Source rock and maturation characteristics of the sedimentary sequence of the Otway Basin, Australia

The Otway Basin is one of several extensional basins along the southern margin of Australia. These basins developed in the Late Jurassic to Early Cretaceous before the breakup of eastern Gondwanaland. The Otway Basin is located to the west of the Gippsland Basin which contains large reserves of hydrocarbons. In the Otway Basin, only three small commercial gas accumulations have been discovered to date, in spite of extensive exploration. Organic petrological methods yield information on abundance, composition and maturity of organic matter in sedimentary rocks. This information enables assessment of hydrocarbon source potential. The Otway Basin contains a succession of Mesozoic to Tertiary sedimentary rocks up to 10km thick, comprising a ?Late Jurassic to Early Cretaceous synrift sequence and a Late Cretaceous to Tertiary post-breakup sequence.