Patent ID: 8143197
Filing Date: 2012-03-27
Classification: C09K

Abstract:
1. Method for recovering hydrocarbons comprising: providing an aqueous viscoelastic fracturing fluid comprising a viscoelastic surfactant and a hydrophobically-modified polymer wherein the concentration of the hydrophobically-modified polymer is not less than, approximately, its overlap concentration c* when measured at 25° C., and injecting said fluid into formation rocks in order to fracture said rocks, wherein the injected fluid forms a gel with viscosity greater than the viscosities of the surfactant and the polymer but thereafter while in the formation rocks the gel remains responsive to contact with hydrocarbons until such contact occurs and the gel is broken down on mixing with hydrocarbons; wherein the fluid breaks down under downhole conditions, on contact or mixing with hydrocarbons, so as to have a viscosity of less than 20 cP in less than 2 hours.