The method feeder for gravel packing wells having a long interval

Change of concentrations of brine gravel pack carrier fluid gelled with a viscoelastic surfactant (VES) fluid increases the efficiency of gravel packing of wells with long intervals, such as wellbore producing interval greater than about 100 feet (about 30 m) VES-gelled fluids used as gravel packing fluid herein includes surfactants , fluid loss control agents, internal switches and brine in addition to gravel. Viscoelasticity of the fluid system can suspend and deliver the high concentration of gravel while reducing carrier fluid volume.