Abstract The Esso-Hematite Mackerel oil field, located in the Gippsland basin, Australia, is in a high-quality Paleocene sandstone section and has been delineated by four exploration wells. A pre-development structural and stratigraphic model of the field was constructed from detailed analysis of high-quality seismic data. Although very little lithologic and log-character contrast could be seen in the four wells, seismic-data quality was sufficient to break out 11 discrete depositional units, each with an apparent progradational character. The boundaries of these seismic units were then tied back into minor variations in log and core-lithology characteristics, providing depth control for the model. It was possible, therefore, to construct a detailed geologic picture, with emphasis on the vertical and lateral extent of facies distribution, petrographic character, and reservoir properties, in a reservoir which initially appeared to be massive and homogenous, and generally ambiguous in its stratigraphic position in the depositional framework of the surrounding area. Development well results have provided feedback to the model, which is being continuously updated.