The Otway Basin is a broadly northwest-southeast trending basin and forms part of a rift system that developed along Australia's southern margin. It is an established hydrocarbon province with onshore and shallow-water offshore discoveries. The outboard deep-water Otway Basin, with water depths ranging from 500 m to 6300 m, is comparatively underexplored and considered a frontier area. Following the completion of a basin-wide seismic program in 2020 and insights from revised regional seismic interpretation, we undertook a comprehensive petroleum system modelling (PSM) study, integrating these data and findings. The modelling results indicate that hydrocarbon generation is mainly controlled by burial of Upper Cretaceous intervals (Shipwreck and Sherbrook supersequences), especially in the deep-water areas of the basin where generation is predicted to have ceased at the end of the Cretaceous. Towards the southeast, source rocks are generally shallower at present-day, and this part of the basin was also less affected by Late Cretaceous erosion, resulting in greater post- Cretaceous hydrocarbon potential. There are several areas across the basin where modelled generation from Upper Cretaceous source rocks occurred during the Cenozoic. These are located 1) in the far outboard areas of the study area where isolated Cenozoic depocenters exist, and 2) in tilted fault blocks closer to the current shelf edge where they are positively influenced by the late burial of the Heytesbury and Whalers Bluff supersequences. In the deep-water part of the basin, where postulated source rocks are overmature prior to seal effectiveness, model results still predict hydrocarbon potential due to the modelled slow migration of hydrocarbons through mud-dominated intervals, charging potential traps later when seals are effective. The regional PSM study represents a framework for improved understanding of the dynamic evolution of the Otway Basin and its complex thermal and charge history. Model refinements and additional sensitivity analyses should enable play elements to be better defined.

Open-Access Online Publication: May 29, 2023