GEOCHEMICAL CHARACTERISTICS OF AUSTRALIA'S SOUTHERN MARGIN PETROLEUM SYSTEMS

Abstract

The hydrocarbons discovered to date on the southern margin of Australia have been assigned to the Austral Petroleum Supersystem based on the age of their source rocks and common tectonic history. Modelling of the source facies distribution within this supersystem using tectonic, climatic and geographic history of the southern margin basins, suggests the presence of a variety of source rocks deposited in saline playa lakes, fluvial, lacustrine, deltaic and anoxic marine environments.Testing of the palaeogeographic model using geochemical characteristics of liquid hydrocarbons confirms the three-fold subdivision (Al, A2 and A3) of the Austral Petroleum Supersystem.Bass Basin oils are assigned to the Austral 3, Eastern View Petroleum System. The presence of oleanane in the biomarker assemblages of these oils, together with their negatively sloping, heavy, isotopic profiles, indicate derivation from Upper Cretaceous-Tertiary fluvio–deltaic source facies.In the eastern Otway Basin, oils of the Austral 2, Eumeralla Petroleum System are sourced by Lower Cretaceous (Aptian–Albian) coaly facies. Oil shows reservoired in the Wigunda Formation at Greenly-1 in the Duntroon Basin are possibly sourced from the Borda Formation and are assigned to the Austral 2, Borda Petroleum System.In the western Otway, Duntroon and Bight basins, a lack of definitive oil-source rock correlations precludes the identification of individual Austral 1 petroleum systems.

Australasian asphaltite strandings: Their origin reviewed in light of the effects of weathering and biodegradation on their biomarker and isotopic profiles

“…3). Accordingly, euxinic marine sediments have been identified in several of the corresponding Australian depocentres, possibly recording the Cenomanian-Turonian OAE2 (Bonarelli Event) and shorter-lived late Albian oceanic anoxic subevent OAE 1d (Breistroffer Event) (Edwards et al, 1999;Boreham et al, 2001;Struckmeyer et al, 2001;Boreham, 2008;Totterdell et al, 2008). Boult et al (2005) proposed seafloor seepage of tar as the likely source for the southern Australian asphaltites whereas Logan et al (2010), expanding upon one of the hypotheses of Edwards et al (1998), favoured the idea that they were the end result of oil slick mousse stabilising at the ocean surface prior to stranding.…”

Evaluation of organic matters, hydrocarbon potential and thermal maturity of source rocks based on geochemical and statistical methods: Case study of source rocks in Ras Gharib oilfield, central Gulf of Suez, Egypt

“…8), highly negative correlation with oxygen index and no correlation between TOC and Tmax (Fig. 8) and PI indicate that the maturity of source rocks is independent of the amount of organic matter [23]. Highly positive correlation between S1 and S2 (Fig.…”

“…A hierarchical tree diagram, called a dendrogram on SPSS, can be produced to show the linkage points. The clusters are linked at increasing levels of dissimilarity [23].…”

Seafloor features and fluid migration in the Capel and Faust basins, offshore eastern Australia

“…Coaly and lacustrine potential source rocks may also occur in the Syn-rift 1 and Syn-rift 2 successions Hashimoto et al, 2010). Cretaceous coals are a proven source to producing fields in the Otway (Edwards et al, 1999;Boreham et al, 2004) and Gippsland (Rahmanian et al, 1990;Moore et al, 1992) basins in southeastern Australia, and in the Taranaki Basin (King and Thrasher, 1996;Uruski, 2008). Potential reservoir sandstones are expected in the syn-rift and lower post-rift successions Hashimoto et al, 2010).…”