Patent ID: 8517100
Filing Date: 2013-08-27
Classification: C09K

Abstract:
1. A method for cleaning a section of a wellbore prior to a cementing operation, the wellbore having a casing suspended therein, and containing or having been treated with an oil- or synthetic-base drilling fluid, the method comprising the pumping of a single-phase Winsor IV-type microemulsion spacer into the wellbore, the microemulsion comprising: 5%-45% by weight solvent; 5%-45% by weight co-solvent; 1%-5% by weight water-wetting surfactant mixture or non-ionic surfactant; 1%-25% by weight co-surfactant; 1%-10% by weight oil-solubilizing surfactant; and 5%-30% aqueous fluid, wherein the co-surfactant in the microemulsion is a blend of linear sodium dodecylbenzenesulfonate and branched sodium dodecylbenzenesulfonate.