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A comprehensive examination of the hydrocarbon charge and formation water history of the central Vulcan Sub-basin, Timor Sea has been completed and a model developed to describe the evolution of the region’s petroleum systems. Reservoir horizons within the Mesozoic pre-, syn- and post-rift megasequences have been evaluated for their ability to host and retain oil and gas through a period of tectonic upheaval, associated with oblique plate collision in the Neogene. A coupled hydrocarbon-formation water model has been developed that describes two discrete formation water phases (W1 and W2) and three hydrocarbon phases (H1, H2, H3), with the timing of these events linked to important phases in the basin evolution.The Vulcan Sub-basin contains the components required to produce an effective petroleum system. The principal clastic reservoirs generally exhibit good porosity and permeability and are capped by effective, regionally extensive, seal rocks. A consistent paragenetic sequence can be recognised for Mesozoic reservoirs with early glauconite and pyrite phases preceding clay authigenesis. These early phases are in turn enclosed by quartz overgrowths that are subsequently enclosed by ankerite cement and in more deeply buried samples, filamentous illite. Source rocks are suitably located adjacent to these reservoirs, are organically rich and have experienced sufficient burial to promote thermal maturation and expulsion of generated hydrocarbons.The novel Grains with Oil Inclusions (GOI) fluid inclusion technique that allows the abundance of oil-filled fluid inclusions to be related to the maximum level of oil saturation experienced by a sandstone reservoir through time has been used to describe the charge history of a selection of wells from across the Vulcan Sub-basin. GOI data shows that the source rocks have been extremely productive, with three discernible hydrocarbon charge events recognised (H1, H2 and H3). An early gas charge (H1) appears to be widespread in th