Abstract: The injectivity of an oil-containing reservoir is increased by injecting successive portions of a solution or slightly turbid dispersion of reservoir-tailored amounts of polyalkoxyalcohol sulfate surfactant and lower alkanol in highly saline aqueous liquid and a reservoir acidizing solution.

Abstract: In a viscous 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 oil is produced. Steam is injected and fluid is produced at rates causing a steam channel to be extended between locations that are horizontally separated. A foam-forming mixture of steam, noncondensable gas and surfactant is then injected into the steam channel 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 steam channel expansion exceed those which could be provided by steam alone.

Abstract: A process for recovering oil by successively injecting at least a chemical slug containing an active aqueous surfactant system or thickened aqueous liquid and an aqueous drive liquid into a reservoir having a significant amount of ion exchange capacity, is improved. The ionic composition of each injected fluid is arranged to provide a ratio, between the concentration of its effectively predominate monovalent cation and the square root of the concentration of its effectively predominate divalent cation, which ratio at least substantially equals such a ratio within the aqueous fluid immediately ahead of the injected fluid.

Abstract: An improved aqueous anionic surfactant system for providing low interfacial tensions against oil is formed by including an aromatic ether polysulfonate in the system. This improves the tolerance of the system toward salts of monovalent and/or multivalent cations, and also causes emulsions formed between the oil and the oil-displacing system to be less viscous and less stable.

Abstract: The properties of an aqueous surfactant system for displacing oil within a permeable medium are improved by adding an aromatic ether polysulfonate to the system. This improves the tolerance of the system toward salts of monovalent and/or multivalent cations, and also causes emulsions formed between the oil and the oil-displacing system to be less viscous and less stable.