CO2 Controlled Release Experiment

A controlled-release test at the In-Situ Laboratory Project in Western Australia injected 38 tonnes of gaseous CO₂ over 4 days in February 2019 between 336−342m depth in a fault zone, and the gas was monitored by a wide range of downhole and surface monitoring technologies.

Injection of CO₂ at this depth fills the gap between shallow release (< 25 m) and storage (> 600 m) field trials.

The main objectives of the controlled-release test were to assess the monitorability of shallow CO₂ accumulations, and to investigate the impacts of a fault zone on CO₂ migration.

A mobile CO₂ tank, heater and pump were deployed to the site for the duration of the experiment.

CO₂ arrival was detected by distributed temperature sensing at the monitoring well (7m away) after approximately 1.5 days and an injection volume of 5 tonnes.

The CO₂ plume was detected also by borehole seismic and electric resistivity imaging.

The detection of significantly less than 38 tonnes of CO₂ in the shallow subsurface demonstrates rapid and sensitive monitorability of potential leaks in the overburden of a commercial-scale storage project, prior to reaching shallow groundwater, soil zones or the atmosphere.

Observations suggest that the fault zone did not alter the CO₂ migration along bedding at the scale and depth of the test.

Contrary to model predictions, no vertical CO₂ migration was detected beyond the perforated injection interval.

CO₂ and formation water escaped to the surface through the monitoring well at the end of the experiment due to unexpected damage to the well’s fibreglass casing. The well was successfully remediated without impact to the environment and the site is ready for future experiments.

See Publications for more details and results.