Experimental and zero-dimensional analysis of CO2-N2 gas cyclic injection processes

This study investigates the influence of dominant mechanisms in the cyclic injection of a CO2 and N2 process through laboratory experiments. A PVT cell was used to perform six cycles of injection at typical conditions found in shallow depleted oil reservoirs (150 psig and 70F)the prime reservoir candidates for gas cyclic injection. These conditions are kept for five different injected mixtures, said 100%-0%, 80%-20%, 53%-47%, 20%-80%, and 0%-100% of CO2 and N2 respectively. Experimental results are presented to reveal the mechanisms taking place during this process. A zero-dimensional model, based on a tuned cubic EOS, is proposed to successfully predict a component's trend through all cycles and observed experimental compositions in both phases.