The rheological properties of viscoelastic surfactant (VES)-based gels prepared from a single surfactant (sodium lauryl sulfate) and mixed surfactants (cocamidopropyl betaine and sodium lauryl sulfate) are characterized and interpreted in detail with the addition of alkali. The phase diagrams were prepared to identify the gel region. These were pseudoplastic fluids with shear-thinning nature. VES fluids prepared from mixed surfactants consisting of cocamidopropyl betaine and sodium lauryl sulfate presented better rheology as analyzed. The effect of the addition of nanoparticles to this system was also studied in detail for enhancement of the thermal stability. A dynamic rheology test was also conducted to show enhancement of the storage and loss modulus with the addition of alkali and nanoparticles. A miscibility test was conducted to show the miscibility of the prepared gel with oil and water because it is one of the properties of fracturing fluid used to clean the postfractured formation.