METHOD FOR INCREASED OIL RECOVERY

摘要

By means of the invention a process is provided for increasing the recovery of oil from an oil bearing underground formation which contains naphthenic acid or stoichiometrically equivalent naphthenate or naphthenic acid-lye extract in a concentration of C0 in the formation water, wherein C0 is less than a maximum value Cmax which underground formation is penetrated by one or several injection wells and on or several production wells, whereby water which may have been retreated is injected continuously or in portions into one or several of the injection wells and oil being produced from one or several of the production wells, distinguished in that into the injection water naphthenic acid or stoichiometrically equivalent naphthenate or naphthenic acid-lye extract is mixed in an amount yielding a stoichiometrically equivalent concentration of naphthenic acid in the injection water in the range from more than C0 to the highest value selected among the solubility limit of naphthenic acid or said equivalents in the injection water and the maximum amount of naphthenic acid or said equivalents which is capable of being emulsified in the injection water. The invention also comprises a plant and a concentrate for carrying out the process.