Abstract: A stable xanthan solution with superior filterability and subterranean injectivity characteristics comprising biopolymer and a chelating agent selected from aliphatic alpha-hydroxy acids having from about 2-7 carbon atoms; aliphatic and aromatic beta-keto compounds having from about 4-9 carbon atoms; or 2- and 4-pyrones having a hydroxyl group alpha to the carbonyl and having 5 or 6 carbon atoms; said chelating agent being present in an amount of at least about 1.0 ppm of the total solution. A method of enhancing oil recovery comprising employing as a mobility control solution in oil-bearing formations a mixture of xanthan biopolymer and a chelating agent is also disclosed.

Abstract: A method of tertiary oil recovery from petroleum-containing formations at elevated temperature comprises injecting a substantially oxygen-free aqueous saline solution of water-soluble polysaccharide biopolymer treated at pH of at least 5 by the addition of alkali metal borohydride as viscosity stabilizer.

Abstract: An aqueous mobility control solution for tertiary oil recovery from saline oil fields comprises from about 200 to 2000 ppm xanthan biopolymer in the form of clean, unreconstituted fermentation broth and from about 20 to 200 ppm of a selected water-soluble polyglycol-based surfactant. A process for tertiary oil recovery which comprises the injection of the mobility control solution into saline oil-bearing subterranian formations is also disclosed.

Abstract: The preparation of citraconic anhydride by catalytic vapor phase oxidation of methyl butanols and methyl butenols.