Patent ID: 7967068

Claim:
A method for reducing fluid loss of an aqueous fluid gelled with a viscoelastic surfactant (VES) comprising adding to the aqueous fluid in any order: at least one VES in an amount effective to increase viscosity of the aqueous fluid; and at least one particulate fluid loss control agent slurried in at least one mineral oil fluid loss control agent, where the at least one mineral oil fluid loss control agent has a dynamic viscosity greater than about 20 cps at ambient temperature, and where the at least one particulate fluid loss control agent is selected from the group consisting of alkaline earth metal oxides, alkaline earth metal hydroxides, transition metal oxides, transition metal hydroxides, and mixtures thereof, where the fluid loss control agents are present in amounts effective to reduce the fluid loss of the gelled aqueous fluid, the method further comprising synergistically reducing the viscosity of the gelled aqueous fluid as compared to using the mineral oil fluid loss control agent or the particulate fluid loss control agents independently.