Australia has significant gas resources capable of meeting the needs of domestic and international consumers for decades. Commercial viability of the resource depends on a number of factors such as geology, infrastructure, resource quality, and water depth. Further exploration is required to bring on Australia's lowest cost gas resources.

Animation demonstrating how fraccing is used in Coal Seam Gas (CSG) extraction.

A major concern for regulators and the public with geologically storage of gas is the potential for the migration of gas (e.g. CO2) via a leaky fault or well into potable groundwater supplies. Given sufficient CO2, an immediate effect on groundwater would be a decrease in pH which could lead to accelerated weathering, an increase in alkalinity and the release of major and minor ions. Laboratory and core studies have demonstrated that on contact with CO2 heavy metals can be released under low pH and high CO2 conditions (particularly Pd, Ni and Cr). There is also a concern that trace organic contaminants could be mobilised due to the high solubility of many organics in supercritical CO2. These scenarios could potentially occur under a high CO2 leakage event but a small leak might be barely perceptible yet could provide an important early warning for a subsequent and more substantial impact. Different approaches are required for the detection and quantification of these low level leaks and are the subject of this paper. A 3 year groundwater survey was recently completed in the Surat Basin, which forms part of the Triassic-Cretaceous, Great Artesian Basin (GAB) aquifer sequence. In addition to a comprehensive water and isotopic analysis of samples from groundwater wells, gases were collected from groundwater samples and analysed for composition, '13CCO2, '13CCH4 and '2HCH4. Methane is prevalent in the major aquifers in the Surat Basin (e.g. Mooga, Gubbermunda and Hutton sandstones) and is invariably associated with a bacterial (methanogenic) carbonate reduction source, evident from its isotopic signature ('13CCH4 ~ -70', '2HCH4 ~ 220'). In addition to methane and low levels of CO2, trace levels of ethane are often detected.

The study provides a comprehensive analysis of the natural gases from the Bonaparte, Browse, Carnarvon and Perth basins (in 4 modules). Geochemical analyses for the molecular and carbon isotope composition were performed on 96 gases and associated liquids, and these data are interpreted in a geological context. Additional non-exclusive data from the AGSO database have been used for correlation/interpretation purposes. The study addresses factors influencing the composition of gaseous and other light hydrocarbons in natural gas (and associated oil accumulations) including; - primary source and maturity controls, - secondary alteration processes, e.g. migration fractionation, water washing, biodegradation, and - multiple charge histories, including deep dry gas inputs.

The Clarence-Moreton and the Surat basins in Queensland and northern New South Wales contain the coal-bearing sedimentary sequences of the Jurassic Walloon Coal Measures, composed of up to approximately 600 m of mudstone, siltstone, sandstone and coal. In recent years, the intensification of exploration for coal seam gas (CSG) resources within both basins has led to concerns that the depressurisation associated with future resource development may cause adverse impacts on water resources in adjacent aquifers. In order to identify the most suitable tracers to study groundwater recharge and flow patterns within the Walloon Coal Measures and their degree of connectivity with over- or underlying formations, samples were collected from the Walloon Coal Measures and adjacent aquifers in the northern Clarence-Moreton Basin and eastern Surat Basin, and analysed for a wide range of hydrochemical and isotopic parameters. Parameters that were analysed include major ion chemistry, -13C-DIC, -18O, 87Sr/86Sr, Rare Earth Elements (REE), 14C, -2H and -13C of CH4 as well as concentrations of dissolved gases (including methane). Dissolved methane concentrations range from below the reporting limit (10 µg/L) to approximately 50 mg/L in groundwaters of the Walloon Coal Measures. However, the high degree of spatial variability of methane concentrations highlights the general complexity of recharge and groundwater flow processes, especially in the Laidley Sub-Basin of the Clarence-Moreton Basin, where numerous volcanic cones penetrate the Walloon Coal Measures and may form pathways for preferential recharge to the Walloon Coal Measures. Interestingly, dissolved methane was also measured in other sedimentary bedrock units and in alluvial aquifers in areas where no previous CSG exploration or development has occurred, highlighting the natural presence of methane in different aquifers. Radiocarbon ages of Walloon Coal Measure groundwaters are also highly variable, ranging from approximately 2000 yrs BP to >40000 yrs BP. While groundwaters sampled in close proximity to the east and west of the Great Dividing Range are mostly young, suggesting that recharge to the Walloon Coal Measures through the basalts of the Great Dividing Range occurs here, there are otherwise no clearly discernable spatial patterns and no strong correlations with depth or distance along inferred flow paths in the Clarence-Moreton Basin. In contrast to this strong spatial variability of methane concentrations and groundwater ages, REE and 87Sr/86Sr isotope ratios of Walloon Coal Measures groundwaters appear to be very uniform and clearly distinct from groundwaters contained in other bedrock units. This difference is attributed to the different source material of the Walloon Coal Measures (mostly basalts in comparison to other bedrock units which are mostly composed of mineralogical more variable Paleozoic basement rocks of the New England Orogen). This study suggests that REE and 87Sr/86Sr ratios may be a suitable tracer to study hydraulic connectivity of the Walloon Coal Measures with over- or underlying aquifers. In addition, this study also highlights the need to conduct detailed water chemistry and isotope baseline studies prior to the development of coal seam gas resources in order to differentiate between natural background values of methane and potential impacts of coal seam gas development.

