Good read!!18 Jun 2026 09:32
The Officer Basin covers an area of 320 000 km2
in Western Australia, with a Neoproterozoic sedimentary section in
excess of 6 km thick. The Gibson area, in the western Officer Basin, contains 1071 km of regional seismic data and two
petroleum wells: Dragoon 1 and Hussar 1. The sedimentary succession has a mostly uniform thickness, which gradually
thins towards the basin margin. The consistent seismic character of the Browne, Hussar, Kanpa, and Steptoe Formations
allows them to be confidently correlated from the geologically better understood Yowalga area to the Gibson area. In
these formations, the depositional facies of the Neoproterozoic succession are similar and the two regions are not
individual sub-basins, but merely sub-areas of the larger western Officer Basin. During deposition of Supersequences 3
and 4 the Gibson area was more tectonically active than the Yowalga area, subsiding at a faster rate, with halokinesis
drastically changing local geometry.
From measurements in Hussar 1 and by analogy with the Yowalga area, adequate source rock, reservoir, and seal are
present in the Gibson area. Seismic control is inadequate to define structural and stratigraphic prospects and data quality
can be improved with reprocessing. Nevertheless, a large variety of trapping styles, from simple fault traps, simple
anticlines, stratigraphic traps (depositional and erosional), and halokinetic traps are recognized. Some of these are
potentially large. In particular, large salt emplacements at different times suggest that halokinetic traps could have been
formed within the younger units. Geothermal modelling of a deep location indicates three periods of hydrocarbon
generation: during deposition of the later part of Supersequence 1, during deposition of Supersequence 3, and during
deposition of Supersequence 4. For the deepest source rock (Browne Formation), production of up to half of its generative
potential may have taken place before the major structuring phase, and accumulation would require a stratigraphic trap for
this charge. For less deeply buried source rock, the timing of trap formation is favourable with respect to generation. The
Kanpa Formation and younger source rocks have not commenced substantial petroleum expulsion.
The available data, though sparse, indicate that the petroleum potential of the Gibson area could be significant.
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