An effective parameter in the miscible-CO₂ enhanced oil recovery procedure is the minimum miscibility pressure (MMP) defined as the lowest pressure that the oil in place and the injected gas into reservoir achieve miscibility at a given temperature. Flue gases released from power plants can provide an available source of CO₂, which would otherwise be emitted to the atmosphere, for injection into a reservoir. However, the costs related to gas extraction from flue gases is potentially high. Hence, greater understanding the role of impurities in miscibility characteristics between CO₂ and reservoir fluids helps to establish which impurities are tolerable and which are not. In this study, we simulate the effects of the impurities nitrogen (N₂), methane (C₁), ethane (C₂) and propane (C₃) on CO₂ MMP. The simulation results reveal that, as an impurity, nitrogen increases CO₂–oil MMP more so than methane. On the other hand, increasing the propane (C₃) content can lead to a significant decrease in CO₂ MMP, whereas varying the concentrations of ethane (C₂) does not have a significant effect on the minimum miscibility pressure of reservoir crude oil and CO₂ gas. The novel relationships established are particularly valuable in circumstances where MMP experimental data are not available