Publication Name: New Petroleum Symposium 1993
Authors: I.R. Mortimore, T.P. Bray and G.J. Daneel
Date Published: December 1993
Number of Pages: 33
Reference Type: Magazine Article
Abstract:
The Clarence-Moreton Basin straddles the New South Wales/Queensland border covering an area of 46 000 sq km of which approximately one third is within New South Wales. The thick sequence (up to 3500 m) of Late Triassic to Early Cretaceous sediments has long been recognised as possessing a potential for commercial hydrocarbon discoveries, a potential which to date has not been realised.Through the 1980s/ early 1990s Government authorities and explorers have advanced their understanding of the controls on hydrocarbon entrapment in the Clarence-Moreton Basin and the interplay of these controls which must exist for success in exploration of the Basin.
The Clarence-Moreton Basin is considered to have been part of a much larger basin encompassing the Surat and Maryborough Basins. Its singular identity became established in Early Cretaceous as half graben development took place as a result of lithospheric extension which preceded the opening of the Tasman Sea. The latter event saw compression and structural inversion during the Albian-Cenomanian time and was accompanied by maximum heat flow at around 100 Ma to 80 Ma which resulted in the upper Oarence-Moreton sediments
entering into the oil generative stage and deeper sediments the gas generative stage. The recognition of the relative timing of these events has enhanced the probability of success in exploration of the Basin.
The Koukandowie Formation and sandstones within the Walloon Coal Measures are considered to possess the best exploration opportunities for liquid hydrocarbons probably sourced, sealed and reservoired intra-formationally while a deeper basal Bundamba sandstone unit offers good potential for gas accumulations sourced by the still deeper Triassic Ipswich and Nymbodia Coal Measures. Oil and gas generative stages can be identified in the context of a tectonic framework considered favourable to the accumulation of hydrocarbons.