Quantifying residual and solubility trapping of CO₂ at the CO₂CRC Otway test site

In December 2014, three researchers from the University of Edinburgh, Stuart Gilfillan, Gareth Johnson and Sascha Serno, travelled halfway around the world to Australia with the help of UKCCSRC Call 2 funding to participate in and co-lead the Otway 2B extension project conducted at the CO₂CRC Otway CO₂ injection site southwest of Melbourne. CO₂CRC is one of the world’s leading CCS research organisations. Their Otway test site, located in the rolling cow pastures of the Otway Basin and just off the spectacular coastal part of the Great Ocean Road, was established in 2003 and is one of only a handful of single-well CO₂ test injection sites in the world. This test site provides CCS researchers with the ideal conditions to run monitoring experiments to demonstrate that CCS is a technically and environmentally safe way to make deep cuts into CO₂ emissions from fossil fuel combustion.

We were lucky enough to be in Australia for 3 weeks and worked at the Otway site for two of the weeks. In the first week, the team of 10 scientists from 5 different countries injected formation water including known amounts of the noble gases (Xenon and Krypton) into the Paaratte Formation through the CO₂ injection well to characterise the noble gas behaviour in the reservoir when no CO₂ is present. The second part followed an interval of pure CO₂ and then CO₂-saturated brine injection into the reservoir. We injected CO₂-saturated formation water with Xenon and Krypton for the final residual saturation test. This was an around the clock operation and the on-site scientific team was split up into day and night shifts (from 7 am to 7 pm, and then from 7 pm to 7 am). Two scientists per shift, including Gareth and Sascha, were located at the injection well to collect water and gas samples at in situ pressure from the formation using a U-tube system, with Scottish autumn-like temperatures and with poisonous spiders and snakes for company. The three other scientists from each shift, including Stuart, had the luxury of working in a heated container to measure noble gas tracer concentrations on-site and enjoying the semi-working Australian Wi-Fi. As a result of good planning, great organisational leadership by Dr. Chris Boreham from Geoscience Australia and Mr. Rajindar Singh from CO₂CRC and excellent collaboration between the different international scientists and field operators in the shifts, the field measurements were very successful and recovered a significant portion of the injected tracers.

The geochemical interpretation of the field data from the Otway 2B extension campaign, in close collaboration with our colleagues from CO₂CRC and other research institutions in Australia, will provide us with reliable estimates of the levels of residual and solubility trapping at the Otway site. The stay at the Otway site was an ideal opportunity to further strengthen existing research collaborations between the UK and Australian CCS communities which will be beneficial in future collaborative projects. CO₂CRC secured funding for CCS projects until 2020 from the Australian Government, and new monitoring experiments at the Otway site are already planned for the upcoming years. The University of Edinburgh and the entire UK CCS community hope to be an active and leading part during these field campaigns. We would like to use the opportunity to thank UKCCSRC for providing funding for this fieldtrip.

For more information about the work CO₂CRC is doing, check https://www.co2crc.com.au.

For further details about the Otway Project, check https://www.co2crc.com.au/otway.