New insights into the deep-water Otway Basin – Part 3. Petroleum system modelling

Abstract

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 represents an established hydrocarbon province with mostly onshore and shallow-water offshore discoveries. However, the outboard deep-water Otway Basin, with water depths up to 6300m, is comparatively underexplored and can be considered a frontier area. Following the completion of a basin-wide seismic depth-imaging program (Part 1) and insights from the revised seismic interpretation (Part 2), we have developed a comprehensive petroleum system modelling (PSM) study by integrating these data and findings (Part 3). Together, the studies have resulted in an improved understanding of the hydrocarbon prospectivity of the deep-water areas of the basin. Given the sparsity of data outboard, almost all legacy PSM studies have been focused either on the onshore or shallow-water areas of the basin and primarily on their thick Lower Cretaceous depocentres. The limitations of legacy seismic datasets resulted in a high degree of uncertainty in the derivative interpretations used as input into PSM studies. In addition, the paucity and poor quality of data in the deep-water area reduced confidence in the understanding of the basin evolution and spatial distribution of depositional environments through time. The newly acquired 2D seismic survey and reprocessed legacy data, with calibration via several wells across the basin, have improved confidence in our understanding of the tectonostratigraphic evolution of the basin (Part 2). The study presented herein integrates products from the work in Part 2 into a petroleum system model with the primary objective being to better understand the petroleum systems across the deep-water Otway Basin.