Investigation of decane displacement mechanism during in situ supercritical CO2 injection in limestones and the study of additive performance

Carbon capture and storage (CCS) has been recognized key technology to reduce greenhouse gas emissions in an attempt to limit the effects of global climate change. Nowadays, carbon dioxide-enhanced oil recovery (CO2-EOR) has gained global attention in light of declining oil reserves. The potential of combining CO2-EOR technology with CCS has the benefits of enhanced oil recovery and permanent storage of an amount of injected CO2 in the depleted reservoir. In a previous NIMROD experiment we have examined the oil recovery at the nanoscale by injection of supercritical CO2 into a limestone sample loaded with decane. The neutron profiles showed the decane displacement as well as the structural properties of confined CO2 and the pore accessibility to CO2. It was also concluded that a large fraction of small mesopores were inaccessible, to CO2, suggesting that most of these pores are unavailable for storage for geologic CO2 sequestration. We have also observed that a total recovery was not achieved. We are now proposing to investigate if the remaining decane amount was entrapped over the limestone surfaces and through the pore throats or did not fully displaced due to the limited cell volume. Finally, the additive performance will be examined.