Exploration Opportunities: CO2CRC’s PPL’s 11 & 13, Otway Basin, Victoria
Kilgariff, Kieran A.
Geoscience Honours Degree, 2011
University of Adelaide
This project was undertaken to better understand unexploited opportunities for hydrocarbon and CO2 exploration in the lower Tertiary and Cretaceous formations in and around CO2CRC operating licence holdings in the Port Campbell Embayment, Otway Basin, Victoria. Three untested, tilted fault blocks between Buttress-1 and McIntee-1 were identified in the north of PPL 11 following interpretation of available seismic data across the project area.
The reflection character of the Flaxmans, Waarre and Eumeralla Formations in the fault blocks are very bright and consistent with those found in the Naylor, McIntee, Buttress and Croft gas fields before they were developed. It is currently thought that the brightness of the reflections is due to high pre-production gas saturation.
Through depth conversion an isopach map was produced and volumetric estimations were calculated to demonstrate the methane and CO2 containing potential of each fault block. Some prospects show potential to contain a higher gas in place volume than the Naylor field. Prospectivity of the fault blocks is highly uncertain because past exploration has shown the composition of formation fluid to vary considerably within a relatively small local area. The Buttress field to the south contains 80% carbon dioxide and 20% methane in the Waarre reservoir unit, and the Boggy Creek field reservoir to the southeast contains 92% carbon dioxide. In contrast the McIntee field to the north is a hydrocarbon producing field and the Naylor field, further to the south, is a depleted gas field.
Shale gouge ratio was calculated for several major bounding faults to give an indication of likely sealing capacity. A geomechanical fault stability literature review provides context to these results, which indicate whether use of these fault blocks for carbon storage experiments is viable.