GB1441710A - Oil recovery process - Google Patents

Abstract

1441710 Secondary recovery from wells TEXACO DEVELOPMENT CORP 8 May 1974 20273/74 Heading E1F Oil is recovered from a reservoir containing water having at least 1,500 ppm of polyvalent ions dissolved therein by injecting, through an injection well, an aqueous solution containing a first anionic surfactant selected: from alkyl sulphonates containing from 5 to 25 carbon atoms, alkyl aryl sulphonates wherein the alkyl constituent contains from 5 to 25 carbon atoms, and petroleum sulphonate; and a second anionic surfactant comprising a water soluble salt of an alkyl polyethoxy sulphate containing from 1 to 10 ethoxy groups and wherein the alkyl constituent contains from 7 to 20 carbon atoms. Preferably the aqueous solution contains a nonionic surfactant selected from polyethoxylated alkylphenols having from 6 to 20 ethoxy groups and wherein the alkyl constituent contains from 5 to 20 carbon atoms, polyethoxylated aliphatic alcohols containing from 5 to 20 carbon atoms in the alcohol moiety and from 6 to 20 ethoxy groups, fatty acid dialkanolamides and fatty acid monoalkanolamides, the fatty acid containing from 5 to 20 carbon atoms. The concentrations of the first and second anionic surfactants and the non-ionic surfactant are from 0.05-5.0% by weight. The ratio of the concentrations of the first and second anionic surfactants is from 1:4 to 4:1 and the concentration of the first anionic surfactant to that of the nonionic surfactant is 1 to 8. The viscosity of the solution may be increased by known polymers.