| 摘要 |
This invention provides a method for enhanced oil recovery which comprises two steps. In the first step, an oil-mobilizing agent comprising (a) a gas and an alkyl aromatic sulfonate or (b) an organic solvent is injected into the reservoir formation sufficient to reduce the oil concentration in at least a portion of the formation. Then in the second injection, steam and an oil-sensitive surfactant effective in forming a steam blocking foam in formations of lower oil concentration. Preferred oil-sensitive surfactants are alpha-olefin sulfonate dimer or alpha-olefin sulfonate surfactants used to form a foam in the oil depleted portions of the formation and to assist the movement of steam and hydrocarbons through the higher oil concentration portions of the formation. The stepwise enhanced recovery method of this invention provides increased efficiency by moving the higher concentration of oil through the formation with an organic solvent or with an alkyl aromatic sulfonate, then moving the lower concentrations of oil through the formation with the steam foam comprising alpha-olefin sulfonate dimer or alpha-olefin sulfonate surfactants.
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