Victoria's Sedimentary Basins
Victoria has three sedimentary basins of Jurassic to Cenozoic age with either proven or potential oil and gas resources. These are the Gippsland, Otway and Murray basins.
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The Gippsland and Otway basins are located onshore and offshore of Victoria’s southern coastline. The Bass Basin lies in Commonwealth and Tasmanian waters.
The three basins developed during the Jurassic to Early Cretaceous separation of the Australian continent from Antarctica. They were infilled with a thick sequence of volcanoclastic sediments, which gave way to terrestrial and later, marine siliciclastics in the Late Cretaceous. During the Palaeocene to Eocene, vast amounts of organic-rich sediments accumulated in lower coastal plain and deltaic environments, leading to the formation of thick coal seams, particularly in the Gippsland Basin.
In the mid-Oligocene, marine conditions were established along the southern Australian margin, with cool-water carbonate sedimentation dominating the shelfal areas. Tectonic compression events in the Neogene inverted many of the early-formed basin structures and created the majority of the hydrocarbon traps in the Gippsland Basin. In the Otway Basin, trap styles range from early-formed, fault-dependent structures to later inversion-related anticlines.
The Petroleum Atlas of Victoria (2001), provides an overview of the regional geological and geophysical characteristics of the Otway and Gippsland basins.
Geoscience Australia provides information about petroleum basins nationally.
The offshore Gippsland Basin has been the source of significant oil and gas production since the late 1960s. Conventional petroleum resources have been discovered in structural and combined structural and stratigraphic traps, mostly within Late Cretaceous to Eocene clastic sequences.
A total of 26,089 petajoules* (PJ) of liquids and 9,120 PJ of gas have been produced up to 2014 from the Gippsland Basin.
Oil and Gas Resources of Victoria – Gippsland Basin contains data for individual fields, structure maps and geological cross sections.
The Otway Basin covers approximately 150,000km, extending along the southern margin of Victoria and South Australia to the north-west of Tasmania. Eighty per cent of the basin is offshore.
The first wells in the Victorian part of the Otway Basin were drilled in the 1920s to 1940s in the Anglesea and Torquay areas. The Otway Basin has been the source of a number of important gas discoveries, particularly in the offshore Shipwreck Trough and the onshore Port Campbell Embayment, with 850 PJ of gas produced from the basin in total.
Gas Resources of the Otway Basin in Victoria (2002) provides an overview of the Victorian Otway Basin and its petroleum resources, including the geology of the basin, technical data and field production histories.
The Murray Basin extends across three states: South Australia, New South Wales and Victoria. In Victoria, there has been limited exploration specifically targeting petroleum in the Murray Basin and there have been no significant hydrocarbon indications identified to date.
The following Murray Basin reports are available from the Online Store:
- The Geology & Prospectivity of the Southern Margin of the Murray Basin (1995)
- A Preliminary Appraisal of the Pre-Tertiary Infrabasins Beneath the Murray Basin, Northwestern Victoria (1995).
*1 petajoule = 277.78 million kWh or approximately 23,884.59 tonnes of oil equivalent