II II II II II - Geoscience Australia

Basins were sourced from the underlying Permian. The extensive coal deposits
present in many of the Permian basins appear to have been particularly significant in
the generation of oil and gas. The data maps show the location of representative oil
and gas occurrences by age of reservoir.
Bonaparte Basin
The Bonaparte Basin is notable for the Tern and Petrel gas fields, both currently (1989)
sub-economic. The Tern reservoirs lie at the top of the Late Permian Hyland Bay
Formation, and consist of lower shoreface zone sands (Bhatia and others, 1984). The
Petrel reservoirs occur lower down in the same formation, and were deposited as
sands in estuarine channels, tidal bars and mouth bars, within lower delta plain and
adjoining delta front platform settings. A minor gas accumulation in Penguin 1 is
present in shallow marine calcareous sandstone, at the base of the Hyland Bay
Formation (Layering & Ozimic, 1989) (top of Fossil Head Formation according to
Bhatia & others, 1984). Oil shows have been encountered in Barnett 1 in both shallow
marine limestone of the Hyland Bay Formation, and in marginal marine sandstone of
the Late Carboniferous - Early Permian Kulshill Group. Other oil shows in the KuIshiil
are known from Lacrosse 1, Turtle 1, and KuIshii! 1 (Layering & Ozimic, 1989), in
fluvial, deltaic, and shallow marine fades respectively. The best Ku[shill reservoirs are
generally restricted to the upper part of the formation and the south of the basin (Gunn
& Ly, 1989).
Canning Basin
The majority of hydrocarbon shows in the onshore portion of the Canning Basin are
bitumen and asphalt in the Grant Group (Foreman & Wales, 1981), particularly in the
shallow water glaciomarine sands of the Betty Formation, where porosities (commonly
> 20%) and permeabilities are usually highest. Exploration at this stratigraphic level
was stimulated by the oil discoveries in the West Terrace and the Sundown oil fields,
the latter producing from two quartz sandstones. Large palochannel systems exist
within the Grant Group, with interfluvial highs, and to a lesser extent, channel-form
pinch-outs, providing attractive but high-risk drilling targets (Goldstein, 1989). Potential
reservoir sands, with porosities up to 30 +%, also occur at the top of the Grant Group,
but shows at this level are rare, casting doubt on the seal quality of the overlying Nura
Nura Member, even where it contains tight carbonates, shales, and siltstones, as in
the northwest (Goldstein, 1989). The Artinskian fluvial, lagoonal, and barrier bar Poole
Sandstone , with porosities ranging to over 30%, ought to contain good reservoirs, but
the seal quality of the overlying Noonkanbah Formation is suspect, and the unit is also
stratigraphically remote from mature source rocks. Shales within the Grant Group,
Nura Nura Member, and particularly the shallow marine Noonkanbah Formation may
be source rocks (Forman & Wales, 1981); the last named consistently shows high
total organic carbon (TOO) up to 6% in the wells sampled (Burne & others, 1979).
Though some sandstones within the Noonkanbah have the potential to act as
reservoirs, organic maturity of the formation is often insuffient. However, the interval
may be mature in the eastern Fitzroy Trough and in parts of the Kidson Sub-basin
(Forman & Wales, 1981). The thermal maturation study of Nicoll & Gorter (1984)
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