Geological characterisation of the Early Permian shalegas reservoirs of the Cadda Terrace, northern Perth Basin, Western Australia

Sedimentological and geochemical characterisation of Early Permian shale-gas reservoirs on the Cadda Terrace (northern Perth Basin) in the Carynginia Formation and Irwin River Coal Measures has identified four facies associations representing a shoreface to coastal plain depositional setting. Illite and mixed-layer illite/smectite are the dominant clay minerals in the shales. Source rock evaluation indicates dominant Type III organic matter and that both formations are in the immature-mid oil-dry gas window for hydrocarbon generation. K-Ar and Rb-Sr dating of authigenic illite identified several thermal events related to rifting, notably during the Late Triassic and Early Jurassic Synrift II phase.