Controlled CO2 release experiment into Brumbys Fault: fault characterisation

In early 2024, a novel field trial will be conducted at the CO2CRC Otway International Test Centre, in which a small volume of CO2 will be injected into a shallow fault and monitored using various techniques. The planned experiment is designed with the goal of better understanding how a CO2 plume might interact with shallow faults about a CO2 storage reservoir, and also develop monitoring strategies that can help provide assurances to stakeholders and the public regarding future CCS projects. The experiment will occur in the Port Campbell Limestone sequence, which is a Miocene aged carbonate sequence that outcrops over much of southern Victoria.

The fault involved with the 2024 injection test has been named Brumbys Fault, and was identified in 2016 from a high resolution shallow seismic survey. The fault extends from the surface down to about 450 m, and can be traced for about 1 km laterally. In 2019, two wells were drilled (Brumbys 1 and 2) with the purpose of detailed data collection on the fault and surrounding rock (geomechanical, resistivity, geochemical) so that accurate modelling and planning could be conducted for the controlled release experiment. This paper details the properties of the fault and surrounding lithologies and presents results of dynamic simulations performed in advance of the experiment.