A RE-ASSESSMENT OF THE PETROLEUM POTENTIAL OF THE DARLING BASIN: A DISCOVERY 2000 INITIATIVE

Abstract

New data, including regional high resolution aeromagnet ic coverage, acquired by the New South Wales Department of Mineral Resources (DMR) as part of its Discovery 2000 Initiative, have provided the first opportunity for a comprehensive review of the regional framework of the Darling Basin. Covering an area of 90,000 km2 in central western NSW, the Darling Basin contains over 8,000 m of mainly Palaeozoic sediments. With only 17 petroleum wells drilled in the basin, mostly during the 1960s and 1970s, and some 1,550 km of modern multifold seismic coverage, the Darling Basin represents one of the major frontier basinal regions of onshore Australia.The initial phase of petroleum exploration was discouraged by the lack of shows, the likelihood of gas-prone source rocks and presence of a thick, red-bed dominated, organically lean, Late Devonian sequence. Renewed interest in the Darling Basin's prospectivity followed from favourable, albeit superficial, comparisons between the Darling Basin and Queensland's Adavale Basin, where commercial gas is produced at the Gilmore Gas Field. Additionally, as part of some $15 million expenditure by the DMR on acquiring new and reassessing old data from the Darling Basin, new geochemical analyses of extracts collected from core holes and out-crop suggest the presence of at least one active Palaeozoic petroleum system. This system has been responsible for generating oil and possibly substantial quantities of gas found dissolved within artesian waters in the overlying shallow Mesozoic sequences.