Definition of Basin Phases in the Petrel Sub-basin (Australia): Implications for the Development of Palaeozoic Petroleum Systems

J. E. Blevin, J. B. Colwell, J. M. Kennard, D. S. Edwards, P. J. Jones, and R. S. Nicoll

An study of the Petrel Sub-basin (Bonaparte Basin) on Australia's northwest margin has identified seven main phases of basin development spanning the Early Cambrian to Tertiary. Each phase was initiated and terminated by distinct, primarily tectonic events that have controlled the structural and stratigraphic evolution of the basin and the development petroleum systems. These phases include periods of major extension (Ear Cambrian, Middle Devonian to early Carboniferous) and compression (Early Devonian, mid-Triassic), as well as rapid and slow subsidence phases in the Early to Late Carboniferous and Late Carboniferous to Triassic, respectively. Basin inversion in the mid-Triassic has been critical in controlling the development of broad anticlinal features that presently eservoir the large but as yet undeveloped gas/condensate fields Petrel and Tern. An earlier period of minor compression during the late Carboniferous initiated limited movement of Palaeozoic salt within the deeper basin, forming salt-core low amplitude anticlines in the predominantly carbonate Tanmuri Formation, a play which remains untested. In the southern Petrel Sub-basin early phases of hydrocarbon generation and fluid migration associated with salt movement are poorly understood. Preliminary results of geochemic studies indicate that there are at least two oil families in Devonian arn Carboniferous reservoirs. This suggests multiple source intervals within the deeper flanks of the basin, thus the understanding of sedimentation during early basin phases may be critical in evaluating etroleum systems.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California