Process for recovering oil from a subterranean reservoir by means of injection of steam

Abstract From the Canadian patent

In an oil reservoir in which the stratification of the rock permeability is insufficient to confine steam within the most permeable strata, oil can be produced by forming and expanding a steam channel through which steam is flowed and from which oil is produced. Steam injection into the channel is then replaced by the injection of a foam-forming mixture of steam, noncondensable gas, electrolyte and surfactant to provide foam and a relatively high pressure gradient within the channel, without plugging the channel. A flow of steam-containing fluid through the steam channel is continued in a manner such that the magnitudes of the pressure gradient, the rate of oil production and the rate, of …