This Oil and Gas Resources of Australia 2010 publication is the successor to Oil and Gas Resources of Australia 2009 and continues as the definitive reference on exploration, development and production of Australia's petroleum resources. The tables describe: - wells drilled - seismic surveys - petroleum discoveries - petroleum reserves - production and development, including forecasts of crude oil and condensate and a listing of offshore facilities

From the beginning of petroleum exploration in the Perth Basin, the importance of the Early Triassic marine Kockatea Shale was recognised as the principal source for liquid petroleum in the onshore northern Perth Basin (Powell and McKirdy, 1976). Thomas and Barber (2004) constrained the effective source rock to a Early Triassic, middle Sapropelic Interval in the Hovea Member of the lower Kockatea Shale. In addition, Jurassic and Permian sourced-oils (Summons et al., 1995) demonstrate local effective non-Kockatea source rocks. However, evidence for multiple effective gas source rocks is limited. This study utilizes the molecular composition and carbon and hydrogen isotopic compositions of 34 natural gases from the Perth Basin, extending the previous study (Boreham et al., 2001) to the offshore and includes hydrogen isotopes and gases. It shows the existence of Jurassic to Permain gas systems in the Perth Basin.

Gas is a vital and growing part of the Australian and global energy mix. The gas industry is being transformed due to changes in markets and technology that are bringing new gas resources into play. This report builds on the Australian Energy Resource Assessment (AERA) was first published in March 2010 as a supporting document to the Energy White Paper process. The AERA (Geoscience Australia and ABARE, 2010) is a national prospectus for energy resources. It examined Australia's identified and potential energy resources ranging from fossil fuels and uranium to renewable sources. In the two years following the release of the AERA there have been significant changes in gas resources and within the gas market. This report provides an assessment of Australia's gas resources in 2012 and has been released to contribute to the final phase of the Energy White Paper process. The report documents the growth of gas resources and new projects that underpin an increasing role for gas both in Australia and internationally. For example coal seam gas (CSG) reserves have doubled since 2010 and three CSG/liquid natural gas (LNG) projects are now under construction, In addition, major new offshore conventional gas projects have been committed and commenced construction, including Ichthys in the Browse Basin and Prelude, the world's first floating LNG project. And Australia's third export LNG project, Pluto, has commenced operations.

<div>Australia’s Energy Commodity Resources (AECR) provides estimates of Australia’s energy commodity reserves, resources, and production as at the end of 2021. The 2023 edition of AECR also includes previously unpublished energy commodity resource estimates data compiled by Geoscience Australia for the 2021 reporting period. The AECR energy commodity resource estimates are based primarily on published open file data and aggregated (de identified) confidential data. The assessment provides a baseline for the production and remaining recoverable resources of gas, oil, coal, uranium and thorium in Australia, and the global significance of our nation’s energy commodity resources.</div>

Map of Australia showing the distribution of black coal, brown coal and Coal Seam Gas bearing basins overlain by prohibited areas. This map and enlargements of the Sydney, Bowen/Surat and Arckaringa basins were provided to DoFD as part advice regarding CSG exploration and coal extraction on commonwealth lands. These maps and their subsets are in 'DRAFT' form and are for internal use only.