In Carbon Capture, Utilisation, and Storage (CCUS) projects, it is crucial to understand how faults influence fluid migration behaviour. This knowledge enables the assessment of risks associated with vertical gas migration through fault zones and supports the development of effective monitoring strategies for geological storage. Experimental field data also plays a vital role in validating fluid-flow simulations in the presence of faults, helping to establish and confirm whether these features inhibit or enhance CO₂ movements. Presently, there is a lack of targeted empirical data to provide standardised guidelines. The shallow CO₂ release project at the CO2CRC Otway International Test Centre provides valuable empirical insights into how carbon dioxide flows within vertical faults.

 

The shallow controlled CO₂ release experiment has been conducted at the CO2CRC Otway International Test Centre, located in the vicinity of a known near-surface strike-slip Brumbys Fault, to simulate a CO₂ leakage scenario and monitor its migration in the subsurface. The target fault is a normal fault dipping ~70 degrees east, and it is mapped to about 25 m below the surface. The experiment involves the injection of ~16 tonnes of gaseous carbon dioxide under the fault. The geophysical program employed a variety of active and passive borehole seismic methods to provide frequent, high-resolution snapshots of subsurface changes at a relatively low acquisition cost. The obtained series of monitor vintages showed the detailed evolution of the CO₂ plume in the fault zone. The post-injection monitor indicates that the initial plume is divided into two large CO2-saturated regions, aligned with a fault, and that the gas has definitely reached the surface.