Abstract
Gas-oil foam has been; observed at reservoir conditions in microvisual experiments, created in laboratory corefloods, and shown to have been responsible for CO2 and N2 mobility reduction in experiments.
Gas-oil foam can increase oil recovery, since gas mobility is reduced without a reduction in oil mobility. It occurs when oil spreads between water and gas, and oil wets solid surfaces. The surfaces may be oil wet, be wet as surfactant partitions into oil, or when a surfactant is used below its Critical Micelle Concentration (CMC).
An oil bank is more mobile than injected brine, so oil soluble surfactants move ahead of aqueous components. Modeling suggest that gas-oil foam improves oil production in a reservoir, because surfactant in the oil rises to the oil bank at the top of a reservoir, where water mobility is too low for surfactant transport.
