Experimental and Zero-dimensional Analysis of CO2-N2 Gas Cyclic Injection Processes

Abstract

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 70°F)—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.