Patent ID: 8921285

Claim:
An aqueous fluid comprising: water; about 0.5 to about 25% by volume, based on the total aqueous fluid, of at least one amine oxide viscoelastic surfactant (VES) in an amount effective to increase the viscosity of the aqueous fluid; and based on the total aqueous fluid, from about 0.1 to about 200 pounds per thousand gallons (pptg) (about 0.012 to about 24 kg/m 3 ) of at least one particulate fluid loss control agent slurried in from about 0.2 to about 10% by volume (bv) of at least one mineral oil fluid loss control agent to give a slurry of microscopic oil droplets dispersed in the water, where all of the particulate fluid loss control agent is coated by the mineral oil in an amount effective to reduce fluid loss of the aqueous fluid, where the at least one mineral oil fluid loss control agent has a dynamic viscosity greater than 20 cps at ambient temperature, and where the at least one particulate fluid loss control agent is present in an amount effective to reduce fluid loss of the aqueous fluid, 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 at least one particulate fluid loss control agent has a particle size equal to or less than about 0.2 millimeter, where the slurried fluid loss control agents are present in amounts effective to synergistically reduce 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.