Fracturing/gravel packing tool system with dual flow capabilities

A fracturing/gravel packing tool system with dual flow capabilities. A method of treating a well includes the steps of: flowing a fluid into the well through a work string while simultaneously flowing another fluid into the well through an annulus; and directing each of the fluids to the exterior of a well screen in the well. A well treatment system includes a slurry and a fluid flowed into a well. The slurry has an initial density, but the fluid is mixed with the slurry in the well, thereby causing the slurry to have a reduced density in the well. Another method of treating a well includes the steps of: installing a gravel packing assembly including a well screen in the well; flowing a slurry and a fluid into the well; mixing the slurry with the fluid, thereby reducing a density of the slurry in the well; and flowing the reduced density slurry about an exterior of the well screen.