Changes

Methods are provided for stimulation of hydrocarbon production from low permeability formations by hydraulic fracturing, '''acid fracturing''', and hydraulic fracturing followed by gravel packing in a single operation. The methods uses a first injected viscous pad made with a low concentration (such as about 10 to about 15 ppt (pounds per thousand gallons fluid)) of uncross linked polymer and provides an inexpensive and effective material to initiate and propagate the fracture and control fluid loss, followed by a second injected fluid gelled with a viscoelastic surfactant for carrying proppant or acid into the fracture. The viscosity of the uncross linked polymer is lower than that of the VES fluid subsequently pumped, requiring less hydraulic horsepower expense....[Contd]