Chris S. Kenyon¹
(1) Robertson Research Australia Ltd, Perth, Australia

Abstract: The petroleum systems and hydrocarbon potential of the deepwater Outer Browse Basin, Northwest Shelf, Australia

This paper describes the results of a detailed evaluation of the hydrocarbon controls of the sparsely explored deepwater portions of the Rowley and Barcoo sub-basins of the Outer Browse Basin. The work involved the interpretation of 6000 km of newly acquired 2-D seismic data and the integration of geochemical, sedimentological and stratigraphic data from some 39 wells in the adjacent shallow water areas of the Browse and Canning basins. Sequence analysis of key lines tied to wells landward of the shelf/slope break was used to predict the geometry and lithofacies for the key Triassic through Upper Jurassic part of the section containing the main potential source and reservoir intervals. Prospective reservoir targets within this sequence include extensive fluvio-deltaic sandstones of Middle Jurassic age and basal Lower Jurassic sandstone reservoirs, equivalent to the North Rankin Formation in the Beagle and Dixon Sub-basins. In addition, large anomalies associated with high amplitude reflectors are observed on the new seismic data and are interpreted as Triassic reefs or bank carbonates. These constitute a viable new play. Other new play types involve lowstand fans evident in the Cretaceous and Tertiary section. Source rock evaluation and thermal modelling have been used to establish the likely existence of a number of petroleum systems. Timing of expulsion predating trap formation appears to be one of the main reasons for failure of a number of wells in the shallow water part of the basin. Prospective traps demonstrating structural growth predating expulsion offer considerable hope in the deepwater area.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana