Petroleum Systems of the Perth Basin, Western Australia

Abstract

Emerging shale plays, with encouraging results at Woodada Deep 1 and Arrowsmith 2, and a new Permian gas-play at Senecio 3 have revived exploration in the Perth Basin. Locally significant petroleum production (55,769 barrels of liquid and 9.45 million cubic feet of gas in 2013) also point to significant tight-sand and shale petroleum potential in the Perth Basin. High-quality source rocks with over 2% TOC and 5 mg/g potential yields are present across the basin with Permian coal and shale predominantly gas-prone, Triassic shale oil-prone, Jurassic coal and shale both gas- and oil-prone, and Cretaceous shale oil-prone. Correlations between oil and source rock show that Whicher Range oil has a Permian source; Dongara, Erregulla, Mount Horner, and Yardarino oil are derived from Triassic source rocks; and oil from Walyering and Gage Roads wells are from Jurassic and Cretaceous sources, respectively. Petroleum system modelling of Arranoo South 1, Cataby 1, West Erregulla 1, and Whicher Range 1 indicates major Permian–Jurassic subsidence and burial in the onshore Perth Basin. Apatite fission-track data indicate regional palaeothermal events during the Cretaceous (135–56 Ma) and Tertiary (30–0 Ma), which vary locally and Cretaceous event extend up to Permian. Consequently, there are significant variations in the timing of petroleum generation across the basin. Initial estimates by US Energy Information Administration indicate tight-sand/shale oil and gas resources in Permian shales of up to 25 trillion cubic feet (Tcf) gas, and in Triassic shales up to 8 trillion cubic feet (Tcf) gas and 500 million barrels oil/condensate. Shale oil and gas exploration is at a very early stage, and more work is needed to verify these estimates as well as to include estimates for the Jurassic. By comparison, the Cretaceous is relatively thin onshore and so is unlikely to contain significant hydrocarbons. KEYWORDS: petroleum geochemistry, petroleum systems, source-rock quality, thermal maturity, Perth Basin, Western Australia.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015