Gas EOR Project 3: Novel Concepts of Fluid Mobility Control for CO2 Flooding

Primary Investiagors: Quoc Nguyen, Gary Pope

CO2 injection is being widely applied for enhanced oil recovery (EOR). However, this process frequently suffers from fingering and channeling of CO2 in heterogeneous and naturally fractured formations, and the inefficient displacement of oil in reservoirs with pressure below the minimum miscibility pressure (MMP). We have developed a novel concept of surfactant-stabilized CO2 foam that enhances the reservoir conformance of both CO2 and surfactant. In this concept, strong foam is expected to form in fractures and depleted zones where it diverts CO2 and surfactant to oil-rich zones. The surfactants are soluble in CO2 and can be injected in the CO2-rich gas phase. Surfactant will transport with gas directly to high-permeability depleted zones rather than slumping with water toward the bottom of the reservoir. Robust foam propagation can re-pressurize a reservoir up to MMP while optimized injection of low temperature CO¬2 can lower CO2 MMP. A parallel program of modeling and experiments is used to evaluate this concept. Experiments in parallel with computational methods are used to tailor low-cost surfactant structures for mobility control, as well as for understanding of MMP modification by optimum temperature gradient and injection strategies. CO2-surfactant process simulations are used to evaluate the process for specific field conditions.