Surfactant concentration for foam formation and propagation in Snorre reservoir core

A series of foam floods was conducted in an oil-free Snorre field core with C14–16 AOS surfactant and methane or Snorre field injection gas, at 90°C and 300 bar. The lowest surfactant concentration at which foam was generated in the core overlapped the cmc region. However, concentrations exceeding the cmc were required to propagate the foam through the core, independently of surfactant adsorption. Once formed and propagated, the foam could be maintained for prolonged periods of gas/liquid co-injection even at sub-cmc or zero surfactant concentrations, possibly allowing surfactant requirements to be minimized in a field application. Results of the foam floods were consistent with the surfactantʹs adsorption isotherm.