Surfactant blends for well operation

A method for formulating a surfactant composition having a predetermined solubilization parameter of oil and water and wherein the surfactant composition consists essentially of a first surfactant selected from the group consisting of alkyl polyglycosides containing alkyl groups containing an odd number of carbon atoms from about 9 to 13 carbon atoms, a second surfactant selected from the group consisting of alkyl polyglycosides containing alkyl groups containing from about 12 to about 18 carbon atoms and a third surfactant selected from the group consisting of linear alkyl ethoxylated alcohol surfactants containing from about 8 to about 12 carbon atoms in the linear alkyl alcohol and from about 2.5 to about 8 ethylene oxide groups, comprising the steps of:

• (a) determining the concentrations of the first surfactant, second surfactant, and third surfactant which will provide the predetermined solubilization parameter in a selected oil/water system by mixing a known volume of oil together with a known volume of a solution of surfactant composition and one of water or brine, measuring the volume of a type III microemulsion occupying a volume previously occupied by the oil and measuring the volume of said microemulsion previously occupied by the water or brine in surfactant solution;
• and
• (b) varying the concentrations of the first, second and third surfactants, respectively, in the solution and repeating step (a) until the predetermined solubilization parameter value is provided in a range of concentration of the first surfactant, second and third surfactant which forms the Type III microemulsion.