Patent ID: 8763705
Filing Date: 2014-07-01
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: pumping a wellbore-cleaning composition into the wellbore, the composition comprising a microemulsion, the microemulsion comprising a solvent, a co-solvent, a water-wetting surfactant, a cleaning surfactant, a non-ionic surfactant, a non-ionic co-surfactant, an emulsifying surfactant and an aqueous fluid, wherein the microemulsion comprises: 10%-45% by weight solvent 10%-40% by weight co-solvent; 5%-10% by weight water-wetting surfactant; 5%-20% by weight cleaning surfactant; 1%-10% by weight non-ionic surfactant; 1%-5% by weight non-ionic co-surfactant 1%-5% by weight emulsifying surfactant; and 1%-5% by weight aqueous fluid.