An assessment of tight, shale and deep coal gas prospectivity of the Cooper Basin has been undertaken as part of the Australian Government’s Geological and Bioregional Assessment Program. This aims to both encourage exploration and understand the potential impacts of resource development on water and the environment. This appendix presents a review of the regional petroleum prospectivity, its exploration, and the characterisation and analysis of shale, deep coal and tight gas in Carboniferous–Permian Gidgealpa Group of the Cooper Basin. The Cooper Basin is Australia’s premier onshore conventional hydrocarbon-producing province providing domestic gas for the East Coast Gas Market. As of December 2014, the Cooper and Eromanga basins have produced 6.54 Tcf of gas since 1969. The basins contain 256 gas fields as well as 166 oil fields that are currently in production. Gas is predominantly reservoired in the Cooper Basin, whereas the overlying Eromanga Basin hosts mainly oil. Hydrocarbon shows are found in the reservoir units throughout the succession. Recently, exploration targeting a range of unconventional plays has gained momentum. Unconventional play types within the mainly Permian Gidgealpa Group include shale gas associated with the Patchawarra Formation and the Roseneath and Murteree shales, tight and deep coal gas accumulations within the Toolachee, Epsilon and Patchawarra formations and additional tight gas plays in the Daralingie Formation and Tirrawarra Sandstone. To date, at least 80 wells have been drilled to test shale, tight and deep coal gas plays. Given the basin’s existing conventional production, and its processing and pipeline infrastructure, these plays are well placed to be rapidly commercialised, should exploration be successful. A prospectivity confidence mapping workflow was developed to evaluate the regional distribution of key unconventional gas plays within the Gidgealpa Group. For each play type, key physical properties were identified and characterised. The specific physical properties evaluated include formation extents, source rock properties (net thickness, TOC, quality and thermal maturity), reservoir characteristics (porosity, permeability, gas saturation and brittleness), regional stress regime and overpressure. Parameters for mappable physical properties were individually classified to assign prospectivity rankings. Individual properties were then multiplied together produce formation and play-specific prospectivity confidence maps. Non-mappable criteria were not integrated into the prospectivity mapping but were used to better understand the geological characteristics of the formations. Overall, both source and reservoir characteristics were found to be moderately to highly favourable for all play types assessed. Abundant source rocks are present in the Gidgealpa Group across the Cooper Basin. The Toolachee and Patchawarra formations are the richest, thickest and most extensive source rocks, with good to excellent source potential across their entire formation extents. Net shale, coal and sand thicknesses also demonstrate an abundance of potential reservoir units in the Gidgealpa Group across the basin. The predominantly fluvial Toolachee Formation is thickest in the Windorah Trough and Ullenbury Depression. Average effective porosity for assessed tight gas plays ranges from 6.7 % in the fluvio-deltaic to lacustrine Epsilon Formation to 7.8% in the Toolachee Formation. Based on an assessment of the brittleness of the shales and coaly shales, the Patchawarra Formation appears to be most favourable for hydraulic stimulation with an average Brittleness Index of 0.695, indicative of brittle rocks. This compares to the less brittle lacustrine Roseneath and Murteree shales have brittleness indices of 0.343 and 0.374, respectively. As-received total gas content is favourable, with averages ranging from 1.3 scc/g in the Patchawarra Formation to 1.6 scc/g for the Murteree Shale. The regional stress regime has an approximately east-west oriented maximum horizontal stress azimuth, resulting in predominantly strike-slip faulting to reverse faulting, depending on the depth, lithology and proximity of structures, e.g. GMI ridge. Significant overpressure is present at depths greater than 2800 m, especially in the Nappamerri and Patchawarra troughs. Overpressures are generally constrained to the Gidgealpa Group, with the Toolachee Formation being the youngest formation in which significant overpressure has been achieved. Based on a review of the geomechanical properties of the Cooper Basin sedimentary succession, it was found that stress variations within and between lithologies and formations are likely to provide natural barriers to fracture propagation between the gas saturated Permian sediments and the overlying Eromanga Basin. Prospectivity confidence maps were generated for six individual shale and deep coal plays and one combined tight gas play across the Gidgealpa Group. Comparison with key wells targeting shale, tight and deep coal gas plays, indicates that the prospectivity confidence mapping results are largely consistent with exploration activity to-date, with the highest prospectivity confidence for tight, shale and deep coal gas plays mapped in the Nappamerri, Patchawarra, Windorah, Allunga and Wooloo troughs and the southern Ullenbury Depression. Consequently, there is more confidence in the resultant maps in the southern Cooper Basin as more data was available here. Prospectivity confidence maps are relative, therefore a high prospectivity confidence does not equate to 100 % chance of success for a particular formation or play. The outputs of this regional prospectivity assessment identify areas warranting more detailed data collection and exploration and the assessment of potential impacts of resource development on water and the environment. The results also have the potential to encourage further exploration investment in underexplored regions of the Cooper Basin.

<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

<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.