Introducing the Untested Sub-Salt Play in the Officer Basin, South Australia

Boult, Peter J.¹, Clerk M. Petrick¹, Vicki Stamoulis², Kerry Deller¹ (1) University of Adelaide, Adelaide, Australia (2) PIRSA, Adelaide, Australia

The Neoproterozoic–Devonian eastern Officer Basin, South Australia, has the potential to contain several very large oil fields within horsts capped by thick salt. Oil shows are com­mon in mineral wells and some have been correlated to sub-salt source rocks. Excellent quality reservoirs are proven in nearby wells (>20% phi, > 1 Darcy) and abundant salt implies long-term preservation is feasible. Target depths are less than 1 second TWT.

The stable Murnaroo platform, which is adjacent to the Munyarai Trough containing up to 10 km of sediment, comprises over 1 km of undrilled section, including ~500 m of con­tinuous salt canopy above the aeolian Pindyin Sandstone.

Cambrian generation and migration occurred after the development of Neoproterozoic–Cambrian traps. Transpression and likely breaching of traps during the Carboniferous Alice Springs Orogeny is confined to north of the Birksgate Coober-Pedy stru­cutural corridor, which forms the boundary between the platform and trough.

Magnetotelluric methods are proving to be an effective and cheap method for mapping salt onshore due to the high resistivity contrast between highly resistive rock salt and sur­rounding very conductive saline saturated sediments. Salt diapirism is confined to the deep­er parts of the basin and is controlled by basement structure. Its movement was initiated during the late proterozoic, where infill canyoning events are mapped, and continues today where movement can be mapped on satellite images of the earths surface.