Release Areas NT92-1 and NT92-2 comprise 138 blocks and 133 blocks respectively, located in the northeastern part of the Bonaparte Basin, approximately 300 kilometres northwest of Darwin. The release areas overlie the eastern part of the Malita Graben, the Sahul Platform to the north, and the margin of the Darwin Shelf to the south. In this study, most of the lines from WMC's 1985 Marie Seismic Survey were used to provide a grid of about 20 x 30 kilometres over most of the two release areas. Three lines from WMC's 1987 Connie Seismic survey and two lines from ARCO Australia Limited (ARCO)'s 1972 Baldwin Bank Seismic Survey were also used to infill some detail. Twenty interpreted lines are included in the prospectivity package. Four key horizons were eventually mapped: top Cretaceous, Turonian marker, Albian/Aptian Unconformity and the Callovian ('Breakup') Unconformity. On some lines, the probable top Permian or Triassic is mapped in part, but this horizon is unreliable as there is no well control. Control for the other horizons was provided by Shearwater I, Heron 1 and Evans Shoal. The Albian/Aptian Unconformity provides a very strong regional marker at about 2 to 2.5 secs (TWT), resulting from a seismic contrast between the overlying basal Bathurst Island Group carbonates and underlying Flamingo Group sands/shales. At least five play types have been identified in the release areas. Most are associated with fault-dependent anticlines or horst blocks within the Malita Graben and Sahul Platform. This study demonstrates that in this area of nearly 23 000 square kilometres, which, by modern standards, has generally inadequate seismic coverage with relatively poor quality data, there are numerous targets remaining to the evaluated, many of which require only minimal work to be brought up to prospect status. As the region has known hydrocarbon occurrences, the results of this study indicate that Areas NT92-1 and NT92-2 should be considered to be highly prospective.
