Down and out in Gippsland: using potential fields to look deeper and wider for new hydrocarbons

David Hugh Moore, David Wong

Research output: Chapter in Book/Report/Conference proceedingConference PaperResearchpeer-review

Abstract

Athough aeromagnetic interpretations are not usual aids in detailed assessments of hydrocarbon provinces, they can provide insights into the deep stmctures that often control the distribution of hydrocarbons within the basin fill. This paper summarises an interpretation derived from integrating the 1999 AGSO aeromagnetic data with pre-existing seismic and other data.

The interpretation divides the Gippsland Basin into three zones that link basement strncture, basin development and ultimately, the locations of hydrocarbons. In the west, the α Zone has a basement of the Selwyn Block, the extension of the Tasmanian craton into Victoria. Its eastern edge is just east of the Strzelecki Ranges. No significant oil or gas discoveries have been made in the relatively thin sequence preserved over the Selwyn Block. This zone probably also includes the southern edge of the basin.

Typical lower Palaeozoic Lachlan Fold Belt rocks floor the β Zone, the 'offshore' Gippsland Basin and the easternmost parts of the onshore section. Almost all of the 4.1 BBL of oil and 13 TCF of gas found in the basin have come from this region. The 15 km thick basin sequence includes both marine and terrestrial rocks. Many major hydrocarbon accumulations cluster on the edges of a major magnetic low. suggesting a Palaeozoic innuence on their location.

The γ Zone is mostly in the deep water in and around the Bass Canyon. Sole and Basker-Manta are on the zone edges, but some seemingly prospective parts have not been drill tested and have only limited seismic cover. The Lachlan Fold Belt basement is overlain by a possible Permo-Triassic sequence. In the Eastern Graben, sediment thickness reaches 15 km, including about 5 km of Cretaceous and early Tertiary Latrobe Siliciclastics and Golden Beach Subgroup, overlain by up to 2 km of late Cainozoic Seaspray Group. Fluids are presently venting from its eastern edge.
Original languageEnglish
Title of host publicationEastern Australian Basins Symposium
EditorsKevin Hill, Thomas Bernecker
PublisherPetroleum Exploration Society of Australia (PESA)
Pages363-371
ISBN (Electronic)1 875776 87 7
Publication statusPublished - 2001
Externally publishedYes

Publication series

NameSpecial Publication

Keywords

  • Gippsland Basin
  • Victoria
  • Hydrocarbon exploration
  • Potential field interpretation

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