this gave a fractional flow of 0 91 at standard conditions in experiments using an oil the oil was an 85 15 mixture of nujol shell sol 71 having a viscosity of 47 cp and a density of 0 83 g cm 3 weights of liquid injected and produced were continuously monitored to allow computation of average gas saturation in the experiments without oil in the experiments involving oil the amount of the oleic and aqueous phases produced were measured volumetrically at times the produced emulsions were broken by centrifuging the connate water and surfactant solutions were colored with blue and red food colors respectively and the oil was colored with a green organic dye to aid flow visualization fig2 shows average gas saturation histories for pressurecycling flow and continuous flow of the foam components through the sand pack in the absence of oil the sand pack was initially fully saturated with water in both experiments in the pressure cycle experiment typical of the process of the present invention the foam components were continuously injected with the producer shut in throughout the pressure buildup cycle when the pressure throughout the sand pack and within the simulated producing well reached 15 to 20 psig the producer was opened while maintaining the same rate of injection this reduced the pressure at the outflow end of the sand pack to substantially atmospheric pressure and propagated a wave of pressure reduction upstream of the fluid flow through the sand pack when no further decrease in the pressure was noted throughout the sand pack the producer was shut in to repeat the pressure buildup cycle the time required to conduct one complete pressure.