Experimental investigation of rheological properties in zwitterionic-anionic mixed-surfactant based fracturing fluids

Zwitterionic-anionic mixed surfactant systems offer synergistic interactions in aqueous medium due to polymorphism of self-assembly structures that have combined properties of surfactants in the mixture. In this paper, a comparative study is done on rheological properties of Viscoelastic Surfactant (VES) based fracturing fluids (FF) developed from CAPB+NaOA/iso‐amyl alcohol/clove oil/water and CAPB+SDS/iso‐amyl alcohol/clove oil/water systems. Static and dynamic rheological tests indicated superior viscoelastic properties of the former system (26% and 28% C/S) at a relatively low %C/S in contrast to the latter system (28% and 30% C/S). The addition of alkali (0.1% NaOH) and SiO2 nano-particles in the fluid further intensified the viscoelastic properties. The 0.1% SiO2+0.1% NaOH+28% C/S VES fluid developed from CAPB+NaOA/iso‐amyl alcohol/clove oil/water offered good apparent viscosity stability for 120 min at 103 °C and 100 s−1 under different test pressures (2068, 4137 and 6205 KPa) that is suitable for conducing fracturing job and to suspend proppants. Unlike in diesel oil, the miscibility test evidenced solubility of the VES fluids in water. These VES fluids provided satisfactory proppant suspension capabilities in the presence of three proppants (20/40 mesh size) at different test temperatures (70-100 °C).