An evaluation of the oil and gas potential of the Murray Basin

This study presents organic petrological and chemical data, summarises well completion report details from boreholes drilled into the Murray Basin and evaluates the potential of finding commercial quantities of oil and gas. The epicratonic Murray Basin is an extensive on-shore depositional basin of Cainozoic age which overlies a number of infrabasins containing thickened sequences of Palaeozoic and Mesozoic sediments. Pre-Carboniferous sediments are much more strongly lithified than the younger sediments and the post- Carboniferous strata are considered non-prospective in the Darling River region. Weak hydrocarbon shows including traces of bitumen, minor oil staining core and some gas concentrations have been found during drilling investigations. Reservoir conditions exist in rocks of Middle Devonian to Early Carboniferous age and source potential is favourable for the Early Devonian and Cambro-Ordovician sequences. The subsurface extent of these sequences is poorly known. The conclusion of this study recognizes the widespread paucity of suitable organic matter to generate hydrocarbons and the lack of thermal maturation of those sediments containing appropriate source materials. At best only moderate quantities of gas and small amounts of oil are likely to be found in high risk exploration programmes. Target areas for such ventures should focus on more favourable Palaeozoic sequences in the northeastern parts of the Murray Basin and the Darling Depression.