PGS Access Westralia: New insights into the Inner Browse and a look at the 2016 Offshore Petroleum Exploration Acreage Release

The PGS Access Westralia study provides new insights into the hydrocarbon potential and prospectivity of the Australian North West Shelf by offering a fresh perspective on the geological evolution of the primary underlying structures. The recent release of the 2016 Offshore Petroleum Exploration Acreage Release includes a focus on the inner rim of the Browse Basin (W16-4), which is an area where new insights can give an entirely new perspective.

Figure 1: Location map of PGS Access Westralia study & 2016 Acreage ReleaseFigure 1: Location map of PGS Access Westralia study and 2016 acreage release

Within the Browse Basin, which is part of the larger Westralia Superbasin, there are a number of smaller structural elements. The largest and best-known depocenter is the gas-rich Caswell Sub-basin which contains a number of significant gas discoveries, e.g. Prelude, Ichthys and Concerto. The W16-4 block sits on the inner rim of the main depocentre, on the edge of the Yampi Shelf basement high. There is an overall northeast-southwest structural trend that dominates the entire basin and is reflected in a previously unnamed structural feature, recently coined the “Aurora Graben”. The Aurora structure has been identified in the PGS Access Westralia study and shown in great detail with the PGS Aurora MC3D survey. 

Figure 2: Regional 2D lines showing major regional trends of the Browse BasinFigure 2: Regional 2D lines showing major regional trends of the Browse Basin

The insights offered by the PGS Access Westralia study indicate that in the W16-4 block there is a localized thickening of the oil-prone Echuca Shoals Formation, influenced by the newly identified Aurora Graben which underlies it. This Browse Basin inner rim area takes on new significance as a previously underexplored source kitchen for the generation and migration of oil. The position of this acreage on the basin margin is also optimal for the development of stratigraphically-trapped sandstones that have been deposited as turbidite flows.

 

Figure 3: Aurora Half-Graben & Inner Browse oil playFigure 3: Aurora Half-Graben & Inner Browse oil play

PGS Access Westralia is already revealing new insights into bypassed plays in time for the 2016 Offshore Petroleum Exploration Acreage Release. The PGS Access Westralia Study demonstrates the value of using an integrated study to give a new perspective to the established understanding of a classic North West Shelf petroleum play. Here, new work suggests significant potential in a new oil play fairway in an accessible, shallow water, part of the Browse basin.