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.

Laboratory results for fluid inclusion gas analysis in GA's Isotope and Organic Geochemistry Laboratory under GSWA Approval G004119

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.

This report presents the results of scanning electron microscopy (SEM) and mercury porosimetry analyses on 1 whole core sample from the GSWA Waukarlycarly 1 stratigraphic well drilled in the Canning Basin. The well was drilled as part of a co-funded collaboration between Geoscience Australia (GA) and the Geological Survey of Western Australia (GSWA) aimed at gathering new subsurface data on the potential mineral, energy and groundwater resources in the southern Canning Basin. The collaboration resulted in the acquisition of the Kidson Deep Crustal Seismic Reflection Survey in 2018; and the drilling of deep stratigraphic well GSWA Waukarlycarly 1, located along the Kidson Sub-basin seismic line within the Waukarlycarly Embayment in 2019 (Figure 1). GSWA Waukarlycarly 1 reached a total depth of 2680.53 m at the end of November 2019 and was continuously cored through the entire Canning Basin stratigraphy. Coring was complemented by the acquisition of a standard suite of wireline logs and a vertical seismic profile. The work presented in this report constitutes part of the post well data acquisition. The purpose of the SEM analysis was to determine mineralogy and textural relationships between grains, verify the presence of organic material at the micro-scale, document i) the presence of diagenetic alterations to the detrital mineral assemblage and ii) eventual distribution of visible pores. Additionally, mercury injection capillary pressure porosimetry (MICP) was used to assess interconnected porosityand pore size distribution.

A large proportion of Australia’s onshore sedimentary basins remain exploration frontiers. Industry interest in these basins has recently increased due to the global and domestic energy demand, and the growth in unconventional hydrocarbon exploration. In 2016, Geoscience Australia released an assessment of eight central Australian basins that summarised the current status of geoscientific knowledge and petroleum exploration, and the key questions, for each basin. This publication provides a comprehensive assessment of the geology, petroleum systems, exploration status and data coverage for additional three basins in western and central Australia: the Canning, Perth and Officer basins. The Perth and Canning basins are producing petroleum basins, however, they may be regarded as frontier basins for unconventional hydrocarbon resources. The Officer Basin is a large, unproven frontier basin which has seen little exploration to date.

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.

<p>The Paleozoic Canning Basin is a large (~720 000 km2) frontier province with several proven petroleum systems. Recent oil production from the Ungani field on the southern edge of the Fitzroy Trough has boosted the small-scale production of crude oil and gas discovered in the 1980s on the Lennard Shelf and flanking terraces (e.g. Blina, Boundary, Lloyd, Sundown, West Kora, West Terrace). Determining the paleo-depositional environments within the epicontinental seaway is essential to characterise source rock formation and distribution, and hence assist future exploration strategies.</p> <p>This study of diagnostic biomarker hydrocarbons derived from the coloured carotenoid pigments of photosynthetic organisms (including plants, algae, cyanobacteria and photosynthetic bacteria) was designed to extend the geochemistry of the Ordovician-, Middle to Late Devonian- and Early Carboniferous-sourced oils of the basin published by Edwards et al. (2013) and Spaak et al. (2017, 2018), and implemented by GeoMark Research. The focus was to clarify the paleo-depositional environment of their marine source rocks and the extent of water stratification, and to expand upon the diversity of the contributing organic matter. The oils on the Lennard Shelf and those on the southern side of the Fitzroy Trough (e.g. Ungani and Dodonea 1) preserve a diverse range of biomarkers, including both saturated and aromatic C40 carotenoid-derived compounds (Figure 1) due to minimal secondary alteration. All analysed oils contain the saturated biomarker beta-carotane, derived from algae and cyanobacteria that flourish in sunlit oxygenated water. In addition, the oils also contain aromatic carotenoids produced by photosynthetic green sulphur bacteria, which inhabit the photic zone of euxinic water columns (e.g. Summons & Powell, 1986; French et al., 2015). Paleorenieratane is the dominant C40 aromatic carotenoid in the Ordovician (Dodonea 1, Pictor) and Late Devonian-sourced oils (Blina 1, 2, 4 and Janpam North 1; Figure 1). Oils on the Lennard Shelf generated by Lower Carboniferous source rocks have variable distributions of carotenoids with isorenieratane either in similar concentration to paleorenieratane (Point Torment 1, Sundown 2), absent (West Kora 1) or, in the case of Terrace 1, in lower abundance relative to paleorenieratane. Paleorenieratane, isorenieratane and renieratane are absent in oils from Wattle 1 ST1 and Mirbelia 1. Chlorobactane, also derived from green sulphur bacteria, is present in many of the analysed oils (and is the dominant peak in Point Torment 1), whereas okenane (derived from purple sulphur bacteria) was not detected. The exception is the Late Ordovician (Sandbian) Cudalgarra 1 oil that contains a low concentration of okenane, and in which isorenieratane predominates over paleorenieratane. The aromatic carotenoid distribution in oil from Ungani 2 is similar to those from both Terrace 1 and Blina (Figure 1).</p> <p>The association of these saturated and aromatic carotenoids in Paleozoic Canning Basin oils provides evidence for long-term restricted circulation and the development of shallow chemoclines in an epicontinental seaway centred along the Fitzroy Trough and Gregory Sub-basin in which oxygenated surface water frequently overlaid deeper, anoxic, sulphidic (euxinic) water also within the photic zone.</p> <p>REFERENCES Edwards, D.S., Boreham, C.J., Chen, J., Grosjean, E., Mory, A.J., Sohn, J., Zumberge, J.E., 2013. Stable carbon and hydrogen isotopic compositions of Paleozoic marine crude oils from the Canning Basin: comparison with other west Australian crude oils. In: Keep, M., Moss, S. (Editors), The Sedimentary Basins of Western Australia IV, Perth, WA. Edwards, P., Streitberg, E., 2013. Have we deciphered the Canning? Discovery of the Ungani oil field. In: Keep, M., Moss, S. (Editors), The Sedimentary Basins of Western Australia IV, Perth, WA. French, K.L., Rocher, D., Zumberge, J.E., Summons, R.E., 2015. Assessing the distribution of sedimentary C40 carotenoids through time. Geobiology 13, 139–151, 10.1111/gbi.12126. Spaak, G., Edwards, D.S., Allen, H.J., Grotheer, H., Summons, R.E., Coolen, M.J.L., Grice, K., 2018. Extent and persistence of photic zone euxinia in Middle–Late Devonian seas – insights from the Canning Basin and implications for petroleum source rock formation. Marine and Petroleum Geology, 93, 33–56. Spaak, G., Edwards, D.S., Foster, C.B., Pagès, A., Summons, R.E., Sherwood, N., Grice, K., 2017. Environmental conditions and microbial community structure during the Great Ordovician Biodiversification Event; a multi-disciplinary study from the Canning Basin, Western Australia. Global and Planetary Change, 159, 93–112. Summons, R.E., Powell, T.G., 1986. Chlorobiaceae in Palaeozoic seas revealed by biological markers, isotopes and geology. Nature 319, 763–765.</p>

