VIMP Report 57 - Geology and prospectivity of the western Victorian Voluta Trough, Otway Basin for the 1998 Acreage Release
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Product description:Download The downloadable version of this report is supplied in PDF format. Executive Summary The Commonwealth of Australia has invited applications for six exploration areas in the offshore Otway Basin in Victoria and South Australia. To coincide with this release, the Victorian Government has also released four blocks within the three mile coastal zone or “territorial seas”. This report has been produced to assess the prospectivity of the westernmost block in the offshore Victorian Otway Basin, V98-5 and the adjacent block within the territorial seas, 98O-1(V). Only four wells have been drilled in the area since 1967. All were plugged and abandoned with only two producing minor gas shows. Breaksea Reef-1, immediately west of the study area, intersected significant oil shows and a possible oil column in tight sandstones of the Waare Formation. At a glance, the Voluta Trough appears less prospective than the adjacent Mussel Platform. The highly permeable sandstones of the Waarre Formation which form the reservoir at the LaBella and Minerva gas fields are deeply buried in the Voluta Trough, and in the few areas where it has been intersected, porosity and pemeability is significantly diminished. In addition the oil prone source intervals of the lower Eumeralla Formation are also deeply buried and are gas mature throughout most of the Voluta Trough. This evaluation of the Voluta Trough, carried out in the Basin Studies Group of Minerals and Petroleum Victoria demonstrates that alternative untested plays are present in the Voluta Trough. These include Santonian-Campanian delta front sandstones with excellent reservoir potential. Large prospective Middle Eocene erosional remnants, with upper delta plain sandstones also provide targets with potentially excellent reservoirs. An oil-prone petroleum system based on Late Cretaceous carbonaceous mudstones and coals is also recognised. These units are oil mature through most of the study area. The validity of the potential petroleum system is supported by the presence of the interpreted oil column at Breaksea Reef-1. There is little doubt that the study area is high risk, but the upside potential is believed to be considerable. Several plays are discussed in this report, the majority of which are untested. Furthermore, the Victorian Otway Basin is well located for access to infrastructure and markets to minimise the costs of exploration and development. Gas markets are expected to significantly increase on the eastern seaboard of Australia during the mid-term. Bibliographic reference Lavin, C.J. 1998. Geology and Prospectivity of the western Victorian Voluta Trough—Otway Basin for the 1998 Acreage Release. Victorian Initiative for Minerals and Petroleum Report 57. Department of Natural Resources and Environment. | ||||||
