LAUSR

CO2 geosequestration in oil reservoirs is an economically attractive solution as it can be combined with enhanced oil recovery (CO2‐EOR). However, the effectiveness of the associated three‐phase displacement processes has not been tested at the micrometer pore scale, which determines the overall reservoir‐scale fluid dynamics and thus CO2‐EOR project success. We thus imaged such displacement processes in situ in 3‐D with X‐ray microcomputed tomography at high resolution at reservoir conditions and found that oil extraction was enhanced substantially, while a significant residual CO2 saturation (13.5%) could be achieved in oil‐wet rock. Statistics of the residual CO2 and oil clusters are also provided; they are similar to what is found in analogue two‐phase systems although some details are different, and displacement processes are significantly more complex.