Patent ID: 8839865

Claim:
A method of treating a formation penetrated by a wellbore comprising: introducing a first fluid comprising a first gelling agent into the formation, wherein the first fluid has a viscosity of at least 35 mPa-s; introducing a second fluid comprising a second gelling agent into the formation in contact with the first fluid at an interface between the first and second fluids, wherein the first and second gelling agents can be the same or different, and the second fluid has a viscosity of at least 35 mPa-s; and forming a slip layer having a viscosity of less than 15 mPa-s at the interface between the first and second fluids to facilitate penetration of the second fluid through the first fluid, wherein the slip layer is formed in situ by the reaction of at least one reactant from the first fluid and at least one reactant from the second fluid.