Under-explored Palaeozoic and Mesozoic petroleum systems of the Timor and Arafura seas, northern Australian continental margin

The Timor and Arafura seas extend over a substantial portion of the northern Australian continental margin. Exploration commenced in Australian waters in 1971, resulting in the discovery of the Greater Sunrise and Evans Shoals gas fields, while the first significant test in Indonesian waters was the Abadi-1 gas discovery in 2000. This paper links the Australian gas discoveries of Greater Sunrise and Evans Shoal with the Abadi accumulation using the newly acquired Matahari MC2D seismic data, which extends into open acreage to the north and east of Abadi. This paper briefly: examines structural relationships of Palaeozoic and early Mesozoic strata that form the foundation for these gas discoveries; presents a revised distribution for Palaeozoic/ Mesozoic tectonic provinces; and discusses the potential for oil-prone source rocks of Palaeozoic and Early Cretaceous age.
To the north and northeast of Abadi, especially bordering the southeastern margin of the Tanimbar Trough, the new seismic interpretation has clarified the geology of the Palaeozoic Barakan Basin. Based on analogues with the Petrel Sub-basin and Goulburn Graben of northern Australia, it is speculated that the Barakan Basin could contain high-quality mature oil-prone Type II source rocks of Cambrian, Devonian and Permian age. In addition, deeply buried Early Cretaceous source rocks, similar to the Echuca Shoals Formation of the Browse Basin, may exist in the Malita and Calder grabens and along the southern flank of the Tanimbar Trough.