This invention relates to fluid compositions used in treating a subterranean formation. In particular, the invention is aqueous wellbore treatment compositions which are foams containing a viscosifying agent, a foam extender, a gas component, and a surfactant, as well as methods of forming such fluids, and uses thereof. The viscosifying agent may be a hydratable polymer, viscoelastic surfactant, or heteropolysaccharide. The foam extender may be a material such as a polyoxyalkyleneamines, ethylenepolyamines, tertiary polyamines, bicarbonate, carbonate, phosphate, or sesquicarbonate.