Rheology and delayed micellar formation process of novel tetrameric cationic surfactant fracturing fluid

To enrich the clean fracturing fluid system with high temperature resistance, a novel tetrameric cationic surfactant (TET) was developed and used as a thickener and mixed with different concentrations of sodium salicylate (NaSal) to obtain a new clean fracturing fluid. The flow curves, thixotropy, viscoelasticity, temperature resistance property, and proppant‐suspending capacity were further investigated. The rheological study showed that the Casson model could be used to accurately describe the flow curve of TET/NaSal micelle solutions and the addition of NaSal improved the thixotropy and viscoelasticity of surfactant solution. The optimal mass ratio of TET/NaSal solution was 5/1.5 wt%, and it had good proppant‐suspending capacity. What is more, the retained viscosity of TET/NaSal (5/1.5 wt%) solution was 52.27 mPa·s after shearing at 140°C and 100.0 s−1 for 65 min, which met industry requirements (viscosity > 20 mPa·s) of viscoelastic surfactant fracturing fluids. Moreover, the combination of 10 wt% TET aqueous solution with pH value of 8.51 and 2.6 wt% salicylic acid (HSal) suspension of the same mass significantly delayed micellar formation. The four‐parameter rheo‐kinetics model can be used to fit the viscosity curves of micellar formation, which provided the rheological basis for the study of delayed viscoelastic micellar formation.