United States Patent (19) 11 Patent Number: 4,572,296 Watkins W (45
United States Patent (19) 11 Patent Number: 4,572,296 Watkins w (45. Date of Patent: Feb. 25, 1986 (54) STEAM INJECTION METHOD Primary Examiner-George A. Suchfield Attorney, Agent, or Firm-Dean Sandford; Gregory F. (75) Inventor: David R. Watkins, Irvine, Calif. Wirzbicki; Robert A. Franks 73) Assignee: Union Oil Company of California, Los Angeles, Calif. (57) ABSTRACT 21 Appl. No.: 653,027 A method is disclosed for inhibiting silica dissolution during steam injection into a formation. In the method, 22 Filed: Sep. 20, 1984 there is added to the steam, or to feedwater used to 51) Int. Cl. .............................................. E21B 43/24 generate the steam, a mixture comprising: (52) ... 166/303; 166/902 (a) a compound selected from the group consisting of 58) Field of Search .................... 166/272,303, 244 C ammonium salts of inorganic acids, ammonium salts 56) References Cited of carboxylic acids, quaternary ammonium halides, amine or substituted amine hydrochlorides, and mix U.S. PATENT DOCUMENTS tures thereof; and 3,379,249 4/1968 Gilchrist et al. ................ 166/303 X (b) a compound selected from the group consisting of 3,822,749 7/1974. Thigpen, Jr. ........................ 166/303 ammonia, salts which decompose in steam to form 3,938,590 2/1976 Redford et al. 166/272 X 4, 156,463 5/1979 Hall ..................................... 166/272 acid neutralizers or buffers having alkaline pH values, 4,222,439 9/1980 Estes et al. ... 166/272 amides of carbamic acid or thiocarbamic acid and 4,223,731 9/1980 Estes et al. .. ... 166/272 derivatives of such amides, tertiary carboxylic acid 4,475,595 10/1984 Watkins et al.
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