Bowen Basin

Basin Details and Geological Overview

The foreland, Early Permian to Middle Triassic Bowen Basin of eastern Queensland occupies about 160 000km², the southern half of which is covered by the Surat Basin. It has a maximum sediment thickness of about 10 000 metres concentrated in two north-trending depocentres, the Taroom Trough to the east and the Denison Trough to the west. Deposition in the basin commenced during an Early Permian extensional phase, with fluvial and lacustrine sediments and volcanics being deposited in a series of half-graben in the east while in the west a thick succession of coals and nonmarine clastics. Following rifting there was a thermal subsidence phase extending from the mid Early to Late Permian, during which a basin-wide transgression allowed deposition of deltaic and shallow marine, predominantly clastic sediments as well as extensive coal measures. Foreland loading of the basin spread from east to west during the Late Permian, resulting in accelerated subsidence, which allowed the deposition of a very thick succession of Late Permian marine and fluvial clastics, again with coal and Early to Middle Triassic fluvial and lacustrine clastics. Sedimentation in the basin was terminated by a Middle to Late Triassic contractional event.

Over 100 hydrocarbon accumulations have been discovered in the Bowen Basin, of which about one third are producing fields. Accumulations occur throughout the succession, but the most important reservoirs are in the Early Permian and Middle Triassic. Source rocks have been identified throughout the Permian and in the Middle Triassic and are mostly nonmarine. Proven plays comprise mostly anticlinal closures sometimes enhanced by a stratigraphic component, as well as fault rollovers. Other plays are largely untested. The Bowen Basin also has vast coal resources, with major open cut and underground coal mines in the north of the basin. Large volumes of methane gas are held at shallow depths within Permian coals in the north and has potential for coal seam methane developments.

Key References