Petroleum implications of stacked deltas in the Fairway Basin, offshore New Caledonia, Northern Tasman Frontier

Abstract

The Fairway Basin lies between Australia and New Caledonia in the northern Tasman Frontier area with water depths ranging from less than 1,000–2,400 m. This basin formed in mid-to-Late Cretaceous during eastern Gondwana breakup and received detrital and pelagic sediments since that time. It is known for a 70,000 km2 bottom simulating reflector interpreted as either one of the world’s largest gas hydrate layers or as a regional diagenetic front. Seismic reflection data shows sedimentary thicknesses (up to 4 km) and geometries capable of trapping hydrocarbons. We interpret seismic stratigraphy and available well data in terms of paleogeography and tectonic evolution. This work allowed the discovery of a deeply buried delta probably of the same type as the deepwater Taranaki Delta. This stratigraphic framework is used to constrain multi-1D generation modelling and to test three main hypotheses of source rocks. The most likely scenario, similar to the one accepted for the Taranaki petroleum province, are a type-III and type-II source rocks intercalated in Cretaceous prograding series. Another possible scenario is a source rock equivalent to the East Australian Walloon Formation and occurrence of marine source rock in the pre-rift sequence. Although large modelled volumes at this stage are speculative due to limited data on source rock composition, richness and distribution, as well as on the presence and quality of reservoir and seal, this study confirms the prospectivity of the Fairway Basin and the need for more data to further assess this basin.