A Multi-phase, Multi-component and Division Model for CO2 Flooding Including Diffusion Consideration in Low Permeability Reservoir

During CO₂ flooding in low permeability reservoir, the pressure of CO₂ injection will decrease from near the injection well zone to far of it. The decrease of pressure will cause three areas, miscible flooding area, immiscible flooding area and transition area in reservoir (only miscible flooding area and immiscible flooding area are considered in this paper). At the same time, diffusion will be happen between CO₂ and formation fluid. Base on the mass conservation and percolation theory, multi-phase, multi-component and division mathematical model was established. In this model, diffusion is considered in the process of miscible flooding and immiscible flooding. It is different from conventional mathematical model. Research result is meaningful for numerical simulation for CO₂ flooding in low permeability reservoir with diffusion consideration.