Katriona Edlmann , Sofi Hinchliffe, Niklas Heinemann, Gareth Johnson, Jonathan Ennis-King, Christopher McDermott

To meet the Paris Agreement target of limiting global warming to 2ºC or below it is widely accepted that Carbon Capture and Storage (CCS) will have to be deployed at scale. The influence of residual trapping on CO2 well injectivity and its response over time has a major impact on the injection efficiency and storage capacity of CO2 storage sites. For the first time, experiments have been undertaken over six cycles of water and supercritical CO2 injection using a state of the art high flow rig recreating in-situ conditions of near wellbore injection into analogue storage reservoir rocks. The results show that differential pressure continuously increases over multiple injection cycles. Our interpretation is that multiple cycles of injection results in a reduced effective permeability due to increased residual trapping acting as a barrier to flow resulting in reduced injectivity rates. This is supported by numerical modelling and field observations that show CO2 injectivity and its response over time will be affected by multiple cycles of injection. These results suggest that loss of injectivity must be incorporated into the injection strategy and that careful management of cyclic injection will create the opportunity to increase residual trapping.