This paper presents a comparative study, based on analysis of phase behavior, compositional reservoir simulations, and slim-tube experiments, of displacement characteristics of nitrogen and methane flooding into a volatile-oil reservoir. Results show that nitrogen has the same minimum multiple-contact-miscibility (MCM) pressure as methane, provided the oil contains enough methane. When dispersion occurs, the recovery efficiency for methane is better than that for nitrogen injection. The difference between nitrogen and methane injection above the minimum miscibility pressure (MMP) decreases with increasing Peclet number values.