The Shallow Fault Project aims to investigate the movement of CO₂ injection along and/or through the fault plane in the Port Campbell limestone reservoir. Significant efforts were dedicated to modelling the likely behaviour of the CO₂ plume around the Brumbys fault. In preparation for the injection phase in Q1 of 2024, a water pump test was completed to understand the injectivity of the injection well (Brumbys-3), pressure and hydraulic communication between the wells and to update the reservoir model with the collected data.

The pump test, completed in August 2023, provides valuable data on reservoir performance and injectivity.  Two wells, Brumbys-1 and Brumbys-3 were utilised for the injection and all four bores collected pressure, temperature and strain data during the test. Brumbys-1 is in communication with the formation through the screened interval at 98-110m, where it intersects the Brumbys fault. The screened interval of Brumbys-3 is open at 69-79m where the intended 10 tonne injection is to happen.

Visual checks through downhole camera showed that majority of the screened interval is covered by debris, hence potentially impacting the injectivity during the CO₂ injection operation. Well cleaning was performed prior and in-between the water test intervals and its impact was assessed against the injectivity performance.

The water injection adopted variable rates (50 litres/min to 150 litres/min) at Brumbys-1 where pressure analysis techniques are employed to evaluate the suitability of the reservoir for CO₂ injection. The results indicate that the injection well, Brumbys-3, exhibits suitable injectivity, suggesting its potential for successful CO₂ injection. 

As part of the study, efforts are made to update the previous understanding of the reservoir. By integrating data from the pump test, pressure analysis, and monitoring well, the reservoir model is updated. This model aids in predicting the behaviour of the injected CO₂ and assessing its potential implications. Notably, this project specifically investigates the movement of CO₂ injection along and/or through the fault plane.