Salt tectonics in the Officer Basin: implications for trap formation and petroleum exploration

Abstract

The Neoproterozoic Officer Basin in Western Australia is an inland frontier area that covers about 300 000 km² in Western Australia and 225 000 km² in South Australia. The present-day structural?stratigraphic framework is dominated by salt deformation and associated features. In the central western Officer Basin, approximately 6500 km of 2D seismic data were recently reinterpreted and integrated with potential field regional datasets. This has led to improved understanding of the halokinetic evolution and the petroleum potential of the region, summarised herein. Compressional processes, associated with tectonism in the adjacent Paterson Orogen, are probably the key mechanism initiating multi-phase mobilisation of a thick halite-dominated sequence, the Browne Formation, low in the succession. Significant salt redistribution resulted in thickness variations of the Browne Formation and the overlying section, and a variety of halokinetic structures. Prospective structures caused by salt tectonics include drape folds with a potential for multiple pay, thrustrelated anticlinal features, combined traps at diapir flanks and enhanced porosity traps. Most of these traps were in place before the main phases of hydrocarbon generation and could form attractive petroleum exploration targets.