A Stratigraphic Study of the Crayfish Group in the Penola Trough, Otway Basin

Abstract

The Otway Basin is a northwest-striking, rifted passive continental margin located along the southern margin of the Australian continent. The Early Cretaceous Crayfish Group in the Penola Trough, Otway Basin was deposited as part of the early syn-rift graben-fill succession overlying the Late Jurassic to Early Cretaceous Casterton Formation. Commercial volumes of hydrocarbons have been produced from formations within the Crayfish Group. However, correlation of the Crayfish Group stratigraphy across the Penola Trough has been difficult due to lateral facies variations, significant faulting and variable quality seismic data. A multidisciplinary approach has been applied in this study towards developing a better understanding of the lateral extent, and relationships between the Crayfish Group formations in the South Australian and Victorian sections of the Penola Trough. Results from an analysis of the formations; through a workflow which included core logging, palynostratigraphy, wireline logging and seismic stratigraphic interpretation, have provided a comprehensive overview of the connectivity between formations, as well as an improved understanding of the palaeogeographic environment at the time of deposition. The application of a sequence stratigraphic framework to the Crayfish Group has enabled a new way of interpreting the temporal and spatial characteristics of the formations, as well as the key surfaces between the assigned depositional system tracts. The results from this study allow for a new approach to defining the stratigraphy of the Crayfish Group formations, providing a platform for future exploration and reservoir development in the Penola Trough.

AAPG Datapages/Search and Discovery Article #90217 © 2015 International Conference & Exhibition, Melbourne, Australia, September 13-16, 2015