphy are similar, albeit with some minor differences, and mafic igneous units are more interconnected than previously documented whereby they may constitute a mafic magmatic province. These basin-scale maps provide a framework for future research and resource exploration in the Canning Basin. To better understand the basin’s geological evolution, tectonic history and petroleum prospectivity, additional well data are needed in the offshore Canning Basin where Ordovician strata have yet to be sampled.</div><div><br></div><div>C. T. G. Yule, J. Daniell, D. S. Edwards, N. Rollet & E. M. Roberts&nbsp;(2023).&nbsp;Reconciling the onshore/offshore stratigraphy of the Canning Basin and implications for petroleum prospectivity,&nbsp;Australian Journal of Earth Sciences,&nbsp;DOI:&nbsp;10.1080/08120099.2023.2194945</div> Appeared in Australian Journal of Earth Sciences Pages 691-715, Volume 70, 2023 - Issue 5.