Foam Mobility Control for Surfactant Enhanced Oil Recovery

Summary Foam generated in situ by surfactant-alternating-gas (SAG) injection is demonstrated as a substitute for polymer drive in the alkaline/surfactant/polymer (ASP) enhanced-oil-recovery (EOR) process. Foam is also effective in a similar process for a 266-cp crude oil, even though the system did not have enough polymer for favorable mobility control. Foam is shown to enhance sweep efficiency greatly in a layered sandpack with a 19:1 permeability ratio. Foam diverted surfactant solution from the high-permeability layer to the low-permeability layer. Ahead of the foam front, liquid in the low-permeability layer crossflowed into the high-permeability layer. A layered system with a 19:1 permeability contrast could be completely swept in 1.3 total pore volumes (TPV) with foam, while waterflood required 8 pore volumes (PV).