Evaluation of oil foam as a displacing phase to improve oil recovery: A laboratory study

The objective of this work is to investigate the possibility of considering oil foams for practical use in the recovery of oil. To achieve this objective a multifunction laboratory setup was designed to provide capillary tube-foam viscosity measurements, selective core configuration, selective foam generation scheme, and good control of gas injection-pressure and liquid injection-rate. The porous medium was represented by a 2. ft. ×. 2. in. cylindrical Berea sandstone core with absolute permeability of 139.6. md and porosity of 23.1%. Kerosene (viscosity of 1.458. cp) and Nitrogen (specific gravity of 0.9672) were used as the liquid and gas components of the oil foam, respectively. A surfactant with code name FC-432 was used as foaming agent at a concentration of 1% by volume. The effects of imposed pressure differential, slug size of surfactant solution, and gravity on oil displacement by internally-generated foam scheme were investigated. The displacement of oil by externally generated foam was tested for three foam qualities of 70, 80, and 90% under imposed pressure differential of 15. psia. Gas drive and water flood tests were conducted for comparison purposes. Injection pressure in all tests was near 830. psia. The results of this work revealed that oil foams behave as non-Newtonian fluids with low yield stress and that their plastic viscosities increase with increased foam quality. Oil recoveries by oil foam displacement were significantly higher than those observed in gas drive and water drive tests. Vertical core configuration was found to yield higher oil recoveries than horizontal core configuration. Also higher oil recoveries were generally associated with lower imposed pressure drops, lower foam qualities, and larger slug size of surfactant solution. The mechanism of foam flow in the core was deduced from gas breakthrough, relative permeability concepts, and capillary tube model. A new iterative scheme of calculations is proposed to determine average foam saturation inside the core.