Mobility control during CO2 EOR in fractured carbonates using foam: Laboratory evaluation and numerical simulations

Laboratory miscible CO2 and CO2-foam injection tests were performed to study CO2 EOR in fractured carbonate core plugs and to evaluate the feasibility of using foam for mobility control in fractured systems. A significant oil recovery was observed during CO2 injections at miscible conditions ranging between 75% and 92% OOIP in cores with irreducible initial water saturation. In fractured core plugs viscous displacement was negligible and the recovery was mainly driven by diffusion. Injection of pre-generated CO2-foam accelerated oil recovery compared to pure CO2 injection in fractured core plugs, by adding a viscous displacement in addition to diffusion. A conceptual numerical model was built to study the effect of reduced fracture conductivity on oil recovery efficiency and the impact of system size and orientation on diffusion dominated oil recovery during CO2 injection in fractured systems.