Definition of the Beetaloo Sub-basin

Abstract

The Beetaloo Sub-basin is a 28 000 km2, completely subsurface, composite depocentre located in northern central Northern Territory and centred on the rural township of Daly Waters, ~300 km south-southeast of Katherine. The sub-basin is one of the principle depocentres of the southern McArthur Basin. It contains an interpreted 9000 m thickness of sedimentary and minor volcanic rocks assigned to the following stratigraphic groups or their equivalents: the Palaeoproterozoic Tawallah and McArthur groups, and the Mesoproterozoic Nathan and Roper groups. The sub-basin is of considerable economic interest as a potential host for unconventional and conventional petroleum resources, particularly in the uppermost Roper Group. In 2017, following industry acquisition of new seismic data and the drilling of a number of strategically positioned stratigraphic wells, the Northern Territory Geological Survey undertook a thorough geological interpretation of the sub-basin's extent using open file seismic survey data and petroleum well completion reports. This resulted in a new basin boundary that is constrained by lithostratigraphic data from 26 wells tied to stratigraphic interpretations of 96 seismic surveys.

It is important to note that this new boundary does not represent the extents of hydrocarbon potential in the region. It is a geological interpretation that represents the subsurface Mesozoic stratigraphic succession as completely as possible. Hydrocarbon plays have been identified beyond the extents of this new boundary definition.