Although the Canning Basin has yielded minor gas and oil within conventional and unconventional reservoirs, the relatively limited geological data available in this under-explored basin hinder a thorough assessment of its hydrocarbon potential. Knowledge of the Paleozoic Larapintine Petroleum Supersystem is restricted by the scarcity of samples, especially recovered natural gases, which are limited to those collected from recent exploration successes in Ordovician and Permo-Carboniferous successions along the margins of the Fitzroy Trough and Broome Platform. To address this shortcoming, gases trapped within fluid inclusions were analysed from 121 Ordovician to Permian rock samples (encompassing cores, sidewall cores and cuttings) from 70 exploration wells with elevated mud gas readings. The molecular and carbon isotopic compositions of these gases have been integrated with gas compositions derived from open-file sources and recovered gases analysed by Geoscience Australia. Fluid inclusion C1–C5 hydrocarbon gases record a snapshot of the hydrocarbon generation history. Where fluid inclusion gases and recovered gases show similar carbon isotopes, a simple filling history is likely; where they differ, a multicharge history is evident. Since some fluid inclusion gases fall outside the carbon isotopic range of recovered gases, previously unidentified gas systems may have operated in the Canning Basin. Interestingly, the carbon isotopes of the fluid-inclusion heavy wet gases converge with the carbon isotopes of the light oil liquids, indicating potential for gas–oil correlation. A regional geochemical database incorporating these analyses underpins our re-evaluation of gas systems and gas–gas correlations across the basin. <b>Citation:</b> Boreham, C.J., Edwards, D.S., Sohn, J.H., Palatty, P., Chen, J.H. and Mory, A.J., 2020. Gas systems in the onshore Canning Basin as revealed by gas trapped in fluid inclusions. 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.

A regional hydrocarbon prospectivity study was undertaken in the onshore Canning Basin in Western Australia as part of the Exploring for the Future (EFTF) program, an Australian Government initiative dedicated to driving investment in resource exploration. 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, Barnicarndy 1, was drilled in 2019 in a partnership between Geoscience Australia (GA) and the Geological Survey of Western Australia (GSWA) in the Barnicarndy Graben, 67 km west of Telfer, in the southwest Canning Basin. Drilling recovered about 2100 m of continuous core from 580 mRT to the driller’s total depth (TD) of 2680.53 mRT. An extensive analytical program was carried out to characterise the lithology, age and depositional environment of these sediments. This data release presents organic geochemical analyses undertaken on rock extracts obtained from cores selected from the Barnicarndy 1 well. The molecular and stable isotope data carbon and hydrogen will be used to understand the type of organic matter being preserved, the depositional facies and thermal maturity of the Lower Ordovician sedimentary rocks penetrated in this well. This information provides complementary information to other datasets including organic petrological and palynological studies.

This Geoscience Australia Record reports the findings of the Canning Basin Petroleum Systems Modelling Project. The southern, frontier portions of the Canning Basin have numerous potential hydrocarbon play opportunities, in particular unconventional gas plays, which remain untested. Of particular interest are Ordovician-aged petroleum systems. Geoscience Australia in collaboration with the Geological Survey of Western Australia acquired an 872 km long 2D seismic line across the south and south-west Canning Basin in 2018, and drilled the 2680 m stratigraphic hole Barnicarndy 1 in the Barnicarndy Graben to further develop the understanding of hydrocarbon prospectivity in these frontier regions. As part of the Exploring for the Future program Geoscience Australia contracted GNS Science to construct ten 1D petroleum systems models and one 2D model across the frontier southern parts of the basin. The aim was to combine interpretation of the newly acquired seismic data with interpretation of legacy and new well data, in particular organic geochemical data, to improve the understanding of the burial and thermal history, trap formation, generation and migration of hydrocarbons in the southern, frontier parts of the Canning Basin. This Record is a compilation of the work completed by GNS Science International Limited and the reports containing new data collected and analyzed relevant to the petroleum systems modelling.