An elemental chemostratigraphic study of the offshore Otway basin has been undertaken as part of a collaboration between Chemostrat and Geoscience Australia (GA). The main aim of which is to better constrain the sequence boundaries of, and within, the Sherbrook Supersequence. This comprehensive study includes the elemental analysis of 1185 cuttings samples from the Sherbrook Supersequence (and overlying stratigraphy) in 13 wells, located offshore Otway Basin. Sampling of cuttings for this project was particularly challenging as many of the targeted wells have a paucity of material available for destructive analysis. Lithological and well log interpretation in the basin is often inadequate for constraint of sequence boundaries. Nonetheless the use of Inductively Coupled Plasma-Optical Emission Spectrometry and Mass Spectrometry (ICP-OES and MS) analysis was undertaken to complete a regional elemental chemostratigraphic study of the Sherbrook Supersequence, Otway Basin. The resultant chemostratigraphic framework, with nomenclature adapted from Forbes et al (2020) comprises of two chemostratigraphic sequences, eight chemostratigraphic packages and seventeen chemostratigraphic units. It is important to note that in some wells the chemostratigraphic correlation differs extensively from the lithostratigraphy, highlighting areas for closer examination. From the 13 wells analysed at least three, Crayfish-1A, Copa-1 and Breaksea Reef-1, indicate necessary changes to markers for LC2 (base Sherbrook). Additionally, within the Sherbrook Supersequence, there is scope for correlation between wells despite their separation, and seismic ties can now be better constrained.
Presented at the Australian Energy Producers (AEP) Conference & Exhibition
