Quantifying Residual and Dissolution Trapping in the CO₂CRC Otway Injection Site

For a wide adoption of the Carbon Capture and Storage (CCS) technology, it is essential to provide a commercial operator with a reassurance of the predictability of their proposed site for CO₂ storage through geochemical monitoring techniques. This is particular important for assessing residual and solubility trapping, which are more secure than structural trapping of free-phase CO₂. It is difficult to quantify how much CO₂ is stored by residual and solubility trapping across an entire storage site. Hence, there is a need to develop a test which can be performed at a single injection well during assessment of a potential site for CO₂ injection. CO₂CRC, one of the world-leading CCS research organisations, conducted the Otway Stage 2B Extension residual saturation test in December 2014 to determine residual trapping at their Otway test site in Victoria, Australia, using a single-well field setting. In direct collaboration with CO₂CRC and other global research institutions (CSIRO Energy, University of Melbourne, Simon Fraser University, Lawrence Berkeley National Laboratory), we use water and gas geochemistry to establish the fate of CO₂ injected into the Paaratte Formation at the Otway test site. More specifically, we study the application of oxygen isotopes and noble gases to reconstruct levels of residual trapping of CO₂.

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